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Products => Test Equipment => Topic started by: Amysmith on July 28, 2017, 05:16:02 am

Title: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Amysmith on July 28, 2017, 05:16:02 am
I looking very cheap FY6600 arbitrary waveform signal generator on ebay, the sine wave support 30Mhz, 50MHz, 60MHz on different models, and  arbitrary waveform to 10MHz.
with voltage control output function.

http://www.ebay.com/itm/FeelTech-FY6600-2-CH-DDS-Function-Arbitrary-Waveform-Pulse-Signal-Generator-VCO-/263105160109? (http://www.ebay.com/itm/FeelTech-FY6600-2-CH-DDS-Function-Arbitrary-Waveform-Pulse-Signal-Generator-VCO-/263105160109?)

Only 90.79 USD for 30HMz, so I'm thinking buying one.
Does anybody on this forum have experience with the FeelTech FY6600 function generator?

(http://i.ebayimg.com/images/g/MUkAAOSwPbBZdrS3/s-l1600.png)

Who has bought this FY6600?
How accurate and reliable is it?

I will grateful for any suggestion from all. :-+ :-+ :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on July 28, 2017, 08:37:20 am
I guess this is a beefed up version of the older models. The price is pretty sweet though for a 60MHz function generator! I'm wondering what the TTL outputs can be used for. Digital pattern generation would be nice.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 05, 2017, 01:42:36 am
Interesting unit. I see that, apart from the upper limit of the sine wave output, there appears to be no functional difference between the 30MHz unit and the 60MHz one (25MHz square wave and 10MHz for all others). Has AM/FM/ASK/PSK/FSK/VCO and AWG capability. Would be nice to see a comparison of this with the JDS unit.

My old analog Wavetek does AWG... you just have to hit it hard enough. Time for a new unit, I think.  ::)

PS: Here is the FY6600 Manual, in case anyone is interested: http://kenswu.zzvps.com/Function/Manual/FY6600%20Series%20Users%20Manual%20V2.2.pdf (http://kenswu.zzvps.com/Function/Manual/FY6600%20Series%20Users%20Manual%20V2.2.pdf)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 05, 2017, 07:22:58 pm
Has anyone checked what voltage(s) the internal power supply provides to the rest of the system? I am fairly interested in this model, but I have issues with using Chinese budget power supplies on mains. I am just not comfortable with that. Maybe that upgrading the power supply to something trustworthy could soothe my worries.

If there is no easy way to upgrade the power supply, I might order the competing JDS6600 instead. That uses a 5V plug-pack that is easily swapped for a trustworthy supply.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: MadTux on August 05, 2017, 08:01:53 pm
There is already a teardown available on youtube:
https://youtu.be/LNBX3yrp5ps?t=1m43s (https://youtu.be/LNBX3yrp5ps?t=1m43s)
Test from the same guy:
https://www.youtube.com/watch?v=hKgg8y5K0ls (https://www.youtube.com/watch?v=hKgg8y5K0ls)

IMO just the classic chinese plastic box with a minimal amount of electronics inside.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 05, 2017, 10:10:45 pm
Has anyone checked what voltage(s) the internal power supply provides to the rest of the system? I am fairly interested in this model, but I have issues with using Chinese budget power supplies on mains. I am just not comfortable with that. Maybe that upgrading the power supply to something trustworthy could soothe my worries.
I just noticed the mechanical switch on the back. The option to switch the unit off properly changes the proposition a little bit, as you can actually turn the supply completely off when you are not around. However, I would still rather see a plug-pack powered device.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 06, 2017, 12:06:51 am
Has anyone checked what voltage(s) the internal power supply provides to the rest of the system? I am fairly interested in this model, but I have issues with using Chinese budget power supplies on mains. I am just not comfortable with that. Maybe that upgrading the power supply to something trustworthy could soothe my worries.

If there is no easy way to upgrade the power supply, I might order the competing JDS6600 instead. That uses a 5V plug-pack that is easily swapped for a trustworthy supply.
Going by the teardown video, the PSU looks reasonable and fairly straightforward if you want to replace with your own. Its on its own separate board with lots of extra internal space. Looks like two, maybe three, different output voltages.

EDIT: Looking at the video its 6 lines, 2 X 5V, 2 X GND, 2 X 12V.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 06, 2017, 01:59:16 am
EDIT: Looking at the video its 6 lines, 2 X 5V, 2 X GND, 2 X 12V.
Good eye. I looked for markings on the main board, but missed the voltages on the power board.

Those are very convenient voltages. There are plenty of power supplies available with those, including ATX and other PC power supplies. The trick is to find one that fits neatly into that box.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 06, 2017, 03:30:04 am
EDIT: Looking at the video its 6 lines, 2 X 5V, 2 X GND, 2 X 12V.
Good eye. I looked for markings on the main board, but missed the voltages on the power board.

Those are very convenient voltages. There are plenty of power supplies available with those, including ATX and other PC power supplies. The trick is to find one that fits neatly into that box.
Its only my speculation from what I could see on the video. I'll probably order one sooner rather than later and can post up a review... when it arrives.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: StillTrying on August 06, 2017, 11:44:32 am
Is it just me that thinks  00'010.000'000'000KHz  is a horrible way to show 10kHz. Does it need to be shown to 1 millionth of a Hz ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on August 06, 2017, 01:03:57 pm
If you hang a while, there will more then likely be another similar unit launched by another company in China (Minghe) that will do away the SMPS and its associated possibility of high voltages on the ground of the BNC and USB sockets by using a 5VDC wall wart to feed the unit.  Its smaller less powerful cousin 20Mhz or 25Mhz has been tested and people have noticed tingles when using them. I have a Minghe MHS-5200A that uses the 5vdc wall wart, no problems with that at all.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on August 06, 2017, 01:16:14 pm
It seems that there is another unit already on Ebay that goes upto 40Mhz but with a wall wart, here's the link http://www.ebay.co.uk/itm/24-25-30-40MHz-Dual-channel-DDS-Arbitrary-Waveform-Function-Signal-Generator-Kit/172775654978?_trksid=p2481888.c100651.m4497&_trkparms=aid%3D777001%26algo%3DDISCO.FEED%26ao%3D1%26asc%3D20160801204525%26meid%3D87253c69a4d8403598de045c372b2e6f%26pid%3D100651%26rk%3D1%26rkt%3D1%26&_trkparms=pageci%253Aa06cd29b-7aa8-11e7-afd3-74dbd180fb11%257Cparentrq%253Ab7ab21da15d0aa48d8bc3de8fffcbe6c%257Ciid%253A2 (http://www.ebay.co.uk/itm/24-25-30-40MHz-Dual-channel-DDS-Arbitrary-Waveform-Function-Signal-Generator-Kit/172775654978?_trksid=p2481888.c100651.m4497&_trkparms=aid%3D777001%26algo%3DDISCO.FEED%26ao%3D1%26asc%3D20160801204525%26meid%3D87253c69a4d8403598de045c372b2e6f%26pid%3D100651%26rk%3D1%26rkt%3D1%26&_trkparms=pageci%253Aa06cd29b-7aa8-11e7-afd3-74dbd180fb11%257Cparentrq%253Ab7ab21da15d0aa48d8bc3de8fffcbe6c%257Ciid%253A2)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 06, 2017, 02:33:22 pm
If you hang a while, there will more then likely be another similar unit launched by another company in China (Minghe) that will do away the SMPS and its associated possibility of high voltages on the ground of the BNC and USB sockets by using a 5VDC wall wart to feed the unit.  Its smaller less powerful cousin 20Mhz or 25Mhz has been tested and people have noticed tingles when using them. I have a Minghe MHS-5200A that uses the 5vdc wall wart, no problems with that at all.

That's the JDS6600 which has the wall wart, already a thread or two on it in the forum. It appears to be 12 bit rather than 14 and have no modulation capabilities. The internal PSU on the FY6600 seems to have changed a little from the ones used in the FY3224S with at least the inclusion of an X-class cap. But its probably the crappy xformer leaking the AC onto the ground. I like the physical buttons on the JDS.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on August 06, 2017, 04:01:02 pm
If you hang a while, there will more then likely be another similar unit launched by another company in China (Minghe) that will do away the SMPS and its associated possibility of high voltages on the ground of the BNC and USB sockets by using a 5VDC wall wart to feed the unit.  Its smaller less powerful cousin 20Mhz or 25Mhz has been tested and people have noticed tingles when using them. I have a Minghe MHS-5200A that uses the 5vdc wall wart, no problems with that at all.
Most wall-warts have capacitors connected to mains which results in half the mains voltage at the output so that isn't a solution. The best is to fit a ground outlet in the function generator.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on August 06, 2017, 06:07:43 pm
you also of course have the option of powering it from a battery pack if required.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 06, 2017, 09:15:59 pm
Most wall-warts have capacitors connected to mains which results in half the mains voltage at the output so that isn't a solution. The best is to fit a ground outlet in the function generator.
This is where my lack of experience shows. You say a wall wart is not an adequate solution?

What would be needed to hook it up correctly and how would one go about it? Replacing the two prong socket and switch with a three prong fused socket should be doable. I know ground often is hooked up to the case or chassis of the device, but this case is plastic. How would you then hook the ground up internally? Is it as simple as connecting internal ground to the ground pin, so that the fuse box in your house can detect any difference between incoming and outgoing power?


That's the JDS6600 which has the wall wart, already a thread or two on it in the forum. It appears to be 12 bit rather than 14 and have no modulation capabilities. The internal PSU on the FY6600 seems to have changed a little from the ones used in the FY3224S with at least the inclusion of an X-class cap. But its probably the crappy xformer leaking the AC onto the ground. I like the physical buttons on the JDS.
Modulation is also what interests me about the Feeltech. I currently have no use for it, but if history is any indication, I will as soon as I purchase the device without it :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on August 07, 2017, 12:01:58 am
Like Nitco said most cheap and certainly the supplied wall wart with the unit I suspect will have the capacitor but you can get better ones that are multi-voltage out ones that normally have a linear power supply, they will be larger and heavier and considerably more expensive but should well worth it for the piece of mind alone.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 07, 2017, 12:16:27 am
Like Nitco said most cheap and certainly the supplied wall wart with the unit I suspect will have the capacitor but you can get better ones that are multi-voltage out ones that normally have a linear power supply, they will be larger and heavier and considerably more expensive but should well worth it for the piece of mind alone.
I thought he didn't consider it to be a solution because a wall wart leaves the device floating. Guess I was wrong :)



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cdev on August 07, 2017, 03:39:14 am
Although everybody is alluding to it, for the benefit of newer visitors, let me just recap why everybody is talking about the power supply. If you are just reading about them for the first time, the crucial unvarnished fact is that unmodified, the "ground" connection on the BNCs on the older FY32xx carry leakage voltages high enough not only to damage delicate components many times over, but also to present a shock hazard if somebody is sweaty or has wet hands, under some conditions.

But the big danger it presents is to chips, if its used ungrounded, which is fairly likely given its target market, electronics hobbyists.

So one has to be careful to always ground it - and perhaps even unplug it when it isn't in use.

How much more would it have cost them to do that right?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 07, 2017, 03:51:46 am
Someone should mention that unmodified, the "ground" connection on the BNCs on he older FY32xx carry leakage voltages high enough to damage delicate components many times over, but at low current.

So one has to be careful to always ground it - by means of the shield of the BNCs on the back or similar, when its in use, and unplug it when it isn't.

How much more would it have cost them to do that right?

To be fair its a tough call. Sometimes you want a floating source. Linear supplies are more expensive and heavier (important when shipping from PRC). Something has to give at these prices.

The USB port could always be connected to a grounded source like a PC. The other thing you could do is add another Y class cap from the secondary negative to an external ground source and redirect the primary Y to this ground as well. Internal ground still floats and is isolated but AC has a path to PE.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kleinstein on August 07, 2017, 05:15:45 pm
The leakage current problem is not so much about an internal or external (wall wart) power supply. It is more about switched mode power supply not using PE or a classical transformer. To meet EMI regulations a SMPS essentially needs the class y capacitor from the output to an RF ground. With a class II supply (using only 2 wires) there are usually 2 Y capacitors towards both sides of the supply and thus half the mains voltage when measured with a high impedance meter. This applies to the cheap internal supply and most SMPS based wall warts. Most instruments should survive the small voltage spikes of the 5 nF (or so) Y cap.

A way around this would be using a supply with a classical transformer or a SMPS with a third wire (PE). The PE connection could be used for a direct connection the GND (e.g. BNC) or just for the y capacitor. So ideally they would have 2 class Y caps from the power pin to warts a PE connection and then a 3rd y cap (and maybe a resistor in the M Ohms range) to the output.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 07, 2017, 05:50:04 pm
The leakage current problem is not so much about an internal or external (wall wart) power supply. It is more about switched mode power supply not using PE or a classical transformer. To meet EMI regulations a SMPS essentially needs the class y capacitor from the output to an RF ground. With a class II supply (using only 2 wires) there are usually 2 Y capacitors towards both sides of the supply and thus half the mains voltage when measured with a high impedance meter. This applies to the cheap internal supply and most SMPS based wall warts. Most instruments should survive the small voltage spikes of the 5 nF (or so) Y cap.

A way around this would be using a supply with a classical transformer or a SMPS with a third wire (PE). The PE connection could be used for a direct connection the GND (e.g. BNC) or just for the y capacitor. So ideally they would have 2 class Y caps from the power pin to warts a PE connection and then a 3rd y cap (and maybe a resistor in the M Ohms range) to the output.

Yes. This was my thought. A simple "fix" would be to change the power connector to an IEC and then add a Y cap (and maybe a high value resistor) from internal ground to PE. That should droip the leakage to very low levels. And if you don't need a floating output, just short the internal ground to PE.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 07, 2017, 06:07:32 pm
A way around this would be using a supply with a classical transformer or a SMPS with a third wire (PE). The PE connection could be used for a direct connection the GND (e.g. BNC) or just for the y capacitor. So ideally they would have 2 class Y caps from the power pin to warts a PE connection and then a 3rd y cap (and maybe a resistor in the M Ohms range) to the output.
I found this power supply. Even though it is obviously switching and cheap, it does have a third prong and does come from a reputable source. I was suprised the shipping does not kill it either.

https://www.sparkfun.com/products/11296 (https://www.sparkfun.com/products/11296)

So this is the one to get, aside from the ground concern? What is different about the 60M version?[/]

I might hack the case to install a 3-prong receptacle and set up a grounding circuit inside the unit since there is so much room.

Is there an English language review? Dave?
I am curious about the differences between the versions too and whether they are actually different, or just firmware limited.

Dave seems to be quite harsh on anything cheap and Chinese, so I do not expect a recommendation from him.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 07, 2017, 06:14:42 pm
A way around this would be using a supply with a classical transformer or a SMPS with a third wire (PE). The PE connection could be used for a direct connection the GND (e.g. BNC) or just for the y capacitor. So ideally they would have 2 class Y caps from the power pin to warts a PE connection and then a 3rd y cap (and maybe a resistor in the M Ohms range) to the output.
I found this power supply. Even though it is obviously switching and cheap, it does have a third prong and does come from a reputable source. I was suprised the shipping does not kill it either.

https://www.sparkfun.com/products/11296 (https://www.sparkfun.com/products/11296)

So this is the one to get, aside from the ground concern? What is different about the 60M version?[/]

I might hack the case to install a 3-prong receptacle and set up a grounding circuit inside the unit since there is so much room.

Is there an English language review? Dave?
I am curious about the differences between the versions too and whether they are actually different, or just firmware limited.

Dave seems to be quite harsh on anything cheap and Chinese, so I do not expect a recommendation from him.

One of the 12V lines might be negative like on the FY3200 series. Best get someone to confirm before ordering parts. Yeah, I don't expect any review from Dave. He concentrates on either the professional stuff or the "serious" home lab and I expect he would recommend a used unit of known quality before this one. Problem is that even the cheapest AWG's from brand names go for twice the price or more used and much more if you want more than 25MHz. I am looking to use the unit in a space limited setup as well and this is one of the smaller ones.

As for the differences, in the manual I can only see  the sine wave output as being different between the models. Everything else looks the same. Probably a firmware hack but then its only about $30 difference between the 15MHz and the 60MHz so hardly worth the time.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 07, 2017, 07:58:33 pm
I was wondering if you traded resolution for frequency or some other function. I did look at some of the used name brand and did notice how quick it gets expensive.
Same resolution of 1uHz across the board. The only other limitation is the 15MHz unit is restricted to a 15Mhz square as well as sine wave. I think the 30 or 50MHz units are the best value.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on August 07, 2017, 08:52:15 pm
I was wondering if you traded resolution for frequency or some other function. I did look at some of the used name brand and did notice how quick it gets expensive.
To some extent this might be true, I have the MHS 5200A version which is 25Mhz and if you look on here and you tube there are plenty of reports and reviews basically slagging it off as it having poor square waves at 25Mhz they say it looked more like sine waves, also stating that it claimed to be capable of 20Vpp but couldn't deliver etc. But in reality, checking the manual reveals the following:-
Sine wave is the only one to go the 25Mhz, all others, Sq, Saw Tooth and Arbitrary waves are up to 6Mhz. output is indeed 20Vpp on all waves up to 12Mhz and after it drops down to 15Vpp.

This I suspect is really a function of the limited supply coming from the built in SMPS, maybe replacing this with a linear power supply may lift this.

Is it really worth paying out for the second hand more well known and very expensive branded lab type of equipment for the average user? I would say, only if you really must have / require the extra functions / accuracy etc that these will provide, maybe if your using them in a business yes but if you're like me, just dabbling at home for the fun of it, then no.

You pay your money and takes your choice, at the end of the day, thats a decision only you can make, but personally, I'd check the manual and see if it can do what you need it to do and take it from there.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on August 07, 2017, 09:03:02 pm
I was wondering if you traded resolution for frequency or some other function. I did look at some of the used name brand and did notice how quick it gets expensive.
To some extent this might be true, I have the MHS 5200A version which is 25Mhz and if you look on here and you tube there are plenty of reports and reviews basically slagging it off as it having poor square waves at 25Mhz they say it looked more like sine waves, also stating that it claimed to be capable of 20Vpp but couldn't deliver etc. But in reality, checking the manual reveals the following:-
Sine wave is the only one to go the 25Mhz, all others, Sq, Saw Tooth and Arbitrary waves are up to 6Mhz. output is indeed 20Vpp on all waves up to 12Mhz and after it drops down to 15Vpp.

This I suspect is really a function of the limited supply coming from the built in SMPS, maybe replacing this with a linear power supply may lift this.
No, what is limiting the the maximum output voltage is the slew rate of the amplifier stage driving the output. 20Vpp @12MHz is quite a lot already.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on August 08, 2017, 02:50:07 am
I suppose if you occasionally needed a well-formed square wave, you could have the AWG drive an external Schmidt trigger.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 08, 2017, 04:35:17 am
One of the limitations to this unit, suffered by many others I am sure, is that it supports a 20Vpp output only to 10MHz, then 10Vpp to 20MHz and then 5Vpp thereafter. As noted before, this is likely a limitation of the output amplifier. I would suggest buyers RTFM before purchase to know exactly the limitations here.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 08, 2017, 09:46:06 pm
One of the limitations to this unit, suffered by many others I am sure, is that it supports a 20Vpp output only to 10MHz, then 10Vpp to 20MHz and then 5Vpp thereafter. As noted before, this is likely a limitation of the output amplifier. I would suggest buyers RTFM before purchase to know exactly the limitations here.
That's common amongst these cheap units, but if it is properly and accurately specified, there is no problem.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pi^2 on August 27, 2017, 05:37:07 pm
My FY6600 BNC-ground to Earth-ground Voltage is 94 Volt.
Zing zing zing, not happy about it.
Will have a look for a cheap 30VA isolation transformer.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 27, 2017, 05:45:23 pm
My FY6600 BNC-ground to Earth-ground Voltage is 94 Volt.
Zing zing zing, not happy about it.
Will have a look for a cheap 30VA isolation transformer.
That's what I was afraid of. I'm kind of glad I didn't pull the trigger on this one. With all the extra fiddling and hours measuring and fixing things involved, buying a 'real' unit isn't that much more expensive.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 27, 2017, 06:09:48 pm
Wouldn't have cost them more than a few cents to provide a PE supply.  |O
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on August 27, 2017, 06:20:08 pm
My FY6600 BNC-ground to Earth-ground Voltage is 94 Volt.
Zing zing zing, not happy about it.
Will have a look for a cheap 30VA isolation transformer.
That's what I was afraid of. I'm kind of glad I didn't pull the trigger on this one. With all the extra fiddling and hours measuring and fixing things involved, buying a 'real' unit isn't that much more expensive.
I don't know what your hourly rate is but putting a IEC socket with earth in and connecting the earth to the 0V of the power supply takes about half an hour. I know many people like to turn this into a big project but that is not necessary at all.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 27, 2017, 06:38:00 pm
I don't know what your hourly rate is but putting a IEC socket with earth in and connecting the earth to the 0V of the power supply takes about half an hour. I know many people like to turn this into a big project but that is not necessary at all.
Just talking about it here has cost me more than half an hour, so that ship has sailed :D Doing research on the construction and parts that have to be ordered, the costs of the parts, putting the parts in and testing whether the problem has been adequately solved all add up. That's probably more than an evening of work. I tend to share your optimistic judgement of project times, and it somehow never seems to pan out.

Of course, it could be a nice project, but I have reached the point where I want to focus more on my actual projects, rather than every tool added becoming a project on its own just to save a few bucks.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on August 27, 2017, 06:57:21 pm
I don't know what your hourly rate is but putting a IEC socket with earth in and connecting the earth to the 0V of the power supply takes about half an hour. I know many people like to turn this into a big project but that is not necessary at all.
That's probably more than an evening of work. I tend to share your optimistic judgement of project times, and it somehow never seems to pan out.
Well I already upgraded a FY3000S series so I know it is half an hour of work. And what is difficult about ordering an IEC inlet and a piece of wire (if you don't have these already)?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on August 27, 2017, 07:05:13 pm
I don't know what your hourly rate is but putting a IEC socket with earth in and connecting the earth to the 0V of the power supply takes about half an hour. I know many people like to turn this into a big project but that is not necessary at all.
That's probably more than an evening of work. I tend to share your optimistic judgement of project times, and it somehow never seems to pan out.
Well I already upgraded a FY3000S series so I know it is half an hour of work. And what is difficult about ordering an IEC inlet and a piece of wire (if you don't have these already)?

Did you use a Y cap or just a direct connection?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on August 27, 2017, 07:10:17 pm
I don't know what your hourly rate is but putting a IEC socket with earth in and connecting the earth to the 0V of the power supply takes about half an hour. I know many people like to turn this into a big project but that is not necessary at all.
That's probably more than an evening of work. I tend to share your optimistic judgement of project times, and it somehow never seems to pan out.
Well I already upgraded a FY3000S series so I know it is half an hour of work. And what is difficult about ordering an IEC inlet and a piece of wire (if you don't have these already)?
Did you use a Y cap or just a direct connection?
Direct connection. The Y cap is already in the power supply. The problem is the leakage current caused by the mains filter.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on September 03, 2017, 04:01:38 am
English review up on youtube now. Highlights a few hidden bugs.

https://www.youtube.com/watch?v=409mkMmJ-jE (https://www.youtube.com/watch?v=409mkMmJ-jE)

A little disappointed  that he doesn't give any overview of the VCO functions.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sp2iqw on September 06, 2017, 10:37:51 am
Few days I have ordered 30MHz version so now I'm waiting  :)

This genarator has very good price/performance ratio so it is hard to expect more in this price range.

Anyone know what is a freqency of an oscillator clocking the Cyclone IV FPGA ? No way to read it on a "a teardown" film available on Youtube (https://youtu.be/LNBX3yrp5ps?t=1m43s)
20ppm specification is rather low comparing to sub-1ppm TCXOs available on the market under 1$.  Of course in majority of apllications that's more than enough.

Michal
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: feeltech on September 08, 2017, 12:52:11 am
First of all, in the absence of the introduction of the ground wire of the two-wire plug of the switching power supply system will have such a situation.
In order to suppress common mode interference, the switching power supply in the design, the "safety capacitor" will be between the "LG / NG" (safety capacitor is used for such occasions, even if the capacitor fails, will not lead to electric shock,  so the secondary side of the switching power supply "ground" is equivalent to the midpoint of the AC voltage, so you measured 110V voltage. But this does not mean there will be security risks, after all, the capacitance capacity of only 1000pf.
If you are still worried about its leakage, then the correct way is to measure its DC leakage resistance, the use of insulation tester is the most effective way
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on September 08, 2017, 12:56:02 am
First of all...

Is this the "real" FeelTech?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: feeltech on September 08, 2017, 01:07:09 am
First of all...

Is this the "real" FeelTech?

Yes, we need to listen to all kinds of opinions or suggestions in order to make the product better.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on September 08, 2017, 03:33:49 am
That's great! Welcome to the forum. :-+

Since you're here, if there is a way to update the firmware in the FY3224S, can you post that info in the FY3224S thread (https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/)? Many have asked about it. Thanks!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on September 08, 2017, 08:15:35 am
First of all, in the absence of the introduction of the ground wire of the two-wire plug of the switching power supply system will have such a situation.
In order to suppress common mode interference, the switching power supply in the design, the "safety capacitor" will be between the "LG / NG" (safety capacitor is used for such occasions, even if the capacitor fails, will not lead to electric shock,  so the secondary side of the switching power supply "ground" is equivalent to the midpoint of the AC voltage, so you measured 110V voltage. But this does not mean there will be security risks, after all, the capacitance capacity of only 1000pf.
If you are still worried about its leakage, then the correct way is to measure its DC leakage resistance, the use of insulation tester is the most effective way
Test equipment should not have this problem. The leakage current is big enoug to destroy a circuit so it is very bad!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: feeltech on September 08, 2017, 08:49:53 am
That's great! Welcome to the forum. :-+

Since you're here, if there is a way to update the firmware in the FY3224S, can you post that info in the FY3224S thread (https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/)? Many have asked about it. Thanks!
There is no online upgrade function, if there is an error, can only contact the dealer to replace, we repair and upgrade, but FY6600 after the product we will add online upgrade function.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on September 08, 2017, 09:00:19 am
Test equipment should not have this problem. The leakage current is big enoug to destroy a circuit so it is very bad!
For me, it is the reason not to buy the unit, along with not trusting no Chinese things on mains. If I can use my own plugpack or power supply, I'm game.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on September 08, 2017, 09:07:52 am
Test equipment should not have this problem. The leakage current is big enoug to destroy a circuit so it is very bad!
For me, it is the reason not to buy the unit, along with not trusting no-Chinese things on mains. If I can use my own plugpack or power supply, I'm game.
-sigh- Your own plugpack will have the same problem if it is a switching one.  :palm: And it is probably made in China as well.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on September 08, 2017, 09:47:54 am
-sigh- Your own plugpack will have the same problem if it is a switching one.  :palm: And it is probably made in China as well.
Note it's a two part remark. One is about not blowing your DUT up. That will not be solved by a switching plugpack, though picking the right power supply might. The second part is about not burning your house down, which, if I have to choose, is my biggest priority.

Also note the difference between "Chinese" and "made in China". The first denotes something designed, sold or made by an unknown Chinese company, with no local legal entity to address in case of trouble. The second includes products designed and sold by reputable companies that have much to lose in case of neglect. Buying a decent brand microwave and finding out it's made in China? Fine. Buying an unbranded mains to DC power supply off of eBay and actually using it? No, thank you kindly.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: inqubi on September 08, 2017, 07:45:49 pm
Hi

I have just discovered this forum searching the web for any Feeltech support...

Ordered on eBay, my FY6600 has been delivered today and after checking its CD proved not to be properly burned. Could somebody be so kind and upload somewhere (any cyberlocker You like:  https://mega.nz (https://mega.nz)  https://mediafire.com (https://mediafire.com)  http://catshare.net (http://catshare.net) ....) zipped all its content ??

A link to uploaded CD, posted earlier in this thread is down now.

Many Thanks!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: feeltech on September 09, 2017, 03:24:06 am
Hi

I have just discovered this forum searching the web for any Feeltech support...

Ordered on eBay, my FY6600 has been delivered today and after checking its CD proved not to be properly burned. Could somebody be so kind and upload somewhere (any cyberlocker You like:  https://mega.nz (https://mega.nz)  https://mediafire.com (https://mediafire.com)  http://catshare.net (http://catshare.net) ....) zipped all its content ??

A link to uploaded CD, posted earlier in this thread is down now.




Many Thanks!
FY6600 User Guidehttps://drive.google.com/file/d/0B3N_NW8vylrmaHFRLXloOVJQYjA/view?usp=sharing (https://drive.google.com/file/d/0B3N_NW8vylrmaHFRLXloOVJQYjA/view?usp=sharing)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sintechs on September 12, 2017, 12:01:55 pm
but FY6600 after the product we will add online upgrade function.
You mean that FY6600 already has the ability to upgrade firmware online?
I'm asking this because some sellers have FW ver. 2.6, others 2.8.
Does it make sense to buy the latest firmware now, if online upgrade going to be available soon?
Could you please describe the difference between 2.6, 2.8, 2.9?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: feeltech on September 16, 2017, 09:04:14 am
but FY6600 after the product we will add online upgrade function.
You mean that FY6600 already has the ability to upgrade firmware online?
I'm asking this because some sellers have FW ver. 2.6, others 2.8.
Does it make sense to buy the latest firmware now, if online upgrade going to be available soon?
Could you please describe the difference between 2.6, 2.8, 2.9?
Function is not much difference, just fix some of the different languages show the problem
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on October 13, 2017, 06:13:55 pm
Hi

I have just discovered this forum searching the web for any Feeltech support...

Ordered on eBay, my FY6600 has been delivered today and after checking its CD proved not to be properly burned. .../...
A link to uploaded CD, posted earlier in this thread is down now.

Many Thanks!

Hi all,
The same for me, the CD I received with the Feeltech FY6600 (rev 3.1) last week is 100% unreadable (I checked it on 3 PC, all 3 with the same issue)
I really need the software to play arbitrary signals.
Someone can help me by posting the software ? (email or cloud)

Thanks a lot
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on October 28, 2017, 05:51:34 pm
Hi All

also got a FeelTech FY6600
regarding CD: I don't even know if I can read it. I do have an old PC with CD collecting dust somewhere, but I don't feel like digging it out. So if anyone does get a link...


I played around a bit with the FY6600, and it seems to work OK. Sine is exactly the same as generated by the one build into my DS1074Z-S. (I compared with A-B math function) Square has a slightly better rise time (about 8ms instead of the 12ns of the build in.) And control is a *lot* easier. That is the biggest problem with the DS1074Z-S build in: really bad controls. Frequency wise, on a 15Mhz signal, they differ about 100Hz, drifting back and forth a bit. So about 6ppm. I suspect that is pretty OK for cheap equipment like these two.


Signal wise, I found only one problem: all vertical edges (square, step, sawtooth) have a 5ns variance in timing. Regardless of the frequency, you always get runt edges 5ns apart. I suspect the max resolution of some internal CPU or DAC frequency is showing here. It of course is only important for higher frequencies, shown is 15Mhz. The Blue one is the DS1074S-Z internal signal, its fuzzy because I am triggering on the yellow FY6600. As you can see, apart from the 5ns variance, the FY6600 has a better rise time and a better shape.


Control wise, it works a *lot* better then the DS1074Z-S internal signal gen. Pretty intuitive too.

A few minor control annoyances:

- You cannot stop the modulation. You can select other modulation parameters, but you cannot stop. The only way I found is to set it to use Channel 2 as mod source (that is default anyway) and then stop channel 2. That will go back to normal signal gen mode. Unlike Sweep, which you can start, and stop at will. Just press CH1...Doh.

- The "Wave" button does not only highlight the waveform menu option, so the rotary button can be used on that menu, but immediately advances the value selection as well. Iow, selects the next waveform. This is different than all the other buttons (like Freq, Ampl, Offs, Duty, Phas) which all select the menu on the first press, and only the second press advances the value (or you can use the rotary button). Not very important, but a bit annoying.
 
- 00'010.000'000'000KHz is a pretty weird way of writing 10 Khz. I had to stare at that for a while. I think there are better ways to indicate the frequency. 
Edit: And now it is displaying 00'002'000'000'000uHz to show 2KHz. 2 billion microHerz  :palm: Must be a setting somewhere.... OK, not important. The value is technically correct.


So since FeelTech seems to be reading this topic, please take note.

Thanks

Edit: to get these square waves without overshoot, I had to properly terminate with 50 Ohm.
Edit2: This is a FY6600-60M version 3.1 English

(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=364945;image)

More edit: SYNC

I also played with the SYNC function. It has external SYNC in and out, and supposedly you can link multiple devices together, as well as sync CH1 anc CH2.
Some problems with both:

While I do not have two devices, when I put mine in master mode, all it outputs is a 1V square wave that matches CH1 (0V~1V 50 Ohm). No fancy protocol. So you'd think I can also link any other signal source if I match that. No avail, whatever I try, I am not getting it to follow another signal source. Some disclosure by FeelTech would be nice.


SYNC between CH1 and CH2 it works better. It all works nicely at lower frequencies, lets say < 5MHz, but at higher frequencies, the phase starts to go wrong.

The problem seems to be that CH1 and CH2, when "in phase" are still 4ns apart. Again this 4ns (I now believe the 5ns above is also 4ns)
This is of course due to the 250MSa/s specification for the device: 250MSa/s means 1 sample every 4 ns

 That means that if you specify 0 degree phase difference, at <5 MHz frequencies, they are pretty much in sync (4ns = 7 degrees).
But at 60MHz they are pretty much in quadrature (4ns = 86 degrees)
So if you specify 86 degrees offset, they are actually in-phase.

So, at 5Mhz, in-phase is indeed in-phase (roughly). But then if you dial up to 60MHz, you visibly see it shift out of phase.
Now here is the weird thing: You can still then correct the 60MHz to in=phase, by setting it to 86 degrees.
And even weirder, somehow you can also set it to all phases in-between with a pretty good resolution.
I think its because the Sine at this point is filtered rather then sampled, but I was still surprised by it.

It does mean FeelTech could fix this, they could "correct" the phase automatically with software, just like I can manually.
And indeed, the DS1074Z-S internal generator does not have these problems, even though its only using a 200MSa/s DAC.
Use equal length cables dummy!

Yet more edit: SWEEP

It works. But I suddenly realize I miss a sweep/trace/scan output. Not sure what the name is. But a sawtooth that shows how far the sweep is, and that I can feed into my scope as X trigger.

One could naturally have this if CH2 could be used as driver for the sweep in stead of VCO, but that is not an option: only fixed time window and VCO are allowable sources.
So I took CH2, looped it into the VCO and that works but it is a bit unclean. In fact, I found it better to simply put a sawtooth on CH2 and do FM modulation, that also causes a frequency sweep. AM for amplitude sweep. For PWM, still have to use the CH2-VCO loop.

Request/suggestion to Feeltech: allow CH2 as source for Sweep, using the default 5Vpp as normal rather then the 0-5V from VCO. Or alternatively, output the set sweep time values as sawtooth on CH2.


Still good. I wanted a device that is easier to control then the DS1074Z-S internal one, and that can do SWEEP.
I don't think I will be often running at high frequencies. And the sweep is 'workable'. So I am happy with the device. For now.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on October 29, 2017, 08:18:45 pm
Hi there,

I ordered one for its capabilities with arbitrary signals and modulation too.
I played around with it (FY6600-30M version 3.1 English)  for days now, its a nice generator full of features and not very expensive.

but I'm facing a weird situation with the sine wave, and only with the sine on both channels. |O

When I select the sine wave from the stored waves (1st position, not arbitrary number 24 which is okay), sine is no more displayed on the FY6600 screen like other waveforms, and the signal on the output is really crapy.
The sine wave seems to be "modulated" with sharp pulses.
It happens only with the sine wave selected, other waveforms are ok.

I made a soft reset, tried to play with all the parameters and found nothing relevant to restore that situation.

I really need some help from you guys ;-)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on October 29, 2017, 09:52:01 pm
Was it always like that, or is that new?
What exactly do you mean by: "sine is no more displayed on the FY6600 screen like other waveforms"

My interpretation of that phrase is: The little graph/icon of the waveform is gone or messed up.
Maybe add a photo? And a snapshot of the actual waveform with peaks?

But if so, I would guess flash/eeprom corruption of the area where waveform 1 is stored.

Did you manage to get the software to work, and did you upload your own arbitrary waveforms?
Because I guess they are all stored waveforms, maybe it is a bug and the  software accidentally overwrite the Sine instead of Arb1
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: gby on October 29, 2017, 11:12:36 pm
A couple of people have been unable to read the CD that came with their generator.  Unfortunately the Feeltech website (http://en.feeltech.net/ (http://en.feeltech.net/)) does not have FY6600 files for download yet.  Since I was able to read my CD I made a zip file of just the files relevant to the FY6600 and put it up on https://wetransfer.com/ (https://wetransfer.com/) on a free hosting.  Since this is a free hosting it will only be available for 7 days so get it right away.

https://we.tl/2UmRtktEZy (https://we.tl/2UmRtktEZy)

I haven't loaded it myself yet but would be interested in folk's experience with it.

Enjoy
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on October 30, 2017, 10:22:22 pm
Was it always like that, or is that new?
What exactly do you mean by: "sine is no more displayed on the FY6600 screen like other waveforms"
New after using 2 times
Quote
My interpretation of that phrase is: The little graph/icon of the waveform is gone or messed up.
Maybe add a photo? And a snapshot of the actual waveform with peaks?
When the sine waveform is selected, the graph on the display is now a flat line  :-[

Quote
But if so, I would guess flash/eeprom corruption of the area where waveform 1 is stored.
Did you manage to get the software to work, and did you upload your own arbitrary waveforms?
Because I guess they are all stored waveforms, maybe it is a bug and the  software accidentally overwrite the Sine instead of Arb1
I agree with you, something went wrong with data stored in the eeprom.
Today I've installed the program on my PC, however there's no way to overwrite the datas stored in the eeprom (only the bank corresponding to the arbitrary waves from 1 to 64 slots can be managed)

Thanks Cybermaus for your help :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on October 30, 2017, 11:33:53 pm
Contact the seller about getting it repaired or replaced under warranty.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 01, 2017, 02:52:09 pm
Hello
I want to buy a function generator
which one has the better quality? JDS600 or FY6600?

Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 01, 2017, 03:30:33 pm
Hard to say man.

My personal feel is FY has more options, and if you look at the square wave rise time in this link (https://www.eevblog.com/forum/testgear/anybody-know-anything-about-this-signal-generator/msg1240749/#msg1240749) from the JDS thread vs mine above, I'd say FY also as better quality in square signals (they all can do a proper Sine, sine is easy, that's why they always rate their highest frequency on the Sine wave).

But in reality: If you want "quality" above 5MHz you'd probably need to step up your budget.
And if you are looking for play and hobby, they are probably both "good enough"

Thats my 5ct anyway. No-one seems to actually have both devices, so its all subjective.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 01, 2017, 04:15:35 pm
Dear
I want to tune my medical board. I should increase the frequency from 10KHz to 20MHz and check the close loop response (AC Analysis)
another usage is checking the step response of my circuit. actually measuring the amount of overshoot. 100KHz or 1MHz clean pulse waveform is adequate.
all the ports are terminated at 50R. the test signal should be 1Vpp at 50R.
if you have one please show me the quality of square wave from 10KHz to the Maximum frequency. it's very important.

Regards
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 01, 2017, 09:02:06 pm
10KHz 1Vpp terminated at 50 Ohm (so shows as 0.5Vpp):
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366374;image)

Same, but completely zoomed into risetime of 7.4ns (see measurement in lower left corner)
A small wiggle, not does not really overshoot at all.
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366376;image)

Same, but at 1MHz 10MHz
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366378;image)

Same but at 25MHz, the official top frequency for square wave for this device
Note that there are no 5ns runt flanks as described in the post above. That is because 25MHz is a perfect divider of the 250MSa/s DAC. With 24MHz or 26MHZ runt flanks again.
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366380;image)

Same, but at 50MHz square pulse. This is above device specification, but you can turn the knob up all the way to this.
It basically became an attenuated sine wave, not really a square anymore:
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366383;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 01, 2017, 10:33:33 pm
Dear
I really appreciate you for your work :)
I think the quality is good.
actually when you have a 50MHz sine generator the maximum frequency of a good quality Square wave should be 10MHz.
consider you want to design a 50MHz sine signal generator. you should filter the output to have a good SNR and THD.
for example you set the f-3dB of the LPF at 75MHz.
now if you order to generate a 50MHz square signal it will be Sine signal as you have shown in the above pic! :)
it's not a drawback.

another way is converting a sine signal to a square signal using a fast comparator and a high speed buffer.
http://www.arrl.org/files/file/QEX_Next_Issue/May-Jun_2013/Fernandes_QEX_5_13.pdf (http://www.arrl.org/files/file/QEX_Next_Issue/May-Jun_2013/Fernandes_QEX_5_13.pdf)
 :popcorn:
http://www.high-voltage-lab.com/186/self-powered-sine-to-square-wave-converter (http://www.high-voltage-lab.com/186/self-powered-sine-to-square-wave-converter)

you can see a 200MHz high quality signal generator in the below! (it's only 100$)
look at the Spectrum Analyzer's pics.
https://www.circuitsonline.net/forum/view/130301 (https://www.circuitsonline.net/forum/view/130301)
it's another project:
https://wiki.electroniciens.cnrs.fr/index.php/Le_groupe_DDS (https://wiki.electroniciens.cnrs.fr/index.php/Le_groupe_DDS)
AD9954 is another DDS IC. (check aliexpress or ebay)

if you have free time would you please do a test?
set your function generator in Sine mode and 2Vpp. (terminate your Oscope at 50R)
change the frequency from 10KHz to the maximum frequency step by step. (for example in 10 steps ... more points is better)
each time turn on the FFT function and set the Average to 64 or 128.
now measure the peak magnitude and write it in a Table.
would you share the Table? :)

Best Regards
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 02, 2017, 09:43:06 am
Hi all,

Just a practical tip if you tried to talk with the FY6600 over serial com port.
The parameters are 115200/8/n/1 and not 9600/8/n/1 as described in the documentation.

Enjoy talking with your FY6600 !

In attachment, the response to UMO command (return the model of your generator)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maddin on November 02, 2017, 07:09:51 pm
Hello together,
i have also ordered a FY6600. Because there seems to be a lot of trouble reading the CD i have load the software from the link gpy posted.
Thanks to gpy for upload the CD.

I have scanned the "FY6600 PC Software V5.2.exe" on virustotal.com ; one result: Suspicious_GEN.F47V1016 :-//
Should i been concerned about this ? What's  your experience with the software ?

Best regards
maddin
 
   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on November 02, 2017, 07:20:57 pm
Lots of antivirus programs will see an unknown .EXE file as a potential threat and flag it as suspicious. I doubt you have anything to worry about, nobody else here has reported any problems apart from the odd difficulty reading the CD.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on November 02, 2017, 07:29:32 pm
Then again, if most owners can't read their CD and, prior to gby uploading, didn't have another means for acquiring the software, there could be something awry that we haven't heard about.

It's likely a false alarm, but not a lot of info either way.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 02, 2017, 08:20:53 pm
I would be grateful if you could do the below test:
if you have free time

set your function generator in Sine mode and 2Vpp. (or 2Vpp RMS) (terminate your Oscope at 50R)
change the frequency from 10KHz to the maximum frequency step by step. (for example in 10 steps ... more points is better)
each time turn on the FFT function and set the Average to 64 or 128.
now measure the peak magnitude and write it in a Table.
would you share the Table? :)



Best Regards
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on November 02, 2017, 08:32:28 pm
it would drop I expect by quite a large percentage as you approach the upper limits, I know that the previous round of such devices did.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 02, 2017, 08:34:55 pm
Regarding the "virus" : run it against https://www.virustotal.com/#/home/upload (https://www.virustotal.com/#/home/upload) to see if it is a false positive

Regarding the FFT request: The math and FFT on my DS1000Z series is pretty useless, I feel you want someone with a 2000 or 4000 series to do that.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 02, 2017, 08:37:05 pm
No doubt. I want to judge the quality :) if you have one please do this easy test :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yannik on November 02, 2017, 08:40:32 pm
Is it possible to adjust the rise/fall time of square waves with this generator? I really need that capability.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 02, 2017, 08:43:20 pm
Pretty sure that is not possible.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 02, 2017, 08:57:58 pm
it's a very interesting option.
due to the 7ns rise time it's mandatory to use 50R terminated devices :)
consider the device use RG174 or RG316 cable, so the velocity factor is 0.7 now if you want to not encounter some problem, use 18cm Cable not anymore :)
if you could set the rise/fall time to 38nsec and use a 1m Cable you wouldn't have any problems :)

Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 02, 2017, 09:06:10 pm
Well, I guess you could always upload a arbitrary wave with such a shape that it is effectively a square with 38ns risetime

Maybe one such wave for 1MHZ, one for 10MHz etc. After all, you got a shitload of 64 ARB positions. One for each of your desired risetimes.


What I did find is that if you take a square, and modulate it with PSK with another square of the same frequency, I get a nice 4.4ns risetime square wave!
I think that is really impressive. I was playing with time-domain reflections to measure length the other day. with a <5ns device I should retry that play.

Edit: In fact, all the vertical edge waveforms (pulse, cmos, reverse sawtooth, all of them), *except* the square seems to be 4.4ns. Only the square has 7.8ns.
And indeed, much cleaner to see cable reflections with 4.4ns. Now I know my pieces of BNC-coax are about 1mtr in length  :P
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 02, 2017, 10:10:36 pm
Is it possible to adjust the rise/fall time of square waves with this generator? I really need that capability.
Nope
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 02, 2017, 10:26:53 pm
For those who are interested in the spectral behaviour above 1 MHz, I've made some tests with my spectrum analyzer.

Have a look at this :

30M Sine purity, better than 44dB
1M Sine 0dBm, 2nd and 3rd orders are below 52dB, not too bad indeed !
Bandwidth greater than 80MHz with a 10MHz multitone signal test, quite impressive

For <100$ , I've to admit that the results are pretty good !
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on November 02, 2017, 10:29:03 pm
Lots of antivirus programs will see an unknown .EXE file as a potential threat and flag it as suspicious. I doubt you have anything to worry about, nobody else here has reported any problems apart from the odd difficulty reading the CD.
While it's true that some antivirus solutions will flag certain types of code as suspicious, it's also true that many people ignore reported malware on account of it likely being a false positive. If malware is somewhat decently constructed and depending on the purpose, the user won't notice anything being wrong after getting infected.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 02, 2017, 10:56:40 pm
I'm wondered HOW the designer designed the setup?!
for 1MHz the SFDR is 54dBc :| for a cheap generator is good.
But I can not admit it! they have used a 14-Bit 250MSPS DAC, the frequency is only 1MHz! the SFDR should be better than 80dBc :)
above 70MHz they should use back to back topology (by using two Baluns) to have the better Harmonic Distortion suppression.

*which type of capacitors they have used?!
*which OP-AMPs they have used?

I'm familiar with designing such devices :)

I think it's a good AFG to tune the circuits (without checking the THD and ...) and checking the step response.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 02, 2017, 11:30:14 pm
Frankly it is a mistery.
Unfortunately it will be difficult to make some reverse engineering as a lot of ICs have no names (information scratched by Feeltech)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 03, 2017, 04:58:16 am
I am still a bit unhappy about those 4ns runt edges though. Not being a signal generator specialist, it seems to me like a unavoidable problem if you have a 250MSa/s DAC, but I am wondering how my DS1074Z-S internal generator is able to work without such edges when it has an even lower DAC of 200MSa/s


Also, I think I see a JTAG port, so while not officially updateable, it should be possible if we have the firmware and correct procedure.



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 03, 2017, 08:31:02 am
the Baluns are used for the frequency above 5MHz. when you have back-to-back topology the bandwidth is divided by sqrt(2).
it's recommended for the frequency above 70MHz. I think they have used some schematics from some datasheets.
there is no Baluns to support the frequency below 15KHz.

now let me show you an interesting curve about the SFDR and use of a Balun:
(http://s9.picofile.com/file/8310789234/fy6600_2.PNG)

even I suspect the capacitor's type you have used in the design!
now let me show you an interesting curve about THD+N vs frequency and Vrms:

(http://s8.picofile.com/file/8310790918/fy6600_3.PNG)

(http://s9.picofile.com/file/8310790992/fy6600_4.PNG)

Best Regards

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on November 03, 2017, 06:10:07 pm
I'm pretty sure the two chips next to the FPGA are overclocked DAC904s, to the right of the FPGA are a couple of buffer amps and discrete anti-aliasing filters.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on November 03, 2017, 06:56:52 pm
so the higher freqency models are just moer overclocked?  |O I just happen to be looking at this on ebay last night, local seller for best price I've seen so far. Almost...
You say it like it's a bad thing. Intel sells the same silicon at different clock speeds for different amoutns of money. Dave has done a video about factory overclocking. If you have tested and can guarantee operation, or even binned the chips, there little wrong with the practice.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 03, 2017, 07:23:54 pm
Dear
I couldn't read any part numbers at that video!
DAC904 is belong to Burr-Brown!
even I see two white components near BNC jacks. can you read the part number?

My brother told me to not buy this Function generator yesterday, he told me to buy a Rigol AFG at-least.
I think the best version of this AFG is 30MHZ bcoz DAC904 is a 160MSPS DAC.

it's worthy to note that some pics I uploaded above are the performance of a 12-Bit DAC!
even the Feeltech's designer couldn't keep the performance of 14Bit DAC904!
bad layout, bad capacitor type and ... will ruin the performance. he could have achieved very better performance even with 10 or 12Bits DAC!!!


Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 03, 2017, 10:15:33 pm
Some photos are following.
Your comments are welcome.

The high res images are stored on onedrive here :
https://1drv.ms/f/s!Alr1uExd0Z7lleYbxrcIoIomOrVprA (https://1drv.ms/f/s!Alr1uExd0Z7lleYbxrcIoIomOrVprA)

There is 14 DAC pins connected to the FGPA, photo FY6600-05 !
It seems to be a DAC904, the pinouts are corresponding to the photo.
The DAC904 is a 14b 165Msps converter produced by Burr Brown or TI.

DAC904 => LPFilter => OPA686


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 04, 2017, 04:14:53 pm
A couple of comments: the power input connector can easily be changed but the back panel is thin fiberglass so care must be taken when enlarging the opening so you don't crack the panel. Also the power supply already has a unused ground pad that can be used by just soldering the ground wire to it. That ground is carried on the 2 middle pins of the power supply interconnect cable so all the BNC shells on the panel are at zero potential. I've (hopefully) attached a photo showing what I did. 

Also the 50 Mhz oscillator in my unit isn't that great although it may meet the specs. If you have a function generator capable of many digits of resolution but the timebase is only accurate to 5 places, that is a waste. There are unused pads marked "S1" on the main board near the oscillator that may be for an external timebase that I'll look into.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on November 04, 2017, 04:18:08 pm
Welcome to the forum, Arthur and thanks for the info. Looking forward to your findings.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: mk_ on November 04, 2017, 04:34:52 pm
Some photos are following.
Your comments are welcome.

The high res images are stored on onedrive here :
https://1drv.ms/f/s!Alr1uExd0Z7lleYbxrcIoIomOrVprA (https://1drv.ms/f/s!Alr1uExd0Z7lleYbxrcIoIomOrVprA)


Thanks for detailed pictures

Well, at least it shows how not to design passive filter-gnd- areas.
In FY6600 -07.jpg there is only one (!) GND-via visible in the LPF1- filter-area (betweeen C36 and C37) so if this stuff will see the hf this filter will do a lot of jiggel but nothing predictable...
me thinks so the same mistake in LPF2.

michael
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 04, 2017, 05:05:30 pm
even I think the LPF should be placed after the Buffer to reduce the noise effectively not before!
the Buffer is actually a difference Amp.
I see two cap trimmers or 2 res pots. the CMRR of such designs is not good!
L10+C4+C27 and L12+C5+C16 are power supply filters to reduce the noise for the buffer.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 04, 2017, 05:33:33 pm
Also the 50 Mhz oscillator in my unit isn't that great although it may meet the specs. If you have a function generator capable of many digits of resolution but the timebase is only accurate to 5 places, that is a waste. There are unused pads marked "S1" on the main board near the oscillator that may be for an external timebase that I'll look into.

Is that a HHttG reference, or are you actually named Arthur Dent?

Anyway, if we could hook this up to an external 10MHz GPS disciplined reference oscillator, that would be marvelous.

Or even better, directly build in one of the cheap uBlox GPS modules. So we do not need to mess with amps and drivers, but could use the FY6600 itself as an adjustable reference frequency. That would be a nice project. Would make it into a pretty good frequency counter too then.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on November 04, 2017, 05:58:23 pm
bad layout, bad capacitor type and ... will ruin the performance. he could have achieved very better performance even with 10 or 12Bits DAC!!!

There is a ridiculous lack of competition in even medium speed DACs/ADCs, higher speed is worse, either they are completely integrated without general purpose use (mobile chipsets, cable modems etc) or you pay a ransom. There are only a couple of chips with really low prices, the DAC904 is one of them ... and it's not all that good to begin with regardless how you use it. Which is why some designs just stick with resistor ladders in this day and age still.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 04, 2017, 06:42:25 pm
You asked: "Is that a HHttG reference, or are you actually named Arthur Dent?"

This is a screen shot of the EEVBlog screen when I just registered. I had to save it because of what the answer to the last question was going to be. Certainly not a coincidence and I almost couldn't believe it! My 'real' name is Arthur Phillip Dent.   ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 04, 2017, 06:58:18 pm
That is hilarious  :-DD

But it has to be a coincidence. If people making HH references was normal enough for the web-admin to program such a Easter egg, your username would have been gone already.
Anyway, let me go and make up some towel jokes to include in the next couple of posts...

Edit: waaait a minute: It's actually more likely you decided on that user handle after you read the question ???



More seriously: I was assuming that S1 is a JTAG connector, but admittedly for no other reason that I would expect an unpopulated  JTAG on such a board, I did not follow the traces. But I am still thinking if you want to replace the timebase, you'd have to desolder the xtal module.

Edit: Yes, the chip between the S1 and the 50MHz is a Winbond 25Q16BVSIG : 16MBit Serial Flash with Dual SPI
 (https://media.digikey.com/pdf/Data%20Sheets/Winbond%20PDFs/W25Q16BV.pdf)It has at least 6 connections with the S1, so that makes it *very* likely some sort of SPI based programming header, like JTAG

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 04, 2017, 08:07:01 pm
While following the JTAG, I noticed 4 configuration solder islands labeled J10 J11 and J12 J6
Toward the back of the device, 2 on each side.

Not sure what they configure, my 60M board is coded like this:
J10 - closed by thin pcb trace
J11 - open, no pcb trace and no solder drop

J12 - closed by thin pcb trace
J6  - open, no pcb trace and no solder drop

So no solder drops, nor any scratched traces, meaning default PCB hardware.
I guess it would be too easy if this was the 60M 30M 15M frequency selection, but you guys check anyway.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 04, 2017, 09:04:14 pm
By PM request, some sine pics.

Mind you, not sure why you want these, if you think you can "eyeball" sine quality, you would be better off checking the spectrum pics a page back, they are much more relevant. The only thing you can get from these pics is a slight attenuation toward higher frequencies, which may as well be my scope rather then the AWG.

Also, please note the scope measurement at the bottom cannot be trusted on decimals. It is constantly jumping from 19.8 to 20.0 to 20.2, showing it lacks resolution.

20Mhz to 60MHz 1Vpp 50 Ohm
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 05, 2017, 01:35:48 am
Hello,

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366988;image (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366988;image)


The integrated circuit on each side of U302 is MCP 4822E Dual 12-Bit Voltage Output DAC.

Regards,
Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 05, 2017, 09:20:32 am
By PM request, some sine pics.

Mind you, not sure why you want these, if you think you can "eyeball" sine quality, you would be better off checking the spectrum pics a page back, they are much more relevant. The only thing you can get from these pics is a slight attenuation toward higher frequencies, which may as well be my scope rather then the AWG.

Also, please note the scope measurement at the bottom cannot be trusted on decimals. It is constantly jumping from 19.8 to 20.0 to 20.2, showing it lacks resolution.

20Mhz to 60MHz 1Vpp 50 Ohm

good job :) I see 0.5dB  attenuation at 20MHz and 2dB attenuation at 60MHz.

when the input impedance of your Oscope is 1M || 15pF and use a 50R capline, the VSWR<1.3 for up to 55MHz.  :horse:
but it depends on the quality of BNC T Adapter and other parasitic inductance, it could be 110MHz.  :bullshit:
so it's better to use an Active Adapter.

Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 05, 2017, 10:29:33 am
The puzzle is almost complete, thanks to all the contributors :-+

1   CH340G             /USB to serial
2   HC245               /octal bus transceiver
3   25Q16BVSIG      /Winbond 16MBit Serial Flash with Dual SPI
4   EP4CE6E22C8N  /FGPA Altera Cyclone4
5   DAC904             /14 bits DAC 165Msps =Channel 2
6   DAC904             /14 bits DAC 165Msps =Channel 1
7   MCP4822E         /Dual 12-Bit Voltage Output DAC (level Ch2)
8   MCP4822E         /Dual 12-Bit Voltage Output DAC (level Ch1)
9   OPA686N           /wideband low noise voltage amplifier
10 OPA686N           /wideband low noise voltage amplifier
11 JRC4558D          /Dual op amp
12 ?                       /wideband amplifier
13 ?                       /wideband amplifier
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 05, 2017, 11:38:26 am
Hi all
Did someone tried to play around with arbitrary waves with the FY6600 PC Software?
I'm facing issues when I try to open waveforms that were previously saved (file xxxx.FY).
After having opened the file, the waveform is always not corresponding to the saved one, the scale and the plots are totaly messy  |O

Hereafter, a printscreen of a ramp waveform saved and then reloaded !

Update : the method described above wasn't the right one (thanks to cybermaus), you'd better use "text window" and "add waveform" to perform the handling of custom waveform.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on November 05, 2017, 12:01:50 pm
Hi!

At the price they are it'd be within my monthly pocket-money allowance to buy one simply for the purpose of tearing-down and depopulating for the purposes of compiling a full proper instruction & service manual, and the posts in this thread so far, so if the superb clever chaps on here can pinpoint the last two chips U12 & U13 that'll be the inspiration I need to buy one for reverse-engineering purposes!

Is it worth looking in the EL-series to see if there's a pin-out match for the last two chips? Is there a way of removing the small square ali heat-sink from the O/P amplifier chips without risking wrecking the PCB it's made on?

PS!

1) Can anyone tell me how to extract pictures from PDFs and the little icons on toolbar buttons, etc., like they do to write software/product instruction manuals?

2) Has anyone dismantled the front-panel/display assembly of one of these and got the type-no and pixel-size spec. of the TFT colour display module yet?

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 05, 2017, 01:08:39 pm
Hi all
Did someone tried to play around with arbitrary waves with the FY6600 PC Software?
I'm facing issues when I try to open waveforms that were previously saved (file xxxx.FY).
After having opened the file, the waveform is always not corresponding to the saved one, the scale and the plots are totaly messy  |O

Hereafter, a printscreen of a ramp waveform saved and then reloaded !

Just works for me:
Opened tool. Made a waveform (combined sine, triangle and ramp), saved it.

Closed program, reopened program, loaded the waveform, no problem (attachment 1)

The only slightly odd thing is, if you "Open" a waveform, you get a dialog that has title&button "Save"
But it is actually loading the file, not saving it. (attachment 2)





Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 05, 2017, 05:29:46 pm
1) Can anyone tell me how to extract pictures from PDFs and the little icons on toolbar buttons, etc., like they do to write software/product instruction manuals?
If you have Acrobat, full version, there is usually a menu item to save all images as jpg. I am not familiar with any 3rd party Acrobat tools. Otherwise, you can just view at 100% and take a screen capture - tedious if there are many images...

Or if your budget is lower, GhostScript is the de-factor free-and-open-version. Very technical, but there are some interfaces like muPDF around it.
And many of the other commercial but cheap PDF tools are usually based on Ghostscript, but dumbed down for easy use.

I have not been active with that for a while, so not up to speed which of the cheap ghostscript wrap-arounds is currently best. Last time I used it was Foxit, actually not based on Ghostscript (or hidden very well). But that was years ago.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 05, 2017, 05:42:31 pm
Hi!
1) Can anyone tell me how to extract pictures from PDFs and the little icons on toolbar buttons, etc., like they do to write software/product instruction manuals?

Chris Williams

Dear
I have prepared a simple video for you: (all the tools is free!)
http://s9.picofile.com/file/8311018192/Untitled_2017_11_05_21_01_24.mp4.html (http://s9.picofile.com/file/8311018192/Untitled_2017_11_05_21_01_24.mp4.html)

if you want to extract the icons from any software, you can use Resource hack or any similar software.

Regards
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 05, 2017, 05:54:26 pm
I want to buy a FY6600 Function generator.
in contrast to the Feeltech's AD, the DAC IC is 160MSPS.
now I'm hesitating whether to choose 30MHz or 60MHz versions. Are you satisfied with your 60MHz version? or 30MHz is better?

Best Regards
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 05, 2017, 06:06:38 pm
Inspired by ArthurDents clock remark, I ordered a uBlox NEO-M8N module (arduino ready) for $10.
At the very least I should be able to turn that into a stand-alone 10MHz GPS reference singal, but maybe also add a x5 PLL and make this AWG run of it.
I took the M8N version, because it has flash, so you can configure it once and then hook it in.

If that works, one would have a better then 1ppm (uBlox claims 5ppb) generator as well as frequency counter.
Then all those digits they display (60.000.000.000.000 uHz) actually make sense  ::)

I am thinking a NB3N502 PLL (https://www.onsemi.com/pub/Collateral/NB3N502-D.PDF), because it can do x5 on a 10MHz signal, as well as passes through the original 10MHz buffered. And it is cheap. But if anyone has other suggestions.

Edit: later thinking is a double NB3N502. Because uBlox writes that only 1, 2, 4, 8 MHZ (any division of the internal 48MHz clock) is jitter free, whereas a 10MHz has significant jitter. So 2.5x VCO PLL on 4MHz would clean up an already good base signal. An 2nd x5 would then buffer out the 10MHz as well as provide the 50MHz.

Also, uBlox claims a 5ppm "holdover" precision when the GPS is not locked, so that is pretty much equal to the current 50.0000 VCXO
Probably because they internally use a 48.0000 VCXO themselves.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on November 05, 2017, 06:13:21 pm
now I'm hesitating whether to choose 30MHz or 60MHz versions. Are you satisfied with your 60MHz version? or 30MHz is better?

Just for reference, there's an Ebay seller which ships from Frankfurt ... and he only sells the 60 MHz version. Don't know if that matters to you, but because it's above the custom limit for my country that clinched it for me. I don't want it for MHz signal generation, so that didn't matter to me.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 05, 2017, 06:22:04 pm
Just for reference, there's an Ebay seller which ships from Frankfurt ... and he only sells the 60 MHz version. Don't know if that matters to you, but because it's above the custom limit for my country that clinched it for me. I don't want it for MHz signal generation, so that didn't matter to me.

Yeah, nowadays I just assume and budget for €20 handling + VAT extra when I buy stuff like that. Most off the bigger items are snatched by customs nowadays. Gone are the free days of the 2005~2015 era. However to my surprise, the FY6600 was *not* taxed.

I am sure they did take it out of the queue and must have handled it, because the address label had been tampered with, a new local Dutch one placed on top and it took an unusual (but not impossible) 5 weeks to arrive. (usual is 2 to 4).

But the expected "please pay extra" letter from KPN was not there. I think they could not recognize it from the X-Ray. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 05, 2017, 06:35:48 pm
now I'm hesitating whether to choose 30MHz or 60MHz versions. Are you satisfied with your 60MHz version? or 30MHz is better?

Just for reference, there's an Ebay seller which ships from Frankfurt ... and he only sells the 60 MHz version. Don't know if that matters to you, but because it's above the custom limit for my country that clinched it for me. I don't want it for MHz signal generation, so that didn't matter to me.

there are some sellers in aliexpress. the ship cost is $43,  the total price is $150~$170.
some people here uploaded some pics, the quality based on these pics is good but I'm very concerned about it!  :horse:
you know Chinese manufacturers use very low quality components in their designs! (after 6 month all capacitors, inductors, silkscreen,... will be corrupted)
 
My Brother told me, it's better to buy a Rigol to tune your medical board. (only check AC response and step response, the desired frequency is 10KHz to 20MHz)
for Harmonic distortion and noise analysis I will use other instruments.
I'm a student and don't want to pay money a lot.

Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on November 05, 2017, 06:41:46 pm
I am sure they did take it out of the queue and must have handled it, because the address label had been tampered with, a new local Dutch one placed on top and it took an unusual (but not impossible) 5 weeks to arrive. (usual is 2 to 4).
The one from Frankfurt I ordered Saturday and I got I think Wednesday, so that's another thing to consider.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 05, 2017, 08:17:30 pm
I ordered mine (30MHz version) from Fasttech, they sell both 30 and 60MHz.
Paid 88$ (~75€), with no shipping fees or taxes added.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 05, 2017, 08:33:14 pm
I ordered mine (30MHz version) from Fasttech, they sell both 30 and 60MHz.
Paid 88$ (~75€), with no shipping fees or taxes added.

I have never been seen this website! it seems OK :) the price and shipping cost in the website is lower than aliexpress and other similar.
where is the origin of this website?
Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 06, 2017, 01:55:44 am
Hello,

For FY6600 generators the maximum frequency is valid for the sinusoidal signal, the other signals capping at 20-25 mhz.
The 2 integrated circuits under the aluminum radiator are 4558.
The crystal quartz reference for the Altera Cyclone FPGA is still 50 mhz in FY 6600 and FY2300H.
The output level of the signals is guaranteed stable only on 5 volts, or below.
Sellers always indicate the characteristics, you need to consult them.
Pay attention to customs fees that can be charged by the customs of each country.
By going through the NL post we escape customs taxes since NL is European, that's why the delivery labels are replaced.

Regards,
Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 06, 2017, 05:54:39 am
Hello,

For FY6600 generators the maximum frequency is valid for the sinusoidal signal, the other signals capping at 20-25 mhz.
The 2 integrated circuits under the aluminum radiator are 4558.
The crystal quartz reference for the Altera Cyclone FPGA is still 50 mhz in FY 6600 and FY2300H.

Dear are you sure the IC is 4558?  |O

device has a 1.7 V/?s slew rate
Unity-Gain Bandwidth: 3 MHz Typ
8 nV/?Hz Typ at 1 kHz

The device is a dual general-purpose operational amplifier, with each half electrically similar to the ?A741, except that offset null capability is not provided.
this amplifier ideal for voltage-follower applications. The device is short-circuit protected, and the internal frequency compensation ensures stability without external components.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 06, 2017, 08:31:16 pm
Hi xzswq21
Fasttech is located in Hong Kong.

Regards
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on November 06, 2017, 10:35:15 pm
it's interesting!
*updated
I hope to @Ebel0410 will post the quality of FY6600-30MHz soon :) :popcorn:


for your information:
I want to make a comparison between SDG1010 (Siglent 10MHz), SDG1032x (High quality Siglent 30MHz) and Fy6600!!!  :-DD

inside the SDG1010 (Siglent 10MHz):

(https://www.eevblog.com/forum/reviews/siglent-sdg1010-function-generator-teardown/?action=dlattach;attach=28699;image)
(https://www.eevblog.com/forum/reviews/siglent-sdg1010-function-generator-teardown/?action=dlattach;attach=28723;image)

inside the SDG1032x (High quality Siglent 30MHz):
(https://www.eevblog.com/forum/testgear/siglent-sdg1032x-mini-teardown/?action=dlattach;attach=289348;image)
this is the quality of SDG1032x:
(https://m.media-amazon.com/images/S/aplus-media/vc/90620621-dffb-45d2-a30c-4e98b3453b42._SR970,300_.png)


inside FY6600:
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366988;image)

one of drawback of FY6600 is the LPF is placed before OPAMP.
another thing the Low CMRR of Amp stage (due to design)
(http://s8.picofile.com/file/8311124400/FY6600_6.PNG)
and I don't know about the capacitors type inside FY6600 (at page 4 there are some tech information)
the Layout is very important.
and some area should be ground free!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on November 07, 2017, 12:22:08 am
I ordered mine (30MHz version) from Fasttech, they sell both 30 and 60MHz.
Paid 88$ (~75€), with no shipping fees or taxes added.
Can you look at the jumpers mentioned before? It would be most interesting to see the difference with the 60 MHz version.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 07, 2017, 12:26:55 am
Hello,

For FY6600 generators the maximum frequency is valid for the sinusoidal signal, the other signals capping at 20-25 mhz.
The 2 integrated circuits under the aluminum radiator are 4558.
The crystal quartz reference for the Altera Cyclone FPGA is still 50 mhz in FY 6600 and FY2300H.

Dear are you sure the IC is 4558?  |O

device has a 1.7 V/?s slew rate
Unity-Gain Bandwidth: 3 MHz Typ
8 nV/?Hz Typ at 1 kHz

The device is a dual general-purpose operational amplifier, with each half electrically similar to the ?A741, except that offset null capability is not provided.
this amplifier ideal for voltage-follower applications. The device is short-circuit protected, and the internal frequency compensation ensures stability without external components.

Hello,
On FY2300H 25 mhz they are MC4558 under the aluminum radiator, I looked.

Regards.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 07, 2017, 02:37:15 am
I ordered mine (30MHz version) from Fasttech, they sell both 30 and 60MHz.
Paid 88$ (~75€), with no shipping fees or taxes added.
Can you look at the jumpers mentioned before? It would be most interesting to see the difference with the 60 MHz version.

I followed one of the traces, and its not a setting, but routing the VCO BNC connector to a different trace.
So that is why they are in pairs with one connected (scratchable) and one not connectedd.
Either the BNC plug is connected to one, or to another trace.

I believe something similar is true for the other pair, but something with USB/serial.

IOW, nothing to do with frequency models.
As stated, it would have been too easy if that was how it worked.

So if you want the 60MHz, just shell out an extra $20  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 07, 2017, 03:38:03 am
Hi all,

so I wasn't going to join up but I kept reading posts and watching some great videos from some slightly mad nerd and here I am  ;D

I have just taken delivery of a 30Mhz version Firmware 3.1 which as mentioned here already has an issue with a fairly unhealthy floating AC issue. To go with the ugly it is also very accurate in most other things.

It also has an issue with the DC offset having a consistently increasing error that appears to be firmware/maths related. 'Apparently' according to Feeltech this can be and has been fixed with more recent firmware upgrades but as that means shipping a newly delivered unit to mainland China and back it really isn't worth it.   :-- 

Trying to protect their software IP is I guess the major reason rather than enabling a simple programming header or upload system. If that is the reason then it is a poor one plenty of people out there love a challenge  :-+

First problem as discussed in this thread getting the ac floating voltage down. I was just going to drop an IEC socket in but changed my mind as there is plenty of case room for maybe fitting something else into the box as my electronics space is limited due to other toys. So Switch/Fuse and Socket adapter installed instead.

A quick check around the board, jacks and other metal plugs sees the USB case and all the BNC's sharing a common
 AC floating neutral. So like others I am far from happy plugging it into or onto gear until this is reduced.

Few components to add but the coffee needs roasting (part of what I do)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on November 07, 2017, 04:20:42 am
Could you check the aforementioned jumpers?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 07, 2017, 04:54:53 am
I am assuming you mean the jumper from the power supply to main board?

All the terminals (including internal ground) are currently sitting at 32Vac at 50hz. I will be able to spend some more time looking at the board later.

Edit

went back a page. Gather you were now referring to the board jumbers J6, J10-12. They are the same settings as previously mentioned on mine.

2nd edit.

This makes for some interesting reading on the power supply design. https://www.eevblog.com/forum/projects/rm6203-switching-psu-controller/ (https://www.eevblog.com/forum/projects/rm6203-switching-psu-controller/)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 07, 2017, 07:04:03 am
I am assuming you mean the jumper from the power supply to main board?

Actually, I find the question on what "leakage voltage" you measure on the supply lines and/or BNC ground also interesting.
And maybe also how much the leakage voltage drops when grounding with a 1M, 100K, 1K resistor to ground. (iow, how current much the leakage can actually source)

As to your "where does the yellow one go" picture title? Is that a question?

If so, I saw someone claim that the 3 holes on the power board, shown pretty just below much dead-centre on your "Feeltech-stock.jpg" image (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=367724;image), are ground connections.

And this guy (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1275521/#msg1275521) suggests maybe in stead of directly grounding it, using a Y cap. Maybe even a switch and a Y cap, so you can choose whether you want floating or fixed.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 07, 2017, 07:12:34 am
Based on a little reading on Class Y leakage and the RM6203 I am leaning toward connecting a 10nF cap from the secondary to earth. The idea of a hard switched internal ground to earth is an easy answer but it then places some operational limits on the device.

I do have an order to put into E14 in the next few days so I am going to add some 'proper' Class Y caps and swap out the current one and see if that helps too.

Fall back is to dump the cheapo power supply and fit a better one  :horse:

Just checked the underside of the board. Of the 3 holes in the pic the two outside are indeed connected to the virtual ground, the centre one has no copper around it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maddin on November 07, 2017, 07:33:52 pm
I found this interesting infos regarding Y capacitor:

https://electronics.stackexchange.com/questions/216959/what-does-the-y-capacitor-in-a-smps-do

If you don't like hard switche internal ground to earth the guy suggested using two capacitors, one from the output to mains earth and one from mains earth to the input.
Maybe the best way also for the FY6600. Anybody tried this solution ? What capacitors were used ?

Regards
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: wilhe_jo on November 07, 2017, 07:47:57 pm
For all of you searching for the CD contents....

http://www.feeltech.net/html/list_6.htm (http://www.feeltech.net/html/list_6.htm) brings you to http://www.feeltech.net/html/show_71.htm (http://www.feeltech.net/html/show_71.htm) which lets you download the RAR archive :)

vy 73
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maddin on November 07, 2017, 08:39:02 pm
Included FY6600 PC Software V5.3.exe seems also be improved; no virus found  :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 07, 2017, 10:58:36 pm
10nF cap to from the secondary side of the Y cap to mains earth.

Result is a much better 9V at 50hZ. Some more playing needed but first COFFEE  :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: battlecoder on November 07, 2017, 11:16:08 pm
After stalking the forums for a few days I decided to join the community.
Initially to thank all of you for sharing your tests and research on this device.

I think I'll be ordering one this week, and will try to contribute to this thread as soon as I get mine.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on November 07, 2017, 11:18:07 pm
Welcome to the forum, battlecoder!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 08, 2017, 01:24:45 am
A little bodgetronics later  :o Instrument ground sits at about 3V ac maximum interestingly the Agilent is now reading it at 35kHz (checked on a handheld non rms reads 3.4V)  :-//

There is a little patch of unused board conveniently located right next to the secondaries of the transformer. 2mm screw, shakeproof washer and knurl nut as an earth point. A 10nF ceramic cap and a little heatshrink to each of the transformer secondaries.

Screen of the transient Earth to Virtual Ground below.

Out of ideas or improvements for now. Anyone else suggest an better option?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 08, 2017, 04:36:22 am
Scrapped all but the one Cap from the Y cap to Earth. The transients on the power supply were ugly and while the measured AC was down not a good solution I feel.

So out with my dodgy Hantek. What is interesting is that as soon as it is connected the before measured 7-9V ac all but dissipates. Earth to VG drops straight down to mV as per CH2. This is backed up by the Agilent in terms of DC offset of about -50mV Earth to VG and a spread of AC hash in measured the order of 150mV.

Frequency is bang on on both instruments at 10kHz (10,004 Agilent). Amplitude on the Hantek says 5.2V P-P, Agilent at 1.814 (5.13) for a figure of 5V on the Generator. Waveform looks nice and clean and Symmetrical. (with the single extra cap to earth).

Right now considering looking for a new power supply  :horse:

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: battlecoder on November 08, 2017, 04:48:38 am
Right now considering looking for a new power supply  :horse:

That seems to be the best way of dealing with this, unfortunately.
Other similar generators from Feeltech have this issue (e.g: The FY3200) and a DIY linear supply seems to be the best way of fixing. I do recall there was a video on youtube showing exactly this.
EDIT: https://www.youtube.com/watch?v=ML-lmuHoh-0 (https://www.youtube.com/watch?v=ML-lmuHoh-0)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 08, 2017, 05:56:08 am
Linear makes lots of sense.  :palm:

Dropped a 100k Bleeder Resistor from VG to Earth 2.5V ac and virtually nil DC as to be expected. Tried 500k and 1M but not much of a drop in AC. For reading Good enough for Keysight then good enough for Feeltech  :horse: http://powersupply.blogs.keysight.com/2014/11/why-do-i-measure-voltage-to-earth.html (http://powersupply.blogs.keysight.com/2014/11/why-do-i-measure-voltage-to-earth.html)

Back at this sort of voltage should make it safe for 'most' uses and users. Certainly a lot better than the garbage without it.

For my own use I am fairly happy now at this as when loaded with my just the DSO and bleeder/cap it drops way below these figures at 15mV AC and -50mV dc. Most likely won't look at a new supply at this stage.

***** Earth to VG is now at 20mV/div
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 08, 2017, 06:47:34 am
I was about to suggest you are overenginering, and should check what it can source and/or add a resistor, when I got notification of a new post.

Linear makes lots of sense.  :palm:

I don't know man. Did you see on the video that even with Linear he also still has an AC leakage of 12V (https://youtu.be/ML-lmuHoh-0?t=1600) Thats much more than what you have right now, despite his linear supply.

I think what you have now is a very good balance between simplistic and effective, and I will copy it.
The only think I might try is a 1M resister instead of a 100K, you said you tried but I did not quite understood the result.

I am not at home right now, otherwise I would be testing myself.  This thread seems to make it all very important, but I just did not pay attention before and everything seems to work. That is why I think that the 'floating' cannot really source any current, and we are being oversensitive.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 08, 2017, 07:01:53 am
I guess I have fried and seen enough things fried by ordinary design and attention to detail over the years. Haven't watched the video yet either.

Apart from a new supply it was always just a matter of 'some' filtering on the basis it is never going to be perfect but just where and what needed some educated blind guesswork. Given the bad start point and the low cost to big improvement well worth it for anyone with this supply. I will still fit up a different Y cap when they arrive.

Let us know what you find with the 1M, I have put the lid back on mine for now and will use it as is and have a proper play.  8)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: battlecoder on November 08, 2017, 07:20:54 am
I don't know man. Did you see on the video that even with Linear he also still has an AC leakage of 12V (https://youtu.be/ML-lmuHoh-0?t=1600) Thats much more than what you have right now, despite his linear supply.

I think what you have now is a very good balance between simplistic and effective, and I will copy it.
The only think I might try is a 1M resister instead of a 100K, you said you tried but I did not quite understood the result.

I am not at home right now, otherwise I would be testing myself.  This thread seems to make it all very important, but I just did not pay attention before and everything seems to work. That is why I think that the 'floating' cannot really source any current, and we are being oversensitive.
In defense of the mod suggested on the video, it was 12VAC but virtually 0 current (below 1 uA, apparently).

Anyway, I suspect that the optimal (or "good enough" solution) will be different for every user, depending on what they will be using the device for, and whatever lets them sleep at night.
For instance, I'll most likely follow the steps of beanflying and yourself, and simply use a bleeder resistor, because it's simple and apparently works a treat, but I'm sure a number of users would prefer to ditch the switching supply entirely and put a linear one in there.

I still hope that the unit I receive will not leak badly. It happened with the FY3200 that users were getting different voltage and current values for the "leak" (probably different hardware revisions, but could also be related to the difference in mains voltage and frequency between countries).
I guess it's like they say: "Your leakage may vary".
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 08, 2017, 10:47:03 am
It happened with the FY3200 that users were getting different voltage and...

Well, it also depends on your measuring equipment. Using 240V mains base (UK), measuring a 12V AC signal with a DMM that has a 10M impedance would imply a "leakage" of 200MOhm (ok, 190M), either restive or reactive. And there will always be some capacitance, so some reactive impedance.
Someone else measuring the exact same device with a DMM of 1M impedance would find 1.2V

... and current values for the "leak"

which is thus much more relevant. What current can the "leak" source. I plan to measure it as soon as I get home, but no-one else seemed to have supplied numbers here (maybe I have missed them). Which is why I suggested we should be a little more relaxed before bashing the power supply and adding deceased animal abuse symbols. At the very least until we have leakage current measurements.

Especially because the DC findings from @beanflying suggest a <10mV at 100KOhm measure impedance. Even though that was ground to virtual ground, it does suggest a better then 2400MOhm DC (non reactive, restive, please check my math) impedance on the mains-secondary-virtualground-ground path. 2.4GOhm ! Which if true means quite the opposite of the impression that this thread may be giving people.
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on November 08, 2017, 11:07:31 am
I think that at the end of the day a decent linear power supply would certainly eliminate most of the leakage and if it really was a major concern, then it would not take too much to rig up a battery power pack option to completely remove the leakage to ground and thus the potential difference and problems arising from it? The current draw surely is not going to be that great is it?   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 08, 2017, 12:44:47 pm
Nothing essentially wrong with switch mode power supplies. My 8 year old 15V 60A Switch mode Manson still runs at less than 5mV ripple in spite of plenty of kwality Capxom Caps. My Fixed 12V 20A bench supply (Chinese LED driver $25) is under 20mV and the VG on it is under 6V ac but using a little of what I have learned here I will have a look at improving it a bit too.

Dead animal flogging or not the power supply used here can and should be improved as it is sub standard for test equipment. It seems that if the same issue with earlier models has just flowed into this one then without making a little noise will likely see it continue in future production and models.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 09, 2017, 02:48:52 am
After reading some of the other replies I have come up with a plan for the mods I want to try. First I measured the voltages on the stock power supply and measured +4.78, +13.6, and -13.8 which isn’t that close to the +5, +12, and -12 that it should be putting out - certainly not the best supply. Most good SMPS units have an adjustment that trims the +5 and the other two voltages are just kind of a ratio from the +5.00 so they aren’t as close but generally within +/- .2 volt.  Obviously the FY6600 worked with the existing P.S. but I wanted something closer so that meant changing supplies.

 I also wanted to change the timebase which is worse than 100 PPM and 50 Mhz so I figured I’d use a decent square wave 10 Mhz OCXO followed by a 50 Mhz passive bandpass filter to use the 5th harmonic from the square wave but CyberMaus mentioned the NB3N502 PLL IC that I didn’t know about and it looks like the perfect solution.  I didn’t want to incorporate a GPS into the unit (I have several different ones running 24/7) so decided to use an OCXO from a Trimble Thunderbolt that is fast warm-up and very stable. Power required at +12 cold is .7 amp so the existing P.S. wouldn’t have worked anyway. I’ll include a switch on the back panel so if I want to make use of the resolution the FY6600 is capable of at GPS or rubidium accuracy I can feed an external input to the X5 PLL. 

 So I’ve ordered a couple of NB3N502 PLL chips from Mouser that should be here any day now and I can get to removing the 50 MHZ SMD crappy oscillator and Frankenstein the PLL chip on the board in place of the 50 Mhz oscillator and put the OXCO on a small circuit board with a ten-turn pot to trim it on the back panel next to the switch and BNC for my external 10 Mhz reference.
 
 I have already changed power supplies and the one I chose is heftier than needed but is high quality and I had a few new ones I could use. The supply is a NFS40-7608 which is made by several venders and I bought the supplies I have from a surplus catalog at a good price.  So here is a photo of the power supply mounted in the case and working. I had to cut and splice the connector cable but it works as intended and I'll do an update once I get the rest of the modification done.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 09, 2017, 03:40:12 am
Fits Nicely :)

I gather looking at the photo you are running with Mains Earth directly to Virtual Ground?

May be there is a newer model of this supply available too. Some details and world wide vendors lists of that one https://www.artesyn.com/power/power-supplies/websheet/222/nlp40-series#stock (https://www.artesyn.com/power/power-supplies/websheet/222/nlp40-series#stock)

(https://i.imgur.com/uYsPzXY.gif)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 10, 2017, 09:58:42 pm
In my last post I said what I planned to do to modify the timebase for far greater accuracy and promised an update. Well the 3N502 PLL frequency multiplier chips I ordered came today so I tried to remove the 50 Mhz SMD oscillator and install one of the chips. It was kind of tricky because I don’t have a desolder tool so I made a small 4-tined ‘fork’ with offset legs made out of 1-watt resistor leads connected to the tip of my soldering iron that would heat all 4 pads of the oscillator simultaneously and it came off without any damage. As it works out, there isn’t much you have to do to install the chip and it worked perfectly once installed. I connected one of my GPS standards to the 10 Mhz input to the chip and got the expected 50 Mhz out of the installed chip. I then set the output of the FY6600 to 10.12345678 Mhz and measured it on my counter and the photo shows the output is correct to all 10 displayed digits.  Great!

The pins on the installed 3N502 chip that aren’t used I just bent out straight.  The resist on the ground plane under pin 7 had to be scraped so that pin could be soldered to ground. Pin 2 is connected to the 3.3 V pad on the board with a piece of #30 wire and a cap is connected from pin 2 to ground as recommended. The output on pin 5 is soldered directly to the pad underneath it because that run already has a resistor in series with the output that is also recommended in the spec sheet for the chip. The yellow 10 Mhz input wire was just tacked to pin 1 and that will be cleaned up in the final version. 

I still have to install the OXCO I’ll be using along with the associated BNC connector, trim pot, and switch but I had to test the timebase multiplier chip to see if it would do what I hoped it would and I’ll include another update when that’s done and the mods are all complete. I do want to thank CyberMaus again for finding the 3N502 chip because it works great. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 11, 2017, 02:02:21 am
Back from vacation and sitting in the post office was my F&6600 60MHz. Works fine and as expected. 50V AC on the output grounds... as expected. I'll add a grounded power connector and a Y cap/resistor pair to ground and call it a day. Nice to see so much interest in the unit.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 11, 2017, 02:36:41 am
I then set the output of the FY6600 to 10.12345678 Mhz and measured it on my counter and the photo shows the output is correct to all 10 displayed digits.  Great!
Correct 10 digits to 0.01Hz. That is great.  :-+ What absolute precision do you think your GPS have?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on November 11, 2017, 02:39:04 am
In my last post I said what I planned to do to modify the timebase for far greater accuracy and promised an update. Well the 3N502 PLL frequency multiplier chips I ordered came today so I tried to remove the 50 Mhz SMD oscillator and install one of the chips. It was kind of tricky because I don’t have a desolder tool so I made a small 4-tined ‘fork’ with offset legs made out of 1-watt resistor leads connected to the tip of my soldering iron that would heat all 4 pads of the oscillator simultaneously and it came off without any damage. As it works out, there isn’t much you have to do to install the chip and it worked perfectly once installed. I connected one of my GPS standards to the 10 Mhz input to the chip and got the expected 50 Mhz out of the installed chip. I then set the output of the FY6600 to 10.12345678 Mhz and measured it on my counter and the photo shows the output is correct to all 10 displayed digits.  Great!

The pins on the installed 3N502 chip that aren’t used I just bent out straight.  The resist on the ground plane under pin 7 had to be scraped so that pin could be soldered to ground. Pin 2 is connected to the 3.3 V pad on the board with a piece of #30 wire and a cap is connected from pin 2 to ground as recommended. The output on pin 5 is soldered directly to the pad underneath it because that run already has a resistor in series with the output that is also recommended in the spec sheet for the chip. The yellow 10 Mhz input wire was just tacked to pin 1 and that will be cleaned up in the final version. 

I still have to install the OXCO I’ll be using along with the associated BNC connector, trim pot, and switch but I had to test the timebase multiplier chip to see if it would do what I hoped it would and I’ll include another update when that’s done and the mods are all complete. I do want to thank CyberMaus again for finding the 3N502 chip because it works great.
Can you tell us a little more about that sweet counter in the picture? The internet seems to be having trouble telling me about it. Is it a universal counter too?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sorin on November 11, 2017, 02:56:12 am
http://www.es-france.com/pdf/pd_cnt81_81r.pdf (http://www.es-france.com/pdf/pd_cnt81_81r.pdf)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 11, 2017, 03:16:41 am
Identical to FLUKE PM6681 (https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwj8jruWx7XXAhVpIsAKHVReCD4QFggoMAA&url=http%3A%2F%2Fwww.testequipmenthq.com%2Fdatasheets%2FFLUKE-PM6681-Datasheet.pdf&usg=AOvVaw30eIFkJ864r2NdmPuRgvs1)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 11, 2017, 07:20:11 pm
Ok, so I do not think we will ever reach full concensus, but because I said I would, I went and measured current as well as voltage on a range of devices.
See attached table with AC values. DC was always 0 for all, so I did not even add it to the table, my basis is a 230V 50Hz mains

My conclusion: the FY6600 is indeed not the best (and I focus mostly on current) but in fact the Rigol DS1074Z is a lot worse. If you disconnect the earth.
And if you do connect them both to earth, again the Rigol is worse.

For the rest, the official Samsung USB is the best, by far, followed by my cheapo china linear bench supply.
In fact, the Samsung is so good, I had to doublecheck my DMM had not stopped working.
I measured some more cheapo supplies, but stopped writing them down, most are similar to the FY6600.

What I have learned from this is that if at all possible, I should avoid using my Rigol in "fake differential" mode by disconnecting the earth. I have done that in the past, have a special cable for it. I will modify that cable to also have the Y-cap (actually X2 because I have those) and 1M resistor, and use it sparingly. Yes, go ahead and scold me for it.
If only the math function (A-B) on the rigol was not so annoyingly slow.

The FY6600 will get a X2 and 1M, pretty much like beanflying, but also a switch so that most of the time it is simply fully grounded and not floating at all.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 11, 2017, 07:36:22 pm
I desoldered the mains leg of the Y cap and added a 10nf Y cap (that's what I have) from the mains side to the free leg of the original cap and then grounded the joined legs of the caps. Now getting 2.2VAC on low-z and a handful of uA (into the noise). This will be my default "floating" and then add a switch to fully ground the output.

Adding the grounded IEC was easy as the back panel is very thin and a dremel cuts through it like a knife through butter. Note that the original cable and socket are not even polarized.  ::)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on November 12, 2017, 05:50:54 am
For the rest, the official Samsung USB is the best, by far, followed by my cheapo china linear bench supply.
In fact, the Samsung is so good, I had to doublecheck my DMM had not stopped working.

That is really good. What was the arrangement in their supply (or is it inconveniently welded shut)?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 12, 2017, 04:03:25 pm
Well I believe I’m pretty much finished with the modifications to my FY660.  I’ll answer a couple of questions that popped up concerning my equipment or what I did then show some photos of the finished product.

As to testing this FY6600 using my GPSDOs as standards and how ‘accurate’ they are, what I have is two 26 dB gain GPS antennas at the opposite ends of my roof that drive two GPS distribution amps to allow me to run and test multiple GPS receivers simultaneously. I had sold about 200 Trimble Thunderbolts GPSDOs in the past which is one reason for the setup I have. As to the accuracy of my GPS system, long term it is about as accurate as the GPS source and short term the 10 Mhz output stays within a couple hundred PPT worse case. A 25-year old rubidium standard I have has better short term stability but a couple of my crystal standards have less noise and very good short term stability.  For most stuff all this is far more accurate and stable than I would ever need but you gotta have neat toys, right?

I have carried the physical ground from the power cord right through on the FY6600 and almost every piece of equipment I own comes grounded that same way.  The only place I ever had to be concerned about ground loops was a place I worked where we tested (sometimes very destructively) products with high voltage/current pulses a few microseconds long and with current spikes of 20,000 amps. Even with the heavy copper bus bars for grounding we had to pay careful attention to using a common ground point so the readings we took weren’t influenced by the voltage drop across these massive copper bars.

The Fluke/Philips 6681 or Pendulum CNT-81 counters I use are excellent counters that let me display the 10 Mhz frequency I am generally interested in directly to 10 digits (2 decimal places) in one second or by using the built in math function to 5 decimal places in 10 seconds which is perhaps giving me more resolution than accuracy, but not by much.  I have a saved function on the counters that subtracts 9,999,999hz from the 10,000,000 Hz signal. If the test 10 Mhz input is exactly equal to the 10 Mhz external reference from my standards, in 10 seconds the counter will display 1.00000 or 5 decimal places (ignore the 1, it just helps the display format).  I generally also feed the same signal into my scope which is externally triggered by my same external 10 Mhz standard and check for drift at 2 ns/div giving me a visual indication as well. 

Why the 50 Mhz timebase in the FY6600 bugged me so much is that the frequency output can be set to 14 digits but the timebase was only accurate to about 5 digits. Also it wasn’t stable or trimable. With the top cover off the FY6600 and the output set to 10 Mhz and displayed on a scope triggered from an external 10 Mhz standard, if you just blew across the 50 Mhz oscillator you would see the frequency change rapidly and drastically. The OXCO I built into the FY6600 looks very good after warm-up and I can always use an external 10 Mhz reference if I want more accuracy and stability. Here is what the frequency output set to 10 Mhz (and the oscillator) looks like on warm-up after having been trimmed previously.  Start-up  -200hz ; 3min +.05 ; 20min +.01 ; 30min onward +/-.005hz or +/-5 at the 11th digit. Because the rear switch on the FY6600 turns the power supply on/off and the front panel power switch just puts the main board in standby mode, if you leave the rear switch on the OXCO is always powered and you eliminate the warm-up period. Generally the longer a good crystal oscillator is left on the more stable it becomes and some of the better standards I have take over 2 weeks to really stabilize. Using a TXCO with low power supply current requirements instead of an OXCO like I used could allow you to use the existing SMPS with some loss of accuracy and stability if you want to keep the modifications simpler.

The photos show the back panel with the added BNC connector for 10 Mhz ext ref in, the int/ext switch, and the recessed trimpot. Unfortunately installing these parts covered some of the text on the rear panel but I can live with that. Perhaps a small SMA connector and a smaller switch would be a better choice. The inside photo of that area shows how the OXCO is mounted on a phenolic board that was hand wired and that board mounted on the aluminum bracket held to the rear panel by the BNC connector and the switch mounting hardware.  There are a few resistors near the switch to adjust the levels the PLL chip sees from the OXCO and the ext ref and I may add a buffer to further protect the PLL chip from possible input spikes from any ext ref. The 3rd photo shows the sub-miniature Teflon coax I securely soldered to the ground plane near the PLL chip and the center wire soldered to the input pin. It was important that there was little strain on that cable so it wouldn’t rip off and break the input pin off the PLL chip.
 
Sorry for being longwinded but I hope this explanation helps others decide what they want to do and what is important to their needs.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 12, 2017, 06:28:13 pm
So your stated credentials are such that I have to assume you know your way around time standards. So please consider these questions as education for me, and not as questioning your setup.

As to the accuracy of my GPS system, long term it is about as accurate as the GPS source and short term the 10 Mhz output stays within a couple hundred nanoseconds worse case.

So a couple of "a couple hundred nanoseconds" does not actually sound very precise. When I read the NEO-M8N specs, it mentions 30ns, but graphs in the application note (https://www.u-blox.com/sites/default/files/products/documents/Timing_AppNote_%28GPS.G6-X-11007%29.pdf?utm_source=en%2Fimages%2Fdownloads%2FProduct_Docs%2FTiming_AppNote_%28GPS.G6-X-11007%29.pdf) show this to be -17/+13ns on a 1pps pulse, mostly due to quantification of the internal 48MHz TCXO.

So am I interpreting this wrong, or is your GPS older and not very precise when compared to recent GPS modules?

The application note also lists other precisions, like 0.062ppb frequency stability (maybe very long term?) and a 4E-9 (4ppb) Allen deviation at 1 sec, and I cannot make heads or tails of the sub second precision expressed in spectrum graph, though I do see it is based on a 24MHz signal with only 3.046ns jitter.
Which I am hopefully interpreting as possible to get 3ns precision, if you stay with an integer division of 48MHz timepulse, which is also advised in the summery of the application note.

Could I tempt you to read the application note, and give me your though on it.


I could not find a local source (only potted modules for drones), so am waiting for china, but alas, ebay kicked out my seller, so I had to re-order, and wait even more.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 12, 2017, 07:28:50 pm
Cybermaus, when you say: "So a couple of "a couple hundred nanoseconds" does not actually sound very precise." you are correct. I have corrected that reference in my previous post after reading your comment. The line should have read "PPT" for parts per trillion, not nanoseconds. Generally the time instability is 2 ns or less. Sorry for the screw up and thanks for picking it up. Here is a 10 hour graph that shows the 10 Mhz output stability of one of the Nortel/Lucent GPSTMs that I modify.
Title: Re : FeelTech FY6600 60MHz 2 canaux VCO fonction générateur de signaux arbitraires Signal
Post by: Ebel0410 on November 12, 2017, 07:46:58 pm
Just ordered on eBay a TCXO 25MHz and 5x ICS511M for a total amount of 10$.
This TCXO is announced better than 1ppm (it means 0,0001%) and it can be trimmed +/-5ppm around 25.000MHz.
I hope that the ICS511 (used as frequency doubler) will not introduce too much jitter.

The frequency tested on the stock CXO 50.000 XTAL in my FY6600 is 50.000.492Hz,

I'll keep you posted when I'll receive them.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 13, 2017, 12:08:01 am
Following the lead of others, I am also looking at building a TCXO and PLL with maybe an optional 10MHz input. Might be a nice add-in board kit for someone to design. Apart from the PSU, the timebase is the other major weak part of this device.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 13, 2017, 02:20:56 am
And to think all I wanted was a 'cheap' signal generator that worked  :palm:

Nice work on the mods all  :clap:

off to look at 'cheap' spectrum analyzers next .........
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 13, 2017, 02:46:10 am
And to think all I wanted was a 'cheap' signal generator that worked  :palm:

Nice work on the mods all  :clap:

off to look at 'cheap' spectrum analyzers next .........

Yeah... to be fair, I knew about the PSU going in and its not an expensive nor time consuming mod. The poor time base is a disappointment but the added cost is not huge, although it may require more time to complete. I hope Feeltech is paying attention here. They could have a real killer AWG for the money with a few small changes.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 13, 2017, 06:18:34 am
Hello, everyone,
I just finished my modifications of the fy6600:

1. Replaced the power supply with a linear one. The voltage was increased to +-15V because +-12V does not give enough headroom for the output amplifier to be able to go all the way up to the maximum amplitude of 20Vpp (or, rather 10Vpp into 50 Ohms).

2. Then, I replaced the dodgy output amplifier op-amp. The original one is an unknown 30021. At first I thought this is a dual variant of the single THS3001 but some guy has inquired about it from Texas Instruments and they replied that they do not manufacture such. So, who knows what FeelTech uses here. Therefore, I chose to replace it with two single THS3095 op-amps. Thankfully, the board has places ready for them, with all bypassing and anything needed. Beauty! This change (and, of course, new +-15V power supply) now lets the generator output full 10Vpp into 50 Ohms with no distortion (the original 30021 would go only to somewhere above 7Vpp and heavily clipped, and increasing power supply did not do much).

3. Some other mods - changed the output amplifier heatsink to a larger one, added a small heatsink to the FPGA, added a 12V fan (I run it from 8V, so it is quiet; a separate power supply for the fan, because connecting a fan to the 5V or 15V rail will affect the performance of the generator).

Here is the list of pictures:
1. Original board with the dodgy 30021 op amp.
2. Modified board with two THS3095 op amps.
3. 1M sinewave at full amplitude of 10Vpp into 50 Ohms termination.
4, 5. 1M sinewave at 5Vpp and 20Vpp. In both, harmonics are -60dB down. Beauty!
6. Modified internals.
7. 1M sinewave AM modulated with the 1K signal from the second channel.
Cheers!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 13, 2017, 04:17:48 pm
Nice work but won't the presence of a fan affect the 50Mhz time base?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 13, 2017, 04:56:51 pm
Just picked this up from the manual:

"Use the process, long press the parameter adjustment knob (OK button), you
can quickly save the instrument output parameters, the next boot,
automatically load the saved parameters."

And it actually works, except (Feeltech, if you read, please take note!)
- There is absolutely no feedback that the save has happened. No beep, no message.
- It saves the waveform, but it does not save if the channels are active or not. I feel if for example Ch2 is inactive during save, it should also be inactive after reboot.

Still, a useful bit of info I thought.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 13, 2017, 05:08:49 pm
Checking @Vytautas: Indeed, 20Vpp at high-z is OK, but at 50R is at 7.x V only, and looks to have very rounded domes.

But is that due to the 12V supply (actually about 14.8), or due to the "donky" OpAmp? It must step up the 12V to 22V anyway, because at high-z I can even add 1.5V offset before clipping starts, getting a nice shape up to 21.5V and -21.5V

Also, 20Vpp at high-z, it looks perfect sine (eyeballing) up until 3MHz or so, then it starts to visibly distort. Hence I was reading the manual to check if the 20Vpp was supposed to be up to what frequency. But it automatically steps down to 5Vpp at 20MHz. I wonder if @Vytautas can check that with his new OpAmps.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 13, 2017, 06:17:40 pm
Hi, cybermaus,
The problem is mostly due to the "30021" op amp. As you say, it is only just above 7Vpp into 50 ohms. And I had tried at first powering the generator from my lab supply with +-15V. The improvement was miserable if any. So, it must be the op amp.

With the THS3095 the generator easily outputs 20Vpp (10Vpp into 50R), no problem. Still, if to be picky, the behavior of the THS3095 is in line with what the manufacturer shows in their datasheet for the component. The pictures bellow are taken from the datasheet. At high frequencies, as those graphs also show, I see some distortion (not clipping though but exactly the same as manufacturer graphs show). The manufacturer suggests properly paralleling two op-amps for each channel (second picture) to remove most of the distortion. That is what major manufacturers, like Siglent, and others do in their designs. For the sake of interest, I might have a look at that later (accidentally, I do have two more THS3095s in my drawer). By the way, Texas Instruments have recently introduced a new power opamp - THS3491. If what they say is true, that one is a real beast with unmatched performance. But they do not have them yet.

Sure, the generator steps down to 5Vpp at 20MHz. But that is to be expected. Normal behavior. Difficult to achieve frequent swings at high voltages.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 13, 2017, 06:23:56 pm
Nice work but won't the presence of a fan affect the 50Mhz time base?

Why would you think it would?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 13, 2017, 06:29:30 pm
Nice work but won't the presence of a fan affect the 50Mhz time base?

Why would you think it would?

A previous poster has noted that just blowing on the oscillator changes the frequency. It appears to have poor temp stability.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 13, 2017, 06:33:19 pm
Sorry, my question was not properly constructed:

"Also, 20Vpp at high-z, it looks perfect sine (eyeballing) up until 3MHz or so, then it starts to visibly distort. Hence I was reading the manual to check if the 20Vpp was supposed to be up to what frequency. But it automatically steps down to 5Vpp at 20MHz. I wonder if @Vytautas can check that with his new OpAmps."

I did not mean to ask if it also stepped down to 5Vpp, because that is kinda obvious.
Instead I meant: Can you check with your new Op-Amps if the range from 3MHz to 20MHz in high-z is still so horribly distorted, or did that improve with those op-amps.

And now I have a new question, based on your graphs: the old op-amps had a pretty good high frequency signal at lower voltages. @Ebel0410 showed -44dB
Are you saying that is now worse with your new opamp, or are those errors only at full voltage swing?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 13, 2017, 07:26:26 pm
Rest assured, the performance with the new op amps is way better.
Here are some of the photos - 3MHz, 20MHz, 30MHz, 60MHz - at maximum possible amplitude. Left is High-Z, right - 50 ohms terminated.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 13, 2017, 07:41:43 pm
Do the upcoming 3491's share the same footprint? Might make a good future upgrade.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 13, 2017, 07:48:42 pm
Yes, they are a direct pin compatible replacement for the 3095 with performance figures hard to believe. Lets see. They certainly should become a worth replacement.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 13, 2017, 07:51:32 pm
Here Texas Instruments have a comparison table:
http://www.ti.com/product/THS3491 (http://www.ti.com/product/THS3491)
Better BW, better slew rate,  better noise performance.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 14, 2017, 10:41:16 am
Hi, cybermouse,
Just to be sure, I tried powering the modified board with new op amps from the original switching power supply. Sure enough, the waveform is clipped and heavily distorted in high amplitude settings. So, the voltage from that supply is not enough. +-15V is a must (no wonder, this is to be expected).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 14, 2017, 10:56:17 am
Ok, noted. Not sure how mine does the high impedance 20Vpp then, but noted anyway.

So just to make clear: You state to have a +-15V linear transformer, but are feeding linear regulated (79/7815, so +-15V) to the device? Or are you regulating higher, using the  sqrt(2)*15V=21V peaks?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 14, 2017, 11:36:06 am
Ok, noted. Not sure how mine does the high impedance 20Vpp then, but noted anyway.

So just to make clear: You state to have a +-15V linear transformer, but are feeding linear regulated (79/7815, so +-15V) to the device? Or are you regulating higher, using the  sqrt(2)*15V=21V peaks?

I am using a 20V linear tranformers (more precisely, two 9,8V windings of the transformer in series) and regulating with LM317 and LM337 regulators both for +-15V and +5V (these, actually, have a better noise performance than 7915/7815s). The voltage stays +-15V under load, naturally.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 14, 2017, 12:11:18 pm
By the way, this is the schematic of my +-15V rail. It is, sure, an overkill. But I like overkills  :palm:
16V AC enough to drive it. Or, alternatyvely, two 15 AC windings could be used for full wave rectification.
Cheers!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 14, 2017, 12:53:01 pm
 :wtf: I now have additional questions.

You seem to have it working, so I must be missing some trick.
How are you getting 16V peak out of 9.8Vrms?
What are those 100R R1,R2, C5,C6 doing there, are they not dropping voltage even more?
Also, what is that 10R R7 doing?

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 14, 2017, 01:02:05 pm
Not out of 9.8V but out of 19.6V. As I mentioned the double 9.8V windings are connected in series to get 19.6V. Both transformers you see in the image have DUAL 9.8V windings (and other windings which I use for the +5V rail).
Concerning the components, if you want to read more about a similar supply design, welcome to see here:
http://sound.whsites.net/project05b.htm (http://sound.whsites.net/project05b.htm)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 14, 2017, 01:08:19 pm
Ah! I stupidly assumed the other one was the 5V trafo.

I read you had them in series, but even that I had read as in series and centre tapped.
I guess your unique transformer selection means they all come from the leftover bin.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 14, 2017, 01:21:12 pm
Of course, left over. If I were richer, I might have well purchased a fancy Agilent or Tektronix generator  :o
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 15, 2017, 01:35:02 am
My x1 y1 Vishays turned up today. Same esr for the stock and vishay and in the end the same sorts of voltages to mains earth.

I went back over the 1M, 470k, and the 100k resistors from virtual ground to mains earth and the 100k as before gave the lowest result at under 3Vac again.

So nothing new I guess. Must look back at the better quality mods now  8)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 15, 2017, 03:34:37 am
Firstly I know ZERO about Cyclone chips but has anyone got any thoughts on the possibility of downloading and or upgrading the firmware without this ridiculous 'must be sent back to the factory for upgrade'?

My reason is this seems this version 2.9 is consistantly higher on output than indicated on both DC offset and AC waveforms at least. I haven't looked more comprehensively at the other waves and such or pushed the limits of the unit.

My Hantek Scope backs up my Agilent and double checked against one of my Victors on this.

5Vac p-p (1.768 RMS) 50hZ indicated (Victor 86B 1.842 49.98Hz) (Agilent 1.8396 50.001Hz)
5Vac p-p (1.768 RMS) 1kHz indicated (Victor 86B 1.826 0.999kHz) (Agilent 1.8394 1.00004kHz)
5Vac p-p (1.768 RMS) 10kHz indicated (Victor 86B 1.128** 9.99kHz) (Agilent 1.835 10.0004kHz)

The real problem becomes when you add a small DC offset to it as per the picture below.

Same series of Voltages and Frequencies as above with a "2Vdc" offset just with the Agilent. Not sure if the small drop off in AC voltage is power supply or maybe meter waveform integration related?

50Hz  1.798ac 50.002Hz 2.2215Vdc
1K 1.797ac 10.00004kHz 2.2212Vdc
10k 1.793ac 10.00004kHz 2.2206Vdc

Even when I drop the Amplitude and Frequency off to Zero it still reads 2.178Vdc (ac circa 0.06mV) apparently this is a firmware calibration issue hence the first question.  :-//
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 15, 2017, 06:43:10 am
Measured my values to compare, on a 3.1 version
Note that if these devices are calibrated, that would also be in the flash, and more relevant then the version.

I do not have such a nice bench meter, but here is what I measured:

5Vpp + 0Vdc, pretty consistent for 10KHz 1KHz 50Hz
5.3Vpp (scope)
1.77Vrms on my trueRMS BXM9BT
1.77Vac on my VC9808+

5Vpp + 2Vdc and 0Vpp+2Vdc
2.15Vmid (scope)
2.14Vdc on my trueRMS BXM9BT
2.13Vdc on my VC9808+

0Vpp + 4Vdc
4.34Vmid (scope)
4.33Vdc on my trueRMS BXM9BT
4.30Vdc on my VC9808+

So, over the board +7% on DC offset, but Vpp was pretty good.
Slightly better I guess, but is it version or calibration? They may have skipped calibration in mass production, and offered you calibration (on top of new flash)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 15, 2017, 08:53:48 am
Not sure if I feel better or not now knowing mine is not the only one out of step with accuracy  :-\

Interesting to see if anyone with 3.9 or more recent firmware gets better or similar. If similar then I guess it's time to go chasing a hardware solution?

As a fallback not that it is ideal there is several regular waveforms needed I planned to program anyway so I could always preset "known" voltages for these against  my Agilent or CRO.

For the sorts of work I am doing which is low voltage and sub 1Mhz DC the timebase issue doesn't concern me at this time but cool creative stuff still :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 16, 2017, 03:54:59 pm
(Note: I edited this post after don.r pointed out I had misread the part number mentioned as a future replacement IC. The rest of what I posted regarding possible noise imposed on the +/- supplies should be correct.)

On replacing the mystery dual op amp with 2 THS3095D single op amps as Vytautas has done, I just ordered 2 from Mouser Electronics. They still aren't real cheap at $10.64 US each but still worth the cost if you want to upgrade the output to get lower distortion at the higher voltage the FY6600 is capable of.

I'm not sure if these faster chips will improve the rise time on square waves or not but they won't hurt. Also I'd assume the THS3095D chips draw a little more supply current and may impose some added load and noise on the +/- supplies feeding them and means you'll want to use a +/-15V supply with higher output current capacity instead of the existing +/-12V supply to get the full benefit of the new chips. I'll check the a.c. voltages on the bypass capacitors next to these chip with the scope once they are installed to see if there is any noise cause by the higher current drain of the THS3095D chips necessitating more capacitance needed across the existing capacitors and report what I find, probably in about 1 week.   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 16, 2017, 04:01:33 pm
The THS3091 is an old chip. The new ones are the THS3491.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 16, 2017, 04:13:51 pm
Oops, I misread. Should pay more attention next time. Thanks for pointing it out.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 17, 2017, 01:28:34 am
Output Voltage Calibration

Seems the output voltages are not in fact firmware set. After taking a careful photo and tracing the board a bit the following pots can be twirled  :scared:

As labeled. They are very twitchy so I might look at hacking some 10 turn pots to replace them.

W5 CH1 DC offset adjustment
W3 CH2 DC offset adjustment

Easiest cal method. Set Frequency to 0 and ampl to 0. Set offset to 10V and tweak. There is still a bit of non linearity so some more looking at resistors or for voltage references is in order.

W26 CH1 AMPL P-P adjustment
W16 CH2 AMPL P-P adjustment

I found setting these to 10V P-P gave me about the best linearity across the range. At 20V P-P low Amplitudes were out. So like the DC a bit more looking required. Tested from 50Hz to 100kHz and no real amplitude change.

This gets it within 1-2% across the range instead of the up to 10% I was reading  :-+

So what does it mean - less than ideal calibration and testing in the factory I suspect?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 17, 2017, 05:04:23 am
W1 changes the CH2 low end DC calibration. Set 100mV and tweak seems to work best

W2 is the same but for CH1.

They do also effect the top end DC calibration by a small margin so a little to and fro with W3 and W5 is needed to get the best result across the range.

I have exhausted what coffee can do for today. Time for a BEER  :popcorn:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 17, 2017, 05:48:16 am
Hello,

I own the FY2300H 14 bit 250 MSa / s and had to open the generator to adjust the output levels when I received it. Under the radiator FY2300H there are IC 30021 and MC45558, and also the free tracks U21 and U22 for soldering of 2 IC TH3091 after remove IC 30021.
The THS3095 IC has a power-down spindle that is not useful since not connected on FY6600 et FY2300H Feeltech.
 
Buy THS3091 low price :
- https://fr.aliexpress.com/item/1pcs-THS3091DR-THS3091-SOP-8/32824185282.html?spm=a2g0s.9042311.0.0.SpCn6H


Regards,
Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 17, 2017, 06:31:19 am
I have exhausted what coffee can do for today. Time for a BEER  :popcorn:
Well earned.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 17, 2017, 07:41:47 am
And to Feeltech, you shouldn't take our criticisms of the current generation of product to heart to much. There is a reason we are working on our units the basic ideas and features we like are worth persisting with and if it helps you to improve future models then great  :-+

So far mine for some time and under $4 of components is a much improved item. Some of the others upgrades would certainly add a bit to your costs but for most users not required I feel.

Jump back in we don't bite to much  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sorin on November 17, 2017, 10:54:05 am
Output Voltage Calibration

Seems the output voltages are not in fact firmware set. After taking a careful photo and tracing the board a bit the following pots can be twirled  :scared:

As labeled. They are very twitchy so I might look at hacking some 10 turn pots to replace them.

W5 CH1 DC offset adjustment
W3 CH2 DC offset adjustment

Easiest cal method. Set Frequency to 0 and ampl to 0. Set offset to 10V and tweak. There is still a bit of non linearity so some more looking at resistors or for voltage references is in order.

W26 CH1 AMPL P-P adjustment
W16 CH2 AMPL P-P adjustment

I found setting these to 10V P-P gave me about the best linearity across the range. At 20V P-P low Amplitudes were out. So like the DC a bit more looking required. Tested from 50Hz to 100kHz and no real amplitude change.

This gets it within 1-2% across the range instead of the up to 10% I was reading  :-+

So what does it mean - less than ideal calibration and testing in the factory I suspect?


I dont think so.
In my opinion W5, W3, W26, W16 are used for Differential OpAmp compensation.
More info here (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1343034/#msg1343034).

The responsible components for the DC offset are IC7 & IC8, 12bit DAC [MCP4822E].

(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=367323;image)
Thanks to Ebel0410 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1351221/#msg1351221) for the image.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 17, 2017, 01:21:09 pm
And if we continue your logic the DAC's are actually controlled by the Cyclone so that is what actually controls the DC offsets not the DAC's.

As we currently have no way into the micro we have no control over the DAC's and their output calibration so the only control over the outputs is by controlling the opamps or additional analog circuitry after the DAC's to my way of thinking.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 17, 2017, 04:36:01 pm
In my opinion W5, W3, W26, W16 are used for Differential OpAmp compensation.
More info here (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1343034/#msg1343034).

The responsible components for the DC offset are IC7 & IC8, 12bit DAC [MCP4822E]

My original thinking was also that those low-speed DAC's do slow amplification and offset levels. However, one cannot argue with results, and beanflying seemed to got that.
It may have been a side-effect of something else, but can you explain what in your view the differential opamp actually does, and what would have been de-tuned when beanflying changed those pots?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 17, 2017, 04:49:48 pm
Hello,
W1 and W2 are the settings that I had to adjust equalize the amplitudes when receiving my FY2300H
I ordered 2 IC THS3091 to improve (?) the signals and also to spread the heat dissipation on 2 IC and not on 1 IC alone.

Regards,
Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 17, 2017, 10:53:31 pm
Coffee Morning Sunshine and a pleasant 22 degrees in the shack  :-+

Just ran a series of tests on Ch1 and 2 after yesterdays tweaking. A few of the 1Mhz voltages must be pushing either the Feeltech or the Agilent a bit so they are out. Will boot up the scope later and have a look.

Just checked the Agilent is rated +-4% from 100-300KHz and Typical error at 1MHz of 30%  8)



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 18, 2017, 02:41:03 am
Coffee Morning Sunshine and a pleasant 22 degrees in the shack  :-+

My lab in the garage is 2 degrees this evening.  :--
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on November 18, 2017, 03:00:49 am
My lab in the garage is 2 degrees this evening.  :--
Just give your office chair a push and you'll see the other 358 degrees swirls by in no time.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 18, 2017, 03:07:34 am
Coffee Morning Sunshine and a pleasant 22 degrees in the shack  :-+

My lab in the garage is 2 degrees this evening.  :--

I remember being in Chicago in early November once when the NW wind came in out of Canada wasn't pleasant at all.

Building Voltage references in shorts and a Tshirt at present :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 18, 2017, 03:19:30 am
Coffee Morning Sunshine and a pleasant 22 degrees in the shack  :-+

My lab in the garage is 2 degrees this evening.  :--

I remember being in Chicago in early November once when the NW wind came in out of Canada wasn't pleasant at all.

Building Voltage references in shorts and a Tshirt at present :-DD

I shouldn't complain really. I just spent two weeks in Hawaii. Maybe that's why 2 degrees feels like -20 right now.  ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 18, 2017, 02:41:41 pm
So, I read out the 25 spi flash Winbond 25Q16BVSIG flash chip.
Content attached. Did cursory review, some patterns, some empty space, some high density data.

What I would like is if someone with a 2.9 or 3.2 or even also 3.2.1 model to also do this, so we can check if indeed there are only settings in the FLASH.
Presumably waveforms are all the same between 2.9 and 3.1, so if there are only very little changes, it would point to calibration.
Similar for 30MHz models.

However, (should not need to mention it on this forum, but do so anyway) this is at your own risk. I am not responsible for you messing up your device.




Please note that I think the flash is not all the firmware. The display board ARM SoC also has internal flash. It is quite possible these 2 are not always compatible when different versions.
But waveforms is definitely be in the flash, likely also the Cyclone, but probably not the UI programming or the user settings.
Posted some more on Winbond flash memory map here (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1353950/#msg1353950).

Used a cheap CH341A clone SPI programmer (https://www.ebay.com/itm/172265718620) . See this video (not mine)
tool download link in video (https://drive.google.com/file/d/0ByEQKtsOckWBUVBqajZOUGtLcnM/view)

Warning: not all CH341A clones are 3.3V (https://www.eevblog.com/forum/repair/ch341a-serial-memory-programmer-power-supply-fix/). Ensure you have one that can be properly set to 3.3V.
Note that depending on the clone, you need to pay attention to chip orientation. Both the program icon and the video instruction did not match correct orientation for my programmer clone (I have the exact one of the link above, but there seem to be 2 or 3 more variants.
So look at the silkscreen, use the 25x position for this Winbond chip.

this video (https://www.youtube.com/watch?v=L0ChYNwunUE)

FY6600 Programming header (Cyclone header):
1CLKGND2
3DONEVcc4
5/CFG/CE6
7DO/CS8
9DIGND10

Pinout mapping:
JTAGFPGA (https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/dp/cyclone-iv/ep4ce6.pdf)FLASH (https://media.digikey.com/pdf/Data%20Sheets/Winbond%20PDFs/W25Q16BV.pdf)
1126CLK
2 4GND
392 Conf_DonePulled up with 10K
4 8Vcc
514 nConfigWarning, low can clear the FPGA? Is pulled high by 10K
621 nCEWhen high FPGA disable in tri-state
7132DO / Data0
8 1/CSWhen high FLASH disable in tri-state
965DI / ASDO
10 4GND

To program Cyclone IV:
- Instructions to be interpreted by a Cyclone expert, being someone else then me
- Keep /CS from Winbond HIGH to disable Winbond Flash
- Pins CLK, /CFG,/CE, DO, DI, DONE have Cyclone functions DCLK, nConfig, nCE, Data0, ASDO, Conf_Done
- Use ByteBlaster II or USB Blaster 10-pin header

To program Winbond:
- Ensure 3.3V or lower programming level
- Connect GND, but Vcc is probably not needed (already fed from FY6600)
- Warning, never make /CFG or nConfig from Cyclone low, as this may clear the Cyclone (https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/dp/cyclone-iv/pcg-01008.pdf)
   maybe best not to even wire the /CFG pin.
- Keep /CE from Cyclone HIGH to disable the Cyclone
- Connect CLK, DO, DI, /CS to SPI programmer (or keep CS low)
- WP and HOLD are already connected high on the FY6600 board

Winbond Cable FY6600-JTAG to DIL-8 emulated chip footprint:
- Loop /CE to Vcc. /CE is normally 10K to ground, so must be lower impedance to Vcc
- Connect GND, CLK, DO, DI, /CS to SPI programmer
 
When you connect the cable the Cyclone IV FPGA will not start up because nCE is looped high to Vcc. Not even if the other end of the cable is not connected. But the FY6600 does does show its logo. I guess the logo is burned into the screen driver rather then driven by the FPGA

Cable for Flash read/write
WARNING: I wrote this down incorrectly and swapped in 4 and 6. Sorry. Correct now.
JTAGDIL-8
16
24
3
4 loop to 6
5
6 loop to 4
72
81
95
10





Edit: While analyzing the firmware, I made some interesting new finds:
More detailed info here (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1353950/#msg1353950), but a summery:

The programming header is a standard Cyclone USB Blaster II header, see newly attached image.
Also, I now believe the first x05ffff bytes of the flash are the Cyclone configuration bitstream. The cyclone itself reads this without the intervention of a CPU, as shown in this document. (https://www.altera.com/en_US/pdfs/literature/hb/cyclone-iv/cyiv-51008.pdf)

Flash structure:
0x000000 Cyclone bitstream
0x060000 Most build in waveforms (not in 1:1 mapping) (the ones repeating in Arb).
0x100000 Arb1~64 in blocks of x4000 bytes (first 32 a repeat of 0x060000)

There is likely no user settings or calibration in the flash. I changed settings, and reread, and nothing was changed.
So user settings are likely stored in SoC on the display board, which controls the Cyclone by simply serial commands.

In other words, the SoC has the User UI firmware, that is not stored in the Winbond flash, and we need to retrieve that too.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 18, 2017, 05:08:38 pm
Hey Cybermaus, you did a great job !
Day after day we're moving forward to the Graal...

Now we need the help of someone who's is talking FGPA and hacking fluently.
I read that for example and it was really awesome (http://blog.weinigel.se/2016/05/01/sds7102-hacking.html (http://blog.weinigel.se/2016/05/01/sds7102-hacking.html))
, that man would be very helpful to move one step higher.
Christer christer@weinigel.se , if you feel inspired, don't hesitate  :P
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 18, 2017, 06:33:59 pm
Well, if you want that kind of help from someone not already part of the FY6600 community, you may need to gift them a device (in the form of a dropship) with no expectations attached.

But more to the point: his Owon has a SoC CPU controlling the FPGA. A CPU typically works from a file system, with a bootloader and mountable partitions.
And in fact the CPU feeds the FPGA the configuration bitstream, so that FPGA config is a readable file in said filesystem. Its what your android does when it upgrades its radio/modem sub-firmware.


In our case, there is no SoC, its only the FPGA. And thus it is not programmed through the CPU, but directly from the header, as evident by the pins on the header.
This is why we cannot upgrade via USB. While you can configure a simple virtual CPU core on an FPGA, you cannot use programming on that core itself to reconfigure itself.
Also as far as I understand them a typical FPGA configuration cannot be read, only written.

So, sorry I do not think there will be hacking of the FPGA, not even by an expert like your Christer
(unless if I completely misunderstands FPGA's, not entirely impossible)


Also, it is unlikely the actual programming for any virtual CPU is in the flash. It is probably also in the FPGA.
Maybe a very small UI program (though I did not even see any strings, there was a high density section in the memory).

The reason I think so are these:
- The system starts up way too fast to download much software out of flash first
- The waveforms themselves (36+64@8192words) take up 1.6MB out of the 2MB. So not much left
- The actual signal processing at 2x250MSa/s does not allow for CPU based logic. Its all configured transistors.


BUT (http://www.st.com/content/ccc/resource/technical/document/application_note/b9/9b/16/3a/12/1e/40/0c/CD00167594.pdf/files/CD00167594.pdf/jcr:content/translations/en.CD00167594.pdf): At least we will be able to repair the broken waveform for that guy who lost his SINE. What that you or someone else?



EDIT: new info found (see other post for more info):

- Cyclone can self-read config, and its bitstream likely is in start of the windbond flash. So can be upgraded by us
- UI is in display SoC, still need to figure out how to read/write that.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 18, 2017, 10:22:59 pm
Hello,

On the front panel there is, unless I am mistaken, 1 STM32F103C8.
What do you think ?

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 18, 2017, 10:25:03 pm
Hello,

On the front panel there is, unless I am mistaken, 1 STM32F103C8.
What do you think ?

Diabolo

... and its jtag is just under the connector to the main board. Should be capable of a dump.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 19, 2017, 01:56:14 am
Hmm, I did not even look at the display board. A bit short sighted of me.

I will look at that, out of interest, but I suspect the situation remains the same, its just a display driver.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 19, 2017, 02:09:51 am
Hmm, I did not even look at the display board. A bit short sighted of me.

I will look at that, out of interest, but I suspect the situation remains the same, its just a display driver.

There are a couple of issues with the display that could be fixed. For one thing, the font. Its gross and not the most legible. Another thing is the frequency display. Strip leading zeros, standardize units, more legible colours, etc. I'm sure there are other changes that people would want. If its only the display driver, maybe FeelTech could see their way to making it Open Source.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on November 19, 2017, 02:28:11 am
There are a couple of issues with the display that could be fixed. For one thing, the font. Its gross and not the most legible. Another thing is the frequency display. Strip leading zeros, standardize units, more legible colours, etc. I'm sure there are other changes that people would want. If its only the display driver, maybe FeelTech could see their way to making it Open Source.
Yeah, that very typical font has to go. A lot of the cheap Chinese stuff comes with it and it's a shame to have it detract from the device. Mind you, I can imagine it's all the same to someone whose native alphabet is different.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 19, 2017, 08:54:04 am
BUT: At least we will be able to repair the broken waveform for that guy who lost his SINE. What that you or someone else?
In reply to Cybermaus : Yes, it's me ! The Sine memory waveform is a flat line on both channels.
And I guess that could help that guy too : https://www.eevblog.com/forum/repair/reflashing-or-resetting-a-feeltech-fy6600-signal-generator/ (https://www.eevblog.com/forum/repair/reflashing-or-resetting-a-feeltech-fy6600-signal-generator/)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 19, 2017, 09:52:00 am
well, get your own CH341A and read the flash, so we can compare and then repair.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 19, 2017, 09:54:14 am
Not sure if I can get as motivated about fonts as for the other stuff that was already done.

For new buyers and users, a summery of what can be done, with links.
(so no desires and rants but achieved items)

1: The power supply can be made less leaky
Simple solution is to add a grounded socket  (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1343235/#msg1343235)and either fully ground the device, or add some Y-caps (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1344167/#msg1344167) or reconnect the one already there (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1347131/#msg1347131)
Deep solution is to fully replace the supply (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1348087/#msg1348087)

2: The time base can be made more precise
Simple solution is to replace CXO with a 0.1ppm TCXO, (https://www.ebay.com/itm/263019239549) either directly 50Mhz or a a 10MHz one with a PLL multiplier (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1346454/#msg1346454)
Deep solution is to add a external GPSDO or OCXO or external 10MHz reference source (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1347624/#msg1347624)

3: Good waveform at lower Vpp, but at full 20Vpp and above 5MHz, it can be improved
Replace the end opamp with two separate better ones (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1348087/#msg1348087)
May also need a new power supply, with a little more oomph to keep the +-15V up, see 1: above

4: DC Offset and Vpp calibrations can be tuned.
Unfortunately not (yet) by firmware, but simply tweak the pots on the board. (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1351221/#msg1351221)


Did I miss anything? (something people can do, not things we would like to do)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 19, 2017, 04:41:12 pm
Hello,

For the power supply with 15V, be careful the internal capacitors are maximum 16V !!

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 19, 2017, 06:25:32 pm
Cybermaus has listed the modifications that have been tried and seem to work so you can pick and choose what ‘options’ you want to add to your FY6600 from the list.

I have chosen to carry the ground (earth) from the 3-wire cord I added through to the power supply output ground and to replace the wimpy original supply with a heftier one. I’m not convinced that anyone can guarantee that all the parts will continue working at +/-15V instead of the +/-12V the board calls for. The board appears to work just fine with the +/-15V but with the part numbers ground off some ICs I don’t think there is any guarantee that some of the mystery parts aren’t seeing a higher voltage than they are designed for so I’m going to stick with a replacement +/-12V supply. The one I had used originally was a 40W supply that was much larger than needed but I had it on hand. I found a good quality 25W +/-12V supply for $13 plus shipping that doesn’t waste as much power (2W less than the 40W supply) so I’m using that supply as shown in the photos. I did find an excellent +/-15V supply that will just physically fit if I decide later to go with the higher voltage and that supply cost me about $13 with shipping and I have a photo showing how that would fit in the FY6600.

The OCXO I added is working great and if I leave the rear switch on so the OCXO is always warmed up the 10Mhz seems to generally stay within +/-.005Hz (9,999,999.995Mhz to 10,000,000.005Mhz) and I have the switch and BNC I added to the back to connect an external 10Mhz standard if I want.

I should get the THS3095D chips to replace the output amplifier chips and I think that is the last (really!) modification I’ll make unless I go with the +/-15V supply at a later date.

+/-12V supply  http://www.mpja.com/ (http://www.mpja.com/) Stock No: 34322 PS
+/-15V supply Ebay # 263326410466
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 19, 2017, 06:56:11 pm
I'll definitely do the time base next as the TCXO and PLL only consume a few more mA than the current 50Mhz crystal so the original PSU is still OK. It would also be an opportunity to add an external port for the 10Mhz like you did. This should be standard on even low end wavegens. I'm going to wait for the 3491's to be released and examined before I go further as I'm not sure about running the rest of the board at 15V. I don't have much of a need for more than a few V's of output anyhow.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 19, 2017, 07:30:24 pm
I’m not convinced that anyone can guarantee that all the parts will continue working at +/-15V instead of the +/-12V the board calls for.

Remind me, why do we believe the board calls for +/-12V?

At first I also I also thought it was a common +5V +12V board because not only is that common, but also someone reported that. But that very same person also mentioned his 12V supply was not very good because it was almost 15V. And mine is also hovering between 14.5V and 15.2V.

So I am wondering, maybe it simply is supposed to be a 15V supply? After all, +-15V is not an uncommon rail for OpAmps. So indeed, remind me, why do we think it is a +/-12V board?

I do agree though, if 15V, make sure you do not creep toward 16V.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 19, 2017, 07:42:23 pm
I’m not convinced that anyone can guarantee that all the parts will continue working at +/-15V instead of the +/-12V the board calls for.

Remind me, why do we believe the board calls for +/-12V?

At first I also I also thought it was a common +5V +12V board because not only is that common, but also someone reported that. But that very same person also mentioned his 12V supply was not very good because it was almost 15V. And mine is also hovering between 14.5V and 15.2V.

So I am wondering, maybe it simply is supposed to be a 15V supply? After all, +-15V is not an uncommon rail for OpAmps. So indeed, remind me, why do we think it is a +/-12V board?

I do agree though, if 15V, make sure you do not creep toward 16V.

Its stamped +-12V on the board. Mine measures +15.8V and -15.2V unloaded.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 19, 2017, 07:48:20 pm
Here's a photo of the voltages on the power supply board. The numbers are almost hidden by the connector.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 19, 2017, 07:49:55 pm
Somewhat unnerving that its labelled as 12v but measuring 15.8V and has 16V rated output caps. They should be 25V rated.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 19, 2017, 07:54:18 pm
Hello,

Nobody tried the THS3092 which contains 2 AOP +/- of THS3091 in the same S0P8 case, or almost "equivalent" to 30021 of origin FY6600 ?
Datasheet THS3092 :
http://www.ti.com/lit/ds/symlink/ths3092.pdf (http://www.ti.com/lit/ds/symlink/ths3092.pdf)
----
Buy THS3092 :
https://fr.aliexpress.com/item/THS3092-THS3092D-THS3092DDA-THS3092DDAR-3092-SOP/32827398519.html?ws_ab_test=searchweb0_0,searchweb201602_3_10152_10065_10151_10344_10068_10345_10342_10343_10340_10341_10541_10562_10084_10083_10305_10304_10307_10306_10177_10302_10060_10155_10154_10539_10312_10059_10313_10314_10184_10534_10533_100031_10103_10073_10594_10557_10596_10595_10142_10107-10177,searchweb201603_14,ppcSwitch_4&btsid=fa0c137f-85cc-4348-92e5-524764005c20&algo_expid=d4b84c0c-c840-4c1c-99cd-e0f428d02b99-7&algo_pvid=d4b84c0c-c840-4c1c-99cd-e0f428d02b99&rmStoreLevelAB=0 (https://fr.aliexpress.com/item/THS3092-THS3092D-THS3092DDA-THS3092DDAR-3092-SOP/32827398519.html?ws_ab_test=searchweb0_0,searchweb201602_3_10152_10065_10151_10344_10068_10345_10342_10343_10340_10341_10541_10562_10084_10083_10305_10304_10307_10306_10177_10302_10060_10155_10154_10539_10312_10059_10313_10314_10184_10534_10533_100031_10103_10073_10594_10557_10596_10595_10142_10107-10177,searchweb201603_14,ppcSwitch_4&btsid=fa0c137f-85cc-4348-92e5-524764005c20&algo_expid=d4b84c0c-c840-4c1c-99cd-e0f428d02b99-7&algo_pvid=d4b84c0c-c840-4c1c-99cd-e0f428d02b99&rmStoreLevelAB=0)


Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 19, 2017, 08:00:20 pm
+/-12V supply  http://www.mpja.com/ (http://www.mpja.com/) Stock No: 34322 PS
+/-15V supply Ebay # 263326410466

Ebay # 263326410466 : Does not ship to the NL
HUGE pity, because $6 seems a steal, even pre-owned.

Same on Mouser: End of Life: Scheduled for obsolescence. And a €93 price (on top of nl.mousers standard of € 20 shipping)
Makes the $6 seem like even more of a steal. Even when adding $8 shipping to US.

I am tempted to ask you to get me two of those boards, but I will not be in US till May, and not sure what privately international shipping would add to the cost. Why do so many US eBayers not ship international! (I did send him a message, but usually they answer they simply do not want the hassle)

Actually, this Meanwell is local and not a bad price:
http://www.meanwell.nl/products/Meanwell-PT-45C---PSU-pcb--plus-5V-5A---plus-15V-23A---15V-05A__PT-45C.aspx (http://www.meanwell.nl/products/Meanwell-PT-45C---PSU-pcb--plus-5V-5A---plus-15V-23A---15V-05A__PT-45C.aspx)
A bit oversized though, but it seems to be there smallest tripple output

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on November 20, 2017, 01:37:28 pm
As a reply concerning the 3092. It could be a better option than the original "30021" also, though sharing the load between two chips instead of one is better, IMHO.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 20, 2017, 02:36:51 pm
Some more info on the firmware from the flashchip:

Waveforms:

By creating square waveform, uploading, and then rereading the flash, I found the following:

A waveform is 16K in size. Arb1 starts at 0x0100000 with 64 waves that means precisely the last 1M (iow, second half of the full 2MB chip) is filled with the 64 ARB waves of which the first 32 is a repeat of build in, and the last 32 are all xFFFF values. There is no meta-data at all. The little graph on the screen is calculated on the fly, and there is no descriptive string,.

Looking at the data, it is all xFF3F for +1 and x0000 for -1 of the defined square wave as defined in the tool.
So the data is in LSB, and should read x3FFF instead, which is exactly 14 bits.
x0000 is -1, what we consider 0Vdc is x2000 and +1 is x3FFF

I also possibly spotted an a few wave definition errors:

The wave generated and uploaded by the tool is 8191 words long, the space in the flash 8192 words long, and indeed there seems to be one leftover word with a odd value in the flash. This could give spikes on the waveform? Need to check.

The square wave generated by the tool starts with a single +0.5 value before staying on +1 half the way. I suspect it is because the tool average values and start with 0. In any case, this could explain the 7.4ns risetime I noticed on the official square wave, vs 4.8ns on all other vertical edges. It may be they generated the official one also with the tool.
Indeed, when I made my own square wave, it gave me a 4.8ns risetime. Pretty nice 31.250 MHz square (no jitter on 250MSa/31.250MHz)

Position 0x060000 to 0x0DFFFF are the build in waveforms, an exact copy of 0x100000 to 0x17FFFF, but not an exact match for the build in waves of the UI
I suspect that some of them, like Sine, Square, CMOS, DC are hardcoded FPGE procedural instead of numerical. Sine so it can go up higher, and Square and CMOS so you can control the duty cycle. And DC because I found no block of x2000 values.

Settings and Calibration:

By changing settings and then rereading the flash, I found the following:
Nothing changed in the Winbond flash. So there are no settings in the flash. None.
And I now believe also no calibration. Instead those are thus stored in the as yet unreadble STM32 chip on the UI board.

Cyclone Config:

I read some info on the Cyclone, and I now believe the first 0x05FFFF bytes are the Cyclone IV bitstream, which are read at startup. I added some references to the other post about flashing, including the official header description. So the flash is most of the firmware, it also has the FPGA stuff. But the display board SoC actually has the UI programming as well as all settings.

Memory map:

Unknown
0x000000 to 0x0000ff Mostly ff, some other values
0x000100 to 0x001341 Patterns many in dual byte pairs
0x001342 to 0x059d4f very low density data, mostly 0 bits
                     Maybe FPGA matrix pin connections?
                     Can FPGA self-program from flash? (answer: yes it can (https://www.altera.com/en_US/pdfs/literature/hb/cyclone-iv/cyiv-51008.pdf))
                     I am guessing. Not program or waveform data though
0x059d50 to 0x05ffff all ff. Filler to boundery


Build in waveforms in blocks of x4000
0x060000 to 0x0dffff (32 waveforms)

0x0e0000 to 0x0effff all ff
0x0f0000 to 0x0f0fff 16x a count from 00~ff (user or leftover development junk?)
0x0f1000 to 0x0fffff all ff

Waveform Arb1~64 in blocks of x4000
0x100000 to 0x17ffff repeat of x060000 to x0dffff
0x180000 to 0x1fffff all ff
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on November 20, 2017, 04:28:24 pm
Cybermaus, check these Ebay listings for +/-15V power supplies as possible replacements for the +/-12V one in the FY6600. Both are small and should fit. I don’t know anything about the seller but their feedback is 100% and these supplies have worldwide shipping (~$20 to NL) so they might be worth checking. You first might want to measure what the minimum current drawn from each voltage rail is in your FY6600 is and check the specs on the power supply datasheet for each supply. I didn’t check the specs carefully so I may have missed something you’d find important. If both meets your needs I’d lean toward the RPT-60C model. Here are the Ebay listing numbers   252596788777  252511042883
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: chtech0710 on November 21, 2017, 05:05:43 pm
Hi,

i've got my FY6600 recently and now it has stopped working  :(

Because i've replaced the power supply, modified the housing and added some shielding, i can't send it back to the seller (or Feeltech anyways).
I don't think the new power supply has caused the problem, it's a really good one (actually the same that ArthurDent uses in one of his.)

I've measured all suppy rails (also on the voltage regulators), which seems fine.
I also read the Flash content and compared with the uploaded content from cybermaus (btw. THX for uploading  ;) ) and it's identically.
The next thing i've checked was the nStatus pin (pin 92, also available at R2) and the Conf-Done pin (pin 9, also available at R3) from the cyclone after power-on - if there is any error. Even all clocks are present and fine so the Cyclone seems to be okay.

But nothing happens on the front panel. Just 2 relay clicks after power-on. No display, no LEDs light up, no beep.

My guess is, the little STM32 is gone bad or it's memory became corrupted.
That would be most likely the case, because the FY6600 stopped working after a factory reset and power-off.

My question: is it possible to get the flash content from the STM32?
I would try to reflash it or replace the whole IC if i got the firmware.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 21, 2017, 06:25:57 pm
Sorry to hear that. Unfortunately you seem to be the 5th one where the device went bad.

It may be better to move your question to the other thread (https://www.eevblog.com/forum/repair/reflashing-or-resetting-a-feeltech-fy6600-signal-generator/) though, so we keep the flash corruption & problem emails in one place.

At the very least, read that thread, because it seems your failure mode is completely different then the other 4, who had all 4 had identical progressive problems, and yours is a sudden dead. So it may simply be a power problem on the display board.
Hopefully so, because I have a STLink2 flash/read tool underway, but it seems often these STM32 chips are read-protected in commercial products.

Also: So flashchip is completely identical. Ok. What version and frequency model?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: chtech0710 on November 21, 2017, 07:03:01 pm
Sorry, my fault. I just googled "FY6600 firmware" and as a result found this post.
Now i've read the other thread, but it doesn't help very much.

I don't think it's a power problem, because the 3.3V on the vreg for the STM are present and stable. (Perhaps, a transient killed the STM32? Mhmmm...)
I've tried to measure if the crystal (next to the STM32) is working, but nothing. I replaced it, nothing changed.

I've got the 30 MHz model. I think the version was the latest, i can't tell you exactly, cause i'm at home now and not at my workshop.

The content of the flash chip ist almost identically (havent checked every single bit  ::) )
I've read out the old firmware from the flash chip (and saved it). Have tried your uploaded one. Makes no difference if I try your firmware or the original one.
I do not think the Cyclone is broken. By capturing some data between the flash chip and the Cyclone, everything seems normal.

BTW, could a friendly moderator move my (and your last) post into the appropriate thread? THX  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 21, 2017, 07:05:36 pm
Hello,

To read, write, remove read / write protection on STM32:
- http://www.jyetech.com/Support/STM32_FlashLoaderDemonstrator_v2.7.zip (http://www.jyetech.com/Support/STM32_FlashLoaderDemonstrator_v2.7.zip)

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: chtech0710 on November 21, 2017, 07:17:45 pm
Just recently used this tool to upgrade the firmware from my DSOShell, but I wouldn't have come up with the idea to use it for this problem.  ;D
But, this tool needs a bootloader to work? i dunno.

Anyhow, i will try it tomorrow. THX  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 21, 2017, 07:51:06 pm
From what I read in this STM32 doc (http://www.st.com/content/ccc/resource/technical/document/application_note/b9/9b/16/3a/12/1e/40/0c/CD00167594.pdf/files/CD00167594.pdf/jcr:content/translations/en.CD00167594.pdf) (yes, I have been reading a lot about the STM32 lately. Demo board and STLink2 tool should be here tomorrow), the bootloader is always present on this chips, in masked ROM even. Hence it can update using this serial tool.

But remember, you want to read, not write, the firmware.

But good to check the tool anyway, at least it will tell you if the chip is still alive.

Can you send me your WInbond flash file, so I can binary compare them?
ALso, I would really like to know what version your device was. Did you never look before it crashed?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: chtech0710 on November 21, 2017, 08:30:05 pm
Unfortunately, I do not have much experience with STM32 µCs. At work we use mostly ATmega, PIC, some lower-end FPGA or "fancy" embedded computers with linux. (it's a small company)

Good to know that the bootloader is always present. I will definitely try to unlock and/or read the content from the STM32 tomorrow (but only if the chip is alive  :-\)
And i will also upload the flash content from the Winbond flash ic.

Apart from that, by comparing available pictures of the hardware it almost looks like the hardware is pretty identical to most models (15/30/50/60?MHz). A comparison of the different firmwares should give us information about possibilities for hacks.  ;)

I was recently looking for an update of the firmware, but it was (and is) not possible yet, and unfortunately i didn't take much care about my fw version. I#m pretty sure it was the latest version 3.1(?)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 21, 2017, 08:55:44 pm
Careful with the "unlock". Not sure if you can do that from serial, but:

According to these people (https://www.usenix.org/system/files/conference/woot17/woot17-paper-obermaier.pdf), unlock from security level RDP1 to RDP0 is possible, but will auto-erase the flash, making the chip back ready for a new program, but not helpful for us.

They did find a way to read the flash while in RDP1, by means of a custom reader that resets the debug tool, it seems that each well timed reset leaks one byte of flash. But that will not work for normal available tools, and they did not release the software.

From what I understand, our only realistic hope is that the manufacturer did not secure the chip. Or makes the firmware available in order to stop negative posts.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: chtech0710 on November 22, 2017, 10:03:18 am
After many cups of coffee, and playing around i've managed to get access to the bootloader with the ST Flash Loader Demonstrator.

First of all, the memory is protected...  :'(
and by trying to unlock, it was auto-erased... damn!

In case someone else will try it:
USART1 isn't easy availlable, so you have to solder some small wires to the STM. The RX/TX from J1 are wired to USART2 and useless in our case.
First, we need to set the BOOT0 pin to high (3.3V) to enable the bootloader. BOOT0 is at pin 44.
USART1-TX is on pin 30 and USART-RX is on pin 31, which also goes to C1 and the encoder.
You have to remove C1, cause C1 acts like a filter. I've used the pad from C1 to attach the RX-wire.
We need the RESET-pin, which is availlable at pin 7 and R1.
GND and 3.3V are availlabe from JK1.

Finally, the baudrate is 115200,8N1 with even parity.
By using the Flash Loader Demonstrator, you shoud disable ECHO and set the timeout to 5.

And here are some pics showing my attempts to get access to the bootloader.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 22, 2017, 12:47:33 pm
Big bummer. No need for me to check anymore if the STM32 is locked

So there are already 5 people with broken STM32 flash. And we know how to write the flash.
We need some way to make the vendor relinquish the firmware?

Easy for me to say, mine is still working, but keep asking for service requests? Not buy anymore of their stuff until this is fixed / fixable.
That latter one is pretty understandable, as much as I am happy with mine, knowing it can corrupt its own flash at any moment means I would not recommend to others.


Sidenote, I checked your firmware file. While it appears the same on a quick glance, it is quite different.
Not only did you already upload the first and last few arbitrary waveforms, 2 of the build in ones are also slightly different.
And though not easy to spot due to the low bit density, the Cyclone part is also different all over.
So it seems they are making changes to the Cyclone between versions as well as the UI



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 22, 2017, 10:19:07 pm
Disappointing about the firmware failures. Time for Feeltech to release a method and the firmware to fix this issue and enable user upgrading or repair.  :-+

This thread until it happens will continue to turn up very high in the search rankings and random failures that require unit returns to mainland China are not going to reflect well on sales.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scratch.HTF on November 23, 2017, 02:42:49 am
Since I intend to sync this unit to an external frequency reference, is the frequency at the Sync OUT port 10 MHz?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on November 23, 2017, 02:48:43 am
Hello,

Aie, it's a shame for the erased STM32 memory.
But we will find a solution to restore everything in condition. ;)
----
How does a power supply / charger for laptops, LCD TVs, GSM, etc ... (Sony, Asus, Samsung, etc ...) that have a 110V-220V with 2 pins compared to the ground?
They must also have 32V of differential with the ground under power supply AC 220V and the general mass ?
----
Datasheet on various TCXO, stability seems good for general purpose :
- http://www.metatech.com.hk/product/fordahl/pdf/2002%20TCXO%20Page%2043-58.pdf (http://www.metatech.com.hk/product/fordahl/pdf/2002%20TCXO%20Page%2043-58.pdf)
- http://docs-europe.electrocomponents.com/webdocs/0d5a/0900766b80d5a4cf.pdf (http://docs-europe.electrocomponents.com/webdocs/0d5a/0900766b80d5a4cf.pdf)


Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 23, 2017, 05:39:23 am
Since I intend to sync this unit to an external frequency reference, is the frequency at the Sync OUT port 10 MHz?
No, but its fairly easily and effectively added. (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1346454/#msg1346454)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 23, 2017, 07:01:28 am
Hello,

How does a power supply / charger for laptops, LCD TVs, GSM, etc ... (Sony, Asus, Samsung, etc ...) that have a 110V-220V with 2 pins compared to the ground?
They must also have 32V of differential with the ground under power supply AC 220V and the general mass ?

Diabolo

Some are good some are junk  :--

Quick test on what I have on hand  on the bench at present 2-40V above ground. Includes built in USB mains adapters. 17V dc LED drivers. The one that is the best is also the cheapest  |O

I have a bunch of these all are in the 2V ac range  :-// https://www.ebay.com.au/itm/AC-DC-220-to-5V-12V-5V-600mA-Isolated-Switching-Power-Supply-Module-Power-Supply/400914188250?hash=item5d585907da:g:AYkAAOSwv0tVRd-R (https://www.ebay.com.au/itm/AC-DC-220-to-5V-12V-5V-600mA-Isolated-Switching-Power-Supply-Module-Power-Supply/400914188250?hash=item5d585907da:g:AYkAAOSwv0tVRd-R)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 23, 2017, 08:07:04 am
Test the illogically good cheap ones again while reversing their AC polarity.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 23, 2017, 08:49:38 am
Fairly humid and hot here tonight. To earth in bare feet on concrete I am generating about 200mVac  :o Also drinking my 3rd Beer and hot swapping 240AC what could go wrong  :palm:

column 1 is one way, 2 is reversed ac. First 4 including the 12V are the same manufacturer. Last 3 are just a few unearthed randoms LED drivers in the box, didn't bother reversing inputs need more :popcorn:

5Vdc 1 - 1.5Vac, 1.47Vac  5.0980Vdc
5Vdc 2 - 1.3Vac, 1.32Vac, 5.0860Vdc
5Vdc 3 - 1.46Vac, 1.45Vac, 5.084Vdc
12Vdc  - 1.14Vac, 1.13Vac, 11.992Vdc

3.16V ac 23.1Vdc
2.89V ac 20.9Vdc
75.1 Vac 12.1dc largest at 10Wand the most EXPENSIVE of the bunch  |O

So the conclusion from this is  :scared:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aylesj on November 23, 2017, 03:54:26 pm
If anyone was thinking of buying one, fasttech are offering 15% off everything at the moment (valid 23rd - 27th Nov), so the 60 MHz version can be had for $86.66 including delivery (Normally $101.95). Use the coupon code THANKS15 after you have added it to the basket.

Unfortunately I ordered one from them a week ago, so missed this discount. It took 8 days from ordering to receive an 'item shipped' email. I'm guessing it will take another 10-14 days to ship to the UK.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on November 24, 2017, 12:07:24 am
Just received my FY6600. Free post, one week Shenzen to Sydney. Impressive.
This is my first post on this thread. I won't be hacking the instrument (much), but follow the thread with interest.

Not sure how to post a quote, but this from Cybermaus 3 weeks ago got my attention.
"So I took CH2, looped it into the VCO and that works but it is a bit unclean. In fact, I found it better to simply put a sawtooth on CH2 and do FM modulation, that also causes a frequency sweep. AM for amplitude sweep. For PWM, still have to use the CH2-VCO"
I find the Ch2 - VCO loop works well, but it is necessary to offset the Ch2 output otherwise you only get half a sweep. Ch2 swings around 0V, but VCO in expects 0-5V. Using CH2 with ramp in this way gives a trigger that is ideal for syncing the scope trace to the Feeltech.

Also I'm a bit intrigued by the power supply issue. As soon as I connect the Feeltech to a scope or other grounded instrument, its internal common is solidly grounded. Nevertheless I will be looking at a grounded IEC connector, as I do appreciate the risk of connecting the signal to a device under test before connecting the ground.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 24, 2017, 01:57:09 am
Welcome  :)

My main concern was frying a low voltage micro in some way with the high floating ground. My bench has a dedicated earth point if needed regardless but I really wanted it to remain floating depending on the application but with lower risk to any DUT.

More risk now of me frying the DUT than the Feeltech  |O
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 24, 2017, 07:10:29 am
Just received my FY6600. Free post, one week Shenzen to Sydney. Impressive.
I find the Ch2 - VCO loop works well, but it is necessary to offset the Ch2 output otherwise you only get half a sweep. Ch2 swings around 0V, but VCO in expects 0-5V. Using CH2 with ramp in this way gives a trigger that is ideal for syncing the scope trace to the Feeltech.

I have since created an dedicated ARB with a sawtooth from 0 to 1 rather then -1 to 1, but starting with a tiny -1 pulse to easily have the scope trigger.


Another usage tip I have since found (maybe common knowledge already)
People (including myself) complained both channels automatically start when you turn on the device. That is actually a setting in the system menu. (ChX boot Yes/No)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 24, 2017, 11:08:24 pm
I folks !

Finally I've decided not buying a new power supply, but making some modifications to the stock PS Feeltech.
I've focused my work on the caps and I would say that it's worth it.

The output filtering capacitors were swapped with low ESR and higher voltage ones.
Main front end circuit, a new high voltage cap 68µ/400v now takes place instead of the old crappy one (10µ/450v)
And last but not least, I've added a second HV cap between 0V and the unconnected mains.
It didn't cost me anything as I used parts from my old stock of electronic devices.


 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 25, 2017, 06:14:18 am
I think your Power Supply board is now at 'capacity'  ;D

Did you run an earth wire or just the extra Caps to try and soak up a bit of the voltage?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 25, 2017, 10:11:39 pm
I think your Power Supply board is now at 'capacity'  ;D
Almost, but you know this PS is really a piece of sh..
I had to remove all the output diodes and replace them with more efficient ones. The gain is roughly +0,5V on each output.
Not so bad !

Quote
Did you run an earth wire or just the extra Caps to try and soak up a bit of the voltage?
Only an extra Cap so the leaked voltage is now half the value of the mains voltage.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on November 25, 2017, 10:47:16 pm
It didn't cost me anything as I used parts from my old stock of electronic devices.
So replace brand new components with old ones in unknown condition?  :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on November 26, 2017, 12:57:28 am
I folks !

Finally I've decided not buying a new power supply, but making some modifications to the stock PS Feeltech.
I've focused my work on the caps and I would say that it's worth it.

The output filtering capacitors were swapped with low ESR and higher voltage ones.
Main front end circuit, a new high voltage cap 68µ/400v now takes place instead of the old crappy one (10µ/450v)
And last but not least, I've added a second HV cap between 0V and the unconnected mains.
It didn't cost me anything as I used parts from my old stock of electronic devices.

Why is that transformer at that ridiculous angle, surely you sorted that out? :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 26, 2017, 08:23:05 am
So replace brand new components with old ones in unknown condition?
I never said that all my old stock is vintage, and I tested them before mounting on the PS pcb.
Reuse quality components for servicing is better than use brand new ones with low performances imho.

Quote
Why is that transformer at that ridiculous angle, surely you sorted that out?
Not at all, the FY6600 was delivered with the transformer in this position.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bianchifan on November 26, 2017, 12:33:32 pm
2. Then, I replaced the dodgy output amplifier op-amp. The original one is an unknown 30021. At first I thought this is a dual variant of the single THS3001 but some guy has inquired about it from Texas Instruments and they replied that they do not manufacture such.
Your dodgy crappy unknown 30021 are very well known 3002I -> THS3002 with extended operational temperature!
They are used frequently in FeelTech Signal Genarators (esp. 32xx) and often discussed in russian forums like mysku, radiokot, x-faq and so on...
For various reasons many people prefer them to THS3092, although 3092 can drive more current.
(https://img.mysku-st.ru/uploads/images/04/34/11/2016/07/06/aa2276.jpg)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 26, 2017, 03:19:59 pm
Mine came yesterday.  Being forewarned I plugged it in and took a meter to it.  50 V between BNC and earth ground.  FeelTech *really* should fix that.  It's a huge menace to anyone using it as a signal source for embedded work.  I've generally steered clear of such kit because of this.  The *only* reason I felt comfortable buying one was the information from this thread.  Hopefully FeelTech will take that to heart and modify the design appropriately.   I'm mostly going to be using it with MCUs, so the other mods are less important to me.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 26, 2017, 04:29:31 pm
I really still believe it is theoratically inherent to the 2-prong class II design. In other words, all non-ground connected SMPS have it.
How much they have it depends on the size of the Y-Cap, and that depends on how much they want to suppress EMI and how much power supplies
(Note to self, I need to check that 'real good' Samsung USB for EMI leakage (but I do not have the equipment) and floating while loaded)

So I believe a design change simply means, factory fitted with 3-prong cable.
Which is a good idea, for sure.

Please note: I am not saying its a good supply, but in my view, the leakage is not part of its badness.
What is part of its badness is being labeled at 12V but giving over 15V, unconnected 20V but having only 16V caps.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 26, 2017, 04:40:59 pm
What is part of its badness is being labeled at 12V but giving over 15V, unconnected 20V but having only 16V caps.

Yes. This is not acceptable. The output caps should be 25V rated if the supply is giving 15V. The other problem is that the main board caps are all surface mount and 16V rated also. I'll have to probe around and see what the voltages are, especially around the output amplifiers.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 26, 2017, 05:52:08 pm
I just connected my scope to the ground of the unit.  Yikes!  Yeah, it's 50 Vrms, but it's 174 Vpk-pk!

The first scope image is with the probe connected to the BNC ground, no ground lead connected.  The second image is the BNC ground lead of the FeelTech connected to the scope ground via a 100K resistor and probe across the resistor.

It's so bad I'm reconsidering whether to keep it.  I notice that there are no approval marking of any kind.  It shipped from CA which raises the question of whether it's even legal to sell it in the US.

Edit:

Here's the drop across a 10K resistor.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 26, 2017, 05:56:25 pm
Now do the same for any other 2-prong device you have.
It will be better for smaller power supplies, but most of them look scary.

You are basically just measuring mains through a 1pF capacitor.

Whether you want to send back or not is up to you, but of you keep it, just do the 3-prong+y-cap mod.
I now have about 1Vac, and it is still floating. Or hard-link to the GND for 0V
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on November 26, 2017, 06:01:22 pm
Quote
Why is that transformer at that ridiculous angle, surely you sorted that out?
Not at all, the FY6600 was delivered with the transformer in this position.
WTF is that all about then, is there something under it like thermal cutout or what, if there's nothing there then I would have certainly have corrected that, its a reasonable sized lump flapping in the breeze there and producing untold stresses on the PCB due to inherent vibrations.  :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 26, 2017, 07:14:37 pm
Now do the same for any other 2-prong device you have.
It will be better for smaller power supplies, but most of them look scary.

Interesting.  I just repeated the test with a 5V wall wart supply from a kit of Arduino stuff.  Very similar picture.  I'd never  considered the matter.  Good thing to be more aware of.  I'd never thought closely about ground loops in my bench setup, but clearly with a variety of power sources and grounds, it gets messy.

I'm looking it over closely.  I don't understand the main board SMD electrolytic markings.  Two are clearly marked 16 V, but most are marked "100 10S 3R7"  Has anyone got a decoder ring?

I shall certainly put a proper ground on it if I keep it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 26, 2017, 07:35:31 pm
I'd never  considered the matter.

Same for me, till this thread. Learned a bit

I have a old ATX power supply that I use for easy and beefy +5V and +12V (as well as minor -12V)
I had isolated them from ground, yeaaaars ago, never had a problem.
Probably because I always hook up 0V first, and then my DUT is referenced to that 0V.

But just to feel happy, I just added a capacitor and 1 meg resistor to ground there too (I like to keep it floating)
Now also looks a lot nicer. from 60Vac floating to 1Vac floating


Basically, the build in Y-cap crossing the transformer has to be significant larger (10x) then the inherent capacitance of the transformer itself, to avoid EMI.
And to counter mid-point "leaky" ac voltage, the cap from secondary 0V to ground should be significant (10x) bigger then that Y-cap
I believe this 2nd cap does not need to be Y, I am using X. Because it is not connected to mains. Also because I have those.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 26, 2017, 07:52:21 pm
Now do the same for any other 2-prong device you have.
It will be better for smaller power supplies, but most of them look scary.

Interesting.  I just repeated the test with a 5V wall wart supply from a kit of Arduino stuff.  Very similar picture.  I'd never  considered the matter.  Good thing to be more aware of.  I'd never thought closely about ground loops in my bench setup, but clearly with a variety of power sources and grounds, it gets messy.

I'm looking it over closely.  I don't understand the main board SMD electrolytic markings.  Two are clearly marked 16 V, but most are marked "100 10S 3R7"  Has anyone got a decoder ring?

I shall certainly put a proper ground on it if I keep it.
The caps marked 10S are 10V. I checked continuity and none are connected to the "12"V rails. They are connected to the 5V or come after some of the other linear regulators on the board. The 16V ones do have continuity to the 12V rails. Hopefully they hold.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 26, 2017, 08:19:49 pm
The 16V ones do have continuity to the 12V rails. Hopefully they hold.

When I worked on the supply, and had it disconnected, I measured 20V.
Before I connected to the AWG board again, I had the presence of mind to first discharge the power supply caps. Gave a bit of a zap. Imagine hooking up the AWG board with 20V precharged into the caps...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on November 26, 2017, 08:26:31 pm
My supply measured 15.8V when unloaded. Appears to be a lot of variability, at least when measured unloaded.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 27, 2017, 02:21:41 am
I worked up the nerve to connect it to my new scope.  The Instek spectrum analyzer demo allows the user to control the SA settings by pressing the lower right corner button  by the screen.  I've set it up for 0-100 MHz span.  As far as I can tell, this is the MDO line SA function.  It's a bit flaky, but seems pretty usable if you  can accept an RBW of 10KHz.  The white trace is a 16 point average of the spectrum.

The plots are 0.1 V, 1.0 V and 10 V output settings.  At low output voltages it looks quite good, but the harmonics get really bad above 1 V.  The obvious question is, is it the PS or the PA?

It seems to me the appropriate next step is to hook it up to my bench supply.

The SG is set to 5 MHz.  I'm using an MSO-2204EA.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 27, 2017, 02:43:49 am
For the sake of comparison here is the internal AWG on the Instek MSO-2204EA at 1 Vpk-pk and 5 V pk-pk.

Edit:

For completeness I've added the 0.1 V case.  The Instek built in AWG pretty much goes to hell around 1.5 V.  5 V is the max.

All the plots had a 6 dB attenuator inline to provide a 50 ohm match for the source.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 27, 2017, 06:18:05 am
That is undesirable. I do not have a SA myself (and my  rigol FFT is non-usable) but looking at this link (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1339656/#msg1339656) it should be much better.
Vpp is not mentioned, so I am assuming 5Vpp default.

Maybe your log steps of 0.1 - 1 - 10 are a bit too much, and the supply only falls short over 9Vpp
So mid-voltages are still good.

But this guy (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1348087/#msg1348087) does indeed claims both a better Op-Amp and a better supply are needed at 20Vpp.

Interested to see what it does when hooked to your bench supply instead of internal, but smaller steps please.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 27, 2017, 01:32:13 pm
The harmonics grow rapidly above about 1.5 V.  5 V was the limit on the Instek AWG.  I am unable to control the input attenuator in the SA demo.  So some of this may be sampling artifacts.  I'll repeat later today with the regular FFT function.  Unfortunately, that does not have the ability to super impose a running average of the spectrum.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 27, 2017, 10:41:06 pm
Here are screen shots with the generator running from an Instek linear bench supply feeding +- 12 & +5 V.  The harmonics start growing around 6-7 V.

For these I used the regular FFT function rather than the SA demo.  I think a lot of the harmonic distortion in the previous screen shots was the scope attenuator being set too low and clipping the ADC input.  The SA demo does not allow any adjustment of the input channel gain that I can tell.

There's a 6 dB attenuator inline to provide a 50 ohm termination to the FeelTech.

I'll repeat the same tests using the internal PS later.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 27, 2017, 11:19:32 pm
Here they are using the internal PS.  I can't see a significant difference toggling between the images.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 28, 2017, 05:57:26 am
Here they are using the internal PS.  I can't see a significant difference toggling between the images.

So if I read that correct:

+01Vpp -55dB
+05Vpp -55dB
+10Vpp -44dB
+15Vpp -31dB
+20Vpp -25dB

I actually think that is pretty good. That is still 25dB down at full 20Vpp swing....

I'd argue the old argument that it is only a $100 device, comparable features to a to a $900 Rigol DG1062Z
But to be quite honest, I think that Rigol may not fare much, if any, better at +20Vpp

For comparison, look at the remainder of this video (https://youtu.be/ML-lmuHoh-0?t=1792) on the previous generation of cheap awg.
If I can eyeball the distortion, imagine the spectrum on that?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 28, 2017, 01:47:14 pm
I think it is quite good, especially for the price. And with my embedded & SDR  focus I can't imagine a need to go above 5 V.  I've noticed that there is a relay click when going from 5 to 6 V.

For my purposes I think all that's needed is to suppress the AC leakage.  Which raises a question.  One Y cap or two?  I'd never even heard of them, but the last time I was heavily active in electronics (i.e. had a bench set up) most supplies were linear.

While fooling around last night I noticed some curious behavior for ARB28 when I varied the frequency setting.  So an investigation of the frequency axis seems in order for this evening.  Unfortunately, it appears that either the dual display FFT or the V 1.32 FW update removed the ability to display an FFT all the way to Nyquist which is rather annoying.  So I got a better UI at the price of reduced functionality.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 29, 2017, 01:19:25 am
Here is a plot of 1 MHz at 1 V.  Cursor measurements give the following:

2nd  -60
3rd   -64
4th  -60
5th  -60
6th  -52
7th  -62
8th  -60
9th  -60

Noise floor -72

The Instek SA demo is set up with the internal function generator a 1 V.  The input attenuator setting is unknown, however, I should expect that Instek made there demo look as good as possible.  So I think the results are reasonably accurate within the limitations of 8 bit sampling.  Looks quite good to me. In fact, amazing.  I don't want to think about what it would take to build an analog 1 MHz oscillator with equal performance.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 29, 2017, 02:17:53 am
Here are spectra at 1 V for 10-60 MHz in 10 MHz steps.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 29, 2017, 02:39:52 am
Same setup, but 1 MHz span
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 29, 2017, 07:11:49 am

I wonder if those sidebands (at roughly 30KHz / 300pSec offset) are jitter from the oscillator.

Would be interesting to see if they still exists after replacing that oscillator with that NB3N502 PLL that supposedly only has 15pSec jitter
Either ArthurDent needs to check that, or I need to buy a decent Spectrum Analyser.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 29, 2017, 03:31:06 pm
It appears to be a sampling artifact.  Here's what an RSP2 says set to 5 MHz BW.  10 MHz BW is similar.  The display is *very* different with narrower BW to the point of not seeing a pronounced peak at 40 MHz.  Not sure what is going on.

I've added a shot with the RSP2 set to 4 MHz BW.  Very strange.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on November 29, 2017, 09:26:49 pm
It appears to be a sampling artifact.  Here's what an RSP2 says set to 5 MHz BW.  10 MHz BW is similar.  The display is *very* different with narrower BW to the point of not seeing a pronounced peak at 40 MHz.  Not sure what is going on.

I've added a shot with the RSP2 set to 4 MHz BW.  Very strange.
Actually it isn't so strange at all, a SDR is not a spectrum analyser with professional specifications.
I think that relevant spectrum analysis can only be done with a spectrum analyser, and fortunately I own one.
I'll send full detailed spectrum traces to that thread in the next coming days if someone is interested in (no time for doing that right now)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 30, 2017, 04:07:24 am
Turns out the front end was being overdriven and went into oscillation when the bandwidth changed.  Not yet sure why it does that.

An SA is the next item on my shopping list, but good ones are expensive.  The RSP2 does a pretty good job over a 10 MHz span.  So combined with the FY-6600 it should be usable for checking filters for HF.

The sidebands displayed by the RSP2 are very different from the picture presented by the scope FFT.  For close in, I'm much more inclined to believe the RSP2 as the RBW is much smaller.  There's really not a lot of control of the FFT parameters on the scope and the dynamic range is also smaller.

For "no-signal" I just disconnected the AWG.  It seems likely that the RSP2 close in spectrum is the more accurate.

It would be very helpful to have spectra from a calibrated commercial SA to compare to the RSP2 and scope FFT plots.  I'm trying to sort out which of these things I should believe and when.  So references are very helpful.

I fitted a grounded plug to my FY-6600, but still need to get Y caps for it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on November 30, 2017, 06:28:17 am
I fitted a grounded plug to my FY-6600, but still need to get Y caps for it.

In my view:

Y-cap are safety. Because mains to any touchable item *must* be safe, even when it fails, they must be super safe, tested to 10KV as well as (I presume) lots of mechanical stresses. That is why the capacitor spanning the transformer must be a Y-cap, as it is potentially violating the galvanic isolation.


But you are planning to put a cap between an already safe item (the BNC is already touchable safe) and earth (also already touchable)
So while the habit for these things is to talk about y-caps, other caps should also be OK. I did put a Y cap, because I had one, but on my other 2 supplies that I modified, I put X-caps (because I had only 1 Y-cap)

Also, as I wrote earlier, the mains-to-0V Y-cap should be significantly higher then the transformer parasitic capacitance
And the cap from 0V-to-earth should be significantly higher than that to divide up the floating mid-voltage to null potential as much as possible.

But it should not be too high. At least, not if you really want to use the signal gen as floating.
Because it does have "probe loading" consequences. If/When you connect the signal to a DUT that is not 0V potential, it will first have to charge the cap to whatever potential the DUT is. And you do not want that to be too much of a jolt.


So the original Y-Cap is about 1nF (I measured)
The extra Y-cap I used is 4.7nF (that was the only one I had)
I would try to not make it higher then 10nF


Of course, I am new to this particular topic, so do take my view with some critical thinking.


It would be very helpful to have spectra from a calibrated commercial SA to compare to the RSP2 and scope FFT plots.  I'm trying to sort out which of these things I should believe and when.  So references are very helpful.

I was also playing with SDR based SA. But I did not get any result that I would think usable. Nice to locate FM radio stations.
But as electronics SA: when you know what peaks to expect, you can find them. But only being able to find what you already know is there is of limited use. And I have to many other peaks that I suspect are artifacts, clouding up the picture.

Of course, my SDR is one of those toy DVB-RTL sticks that I had lying around. That RSP2 does look like it is giving better screens, but are they true?
If not, it may be better to not spend $150 for a RSP2, and put that toward a real SA instead?



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on November 30, 2017, 06:40:57 am
Would like a SA but luckily I can 'borrow' some time on a nice HP if needed  8)

Toy Budget left this week -$500+ pushing four figures  :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 30, 2017, 02:33:10 pm
There are lots of spurs as there are in any radio,  SDR or analog.  I'm quite happy with the RSP2.  The software less so, but SDRuno seems to provide pretty usable displays.  Now that I have serviceable signal sources I think I'll start a thread on the RSP2 showing it's application to filter characterization, etc.

The thing that is needed most for using an SDR as an SA is the ability to store a reference trace and then divide by the reference trace.  That would allow correcting for internal self noise and source variations and is a standard feature on an SA. Hopefully someone with access to an SA and an FY-6600 will repeat my examples and post them.  I'm most interested in the "signal", "no-signal" example with the small RBW.  I'd really like to know if that's a proper result.  The software aspect of T&M kit makes me reluctant to trust anything very much.

The LimeSDRmini should be a good low cost, wide range SA-TG with appropriate packaging and software.  I've got a LimeSDR which I bought mostly for use as a test instrument.  Still working on suitable packaging.  They get hot and they need shielding.  The RTL and RSP are based on clever use of TV tuner chipsets.  There's a wave of much more general chips coming along which should provide substantially better performance.

Now that I've started using Windows, I'm considering a VNWA from SSDR-kits very seriously.  The support in the yahoo group is excellent.  For a long time I refused to use Windows, but I find Linux not all that much better and there is far more Windows EE software available.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on December 02, 2017, 01:41:22 pm
Hi folks
for those who are interested in some measures relatives to the HF behaviour of our beloved one, here it is.
SA is a Rohde & Schwarz, Professional reference in Spectrum analysis.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: technogeeky on December 03, 2017, 06:54:21 am
Hi folks
for those who are interested in some measures relatives to the HF behaviour of our beloved one, here it is.
SA is a Rohde & Schwarz, Professional reference in Spectrum analysis.

That's actually pretty damn impressive.

The two anomalies that I see are between picture 14 and picture 15 (why is there a 10dB rise in the noise floor, but only on the lower sideband?), and between pictures 16 and 17 (why would moving from 14.8 MHz to 14.9 MHz add some comb of spikes just above the noise floor?). I don't think either of these two things are deal breakers (after all, these two problems lie 70 dBc and 65 dBc down, respectively). But I would be curious to hear a hypothesis about them.


And just for reference, please edit the post to include the exact model of the specan and the R/S signal generator (not that I doubt their performance, but perhaps someone wants to get a sense of the instrument's noise floor and phase noise).


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 03, 2017, 06:58:15 am
I also have the impression the source column in the table may be incorrect.
Or else I cannot explain 14,15 and 16,17, why measure the same thing twice on the same device?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: technogeeky on December 03, 2017, 09:13:23 am
I also have the impression the source column in the table may be incorrect.
Or else I cannot explain 14,15 and 16,17, why measure the same thing twice on the same device?

It's not the same. I think he must have noticed that a small difference in frequency (10.7M vs 10.8M, and 14.8M vs 14.9M) causes marked differences in output.

The center frequency is the same, but the actual main tone can be seen shifting in both cases.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on December 03, 2017, 10:09:31 am
It's not the same. I think he must have noticed that a small difference in frequency (10.7M vs 10.8M, and 14.8M vs 14.9M) causes marked differences in output.
The center frequency is the same, but the actual main tone can be seen shifting in both cases.
Yes, that was my point, focusing on figures at particular frequencies.
For instance 10,7MHz, at this specific frequency, the noise floor raise suddenly 10db on the lower frequencies, really strange behaviour indeed.

The test equipments that I use are :
SMG = 801.0001.52 Rohde Schwarz signal generator 0.1-1000MHz
SA = FSC 3 Rohde Schwartz spectrum analyser 9k-3GHz
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: hainjedaf on December 03, 2017, 04:06:42 pm
Maybe a dub question, but I hope to learn:

I have a switchmode PSU (MeanWell PT-45B) kicking around. Would this be an improvement to replace the FY6600 psu?
Of course I'd add a grounded mains connector.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 03, 2017, 06:29:42 pm
In my view: Yes, but No.

Its too big, physically. Its also a bit of a waste, because its unneededly big, electrically.

It will also not get you any better leakage result then simply adding a 3-prong and connecting to ground:
Note the specifications of that supply (http://meanwellusa.com/productPdf.aspx?i=660#1) give you <0.5mA (or <500uA) leakage current, a lot worse than what is already in the FY6600. This is because the leakage is a function of the power a supply can deliver and as already stated the Meanwell is unneededly big.

It would really only improve the fact that the unknown Chinese PSU may blow its caps sooner rather then later and take the AWG with it.
Which is a big deal I suspect,

So while I am as yet choosing to keep the original supply, I cannot state that is a good idea. But that Meanwell is not a good choice.
Go with a smaller one. Or replace the 16 caps with 25V ones and add a 3-prong.





Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: hainjedaf on December 03, 2017, 07:48:25 pm
So updating the caps in the original PSU would serve better purpose.

Where does one hook up the PE lead? Secondary ground?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: don.r on December 03, 2017, 07:53:37 pm
So updating the caps in the original PSU would serve better purpose.

Where does one hook up the PE lead? Secondary ground?

That would be the easiest. The 25V caps don't fit in neatly as space is tight on the output side but they can be mounted a little off the board. Grounding should be on the secondary side, there is an empty pair of ground pads near the PSU output jumper that can be soldered to.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on December 03, 2017, 09:03:10 pm

I wonder if those sidebands (at roughly 30KHz / 300pSec offset) are jitter from the oscillator.

Would be interesting to see if they still exists after replacing that oscillator with that NB3N502 PLL that supposedly only has 15pSec jitter
Either ArthurDent needs to check that, or I need to buy a decent Spectrum Analyser.

15ps is high :)
with 15ps of jitter and ideal analog output driver, we have:
@4.2MHz the ENOB<11Bits
@8.5MHz the ENOB<10Bits   ------>    SINAD<62
@15MHz the ENOB<9Bits      ------>     SINAD<60
@34MHz the ENOB<8Bits
@69MHz the ENOB<7Bits      ------>    SINAD<44
any bad layout, power supply noise, bad selection op-amp,... will ruin the performance.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on December 06, 2017, 05:14:13 am
The array of modifications various posters have come up with to improve the FY6600 is interesting and depends a lot on what that particular user’s main requirements are. My first interest was mainly to make the FY6600 safer by including a real ground through a 3-wire power cord and not to rely on an iffy virtual ground.  Secondly I really wanted to make the timebase more stable and a LOT more accurate with the option of using an external 10 Mhz reference from GPS or a rubidium source. Along the way I discovered the existing power supply was crappy and not what I considered fixable so that had to be replaced as well. The grounding and timebase modifications I made worked as well as I hoped they would so that left the power supply and possibly the output amp that others considered lacking.

Recently I tried replacing the output amps as others had recommended and didn’t see that really improved anything for me and went back to the original single chip. I rarely go above 5 volts output so this modification wasn’t that high on my to-do list. Others have run the FY6600 main board on +/-15 to improve the output at higher levels with no reported problems but I was still worried about a possible failure. I had tried a +/-15 vdc supply I modified to put out about 14.2 vdc to perhaps give me a little more margin of safety. I was uneasy in running the main board at a full 15 volts with the caps on the board rated at 16 volts (as others have mentioned) plus I wasn’t so sure that some of the other parts wouldn’t be stressed by the higher voltage. Almost all SMPSs have one adjustment for the +5 and the other two supplies are ratios of that so to just use that adjustment to lower the +/-15 supplies to about 14.2 volts, which I thought might be safer, would mean that the +5 would be lowered as well by about .3 volts, and I didn’t find this acceptable. What I tried was to put a conventional 3-amp diode in series with the two + and – supplies which would drop those voltages by about .8 to .9 volts while leaving the +5 right on.

While that worked to lower the +/- voltages a little and made me feel a little better, the supply I used that just fit in the space in the case was a supply capable of supplying 60 watts. This meant that although the main board doesn’t require much power, the supply used 10 watts and most of that was given up as heat and the FY6600 ran warmer than I liked. The first 40 watt +/-12 vdc supply I tried was a little more efficient but still generated some heat and used about 8 watts. The supply I settled on was a 25 watt +/-12 vdc supply I have shown previously that uses only 6 watts when powering the FY6600 and 4-5 watts when the front switch is turned off but parts of the main board are still powered. Keep in mind that the OCXO that I used as a timebase stays powered when the back switch is on and does use about 1.5-1.8 watts when it is at temperature but that doesn’t contribute much internal heat.
 
Here are 2 photos. One shows how I added the diodes in series with the +/- supply lines and bypassed then with a couple of tantalum capacitors if anyone might want to try that. The second photo is of the 25 watt supply I showed before. I’m pretty sure these are all the modifications I’ll be making to the FY6600 but I’ll keep reading to see what other great ideas others come up with. In a way I spent more time with the FY6600 apart than with it together and doing what amounts to trying to make a Ford run like a Mercedes when I might have been better off buying the Mercedes in the first place! 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on December 06, 2017, 05:42:11 am
Oh, and one thing I've wondered about and it might be worth checking into, is the failure rate on the FY6600. One reason a lot of people are concerned about the leakage voltage on the output is that it could zap whatever you're connecting the FY6600 to. Is it possible that if you have an ungrounded FY6600 that you could zap it by touching the keypad? Capacitive coupling of the leakage voltage through the keypad could possibly account for this. Maybe there should be a poll of those who have had failures, especially of the display being garbled, to see if there is a correlation between ungrounded units and number of failures, or if it's just random.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 06, 2017, 05:57:32 am
Happy enough with mine with Earthing and extra Cap. Tweaks to the OpAmps were also well worth the effort IMO.

Disappointing that Feeltech haven't jumped back in to help out. The 'send it back to the factory' isn't adequate at this price point or day and age of 'easy' online firmware upgrades for plenty of other equipment.

If they chose to open source the firmware even and open themselves up to hackers and modders might see a boon in their sales numbers and be able to pick and choose mods by users to keep in the official firmware at little cost to themselves.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 07, 2017, 03:49:14 am
After I finished adding a ground and reassembled the unit, I ran it on the bench for an hour or so measuring the frequency with a counter and looking at the amplitude fall off at slightly over 50 MHz.  I put it aside (very cramped work space).  After supper I hooked it up to a scope to do some more analysis.  Borked display!

It works, but the display and UI are buggered, *exactly* the same as shown in the start of the thread on reflashing.  So it's obviously a pretty consistent defect.  I'm not clear on how cybermaus read the flash.  I chased some links, but didn't get anywhere.  I'll do some detailed testing to see if all the functions still work.

In looking at it, I notice that several chips next to the FPGA  have had the markings sanded off.  Has anyone else seen that?

Ironically, I had just given it a very positive review on eBay shortly before discovering it had borked itself.

 JK1 on the front panel board is the STM32 programming interface.  I just checked the pinout on the datasheet. Looks to be Spy-by-Wire.  I'll have to look at my collection of STMF32 boards to see if I can use one of them as a programmer/debugger.

There's been enough work done evaluating the unit, that I hope FeelTech will realize that they need to fix the bug and support the EEVblog community.  If it were reliable, it would easily be a very popular AWG.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 07, 2017, 04:29:17 am
All the waveforms seem to work except  SQUR, ADJ-PULSE and ARB33-64.  DC offset works. The other UI options seem a bit confused, but mostly seem to work.  A bit hard to test as I haven't had the unit long enough to get acquainted.

It is actually producing  NegRamp at the weird frequency that appears on the display at power up and the Vpp shown!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 07, 2017, 05:30:12 am
Damn. another one.

As to how I read the flash: I read the wrong flash.
Since my original happy post, we learned that I read the FPGA and waveform flash, but the GUI and control flash is in the STM32 and that is the one that fails. Which alas is protected from reading. So we are at a dead end there.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jleg on December 07, 2017, 10:46:57 am
All the waveforms seem to work except  SQUR, ADJ-PULSE and ARB33-64.  DC offset works. The other UI options seem a bit confused, but mostly seem to work.  A bit hard to test as I haven't had the unit long enough to get acquainted.

at this very similar stage i did a "factory reset" (load factory defaults from system menu) - after that, also the last working wave forms vanished...

The interesting question is: what firmware version does your FY6600 have? The current "hypothesis" is, that it is propably a bug of V3.0 specifically..
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 07, 2017, 02:17:34 pm
Mine is version 3.0.  Thanks for the warning about doing a factory reset.

I think it's time to sniff the cables from the front panel.  Has anyone checked the USB - PC connection?

Based on Ebel0410's spectrum analyzer plots, the signal generation board is very good.  So finding an alternative UI is well worth while.

As FeelTech is t least aware of this thread I hope they're paying attention and will respond appropriately.  There is certainly nothing in the UI worth protecting.

I still want to know how cybermaus read the flash.  I was already aware it was just the signal generator flash, but not the details of how.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 07, 2017, 02:33:30 pm
I did not sniff the USB connection, no, but I am not expecting anything of note in there, just the sending of control commands, but no way to read the flash.
Saying that out loud, I realize you may still be able to fully control the device, maybe even re-upload waveforms, using the PC program. But that is speculation.

I (and one other person) did hook up the STLINK to the STM32, and the flash is read protected, and unreadable, unless if you are a university level hacker (https://www.usenix.org/system/files/conference/woot17/woot17-paper-obermaier.pdf).

As to how exactly I read the FPGA and waveform flash: Please study this post and its video (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1352448/#msg1352448), and if that is not enough, please at least have specific questions about what steps you have trouble with. There is also a follow up post on the flash data structure.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jleg on December 07, 2017, 02:36:42 pm
Mine is version 3.0.  Thanks for the warning about doing a factory reset.

...looks like we now have 3 confirmed failures of this type, all with FW V3.0.

Afaik, current version is 3.2, so perhaps it is safe to try again and order a new one?  Hmmm... ::)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 07, 2017, 02:56:13 pm
 I would suggest no, because you should not reward this behavior?

If anything, you should nag them about warranty and refund, and if they go the "return at own expense" route, nag further about either the expense, or about at least sending out a pre-programmed STM32 for self-repair.

(Easy for me to say, I know, mine is still working. I am not sure I would could bring up to invest time in such a thing)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on December 07, 2017, 03:57:37 pm
I just checked the revision on my FY6600. It is V3.1 and it is still working properly. If the problem is only associated with V3.0 and newer/older versions are ok then I would think FeelTech would be obliged to offer those owners with V3.0 an free upgrade because they didn't get a properly working FY6600 that they paid for.

Some years ago I worked for a company that made a test instrument that had firmware burn into an eprom. Our customers were spread all over the U.S. and a very few scattered customers reported a strange intermittent problem. Seeing these instruments were used for billing huge dollar amounts this was a big deal.  Two of the instruments were sent back and I spent days trying and not being able to duplicate the problem until finally I saw the problem. It took some time to figure out what steps I had done to get the problem to appear because I had pushed a lot of buttons in multiple random steps to get there but I finally remembered enough of what I’d done to duplicate the problem repeatedly. What happened was that one data field had a fixed length and if you entered about 10 unique and not that common steps that data field length was exceeded, pushing data into the next field and someone would be billed many times what they should be.

It could be that in trying to improve the way the FY6600 worked in one area FeelTech inadvertently screwed up something else. It doesn’t seem likely that this could be a hardware problem from what you’re saying about V3.0 so it’s time for FeelTech to do something about offering a solution.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 07, 2017, 04:18:46 pm
I reread everything, watched the video and looked at all the pictures.  As I don't have one of those CH346s I was going to use a different device.

So to summarize:

The unpopulated header, S1,  next to the FPGA was what was used to access the Winbond  flash.

The PC software can't talk to the device properly even though I can still partially control it via the front panel.  However, it is less than stellar software, so a check by someone with a different FW version would be good.

I was referring to sniffing  the 8 bit bus from the front panel to the AWG board.  That's key to writing new UI firmware.  That should be a pretty simple command protocol.  So it should not be hard to reverse engineer.

There is also an XON/XOFF RS232 port coming from the UI board.

FWIW I read the Fraunhofer paper some time ago, so that has been in the back of my mind all along.

I'm going to raise the repair question with FeelTech to see if they consider the warranty void because of the ground modification.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 07, 2017, 04:27:01 pm
I would not even mention the ground modification, unless if they specifically ask about it.
If they do ask about it, it means they do read this thread, and are aware. Maybe no legal weight, but definitely moral weight into the matter.

They will try and evade the warranty by claiming you need to pay for return.
So my advised argument would be they are responsible for that. If they want to fix it, send out new device, front PCB, or maybe even only the STM32


but as mentioned, easy talk for me, I do not need to invest the time and effort.


Edit: the PC software does work for me to control the device. Pretty well even.

Edit2: Not that I think they will offer it, but anyway: Only accept a preprogrammed STM32 as solution if you have confidence in your own ability to solder it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: feeltech on December 09, 2017, 12:56:09 am
The array of modifications various posters have come up with to improve the FY6600 is interesting and depends a lot on what that particular user’s main requirements are. My first interest was mainly to make the FY6600 safer by including a real ground through a 3-wire power cord and not to rely on an iffy virtual ground.  Secondly I really wanted to make the timebase more stable and a LOT more accurate with the option of using an external 10 Mhz reference from GPS or a rubidium source. Along the way I discovered the existing power supply was crappy and not what I considered fixable so that had to be replaced as well. The grounding and timebase modifications I made worked as well as I hoped they would so that left the power supply and possibly the output amp that others considered lacking.

Recently I tried replacing the output amps as others had recommended and didn’t see that really improved anything for me and went back to the original single chip. I rarely go above 5 volts output so this modification wasn’t that high on my to-do list. Others have run the FY6600 main board on +/-15 to improve the output at higher levels with no reported problems but I was still worried about a possible failure. I had tried a +/-15 vdc supply I modified to put out about 14.2 vdc to perhaps give me a little more margin of safety. I was uneasy in running the main board at a full 15 volts with the caps on the board rated at 16 volts (as others have mentioned) plus I wasn’t so sure that some of the other parts wouldn’t be stressed by the higher voltage. Almost all SMPSs have one adjustment for the +5 and the other two supplies are ratios of that so to just use that adjustment to lower the +/-15 supplies to about 14.2 volts, which I thought might be safer, would mean that the +5 would be lowered as well by about .3 volts, and I didn’t find this acceptable. What I tried was to put a conventional 3-amp diode in series with the two + and – supplies which would drop those voltages by about .8 to .9 volts while leaving the +5 right on.

While that worked to lower the +/- voltages a little and made me feel a little better, the supply I used that just fit in the space in the case was a supply capable of supplying 60 watts. This meant that although the main board doesn’t require much power, the supply used 10 watts and most of that was given up as heat and the FY6600 ran warmer than I liked. The first 40 watt +/-12 vdc supply I tried was a little more efficient but still generated some heat and used about 8 watts. The supply I settled on was a 25 watt +/-12 vdc supply I have shown previously that uses only 6 watts when powering the FY6600 and 4-5 watts when the front switch is turned off but parts of the main board are still powered. Keep in mind that the OCXO that I used as a timebase stays powered when the back switch is on and does use about 1.5-1.8 watts when it is at temperature but that doesn’t contribute much internal heat.
 
Here are 2 photos. One shows how I added the diodes in series with the +/- supply lines and bypassed then with a couple of tantalum capacitors if anyone might want to try that. The second photo is of the 25 watt supply I showed before. I’m pretty sure these are all the modifications I’ll be making to the FY6600 but I’ll keep reading to see what other great ideas others come up with. In a way I spent more time with the FY6600 apart than with it together and doing what amounts to trying to make a Ford run like a Mercedes when I might have been better off buying the Mercedes in the first place!


Thanks for using our products, we will replace the three-core plug in the next version to improve the stability.
If you have better comments or suggestions can be sent directly to the mailbox: admin@feeltech.net
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 09, 2017, 02:31:01 am
I sent FeelTech an email about my scrambled V 3.0 unit earlier today.  In it I linked both this thread and the reflashing thread.  I also explained about the grounding mod I'd done and why.  I saw the response in the reflashing thread even before I read the email response sent to me. That's *real* customer responce!

I've contacted the eBay seller about getting a new front panel so I can avoid redoing the power plug mod.  I added 200 nF from the PS ground to the plug ground which lowered the voltage on the BNC ground from 176 Vpp to 1 Vpp.  More work than I expected, but worthwhile.  The fiddle was because I had to add a small metal brace to support the plug receptacle I scavenged from a dead PC PS.

I rather hope they'll offer a revised unit with external reference input and a sweep ramp output.  I'll be very happy to buy another one with those features.  It makes them very handy for checking HF filters, etc.  You *can* do that by triggering on the width of the first sync pulse, but it's more fiddly than just using XY mode.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 09, 2017, 06:47:19 am
Amazing responses both threads.  :-+ Please keep us updated on how this warranty repair stuff works out.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 09, 2017, 05:30:50 pm
I sent "admin" a link specifically to Ebel0410's spectrum analysis post. That's pretty powerful marketing material for FeelTech. I've also noticed that there is another clone called Koolertron.  The other ones have nicer cosmetics, but lack the back panel options.  FeelTech has a number of variants, some in aluminum cases, but lacking the back panel connections.

The timing of ArthurDent's summary was quite fortuitous and feeltech's quoting it very encouraging. 

It would be very interesting to know who the designers are.  I noticed last night that Hantek offers design services both initial and updates.  It's entirely possible that the instrument section of FeelTech is a couple of people working in an LCD manufacturing plant who got funding to buy a design and market it.  If you think about it, the reluctance to provide schematics and source code may be contractually required by a design house when a manufacturer licenses a base design.  It would be interesting to hear from blueskull or some other Chinese member familiar with electronics manufacturing in China.  The "cloning" might not represent IP theft, but rather reflect product design as a service.  I can easily see a small manufacturer with excess capacity buying the rights to use a variant of an existing design rather than engineering there own product.

The seller, sportsgogo, replied saying they were contacting the supplier about my request for a new front panel.  I spent a long time last night browsing the sportsgogo eBay store "industrial" section.  Staggering assortment of goods. They have warehousing in the US, so if they will allow returns to the US rather than China I may shop there a good bit more.  I don't like buying expensive stuff direct from China because of the cost of a return.  But I'd be much more comfortable with shipment from China if I could make a return to a US location.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on December 10, 2017, 02:54:37 am
It would be very interesting to know who the designers are.

I agree that it'd be great to know more about the designer(s) of the FeelTech equipment. I had heard that they used to work for or have been otherwise associated with one of the competing companies in the space. Unfortunately, I don't have anything more concrete than that.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 11, 2017, 05:43:30 am
Slow day in the shack today. Such as the frequency measurement on the 34401a is. Very consistant with 30 minutes to an hour at each stop. Bit of flicker at 1Meg but most likely the agilent.

I have a couple of aged Polytron ocxo on the way to play with and make a 10Mhz standard not that I need better than it is  8)

Currently running 10.00042 Hz
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 12, 2017, 08:07:36 pm
As you may have seen in the other thread I've decided to spend some time reversing/redoing their FP software and got me one of the devices from a supplier that claims it's in Germany.
Before it arrives, cybermaus, did you hook the debugger and read the protection level, is it one or two ?
The panel controller is confirmed STM32F103C8 ?

  Best regards,
  DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 13, 2017, 03:30:07 am
Its one.

Though it is always possible they changed it to two on later builds / firmware's especially with all these links to Frauenhofer around.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 13, 2017, 07:06:50 am
Cool, that's nice to know, I'm curious what will be the level on mine, but as I've said, if we can recover the firmware it's perfect, to allow for a fast "clean room" implementation, similar with the Compaq and original PC BIOS, to get rid of all the copyright crap, if not, reversing the FP schematic and communication protocol with the signal board is the way to go, there are TONS of libraries for LCD driving and key matrix reading, hey we could even implement a FW update using either the USB or the, now useless, serial port header on the PCB.

Also, if its the level 2 already programmed, I've asked a more HW oriented friend what can we do, besides un-soldering the chip, and his response was disconnecting the power supply, and replacing it with a pulsing slightly negative current supply, something like 1KHz /-0.6V/few mA just to put the protection diodes in conduction, but not overload them, and then blasting the chip with a cooling spray to at least -25C or lower.
2-3 cycles and the flash content is gone, or so he says.
If I'll have to replace the chip anyway (if level 2 protection is programmed) I may try this before replacing the chip.

Related, if someone who had the generator FP borked, and can sell or loan the defective device/FP for a reasonable price, including shipping to Germany, for research purposes, please PM me. In case of a loan I promise to follow the pharmacists principle "Primum non nocere, hic curare" so it will most likely not have its state worsened.
 

Its one.

Though it is always possible they changed it to two on later builds / firmware's especially with all these links to Frauenhofer around.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on December 15, 2017, 01:25:28 pm
Screw cleanroom, just throw the ripped flash on a torrent and publish improvements as binary patches.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on December 16, 2017, 07:40:51 pm
Hi!

My plan to buy one to document on this Forum has borne fruit and I'm expecting delivery after the Christmas Holidays!

I'll be posting pictures, details of FW version, waveform samples, plus circuit-details, parts lists, etc., rev'd from the unit exactly from as I receive it, and I'll report the effect of the OEM's "Factory Reset" - if it borks the unit then I'll send the STM32 FP Assembly to Member DC1MC for his perusal!

Unfortunately I haven't got (can't afford yet!) one of those nice colour-screen LED Oscilloscopes that other members publish their oscillograms from, I can only offer ordinary analogue 'scope trace pics for now!

Chris WIlliams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 16, 2017, 11:34:09 pm
Hi Chris, thanks for the offer, it's gladly accepted, but let's hope that yours and mine won't do any borking at all and we'll do all the research just for the purpose of opening the firmware and extending the functionality.
Mine hopefully will arrive some time before Christmas so I can profit of the little vacation.
Don't worry about the scope, the time for it will come, but most likely you'll need some cheap Logic Analyzer because I'd say that the first thing is to sniff and decode the protocol between the FP and the signal board. Once this is done then the signal board could be controlled form other sources as well, I'll eventually produce a remote control device using the 7,99EUR OrangePi Zero that is a neat Linux system and much easier to program for non-trivial stuff than an Arduino (IMHO),.


Hi!

My plan to buy one to document on this Forum has borne fruit and I'm expecting delivery after the Christmas Holidays!

I'll be posting pictures, details of FW version, waveform samples, plus circuit-details, parts lists, etc., rev'd from the unit exactly from as I receive it, and I'll report the effect of the OEM's "Factory Reset" - if it borks the unit then I'll send the STM32 FP Assembly to Member DC1MC for his perusal!

Unfortunately I haven't got (can't afford yet!) one of those nice colour-screen LED Oscilloscopes that other members publish their oscillograms from, I can only offer ordinary analogue 'scope trace pics for now!

Chris WIlliams

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on December 18, 2017, 09:57:59 pm
 I don’t have a real spectrum analyzer but I get a fairly good idea of how much jitter my FY6600 output has by observing the waveform on my scope at the highest sweep rate and lowest volts/division and also plotting the output frequency over time using a computer program. This plot also gives me a good presentation of how the OCXO I installed in the FY6600 drifts during warm-up after it has been off for a few days. I set the output to 3 volt and a sinewave of 10,000,000 Hz and then plotted this output compared to a modified Trimble Thunderbolt GPSDO and Lady Heather software so I’m not just checking the oscillator output against GPS but checking the output of the FY6600 after it has done all its magic to produce this frequency and waveform from the OCXO. There is always a retrace error with crystal oscillators so on every power-up they never settle on exactly the same frequency but are very close. On this test the 10,000,000.000 Hz output settled at about 0.047 Hz higher than the 10,000,000 Hz I set the OCXO to the last time I used it. This is why on frequency standard OCXOs once they have stabilized and have been adjusted you leave them on.   

Initially at turn on the output was high (low on the graph) but within 10 minutes it was almost at the exact frequency. For the next 20 hours the frequency increased about an additional .04 Hz before leveling off at about .047 Hz high. As long as the switch on the back is on the OCXO and parts of the main board have power but the display is blank. Because the internal timebase is close enough for most testing I would use it for I have found that leaving the switch on the rear panel off and having this small error isn’t a problem. If I need a really accurate frequency I have the added switch on the rear to switch from the internal timebase to one of my external standards which is always on and far more accurate and stable.  Even though the frequency of the FY6600 can be set in steps as low as microhertz I can’t see how I could use such small steps.

The attached photo shows the 10 Mhz output (in white) plotted over an almost 30 hour period. The first 20 hours the OCXO is warming up and settling at what will be its frequency for this power-up cycle. After about 20 hours the frequency is very stable but plotted over days and weeks you would see a smaller drift due to aging of the crystal. You can also see a slight temperature correlation after the 20 hour mark. Weight loss as atoms are ‘boiled’ off the crystal slab increasing the frequency slightly. The big dip in temperature (yellow graph) was cause by my house temperature being set lower at night.   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 18, 2017, 10:55:46 pm
Talk about turning a Ford into a Mercedes!

Very cool.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 19, 2017, 05:42:08 am
Second this, transforming the device from a "meh-OK" device to an "almost R&S generator quality" is an impressive feat.

I hope that I'll be able to duplicate or come close o it on my device.

 Congraturlations Arthur  :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 19, 2017, 06:18:20 am
Which replacement power inlet socket do you recommend ?

I like a lot these IEC320-C6 sockets, because the cables are less bulky then the usual ones:
https://www.mouser.de/productdetail/schurter/43000100?qs=sGAEpiMZZMv1TUPJeFpwblxZ%252bgbqW48rSymwXXVJLLw%3D (https://www.mouser.de/productdetail/schurter/43000100?qs=sGAEpiMZZMv1TUPJeFpwblxZ%252bgbqW48rSymwXXVJLLw%3D)

But I wasn't able to find any filtered or switched ones, given that they are mostly used for laptops AC adapters.

In case of a classical one, which model are you recommending, probably switched as well, I don't see too much space on the back panel.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 19, 2017, 06:47:15 am
I just used a cheap and cheerful Chinese switched one https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1343235/#msg1343235 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1343235/#msg1343235)

Staying IEC made sense as most other things on my bench already have them. A little off topic but  I also got a couple of these which tidied up my bench and gear shelf a lot. https://www.ebay.com.au/itm/Black-57cm-IEC-320-C14-Male-to-3-x-C13-Female-Y-Splitter-Power-Cable-Cord/331700358437?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 (https://www.ebay.com.au/itm/Black-57cm-IEC-320-C14-Male-to-3-x-C13-Female-Y-Splitter-Power-Cable-Cord/331700358437?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 19, 2017, 06:53:32 am
What about these guys. they are cheap cheerful AND filtered ?

http://www.mouser.com/ds/2/769/lcr082-971565.pdf (http://www.mouser.com/ds/2/769/lcr082-971565.pdf)

I just used a cheap and cheerful Chinese switched one https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1343235/#msg1343235 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1343235/#msg1343235)

Staying IEC made sense as most other things on my bench already have them. A little off topic but  I also got a couple of these which tidied up my bench and gear shelf a lot. https://www.ebay.com.au/itm/Black-57cm-IEC-320-C14-Male-to-3-x-C13-Female-Y-Splitter-Power-Cable-Cord/331700358437?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 (https://www.ebay.com.au/itm/Black-57cm-IEC-320-C14-Male-to-3-x-C13-Female-Y-Splitter-Power-Cable-Cord/331700358437?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 19, 2017, 07:01:23 am
...but checking the output of the FY6600 after it has done all its magic to produce this frequency and waveform...

This already amazed me last time, when you had the 10.123.456,78 MHz test. I would have thought that the clunky nature of the software would skip and misplace a tick every so often. But it seems that while the UI is clunky, the FPGA part is running very well disciplined. put 10.000.000,000 in, and you get 10.000.000,000 out
That means this device really can use a good reference.

As to being a Mercedes: Its still a cheap car. Just with a new state of the art ignition system.
But it is cool though, for us folk who look under the hood.

On the 3-prong plug: I just de-soldered one from the pile of junk recycle corner.
No need to buy anything fancy.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 19, 2017, 07:09:22 am
What about these guys. they are cheap cheerful AND filtered ?

Check the overall height? I think you may run into problems as that switch is a lot taller than the one I used.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 19, 2017, 03:30:27 pm
I scavenged a 3 prong from a dead PC PS which allowed me to keep the original switch.  The downside was a bunch of fiddle to fit a scrap of the PS case as reinforcement for the back panel.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 19, 2017, 03:48:14 pm
Similar. But I did at least put some insulation for anti-touch.
Because I suspect I may be busy inside the device more then outside it  :P
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 19, 2017, 05:02:24 pm
Yeah.  But mine borked itself before I got the screws back in the case.  I'd run it for a few hours on the bench with a scope and counter hooked up looking at various signals., particularly the ground to ground voltage.  Turned it off and went to bed.  Next day the UI was buggered.  So not much incentive to complete the task until I get a new front panel.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on December 19, 2017, 07:08:49 pm
Changing the A.C. connector on the back of the FY6600 from a 2-wire to a 3-wire is a very good idea but I don’t see an advantage to getting a connecter/filter. Almost every SMPS has a built-in filter so adding another one wouldn’t hurt but I see no benefit. Even the crappy existing SMPS that came with the FY6600 has a capacitor across the input and a common mode dual inductor in series with the A.C. line and that would probably be acceptable but if you replace the crappy SMPS with a good one it will have a filter that probably would be identical to the Mouser LCR-082 that was mentioned.

Here is a schematic of a generalized SMPS showing a typical built-in line filter with the Mouser filter as an insert to show how alike they are. All the SMPSs I tried had a well-designed input filter like the ones shown as well as inductors in the output lines for additional filtering.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 19, 2017, 07:20:33 pm
Indeed, you can see that filter on the photo's above: the black/copper colored horizontal coil on the left, above the yellow capacitor, and to the right of the white connector.

I did add a ferrite beat myself, because I had them anyway, and also I was fighting noise on my scope at that time.

(Turned out to be the 1200x300 office LED panel attached to the ceiling. Weird, because that was not a china purchase but an expensive one bought from a professional office outfitter. just goes to show: if you pay a lot, you may still get the Chinese crap, just someone else has a big margin for putting on a label)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on December 19, 2017, 08:20:21 pm
Cybermaus, your story about the overhead LED lighting causing interference reminds me of a slightly off topic story that is somewhat the same. A guy I met while hiking the Appalachian Trail and I would see each other every few years at some of the yearly hiker gatherings. He had lost his right arm above the elbow many years before and had a hook for his right hand. He was so adept at using the hook that he could open pop-top beverage cans with ease. Once when we were at one of these events sitting around enjoying an adult beverage he told me about how he had been involved with some of the early experiments on using nerve impulses to control a more natural looking robotic arm. He told me that one of the problems the designers ran into on the early prototypes was that when he would walk under a florescent light fixture that the RFI from the light would cause the robotic arm to go crazy and lurch uncontrollably.  Some shielding of the arm electronics cured that unforeseen problem. I still smile when I visualize him walking under a light.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 19, 2017, 08:23:04 pm
If everything goes OK, this guy will be able to fit in (kindly please confirm it for me, if anyone has an open case), and I trust more its medical device and test instruments rated filter and the dual pole switch, if I've seen correctly the original switch only breaks one wire, and I have a feeling that I'll be busy inside as well and it's not impossible that I'll replace the original PS:

http://www.mouser.com/ds/2/355/FN%209264-1036108.pdf (http://www.mouser.com/ds/2/355/FN%209264-1036108.pdf) looking at the 1A version: FN 9264-xx-1-06-y

On the other side, I think I've really scared my distributor, because I've told them that if I got one with a bad firmware they will suffer a lot, and I think they wait for a new lot with updated firmware. Or of course they are just rectums.

Finally I'm thinking of replacing the back panel with a piece of nicely anodized aluminum, do you think it's a good idea ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 20, 2017, 05:44:42 am
Hey, look what I've found thid morning in my Inbox (chinglish spelling and grammar unaltered):

Quote
Dear customer,
Hope you rae doing fine.
Thank you for your question.
Okay. Sure. The item owns the latest 3.2 version.
Have great day
Best regards

So did anyone ever see this elusive 3.2 firmware version, should I go for it ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 20, 2017, 06:12:28 am
From the Factory on the 4th of November "The latest firmware of the instrument is version 4.2 ."

Also

"DC deviations can only be corrected by updating firmware. " which as per an earlier post of mine isn't quite correct. What I suspect they mean is we have a rough stab at the trimpots then correct it in software.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 20, 2017, 06:25:39 am
Really, this is actually from Feeltech  :wtf: ?!?!?

Bloody hell, as Lucifer said,  time to have a serious conversation with those guys :box:, thanks for sharing.

 So about the DC bias, it's actually stable but it has an offset against the programmed value that needs to be compensated in SW, or it drifts away while operating ?

 Thanks,
 DC1MC

From the Factory on the 4th of November "The latest firmware of the instrument is version 4.2 ."

Also

"DC deviations can only be corrected by updating firmware. " which as per an earlier post of mine isn't quite correct. What I suspect they mean is we have a rough stab at the trimpots then correct it in software.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 20, 2017, 06:34:00 am
Since I sorted the bias it has stayed close to what it was set at allowing for tempco etc.... Certainly a lot better than when I got it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 20, 2017, 06:44:50 am
Counter reply form the distributor:

"Hope you are doing fine.

Oh, sorry. The factory staff said the device embraces 3.2 firmware version, and it's the latest version at present.
Hope you could udnerstand that.

Have a great day
Best regards"
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 20, 2017, 07:07:19 am
Well someone is in error then  ::)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 20, 2017, 07:15:30 am
The plot thickens, I've send them the picture (and also made myself an inquiry to Feeltech), and reminding them about warranty law in Germany (they'll have to support the costs of updating), let's see what comes out of it.  Maybe dome price decrease  >:D.

 Thanks a lot,
 DC1MC

Well someone is in error then  ::)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on December 20, 2017, 08:15:55 am
Could be a simple typo. 3 vs 4 would make them both claim 3.2. I hope you are not under the impression a lot of effort and care went into that email.
I would find 3.2 more believable then 4.2, as everyone else in seemed to have gotten 2.9; 3.0; 3.1 devices

Of course, I would not recommend buying the device anyway. Not rewarding Feeltech until they do some actual warranty repairs rather then promising them.
Mine is still working, but every time I turn it on I worry.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jleg on December 20, 2017, 11:55:16 am
I'd also say this is a typo - 3.2 seems to be confirmed from various sides, and i never heard from a 4.x version...

Btw, Feeltech requested my seller's name/address, because they "will help me to handle it". What ever that means, it does not sound like "we'll send a new front panel"...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on December 20, 2017, 11:59:09 am
The plot thickens, I've send them the picture (and also made myself an inquiry to Feeltech), and reminding them about warranty law in Germany (they'll have to support the costs of updating), let's see what comes out of it.  Maybe dome price decrease  >:D.

 Thanks a lot,
 DC1MC
Why would Feeltech be bound to German warranty laws?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on December 20, 2017, 12:20:04 pm
Hello,

Have customs taxes been paid ?

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: khach on December 20, 2017, 12:55:48 pm
I that any hardware difference between 60MHz,50 MHz, 30 MHz and 15 MHz version of  FY6600? Is low frequency version upgradable by hack  to  high frequency version?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 20, 2017, 08:08:52 pm

Why would Feeltech be bound to German warranty laws?
[/quote]

Feeltech couldn't give a rat behind about German warranty laws, the seller of the device on the other side does, because it sells this stuff form inside Germany, with VAT and invoice.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 20, 2017, 08:10:40 pm
Most certain is a typo, but I wanted to have them admit that they will support the upgrade expenses if it's not the right version (I have doubts that is even 3.2), we'll see.

Could be a simple typo. 3 vs 4 would make them both claim 3.2. I hope you are not under the impression a lot of effort and care went into that email.
I would find 3.2 more believable then 4.2, as everyone else in seemed to have gotten 2.9; 3.0; 3.1 devices

Of course, I would not recommend buying the device anyway. Not rewarding Feeltech until they do some actual warranty repairs rather then promising them.
Mine is still working, but every time I turn it on I worry.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 20, 2017, 08:13:04 pm
I that any hardware difference between 60MHz,50 MHz, 30 MHz and 15 MHz version of  FY6600? Is low frequency version upgradable by hack  to  high frequency version?

Could be, but now the price difference is that small that it's not worth the effort to lose the warranty (the firmware isn't fully stable yet) and hack it for ca. 18-20EUR gain.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 20, 2017, 08:14:12 pm
Huh ?!?! What are trying to say here ?


Hello,

Have customs taxes been paid ?

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on December 26, 2017, 05:46:48 pm
Hi!

Has anybody tried modernising their FY6600 with one of these:–

https://m.ebay.co.uk/itm/New-Multi-channel-Linear-DC-Power-Supply-Module-3-3V-5V-12V-Adjustable-Output/262612931341?hash=item3d24f3530d:g:ZgYAAOSw8oFXz3Vu

Are they capable of supplying the necessary power requirements of the unit? I'm thinking of replacing the cheap and horrible SMPSU with one of these linear modules with the advantage of transformer isolation!

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on December 26, 2017, 05:50:06 pm
Hi!

Has anybody tried modernising their FY6600 with one of these:–

https://m.ebay.co.uk/itm/New-Multi-channel-Linear-DC-Power-Supply-Module-3-3V-5V-12V-Adjustable-Output/262612931341?hash=item3d24f3530d:g:ZgYAAOSw8oFXz3Vu

Are they capable of supplying the necessary power requirements of the unit? I'm thinking of replacing the cheap and horrible SMPSU with one of these linear modules with the advantage of transformer isolation!

Chris Williams
I think you'd have to ask yourself whether you really want to hook up an unmarked and unknown Chinese power supply to mains.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on December 26, 2017, 07:12:04 pm
Hello,

This power supply will do the job by adding an internal transformer, or external power supply.
- https://www.banggood.com/fr/DIY-USB-Boost-Single-Turn-Dual-Power-Module-Linear-Regulators-Multiple-Output-Power-Kit-p-1022517.html?rmmds=myorder&cur_warehouse=UK (https://www.banggood.com/fr/DIY-USB-Boost-Single-Turn-Dual-Power-Module-Linear-Regulators-Multiple-Output-Power-Kit-p-1022517.html?rmmds=myorder&cur_warehouse=UK)
- https://fr.aliexpress.com/item/New-Arrival-DIY-Power-Supply-Module-USB-Boost-Single-Turn-Dual-Linear-Regulated-Power-Kit-Regulator/32695921692.html?spm=a2g0w.10010108.1000014.24.32b7a9aOyqOWH&traffic_analysisId=recommend_3035_null_null_null&scm=1007.13338.80878.000000000000000&pvid=506d4eea-89c5-4977-9f9d-77e306085a91&tpp=1 (https://fr.aliexpress.com/item/New-Arrival-DIY-Power-Supply-Module-USB-Boost-Single-Turn-Dual-Linear-Regulated-Power-Kit-Regulator/32695921692.html?spm=a2g0w.10010108.1000014.24.32b7a9aOyqOWH&traffic_analysisId=recommend_3035_null_null_null&scm=1007.13338.80878.000000000000000&pvid=506d4eea-89c5-4977-9f9d-77e306085a91&tpp=1)

(http://img15.hostingpics.net/thumbs/mini_871590Alimentationsymtrique.jpg) (http://www.hostingpics.net/viewer.php?id=871590Alimentationsymtrique.jpg)


Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on December 26, 2017, 09:15:25 pm
Hi!

Quote
https://www.banggood.com/fr/DIY-USB-Boost-Single-Turn-Dual-Power-Module-Linear-Regulators-Multiple-Output-Power-Kit-p-1022517.html?rmmds=myorder&cur_warehouse=UK/quote]

I'd certainly go with one of these (bought in kit form so I can document the schematic & parts list of course!!!) and have been thinking about one – I've got an RS 78xx PCB floating about to fit rectifiers & smoothing capacitors to!

Does anyone know the approximate current consumption of the FY6600 (per rail) driving 10V p–p square @ 1 MHz into 50 ohms ?

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 26, 2017, 10:42:47 pm
Hi!

Has anybody tried modernising their FY6600 with one of these:–

https://m.ebay.co.uk/itm/New-Multi-channel-Linear-DC-Power-Supply-Module-3-3V-5V-12V-Adjustable-Output/262612931341?hash=item3d24f3530d:g:ZgYAAOSw8oFXz3Vu

Are they capable of supplying the necessary power requirements of the unit? I'm thinking of replacing the cheap and horrible SMPSU with one of these linear modules with the advantage of transformer isolation!

Chris Williams

Hi Chris, the idea of using an analog power supply it's excellent, I'll do it my self as one of the last steps of modding the FY into a better instrument, the mains isolation and lack of SMPS noise it's a great thing to have if the transformer and caps are fitting in the box. But the posted power supply looks really bad, the 12V AC secondary and the 2 anemic filtering caps will not produce such a good power.
UPS finally send my tracking number and in max two days mine will reach me, I'll do the power measurements but there is no way this PS will sustain 10Vp-p on a 50ohm load, IMHO.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 27, 2017, 10:12:39 am
In preparation to the big communication protocol reversing, before my device and LA arrives, I have a request for the people who can still open their FY and do some measurements:

 - By looking at the posted pictures and videos, it seem that the flat cable caries 2 things:
 
- 1 Serial Interface that goes to the signal board serial to USB connector.
- And the 8 (?!?!) bit parallel (?!?!) bus for configuring the the generator.

I have the following questions:
- The parallel bus has really just 8 wires, I may have miscounted looking at the pictures ?
- Has anyone put an oscilloscope on this bus, has the communication been identified or at least if there's some clock, R/-W pin and similar,  is the bus bidirectional or there are separate Is and Os ?

Also one administrative question: should we keep one of the current threads alive with this project (either this one or the one with the firmware flashing) or should I create a new thread ?

I soo much wish that the UPS guys will move a bit faster  :scared:

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 27, 2017, 01:42:15 pm
 I located a clock and events when I pressed buttons  The ribbon has 12 wires, four of which appear to be for the RS232 connection. IIRC I only observed data on 3 lines + the clock.  That suggests that every other line is ground.

I did not have a reliable connection to the bus, so I stopped until I have time to put an attachment for probing together.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 27, 2017, 01:52:46 pm
I located a clock and events when I pressed buttons  The ribbon has 12 wires, four of which appear to be for the RS232 connection. IIRC I only observed data on 3 lines + the clock.  That suggests that every other line is ground.

I did not have a reliable connection to the bus, so I stopped until I have time to put an attachment for probing together.

Cool, now it's the time for Captain LA to save the day  :box: !!!

Before I'm engaging in more (possible destructive) testing on the FP firmware I want to fully decode the protocol, especially if there are calibration constants stored in the FP firmware.
Once this is done, then there is no stress if the firmware goes puff, I was thinking anyways to move the signal board in an re-purposed scope box that has an encoder on FP and enough buttons.
Also, once the programming of the signal board it's fully reversed, a better LCD control unit can be connected, eventually a repurposed tabled with touch screen.

I'm biting my fingernails waiting for the boxes wit the FY and an LA, let's see what UPS is doing.

 



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 27, 2017, 02:13:12 pm
If you have the connector parts make yourself a 1x8 jumper cable with probe points.  I just got the connectors a couple of days ago, but I'm cleaning and reorganizing my work space (and I've got a remodeling project I need to get back to work on).  I just got my MSO-2204EA a month or so ago and am still in the process of tooling up to use it. The last time I did this everything was through hole DIPs, but those probe clips aren't much help with SMD parts.

You *might* be able to separate the factory cable wires and attach probes, but there's not a lot of slack.  I stuck the probe leads down into the back of the generator board connector but that was not a very secure connection.  I got a kit of "dupont" cable connectors from eBay and will make up a complete set of 1xN M-F probing jumpers some evening soon.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on December 27, 2017, 05:22:55 pm
I located a clock and events when I pressed buttons  The ribbon has 12 wires, four of which appear to be for the RS232 connection. IIRC I only observed data on 3 lines + the clock.  That suggests that every other line is ground.

I did not have a reliable connection to the bus, so I stopped until I have time to put an attachment for probing together.
What works well for me when probing many signals is a dual row header with enamel wires attached to it. One row are for signals, the other row is for ground. I solder the enamel wires to the board because clips let go way too easely.
(https://farm5.staticflickr.com/4690/38627635874_d6d5695767_z.jpg) (https://flic.kr/p/21RoJnY)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 27, 2017, 06:25:47 pm
Certainly the way to go if you need to connect to a PCB.  Sadly, to be useful with an MSO-2204EA I'll have to repackage the LA probes to use a 2x8 header.  I've planned to do that, but have other mischief I want to do first.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 27, 2017, 07:11:50 pm
Well, now we have to get Cybermaus, and the other guys that suffered, on board. Time to spend some calories on something more advanced than replacing capacitors.
On connecting side, I have a crimping female FRC connector, if by chance the cable fits than that's it, if not I will pierce the isolation with some needles, if somebody know if there are some "vampire" grippers for small wires, now it will be a good chance to tell about them, and better be available in EU or I'll pester the US guys here to send me some in an envelope ;).

Three signals plus clock, I'm wondering what kind of contraption is there, could it be two synchronous independent channels, I 'm really wondering if the communication is bidirectional and how it's implemented.
Finally something interesting to play with, I so much wish to get on board someone with one of this advanced LAs, with a gadzillion protocol decoders.

Oh well, not much to do until the stuff arrives, I'll keep on eye here and read something more about the STM32.

I've still didn't hear the thread option, should we stay on this thread when the work starts or should I create a new thread specialized for this project ?
Here's a picture of my cat looking forward to participate on the project as a source of entropy  >:D.


 Cheers, DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 27, 2017, 08:59:30 pm
For the STM32 experiments bought myself a pair of these (one will become a controlled SWI debugger to test some of the Fraunhoffer guys experiments) :

https://www.ebay.de/itm/282786310657 (https://www.ebay.de/itm/282786310657)

Anybody has a recommendation for a non-castrated C development environment, based on GCC if possible ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 28, 2017, 12:30:15 am
The STM32F429 Discovery kit includes a 320x240 touch screen for $24 US the last time I checked.  At any rate, the chips are so good, you can't have too many.

ST offers a full dev kit and there is the gcc toolchain, so everything you need several times over.  You might want to look into Matthias Koch's Mecrisp which is an approximately ANS forth of superb quality.

ST provides a large suite of examples and libraries for their devices.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 28, 2017, 12:34:31 am
I've bought the little boards not because there weren't any other more interesting or more capable, but because I needed something that has the same chip variant as the FP MCU of the FY.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: texaspyro on December 28, 2017, 01:30:44 am
Or instead of keeping with the ARM, maybe a Arduino 2560 or other Atmel CPU.   That way there is no arguing about copyright issues.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on December 28, 2017, 06:56:56 am
I've bought one of these units and have done some quick tests and it seems I have some wierd DC offsets in the waveforms above an amplitude of 0.5Vpp (as set on the instrument itself):

https://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-another-one-really.html (https://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-another-one-really.html)

Anyone else seeing this?

I've managed to "break" the software a few times and needed a power off-on to get it going again. There is certainly a firmware bug around 0.5V amplitude where a relay goes clunk inside the box; sometimes sometimes that step from below to above 0.5V can be huge even when the adjustment in amplitude made is in the decimal points of the value.

And for sure the manual states that the outputs are 50 ohm but the amplitude setting and the measurements at 50 ohm have little or no resemblance to each other.

Anyone else seeing the same thing?

Mark
G0MGX
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 28, 2017, 08:53:33 am
Hi Mark, what is the firmware version of your unit ?
There were other reports of strange DC offset, but FeelTech claims that this is fixed in fw. version 3.2

The calibration constants and all the necessary math are (allegedly) stored and done in the Front Panel little MCU, and the firmware there has lots of bugs, it could be that the MCU they've chosen doesn't have enough resources.
 
I hope you can participate in the effort to reverse and understand the communication protocol between the front panel and the signal board.
The signal board is reported reasonable good as-is, and can be made better with inexpensive modifications.
My unit it's finally "in delivery" and will reach me today, so I will contribute also reports.
Also when my LA will reach me, I will start working on the communication protocol, but I need other owners to look on the bus so we can compare results.

  73 de DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on December 28, 2017, 11:33:51 am
Hi!

I have just gone through the whole thread. Interesting device this is.

Can somebody please enlighten me how the output amplitude control is done in this device?

Thx, Y.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 28, 2017, 12:20:17 pm
My FY6600 arrived, the piece of excrement Chinese distributor send one with firmware 3.1, solidifying my opinion that they are scum of the Earth.  |O :palm:
Of course after confirming in their crappy Chinglish that their devices have 3.2, you've seen the exchange somewhere else in the thread where that was a question about a version 4.2.

I'm asking for your opinion, what should I do, should I send it back as is or should I start working on it.

I don't care about their firmware shit, but I needed one with a (semi)decent fw. to not get their stupid mistakes in configuring the generator, decoding and extracting the firmware it's a lot of work and I don't want to do it twice. and this seem to be the firmware that does not fuck the display but has some numerical errors in setting the DC offset and signal level, exactly the stuff I wanted to have.


Is there somebody with a version 3.2 and a Logic Analyzer willing to reproduce my steps here to decode the protocol (nothing will be done on the firmware extraction until the protocol it's fully understood, so it should be relatively safe) and compare the results ?
Please let me know about your opinion.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 28, 2017, 12:30:30 pm
Hi!

I have just gone through the whole thread. Interesting device this is.

Can somebody please enlighten me how the output amplitude control is done in this device?

Thx, Y.

I was planning to do a schematic capture today, while replacing the crapacitors, not sure if I'll do it or I'll be waiting for the one with the 3.2 firmware.

Anyway, a schematic will be done.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on December 28, 2017, 12:37:35 pm
OK thanks.  I have noticed the DAC904 has an external VREF input and someone have noticed there are some Microchip DACs like MCP4821 or what. I think they obviously use these to set the VREF of the DAC904, which makes sense.

(In the neighbouring thread about the JDS6600 generator, they use a 4quadrant multiplier to do it and I was curious abotu the solution in the FY6600.)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: kahe40 on December 28, 2017, 02:21:28 pm

a firmware bug around 0.5V amplitude where a relay goes clunk inside the box ...


no problem at all with v3.1     (push SYS, maybe you have v3.0)

< 1mV it is not really perfect, e.g. 200uV positive and 400uV negative sinus,
but from 1mV upwards everything is perfect



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on December 28, 2017, 02:55:51 pm
My firmware is V3.2 (thats what is reported on boot and in the SYS screen).

There are quite a few issues with the software all of which seem to be fixed by a mains cycle.

Another issue I have found with my unit is that **sometimes** if you power it off with a 0.5V amplitude using the soft power switch on the front, when you switch it back on again there is no output until you increase or decrease the amplitude; it then works fine at the 0.5V setting.

I wonder if I have a sticky relay or two?

I need to read through the whole thread - but it's very long now - happy to get involved in the decoding of comms.

Mark
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 28, 2017, 03:02:52 pm
I had proposed an instrument wiki so that we could organize such things more easily.  I'd love to be able to read a summary of the $20 LCR thread, but at 170+ pages it's just too long.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on December 28, 2017, 04:19:54 pm
I've now read the entire thread and have taken the PSU board out of mine to take a look at the caps.

The 10uF 450V cap in mine has only one leg soldered to the PCB, so I don't think that will have been helping much  :palm:

I've already changed the mains socket for 3 pin type and connected the mains earth to the 0V line; saves doing this with my PC and a USB cable instead. I'll change all the caps in the output for 25V types and see what happens.

Mark

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 28, 2017, 06:20:51 pm
You may want to reinforce the panel.  Your mount is like mine and when I pushed a cord on, it deflected too much to be comfortable. So I took it apart and added a metal brace scured by hot melt glue to the bottom of the case.  The socket screws thread into the metal which was cut from on old PS case.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 28, 2017, 07:40:06 pm
Hi, these are the latest news, my fw. is indeed 3.1, I've contacted the seller that hasn't responded yet and "suddenly" all the available 60MHz units are not available anymore, just some 30MHz.
I was able to read the CD, it seem to be some software for more models and due to some family obligations I wasn't able to do more.
I seem that my LA will be delayed to the next year as well :'(, so I have to use my 4 channels Tek to try to get some data out of the bus, if I don't send the device back. Really, I wish that seller and his company to have 4 as a number for 10 years and  live trough the most interesting of times.
I'm so happy that there is someone with a 3.2 software willing to sniff the bus as well, I will try to hook the scope tomorrow and see what is coming out.
And Feeltech, I know that you're monitoring the thread, do try to get some (half)honest distributors, you will lose face and crash your momentum, you've managed to anger a large part of your customer base.
See you tomorrow, DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 29, 2017, 12:11:24 am
My last communication from FeelTech :-(

--------------------------------------------------------------------------------------------------------
Re:FY-6600 V3.0 FW problem
Thursday, December 21, 2017 3:51 AM

From:
    "????" <admin@feeltech.net>
To:
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx

We will deal with it as soon as possible to keep you waiting

---------------------------------------------------------------------------------

No response at all from the seller since this:

---------------------------------------------------------------------------------------------------------------
Friday, December 8, 2017 11:40 PM

From:
    "eBay - sportgogo" <sportg_gx3808oho@members.ebay.com.hk>
To:
   xxxxxxxxxxxxxxxxxxxxxxxxxxxx

sorry for this,we will check with supplier,please don't worry.
best regards,
 
---------------------------------------------------------------------------------------------------


Needless to say, I am not happy.  It is very hard to believe there is a good faith effort being made.  In fact, I don't believe *any* effort is being made.  So I think complaints to eBay and PayPal are in order.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: armrisc on December 29, 2017, 02:25:09 am
Hi guys! My firsts post here. I'l read about this generator for a while and i started to realy like it. Expecially external trigger is realy usefull for my uses(in contrast to JDS6600) At the start i was looking at the Rigol DG1022, but for a hobbyist - price is to high for my liking, so Fy6600 is like a superb new year gift for mysefl. :)
The reason I registered is regarding firmware - mainly problems with it - display corruption, not possible to reflash it localy etc. What concerns me the most is why this corruption ocurrs? You can avoid problems if you know reasons, but at this point it's a black hole.
I read through all posts, maybe missed it. As far as my understanding goes it only can be related with waveform upload, this is the only time write to chip is happening?, or is it memory overflow,bug  issues and with time you will be hit by corruption anyway? Returning device to manufacturer for me is is a no-go, I can by a new item for the same cost. Any ideas anybody?
Thanks in advance.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 29, 2017, 02:57:26 am
I modified mine to add a grounded power cord as my scope showed 176 Vpp from the BNC to earth ground.  I closed it up and it sat on the bench hooked up to a scope and a frequency counter for a couple of hours.  Everything was fine.  I shutdown the lab bench and went to bed.  The next day I powered it up to do some more experiments.  Display was borked.  It mostly works, but several waveforms stopped working entirely.  At power up it sets very strange values which *are* the correct values for the output.  My screen looks exactly like the photos in the first post of the reflashing thread.  Another owner tried to reset to factory defaults.  That made the unit completely non-functional.

I never got as far as trying to load a waveform.  The consistency of the failures of the V 3.0 devices indicates it's a serious software error.  It is known that 3.1 has problems and there is a growing suspicion that 3.2 also has a problem, though the extent of issues with 3.2 is not yet well known.

My post earlier today should give you a pretty good idea of the current support situation.  You *really* don't want one of these until FeelTech provides replacement front panels to affected owners.  Unless, of course, you're looking for a repair and hacking project.  Those of us with borked units would love help figuring out how to fix them.

These are *not* getting borked by the users doing something wrong.  They are failing because there is a FW error which FeelTech knows about.  They have updated the FW twice, but have not provided any fix for units in the field.  Lots of promises, but no action.  Returning a failed unit to China will cost $30 from the US.  There is no guarantee you'll get *anything* back.  So returning it is just throwing good money after bad.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 29, 2017, 03:30:16 am
As I have mentioned before in this thread and given the numbers of firmware failures of these time for Feeltech to come up with a method of user upgrading.

Continual placing of their heads in the sand over this will see a severe decline in sales as any quick Google check of their product will get you here!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on December 29, 2017, 04:56:15 am
Hi!

I've just been advised by Royal Mail that delivery of my unit is expected by 9 Jan – I've no problems with that as I ordered mine for delivery to my work address and I'm not back on duty till Tuesday the 2nd!

Funny the 60 MHz units all seem to be suddenly "out of stock" or "unavailable" tho' – this does make me wonder if the maximum sine frequency is both a hardware and a firmware change!

(I can't afford to buy a unit of each frequency–spec. to see what the differences are!)

Regrettably I've little or no experience on extracting communication protocols, having never had reason to need to do it, but I will do what I am experienced at, namely providing a set of full schematic diagrams!

I do have one question tho' – are the "waveform graphics" shown on the front display/U.I. actually drawn/calculated from whatever is sent to the DAC controls, or are they a simple graphic plot worked out from a library function table, etc?

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on December 29, 2017, 06:39:10 am
I do have one question tho' – are the "waveform graphics" shown on the front display/U.I. actually drawn/calculated from whatever is sent to the DAC controls, or are they a simple graphic plot worked out from a library function table, etc?

The graphic on the screen changes with waveform and if applicable Duty, no changes with amplitude, offset of phase. Both Ch1 and Ch2 waveform types appear regardless of the on/off status of the channels.

Mark
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on December 29, 2017, 07:08:21 am
I am rapidly concluding that the bug list in this device is way longer that any of us realise.

This morning I have tried two identical signals 90 degrees out of phase; they measured about 83 degrees apart. Then a quick power on off corrects this issue but now the channel 2 signal has the weird DC offset I reported previously on Ch1  but Ch1 is centered around 0V correctly. With both channels the same (using the "Sync" feature) at 10MHz and an amplitude of 0.5V, a soft power off guarantees neither channel will start on power on until you alter the amplitude of each one away from 0.5V.

(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/outofphase.png)

(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/2chsync.png)

(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/2chsync%20II.png)

(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/DSCF4050-Optimized.JPG)

(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/DSCF4051-Optimized.JPG)

I'm rapidly drawing conclusions on this unit, especially around the amplitude setting of 0.5V where **something** weird seems guaranteed every time  |O

Mark
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CustomEngineerer on December 29, 2017, 07:29:07 am
Continual placing of their heads in the sand over this will see a severe decline in sales as any quick Google check of their product will get you here!

I'll believe it when I see it. These units have had major issues since day 1 (that feeltech still hasn't addressed), but people continue to buy them anyways.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on December 29, 2017, 08:03:19 am
Just to be sure, but did you properly terminate the cables? Weird phase shifts can be sometimes seen in unterminated cables, though I'm not sure the frequency is high enough for that.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on December 29, 2017, 08:49:15 am
Continual placing of their heads in the sand over this will see a severe decline in sales as any quick Google check of their product will get you here!

I'll believe it when I see it. These units have had major issues since day 1 (that feeltech still hasn't addressed), but people continue to buy them anyways.

It is a shame as the built in feature set with a few on going hardware improvements from there end would see market dominance in this lower priced Sig Gen market. Open Source the software/firmware and remain the hardware provider and take advantage of a user base modding and tweaking would be a win win for them.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on December 29, 2017, 08:56:06 am


Just to be sure, but did you properly terminate the cables?
Yes, the 'scope is 50R terminated in both channels.

I've created a video of my issues (well only some of them)

https://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-issues-list.html (https://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-issues-list.html)

I can't help thinking that what I am seeing is a combination of firmware and possible some crappy relays sticking.

Anyone with the same unit, can you reproduce what I show on the video?

To confirm the firmware in my unit is 3.2.

Mark
G0MGX
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 29, 2017, 09:16:16 am
Hi, just some replies on topics, in no specific order, of course everything is IMO and IMMV:

- The people still buy it because for the price is by far the best option of a signal and AWF generator, the signal board is decent but controlling part is crap, they've chosen a way too weak MCU that does way too much. And the original, non-copied Chinese software still has a lot to catch, the hardware production was outsourced in China, not the software (that was outsourced in India).

- The distributors and FeelTech are in between a rock and a hard place, even with Asian production costs and sponsored shipping to EU/US, I believe the margins are not too big. And shipping from EU/US to China is NOT sponsored, to every repaired unit will bring them a net loss. Not to mention that the firmware is way too unstable and more than one trip will be needed, even if they will release the firmware, the unit needs serious modifications to even be capable of upgrade, it still could be possible that there is some way to do it over the exposed serial interface and FeelTech are just a-holes not willing to release the firmware.

In the end they will probably design another unit, a bit better and leave the ones who bought the FY6600 hanging dry. So the effort to reverse and open source the protocol/fw may or may not succeed, who wants official vendor support for this model is probably out of luck and should try to return them while still possible.Who decides to keep the unit, either because it likes it or it does modifications that voids the warranty should better start hooking the logic analyzers and draw schematics, I'll do it, because I've promised to do it and I see some value in the signal board.

DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 29, 2017, 09:18:20 am


Just to be sure, but did you properly terminate the cables?
Yes, the 'scope is 50R terminated in both channels.

I've created a video of my issues (well only some of them)

https://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-issues-list.html (https://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-issues-list.html)

I can't help thinking that what I am seeing is a combination of firmware and possible some crappy relays sticking.

Anyone with the same unit, can you reproduce what I show on the video?

To confirm the firmware in my unit is 3.2.

Mark
G0MGX

Hi Mark, I don't believe in the sticky relay thing, I believe that most likely when they try to restore the state after stand-by, they just forget to restore thing properly in the signal board, IMO it's 100% a firmware issue.

 Cheers,
 DC1MC
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 29, 2017, 09:23:07 am
Continual placing of their heads in the sand over this will see a severe decline in sales as any quick Google check of their product will get you here!

I'll believe it when I see it. These units have had major issues since day 1 (that feeltech still hasn't addressed), but people continue to buy them anyways.

It is a shame as the built in feature set with a few on going hardware improvements from there end would see market dominance in this lower priced Sig Gen market. Open Source the software/firmware and remain the hardware provider and take advantage of a user base modding and tweaking would be a win win for them.

The one that will convince a Chinese company to open-source and deobfuscate the specs of one of their (good selling) products will be remembered for ever as a hero and saint, it's so opposed to their culture that it's almost impossible, the specifications, protocols and everything must be reversed and extracted with great pain if someone wants them.

On the other side, profiting form OSS and public knowledge and not giving anything back, hell yeah, that makes good business sense, "they are giving this sh..t for free, let's use it..."
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on December 29, 2017, 11:15:24 am
they've chosen a way too weak MCU that does way too much.

Any proof of that statement? I think that this is only empty screaming around.  72MHz Cortex M3 is pretty adequate to control a decent DDS generator.

The MCU does zero to nothing, apart from reading buttons and playing with the LCD. This is simply a issue of crap FW, not weak MCU.

All the interesting magic happens inside the FPGA. The MCU just commands it with the frequency and other such settings.

Reverse engineering the schematic would be awesome. However, is reverse engineering of the FPGA-to-MCU protocol necessary? Wouldn't it be easier to make the whole FPGA content new? I can not help much with that, as I have less than little experience in VHDL (and only using small CPLDs), can only offer quite some expertise on STM32.
My idea about the FPGA does tell me, there really should not be that much in there.

But considering the amount of work required for this, wouldn't it be better to even redesign the PCB? I see a lot of room for some marginal improvments, right?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 29, 2017, 11:28:40 am
One step at a time, in order of difficulty:

 1x - Capturing the schematics, to see with what we're actually dealing.
 3x - Decoding the communication protocol and capabilities of the existing signal board / firmware.
 9x - Redoing the STM32 firmware in a proper way.
27x - Exploring and fully understanding the possibilities and limitations of the current signal board design, including the firmware.
81x - Redesigning and producing an improved FPGA firmware.
243x - Redesigning and producing another signal board with better features and performance

These are my very conservative and optimistic estimates of the difficulty multiplication factor of the tasks ahead.
One has only to provide the number of hours needed for capturing the schematics.

So, let's try to get the schematics of the existing unit to get the unit of effort (UE) in work hours for the project.

 Cheers,
 DC1MC
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: kahe40 on December 29, 2017, 12:40:30 pm

Anyone with the same unit, can you reproduce what I show on the video?


no such a behavior here with 30MHz model and v3.1 with Ser# 893 783 770
and a quick test (family is demanding), but You say in Your blog :

>> ... amplitude setting of 2.0V (the manual says this is "default"
>>  peak to peak - I have found no way to change this "default" setting).

try   SYS/MORE/factory default:OFF
and save several presets in SYS/SAVE/S01 S02 ...

those are my conditions, FactoryOFF
and several saved Sets, from which I start working.
Maybe in your fresh unit something is not initialized ?
Or new bugs in v3.2 ?

edit Ser#
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on December 29, 2017, 12:52:21 pm
One step at a time, in order of difficulty:

 1x - Capturing the schematics, to see with what we're actually dealing.
 3x - Decoding the communication protocol and capabilities of the existing signal board / firmware.
 9x - Redoing the STM32 firmware in a proper way.
27x - Exploring and fully understanding the possibilities and limitations of the current signal board design, including the firmware.
81x - Redesigning and producing an improved FPGA firmware.
243x - Redesigning and producing another signal board with better features and performance

These are my very conservative and optimistic estimates of the difficulty multiplication factor of the tasks ahead.
One has only to provide the number of hours needed for capturing the schematics.

So, let's try to get the schematics of the existing unit to get the unit of effort (UE) in work hours for the project.

 Cheers,
 DC1MC

Well I am aware of that this is a time consuming black hole, but I'd like to point that you should probably have some coefficients even bigger. Guessing you can do the schematic within a few hours, but you won't rewrite the STM32 firmware in just 10 hours. Maybe 50 hours, likely more. Well... lets keep us being optimistic :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 29, 2017, 05:13:44 pm
I would say a proper schematic capture will take at least 10 hours, rewriting the STM firmware after one has the full schematic and protocol to be implemented fully specified, it's realistic to have it in beta after 90 hours.

 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on December 29, 2017, 07:48:07 pm
Hi!

Quote
I would say a proper schematic capture will take at least 10 hours, rewriting the STM firmware after one has the full schematic and protocol to be implemented fully specified, it's realistic to have it in beta after 90 hours.

I think that's a reasonable, possibly even conservative, estimate of the time needed to produce a good set of Schematic Diagrams!

I admit, as I said in a previous post, that I'm not skilled in reversing firmware or communication protocols in a given piece of unknown equipment, but I can use Member DC1MC's estimate of how long the drawing–out will take as a guide and compare how long I take with the ten hours estimated!

(I think it wouldn't be a wasted effort for more than one of us to work on the schematics as with a densly–populated analogue/digital surface–mount PCB like this it's so easy to get it wrong somewhere, which would affect the FW reversal!)

My suggestion for new firmware would be:–

1) Find out what type of LCD driver is needed for the original display and design a good U.I  (No horrible Chinese Lettering!) – Our Continental Friends may be able to assist with translations for additional languages if needed;

2) Find out how many functions need to be sent back to the main PCB for control of the Altera Cyclone;

(Waveform type selection, amplitude, frequency, phase, DC offset etc., per channel, plus one function for each Arbitrary Waveform provided – it may be possible to use the PC software provided by FeelTech to get the waveform–function for each Arbitrary Waveform provided;

3) Decide on implementation of the additional control functions – AM/FM Mod, VCF, Sync, etc;

4) Consider wether a Frequency Counter Function is needed;

5) Finally, the "housekeeping" functions – factory reset, Cal/setup, self–test, firmware-update, etc;

I certainly agree it's not trivial but I thought if I set out a rough draft of the firmware functions first it'll assist those excellent chaps on here who are much more "au–fait" with software/firmware engineering than I am!

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on December 29, 2017, 08:48:26 pm
If someone can read out the firmware finding the buffer overflow (or they might be slamming the flash with way too many writes I guess) shouldn't be that hard if they have IDA ... it happens frequently enough that it shouldn't take too long just triggering on memory access. Binary patch it and throw it on the internet.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 29, 2017, 09:36:33 pm
If someone can read out the firmware finding the buffer overflow (or they might be slamming the flash with way too many writes I guess) shouldn't be that hard if they have IDA ... it happens frequently enough that it shouldn't take too long just triggering on memory access. Binary patch it and throw it on the internet.

Uhmm, so which firmware version exactly are you talking about, all seem to be buggy ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 29, 2017, 11:53:53 pm
Based on my bus probing, there is a pretty simple command protocol.  The UI shows the user what the current parameters are and transmits the changes. At boot time it sends the boot time settings to the AWG.  Other than an ACK/NACK, there is no reason in AWG mode for any traffic from the AWG board to the UI board.

So IMHO, the first step is to figure out what the UI sends to the AWG when you change a setting.  Forget the counter function until the AWG works.  That's the part that's valuable.  You can buy a much more capable counter on eBay for $12-15.


As for reading the FW, read the Fraunhofer paper, implement it and get back to us with the FW dump. We'll be happy to take it from there.

I've had to fix a few million lines of other people's code.  At a certain point, it is easier and quicker to simply consider the problem and write the code from scratch.  I think that is true in this case.  Using the device as an AWG only requires sorting out the command set.  I'll gladly write code to control the AWG via RS-232.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on December 30, 2017, 12:09:14 am
Uhmm, so which firmware version exactly are you talking about, all seem to be buggy ?

The most severe bug, ie. the fact it trashes the program storage, shouldn't be too hard to track down with a disassembler (IDA) and debugging once you have ripped the firmware. Then you can patch it at assembly or even machine code level.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 30, 2017, 12:10:19 am
Based on my bus probing, there is a pretty simple command protocol.  The UI shows the user what the current parameters are and transmits the changes. At boot time it sends the boot time settings to the AWG.  Other than an ACK/NACK, there is no reason in AWG mode for any traffic from the AWG board to the UI board.

So IMHO, the first step is to figure out what the UI sends to the AWG when you change a setting.  Forget the counter function until the AWG works.  That's the part that's valuable.  You can buy a much more capable counter on eBay for $12-15.


As for reading the FW, read the Fraunhofer paper, implement it and get back to us with the FW dump. We'll be happy to take it from there.

I've had to fix a few million lines of other people's code.  At a certain point, it is easier and quicker to simply consider the problem and write the code from scratch.  I think that is true in this case.  Using the device as an AWG only requires sorting out the command set.  I'll gladly write code to control the AWG via RS-232.

The more I look into this stuff, the more I believe that rewriting the firmware is the best way to do it, the Fraunhofer method it's a PITA and reversing the screwed up crap in their firmware it will be most likely useless and a waste of time. I've seen that STM offers a lot of libraries for everything from serial and LCD driving to graphical and mathematical routines and I doubt that our Chinese friends used something else, new and original. And if they did, it's the buggy part. Not to mention that in this situation nobody can claim or hinder us with DMCA and copyright shite.

Now on the actual work, Rhb, could you kindly share your actual findings, which one is the clock line, what freq it used, are there direction switching signals and R/W selector or anything of importance of your findings. I will try to hook tomorrow my scope, the LA it's still on its way to me.  I should at least see how the bus it's structured physically and if I'm extremely lucky the protocol used. Hopefully more forum members will use their powerful test gear and lend a hand.

See you tomorrow,
DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 30, 2017, 01:12:03 am
I did very little.  I hooked up the MSO LA lines and rotated the knob.  I'd never used the LA function before, so it was mostly an instrument training session.  I'm afraid I lost my notes in the process of reorganizing my workspace.  The clock was quite slow, KHz IIRC.  My biggest problem was sorting out the MSO UI.

IIRC 0 at one side was the clock and  4, 5 & 6 or 3 were signal lines. 

I was not very happy with the LA function.  So I suggest setting single shot mode on as many lines as possible, pressing all the buttons and turning the knob.  then go to the next set of lines and repeat in a systematic fashion.

I'm jammed up the next two weeks, but will be able to work on this after that. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on December 31, 2017, 09:27:24 pm
Hi!

Quote
The more I look into this stuff, the more I believe that rewriting the firmware is the best way to do it, the Fraunhofer method it's a PITA and reversing the screwed up crap in their firmware it will be most likely useless and a waste of time. I've seen that STM offers a lot of libraries for everything from serial and LCD driving to graphical and mathematical routines and I doubt that our Chinese friends used something else, new and original. And if they did, it's the buggy part. Not to mention that in this situation nobody can claim or hinder us with DMCA and copyright shite.

I couldn't agree more!

A quick question tho' - are there standard code libraries available to enable a (reasonably nice!) text/graphical interface to be designed with choice of coloured selections for settings, functions, and a good font, such as Helvetica, Gill Sans or Frutiger? (the one the UK NHS uses for Hospital internal signage!)

(I realise Gill Sans isn't commonly found on T & M Equipment, but it does have the advantage of being clear and easy to read on graphic LCD modules!)

Better still, are there programs available that allow a U.I. to be designed by graphical means on a PC that compile source-code from this, or am I looking at a mega-costly un-affordable solution for this aspect of the firmware?

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on December 31, 2017, 09:29:28 pm
STemWin. But... you better make your own library, before you adapt that bastard for a custom LCD.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 31, 2017, 09:54:43 pm
Some initial bus sniffing of the communication, VERY preliminary results:

Control connector, 8 pins, FS1

 1 - PA0 = Some kind of -POWER_GOOD, is connected to a transistor on SP with the base at 3.3V

 2 - GND

 3 - PA1 = Not found yet

 4 - PB11 = BitX FP -> SB

 5 - PB12 = BitX FP -> SB

 6 - PB13 = CLOCK, 18MHz !!!, 32 clocks/transfer.

 7 - PB14 = BitX FP -> SB

 8 - PB15 = BitX FP -> SB

So, it seem that most of statements up until now regarding the communication protocols were false, including some assumptions of mine.  :palm:

The clock is a respectable 18MHz, the data bus seem to nibble oriented, 4bits / clock, 32 nibbles  or 16 bytes or 4 x 32bits values.
No matter how small is the change ( for example just moving the encoder one position, there is a minimum of 16 transfers, or 64 x 32bit values.
So I have the feeling that each time the SB it's fully programmed, no matter how small it's the change !!!

Also barring pin 3 (PA1) doing any direction switch, the data transfer seem to be strictly from FP to SB, I have no idea how the stored waveforms are read back, if they are read.
Have a look on the pictures attached, made with my crappy TBS1104, there are 3 bits and the clock is on the yellow trace.

TODO:

 - See what is happening with pin 3, it really the transfer uni-directional ?
 - See which bit is which ?
 - Connect a proper LA (if it will ever arrive) and get a number of transfers
 - Decode the protocol and how the calibration constants are loaded.
 - The waveforms are actually stored in the SB flash and the FP just tell the SB which one to load ?

 Happy New Year !!!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 31, 2017, 10:19:02 pm
The bus should have traffic to the front panel in counter mode.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on December 31, 2017, 10:25:40 pm
Could be, after I'll get my LA, I'll first try to find the bit positions, putting something like 12,234,567,890 Hz and looking at the patterns. Once the bits and transfers from FP to SB are done, then follows the frequency meter mode, prolly pin 3 will switch the direction.
I'm actually curious what is happening, but it's interesting, 18MHz clock, that's a lot for the little MCU, really interested on how it was implemented.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on December 31, 2017, 10:34:52 pm
Regarding the pins sniffed:

PB12 is likely SPI2_NSS
PB13 is likely SPI2_SCK
PB14 is likely SPI2_MISO
PB15 is likely SPI2_MOSI

As PB11 can be I2C2_SDA or USART3_RX, I'd assume it is either the RX port of UART3, or more likely a second NSS (chipselect) for the SPI.

18MHz corresponds to a PCLK divided by 2. 18MHz is nothing to be afraid of. This ain't arduino for kids. Those other  pins aroun the clock pins are definitely the SPI peripheral. There is no way it will be different. PB12 most likely the chip select signal and PB11 maybe second chip select signal.

Now you can start sniffing the data from the SPI.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on December 31, 2017, 11:45:38 pm
Hi!

Just a quickie one!

I've been reading the STM32F103C8 Datasheet, I was just wondering if Pins PA4 to PA7 are the ones returning from the main PCB (Altera Cyclone Arbitrary W.F. Data out perhaps?) that indicate to the STM32 MCU what waveform is being generated?

These are given in the STMJ32 Data as:-

PA4:- SPI1_NSS/USART2_CK/ADC12_IN4;

PA5:- SPI1_SCK/ADC12_IN;

PA6:- SPI1_MISO/ADC12_IN6/TIM3_CH1;

PA7:- SPI1_MOSI/ADC12_IN7/TIM3_CH2.

Monitoring these four lines whilst changing the waveform-type/amplitude/frequency, etc., using the front-panel controls would suggest this to be the case - I'm assuming these parameters are stored in the Winbond Flash, so it might be worth a continuity-prod or two to see if PA4 to PA7 on the STM32-etc., goes back to the Winbond!

Chris Williams

PS!

I've just realised Member DC1MC only mentioned an 8-pin interface connector plug between FP and SB, but there has to be another one for the 3.3V/5V supplies, earth, etc., so it's possible there may be another multi-plug with some more STM32 lines on it!

BTW, I won't get my generator at least until I'm back on duty @ work Tuesday, but I can surmise one or two things from the information already given so far!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on December 31, 2017, 11:59:49 pm
Now there seems to be a mess in the thread.

What pins are connected in between the MCU and the other board?

Or how did you come up with the SPI1 pins?

//And note there won't most likely be any "waveform indication pins" - why would they? You have full duplex rather high speed SPI bus already there.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 01, 2018, 12:08:51 am
PPS!

Just a thought - I've just been reading Carmine Noviello's book "Mastering STM32" (V0.21), Section 20.2.1 "Flash Memory Unlocking", p. 573, where the Author clearly recommends the line:-

HAL_StatusTypeDef HAL_FLASH_Lock();

be included in the code to prevent inadvertant over-writing of the flash memory due to transients, power-faults, etc., etc., - what's the betting the Chinks (accidentally-on-purpose?!) left this line out of their code to ensure the things'd fall over before the warranty expired to try and get back development costs in the hope disgruntled users would buy replacement/upgraded/newer units?!

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 01, 2018, 12:15:13 am
Hi!

Quote
Now there seems to be a mess in the thread.

What pins are connected in between the MCU and the other board?

Or how did you come up with the SPI1 pins?

The SPI1 pins are given in the STM32F103C8 datasheet pin-out table.

Member DC1MC mentioned only one 8-pin plug, none of which carry power-supply voltages, so there has to be another connector for these, so if more than two/three pins are used on a second or further connector plug, there's every possibility of there being further connections back to the MCU!

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 01, 2018, 12:23:17 am
The cable between the front panel and main board is a 12 wire cable split into two groups of 4 & 8.  The 4 pin  group is  Gnd, Rx, Tx and 5V.  There are no other wires between the FP & MB.  My main board is marked V1.5.

BTW Mine was working fine for a couple of hours after I completed the grounded plug installation feeding my scope and a counter.  I shut the bench down for the night using the power strip.  When powered up the next morning it looked *exactly* like @canyon's photos at the start of the reflashing thread.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 01, 2018, 12:31:04 am
Hi!

Fair enough, Member rhb's identification of the connections rules out a direct connection from PA4-PA7 back to the WinBond, and also indicates the 3.3V reg for the STM32 will (or should be!) on the front panel PCB.

That does suggest the data control interface on lines PB12-PB15 could possibly be bi-directional, I don't think Tx and Rx will be anything like fast enough to carry waveform parameter data back.

I'll get started on a FP schematic as soon as I get my hands on my unit when I'm back at work!

Chris WIlliams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 01, 2018, 12:35:30 am
SU1 on the FP board is an AMS1117 3.3 V LDO regulator.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on January 01, 2018, 12:58:58 am
Hi Chris,

have you read what I have written or are you deliberately ignoring my posts? I have already written you that SPI2 is used and identified the pins accordingly.

I do not know where did you get that those pins PA4 to PA7 are used in the FY6600 to communicate with the FPGA board. Or have I missed a post about them?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 01:35:26 am
On my device there are 2 separate cables between FP and SB,

One 4 pin, J1
5V
GND
TxD
RxD

And the 8pin data cable that does not carry any power, it just have a GND wire.

The clock and data pins I have described in previous post.

I will see when my LA will arrive if the protocol is a variant of SPI or some other non-standard, simpler stuff. Even if the Intronix it's a bit old, it should be capable of decoding all SPI versions.
It's very likely that the SPI serializer block is used, because 18MHz it's really difficult to do by bitbanging. What it's left to see it's to see if they used the SPI interface in a sane way or in some perverted mode.
Dear members that already have a logic analyzer, please connect and determine at least the purpose of pin 3 (PA1), is it a direction switch or what.

come on, you collected all this coll gear, use it this year  :P

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on January 01, 2018, 01:40:10 am
Well... I don't have the FY6600 to begin wirt.  Maybe if one could donate or lend me one for reverse engineering? Germany somebody?  ;D
This way I can only give expertise on STM32 device side.

They use the SPI2 for sure. Just identify the rest of the GPIOs where do they end on the FPGA board.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 01:46:34 am
Well... I don't have the FY6600 to begin wirt.  Maybe if one could donate or lend me one for reverse engineering? Germany somebody?  ;D
This way I can only give expertise on STM32 device side.

They use the SPI2 for sure. Just identify the rest of the GPIOs where do they end on the FPGA board.

There is just ONE GPIO left to be identified (PA1).
It will not survive too much afrer my LA will arrive and it will be identified ;).

On the other side, if you're close to Mannheim, I can drive to you with my FY, assuming that you have a proper LA and scope, we can even try to reproduce the Fraunhofer experiment ;).
The problem is that my LA is scheduled to arrive on 8.01, exactly when my vacation is over :(

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on January 01, 2018, 02:05:09 am
Thanks for your interest, unfortunately not anywhere close around Mannheim.  But Germany is the closest place where someone could have one  :)

I should be doing different things, than playing with electronics anyway... but you know it: Everything is better than to do some boring obligatory work for ... 




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on January 01, 2018, 06:12:03 am
The 4 pin  group is  Gnd, Rx, Tx and 5V.  There are no other wires between the FP & MB.  My main board is marked V1.5.

The 4 pin cable is from the USB to 232 CH340 device on the main board to the FP. As far as I could tell that 5V line was the only power feed to the FP so there must be a 3.3V reg on the FP board.

Mark
G0MGX
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 10:34:24 am
Gentlemen, let's focus on the important things, there is no other power line to the FP except the 5V0 coming along with the serial interface cable, the FP has 3V3 LDO  on PCB and this is that. Once I'll be able to get more friendly with KiCAD I may drawn a schematic, of I could draw it on paper faster and have some kind soul put it in his schematic capture program and produce a PDF out of it. This is really the least of our concerns here.

The data communication seem to be done over an SPI interface, that makes sense, it's bidirectional and easy to implement in FPGA. One of the signals that it's not part of the SPI interface is just a pull down transistor and another it's a mystery one that seem to stay unused at lest in the simple tests I've done.

Now, please, pretty please with sugar on top, could someone hook an Logic Analyzer on the SPI interface and get some traffic sniffed, she/he'll be my hero, because my LA coming form UK it's stuck on "Arrival Scan" and Germany it's fully stopped now :(. Come on, out of 5-6 people that spend time modding this generator it HAS to be one willing to donate a bit of time with an LA.

Waiting for good news,
DC1MC
   

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 12:06:40 pm
OK, here are some more snapshots, taken with my most craptacular Craptronis scope EVAR, TBS1104, if you ever see one, destroy it with fire and a large hammer :scared: :horse:

Legend:

Yellow - SPI CLK
Blue   - PB15 MOSI
Lila     - PB12 SPI_NSS
Green - PB11 Used as another CS


There seem to be at least 2 SPI devices, form the miserable screen I just can see that there are data transfers when at least one tof the selector signals is in 0 and mone when both are 1, this is as expected
Another thing is that the word size is set to 16 bits.
And yet another thing is that there are a crapload of transfers, to just change the the last digit of the frequency  :-//.

Right now I've reached the limits of this Fully Feature-Free (TM) (C) Tektronix piece of junk, so please try to reproduce my experiments with a better scope and suggest me please a better scope in 500EUR range, this POS has to go.

Enjoy the (crappy) shots I've made with our data transfers.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 01, 2018, 12:07:05 pm
Hi!

I would like to have a go at this myself – can anyone who's a bit more "au–fait" with Logic Analyzers than I am suggest what sort I'll need – does it need an expensive "all bells and whistles" instrument that can decode the logic–bits into a hex byte, or it it possible to make up some sort of SPI decoder for the STM32 that can display the data in some form of human–readable format?

I do have an Zicon Electronics 16–channel one that displays on an ordinary oscilloscope – is this suitable for reading the SPI Lines?

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on January 01, 2018, 12:07:21 pm
I'm happy to put some time into this, the problem is I have no experience with SPI comms and hence I dont know what I am doing.

I've attached a 'scope grab of each pin (pin 2 is ground for sure) and also the drivel I get when I try and decode this.

I'm not sure what line is CS?

If anyone wants to give me some guidance I am happy to help, otherwise I have to retreat to the sidelines and hope to learn.

I will now start a search on you tube for sniffing SPI and see what I can find.....

Pin 1:
(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pin%201.png)

Pin 3:
(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pin%203.png)

Pin4:
(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pin%204.png)

Pin 5:
(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pin%205.png)

Pin 6:
(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pin%206.png)

Pin 7:
(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pin%207.png)

Pin 8:
(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pin%208.png)

Some total Drivel:
(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pulse%20View.png)

Mark
G0MGX
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 12:17:17 pm
Hi Mark, and thanks for chiming in, I was getting a bit lonely here  :-\. So, YOU WILL NOT RETREAT, YOU WILL NOT GIVE UP, you hear me  :scared:.

Now is the chance to put that gear to good use and learn a bit in the process.

So first things first, just ignore the any pins besides 4 to 8.

We don't have a really simple SPI interface here, there are at lest two, maybe three devices, most likely one is the Winbond flash.

You see on my top post what the signals are, put MISO as well, and set the logic analyzer to trigger on combinations of pin 4 and 5 as CS or just pin 5 as  CS that seem to be always 0 when trasnfers are made.

And now get us some nice decoded data, my better half is calling for lunch, but I'll be back.
   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on January 01, 2018, 12:28:27 pm
Those scope measurements look bad. You need to use better probing technique. Use very very short ground lead or make a 50ohm cable terminated properly at both ends.  Otherwise the waveforms will be full of crud. Probing high speed digital circuits ain't no easy...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 01, 2018, 12:33:37 pm
Hi!

One of these is within my monthly pocket money allowance – would it be worthwhile trying one on the FY6600?

https://m.ebay.co.uk/itm/USB-Logic-100MHz-16Ch-Logic-Analyzer-16-Channel-Analyzer-for-ARM-FPGA/182821963784?epid=915703876&hash=item2a9109c808:g:OdwAAOSwLiJZ3YiF

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 12:51:19 pm
Hi!

One of these is within my monthly pocket money allowance – would it be worthwhile trying one on the FY6600?

https://m.ebay.co.uk/itm/USB-Logic-100MHz-16Ch-Logic-Analyzer-16-Channel-Analyzer-for-ARM-FPGA/182821963784?epid=915703876&hash=item2a9109c808:g:OdwAAOSwLiJZ3YiF

Chris Williams

From the Chinglish description it sounds OK, especially if it's supporting the original software somehow.

@Yansi: I double dare you to get better waveforms with this POS TBS1104 !!!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on January 01, 2018, 12:51:43 pm
I'm off to do some more research into this data format.

(http://qsl.net/g/g0mgx//BlogFiles/FeelTech/Pulse%20View%202.png)

Mark
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 12:56:53 pm
I'm off to do some more research into this data format.


Mark

Mark, the pin 6 clock looks a bit strange to me, there should be 16 clock cycles and they are not, at least in the picture, can you switch your LA to state mode and sampe using pin 6 as clock ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on January 01, 2018, 01:19:49 pm
Interesting

I can see and count 16 clock cycles on the 'scope but not on the LA.

I've just hooked the LA directly to my sig gen and it's good up to about 3MHz and then the capture becomes inaccurate above that.

Therefore this LA of mine is a load of https://www.urbandictionary.com/define.php?term=Dingo%27s%20Kidneys (https://www.urbandictionary.com/define.php?term=Dingo%27s%20Kidneys)

Mark
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 01:22:46 pm
Yup, dingo kidney it is, same as my 4 channel scope  :rant:, but hopefully in state mode it will be able to clock with 18MHz, if not, you can safely discard it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on January 01, 2018, 01:34:12 pm
I think it is related to USB connection speed so have some things to try.

Mark
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 01:51:53 pm
Yup, if the LA doesn't have a lot of local buffers, the samples will be lost in unattended sampling.
Better switch it to state mode and use SPI_SCK (pin 6) as sampling clock, at least the data will be correct.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 01, 2018, 03:46:19 pm
Hi!

Quote
From the Chinglish description it sounds OK, especially if it's supporting the original software somehow.

Fair enough - I'll try one and post what I get on here using it when it arrives!

Chris Willams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on January 01, 2018, 05:03:56 pm
Better switch it to state mode and use SPI_SCK (pin 6) as sampling clock, at least the data will be correct.

I dont see any reference to "state mode" in PulseView - might it be called something else?

Installing a USB3 PCI card has improved things, but still I am missing samples at very repeatable intervals - looks like something else is occupying the PC at those times as the pulses being dropped now are evenly spaced. It is supposed to support up to 24MHz dependent on PC hardware and data transfer rates so there are more options for me to try.

I haven't given up yet (well not quite anyhow).

Mark
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 01, 2018, 05:17:40 pm
Hi!

One of these is within my monthly pocket money allowance – would it be worthwhile trying one on the FY6600?

https://m.ebay.co.uk/itm/USB-Logic-100MHz-16Ch-Logic-Analyzer-16-Channel-Analyzer-for-ARM-FPGA/182821963784?epid=915703876&hash=item2a9109c808:g:OdwAAOSwLiJZ3YiF

Chris Williams

From the Chinglish description it sounds OK, especially if it's supporting the original software somehow.


Those are blatant copies of a Saleae product which sells for a lot more and of very high quality.  I've not investigated closely, but I *think* that Saleae has the source code available online.  It appears that their attitude is we're selling quality hardware at a fair price.  You can buy cheap knockoffs and use our software if you want.  When you get tired of the problems you'll want to buy one of ours.  It also works with Sigrok.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 06:43:13 pm
Better switch it to state mode and use SPI_SCK (pin 6) as sampling clock, at least the data will be correct.

I dont see any reference to "state mode" in PulseView - might it be called something else?

Installing a USB3 PCI card has improved things, but still I am missing samples at very repeatable intervals - looks like something else is occupying the PC at those times as the pulses being dropped now are evenly spaced. It is supposed to support up to 24MHz dependent on PC hardware and data transfer rates so there are more options for me to try.

I haven't given up yet (well not quite anyhow).

Mark

OK, I had a look on this PulseView software, same unintuitive, clumsy interface (but hey, it's scriptable) and a complete lack of documentation, so to say a typical open source project.
So to summarize, your problem is that blindly sampling at the highest speed will not give anything anything besides digital garbage, because the you can't stream fast enough over USB at this clock.
So forget about it and don't do it anymore, it's useless.


Good, now from what I've seen from the abstraction aspies that build that clumsy unintuitive junk decided that the distinction between sample and state mode is not necessary (HP, Agilent and friends must be cretins to do it  :palm:) so no mention about it, BUUUT it seems that you can assign a signal to be used as a state clock, of course I had to google this, because it's not obvious.
So assign the Pin6 as the (state) clock and you should be able to collect some meaningful data, I would sample at rising edge.
Basically this way you just record the states and bits that are necessary and don't play an oscilloscope when it's not needed, the sampling feature is cool in many situations but not in this case.
If even after assigning the external clock, the LA can't save correctly over an USB 2.0 the short and anemic bitstream, then either throw away the hw or the sw.
Good luck and bring us some data to chew on  ;D
   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cpposteve on January 01, 2018, 07:03:21 pm
Partner bought me one of these for christmas as im currently trying to self teach my self electronics (have been for the past 20+ years) and looks to be ok for the beginner, was just wondering to myself today if there is any firmware updates for this, and a few seconds on google brings me this  :'(. anyway, really interesting reading this thread and to all those that are helping to get to the bottom of this keep up the good work.

steve
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 01, 2018, 07:32:18 pm
Partner bought me one of these for christmas as im currently trying to self teach my self electronics (have been for the past 20+ years) and looks to be ok for the beginner, was just wondering to myself today if there is any firmware updates for this, and a few seconds on google brings me this  :'(. anyway, really interesting reading this thread and to all those that are helping to get to the bottom of this keep up the good work.

steve

Hi Steve and welcome to our merry gang  ;D, be yourself the change in the firmware, and if you want to train yourself in electronics (the practical side) now it's an excellent change to do it, select from the plate of goodies:

- Look higher in thread, practical examples on how to make the device electrical safe for other devices, replacing the power connector with a grounded one, changing the cabling and modifying the back pannel.
Skills needed: basic craftsmanship with a Dremmel tool and a file, some basic soldering skill, ability to follow simple instructions and pictures.

- Capture the schematic of the Power Supply (low skill), Front Panel (average skill) and Signal Board (advanced skill).
Skills needed: The ability to disassemble non-destructively an equipment, recognizing components, using a multimeter with a continuity beeper, using a schematic capture CAD program ( KiCAD, Circuit MAker, pirated version of Altium).

- Replace the miserable 16V electrolytic capacitors on +/- 12V rails in preparation for changing the power supply to a better one delivering stabilized +/- 15V.
Skills needed: Basic desoldering/soldering skill, a good soldering station and eventually a desoldering tool.

- Help the effort of decoding the communication protocol between the FB and SB, to be able to control the device with another software or board, for example an RPi. Also if the FW craps out, to get your calibration constants in a safe place.
Skills needed: Ability to work with a scope and logic analyzer, connecting over the signal cable in a movie hacke way :). Tools needed: a GOOD logic analyzer and a reasonable scope (this will be needed later).

- Help build a new, improved firmware for the front panel or for other MCU with a LCD, alternatively for a tablet, Android or IPAD
Skills needed: understanding the hardware and the control protocol, advanced programming capabilities for iOS or Android.

- Improve the Signal Board and signal quality, replace the power supply with a better one with stabilized outputs, eventually a linear one instead of the switching mode one, replace the output operational amplifiers, recalibrate the whole system while system while doing many measurements for at least 1024 calibration points, enter in flame fests about the spectrum analyzer settings and rubidium controlled reference clocks.
Skills needed: master analogue and digital hacker skills. Tools needed: Highly advanced Spectrum analyzer, GPS synchronized frequency reference, complex power meters with precise probes, highly advanced scope to measure the phase shift.

- Rebuild the FPGA programming based on the above acquired knowledge, discover neat trick to move the frequency for non sinus waveforms, shame the FeelTech Chinese programmers and become a forum luminary and mentor. Avoid and be anoyed about all the recruiters begging to hire you.
Skills needed: alpha level hacker in mixed mode devices. Serious deep theoretical and practical knowledge of the whole matter. Tools needed: cheap USB Blaster-2 and Quartus software over what you've aleady collected.

So you see that starting with this humble cheap generator can improve your electronics skill and advance you professionally a lot. You just have to start  :D, so go get'em  :box:
 
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 01, 2018, 08:31:12 pm
Hi!

Quote
Hi Steve and welcome to our merry gang  ;D, be yourself the change in the firmware, and if you want to train yourself in electronics (the practical side) now it's an excellent change to do it, select from the plate of goodies:

- Look higher in thread, practical examples on how to make the device electrical safe for other devices, replacing the power connector with a grounded one, changing the cabling and modifying the back pannel.
Skills needed: basic craftsmanship with a Dremmel tool and a file, some basic soldering skill, ability to follow simple instructions and pictures.

- Capture the schematic of the Power Supply (low skill), Front Panel (average skill) and Signal Board (advanced skill).
Skills needed: The ability to disassemble non-destructively an equipment, recognizing components, using a multimeter with a continuity beeper, using a schematic capture CAD program ( KiCAD, Circuit MAker, pirated version of Altium).

- Replace the miserable 16V electrolytic capacitors on +/- 12V rails in preparation for changing the power supply to a better one delivering stabilized +/- 15V.
Skills needed: Basic desoldering/soldering skill, a good soldering station and eventually a desoldering tool.

- Help the effort of decoding the communication protocol between the FB and SB, to be able to control the device with another software or board, for example an RPi. Also if the FW craps out, to get your calibration constants in a safe place.
Skills needed: Ability to work with a scope and logic analyzer, connecting over the signal cable in a movie hacke way :). Tools needed: a GOOD logic analyzer and a reasonable scope (this will be needed later).

- Help build a new, improved firmware for the front panel or for other MCU with a LCD, alternatively for a tablet, Android or IPAD
Skills needed: understanding the hardware and the control protocol, advanced programming capabilities for iOS or Android.

- Improve the Signal Board and signal quality, replace the power supply with a better one with stabilized outputs, eventually a linear one instead of the switching mode one, replace the output operational amplifiers, recalibrate the whole system while system while doing many measurements for at least 1024 calibration points, enter in flame fests about the spectrum analyzer settings and rubidium controlled reference clocks.
Skills needed: master analogue and digital hacker skills. Tools needed: Highly advanced Spectrum analyzer, GPS synchronized frequency reference, complex power meters with precise probes, highly advanced scope to measure the phase shift.

- Rebuild the FPGA programming based on the above acquired knowledge, discover neat trick to move the frequency for non sinus waveforms, shame the FeelTech Chinese programmers and become a forum luminary and mentor. Avoid and be anoyed about all the recruiters begging to hire you.
Skills needed: alpha level hacker in mixed mode devices. Serious deep theoretical and practical knowledge of the whole matter. Tools needed: cheap USB Blaster-2 and Quartus software over what you've aleady collected.

So you see that starting with this humble cheap generator can improve your electronics skill and advance you professionally a lot. You just have to start   :D, so go get'em  :box:

Amen to that – that's basically my plan with these (at least as far as the first five paragraphs at any rate!) as well!!!!

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 01, 2018, 10:56:43 pm
If you've got some spare time after what @DC1MC has outlined you can help with this project:

https://www.eevblog.com/forum/testgear/gw-instek-gds-2000e-released/msg1388999/#msg1388999 (https://www.eevblog.com/forum/testgear/gw-instek-gds-2000e-released/msg1388999/#msg1388999)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on January 02, 2018, 09:45:22 pm
Hi

You know what ? I'am a happy man  :-+
All the modifications I intended to do since the FY6600 arrived here are now completed.

- Mains socket with earth tied to ground : done
- Internal PS upgrade with fast switching diodes, better output capacitors : done
- <1ppm clock (low cost DIY 50MHz) : done
- reflashing the flash memory where the sine waveform had been corrupted : done

Flashing : thanks to Cybermaus for his precious tips.
One more advice, don't forget to firstly erase the flash before rewriting it !
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 02, 2018, 10:11:55 pm
Hi Ebel, nice mods, I plan to do them myself after I'm done with the "hacking", if the device survives ;).

Would you join our reversing effort for the protocol ?

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 02, 2018, 11:03:19 pm

- reflashing the flash memory where the sine waveform had been corrupted : done

Flashing : thanks to Cybermaus for his precious tips.
One more advice, don't forget to firstly erase the flash before rewriting it !

How?  Please tell us!!  I've been waiting 2 weeks for FeelTech & sportgogo to reply with anything more than empty promises.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 02, 2018, 11:15:03 pm

- reflashing the flash memory where the sine waveform had been corrupted : done

Flashing : thanks to Cybermaus for his precious tips.
One more advice, don't forget to firstly erase the flash before rewriting it !

How?  Please tell us!!  I've been waiting 2 weeks for FeelTech & sportgogo to reply with anything more than empty promises.

It's the Signal Board flash where the waveforms are stored, the Front Panel firmware still has to be "liberated" ;)
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 02, 2018, 11:47:29 pm
Hi Everyone - another new member here.

I've been reading this thread for a couple of weeks, and my FY6600 just arrived today.  I've only had half an hour to play with it, and it seems to be working fine.  I've also had a look inside in preparation for doing the PS mods, and the main board is now up to v1.501.  The PS board is one made by Suoer, and looks even weedier than the Feeltech board in other members' boxes (but has the same layout).  It's giving 4.33uA @ 92.4v AC on the BNC sockets, so the earth mod is a prority.

I also thought I'd take a look at the stuff on the CD to see what version the software was up to (only 5.2), and went to check the version I downloaded and installed from the Feeltech website a few days ago, using the customary Help - About route.  However, on this version (5.3 as I found out from the original filename), there is no "About", but a single menu option under Help, labelled "Repair_Sine", which attempts to connect to the FY6600 when clicked.  As I haven't connected the unit to my PC yet (and won't be until the mods are done) I have no idea what the outcome would have been, but what's the likelihood of Feeltech having included an undocumented fix for the corrupted sine waves problem in their latest PC control software?  Just a thought ...

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on January 03, 2018, 08:30:08 am
Hi Dave

Interesting!

When you say your unit is working - are you able to reproduce any of the issues in my video?

http://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-issues-list.html (http://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-issues-list.html)

Assuming your version of firmware is the same as mine, if your unit doesnt exhibit the same issues as mine, then I will have to start to look at other possible hardware issues in my unit.

Grateful for your report back!

Mark
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 03, 2018, 11:40:52 am
Hi Mark,

I'll see if I get time later today to do a comparison, but right now the DPD man has just been to the door and I've got a nice new Airspy HF+ in my hand which needs to be played with!

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on January 03, 2018, 11:48:10 am
I have been following this thread for some time. I am not in the same league as you hackers, but your discussion has inspired me to look into logic analysers. My el cheapo unit arrives in a couple of days. I have downloaded the Seleae software and played with it in demo mode, but I'd rather use Sigrok because of the open source licence and the possible proprietory blocks I will find in the Seleae. I have explored the Sigrok site but find I don't speak the language. Trying to download Pulseview sends me around endless loops and null files. Can anybody list how to download and install Pulseview for Windows 10? I'd appreciate the help. Thanks.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 03, 2018, 11:52:45 am
@plb - And I thought that down there they speak a dialect of English  >:D

Here:
https://sigrok.org/wiki/Downloads (https://sigrok.org/wiki/Downloads)

Direct links:
http://sigrok.org/jenkins/job/sigrok-cross-mingw/buildtype=static,debugtype=release,platform=cross-i686-w64-mingw32/lastSuccessfulBuild/artifact/pulseview-NIGHTLY-32bit-static-release-installer.exe (http://sigrok.org/jenkins/job/sigrok-cross-mingw/buildtype=static,debugtype=release,platform=cross-i686-w64-mingw32/lastSuccessfulBuild/artifact/pulseview-NIGHTLY-32bit-static-release-installer.exe)

But IMHO, the software is crap.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on January 03, 2018, 08:12:45 pm
Would you join our reversing effort for the protocol ?

 Cheers,
 DC1MC

Could be a nice challenge, thank you for the invitation.
however that was not my trip when I bought the FY6600 and I've no skills in hacking protocols (nor the set of equipment to do that).
My generator woks fine now after beiing modified as described above.
Go ahead DC1MC, I'm with you  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on January 03, 2018, 08:44:23 pm

- reflashing the flash memory where the sine waveform had been corrupted : done

Flashing : thanks to Cybermaus for his precious tips.
One more advice, don't forget to firstly erase the flash before rewriting it !

How?  Please tell us!!  I've been waiting 2 weeks for FeelTech & sportgogo to reply with anything more than empty promises.

Have a look at this post, you'll have all the explanation to read/write the flash memory.
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1352448/#msg1352448 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1352448/#msg1352448)
All you need is a CH341a board (seek it on ebayy or aliexprss, mine is the black board), and some skills in cabling for linking the JTAG footprint on the FY6600 main board to the CH341.

FY6600    CH341(25SPI pins)
1   ->       6
2   ->       4
3

4  -> I
5       I (connect JTAG 4 to JTAG 6 to disable the Cyclone during flash read/write operation)
6  <- I

7   ->    2
8   ->    1
9   ->    5
10 ->    4 (same as 2 = GND)

CH341A = set to Windbond W25Q16BV
If your cabling is correct you'll be able to read the flash memory.
Let us know ;-)


Cheers
(don't hesitate to DM me if you need some help)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 03, 2018, 09:15:34 pm
Hi Mark,

I've watched your video and tried to replicate the issues you noted, but with limited success.  I have no problem at all with Ch2 switching on after a soft off and on, and no problems with remembered offsets, regardless of waveform, frequency or amplitude set. (I assume you've checked the channel boot conditions [SYS - F4] to make sure that Ch2 is actually set to turn on?)  I did get the apparent amplitude jump when changing from 0.5v to 0.6V, but it's caused by an offset of 18-20mV occurring when the relay activates - the amplitude changes correctly, but the whole waveform moves vertically, and this can be seen in the video as well.  Obviously the circuits switched by the relay are not as well matched at the changeover as they could be.  The relays in mine also change with just a single click, so you could be right about a dodgy one in yours (or maybe a borderline voltage failing to activate it cleanly?).

You mentioned a phase change problem at one point, but all I could find was little glitch which occurred when changing amplitude on Ch2 at 10MHz whilst the scope was set to trigger on Ch1 - when the relay activated as above there was a slight (12deg) phase shift.  This wasn't present at much lower frequencies, so it's probably only noticeable at the higher end of the scale, and it disappeared when I set the scope to trigger on Ch2.

I hope this is of some use!

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 04, 2018, 07:06:13 pm
Hi!

My FY6600 60 MHz unit arrived this morning, in a plain cardboard box with "FY6600 signal Generator" in black on the side.

Supplied with the generator is -

"QA Assurance" card entirely in Chinese;

A thin floppy BNC – BNC lead about 30 cm long;

One (not two!) BNC – Crocodile–clip lead;

Software CD that might or might not be readable;

Unbranded "Figure–of–8" lead; (I thought Feel–Tech promised they'd fit a three–pole connector?! Or have we to wait for the delights (!!!!) of the next model?!)

Piccies to follow tomorrow when I've brought it home! I'm not sure what version F.W. they've foisted on me as I've not tried it out yet!

I'll begin with measuring the phantom BNC–common to mains earth voltage and the maximum p–p  square–wave amplitude and frequency before serious distortion begins, and also the PSU voltages etc.

I realize this is completely standard stuff others have already done, the idea being to give a comparison between older and more recently supplied units, as other Members have found the internal cheap power–supply boards fitted are subject to considerable variation in type and performance!

I propose to use the AliExpress/Bangoood USB Multi–Output Kit PSU (300 mA nom. per o/p., plus one of the "LM317/LM337 Linear Voltage Regulator Kits" to replace the low quality original, the linear kit carrying the rectifiers, etc., used to give ± 15V for the output–amplifiers, whilst the +3.3V and 5V outputs from the "Banggood" kit will supply the digital sections. A toroidial 18V 1A mains transformer is proposed to supply the replacement PSU PCBs and full documentation/pictures will be provided for this.

As well as the above, I'll convert the mains switch to illuminated D.P. rocker as recommended by Elektor magazine in their guide "Safety Recommendations for construction of Electronic Equipment", frequently republished in their magazine.

I'll start work on the front–panel schematic & parts–list next week!

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 04, 2018, 07:25:33 pm
My Intronix LogicPort arrived today  8), I'll familiarize myself with the software and tomorrow I'll do a decoding session.  :box:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Studio1@29 on January 05, 2018, 12:13:28 pm
I have just taken delivery of a FeelTech FY3200S  Dual Channel Arbitrary Function Signal Generator/Counter from e-Bay and it cost  £46.99 (inc delivery) It came with a micro CD with User Manual on it - but that was pretty useless given the complexity of this beast - so I e-Mailed the FeelTech Technical Support this morning - and about an hour later got their comprehensive and helpful reply. e-mail: <feeltech@125.com>  Michael  UK
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 09, 2018, 07:56:10 pm
Interesting that FeelTech now has an additional contact.  I've still received *nothing* for either FeelTech or sportgogo.  No replacement panel or firmware update.  Not even an email update on status.

Has anyone with defective FW had any useful response or just lots of empty promises?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on January 09, 2018, 08:22:16 pm
Realistically there's two things they can do :

- Fuck the buyers of 3.0/3.1 firmware devices.
- Provide unprotected firmware we can burn into a new microcontroller ourselves, not ideal but better than nothing.

Anything else costs too much money, given the thin margins. I don't think they should be rewarded for fucking people ... so I think discussion of purchasing/improving the device is undesirable. Hell if I had my way the title would be changed to "FeelTech FY6600, firmware broke, devices bricked, no fix in sight". Use the little power this forum has for the best.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 09, 2018, 09:05:43 pm

- reflashing the flash memory where the sine waveform had been corrupted : done

Flashing : thanks to Cybermaus for his precious tips.
One more advice, don't forget to firstly erase the flash before rewriting it !

How?  Please tell us!!  I've been waiting 2 weeks for FeelTech & sportgogo to reply with anything more than empty promises.

Have a look at this post, you'll have all the explanation to read/write the flash memory.
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1352448/#msg1352448 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1352448/#msg1352448)
All you need is a CH341a board (seek it on ebayy or aliexprss, mine is the black board), and some skills in cabling for linking the JTAG footprint on the FY6600 main board to the CH341.

FY6600    CH341(25SPI pins)
1   ->       6
2   ->       4
3

4  -> I
5       I (connect JTAG 4 to JTAG 6 to disable the Cyclone during flash read/write operation)
6  <- I

7   ->    2
8   ->    1
9   ->    5
10 ->    4 (same as 2 = GND)

CH341A = set to Windbond W25Q16BV
If your cabling is correct you'll be able to read the flash memory.
Let us know ;-)


Cheers
(don't hesitate to DM me if you need some help)

Hi Ebel0410, rhd. Sorry, was out for a few weeks.

Indeed, Winbond flash has only the waveforms. Enough for Ebel0410's specific problem, possibly/probably not enough for the more generic screen corruption problem.
One warning, with a link that I also added to the original post (https://www.eevblog.com/forum/repair/ch341a-serial-memory-programmer-power-supply-fix/) of the winbond flash: ensure you have a CH341 that can do 3.3V. Some cheap CH341 cannot do 3.3V
The winbond chip can easily deal with 5V, but the FPGA manual is full with warnings about never putting more then 3.3V on its pins.

Unless of course if Ebel0410 already used a 5V CH341. If thats the case, maybe the warning is not so urgent, but I still advise caution.




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 09, 2018, 09:32:05 pm
Hi Dave

Interesting!

When you say your unit is working - are you able to reproduce any of the issues in my video?

http://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-issues-list.html (http://g0mgx.blogspot.co.uk/2017/12/feeltech-6600-issues-list.html)

Assuming your version of firmware is the same as mine, if your unit doesnt exhibit the same issues as mine, then I will have to start to look at other possible hardware issues in my unit.

Grateful for your report back!

Mark

I also do not see those errors with DC offset nor that intermittent amplitude problem.
A broken relay does sound plausible, especially in view of the intermittent nature of it.
Though it would not explain the CH2 not starting up. Did you try unsetting and resetting the CH2 autostart in the system settings?

I did see a phase offset (as well as jitter) at higher frequencies, caused by the 4ns clock cycle.
Originally I explained it  here.  (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1335080/#msg1335080)

At the time I thought it inevitable due to the 250MHz DAC, but later I realized the jitter may be inevitable (or very hard to work around), but since each channel has its own DAC, the 4ns phase difference is just due to sloppy programming.





Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 10, 2018, 12:24:59 am
Hi!

My unit arrived with F.W. 3.2, so hopefully no screen–corruption issue!

The mini–CD came with one solitary folder that was named "V6.60" but I couldn't read anything from it!

I've started work on the Front Panel Schematics, they'll be drawn with Abacom's sPlan as I find this quick and easy to use, gives clear results with IEC 60617 symbols, and it's very well suited to front special symbols, lines, etc., etc., to clarify points on a large diagram, which most other tools are incapable of!

There is a free viewer–tool for these but diagrams will be issued in pdf for everyone to be able to read!

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 10, 2018, 07:42:19 am
Hello everybody, I'm not gone, just finished the vacation and started the work, as usual in the beginning lots of stress and things to catch on  :palm:.

In this WE I'll sniff the hell out of the bus, as promised, I've prepared a special laptop with Win7-32bit for the LA and other 'doze only programs.

Owners of the devices with 3.0/3.1 firmware, especially modified ones without chance for warranty and returns, please also contribute a bit, there is not a big deal to do.

Once I'll get a fairly comlete understanding of the communication protocol, I'll try the Fraunhofer experiment on the FP, just for giggles, unfortunately I only have 3.1 as well, after all the lengthy communication and crap the vendor went fully silent, I can still return the device but why bother, I'll give him a very bad review and they will spring immediately back with a request for modification and hopefully 20EUR back.

 Cheers,
 DC1MC
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 10, 2018, 02:01:42 pm
Hi!

Let's get that special thread started on FeelTech after–sales support!

There is absolutely no excuse for releasing gear with buggy/known defective firmware onto any T & M market, even a hobbyist one!!

These generators are sold specifically for those who are unable to afford the highest–quality Keysight/Tek/Siglent or Rigol models, and they are entitled to a working instrument that remains so for a reasonable length of time, not half-a–dozen power cycles or so, and expecting users to pay for shipping corrupted units to China, etc., at enormous expense when their export shipments are heavily subsided or free is totally unacceptable!

I am going to put my efforts into the best quality schematics I can provide, plus a pcb design for a combined linear/switch mode PSU, transformer operated, that I will try and make to the same dimensions as the cheap and nasty PSU they came with!

The design will use parts from the Banggood Multi–Output USB power–supply kit for the +3.3 V and the + 5V digital supply rails, plus parts from the Banggood LM317/LM337 Linear PSU Kit for the two ± 15V and + 12V rails for the linear/output parts of the circuit.

NB!!

I'm still waiting for my PSU kits to arrive and I'll need 'em "in the flesh" as it were before I can begin my PSU board design.

The design'll be done in Sprint Layout 6.0 with native and Gerber files supplied, and posted in the Projects thread separately for other Members to study and comment on as needed!

The point being tho, why should all this have been needed in the first place?

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 10, 2018, 06:55:54 pm
Great spirits think the same, I've bought from fleabay this beauty for 4,5EUR + shipping. Fused and a lot better islated.
The analogue PSU is next on to do list after the whole fw stuff is done.

And it is needed because our Chinese overlords love to keep us occupied with stuff to repair  :-DD.

 Cheers,
 DC1MC


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 10, 2018, 10:57:50 pm
I've been having a little play with mine this afternoon as well, starting with a switched 3-pin socket on the backplate and earthing the boards.  I still haven't decided what to do about the PS yet, but I checked the output voltages on the weedy Suoer one it came with: +/- 21v and an unstable 4.90-5.10v under no load, dropping to +13.06, -12.10 and 4.97 after boot up, with a 20v PP sine wave output, so not as bad as first feared.

I also wanted to see what it was like if fed from an external wall wart, so I used a 12v 1A supply into a splitter cable feeding a multi output board for the +/-12v lines (as per Diablo's photo - I already had three of these and had planned to try one anyway) and an adjustable LM317 module for the 5v line.  The combination was fine, so is perfectly viable for anyone wanting to run the device in floating mode.  The multi output board couldn't supply enough 5v current to be used by itself, though, as the resettable fuse cut out each time as soon as the FY6600 had booted up.  I think the stated 300mA per line output given in the sales description is rather on the hopeful side, but there's certainly no problem supplying the +/-12v requirements, and nothing on the multi-board even got warm when the LM317 module was used for 5v.  The 1A wall wart was also more than adequate, and was barely warm after an hour's use.

Back on mains power, I checked the frequency accuracy using a 3GHz counter, cross checked with the oscilloscope, and got quite a tight average -4.65ppm result from 0.1 - 60MHz, against the specified +/-20ppm, so I'm not sure whether it's worth the effort to try to improve on that.  I think I can live with making an arithmetic adjustment to set the dialled in value if I ever need super accuracy (which isn't likely).

I also checked for phase shift again, using a constant 5v amplitude, and found that the two channels were only 1.4nS apart after going from 1MHz to 60MHz, although both had also shifted another 2nS along the time axis.  I haven't read your explanation of the 4nS discrepancy you found, Chris, but my readings indicate that it might just be a bit of "natural variation" (in a sample size of two).

Back to pondering what more to do (if anything) with the PS in mine now ......

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on January 11, 2018, 01:16:04 pm
Hi, everyone,

Has anybody addressed or figured out the reason (or reasons) for the jitter (for example, about 4 ns jittering on the falling edge of the squarewave) in this unit? Has anybody suggested any solutions yet? I suppose, just changing the clock oscillator to an ultra-low jitter type wouldn't help here. Thanks to everybody's input!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 11, 2018, 01:41:53 pm
I also checked for phase shift again, using a constant 5v amplitude, and found that the two channels were only 1.4nS apart after going from 1MHz to 60MHz, although both had also shifted another 2nS along the time axis.  I haven't read your explanation of the 4nS discrepancy you found, Chris, but my readings indicate that it might just be a bit of "natural variation" (in a sample size of two).

Interesting. I wonder if that is something they fixed going from my 3.1 to your 3.2.
Because for me, it is very clear and certain: 4ns timeshift on the phase over the entire frequency range. Which I interpret as always exactly 1 tick too late on the 250MHz DAC clock
Something that probably is fixable, and maybe they did  :)

Though numerically, I wonder where your new 1.4ns value would then come from. Can you test this specifically with some frequencies which are whole divisions of the 250mHz clock. Like 50.00, 41.66, 35.71, 31.25, 27.77, 25.00 MHz
If it does not happen there, I may be able to come up with some technobabble on how aliasing could cause this.


Has anybody addressed or figured out the reason (or reasons) for the jitter (for example, about 4 ns jittering on the falling edge of the squarewave) in this unit? Has anybody suggested any solutions yet? I suppose, just changing the clock oscillator to an ultra-low jitter type wouldn't help here. Thanks to everybody's input!

Yes, I am pretty sure its its due to the 250MHz DAC clock (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1335080/#msg1335080). So each next sample is 4ns apart, and alas they cannot make a wave rise or fall in the middle of that.
So while the 4ns phase difference is avoidable, I suspect the the 4ns jitter is not. At least, not on a AWG generator.
(a PLL generator would of course be able to get a cleaner square wave)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on January 11, 2018, 02:21:54 pm
Hi, everyone,

Has anybody addressed or figured out the reason (or reasons) for the jitter (for example, about 4 ns jittering on the falling edge of the squarewave) in this unit? Has anybody suggested any solutions yet? I suppose, just changing the clock oscillator to an ultra-low jitter type wouldn't help here. Thanks to everybody's input!
Isn't that the classic square wave frequency not being divisible by the clock frequency jitter?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on January 11, 2018, 07:58:46 pm
Thanks, cybermaus, looks to be just it. Well, you get what you pay for.  :(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 11, 2018, 08:56:21 pm
Not sure I agree to that.

There are some issues with this device, but the 4ns jitter? I strongly suspect that the 10x more expensive equivalent Rigol DG1062Z 60Mhz 2 channel AWG has the same issue.
So we are getting a more then we paid for.

In fact, all of the device is a good deal, with all quirks, even the leaky PSU, if you check price/performance to what said equivalent Rigol would cost.
Only the firmware-self-destruct is below par. So far below par I cannot advise the device till they have a warranty system.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on January 11, 2018, 09:05:38 pm
As I said, what we should be asking for is firmware we can use to fix our devices. It's the most realistic solution.

PS. I still say change the title of this thread to mention bricking to apply a little pressure, it's a top google result for this device, it can help ... or at least provide a tiny bit of retribution. With the single post from the OP it was clearly an advertising post any way, an advertising post for a device which fucked a fair few forum members.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 11, 2018, 09:20:07 pm
I previously suggested a thread entitled "FeelTech FY-6600 Product Support Reviews" with all the empty promises from FeelTech and the sellers posted.

I plan to do this as soon as I have recovered from my bout of flu.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 11, 2018, 09:33:59 pm
I don't think we can change the thread title, can we? It was started by a Feeltech marketing shill.
I do not think Dave would change the title for us. Would set a nasty precedent.

It is the first google result though, a new thread would not easily take that over.

Just always make sure the last page has at least one clear statement "do not buy unless feeltech finally gives warranty" message.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 11, 2018, 10:46:55 pm
I just went through a maddening exercise trying to contact Paypal and eBay who clearly don't want to allow you to contact them except by checkbox forms.  It would appear that I shall have to write a paper letter to complain to eBay.

I ordered mine on 20 Nov and first contacted FeelTech on 8 December.  I feel fairly certain that the strategy at FeelTech is to stall the user until the Paypal and EBay protections expire.

In the meantime, I've modified my .sig.  I should like to suggest that others do similarly.  That will spread the word rather widely.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on January 11, 2018, 10:59:52 pm
rhb, yeah, it is buried a bit deeply. However, you can call them by navigating as follows:

1. Go to https://ocsnext.ebay.com/ocs/home
2. Click Contact us button
3. Select Buying
4. Select Returns
5. Select Returning an item
6. At the bottom of the page, click Call us or call me button
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 11, 2018, 11:13:36 pm
Can you test this specifically with some frequencies which are whole divisions of the 250mHz clock. Like 50.00, 41.66, 35.71, 31.25, 27.77, 25.00 MHz

I did the measurements at the requested frequencies, a lot more carefully than the previous day's rough look, and took the average over four separate trials, after a 30 minute warm up period.  The Ch1 trace was centered exactly on the crosshairs at 25MHz, and the Ch2 lag time was measured at each frequency, the results being:

25.00MHZ   1.00nS
27.77MHz   1.00nS
31.25MHZ   1.10nS
35.71MHz   1.00nS
41.66MHz   1.10nS
50.00MHz   1.20nS

In fact, the relative phase shift was constant from at least 5Mhz to 50MHZ, but both traces kick laterally by about 2nS at 20MHz - otherwise their positions are quite stable.

One thing I did notice today, however, is that the Ch2 amplitude is about 0.15v less than Ch1's when set to 5v at 25MHz, when the channels are supposed to be in sync, and the difference appears to get bigger as the frequency increases.  I'll have to have another look at that to see exactly whats going on over the whole range, and see if other waveforms are affected.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on January 12, 2018, 07:37:55 am
Somewhat unnerving that its labelled as 12v but measuring 15.8V and has 16V rated output caps. They should be 25V rated.

These voltages may well be an issue. Mine are around 14V. The negative 5V regulator gave up the ghost, truncating the negative half of the output waveforms. Both it and the positive 78L05 got stinking hot in operation - I couldn't touch them for more than a few millisec- and the 100uF capacitors got uncomfortably hot. Replaced the negative regulator, then the positive one carked. Its replacement carked, so I mounted a TO220 7805 and ran wires to the SMD pads. Both the regulators are now tolerable to touch. I took the opportunity to replace the metal can caps with 25V tantalum/MnO2 types. They barely get warm. It's been running a couple of hours now. Fingers crossed.

And on another subject - if you ground the signal common, run the 3rd pin ground to the power supply board, not the main board, otherwise when you disconnect the power supply board from the main board it is easy to defibrillate yourself. (Ask me how I know...)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on January 12, 2018, 11:24:34 am
Not sure I agree to that.

There are some issues with this device, but the 4ns jitter? I strongly suspect that the 10x more expensive equivalent Rigol DG1062Z 60Mhz 2 channel AWG has the same issue.
So we are getting a more then we paid for.

In fact, all of the device is a good deal, with all quirks, even the leaky PSU, if you check price/performance to what said equivalent Rigol would cost.
Only the firmware-self-destruct is below par. So far below par I cannot advise the device till they have a warranty system.

Sorry. I expressed myself wrong. I meant that for this money you cannot expect it to be perfect. And yes, this generator certainly satisfies my needs. By the way, I replaced the power supply again. Or, rather, the transformers to one torroidal. Voltages are still +-15V. Also, replaced the 16V electrolytics to be sure with 35V ones (not SMD but through-hole ones; just soldered them on top and used some hot glue to fix in place). Now, somehow, the waveforms do not show ANY visible distortion at any settings. Even the slight distortions you saw in my previous post, are gone.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 12, 2018, 09:21:41 pm
Can you test this specifically with some frequencies which are whole divisions of the 250mHz clock. Like 50.00, 41.66, 35.71, 31.25, 27.77, 25.00 MHz

I did the measurements at the requested frequencies, a lot more carefully than the previous day's rough look, and took the average over four separate trials, after a 30 minute warm up period.  The Ch1 trace was centered exactly on the crosshairs at 25MHz, and the Ch2 lag time was measured at each frequency, the results being:

25.00MHZ   1.00nS
27.77MHz   1.00nS
31.25MHZ   1.10nS
35.71MHz   1.00nS
41.66MHz   1.10nS
50.00MHz   1.20nS

In fact, the relative phase shift was constant from at least 5Mhz to 50MHZ, but both traces kick laterally by about 2nS at 20MHz - otherwise their positions are quite stable.

One thing I did notice today, however, is that the Ch2 amplitude is about 0.15v less than Ch1's when set to 5v at 25MHz, when the channels are supposed to be in sync, and the difference appears to get bigger as the frequency increases.  I'll have to have another look at that to see exactly whats going on over the whole range, and see if other waveforms are affected.

Regards,
Dave

OK, I have a confession to make.
Just to dot the i's, I figured I also measure the delay on my device for all these frequencies. *and now I measure the same 1.2ns*

So I tried all sorts of things to recreate my original delay of 4ns. Long story short, I think I used cables of different length back then... |O
Sorry

However, the 4ns jitter (and its explanation of 250MHz DAC) stands. Just the phase difference does not, it is 1.2 and not 4 on my V3.1.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 13, 2018, 04:50:31 pm
Yep, different length cables certainly make a difference - even 25mm, as I've just found out, is noticeable when the cables are swapped over.

I've also discovered that the 0.15v amplitude difference I was seeing was caused by the ultra-crappy BNC lead which Feeltech supplied: it's got twice the resistance of an RG58 lead of similar length, and probably a huge impedance difference as well.  The BNC connectors are so loose they won't lock onto the sockets properly, and one of them even pulls straight off!

It's prompted me check all my interconnect leads, and I've discovered that I haven't got a single pair of equal length and made from the same cable and fittings, so that's my next little tasklet for this evening....
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on January 13, 2018, 05:51:28 pm
Damn Chinese piece of crap!!!
I was today using the fy6600 for some tasks and all of a sudden here what jumps out. The sine wave goes crazy. It is all over the place (multiple sine waves flashing all around) and the screen of the fy6600 starts showing all kinds of mess. The supply voltages are fine. Output amps seem to work fine, but there is something with the soft, I think. My version is 3.0. Damn Chinese crap. Does anyone have experience of FeelTech responding to these issues?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 13, 2018, 06:02:44 pm
You're done for it, as you can see the<firmware version 3.0 it's a time bomb, and yours just exploded.  :'(
Interested in joining the firmare reversing/extracted effort, because there will not be any trip to China and back for your device ?

 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 13, 2018, 06:20:04 pm
I found I could use mine by resetting the idiotic values.  IIRC there is an ARB setting with a valid sine wave.  As for the rest, read my .sig :-(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on January 13, 2018, 06:22:04 pm
Sure I am interested.
What a nonsense those guys do not provide any support for soft upgrade!  >:( >:( >:(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 13, 2018, 10:32:37 pm
Out of curiosity, Vytautas, why don't you give the "Help - Repair_Sine" option in the latest control software a try.  We don't know what it does yet, but my guess it was added in after it became known that 3.0 was a major problem, and this could be the fix for it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jleg on January 14, 2018, 09:32:15 am
Out of curiosity, Vytautas, why don't you give the "Help - Repair_Sine" option in the latest control software a try.  We don't know what it does yet, but my guess it was added in after it became known that 3.0 was a major problem, and this could be the fix for it.

No, this unfortunately is not the fix. Not sure, if this even is a fix for anything else...
The only thing  on my V3.0 which remained not being totally scrambled is functionality of channel 2. Since the display still is not of much use though, the PC software helps a bit controling the thing.
And in fact, after applying the „fix sine“ from the menu, also the sine shows up again. But unfortunately, this does not last long, nor does it survive a restart. So you end up applying this again and again...

P.S.: just for completeness - nothing heard back from Feeltech, no proposal or anything.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on January 14, 2018, 09:59:29 am
Just tried the "sine repair" thing. Thank you for notifying me.
Unfortunately, that is not repairing anything. Now I can control the sine wave from the PC and it works, when controlled by PC. But the rotary knob does not work for setting the frequency, it only controls the amplitude. The screen still has various signs on it. And other waveforms do not work in any way, neither when controlled from PC.
In a current condition its a 100 euro paper weight.  |O
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 15, 2018, 07:39:34 pm
I saw the topic on FY6600 and signed up,

Thanks for all the great tips and suggestions ,

I just ordered one from ebay,

I was thinking ,a neat way to get galvanic isolation without completely replacing the psu with a linear one is to simply add a shaver transformer isolator socket to the enclosure 230/110-230volt ,plenty of room to mount the switch modes along side too .
Costs around 10 euros from my local electrical supplier .
I think two seperate switchmodes is the way to go ,one for the 5 volts and another for the +/- rails .Replacing the no brand psu caps with proper items should help a lot also. Rf and magnetic sheilding of the transformer and switchers might be worth doing as well as some extra LC at the dc outputs .
 


 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 15, 2018, 07:45:04 pm
Common shaver type socket
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 15, 2018, 09:23:33 pm
Theres a chunky ground terminal on the transformer ,that could remain permanently bonded to mains earth . A 'system' ground switch could be placed between the ground terminal of the psu and mains earth,that way you decide if you want the unit grounded through the mains line or via the unit under test etc ,it allows ground loops to be  broken if the need arises .

I havent tried feeding a switchmode from a transformer before ,the windings will drastically limit the initial inrush current compared to direct mains connection ,probably no bad thing as the capacitor charge on regular wall warts etc creates quite a spark when they are plugged in ,something Ive never liked about switcher psu's .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 16, 2018, 01:04:33 am
Why would you order one after reading about the FW issue?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 16, 2018, 01:56:08 am
Before I purchased the unit I messaged  the seller asking which firmware revision his units were ,I still havent heard back on it from him .
I went ahead and ordered but told them to hold the order until I get the answer to the question .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: mr.fabe on January 16, 2018, 02:01:38 am
Before I purchased the unit I messaged  the seller asking which firmware revision his units were ,I still havent heard back on it from him .
I went ahead and ordered but told them to hold the order until I get the answer to the question .
I purchased my unit on Dec 8th and received the 3.2 FW

Sent from my XT1575 using Tapatalk

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 16, 2018, 03:07:09 am
Thanks for that Mr Fabe,
Hopefully the bad units have been cleared by now ,the supplier I ordered in from seems to have high volume sales so fingers crossed its all ok at this stage .
I found the op amps for the output stage on ebay too ,so I'll most likely solder a couple of them in while Im at it .
The interest and enthusiasm I found here made me want to buy one ,I can take care of the few fixes like mains isolation , extra power supply capacity and adding the output opamps for about 20 euros in parts so its worth a shot.




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 16, 2018, 05:21:16 am
Touch wood my version 2.9 has been fine apart from the sort out issues earlier this thread. Unless you go over $500 you are still hard pressed to find much if any improvement in features and performance which makes the lack of decent assistance from Feeltech ridiculous as they have a niche they could control.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 16, 2018, 07:41:58 am
In the worst case you get a good FPGA development kit ;).
The probes are set, the sniffing will commence soon !!!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on January 16, 2018, 08:12:44 am
Hi, DC1MC,
please, continue your good project.  :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 16, 2018, 10:58:13 pm
I found this and thought it might be of some use ,mentions the Cyclone 4 chip

http://dl.altera.com/?edition=lite (http://dl.altera.com/?edition=lite)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 16, 2018, 11:17:06 pm
Heres a link to a post a while back ,a guy managed to do very similar to whats being attempted here ,

https://www.eevblog.com/forum/testgear/mhs-5200a-serial-protocol-reverse-engineered/ (https://www.eevblog.com/forum/testgear/mhs-5200a-serial-protocol-reverse-engineered/)

maybe its of use .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 17, 2018, 07:03:10 am
Aaaand just like this the stored sine wave on mine got corrupted ( fw. 3.1), and by just like this I mean changing the frequency and turning on and off the channels !!!
Trully a Piece Of Smart  |O 
I'll continue doing the captures and hope that I'll be able to do a list of commands soon, but owners with fw. 3.1 , you're NOT safe !!!


 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 17, 2018, 09:36:12 am
Well, stored waveform corruption on V3.1 is different then firmware corruption on V3.0
Its probably what this new "Fix Sine" menu option in the PC software is about (do try that) and failing that, you can always rewrite the Winbond flash (or flash section) like Ebel0410 did. (He is the only other person I know about with specific sine corruption, and he also had V3.1)

So it seems indeed V3.1 is not safe, but it is repairable.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 17, 2018, 03:19:35 pm
Oh thats bad news Dc ,
Seems crazy that Feeltech wont offer an abillity to upgrade the unit ,anyone that buys this product will have an interest in electronic to begin with ,and getting together the programer card shouldnt be that difficult, it does seem like there might be a few steps in getting the right code to each of the chips ,and the usb connection doesnt seem to be set up to upgrade all  in one go .
It would seem if Feeltech want their customers to remain loyal and not leave them with a paper weight and a bunch of negative press they need to at very least offer people some viable alternative to shipping it back to factory at their own cost.
If Feeltech guys  are steadfastly refusing to offer online updates ,then really they need to start sending out replacement boards to those who can show documentary evidence of these faults free of charge ,really if they just bit the bullet and sent out brand new boxes to its customers who were affected they could probably reverse all the reputational damage that has occured already . Ive just emailed the vendor for the third time asking what software revision the machine they are send me is .this time I reminded him that he simply needs to power up one of the units to check which FW revision its at .For the money Fy6600 is hard to beat in terms of functionality ,if feeltech can fix the issues there onto a winner for sure .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jleg on January 17, 2018, 03:32:57 pm
So it seems indeed V3.1 is not safe, but it is repairable.
i would not call this "repairable". It just fixes the issue "for the moment". The next moment, it is gone again. At least this is what i observe with this "repair".
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CustomEngineerer on January 17, 2018, 04:42:48 pm
It would seem if Feeltech want their customers to remain loyal and not leave them with a paper weight and a bunch of negative press they need to at very least offer people some viable alternative to shipping it back to factory at their own cost.

It would seem that way, but people just keep giving Feeltech their money despite all the negative press that's already out there. Feeltech has made it clear they don't care.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 17, 2018, 09:46:04 pm
Hello everybody, here are some preliminary news on the protocol decoding stuff (btw, the stored sine waves have been repaired):

- The control message that the FP sends seem to be the FULL configuration, that is, the frequency, amplitude and whatever is send for the both channels and the FPGA reconfigures fully.
- The numerical information (at least for the frequency and amplitude) seem to be organized into 48bit !!! numbers ( 3x16bit), there are at least 32 of this 48bit parameters that are send.
- I've managed to identify the frequency slot, it does increase with this stupid mHz increment, and the number reflects the display.
I'm so curios what is happening  if somebody forces a value larger than 60MHz on the slot, especially on the 30MHz units !!!
- I've managed to identify the amplitude slot, this somehow varies monotonic with the display, but there on 1 to 1 correspondence, seem to be some quanta, even values from a table, to be investigated.
- I've managed to quickly reach the limits of the Intronix logic analyzer, to get somehow reliable and repeatable measurements at 18MHz clock, I need to sample at 50MHz and the little buffer fills quickly, even with compression active. the software on the other side was so cool, it took me like 5 seconds change the SPI protocol interpreter from 8 bits to 16bits. I really hope that the owner of the LogicPort IP will produce an updated variant or at least open-source it, because I really like it.
- To continue work I need to use the LA advanced features, like repeated condition trigger, to skip groups of 3 SPI transfers, but that means doing single acquisitions instead of looping and comparing values, and this pisses me off.
!!! WANTED !!! Kind Soul  to Lease a Logic Analyzer  with a RELIABLE sampling mode (3V3 levels) of at least 50MHz (100MHz preferable, not every Chinese firma is Intronix) on at least 4 channels (I need an extra for the extra chip select, to see where this long string of words are going, remember we have 2 chip selects!!!) and yuuuuge buffer, at least 4Msample without compression, there is a large interval in between transfers compared with the actual transfer time of 3 words, and if the LA is of naive design it really needs a large buffer.   

Hopefully I'll be soon able to get the control message, without a powerful LA will be painful, but it's doable.

Humanitarian appeal: Dear gentle beings that lurks on this thread, I know that some of you have these cool scopes with LA and/or preformant LAs, kindly please try to reproduce my measurements, the connector is gigantic at today's standard and there is no pain in hooking the LA, 5 pins with plastic balls it's all that is needed for the grabbers to have a grabbing point ;).
If you don't want, at least some encouraging words will be appreciated  ^-^.

I'm posting some pictures with my setup to encourage you to contribute  :-DMM

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 17, 2018, 10:33:14 pm
Hello everybody, here are some preliminary news on the protocol decoding stuff (btw, the stored sine waves have been repaired):
I assume with PC software menu option?

Quote
- The control message that the FP sends seem to be the FULL configuration, that is, the frequency, amplitude and whatever is send for the both channels and the FPGA reconfigures fully.
If it sends the entire config, does that mean the entire waveform gets reset? It seems not. At least not if I change the amplitude (easy to trigger on) on channel A, channel B runs without any discontinuity, and even channel A only changes amplitude while its phase runs continuously.

Image 1: 10KHz + 11KHz and jumping from 4V to 5V
Note: if you change from 5V to 6V, channel A disappears for 4ms due to a relay clicking over

Image 2: same with 1MHz and 1.1MHz
Note that it actually takes 15usec or so for the amplitude to actually rise

That most likely means that the waveform is not reset as the FPGA continues to tick down the waveform samples.
So likely you can expect the same control set for all settings, except when you change the waveform, that will have its own completely distinct control set.

Quote
WANTED !!! Kind Soul  to Lease a Logic Analyzer  with a RELIABLE sampling mode (3V3 levels) of at least 50MHz (100MHz preferable, not every Chinese firma is Intronix) on at least 4 channels.
I assume you mean 'loan'? Sorry, I only have a 20MS/s 256KB Scanalogic-2 (IKALogic)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 17, 2018, 11:06:29 pm
I have a MICSIG 1104 on the way (been in this country for 3 days without moving  >:( ) It should be able to cope with the specs you mention and has built in bus decoding installed. Mine is the 30MhZ Signal generator too.

Bus decoding/sniffing isn't my thing but I will try anything 'once'  ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 18, 2018, 01:25:23 am
I guess to some extent we all knew what we were getting into buying one of these units ,
Its one of those too good to be true type deals ,but having said that ,for the money involved,for me its worth the risk, I can do all of the upgrades component  wise myself for next to nothing .
Maybe a simple survey in here involving owners of the FY6600 and we could get some stats on the failure rates ,something which Dr Feeltech knows only too well at this stage Id imagine.
Im afraid Im not much use on the programming front ,I can certainly follow instruction on how to flash something but beyond that ,programming isnt my thing .
Analog audio is my main focus,specifically valve/tube gear, the 1's and 0's I dont bother so much with as long as what I put in comes back out cleanly at the other side .

Incidently I went to my electronics recycling point yesterday with a few odds and ends to get rid of ,I took a Technomate sat box back from the heap with me and found a very suitable replacement psu for anything small requireing +3.3+5+12-12 volts inside ,each of the rails has proper CLC filters at the outputs ,something a lot of manufacturers penny pinch over.

Im sceptical of switchmodes because over the years Iv seen some very bizzare behaviour when different units which rely on switcher psu's share a common ground.Once on a live recording session I had a bass player turn up with a Genz Benz ,lightweight 500w amp ,it had an xlr out which I took a connection from to my hardisk recorder/mixer. The amp for what ever reason simply stopped working completely until the signal connection was broken ,accompanied with a mini melt down on behalf of the bass player . Anyway just went back to old fashioned active DI box directly from the bass and everything worked great again , a real ghost in the machine type experience for the amp owner though. Another time I re-jigged a vintage radio cabinet into a modern unit with a switching amp pulled from my fostex PM.03's , it works fine with most sources ,but pair it to a dab radio and the interaction/interference from the two switchmodes makes the whole set up unusable ,a mix of 50/100hz hum and spikey rf voltages are all that come through the speakers ,with very carefull routing of the wiring from the supplies it can work but its well beyond the average persons ability to understand . Id be interested if anyone else has experienced similar weirdness when multiple switchers interact via ground and crap gets induced into your audio wires .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 18, 2018, 02:25:06 am
Forum survey in this case would only reveal a Negative view. We are most likely a few percent of their sales at best and it seems that most have found their way here to improve weaknesses or try and revive dead ones.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 18, 2018, 04:38:01 am
I just happened to click on the ebay link that was left by the person who started this post ,
Ironically it says that this sale has been removed by the seller because the item was lost or broken .

You could be right Bean ,maybe a post called 'Feeltech FY6600 Complaints department' for everyone who's been stung might make Dr Feeltech sit up and take notice , aside from a few youtube vids and sellers of the item, google search sends people straight here and it seems to be the only serious blog out there on this particular machine, that gives us a bit of leverage .
Maybe a new topic page where everyone who got a dud FY6600 machine goes and puts the name of the ebay seller, FW version ,and a short description of the fault,nice an simple   ,
Id say it wouldnt take long for Mr Feeltech to hearback from his retailers   :rant:
And that might be enough to change his mind on doing right by the people who were dissapointed , the softly softly approach has been tried, time to up the ante Id say .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 18, 2018, 07:47:36 am
Quick before going out:
@cybermaus all the measurements were done with the default sine wave on, no custom waveform, too bad about your LA, yes, I wanted to say lease not loan, aber wir schaffen das :).

@beanflying the LA is cool, there is nothing über-hackerish to do, just connect it to the data cable, and write down what get's send when some commands are done. If the LA has a protocol decoder, then there are just a number of values to be jotted down, this will actually be really helpful to be able to compare two separate units.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 18, 2018, 08:25:16 am
Not entirely sure but I think the MICSIG can take videos of the screen  ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 18, 2018, 09:15:09 pm
I had been wondering about a question that has arrisen a few times on the thread ,but their didnt seem to be a straight answer to ,
What exactly is the difference between the 15/30/45/60 mhz models , have the upper models the different opp amps on the output stage ,or different power supply ,is there a different software on the higher frequency models or other different hardware modifications ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 19, 2018, 04:07:56 am
Just an introduction today. Feeltech meet MICSIG hardware and software from Shenzen that works  >:D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 19, 2018, 04:50:38 am
It seems to me that reviewing the other similar units would be more useful for others.  I rather doubt that FeelTech will continue in the T&M business.

It seems to me that the only way to get any kind of warranty out of FeelTech is to order a replacement  from a seller with low cost return shipping. swap the bad board and return for a refund.   However,  a string of V 3.0 or 3.1 units would make even that unattractive.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 19, 2018, 06:56:49 pm
OK gentlemen, the WE is starting and so is the sniffing session.
One thing is for sure, for one click of the encoder in the frequency change mode exactly 17 x 48bit values are send form the FP to the SB.
The frequency value is only linear up to some value, afterwards it become a little strange.
The Intronix LA is really superb, but I've hit as well the limit in the sample memory, what a real pity that the designer got some personality disorder and doesn't want a redesign for a larger sample memory, I will definitely pay for an updated version.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bsudbrink on January 19, 2018, 07:29:49 pm
Last year, when I decided to by an FY6600, there was a competitor, the JDS6600.  Part of my decision was based on the fact that more people around here seemed more enthusiastic about the FY6600.  I figured, more hacks, more fun.  Thing is, I don't seem to see any further discussion of the JDS6600 past last November.  Does anyone have both?  Does the JDS have similar issues to the FY?  Could the JDS give any clues on how to "get into" the FY?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 19, 2018, 08:26:59 pm
The software with the Jds does look better than what comes with the FY6600, maybe its worth trying it out to see if it functions with the Feeltech as well .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 20, 2018, 12:55:09 am
Unfortunately, there was just enough information to make a bad decision.  I'm considering ordering  either a JDS or Koolertronic unit as a replacement if DC1MC doesn't  manage to document the bus  protocol to the point I can reprogram the FeelTech. Of course, he should return the V 3.1 unit he received as defective and repeat the process until he gets a unit that doesn't crap on itself.

I was visiting my sister in CA and  just got home.  I'm still trying to to get back up to speed with what I was doing when I left.   The migration of my Solaris 10 system from 1 TB to 2 TB disks for the ZFS arrays is almost complete.  So the big project still in progress is the T&M restack.  I've also got to source a distribution  amplifier and set up my Leo Bodnar GPSDO to feed the other instruments.  Which probably won't happen for a day or two as the 40 nS rise time pulse generator is much more interesting. Many years ago I tried to build such a thing and got my head handed to me on a platter.  I plan on a rematch.  I don't intend to try to beat Leo. Just meet my original 900 pS risetime goal set by the Tek 465 cal procedures.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 20, 2018, 01:03:59 am
Aside from the software related issues that some have experienced ,the extra features on the FY6600 like sync input ,and the ability to modulate one signal with another just make the FY a better more versatile piece of kit , fingers crossed  the 'Feelers' guys have got their sh1t together with the software glitches now too ,my unit is on the slow boat from China as we speak ,still no response from the seller about which FW version Im getting either , worst comes to worst and they try and pawn me off an older firmware revision I'll most likely shed the load and tell the courier to return it from whence it came. Hopefully  Feeltech have recalled the funky units with FW 3.0 and 3.1 from their retailers at this stage.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 20, 2018, 01:14:44 am
I was told I had a "lifetime" warranty.  FT does not even reply now nor does the seller. sportgogo.  I'm about to start the agony of making formal complaints to eBay and Paypal.

I think that "justice" would be open source FW.  Make it *really* easy to launch a competing product.  Let's face it, there's not a lot to the UI software.  I strongly suspect that the issues result from a demented attitude about "intellectual property".
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 20, 2018, 02:27:17 am
I guess we have to clap ourself on the back here in the west ,Im not sure if the concept of intellectual property even existed in China uptill modern times .
Maybe its not just as simple as upgrading the firmware in one go via usb like with most equipment ,maybe the process is fiddly and way to awkward for a non technical person to do .

Thats a real shame they have left you in the lurch RHB, at least you have plenty of documentary evidence from this post to back up your side of the story . I hope you get some satisfaction ,maybe if enough complaints are lodged, Ebay will contact the Feeltech in person for an explanation , at the end of the day the seller is only the middle man and has no control over the quality ,the person who ends up taking the lumps when things go wrong are the actual employees of the seller ,theres a lack of acountabillity from the people raking in the big money ,but isnt that the way all over .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 20, 2018, 07:21:17 am
My opinion of the JDS is it is a rip off of the basic Feeltech unit but they also too some shortcuts and cost savings using a resistor ladder instead of a proper DAC

Just finished a 14 hours day on my feet with another few to clean up yet. Monday/Tuesday I will crack the lid on mine and have a play with the new scope.   :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 20, 2018, 09:14:11 am
Dear forum members, I'm glad to announce the first official results of the FY6600 bus sniffing.

General considerations:
Pinout you can see it on the page 17 of this thread, signal level is 3V3 logic.
The data is transfered form the FP (front panel) to the SB (signal board) and back via 16bit word SPI transfers with an 18MHz clock, MSBit first.
Logically we are talking about a number of 32bit registers, in big-endian format, and one MOSI transfer consists of 16bit register address (so far observed addresses are less than 0x20, but the night is young), followed by the MSW and LSW .

Frequency registers general note:
- There are two 32 bit consecutive address registers for each channel, one holds the frequency in increments of 0.1Hz and the other one the centi-Hz and beyond, going to 0.099999Hz. On my 60MHz unit it goes to the max value and any further attempts to increase the frequency programs the same value. Values are 1to1 linear, no offsets or table lookup found.
The full control message programs 20 x 32bit registers, the register for CH1 are number 9 and 10 in the control message and for CH2 are 11 and 12 (these are positions in the 20 transfers control message starting from 1, NOT the actual register addresses !!!). Order is MSW then LSW, don't know if it matters.
- Frequency setting register addresses:
  CH1 MSW 0x02, LSW 0x01
  CH2 MSW 0x04, LSW 0x03


 >:D note: Is the freq limit hardcoded in the FP (bypassed by a new firmware or MCU), in the SB (bypassed by copying the SB flash) or in the components used (bypassed by soldering the right ones) ?

Next to come: Amplitude

Bonus, for amateur detectives: a Full sine frequency setting message, amplitude is set to 5.0000V, offset 0.00000, duty cycle 50%, phase shift 0.00000.

  8) First prize: The finder of one or the rest registers for setting the amplitude , phase and duty cycle, using just this provided sample.
 :-+ Second prize: The finder of current frequency settings by using the information I've provided.
 >:D Third prize: There is no third prize !!!

Sample (A.M.L):
1D.0000.0002
24.0000.0010
2B.0000.07FF
2C.0000.07FF
06.0000.00C0
06.0000.00C0
2D.0000.0E65
2E.0000.0E65
02.0BEE.32EF
01.0000.AB5C
04.0001.86A0
03.0000.0000
2F.0001.0000
30.0001.0000
05.0000.0000
38.07FF.DFFF
39.07FF.DFFF
08.000F.FFFF
09.000F.FFFF
37.0000.0000


Now  :box:

DC1MC





   

CH
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 20, 2018, 10:25:32 am
The unmodified 10KHz of channel B is easy.
The 20.015.998.343.868 uHz on Channel A is also not too hard, but a bit of a random number though.

But is a quiz really the right format to bring us new knowledge. Even if you are in teacher-testing mode, didactically the number set should have been one not obvious from the quiz, but once decoded reward the student with a good feeling. Like 02.075B.CD15 01.0000.04D2 would have. or if thats too obvious, maybe 02.075B.CD08 01.0000.D431

As to the others. Likely this:
The 50% ones are obviously one of the 7FF... values, do not even need a calculator for that. But offset is also a 50% value (0 being the middle)
Of course there are multiple candidates, depending on the resolution I would go for 07FF.DFFF, (not sure about the D) and 0000.07FF for offset.
Phase shift would be one of the 0000 values.


HOWEVER:

If for some technical reason, it was easier to build the FPGA blocks like that, they could just as easily use the 0001.0000 values as a hex 50%, and therefore a full scale would be 0000.0000 to 0001.FFFF to map out the offset. Or the duty cycle.

Or they could use proper binary values, with x0000 being 0, and negative offsets as signed binary, like 0FFFF for -0.001V and x7FFF being the maximum rather then the middle


You see, you are not really playing nice. You had multiple samples, saw what changed when, and know the answers. But now you make the questions as if your answers are the only possible ones, but without extra info, there are multiple solutions.


Anyway, more seriously:
 
>:D note: Is the freq limit hardcoded in the FP (bypassed by a new firmware or MCU), in the SB (bypassed by copying the SB flash) or in the components used (bypassed by soldering the right ones) ?

I would argue (but am not absolutely certain):
- Hardware differences are unlikely due to production cost, cost of keeping multiple stock.
- FPGA is unlikely as it is not protected
- CPU is likely, and in fact the reason why they do not distribute the firmware, even more then them worrying about IP

We can prove the FPGA is not it if someone with a 30MHz V3.1 reads the Winbond, so I can compare with my 60MHz V3.1
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 20, 2018, 10:40:36 am
Oh cybermaus, you hurt me  :P, this is my first capture with the LA, I even forgot what was the idea, prolly to generate a binary pattern of 0x123456789ab.
Besides this I have no clue what other parameter are formated and in which addresses are stored, I'll get them after returning from shopping, now that the other Saturday chores are done.
Parameter settings are easy, but when you press F1 repeatedly, it rereads stuff from the FPGA, I'm really curious what is there.
And of course, Sysinfo decoding it will be interesting.
It really sucks that nobody wants to hook an LA to its unit as well :(, but I will do whatever captures are needed or suggested.
But first parameter settings must be fully determined.
Now Accepting Ideas about some wave forms  to determine the waveform loading procedure!!!

Cheers,
DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 20, 2018, 11:07:57 am
Sorry, I did not mean to curb your enthusiasm

Possibly I misinterpreted whether you were quizzing for the duty/offset/phase or did not know yet and was asked us.
But that misunderstanding is then also due to the bringing us the frequency as a quiz. As I said, I do not think quizzing is the way to go here.

The reason I am not LA' ing is multiple:

- I spend a lot of time  learning the STM32 and its features on a blue-pill with the hope of reading it. And I have at this moment confirmed that all the security measures described in the reference manual are in place and working. Many ideas to hack around it came and went out the door again. No closer to reading the FB, but I did spend my time.

- Reading the protocol is interesting, and I am not against puzzles, but it would be only half the work. After that there is also the grinding work of reprogramming another device as UI. Maybe said stm32 blue-pill, but a lot of extra work, and we are bound to also make bugs, like feeltech.

- as stated, my LA is a bit sub-par.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 20, 2018, 02:55:27 pm
Back from shopping in the most miserable goth-mannheimisch weather evar :(.
So cybermaus, about the the security measures, can you detail, is the MCU closed on level 1 (doable) or on level 2 (not doable) ?
Also there was another kind soul that said he'll work on the FP schematic, any results yet, after the protocol is done I intend to do a Fraunhoffer on the FP, but not before.
In the end, the STM is providing really cool libraries for graphical LCD any many other goodies, it's doable with a bit elbow grease.
Now, enough talkin and more analyzing, up next, output voltage, phase and offset.
DC1MC

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 20, 2018, 04:16:12 pm
- Reading the protocol is interesting, and I am not against puzzles, but it would be only half the work. After that there is also the grinding work of reprogramming another device as UI. Maybe said stm32 blue-pill, but a lot of extra work, and we are bound to also make bugs, like feeltech.

I'm ready to start testing using another device as soon as I have a description of the bus protocol.  I plan to start by using Mecrisp to control the AWG board from a terminal window.  I have an ample supply of dev boards, etc.  This has the major advantage that exhaustive protocol testing is trivially scripted.

I've written thousands of lines of software professionally that were in service for almost 20 years with NO user reported bugs.  This included FORTRAN initializing a function pointer table in C that called FORTRAN routines to populate FORTRAN structures, so not trivial code either.  I realize that is unusual, but it shouldn't be.

@DC1MC Please start a new thread, "FeelTech FY-6600 Firmware Recovery"  in the "Repair" group and put all the information you have  collected in the first post, updated as we collect more information.  That will make it much easier to find out the current status of work.  We should keep the discussion here so as not to clutter up the technical documentation.

I'm still a few days from completing a major workspace  reorganization, but should be in full swing by next weekend at which point I'll start verifying the accumulated documentation. At least in theory I should be able to automate verification using the MSO2204EA features to verify the AWG output for all the bus commands.  It will be an interesting test of the Instek SCPI implementation.

[Edit]  I just saw this.  Never heard of the package, but obviously highly relevant.

https://www.eevblog.com/forum/microcontrollers/truestudio-v9-released-100-free-but-only-for-stm32/?topicseen (https://www.eevblog.com/forum/microcontrollers/truestudio-v9-released-100-free-but-only-for-stm32/?topicseen)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on January 20, 2018, 06:13:33 pm
Perhaps just a general repair thread outlining what steps are necessary to make the power supply safe, ground the device, give it a proper reference, and fix the UI display would be good. Put it all in one place!

Also, my device is also on the slow boat from China, what kind of logistics analyzer is needed to accomplish what's left to do?

i.e. how many channels, what sample rate, and how much sample memory?

If something like this would work, I will spring the cash and join the effort:
https://m.ebay.com/itm/USB-Logic-Analyzer-16CH-100MHz-4CH-400MHz-Base-on-Xilinx-Spartan-6-FPGA-in-US/162474227153?hash=item25d437f5d1:g:3NAAAOSwjyxZcVTv
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 20, 2018, 06:26:07 pm
So cybermaus, about the the security measures, can you detail, is the MCU closed on level 1 (doable) or on level 2 (not doable) ?

Short answer: it has RDP1

Longer answer: RDP1 and RDP2 does not exist on the STM32F103C8. Not exact.

You see, the Frauenhofer document is specifically for the STM32F0xx series, which is slightly newer, and indeed have an extra protection option. And because there are 3 protection levels, they call it 0, 1, 2. The older STM32F1xx devices only have RDP, or no RDP (on or off, if you will). No mention of levels anywhere in the document.
But functionally, RDP on is similar to RDP level 1.

That also means that the exact cold-boot race condition that Frauenhofer described, may or may not work.
It is a different device, with a specific implementation change in this specific part of the chip. The flaw was likely also already there in the older series, but we cannot be sure.

I am actually studying the Frauenhofer document at the moment, not merely skimming it an looking at the video, but trying to read and understand every word of it.
But to be honest: Don't hold your breath, I have other stuff to do too.




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 20, 2018, 09:07:25 pm
Hello again, after a short nap to rest these old eyes, here are some quick answers to the messages until now and some new findings, aka "level control is a new level of...":

@cybermaus: Thanks for clarifying the RDP situation with the FP MCU, I downloaded the code form the Fraunhoffer project, once I have the protocol figured out (in case the firmware/FP dies at least I can control the SB via something else). I wish you'll find some time to contribute further to our little project, but thanks again for all your previous work, it was an inspiration.

@rhb: Your offer to do a detailed and formal protocol testing is wonderful, we need this and we desperately need at least one person with another AWG to do some investigation, as far as I was able to see until now, there are no "secret sauce" calibration values stored somewhere, the firmware trusts the SB to do its stuff, for example, I didn't see so far any difference in setting the amplitude for the channels in the actual firmware, but with your help we can really devise a calibration procedure for the device. Also thanks for the advanced debugger package info, it will come handy later. Finally, I will continue this thread for a while and tomorrow I will start  a new one as suggested.

@SMB784: I will offer some of my findings to kick start your stuff, some are fact(F) and some are anecdotal (A, personal experience):
 - F: As the SPI interface clock is 18MHz, you need an LA that can work reliably at least 100MHz in sample mode.
 - F: The absolute minimum number of channels is 3: CS, CLK and MISO or MOSI, better is 4 (to see simultaneously both data pins) and best is 6, because we have some other signals (an assumed extra CS to select another device, and a "mystery" signal, not determined yet).
 - F: The logic levels are 3V3, single ended, ALL the LA in the world should be able to cope with this.
 - F: The LA has to have some on device memory, either large or with RLL or other compression method, we have some kind of trifecta thing, the data it's very fast when is coming,  but come in widely spaced bursts, and a "naive" LA that once triggered, keeps on sampling, it will need to have a real large sample buffer.
 - F: To add to the sample buffer size, I still have to see how the waveform loading goes over the SPI bus, it could be that my Intronix is insufficient for this.
 - F: The LA should be able to have a reliable 16bit, MSBit first, protocol decoder, or it's useless.
 - A: Personally I use an Intronix LogicPort (one right now on fleabay, https://www.ebay.de/itm/INTRONIX-Logicport-34-Channel-Logic-Analyzer/192427289565 (https://www.ebay.de/itm/INTRONIX-Logicport-34-Channel-Logic-Analyzer/192427289565) ),  and they are still sold, while dated, it does the job (praise benevolent Fraser that offered one at a good price), it has RLL compression and some minuscule sample memory, so while the data can come as it wants, the few Kbits of sample buffer it fills up pretty fast and game over. Buuuut, if one is not lazy and expects the whole control msg in one shot, he can increase the number of trigger condition (CS going down) repetitions and position directly on the needed value or do a multi-segment acquisition. So far it proved to be OK, but I'm shopping for another LA, eventually with USB3 interface, and definitely with a large on device sample memory.
It's a tragedy that the Intronix guy got some kind of brain fart and totally refuses to update the design, he's a very pleasant and helpful person to talk with, UNTIL the design update subject comes :(.
 - A: I was also looking at the DS Xilinx whatever clones, it doesn't seem to have RLL compression implemented, and if so, even with the 256KBits sample memory, it's useless. In streaming mode is definitely useless. But of course, I can only use the seller provided information, that is some distorted chinglish and on 10 similar looking devices you've got 10 different descriptions, they are throwing whatever shit and see which of it sticks on the wall and sells more. And most likely the software is nicely done and a pleasure to work with  >:D.

I have lowered my LA standards as low as possible, but even so, finding a device that has the same features as the Intronix and a bit of extra buffer space under 1000EUR it's just not possible, Chinese or not. And btw, fuck those SA--äE sales drones with a rotating cactus, it took me half an hour with their miserable support software AI or cognitively challenged salesoid to confirm that the latest and grates expensive POS still doesn't have on device memory and doesn't do any RLL compression on acquisition and "it uses the PC memory". Sigh.

As this post has become too long, I will post the amplitude registers and description in my next post (that one will be also long, but with nuuuumeeeers :)

 Cheers,
 DC1MC



 if it's one of these devices that are just some Cypress USB interfaces with some analog front end,


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 20, 2018, 09:31:15 pm
... I downloaded the code form the Fraunhoffer project....

What? Where?
I was under the impression they did not publish the code.

edit: never mind. got it.

Also this is my analysis of the Frauenhofer paper (bad news):

- Cold-Boot SRAM attack: This assumes the bootloader first does a firmware CRC check, so every flash byte passes through the SRAM in an ordered and well-timed fashion. And I think our devices do not do a CRC check. Otherwise, how could they boot up with corrupted firmware

- SWD race attack: Quote: "experiments on a few samples indicate, that other series might not be vulnerable"
Translation: they tried it already on a STM32F1 and could not get it to work (in other places they also refer to F1 by name as "other series")

I am probably going to try anyway...

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on January 20, 2018, 10:08:13 pm
- A: I was also looking at the DS Xilinx whatever clones, it doesn't seem to have RLL compression implemented, and if so, even with the 256KBits sample memory, it's useless. In streaming mode is definitely useless. But of course, I can only use the seller provided information, that is some distorted chinglish and on 10 similar looking devices you've got 10 different descriptions, they are throwing whatever shit and see which of it sticks on the wall and sells more. And most likely the software is nicely done and a pleasure to work with  >:D.

Would it matter if the device has 256 MBits of onboard storage memory, like this one? (https://www.ebay.com/itm/USB-Logic-DSLogic-Analyzer-16Ch-100MHz-4Ch-400MHz-Xilinx-Spartan-6-FPGA/182687940922?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D49899%26meid%3D7312b39552504dc08178c8d5d2f784b7%26pid%3D100890%26rk%3D1%26rkt%3D12%26sd%3D162474227153&_trksid=p2056116.c100890.m2460)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 20, 2018, 11:03:07 pm
- A: I was also looking at the DS Xilinx whatever clones, it doesn't seem to have RLL compression implemented, and if so, even with the 256KBits sample memory, it's useless. In streaming mode is definitely useless. But of course, I can only use the seller provided information, that is some distorted chinglish and on 10 similar looking devices you've got 10 different descriptions, they are throwing whatever shit and see which of it sticks on the wall and sells more. And most likely the software is nicely done and a pleasure to work with  >:D.

Would it matter if the device has 256 MBits of onboard storage memory, like this one? (https://www.ebay.com/itm/USB-Logic-DSLogic-Analyzer-16Ch-100MHz-4Ch-400MHz-Xilinx-Spartan-6-FPGA/182687940922?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D49899%26meid%3D7312b39552504dc08178c8d5d2f784b7%26pid%3D100890%26rk%3D1%26rkt%3D12%26sd%3D162474227153&_trksid=p2056116.c100890.m2460)

Not really 256MBits, the description says:
"DSLogic basic version Specifications:

- Hardware storage:256Kbits"
The ony one that comes close to what I want is/was USBee QX, but they are gone now :(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 21, 2018, 12:02:06 am
And now the log awaited amplitude settings:

General Notes:
Register addresses:
 CH1 - 0x2D
 CH2 - 0x2E

Range of digital values, both channels, no difference, no channel specific values:
 0x0000..0x0E65 (?!?!)

Ranges and corresponding relay bits in register 0x06 (NOTE the firmware has a naive way to set the register 6, it does one write for CH1 followed by another write with CH2 bits added, Bits 7to4 are undetermined yet):
 CH1 - 0.0000 to  0.5000V ( Bit 3 = 0, Bit 2 = 1 )
 CH1 - 0.5001 to  5.0000V ( Bit 3 = 0, Bit 2 = 0)
 CH1 - 5.0001 to 20.0000V ( Bit 3 = 1, Bit 2 = 0 )
 CH2 - 0.0000 to  0.5000V ( Bit 1 = 0, Bit 0 = 1 )
 CH2 - 0.5001 to  5.0000V ( Bit 1 = 0, Bit 0 = 0 )
 CH2 - 5.0001 to 20.0000V (Bit 1 = 1, Bit 0 = 0 )

Long list of panel value and actual digital representations over the SPI, there is clearly either a formula or some kind of calculations done, one can see some arithmetic rounding issues, the values are identical for the both channels for the same amplitude value, the new fw will benefit of some calibration tables.

0.0000V - 0000
0.0003V - 0001
0.0004V - 0002
0.0005V - 0003
0.0007V - 0004
0.0008V - 0005
0.0009V - 0006
0.0010V - 0007
0.0020V - 000E
0.0030V - 0031
0.1000V - 02E1
0.2000V - 05C2
0.3000V - 08A3
0.4000V - 0B84
0.5000V - 0E65
=== KLAK ===
0.5001V - 0170
0.5007V - 0171
0.5031V - 0172
0.5043V - 0173
0.5055V - 0174
0.5068V - 0175
...
0.5100V - 0177
0.5200V - 017E
0.5500V - 0195
0.6000V - 01B9
0.7000V - 0203
0.8000V - 024D
0.9000V - 0297
1.0000V - 02E1
1.1000V - 03A2
2.0000V - 05C2
3.0000V - 08A3
4.0000V - 0B84
5.0000V - 0E65
=== KLAK ===
5.0001V - 0399
5.0037V - 039A
5.0098V - 039B
5.0147V - 039C
5.0208V - 039D
...
5.0500V - 03A2
5.1000V - 03AB
5.2000V - 03BE
5.5000V - 03F5
6.0000V - 0451
6.5000V - 04AD
7.0000V - 0509
7.5000V - 0565
8.0000V - 05C2
8.5000V - 061E
9.0000V - 067A
9.5000V - 06D6
9.9963V - 0731
10.000V - 0732
10.0025V - 0733
10.500V - 078E
11.000V - 07EB
11.500V - 0847
12.000V - 08A3
...
19.000V - 0DAD
19.500V - 0E09
19.9971V - 0E64
20.0000V - 0E65
=== BEEEP ===

For short time taking requests for special voltage values and thankfully accepts nice plots and graphs.

WANTED: DIGITAL SECRETARY TO MAKE A NICE SUMMARY DOCUMENT, EXPORTABLE TO PDF

Tomorrow, offset and phase, time permitting.

 DC1MC


10.500V - 0
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 21, 2018, 12:19:18 am
There are 17 switches and an optical encoder on the FP.  Would someone with a functioning (V 3.2+) unit document the state machine?  Most of the switches just select which input parameter is controlled by the optical encoder and the LCD panel switches.  It would also be helpful to know more about the RS-232 port and the LCD display.  That will let me start designing new FW.

I don't think it is worth spending much time on the FT FW aside from pure entertainment of trying the Fraunhofer attack.

I got my test monitor mounted to the wall, so I should be able to cable most of the bench tomorrow.  Then I'll install programming  pins and make an LA probing cable.  I've got an STM32F429 Discovery board, so I'll probably use that for the initial FW dev work as it has lots more resources and I know I can reprogram it.

I'm not clear on the "registers" DC1MC mentions.  Are these in the FPGA or the STM32?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 21, 2018, 12:34:26 am
There are 17 switches and an optical encoder on the FP.  Would someone with a functioning (V 3.2+) unit document the state machine?  Most of the switches just select which input parameter is controlled by the optical encoder and the LCD panel switches.  It would also be helpful to know more about the RS-232 port and the LCD display.  That will let me start designing new FW.

I don't think it is worth spending much time on the FT FW aside from pure entertainment of trying the Fraunhofer attack.

I got my test monitor mounted to the wall, so I should be able to cable most of the bench tomorrow.  Then I'll install programming  pins and make an LA probing cable.  I've got an STM32F429 Discovery board, so I'll probably use that for the initial FW dev work as it has lots more resources and I know I can reprogram it.

I'm not clear on the "registers" DC1MC mentions.  Are these in the FPGA or the STM32?

Cool, more hand and eyes needed.
Usually this the name for things implemented in the FPGA that are addressable, they are called registers.
We have an SPI interface and a number of these 32bit  registers in the FPGA, each with their own address (so far less than 8bits address space).
The registers that I've documented are in the FPGA and loaded/read via the SPI interface with 3 x 16bit word SPI transfers, first is the address (A), then the most significant bits in big-endian format(M) and the least significant bits (L) in the last transfer.
To start the new FW programming on the old FP we need the schematic, one member promised to work on it, but I didn't hear form him recently, if you want to use your own board then you need just an SPI interface to the signal board and 2 I/O pins for secondary functions, for start they can be skipped and  just use a 4 wire SPI.

Out of the registers block I have fully documented: 0x01,0x02,0x03,0x04,0x2D,0x2E and some bits in 0x06.
As functions we have now full control of the frequency and amplitude on sinus wave.
I've also posted a full configuration packet, that sets 20 registers at a time, for sine wave settings.
Tomorrow I will try to document phase and offset registers as well for the sine wave and channel enable bits (I have a hunch that they are also in register 6).

 Any questions welcome.

 Cheers,
 DC1MC

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 21, 2018, 01:11:29 am
Here is a plot of the "register" value vs voltage that DC1MC posted with the values converted from base 16 to base 10.

We really need for someone with a V3.2+ unit to verify that the voltage-register relationship is not borked.  I'll split off ranges and plot to check for calibration effects.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on January 21, 2018, 01:21:22 am
If my unit that arrives sometime next week is v3.2+, I will attempt to verify that. What is the necessary procedure for doing that?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 21, 2018, 01:31:46 am
Here is a plot of the deviation from a linear fit of voltage and register value based on my recollection that the DAC is 12 bit for the range from 5-20 V.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 21, 2018, 01:39:10 am
[
I've also posted a full configuration packet, that sets 20 registers at a time, for sine wave settings.


Where?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 21, 2018, 08:23:07 am
Reply #532 has a complete control message, the things there now are starting to make more sense, and if we have the phase and amplitude registers today, it will be even more clear.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 21, 2018, 12:47:41 pm
Hello everybody, some more registers have meaning now:

Phase shift:

 CH1 - Reg. 0x08
 CH2 - Reg. 0x09

Phase shift range:
 0x00002..0xFFFFF

Phase shift interesting values (sine waveform):
 000.000" - 0xFFFFF
 089.999" - 0xC0002
 090.000" - 0xBFFFF
 090.001" - 0xBFFFC
 179.999" - 0x80002
 180.000" - 0x7FFFF
 180.001" - 0x7FFFC
 399.999" - 0x00002

Offset:

 CH1 - Reg. 0x2B
 CH2 - Reg. 0x2C

Offset range:
 0x155..0xEA8 corresponding to -10.000V..+10.000V

NOTE: The relays activates according with the ranges described in the message dealing with Amplitude

Offset interesting values (sine wave 1.0000V amplitude)

 0.0000V - 0x07FF
-0.002V - 0x07FE
+0.003V - 0x0800

  As usual, taking requests for special values of interest, if any.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on January 21, 2018, 01:42:32 pm
Is the phase shift table above correct or am I misunderstanding what it is indicating? Is the symbol " meant to be ° for degrees and if so is the last entry meant to be 359.999° ?
-Arthur

Phase shift interesting values (sine waveform):
 000.000" - 0xFFFFF
 089.999" - 0xC0002
 090.000" - 0xBFFFF
 090.001" - 0xBFFFC
 179.999" - 0x80002
 180.000" - 0x7FFFF
 180.001" - 0x7FFFC
 399.999" - 0x00002
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 21, 2018, 02:07:43 pm
Is the phase shift table above correct or am I misunderstanding what it is indicating? Is the symbol " meant to be ° for degrees and if so is the last entry meant to be 359.999° ?
-Arthur

Phase shift interesting values (sine waveform):
 000.000" - 0xFFFFF
 089.999" - 0xC0002
 090.000" - 0xBFFFF
 090.001" - 0xBFFFC
 179.999" - 0x80002
 180.000" - 0x7FFFF
 180.001" - 0x7FFFC
 399.999" - 0x00002

On the left are the values of phase as indicated on the Front Panel, the " was used instead of whatever sign indicating degrees was used on the FP.
On the right are the digital numbers loaded in the corresponding state machine register in the Signal Board FPGA via the SPI interface, I try to be very careful and repeat the measurements a number of times before I post something, but of course, nobody's perfect, so if you spot any possible issue, I can redo the measurement.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 21, 2018, 04:35:28 pm
A few stray thoughts:

The memory corruption may be a HW design fault.  In particular, failure to hold the power good pin off long enough for the PSU to stabilize. Mine worked fine until I turned it on for the Nth time.  My understanding is that same scenario applies to the other failures.  so potentially another thing that needs to be fixed.

The units may need individual calibration to correct for DAC errors.  The extent of the memory corruption makes any existing calibration tables highly suspect.  Recalibrating with limited equipment is likely to be quite challenging.

I looked at a couple of YoutTube reviews , one with a teardown,  of the JDS6600 which uses a different FPGA and generates the output voltages from a 5 V input.  It also uses the STM32F103, but the UI board is different. Unfortunately, neither of the reviews checked the voltage on the BNC ground.



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 21, 2018, 04:44:48 pm
A few stray thoughts:

The memory corruption may be a HW design fault.  In particular, failure to hold the power good pin off long enough for the PSU to stabilize. Mine worked fine until I turned it on for the Nth time.  My understanding is that same scenario applies to the other failures.  so potentially another thing that needs to be fixed.

The units may need individual calibration to correct for DAC errors.  The extent of the memory corruption makes any existing calibration tables highly suspect.  Recalibrating with limited equipment is likely to be quite challenging.

I looked at a couple of YoutTube reviews , one with a teardown,  of the JDS6600 which uses a different FPGA and generates the output voltages from a 5 V input.  It also uses the STM32F103, but the UI board is different. Unfortunately, neither of the reviews checked the voltage on the BNC ground.

We need another unit to check, but it could be that there are NO calibration tables in the exiting fw, at lest for frequency, amplitude, phase and offset, that I've tested here. It could be that they measured once and determined the values and then left these trimmer resistors for tunning and that's it. The units will benefit for some individual calibration.
For the PSU they do offer a power-good pin that goes 0 when the power is there (it's a transistor with a resistor to base, of course, this one it's also not calibrated).

I hope that in the end I will produce enough data for the people that can't return their devices anymore and got more or less bricked, to be able to connect a blue pill board or something similar with an SPI interface to the SB and serial or USB to the outside and manage to control their board.
And for the people with better expectation to be able to aclibrate and control better their unit.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 21, 2018, 06:06:13 pm

We need another unit to check, but it could be that there are NO calibration tables in the exiting fw, at lest for frequency, amplitude, phase and offset, that I've tested here. It could be that they measured once and determined the values and then left these trimmer resistors for tunning and that's it. The units will benefit for some individual calibration.
For the PSU they do offer a power-good pin that goes 0 when the power is there (it's a transistor with a resistor to base, of course, this one it's also not calibrated).


The non-linearity of the amplitude-value pairs suggest that they put a lookup table in the STM32 which is populated during production test.  But that may be a "feature" that they don't actually use.

Can you measure the delay for the power-good pin?  I'm going to do that on mine as soon as I get the workbench rewired.  At the moment I have gear on new shelves, but no power yet.  I'm still severely outlet challenged. I need another 8-10 outlets, but haven't yet figured out where to put them.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on January 21, 2018, 06:13:43 pm
Hi!

I've got Mr. Tiong's books (both!) on PCB Reverse Engineering and I've started work on the schematic for the front–panel – I'm just laying–out the library symbols now before I draw out the schematic proper!

I'll draw up the Register Table once I've got a suitable copy of Office installed on my home lappy!

Chris Williams
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on January 21, 2018, 09:32:12 pm
DC1MC -"I try to be very careful and repeat the measurements a number of times before I post something, but of course, nobody's perfect, so if you spot any possible issue, I can redo the measurement."

Perhaps I wasn't clear enough in my previous post. I had two points of confusion, the " vs  ° I could see, but where the last left entry in the table was 399.999, which is over 360°, I was wondering if I was missing something. The last value you got on the right looks logical for 359.999°. None of the results are not being questioned, just that there was a wrong digit entered.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 22, 2018, 11:43:25 am
DC1MC -"I try to be very careful and repeat the measurements a number of times before I post something, but of course, nobody's perfect, so if you spot any possible issue, I can redo the measurement."

Perhaps I wasn't clear enough in my previous post. I had two points of confusion, the " vs  ° I could see, but where the last left entry in the table was 399.999, which is over 360°, I was wondering if I was missing something. The last value you got on the right looks logical for 359.999°. None of the results are not being questioned, just that there was a wrong digit entered.
True Arthur, this was a brainfart while transcribing :(, of course is 359.999
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 22, 2018, 03:10:35 pm
I had a look at the JDS6600 teardown too ,despite looking very similar outwardly to the FY6600 ,its a very much simpler unit inside in all respects .Sorry Im not much use at programming ,so very little I can contribute to the great work you guys are doing in that respect.
I will be replacing the psu on mine once it arrives , I'll solder in the new output Ic's too .
That theory about the psu management pin sounds promising ,and surely wont be a major problem to fix if it turns out to be the weak link .
I did notice on the spec sheet that the distortion on the outputs reaches something in the order of 0.8% @ 0dbm, I wonder if this is something inherent in the DDS methodology or can be improved with a better powersupply and upgraded op-amps.
A proper Rf sheilding cage around the switchmode might also help in this respect as well as extra LC filters before the rails hit the main pcb, I found a lot of small switch psu's have extra space for these components ,but all too often these spaces remain unpopulated ,to save a few pennies. Theres always something gratifying about turning a sows ear into a silk purse .
The abillity to open up the firmware and turn a 15mhz unit into a 60mhz would truly be the icing on the cake ,and might serve as a wake-up call to the 'Feelers' guys to start treating their customers right.

DC1MC , RHB, Arth and Chris56 , sincerest thanks for your for your efforts and hard work .


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 22, 2018, 08:12:39 pm
Hi Chris, welcome back after the hiatus, I'v thought that we've lost you   :'(, but now I hope you  :box: again. Soundtec, there is no programming so far, just some (bus) sniffing around, now and then please check this thread, who knows what nice things will pop.
My minimum goal is to bring the command decoding to the level where the signal board can be controlled with whatever thing has a SPI interface and 2-3 extra I/O, that means almost every fruit board and Arduino in the world.
Afterward I'll see if there is interest for more,  and of course participation from some other members.

I was trying to decode the channel on and off commands and along with the waveform change, they are way too much for Intronix, I can painfully log segments, but now it's clear that I need a better LA, with larger on device sample buffers and RLL compression.
I do kick myself that I didn't learn proper digital design, I was looking at all these affordable FPGA based ones, most of them have no sample compression (ACUTE up 600EUR, Digilent, others...) because they have a bit of memory on device and the rest have other strange design flaws, like this miserable and expensive junk that "uses PC memory" :(.
And I do have do ideas a proper USB 3 + FPGA LA design in a logic and pipelined way, but no way to implement them  :'( :'( :'(, even if I force mayself to start from almost scratch, getting the software infrastructure up and running and properly learning the design tools and simulators is way too much.
 
I repeat my appeal for an performant LA lease (2-3days, practically a week-end), if not, my meager finances will only let me try a SCANA Plus from IKALOGIC  for 95-100EUR or DS Studio clone, also any recommendation will be nice.


In the mean time let me tell you why I'm whining here, optimistic with the relatively easy capture for the sine waveform I've tried to change the waveform to square and also determine the on/off sequence for enabling the channels. Sadly this always triggers a full readout and refreshing of the LCD, and this is too much for the little Intronix and my attention span,  I can only get something like 8-10 registers even with compression, and it's easy to lose count when the control message has both readings and writings and around 60-100 registers moved around :(.

So right now I'm desperately sending price offers in fleabay, because if I order from China it will take ages. And trust me, it hurts to have to buy this crap and I have a good chance to be also useless.
 >:D note: If I'll ever make a commercial device with SPI interface, I'll make the clock high enough and space the transfers far enough to kill all the miserable LA, only elite LA owners should be able to decode it, at least here FeelTech did something good  ::) 

   Cheers,
   DC1MC
 



 

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: 2N3055 on January 22, 2018, 11:10:47 pm
I believe I did mention this before  Zeroplus LAP-C has compression and also something they call "filtering", which is basically "sample enable gating".. You can enable one of the inputs to  behave as a sort of "enable", gating,  so analyser is not spending memory when not enabled. On SPI protocol you can set it to work on chip select for instance, and it will sample only when CS is active...
Sampling to 200Mhz..
I have 16128, 16ch 128k samples depth. Useful little thing..
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 23, 2018, 01:18:06 am
On the subject of getting stuff delivered from China ,
I ordered quite a few items in early December ,some arrived within the specified time frame ,other stuff Im still waiting on .
Ive contacted a few of the sellers just to let them know Im still waiting .
Most just said hang tough another while ,but one offered to courier air freight another unit for something like 3 dollars US and work out what to do later if the original order arrives ,So really Im just saying if you see something at a good price from PROC it could be worth asking about what other delivery services are available , Im guessing the 3 dollars covers their costs,but you do see many places offereing courier delivery for way more more money ,like 20 dollars. Something small like a logic analyser might be cheap to fast track .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 23, 2018, 11:55:02 am
I believe I did mention this before  Zeroplus LAP-C has compression and also something they call "filtering", which is basically "sample enable gating".. You can enable one of the inputs to  behave as a sort of "enable", gating,  so analyser is not spending memory when not enabled. On SPI protocol you can set it to work on chip select for instance, and it will sample only when CS is active...
Sampling to 200Mhz..
I have 16128, 16ch 128k samples depth. Useful little thing..

Well, good for you and the useful little thing, the problem is the "upgradeable" 16032 units from 2011-2013 are long gone, fleabay has exactly ONE 16034 unit for 225 EUR and looking at the German/EU specialty shops shows the thing in between 480 and 800EUR, and I will never pay so much.

What will be nice to have is a board with a robust Xilinx FPGA  + DDR2 RAM like this Papillio or the Pipistrello board, unfortunately ALL of them had brainfarts during design, instead of putting some Cypress FX, interfaces they've put either some lame USB to serial converters or even lamer PICs, making them completely useless for anything, and so these boards have more or less disappeared.

Why is nobody connecting one of these FX3 chips to a FPGA+tons of RAM (64MBit at least) and so a nice logic analyzer design on it, with RLL, gating and data streaming, using the on device RAM for ample buffering.
On such a device I definitely spend  5-600EUR, not on some unknown ASIC based crap that is not even USB3.

 OH well, I have to ask in forums if such a board already exists, maybe I do need to start a bit of digital design.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 23, 2018, 09:59:07 pm
So I am on a different path. Mind you, not a very successful one, but I may as well see it through.

The Frauenhofer powerpoint is even more explicit then the paper. Where the paper states something along the lines of "testing some samples showed that the attack may not work on other series", the powerpoint simply states "we could not get this attack to work on other series"
And they do write they also had access to the STM32F103C8. I am also not able to get it to work, but that maybe me being stupid.

So, just for the heck of it, I ordered the same development board they were using (with a STM32F051R8T6)
If I can get the attack to work on that, I know I am doing it right. And if it then still not works on the STM32F103C8, I know we are screwed.

Should be here soon too.  For some unfathomable reason,  buying it local in Netherlands is cheaper then on eBay. Weird.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 23, 2018, 10:25:02 pm
Strange thing Cybermaus, in Merkelania, the blue pills with the exact same chip as in the FP are something like 4,99EUR, I've got two of them, to use for the Fraunhoffer experiment, I was thinking to make the pseudo SWI debug interface on one of them and use it on the other and fine tunning the timing, I think it will get a bit better and faster then what the researchers used.
Right now I'm getting hold back by the lack of a proper LA (hint for the gear heads, part for a week-end of your cool LA, I promise not to run with it ;) so in the mean time I have to see how to solve this.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: 2N3055 on January 23, 2018, 10:58:19 pm

Well, good for you and the useful little thing, the problem is the "upgradeable" 16032 units from 2011-2013 are long gone, fleabay has exactly ONE 16034 unit for 225 EUR and looking at the German/EU specialty shops shows the thing in between 480 and 800EUR, and I will never pay so much.
My 16128  was 270 € (no VAT) in eleshop...

What will be nice to have is a board with a robust Xilinx FPGA  + DDR2 RAM like this Papillio or the Pipistrello board, unfortunately ALL of them had brainfarts during design, instead of putting some Cypress FX, interfaces they've put either some lame USB to serial converters or even lamer PICs, making them completely useless for anything, and so these boards have more or less disappeared.

Why is nobody connecting one of these FX3 chips to a FPGA+tons of RAM (64MBit at least) and so a nice logic analyzer design on it, with RLL, gating and data streaming, using the on device RAM for ample buffering.
On such a device I definitely spend  5-600EUR, not on some unknown ASIC based crap that is not even USB3.

 OH well, I have to ask in forums if such a board already exists, maybe I do need to start a bit of digital design.

 Cheers,
 DC1MC

Also was said, tool with Xilinx® Spartan®-6 FPGA and 2Gbit of buffer RAM is Digital discovery...  That one was 186 € (no VAT)... No compression, but it has segmented capture..
Maybe Digilent could be persuaded to add compression ??

Regards,

Sinisa
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 23, 2018, 11:30:43 pm

Well, good for you and the useful little thing, the problem is the "upgradeable" 16032 units from 2011-2013 are long gone, fleabay has exactly ONE 16034 unit for 225 EUR and looking at the German/EU specialty shops shows the thing in between 480 and 800EUR, and I will never pay so much.
My 16128  was 270 € (no VAT) in eleshop...
Now out of stock :(

What will be nice to have is a board with a robust Xilinx FPGA  + DDR2 RAM like this Papillio or the Pipistrello board, unfortunately ALL of them had brainfarts during design, instead of putting some Cypress FX, interfaces they've put either some lame USB to serial converters or even lamer PICs, making them completely useless for anything, and so these boards have more or less disappeared.

Why is nobody connecting one of these FX3 chips to a FPGA+tons of RAM (64MBit at least) and so a nice logic analyzer design on it, with RLL, gating and data streaming, using the on device RAM for ample buffering.
On such a device I definitely spend  5-600EUR, not on some unknown ASIC based crap that is not even USB3.

 OH well, I have to ask in forums if such a board already exists, maybe I do need to start a bit of digital design.

 Cheers,
 DC1MC

Also was said, tool with Xilinx® Spartan®-6 FPGA and 2Gbit of buffer RAM is Digital discovery...  That one was 186 € (no VAT)... No compression, but it has segmented capture..
Maybe Digilent could be persuaded to add compression ??
This is a thing that I will not pick it for free, my rant about can be read for your enjoyment in the other forum where I was asking for board suggestions  :-DD

Regards,

Sinisa

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 24, 2018, 12:32:16 am
The good news:  I've got reliable connections to the bus and am getting data.  The MSO2204EA will collect 10 Mpts at 100,200,500 Ms/S & 1 Gs/S.

The bad news: I have no clue what I'm doing.  I've never used the LA features before other than a brief attempt which made clear I needed more reliable connections to the bus.  So I have several things to learn.  The scope LA , the AWG and the SPI bus..  I know what the SPI bus  is and  its strengths and weaknesses, but I have no practical experience working with it.  I've also never used a  LA before.

FWIW I was reading the JDS thread today.  The maker is very active in the forum helping owners and explaining the history of the very similar units.  Apparently two engineers designed all the units.  The JDS is the most recent version.  I think a major issue for FeelTech is the lack of an engineer with English language skills.  I urge everyone to ask for technical assistance from FeelTech.  JDS is providing the bus command protocol.  It's in Chinese so google translate is required for most, but they will help with problems.

Please!!!! Start a thread in the repair section of EEVblog so people can find things like bus pin assignments, etc.  Trolling through this thread to find a snippet of information is a huge waste of time.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 24, 2018, 06:23:04 am
I can arrange Chinese translations if needed. I am owed a few favours  :)

Now what and where do I probe or more to the point what is most useful? Thinking of populating the third header on the display board with pins to make it a bit easier?

Both my boards are V1.5 running v3.1 firmware btw

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 24, 2018, 07:29:25 am
The good news:  I've got reliable connections to the bus and am getting data.  The MSO2204EA will collect 10 Mpts at 100,200,500 Ms/S & 1 Gs/S.

The bad news: I have no clue what I'm doing.  I've never used the LA features before other than a brief attempt which made clear I needed more reliable connections to the bus.  So I have several things to learn.  The scope LA , the AWG and the SPI bus..  I know what the SPI bus  is and  its strengths and weaknesses, but I have no practical experience working with it.  I've also never used a  LA before.

FWIW I was reading the JDS thread today.  The maker is very active in the forum helping owners and explaining the history of the very similar units.  Apparently two engineers designed all the units.  The JDS is the most recent version.  I think a major issue for FeelTech is the lack of an engineer with English language skills.  I urge everyone to ask for technical assistance from FeelTech.  JDS is providing the bus command protocol.  It's in Chinese so google translate is required for most, but they will help with problems.

Please!!!! Start a thread in the repair section of EEVblog so people can find things like bus pin assignments, etc.  Trolling through this thread to find a snippet of information is a huge waste of time.

OK, the's take them in importance order last is bigger:
1) FeelTech and technical assistance: Only in China you can became an electronics engineer without proficient English, all over the world you're screwed if you try, I wish they would have exported just the textile industry there :(.
Asking for technical assistance: I have asked FeelTech really politely for very minor things, I've got exactly ZERO answers, if nobody knows English there it's understandable, if somebody ask for me of something in Swahily I won't be able to answer them, or just confirm that I've received an inquiry, that make sense. Ah, who am I kidding, they are the typical Asian company, eager to copy and profit from everything and considering a weakness and stupidity to share anything back, at least with non-Asians. I would so much LOVE to be proven wrong, but in 15 years or so while dealing with them I never had a cool story, and I haven't heard too many as well.  So JDS has a full specification of the control protocol from the FP to the Signal Board, all the registers and settings being explained, and compatible with FY6600 huh ? Willing to share it, but in Chinese ?
I would say bring it on, I've never seen a real unicorn yet :), and being a Mandarin Unicorn will not make it less beautiful ;).
Also a link to the JDS thread will help.

2) About actually doing stuff, I don't know if your scope has an individual LA or just has a protocol decoder using the analogue scope inputs.
<Beginner explain mode>
The commands are send via SPI protocol, the protocol uses 3 to 4 wires and it's a synchronous protocol, that means the data it's send and received being aligned with a common clock shared both by the sender and the receiver.
So you have to grab that clock before everything else, in our situation it's on pin 6 of the connector, the SPI protocol it's also a raycist  ;D  protocol, where there is a master and a number of slaves, they are selected with an individual selection pin, in our case there seem to be two slaves, but for basic stuff we can ignore it for the moment. Only master talks and generates the clock, and talks to the slaves using the MOSI signal (Master Out, Slave In), pin 8 and listen to what are they saying using the MISO pin (Master In, Slave Out), pin 7.
There is also a Slave Select or Chip Select pin, that goes to 0 usually, to wake up the slaves and tell them that the master is gonna talk and they better be listening and answering or else... (very raycist ;)
This is our pin 5, usually if you have a LA you use this pin on falling edge to trigger acquisition, if you have a two channel scope with separate sync input you put it there and use it as trigger, if you have a 4CH scope you can still put it on the sync input but also on one of the channels, and if you have just a 2 channel scope without separate sync, you ignore it and use the clock signal to trigger, but it's a bit on the edge.

So, with a two inputs scope you can see one direction only M->S or S->M, with a 4 inputs scope you can see and decode fully the SPI interface, same with a proper LA.

Now the clock and transfer size varies, in our case the clock it's 18MHz and the transfer size or word size it's 16 bits, an LA should be  used in sampling mode, with a sampling frequency of at least 100MHz to get reliable results. Scope ca. 50ns/div, depends on what they recommend for SPI protocol decoding in regard with the clock frequency.

On the Signal Board side, in the FPGA, there are a number of individual addressable entities called registers, a register is written or read using 3 x 16bit transfers, one for address and two for the data to be written or read, you can see a bit behind some of those registers read and explained, my LA has reached it's limits, so I'm waiting to get a proper one.

If your protocol decoder works, you should be able to get the registers values while doing different settings (compare first with the ones already discovered to make sure that everything it's set OK ).
In the evening I will make a new post in the Repairs forum, summarizing the details spread around here and I can assist anyone trying to get the information or trying to translate this mystical JDS document :).

I have to run for work now, cheers.

</Beginner explain mode>
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on January 24, 2018, 07:35:12 am
Despite all the warnings and firmware issues I decided to buy the unit beginning this month and it still somewhere between China and me. But I expect the unit to be delivered next week if customs is playing nice this time.

I was planning to help with the protocol decoding but all the high speeds and long packet pauses got me of this helping plan since I don't have a capable LA. only a 4ch 200Ms scope with limited memory.

Making a schematic of the boards should be no big deal as from the pictures most of it is clear enough already. The front panel is still a bit unknown to me as there are no high res pictures available yet.

I plan on making a linear PSU with 6 outputs 2x +5, +-13.8V and +-5V for the 5 legged op amps to replace the 7805 and 7905.

Hope to make a new front panel controller/software with a combined effort of us all, only for a different font would be top notch :D

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 24, 2018, 08:11:56 am
Scope is a 4channel 100MHz with uart spi i2c can bus decoding etc.

Just for my information as much as anyone elses I have buzzed out the header on the front panel because as has been mentioned this thread is getting a little bulky to follow and got the following.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 24, 2018, 11:56:33 am
Scope is a 4channel 100MHz with uart spi i2c can bus decoding etc.

Just for my information as much as anyone elses I have buzzed out the header on the front panel because as has been mentioned this thread is getting a little bulky to follow and got the following.

Well, now you know where to hook you scope  ;D, waiting for the first results, if possible try to reproduce the Sine wave result that I have posted, there are 20 registers set ( 30 SPI transfers) and then try for example disabling and re-enabling of a channel, this updated the LDC and transfers muuuuch more data, this killed my little Intronix.

Nice picture with comments, we should include it in the official documentation in the new thread, I'll do a fully disassemble of my FP to get pictures and try to map the buttons and the LCD connector.
Maybe you can post it completely along with others to help DerKammi with the schematic capture.

@DerKammi Let's not be swept away by all the negativity, for the price it's really a good development platform for people that want to study and understand many things, from MCU to FPGA programming, direct digital synthesis of signals, analog stuff and much more (even power supply design and pitfalls). And when it works it makes a usable device and if fully moded and fitted with our new fw ;) will make a killer device.

 Cheers from the lunch break, DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on January 24, 2018, 12:08:47 pm
@DerKammi Let's not be swept away by all the negativity, for the price it's really a good development platform for people that want to study and understand many things, from MCU to FPGA programming, direct digital synthesis of signals, analog stuff and much more (even power supply design and pitfalls). And when it works it makes a usable device and if fully moded and fitted with our new fw ;) will make a killer device.

Oh I'm not at all. The reason of the purchase is the modding capabilities of this device. Also a new firmware is something which I find to have a real goal of writing software for. Taking also those small embedded projects to the next level in my hobby environment.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 24, 2018, 04:32:49 pm
Ask for a pinout and get a lecture on PC :-(

The FD JDS6600 thread is here:

https://www.eevblog.com/forum/testgear/anybody-know-anything-about-this-signal-generator/msg1233239/#msg1233239 (https://www.eevblog.com/forum/testgear/anybody-know-anything-about-this-signal-generator/msg1233239/#msg1233239)

Sadly, I am now completely borked.  I was getting SPI traffic last night but didn't know which pins to assign in the LA.  This morning when I powered it on, the LA reported "buffer overflow".   After that there was no detectable bus traffic.

After I dug through all the excess verbiage and found the pin assignments I discovered that except for an occasional burst of noise on all channels of the SPI bus, there is NO traffic.  The beeper makes noise, but maybe one out of 10-20 beeps is accompanied by bus traffic.  Just in case it was an error setting up the LA, I switched to using the analog channels.  It's just noise.

Two pins are logic high and two are logic low when it is idle.  There is now no output from either channel.  There was earlier this morning, but I could not change the waveforms.  Power cycling seems to be fatal.

Nothing left now for me to do except to treat the FP as a crappy dev board with some buttons and an unknown LCD unless someone comes up with a FW image or the bus protocol.  It will be interesting to see what eBay and Paypal have to say.  I just wish it were easier to contact them.

I'll probably order an FD JDS6600 in the next few days to have a decent AWG.  But I'm going to read the full thread first.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 24, 2018, 05:53:35 pm
@rhb: Oh man, this is really terrible  :palm:, it seem that there really is something that kills them, the firmware or the power supply must be really bad, because I've abused a blue pill board with the same chip and practically 0 power filtering, besides an anemic cap, and I still wasn't able to bork it.
Kindly please tell us the firmware version, how is the defect manifesting (besides no signal) like is the display still  correctly showing up info, the channel LEDs are going on and off when you enable and disable the channel, and finally, is the unit recognized and controllable from the PC, can you try there to set up a sine waveform from the PC ?
The I/O pins of the STM are pretty resilient to grounding and short-circuiting and on the configuration connector there is no power, just ground.
For the sine wave we have the SPI control sequence, to set up almost everything, we're missing the initialization sequence and then you can connect anything that can do SPI with 16bit word ( again a blue pill will be the best and very cheap).

I'M MAKING AN APPEAL TO GERMAN READERS THAT ARE PLACED IN THE MANNHEIM-HEIDELBERG-KARLSRUHE-STUTTGART AREA AND HAVE A PERFORMANT LOGIC ANALYZER FOR LEASING IT TO ME FOR A WEEK-END OR I CAN COME WITH MY UNIT TO THEIR PLACE AND MEASURE THE BUS TO GET THE PROTOCOL OUT OF THE WAY !!!


It's a four hour work with two persons, and I can also provide the beer and Würstchen, or a snack/beverage of choice plus he'll get all the forum glory and karma  :-+ .

If by this week-end I'll not find a better analyzer, I'll try to proceed with my Intronix to get at least the initialization sequence out of many restarts, if it holds it holds, if it dies it dies, if not at least we can still use the borked units until the fw is recovered/rebuild.

Keep fighting,
DC1MC

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on January 24, 2018, 06:05:34 pm
Hello,

It would not be electrostatic discharge that would be a problem ?

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 24, 2018, 06:12:56 pm
Hello,

It would not be electrostatic discharge that would be a problem ?

Diabolo

That could be a cause, but I believe everybody here knows the basic rules for ESD protection and rsd isn't a novice. Also the defect appeared at power-on not when wires were moved around, AFAIK it was working OK and rhb turned it off for the evening and when turned back it was not working anymore. There are so many reports of these just dying at power-up that it seems there is a catastrophic design fault, wonder if it's sw or hw  :o.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on January 24, 2018, 06:24:51 pm
Hello,

It may be a "weak" component that dropped at startup.
I have a FY2300H (color blue) version 3.2 (bought July 2017) and I have no problem, its power is 5V - 1A by a PS style charger GSM.


Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 24, 2018, 07:00:49 pm
I have started a thread in Repair "FeelTech FY-6600 Corrupt Flash Repair" which summarizes what information we have.  If you post there *please* be brief and clear.  Discussion should remain here.

FWIW I'm working on an ESD mat and the humidity is 100%.  With exactly identical screens on multiple units after corruption, ESD seems an unlikely cause.

I'm about to start testing the FP separated from the SB.  I have other projects and this is looking a lot like what we call a "dry hole" in the oil industry.  So further efforts by me will be sporadic.






Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 24, 2018, 07:46:51 pm
Hi there!

Nice thread and a lot of interesting things to read.
I've got a FY6600 60Mhz with firmware V3.2.
You will find attached a dump of the flash memory for the records. (@cybermaus: nice how to... )

I have also hooked up my LA to the board and will try to help gathering informations on the FP<-> FPGA protocol (just a matter of free time).
I will first try to see if there are obvious differences in the V3.2 protocol with what DC1M1C already described for V3.1.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 24, 2018, 08:40:29 pm
Welcome on board fremen67  ^-^, I hope that you'll be the next one to get some data out of this cable.
Now it's the battle royale of the Logic Analyzers, I've wanted to see how much it's the initialization sequence when one channel is activated and the whole LCD is refreshed, as my little LA doesn't stand a chance to log the sequence I started to count the SPI transfers at least.
BLOODY ROTATING HELL !!!
5608 transfers !!!
Whoever has a LA that is able to log this, please tell, I want one.
The novelty is, as opposed with setting frequency, amplitude and such, this time I have managed to capture the one SPI register read operation, the exact last one even :).
They differ from write operation, that have one SPI transfer 3x16bits words (address + 32 bit value), the register read operation first sent the address (one transfer MOSI) then, a bit later, reads 32 bits in two transfers form the slave (MISO).
Please have a look at the attached picture, the full read operation is between cursors A and B.

Good that I've found an excellent FPGA board with lots of DDR3 ram and USB 3.0 interface and I've reconnected with an old digital designer friend, this calls for a serious LA  ;D

 Cheers,
 DC1MC

 


 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 24, 2018, 08:54:24 pm
I've separated the FP from the SB.  If I power up the FP without connection to the SB it just displays the FeelTech logo.  No other information.  So there is some communication from the SB to the FP.

I'm getting waveforms out again, so it appears that I caused problems when I soldered wires to the 8  bit bus connectors making the connections to the SB header unreliable.   In retrospect, I should have cut the cable in the middle and soldered the ends together to take the grabbers.

I observed some large globs of flux which I have cleaned off with isopropyl.  I've encountered problems in humid climates with absorption of moisture affecting signal integrity.

@DC1MC the picture is missing
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: texaspyro on January 24, 2018, 09:00:51 pm
Are you qualifying the logic analyzer clock with the SPI chip select signal for the signal board?  That will limit captures to just those for the signal board.  Most analyzers have a way to qualify the clock,  otherwise you may need to add an external gate.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 24, 2018, 09:40:43 pm
Here is a capture of the Power On initialization sequence for the main 6 signals : 4.5 sec,  29403 transfers... A lot of material to study ...

PA1 seems to be some sort of /FPGA Ready signal. It is true at the beginning then falls just after MISO has been released. It last for 180ms
PB 11may not be a second CS as already suggested but rather a /Register Select signal. It is always down when sending the register number to the FPGA then up when sending the value for it.

If you want to have a look at the power on sequence, you need to download Dsview 0.98 here: http://www.dreamsourcelab.com/download.html (http://www.dreamsourcelab.com/download.html)
Just open the .dsl file and the Decoder window. The screenshot shows you what you can see when zooming
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 24, 2018, 10:19:05 pm
... I've wanted to see how much it's the initialization sequence when one channel is activated and the whole LCD is refreshed, as my little LA doesn't stand a chance to log the sequence I started to count the SPI transfers at least.
BLOODY ROTATING HELL !!!
5608 transfers !!!
I attached 2 captures: the OFF to ON and then ON to OFF sequences for CH1: Sine, Freq.10Khz, Amp.5V, Off.0V, Duty.50%, Phase.0, same on CH2 which remained OFF.
EDIT: I just noticed that with V3.2 I have 6024 transfers in that case compared to your 5608 ...

Whoever has a LA that is able to log this, please tell, I want one.
The captures where made using a DSLogic Basic (55€ on aliexpress) upgraded to the Plus version by adding a 256Mbit RAM Buffer (2€ @mouser). But even the Basic version can stream the Power On initialization sequence with simple Triggers (6 channels@ 50Mhz or 3 signals @100Mhz).
Having the buffer allows you to setup complex triggers (like a specific register value) at higher sampling rates: @400Mhz for 4 signals (You can also activate RLE compression when needed).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 24, 2018, 10:32:30 pm
I'm getting waveforms out again, so it appears that I caused problems when I soldered wires to the 8  bit bus connectors making the connections to the SB header unreliable.   In retrospect, I should have cut the cable in the middle and soldered the ends together to take the grabbers.
Cutting wires is a little bit extremist  :)
With this type of connector, you don't need grabbers. I would suggest to solder head to head 2 rows of 8 pins. You release the connector from the board, insert one side of the 8 pins in the upper part of the connector and then replug the connector. This will lock the pins in place. Than you connect on the other side of the 8 pins directly your LA wires (or eventually scope probes). Have a look at the photo I posted before, this should be clearer than my explanation  ;)

EDIT: Typo.. "lock" and not "look".. sorry
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 24, 2018, 11:41:04 pm
... I've wanted to see how much it's the initialization sequence when one channel is activated and the whole LCD is refreshed, as my little LA doesn't stand a chance to log the sequence I started to count the SPI transfers at least.
BLOODY ROTATING HELL !!!
5608 transfers !!!
I attached 2 captures: the OFF to ON and then ON to OFF sequences for CH1: Sine, Freq.10Khz, Amp.5V, Off.0V, Duty.50%, Phase.0, same on CH2 which remained OFF.
EDIT: I just noticed that with V3.2 I have 6024 transfers in that case compared to your 5608 ...

It is even worse than that.. I was only capturing the first train of tranfers. In fact when you switch ON CH1, there are 3 trains of transfers.. 12111 transfers in total. I could not find a difference when analysing the captures of CH1 OFF->ON and ON->OFF... just because the first train is identical... so 6024 transfers less to search in  ;)

EDIT: 12111 transfers for one command :scared:
Reg 0x05 = 0  -> CH1=ON, CH2=ON
Reg 0x05 = 4  -> CH1=OFF, CH2 = ON
Reg 0x05 = 24  -> CH1=OFF, CH2 = OFF
Reg 0x05 = 20  -> CH1=ON, CH2 = OFF

So if I make no mistakes:
Reg 0x05:bit5=0/1 -> CH1=ON/OFF
Reg 0x05:bit2=0/1 -> CH2=ON/OFF

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 25, 2018, 12:40:46 am

Cutting wires is a little bit extremist  :)
With this type of connector, you don't need grabbers. I would suggest to solder head to head 2 rows of 8 pins. You release the connector from the board, insert one side of the 8 pins in the upper part of the connector and then replug the connector. This will lock the pins in place. Than you connect on the other side of the 8 pins directly your LA wires (or eventually scope probes). Have a look at the photo I posted before, this should be clearer than my explanation  ;)

EDIT: Typo.. "lock" and not "look".. sorry

What is the connector and where can you buy them?  I looked for a long time online without finding anything.  I made a new connector using an 8 pin "Dupont" connector, but it doesn't make reliable connections.

My original intent had been to make a probing harness, but I got impatient.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 25, 2018, 01:38:40 am

Cutting wires is a little bit extremist  :)
With this type of connector, you don't need grabbers. I would suggest to solder head to head 2 rows of 8 pins. You release the connector from the board, insert one side of the 8 pins in the upper part of the connector and then replug the connector. This will lock the pins in place. Than you connect on the other side of the 8 pins directly your LA wires (or eventually scope probes). Have a look at the photo I posted before, this should be clearer than my explanation  ;)

EDIT: Typo.. "lock" and not "look".. sorry

What is the connector and where can you buy them?  I looked for a long time online without finding anything.  I made a new connector using an 8 pin "Dupont" connector, but it doesn't make reliable connections.

My original intent had been to make a probing harness, but I got impatient.

I guess what I wrote was not clear :) When I wrote "With this type of connector" I was talking about the type of the white connector used on the board. Because it is huge and has 2,54 mm spacing you can just use classical 2.54mm male breakable Header Strip. I am sure you have plenty of them in your drawers. You cut 2 rows of 8 pins, solder them together by the shorter side and that's it. It is the same idea as putting needles in the rear side of the connector to access the contacts. With this photo you will find it obvious  ;)
The tip is to remove the connector from the board before inserting the header pin "connector" in it: it is much easer to put it in and afterwards when you reconnect your connector on the board, the header pins can't move.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 25, 2018, 02:20:32 am
If that were a M-F pair I could see how you could put grabbers on between the plastic strips.  However, I'm not getting reliable connections using female connectors  on the male board  pins. The header pins on the board  are much shorter than the headers in your picture.  I cut back the plastic on the F connector, but the sockets don't stay in place when I try to press the connector in place.

You can plug the setup you show into the FP or SB, but they don't work without talking to each other.  So I'm still unclear how what you are suggesting would work unless you had a pair of F-F cables.

Which still leaves my question,  What is a source for those cable connectors?  Or  replacement  cables.

[edit]

I found the connectors.  It's the JST XH series.  Digikey carries them.  Unfortunately, the crimping tool is *very* expensive.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 25, 2018, 03:26:48 am
Here's a possible option for the LA problem;

https://www.youtube.com/watch?v=_LnZrXrdC00 (https://www.youtube.com/watch?v=_LnZrXrdC00)

An FPGA and some compression logic would be nice, but for $45 and 200 MB/S it looks as if it might well do the job for this problem.

I opened up the Instek LA pods and they have a bunch of ADCMP561s and a bunch of discretes in addition to some other stuff.  Pods are marked 100K ohms and 40 V.

So there's a bit more than just an FX3 to making a proper LA, but as we are dealing w/ 3.3 V logic it might be worth a gamble.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 25, 2018, 03:49:14 am
I found the connectors.  It's the JST XH series.  Digikey carries them.  Unfortunately, the crimping tool is *very* expensive.

You don't need a rip-off crimping tool for XH connectors - just use lengths of FTP network cable wire and solder them to the pins, then use a pair of needle nosed pliers to fold the "wings" of the pins over the insulation to grip the wires.  Just use minimal amounts of solder so that you can still insert the pins into the plastic shell.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CustomEngineerer on January 25, 2018, 04:21:45 am
If that were a M-F pair I could see how you could put grabbers on between the plastic strips.  However, I'm not getting reliable connections using female connectors  on the male board  pins. The header pins on the board  are much shorter than the headers in your picture.  I cut back the plastic on the F connector, but the sockets don't stay in place when I try to press the connector in place.

You can plug the setup you show into the FP or SB, but they don't work without talking to each other.  So I'm still unclear how what you are suggesting would work unless you had a pair of F-F cables.

Which still leaves my question,  What is a source for those cable connectors?  Or  replacement  cables.

[edit]

I found the connectors.  It's the JST XH series.  Digikey carries them.  Unfortunately, the crimping tool is *very* expensive.

Pretty much any cheap generic jst/dupont crimpers will work. You can even use the cheap sockets for making the dupont connectors, but instead of putting the plastic housing on just put some shrink wrap. I made the one in the picture the other day with exactly what's in the picture (~$10 for the crimper 5 - 10 years ago, ~$1 for the sockets). As for fremen67's suggested way of connecting, you are way overthinking what he is saying. Go back and look at the first picture he posted where he is already hooked in. He is not using (or suggesting to use) grabbers. The multicolor cables are going back to the LA, no grabbers necessary, the LA cables just plug directly into the adapter. And the adapter is being pushed directly into the original connector that is already in the generator. He is just suggesting to pull the cable from the generator board before trying to push the adapter into the back of it to allow the adapter pins to go in easier, then the generator cable gets plugged directly back into the board.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 25, 2018, 04:37:41 am
Long pin header seems to work fine for me . Plenty of length for clips or probes.  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 25, 2018, 07:21:31 am
Holly cow, you go to sleep a bit depressed and you wake up with a lot of cool activity  ^-^ ^-^ ^-^

@fremen67  Vive la France !!! finally data, sweet data, to analyze  8) !!! Than you so much !!!
Now some comments:
Basic architecture:
- Having -PWRGOOD and -FPGARDY signals are a good and logic design decision, I did the same as @rhb and started the FP with the data connector out, it now explains why it blocks waiting for the two signals to drop, for the sake of experiment I will try to artificially pull them down and see how the FP display looks like, especially what waveform data is selected by default and how the picture of it looks.
- Having an address/data selector pin it's a bit meh, if the registers are always 32bits, it will introduce a minor complication while writing the new firmware, I'm curious how they switch in between reading and writing a register from the FPGA pov, because this will help us to produce the first and most important new firmware routines: register read and write.
- Detaching the actual configuration commands from the stuff that displays the waveform on the LCD, that IMO is the bulk of the transfers and should consist mostly of reads (sample the waveform description in FPGA to do a drawing ?!?!?),  because for the non-FP firmware, we don't need to bother with little miserable pictures for starters.

Current data sets:
@fremen67
- I want to kindly ask you to do an 100MHz sampling "reference" capture for the initialization sequence, the SPI clock it's 18MHz and Shannon may wink from where it is  >:D, so activate the RLE and buffering and get the full initialization seq for reference, I'll have to munch on it, it's a lot of research, for example I'm really curious if the FP reads the data from the SPI Flash first and then push it to the FPGA.
About the On/Off captures and the multiple train of pulses, this sounds a bit weird, I did my captures with CH1 already in the OFF state and counting the pulses for the push to ON, and even if my little LA it's outclassed by the diarrhea of data, it was counting reliably the number of transfers (NCSS going down), putting one transfer more in the trigger settings was not triggering it,
If you can repeat (again as 100MHz sampling) the measurement with the CH1 already in OFF state before starting measurement I will double grateful.

Logic Analyzer:
I've found this excellent Artix boards with lots of RAM and Cypress FX3 interface, and a digital designer to help me, the seller send the schematics and SDK and it actually looks sane, I'll try to produce an updated DSPro+ thingie to not be caught off-guard if the next project with an 33MHz SPI clock ;). The analog front end will be a pleasure to design  8). I'll let you know if you're interested, PM me, it's off-topic on this thread.

 See you all in the evening,
 DC1MC 

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on January 25, 2018, 12:32:56 pm
The captures where made using a DSLogic Basic (55€ on aliexpress) upgraded to the Plus version by adding a 256Mbit RAM Buffer (2€ @mouser). But even the Basic version can stream the Power On initialization sequence with simple Triggers (6 channels@ 50Mhz or 3 signals @100Mhz).
Having the buffer allows you to setup complex triggers (like a specific register value) at higher sampling rates: @400Mhz for 4 signals (You can also activate RLE compression when needed).

Which chip did you use? I like the idea of this kind. ^-^
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 25, 2018, 03:07:44 pm
I tried what fremen67 does, but with individual wires which proved unreliable.  Wish I had thought of using a header like that.  Very slick. 

The "dupont" style connectors I have (eBay assortment) have the sockets recessed too far to reach the board pins.

So I'll be filling in the hole i dug once I get some connectors and a crimping tool.

BTW I'm *very* interested in a more capable LA than what the Instek provides.   Something that just sends transitions to the PC for recording and which can be configured to sample at some multiple of the target clock.  So please start a thread in the Projects section.  I've been planning to get a miniZed because of the widespread use of the Zynq in scopes.  Getting another would not be an issue.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: gbraux on January 25, 2018, 07:11:17 pm
Hi. I am new to the forum, so a big hello from Paris, France.

I have just received my FY6600 (30Mhz) from Aliexpress and ... looks like they have updated the PSU :-)
I also ordered some IEC connectors at the same time ... but I won't bother making the ground hack : Ground-BNC to Ground-Earth = 300mV :-)

FW Version : 3.2
Main board Feeltech branded V1.501
PSU brand is "SUOR". Most immediate visual difference with the previous PSU is the banding (used to be FeelTech) , and they have removed the unpopulated headers we used to use for connecting ground-earth(IEC hack). There may (for sure) be some other differences, but not an expert ...

Guillaume.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 25, 2018, 09:53:26 pm
Hi Guillaume,
welcome to the forum .
That sounds like good news ,maybe the original supply was responsable for the dodgy batch ,
I said I might as well repost this image from a previous comment for the purposes of comparison.
not the greatest of images ,maybe theres a better one to be found .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 25, 2018, 09:58:00 pm
Only difference I can spot for sure from those two photos is the Yellow mains input filter cap is gone .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on January 25, 2018, 10:12:29 pm
Slightly better image here ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 26, 2018, 12:36:10 am
- Having an address/data selector pin it's a bit meh, if the registers are always 32bits, it will introduce a minor complication while writing the new firmware …
But it is more robust  as a falling edge of CS while having RS low always indicates the beginning of a register write command thus insuring synchronization…

- I want to kindly ask you to do an 100MHz sampling "reference" capture for the initialization sequence, the SPI clock it's 18MHz and Shannon may wink from where it is  >:D
In streaming mode the LA can sample up to 3 signals @100Mhz  and up to 6 @50Mhz (In buffer mode there is no way that it can capture 4.5 sec of signal, even with RLE activated…).
I recorded  yesterday 2 captures of the init sequence @100Mhz (MOSI-MISO-CLK) and @ 50Mhz (MOSI-MISO-CLK-/CS-/RS) and then checked that the SPI decoded values where exactly the same. So appart from cosmetical consideration on CLK not beeing a perfect square signal, all the SPI decoded value should be correct in the 50Mhz capture with the benefit of having CS and RS at the same time.
I will post a 100Mhz capture for you but I find the 50Mhz one much easier to read.

Regarding Shannon winking I think he could be reassured and RIP  :)
The Shannon Sampling Theorem states that your sampling rate should be at least twice the highest frequency contained in your signal, that is 18Mhz here from CLK, thus the sampling rate should be at least 36Mhz. There is a rule of thumb that says you need at least 4 times the highest  frequency to be on the safe side (that is 72Mhz here) but hey … with 50 Mhz we are somewhere in the middle… and it works.

About the On/Off captures and the multiple train of pulses, this sounds a bit weird, I did my captures with CH1 already in the OFF state and counting the pulses for the push to ON, and even if my little LA it's outclassed by the diarrhea of data, it was counting reliably the number of transfers (NCSS going down), putting one transfer more in the trigger settings was not triggering it,
If you can repeat (again as 100MHz sampling) the measurement with the CH1 already in OFF state before starting measurement I will double grateful.
This is exactly what I did yesterday (about 15 times I think, maybe more...and @100Mhz) plus the other way (ON to OFF). Don’t forget that :   
-   There is more than 172ms between train 1 and 2
-   The revision I have is V3.2 (I think you have 3.1 ?)
That could explain the different behaviour.

For the init sequence capture, I would recommend that you place a cursor just before the first SPI transaction (around 66.66 ms) and change the protocol decoding start from "Start" to "Cursor 1" (see photo)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 26, 2018, 12:47:04 am
The captures where made using a DSLogic Basic (55€ on aliexpress) upgraded to the Plus version by adding a 256Mbit RAM Buffer (2€ @mouser). But even the Basic version can stream the Power On initialization sequence with simple Triggers (6 channels@ 50Mhz or 3 signals @100Mhz).
Having the buffer allows you to setup complex triggers (like a specific register value) at higher sampling rates: @400Mhz for 4 signals (You can also activate RLE compression when needed).

Which chip did you use? I like the idea of this kind. ^-^

This one : https://www.mouser.fr/ProductDetail/913-4816M16A2TG6AGTR (https://www.mouser.fr/ProductDetail/913-4816M16A2TG6AGTR)
But you then have to either change the USB VID/PID in the program (DSview) or in the onboard eeprom so that it is seen as a "Plus" and not a "Basic" one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 26, 2018, 01:47:28 am
For those who are interested I started this thread:

https://www.eevblog.com/forum/testgear/what-is-the-state-of-the-art-for-a-reasonable-diy-la/ (https://www.eevblog.com/forum/testgear/what-is-the-state-of-the-art-for-a-reasonable-diy-la/)

to focus on providing an affordable high performance LA solution  using COTS HW and FOSS software.

PS I'll order my repair parts manana.    Sometimes it's just more fun than I can stand.  Makes me want to go hang sheet rock.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on January 26, 2018, 01:59:08 am
I have just received my FY6600 (30Mhz) from Aliexpress and ... looks like they have updated the PSU :-)

Hi Guillaume - the power supply in yours is the same as in mine (also v3.2 firmware).  It's also the same as was used in the FY3200 series, when the board was labelled v1.1; ours are v1.6, but there's no visible difference between the two versions that I can see.  I'm hoping that the change of the main board from v1.50 to 1.501 might just be the correction of the flaw in the design, and not just a "suck it and see" attempt to sort it out.

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on January 26, 2018, 02:44:58 am
The new power supply in the unit gbraux just received doesn’t instill confidence in me that FeelTech is trying to improve the FY6600. As soundtec mentioned the yellow cap on the input has been eliminated (and the resistor next to it) plus there are other changes. It appears from the photos of the 2 supplies that the ‘new’ board material is phenolic where the old one was fiberglass, which I consider better. The cut gap in the old FY6600 power supply board under the optoisolator that is a safety feature has been eliminated as has the grounding pads already mentioned. All the parts on the secondary side seem to be the same values as near as I can see except the larger of the 3 diodes near the transformer (that I assume is for the +5 supply) is physically smaller on the new board.

I get the feeling that the new supply isn’t better at all and they just cost reduced it to save a few more cents and it certainly won’t improve the performance at all and it could be worse.  Using the same supply that is used in the FY3200 series certainly would be a cost cutting move. I wonder if there are other similar changes to the main board, it would be interesting to see side by side photos to see. My guess the main board has remained the same.

So far my FY6600 is still working but I have my fingers crossed.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 26, 2018, 07:11:33 am
Hi. I am new to the forum, so a big hello from Paris, France.

I have just received my FY6600 (30Mhz) from Aliexpress and ... looks like they have updated the PSU :-)
I also ordered some IEC connectors at the same time ... but I won't bother making the ground hack : Ground-BNC to Ground-Earth = 300mV :-)

Did you measure AC or DC?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on January 26, 2018, 08:49:32 am
This one : https://www.mouser.fr/ProductDetail/913-4816M16A2TG6AGTR (https://www.mouser.fr/ProductDetail/913-4816M16A2TG6AGTR)
But you then have to either change the USB VID/PID in the program (DSview) or in the onboard eeprom so that it is seen as a "Plus" and not a "Basic" one.

Whoaa €20 shipping, that is steep. Got 1 spare by coincidence? It would make a nice way of tackling the Feeltech hobby board :)

Where did you change these in the DSview? in the source code?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 26, 2018, 09:07:29 am
Are you sure? I get a "this product ships free" message for mouser. Did you check mouser.nl or mouser.fr?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 26, 2018, 09:08:33 am
@everybody - sorry some family thing to do got hold of my time, now I'm done, so back to our business.

@DerKammi - Fleabay to the rescue, Mouser, Digikey and friends have very fast and reliable shipping, but also very expensive. It's worth getting lots of stuff to offset the transport costs. They really are "en-gorre" sellers mostly.

@fremen67 - Thanks for the extra captures, I was wondering how is the FPGA detecting between reada and writes, I see on my captures that there are two CS cycles, one with the address CD goes up and then goes down again for data. Anyway, I'll have a full week-en, the DS Studio compiled nicely on my Ubuntu 16.04.

@rhb - I'll add to the LA topic you've created, I'll post soon the github to the code of the seller along with schematics of the board I've chose, call for features and some ideas for high-speed, high-impedance, pods, both active and passive. I think there are enough "cheap affordable" analyzers that on anything over 33MHz are useless, time to try a mid-range design with COTS stuff.

@Guillaume To me the new PS doesn't look way better, and frankly, the voltage gradient against ground of 300mV looks waaay too good even for hi-end unearthed SMPS. 


 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on January 26, 2018, 09:32:38 am
Are you sure? I get a "this product ships free" message for mouser. Did you check mouser.nl or mouser.fr?

I'm afraid the warehouse is in France, under 50 I get 20 shipping.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on January 26, 2018, 09:50:43 am
Oh yeah. When I actually press "order" they add the usual 20. Sorry.
But why the highlighted "ships free" on that page? Weird marketing.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: 001 on January 26, 2018, 07:23:38 pm
I`m crasy with 25 pages tread   |O

But tell me in two words please:

Is item have some big problems exept stupid power supply ground?
Is it good for money?
Why nowbody didnt rehouse it in metal enclosure with external quiet 60Hz transformer PS?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on January 26, 2018, 07:45:21 pm
I`m crasy with 25 pages tread   |O

But tell me in two words please:

Is item have some big problems exept stupid power supply ground?
Is it good for money?
Why nowbody didnt rehouse it in metal enclosure with external quiet 60Hz transformer PS?

1.) Is item have some big problems exept stupid power supply ground?  Yes, it has the problem that it breaks itself for no reason if you turn it on too many times (i.e. it has a very limited lifespan)
2.) Is it good for money? If the above problem is fixable, yes.  Otherwise, no.
3.) Why nowbody didnt rehouse it in metal enclosure with external quiet 60Hz transformer PS? People have done that
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 26, 2018, 07:57:16 pm
@001: To make it short for you:

The signal parameters of the generator are very good for the price IF/WHEN this thing behave according to the specification, measurements have been made with pro equipment and I've actually heard the signal in hi-end transceiver. It's very clean and stable and only on high levels on 50ohm load you start hearing the power supply and distortions. The modulation and usability is very good and the PC software control it, it's clumsy but usable. The external USB control interface looks like an ASCII command serial port, so it can be controlled from different other device. The good new end here !!!

The bad news:
The power supply is a miserable, unstabilized, ungrounded POS, and noisy under load. It leaks high voltage on the floating ground and has to be grounded and/or replaced with an stabilized +/-15V, +5V stabilized power supply, no discussion here. Ground this shitty POS PS or better replace it. This alone will increase the quality of the signal, especially under load at high levels. the output operational amplifiers could be tweaked and replaced with two independent one, same with the oscillator, could e replaced with stable external reference. This will give you some minor but useful improvements.

 THE MISERABLE BAD NEWS AND THIS IS WHY FEELTECH IS A BAD COMPANY THAT DISRESPECTS THE CUSTOMERS

As others have said, the thing has a terrible firmware flaw and it self-destroys after some power-cycles, and we're fighting and struggling either reverse or reproduce the front panel firmware, Feeltech put there some kind of "salami pricing" to differentiate models.
They WILL NEVER RELEASE AN FIRMWARE UPDATE AND IF YOU DO ANY MODIFICATION YOU EITHER HAVE TO THROW IT AWAY OR PARTICIPATE ON OUR EFFORTS HERE !!!
If you want a plug'n play generator and you're not prepared for serious efforts and frustration, buy something else, don't buy it !!!
 YOU HAVE BEEN WARNED !!!

   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on January 26, 2018, 09:03:10 pm
As others have said, the thing has a terrible firmware flaw and it self-destroys after some power-cycles, and we're fighting and struggling either reverse or reproduce the front panel firmware, Feeltech put there some kind of "salami pricing" to differentiate models.

Just out of curiousity, what does "salami pricing" mean?  I've never heard the term used before.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 26, 2018, 09:27:21 pm
@SMB784: AFAIK, "salami pricing" or "salami slicing"means having a product, that have its intrinsic capabilities limited arbitrarily and then the limitations are removed after paying piecemeal, like all those scopes and analyzers and other TE that have 100% same hardware but features (sometime trivial) blocked and unlocked for extra cash, so the fully featured device it's the salami and you slice it for the customers to buy 100g at a time (only when he's starving, of course).
This proved to be a good sales and marketing strategy, because it was statistically proven that slicing the features and selling them separately brings more profit then selling the device fully featured ( for example, one scope/SA fully featured costs less than the same scope  + later bought licenses/unlock codes for the feature).
In our case, Feeltech decided copy this strategy and launched 2-3 models with the EXACT same hw, but frequency ranges limited arbitrarily (20, 30, 60MHz or such).
But but being beginners at this game, they put the limitations in the  front panel MCU firmware and because the platform has no DRM, they 've released different priced versions with the MCU flush fully locked and no possibility of upgrade.
This would have somehow worked, but their firmware is buggy as hell and crashes, corrupting the data structures of the flash, and without updates possible on-site, the salamification strategy ;) failed.

 Cheers, DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on January 26, 2018, 10:57:14 pm
Good explanation, I understand now.  Thanks for that clarification.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on January 26, 2018, 11:19:00 pm
Didn't know about the phrase "salami pricing", although I got  sieben Jahre Deutchkurs abgeschlossen.  :)

(Or is it a German specialty word phrase? Never heard of it.)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on January 26, 2018, 11:21:29 pm
This might be considered "salami pricing". The company I used to work for made a product to read electrical power meters. They also made a reader/programmer to program these same meters. The reader sold for $3000 and the reader/programmer for $5000. I worked on this line of products so I knew the only difference was the code contained in the eprom that told the unit what to do. I asked a marketing representative how they could justify charging that big difference for basically no physical difference and he told me they were charging for functionality.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: 001 on January 27, 2018, 12:34:25 am
Sanx a lot!

What is alternative avaliable at EBAy?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 27, 2018, 10:00:11 am
Sanx a lot!

What is alternative avaliable at EBAy?

Well on need to sank me, the problem is that are really not  many acceptable AWGs in this price range, the FY6600 it's a sane design with possibilities of improvement by a hobbyist, or else nobody will give a rat behind for it.
What sinked it as a product, were the miserable decisions of FeelTech, a company that doesn't care about customers and wanted to squeeze the last cent form a good design, by Chinese-fying it.
IMHO if they would have chosen a sane power supply, with good mains isolation, suitable for a test instrument, the price increase would have been, like 10EUR, at most.
If they would have assembled the hi-quality components (the PCB has places for them) that would have added an extra 10EUR, maybe.
Adding a way to update the firmware, or at least opening the protocol to the signal board, would have not cost them a cent and all of the bad reputation would be gone, "oh well, we've screwed this firmware version, kindly please update", hell, they could have put this option in their PC control software.

But they've really wanted to sell the same hardware at different prices, and they thought that locking the firmware will protect them against the customers "upgrading" the devices and competition copying their design, that is laughable, on the chosen hardware it would have taken a week at most to a dedicated Chinese "replica laboratory" to build such a replica. But how much cheap a similar hw replica could cost, the profits on this design sold at 100EUR end price were anyway razor thin and the competition has build one rather similar device with R/2R DACs that will now slowly erode their market, even if IMHO the ADC solution is better.

They should have take a hint from their betters, Rigol and Siglent, that were not making a fuss about the enthusiasts modifying their "salami" to get all the slices ;), because they've realized that in professional environment it's not worth the time spent and loss of warranty, and if you have actual and future professionals getting used with your stuff, they will recommend it in the workplace. Microsoft realized this long time ago.

 So yeah, I can't really recommend a similar replacement, if you get the FY6600 with the 3.2 firmware, it's somehow OK (no reported catastrophic crashes), after the modification of the PS and the previously described stuff, it depends on how much you're convinced that voting with the wallet can convince a company to change it's ways.

 For me it's a nice hobby project, I've improved my old hw knowledge (too much sw dev in the day job), got reasons for a new cool project (a high performance LA), meet nice people and my inner geek had fun looking on how they implemented their stuff and trying to reverse it. And in the end, I may also got an usable AWG and signal generator out of it ;). So it's worth the money and time spent.

YMMV of course  :D

 Cheers,
 DC1MC


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on January 27, 2018, 10:01:34 am
Hi Guillaume,
welcome to the forum .
That sounds like good news ,maybe the original supply was responsable for the dodgy batch ,
I said I might as well repost this image from a previous comment for the purposes of comparison.
not the greatest of images ,maybe theres a better one to be found .


Hi folks
(and welcome to Guillaume, the french team is growing day after day  :D)

Regarding the PSU photo you posted here, it doesn't sounds good at all imho.
The batch or the provider of the PSU seems different, but as a result it's always a holy piece of shit.
10µF as a primary cap is undersized, a 33µ or 47 value should be a minimum.
No reasonable quality highspeed diodes and low ESR capacitors on the ouptput stage, even if it costs some more cents, it would be a positive gamble for Feeltech.
Proceeding like Feeltech is doing with the PSU design is a total mistery for me.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: 001 on January 27, 2018, 12:39:58 pm
--

thanx again!


Does it mean what firmware can fail randomly? Is it possible to dump it?
Is a firmware fail a part of Planned obsolescence strategy?
How many  bricked FY6600 You know?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 27, 2018, 05:26:17 pm
@001:
Yes, it's very possible to fail, totally random and unexpected, because FeelTech don't feel anything for its customers.

No, the firmware it's locked, there is a paper from the German Fraunhoffer Institute describing an attack against flash reading protection (with code for the exploit device), so far nobody, AFAIK, managed to do it for this chip.

No, that was a stupidly done sales strategy that backfired, the bad company FeelTech representative (that actually STARTED this thread to advertise their device !!!)  even admitted that their NEXT model will have upgrade capabilities, like somebody will pay AGAIN for their stuff, but prolly not a problem, they we'll change the company name as usually in China.

At least 4 bricked devices in this thread, mine with firmware 3.1 just destroyed so far the stored sine waveform but their latest software can attempt to repair it that, most of the people had them returned via EBAY or Amazon policies, the problem is with the people that already modified their device's power supply and lost warranty 2 weeks later. Even the persons who didn't modify the devices and had them auto-bricked had to deal with hostile and non-cooperative distributors.


@everybody else - Prepare for FUUUUUUN WITH REGISTEEEERS  in the next post !!!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 27, 2018, 10:15:28 pm
Fun with Registers: Episode 3 "Off and On"

The CH1/2 switching procedure does two large IDENTICAL transfers (T1 and T2) and a small one that actually matters (T3)

Let's start with T3, 21 register writes.

1D:00000002
24:00000010
2B:00000A50
2C:000007FF
06:000000C4
06:000000C4
2D:00000DD1
2E:00000000
02:000186A0
01:00000000
04:000186A0
03:00000000
2F:00010000
30:00010000
05:00000020
38:07FFDFFF
39:07FFDFFF
08:000FFFFF
09:000FFFFF
37:00000001
37:00000000


This is actually the "classical" CH1/2 parameters setting, from the previous episodes you've seen that this train of registers comes when one rotates the digitizer button and change a channel parameter, it could be possible that actually this is all you need to set the parameters, at least in sine wave.

##### Commercial break >:) #####

T1 and T2 are two identical transfers of 4 identical large-patterns, they seem to be used to build the waveform displayed on the LCD by sampling 100 times the FPGA waveform RAM and also a mystery part of the RAM that could be a calibration constant.
Each large-pattern has 100 basic-patterns, or samples, the address/block from where to read is given in the register 0x12 (at least), the readback is done via register 0x0E, another register that it's read is 0x18, but it always return 32bit of 0, could be a way to prime the SPI block or maybe some status.
The RAM addresses/blocks in the register 0x12 are always spaced at the 0XA2 offsets.

The waveform samples are nice and clear, with some peculiarities (the wave first value doesn't start from 0), but the the accompanying calibraton/offset/mystery constant is vey strange, please see the plots. Please see the attached plots.


Basic-Pattern (sample) element:

12:00063F5B <- Setting the sample point address, waveform.
0F:00000001 <- Write op, unknown purpose.
0F:00000000 <- Write op, unknown purpose.
18:00000000 <- Read but result is always full 0.
0E:XXXXXXXX <- Read operation there, waveform value.
12:00063F5A <- Setting the sample point address, calibration ?
0F:00000001 <- Write op, unknown purpose.
0F:00000000 <- Write op, unknown purpose.
18:00000000 <- Read op, always 0.
0E:XXXXXXXX <- Read op, calibration constant value ?

Notes:
At the large patterns start there is a small 4 register op header, purpose unknown:
14:00000000 <- Write op, unknown purpose.
16:00000000 <- Write op, unknown purpose.
18:00000000 <- Read op, always 0
18:00000000 <- Read op, always 0

All uses data files are attached for independent verification, plots of one full waveform sample and the corresponding calibration offsets/constants are attached.
All data derived from member fremen67 capture file fy6600_CH1_OFF_ON_100Mhz_FULL.dsl form a previous message.

 Cheers and tired,
 DC1MC
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 28, 2018, 05:46:40 am
Sorry for the lack of bit bashing from me but the shack is currently over 45 degrees again  :phew:

I have ordered a bus pirate to play with this as well
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 28, 2018, 08:56:42 am
Sorry for the lack of bit bashing from me but the shack is currently over 45 degrees again  :phew:

I have ordered a bus pirate to play with this as well

@beanflying, oh the injustice of weather distribution, here in between two large rivers  I have to deal with Gothic/Gotham weather for 10 weeks now, it's a perpetual dusk and then night, when the bloody hurricane was blowing the sky cleared for 2 hours and then the ceiling closed again, it drives me crazy, there a good chance to go to a tanning salon just for the UV and vitamin D.
About your choice of LA, Bus Pirate, I kind of lost the contact with whatever community stuff, but you're sure that it can stream reliably at 50MHz at least 6 channels and has RLE in sample mode?
Or else it's useless for our SPI bus-pirating purposes on FY6600.

@fremen67 You are the savior Mua'Dib, until my LA project bears fruits you're the only one who got reliable captures, in need the following captures:
 - Setting amplitude/frequency message (start capture, trigger on -CS and rotate the encoder one position), it seem that the setting message on 3.2 has 21 register operations instead of 20 and I want to see the difference. It will help with the Episode 2- "Hopey and changey!
 - The same setting message for duty cycle value when the wave it's square, to activate this function, the duty cycle register it's assumed but not proved, kindly please try to get the extremes and somwhere in the middle.
 - BIG ONE: Capture the process process of switching the wave, form sine to triangle, and triangle to square, if's the only big deal on how to load waveforms, there is also the custom waveform issue but we leave this for later.
Thanks a lot and sorry that I put this burden on you, for the moment no other capable LA is hooked to an 3.2FY6600, made by FeelTech - "Our Bugs it's Your Problem".


@everybody - I'm going to tackle the startup sequence, wish me luck, 'cause it's looking a lot like work !!!
 
 Cheers,
 DC1MC
 


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: texaspyro on January 28, 2018, 07:06:32 pm
You REALLY don't want to be using a logic analyzer that samples the signals asynchronously.  You want one where the data lines are clocked in by the SPI clock (preferably qualified by chip select).  That way you only transfer data that is relevant and at a 18 MHz max data rate. 

If you have an analyzer with enough channels, maybe build a shift register front end and clock the whole (48-bit?) transfer into it and have the analyzer grab those.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 28, 2018, 07:27:14 pm
You REALLY don't want to be using a logic analyzer that samples the signals asynchronously.  You want one where the data lines are clocked in by the SPI clock (preferably qualified by chip select).  That way you only transfer data that is relevant and at a 18 MHz max data rate. 

If you have an analyzer with enough channels, maybe build a shift register front end and clock the whole (48-bit?) transfer into it and have the analyzer grab those.

In theory it works, in practice not so much, we need here the temporal information as well and unfortunately not all the operations are 3 x16bits over one CS low, the read transfers are first transfer register address follower by one or more 2x16bits per CS low value read operations. So IMHO, no way around a good minimum 50MHz sampling, RLE and streaming LA.

But if you have the FY6600, you can give it a try and post some captures, I will decode them for you, start with short message, like value changes that are just 20-21 register operations.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: texaspyro on January 28, 2018, 09:47:43 pm
For the protocol decoding, I doubt you need any temporal data.   You just need the data that is transferred.  Also, you could use just an 8-bit shift register... that would cut the data rate down quite a bit.  I've been using logic analyzers and protocol decoding for over 40 years.  Unless there is something silly going on with the FY6600,  using an asynchronous capture mode is the wrong way of going about it.

I don't have a FY6600 to test, or time to do it if I had one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 29, 2018, 06:37:30 pm
Hello everybody, quick update for the startup sequence, it mostly consists of endless reads, WITHOUT sending an address, the readback values are some times a string off zeros or a string of 0x00000001.

Fremen67, guys, you're still around, not much activity over WE :(.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on January 29, 2018, 08:24:36 pm
The unit is finally in Holland. So yes pretty quiet :D Need it on the doorstep....
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: gbraux on January 29, 2018, 10:05:57 pm
Hi. I am new to the forum, so a big hello from Paris, France.

I have just received my FY6600 (30Mhz) from Aliexpress and ... looks like they have updated the PSU :-)
I also ordered some IEC connectors at the same time ... but I won't bother making the ground hack : Ground-BNC to Ground-Earth = 300mV :-)

Did you measure AC or DC?

Oups ! My bad, was measuring DC ... now measuring 84V AC  :-(
Just added an IEC plug (and as the ground connector is not there anymore on the refreshed PSU, I directly soldered earth-ground to the back of the PCB).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 29, 2018, 10:13:28 pm
I think my SB may windup inside the GDS-2072E  Just need the proper signals and a map of the state machine.  Integrating it with the GDS-2000E software is more work, but preferable in the long run.  One could do a lot of cool stuff with the addition of a GPSDO timebase.  Full measurement  up to 6 M for under $400?  Not bad.  But I think I'll buy a JDS for regular use unless someone comes up with a way to reflash the FT devices with a usable image.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 29, 2018, 10:20:37 pm
Fremen67, guys, you're still around, not much activity over WE :(.
Well this is not exactly what I would say.

I decided this Saturday evening to have a one hour session on the FP-FPGA protocol decoding to see what I could find. What happened to me was worse than being attracted by a black hole. My last two evenings where long… my last to nights were short. This thing is more addictive than drugs.
First I decided to add the nor flash into the game. Cybermaus already explained precisely how it was organized, containing the predefined waveforms and the arbitrary waveforms as well. As I did a backup of the flash, I already had the header pins soldered. A quick check at the Flash_CLK pin showed that it was running @ 20Mhz. So definitely a separated SPI bus that has to be connected to the FPGA. Five pins connected later, and after adding a second SPI protocol in the LA configuration, I was able to see the flash talking synchronized with the FPGA-FP telegrams when switching waveforms. So far so good. But that was just the beginning of the black hole thing… Long story short..The service telegrams are now decoded  (containing mode, state, setpoints of CH1&CH2) and the Read mechanism from Flash to FPGA, From Flash to FP and Write from FP to Flash is now clear, that is:
1-   Direct transfer requests of waveforms from Flash to FPGA (FP don’t see the values)
2-   Read requests from flash to FP, FPGA being a letter box
3-   Write requests from FP to flash, FPGA being again a letter box (when using the PC software)

All the captures I made showed a combination of those mechanisms in Power On, ON/OFF, waveform selection, setpoint modification telegrams.
There is also a specific telegram when in Measure Mode but it is much simpler and smaller, for reading counter, frequency and the 2 half parts of a cyclic input signal.
You will find attached a description overview of the registers, new ones, some of them still to be identified, others already identified by DC1MC who also already explained the register write mechanism.
With this file, every one should be able to decode almost all the messages that we captured. The main missing registers are used during the power ON sequence, I suppose for initialization purposes but no clue for them at the moment.

I will post some other documents later on too that might help understanding the mechanism and will also try to explain more precisely the read/write protocol.
Not sure how long I will stay awaken ...
Enjoy!

Hello everybody, quick update for the startup sequence, it mostly consists of endless reads, WITHOUT sending an address, the readback values are some times a string off zeros or a string of 0x00000001.
Should be crystal clear now... :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on January 29, 2018, 11:54:16 pm
Fremen67, guys, you're still around, not much activity over WE :(.
Well this is not exactly what I would say.

I decided this Saturday evening to have a one hour session on the FP-FPGA protocol decoding to see what I could find. What happened to me was worse than being attracted by a black hole. My last two evenings where long… my last to nights were short. This thing is more addictive than drugs.
First I decided to add the nor flash into the game. Cybermaus already explained precisely how it was organized, containing the predefined waveforms and the arbitrary waveforms as well. As I did a backup of the flash, I already had the header pins soldered. A quick check at the Flash_CLK pin showed that it was running @ 20Mhz. So definitely a separated SPI bus that has to be connected to the FPGA. Five pins connected later, and after adding a second SPI protocol in the LA configuration, I was able to see the flash talking synchronized with the FPGA-FP telegrams when switching waveforms. So far so good. But that was just the beginning of the black hole thing… Long story short..The service telegrams are now decoded  (containing mode, state, setpoints of CH1&CH2) and the Read mechanism from Flash to FPGA, From Flash to FP and Write from FP to Flash is now clear, that is:
1-   Direct transfer requests of waveforms from Flash to FPGA (FP don’t see the values)
2-   Read requests from flash to FP, FPGA being a letter box
3-   Write requests from FP to flash, FPGA being again a letter box (when using the PC software)

All the captures I made showed a combination of those mechanisms in Power On, ON/OFF, waveform selection, setpoint modification telegrams.
There is also a specific telegram when in Measure Mode but it is much simpler and smaller, for reading counter, frequency and the 2 half parts of a cyclic input signal.
You will find attached a description overview of the registers, new ones, some of them still to be identified, others already identified by DC1MC who also already explained the register write mechanism.
With this file, every one should be able to decode almost all the messages that we captured. The main missing registers are used during the power ON sequence, I suppose for initialization purposes but no clue for them at the moment.

I will post some other documents later on too that might help understanding the mechanism and will also try to explain more precisely the read/write protocol.
Not sure how long I will stay awaken ...
Enjoy!

Hello everybody, quick update for the startup sequence, it mostly consists of endless reads, WITHOUT sending an address, the readback values are some times a string off zeros or a string of 0x00000001.
Should be crystal clear now... :)

That is some excellent work there, Fremen!

I just got my device in the mail today, and I just found out that it is version 3.1.

With that being said, in light of Fremen67's work, can we get an update on what still needs to be done?  What tasks are left, and what unknowns still exist?  I would like to contribute, but I don't yet know what I should be doing.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 30, 2018, 12:50:43 am
With that being said, in light of Fremen67's work, can we get an update on what still needs to be done?  What tasks are left, and what unknowns still exist?  I would like to contribute, but I don't yet know what I should be doing.

There are still some registers to discover (I just realized I forgot to update my document with Reg 0x37... for the next time).

Registers definition are the keys to understand what is done on a macroscopic point of view. To move on, we need now to have a macroscopic description of what is done by the FP for each possible action on the FP.

A macroscopic description would be: "When changing the frequency on a sine wave, the FP sends a service telegram which includes: modulation status , CH1&CH2 offsets, ..." rather than: "When changing the frequency on a sine wave, the FP writes reg0x1D, Reg0x24, Reg0x2B, Reg0x2C, ...."

Another example: If you select a new Sine waveform, you could describe it this way:
"The FP:
1 - Reads CH2 waveform from flash
2 - Reads CH1 Waveform from flash
3 - Wait about 58ms
4 - Sends a service telegram with modulation status, ...
5 - Request the FPGA to read a sine waveform from the Flash
6 - Sends a service telegram with output status, ..."

This would the base for a new FP program.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 30, 2018, 01:14:33 am
@DC1MC
You will find attached the files you requested (plus some extra).
For the waveform loading captures on CH1, I selected ARB63 on CH2. This is an empty waveform, which eases the analysis (you will notice with MISO from FP SPI). It  is also stored in Flash so you will see CH2 transfer).

There is definitively something strange with the TRGL waveform :
- When switching from DC to Triangle, The FP reads CH2 waveform, than CH1 waveform (that is TRGL) from flash but does not request FPGA to update its waveform from flash
- When switching from Ramp to Triangle, The FP reads CH2 waveform, than CH1 waveform (that is TRGL) from flash AND does request FPGA to update its waveform from flash (you see the transfert)

I wonder if it's a new behaviour on v3.2 or if it's already like that on V3.1 ...

The other waveform loading captures also show which are in flash and which are not.

The duty cycle modifications on a square waveforms look very interesting!

Good luck. You will see that the flash SPI under the other signals will change your live  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 30, 2018, 08:34:45 am
Fremen67, guys, you're still around, not much activity over WE :(.
Well this is not exactly what I would say.

I decided this Saturday evening to have a one hour session on the FP-FPGA protocol decoding to see what I could find. What happened to me was worse than being attracted by a black hole. My last two evenings where long… my last to nights were short. This thing is more addictive than drugs.
First I decided to add the nor flash into the game. Cybermaus already explained precisely how it was organized, containing the predefined waveforms and the arbitrary waveforms as well. As I did a backup of the flash, I already had the header pins soldered. A quick check at the Flash_CLK pin showed that it was running @ 20Mhz. So definitely a separated SPI bus that has to be connected to the FPGA. Five pins connected later, and after adding a second SPI protocol in the LA configuration, I was able to see the flash talking synchronized with the FPGA-FP telegrams when switching waveforms. So far so good. But that was just the beginning of the black hole thing… Long story short..The service telegrams are now decoded  (containing mode, state, setpoints of CH1&CH2) and the Read mechanism from Flash to FPGA, From Flash to FP and Write from FP to Flash is now clear, that is:
1-   Direct transfer requests of waveforms from Flash to FPGA (FP don’t see the values)
2-   Read requests from flash to FP, FPGA being a letter box
3-   Write requests from FP to flash, FPGA being again a letter box (when using the PC software)

All the captures I made showed a combination of those mechanisms in Power On, ON/OFF, waveform selection, setpoint modification telegrams.
There is also a specific telegram when in Measure Mode but it is much simpler and smaller, for reading counter, frequency and the 2 half parts of a cyclic input signal.
You will find attached a description overview of the registers, new ones, some of them still to be identified, others already identified by DC1MC who also already explained the register write mechanism.
With this file, every one should be able to decode almost all the messages that we captured. The main missing registers are used during the power ON sequence, I suppose for initialization purposes but no clue for them at the moment.

I will post some other documents later on too that might help understanding the mechanism and will also try to explain more precisely the read/write protocol.
Not sure how long I will stay awaken ...
Enjoy!

Hello everybody, quick update for the startup sequence, it mostly consists of endless reads, WITHOUT sending an address, the readback values are some times a string off zeros or a string of 0x00000001.
Should be crystal clear now... :)

Holly rotating cow on 3D gymball, fremen67 are you a younger version of me  ^-^ ?!?!  I remember ca 35 years ago disassembling the Sinclair Spectrum ROM with just a pencil, a paper notebook and bootleg copy of Z80 manual. Painful, but somehow you wake up  in an excellent mood, better than the other thing ;)

That's a real effort here people, the WE silence was bringing us so much stuff, thank you so much, chapeau bas  ;D. I was coming very late yesterday from the Arbeit, and only this morning I had a look at the headmounted glasses post responses, and observed that  there is one more post in the FY6600 topic and casually looked on it, and by Jove, now I have to take  some hours off !!!

One quick thing about the register 0x25 (50 million) and 0x26 (500million), they seem to be correlated with the 50MHz oscillator that is used as timebase, in a joyful future we may be able to replace it with a stable 10MHz source, and if these are the only modifications, jackpot  >:D !!!  Most likely they are just time base for the frequency measurement, but one can dream :).

I would look in to the triang waveform, can you switch sometime form sine to triang, to see it this time at least it updates the waveform in RAM, or it could be as well yet another bug from our FeeTech guys.

The common measurement along with the flash SPI was really perfect, we need to see edges, where this shitty fw screws thing. I'm really curious where in the MCU firmware are writing operations, because I can understand screwing up the external flash, but I don't understand what had happened with the internal one ?!?!?

What we need now:

 - Blue pills board to do a quick serial-to-SPI converter, I'm curious if the Dupont pins are fitting there, then there is no need for connector.
 - A set of basic routines, I'll list them there for reference:
 = Wait_For_Ready.
 = Writer_register
 = Set_Register_Address
 = Read_Register
 
And then one level higher routines:
 Set_Freq
 Set_Level
 Set_Offset
 Set_Phase
 ---
 and so on
(for the development purposes, these can be emuleted for the moment in a PC program that discuss with the blue pill via serial)

And of course the telegrams ( I like this word, better thane the messages that I was using)


If we get some good news form the members that promised to extract the schematic, we can focus afterwards on how the LCD is driven and see if in the yuuuge library collection from STM there is something compatible, and get rid of the ugly fonts  :box:.

Also in the end ( I have now to run ), it would be sooo nice to have a member with a 30MHz or lower device, trying to program the 59.999 MHz :), revenge at last  >:D

 Cheers,
 DC1MC



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on January 30, 2018, 11:39:46 pm
Holly rotating cow on 3D gymball, fremen67 are you a younger version of me  ^-^ ?!?!  I remember ca 35 years ago disassembling the Sinclair Spectrum ROM with just a pencil, a paper notebook and bootleg copy of Z80 manual. Painful, but somehow you wake up  in an excellent mood, better than the other thing ;)
Younger ... well... as I also remember having done the same kind of stuff on the ZX81 (the model before the Spectrum) in 1981, that is ca 37 years ago, (and I also had the same tools  ;D) you could also be the younger one  ;)
I am pretty sure that I still have the ZX81 with the original manual and some tapes somewhere in the attic...

I would look in to the triang waveform, can you switch sometime form sine to triang, to see it this time at least it updates the waveform in RAM, or it could be as well yet another bug from our FeeTech guys.
No problem when switching directly from Sine to Triangle, it updates the waveform in RAM.

What we need now:

 - Blue pills board to do a quick serial-to-SPI converter, I'm curious if the Dupont pins are fitting there, then there is no need for connector.
 - A set of basic routines, I'll list them there for reference:
 = Wait_For_Ready.
 = Writer_register
 = Set_Register_Address
 = Read_Register
 
And then one level higher routines:
 Set_Freq
 Set_Level
 Set_Offset
 Set_Phase
 ---
 and so on
(for the development purposes, these can be emuleted for the moment in a PC program that discuss with the blue pill via serial)
I have a STM32 dev board that I used some years ago. It may even be the same CPU as the FP. I will hock it and try to send some SPI commands. I would like to check the read sequence with CS RS. I will try with Reg0x18 (cyclic flash status update) as it seems to be the easier to begin with.

Cheers!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on January 31, 2018, 07:33:15 am
@fremen67 OK then, I'm the low energy youngster then  :-DD.

Nice work with the triangle wave, then it's yet another bug form FeelTech.
I'm also wondering if those really insane repetitions are really needed, the endless repetitions of all the parameters for the slightest change and so on, I have a feeling that the SB programming can be streamlined a lot, this we'll also help if we're gonna improve the seeping function.

What can I say, I'm humbled, keep up the good work, if you'll be able to communicate with the SB you'll be our hero, I  came so drained form the day job and this endless gray sky it's sapping the rest of the what little energy remains :(. But I'll push myself to see this to the end.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 01, 2018, 01:29:21 am
Quick update of preliminary service telegram tests:

I hooked up a STM32 dev board directly to the Signal board on the FY6600 and was able to change frequency and amplitude  :-+

That is just a proof of concept but this is very encouraging.
The test was as follows:
- FY6600 powered on, CH1 ON and connected to a scope, sine @10Khz and 5V amplitude, LA still connected
- I disconnected the ribbon  from the FP and connected directly my dev board to it
- I downloaded the first test program to the dev board: service telegram with modified frequency @20Khz and ... bingo! 20khz on the scope.
- Second test with a modified Amplitude à 2.5V and bingo again !! 2.5V Amp on the scope.
Attached a photo of the setup, 2 functions of the test program and the first LA capture of an alien processor fooling the FPGA 8)
I think I will sleep well  8)

Code: [Select]
void test_service_telegram(void)
{
  fpga_write_register(0x1D,0x00,0x02);
  fpga_write_register(0x24,0x00,0x10);
 
  fpga_write_register(0x2B,0x00,0x7FF);
  fpga_write_register(0x2C,0x00,0x7FF);

  fpga_write_register(0x06,0x00,0x80);
  fpga_write_register(0x06,0x00,0x80);

  fpga_write_register(0x2D,0x00,0xE65); // 5.00V
//  fpga_write_register(0x2D,0x00,0x732); // 2.50V
  fpga_write_register(0x2E,0x00,0x00);

//  fpga_write_register(0x02,0x03,0x0D40); // 20kHz
  fpga_write_register(0x02,0x01,0x86A0); // 10Khz
  fpga_write_register(0x01,0x00,0x00);
  fpga_write_register(0x04,0x01,0x86A0);
  fpga_write_register(0x03,0x00,0x00);
 
  fpga_write_register(0x2F,0x01,0x00);
  fpga_write_register(0x30,0x01,0x00);

  fpga_write_register(0x05,0x00,0x20);
  fpga_write_register(0x38,0x7FF,0xDFFF);
  fpga_write_register(0x39,0x7FF,0xDFFF);

  fpga_write_register(0x08,0x0F,0xFFFF);
  fpga_write_register(0x09,0x0F,0xFFFF);
  fpga_write_register(0x37,0x00,0x01);
  fpga_write_register(0x37,0x00,0x00);


static void fpga_write_register(uint16_t chRegister, uint16_t chDataMSW, uint16_t chDataLSW)
{
  __FPGA_DC_CLR();
  __FPGA_CS_CLR();
  __FPGA_WRITE_WORD(chRegister);
  __FPGA_DC_SET();

  __FPGA_WRITE_WORD(chDataMSW);
  __FPGA_WRITE_WORD(chDataLSW);

  __FPGA_CS_SET();


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on February 01, 2018, 05:18:59 am
Cant seem to remember front side shots of the FP. Wonder what K8 did? Wonder also what chip is hiding on the lcd......

Switch is connected to PB6 on the STM btw :-\
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 01, 2018, 06:45:31 am
@fremen67 great news, nice effort. Looking good so far.

I think the LCD is a standard ILI9340/ILI9341 chip one. These are used very widely. Libraries are no issue for these.

My unit is available for pickup today, hope to get some schematics done next week.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on February 01, 2018, 06:59:07 am
Forgot to add my FP PCB was 'packed' with two washers to allow a couple of the switches to not be closed when the nuts were done up  properly :--

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on February 01, 2018, 06:59:52 am
Hello,

The K8 switch has the same function when the rotary encoder button is pressed.
Feeltech deliberately destroyed the K8 switch to prevent deformation of the facade.

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 01, 2018, 07:02:23 am
@fremen67 you're our hero, you deserve a good rest, better than this can't be.

Now I'm wondering two things:

 1) Is it really necessary to send a full telegram to change one parameter, what about just sending the SetFrequecy sequence and see if just the frequency changes ? If we can send the parameters individually, that will make a kick-ass sweeping generator /wobbler/antenna analyzer  8).

 2) What about programming 65.200MHz, what it's actually the upper limit of the sine wave, hopefully someone with a 30MHz unit will chime-in and try to program 69MHz on it, if it works I have a feeling that the 30MHz cheaper ones will disappear abruptly  >:D.

 Best regards,
 DC1MC

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 01, 2018, 07:39:53 am
I think the LCD is a standard ILI9340/ILI9341 chip one. These are used very widely. Libraries are no issue for these.
Yes that is also my first bet. It definitively has to be widely spread ans cheap. Once the FP schematic is ready, this should be easy to check.
If it's not the ILI9341, there won't be a lot more to check.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 01, 2018, 07:47:10 am
1) Is it really necessary to send a full telegram to change one parameter, what about just sending the SetFrequecy sequence and see if just the frequency changes ? If we can send the parameters individually, that will make a kick-ass sweeping generator /wobbler/antenna analyzer  8).

 2) What about programming 65.200MHz, what it's actually the upper limit of the sine wave, hopefully someone with a 30MHz unit will chime-in and try to program 69MHz on it, if it works I have a feeling that the 30MHz cheaper ones will disappear abruptly  >:D.

This will be very easy to check but I first have to code the initialization sequence in the dev board because switching the SB from FP to dev board when everything is powered ON is really not the way to go .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 01, 2018, 08:27:02 pm
Always nice having a new unit to play with and it stops with a Feeltech logo at boot (Feelbad)

Then off course opening the unit to plug in the FPGA ribbon connector and everything is Feelgood. Strange quality control these guys have :(

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Specmaster on February 01, 2018, 09:25:59 pm
Always nice having a new unit to play with and it stops with a Feeltech logo at boot (Feelbad)

Then off course opening the unit to plug in the FPGA ribbon connector and everything is Feelgood. Strange quality control these guys have :(
Well it passed the test bench OK, whats the matter with that? It just took the quicker route to you by bypassing the tester  :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on February 01, 2018, 10:23:27 pm
Always nice having a new unit to play with and it stops with a Feeltech logo at boot (Feelbad)

Then off course opening the unit to plug in the FPGA ribbon connector and everything is Feelgood. Strange quality control these guys have :(

Very thoughtful of them. Just getting it ready for you to start adding jumpers for hacking   :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 02, 2018, 08:39:34 am
How long were you staring at that logo feeling increasingly :scared: before you opened the device?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 02, 2018, 08:45:33 am
How about 1.5s.... saying "sukkels" and grabbed the cordless screwdriver :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 02, 2018, 12:46:04 pm
Cheapest FY6600-15MHz https://www.ebay.de/itm/FY6600-Dual-Kanal-DDS-Signalquelle-Arbitrarsignal-Signalgenerator-15-60MHz-mj/311950831692 (https://www.ebay.de/itm/FY6600-Dual-Kanal-DDS-Signalquelle-Arbitrarsignal-Signalgenerator-15-60MHz-mj/311950831692)

 Can it be upgraded  >:D ?

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 02, 2018, 03:10:42 pm
Once your effort to write your own firmware works, I am pretty sure yes, it can.
Equally sure that at soon after that moment the 15MHz model will no longer be sold though.

Sorry for not being active myself. Still have the intent to work on the frauenhofer hack, even though it is for the wrong chip.
But a bit busy with my dayjob at the moment. I admire your (plural) progress though.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on February 02, 2018, 04:42:48 pm
Hello,

With GPSDO 10 Mhz the accuracy of the counter measurement FY2300H is + 95hz, displayed 10.000.095 Mhz


Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: odo on February 02, 2018, 11:57:47 pm
I am thinking about buying this generator. I like the number of features of this generator for such low price, but I see one disadvantage, maybe you could help me.
I initially decided to buy JSD6600 from FeelTech competitors, they have nice looking rubber buttons on the front panel like typical bench equipment. I expect that using "foil" buttons like on FY6600 it is not so convenient as using real rubber buttons. Could you say something about this? Are they hard to use on the table? Do generator moves when you try to press buttons?

One more questions to FeelTech representative who was on the forum, I hope is still there. Do you plan to upgrade FY6600 to rubber buttons?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 03, 2018, 12:18:03 am
Hi odo,

The buttons are not as bad to use as you'd think - you just need to put your fingers on top of the case and use your thumb to press them.  Yes, the case moves around, but that's because it's so light - it would still move around if it had any other type of buttons.  Either put something behind it, or put some sticky, non-slip rubber feet on the bottom of the case to hold it a little better (or add some weight inside, like a big power transformer).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 03, 2018, 01:32:12 pm
Any body in Europe or otherwise (shipping :() who is willing to send their bricked unit or front panel to me for software testing?

I like to keep my unit working for comparison of features while testing out all functions. Will send it back when wanted or needed or when the software is up to par.
Paying €70 for a 15Mhz unit is a bit of waste in my opinion.

I finished the the reverse engineering of the front panel of my unit, just need to draw the schematics in some tool. Eagle is what I use normally for these tiny schematics.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CharlieEcho on February 03, 2018, 01:47:07 pm
Either put something behind it, or put some sticky, non-slip rubber feet on the bottom of the case to hold it a little better (or add some weight inside, like a big power transformer).

Some kind of little chock secured to the shelf or desktop behind it's front feet (underneath the unit) works too.

The membrane buttons are fine in terms of feel (although they're less durable). The encoder wheel is clicky.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on February 04, 2018, 02:08:11 am
I am thinking about buying this generator. I like the number of features of this generator for such low price, but I see one disadvantage, maybe you could help me.
I initially decided to buy JSD6600 from FeelTech competitors, they have nice looking rubber buttons on the front panel like typical bench equipment. I expect that using "foil" buttons like on FY6600 it is not so convenient as using real rubber buttons. Could you say something about this? Are they hard to use on the table? Do generator moves when you try to press buttons?

Hi odo. Welcome to the forum.

There is another disadvantage — one that could totally outweigh your button concern. If you read back some pages from here, you'll see that this generator could lose its mind unexpectedly, rendering the device inoperative. That's what all the reverse engineering discussion is about.

So, you may want to wait and see how the brave adventurers here tackle that challenge before spending your money.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on February 04, 2018, 02:47:18 am
There is another disadvantage — one that could totally outweigh your button concern. If you read back some pages from here, you'll see that this generator could lose its mind unexpectedly, rendering the device inoperative. That's what all the reverse engineering discussion is about.

...Except that V3.2, the version currently being delivered from higher turnover sources, does not seem to show this problem.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: 4thDoctorWhoFan on February 04, 2018, 02:53:54 am
Hello,

With GPSDO 10 Mhz the accuracy of the counter measurement FY2300H is + 95hz, displayed 10.000.095 Mhz


Diabolo
Well, that's horrible.  Why even bother?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on February 04, 2018, 02:58:22 am
There is another disadvantage — one that could totally outweigh your button concern. If you read back some pages from here, you'll see that this generator could lose its mind unexpectedly, rendering the device inoperative. That's what all the reverse engineering discussion is about.

...Except that V3.2, the version currently being delivered from higher turnover sources, does not seem to show this problem.

Yep. Just have to ensure that you can get that specific version. I don't know how many vendors know enough to send the right one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CharlieEcho on February 04, 2018, 04:27:42 am
95hz, displayed 10.000.095 Mhz

With the FW my unit was delivered with (3.2), clicking the encoder wheel with the selector on the frequency line (F1) changes the units between HZ, KHz, MHz, and uHz. In case anyone hasn't noticed that.

Anyone know how to change the modes the channels default to at power up? I don't really want both channels on and cranking out a ton of volts.

EDIT: Well, I don't know what I did but now I have mine starting up with the channels off, so good enough.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on February 04, 2018, 05:02:49 am
If you haven't already got one, you can get a user manual from
https://kenswu.zzvps.com/Function/Manual/FY6600%20Series%20Users%20Manual%20V2.2.pdf
I sometimes find that reading it beats thumping the front panel and swearing...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: g0mgx on February 04, 2018, 07:01:59 am
Any body in Europe or otherwise (shipping :() who is willing to send their bricked unit or front panel to me for software testing?

I like to keep my unit working for comparison of features while testing out all functions. Will send it back when wanted or needed or when the software is up to par.
Paying €70 for a 15Mhz unit is a bit of waste in my opinion.

I finished the the reverse engineering of the front panel of my unit, just need to draw the schematics in some tool. Eagle is what I use normally for these tiny schematics.

Mine isn't bricked but is definitely doing more weird things than others; I still think some of the relays are bad.

You are welcome to my unit - where are you?

Mark
G0MGX
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 04, 2018, 07:54:57 am
Any body in Europe or otherwise (shipping :() who is willing to send their bricked unit or front panel to me for software testing?

I like to keep my unit working for comparison of features while testing out all functions. Will send it back when wanted or needed or when the software is up to par.
Paying €70 for a 15Mhz unit is a bit of waste in my opinion.

I finished the the reverse engineering of the front panel of my unit, just need to draw the schematics in some tool. Eagle is what I use normally for these tiny schematics.

Mine isn't bricked but is definitely doing more weird things than others; I still think some of the relays are bad.

You are welcome to my unit - where are you?

Mark
G0MGX

Great Mark, sounds fine to me. I'm in the Netherlands. Could you check out the shipping? I'm fine with the slowboat shipping method.
Should we take it further in PM's?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 04, 2018, 12:56:52 pm
With the FW my unit was delivered with (3.2), clicking the encoder wheel with the selector on the frequency line (F1) changes the units between HZ, KHz, MHz, and uHz. In case anyone hasn't noticed that.
I had not noticed that, thanks, I do not like that standard KHz readout, and once I was stuck on uHz readout. 10000000000000uHz :palm:
Quote
Anyone know how to change the modes the channels default to at power up? I don't really wagood enough.
In the SYS->MORE menu, there is a "boot" for CH1 and CH2.
I have mine set to not start automatically also.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cdev on February 04, 2018, 01:48:13 pm
You guys should scour the old posts here, looking for promises that I vaguely remember were made that the next version they were working on would have user upgradeable firmware.

I own the next lower version, the FY3224.

It has some issues. The very very low frequencies displayed are non-accurate. It would be nice if that could be fixed.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 04, 2018, 01:53:32 pm
The vague and never followed up promises were made for the next hardware version, if will ever show up, of course that was just a marketing droid that since then never posted anything more.
The current ones will be for ever not upgradeable by the manufacturer, until a new firmware (and hope ;) ) emerge.

 So start contributing for your version with stuff, schematics, connector pins mapping, even testing the existing commands.

 Cheers,
 DC1MC
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on February 04, 2018, 02:46:42 pm
Reply #671 gives a link to a user manual for the FY6600 but that manual is V2.2 from July, 2017 and the FeelTech home page has what appears to be the latest v2.9 from August, 2017. The date on the download link for the FY6600 English manual says 2017-10-17. 

http://en.feeltech.net/index.php?case=archive&act=list&catid=6 (http://en.feeltech.net/index.php?case=archive&act=list&catid=6)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 04, 2018, 04:05:33 pm
Im still waiting on my unit to arrive .

For the purposes of experimentation and learning Ive also sent out for one of the DSO138's , contains a similar STM32 type controler chip to the FY .There is open source software available for the DSO which allows you to access an extra  analog input and two digital logic inputs on that board,  and also  a few mods to reduce the very noisey input stage . its also a simple matter to add a rotary  encoder

https://github.com/ardyesp/DLO-138

Seeing as its mostly audio I do , this unit will make a handy tool to have  for a mobile test up.
I bought a second spare perspex case and I intend to house a battery/chg ,proper analog +- rails ,and a discrete op amp based 2nd analog audio mic/line input.

Could  a dso130 board be used as a controller for the FY6600 main board ?
only the software and the push buttons would need to be added .
It seems from what ive read that we can control the main board of the FY6600 remotely with the correct usb interface .
Would it make sense to try and figure out a way to make a cheap new front panel  or how about replacing the controller chip on the FY front panel with whats on the DSO board ,then putting together our own software interface ,what about the JTS  front panel code it looks very similar too

Anyway there my ideas ,hopefully theres inspiration in there somewhere to get the ball rolling again .
 

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CharlieEcho on February 04, 2018, 04:19:36 pm
I am happy to perform whatever stepwise procedures I can on my unit, to the extent that will help out. The STM32 attack paper (https://www.usenix.org/system/files/conference/woot17/woot17-paper-obermaier.pdf) is interesting reading but I lack the skill to have much hope of implementing the authors' "cold boot" attack on my own.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: skander36 on February 04, 2018, 06:15:56 pm
Hi guys , I am also waiting for my FY 6600 .
I have found this thread shortly after I was pay for this , so ...too late .

@DerKammi did you have paid custom tax for your ? I was ordered through Banggood .

For a new control board this ready made solutions can short time or at least may help :

https://www.embedded-wizard.de/high-performance-gui-hmi-for-stm32f7-discovery.html (https://www.embedded-wizard.de/high-performance-gui-hmi-for-stm32f7-discovery.html)
With the demo version you can compile a working interface that can be uploaded to STM board .

They have even a demo of a signal generator interface here :
https://www.embedded-wizard.de/files/cto_layout/img/demo/webgl/WaveformGenerator/EmWiApp.html (https://www.embedded-wizard.de/files/cto_layout/img/demo/webgl/WaveformGenerator/EmWiApp.html) 

Or Nextion smart displays which can send commands through Serial interface
https://nextion.itead.cc/ (https://nextion.itead.cc/) - This has free IDE and serial communication .

Many appreciations about your great work !
 

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cdev on February 04, 2018, 08:25:02 pm
Maybe you should try to get refunds on your FY6600s.

Unless I'm getting something wrong, I'm gathering that ones that are working could self destruct at any time?

Do I have this right? Does its firmware corrupt itself?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 04, 2018, 08:36:32 pm
Reply #671 gives a link to a user manual for the FY6600 but that manual is V2.2 from July, 2017 and the FeelTech home page has what appears to be the latest v2.9 from August, 2017. The date on the download link for the FY6600 English manual says 2017-10-17. 

http://en.feeltech.net/index.php?case=archive&act=list&catid=6 (http://en.feeltech.net/index.php?case=archive&act=list&catid=6)

The PC control software is now also up to v5.5 (may be worth trying the repair_sine option again?), and other documents include detailed descriptions of the PC -> Device serial communication and arbitrary waveform data transfer protocols, which might come in useful.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 05, 2018, 06:59:34 am
Hi guys , I am also waiting for my FY 6600 .
I have found this thread shortly after I was pay for this , so ...too late .

@DerKammi did you have paid custom tax for your ? I was ordered through Banggood .

For a new control board this ready made solutions can short time or at least may help :

https://www.embedded-wizard.de/high-performance-gui-hmi-for-stm32f7-discovery.html (https://www.embedded-wizard.de/high-performance-gui-hmi-for-stm32f7-discovery.html)
With the demo version you can compile a working interface that can be uploaded to STM board .

They have even a demo of a signal generator interface here :
https://www.embedded-wizard.de/files/cto_layout/img/demo/webgl/WaveformGenerator/EmWiApp.html (https://www.embedded-wizard.de/files/cto_layout/img/demo/webgl/WaveformGenerator/EmWiApp.html) 

Or Nextion smart displays which can send commands through Serial interface
https://nextion.itead.cc/ (https://nextion.itead.cc/) - This has free IDE and serial communication .

Many appreciations about your great work !

I did not have to pay any tax, but that is just lucky these days due to the huge amount of packages bought by the dutch these days from China. I ordered mine from Aliexpress though.

The board you linked is a F7 board, this one has huge amount of power compared to the F1 series, can't compare at all. So fancy smooth fading GUIs are possibly not all that easy on 320x240 screens.
I'm receiving the unit from Mark to develop/test the software on, so I can make his mangled unit better :D

Maybe you should try to get refunds on your FY6600s.

Unless I'm getting something wrong, I'm gathering that ones that are working could self destruct at any time?

Do I have this right? Does its firmware corrupt itself?

The story goes in this topic that V3.1 and earlier firmware corrupt them selves randomly. The V3.2 unit up until now are OK.

I am happy to perform whatever stepwise procedures I can on my unit, to the extent that will help out. The STM32 attack paper (https://www.usenix.org/system/files/conference/woot17/woot17-paper-obermaier.pdf) is interesting reading but I lack the skill to have much hope of implementing the authors' "cold boot" attack on my own.

I ordered 4 F103 boards with the same controller from Aliexpress to controll the FPGA in simple mode but also try to hack the fuse bits with the document. Hack one the other :)

Plenty to do, and also fixing to pinball machines. These projects are not helping each other.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 05, 2018, 08:41:35 am
By luck, I also did not pay taxes. I had fully expected to and budgeted for it. Seems sometimes one does slip by, but in my experience any package bigger then a stuffed letter you should expect to have to fill in extra paperwork and add both +21% VAT and + €12 handling

---

The hard problem seems to be only V3.0. I recall no-one (as-yet) reported self-destruct problem on a V2.9 or V3.1 firmware.
The lesser problem of Sine corruption did happen on V3.1, but they included the "fix sine" option into the PC software

I think the counts are:
5 people reported self-destructed V3.0
2 people reported sine corrupt on V3.1

---

As to the redevelopment board: I am not very active so I should probably not complain and be happy with whatever comes out...

But I would like to mention that the most obvious board to redevelop for is not some "yet another" board, but simply the panel included with the FY6600
After all, if you clear the F103, it is just as good as new, and just as much/little work to program then any other STM32 F0, F1, F7 board. All we need to do is figure out the GPIO pin to button mapping, but you would have to make such a map on a completely new board also.

So my advise/request: please do all redevelopment on a F103 with similar GPIO mapping so it fits the original.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 05, 2018, 08:45:41 am
Update on my firmware extraction: (tl;dr: not good)

I spend most of this weekend on the frauenhofer 3.3 Debug Exploit attack.
- It should works on a locked F051 (but I stupidly only ordered 1)
- It works :) on an unlocked  :-\ F103
- It does not work on an locked F103

Working on an unlocked F103 is actually not as trivial as you may think:

The attack works by reading one byte per reset cycle in a race condition with the flash lockdown. You can extract the exact same one byte in the exact same method if the flash is not locking down (you simply always win the race).  And this shows that the cabling is good and your commands work etc.
Also due to the UART debugging and porting attempt (see below) I feel I am now getting a quite good understandinf of code and attack (definitely more then from just watching the powerpoint and video).

For example, this is how I learned of yet another structural difference: Unlike the F051, on the F103 the SWD (single wire debug) shares its pin with JTAG and you need to send a special bit-train to disable JTAG first. It is not impossible this bit-train is pre-warning the debug-lockdown, thus is slowing us down enough so that we always loose the SWD race. But as mentioned in previous post, it could also be that the F1 family uses a different internal lockdown logic altogether, as witnessed by the fact it does not have a RDP-2 level.

Interesting was that the frauenhofer code already had code to switch the GPIO pin from JTAG to SWD, but it was commented out. Shows that they too had been testing somewhat seriously on the F1 family. Not sure though if they corrected the timing for a 72MHz bus rather then a 48MHz one.

The reason I ordered only one F051 is I naivety though I could run the extraction code on a blue-pill F103 with my F051 as the target.
So I learned the F0 and F1 are *really* different. Even GPIO programming is using completely different methods, and porting the code is a drag.
I will order a 2nd F051 though. But to be honest, only for the learning of it, and maybe because I want to be able to say I did actually extracted code, not just did armchair research. Bug given the huge differences between F0 and F1, I have no real belief anymore on success.

---

Additional rant: I spend half the weekend fighting the wrong enemy. Turns out I had a usb-rs232-ttl cable that "somewhat" worked, enough to make me think it worked (typing; test transfers), but working erratically when driven by the F051 non the less. And no, it was not a Xon/Xoff thing. Its now cut into a thousand pieces in the bin so I never accidentally use it again.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 05, 2018, 10:02:31 am
Ahh that would be a pitty. Damn JTAG.

Changing the sequence of commands perhaps?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 05, 2018, 06:47:09 pm
Hi everybody, sorry I couldn't focus mor on this project :(, just a quick note regarding the SWI/JTAG issue:

I was wondering if the SWI and JTAG clock are independent of the CPU clock, maybe we can slow down enormously the MCU clock, like 100KHz or such and use the fastest possible clock for the JTAG/SWI if they are synchrone with their own clock ?

 Cheers,
 DC1MC

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 05, 2018, 07:38:06 pm
Like your thinking. But I wouldn't think so. The PLL is doing havoc here I'm afraid. Worth a look though feeding an external clock which will be enough for the PLL to run and start the SWI interface.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 05, 2018, 08:05:33 pm
Lol, I was looking at the clock config as I was reading this....
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 05, 2018, 08:24:17 pm
Let the PLL wobble, as long as it spits a bite it can be as bad as possible, there is no need to run any code, I hope that the SWI interface is a simpler state machine and it will suck a byte, eventually after many tries :).

 Cheers,
 DC1MC 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 05, 2018, 10:23:18 pm
Some updates: I have now written the basic functions for the FPGA (register read/write, flash erase/write/read) some macro functions (waveforms read/write and resample for display), a startup function like the original one (flash test, FPGA init, Waveform loading for the FPGA), and I am able to command the FPGA from my STM32 dev board.
I have not seen any model related limitation in the FPGA: increasing to 110Mhz the frequency of a sine wave ... outputs a 110Mhz sine wave (well, not the prettiest one  :))

As the serial protocol is documented, I have now connected my dev board to the other ribbon cable (serial link) and am working on programming the basic serial functions so that I can use the PC Software to control the FPGA through the dev board.
We should have shortly the basic tools needed to go on with the next parallel steps, which could be:

- Working on the GUI directly on the FP (which could directly use FPGA functions already tested with the serial protocol)
- Describing remaining high level functions (like sweep done by the FP...)
- Extending internal functions Library (Modulation, sweep, input, ...)
- Extending serial protocol functions
- Working on a new PC Software
- ...

Of course we will have to choose a toolchain before. At the moment I use Keil µvision with my dev board (with STM32F10x_StdPeriph_Lib_V3.5.0) but other choices could be fine as well (arduino with STM32duino for example could also be fine and easy for upgrades). We also have to see what kind of LCD is used...


But I would like to mention that the most obvious board to redevelop for is not some "yet another" board, but simply the panel included with the FY6600
After all, if you clear the F103, it is just as good as new, and just as much/little work to program then any other STM32 F0, F1, F7 board. All we need to do is figure out the GPIO pin to button mapping, but you would have to make such a map on a completely new board also.

So my advise/request: please do all redevelopment on a F103 with similar GPIO mapping so it fits the original.
Yes, and before using the FP as dev board, any STM32F103c8t6 like this one will be perfect https://fr.aliexpress.com/premium/STM32F103c8t6.html?d=y&origin=y&blanktest=0&tc=ppc&initiative_id=SB_20180205135516&isViewCP=y&catId=0 (https://fr.aliexpress.com/premium/STM32F103c8t6.html?d=y&origin=y&blanktest=0&tc=ppc&initiative_id=SB_20180205135516&isViewCP=y&catId=0)


Reply #671 gives a link to a user manual for the FY6600 but that manual is V2.2 from July, 2017 and the FeelTech home page has what appears to be the latest v2.9 from August, 2017. The date on the download link for the FY6600 English manual says 2017-10-17. 

http://en.feeltech.net/index.php?case=archive&act=list&catid=6 (http://en.feeltech.net/index.php?case=archive&act=list&catid=6)

The PC control software is now also up to v5.5 (may be worth trying the repair_sine option again?), and other documents include detailed descriptions of the PC -> Device serial communication and arbitrary waveform data transfer protocols, which might come in useful.
Yes very usefull. Even the PC software source code seems to be included.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 06, 2018, 06:59:19 am
Some updates: I have now written the basic functions for the FPGA (register read/write, flash erase/write/read) some macro functions (waveforms read/write and resample for display), a startup function like the original one (flash test, FPGA init, Waveform loading for the FPGA), and I am able to command the FPGA from my STM32 dev board.
I have not seen any model related limitation in the FPGA: increasing to 110Mhz the frequency of a sine wave ... outputs a 110Mhz sine wave (well, not the prettiest one  :))

As the serial protocol is documented, I have now connected my dev board to the other ribbon cable (serial link) and am working on programming the basic serial functions so that I can use the PC Software to control the FPGA through the dev board.
We should have shortly the basic tools needed to go on with the next parallel steps, which could be:

- Working on the GUI directly on the FP (which could directly use FPGA functions already tested with the serial protocol)
- Describing remaining high level functions (like sweep done by the FP...)
- Extending internal functions Library (Modulation, sweep, input, ...)
- Extending serial protocol functions
- Working on a new PC Software
- ...

Of course we will have to choose a toolchain before. At the moment I use Keil µvision with my dev board (with STM32F10x_StdPeriph_Lib_V3.5.0) but other choices could be fine as well (arduino with STM32duino for example could also be fine and easy for upgrades). We also have to see what kind of LCD is used...

^^^HERO^^^

A bad 110MHz sine is expected off course since the 165MHz DAC, but the limit is not there. Very nice all in all.

The display is a ILI9341 for 99% sure. The pinout is the classic 18 pin for this type op display. Link for similar display (https://www.solidrop.net/product/free-ship-5pc-lot-2-4inch-spi-tft-lcd-screen-18pin-240-320-color-lcd-drive-ic-ili9341-4io-only-for-stm32-mcu-raspberry-pi.html)

But I would like to mention that the most obvious board to redevelop for is not some "yet another" board, but simply the panel included with the FY6600
After all, if you clear the F103, it is just as good as new, and just as much/little work to program then any other STM32 F0, F1, F7 board. All we need to do is figure out the GPIO pin to button mapping, but you would have to make such a map on a completely new board also.

So my advise/request: please do all redevelopment on a F103 with similar GPIO mapping so it fits the original.
Yes, and before using the FP as dev board, any STM32F103c8t6 like this one will be perfect https://fr.aliexpress.com/premium/STM32F103c8t6.html?d=y&origin=y&blanktest=0&tc=ppc&initiative_id=SB_20180205135516&isViewCP=y&catId=0 (https://fr.aliexpress.com/premium/STM32F103c8t6.html?d=y&origin=y&blanktest=0&tc=ppc&initiative_id=SB_20180205135516&isViewCP=y&catId=0)

I'm receiving the unit from Mark today and can test all the things we need. I'm not much of a C++ hero myself but sure can monkey test the crap out of things. So if things need to be tested just send the hex file and I'll flash it once I receive my ST-Link clone this or next week.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 06, 2018, 07:31:32 am
Of course we will have to choose a toolchain before. At the moment I use Keil µvision with my dev board (with STM32F10x_StdPeriph_Lib_V3.5.0) but other choices could be fine as well (arduino with STM32duino for example could also be fine and easy for upgrades). We also have to see what kind of LCD is used..

Wow, you guys are actually pulling this off.. Very impressed

Putting this in an STM32duino toolchain is a novel but interesting suggestion. But it would mean all your code so far has to be rewritten right? Painful.
Then again, it has the advantage that people can more easily make local mods, or even do a quick temp hardcode of some sort of "special signal train" by coding very fast changes directly to the FPGA. After all, everybody and their grandmother know how to slightly mod an pre-existing Arduino program.

But it does mean the USB pins that STM32duino bootloader uses should not be used yet. Need to check that.

If it works, it would make it easier for someone else to pick up should you (heaven forbid) loose interest.
Of course, it also means there is going to be like a bazillion forks and variants on the internet.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 06, 2018, 07:44:34 am
I have not seen any model related limitation in the FPGA: increasing to 110Mhz the frequency of a sine wave ... outputs a 110Mhz sine wave (well, not the prettiest one  :))
62.5MHz should be pretty still. And 125MHz should be better then 110MHz.
Due to them being nice round numbers.

A bad 110MHz sine is expected off course since the 165MHz DAC, but the limit is not there. Very nice all in all.
The DAC is actually overclocked to 250MHz. But 4 samples per sine is really the minimum, so practically 60 (62.5) MHz would indeed be the max.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: scott0999 on February 06, 2018, 06:26:53 pm
 I don't see the firmware specified anywhere when ordering one. Any way to be sure I get the latest 3.2 firmware?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 06, 2018, 06:44:08 pm
I don't see the firmware specified anywhere when ordering one. Any way to be sure I get the latest 3.2 firmware?
Uhmm, ask the seller  :-// ? I did so, and still got 3.1, they don't give a rat behind.  :-\
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 06, 2018, 06:55:28 pm
Putting this in an STM32duino toolchain is a novel but interesting suggestion. But it would mean all your code so far has to be rewritten right? Painful.
Not really. I tried not to code it the way my grandmother would have done it  ;). The FPGA functions are in a library which does not access directly GPIOs, and low level functions calls (SPI) are macros defined outside the library in a config file.

Then again, it has the advantage that people can more easily make local mods, or even do a quick temp hardcode of some sort of "special signal train" by coding very fast changes directly to the FPGA. After all, everybody and their grandmother know how to slightly mod an pre-existing Arduino program.
That is exactly the point, except that we are just talking to the FPGA  not programming it.

If it works, it would make it easier for someone else to pick up should you (heaven forbid) loose interest.
Exactly my point again but it would be more a lack of time than a lost of interest.
I tried STM32duino and a STM32F103c8t6 for the replacement of  the VFD display of a fluke 8842A with a SSD1322 OLED display: no problems!.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 06, 2018, 07:04:14 pm
I know it was talked about, but did anyone already map out all the buttons and connections of the FB?
If not, I may have a go at that, but I do not want to be doing duplicate work.

Especially the use of PA11;12; PC12;13;14;15 may be important to figure out to see if STM32duino could run on this board (with a standard bootloader)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 06, 2018, 07:56:14 pm
I know it was talked about, but did anyone already map out all the buttons and connections of the FB?
If not, I may have a go at that, but I do not want to be doing duplicate work.

Especially the use of PA11;12; PC12;13;14;15 may be important to figure out to see if STM32duino could run on this board (with a standard bootloader)

I have, and I'm in the process of making the schematics in Eagle.
Buttons are in a 4x4 matrix on PB0..PB7

PA11 is LCD backlight
PA12 is Buzzer

PC12 does not exist

PC13 is LCD reset
PC14 not used
PC15 not used
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 06, 2018, 08:50:19 pm
Hmm, PC14/15 would be the 32K crystal. I guess there is none? Then in initialization we should ensure RTC (real time clock) uses a different source.
PC12/13 is often the dev board user button & led, but that is OK we can redefine those in the bootloader. (Where are the 3 leds anyway?)

PA11/12 is a pity though. They are for the Arduino USB sketch upload
If they are used as GPIO, we cannot use it to upload a sketch.

Alternative would be serial, but that uses PA9/10 and constantly change the BOOT0 jumper. So not easy and anyway PA9/10 are already hooked up elsewhere. I am surprised those are not the ones running to the serial header on the backside.

Yet another upload alternative would be STLink on PA13/14. Are those free at least? Probably they are, I bet its how they program in the factory.
Soldering in a standard STLink header would not be a bad idea anyway. And a clone STlink is cheap enough to permanently mount one inside the device


BTW: I thought of a disadvantage to STM32duino: it may be a low threshold. But it does not have a proper debug function where we can step through the code.
If we have to integrate a STLink anyway, maybe Keil is not so bad afterall. (I say 'we' but I am not actually writing code. This is all just musings for your consideration, fremen67)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 06, 2018, 09:09:57 pm
Just made the first draft, not all is in, but keys,leds and LCD (pdf).

Leds are for power and CH1,CH2 on/off

The ST-Link is on JK1 so that is the one to use in my opinion. Standard four pin ST-Link (image).

Serial to the back are on PA2 and PA3

I like the idea of using the Atollic TrueSTUDIO mentioned earlier in this topic, worth checking/trying out, its free as of the new version.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 06, 2018, 10:23:26 pm
Solid work guys, well done ,

Did the supplier specify which firmware you were getting DCMC? I asked the same question about my unit and got no response from the seller. Im thinking on account of weight I might not have to pay the import duties ,usually dont take a hit if its delivered via regular post either ,often sellers missquote the value as well .I ordered a new multimeter as well ,that is due tomorrow by courier ,I might not be so lucky on that parcel .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 07, 2018, 12:14:31 am
Yet another upload alternative would be STLink on PA13/14. Are those free at least? Probably they are, I bet its how they program in the factory.
Soldering in a standard STLink header would not be a bad idea anyway. And a clone STlink is cheap enough to permanently mount one inside the device
I did not use the arduino bootloader last time as the flash memory is already pretty small. I just used the STlink for download. That's a cheap and convenient solution.

BTW: I thought of a disadvantage to STM32duino: it may be a low threshold. But it does not have a proper debug function where we can step through the code.
If we have to integrate a STLink anyway, maybe Keil is not so bad afterall. (I say 'we' but I am not actually writing code. This is all just musings for your consideration, fremen67)
That's right but not really a big deal. I am more concern about the code size limitation of the free version of Keil for future developments.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 07, 2018, 12:29:12 am
Just made the first draft, not all is in, but keys,leds and LCD (pdf).

Leds are for power and CH1,CH2 on/off

The ST-Link is on JK1 so that is the one to use in my opinion. Standard four pin ST-Link (image).

Serial to the back are on PA2 and PA3
Well done :-+ Very promising!

I like the idea of using the Atollic TrueSTUDIO mentioned earlier in this topic, worth checking/trying out, its free as of the new version.
I never used it but I will try. My project should already be compatible with it.

Note: The PC Software already wants to talk to me. I just said to him I was "FY6600-60M"  when he asked ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Malvineous on February 07, 2018, 02:07:11 am
Is there a place yet where this stuff is documented?  The thread is becoming a bit long to read through to find info on the protocols etc.

If not, might I suggest someone create a GitHub repository and enable the wiki for the repo?  Then we can add interested people to the project and they will be able to document the latest info in a nice clean wiki structure for all to see.  Happy to be the one to set this up if it would help.  (GitHub account required, git skills not required, editing the wiki is web based like any other wiki.)

The reason I ask is that I'm wondering whether the serial protocol between the FP and FPGA has any unused commands, e.g. that allow the FPGA to read or write memory on the FP board.  If it did, it might be another way to dump the firmware, by sending the FP commands to read out the contents of the ROM, which won't be locked if it's the program itself performing the reads.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 07, 2018, 05:20:53 am
Sounds like a good plan Mal ,
The Github seems to be the place for it alright ,its nice to see the internet or at least one small part of it working in true spirit of sharing and open source.

Im sure some of the other contributors will be able to look into your suggestion for getting the firmware out from behind bars .
From Fremens work we have seen the high frequency limit is down to restrictions in how the front panel commands the FPGA ,so at least via the programer and some software looks like the Feeltech spoiler can be circumvented and we can all have a 60mhz AWG for the price of a 16mhz unit and the appropriate programming  tools.

You know what the funny thing about all this is , our efforts here could actually end up with Feeltech selling even more of these units ,everybody can have their cake and eat it ,win win for all .

Has anyone with a defective unit got any proper response from the factory yet ? It seems totally short sighted of the 'Feelers' just to leave you guys swinging in the wind ,when for a small cost the few who had failed units could be sorted and that in itself would make more people think about buying the product, they have to learn to play the long game to build any kind of brand loyalty .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 07, 2018, 06:51:39 am
Had a go with my account for reading only up until now.

https://github.com/DerKammi/FY6600-15-30-50-60M (https://github.com/DerKammi/FY6600-15-30-50-60M)


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: skander36 on February 07, 2018, 12:15:54 pm
I don't see the firmware specified anywhere when ordering one. Any way to be sure I get the latest 3.2 firmware?
Mine has arrived Monday and has 3.2 . It was ordered on 24 Jan.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 07, 2018, 01:34:19 pm
Wow Skander ,
That was quick ,I ordered on the 15th Jan but still no sign and I have a trail of other packages ordered mid December about half a dozen of which  still havent landed .

I was reading up a few other articles on busting open  Stm32's ,maybe another angle worth looking at might be the update for the sine
wave issue ,there must be a facility to re-write some portion of the code on the device for this to work ,so maybe its another attack vector worth considering .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: skander36 on February 07, 2018, 01:45:44 pm
Wow Skander ,
That was quick ,I ordered on the 15th Jan but still no sign and I have a trail of other packages ordered mid December about half a dozen of which  still havent landed .

I was reading up a few other articles on busting open  Stm32's ,maybe another angle worth looking at might be the update for the sine
wave issue ,there must be a facility to re-write some portion of the code on the device for this to work ,so maybe its another attack vector worth considering .
I ordered from Banggood and I have paid 1,43 E for option "European Direct Mail" .
Total Price for 60MHz version was 92.13E . Through Dutch Mail , no customs tax .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 07, 2018, 02:21:54 pm
Wow Skander ,
That was quick ,I ordered on the 15th Jan but still no sign and I have a trail of other packages ordered mid December about half a dozen of which  still havent landed .

I was reading up a few other articles on busting open  Stm32's ,maybe another angle worth looking at might be the update for the sine
wave issue ,there must be a facility to re-write some portion of the code on the device for this to work ,so maybe its another attack vector worth considering .

Some quick clarifications: the FP is master to the FPGA signal board, so there is no way for the SB to tell anything special to the FP. Also all the waveforms are stored in the external flash on the SB.
Busting open the STM32 has been tried for this version, you should look 1-2 pages back, due to the fact that the JTAG interface shares the pins with the SWI interface we're using too much time switching the interfaces and lose the race, there is still a chance to replace the STM32 quarz with external very slow clock source, but the prognosis is not so good.
So far, if there is no hidden external command over the serial line to overwrite the STM32 firmware than the only solution is to write a new one.

  So far, let's hope that our efforts for a new firmware will give results and official fw 3.2 is not too miserable.

  Cheers,
  DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pauluzs on February 07, 2018, 03:37:41 pm
Just got one from Frankfurt today, FW 3.2

After reading this tread i was curious to see what could be done.
Before doing any of the psu and clock hardware mods, it would be nice to be able to use this device with Sigrok and maybe something like gnuradio on linux.

After playing around with serial the commands as listed in "FY6600 Serial communication protocol" and having a quick glance at the pcb. It seems the ch340 and the tx/rx headers on the back are both connected to the FP. In other words i could not use the serial command with the FP disconnected.

This would be in line with the findings done by cybermaus, fremen67, DC1MC and others. Based on this we would now send all the know serial commands and capture the corresponding spi command from the FP to Winboud?
Would like to know how this communication works, (SERIAL>)FP>WINBOUND and FPGA polls winbound for changes? or does the FP Sends some kind of notification/interrupt to FPGA?

This way it would be possible to replace the FP with something else like a dev board(already done), microcontroller or do a SPI man in the middle between FP and FPGA with something like a rpi that has 2 spi ports.

Last one, if it  could be done. what would it take to have a external clock reference on one of the BNC connectors or header pins instead of modding the pcb clock circuit?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: scott0999 on February 07, 2018, 03:40:00 pm
I don't see the firmware specified anywhere when ordering one. Any way to be sure I get the latest 3.2 firmware?
Mine has arrived Monday and has 3.2 . It was ordered on 24 Jan.

sweet where did you order from?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: skander36 on February 07, 2018, 03:59:18 pm
Romania.
Two posts above .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 07, 2018, 06:33:28 pm
Ok, I think I am ready to close the firmware readout topic.
My 2nd STM32F051 board arrived, and as expected, I can simply reproduce the frauenhofer result, and readout a RDP-1 protected board.
(see images)

It also means my setup is correct, and so the same method cannot be used on a F1 board.
Not unexpected, but at least I now also actually hacked a F051 board, so give my failed F103 attempts some credibility.

tl;dr; some more insight why F0 != F1


Busting open the STM32 has been tried for this version, you should look 1-2 pages back, due to the fact that the JTAG interface shares the pins with the SWI interface we're using too much time switching the interfaces and lose the race, ......

Well, to go into detail: That is not *the* reason, it is merely *one* of the many possible reasons. It could really be any of these:

- F0 vs F1 have different protection implementation, F0 has 2 levels, F1 has 1 level  - (die difference)
- F0 vs F1 have different debug implementations. F0 has only SWD, F1 has JTAG and SWD - (die difference)
- F0 vs F1 have different debug implementations. F0 has only SWD, F1 has JTAG and SWD - (switching to SWD may already trigger the lockdown)
- F0 vs F1 have different core bus matrix design. F0 with M0 core reads flash over shared bus. F1 with M3 code has dedicated ICODE bus (hack is based on bus conflict race)

All 4 of the items above mean that there is a key difference on the section specifically relevant to this attack, so a relevant part of the chip die was redesigned between the two chip families, and so any bug could or could not be there.

So, does that mean the F1 is uncrackable? I do not know. But it does mean that it was rather naive of me to think/hope the F0 debug attack would simply map to the F1.
We may think the chips are similar because we use them similar. But they are really different though and through.

If F1 is hackable, it would need all new top-level base reseach


There is still a chance to replace the STM32 quarz with external very slow clock source, but the prognosis is not so good.
So far, if there is no hidden external command over the serial line to overwrite the STM32 firmware than the only solution is to write a new one.

Alas no. I lol'ed because when this was mentioned, I literally was looking at the clock diagram on my other monitor.
But (apart from the arguments above) the flash controller has its own fixed build in RC clock. To win the race (if one exists on the F1) we would have to make the flash controller slower, and the debug access (APB bus and AHB bus) faster.

And that is the opposite of what we can do. Officially, we can make APB/AHB slower. I guess we could try overclocking. But we do not even know if there is a race condition at all, the F1 is just too different. So I repeat, it would need all new research from the bare basics, not buiding on top of Frauenhofer. Where do we stop, I was not planning on promoting on this.

So, not to be negative, but I am calling it quits.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 07, 2018, 06:48:20 pm
BTW: I have two barely used STM32F051 Discovery boards for sale, if anyone is interested    ;D
Unlocked with factory default blink program loaded.   :P
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 07, 2018, 07:34:43 pm
Ahh that is a pitty Cybermaus. Great goings never the less. A lot more has to be discovered then. Would you share the code you used?

I'm resuming the schematic entry now :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 07, 2018, 09:14:45 pm
Frontpanel schematic are done :) Offcourse some faults can be there and the PA0 signal going to the FPGA is unknown to me as of yet.

The transistors for driving the buzzer and backlight are probably MOSFETs, but I found these first :)

On to the main PCB :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 07, 2018, 09:35:28 pm
Oh well Cybermaus ,
thats a pity but a great effort you made all the same . Even though you didnt reach the finish line I guess its all part of the fun and some lessons were learned at least .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 08, 2018, 12:36:08 am
Frontpanel schematic are done :) Offcourse some faults can be there and the PA0 signal going to the FPGA is unknown to me as of yet.

The transistors for driving the buzzer and backlight are probably MOSFETs, but I found these first :)

On to the main PCB :D
:-+
The model I have on my FP is STM32F103c8t6. You have a STM32F103cbt6?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 08, 2018, 06:16:57 am
That is correct, this is what is in the library, Lazy mode.

Only difference is flash size, the c8 has 64k instead of the 128k in de cb. Pinout is the same.

fremen67: Do you have any documentation for the FPGA comms. to share for on the Git? Or some code even? Don't mind if it is tidy or not. Just want to have a look.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 08, 2018, 06:47:22 am
As mentioned, the only difference between the C8T6 and CBT6 is 64KB vs 128KB flash
But in fact, most C8T6 (blue-pill) users (almost all)  (http://wiki.stm32duino.com/index.php?title=Blue_Pill#128_KB_flash_on_C8_version)report it has 128KB anyway..

Probably a way to sell failed CBT6 chips, and not having enough production fail.
Quite possible Feeltech is buying the cheaper one, but using all 128KB anyway.

Just for fun, I check all my C8T6: both unlocked ones have 128KB usable
The one in my Feeltech I think too, but it reports "inaccurate probe":

Code: [Select]
Open On-Chip Debugger
> reset halt
target state: halted
target halted due to debug-request, current mode: Thread
xPSR: 0x01000000 pc: 0x08000144 msp: 0x20004bb8
> flash banks
#0 : stm32f1x.flash (stm32f1x) at 0x08000000, size 0x00000000, buswidth 0, chipwidth 0
> flash probe 0
device id = 0x20036410
STM32 flash size failed, probe inaccurate - assuming 128k flash
flash size = 128kbytes
flash 'stm32f1x' found at 0x08000000
>

I think it means the chip reports 128K, but he cannot validate it by reading the 2nd half.
They do all 3 give the same device id of 0x20036410
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 08, 2018, 10:40:57 am
Do I read it correctly in a way that 64k is fully guaranteed to work and 128k is not 100% validated?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 08, 2018, 11:35:14 am
Yes, if you follow the link (http://stm32duino.com/viewtopic.php?t=1323&start=20#p18962), you find at 2 users Sylvan_YZY and pokemon99 reported a C8T6 with the nominal 64KB. But both of them also had the chip only report 64K, so if the chip reports 128K, you can assume it is usable. Assume, but I guess no warranty from ST :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 08, 2018, 11:08:14 pm
That is correct, this is what is in the library, Lazy mode.
Only difference is flash size, the c8 has 64k instead of the 128k in de cb. Pinout is the same.
As mentioned, the only difference between the C8T6 and CBT6 is 64KB vs 128KB flash
But in fact, most C8T6 (blue-pill) users (almost all)  (http://wiki.stm32duino.com/index.php?title=Blue_Pill#128_KB_flash_on_C8_version)report it has 128KB anyway..
Yes I also have a mix of C8T6 and CBT6 boards. Not a big deal when you are insured to have the minimum specs.
For us it does matter in the way that we should target 64k as the maximum program size and not 128k.
I guess this is not a problem with real code size as there won't be a lot of code in our case but this could be more important for bitmaps and fonts storage. The UI usually needs some room for cool stuff (well... some UIs do, some others don't ;))
fremen67: Do you have any documentation for the FPGA comms. to share for on the Git? Or some code even? Don't mind if it is tidy or not. Just want to have a look.
Sure. All my "working" notes are in an excel file. The summary sheet is the pdf file I posted some days ago. Maybe not the best format to put on a github... but I suppose for the moment beeing you can post the pdf file as is...
For the code you can post the FPGA Library (FPGA.c) plus a module I used for testing puposes (Tests.c surprisingly  :)) This might help understand the FPGA library which should already be understandable by itself. At least I hope :P
The next module I will post will be the serial protocol which will be less interesting as already documented by Feeltech. Maybe you could also post the original document from Feeltech ...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on February 09, 2018, 12:11:29 am
I just came across this:

https://www.aliexpress.com/item/High-Precision-Digital-Dual-channel-DDS-Function-Signal-Generator-Arbitrary-Waveform-Pulse-Signal-Generator-1Hz-100MHz/32835207150.html (https://www.aliexpress.com/item/High-Precision-Digital-Dual-channel-DDS-Function-Signal-Generator-Arbitrary-Waveform-Pulse-Signal-Generator-1Hz-100MHz/32835207150.html)

I very well think I might get one at $75.   It uses a resistor ladder instead of an IC for the DAC.   I ran across a 5 V linear supply I built long ago which should do just fine powering the METERK JDS6600.  I might enjoy having a unit that didn't require work to be able to use it properly.  But one is paying about $35 for the 4 BNCs on the back of the FeelTech.  Plus the aggravation factor.  I wonder how many other names it sells under on AliExpress.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on February 09, 2018, 12:18:41 am
I think I've seen the JDS-looking version being sold under several names. I don't know if they're rebadged or just look-alike.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on February 09, 2018, 12:53:59 am
I just came across this:

https://www.aliexpress.com/item/High-Precision-Digital-Dual-channel-DDS-Function-Signal-Generator-Arbitrary-Waveform-Pulse-Signal-Generator-1Hz-100MHz/32835207150.html (https://www.aliexpress.com/item/High-Precision-Digital-Dual-channel-DDS-Function-Signal-Generator-Arbitrary-Waveform-Pulse-Signal-Generator-1Hz-100MHz/32835207150.html)
This is the 30MHz version. You may search for "rd jds6600" on Aliexpress and you will find the 5 models 15, 30, 40, 50 and 60MHz of this JDS6600 series products. The psu is 5V/2A. It needs at least stable 5V/1200mA to start and run properly. I have this rd JDS6600 and the FeelTech FY6600.

From the technical side as a signal generator the FeelTech is better. You may compare the technical data. But with an external linear 5V psu you can easily omit the known high voltage to earth problem with the JDS6600. The mechanical user interface is way better than that of the FeelTech.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on February 09, 2018, 01:06:39 am
One of the JDS sellers claims that the engineer who designed the series, and another engineer involved in later work, work for them. And that the JDS is the most recent version.

So it would appear that a designer has created a design, sold it to a manufacturer, then sold sold lower cost designs to other companies. It may well be something like:

Bored engineer in LCD factory designs FPGA/MCU AWG in spare time.  Convinces management to market it.  But management gets weird and puts a super cheap front panel on the units because the 4 BNCs out the back cost so much. So engineer gets ticked off quits and gets job designing similar product.  He goes the opposite end of the feature spectrum, gets a decent front panel and eliminates the back BNCs and we have the JDS6600.  FeelTech and FD make and sell instruments to order with whatever features you are willing to pay for added.

How true I don't know, but it seems like a reasonable fit to the facts.  FeelTech as jerks is quite obvious.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on February 09, 2018, 01:39:00 am
Something like this. The user interface of the two products is nearly identical so the engineers behind these products may come from one company or is identical. The JD6600 has the DC2DC converters on the mainboard. It's a pitty that they use a smpsu and not a linear one. Could be so easy.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 09, 2018, 07:23:01 am
But with an external linear 5V psu you can easily omit the known high voltage to earth problem with the JDS6600.
Not sure if that is true. An external switched PSU has the same problem as an internal one. The only thing is you can more easily switch out a cheap one for a better one, but they both will have leakage through the mandatory capacitor.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 09, 2018, 09:00:20 am
Filled the Git with various info on Hardware/Software/Mods and photos.

https://github.com/DerKammi/FY6600-15-30-50-60M

Lot less scrolling in the pages. Please let me know if something is missing if you want it in.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pauluzs on February 09, 2018, 09:50:34 am
Hi DerKammi,

Couldn't find a overview of the serial commands on the git.
See attached speadsheet
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 09, 2018, 10:00:07 am
Done
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 09, 2018, 12:02:39 pm
Hi DerKammi,

Couldn't find a overview of the serial commands on the git.
See attached speadsheet
Hi pauluzs,
Thank you for helping.
The "SPI Register" column in your document should be removed as it suggests  that there is one register associated to each command.
The serial protocol is only handled by the Front Panel CPU and is transparent for the FPGA.

@DerKamni
The full serial protocol description relased by Feeltech could also be added as well to the repository.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 09, 2018, 12:21:05 pm
Added
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 09, 2018, 01:00:41 pm
Parts identified: I though we had in the mean time discovered the opamp was not a "unknown THS30021" but instead a known type THS3002I
May still be a fake, but at least a known number:

http://pdf1.alldatasheet.com/datasheet-pdf/view/28726/TI/THS3002ID.html (http://pdf1.alldatasheet.com/datasheet-pdf/view/28726/TI/THS3002ID.html)

Also note the PCB layout is such they can use either 2 THS3001, or 1 THS3002

Edit: that was in the FeelTech FY3224 thread (https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/msg879289/#msg879289) that I picked that up.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 09, 2018, 01:10:04 pm
You're right, made a typo in this. Updated the txt file.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 09, 2018, 11:41:43 pm
Hi DerKammi ,
Looks like your Github post comes up top of the list when I search 'FY6600' now  .
With a bit of luck it should draw in a few more people interested in our cause and with it maybe some extra inspiration and technical wizardry too .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on February 10, 2018, 12:19:21 am
But with an external linear 5V psu you can easily omit the known high voltage to earth problem with the JDS6600.
Not sure if that is true. An external switched PSU has the same problem as an internal one. The only thing is you can more easily switch out a cheap one for a better one, but they both will have leakage through the mandatory capacitor.
That is why I wrote an external LINEAR psu. I replaced the external smpsu with a linear one and everything is fine.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 10, 2018, 05:35:57 am
Ah, sorry yes, I missed the linear part.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 10, 2018, 06:45:29 am
Hi DerKammi ,
Looks like your Github post comes up top of the list when I search 'FY6600' now  .
With a bit of luck it should draw in a few more people interested in our cause and with it maybe some extra inspiration and technical wizardry too .

So it does, that is quick. Would be great if we could create that momentum.

Despite the small "bugs" the device has it is worth the price to make some killer custom open source firmware.

I only that FPGA could be... ahh well dreams are for the keeping.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 10, 2018, 03:02:42 pm
Sure. All my "working" notes are in an excel file. The summary sheet is the pdf file I posted some days ago. Maybe not the best format to put on a github... but I suppose for the moment beeing you can post the pdf file as is...
For the code you can post the FPGA Library (FPGA.c) plus a module I used for testing puposes (Tests.c surprisingly  :)) This might help understand the FPGA library which should already be understandable by itself. At least I hope :P
The next module I will post will be the serial protocol which will be less interesting as already documented by Feeltech. Maybe you could also post the original document from Feeltech ...

Can I have the .h files as well? want to have a go with my fresh blue pill boards on Mark his generator this evening.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Lanvernazal on February 11, 2018, 04:20:20 am
I have made and change a linear PSU for my FeelTech FY6600 .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 11, 2018, 06:14:13 am
Well somebody had a busy weekend :)

Nicely done in the limited space.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on February 11, 2018, 09:05:32 am
I have made and change a linear PSU for my FeelTech FY6600 .

Nice job Lanvernazal, you did it well.
On my side, because I am a lazy man, my choice was to make some mods on the stock one.
Upgrading some capacitors, switching diodes, earthing the FY6600 with an appropriate socket for the mains input.
Et voila !!



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 11, 2018, 09:15:10 am
For the German residents, a cheap one (no connection with the seller):

Quote
Biete   Meßgeräte
(Anzeigen-Nr.: 514605)    2-Kanal DDS Signalgenerator Feeltech FY6600-60
Ich biete einen unbenutzten Signalgenerator vom Typ FY6600 an. Es handelt sich um die 60MHz-Ausführung. Informationen dazu finden sich reichlich im Internet. Das Gerät wurde nur einmal zum Funktionstest eingeschaltet. Es arbeitet mit der Firmware V3.2. Preis 70 Euro inkl. Versand innerhalb von DL.
 9.2.18 - 11:06 Uhr    Karsten Hansky - DL3HRT
 dl3hrt@aatis.de

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on February 11, 2018, 11:21:43 am
Has anyone who has gone to a linear PSU done any measurements that demonstrate improvements to stability, distortion, jitter, amplitude vs frequency or any other characteristics? I am mulling the possibility but haven't seen enough justification yet. My limit has been grounding the SMPS common to stop it biting.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 11, 2018, 11:36:42 am
I'm waiting for a 15v / 9v R-core transformer to be delivered, then I'll be doing mine - more out of curiosity than anything else, as I'm not convinced it will make much difference - then I'll give you my thoughts.  I'll be happy if it reduces the jitter somewhat.

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on February 11, 2018, 09:21:59 pm
Thanks Dave, that should be a useful addition to the knowledge bank.
Will you be doing identical before and after tests?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 12, 2018, 06:20:31 am
Has anyone who has gone to a linear PSU done any measurements that demonstrate improvements to stability, distortion, jitter, amplitude vs frequency or any other characteristics? I am mulling the possibility but haven't seen enough justification yet. My limit has been grounding the SMPS common to stop it biting.

Well, aside the mains leakage protection a linear and good stabilized power supply will do jack against jitter (digital issue), frequency stability (oscillator) and amplitude vs frequency.
It will do a lot of good on: distortion factor of high signal levels under load, noise factor and make the amplitude more predictable. I mean if you connect a 1Mohm scope probe, you won't see too much of a difference, if you connect a 50ohm spectrum analyzer input and play a bit with the levels you'll see the difference immediately, also one can connect a scope with a 50 input and put the triangular waveform.

Someone here did the measurement and the output voltage of the power supply swings in between 12 to 17V !! volts, in different load and frequency conditions, this can't be healthy for the analogue block.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CharlieEcho on February 12, 2018, 01:50:54 pm
I don't see the firmware specified anywhere when ordering one. Any way to be sure I get the latest 3.2 firmware?

Order the Kuman-branded version on Amazon (ASIN: B074TCVPVG). It's coming directly from them ("kumanshop") and as of mid-January their stock had v3.2. Boot screen identifies it as a FY6600. They're a Prime seller, so if it disappoints just send it back. Probably pricier than eBay though.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: TopLoser on February 12, 2018, 07:13:24 pm
I ordered one from eBay about 10 days ago and it came with 3.2.1 firmware
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 12, 2018, 07:15:46 pm
3.2.1 ?!?!

A new revision ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: TopLoser on February 12, 2018, 07:26:55 pm
Looks like 3.2.1 to me...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 12, 2018, 07:29:11 pm
Hmmm, what they did corrected this time, maybe this endless stupid repetitions of all parameters re-programming when you just change one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on February 12, 2018, 07:48:17 pm
Sending  all parameters on any change is a good idea.  It makes the FPGA code much simpler.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 12, 2018, 07:49:20 pm
Sending  all parameters on any change is a good idea.  It makes the FPGA code much simpler.

FOUR times ?!?!?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 12, 2018, 09:26:45 pm
I was looking at the front panel pic up close and personal and thinking ,damn that looks crummy ,but then I realised the outer protective plastic wasnt  peeled off yet . I'm half thinking a layer of something like 3M weatherproof clear tape over the buttons might be a good trick for longevity , Ive seen how those polycarbonate bubble switch membranes go after years and years and its not pretty. Course that could all be in vain if the thing ends up brain dead after two weeks . still no sign of my machine yet.......
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: scott0999 on February 13, 2018, 03:10:05 pm
I ordered one from eBay about 10 days ago and it came with 3.2.1 firmware

which seller on ebay?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: TopLoser on February 14, 2018, 04:53:04 pm
Creativeonline100
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 14, 2018, 09:08:36 pm
Some updates on what’s going on.

1-The FPGA Module is finished for now.
2-The main Feeltech serial protocol functions are working :
- Waveform selection
- Frequence
- Amplitude
- Offset
- Phase
- Duty
- CH1/CH2 ON/OFF
- ARBs transfer
The others are foreseen but they will be added later on if/when needed.

3-I am now working on the main control module, including the Relays switching logic and output ranges limitations (Amp and Offset).
As soon as the basic functions are working (end of next week?), I will publish binaries for blue pills board. We will then be able to bypass the front panel and control the FG from the Feeltech PC Software interface. This interface would need some serious QA control but at least it already exists, every one can get it plus the source code is available).
This will allow everyone to test the new firmware without modifying the Front Panel. If it works well, I will then publish the first code source release. The cost of a blue pill board is very low, one just needs to get an ST-Link V2 to flash it (also very affordable).
I received today my second FY6600 (15MHz Model) so this will be my next dev board. Not sure for now if I will flash the FP directly or swap before the CPU with a CPU from one of my blue pills boards to have a spare…

4-Some other points in disorder :
- Reg 0x38 and 0x39 are used for rising/falling time of the square waveform (duty button)
- Need to study Square, CMOS, Adj-Pulse and DC which are handled differently than ARBs
- Sweep functions are handled partially by the FP which sends frequency setpoints in real time
- The blue pill source project should be able to compile with the free version of Keil µvision (8ko of program code/ 18ko of data now for my dev board which already includes some LCD library functions)
- Attached the software architecture I foresee for the moment
- I will open a new thread for the open source FP software as  it might polute this already long thread
- I will have one week off in 2 weeks, this might speed up things ;-)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 14, 2018, 09:10:08 pm
@TopLoser: Would you be able to dump the flash memory? :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 14, 2018, 11:43:57 pm
Tremendous work Fremen,
I think our project would have fallen on its ass without your expertise.
Maybe to get something back for your efforts you could consider offering pre programmed Stm32's .
Ill probably give the blue pill thing a go myself for the learning of it ,
Thanks again,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 15, 2018, 07:00:22 am
Fremen, what is great progress you made. Highly appreciated at the work you are doing. Thanks.

I would love to help you in the coding, but compared to you're speed and knowledge I'm not much of a help I'm afraid.

Since I also have a second unit but waiting on my ST-Link I would like to try out the code you made when possible.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 15, 2018, 06:14:19 pm
Great progress. Very promising.

While not at all urgent, please remember that one of the features of the FY6600 is the ports on the backside. So you may want to keep that in mind when designing the data-structures and things that you 'foresee' for the future.

I do not think anyone mentioned them in a while, or mapped out their SPI protocols.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 15, 2018, 07:48:38 pm
The ports and the modulation stuff is interesting, starting this Sunday I can start contributing again, the Saturday is reserved for the signal generators run, but in the meantime @fremen67, if you have some capture for square wave settings or other interesting signals, please post them here, I'll love to get some eyes on them.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: TopLoser on February 15, 2018, 07:54:04 pm
@TopLoser: Would you be able to dump the flash memory? :)

Sorry, I’ve already shipped it out to somebody. I just handled the buying and shipping for them, complicated story don’t ask!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 16, 2018, 12:20:21 am
Maybe to get something back for your efforts you could consider offering pre programmed Stm32's .
Thank you, that's kind of you but it has to remain free. A matter of principle  :)
Since I also have a second unit but waiting on my ST-Link I would like to try out the code you made when possible.
No problem. I will send you homework  ;)
While not at all urgent, please remember that one of the features of the FY6600 is the ports on the backside. So you may want to keep that in mind when designing the data-structures and things that you 'foresee' for the future.

I do not think anyone mentioned them in a while, or mapped out their SPI protocols.
Those functions are handeld directly by the FPGA as far as I know. I already documented all the related commands in my first pdf more than2 weeks ago  :P
@fremen67, if you have some capture for square wave settings or other interesting signals, please post them here, I'll love to get some eyes on them.
OK I will see what signal could be interresting to check.
Square / CMOS / Adj-Pulse and DC are now clear. They are defined with Reg 0x05 (see updated pdf)


@all of you: Thank you for your support and your kind words :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 16, 2018, 05:37:07 am
@fremen67: I have a small question, do we really need to change the parameters fully to change just one, or for example the frequency can be changed by just one register operation or register operation + reload registers trigger, so just 2 register write, I'm curious haw fast one can sweep the frequency/phase ?

Also, one more thanks for your excellent work  :clap:

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 16, 2018, 06:25:06 am
For anyone having problems installing the FY6600 software and getting an error "Component ‘richtx32.ocx ‘ or one of its dependencies not correctly registered or a file is missing or invalid" here is the solution.
https://www.k6jm.com/hs-setupocx.htm. (https://www.k6jm.com/hs-setupocx.htm.)   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 16, 2018, 06:40:41 am
ehhh, just a bit quick on the feature request possibly, but a request.

I saw in the reviews that when doing a sweep we have to use the VCO to generate a signal for having a sweep output and trigger slope. Can we make it so that we use CH2 as the trigger ramp while CH1 does the sweep. Then we don't need to have the back connections attached for a simple sweep.

Since I also have a second unit but waiting on my ST-Link I would like to try out the code you made when possible.
No problem. I will send you homework  ;)

The better kind of homework in ages :)

Not sure how much room there is to spare on the free version of Keil, but I've been playing with my previous suggestion of Atollic TRUEstudio and this is actually a full grown tool with a huge amount of possibilities for free with no limit in code size. I'm not pushing anything what so ever but together with CubeMX you have a code wizard for the HAL which can init the DMA for the 2 SPI busses with a couple of clicks. I'm very impressed with it so far.

@all of you: Thank you for your support and your kind words :)

You're working hard enough, can't be thanked enough for in this topic.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 16, 2018, 06:55:32 am
Has anyone done a mod to improve the frequency stability?   My new unit FY6600 v3.2 has frequency jitter of about 5Hz at 10MHz.  My older JDS6600 is around 1/10 of that at 0.5Hz
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 16, 2018, 07:03:25 am
Has anyone done a mod to improve the frequency stability?   My new unit FY6600 v3.2 has frequency jitter of about 5Hz at 10MHz.  My older JDS6600 is around 1/10 of that at 0.5Hz

Check these posts:
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1346454/#msg1346454 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1346454/#msg1346454)

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1389870/#msg1389870 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1389870/#msg1389870)

I'm switching my osc for the Farnell 1611840   ASV-50.000MHZ-EJ-T -  Oscillator, 50 MHz, 20 ppm, SMD, 7mm x 5mm, 3.3 V, ASV Series. Not in need of that low jitter specs at this moment.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 16, 2018, 10:52:40 pm
Slow goings on the schematics of the main PCB. Lot of parts needing drawing which takes up quite some time. But the start is there.

Got the FPGA part from Farnell, not sure about the pinning sorted by banks in the way they did. May need to rearrange that for a more clean schematic.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 17, 2018, 04:14:54 am
Slow goings on the schematics of the main PCB. Lot of parts needing drawing which takes up quite some time. But the start is there.

Got the FPGA part from Farnell, not sure about the pinning sorted by banks in the way they did. May need to rearrange that for a more clean schematic.

Nice work @Der Kammi  :clap:, my signal board has some very strange rework done with some blobs of solder in between the oscillator pins on top side  :scared:, I can't wait to see what is there actually.
In the end, the FY6600 may become the best FPGA development board for mixed signal development in its price range  >:D, so we have this for us  :-+

I'm traveling to Düsseldorf in 2h to get the Anritsu boat-anchor, but starting from next week I'll recontribute again (on Sunday I'll do the autopsy ;).

 Cheers,
 DC1MC

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on February 17, 2018, 08:59:55 am
Slow goings on the schematics of the main PCB. Lot of parts needing drawing which takes up quite some time. But the start is there.

Nice first step on drawing down the schematic of the main board, it will be very usefull for all of us.
How can I help ?
I don't have much time to spent on that, however I think I could do something to help.
What sort of EDA are you using ? EasyEDA, Tinycad..

sheers
Eric
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 17, 2018, 01:19:34 pm
@Ebel, the relais routing is a bit strange to me as the common contact looks weird up until now. If you can draw that out that would help me. A photo from a paper drawing is fine.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 18, 2018, 02:28:27 am
Slow goings on the schematics of the main PCB. Lot of parts needing drawing which takes up quite some time. But the start is there.

Got the FPGA part from Farnell, not sure about the pinning sorted by banks in the way they did. May need to rearrange that for a more clean schematic.

Has anyone drawn the power supply board schematic?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on February 18, 2018, 09:19:33 am
Here it is.
I don't have double checked all the components values.

This schematic shows the upgraded version I made by myself (the new values are in red).
The stock values are also mentioned.


(edited)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 18, 2018, 03:57:41 pm
Nice one Eric. No surprises in the PS division so to see. It couldn't be more skimpy on the regulation side :(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 18, 2018, 06:11:58 pm
Soo... Those 220uF 25V, are they what you feel they should have been, or do you actually have 25V instead of the underspec'ed 16V me and others were complaining about?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on February 18, 2018, 09:14:32 pm
You're right Cybermaus my post was not 100% clear, so I edited it.
The schematic correspond to the upgraded version I made some weeks ago.
I uploaded a new one  :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 18, 2018, 09:49:59 pm
Talking of power supplies, I got my transformer on Wednesday, so I've replaced the original in mine with a linear as per the photos attached.  I set the outputs to 5.1v and +/- 12.2v, and the only component which generates any heat is the LM317 on the 5v board, which tops out at 75degC (but well within its design spec).  The transformer runs very cool, and the regulators on  the 12v board hardly get warm.  I didn't bother with a fan because a 90 minute soak test with a temperature probe inside the case showed that the internal temperature only rose to a steady 34C after an hour (10C above ambient), which I don't forsee being a problem.  Some slots in the case above the 5v board will probably lose half of the extra heat anyway, if I need to do anything at all. 

As you can see, I've also replaced the plastic disc on the encoder shaft with a "proper" knob, and this simple change has made a vast improvement in the operation and feel of the thing - I'd recommend this as a "must do" mod (I just had to move the encoder mounting board forward a couple of mm to get the shaft to protrude enough to get it into the collett of the knob).

I haven't carried out any comparative tests between the new and old PS boards yet, but I did notice as soon as I first switched it on that the oscilloscope traces appeared to be much cleaner than before, obviously due to the reduced noise level compared with the SMPS.  Everything is fine so far, after three days and several hours of operation.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on February 19, 2018, 05:36:04 am
Hello,

@Ebel0410.
Thanks for the schema a power supply.
The symbol for 1n5819 and YG911S2 is not correct, it indicates a zener diode but it is a rectifying diode.

Regards,
Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 19, 2018, 06:59:37 am
Hello,

@Ebel0410.
Thanks for the schema a power supply.
The symbol for 1n5819 and YG911S2 is not correct, it indicates a zener diode but it is a rectifying diode.

Regards,
Diabolo

The symbol is perfect, it indicates a Schottky diode, the Zenner is a bit different.

Schottky:
https://www.google.de/search?q=Schottky+symbol&num=50&client=ubuntu&hs=iUN&channel=fs&dcr=0&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwi-haa6s7HZAhVQyaQKHdY2AioQsAQIcg&biw=1855&bih=1102 (https://www.google.de/search?q=Schottky+symbol&num=50&client=ubuntu&hs=iUN&channel=fs&dcr=0&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwi-haa6s7HZAhVQyaQKHdY2AioQsAQIcg&biw=1855&bih=1102)
 
Zenner:
https://www.google.de/search?client=ubuntu&hs=5UN&channel=fs&dcr=0&biw=1855&bih=1102&tbm=isch&sa=1&ei=lHWKWqjIBczUkwWdq42AAQ&q=Zenner+symbol&oq=Zenner+symbol&gs_l=psy-ab.3..0i13k1j0i13i5i30k1j0i8i13i30k1l5j0i13i5i30k1.41765.42808.0.43591.6.6.0.0.0.0.121.487.5j1.6.0....0...1c.1.64.psy-ab..0.5.363...0j0i67k1j0i7i30k1.0.k5lvTbViCbA (https://www.google.de/search?client=ubuntu&hs=5UN&channel=fs&dcr=0&biw=1855&bih=1102&tbm=isch&sa=1&ei=lHWKWqjIBczUkwWdq42AAQ&q=Zenner+symbol&oq=Zenner+symbol&gs_l=psy-ab.3..0i13k1j0i13i5i30k1j0i8i13i30k1l5j0i13i5i30k1.41765.42808.0.43591.6.6.0.0.0.0.121.487.5j1.6.0....0...1c.1.64.psy-ab..0.5.363...0j0i67k1j0i7i30k1.0.k5lvTbViCbA)


 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 19, 2018, 07:32:09 am
Also added it to the git (https://github.com/DerKammi/FY6600-15-30-50-60M)

Here it is.
I don't have double checked all the components values.

This schematic shows the upgraded version I made by myself (the new values are in red).
The stock values are also mentioned.


(edited)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on February 19, 2018, 08:13:39 am
Oops, sorry.
:palm:

Indeed, looking good symbols are correct.
I run to buy good glasses for my eyesight.

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on February 19, 2018, 07:06:48 pm
@Ebel, the relais routing is a bit strange to me as the common contact looks weird up until now. If you can draw that out that would help me. A photo from a paper drawing is fine.


Hi DerKammi,

I'll start working on that next weekend, hard stuff  :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 19, 2018, 07:09:57 pm
Don't worry, I soldered loose some relays of my board just 10 minutes ago and all is clear now.

And offcourse, it makes perfect sense when you see it :) As always. I'll post a small update of the schematics this evening to you show
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 19, 2018, 09:03:27 pm
Here is the schematic update. Onto the digital part.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Vytautas on February 20, 2018, 07:27:43 pm
Here, another guy posted what happened to his fy6600. It seems to be bricked. Though, no details are provided.
https://www.youtube.com/watch?v=a3v9sGDVfMI (https://www.youtube.com/watch?v=a3v9sGDVfMI)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 20, 2018, 07:36:28 pm
This is what typically happens if the CPU on the front board does not get any contact with the FPGA on the mainboard.

Like when you disable the FPGA because you are reading the WInbond, or if the cables between FB and MB are loose or broken.
Someone else reported a device was shipped with a loose cable, also looked like this.

I'd suggest to check the internal cables and their connectors.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 20, 2018, 07:46:35 pm
Like this:
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1415538/#msg1415538 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1415538/#msg1415538)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 21, 2018, 12:47:34 pm
My 6600 arrived  , V3.2
I swapped out the powersupply for something slightly better ,although the stock item seems to have been improved a bit ,it now has 25 volt low esr caps on the 12volt rails ,and the yellow x cap, 1mohm ,and slot by the opto are back ,its on a fibreglass board marked Feeltech V1.1

I have a transformer 2x17v and 8v which I will try later once the linear regulator board arrives .

I changed the dial on the encoder too ,the original is a bit small for the fingers to grasp.

I dont like the way the heatsink is mounted on the output Ic's ,due to a difference in height it doesnt seem to make good contact , I have two 3095 output ic's ,so I'll sort the heatsink out when I get those soldered in .

I tried the version 5.5 software ,one weird thing was that it seems not to respond when I switch on or off the channels via the front panel ,not sure if this is only one way communication here.

I still have to do some proper tests to check voltage and frequency cal .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 21, 2018, 01:05:27 pm
Here's a photo with the upgraded PSU.
Slightly higher current and extra caps and inductors on the +/- rails .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 21, 2018, 03:49:21 pm
Here's a photo with the upgraded PSU.
Slightly higher current and extra caps and inductors on the +/- rails .

Maybe it shows that Feeltech are taking note of, and acting on, what's being discussed on here - even though they're not letting on?  I bet they are taking a keen interest in the reverse engineering developments, with a view to a future model!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 21, 2018, 03:55:26 pm

I tried the version 5.5 software ,one weird thing was that it seems not to respond when I switch on or off the channels via the front panel ,not sure if this is only one way communication here.


Yes, I noticed the same thing.  I could have sworn v5.3 was two-way, but maybe it's a false memory.  I'll try reinstalling the earlier version and get back to you.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 21, 2018, 10:16:39 pm
Hi Dave ,
The pic above is another +5-12+12 supply pulled from a dvd player ,
It has inductors on all the rails ,and a second smoothing caps after ,I even seen some switch modes with two inductors and three caps at the output of each rail .
Some reported that the caps on the feeltech psu 12volt rails were only 16 volts , the one I have has 25volt rated low esr caps at the outputs of each of the +/- ,only the 5 volt rail gets an output inductor and second cap ,also a low esr with 16 volt rating.

Either way when I turn up the output voltage of the generator it tends to pull down the 5 volt rail by a few hundred millivolts , theres likely some signal currents in the simple psu causing this interaction . Most decent equipment you find with switchmodes follow them with 78/79 type regs so noise is mV on the rails .Someone also suggested screening of the switchmode ,as there well known for radiating RF mush into other parts of the circuit . Im kinda just working through improving switchmode performance now ,but ultimately I'll most likely go old school Transformer/linear regulator later ,of course this presents its own electromagnetic screening issue which is expensive and difficult to reduce,upside is no rf problems.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 22, 2018, 04:58:36 am

Hi soundtec - the software IS two-way, but not constantly: if the FY6600 is on when the software is started the settings on the generator are read into the software, but after that they are read only when the "Load" button at the right of the program window is clicked.  That must be what I half remembered from the two or three minutes I played with it a few weeks ago.

You've got me thinking now about alternative power supply sources, as I've got a decent quantity of old satellite receivers and dvd players / recorders stashed in the loft.  I think I'll have to open them up and see what useful bits I can scavenge from them.  Most of them were top quality models when I bought them, so there may be some hidden gems to unearth, with a bit of luck.

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scratch.HTF on February 22, 2018, 09:27:43 am
With regard to the circuit at Reply #791: at the THS3002 amp, the gain figure is 3.986 with a 10K input termination resistor and 4.006 without this resistor; changing this resistor to 33K results in a 3.999951 gain factor which is very close to a perfect 4.
Notably, the sine filter is not switchable and that there appears to be no frequency compensation including through full scale DAC current control for high frequencies.
To preserve waveform fidelity without the need to change waveform data depending on the output level range, the output levels are set by controlling full scale DAC current via its external voltage reference pin which the level is set by an auxiliary DAC.
There is significant jitter at output frequencies which have a division ratio at anything other than an integer against the DAC clock (fixed at 250 MHz) e.g. 250 MHz / 50 MHz = division of 5 has no jitter under ideal conditions while 250 MHz / 40 MHz = division of 6.25 has significant jitter (1.6 MHz).
I still don't know why the DAC clock is fixed at 250 MHz... an Arduino bootloader could be customized for the ARM microcontroller so that we can load custom firmware easily.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 22, 2018, 10:32:33 am
Thanks for that info Dave,

Ive been researching quietening switchmode psu's, assuming you have enough voltage to spare just adding a linear regulator after may not have much effect on high frequency noise ,LC filters ,both common and differential mode are a good idea though .

One benefit of the switcher is that it can withstand short term(100ms) drop outs in the mains supply and still maintain its voltage across the load, where a linear will certainly drop out with even something like 10ms duration of a mains fluctuation.
This might be important for the 5 volt rail ,less of an issue for the +/- 12 volt supplies on the op-amps I would imagine.
Would be interesting to hear from someone with design experience with switchmodes.                             
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 22, 2018, 03:28:07 pm
With regard to the circuit at Reply #791: at the THS3002 amp, the gain figure is 3.986 with a 10K input termination resistor and 4.006 without this resistor; changing this resistor to 33K results in a 3.999951 gain factor which is very close to a perfect 4.
Notably, the sine filter is not switchable and that there appears to be no frequency compensation including through full scale DAC current control for high frequencies.
To preserve waveform fidelity without the need to change waveform data depending on the output level range, the output levels are set by controlling full scale DAC current via its external voltage reference pin which the level is set by an auxiliary DAC.
There is significant jitter at output frequencies which have a division ratio at anything other than an integer against the DAC clock (fixed at 250 MHz) e.g. 250 MHz / 50 MHz = division of 5 has no jitter under ideal conditions while 250 MHz / 40 MHz = division of 6.25 has significant jitter (1.6 MHz).
I still don't know why the DAC clock is fixed at 250 MHz... an Arduino bootloader could be customized for the ARM microcontroller so that we can load custom firmware easily.

Thanks for the 33k resistor change. Like those small changes which help in make this device a little bit better every time.

Together with the adj. resistor we can actually "calibrate" the unit pretty nicely.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 22, 2018, 07:28:26 pm
I still don't know why the DAC clock is fixed at 250 MHz... an Arduino bootloader could be customized for the ARM microcontroller so that we can load custom firmware easily.

These are two separate topics right? (unsure because they are in one sentence)
Assuming indeed they are two topics:

Fremen67 already discussed the possibility to STMduino (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1419584/#msg1419584) this. But alas, the needed pins for the default arduino sketch upload (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1419673/#msg1419673) are used for other purposes on the FB, as are the ones for the serial uploader. We would be stuck using a STlink, even for the STM32duino code. So no easy upload, and thus we may as well burn firmware without loosing space to a bootloader (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1419841/#msg1419841).
Anyway, STlink is also easy, so not worry about it too much.


Not discussed here, but I did also think about changing frequency on the DAC to work around 4ns quantization jitter from a theoretical point of view.
But that is not so easy. PLL's typically have fixed ratio's, so even if you add more ratio's, you increase the number of perfect integers, but they are still among a sea of jittery real numbers.

Right now the FPGA is hard coded on a 50MHz x5 PLL. Even if we were to start tweaking the FPGA as well as the STM, I suspect we could only get fixed ratio;s. x4. x4.5 x5.
It would give us more points with no jitter, but still not all of them.

In my opinion, we'd need a VCO instead of a XO+PLL to get full variable clock and avoid quantization jitter, but it would give back classic jitter and frequency drift instead.




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Val on February 22, 2018, 09:38:20 pm
Output frequency calibration.

It is possible that I missed a similar discussion before.

Many people complain about frequency accuracy and stability of FY6600.
After about 20-30 min frequency is relatively stable, but a reference oscillator lacking accuracy. My generator, for example, has 50,000,215 Hz reference frequency. It is no means to adjust this oscillator.

At the same time FY6600 allows for the output frequency calibration by firmware using the following procedure:

1.   Put the back main switch in “OFF” position.
2.   Press simultaneously “Power” and “CH1” buttons on the front panel and put the back main switch in “ON” position.
3.   Waite 3-4 seconds and release both front buttons.
4.   On CH1 select the highest output frequency for your generator model. Set an amplitude of 0,3-1,0 V.
5.   Press “SYS” and then “More”.
6.   Now on the screen you can see “Oscillator” and on display 10.000.000.000 MHz
7.   Press F5 to go to frequency calibration.
8.   Connect a frequency meter to CH1 output.
9.   Using cursor and the dial obtain reading of the frequency meter the same as set on the generator. If measured frequency is lower – dial should be rotated CCW, if higher – CW.

After calibration press the “Dial” and then CH1 to return to normal operation.
73, Val
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 22, 2018, 10:25:37 pm
Thanks for that Val ,
Ive been through every inch of this topic and I can't recall any internal cal procedures like that mentioned before ,How did you find out about it ? and is there anymore hidden menus?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 22, 2018, 11:32:37 pm
Even though I have no very accurate frequency meter (60,000 counts),I could certainly see that the unit needs some time to stabilize after switch on ,its the same for almost all electronics really ,takes time for the temps inside the case to level out ,its always a good plan especially with test gear to allow a warming up period before attempting to calibrate.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 23, 2018, 06:16:23 am
@Val, That's a great first post in this topic. How do you know this stuff? Any manual we don't know?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 23, 2018, 07:45:28 am
Output frequency calibration.
....

Wow. It actually works.
I was very suspicious and even checked the calendar (not April 1) before trying this, but there actually is such calibration option.

Many thanks for showing us. But also, how did you know? Any other tricks?


However, I feel such calibration would in fact increase the quantisation jitter, because of the fixed 50Mhz x5 clock. So they would have to drop/add a tick every so often.
Remember ArthurDent who replaced the 50MHz XO with a OCXO (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1346454/#msg1346454) and got 10 digits of correctness on his frequency, proving the FPGA logic itself is dead on, and its all about the crystal it uses.
Also, this would not fix the temperature drift as the device heats up. Even blowing on the XO (cooling it) showed a visible drift and back as it cooled and then heated back up

I'd have to test this, if it actually indeed increases jitter.
So if frequency is important to you, especially above lets say 5MHz or so, a better method might be to leave this alone and replace the XO with a better and cheap and easy TCXO or even OCXO


But I do want to repeat this is a amazing find. Wherever/However you found this, what else do you have for us?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 23, 2018, 04:07:21 pm
This is indeed a very useful trick to know, and its existence shows that there's probably a few other hidden engineering functions buried in the firmware.  I'm not too fussed about the frequency accuracy as mine is close enough for my needs, but I'd love to know if there's a way to equalise the amplitudes on each channel to get rid of the small difference I see.  I know there are four little trimpots inside which can be adjusted, but my experience with those things is normally that you can spend an hour tweaking them backwards and forwards without ever hitting the right spot, and if you do it will still need redoing the next time you switch on.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Val on February 23, 2018, 09:26:46 pm
Dear Soundtec,

As they say: If you do not knock - nobody opens a door.
It was very simple: I asked FeelTech.

73, Val
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on February 23, 2018, 09:30:55 pm
It was very simple: I asked FeelTech.

Hehe. Welcome to the forum, Val.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on February 23, 2018, 11:07:46 pm
Thanks Val, your post is very usefull !
Actually, a question came up to my mind.
Is there a procedure to adjust other values ? I guess the answer is certainly positive..
And then, all of these parameters are probably stored in the flash memory, but where ?

It's like looking for a needle in a haystack.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 24, 2018, 02:47:41 am
A ten turn pot on amplitude adjustment on each channel would be nice ,I notice a few tens of mV difference between ch1 and ch2 on my unit ,its awkward to try and fine tune things with single turn micro pots.

Maybe we have underestimated Feeltech's willingness to engage in terms of the product feedback were offering up here ,'ask and you shall receive' is the saying that springs to mind ,'God helps those who help themselves' is another.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 24, 2018, 02:52:18 am
Dont worry by the way ,I'm not some religious nut trying to convert you all with biblical quotes  >:D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 24, 2018, 03:06:09 am
Replacement of 50Mhz clock chip with TCXO (1ppm).   

Greetings.  Yesterday I swapped out my Feeltech 6600 50Mhz IC with a DJ75-050.0M IC.  The DJ75 has a 1ppm per year aging spec as well as 1ppm frequency stability vs temperature.   It has 10 pads of which only 4 are used.  You must connect pads 8 and 9 in this application.  Fortunately they pretty much line up with the existing pads on the Feeltech 6600.   Please excuse my lousy SMD soldering skills in the photos.  Results were good.   After installation I let the unit run overnight to reach thermal equilibrium.  Then I followed the frequency calibration procedure provided by Val (thanks again!).   Results were spot on measured over a couple of hours.  My counter was locked on 60Mhz where the FT6600 was set. 

The DJ75-050.0M is available from Digikey for about $11 US.   Datasheet attached.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on February 24, 2018, 04:07:52 am
Dear Soundtec,

As they say: If you do not knock - nobody opens a door.
It was very simple: I asked FeelTech.

73, Val

And didn't ask them to fix a borked unit.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 24, 2018, 08:11:25 am
So I ordered one of these.  Waiting on delivery.

I scan read the thread.  It's cheap, has some minor issues, that's fine.  The only current use case I have is testing circuits in the audio range, maybe testing a few ultra sonic filters.

Can anyone explain to me if the PSU issues are safe or do I really need to replace it?  If I do need to replace it, would a PC PSU do the job, it has +-12V and +5V obviously.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 24, 2018, 10:12:54 am
So I ordered one of these.  Waiting on delivery.

I scan read the thread.  It's cheap, has some minor issues, that's fine.  The only current use case I have is testing circuits in the audio range, maybe testing a few ultra sonic filters.

Can anyone explain to me if the PSU issues are safe or do I really need to replace it?  If I do need to replace it, would a PC PSU do the job, it has +-12V and +5V obviously.

The unit is basically safe for humans but the "ground" of the BNC will measure about 1/2 of your AC voltage into a high impedance.  The current is small but can be felt as a tingling in some situations.  This could cause problems with sensitive electronics in some situations.  The problem is that they use a two terminal AC input connector so there is no earth ground reference.

Just add three terminal ac input with ground or, like me add a separate banana jack to ground the unit to earth.  This will prevent the outer of the BNC connectors from having any AC on them.

The advantage of the banana jack is that you can easily disconnect it if you wish to float your function generator above ground for some special circuit.   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 24, 2018, 12:31:16 pm
Is there an easy to source alternative to replace the PSU inside?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 24, 2018, 01:41:48 pm
For some reason I'm thinking that there would be some interest for a self designed linear PSU. Just an idea.

@Fremen67: not wanting to push, but do you have any homework for me yet? My ST-Link clones arrived yesterday and are upgraded to the latest firmware. So time to flash these units :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 24, 2018, 02:11:06 pm
For some reason I'm thinking that there would be some interest for a self designed linear PSU. Just an idea.

Interesting.  But it would be my first mains fed PSU.  Makes me re-read my signature.

EDIT: any idea on the current requirements of it?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 24, 2018, 02:34:44 pm
Don't worry. Have one ready from another project. Can be easily made smaller for the space available.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 24, 2018, 04:00:30 pm
@Fremen67: not wanting to push, but do you have any homework for me yet? My ST-Link clones arrived yesterday and are upgraded to the latest firmware. So time to flash these units :D
I had a busy week at work. It seems it's always like that when you want to take some days off  :)

I get stucked in my tests with the Feeltech PC Software. I though it would last longer without any modification but I was too optimistic...
When you type 123.45 Hz, it sends 1 then 12 than 123 then .... Hard to trigger anything correctly when debugging...

So long story short: I made some modifications to the PC Software:
- Add an input box to handle more easily inputs
- Remove all the amplitude & offset modifications the software was doing (the FP already handles that)
- Read back of parameters that the FP could change (Amplitude & Offset)
- Read back of CH2 synchronized parameters when changing CH1 parameters
- Add Synchrone Reads & Writes
- fixed the regional setting issue with "," & "."
- Add a Refresh button, just in case you modify things directly on the FG
- modified the display setting...

The source posted by feeltech was not the latest as you will see (mainly arbs handling differences) but it doesn't matter at the moment

If you already installed the original Feeltach software, you just have to copy and launch the modified one.

Could some of you guys try it ?

Now that the parameters are read from FG, I noticed that negative offset are not sent correctly by the FP. It is sending out of range values. I just display 0 in the case.

So I can go back to FP firmware now  :box:

Edit: Oups! Wrong file. OK now  :P
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 24, 2018, 04:13:49 pm
@fremen67: I have a small question, do we really need to change the parameters fully to change just one, or for example the frequency can be changed by just one register operation or register operation + reload registers trigger, so just 2 register write, I'm curious haw fast one can sweep the frequency/phase ?
Sorry I missed your question. No you don't need to send all the parameters each time. No trigger required except fot the phase. So just one register write most of the time.
I don't know the change speed limit for now. I will see this when programming the sweep function. Not sure this will be the comming week. I first have to finish the basic functions.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 24, 2018, 04:22:29 pm
Here is the schematic update. Onto the digital part.
:-+ Well done.
I think we will have a problem to solve with the outout impedance. It's 50 ohms for the medium and high output range ... but not for the low output range ...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 24, 2018, 04:34:24 pm
Output frequency calibration.

It is possible that I missed a similar discussion before.

Many people complain about frequency accuracy and stability of FY6600.
After about 20-30 min frequency is relatively stable, but a reference oscillator lacking accuracy. My generator, for example, has 50,000,215 Hz reference frequency. It is no means to adjust this oscillator.

At the same time FY6600 allows for the output frequency calibration by firmware using the following procedure:

1.   Put the back main switch in “OFF” position.
2.   Press simultaneously “Power” and “CH1” buttons on the front panel and put the back main switch in “ON” position.
3.   Waite 3-4 seconds and release both front buttons.
4.   On CH1 select the highest output frequency for your generator model. Set an amplitude of 0,3-1,0 V.
5.   Press “SYS” and then “More”.
6.   Now on the screen you can see “Oscillator” and on display 10.000.000.000 MHz
7.   Press F5 to go to frequency calibration.
8.   Connect a frequency meter to CH1 output.
9.   Using cursor and the dial obtain reading of the frequency meter the same as set on the generator. If measured frequency is lower – dial should be rotated CCW, if higher – CW.

After calibration press the “Dial” and then CH1 to return to normal operation.
73, Val
Brilliant. Adjusting frequency sends new values to registers 0x25 to 0x2A which are used during start up  :-+
I don't know what is inside but we now have a way to find out.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 24, 2018, 05:14:16 pm
I will try tomorrow if all goes right this weekend. Family first off course.

Thanks for the effort nevertheless.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 24, 2018, 05:16:36 pm
That could mean a way with a lookup table minimize jitter perhaps?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 25, 2018, 03:13:21 am
Is there an easy to source alternative to replace the PSU inside?

I found a nice small switching supply on Digikey for about $38 that would both fit and work nicely.  But you would still have to add the three terminal AC socket to fix the AC leakage problem.  In the end I decided against it, opting instead to simply upgrade the output capacitors and add a lossy ferrite core to the output cable to damp the switching noise.   I never observed the large swings on the +/- 13V rails that other's have observed.  My 5V rail puts out almost 5V exactly.   These mods only cost a few $ as opposed to $38 which more than 1/2 the cost of the 6600 anyway.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 25, 2018, 04:47:11 am
Yeah spending 50% of the cost of the unit on upgrading the psu doesnt make any sense , I happened to find a clapped out dvd player with a psu with the appropriate rail voltages though . 10 quid 1:1 isolation transformer as found in a shaver panel socket fixes the leakage problem nicely too .

I was thinking, another way to help with bit munching digital attenuation would be to make an old school switchable attenuator and putting it across the output ,and just run the outputs balls to the wall full on ,might well improve the THD levels especially at smaller output signal levels .

I downloaded Fremens special software package too  ,looks very promising ,tomorrow I'll give it a whirl hooked up to the unit and report back ,I also noted the spelling of 'Control' was fixed in that window ,something that caught my eye the first moment I loaded the original Feeltech app .

I got two of the TI 3095 op amps mentioned way back in this topic ,would a recalculation of the feedback resistor be required here in order not to upset voltage scaling ?

Shoehorning in some ten turn preset pots on the amplitude adjustment might be a good plan too ,its fiddly to try and accurately adjust single turn micro presets ,where ten turns would allow us to trim things very much more accurately .

What really makes this project for me is that we've drawn in expertise from every corner of the globe ,and were suceeding in making a humble box of tricks into something which punches well above its weight and learning tons about whats going on under the hood in the process.
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 25, 2018, 04:54:22 am
Channel 2 Output waveform intermittent distortion.

check out this on Ch2 of my FY6600.  Channel 1 does not have this problem.  Any suggestions?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 25, 2018, 08:51:47 am
Yeah spending 50% of the cost of the unit on upgrading the psu doesnt make any sense

Unless it's fun.

Mains leakage scares me.  I don't like the sound of it or the responsibility to understand when it will and when it won't blow stuff up on me.

Like if I want to test a 3 channel mixer breadboard, 2 channels from the FY6600 and one channel from my phone which it's connected via USB to earth ground.  I'd rather not smoke my £300 phone! :)

I still have a unpopulated spot on my EE jumper where the "Built my own PSU" badge goes.  Building a linear mains +-12V +5V supply sounds like a nice project.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 25, 2018, 09:02:15 am

I still have a unpopulated spot on my EE jumper where the "Built my own PSU" badge goes.  Building a linear mains +-12V +5V supply sounds like a nice project.

Will there you go!   Finding transformers you like are usually the hardest part.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 25, 2018, 09:05:07 am

I still have a unpopulated spot on my EE jumper where the "Built my own PSU" badge goes.  Building a linear mains +-12V +5V supply sounds like a nice project.

Will there you go!   Finding transformers you like are usually the hardest part.

Yes.  That and when you look up "How do I pick a transformer" I realise I also lack the "I understand calculus" badge. :(  AC sucks.

The whole VA rating thing might as well be Voodoo to me.  I'm left looking for transformers that have a "Maximum secondary current" spelled out in the datasheet.

Finding a multi-secondary to provide 2x12V + 1x5V seems a next to impossible to.

Probably need another thread in Beginners, but... can I not just drop the +12V side down to 5V with a reg?  Can I just series the 2x12V from the transformer and take the centre point at common?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 25, 2018, 09:31:06 am

I still have a unpopulated spot on my EE jumper where the "Built my own PSU" badge goes.  Building a linear mains +-12V +5V supply sounds like a nice project.

Will there you go!   Finding transformers you like are usually the hardest part.

Yes.  That and when you look up "How do I pick a transformer" I realise I also lack the "I understand calculus" badge. :(  AC sucks.

The whole VA rating thing might as well be Voodoo to me.  I'm left looking for transformers that have a "Maximum secondary current" spelled out in the datasheet.

Finding a multi-secondary to provide 2x12V + 1x5V seems a next to impossible to.

Probably need another thread in Beginners, but... can I not just drop the +12V side down to 5V with a reg?  Can I just series the 2x12V from the transformer and take the centre point at common?

Hello, let me help you, first but this trafo, it has all you need:
https://www.ebay.de/itm/Netztransformator-230V-8V-1-7A-4-2V-0-15A-13-6Volt-2x0-6A-Mittenanzapfung-NEU/152891642048 (https://www.ebay.de/itm/Netztransformator-230V-8V-1-7A-4-2V-0-15A-13-6Volt-2x0-6A-Mittenanzapfung-NEU/152891642048)

Second, of course you can use the 12V and put a linear regulator to make 5V out of it, but it will be a horrible design, for every 1W on 5W, you're wasting 2W of heat, that will make the nerd Baby Jesus cry  :'(.

So, get yourself this trafo, 2 rectifier bridges, one 4700uF/16V, 2 x 2200uF/35V, 3 tantalums of 1uF/35V, even 3 x 0.1uF, one 7815 (+15V), one 7915(-15V) and one 7805 and carefully place them on radiators and you're done, the PCB can be a piece of breadboard, after all is tested, carefull unsolder the original connector or buy a ne one and connect the cable. Fertig !!!
NOTE: If you're using +/-15V you may want to replace the 16V capacitors from the signal board, if you want to use 12V replace 7x15 with 7x12.

 Cheers,
 DC1MC 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on February 25, 2018, 09:46:02 am

I still have a unpopulated spot on my EE jumper where the "Built my own PSU" badge goes.  Building a linear mains +-12V +5V supply sounds like a nice project.

Will there you go!   Finding transformers you like are usually the hardest part.

Yes.  That and when you look up "How do I pick a transformer" I realise I also lack the "I understand calculus" badge. :(  AC sucks.



The whole VA rating thing might as well be Voodoo to me.  I'm left looking for transformers that have a "Maximum secondary current" spelled out in the datasheet.

Finding a multi-secondary to provide 2x12V + 1x5V seems a next to impossible to.

Probably need another thread in Beginners, but... can I not just drop the +12V side down to 5V with a reg?  Can I just series the 2x12V from the transformer and take the centre point at common?

You don't really need calculus for this.   In this application you need +/- 13 VDC and +5 VDC.   The +5 needs to be stiffer (in terms of current) than the 13V rails.  If you were to drop down from a +13 volt rail you would be wasting a lot of power and loading that rail much more than the negative rail.  This likely drives up the transfomer size more than necessary.   Most of the designs I've seen for this particular application use two transformers.  A center-tapped 2x12 or 2x15V for the +/- 13 VDC and a 8 or 10V transformer for the 5V rail.  If you can find a multiple secondary transformer that is ideal of course.   If you can find them in your junk bin the right size great.

Using Digikey as an example source, there are no transformers I can find with the three wingdings desired.  So that leaves a CT 12 or 15V and separate 8 or 10V transformer. 
My FY6600 draws less than 10W.  So we can use pretty small transformers here.   Looking at the PS board of the FY6600 would guess the 13V rails are a small fraction of an amp each and the 5V rail maybe approaching an amp at most.   Since the size of the transformer does not scale linearly with cost, it's safest to oversize them somewhat if you have space.  This keeps them cool and lets you sleep easier.

For the +/-13 V rails the Triad FS24-500-C2 is rated at 500mA for each of it's dual secondary windings.   If you series the primaries you can use 230V in England  (240 would also work).  This transformer is rated 50/60Hz.   For the 5V rail the Triad VPP20–1000 is rated at 1A using both it's 10V secondaries in parallel.  You series the dual primaries as before for operation at 230/240 50/60Hz.  Both of these transformers are PC board mount (mount on perf), but you can find flying lead versions easily but likely cost a bit more.   Other companies offer equally good units.  Each of these cost about $12 or so.   

I also see just as I'm posting this that another member has posted an Ebay link to a multiple secondary transformer on Ebay at a very good price.

Good Luck

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 25, 2018, 09:59:29 am
"Versand: Möglicherweise kein Versand nach Niederlande"
I am assuming the same for UK

@paulca
Does your local municipal recycle centre allow you to browse/takeback  brown goods?
Mine does not anymore, so you have to be sneaky. (they claim they can be held responsible if they allow people to take back faulty stuff)

But if so, typical non-digital era audio amplifiers/preamps have transformers in them that have +/- 15 V for the amp stuff, as well as usually a 12V or 6V rail for auxiliary stuff.
Or you can spend money and get those new (https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=r-core+transformer&_sop=15), but personally I always feel extra pride/smart/aware by repurposing old stuff.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 25, 2018, 10:02:36 am
"Versand: Möglicherweise kein Versand nach Niederlande"
I am assuming the same for UK

@paulca
Does your local municipal recycle centre allow you to browse/takeback  brown goods?
Mine does not anymore, so you have to be sneaky. (they claim they can be held responsible if they allow people to take back faulty stuff)

But if so, typical non-digital era audio amplifiers/preamps have transformers in them that have +/- 15 V for the amp stuff, as well as usually a 12V or 6V rail for auxiliary stuff.
Or you can spend money and get those new (https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=r-core+transformer&_sop=15), but personally I always feel extra pride/smart/aware by repurposing old stuff.

Drop a mail to the seller, you'll find understanding, in the worst case I can act as "relay" if anybody wants it.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 25, 2018, 10:43:13 am
Output frequency calibration.
...

Brilliant. Adjusting frequency sends new values to registers 0x25 to 0x2A which are used during start up  :-+
I don't know what is inside but we now have a way to find out.

That could mean a way with a lookup table minimize jitter perhaps?

So, just in case I was wrong about my "unmuteable fixed clock and PLL" theory, I did some tests.
Alas, correcting the frequency does not actually change the frequencies jitter.
For example, normally 10MHz square is perfectly jitter-free, due to being a perfect divider of 250.

Correcting it to 9.900000 cause the jitter to appear on 10MHz (which is now actually 10.010101MHz), and 9.900000 (which is now actually 10.000000) still is jitter free. To me that shows they are not changing the clock, just count more or less ticks of it, and the jitterfree points stays fixed on the frequencies as they are dividable on the 250MHz clock.
So I see no way how we can use this to reduce the jitter issue.

While it does not make the jitter worse, it does make it less predictable / less easy to calculate.
For example, if you were to set a realistic correction value of 9.999982, you'd get these jitterfree values:
(https://i.imgur.com/Keqy06h.png)
I often use some of these, usually not because the jitter actually matters to the circuit, but mostly because the scope screen is easier to read without those annoying double lines.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 25, 2018, 10:52:34 am
Thanks.

I tried every search under the sun on ebay and it never shows me transformers I want.  That r-core search showed loads.  I conclude that ebay search is rubbish.  How come "Transformer 2 x 13 VAC" doesn't find anything, but there are literallly hundreds of r-core transformers with 2 x 13 VAC in the title... and the related items show non r-core transformers with similar outputs.  Grrr.

What about something like this:
https://www.ebay.co.uk/itm/1x-220V-30W-R-Core-Transformer-R-TRANSFORMER-for-stereo-DAC-board/151254842393?hash=item23377dbc19:g:n1AAAOxyf1dTJG-G (https://www.ebay.co.uk/itm/1x-220V-30W-R-Core-Transformer-R-TRANSFORMER-for-stereo-DAC-board/151254842393?hash=item23377dbc19:g:n1AAAOxyf1dTJG-G)

2x15V 2x9V 30W

Of course the next challenge is learning how to wire it up without blowing stuff up while trying to work out how to series the primaries for 230V and parallel the 2x9V secondaries for 0-9V.  I understand if I short a secondary the fuse, nor RCD will help keep the smoke in.

I'm keen, but maybe out of my depth... although sometimes the deep end is the best place to learn to swim.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 25, 2018, 10:59:43 am
I tried every search under the sun on ebay and it never shows me transformers I want.  That r-core search showed loads.  I conclude that ebay search is rubbish.  How come "Transformer 2 x 13 VAC" doesn't find anything, but there are literallly hundreds of r-core transformers with 2 x 13 VAC in the title... and the related items show non r-core transformers with similar outputs.  Grrr.

Ooops, I was stuck in a sub category.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 25, 2018, 11:25:30 am
From memory, I recall under 200mA or so on the 12V and under 400mA or so on 5V. So 6~7W total.
Linear would waste a bit more but 10W should be enough.

So that 30W does seem a bit overpowered, but then a again, a similar 10W model (https://www.ebay.com/itm/282415016375) is almost the same size.
The one DerKammi DC1MC found is actually slightly smaller still, and at €4.5 pretty cheap, if you manage to get it into the UK at not too much extra cost.

As to wiring. Well, that's petty basic. Good thing about about transformers is they usually take a few seconds, even at a short, before they start releasing smoke.
Simply put a slow 0.1A fuse (https://www.ebay.co.uk/itm/170776131200) on the 240V side if you feel anxious though, that should go with a 30W short.



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 25, 2018, 12:05:02 pm
Well I bought the german ebay one, but I have to ask the seller if they will ship the UK.

I put the request in English and Googlese German:

Können Sie an eine britische Adresse versenden?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on February 25, 2018, 12:11:17 pm
Well I bought the german ebay one, but I have to ask the seller if they will ship the UK.

I put the request in English and Googlese German:

Können Sie an eine britische Adresse versenden?


Good idea.
Shipping with DHL is 8.89EUR without tracking and 13,99EUR with tracking. The seller shouldn't do anything special, except buying an international shipping label from the same EBAY page where it buys its German ones.
Now collect the other parts as well and you're done.  8)
 Cheers,
 DC1MC - "Waiting in a fetal position to get a power n-mos from a kind German soul, but none so far :("


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 25, 2018, 01:27:37 pm
Not sure if it would break your "badge earning rules" but to complete it, have you seen these (https://www.ebay.com/itm/322598834251)

I kind of agree you need to build your own at least once (did mine 30+ years ago), but boy, for $3 I can barely even pick up the needed 7805/7812 at the local component shop.
(also, all local component shops either perished, or are only selling complete gadgets and drones nowadays)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 25, 2018, 02:00:32 pm
Not sure if it would break your "badge earning rules" but to complete it, have you seen these (https://www.ebay.com/itm/322598834251)

I have a couple of those, cybermaus (15v and 12v), and the ouputs are not very well balanced (something like +12.0, -12.7 on the 12v model).  When I made my linear I went for the variable voltage version so that I could ensure that the outputs were balanced, and also to give flexibility to increase the outputs up to +/-15v if a future mod should require it.  The board is a lot bigger, but it still fits nicely in the case with a 15v/9v r-core transformer (as you can see from the photo I posted a couple of pages back).

If you want to build your own, it's still cheaper to buy the kits from China to get the parts, then do your own layout on Veroboard.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 25, 2018, 02:42:20 pm
The CMOS function allows negative offset. Did I miss something or is the CMOS function supposed to be always positive?

I think this could also be usefull to foresee a minimum and a maximum output parameter when connecting sensitive DUT...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 25, 2018, 02:59:45 pm
Thanks for the help guys.  I will move the discussion on building my PSU to the Beginners's forum shortly.  Don't want to pollute the product thread.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 25, 2018, 04:00:03 pm
Tiny update from my side
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 25, 2018, 04:25:51 pm
Is the CMOS not just simply a quick way to set a signal level square?
Possibly the only special thing is: If you increase Vpp, it does not dive negative.

Whereas if you make your own 3.3Vpp 1.65Voffset square, and increase to 5Vpp, it would accidentally go negative first, before you remembered to also change offset to 2.5V
(I have had that problem, luckily my DUT survived)


But to be honest: I feel all waveforms should consider that 0V case. If I have a Vpp and Offset such that Vbottom is 0V or even positive, then merely changing Vpp should not make it negative. Or some sort of boundary setting. (edit, reading back, I realize you were saying the same)

Right now, the only waves that are bottom based are I think CMOS, half-sine, rectified-sine (and of course, negative half-sine is top based)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 25, 2018, 04:38:16 pm
I have a couple of those, cybermaus (15v and 12v), and the ouputs are not very well balanced (something like +12.0, -12.7 on the 12v model).  When I made my linear I went for the variable voltage version so that I could ensure that the outputs were balanced, and also to give flexibility to increase the outputs up to +/-15v if a future mod should require it.  The board is a lot bigger, but it still fits nicely in the case with a 15v/9v r-core transformer (as you can see from the photo I posted a couple of pages back).
Odd. They are 7912's, how are they able to mess that up?
I can only see that happen you had a bad 7912 itself. I guess that is possible

If you want to build your own, it's still cheaper to buy the kits from China to get the parts, then do your own layout on Veroboard.
Which then negates that. Maybe the other way around, buy a new local 7912 and solder it onto the chinese PCB.


Anyway. Anything is possible with these cheap things from eBay. Sometimes very good value, sometimes not even worth the space they take up in the garbage.
The only reason I keep buying it (when not in a hurry) is that if I buy local, it is also junk from china, just someone else did the ordering for me.


Unless if Mouser of course. But you know, €20 handling fee, always.
I do sometimes order with them, but not the small stuff.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 25, 2018, 04:45:00 pm
The only reason I keep buying it (when not in a hurry) is that if I buy local, it is also junk from china, just someone else did the ordering for me.

Unless if Mouser of course. But you know, €20 handling fee, always.
I do sometimes order with them, but not the small stuff.

I agree.  The UK Ebay at the moment is unfortunately infested with Chinese seller with UK addresses, claiming the item location as UK, when it clearly isn't and takes 2 to 4 weeks to arrive if it ever appears.  You have to read seller names and addresses carefully to filter out the bad ones.

I don't order from Mouser, but RS Components or for a sizable order Farnell.  RS have free shipping and no handling charge for any size of order including a single 0.1p resistor technically.  Though you would feel like a bit of a dick doing that to them.

The downside I find is that for some components the price they leaves you running your hands under cold water cause you feel burnt.  Panel volt meters.  You can find pretty decent ones on Ebay for £5.  RS components, unless you want an analogue one they are in the £30-70 range!  There are many other examples. Breakout boards are fierce price too.  Even something mickey mouse like an SOIC-8 to DIP adaptor board is like £8 each!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 25, 2018, 05:27:47 pm
Absolutely no need to be intimidated by the numbers when calculating power supplies Paulca.
Take your winding voltage ,multiply it by 1.4 ,now from this you have to subtract the losses across the diodes in the bridge ,then you'll still have to allow at least a few volts extra so that whatever regulator you have can function effectively without dropouts .
Google Duncans PSUd 2 ,thats a really handy little tool for mocking up your psu's before putting money into components ,after a few uses of this software you'll get a feel for what your doing and the intimidation factor will be a distant memory. The more voltage the regulator has to drop the bigger the heat sink will need to be  , also the more voltage drop across the reg also tends to give a quieter noise level at the output.
Best o luck.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 25, 2018, 06:03:12 pm
Is the CMOS not just simply a quick way to set a signal level square?
Possibly the only special thing is: If you increase Vpp, it does not dive negative.

Whereas if you make your own 3.3Vpp 1.65Voffset square, and increase to 5Vpp, it would accidentally go negative first, before you remembered to also change offset to 2.5V
(I have had that problem, luckily my DUT survived)


But to be honest: I feel all waveforms should consider that 0V case. If I have a Vpp and Offset such that Vbottom is 0V or even positive, then merely changing Vpp should not make it negative. Or some sort of boundary setting. (edit, reading back, I realize you were saying the same)
Yes security for the DUT was the point. In the new firmware, I have at least 3 options: either I just reset the offset when selecting CMOS (as a positive offset could also leads to destruction of the DUT) or I send a null offset when  the CMOS function is in use... or I just let it like this and this will be secured later on with min and max output parameters for all functions... The last one beeing my prefered ATM.
For the other bottom based functions, using the offset does not seem to be a problem.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 25, 2018, 06:52:59 pm
Tiny update from my side
Better each time :-+

May I suggest these modifications?

W16: DC_AMPL_CH2_OFFSET
W3: DC_AMPL_CH2_GAIN

W26: DC_AMPL_CH1_OFFSET
W5: DC_AMPL_CH1_GAIN
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 25, 2018, 06:55:25 pm
Choices, choices.....

I do feel that going from any wave to CMOS should avoid going over 3.3 (5) or below 0, unless you specifically set that.
But I also feel that having set Vpp and offset, and then walking from Sine to Triangle or so, should not loose your values because you happened to walk past CMOS

To be honest, I think apart from your idea to set an optional per channel DUT voltage safety window, when walking through the waveforms they should not immediately apply, but only after you confirm. So you can go from one wave to the other, without generating all the waveforms in-between. This is unlike walking through frequencies, which of course should immediately apply.


In fact, in the hope that FeelTech would pick it up, a good while back I already mentioned (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1335080/#msg1335080) that pressing the Wave button is auto-advancing, which is wrong anyway:
Right now, if I am on Square, and I want to go to Sine (one to the left), I always first have to go to CMOS (one to the right) and then go 2 back. Just plain silly.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 25, 2018, 07:17:49 pm
Absolutely no need to be intimidated by the numbers when calculating power supplies Paulca.
Take your winding voltage ,multiply it by 1.4 ,now from this you have to subtract the losses across the diodes in the bridge ,then you'll still have to allow at least a few volts extra so that whatever regulator you have can function effectively without dropouts .
Google Duncans PSUd 2.

Thank you.  The "time 1.4" thing leads me to ask "why 1.4" which leads to a rabbit hole.  But... I have seen it used enough without caveat that maybe I should just trust it.

I was also considering the drop on the linear regulators and thus aiming high for +-15V to provide +-12V as +-13VAC are hard to find.  Also once you factor in the drop across the recifier 13V will become 12.3 volts quickly. 

Different engineering, but in software when I can't calculate (or don't want to calculate) exact values, I just double the estimates to provide a suitable margin.

Going for +-15V for a +-12 rail through a transformer is not quite doubling, but lets not split hairs. :)

Quote
Best o luck.

You know in an odd way that makes a difference to a post.  I might have had half (+50% engineering grace) a bottle of wine, but for me it suggests you took to the time to actually care that I have luck and you weren't just show boating your knowledge.

The point of this post, having too much wine asides...

It's the VA rating that bothers me.  When a transformer says it has a rating of 6VA,  what does this actually mean in real terms?  Especially if you want to run a given DC load off it?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on February 25, 2018, 07:57:46 pm
Choices, choices.....

I do feel that going from any wave to CMOS should avoid going over 3.3 (5) or below 0, unless you specifically set that.
But I also feel that having set Vpp and offset, and then walking from Sine to Triangle or so, should not loose your values because you happened to walk past CMOS

To be honest, I think apart from your idea to set an optional per channel DUT voltage safety window, when walking through the waveforms they should not immediately apply, but only after you confirm. So you can go from one wave to the other, without generating all the waveforms in-between. This is unlike walking through frequencies, which of course should immediately apply.
So then we could go for a mix: Protection via min/max voltage (to be set before connecting the DUT...) and then anyway sending null offset (without loosing the value) when in CMOS.
But once activated,  over range voltage protection should not depend on the selected wave. Once your DUT is connected it should be protected whatever you could do.
In fact, in the hope that FeelTech would pick it up, a good while back I already mentioned (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1335080/#msg1335080) that pressing the Wave button is auto-advancing, which is wrong anyway:
Right now, if I am on Square, and I want to go to Sine (one to the left), I always first have to go to CMOS (one to the right) and then go 2 back. Just plain silly.
Yes indeed. You can imagine the following:
- 1 push on wave button: highlight wave selection (selection mode)
- another push on wave button: cancel selection mode
When in selection mode:
Turn rotary knob to go through waves without modifying the current one (wave plot having another colour to show selection mode active)
Confirm your choice by pushing the rotary knob..
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 25, 2018, 08:17:57 pm
Tiny update from my side
Better each time :-+

May I suggest these modifications?

W16: DC_AMPL_CH2_OFFSET
W3: DC_AMPL_CH2_GAIN

W26: DC_AMPL_CH1_OFFSET
W5: DC_AMPL_CH1_GAIN

That is why I post the small updates. Consider it done 😁
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on February 25, 2018, 08:37:39 pm
Yes indeed. You can imagine the following:
- 1 push on wave button: highlight wave selection (selection mode)
- another push on wave button: cancel selection mode
When in selection mode:
Turn rotary knob to go through waves without modifying the current one (wave plot having another colour to show selection mode active)
Confirm your choice by pushing the rotary knob..

Exactly. For the Wave.

For others, like frequency, a small variant:

- 1 push on freq button: highlight freq selection (selection-follow mode)
- another push on freq button: different color highlight (selection-confirm mode)
- yet another push on freq button: cancel selection mode, no more highlight.

When in selection-follow mode:
- Turn rotary knob to go through frequencies *with* modifying the frequency,
- As the frequency is set automatically, it stays the normal color

When in selection-confirm mode:
- Turn rotary knob to go through frequencies *without* modifying the current one
- As the frequency is not set, it stays the special UNSET color
- Confirm your choice by pushing the rotary knob, now color returns to the SET color, until you turn the rotary again.
- Canceling your choice (by pressing freq button again, while color is the UNSET color, displays the original frequency and non-highlighted color


So while we have 2 modes for frequency (follow and confirm) and analogue the wave has only one mode (confirm), I would argue for frequency the follow mode is the first one, whereas for wave the confirm mode is the first (and actually only) one.

Amplitude and Offset may also have similar follow and confirm modes, so you can either jump from one to the other, or walk to it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 25, 2018, 08:40:22 pm
Thanks for that Paulca ,
The 1.4 thing is just a rule of thumb ,different factors like load regulation of the transformer  and actual current vs rated current all add variables into the equation . When speccing a transformer for a given job ,you have to not only calculate the output current ,but also add in the ac current handled by the smoothing capacitors too ,typically over speccing your transformer by 50% compared to the load current is a good starting point , as we have seen the power consumption of the FY6600 is about 10 watts max , a 20 watt rated core here will run nice and cool  ,where a lower VA rated component might run hot and because its at the edge of its capabillity magnetic leakage/interference and noise  starts to become a bigger issue also . The great thing about the old style linear supply is that if its nicely over specced for the job you can be sure of a very long and trouble free life , switchers tend to have a limited lifespan ,and once capacitor values stray beyond a certain margin catastrophic failure isnt far off .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 25, 2018, 09:06:58 pm

I don't order from Mouser, but RS Components or for a sizable order Farnell.  RS have free shipping and no handling charge for any size of order including a single 0.1p resistor technically.  Though you would feel like a bit of a dick doing that to them.


I didn't realise RS had free postage on online orders now, but I've just checked and you're right - although I'm sure when I ordered some stuff from them a few months ago I had to add a load of basket fillers to take the value over £25 to get the free delivery.  I've also just found that they've got a branch nearby, which could be handy.

I was quite interested in Insatman's D75J TCXO from Digikey until I saw the price: £8 for the pinhead sized component (not too bad when you consider what it does), and £12 for the postage!  But I could have it delivered free if I bought another £20+ worth of basket fillers to go with it.  I think I'll just live with the 4ppm error I've got. (And it's stable within 10 minutes.)

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on February 25, 2018, 09:09:28 pm
Hi!

Trying to find a good economically priced small transformer with two suitable secondaries small enough to go in the FY6600's case is like trying to find a needle in a haystack with eBay's useless search engine, but I located this one - it's a low-profile R-core transformer of 30VA rating, the two 9V secondary windings can be connected in parallel IF you are careful of course to give 9V @ 1.4A. Best of all, it has dual-primary 115/230V for world-wide application plus an inter-winding screen as well!

I've ordered one to try in mine!

https://www.ebay.co.uk/itm/115V-230V-30W-High-Quality-Audio-R-Core-Transformer-15V-15V-9V-9V-For-Preamp/131588122667?hash=item1ea343682b:g:PfgAAOSwBadTpmyy (https://www.ebay.co.uk/itm/115V-230V-30W-High-Quality-Audio-R-Core-Transformer-15V-15V-9V-9V-For-Preamp/131588122667?hash=item1ea343682b:g:PfgAAOSwBadTpmyy)

Opinions please?

Chris Williams

PS!

Suggestion for 5V linear supply to use with above transformer:-

https://www.ebay.co.uk/itm/L7805-Step-Down-7-5V-35V-to-5V-DIY-Kit-Power-Supply-Module-new-UK-seller/271656192244?hash=item3f3ff888f4:g:2lAAAOSw1XdUV6q1 (https://www.ebay.co.uk/itm/L7805-Step-Down-7-5V-35V-to-5V-DIY-Kit-Power-Supply-Module-new-UK-seller/271656192244?hash=item3f3ff888f4:g:2lAAAOSw1XdUV6q1)

Suggestion for ±15V dual linear PSU module for use with above transformer:-

https://www.ebay.co.uk/itm/AC-DC-Voltage-Regulator-LM317-LM337-Adjustable-Filtering-Power-Supply-DIY-Kits/302371834320?hash=item4666c409d0:m:m3whryg5vfLibDo-QTtc79w (https://www.ebay.co.uk/itm/AC-DC-Voltage-Regulator-LM317-LM337-Adjustable-Filtering-Power-Supply-DIY-Kits/302371834320?hash=item4666c409d0:m:m3whryg5vfLibDo-QTtc79w)

NB!

The links I've provided refer to kit items, to facilitate substitution of higher quality electrolytic capacitors in the designs, etc. I believe the maximum current ratings of these kits are suitable for adequately powering the FY6600's electronics, but please feel free to correct me if I'm wrong!

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 25, 2018, 09:16:44 pm
Another quick update before going to bed.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 25, 2018, 10:11:17 pm

Trying to find a good economically priced small transformer with two suitable secondaries small enough to go in the FY6600's case is like trying to find a needle in a haystack with eBay's useless search engine, but I located this one - it's a low-profile R-core transformer of 30VA rating, the two 9V secondary windings can be connected in parallel IF you are careful of course to give 9V @ 1.4A. Best of all, it has an inter-winding screen as well!


That's the transformer I used, Chris - it's light, cool and, as far as I can tell, very low noise (as r-cores are supposed to be).  I only used one 9v secondary, which is more than enough for the job, as I thought I'd keep the second one free to drive a fan if it needed it (it doesn't).

The bipolar board is also the one I used; it's got nice big tits smoothing capacitors on it, which is a good thing, and it produces very little heat.  It's bigger than it looks in the picture, but still fits in the case ok.

As you've got an adjustable 12 - 15v supply, and as you can't guarantee that the 5v module will actually deliver 5v, why not allow yourself some leeway and get the LM317 version for a few pence extra, then you can dial in whatever exact voltage you want?  (I set mine to 5.1v to give a little extra headroom for the regulators on the main board to play with).  I didn't use the 5k pot that comes with it,  but mounted a multiturn trimpot on a piece of veroboard and put that in its place.  I also left off the switch, and the big spring connectors (I used a screw connector block instead).

The transformer and modules are all fixed with nylon spacers and screws, and I fitted a switched earth wire to the 0v line on the bipolar board so that the whole thing can be either earthed or floating.

Enjoy yourself putting it all together!

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Chris56000 on February 25, 2018, 10:40:21 pm
Hi!

Quote
As you've got an adjustable 12 - 15v supply, and as you can't guarantee that the 5v module will actually deliver 5v, why not allow yourself some leeway and get the LM317 version for a few pence extra, then you can dial in whatever exact voltage you want?  (I set mine to 5.1v to give a little extra headroom for the regulators on the main board to play with).  I didn't use the 5k pot that comes with it,  but mounted a multiturn trimpot on a piece of veroboard and put that in its place.  I also left off the switch, and the big spring connectors (I used a screw connector block instead).

Thanks for your tip Dave - I do industrials at work where I routinely have to fit new 7805s and the ones my employer buys are literally pot-luck as to how accurate they are!

As the FY6600 is only known to take 400-500mA @ 5V, me thinks this one is perfect, not needing anything anything omitting, chucking-out or the board altering! I've ordered one!

https://www.ebay.co.uk/itm/LM317-Adjustable-Power-Supply-Board-With-Rectified-AC-DC-Input-DIY-Kit/401482358932?epid=21010444566&hash=item5d7a36a094:g:2NsAAOSwaLdaaDEO (https://www.ebay.co.uk/itm/LM317-Adjustable-Power-Supply-Board-With-Rectified-AC-DC-Input-DIY-Kit/401482358932?epid=21010444566&hash=item5d7a36a094:g:2NsAAOSwaLdaaDEO)

Chris Williams




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 25, 2018, 11:07:28 pm
That's just the job, Chris.  How have I not come across that one before?  (I've now ordered a couple for the bits box.)

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 26, 2018, 01:52:45 am
I tried out Fremens tweeked software earlier ,thats really handy that it runs seamlessly with the original , even the small changes to the look of it so far is a big improvement over the original ,the white text on black/grey backround looks great ,and the bigger waveform window helps too .

Tomorrow I might try making a steel screening plate to sheild the main boards from any radiated noise from the psu , I might also ask a friend with serious test gear and sixty years electronics experience to run through the unit and pass on any suggestions he might have for improvements .

Apart from non destructively fitting the other psu I had ,I havent done anything yet that voids my warranty , Id prefer to get a few hours up on it and do proper functional tests before filing and drilling ,just in case it has to go back.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 26, 2018, 02:20:00 am
I tried out Fremens tweeked software earlier ,thats really handy that it runs seamlessly with the original , even the small changes to the look of it so far is a big improvement over the original ,the white text on black/grey backround looks great ,and the bigger waveform window helps too .


I agree.  I gave the software a run out as well (Control window, anyway), and it's a big improvement in layout and appearance compared with the original.  All the functions work as they were intended - only the offset display and sliders need more work, but, as fremen said, they aren't a priority at the moment.  Thanks again for what you are doing, fremen67!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Propretor on February 26, 2018, 02:27:50 pm
Hi!
Is there a difference in hardware from the models FeelTech FY6600 60MHz and FY6600 30MHz?
Or the difference is only in FW?
Is there a problem with the FW version? I correctly understood that versions 3.0 and 3.1 are bad, and 2.9 or 3.2 are successful?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 26, 2018, 03:23:28 pm
Hi Prop,
Welcome aboard,

As far as we know the lower end units have the limitations imposed in the front panel firmware ,and due to the dedication of the talented contributors here we're well on the way to jailbreaking it.
The current firmware revisions on offer seem to be 3.2 and 3.21 ,and so far no reports of problems with these .
I ordered my unit mid January and received V3.2 ,the ebay seller was called 'echoii_shop' ,another contributor got V3.21 but you need to scan back through the posts to find the suppliers name. For me, the good spirited nature in which people have given their time and energy to this project made me want to get involved.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 26, 2018, 04:20:57 pm
Well, buying that transformer from Germany has turned into a bit of a farce.  He added 8.00Euro shipping, but switched the payment method to "Money transfer".  I hit "Transfer" and confusingly it just went to a page with nothing of use on it.  I figured from the Google translated german that I had to hit this to get the sellers bank details.

I tried to use Western Union, who were going to charge me something like £6!  But they would not accept my credit card.

So I tried my bank and it would not let me send the money without knowing the exact name and address of both the receiver and his bank.

So I'm now trying to cancel the order.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on February 26, 2018, 05:02:10 pm
The links I've provided refer to kit items, to facilitate substitution of higher quality electrolytic capacitors in the designs, etc. I believe the maximum current ratings of these kits are suitable for adequately powering the FY6600's electronics, but please feel free to correct me if I'm wrong!

I have ordered the same kits.

Is it worth replacing the caps or just run with the ones in it?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 26, 2018, 08:22:00 pm
@Fremen67: Just had a go with your PC software and it is working very nice already. Major thanks to all the work done so far.

Cannot image the work you are going to do on the firmware of the generator. Very promising.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Propretor on February 26, 2018, 08:22:29 pm
Thanks for the answer soundtec. If I correctly understood you, the chips are used the same and the difference is only in the firmware?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Propretor on February 26, 2018, 08:27:59 pm
Colleagues, I do not see the point of changing the switching power supply in the generator. After it there are linear stabilizers. The only thing that makes sense is the ferrite rings on the cable that connects the power supply to the main board and place the power supply inside the metal screen. All the rest does not make sense.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 26, 2018, 09:47:21 pm
Colleagues, I do not see the point of changing the switching power supply in the generator. After it there are linear stabilizers. The only thing that makes sense is the ferrite rings on the cable that connects the power supply to the main board and place the power supply inside the metal screen. All the rest does not make sense.

Thanks for your views, but the power supply was built down to a price, not up to a quality.  Never underestimate the inclination of inquisitive meddlers to obtain pleasure and satisfaction from simply doing the work, whether it makes sense or not.  Some of us do it simply because we can, others because they want to improve their knowledge and skills.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 26, 2018, 09:54:25 pm
Yeah thats my reading of it anyway Propretor,  theres others in here who would be able to explain a lot more precisely the differences between  the models. Its looking like we may have the abillity to link to the generator board itself using a pre programmed chip very similar to what exists in the front panel already ,and thats opening up a few options in terms of the user interface etc,new software and extending the functionality of the 6600.

As for the power supply , It seems the output op-amps at least run directly off the +/- 12 volt rails , I have measured some small dragging down on the 5 volt rail as you increase the amplitude of the output signal ,that means things are modulating to some degree at least . The primary reason people want to include a transformer is for the isolation it provides ,there was a concern with leakage from the standard switching arrangement due to lack of mains grounding also.
I kind of have my options open as far as different power supply arrangements, I'm  running off a switcher for now ,but not the original feeltech part. I might try adding a seperate 5 volt switching rail  and a 1:1 mains transformer , but I also have the right transformers and regulators to do a linear supply later on if I choose too .

There's downsides to both , one plus of the linear approach is that a well designed system could give faultless performance for 30 years or more , the switcher psu lifespan ,its an unknown . The switcher potentially has high frequency garbage on the line,the transformer  could cause magnetic interference ,extra screening between power supply and the other boards would be a good plan in any case .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Propretor on February 27, 2018, 01:30:13 pm
I understand what you're talking about Dave. I myself am so. But in this case, I will confine myself to eliminating the Y capacitor in the power supply and installing the ferrite rings.
I'm worried about something else. After reading this forum (and I do not know English well, I apologize) I became frightened. There were reports that with some versions of the firmware the generator was dying. At the same time it is irretrievable. I would like to avoid this.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Propretor on February 27, 2018, 02:22:57 pm
These reports terrify:
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1411280/#msg1411280 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1411280/#msg1411280)
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1399618/#msg1399618 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1399618/#msg1399618)
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1410592/#msg1410592 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1410592/#msg1410592)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on February 27, 2018, 03:08:11 pm
Hi Propretor,

The instances of dead devices appear to be restricted to those with firmware versions 3.0 amd 3.1 only.  So far, there are no reports of any problems with version 3.2 so we hope that Feeltech have corrected the fault.  It was the dead devices which prompted the urge to reverse engineer the device and try to develop a better, more stable firmware for it.

The power supply issues don't appear to be linked to the firmware problem, so you can do as little or as much to it as you like - but bear in mind that not doing enough has the potential to lead to the death of other devices you connect to it!

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 27, 2018, 08:04:01 pm
How is this for version control. Both are V1.501 boards. Just spotted a subtle difference.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 27, 2018, 08:46:57 pm
Aside from a different clock chip ,I can also spot a missing smd resistor on the second board ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bsudbrink on February 27, 2018, 08:49:01 pm
Immediately above L1, the via was widened into a test point and a flood fill area was added.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 27, 2018, 08:49:54 pm
Oh yeah, couple of extra pads closeby the clock on the second board too ,I wonder which one was the latest revision ,were they both shipped with the same firmware as well ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 27, 2018, 08:59:40 pm
Both V3.2.

The one with the testpad it is not connected anywhere. The one with the via is connected via R16 to the FPGA.

Both are coming from the HC245 and are buffering via J11 the VCO in signal. But the connection is made to J10 to the VCO in so this whole signal is useless.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 27, 2018, 09:30:23 pm
Had some schematic capture activity as you may have guessed. 98% is in. Missing are the decoupling caps around the FPGA and the 2 jumper pairs. Also the counter input is missing.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: seronday on February 27, 2018, 11:15:43 pm
   If anyone with a 15Mhz or 30Mhz version of the FY6600 needs to generate a waveform with a higher output frequency, this can be done by creating an arbitrary waveform of 2 or more cycles.

For example using the FeelTech PC software, create an arbitrary sine wave of 4 cycles and load this into the FY6600.
When this wave form is generated, the output frequency will be 4 times what the FY6600 frequency is set to.
So if the frequency is set to 15Mhz, the output will be 60Mhz.

Keep in mind that the limitations of the DA converter and output op amps still apply.

Regards.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on February 27, 2018, 11:51:04 pm
That Schem is looking real good Derkammi,
Great work .

Hi Seronday,
That sounds like a really neat trick ,isnt it funny how sometimes lateral thinking can provide a simple solution to what seemed like a much more difficult problem, I cant wait to test it out tomorrow . Mr Feeltech wont be happy  |O :-DD

I got out my metal snips today and made a sheild for the PSU section .I used the two screw holes where the original power supply attached to mount the bulkhead.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on February 28, 2018, 06:24:09 am
Also made a small update of the front panel schematics as the unknown signal PA0 is actually the VCO_IN, so the ADC of the micro is used.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 01, 2018, 12:42:02 am
Quick update: Phase 1 is almost over  :)
The basic functions are working with my dev board. I have now to swap it with a bluepill board and create a profil for it in my project.
I also have some modifications on PC Software to do as I added 18 new commands to the official serial protocol. I will add a switch to inhibate new functions so this could still be compatible with official FY6600.
I finally added the configurable min/max output limits for DUT protection and inhibated the offset for CMOS and Adj-Pulse.
If everything goes right, this might be over before end of this week.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 01, 2018, 01:29:25 am
Your status as a Living God will soon be confirmed, fremen  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sdouble on March 02, 2018, 02:37:12 am
say half-god for the moment  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on March 02, 2018, 06:41:01 am
Or demi-god, sounds more French  ^-^, but seriously, I'm impressed in the best way possible, and Feeltech should be as well, we've managed to rescue their almost failed project, if this thing we'll have an open-source panel firmware, there in no other better development and experimentation platform. I mean of course, you can get a solid AWG from somewhere else, but it will just be a box without any possibility of improvement or self-improvement of the owner.
This little plastic gadget offers so much more, if one just wants to use it, soldering a socket and wire is not a problem, if it wants to go to the next level, there are a lot of things to be done to get increasingly better performance and train yourself in electronics, mixed signal processing and, most important, fine soldering and a bit of mechanics ;). And let's not forget, a lot of software is available and get's better by day.

I went 2 days to the Embedded World, and the future of affordable TE is indeed Chinese, the established elephants and gorillas increasingly isolate themselves and see their market share dwindling. Hell, even Owon came with some nice models.
And I've really liked the new SA with VNA from Siglent, they won't send me one as I don't have a YT channel, but Dave's it's on its way ;), and the kid in the booth told me winking that "our products remain software unlockable", so it's nice to see what will come out of it.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 02, 2018, 08:56:33 am
Yes the Chinese are gaining very fast. They are not the master of copying any longer but are more the creators of stuff these day.
They even will beat the Germans in soccer in due time. I don't want to talk about the Dutch team past years :(

But I'm more anxious about fremen67 his software luckily.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on March 02, 2018, 11:17:01 am
With regards the software being produced in this thread.

Did the author have any access to the original code?  Was that code copyrighted?

If the answer is yes to both then it cannot be legally open sourced without the copyright owners permission.  Doing so could result in a "cease and desist order" or court at worst.

Of course this depends on the license agreement under which Feeltech shared the code.

To open source software via reverse engineering it must be done in white/clean room conditions with no access to the original code.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 02, 2018, 11:52:43 am
Written from scratch with reverse engineering the protocol between the µC and the FPGA.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: khach on March 02, 2018, 03:00:23 pm
Any idea about unpopulated U302 IC? Is it possible that U302 is PLL clock generator for jitterless mode operation? Of course, different FPGA core design need for that mode.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on March 02, 2018, 05:58:01 pm
Re :copyright possible legal issues.

I see no Eula section when I load up the Fy6600 computer control software .

I think its fair to say Feeltech will certainly be keeping an eye on developments here ,even though they stopped contributing to the post a good while back . At any rate once Fremens work of genius is complete ,theres nothing to stop Feeltech pinching the code back and upgrading the functionality of the fy6600 with it , If I was them I'd be considering offering Fremens a consultancy position as software developer.
My guess is feeltech are more concerned about other rival companies producing hardware very similar to their own ,end of day what were doing here will only increase the desirabillity and sales of their product , any attempt by them to shut down our efforts here wouldnt do them any good at all .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on March 02, 2018, 06:40:42 pm
To open source software via reverse engineering it must be done in white/clean room conditions with no access to the original code.

Good news! FeelTech won't share their source code.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 02, 2018, 11:17:00 pm
Hello for everybody! It's my first post on the forum and in this thread. Sorry in advance for my poor English, not my native language.
I've been reading this thread since I decided to order FY6600 in the beginning of the year,  a lot of useful infos here!
I have got my unit at February 16, played with it and now decided to join to the forum and to this thread particularly.
First some remarks about the generator as is without any modification. I got it from ebay (echoii_shop), luckily version 3.2, board revision 1.501.
The generator works normally with quite decent calibration: 5.04Vp-p , 30mV offset (5Vp-p, 0V offset, 10kHz sine  settings).
The timebase is a pretty accurate also: -4 ppm after 30 min warm-up with +/-100 ns jitters, planning upgrade generator anyway.
An interesting thing is the switching power supply. As I can see it is a new variant. It has the same problem of leakage current: 90Vac relative PE (my mains is 230V).
But when I measured output voltages I was surprised: +5V under load was exactly +5Vdc (4.9976Vdc on my Fluke 289), and higher voltages were  +12.04Vdc
and -12.08Vdc . In standby mode voltages were +5.0000V :-DMM, +11.877V and -11.940V respectively. And absolutely no adjustment components in the unit :-//!
So no dangerous output voltages in any mode. I check output pulsations, 30mVp-p on +5V bus that is well enough and much worse 300mVp-p on +/-12V buses.
Think I could live with this PSU after modifying it to eliminate the leakage current problem of course.
Now more interesting part of my post ;). I am a quite experienced designer of FPGA based systems, particularly of Altera's repertoire. 
So I can make a few educated conclusions about main board of the generator.
1. As someone already found CycloneIV get its configuration from Winbond's flash and this configuration data is located in the beginning of the chip. Judging by its size
   configuration data are uncompressed. Configuration for Altera's FPGA can be in compressed form that may occupy 30-50% less of memory if we decide to make our own design.
  No problems to write a new configuration by USB interface through the front panel MCU as FPGA has full access to the flash. There're two possibilities:
  MCU can rewrite a portion of the flash with configuration data (if I got it right MCU can write into flash addresses) they are not used after configuration was load.
 But if something goes wrong we get a brick that can be revived only by programming flash with a dedicated cable. So more advanced perspective.
 CycloneIV has remote upgrade mode. In it there are few configurations: one factory one that is never erased and one or more application configuration. The factory configuration is
 load on power-up reset and after it can load any specified application configuration. This process can be controlled by FP MCU. If loading of the application configuration fails
 the chip returns to the factory configuration with indication of a reason for error. So the factory configuration can be used for writing a new working configuration into the flash
 and starting this new configuration after it or after power-up reset. In this case we will always have a fallback procedure if something goes wrong.
 And now main question: for what could we be wanting to modify generally quite good design? Some thoughts.
2. We can enhance square wave generation providing settings for rise/fall times. Concerning 4ns jitters of edges not much can be made here as PLL circuit in the chip is quite limited,
   it can provide frequency Fref *M/N where M,N=1..512, too coarse for any decent frequency resolution. CycloneV has fractional PLLs which could provide a frequency resolution of
  order of a part of a Hertz in our case but we have CycloneIV :(.
3. But PLL in CycloneIV allows easily to use TXCO quartz generator of 10MHz that can facilitate upgrade to external 10MHz precision time reference. Moreover the PLL in CycloneIV can be
   reprogrammed in running chip without reloading of configuration, so we can adjust the same configuration for different reference clocks by MCU in working system.
4. We can add new functions. In the flash can be written a stream of bits (128K at most) instead of an ARB waveform. And that stream can be output as CMOS pulses or any other pulses bit by bit
   with set frequency, amplitude and etc or used as modulating signal for carrier signal (ASK? FSK and so on). It would be useful for testing and debugging digital systems particularely
  digital data transmission ones.
5. Use sigma-delta modulation to get more resolution from DAC when generating lower frequency signals. But I am not sure here as DACs are already overclocked
and might have not very good linearity. This requires additional investigation, unfortunately I haven't got relevant test  devices for it.
6. Something else....
If there is an interest in the community I could contribute to such efforts.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 02, 2018, 11:48:14 pm
It's hard to find words.  Welcome and thanks for joining the conversation.

If corrections calculated at audio frequencies were found to be applicable at higher frequencies I think we should be able to correct DAC linearity errors by means of a soundcard and a test program which generates predistorted waveforms,   But I know little or nothing about the DAC side of things.  If the errors vary with frequency it would still be possible to correct the errors using data from a DSO.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on March 03, 2018, 02:14:13 am
Welcome Comrade Zov ,

Im sure your expertise and familiarity with the Altera series will be definate bonus to our mission .
My Russian language skills are non existant ,not to mention the cyryllic script which I can not pronounce .
And actually the only thing that stopped me from becoming lost forever on a trip on the Moskow underground was a helpfull person who wrote down  the name of the station I needed to get to phonetically in roman alphabet .
Anyway several of your fellow countrymen are involved already so Im sure we can iron out any glitches in the language matrix . 8)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 03, 2018, 06:51:32 am
Zov, great post. Equally great to have a Russian on board with Altera skills. A lot of Russians with hacking skills in my opinion so this me be gold to have.

I did know that we could configure the FPGA at boot with the SPI bus as slave and master but I don't know if the reading of the arb signals is done bij a NIOS core or that we just fill some memory where we write with the STM32 and the FPGA just read this part.

But writing a new config for the FPGA is beyond my knowledge, I can read read what is done by others but writing from scratch is to much.

1.   Is there a way to read the config from a non compressed config data? or is this still encrypted in some way as I have read some CycloneIV datasheets.
2.   2,3 and 5 together as we have a new config we also can reduce the clock and not overclock the DAC to reduce the low linearity and take advantage of the better fractions available to reduce jitter.
3.   This sounds very interesting I must say, this would mean a huge upgrade to the whole ARB system currently used. I guess we need to generate signals on the fly with some power from the micro. Really use the 72Mhz of the CPU.

I truly hope you stay aboard to make this "dev" board the greatest AWG for the the price. Together with fremen76 his efforts this would be possible.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 03, 2018, 10:28:48 am
Here it is. Finally the first release for Blue pills. :)

More comments later on. I will be back this evening. Enjoy!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 03, 2018, 10:34:07 am
GREAT, going to try this asap. Thanks fremen. Willing to post the source?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sokoloff on March 03, 2018, 06:59:21 pm
This might be considered "salami pricing". The company I used to work for made a product to read electrical power meters. They also made a reader/programmer to program these same meters. The reader sold for $3000 and the reader/programmer for $5000. I worked on this line of products so I knew the only difference was the code contained in the eprom that told the unit what to do. I asked a marketing representative how they could justify charging that big difference for basically no physical difference and he told me they were charging for functionality.
Exactly.
Quote from: Theodore Levitt
People don't want to buy a quarter-inch drill; they want a quarter-inch hole.
The programmer product had additional functionality that the customer values; it also has additional coding, sales, and support costs on top of what the reader-only unit has. It's not reasonable for a business to solely price products based on the physical cost plus a fixed markup.

When it comes to test equipment, I don't mind companies that try to segment the market this way. I also don't feel bad about using hacks to modify my own test equipment as I see fit. I choose to support manufacturers with reasonable policies on these things.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 03, 2018, 07:20:17 pm
Thanks for your kind words!
About CYCLONE configuration. I am pretty sure there isn't NIOS processor inside the configuration. It needs a program memory
but the size of the configuration data provides strong evidence that there is only pure configuration without any program code.
NIOS can run from internal memory but there is very little one in used CYCLONE, only 30 kB and that memory is needed for waveform sample storing (see below).
No doubts that existing configuration read waveform samples from the flash into the internal memory buffer (16kB BTW from 32kB available) before
provide that to the output. 250Msamples/s is at the upper limit of the used CYCLONE chip and the flash can't provide that speeds of reading anyway.
About reverse engineering CYCLONE configuration from its uncompressed/compressed data (they only differ by sizeof data, no extra encryption) I think it is out of our capability.
About 3000000 configuration bits needs some automated software tools to restore a source design. And BTW in which forms, Verilog, VHDL, schematic? Didn't hear
about such capabilities anyway. If we made a new configuration we certainly can made a special mode in it where SPI interface of FP MCU would be directly
translated to the flash pins so no problem reprogramming it with any new data from USB interface.
And last but not least for the moment. I have already a few ideas about implementation of such configuration especially about its DSP part. But now it's time for me going on vacation
so I can start this work only as early as end of the March / beginning of the April. So you could consider any new desired functionality for a while and then I try implement it later if possible.
Of course without fremen participation all that could not be possible as I am not familiar with FP MCU programming and debugging.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 03, 2018, 11:18:45 pm
I have already a few ideas about implementation of such configuration especially about its DSP part. But now it's time for me going on vacation so I can start this work only as early as end of the March / beginning of the April. So you could consider any new desired functionality for a while and then I try implement it later if possible.
Of course without fremen participation all that could not be possible as I am not familiar with FP MCU programming and debugging.
Welcome Zov! I would be glad to help  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 03, 2018, 11:26:01 pm
GREAT, going to try this asap. Thanks fremen. Willing to post the source?
Thank you! Waiting for your feedback. As soon as it is stable, I will open a github and post the source. I am still working on this version right now. I should have waited some more days to finish it but it is the week-end and I know you want homework  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 04, 2018, 12:11:24 am
@fremen67 Will the new FW run on the FeelTech FP or is it just a PC UI at this stage?  It looks very nice.  I got the impression it was PC only, but I've been more focused on my Zynq adventures and haven't kept up. 

As I read PM0075 p 19, although the flash is read protected, we can force a mass erase and reprogram the device.  Is that correct?

I've ordered a couple of the ST Link programmers from eBay.  I'm sure I could use one of my dev boards, but when I saw yours I went looking and at  $2.54 decided it was well worth having a couple.

I'm very much looking forward to getting my borked V 3.1 unit working properly.

Many thanks to all for their work on this.  I find a delicious irony in forcing FeelTech to accept GPLed FW on their hardware.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 04, 2018, 01:40:53 am
@fremen67 Will the new FW run on the FeelTech FP or is it just a PC UI at this stage?  It looks very nice.  I got the impression it was PC only, but I've been more focused on my Zynq adventures and haven't kept up
It is both. The firmware is for a bluepill board which by-passes the Feeltech FP but it could also work as well in the Feeltech FP. The UI is the other part, modified Feeltech PC Software to be able to talk to the new FW. The main modification in the PC Software is not only the look of the UI but the fact that it reads back values from the new "FP" when they change, and also allows new functions that have been added (like output range limit for DUT protection). Those functions are handled directly in the new FW, not in the UI.

As I read PM0075 p 19, although the flash is read protected, we can force a mass erase and reprogram the device.  Is that correct?
Yes the feeltech FP can be reflashed. I have a second unit (15Mhz) that I will reflash later on when working on the LCD part.

I've ordered a couple of the ST Link programmers from eBay.  I'm sure I could use one of my dev boards, but when I saw yours I went looking and at  $2.54 decided it was well worth having a couple.
In fact the bluepill board is not my dev board. I just modified the FW which is running on my dev board (HY-STM32) to run on this low cost board. This should allow every one to give it a try for 2 or 3$.
If you are interested, please join and flash a blue pill : the more feedback, the best for the quality tests  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on March 04, 2018, 05:01:59 am
Ive got the various bits of kit needed for the jailbreak on order ,its somewhere between here and Shenzen town now. Im an old fashioned valve/tube/lamp guy and even though Ive tinkered around with computing for over 35 years, a code buster,Im not .
The spirit of human endeavor I've found on the FY6600 topic transcends flags ,politics and media driven stereotypes by a mile,and it gives me hope for the future ,a million miles from the sheepish mass social media frenzy that dictates the lives of so many nowadays.
Too many names to mention for their contributions ,saluts to all who've got involved.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 04, 2018, 06:48:21 am
GREAT, going to try this asap. Thanks fremen. Willing to post the source?
Thank you! Waiting for your feedback. As soon as it is stable, I will open a github and post the source. I am still working on this version right now. I should have waited some more days to finish it but it is the week-end and I know you want homework  ;)

I did some testing yesterday but somehow the PC software stops working as soon as I connect the FPGA wires, maybe some wire up fault on my side. Not sure yet.

Had to stop my hobby time due to a water fountain in the garage due to the freezing temperatures. Nice cut in the piping :(

Back on it this evening I hope.

Can I add you on my Github to keep things in one place?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 04, 2018, 07:14:24 am
Thanks for your kind words!
About CYCLONE configuration. I am pretty sure there isn't NIOS processor inside the configuration. It needs a program memory
but the size of the configuration data provides strong evidence that there is only pure configuration without any program code.
NIOS can run from internal memory but there is very little one in used CYCLONE, only 30 kB and that memory is needed for waveform sample storing (see below).
No doubts that existing configuration read waveform samples from the flash into the internal memory buffer (16kB BTW from 32kB available) before
provide that to the output. 250Msamples/s is at the upper limit of the used CYCLONE chip and the flash can't provide that speeds of reading anyway.

All makes perfect sense. Writing waveforms in a piece of RAM and putting it out on the DAC is indeed the limit of the device as I thought.

Quote
About reverse engineering CYCLONE configuration from its uncompressed/compressed data (they only differ by sizeof data, no extra encryption) I think it is out of our capability.
About 3000000 configuration bits needs some automated software tools to restore a source design. And BTW in which forms, Verilog, VHDL, schematic? Didn't hear
about such capabilities anyway.

The synthesize thing is giving a complete different output than one would image, so too bad then :)

Quote
If we made a new configuration we certainly can made a special mode in it where SPI interface of FP MCU would be directly
translated to the flash pins so no problem reprogramming it with any new data from USB interface.
And last but not least for the moment. I have already a few ideas about implementation of such configuration especially about its DSP part.

Interesting

Quote
But now it's time for me going on vacation so I can start this work only as early as end of the March / beginning of the April. So you could consider any new desired functionality for a while and then I try implement it later if possible.
Of course without fremen participation all that could not be possible as I am not familiar with FP MCU programming and debugging.

We are not moving that fast, so a vacation is pefect for you to come up with some nice ideas ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 04, 2018, 08:16:30 am
fremen67, what is you clock config? I made an config with CubeMX as attached
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 09:00:07 am
It's not working!

I stared at the wires on Fremen67's foto's and PDF diagram, checked, double-checked, and its not working.

Symptoms:
- Both LED's on the bluepill are on
- No signal on the channels
- PC does see the COM10 connecting on USB
- PC software does work on COM10 with original FB
- PC software tells me nothing connected on the PORT with bluepill

So, I stared at the wires for a while. Unfortunately my wires are not the same rainbow as fremen's, but I tried to match them.
And also my bluepill has its headers on the other side of the board, so you have to think mirrored.
But still, I am pretty sure they are all correct.

Someone else wants to stare at my wires for a while, and point out where I went stupid?
Thanks, photo's attached.

(Note the white-gray on the 4-pin is unclear, because the white teared a strip of black along, making it also gray-ish, and the gray is reflecting light, making it also white-ish. And I have two red's. sorry, but so does Fremen67)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 09:41:52 am
Ripped it all out, did it again, not taking note of fremen's original colors, but instead making sure they were nicely and easily aligned.
Neatness if often the key, makes it all better to work with.
Used the PDF to check each one of them, rather then the foto's

Exact same result.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 09:53:13 am
Thinking about it:

Since it is not even showing as connected, it is tempting to think the problem may be in the TTL-UART wiring.
However, that would only be true if the software is such that it still acknowledges the UART if it has a problem with the FPGA connection.

So question to Fremen:
- If the FPGA connection is not properly there, does the software still talk successful with the PC?
- if not, could it easily be made in such a way, to benefit diagnostics?

Alternatively, could there be error-flashing on the LED? (blue pill led, or if real FB, power led)
Something like:
- FPGA not responding, flash 2x
- UART not responding, flash 3x
- LCD not responding, flash 4x


Just a friendly suggestion of course, not intending to bother you too much because I am apparently bad at wiring things.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 04, 2018, 10:40:24 am
Had some more looking into the signals from the bluepill and it does not send any signals on de spi bus.

When de FPGA is connected I cannot connect to the micro but as soon as I disconnect all spi wires I get a connection to the micro again.

The FPGA ready signal is going low but after that all is silent. Some IO mapped wrong maybe? I swapped some wires back and forth but with no different results.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scratch.HTF on March 04, 2018, 11:57:52 am
I decided to turn my FY6600 (60 MHz) into a high frequency clock generator (this was my intention when purchasing the FY6600) with the unit set to Square (required for a proper output - the waveform data is at full scale for each transition), along with fitting in a GPS disciplined oscillator module (with an additional power supply and line filter with an IEC input so that the unit can be grounded) and PLL multiplier for the waveform timebase.
Since the NB3N502 (powered by +5V) was tuning to the third harmonic of the +3.3V level clock applied to the clock input pin; a miniature 1uH series inductor was enough to cure this problem; the buffered clock output also has problems with duty cycle and ringing at frequencies below 1 MHz.
Relays (telecom type) marked "A" are switched together and I wired the NB3N502 to be switched between x2 and x5.
The NB3N502 PLL clock multiplier was stable up to 190 MHz at +5V even though the input frequency had some jitter due to a characteristic of the generator where the DAC clock is fixed at 250 MHz (and that the PLL has some degree of input stabilization) – I did get the PLL multiplier (using a +5V supply) to output a stable 250 MHz clock with a stable 50 MHz input, and it appeared to work at up to 320 MHz – despite the minimum output frequency specification of 14 MHz, it was stable right down to a 2 MHz output!

Stable frequency ranges with this circuit were (using a TI 74HC74 connected to +5V):
0.5x (direct via 74HC74 divide by 2): 0-16 MHz
1x (PLL x2 and 74HC74 divide by 2): 1-34 MHz
2x (PLL x2): 2-76 MHz
2.5x (PLL x5 and 74HC74 divide by 2): 2.5-27.5 MHz
5x (PLL x5): 5-190 MHz
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 04, 2018, 12:16:05 pm
@cybermaus & @DerKammi

Red led ON means problem during initialization. In that case serial link does not work (I should have spend for time on that.. I know :-//).

Try this: just connect the 4 wires ribbon (+5V, ground, TX, RX) and ground /FPGARDY(PA1) and SPI2_MISO(PB14) on the bluepill.

Initialization should complete now ans serial link should work (Red light flash when receiving data).

Not sure you both have 3.1 version... Maybe some timings issue...

I will be busy till late today... sorry I can't help more right now...

In all cases, modified PC software should work with original FP.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 04, 2018, 12:42:52 pm
How nice is that. Just wanted to test... And lights out... Grid down
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 12:57:59 pm
That's impressive! I don't think I will be able to do that.

Trying now though....
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 01:16:20 pm
Well, power stayed on here, so I think you did something wrong.

Only connected 4-wire plus gnd, b14, a1
Same result (both LED solidly on)

Tried 3 startup-modes:
- First power, then USB-UART
- First USB-UART then power
- Both connected, then press reset button
All same result

Also, I had a logic analyzer on the UART, and other then power-on spike, I never got any byte in either direction.

Indeed, I have a 3.1



Also going outside now. Its nice weather.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sokoloff on March 04, 2018, 01:30:04 pm
Well, power stayed on here, so I think you did something wrong.
:-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 04, 2018, 02:31:22 pm
Well it was a big power out in the region, but I think I can be pretty sure that it wasn't my fault |O :=\ :=\ :=\

But power is back no and did some testing again and the result is the same, connect anything to the FPGA and it won't init.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 02:47:06 pm
Tangent: In the nineties, at a business relation in financial centre Londen (I am in ICT), right at the time they were making even transformer intelligent with a simple protocol superimposed on top of the power lines..... a large data center UPS gave just the right noise on the line to confuse the utilities' district distribution. They put a large portion of London's banking district without power twice that day, and then got into a legal shouting match with the utilities.

Moral: It could have been you! Did you install a proper EMI filter on the FY6600?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 04, 2018, 04:33:15 pm
I understand what you are saying, but...

I have done way worse things to the grid without EMI filters in the line.

But the statement of the grid company is that something had to do with the cold weather. Vague general statement they made. But I feel safe doing it again 😂
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 05:10:58 pm
...read waveform samples from the flash into the internal memory buffer (16kB BTW from 32kB available) ...
Remember there is two channels. So that would be all 32KB used up, with not a single byte left for anything else.

I do not know much about FPGA, but maybe those registers and stuff are not RAM, but CLB & IOB states, and not counted toward its memory?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 04, 2018, 07:59:38 pm
Remember there is two channels. So that would be all 32KB used up, with not a single byte left for anything else.

I do not know much about FPGA, but maybe those registers and stuff are not RAM, but CLB & IOB states, and not counted toward its memory?
I forgot about second channels  |O thank you! So no memory left for any other tasks. Implementing memory in LABs (it is equivalent to CLB in Altera's parlance) is too costly from resource point of view.
BTW it is only 6000 LE in the used chip so no more then 6 kbit can be implemented.

Considering your remark about 2nd channel I need rethink my plans for implementation somehow.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 08:35:03 pm
Considering your remark about 2nd channel I need rethink my plans for implementation somehow.
Not sure how serious you are with FPGA redevelop, but if you have that in you and memory is an issue: I for one would be quite happy to go from a 8Ksample AWG to a 4Ks AWG if it would give me more features like: sweep trigger in/out, External sync in/out, etc. Or the holy grail: no jitter (though as you mentioned, not really possible, but you did mention N/M clock ratio's, so with intelligent scheme we could increase the number of sweet spots frequencies)

You could even go half/half: 8Ks on channel A, 4Ks on channel b (by reading only every other byte from the flash)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 04, 2018, 08:53:27 pm
[
Not sure how serious you are with FPGA redevelop, but if you have that in you and memory is an issue: I for one would be quite happy to go from a 8Ksample AWG to a 4Ks AWG if it would give me more features like: sweep trigger in/out, External sync in/out, etc.

Do the external trigger input and sync input and outputs on the back panel not work?  That was the reason I chose it over the JDS.  Mine borked itself before I got that far in my testing.  I for one would hate to give up the longer waveforms as it would lead to more spurs.

However, if there is room in the flash we might be able to select the waveform lengths or generate some of them with the FP  MCU to save space.

Enjoy your vacation Zov.  Your return will be eagerly awaited by all.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 09:07:07 pm
It was also part of my reason. Mostly VCO (sweep) but also you never know what you need, so sync in/out BNC and TTL output headers.

Turns out those sync in/out are not classic 10MHz sync, but they are to sync two FY6600 to each other.
Its actually what the manual also states. Did not test because I have only one.

Measuring them, it seems to be a simple 1Vpp pulse of the exact frequency of the one you dailed in. One may think that means you can hook up any other generator, but alas, I was unable to make my other generator generate a pulse that this one actually synced to. So it must be rather finicky to set right (I did not try extremely hard)

Of course we currently know how to make a normal 10MHz sync, so referencing to a standard clock is doable. But following an external frequency is not (unless if another FY6600)

To be honest, I am not sure about the trigger in, but there is no trigger out for the sweep start. It would be nice if the Sync-Out (presumably the only output) could be a sweep out, or alternatively, if ch-2 could be both output, and used for the sweep vco.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 04, 2018, 09:16:53 pm
Not sure how serious you are with FPGA redevelop, but if you have that in you and memory is an issue: I for one would be quite happy to go from a 8Ksample AWG to a 4Ks AWG if it would give me more features like: sweep trigger in/out, External sync in/out, etc. Or the holy grail: no jitter (though as you mentioned, not really possible, but you did mention N/M clock ratio's, so with intelligent scheme we could increase the number of sweet spots frequencies)

You could even go half/half: 8Ks on channel A, 4Ks on channel b (by reading only every other byte from the flash)
Frankly speaking no issues with memory for the moment, just held it aside as a reserve but alas :(.
And a question: what is the point in making square wave or a waveform with step change without jitter?  I have some thoughts how to make a subset of frequency with jitter decreased on order of magnitude (125 ps) but it would be quite limited set  anyway. And because of complexity of  their implementation it would be certainly very remote perspective.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 04, 2018, 09:44:16 pm
It was also part of my reason. Mostly VCO (sweep) but also you never know what you need, so sync in/out BNC and TTL output headers.

Measuring them, it seems to be a simple 1Vpp pulse of the exact frequency of the one you dailed in. One may think that means you can hook up any other generator, but alas, I was unable to make my other generator generate a pulse that this one actually synced to. So it must be rather finicky to set right (I did not try extremely hard)

AFAIK sweep mode in current implementation is under full control of FP MCU, it just change sweep parameter step by step through SPI. Of course it could be made a more intelligent way inside FPGA. No problem to make sync out with an assistance from FP MCU.

Measuring them, it seems to be a simple 1Vpp pulse of the exact frequency of the one you dailed in. One may think that means you can hook up any other generator, but alas, I was unable to make my other generator generate a pulse that this one actually synced to. So it must be rather finicky to set right (I did not try extremely hard)
If i got it right syncing of multiple units is implemented such a way that a master unit set start phase of waveform generation for all slave units which provide their waveform on their internal reference clocks. It could work well enough for frequencies up to units of megahertz but above an error would be quite appreciable.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 04, 2018, 09:52:53 pm
And a question: what is the point in making square wave or a waveform with step change without jitter?  I have some thoughts how to make a subset of frequency with jitter decreased on order of magnitude (125 ps) but it would be quite limited set  anyway. And because of complexity of  their implementation it would be certainly very remote perspective.
Yeah, I was thinking about the same just now.
Came to the conclusion that with 512:512 ratios, you should be able to get a perfect wave for 2.5 digits deep into the frequency selection.
So all XX.YnnnnnMHz frequencies, with all XX and half of the Y, as well as all X.XYnnnnMHz frequencies

How useful?
As I wrote before, the jitter probably does not matter for any actual DUT (unless if you are working really precise stuff)
But it does help a lot it keep your oscilloscope clean and readable, especially in the 5MHz and above range.
Any signal triggered on or based on that jitter makes the screen somewhat difficult to interpret because of the ghost lines.

I currently find myself often selecting exactly those frequencies 10, 12.5, 25, 32.375, for that reason.
Being able to do all XXMHz would make me happy. But is it worth the trouble? I do not know, because I have no idea of how difficult it is.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 04, 2018, 10:02:28 pm
How useful?
As I wrote before, the jitter probably does not matter for any actual DUT (unless if you are working really precise stuff)
But it does help a lot it keep your oscilloscope clean and readable, especially in the 5MHz and above range.
Any signal triggered on or based on that jitter makes the screen somewhat difficult to interpret because of the ghost lines.

And sine signal cannot be used for oscilloscope syncing? They have no jitter for any set frequency at all.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 05, 2018, 12:24:20 am
Well, power stayed on here, so I think you did something wrong.

Only connected 4-wire plus gnd, b14, a1
Same result (both LED solidly on)

Tried 3 startup-modes:
- First power, then USB-UART
- First USB-UART then power
- Both connected, then press reset button
All same result

Also, I had a logic analyzer on the UART, and other then power-on spike, I never got any byte in either direction.
Good news: I had the same problem with my second FY6600. The difference beeing my LA connected on the working one. I disconnected my LA and ... bluepill did not boot anymore....
Oups! I defined /FPGA RDY as floating input and my LA was pulling it down through its input resistance, hiding the problem. No LA, no pull-down... :palm:
Here is the modified FW with /FPGA RDY defined correctly as Pull-down input.
Sorry about that. :-[

It works on my second FY6600 like that so I hope this time it will work on yours.
At least your are now 100% sure about your wiring  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 05, 2018, 06:51:18 am
Good to know, I had a slight suspicion it had something to do with IO mapping :)

I'll try it this evening, work is making a dent in my free time.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 05, 2018, 08:09:24 am
Greetings from Finland!

I tested the latest hex file. First /FPGARDY & SPI2_MISO grounded to check PC - bluepill communication, this works ok. Then wired FPGA board to BP but this "hangs" BP, led stays on and PC connection does not work. I have 30Mhz v3.1 FY6600.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 05, 2018, 10:51:56 am
Tested first with the FPGA disconnected, PC connection works
Next with FPGA connected: PC connection still works, even able to sniff the UART (see below, simple freq change) but I am not getting any output on the channels.

Code: [Select]
57 4d 46 30 30 31 30 30 30 30 30 30 30 30 30 30  |  WMF0010000000000
30 0a 0a 52 4d 41 0a 35 30 30 30 30 0a 52 4d 4f  |  0..RMA.50000.RMO
0a 30 0a                                         |  .0.             


I also tried to sniff the SPI bus. During power on, I get a lot of stuff on CLK and NSS, but nothing on MOSI or MISO
When already on, and changing something in PC software, it typically does trigger my LA, but nothing shows on any of the wires.

Of course, running in 20MHz with 256K samples, I only get 13msec, maybe the LA needs to wait longer


To finish up, connected FB again, just to see if I had not blown a pin, but it all still works.


I only have one BP at the moment, the other is in use. Have some underway on the slow boat.
I'll try to hook it up to a display later, to see if SPI works properly on this Bluepill, but I suspect its not a hardware problem.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 05, 2018, 02:21:59 pm
Thank you for the feedback. I will flash this evening one of my FY with Rev.3.1 and have a look...
We are getting closer ... and it would have been too easy otherwise :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 05, 2018, 05:02:11 pm

Not sure if it matters or helps debug, but often when  I restart, the PC software comes with a new set of beginning parameters
Maybe some noise on the lines? Too many gnd connections, ground loop?

Most common seems Square 10KHz 2Vpp

But also seen on Channel 1:
squr 10KHz 1.5Vpp 0V
sine 60MHz 5Vpp 0V
sine 2MHz 2Vpp 0V
squr 10KHz 2Vpp 0V


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 05, 2018, 05:34:50 pm

Not sure if it matters or helps debug, but often when  I restart, the PC software comes with a new set of beginning parameters
Maybe some noise on the lines? Too many gnd connections, ground loop?

Most common seems Square 10KHz 2Vpp

But also seen on Channel 1:
squr 10KHz 1.5Vpp 0V
sine 60MHz 5Vpp 0V
sine 2MHz 2Vpp 0V
squr 10KHz 2Vpp 0V
Very interesting indeed. That could be the clue. Could you try to add a 10k pull-up resistor on RX and another 10k pull-up resistor on SPI2_MISO?
(on 3.3V of course).
I will be back in 3 hours. That could help a lot in the meantime.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 05, 2018, 06:20:53 pm
Very interesting indeed. That could be the clue. Could you try to add a 10k pull-up resistor on RX and another 10k pull-up resistor on SPI2_MISO?
(on 3.3V of course).
I will be back in 3 hours. That could help a lot in the meantime.

And it works...
So: 10K pull up to MISO (PB14)

Did not do a pull up to RX (yet)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 05, 2018, 07:37:08 pm
Some testing, actual errors: (just the one)

Chan 1 was set to SQUR, Channel 2 to Sine
I clicked all the sync checkmarks, and though now Channel 2 shows a grayed out SQUR in the PC, it still generated Sine. When stop/start channel 2 it became a SQUR

I assume sweep/mod/counter and fancy stuff like waveform upload are not there yet, right?


Anyway, I made a proper loom, so I can more easily reconnect for next tests.
Basically I took all the single dupont from the clips, and instead grouped them in fixed 3x 4x 5x 8x dupont headers.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 05, 2018, 07:46:15 pm
I just tested mine with a pullup on the MISO line, but no signals on the outputs. The whole interfacing seems to work and I see data on the MISO/MOSI lines with my scope, but no signals out.

You do have outputs Cybermaus?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 05, 2018, 07:59:43 pm
Yes, I have outputs on both channel 1 and 2

It still seems somewhat noise related. Even the first time I had it working, I had to stop and start a few times (power off and on) the device, and then suddenly it worked.
And then after I made my loom again it did not work, and after a few restarts it did. Whenever it does not work, green led stays on.

Key is that green led. If it turns off, you are initialized and it works, outputs nicely follow PC controls.
I think the noise makes it sometimes fail initialization. The pullup helps, but does not eliminate all noise, so its a bit of a try-again game.


You know, I used to work with audio frequencies, and breadboard and ad-hoc wiring is OK. But whenever I try and go about a few MHz, I find that all that spagetti wiring is really disruptive. Stray capacitance, inductance, loops cause all sort of ugly signals.

Here too, I think if we want reliable testing, we should solder a BP to a proper veraboard and proper headers directly for the FY6600 connectors, without any breadboard wiring in between.

PS: with no PC control, the BP seems to send out a channel 1 10KHz 2V square wave by default. So first keep USB unconnected, and turn on/off the FY6600 and/or reset the BP

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 05, 2018, 08:03:58 pm
It does indeed. So for further testing I would like to suggest to slow down the SPI clock to the sub MHz region perhaps, this makes wiring a lot easier. Speed is not really an requirement right now.

I'll hit the trial and error hammer a couple of times.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 05, 2018, 10:00:17 pm
Some testing, actual errors: (just the one)

Chan 1 was set to SQUR, Channel 2 to Sine
I clicked all the sync checkmarks, and though now Channel 2 shows a grayed out SQUR in the PC, it still generated Sine. When stop/start channel 2 it became a SQUR
Thank you for the feedback. I missed this one. A last minute change. Should be corrected in this release.

I assume sweep/mod/counter and fancy stuff like waveform upload are not there yet, right?
Waveform upload is there and should work.
For sweep/mod/counter no it's not there. Sorry about that but it was already a lot work to get there.

I added internal pull-down for MISO and internal pull-up for RX. With this configuration I have 100% boot up on BP. So you can now remove the externel pull-up resistors and test if it's better or not.

On the other FY with my dev board and the LA connected I never had any failure during boot-up so there must be a way...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 06, 2018, 04:41:06 am
FW version 0.2 tested. Randomly BP starts and then everything works fine. 30MHz unit works at 60MHz, this was really nice to see  :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 06, 2018, 06:22:26 am
New firmware v0.2, still with pullup: started on first try
Removed pullup, started on first try again.

Nice!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 06, 2018, 06:36:28 am
MOSI/MISO screenshots of the situation when BP does not boot.  What did you think about them?

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 06, 2018, 06:55:12 am
Not a SPI guy myself. But some suggestions:

- Lay your wire nice and straight, no spaghetti
- Short wires, no loops, and close together, keep the rainbow-ribbon whole if possible
- Turn off any nearby (cheap) electronics, like LED lights with bad transformers on ungrounded two wire connections

(I had to put my LED drivers into a earthed tin can, to get rid of the noise. And they were expensive local store bought office panels too, not even china. Still looking for better LED drivers)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 06, 2018, 07:27:25 am
Not a SPI guy myself. But some suggestions:

- Lay your wire nice and straight, no spaghetti
- Short wires, no loops, and close together, keep the rainbow-ribbon whole if possible

My BP wiring is short, last night made veroboard construction.


 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 06, 2018, 07:38:18 am
You need better grounding, the signals are floating in air and don't have a proper return path with this vero board layout.

Use copper tape under the wires and connect all grounds to this copper tape. If you don't have copper tape then please twist the signal wires with a ground wire.

I'm am doing this this evening hopefully as my spaghetti wiring is making things going haywire.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 06, 2018, 07:46:13 am
Strictly speaking true, but seems overdone. His veroboard is already 10x nicer then my wires, even if I did lay them straight.
So, I don't know, check for bad soldering connections ?

Anyway, today is a busy day, I should tell myself to stop checking this forum.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 06, 2018, 07:55:41 am
I can agree with you but my experience does show different. Loose wire does sometime work better than veroboard. Not always but it does happen. Twisting signal wires with ground does help in a massive way in the MHz range.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 06, 2018, 10:00:51 am
MISO signal is a source of BP problems. Small capacitor (470pf)  to gnd and BP always works. If you have an oscilloscope, check the  signal from your device. You should also look at the signal from the original front panel, it is very bad.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 06, 2018, 10:42:55 am
MISO signal is a source of BP problems. Small capacitor (470pf)  to gnd and BP always works. If you have an oscilloscope, check the  signal from your device. You should also look at the signal from the original front panel, it is very bad.
Well done :-+

Did you notice any update problem with modified PC Software on startup?

I will also define unused I/O pins as output and set them to 0 (except PB0 which is better to keep as an input). This should also increase BP noise immunity.
We may also add the 2x 300 ohms resistors in serial with TX and RX as it is done in the original Feeltech design (At least I think it is, DerKammi could confirm that.). Not sure this will help a lot for noise but at least this would be identical to original design.

I will try to release version with output pin modification this evening.
Unfortunately busy week at work and at home..
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 06, 2018, 10:54:53 am
We may also add the 2x 300 ohms resistors in serial with TX and RX as it is done in the original Feeltech design (At least I think it is, DerKammi could confirm that.). Not sure this will help a lot for noise but at least this would be identical to original design.

They are there on the main board to the connector already, I also don't think there is a problem on the serial side.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 06, 2018, 11:15:49 am
Did you notice any update problem with modified PC Software on startup?

Update problem? I do not really know what you mean? I have not noticed any problems.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 06, 2018, 12:28:41 pm
Did you notice any update problem with modified PC Software on startup?

Update problem? I do not really know what you mean? I have not noticed any problems.
cybermaus noticed random values when launching PC Software, see here https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1444331/#msg1444331 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1444331/#msg1444331)

Default values when starting BP are the one you can see on the screenshot here:
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1441974/#msg1441974 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1441974/#msg1441974)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 06, 2018, 01:24:29 pm
cybermaus noticed random values when launching PC Software, see here https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1444331/#msg1444331 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1444331/#msg1444331)

Just tested several times, I always get the right values. Only when generator is offline results are strange, see pic.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on March 06, 2018, 05:40:30 pm
Even though I don't know enough to contribute to the software/firmware side of the FY6600, I am following this with great interest. Keep up the good work, I'm sure there are many others watching your progress.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ewald1963 on March 06, 2018, 05:58:25 pm
Sure there are undoubtly many other, I am one of them. Great respect for those guys doing a lot of work!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 06, 2018, 08:30:27 pm
Well, finally tested the 0.2 version. And it does work nicely thus far. But not on both devices I have.

My own works fine but Mark his unit isn't listening to the BP. When operated with the FP all is fine. Not sure where to start trouble shooting.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 06, 2018, 08:45:40 pm
Just a though: That was a a broken V3.0 unit, right?

It is possible the FPGA has smaller or larger changes between the versions, and thus it is possible you need to match FPGA firmware with STM32 firmware. For all we know, they made a small but significant change to the SPI protocol. Maybe you need to bring the FPGA to V3.1

What version did Fremen69 use to develop?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 06, 2018, 08:52:15 pm
Both are 3.2 I'm afraid
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 06, 2018, 09:07:47 pm
Well, finally tested the 0.2 version. And it does work nicely thus far. But not on both devices I have.

My own works fine but Mark his unit isn't listening to the BP. When operated with the FP all is fine. Not sure where to start trouble shooting.
Do they have both a modded power supply? Otherwise you could try swapping the mainboards ...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 06, 2018, 09:11:01 pm
Also the same. Clock is running at the DAC but no data.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 06, 2018, 09:47:49 pm
Just a though: That was a a broken V3.0 unit, right?

It is possible the FPGA has smaller or larger changes between the versions, and thus it is possible you need to match FPGA firmware with STM32 firmware. For all we know, they made a small but significant change to the SPI protocol. Maybe you need to bring the FPGA to V3.1

What version did Fremen69 use to develop?
Indeed, configurations of FPGA for different version has been changed. I have checked it comparing flash contents for V3.1 and V3.2. They differ in FPGA configuration data part of them.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 06, 2018, 10:43:26 pm
Also the same. Clock is running at the DAC but no data.

Just a though: That was a a broken V3.0 unit, right?

It is possible the FPGA has smaller or larger changes between the versions, and thus it is possible you need to match FPGA firmware with STM32 firmware. For all we know, they made a small but significant change to the SPI protocol. Maybe you need to bring the FPGA to V3.1

What version did Fremen69 use to develop?
Indeed, configurations of FPGA for different version has been changed. I have checked it comparing flash contents for V3.1 and V3.2. They differ in FPGA configuration data part of them.

Swapping the boards (or the FP) will show any compatibility problem between version.

The reverse engineering has been done on a V3.2 version. We know that BP is also working on V3.1 (cybermaus for example).
We have no clue right now if it is working on other versions.

Should it be the case, I would need a V3.0 dump to test it.

I compiled a new FW version with all unused Pins configured as outputs. It would be interresting to see if it improves noise problems..

I think I will add another functionnality that would be interresting for testing: the possibility to have a fixed output range. This will allow exploring the full output ranges at different frequencies, thus finding the best thresholds for switching the outputs.
This function will also be usefull later on if you don't want relays switching during your tests.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 07, 2018, 05:15:52 am
I'll try to read out the flash chip thus evening to see whether I have differences.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 07, 2018, 06:28:03 am
fremen, do you know whether there is calibration info send out to the FPGA?

Yesterday during testing I saw the PP voltage of a sine drop when I went over 5V, thus switching to the opamp buffer. This will lover the DAC output consequently off course. But the output dropped. I did not notice this when using the FP.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on March 07, 2018, 08:12:05 am
A good idea will be to see if we can use the latest FPGA image for older devices, I'm wondering what had happen with the 3.4.1 firmware version, did anybody encountered it again ?

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tek2232 on March 07, 2018, 09:13:52 am
Sure there are undoubtly many other, I am one of them. Great respect for those guys doing a lot of work!

Same here interesting  stuff !
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 07, 2018, 09:14:52 am
I think I will add another functionality that would be interesting for testing: the possibility to have a fixed output range. This will allow exploring the full output ranges at different frequencies, thus finding the best thresholds for switching the outputs.
This function will also be useful later on if you don't want relays switching during your tests.

I did at some point get annoyed when dialing up the frequency past 20MHz (I think 20 was the limit), and having the Vpp click down from 10Vpp to 5Vpp
It should not change the offset or amplitude just because you are changing frequency. Instead, refuse to set the new frequency.

On the other hand, if you want to go up to 30Mhz, and it is not letting you, it would be nice if it indicated why not. Maybe by flashing the amplitude inverted red every time you try to tick past 20MHz. Same if you try and up the amplitude and it will not let you: flash inverted red the frequency or limits.

This is not exactly what you asked about of course, but related and I was reminded of it.
As to locking the relays/range:

I noted that when you change frequency, the FPGA does that seamlessly. Not a single sample missed in the signal train, it even stays in phase, just at a higher frequency.
Except when it also changes range, then you loose signal for a few ms while it ticks over.  So I can see a locked relay being useful sometimes.



A good idea will be to see if we can use the latest FPGA image for older devices, I'm wondering what had happen with the 3.4.1 firmware version, did anybody encountered it again ?


I think you mean 3.2.1. That was reported once, but I do not remember a 3.4.1
Its easy to experiment with that. We can flash the Winbond all we want. But no-one ever published 3.2

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 07, 2018, 09:28:46 am
We can flash the Winbond all we want. But no-one ever published 3.2

fremen67 did https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=389282 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=389282)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: zov on March 07, 2018, 09:39:13 am
DerKammi, IIRC it's you who decrypted SB PCB layout and made its circuit diagram. If it don't burden you very much can you trace and depict the following pins of FPGA: MSEL0-3 and all JTAG related TCK, TMS, TDI, TDO. Are they hardwired to PWR/GND , left floating or pull-up/pull-down with resistors? It is crucial for developing/debugging FPGA config.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 07, 2018, 09:49:31 am
I'll beep them out this evening. No problem

I'm very much agreeing with Cybermaus on the voltage level switching when upping the frequency, major annoyance. This is something we can address luckily.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on March 07, 2018, 04:56:54 pm
Hey guys, I haven't been able to contribute much, but today maybe that can change.

I was successfully able to get my supplier from eBay to mail me a replacement version 3.2 chip for my working version 3.1 unit. That means that we have a currently functioning 3.1 chip available that we can test and monitor until it fails. Do yall think that this would be helpful in our attempts to fix the firmware problems in 3.1?

I am willing to send this chip anywhere in the world at my own expense if it would help in this effort, once I have received the replacement chip and have verified that it is working and of the correct version.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 07, 2018, 07:42:19 pm
DerKammi, IIRC it's you who decrypted SB PCB layout and made its circuit diagram. If it don't burden you very much can you trace and depict the following pins of FPGA: MSEL0-3 and all JTAG related TCK, TMS, TDI, TDO. Are they hardwired to PWR/GND , left floating or pull-up/pull-down with resistors? It is crucial for developing/debugging FPGA config.

MSEL0 - GND
MSEL1 - 2V5
MSEL2 - GND
All hard tied.

TCK, TMS, TDI and TDO are not connected to anything.

I hope this is good news  :-\
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 07, 2018, 08:31:23 pm
Also made a flash dump of both units. For a large part they are the same but there is a difference. Also compared to the file from Fremen there is a difference. Both at the same address.

Bit to tired now for a deep dive but for the ones just waking up... Knock your self out.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 07, 2018, 09:06:21 pm
cybermaus noticed random values when launching PC Software, see here https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1444331/#msg1444331 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1444331/#msg1444331)

Just tested several times, I always get the right values. Only when generator is offline results are strange, see pic.
Thank you. When there is no communication, you see the screen as it is in dev mode.  Everything is OK then.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 07, 2018, 09:12:40 pm
Even though I don't know enough to contribute to the software/firmware side of the FY6600, I am following this with great interest. Keep up the good work, I'm sure there are many others watching your progress.
Sure there are undoubtly many other, I am one of them. Great respect for those guys doing a lot of work!
Sure there are undoubtly many other, I am one of them. Great respect for those guys doing a lot of work!

Same here interesting  stuff !

Thank you for your support. Very much appreciated. Always funny to see what a small group can do when motivated...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 07, 2018, 09:28:58 pm
fremen, do you know whether there is calibration info send out to the FPGA?
No. None that I saw appart from calibration data that are sent when starting up.

Depending on the output range, the scaling formula is different (see the excel sheet I posted some time ago) but that's all.
This is the next step we will have to work on. We will have to characterize the outputs to find flat parts on each range, then choose thresholds and add calibration data for each output and channel. For that I will release a FW version where we will be able to choose and lock an output range. We will also have to find the best limits for each wave (max frequency) and also max output depending on frequency. After that I will be able to add calibration data in a new firmware. If it's only 2 points by range then this will be easy to do. I will add this in a system tab in the PC Software.

Yesterday during testing I saw the PP voltage of a sine drop when I went over 5V, thus switching to the opamp buffer. This will lover the DAC output consequently off course. But the output dropped. I did not notice this when using the FP.
At the moment I programmed the same thresholds and used the same scaling factors than the one used in the original FG. The difference in output when changing range is logical as there are not hardware calibration possibility for all the ranges.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 07, 2018, 10:02:29 pm
I did at some point get annoyed when dialing up the frequency past 20MHz (I think 20 was the limit), and having the Vpp click down from 10Vpp to 5Vpp
It should not change the offset or amplitude just because you are changing frequency. Instead, refuse to set the new frequency.
Yes I understand that this could be annoying at some point but it's the way it is done in several FG I have (Siglent, Hantek, even Feeltech...). This is the "Frequency priority" function and seems to be a standard way to do. When starting the FG you could also be annoyed that you first have to change your voltage to be able to select a frequency...
Anyway, it's not a big deal to add a configuration switch that inhibate this functionnality if you find it annoying. I will do it.

On the other hand, if you want to go up to 30Mhz, and it is not letting you, it would be nice if it indicated why not. Maybe by flashing the amplitude inverted red every time you try to tick past 20MHz. Same if you try and up the amplitude and it will not let you: flash inverted red the frequency or limits.
Yes this would be a nice way. I could also add it to the PC Software but it's a matter of time and priority. I will see where I can place it in my Doto list which goes on growing  :)
As I explain some time ago, I used the Feeltech Software as a front end because it was already there plus Feeltech made the source code available. So that was the quickest way to go with the possibility to change things, should it be necessary.
The fact is that I had to change things in this software much earlier than I had expected. Actually this PC software has been developped with Visual Basic 6.0. A 20 years old IDE, more than obsolete for a long time now. So this is clearly not the best choice for an application that is suppose to grow.
I know that all the functions I add in the firmware, even if it's in the BP now, wil be usable later on with the onboard LCD.
Not sure about what will happen with the functions that I add in the PC Software now. There are things that I also want to add like Frequency/Period switch, Amplitude&Offset/Voltage High&Voltage-low switch, mHz/Hz/kHz/Mhz choice, .... but all of this is time and this may be wasted work/energy as long as we don't know what will be the final PC front-end..

This is not exactly what you asked about of course, but related and I was reminded of it.
No problem. This is the exact right place to discuss those things  :)

As to locking the relays/range:

I noted that when you change frequency, the FPGA does that seamlessly. Not a single sample missed in the signal train, it even stays in phase, just at a higher frequency.
Except when it also changes range, then you loose signal for a few ms while it ticks over.  So I can see a locked relay being useful sometimes.
Yes that was exactly the point.
In the original FG firmware, you will notice that feeltech added a 4ms slot time with no signal when switching ranges. This a bit overkill so at the moment I just change range and send the new scale value at the same time...does not seem to be that bad but it's a point that may be improved in the future. Tests will tell...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 07, 2018, 10:19:11 pm
Hey guys, I haven't been able to contribute much, but today maybe that can change.

I was successfully able to get my supplier from eBay to mail me a replacement version 3.2 chip for my working version 3.1 unit. That means that we have a currently functioning 3.1 chip available that we can test and monitor until it fails. Do yall think that this would be helpful in our attempts to fix the firmware problems in 3.1?

I am willing to send this chip anywhere in the world at my own expense if it would help in this effort, once I have received the replacement chip and have verified that it is working and of the correct version.
Hey SMB784, Thank you for the proposal. That might become handy.
I have 2 FY6600 at the moment for tests, a 15Mhz and a 60Mhz version. I am willing to flash the 15Mhz with the new firmware as the idea is that this FY will turn into a dev model.
As you may have read, the CPU is protected and I will have to erase it. So I will then only have one official model that I will keep for test and reference. If something happen to this model, I will be clearly annoyed. I was thinking of replacing the CPU of the 15Mhz version with an empty one and keeping the official as a spare but if I can have an original spare without loosing time with desoldering/resoldering the CPU that would be nice...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 07, 2018, 10:25:15 pm
A good idea will be to see if we can use the latest FPGA image for older devices, I'm wondering what had happen with the 3.4.1 firmware version, did anybody encountered it again ?

 Cheers,
 DC1MC
Yes, I think this would be logical at some point to use the new FW with the latest FPGA version. Maybe not during the BP transition but later on when flashing the FP. Plus it will be easy to update. It might even be updated via a PC front end via the FP (with some risks though).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on March 07, 2018, 11:52:11 pm
That sounds like good news for owners of version 3.1 SMB784, its the first real acknowledgement we've had ,either from the supplier or the manufacturer that there was an issue with 3.1 . Is it a new front panel stm32 ic they are sending you ?

I finally went ahead and fitted the IEC connector , a mains Rf filter at the input separate from the psu board ,a grounded the metal screen between the psu and signal board and hooked  the power supply ground back to mains earth .
I had a chance to try it out over at a friends place today ,from a cold switch on the frequency was bang on to 6 digits throughout the range ,better than I thought it would be.

Im still not 100% happy with the interaction between the 5 volt and +/- 12 volts rails under load, so Im on the lookout for a small  5 volt supply .

Can anyone hazard a guess as to why Feeltech made the attenuation kick in at higher frequencies ,doesnt make much sense really ,and a way to get rid of it would be great .
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on March 08, 2018, 02:47:00 am
Hey SMB784, Thank you for the proposal. That might become handy.
I have 2 FY6600 at the moment for tests, a 15Mhz and a 60Mhz version. I am willing to flash the 15Mhz with the new firmware as the idea is that this FY will turn into a dev model.
As you may have read, the CPU is protected and I will have to erase it. So I will then only have one official model that I will keep for test and reference. If something happen to this model, I will be clearly annoyed. I was thinking of replacing the CPU of the 15Mhz version with an empty one and keeping the official as a spare but if I can have an original spare without loosing time with desoldering/resoldering the CPU that would be nice...

I would happily send the chip to you, but I would very much like it to be used to figure out what the mode of failure is for version 3.1.  would that be possible, in your opinion?

That sounds like good news for owners of version 3.1 SMB784, its the first real acknowledgement we've had ,either from the supplier or the manufacturer that there was an issue with 3.1 . Is it a new front panel stm32 ic they are sending you?

I actually have no idea what it is they are sending me, but we will find out when it arrives!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 08, 2018, 06:47:44 am
Well. V3.1 is not actually failing in any critical manner. It is V3.0 that is.

There is a rare report of losing the sine on 3.1, but that is fixable from the PC software, and only 2 people ever reported it.
On v3.0 however we have a half dozen people with completely unusable and un-fixable firmware.


It is very interesting to know how/where you got this promise for a new chip. That half dozen people may be interested to know. You'd still need some pretty good 0.5mm pitch chip de-soldering skills, but if the device is already broken there is little to loose.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scratch.HTF on March 08, 2018, 12:15:17 pm
With regard to the fixed sampling clock for each DAC, there are two general purpose PLLs in the Altera EP4CE6 as used in the FY6600 (each DAC can have an independent PLL clock source in theory); for more information read Clock Networks and PLLs in Cyclone IV Devices at https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/hb/cyclone-iv/cyiv-51005.pdf (https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/hb/cyclone-iv/cyiv-51005.pdf)
The PLL VCO in the EP4CE6 operates from 600 MHz to 1300 MHz which requires an input clock of 5-362 MHz (sourced from the 50 MHz timebase oscillator) as per the C8 suffix device used in the FY6600 and additional PLL specifications can be found at https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/hb/cyclone-iv/cyiv-53001.pdf (https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/hb/cyclone-iv/cyiv-53001.pdf)
Within the PLL VCO range, 1250 MHz / 2 = 625 MHz which means we have a frequency block which can be divided by 2 which results in contiguous blocks e.g. 625-1250/125-250/62.5-125 etc.
All counters in the PLL chain are 16-bit and can be individually bypassed.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 09, 2018, 04:32:50 pm
Another 3.2 tester here happy to report that everything appears to be working well under Blue Pill control (once I'd remembered to plug the USB lead into the SG, anyway  :palm:).

Thanks, fremen.  Standing by for future releases.

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 09, 2018, 10:32:14 pm
Residual FM or short-term jitter of FY6600.

Here is a comparison of short term jitter for three signal generators. Nominal frequency is 10.1398 MHz with each SG offset in frequency a small amount. Shown in the image is a spectrum waterfall (horizontal axis is frequency) with about 2 FFTs per second. Left trace is Marconi 20222D, center is FY6600 and right is cheap ($20) DDS AD9851. Jitter of FY6600 is estimated to be 5 to 6 Hz.

The large jitter in the FY6600 would seem to rule it out for use as a local oscillator in radio projects. Too bad, since many nice applications are based on small FM deviations such as WSPR with 1.46 Hz per symbol. 

Tried the FM modulation function of FY6600 with WSPR symbols programmed in Arbitrary waveform for CH2. It worked sometimes but message was lost most of the time.

Am I correct in assuming that the jitter problem for the FY6600 cannot be resolved?

FY6600 used for the test is new, never opened unit with FW version 3.2.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: doobs on March 10, 2018, 04:43:41 am
Hi,
I bought one of these recently. Up around 60MHz I've been having a bit of trouble getting a reliable external sync out of it. The pulses seem to vary in shape and magnitude like a distorted rectified sine wave.
Makes it a bit problematic trying to get a reliable trigger on me scope.

Doug
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 10, 2018, 06:59:03 am
Which output are you referring to? Front panel output could benefit from different op-amps if really needed.

Back output won't be able to keep up with that high frequency due to a 74HC245 buffer which runs at typical 55 MHz max. so 60 is maxing it out pretty much.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 10, 2018, 07:18:01 am
Here is a comparison of short term jitter for three signal generators.
...
Am I correct in assuming that the jitter problem for the FY6600 cannot be resolved?

Wow, that looks pretty bad. What do you mean by "short term"? How much time does this waterfall cover?
One source of jitter that can be easily fixed is the 50MHz XO. Replace it with a better 50MHz TCXO or even a OXCO.

The other big source of known jitter is the mapping of the wave on the 250MHz DAC resolution, but I am not sure if that applies here, because you are doing sine waves?
What do you mean by "WSPR symbols programmed in Arbitrary waveform"? So you are not using sine?
Out of interest, could you produce the same waterfall on a 10.0000000MHz signal. That would eliminate the 250MHz, so we can see if indeed that does not apply here.


A third possible problem with your use case is that the FM modulation is done not by the FPGA, but by the STM32 CPU quickly and repeatedly telling the FPGA to change frequencies. So you would start getting problems with the CPU speed, the SPI bus speed, as well as the CPU jumping off to serve various interrupt routines.
But again, you seem to hint that you code your own FM into arb waves?



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 10, 2018, 02:56:52 pm
WSPR is a narrow bandwidth FSK mode used in amateur radio which requires a very stable clock, usually a GPSDO.  It was designed to allow measuring propagation over long distances with very low power. A search will turn up lots of information.  For WSPR to work properly the clock has to run at certain frequencies that allow creating the correct tone spacing.  There's a good explanation of the problem on the QRP-Labs website.

I think this is something Zov can fix when he gets back from vacation if there is enough unused real estate in the FPGA to add a PLL to generate the proper clock rates or by modifying the existing clock.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 10, 2018, 04:23:12 pm
Re: FY6600-M60 jitter.

All three signal generators were set to sine wave without any modulation and were used simultaneously. Plot used 2 FFTs per sec or about 20 to 30  seconds. Don't remember exactly.

Yes, the jitter is pretty bad for the FY6600, about 5 to 6 Hz residual FM. I have repeated the test after frequency calibration and sine wave repair. Got exactly the same result.

I mentioned WSPR protocol since it uses 1.46 Hz per symbol for FM. There are 162 symbols in a message with each symbol having 0, 1, 2, or 3. The message is easy to program in an ARB waveform on FY6600. Then I used the ARB waveform on CH2  to FM modulate the sine wave on CH1. In spite of the bad FM jitter observed from above test, decided to try it anyway.  To my amazement it worked... once in a while ...but most of the time the message was not decoded. I attribute the fact that it was decoded at all as due to the robust WSPR protocol which uses forward error correction.

Anyway, I am very discouraged since I had hopes of using this SG for some radio experiments. None-the-less there are some features, like the variable phase output and dual outputs that will prove useful for some work.  My further reading on the subject seems to indicate that jitter is due to the way the DDS plays back an arbitrary waveform. Hopefully someone here can address this jitter problem, if it at all possible.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on March 10, 2018, 09:57:56 pm
Re: FY6600-M60 jitter.
Hopefully someone here can address this jitter problem, if it at all possible.


My opinion is that there will be no simple fix for the jitter problem, because it is inherent to the FY6600 electronic design.
Some of us described how the CycloneIV works with its internal PLL, and how the limits are reached.

The output signal, without any modulation applied (square or sine, it doesn't matter) is jitter free at specific frequencies like 1M, 2M...
I made some tests around 1MHz, there is no jitter at 1M, nor at 1.008375 MHz, 1.016065 MHz and so on. A bit Strange for me
BTW, in your case, to produce a very thin FSQ modulation, you need a carrier as stable as possible(smooth PLL feedback design).
The FY6600 is clearly not designed to provide FSQ modulation as sharp as you mentioned in your last post imho.

Regards
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 11, 2018, 03:03:06 am
Residual FM or short-term jitter of FY6600.

Here is a comparison of short term jitter for three signal generators. Nominal frequency is 10.1398 MHz with each SG offset in frequency a small amount. Shown in the image is a spectrum waterfall (horizontal axis is frequency) with about 2 FFTs per second. Left trace is Marconi 20222D, center is FY6600 and right is cheap ($20) DDS AD9851. Jitter of FY6600 is estimated to be 5 to 6 Hz.

The large jitter in the FY6600 would seem to rule it out for use as a local oscillator in radio projects. Too bad, since many nice applications are based on small FM deviations such as WSPR with 1.46 Hz per symbol. 

Tried the FM modulation function of FY6600 with WSPR symbols programmed in Arbitrary waveform for CH2. It worked sometimes but message was lost most of the time.

Am I correct in assuming that the jitter problem for the FY6600 cannot be resolved?

FY6600 used for the test is new, never opened unit with FW version 3.2.

I ran the same test on my modified FY6600.  The oscillator has been swapped to a TCXO 1ppm unit.  see post https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1434962/#msg1434962. (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1434962/#msg1434962.)   Also my power supply has had the output capacitors replaced with Rubicon low ESR types.  A 100nF X7R ceramic capacitor was added on the bottom of the board on each of the three rails.   These PS mods, plus a lossy ferrite on the power jumper does a lot to get rid of the nasty switching spike on the DC power supplies. 

The data shown below was taken on my SA at 3Hz RBW.   I can see no significant short-term jitter in the signal on the SA or on my Frequency counter.   Frequency drift over several hours was previously observed at ~0.3ppm (10.0MHz). 

The oscillator only costs $11 from Digikey and is relatively easy to install.  Well worth it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 11, 2018, 11:32:25 pm
Problem connecting to the site from France today   :(

Here is a new Version of PC Software and Firmware for BP (v0.4).
I added a configuration tab where you can activate the Over-Voltage protection and choose the range mode from Automatic / Low Range / Mid Range / High Range. This will allow to study the frequency response for each range.
I also removed for now the amplitude limitation to 5V after 20 Mhz.

The idea now is to gather information to:
- allow the best software calibration of Offset and Amplitude in the 3 ranges
- Find the best thresholds for switching ranges (now +/- 0.25V and +/- 2.5V) depending on waves... or not...
- Find the best thresholds for switching ranges for DC (works with Offset) if different from above
- Find the best frequency limits for each wave type
- Find whatever could be usefull ...

I will program what you think is the best configuration. Up to you!  ;)

I was also thinking about adding a 50 Ohms mode (at least for mid and high range as low range is not 50 ohms). Or maybe a user defined load if you think it is usefull...

While waiting for feedbacks, I will work on configurations Back-up & Restore
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 12, 2018, 07:15:21 am
Yeah, it was down all sunday.

I was also thinking about adding a 50 Ohms mode (at least for mid and high range as low range is not 50 ohms). Or maybe a user defined load if you think it is useful...
Explain please. Is it not always already on a 50 Ohm mode?
Would you mod the board for other values?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 12, 2018, 07:42:05 am
Explain please. Is it not always already on a 50 Ohm mode?

When output attenuator (100R/510R/100R)  is in use output impedance is around 85 ohm.
Better attenuator? http://www.leleivre.com/rf_pipad.html (http://www.leleivre.com/rf_pipad.html)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 12, 2018, 08:19:56 am
Ok, but it is still in 50 ohm "mode" even if the value is a little (lot) off.
Or maybe a better description would be "low-Z" mode.

Point however is, Fremen67 is doing software, and talks about "adding a mode".
But this would more be modding the hardware to correct the 85 Ohm, but still not something to add in software.
So I'd still wonder what he meant exactly.


Edit: Also, why would they have made that 85 Ohm?
Surely they could have selected other values, 58+322 (or 56 + (270+390)) would have yielded the same attenuation with a much better matched 50 Ohm
So maybe there is a reason for 85 Ohm?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 12, 2018, 09:21:59 am
Point however is, Fremen67 is doing software, and talks about "adding a mode".
So I'd still wonder what he meant exactly.

He probably means that the amplitude is correct to 50 ohm load, hi-z/low-z (50 ohm) selection.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 12, 2018, 01:09:06 pm
I was also thinking about adding a 50 Ohms mode (at least for mid and high range as low range is not 50 ohms). Or maybe a user defined load if you think it is useful...
Explain please. Is it not always already on a 50 Ohm mode?
Would you mod the board for other values?
« 50 Ohms » and « Hi-Z » output load selection are quite common on function generators.
This selection allows displaying on the FG the voltage that is actually on the output.

Some function generators which have 50 ohms ouput impedance need to have an external 50 ohm on the output to display the correct output voltage. If you don’t, you then have twice the output on a Hi-Z load than what you are supposed to have (which you usually don’t want).
https://www.keysight.com/main/editorial.jspx?ckey=1948055&id=1948055&nid=-11143.0.00&lc=eng&cc=MY (https://www.keysight.com/main/editorial.jspx?ckey=1948055&id=1948055&nid=-11143.0.00&lc=eng&cc=MY)

In our case, the FY6600 has a 50 ohms output impedance on 2 channels but the correct output values are displayed for a Hi-Z load.
If you want to match the impedances to avoid ringing on high frequencies, you are supposed to add 50 ohms near you DUT. In that case, the DUT will only receive a signal with half the voltage it is supposed to. The “50 ohms” or “Hi-Z” mode is only a way to show on the display the actual voltage your DUT is receiving depending on its impedance.
In some other cases, your DUT input impedance could be 75 ohms or something different. In that case you might want to configure it on the FG to display the correct values…

The ouput impedance mode I was talking about is just a way for the FG to know the actual ouput parameters to do the correct maths on output values.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 12, 2018, 01:30:24 pm
Yes, with that last remark of Kaku the penny dropped, thanks.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 12, 2018, 03:50:10 pm
Re: FY6600 Jitter

Insatman... Excellent results!!!  Would you do a simple FM modulation test?
Set CH1 to sine wave with freq as before, 10.1398 MHz.
Set CH2 to Square wave with freq 0.25 Hz. (Don't worry about Ampl and Offset as they are not used for internal FM).
Set modulation source to FM from CH2. Use BIAS 00'000'.001'500'000KHz. This will be set modulation depth to 1.5 Hz.
Your SA FFT waterfall should show the 1.5 Hz square wave modulation of the sine wave.

I'm considering your FY6600 modifications. My smd skills are poor. Probably can make the Power Supply mods. But removing the smd oscillator seems beyond me at the moment. If I can get it removed was thinking of tack soldering wires to the new osc module and tacking these wires to PCB. Any comments?


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 12, 2018, 07:00:30 pm
Set CH1 to sine wave with freq as before, 10.1398 MHz.
Set CH2 to Square wave with freq 0.25 Hz. (Don't worry about Ampl and Offset as they are not used for internal FM).
Set modulation source to FM from CH2. Use BIAS 00'000'.001'500'000KHz. This will be set modulation depth to 1.5 Hz.
For comparison, here is the unmodified FY6600 results in your settings.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 12, 2018, 08:02:52 pm
Re: FY6600 jitter

Thank you Kaku for the wonderful plots! This shows that an unmodified FY6600 is capable of FM down to below 1 Hz.

Unfortunately my brand new FY6600-M60 V3.2 does not have anywhere close to this good performance. See my post #998.

The great mystery now is; what could be causing the FM jitter of 6 Hz and sometimes much more, that I am observing?
I have not opened the enclosure yet or made any modifications. Vendor is close, so maybe it can be returned for another unit.

Could it be a problem with the power supply or some parts not properly soldered? Anyone seen similar jitter?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 13, 2018, 12:55:40 am
The display is a ILI9341 for 99% sure. The pinout is the classic 18 pin for this type op display. Link for similar display (https://www.solidrop.net/product/free-ship-5pc-lot-2-4inch-spi-tft-lcd-screen-18pin-240-320-color-lcd-drive-ic-ili9341-4io-only-for-stm32-mcu-raspberry-pi.html)
Yes it is  :)
SPI1 runs at 18Mhz
Here is the LCD startup sequence, first line value beeing the command register, the other values the parameters:
Code: [Select]
CF 00 81 30
ED 64 03 12 81
E8 85 10 78
CB 39 2C 00 34 02
F7 20
EA 00 00
B1 00 18
B6 0A A2
C0 21
C1 11
C5 3E 31
C7 AA
36 A8
F2 00
26 01
3A 55
E0 0F 26 24 0B 0E 09 54 A8 46 0C 17 09 0F 07 00
E1 00 19 1B 04 10 07 2A 47 39 03 06 06 30 38 0F
2A 00 00 00 EF
2B 00 00 01 3F
11
29

ILI9341 for 100% sure  :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 13, 2018, 06:25:36 am
Great to see that it runs at 18MHz, the max of the F103 chip. That makes up for a speedy display in DMA mode. I'm playing with a F401 nucleo board with a ILI9341 display this week.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 13, 2018, 07:36:36 am
I'm playing with a F401 nucleo board with a ILI9341 display this week.
Nice board . Will you also have time to do some  "homework" on the calibration thing?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 13, 2018, 07:50:23 am
2 evenings at least. Do you have some wishes in the format you need, a protocol as such?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 13, 2018, 08:22:10 am
I had some fun time with a precision impedance analyzer at work today and made some DC-bias curves of the bigger SMD capacitors around the opamps and DAC

Feeltech used some common type caps on these place. As expected.

C53..57 18µF nom >> 12V 2µ7 15% left  :-[
C24..25 6µ8 nom >> 5V 4µ3 63% left

I put a wrong marker at the DAC caps, should have used 3v3 and not 5v but these caps have enough derating left for them to be useful. @3v3 there is roughly 5µ2 left.

But the 18µF ones around the opamps are pretty useless for their size. So there is another upgrade option in place for them. Some proper X7R ones with a lot less derating at higher voltage should help nicely.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 13, 2018, 09:36:48 am
2 evenings at least. Do you have some wishes in the format you need, a protocol as such?
Perfect!
For the format, as long as it is in an Excel like format it will be fine.
For the protocol, the only special thing I can think of is to do tests with and without 50 Ohms load, and at least Vpp for Sine, Square and Ramp waves (and maybe others that you might think interesting) on the 3 ranges + DC
For the rest I am sure you will have other ideas when you see special things during tests execution.

The idea would be that your protocol could be used as a basis for others so that we could have some statistical data.
I will also run your protocol on my 2 FGs. If others can also help and run your protocol, that would help also (cybermaus, DC1MC, DaveR, Kaku, ... any volonteer, depending on your free time,  you help will be very much appreciated :))
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 13, 2018, 11:29:34 am
Not sure I have the correct equipment for this. I have no good SA to see dB levels or harmonics
But I surely do not want to ignore this request, I can only guess at how much time you are spending.

Something like this XLS?
Or would you rather have some other X/Y axis values?
I'll use your suggestions, work out the other ranges, and then attach the XLS itself for others to use.

Note:
- voltage levels read from scope
- dB levels calculated
- yellow means visual distortion on sine wave, red means crappy sine wave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 13, 2018, 01:47:23 pm
Capture the longest DSO traces at 1 GS/S that you can in an ASCII format.  I'll write spectral analysis routines for Octave/MATLAB. I know how to get *many* more bits of precision out of long signals than even a good SA offers.

The traces will be too long to post. Post a short sample so I can get the read correct and install Octave on your system.  I'll post the Octave code so that anyone can do the analysis.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 13, 2018, 02:50:12 pm
If others can also help and run your protocol, that would help also (cybermaus, DC1MC, DaveR, Kaku, ... any volonteer, depending on your free time,  you help will be very much appreciated :))

I'm a bit limited at the moment, as my ST-Link dongle died yesterday after only about six uses.  I've ordered another four from China in the hope that I might get a decent one amongst them, but I probably won't have them for at least ten days.

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 13, 2018, 03:59:52 pm
Capture the longest DSO traces at 1 GS/S that you can in an ASCII format.  I'll write spectral analysis routines for Octave/MATLAB. I know how to get *many* more bits of precision out of long signals than even a good SA offers.

The traces will be too long to post. Post a short sample so I can get the read correct and install Octave on your system.  I'll post the Octave code so that anyone can do the analysis.

Thanks. But that sounds like too many bits of precision. Maybe a bit overkill when all we want to do is determine which "auto" range selection to use?
I have to leave now, but I will at later try to get at least one sample for you, just to see how it works.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 13, 2018, 08:25:42 pm
Not sure I have the correct equipment for this. I have no good SA to see dB levels or harmonics
But I surely do not want to ignore this request, I can only guess at how much time you are spending.

Something like this XLS?
Or would you rather have some other X/Y axis values?
I'll use your suggestions, work out the other ranges, and then attach the XLS itself for others to use.

Note:
- voltage levels read from scope
- dB levels calculated
- yellow means visual distortion on sine wave, red means crappy sine wave
Yes exactly something like this. Thank you!

For this particular Sine example, I was thinking of creating a compensation gain, depending on the frequency, that would flatten the response in the high frequency zone up to 60Mhz... that is  if we are able to find a generic relation (We may need some more samples in the falling part of the curve).
For arbitrary waves, it seems harder to find some compensation trick that would work for every type of signal.

As for static calibration (Offset and Amplitude) that should be easier. For the Offset response, the DC wave will be handy with a DMM. For amplitude a very slow square wave (like 10  0.1 Herz) should be fine so that we could also use a DMM, unless there is something easier I don't see. Once we have the values, we will find out the best parts of the range to use.

Edit: slow wave is obviously not 10 Hz but 0.1 Hz so that you can have time to read values on DMM  :P
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 13, 2018, 08:30:01 pm
I'm a bit limited at the moment, as my ST-Link dongle died yesterday after only about six uses.  I've ordered another four from China in the hope that I might get a decent one amongst them, but I probably won't have them for at least ten days.

Dave

No worries. There will still be things to do in 10 days  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 14, 2018, 12:18:07 am
At 1 GS/S Nyquist is 500 MHz, and the FFT coefficients are at 100 Hz increments with 10 Mpts.  With a sample rate of 250 MS/S the samples are at 25 Hz increments.  So simple averaging will get a few bits at the cost of a little bit of resolution.

The way to flatten the spectrum is to have a digital filter in the FPGA and pipe the output through that.  That will take care of everything.  The filter approximates the corrections at each sine wave frequency, so once you have the table of gain corrections for the sine wave it's just a matter of designing a filter with that response curve.  I think measurements every 5 MHz should do for a start.  I can fit a filter to that and we'll see how accurate it is by measuring the midpoint frequencies.

I've been following progress, but kept quite because I was not in a position to contribute having borked my cable.  But we're now at the DSP stage and that's something I can do easily. The shift to matching MATLAB exactly has made a lot of what I'm used to invalid, but it's not a huge amount of extra trouble.

I'm just about to embark on learning Vivado and Verilog for the Zynq,  so I can't do the FPGA part.  But I can do the math.  This is real time as opposed to the recorded time we deal with in seismic processing.  But I know what the differences are so it shouldn't be to much work to get up to speed on doing it for real time.  And Zov knows how to convert that to the Altera.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 14, 2018, 07:47:08 pm
This is a lot of work, and I had a lot of distraction today (my boss/colleagues/clients kept bothering me)

Attached the XLS with -10~+10 hard range and both High-Z and 50 Ohm.

A few notes:

- At 50 Ohm above 10V, the OpAmp is just not cutting it. Rather then trying to correct this (it will not be able to anyway) this needs to be corrected by a better OpAmp and maybe 15V rails in stead of a 12V rails that is to weak as well. Or at the very least a 12V rail with more power.

- Around 10V - 60Hz there is a weird additional negative offset. It also attenuates more, but I think both are caused by the OpAmp cutting of the high crest of the sine more then the low crest of the sine.

- Likely bad sine to the right and bottom is caused by the OpAmp attenuating, toward the left by a weak DAC signal, amplified noise and DAC resolution.



To be honest, Fremen67, I will provide you with the info requested to my best ability, but I wonder if level correction should not be a lower priority. Sweep/Mod/Counter/LCD may be more rewarding features. Will work on 0.275 range next.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 14, 2018, 08:19:51 pm
And for some reason it won't generate wave forms this evening >:( Flashed the 0.3 and 0.4 and it will connect fine. But no output.  :'(

Was going to fill out Cybermaus his excel to see some diffs maybe. But it is not happening yet  :'( :'( :'(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 14, 2018, 09:35:57 pm
Small intermediate result:

The 5.5Vpp in a hard 2.75V range gives such a perfect 6Vpp that I am wondering if you have a coding error in the software.

Also: apparently  the 2.75 range is able to go up to 3V
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 14, 2018, 11:05:54 pm
This is a lot of work, and I had a lot of distraction today (my boss/colleagues/clients kept bothering me)

Attached the XLS with -10~+10 hard range and both High-Z and 50 Ohm.

A few notes:

- At 50 Ohm above 10V, the OpAmp is just not cutting it. Rather then trying to correct this (it will not be able to anyway) this needs to be corrected by a better OpAmp and maybe 15V rails in stead of a 12V rails that is to weak as well. Or at the very least a 12V rail with more power.

- Around 10V - 60Hz there is a weird additional negative offset. It also attenuates more, but I think both are caused by the OpAmp cutting of the high crest of the sine more then the low crest of the sine.

- Likely bad sine to the right and bottom is caused by the OpAmp attenuating, toward the left by a weak DAC signal, amplified noise and DAC resolution.
Perfect  :-+
A lot of work indeed but essential as we need to analyze what can be done by software and what cannot be. And it will also be the reference for future hardware modifications.
With those results, it already seems obvious that some OpAmp upgrade will be a must. A more powerfull power supply could also be usefull.

To be honest, Fremen67, I will provide you with the info requested to my best ability, but I wonder if level correction should not be a lower priority. Sweep/Mod/Counter/LCD may be more rewarding features. Will work on 0.275 range next.
That is exactly why it is important to have data and think before doing any useless things.
At least static calibration can be done without much effort. A digital filter in the FPGA might be the real solution for bandwith upgrade.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 14, 2018, 11:08:21 pm
And for some reason it won't generate wave forms this evening >:( Flashed the 0.3 and 0.4 and it will connect fine. But no output.  :'(

Was going to fill out Cybermaus his excel to see some diffs maybe. But it is not happening yet  :'( :'( :'(
Lot of chances that it is a wiring problem. I also wasted 1 hour last week because I swapped 2 wires when switching configuration...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 14, 2018, 11:23:34 pm
Small intermediate result:

The 5.5Vpp in a hard 2.75V range gives such a perfect 6Vpp that I am wondering if you have a coding error in the software.

Also: apparently  the 2.75 range is able to go up to 3V
I have a perfect 6.12V on mine for 5.5V  ;)
I think it is now obvious why feeltech did not use the full range. A mistake is always possible but the formula is the same for the whole range... At least you should have the same results with the original firmware in the -2.5V/+2.5V range. In fact based on the formula, it should even go up to 2.778V  for full range (4095 points)
Results should be very similar between the Low and Medium range as there is only a voltage divider to go from one to the other
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 14, 2018, 11:30:53 pm
Ok, uploaded new XLS above, calling it a day.
Also changed the color formulas a bit, if you are using this template.

My intermediate conclusions:

- If you want above 10Vpp with 50 Ohm load, you must hardware mod OpAmp and PSU (at any frequency) (or maybe a cap close to the OpAmp)
- the factory 20MHz drop out of high range seems justified (for autorange)
- the factory switch to low range below 0.5V and to high range above 5V seems justified (for autorange)
- any optional 50 Ohm readout mode should double voltages on native and high range, but 2.65x in low range, due to bad attenuator values.

Edit: Additional thoughts:
- A 75 Ohm readout mode seems tempting, but may falsely lead people to think it can be set to 75 Ohm output impedance.
- Also a true 75 Ohm impedance is easy to make. Just add a 25 (22) Ohm series resistor at the BNC, its close enough to to 50 Ohm resistor to not have relevant reflections.
- Thinking about 75 Ohm I suddenly realize this device is missing a build-in TV (PAL-NTSC) waveform. Not that I need it, but for nostalgia reasons.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 15, 2018, 04:34:21 am
Re: FY6600 Jitter

Insatman... Excellent results!!!  Would you do a simple FM modulation test?
Set CH1 to sine wave with freq as before, 10.1398 MHz.
Set CH2 to Square wave with freq 0.25 Hz. (Don't worry about Ampl and Offset as they are not used for internal FM).
Set modulation source to FM from CH2. Use BIAS 00'000'.001'500'000KHz. This will be set modulation depth to 1.5 Hz.
Your SA FFT waterfall should show the 1.5 Hz square wave modulation of the sine wave.

I'm considering your FY6600 modifications. My smd skills are poor. Probably can make the Power Supply mods. But removing the smd oscillator seems beyond me at the moment. If I can get it removed was thinking of tack soldering wires to the new osc module and tacking these wires to PCB. Any comments?


I did the test you requested with one change.  The CH2 squarewave frequency was reduced to .02 Hz.  This was necessary as the screen/waterfall update rate is about once every 2.5 to 3 seconds on my SA at the RBW of 3Hz.   Running at the faster frequency resulted in "fuzz" rather than the "notched" waterfall pattern.   Note that the spikes on the waterfall plot only occur at frequency transition times.  Also not the lack of average frequency drift on both plots as the measurement took several minutes at approx 2.8 seconds per measurement line.

This was the first time I used the VCO function on my FY6600, so it took me awhile to get it working.

I removed the smd oscillator easily with a hot-air gun.  This was after carefully masking surrounding components with two layers of Kapton tape.   Soldering the new oscillator was more difficult as my smd skills are not great, but I do have a microscope to work under.   As for attaching wires to remote the oscillator...yes this is possible for a short distance as the 50Mhz frequency does not tolerate much inductance.  Twist the wires if at all possible to minimize inductance.   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 15, 2018, 06:43:54 am
Back in business. It was the wiring, but not a fault in which goes where, but a faulty connector. Used a different one in the ribbon and all is well.

And for some reason it won't generate wave forms this evening >:( Flashed the 0.3 and 0.4 and it will connect fine. But no output.  :'(

Was going to fill out Cybermaus his excel to see some diffs maybe. But it is not happening yet  :'( :'( :'(
Lot of chances that it is a wiring problem. I also wasted 1 hour last week because I swapped 2 wires when switching configuration...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gandalf_Sr on March 15, 2018, 08:48:07 am
Which output are you referring to? Front panel output could benefit from different op-amps if really needed.

Back output won't be able to keep up with that high frequency due to a 74HC245 buffer which runs at typical 55 MHz max. so 60 is maxing it out pretty much.
I haven't read/followed the whole thread but was aware of the FY6600's existence, seems like you guys are kicking it into shape - good work :D

Depending on the voltage levels it needs to run at, there are several CMOS family alternatives to the 74HC245 buffer that would have much lower gate propagation times.

1. Is there a schematic available?
2. Who is the preferred vendor to buy an FY6600 from?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 15, 2018, 08:59:09 am
1. yes, please go back a couple of pages and/or search DerKammi's posts.
2. I think they are all equally bad/good. Pick one far away and cheap if you can wait, or local if you want it fast and without added customs tax.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 15, 2018, 09:07:37 am
Here you go...

Which output are you referring to? Front panel output could benefit from different op-amps if really needed.

Back output won't be able to keep up with that high frequency due to a 74HC245 buffer which runs at typical 55 MHz max. so 60 is maxing it out pretty much.
I haven't read/followed the whole thread but was aware of the FY6600's existence, seems like you guys are kicking it into shape - good work :D

Depending on the voltage levels it needs to run at, there are several CMOS family alternatives to the 74HC245 buffer that would have much lower gate propagation times.

1. Is there a schematic available?
2. Who is the preferred vendor to buy an FY6600 from?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 15, 2018, 05:35:51 pm
Thanks Insatman for all the information. Plots are very instructive. Glad to see that your plots are close to other ones from Kaku. This means that this SG should allow some precise work with narrow band FM. Excellent performance for such a low cost SG.

I'm leaning in the direction of making the modifications you describe. Now feel more confident in replacing the original 50 MHz oscillator. Checked and found the TCXO Model D75J in stock at DigiKey. Thanks for all the tips. :)

Right now I am contacting the vendor of my FY6600 M60, FW 3.2 to see if it can be exchanged. The residual FM with my unit is too much for my work. They now have the FW 3.2.1 version in stock. I'm wondering if they upgraded the oscillator. I noticed earlier in this long thread (photos by DerKammi) that two units had different 50 MHz oscillator chips. Kaku's unmodified unit did not have the jitter problem. Maybe I have the poor quality chip in my unit. :(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 15, 2018, 06:09:13 pm
My FY6600 died  :-BROKE. Works yesterday, but today will not start, hangs up at startup at "Feeltech logo", nothing more. I also tested with BP, same result, not work. I'm trying to figure out the problem later.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 15, 2018, 06:16:52 pm
Not sure if it will help you but:

Hanging with the logo displayed means the STM32 CPU is not getting (correct) responses from the FPGA.
For example if you disable FPGA because you are programming Winbond, this is shown. Also some people have reported stuck logo because the cable came loose during transport.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Kaku on March 15, 2018, 06:29:28 pm
Not sure if it will help you but:

Hanging with the logo displayed means the STM32 CPU is not getting (correct) responses from the FPGA.
For example if you disable FPGA because you are programming Winbond, this is shown. Also some people have reported stuck logo because the cable came loose during transport.

I know the effect of fpga disabling. I'll check the cable and other things later, now  :=\
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 15, 2018, 08:49:37 pm
Had my fun testing ranges according the sheet of cybermaus, Did the upper 2 ranges with same values of the sheet.

I have modded the opamps for 2 separate ones. Does yield some differences perhaps.

Connected the AWG directly to my scope via coax cables and switched on/off the builtin terminators of the inputs.

Suggestion from my side. maybe we can have an automated step function with adjustable step time for these tests? So then we can just write down values and not switching back and forth programs and edit values. I'm half dead right now :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 15, 2018, 10:02:13 pm
Yes, it does get boring after a while, doesn't it?

If ever we build a per value / per device calibration matrix, yes, we should have such auto-set macro function. Does not even have to be in the BP, can be in the PC.
However, I think for now, all we need is some rough guidelines on what autoranges to select, and maybe some coarse global correct. So maybe one or two more person, then we are done for now.

Unless Fremen67 has different idea's.


Mind you, I did see something interesting in your data: It does not have the weird breakdown in the 10V-60MHz area, where mine does an extra cripple on the top half of each sine, causing negative offset and extra attenuation. I am suspecting the OpAmp for that. Not sure if the entire OpAmp range, or just my specific chip. Anyway, you replaced those, and have clearly better results in that area.

At the same time though, the 15V and above at 50 Ohm load range, your improved OpAmps are (slightly) worse. Only able to drive 6.6V instead of mine 7.4V.
I wonder if that is because my PSU is rather "uncalibrated" (iow bad), and giving out 15V on the 12V rail, or maybe your improved caps on the PSU are not that much better

What we / I should do is hook up the 12V rail completely external from a pair of bench power supplies, I have some capable of 5A each, should be enough.

PS: what OpAmps did you use again? And what voltage is your 12V rail?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 15, 2018, 10:11:11 pm
Also, you made a couple of likely typo's on:

B61; C58; D63; F61; B43; C48; C33; B30;

I15 is also suspicious

Regarding block line 53 to 63: You filled in a 2.75 50Ohm range there, but I had High-Z on that position. So the dB calculation should have an extra /2 (or *.5) that is why it is so red, basically all dB values should be +3.

PS: apologies if this sounds a little pedantic, not really intended, but unsure how else to bring the info.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on March 16, 2018, 12:07:33 am
I'm leaning in the direction of making the modifications you describe. Now feel more confident in replacing the original 50 MHz oscillator. Checked and found the TCXO Model D75J in stock at DigiKey. Thanks for all the tips. :)
Does anyone know another source for the TCXO than digikey? In germany you pay 34 EUR ($42) including postage when you order from digikey.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scratch.HTF on March 16, 2018, 01:39:26 am
I believe that at least one PLL (which is synchronized for DAC data against the DAC clock) is most likely set to 1000 MHz.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 16, 2018, 07:12:45 am
PS: apologies if this sounds a little pedantic, not really intended, but unsure how else to bring the info.

Don't worry one bit, I'm all about content and not about 2nd guessing peoples meaning. If you think it might be wrong I'll check it asap this weekend, no problem. It was becoming very boring in the second half of the measurements so a mistake is easily made.

I did all the measurements in AC mode as I have a DC offset in all measurements. Didn't want to look at it all the time. So I cannot comment on the neg offset of you. And I'll update the sheet for the LowZ of the mid range.

I did not modify the PS actually, only the opamps and the oscillator. I want to replace it with a full linear +5 +- 14V and also +-5V for replacement of the 7805 and 7905 which get to hot for my liking. But need to measure to current draw first.

All in all I think I am a lit bit lower in gain on both output ranges. My 2nd channel is way lower even. Needs to be adjusted first. Also want to change the 10k for the input of the opamp to 33k as suggested earlier to correct the gain for a better x4 gain.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 16, 2018, 09:10:03 am
I looked a bit further into the 20V into 50 Ohm challange. Basically hooked up the +5V +12V and -12V to linear lab-supplies limited to 1Amp
tl;dr; It *barely* matters. Maybe even makes it a tiny bit worse.
So what I conclude is that only upping the power from the PSU is not going to help. Not on my device anyway.
In fact, in my case it brings a tiny bit more imbalance, not sure if that is my device only.

Yellow is 50 Ohm loaded wave, Blue is non-loaded sine, for shape compare

I also measured current with *both* channels 50 Ohm loaded on 20Vpp: -15V was 101mA and +15 was 99mA and +5V was 394mA
Current does not vary from 10KHz to 20Mhz and above that Vpp drops anyway.
However, when going down to 0.01Hz (practically DC) we do get an increase whenever the crest is moving by:  -15V at 130mA and +15 was 128mA

----

Regarding a new PSU: I was thinking: a dual 15V or 18V transformer may be enough.
Two good + and - 15V regulators, as well as a cheap 5V DC to DC switched regulator.

Because if you look at the schematic, you will see the 5V from the PSU is *never* used as rail. Instead it is used to make the lower voltages 3.3V, 1.8V etc.
And the actual system board 5V rail is taken from the +12V supply.

So a small switched 5V module at 400mA would only need 150mA from an unregulated rectified 18V (so hooked up before the 15V regulator)
A simple dual 15V (or 18V) transformer capable of 250mA may be smaller, cheaper, easier then a triple one. Make it 500mA for some headroom.

Of course, I have no proof more power actually helps. Not with the stock OpAmp at least.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 16, 2018, 10:45:10 am
Could you check the input of 2 stages of opamps? Is it going wrong before or after the THS3001 or even earlier?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 16, 2018, 12:57:12 pm
Well, since the non-loaded output is perfect, I did not see how it could be the input of the OpAmp, but I checked anyway.
As expected, the input of the THS3002 is still a good looking sine with curves in all the right places.

Also, I ran the wave all the way down to 0.01Hz, and the shape of the flattened top stayed the same. Meaning it is not a response time thing. Not even a current thing, because if the local capacitor would drain out, surely it would fall off more toward the trailing edge.

I wonder if it is something to do with the fact this OpAmp is described in the datasheet as a "CURRENT-FEEDBACK AMPLIFIER". I do not know what that means, normally when I mess with OpAmp I consider voltages. Need to read up on that.

Also, I wonder if it can be resolve by, instead of replacing, *adding* an OpAmp.
Just leave the THS3002 in place, and add a pair of THS3001. They have the same behavior, the PCB traces are in place, de-soldering is harder then soldering.
All we need to do is add to the unpopulated footprint.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 16, 2018, 01:04:28 pm
A different topic: I found a bodge and a PCB variance
If you look at the images, my V1.5 board has some missing traces which they fixed with a solder blob.
But also, even if the traces were there, it would be slightly different to DerKammi's V1.501 board.

There is also a lot of unpopulated stuff around that chip. Seems to be a place for another tuning pot.
That area is not yet traced into the schematic is it?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 16, 2018, 01:18:12 pm
While I was studying your schematic, also I think I spotted an error (sorry again).
The DAC's for offset output. VoutA and VoutB seems swapped between the A channel and the B channel. Is that correct?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 16, 2018, 02:11:33 pm
Well, since the non-loaded output is perfect, I did not see how it could be the input of the OpAmp, but I checked anyway.
As expected, the input of the THS3002 is still a good looking sine with curves in all the right places.

Also, I ran the wave all the way down to 0.01Hz, and the shape of the flattened top stayed the same. Meaning it is not a response time thing. Not even a current thing, because if the local capacitor would drain out, surely it would fall off more toward the trailing edge.

I wonder if it is something to do with the fact this OpAmp is described in the datasheet as a "CURRENT-FEEDBACK AMPLIFIER". I do not know what that means, normally when I mess with OpAmp I consider voltages. Need to read up on that.

Also, I wonder if it can be resolve by, instead of replacing, *adding* an OpAmp.
Just leave the THS3002 in place, and add a pair of THS3001. They have the same behavior, the PCB traces are in place, de-soldering is harder then soldering.
All we need to do is add to the unpopulated footprint.

Didn't except to see otherwise. Just a sanity check. Current feedback opamps normally have a higher slew rate. Don't know the details which I can explain in person.

Don't connect 2 opamps with the output directly to each other, need some sort of balance resistor normally.

I'll do some LTspice sims on this to try to understand why this clipping is happening. Current is also not a problem as the lower freqs are fine. The combo voltage/current at the 15..20M is something to look at.

A different topic: I found a bodge and a PCB variance
If you look at the images, my V1.5 board has some missing traces which they fixed with a solder blob.
But also, even if the traces were there, it would be slightly different to DerKammi's V1.501 board.

There is also a lot of unpopulated stuff around that chip. Seems to be a place for another tuning pot.
That area is not yet traced into the schematic is it?

Indeed, but the blob is fine. It's a short anyway for the VCO input buffer which is on the schematic. The other side is unknown to me and looks to be a part of the counter input. This is on the planning of next week.

While I was studying your schematic, also I think I spotted an error (sorry again).
The DAC's for offset output. VoutA and VoutB seems swapped between the A channel and the B channel. Is that correct?

Is correct, checked it a couple of times myself. Board routing is more simple in the current state.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 16, 2018, 07:02:05 pm
Updated my mistakes indeed, lots of leading zero's missing  :=\
Also updates the formula in the sheet.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on March 16, 2018, 10:18:16 pm
Suggestion from my side. maybe we can have an automated step function with adjustable step time for these tests? So then we can just write down values and not switching back and forth programs and edit values. I'm half dead right now :)
If ever we build a per value / per device calibration matrix, yes, we should have such auto-set macro function. Does not even have to be in the BP, can be in the PC.

 :) Yes, boring and source of mistakes. If needed, I will do it. I already did this some years ago: automated calibration on a FG with a DMM and and an oscilloscope with SCPI commands from an  excel sheet (do you guess why I was talking of a SCPI interface in the new firmware  ;))
Anyway thank you for your time, both of you. The more values, the more ideas (and you have a lot), the more potential upgrades.

However, I think for now, all we need is some rough guidelines on what autoranges to select, and maybe some coarse global correct. So maybe one or two more person, then we are done for now.
Agreed on that. I will also run tests and that will be enough data at the moment.
It seems now obvious that we have first to deal with some hardware upgrades before finding software workarounds.
For now I will add static calibration only on the 3 ranges on amplitude and offset. This should be enough for low frequencies.
For higher frequencies, it will be time to think about it later on and decide, after fine tuning the opamp part, if this will be done in FPGA via digital filters (zov maybe?) or if something can be done via FP.

Also, I ran the wave all the way down to 0.01Hz, and the shape of the flattened top stayed the same. Meaning it is not a response time thing. Not even a current thing, because if the local capacitor would drain out, surely it would fall off more toward the trailing edge.

I wonder if it is something to do with the fact this OpAmp is described in the datasheet as a "CURRENT-FEEDBACK AMPLIFIER". I do not know what that means, normally when I mess with OpAmp I consider voltages. Need to read up on that.
From the THS3001 datasheet: "The ability to control the amplifier gain independent of the bandwidth constitutes a major advantage of current-feedback amplifiers over conventional voltage-feedback amplifiers"

A test I would suggest would be to use the feedback resistor value recommended in the THS3001 datasheet, that is 560 ohms for a gain around 5 instead of 1.5kohms. Then replacing the gain resistor with a 180 ohms one instead of the 499 ohms one. This would lead to a gain of 4.11 that could be compensated by the software calibration.
I have some THS3095 ready for tests as well as preproduction THS3491 but not time to do it now...

Also, I wonder if it can be resolve by, instead of replacing, *adding* an OpAmp.
Just leave the THS3002 in place, and add a pair of THS3001. They have the same behavior, the PCB traces are in place, de-soldering is harder then soldering.
All we need to do is add to the unpopulated footprint.
Good idea but as DerKammi said, we would have to add shared output resistors. May not be to difficult to modify traces for that... That is a typical design with THS3491.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 16, 2018, 11:13:55 pm
I managed to find a new ST-Link locally, so I spent a few hours doing cybermaus's range test, as per the attached spreadsheet.  These were carried out on a factory 1.501 board with linear power supply feeding +/-12.2v (adjustable to 15v when needed).  I've also got a couple of THS3095s on order, in the expectation that another mod will be the order of the day quite soon.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 17, 2018, 06:45:41 am
@DaveR: Please add a leading 0 to F60

For the rest, your data looks similar to mine, including the extra dampening spot around 10V/60MHz
But you have no negative offset in that region?

DerKammi's device with the THS3095 does seem to be less deformed in the higher frequencies.
I mean, the color assignment is manual, so a little subjective, but he did not even paint them yellow.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gandalf_Sr on March 17, 2018, 08:41:44 am
DerKammi, I looked at the schematic but U7 (74HC245DW) does not tshpw the power rail connections and I need to know the voltage it's running at to give a recommendation for a replacement.  I'm guessing that it's 5V as it says TTL output and that is actually a limitation on what CMOS family it can be replaced with.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 17, 2018, 11:26:03 am
Wrong guess :) It's on the 3V3 regulator actually.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 17, 2018, 05:35:34 pm
Well spotted, cybermaus - corrected sheet attached.  Our sets of results are indeed very similar, but I certainly didn't see any extra negative offsets in the places you did - unless the amplitude "flickering" I saw was the same thing?  It occurred in the same parts of the high range you noted it, but what I got was a fleeting extension of the negative half of the wave without a corresponding downward movement of the positive half, so I deemed this to be more amplitude instability than an offset change.  It could have been a combination of both, thinking back to it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 19, 2018, 10:08:23 am
:) Yes, boring and source of mistakes. If needed, I will do it. I already did this some years ago: automated calibration on a FG with a DMM and and an oscilloscope with SCPI commands from an  excel sheet (do you guess why I was talking of a SCPI interface in the new firmware  ;))
Anyway thank you for your time, both of you. The more values, the more ideas (and you have a lot), the more potential upgrades.

NICE!

Also, I ran the wave all the way down to 0.01Hz, and the shape of the flattened top stayed the same. Meaning it is not a response time thing. Not even a current thing, because if the local capacitor would drain out, surely it would fall off more toward the trailing edge.

I wonder if it is something to do with the fact this OpAmp is described in the datasheet as a "CURRENT-FEEDBACK AMPLIFIER". I do not know what that means, normally when I mess with OpAmp I consider voltages. Need to read up on that.
From the THS3001 datasheet: "The ability to control the amplifier gain independent of the bandwidth constitutes a major advantage of current-feedback amplifiers over conventional voltage-feedback amplifiers"

A test I would suggest would be to use the feedback resistor value recommended in the THS3001 datasheet, that is 560 ohms for a gain around 5 instead of 1.5kohms. Then replacing the gain resistor with a 180 ohms one instead of the 499 ohms one. This would lead to a gain of 4.11 that could be compensated by the software calibration.
I have some THS3095 ready for tests as well as preproduction THS3491 but not time to do it now...

As I mentioned I wanted to do some LTspice sims. Had a go with the different feedback resistors, 1k5 as of feeltech. 1k as suggested in the datasheet as all rounder and 560 as per datasheet and fremen76 his suggestion. The 1k version has my preference as the gain is linear in the whole range, gain is 4.0297 in the sim. The 560 shows a bump at the 60..120MHz.

Also did some sims on the max gain vs. voltage. The 12V voltage does not seem to be adequate for 20MHz, 4x gain and 10Vpp out. 15V supply is enough.

I got the Pspice model of the TI site and imported into LTspice, this is working fine normally.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 19, 2018, 11:06:33 am
While your simulation does show a better curve from ~30MHz to 100MHz for the 1K resistor, I am not sure if it explains what we are seeing.
We see the odd flattening (not even calling it clipping, its not sharp enough) at *any* frequency, even at 1Hz, and at both voltages rails of 12V and 15V

So I think we are seeing a different effect.
To be sure, can you run those last two simulations at lower frequencies?


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 19, 2018, 12:15:31 pm
Those are the same questions I'm having, it doesn't explain our findings. I had a huge amount of ringing in the flat spot also, more like oscillations of any sort. Maybe the power supply is acting up because of the low quality capacitors.

I did the sims also at 1k, same effect.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 19, 2018, 04:27:39 pm
I finally ordered the JST HX connectors so I can fix my cable and a couple of the "blue pill" STM332F104 boards.  So I should be able to get to work on the FY shortly.  Though I've got a rather large backlog of other projects under way.  My programmers came last week.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 19, 2018, 04:57:52 pm
@Insatman:

Replacement of 50Mhz clock chip with TCXO (1ppm).   

  It has 10 pads of which only 4 are used.  You must connect pads 8 and 9 in this application.

Can I just clarify something with you before I do this mod (I received the D75J and two THS3095s today)?  Did you mean that pads 8 and 9 have to be connected together, ie both to the same solder pad on the board (the one next to L1)?  In other words, you are only using three of the original four solder pads, with the one next to C1 taped off, but still using all four "active" pads on the D75J ?

Thanks,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 19, 2018, 08:59:12 pm
I think we're actually pulling too much current out of the THS3001/2. After some searching around the web and triggering by fremen76 his attachment even the new super THS3491 is in need of 2 chips for driving 13Vpp at 50r. And the THS3491 is capable of delivering 380ma instead of the 100ma of the ths3001.

That 13Vpp is delivered at 100r total load and would mean 6.5V/100 = 65mA. That doesn't look like much of a problem for the 380mA super chip. But still they recommend 2 chips. If the THS3491 can't even do 65mA how is the 4 times lower rated THS3001 able to do it then. It doesn't make 100% sense but this is what mind came up with this evening.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 19, 2018, 09:37:18 pm
So the spice model is rather off at these high currents at high voltage.
Also, it would mean the THS3091/3095 is actually better then the THS3495:
(https://i.imgur.com/O3m5TS1.jpg)
(https://i.imgur.com/GTVAOwx.jpg)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 19, 2018, 09:47:36 pm
Mind you, I think I will pass on modifying the base PCB traces to double up OpAmp. Lots that can go wrong there.
I think I will fix mine by modifying the documentation:

Specs
Output at High-Z load:
  <10MHz         : 20Vpp
  10MHz<f<20MHz  : 10Vpp
  >20MHz         : 5Vpp
Output at 50 Ohm load:
  Any f          : 5Vpp


Modifying with a single 3091/3095 is still a good idea though. Your without load above 20MHz waveform seems better then mine, assuming you colored your XLS correctly.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 20, 2018, 01:26:44 am
@Insatman:

Replacement of 50Mhz clock chip with TCXO (1ppm).   

  It has 10 pads of which only 4 are used.  You must connect pads 8 and 9 in this application.

Can I just clarify something with you before I do this mod (I received the D75J and two THS3095s today)?  Did you mean that pads 8 and 9 have to be connected together, ie both to the same solder pad on the board (the one next to L1)?  In other words, you are only using three of the original four solder pads, with the one next to C1 taped off, but still using all four "active" pads on the D75J ?

Thanks,
Dave

For confusions sake I will call terminals on the D75J "pins" and connections on the PCB "pads".

Yes you must connect pins 8 and 9 together.  Pin 8 is the Enable Pin and must be held High.  I only used three of the original pads and taped off the one closest to C1.  I did this because the datasheet says not to connect to pins 1 and 2 which are facing that pad on the PCB.   Good Luck. 

I should look into the THS3095.  Thus far I have made no mods to the main PCB except the clock chip.   This thread is getting way long.  Can anyone explain quickly benefit of using the THS3095 and which  IC it replaces?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 20, 2018, 01:53:19 am
Thanks for that, Insatman.  I thought that was how you'd done it, looking at your photos, but I just wanted to make doubly sure :)

As for the 3095s, they are to replace the single 30021 opamp under the heatsink on the signal board - see here :  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/)

As to how well they work, well I'll find out tomorrow after I've put mine in and re-run the high range tests.  I'll do the D75J mod after that, but it will have to be later in the week as I've got some urgent car maintenance to get out of the way as well.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 20, 2018, 02:36:42 am
Thanks for that, Insatman.  I thought that was how you'd done it, looking at your photos, but I just wanted to make doubly sure :)

As for the 3095s, they are to replace the single 30021 opamp under the heatsink on the signal board - see here :  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/)

As to how well they work, well I'll find out tomorrow after I've put mine in and re-run the high range tests.  I'll do the D75J mod after that, but it will have to be later in the week as I've got some urgent car maintenance to get out of the way as well.

Please let me know what difference the 3095 chips make using the standard +/-12V power supply rather than the +/- 15V supplies some have retrofitted.  I'm considering ordering them at about $10 each from Digikey on my next order.   I'm reluctant to change out the power supply at this point, other than the mods I've already done to it.

Good Luck with the car maintenance.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 20, 2018, 06:47:01 am
Please order the THS3091, is doesn't have the shutdown pin as the 5 does, we don't need it.

@cybermouse, I'm more than happy with the current output, possibly never use it at these high levels and frequency's together. But a change to the THS3091 I would possibly try out anyway. Just to clarify things whether it helps yes or no.

The white cells in the excel are correct, I checked them yesterday evening. The amplitude goes down by a large amount and therefor the signal stays OK.

The graphs you show are missing in the THS3001/2 datasheet but do show some table values which are running into overload in our use case.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 20, 2018, 08:04:03 am
Please order the THS3091, is doesn't have the shutdown pin as the 5 does, we don't need it.
I checked that I while back, when @Vytautas first mentioned the THS3095, but luckily leaving the pins floating is defined in the specs:
"7.2.1 The power-down pin of the amplifier defaults to the positive supply voltage in the absence of an applied voltage,
putting the amplifier in the power-on mode of operation."
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on March 20, 2018, 08:05:05 am
Ahh ok, just pick the cheapest then :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on March 20, 2018, 03:06:26 pm
So mine finally arrived this morning.  Powered it up and measured the BNC shield to Earth. 

96.6V AC (240V supply)
68uA current

Had a play and orientating the 5V reg module, +-12V reg module and the RCore transformer is just about doable, but not if I replace the power socket/switch with a fused/switched IEC 3 pin socket.  The socket protrudes quote a lot.  Might need to get creating like mounting the socket with spaces so it protrudes in less.

I might be able to live without the transformer chassis earth, but I don't think I can live without a fuse.

Question:

If I am going to use this to test basic op-amp circuits, mostly audio.... how much risk is there in using it as is?

Does it matter if I add a ground referenced USB connection into the mix?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on March 20, 2018, 09:15:09 pm
So my supplier actually got me the replacement chip like they said they would. They shipped me the ST microelectronics chip, and the winbond flash chip. I will install them in my working version 3.1 unit and verify that the version has been changed to version 3.2+. At that point I will ship out the 3.1 chips for testing by the community.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Cliff Matthews on March 20, 2018, 10:47:51 pm
Hello all, there's a new forum member that posted ( https://www.eevblog.com/forum/beginners/software-feeltech-fy6600/ (https://www.eevblog.com/forum/beginners/software-feeltech-fy6600/) ) that he received his FY6600 but the CD is not readable. Is there a link anyone can post to help this member download it? - Thanks!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on March 20, 2018, 10:52:35 pm
Hello all, there's a new forum member that posted ( https://www.eevblog.com/forum/beginners/software-feeltech-fy6600/ (https://www.eevblog.com/forum/beginners/software-feeltech-fy6600/) ) that he received his FY6600 but the CD is not readable. Is there a link anyone can post to help this member download it? - Thanks!

Let's have a fresh link here as well:
https://drive.google.com/drive/folders/0B3N_NW8vylrmQVNrbXVERnltSFk (https://drive.google.com/drive/folders/0B3N_NW8vylrmQVNrbXVERnltSFk)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gandalf_Sr on March 20, 2018, 10:58:10 pm
If the 74HC245DW runs on 3.3 volts then there is a drop in replacement in the LVC version which is about twice as fast. See the chart below which is taken from Ti's CMOS logic guide (http://www.ti.com/lit/sg/sdyu001ab/sdyu001ab.pdf).  AUP would be faster but it's not available in the same package (as far as my limited search went).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 21, 2018, 12:37:56 am
I installed the THS3095 opamps in mine today and re-ran the high range tests as per the attached file.  The results are self evident, and the improvements above 10MHz are very clearly seen.  What isn't seen is that, having viewed the improved waveforms, I was definitely more critical as regards distortion etc this time around, so the real improvement isn't just in the output levels but in the overall quality of the outputs as well.  I also noted that throughout the tests the factory heatsink on the opamps barely got warm, so it's probably grossly oversized already or not needed at all.

I ran the tests this time at +/- 13.5v (I don't want to push any dodgy 16v caps too hard), but at Insatman's request I also checked the 40 - 60MhHz results at +/- 12.0v and there was little or no difference in the results, so it appears that the 3095s are quite happy at the original PS voltages, and I rather doubt there'd be any changes if I upped the supply voltage to 15v.  If you need the higher outputs, then changing the opamps appears to be a "just DO it" mod.

Next task (for fun) is the TCXO change to see how much it stabilises the 40 - 60MHz outputs.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 21, 2018, 03:50:36 am
Re: THS3095

Please help me out.. Digi-Key shows two versions of THS3095, namely the THS3095D and THS3095DDA. The latter one has a power pad but otherwise looks similar. Can the power pad be a problem here? Which one would be best? Which one are you using?

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 21, 2018, 09:18:33 am
I wonder if these are genuine?
https://www.ebay.com/itm/292350281588 (https://www.ebay.com/itm/292350281588)

Oh well, I'll find out soon enough, as I ordered some.
I figure they are not re-used, as they are in the reel cutoffs still.

Please help me out.. Digi-Key shows two versions of THS3095, namely the THS3095D and THS3095DDA. The latter one has a power pad but otherwise looks similar. Can the power pad be a problem here? Which one would be best? Which one are you using?

I had the same doubt. I guess it could be a problem if the powerpad is shorting out traces below, but I figure that can be solved with a strategically placed piece of kapton tape.
But yes, people already using 3095, please say which one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 21, 2018, 11:32:56 am
I bought the plain version without the power pad.  The power pad version is for specially designed boards which have thermal conductivity built in directly under the chip, so that they don't need a passive cooler on the top.  It may or may not work without a problem on the FY6600, but there's no point in buying it to find out that it doesn't :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 21, 2018, 11:38:56 am
I wonder if these are genuine?


At that price I'd say they will be genuine Chinese imitations of the real thing!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 21, 2018, 01:25:57 pm
Re: THS3095

Rough calculation indicates that THS3095 may dissipate up to 0.5W or more when operating with 50 ohm load. IMHO this requires good heat sink.  Looking at Vals post #167 and photos, it appears that three chips will now need to connect to the heat sink. Are all three chips at the same height?  Yes, heat sink compound must be used, but don't want big gap between devices and heat sink.  Does anyone see a problem here? Use individual heat sinks?

Related question: Was a low power soldering iron used or is hot air tool required to install the devices?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 21, 2018, 03:57:31 pm
Well, the calcs are one thing, but my finger tip says there's no heat output worth worrying about - and I was running them under a 50 ohm load for several hours last night.  However, all three chips now under the heatsink make good contact with it and there's no rocking at all, so there's little need for any compound to be used (there wasn't any on mine to start with).  If you're still concerned about heat dissipation, I'd use some pieces of adhesive thermal pad rather than paste, which will just make a big mess as you put the heat sink back on.  The pads will also take up any height discrepancies which may exist when you've finished.  Individual heat sinks will need to be very small themselves to fit next to each other, and they'll probably be less efficient than what's already there.  (I only mentioned the heatsink because I recall some recent post talking about putting an even bigger cooler on them - something which is definitely not necessary.)

I used a hot air gun to remove the THS3002 and a very fine cranked tip on my soldering iron at 260degC to install the 3095s.  The pads on the board are already tinned so you should be able to use a hot air tool to fix them - if you can hold them down in the right places while you wave the gun around over them.  I just prefer to use the soldering iron so that I can see exactly what's happening on each pin and know that the joint is good.  You'll need a good magnifier or loupe for the job as well, unless you've got the eyes of a hawk.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 21, 2018, 04:20:00 pm
Another observation after the 3095s mod is that you can now get half decent output up to at least 100MHz using the two or three cycle sine wave trick.  However, attenuation of the output continues to increase with frequency - you don't get higher output amplitudes despite starting from a lower base frequency in the control software.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: norms on March 22, 2018, 12:28:31 am
Ok, new to this forum. I have a few questions about this 60Mhz Generator which I was not able to find on the net. I would be grateful if someone can answer these queries before I buy one.

1. I need a fm signal at 10mhz with a 1khz modulation, would this unit be able to do that. The manual mentions a vco max of 1khz, but then says vco frequency should be below 500hz.   ???

2. what is the maximum frequency that can be used for the carrier frequency.

3. The firmware version 3.2 is mentioned as the best one to get, I see screen shots show version 2.6. Was 2.6 an earlier sold version or is this references some other version and not the firmware
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: canyon on March 22, 2018, 01:54:50 am
Gang,

It's been quite some time since I checked in here. I have a FY6600 v3.0 that got scrambled the third time I used it. Is there any remedy, reflash or fix available. Or, is it just a plastic case for a new project?

ken
wa4mnt@gmail.com
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 22, 2018, 03:17:54 am
Hi norms,

In answer to your questions, the FY6600 can do a 60Mhz carrier modulated internally at up to 100kHz (tested) and externally at up to 2kHz (according to the latest manual).  Firmware version 3.2 or 3.2.1 is the one which should be supplied if you buy one now, and it appears to be stable.  Earlier versions 3.0 and 3.1 had serious problems, but those should be well out of circulation by now.  I think any version prior to 3.0 probably refers to an earlier model or one of the cheaper, lower maximum frequency versions which can be bought.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 22, 2018, 03:29:46 am
It's been quite some time since I checked in here. I have a FY6600 v3.0 that got scrambled the third time I used it. Is there any remedy, reflash or fix available. Or, is it just a plastic case for a new project?


Hi Ken,

At the moment it's still just a plastic case, but work is well under way on a project which may yet see it able to be revived in one form or another.  Have a read of the last few pages to get a feel for what's going on, and keep your fingers crossed :)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 22, 2018, 10:08:23 pm
I installed the D75J TCXO chip last night, and my frequency error went down from -4.65ppm to 0.45ppm, and after warm up and calibration it was down to 0.02ppm and rock steady - a pretty good result, although it was almost "a mod too far".

For anyone else contemplating replacing the existing clock chip with the D75J, please take my advice NOT to try to solder it directly to the board after the old chip has been removed, as the pads on the new chip are tiny, completely hidden from view, and only just coincide with the edges of the existing solder pads, so getting the chip positioned exactly right is a matter of pure chance.  I think luck must have been with Insatman when he did it, but I wasted over two hours struggling to get the connections made before giving up.  Instead, just cut three pieces of fine wire about 8mm long (34 gauge worked very well) and solder them to pads 4,5, and 8+9 on the chip, then bend them into legs and feet so as to give about 3mm clearance from the board.  Soldering the feet to the board then becomes a simple matter because you can now see precisely what you are doing.  After the abuse it took I'm surprised the chip still worked in the end, but if it packs up now I know I can replace it without fuss in a matter of minutes!

I think that's all the hardware modding done now, except for painting the box red and putting go-faster stripes down the sides, but that can wait :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on March 22, 2018, 11:28:05 pm
Thats a pretty good result Dave ,a ten fold reduction in drift or more.

I have the 3095's here too but I havent soldered them in yet ,is there something about lifting one leg for the powerdown feature ?
Are there already low value output mixing resistors so the two halves of these op amps run correctly?
Are there any other adjustments needed to fix the gain of the stage ?
Might solder in these op amps in the next few days.
I wonder if theres much improvement in THD% with the new op amps in place ,the original spec on the Fy6600 is 0dbm and .8%THD, be nice if that figure comes down a bit .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 23, 2018, 01:14:43 am
Hi soundtec,

Yes, I'm very pleased with the final result - 60Mhz sine waves with no more than a little amplitude modulation now, otherwise a perfect waveform.

For the 3095s, just solder them in as they are: they'll work fine.  No need for anything else except to remove the existing 3002.  It looks as if Feeltech may have been planning for a future higher spec version and made provision for dual amps on the board - which is very fortuitous for us as they make a big difference.  I would imagine the THD does come down, but I've got no means of verifying or quantifying it. 

Happy modding!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on March 23, 2018, 08:01:05 am
For anyone else contemplating replacing the existing clock chip with the D75J, please take my advice NOT to try to solder it directly to the board ..
Can you please make some pictures of your work. I would really appreciate this!

And do you have pictures of the replacement of the THS3095 too (before / after)?
Replacing them is just removing the old ones and replacing with the THS3095 at the same location?

I think I saw already a picture here but cannot find it and slowly I am getting nearer and nearer to make both of this modifcations too  8) after I already made the most important linear psu thing. So I need to complete my local information.

EDIT:
Found the infos for the OP-Amps https://github.com/DerKammi/FY6600-15-30-50-60M
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 23, 2018, 01:12:19 pm
Sorry,  Candid, I didn't take any photos, but you can see Vytautas' before and after pics of his THS3095 changeover here:  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/)

As for the D75J, just read my description in conjunction with what you see when the old clock chip is removed - it will be obvious what needs to be done when you look at the four solder pads on the board and compare them with those on the chip (using the datasheet to identify them).  Basically you are just adding three short table legs to the chip to make it ten times easier to fit onto the board.  You won't be connecting anything to the solder pad next to C1 on the board, and the legs are connected to the other three pads matching each corner of the chip.  For the correct orientation of the chip, see Insatman's photo here:  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/800/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/800/)

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 23, 2018, 01:20:10 pm
Sorry,  Candid, I didn't take any photos, but you can see Vytautas' before and after pics of his THS3095 changeover here:  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/)

As for the D75J, just read my description in conjunction with what you see when the old clock chip is removed - it will be obvious what needs to be done when you look at the four solder pads on the board and compare them with those on the chip (using the datasheet to identify them).  Basically you are just adding three short table legs to the chip to make it ten times easier to fit onto the board.  You won't be connecting anything to the solder pad next to C1 on the board, and the legs are connected to the other three pads matching each corner of the chip.  For the correct orientation of the chip, see Insatman's photo here:  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/800/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/800/)

You know, it is actually possible to link to specific message inside a page rather the the top of the page.
That is a little easier for people to know which one you meant.

Like these:

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1348087/#msg1348087 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1348087/#msg1348087)

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1434962/#msg1434962 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1434962/#msg1434962)

Just rightclick on the specific message and do "copy link address"
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on March 23, 2018, 02:35:48 pm
Thank you for your help. I ordered from digikey because no chance to get the TCXO in germany directly. Even the german distributor does not have in stock and cannot name any supplier in germany. So in the end I paid 52 EUR for the TCXO and the THs including tax and postage. But I started with the linear psu and cannot stop on half the way now with the FeelTech experiment :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 24, 2018, 02:20:16 am
I installed the D75J TCXO chip last night, and my frequency error went down from -4.65ppm to 0.45ppm, and after warm up and calibration it was down to 0.02ppm and rock steady - a pretty good result, although it was almost "a mod too far".

For anyone else contemplating replacing the existing clock chip with the D75J, please take my advice NOT to try to solder it directly to the board after the old chip has been removed, as the pads on the new chip are tiny, completely hidden from view, and only just coincide with the edges of the existing solder pads, so getting the chip positioned exactly right is a matter of pure chance.  I think luck must have been with Insatman when he did it, but I wasted over two hours struggling to get the connections made before giving up.  Instead, just cut three pieces of fine wire about 8mm long (34 gauge worked very well) and solder them to pads 4,5, and 8+9 on the chip, then bend them into legs and feet so as to give about 3mm clearance from the board.  Soldering the feet to the board then becomes a simple matter because you can now see precisely what you are doing.  After the abuse it took I'm surprised the chip still worked in the end, but if it packs up now I know I can replace it without fuss in a matter of minutes!

I think that's all the hardware modding done now, except for painting the box red and putting go-faster stripes down the sides, but that can wait :)

I did have a bit of trouble soldering the D75J, but not as much as you did I guess.   After my first attempt the ground lead was open so I simply heated up the corner of the PCB pad and shoved more solder in.  That worked the trick as Aussie Dave would say.   The D75J ended up a bit crooked in my eariler posted pic but I was not about to unsolder it to fix that.   I probably should have said a bit more about installation in my earlier posts.  I think your method is probably better.   I got similar results on the frequency stability/accuracy.   Now to install those THS3095 ICs that arrived yesterday.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 24, 2018, 02:48:45 am
Umm...

You guys do realize that what you're doing is quite insane don't you?    I think it's pretty cool, but on an objective level it's more than a little daft.  It's like building  a 200 HP air cooled VW.  You *can* do it, but it really doesn't make sense.

I just want mine to work!

Proud owner of a V 3.1,
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 24, 2018, 03:14:11 am
Umm...

I think it's pretty cool, but on an objective level it's more than a little daft.

Since when has objectivity taken precedence over having fun??  We mod because we can! ;D ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 24, 2018, 03:36:38 am

Just rightclick on the specific message and do "copy link address"

Thanks for the pointer, cybermaus - I've done it correctly before, but when the wife's dressed up ready to go shopping and standing behind you, sighing impatiently, it's hard to remember the simple things!

It's actually right-click on the message title and select "copy link location" in my version of Firefox, but I think it's now burned into the memory banks!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 24, 2018, 04:42:54 am
After my first attempt the ground lead was open so I simply heated up the corner of the PCB pad and shoved more solder in. 

It was probably your chip being crooked that helped, and you accidentally found the only position where it would work!  I tried shoving more solder in on all three corners but, being the perverse stuff that molten solder is, it just refused to find one of the pads on the chip, even though I'd tinned them first.  The chip was rigid, so I knew I had two corners fixed, but I couldn't tell which two they were.  Still, the end result was well worth the trouble!!

You'll have no problems with the 3095s :).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: norms on March 24, 2018, 05:21:53 am
Is there some place which has waveforms that can be downloaded for this generator, or is there a site which has user uploaded waveforms which may be compatible. Would be nice to have wide selection to choose from.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 24, 2018, 06:27:57 am
I just want mine to work!

A very valid goal.

And I think it is OK to inform new users by posting every so often that these mods are not strictly needed to have a nicely working $90 AWG signal generator with a good cost/benefit ratio out of the box. But that does not mean we cannot play. 

And also, every so often some handy piece of information may fall out that even the more conservative owners can use.

But yes, adding a €45 TCXO on a $90 device also took my attention. Only do that if you enjoy doing that.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on March 24, 2018, 08:23:31 am
Any tips on getting this to produce bode plot?

I tried earlier today and I don't see a way to output a square wave for the trigger on channel 2.  Also is there a way to one shot the sweep?

Granted it would do without those, but I think at least the trigger would make it easier to read on the scope.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 24, 2018, 10:59:55 am
What I did though is I made a custom waveform, 0 to max, for VCO input to sweep, and a small -max pulse at the beginning to trigger the scope. And I fed that into the VCO in the back. So no need for a square wave.

If you are doing this at higher freuqencies, the pulse at the beginning may need to be more than just one sample, because we may have 8192 samples, but above 30KHz not all samples make it to the signal (250MHz sample rate / 8192 samples)

How to one-shot it though? not sure, I guess that would be a feature request to fremen67.
But why not simply repeat your bode plot?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 24, 2018, 02:52:43 pm
Buying and modifying a FY6600 is not as bad as it sounds. My FY6600 cost $98 with free shipping, the DJ75J-050 TXCO cost $11.44 and the two THS3095Ds cost $19.84. My total: US$129.28  Assuming you don't fry your FY6600 making the modifications, you will have a FG/ARB SG that compares in many features to some of the higher priced ARB/SGs from Rigol, Hantek and Tek.

For example, the Tek AFG1062 has many of the same features but costs over $840. Granted the AFG1062 is better built and has much better support. But in my case I wanted an ARB/SG for doing some limited experiments with variable phase output and internal direct modulation. For this it works good.  Its also a good tool for demonstrating various waveforms and phase shift to science classes.

BTW, on another thread here on EEVblog it was mentioned that a new FY6800 model will be released next week. It is supposed to fix many of the problems discussed here. It will be interesting to see what it looks like.

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 24, 2018, 04:34:13 pm
Assuming you don't fry your FY6600 making the modifications, you will have a FG/ARB SG that compares in many features to some of the higher priced ARB/SGs from Rigol, Hantek and Tek.
Arguably, without mods we have that.

Please note these specs from the Rigol DG1062Z, comparible dual 60MHz for $950

   Range
   ?10MHz: 1.0mVpp to 10Vpp
   ?30MHz: 1.0mVpp to 5.0Vpp
   ?60MHz: 1.0mVpp to 2.5Vp
   Offset (into 50 ?)
   Range (Peak ac+dc) ±5Vpk ac+dc


So, we may complain about distortion into 50 Ohm load above 10Vpp, but the Rigol does not even go there.
And we had some High-Z SA images that proved to be very good without 50 Ohm
To compare we should check 50 Ohm only to 5Vpp, and the others only to 10Vpp

Interesting about the FY6800 though. Likely going to be the better choise going forward. But hacking, modding, tweaking aside, unless I brick it, I am not in need of a new one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Lanvernazal on March 25, 2018, 02:39:42 am
Hello, does anyone know what was supposed to improve version 3.0 compared to version 2.9 (which I own and which works well for the moment)?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 25, 2018, 06:43:41 am
We know they de-proved the lifespan. Significantly. V3.0 will die on you.

But it seems a moot question, we don't have the firmware files, so you cannot upgrade.
Unless you are thinking of buying another one, but if you see a 3.0 in a shop, leave it well alone, only 3.2 or higher is advised for new purchases.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on March 25, 2018, 08:06:35 am
What I did though is I made a custom waveform, 0 to max, for VCO input to sweep, and a small -max pulse at the beginning to trigger the scope. And I fed that into the VCO in the back. So no need for a square wave.

If you are doing this at higher freuqencies, the pulse at the beginning may need to be more than just one sample, because we may have 8192 samples, but above 30KHz not all samples make it to the signal (250MHz sample rate / 8192 samples)

How to one-shot it though? not sure, I guess that would be a feature request to fremen67.
But why not simply repeat your bode plot?

Thanks.  To be honest I was just experimenting, never tried to make a bode plot before, I figured out the concept one rainy morning but then found Dave's video on the same.

My scope is a bit limited and I found it was tricky without the trigger and with the sweep repeating to set the time base and pause the scope at the right point.

If I understand you correctly, your custom waveform sets the frequency of the sweep?  Like the remote VCO input on an old synth?   Could you not add 0Hz portions to either end to at least delimit the bode plot clearly.

Anyway, I think for the level of testing I am doing, which is purely indicatively verifying the real circuit does roughly what Spice said it would it's probably fine with what I have, though I might experiement with the VCO waveform at some point.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 27, 2018, 03:20:29 am
Paulca, expanding on the suggestion of Cybermaus, you can get a triggered sweep for your scope by feeding a low frequency negative ramp from CH2 to the VCO terminal in back. Make sure your ramp goes from 5V to 0 V, using offset and amplitude adjustments. Set your start and stop frequencies, then use"Forth" in Sweep selection to get a forward frequency plot. Your scope can be triggered directly from the positive edge of the ramp using a second scope channel or ext trigger.

While this does work, it is cumbersome and fraught with possible errors. For more serious work with frequency response plots I suggest you get a low cost scalar network analyzer. There are plenty of low cost ones on eBay.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on March 27, 2018, 03:38:46 am
Paulca, expanding on the suggestion of Cybermaus, you can get a triggered sweep for your scope by feeding a low frequency negative ramp from CH2 to the VCO terminal in back. Make sure your ramp goes from 5V to 0 V, using offset and amplitude adjustments. Set your start and stop frequencies, then use"Forth" in Sweep selection to get a forward frequency plot. Your scope can be triggered directly from the positive edge of the ramp using a second scope channel or ext trigger.

While this does work, it is cumbersome and fraught with possible errors. For more serious work with frequency response plots I suggest you get a low cost scalar network analyzer. There are plenty of low cost ones on eBay.

My FY6600 (V3.2) has quite significant variation of amplitude with frequency. While I have used the CH2 ramp to sweep, the result is approximate at best.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on March 28, 2018, 07:27:34 pm
So ,today I took out the original op-amp and soldered in the pair of THS3095's , worked out fine ,slight clipping on the upper sideband of the sine at 20V p-p , as soon as I dialed in .1 volt offset negative the clipping appeared on the lower side instead , shows that balance is fairly good at least . My 12 volt rails are around 11.5 volts so I reckon a couple of extra volts will sort out the clipping issue.The other thing I did was add two layers of thermally conductive insulation on top of each 3095 ,that made up the height difference between the 4558 and the new chips nicely ,I put a small amount of thermal paste on the 4558 also ,even without the new op amps I think sorting the height difference makes sense and allows better conduction to the heatsink . I didnt get a chance to check to see if the op amps made any difference to THD ,but  I'll do that at a later date . It would be nice to be able to bring THD down from the .6% figure quoted in the specs ,would definately make it more suitable for audio testing .Id be interested if anyone else has measured distortion with a linear psu also.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: KD4PBS on March 29, 2018, 01:32:58 pm
For what it's worth as another data point for discussion on this topic, I'll add my experiences with our shop purchasing the Koolertron version of this generator a couple of months ago. 
The 60MHz unit arrived from the Ebay vendor's warehouse in Walton, KY quickly.  Upon initial unboxing and examination of the unit, it was discovered that several waveforms were missing from the generator, right out of the box: Lorenz, Sinc (I assume they meant "Sync"?), Multi-Tone, Exp-Decay, Exp-Rise, and Noise.  No waveforms were output, and the representative waveform on the display was missing; nothing but a flat-line.  Immediately I filed a return.  The vendor was quick to answer back with accusations that I didn't know how top operate the generator, that I should watch a video, and that obviously the generator was fine - the PEBKAG.  They demanded me to post a video of the problem before they would do anything about it.  I wasn't going to stand for that crap and having to jump through their hoops (I can't easily post a video for their amusement) and let them know exactly what was going to happen; send the defective device back for a full refund.  First they stalled a few days.  Then their shipping label that they uploaded to Ebay was irretrievable.  Upon investigation, it was discovered that this is a frequent ploy that some less-than-honest sellers will do; upload an invalid .pdf file as a return shipping label, and in the process, shift all of the legwork of doing the return to the poor soul who bought the defective item in hopes that they'll eventually just give up, or perhaps stall things long enough that the return period will expire.
Long story short, I ended up having to drive tens of miles to get the thing shipped, using my own money.  Their idea of "reimbursement" for the shipping fee was to short change me by exactly $1.  They told me that since they accepted return on my device (yeah, after more than 2 weeks of back-and-forth ridiculousness!) they expected me to reverse the negative feedback given for the transaction (the first and ONLY time I've ever given such in 15 years of Ebaying).  And their response to that negative feedback was that I didn't know how to operate the device.  Uh... yeah.  That's it... I knew how to get sine, square, triangle, and all kinds of other waveforms out of the device but for some reason I just didn't know how to operate the unit well enough to get those other waveforms out of it.
At least the ARB waveforms would work, and I left within the generator a nice little hand-drawn "hand with middle finger saluting them" waveform. :-+
After all that fiasco, I bought the Feeltech model.  The buttons aren't as nice, and I'll have to deal with the voltage on the ground lead, but other than this, so far so good...  I just need to check what version of firmware.
And if anyone needs to know the vendor name, let me know.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 29, 2018, 02:21:03 pm
No, it is spelled Sinc alright.
Interestingly, you leaving a "middle finger" waveform will probably be interpreted by them as "you see, the Sinc function does work"
Because Sinc sort of looks like a middle finger: http://mathworld.wolfram.com/SincFunction.html (http://mathworld.wolfram.com/SincFunction.html)

Though, honestly? No one will ever look at it, and thus not see your middle finger at all.

As to your ebay return experience: Pretty much how would I expect it to be, except for the end result: you actually managed to return it at their expense (minus $1)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 29, 2018, 03:48:53 pm
I just want mine to work!

A very valid goal.

And I think it is OK to inform new users by posting every so often that these mods are not strictly needed to have a nicely working $90 AWG signal generator with a good cost/benefit ratio out of the box. But that does not mean we cannot play. 

And also, every so often some handy piece of information may fall out that even the more conservative owners can use.

But yes, adding a €45 TCXO on a $90 device also took my attention. Only do that if you enjoy doing that.

I'd be far more interested in feeding my GPSDO from Leo Bodnar to it as the clock.  If I need higher output to drive a mixer, I think an outboard LNA that takes the cleanest signal it produces is a lot simpler to do.  And it has other uses as well.  I think the same startegy is more appropriate for the TCXO as well.

I'm still waiting on my STM32F103 boards and have been busy with an LM399 voltage reference and an HP 3478A DMM that came yesterday.  What's the status of just getting usable FW in my 3.1 unit?  Are we there yet?   Recent posts have been on replacing op amps and such which I'm not rally interested in doing.  I've got an STM32 JTAG so I'm ready to reflash the unit once we have a FW candidate.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: KD4PBS on March 29, 2018, 03:52:54 pm
Ahh!  Thanks!  Silly me thought it was supposed to be "sync", as in a synchronization pulse of some kind.
Little did I know it was a math function, especially since I never saw the waveform  :-//

Honestly?  Yes.  The poor dude that gets this generator re-sold to him from this shady vendor might see it and realize that they're selling B (and possibly C) stock. I don't care how it makes someone else feel... it sure made me feel better!  I will say though, my artwork made it obvious what it was, and it looked nothing like a sinc waveform  :-DD .  I won't even go into what the other arbitrary waveform I drew up resembled... ;)

We'll see how long the Feeltech replacement works, but as often as we use something like this in the shop, I'm betting it will be fine for what it is.  First impressions?  What an excellent little generator, with a few limitations and gotchas, but a good bang-for-the-buck.  Does exactly what we need it to do around the shop.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 29, 2018, 04:05:41 pm
What's the status of just getting usable FW in my 3.1 unit?  Are we there yet?
While true that things are a bit quiet around a usable custom firmware, I'd argue the V3.1 is pretty usable already. It is V3.0 that crashes and hangs.
Pretty happy with my own V3.1
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 29, 2018, 05:52:11 pm
Thanks.  I was a bit concerned that it might get worse.  Also I've been buying new toys faster than I can try them all out.  Mostly I'd like to get the FY6600 fixed and off my "to do" list.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 30, 2018, 12:24:15 am
For what it's worth as another data point for discussion on this topic, I'll add my experiences with our shop purchasing the Koolertron version of this generator a couple of months ago. 
The 60MHz unit arrived from the Ebay vendor's warehouse in Walton, KY quickly.  Upon initial unboxing and examination of the unit, it was discovered that several waveforms were missing from the generator, right out of the box: Lorenz, Sinc (I assume they meant "Sync"?), Multi-Tone, Exp-Decay, Exp-Rise, and Noise.  No waveforms were output, and the representative waveform on the display was missing; nothing but a flat-line.  Immediately I filed a return.  The vendor was quick to answer back with accusations that I didn't know how top operate the generator, that I should watch a video, and that obviously the generator was fine - the PEBKAG.  They demanded me to post a video of the problem before they would do anything about it.  I wasn't going to stand for that crap and having to jump through their hoops (I can't easily post a video for their amusement) and let them know exactly what was going to happen; send the defective device back for a full refund.  First they stalled a few days.  Then their shipping label that they uploaded to Ebay was irretrievable.  Upon investigation, it was discovered that this is a frequent ploy that some less-than-honest sellers will do; upload an invalid .pdf file as a return shipping label, and in the process, shift all of the legwork of doing the return to the poor soul who bought the defective item in hopes that they'll eventually just give up, or perhaps stall things long enough that the return period will expire.
Long story short, I ended up having to drive tens of miles to get the thing shipped, using my own money.  Their idea of "reimbursement" for the shipping fee was to short change me by exactly $1.  They told me that since they accepted return on my device (yeah, after more than 2 weeks of back-and-forth ridiculousness!) they expected me to reverse the negative feedback given for the transaction (the first and ONLY time I've ever given such in 15 years of Ebaying).  And their response to that negative feedback was that I didn't know how to operate the device.  Uh... yeah.  That's it... I knew how to get sine, square, triangle, and all kinds of other waveforms out of the device but for some reason I just didn't know how to operate the unit well enough to get those other waveforms out of it.
At least the ARB waveforms would work, and I left within the generator a nice little hand-drawn "hand with middle finger saluting them" waveform. :-+
After all that fiasco, I bought the Feeltech model.  The buttons aren't as nice, and I'll have to deal with the voltage on the ground lead, but other than this, so far so good...  I just need to check what version of firmware.
And if anyone needs to know the vendor name, let me know.

Interesting story and I think unfortunately all to common on Ebay.   As a side note; besides owning a FY6600 I also bought a JDS6600 unit a few months before buying the FY6600.   Your Koolertron unit appears to be a re-brand of the JDS unit (or perhaps visa-versa).   Out of curiosity, I checked the waveform types that were missing on your unit and they all worked on mine.  I don't use the JDS unit much anymore preferring the Feeltech unit after several modifications/upgrades.   Incidentally, the JDS (and likely Koolertron) units also suffer from the AC leakage current even though they use an external DC power supply.   This is due to the cheap type of switching supply used and lack of any earth ground connection.  I measured similar values of ac leakage on both the JDS and FeelTech units prior to adding ground references to them.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArcticGeek on March 30, 2018, 01:12:42 am
Could someone who owns one of these FY6600 signal generators do a simple test - could you set the unit to output a pulse waveform at 10MHz with a ~40% duty cycle and see if it has any jitter as described in this thread:

https://www.eevblog.com/forum/testgear/rd-jds6600-signal-generator-jitter-on-pulse-output-when-duty-cycle-is-not-50/ (https://www.eevblog.com/forum/testgear/rd-jds6600-signal-generator-jitter-on-pulse-output-when-duty-cycle-is-not-50/)

If the Feeltech is clean I might return my unit, otherwise I suppose I might live with it *sigh*.

Thanks much.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 30, 2018, 04:23:15 am
Could someone who owns one of these FY6600 signal generators do a simple test - could you set the unit to output a pulse waveform at 10MHz with a ~40% duty cycle and see if it has any jitter as described in this thread:

https://www.eevblog.com/forum/testgear/rd-jds6600-signal-generator-jitter-on-pulse-output-when-duty-cycle-is-not-50/ (https://www.eevblog.com/forum/testgear/rd-jds6600-signal-generator-jitter-on-pulse-output-when-duty-cycle-is-not-50/)

If the Feeltech is clean I might return my unit, otherwise I suppose I might live with it *sigh*.

Thanks much.

My modified FY6600 has jitter on 50% duty cycle but not at 40%...go figure.   Mods to my unit are; upgraded clock (DJ75), replaced output caps in PS, added ceramic caps and choke to output of PS.  Added replacement opamps (THS3095).   I don't think any of these mods affects this particular problem for good or bad.   I'm guessing it has to do with hitting the duty cycle time close to the clock transition of your particular unit regardless of manufacturer.  A slight change in the duty cycle fixes it.  For instance on my FY6600 going from 50% to 48% eliminates the jitter. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 30, 2018, 05:42:42 am
I am assuming that the 5ns jitter comes from the 200MHz sample rate that the unit has.  I don't really know how DDS signal generators work, but I am assuming this 5ns is an artifact of the 200MHz base clock.
For the same reason, the 250MHz DAC in the FY6600 has 4ns. So a hair less, but pretty much the same.

My modified FY6600 has jitter on 50% duty cycle but not at 40%...go figure.
Did you per chance use the frequency calibration? If you set that different then 10000000, then your 10MHz is no longer a perfect divider and the points where jitter happen shift and are no longer predictable.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 30, 2018, 06:40:59 am

My modified FY6600 has jitter on 50% duty cycle but not at 40%...go figure.
Did you per chance use the frequency calibration? If you set that different then 10000000, then your 10MHz is no longer a perfect divider and the points where jitter happen shift and are no longer predictable.
[/quote]

Yes I did use the frequency calibration to correct for the error in my TCXO so I get a very accurate output frequency.   I think you are correct in that it will change where the jitter shift happens.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArcticGeek on March 30, 2018, 09:20:30 am
Thanks for the replies, that tells me that this issue is inherent in the design.  I guess I'll live with it on my unit.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on March 31, 2018, 04:01:25 am
Well I replaced the old stock version 3.1 chips (winbond flash and stm front panel chip) with the version 3.2 chips that my eBay seller sent via the slow boat from China and they worked like a charm. My device is now upgraded to version 3.2 and everything still works swimmingly.

If there was any doubt, this transaction has convinced me that the sellers know that all the problems are with the front panel programming. Anyway, I have an extra working 3.1 chipset that I will be sending out to Fremen67 for further analysis.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 31, 2018, 04:48:36 am
My device is now upgraded to version 3.2 and all the front panel buttons work swimmingly.
There was a problem with the buttons, that was resolved with V3.2?
Please explain further?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on March 31, 2018, 05:25:33 am
There was a problem with the buttons, that was resolved with V3.2?
Please explain further?

No sorry there was no problem with the buttons in either version, I just mentioned that because I was proud of myself for not screwing up the soldering job (first time working with SMD)

I got the seller to send me a version 3.2 chip to replace my version 3.1 chip that supposedly could lose its ability to output a sine wave under certain circumstances.

Sorry for the confusion
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on March 31, 2018, 07:04:16 am
Ah yes.

Indeed, Louis Rossman may make it seem like it's easy, but I also still think of successfully replacing a 48 pin SMD package as a an accomplishment.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 31, 2018, 07:50:41 am
Ah yes.

Indeed, Louis Rossman may make it seem like it's easy, but I also still think of successfully replacing a 48 pin SMD package as a an accomplishment.

As would I...at least with normal hobbyist equipment/experience those large fine-pitch SMD packages are a B***H.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on March 31, 2018, 07:58:55 am
Paulca, expanding on the suggestion of Cybermaus, you can get a triggered sweep for your scope by feeding a low frequency negative ramp from CH2 to the VCO terminal in back. Make sure your ramp goes from 5V to 0 V, using offset and amplitude adjustments. Set your start and stop frequencies, then use"Forth" in Sweep selection to get a forward frequency plot. Your scope can be triggered directly from the positive edge of the ramp using a second scope channel or ext trigger.

While this does work, it is cumbersome and fraught with possible errors. For more serious work with frequency response plots I suggest you get a low cost scalar network analyzer. There are plenty of low cost ones on eBay.

My FY6600 (V3.2) has quite significant variation of amplitude with frequency. While I have used the CH2 ramp to sweep, the result is approximate at best.

I thought a bit about using the FY6600 as a low-frequency network analyzer.  I have a decent network analyzer in my hacked Siglent SSA3021X  but at low frequencies, say below 1MHz it's performance isn't so great.   The SSA3021X tracking generator is not very stable at the low-end and the unit isn't even rated below 9KHz anyway.   I find myself using the FY6600 for sweeping the response from a few hertz to 10MHz for so.   It's output voltage is very stable through that range.  Only when I get above 30MHz or so the voltage drop off is significant.  Note: I have installed the THS3095 op-amps on my unit.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on March 31, 2018, 03:21:51 pm
Yes, you can use the FY6600 as a scalar network analyzer. For fun, I swept a 14 MHz BPF and got nice response on the scope. But with only the 8 bit converters in the scope and the coarse ability to read out frequency and amplitude, there is much room for error.    Low cost scalar network analyzers like the NWT70 are on eBay for around US$70. I bought this particular version (there are many NWT versions on eBay) since it covered the 50 KHz to 80 MHz range. As I remember, I got it to go down to 1 KHz. Its more accurate than using a FY6600 and has 80 dB dynamic range with on screen plots.

BTW, after several days of experimenting with my new mods on FY6600, I am very pleased with the results. The new 50 MHz oscillator D75J you recommended is excellent. My sine wave FM modulation (jitter) was over 12 Hz at 10 MHz. Now it is way below 0.1 Hz... below what my equipment can measure.  It is stable and doesn't drift. The old one took 30 minutes to stabilize (within the specs in manual). This one is ready as soon as you click on the power.. I was very lucky as my D75J was spot on 50 MHz... did not have to apply the frequency correction to FY6600.

The two replacement amplifiers are working good too. Used heat sink pads under the heatsink. Barely gets warm. I noticed that below 20 dBm output (sine) distortion is below 60 dB. It rises much more as you approach full output of 30 dBm. Noticed that the display voltages on LCD are not correct in predicting dBm. My output was off by -4.1 dB... Ran it all day yesterday on a project and it performed very well. Its now becoming one of my favorite tools. :)



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on March 31, 2018, 11:07:27 pm
Is there a summary of recommended mods (+part numbers) that could be uploaded to Der Kammi's GitHub? Also, is it possible to run the output opamps at a higher voltage (like +/- 15V) in order to avoid the distortion at high amplitude via a better power supply? Or is the high amplitude distortion baked in?

From what I understand, the timebase, the output opamps, the capacitors, and the power supply should be upgraded in various different ways. Is there something else that I have missed?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Bob Sava on March 31, 2018, 11:45:44 pm
My 30Mhz FY6600's square wave (1Vp-p, 10kHz) has a rise time of 20ns.  Would 60Mhz model have a faster rise time (I thought I saw 7ns screenshot here).

EDIT: I don't know what I did but now rise time measures 7.5ns.  Maybe there's something wrong with my scope or user error.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on April 01, 2018, 11:20:14 am
Is there a summary of recommended mods (+part numbers) that could be uploaded to Der Kammi's GitHub? Also, is it possible to run the output opamps at a higher voltage (like +/- 15V) in order to avoid the distortion at high amplitude via a better power supply? Or is the high amplitude distortion baked in?

From what I understand, the timebase, the output opamps, the capacitors, and the power supply should be upgraded in various different ways. Is there something else that I have missed?

I am still waiting for my FY6600 and I have not implemented any of the improvements yet but reading trough the discussion here and also tests elsewhere here is what I have on my list:

1. Power supply
Classical transformer 14Vx2/20VA
Linear regulators 14V DC for some output peak headroom - possibly LM317/337
DC-DC to 6V and then linear to 5V

2. Output buffer
THS3091/95
Better option would be THS3491 but not yet available - it may be worth staying with the 3002 for some time
Thermal paste and heat sink for the THS pair - the 4558 does not need help and just sticking above the other two
Transil voltage protection for the output - something around 25V, low capacitance
Diode clipping to the power supply rails - BAV99

3. Reference clock
10MHz OCXO - the cheapest I could find on ebay
Clock multiplier x5 - NB3N502
Int/ext reference switch with BNC

4. Front panel
Would be nice to have the channels LEDs yellow and blue ;-)
The rotary knob is also mentioned by several people as being shallow

5. Altera
Someone mentioned heat sinking the Altera Cyclone - we'll need to check the temperatures, especially with linear power supply and OCXO all adding heat inside.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 01, 2018, 06:03:18 pm
1. Power supply
Classical transformer 14Vx2/20VA
Linear regulators 14V DC for some output peak headroom - possibly LM317/337
Make sure the 14V has good good buffer caps, or else make the rail 12.5V instead of 14V. Because 14Vdc from 14Vac may cause some ripple if your caps are too small.
Especially since it was reported the 3095 on 11.5V already barely had clipping (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1464545/#msg1464545), so better a stable 12.5V then a ripply 14V

DC-DC to 6V and then linear to 5V
No need. That 5V is not used except to have a linear to 3.3V. So your DC-DC may as well go to 5V directly

Diode clipping to the power supply rails - BAV99
Ok, I missed that one. Why/How clip to rail with BAV99? Is that still needed if you replace the entire PSU?

Would be nice to have the channels LEDs yellow and blue ;-)
The rotary knob is also mentioned by several people as being shallow
Actually, colored LED would be a nice finishing touch. Completely not useful, but nice.
What is with the knob? I find the rotary know quite nice as is?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on April 01, 2018, 07:29:19 pm
1. Power supply
Classical transformer 14Vx2/20VA
Linear regulators 14V DC for some output peak headroom - possibly LM317/337
Make sure the 14V has good good buffer caps, or else make the rail 12.5V instead of 14V. Because 14Vdc from 14Vac may cause some ripple if your caps are too small.
Especially since it was reported the 3095 on 11.5V already barely had clipping (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1464545/#msg1464545), so better a stable 12.5V then a ripply 14V

DC-DC to 6V and then linear to 5V
No need. That 5V is not used except to have a linear to 3.3V. So your DC-DC may as well go to 5V directly

Diode clipping to the power supply rails - BAV99
Ok, I missed that one. Why/How clip to rail with BAV99? Is that still needed if you replace the entire PSU?

Would be nice to have the channels LEDs yellow and blue ;-)
The rotary knob is also mentioned by several people as being shallow
Actually, colored LED would be a nice finishing touch. Completely not useful, but nice.
What is with the knob? I find the rotary know quite nice as is?

Good point about the power supply - 12.5 to 13V seems to be the sweet spot with respect to clipping and minimal losses on the following regulators.

The 5V is regulated down to 2.5V which is the reference voltage for the offset that is superimposed on the output signal so I would rather have quiet 5V DC.

The diode clipping I mean is for protection from injection of high voltage to the output. The original implementation does not have any protection.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 01, 2018, 07:39:16 pm

What is with the knob? I find the rotary know quite nice as is?

It's because you haven't tried it with a proper knob, cybermaus.  That diddly little disc thing is ghastly compared to the real thing.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on April 01, 2018, 08:11:04 pm
On the encoder knob: I found my fingers had a tendency to slip off the thin knob because it didn't stick out far enough. Being lazy, I just pulled it out on the shaft to give me a better grip and I've had no further problems.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 01, 2018, 11:09:13 pm
Here is the v0.5 version of the blupill firmware, together with a modified version of the PC Software.

There is a new tab with calibration data. This allows to calibrate amplitude for low frequencies but more usefull, the DC Offset.
Once calibrated, the DC function becomes quite accurate. Of course it is better to do a manual calibration of offset and amplitude before doing the software calibration.
Calibration data are updated and stored after each calibration value input. They are stored at the end of the STM32 flash eeprom and loaded again on startup.
The Z output load mode is also available.

In the configuration tab you can now:
- activate/desactivate the HiZLoad mode
- modify the Load impedance value from 50 ohms to 1kOhm
- activate/desactivate the use of calibration data

As I also prepared resampled buffers of current waves in the bluepill for future LCD display, I modified the PC Software so that it could read and use those buffers to get a picture of the waves on screen. Square, CMOS, DC and AdjPulse waves pictures are calculated, the others are live resampled values. You should now be able to see on the PC the arbitrary waves that you download to the flash eeprom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 02, 2018, 07:53:38 pm
Well, bummer. I am no longer able to make it work.
Not to worry, it is bound to be me. Because I went back to v0.4 and that also does not work anymore.

So please remind me: if no PC is connected, and comms between CPU and FPGA is good, then it should start with a 10KHz squarewave right?
What I have is:
- Both LEDS turn on (red and green). If memory serves, this means initialization went OK, and there is comms between CPU and FPGA
- There is no wave output on either channel. If init is OK, why no output?
- The PC does see the CH340 driver on COM3, but the software does not see the FY6600. Not in auto, and not when I manually select COM3
- I tried all startup sequences: power first, USB first, press an extra reset later.

Any suggestions
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 02, 2018, 09:30:19 pm

- Both LEDS turn on (red and green). If memory serves, this means initialization went OK, and there is comms between CPU and FPGA
Any suggestions
Red LED is ON by default when powering the bluepill. When Hardware initialization is done, I switch it OFF as soon as I recover control from the initialization routines.
If it stays ON, that means it is stucked during initialization or the bluepill may also be empty or corrupted.
I would first check the large ribbon connection and especially the FPGA Ready wire. Then I would also compare the bluepill program against hex file.
Otherwise, any backup bluepill?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 03, 2018, 02:30:12 am
Nice work, fremen!  The calibration feature works well for DC, and offsets on mine are now within 5mV instead of 150mV.  Sine and square waves are also tightened up so that the two traces are now almost coincident, although the amplitudes don't change very much whether calibration data is switched on or off.  However, I didn't test over a range of frequencies, and certainly not much below 1MHz, so I probably shouldn't have expected to see much change anyway.  I'll do a more thorough test tomorrow.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 03, 2018, 11:36:02 am
However, I didn't test over a range of frequencies, and certainly not much below 1MHz, so I probably shouldn't have expected to see much change anyway.  I'll do a more thorough test tomorrow.
This is only static calibration. For dynamic response modification, a filter in the FPGA might be the solution...
For offset calibration, we can compensate unbalanced -12v and +12v power rail for each range. For amplitude, we can only compensate the gain so that Vpp is calibrated but +Vtop and -Vtop could still be unbalanced.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 03, 2018, 03:59:32 pm
Welcome back Fremen,

I did end up adding a heatsink to the Fpga ,was one I got off an old computer board of some kind I think, about 30mmsq
I didnt bother doing any precise measurements on it ,but it seems from touch at least that now the chip sits between 5 and 10 C cooler ,
Either way its probably still even without it, opperating quite safely tempreture wise ,but shifting a little extra heat is always a good thing anyway . Ill pop the thermo couple onto it at some point later in any case ,just for reference purposes .

After re-seating the heatsink on the main outputs and leveling it with 2 layers of thermally conductive (grey) pad over each 3095 its definately running a bit warmer than before with the single op amp ,probably two reasons for this ,one the 2x3095 draw a bit more current than the single 30021, and two as the original contact between the op amp and the heatsink was marginal at best and it just wasnt removing heat as effectively as it should have been. Of course the amount of heat is proportional to output level too . As I said above I will get some figures for temp vs output drive very soon also.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 03, 2018, 11:16:58 pm
Well after about an hour and ten minutes the FPGA temp stabilised,
Ambient was 19.2c to begin with
So with a 30x30x8mm south bridge type heatsink ,with the lid placed on top loosely,but not clicked in , it leveled out at approx 41.5C
Ktype thermo couple was placed in the centre of the heatsink .
Be interesting if someone could check what temp was reached without FPGA heatsink ,but under similar conditions in other respects,just for comparative purposes.

I might try another similar test tomorrow involving the output stage heatsink ,maybe at 5,10 and 15 volts into 50 ohm load termination.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 04, 2018, 01:46:23 am
Hi soundtec - I could have given you that temperature reading if I'd seen your message a bit earlier, but mine is switched off and cooled down now.  I'll check it tomorrow when I have it on again.  It's worth noting, though, that the rated temperature for the Cyclone IV is 125degC, and I don't think it's going to be anywhere near that (maybe 50C max?).  I did measure the other heat sink's temperature when I did the 3095s and I think it was only around 35C after a heavy session, but for interest's sake I'll check that again too.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 04, 2018, 11:36:23 am
Cheers Dave,
Well within spec so at 40-50C , as I said I didnt go to any extra trouble or expense with the FPGA heatsink ,it was just something I had lying around. I cant help thinking slightly better airflow in the case itself might make things more stable or improve the settling time ,
at any rate not worth hacking up the case and making it look like a dogs dinner over it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on April 04, 2018, 04:27:17 pm
FeelTech announced a little contest for a few pre-release FY6800 units. https://www.eevblog.com/forum/contests/feeltech-fy6800-signal-generator-free-trial/ (https://www.eevblog.com/forum/contests/feeltech-fy6800-signal-generator-free-trial/)

I suggested that they get in touch with you hard working folks to get you units regardless.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 04, 2018, 07:11:33 pm
I am in dire need of a new/better LA

Trying to figure out why it is not working anymore. It is weird, because the BP was never disconnected from the loom, so there is not much chance of me making a mistake with it.
Tried a new BP, and soldered it to a veroboard for better signal and connection quality, and same result. Both BP have the red LED stay on, and both BP nicely run the standard "blink" program from STM32

Using my LA at max 20MHz I am not able to decode what is happening, because the SPI is also at 20Mhz. Ergo, I need a LA of at least 40MHz, better 80MHz
Using my Scope, I was able to see that the SPI signals themselves are pretty clean and well defined, but with the startup delay and limited scope trace, I am not really seeing what is happening (good thing I never paid for the decoding, it is not so very useful)

So:
- Any chance Fremen you can, without too much effort, make a custom 5Mhz clocked version?
- Anyone has advice on what LA? Spec-wise I like the ScanaQuad SQ100, but its a bit pricey and I'd maybe like 8 instead of 4 channels.
  (maybe I should go and search a different thread for that, but here I am anyway)


PS: CHecked and re-checked, so pretty sure about the wiring. But if anyone wants to look, see pictures.
ALso, I keept the veroboard a little larger, so I can add buttons in the future...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on April 04, 2018, 07:13:55 pm
@cybermaus: did you try with the original panel, is it working ?
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 04, 2018, 07:22:12 pm
Yes, still working, even now. (thank god. or invisible pink unicorn. whatever)

When I say I never disconnected the loom from the BP, I mean exactly that. I was of course disconnected from the AWG
But as I had made custom 8 and 4 pin male headers, reconnecting is pretty certain. Even more so now with the vero
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: 2N3055 on April 04, 2018, 07:47:42 pm
@cybermouse,
Avoid ScanaQuad.. ScanaStudio is hipstery crap (they threw away old software that actually worked, and went to make a new software from the scratch. After almost 3 years they are at roughly 25 % of done)
I was early adopter because it held promise.. If they ever manage to make software to be full featured, maybe then...
4 Ch is good only for serial protocols.. It doesn't support segmented capture and compression..  So very short capture...

DSLogic is much better buy for the money...

Regards,

Sinisa


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 04, 2018, 07:50:32 pm
Hi soundtec,

I ran mine for an hour with both channels feeding a 15v, 1Mhz sine wave into 50 ohms, lid 90% on, and the temperatures I got were - Cyclone 46C, op amp heat sink 50.5C.  Half an hour later the Cyclone was still 46C and the heat sink was 52.8C, so your FPGA cooler looks like a "belt, braces, old tie, and a piece of string" job :).  Nothing wrong with that, as it hasn't cost anything.  I also gave them both the finger tip test, and the Cyclone didn't even feel warm, while the output heat sink was only moderately warm, despite the measured temperature.  Presumably the heat flow is so small that a finger tip immediately absorbs what's available and cools the surface of the chip / heat sink to body temperature, so that there's no apparent difference after the first second or two?  (But now we digress into thermodynamics ...)

Your results of the other output tests will be interesting, especially as mine will be used mostly for radio testing and calibration, when I'll only be using a 0.5v signal fed though an 80dB attenuator - so hardly stressing the op amps at all.

If you want better airflow in the case I think it will have to be either a 30mm fan on the back panel, sucking out, or some holes near the front edge of the lid to allow natural venting (maybe coupled with opening up some of the baffles on the sides, which could be done invisibly).  I still might drill a couple of holes over the LM317 on the 5v module, as it's the only component which really generates any amount of heat in mine, but even that only makes a localised warm spot on the lid and is probably nothing to fret over.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 04, 2018, 08:14:17 pm
cybermaus - how many ST-Link dongles have you tried?  I have very little faith in these cheap Chinese affairs as I've now bought six of the things: one died quickly, and only one of the other five will actually program the blue pills, so they're obviously not to be relied upon.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 04, 2018, 08:23:21 pm
Maybe the bluepill board is defective Cybermaus.

So the Fy6800 has appeared ,it does seem like Feeltech were keeping an eye on our suggestions all along ,new rubberised Keypad,proper safety earth and it seems , user upgradeable firmware.
I dived in on the competition entry as well ,
Definately worth your while getting in too ,Cyber, DC1,Fremen you guys have done a lot of the leg work on this project.

Thanks for that Dave, interesting result ,the 5 degrees I guess doesnt make much odds either way ,but it wont do any harm either .
Valve music and sound electronics is my game so fans are a big no no for me ,I might consider slotting the recesses on the top panel alright ,with care it should be possible to do it neatly enough . Probably worth your while getting in on the competition too Dave ,very little to loose in any case ,I did add a proviso to the end of my competition entry that the info contained herein wasnt to be given out to third parties for marketing purposes ,finally the world is waking up to data protection and privacy online .Thats interesting radio is your game ,I junked an old microwave oven lately and was thinking about the big transformers contained in them ,and if it would be possible to re-use them as heater and HT transformers for a valve powered transmitter ,the HT would come out at around 3kv from a regular microwave transformer and its possible to rewind them for Lt heater usage quite easily ,an old pc case would work fine as an enclosure ,kinda like a diy preppers valve transmitter made from easily available garbage pile stuff ,just on the off chance the entire global communications network and the internet goes tits up , ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 04, 2018, 09:28:29 pm
I have 3. One China, and 2 more integrated into official distributor bought real ST brand  STM32F0 discovery boards.

As stated, both Bluepills behave the same, both can be programmed to a simple "blink" program and work, both can be programmed to fremen's and then read back to compare without issue. One Bluepill was brand new out of silver anti-static wrapper. So I have very little doubt about the BluePill or STLink themselves.
Nevertheless, I tried once more using the STM32F0 integrated STLink, just to read back. Program verified without problem, was thus properly programmed with the China STLink, and anyway after reprogramming I had same result.

Well, almost same: When connecting both 4 and 8 pin result is the same.
But doing this, I discovered that if I only connect power (4 pin header) and not the 8 pin header, the LED does turn off, it does get past initialization.
Added my pull-up resistor again, but still not work. Something is unstable on that SPI bus when connected.

It may be because I have slightly older hardware. I need to properly spy that bus.
I'd go for the DSLogic, but that comes from china, I do not want to wait 3 weeks. I'll look for something closer by.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on April 04, 2018, 10:53:42 pm
I'd go for the DSLogic, but that comes from china, I do not want to wait 3 weeks. I'll look for something closer by.
On ebay there's two Chinese sellers with German warehousing and one seller in the UK.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 05, 2018, 06:19:54 am
Sellers on eBay and AliBaba that claim to be in UK or Germany are lying.
I know people do actually exist in UK and Germany, but only a few million, and there is like a few billion people in China, so statistically above statement is true.

Also, I noticed the eBay sellers do not include the special coax-probes, but just the straight lead probes.


Edit: More seriously, this one  (https://www.ebay.de/itm/263582405421)does seem to be in Germany, judging by his claim it will be here Monday and also his offer to drive by and pick it up yourself.  Probably be a "clone" though, judging by the non-coax probes. But I am traveling for work next week, so no need to order that now, I't arrive exactly as I leave.

Edit2: Even found a "Dutch" seller (http://"Dutch" seller). But: 15 days, so drop-shipper. In fact it says so in the header as if its a good thing: "delivery straight from manufacturer". Why would I pay you €106 instead of $70 (https://www.ebay.com/itm/182242758729) if you have no stock and no handling to add value?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on April 05, 2018, 06:28:09 am
I have 3. One China, and 2 more integrated into official distributor bought real ST brand  STM32F0 discovery boards.

As stated, both Bluepills behave the same, both can be programmed to a simple "blink" program and work, both can be programmed to fremen's and then read back to compare without issue. One Bluepill was brand new out of silver anti-static wrapper. So I have very little doubt about the BluePill or STLink themselves.
Nevertheless, I tried once more using the STM32F0 integrated STLink, just to read back. Program verified without problem, was thus properly programmed with the China STLink, and anyway after reprogramming I had same result.

Well, almost same: When connecting both 4 and 8 pin result is the same.
But doing this, I discovered that if I only connect power (4 pin header) and not the 8 pin header, the LED does turn off, it does get past initialization.
Added my pull-up resistor again, but still not work. Something is unstable on that SPI bus when connected.

It may be because I have slightly older hardware. I need to properly spy that bus.
I'd go for the DSLogic, but that comes from china, I do not want to wait 3 weeks. I'll look for something closer by.

I wanted to modify a Zeroplus LAP-C 16032, like in the famous thread on EEVBlog,  had to use that useless STTC-5xx serias tip for something, the seller wants 70EUR for it:
https://www.ebay-kleinanzeigen.de/s-anzeige/zeroplus-lap-c-16032-16-kanal-logic-analyzer-wie-neu/836656943-168-7434 (https://www.ebay-kleinanzeigen.de/s-anzeige/zeroplus-lap-c-16032-16-kanal-logic-analyzer-wie-neu/836656943-168-7434)

Too bad he didn't accept 50, but maybe you want to give it a try.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 05, 2018, 09:55:53 am
I am in dire need of a new/better LA

Trying to figure out why it is not working anymore. It is weird, because the BP was never disconnected from the loom, so there is not much chance of me making a mistake with it.
Tried a new BP, and soldered it to a veroboard for better signal and connection quality, and same result. Both BP have the red LED stay on, and both BP nicely run the standard "blink" program from STM32

Using my LA at max 20MHz I am not able to decode what is happening, because the SPI is also at 20Mhz. Ergo, I need a LA of at least 40MHz, better 80MHz
Using my Scope, I was able to see that the SPI signals themselves are pretty clean and well defined, but with the startup delay and limited scope trace, I am not really seeing what is happening (good thing I never paid for the decoding, it is not so very useful)

So:
- Any chance Fremen you can, without too much effort, make a custom 5Mhz clocked version?
- Anyone has advice on what LA? Spec-wise I like the ScanaQuad SQ100, but its a bit pricey and I'd maybe like 8 instead of 4 channels.
  (maybe I should go and search a different thread for that, but here I am anyway)


PS: CHecked and re-checked, so pretty sure about the wiring. But if anyone wants to look, see pictures.
ALso, I keept the veroboard a little larger, so I can add buttons in the future...
There are lot of chances that it does not come from your bluepill board.

First test:  Just plug the 4 wires ribbon and you  should be able to talk to the board via PC Software.
If it works, second test: plug the two ribbons, except the /FPA Ready pin (you may have to de-solder one wire now with your vero board...). If it works then it comes from a different timing of this signal for whatever reason.. I could just release a FW version that continues init after a time-out. If it does not work than it might come from SPI init. I should have a look at how to recover from this one.
Depending on the results of those 2 tests, I could provide you with a special version with a lower speed SPI.

I will anyway add some diagnostic information in the next FW/PC Software release that could also help (provided that the serial link works with the 4 wires ribbon of course)

Regarding the LA, I would recommend the DsLogic Pro. I am very happy with it. Even the Basic version (like the one you mentioned in Germany) would allow live streaming @ 50Mhz and you could also upgrade it later on by adding a memory chip (when you feel confortable with SMD soldering...).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 05, 2018, 10:22:13 am
Back to the THS3095 topic.

My cheap Chinese "he promised they were genuine (https://www.ebay.com/itm/292350281588)" THS3095 arrived and it was but a moments work to solder them in.
WOW, what a difference that made! I guess they are genuine. Or as good as.

Picture one: Yellow is 20Vpp into 50 Ohm with THS3095
Blue is reference waveform10Vpp into High-Z. You do not even see the blue because they are so equal.

To compare, The one from a few weeks ago, 20Vpp into 50 Ohm with THS3002
Do I need to say more?

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on April 05, 2018, 11:01:38 am
Sellers on eBay and AliBaba that claim to be in UK or Germany are lying.
I know people do actually exist in UK and Germany, but only a few million, and there is like a few billion people in China, so statistically above statement is true.

I bought my FY6600 on ebay and it arrived within a week from a Chinese seller warehousing in Frankfurt and without custom headaches. I'm sure he doesn't live in Frankfurt, but he warehouses there.

Quote
Also, I noticed the eBay sellers do not include the special coax-probes, but just the straight lead probe

Them's the breaks. Don't see what coax probes are going to do on high impedance inputs any way. Proper high speed logic analyzers use attenuation probes which are terminated on the side of the analyzer pod. That's still the domain of more expensive devices though. If you want to you can twist two leads together and it accomplishes as much as that coax does AFAICS. Which is to say, bugger all.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on April 05, 2018, 11:02:37 am
Picture one: Yellow is 20Vpp into 50 Ohm with THS3095
Blue is reference waveform10Vpp into High-Z. You do not even see the blue because they are so equal.
Can you tell something about the reference waveform? Second channel into High-Z or what?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 05, 2018, 11:16:23 am
Yes indeed, just the B channel set to half the amplitude, and no 50 Ohm T at the oscilloscope.
Because there is no load, there is no trouble driving it for the OpAmp

I do not own a Spectrum Analyser, nor an actual reference, so this is the best I can do. So you may still start talking about -dB's and such, but just eyeballing the 3002 into 50 Ohm is so bad I do not need a SA or reference anyway.

And in any case, whatever error there is that I cannot see by eye, at least now the 50 Ohm is as good/bad as the High-Z, they overlap exactly.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on April 05, 2018, 03:57:50 pm
1. Power supply
Classical transformer 14Vx2/20VA
Linear regulators 14V DC for some output peak headroom - possibly LM317/337
Make sure the 14V has good good buffer caps, or else make the rail 12.5V instead of 14V. Because 14Vdc from 14Vac may cause some ripple if your caps are too small.
Especially since it was reported the 3095 on 11.5V already barely had clipping (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1464545/#msg1464545), so better a stable 12.5V then a ripply 14V

DC-DC to 6V and then linear to 5V
No need. That 5V is not used except to have a linear to 3.3V. So your DC-DC may as well go to 5V directly

Diode clipping to the power supply rails - BAV99
Ok, I missed that one. Why/How clip to rail with BAV99? Is that still needed if you replace the entire PSU?

So I have bought a Mean Well RD-3513 (https://www.mouser.com/ProductDetail/709-RD3513) switch mode power supply with +/- 13.5V (tunable from 11.5V to 14V) output to replace the current power supply in the unit.  I'm assuming that removes the need for any transformers or associated regulators in the linear power supply solution quoted above.  If I use a lossy ferrite (any advice on the ferrite resistance?), in yall's estimation will there be any need for additional filtering to remove the switchmode noise besides the ferrite?  Will any other components besides the ferrite & new power supply be needed to power the dual THS3095 output op amps, other than a grounding cable to reference the BNC ground to mains earth?

Finally, are the THS3095's just a drop in replacement for the single output op amp or am I going to need to solder in additional components around them?

The upgrades that I will be performing will include swapping out the power supply, adding in a ferrite to suppress switchmode noise, swapping out the output op amps, grounding the BNC outputs, and installing a new TXCO reference (I went with the D75J (https://www.digikey.com/products/en?keywords=CW657CT-ND)).

Kammi, If this all goes as well as I hope it will, I will upload detailed step by step instructions to the github under the mods section with your permission.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on April 05, 2018, 06:25:55 pm
Will any other components besides the ferrite & new power supply be needed to power the dual THS3095 output op amps, other than a grounding cable to reference the BNC ground to mains earth?
There is no need for a new psu for the THS3095s. A linear psu would prevent the ghost voltage to earth ground and keeps the outputs floating. Your reason for the new smpsu is because of the higher voltage? I replaced the smpsu with a self made linear one with 5V and +/-12V and do not have any problems with 20Vpp output on 50Ohm termination.

Will the mean well fit inside the housing?

Finally, are the THS3095's just a drop in replacement for the single output op amp or am I going to need to solder in additional components around them?
No additional components needed, just a replacement. I attach a picture.

...and installing a new TXCO reference
Soldering the TXCO modul is something you need patience for. I placed kapton tape on the bottom side of the module so that all the not needed pads were covered.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on April 05, 2018, 07:00:21 pm
Thanks, I needed the higher voltage supply to help handle the waveform clipping problem in the output. I just realized that I will need to put a 5V regulator after the 12v output in order to supply the necessary 5v for the rest of the board.  Any suggestions for how I should manage that?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on April 05, 2018, 07:58:31 pm
For this you should take a step down converter that is capable of >1A not a 5V regulator like the 7805. On the 5V rail there is up to 1A needed. Using a 7805 it would need to dissipate (14V - 5V) * 1A = 9V * 1A = 9W! You get step down converters very cheap as ready to use modules. With a small heatsink the XL4015E1 (see picture) would be a good choice. It is capable of up to 5A. This module is only about 5cm x 2,5 cm x 2,5cm.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on April 05, 2018, 07:59:33 pm
Thanks, I needed the higher voltage supply to help handle the waveform clipping problem in the output. I just realized that I will need to put a 5V regulator after the 12v output in order to supply the necessary 5v for the rest of the board.  Any suggestions for how I should manage that?

Personally, one these days I'll do the modifications with the nice 5EUR transformer and 3 linear regulators, plus 2 rectifier bridges and a 6 capacitors, but if you went on the SMPS way, then grab any Aliexpress/fleabay little 5V board and addit there, I think the smallest one was 2x3cm.

https://www.ebay.de/itm/12V-Step-Down-Modul-5V-3A-Konverter-Adapter-Power-Regler-Spannungswandler-MA1391/162762631499 (https://www.ebay.de/itm/12V-Step-Down-Modul-5V-3A-Konverter-Adapter-Power-Regler-Spannungswandler-MA1391/162762631499)
https://www.ebay.de/itm/Micro-UBEC-5s-Lipo-23V-to-5V-6V-12V-Spannungswandler-Mini-FPV-BEC-5g/152707206751 (https://www.ebay.de/itm/Micro-UBEC-5s-Lipo-23V-to-5V-6V-12V-Spannungswandler-Mini-FPV-BEC-5g/152707206751)

My favorite trafo:
https://www.ebay.de/itm/Netztransformator-230V-8V-1-7A-4-2V-0-15A-13-6Volt-2x0-6A-Mittenanzapfung-NEU/152934971288 (https://www.ebay.de/itm/Netztransformator-230V-8V-1-7A-4-2V-0-15A-13-6Volt-2x0-6A-Mittenanzapfung-NEU/152934971288)

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 05, 2018, 08:22:48 pm
First test:  Just plug the 4 wires ribbon and you  should be able to talk to the board via PC Software.
confirmed: both the vero-PB and the loom-BP connect to PC software if only the 4-pin is connected.
btw: unlike what was stated before, it is the green LED that turns off after init.

If it works, second test: plug the two ribbons, except the /FPA Ready pin (you may have to de-solder one wire now with your vero board...). If it works then it comes from a different timing of this signal for whatever reason.. I could just release a FW version that continues init after a time-out. If it does not work than it might come from SPI init. I should have a look at how to recover from this one.
Both the vero-BP and the loom-BP do not work if I disconnect the /FPGARDY signal.

For added info, I attach a scope view of the SPI bus signals. Not sure if it helps in any way.
The first 2 are that I captured between BP and FPGA. The last 2 between FP and FPGA. While there are some overshoots on vertical edges, there is no noise, and there is a good clear difference between 0 and 1.

When BP is connected, these signals are shown over and over again. Hence the they are captured in RUN and nicely bright. My guess is the BP is trying to get the FPGA to say something, but it stays silent.
When FP is connected, the SPI is pretty much silent. I have to press a button to capture some bytes. Hence captured in SINGLE.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 05, 2018, 08:42:36 pm
@cybermaus: any luck with the bluepill now?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 05, 2018, 09:11:23 pm
You may have missed the message just above yours.
Forgot to press refresh I guess.

Also, I ordered the DSLogic. From original website. No mention of delivery times, so likely 2 weeks minimum. But I am gone all next week anyway.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on April 05, 2018, 09:27:28 pm
For this you should take a step down converter that is capable of >1A not a 5V regulator like the 7805. On the 5V rail there is up to 1A needed. Using a 7805 it would need to dissipate (14V - 5V) * 1A = 9V * 1A = 9W! You get step down converters very cheap as ready to use modules. With a small heatsink the XL4015E1 (see picture) would be a good choice. It is capable of up to 5A. This module is only about 5cm x 2,5 cm x 2,5cm.

On the list of DC-DC step-downs, here is what I got just yesterday (so I haven't tested them yet, EDIT: see below), but I had/have a somewhat similar need, though less critical on the noise - just need to get an aux voltage from 55V DC down to run a small fan. And a LED or two, a must have even with no real need/purpose, of course. If these work as advertised, certainly nice and tiny (just about 25.5mm x 16.5mm, looked so "big" in the photos, but in real life, smaller than the end of my thumb... and it is not even the smallest model I've found :P).
https://www.ebay.co.uk/itm/DC-DC-Buck-Step-Down-Converter-48v-36v-24v-18v-12v-9v-to-3-3v-5v-2A-Power-Supply/252932129152 (https://www.ebay.co.uk/itm/DC-DC-Buck-Step-Down-Converter-48v-36v-24v-18v-12v-9v-to-3-3v-5v-2A-Power-Supply/252932129152)
(May need to search a bit to find the same in other ebays, but IIRC, I first found that (or look-a-like) in the US-site.)

EDIT: checked it before powering up and the circuit seems to have some "why, oh why" -stuff:
Assuming the IC works as a real MP4560DN as it claims to be.  The chip's EN pin has been connected to the midpoint between board's edge EN--100k--*--39k--0V, and seller's instructions claim that the EN (at board edge) can be tied to the Vin (upto 55V) to enable output. Well, at 55V in, the midpoint would be at about 15.7V and datasheet says absolute max for EN pin is 5V. Uhoh.
Leaving the board's EN connection floating makes the midpoint pulled down, thus disabling the IC. (1µA pull down from EN-pin's internally driven 3.0V is enough, and the 39k certainly pulls plenty more). The worst thing is, it would have been easier to just bring the EN pin to board edge as is, and let the user pull it down for disable, instead now needing to drive it high (to a voltage between about 6V and 15V) to enable.
I guess I'll just remove the 39k resistor, which will make the EN pin "floating" and thus the IC by default enabled. Desoldering tiny SMD resistors, bleeeh...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Marco on April 05, 2018, 09:38:18 pm
Also, I noticed the eBay sellers do not include the special coax-probes, but just the straight lead probes.
Are there any sellers which advertise the Plus with coaxial leads? I've seen reviews of it, but all the pictures of the Plus on say aliexpress have 4+1 flying leads for each connector. The images for the plus on the Sigrok site do too. (And for some reason the DreamSourceLab website doesn't mention the plus at all.)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 05, 2018, 09:51:18 pm
You may have missed the message just above yours.
Forgot to press refresh I guess.
Oups! I was still on page 47 ... :-DD

Also, I ordered the DSLogic. From original website. No mention of delivery times, so likely 2 weeks minimum. But I am gone all next week anyway.
Nice choice.. plus,  should it happen, I would be able to read and analyze your BP captures  ;)


First test:  Just plug the 4 wires ribbon and you  should be able to talk to the board via PC Software.
confirmed: both the vero-PB and the loom-BP connect to PC software if only the 4-pin is connected.
btw: unlike what was stated before, it is the green LED that turns off after init.

If it works, second test: plug the two ribbons, except the /FPA Ready pin (you may have to de-solder one wire now with your vero board...). If it works then it comes from a different timing of this signal for whatever reason.. I could just release a FW version that continues init after a time-out. If it does not work than it might come from SPI init. I should have a look at how to recover from this one.
Both the vero-BP and the loom-BP do not work if I disconnect the /FPGARDY signal.

For added info, I attach a scope view of the SPI bus signals. Not sure if it helps in any way.
The first 2 are that I captured between BP and FPGA. The last 2 between FP and FPGA. While there are some overshoots on vertical edges, there is no noise, and there is a good clear difference between 0 and 1.

When BP is connected, these signals are shown over and over again. Hence the they are captured in RUN and nicely bright. My guess is the BP is trying to get the FPGA to say something, but it stays silent.
When FP is connected, the SPI is pretty much silent. I have to press a button to capture some bytes. Hence captured in SINGLE.

OK. I think I got it. In fact it should be stucked during flash read tests. As I already added a 2s time-out during FPGA init, it should have failed to initialize the FPGA, went on after 2 sec and jumped to flash eeprom selftest. The FPGA not beeing initialized, it can't answer to flash read requests. That would explain what you see on the scope.
So I have to:
- add time-out to FPGA requests anyway
- skip flash read tests when failling to initialize FPGA
- Add more diagnostic data to startup phase.
I did not spend a lot of of energy in startup sequence diag but I will do it now.

Still it does not explain why the FPGA could not be initialized...
Now the LA would have been indeed handy.

Did you already tried to flash your eeprom with v3.2 ?
Could be interresting to see if it's related to v3.1

Edit: There should be something else . If the FPGA is not initialized at all, it can't block the startup sequence (the case when only connecting the 4 wires ribbon...)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on April 05, 2018, 11:19:19 pm
My favorite trafo:
https://www.ebay.de/itm/Netztransformator-230V-8V-1-7A-4-2V-0-15A-13-6Volt-2x0-6A-Mittenanzapfung-NEU/152934971288 (https://www.ebay.de/itm/Netztransformator-230V-8V-1-7A-4-2V-0-15A-13-6Volt-2x0-6A-Mittenanzapfung-NEU/152934971288)
With 6cm x 5,8cm x 5cm it will be a challenge to fit this beast in the housing. I decided to use two small trafos and it works fine. I added a fan. All parts running well inside their thermal specs and I used standard 7805, 7812 and 7912.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 06, 2018, 12:47:17 am
That's a nice, neat job there, Candid.  I had something similar in mind before I did mine a few weeks ago, but I couldn't find the right transformers or decide whether to go for 12v or 15v outputs.  In the end I went for variable outputs to cover all eventualities (including using the whole power supply for another project).  Do you think the fan is really needed , or have you just fitted it for "insurance"?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Insatman on April 06, 2018, 07:16:20 am
Nice work Candid...clean prototype construction.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 06, 2018, 07:53:19 am
Back to the THS3095 topic.

My cheap Chinese "he promised they were genuine (https://www.ebay.com/itm/292350281588)" THS3095 arrived and it was but a moments work to solder them in.
WOW, what a difference that made! I guess they are genuine. Or as good as.

I guess I caused some extra sales:
(https://i.imgur.com/EBq3RE4.jpg)

I hope they will not burn up after a few days, and people blame me.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on April 06, 2018, 08:09:57 am
Do you think the fan is really needed , or have you just fitted it for "insurance"?
The fan is not a must it's more for insurance. Without it the housing is getting warm but not hot and I did not do much measurement over longer time without the fan. With the fan I get about 32°C air temperature at 21°C room temperature directly at the fan after hours with both channels on at 20Vpp / 20MHz / sine. All the components stay inside their temperature specs. The bridge rectifier I used ist not the best for this scenario but I had them in stock. It stays under 50°C and so I don't care.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: texaspyro on April 06, 2018, 08:46:35 am
I hope they will not burn up after a few days, and people blame me.

It wouldn't matter... we already blame you for all the world's woes...    :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 06, 2018, 06:11:22 pm

For added info, I attach a scope view of the SPI bus signals. Not sure if it helps in any way.
The first 2 are that I captured between BP and FPGA. The last 2 between FP and FPGA. While there are some overshoots on vertical edges, there is no noise, and there is a good clear difference between 0 and 1.

When BP is connected, these signals are shown over and over again. Hence the they are captured in RUN and nicely bright. My guess is the BP is trying to get the FPGA to say something, but it stays silent.
I think I got it. Having a closer look at the scope views, yellow beeing the clock, purple MOSI and blue MISO, the FPGA is answering.
The first picture should be Reg18 request (Flash operation status request) and picture 2 the second part of the answer (LSW) with "1" that is pending operation. There should be another SPI transmission in between with "0" as answer (MSW).
As there is no time-out for flash read, it is stucked when FPGA keep answering "1"
You could confirm by connecting also Regsel as fourth signal and trigger on falling edge of RegSel. You should then see the 3 transactions: picture 1, a missing picture and then picture 2.

I will add a time-out on flash read so it can't get stucked and then we will see what happens after.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 06, 2018, 06:47:13 pm
Ok, many thanks, however I also reached some progress:

With your v0.5 on the BP, I have flashed the Winbond from 3.1 to 3.2, and suddenly both vero-BP and loom-BP worked.
I flashed back to Winbond 3.1, and they both stopped working.
I next flashed your V0.4 onto BP and it still was not working
And I ended again with your V0.5 with Winbond 3.2, and it is working again.

In other words, it is working. But also, why was the combination of V0.4 and V3.1 working a few weeks ago, and not now?
It must be a hair trigger difference somewhere in the timing. Better weather? I did move my desk to the other side of the room.

So, if you feel you still want me to do these test with V0.5 and V3.1 combination, so that we may use my "on the edge instable" setup to improve general stability, then please say so and I will do them.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 06, 2018, 07:35:59 pm
Ok, many thanks, however I also reached some progress:

With your v0.5 on the BP, I have flashed the Winbond from 3.1 to 3.2, and suddenly both vero-BP and loom-BP worked.
I flashed back to Winbond 3.1, and they both stopped working.
I next flashed your V0.4 onto BP and it still was not working
And I ended again with your V0.5 with Winbond 3.2, and it is working again.

In other words, it is working. But also, why was the combination of V0.4 and V3.1 working a few weeks ago, and not now?
It must be a hair trigger difference somewhere in the timing. Better weather? I did move my desk to the other side of the room.

So, if you feel you still want me to do these test with V0.5 and V3.1 combination, so that we may use my "on the edge instable" setup to improve general stability, then please say so and I will do them.
That's good news. So it may rather be related to v3.1 than to your system.
For the moment beeing I would prefer finishing the sweep functions as it is almost done and I will improve startup diag and flash functions later on as you are not stucked.
Did you use the v3.1 that you already posted (to go back from v3.2 to v3.1)or was is a recent backup (corrupted eeprom...)?
This will be easier for me to test things with one on my FY6600 downgraded to v3.1. That would be interresting if I could reproduce the problem later on. So if it is a different backup than the one you posted, I would be interrested in having it.

If you have some time, I would appreciate when you can test the last modifications (calibration and ZLoad mode) on your system.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 06, 2018, 08:07:25 pm
Did you use the v3.1 that you already posted (to go back from v3.2 to v3.1)or was is a recent backup (corrupted eeprom...)?
Went back to November backup. I realized the corruption might be the case, so I did save the current 3.1 before I did the other things.
When comparing though, the only differences are in the custom waveforms.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: TechieTX on April 07, 2018, 06:37:31 pm
Does anyone know offhand if the parts in the pic have the PowerPAD on the bottom?  The seller doesn't know, but at $2.85 each it's a deal either way when Mouser and DigiKey are quoting 9 bucks or more.

(https://i.imgur.com/EhoiKYq.jpg)

Given a choice, I'd rather have the ones with the PowerPAD; I can deal with 2 tiny pieces of Kapton on the FY6600 upgrade.  A quick check at TI shows the '3491 is only sampling in VQFN, and none of the vendors (including TI) are showing stock on SO-8 yet.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 07, 2018, 07:38:58 pm
Yes, powerpad

or at least, I assume this is the same seller as I used, or at least they are using the exact same specific picture, and mine came with powerpad.
Note however the picture shows 3095 57C TATD G4, but the ones delivered are 3095 42T CBZK G4

Indeed, I put two small bits of kapton below it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 07, 2018, 08:13:49 pm
I got out my machine gun and added some ventilation holes along the edges of the top panel ,just to get slightly better airflow over the the electronics , I measured around 27.7C air temp on the signal board side of my unit and around 32C near the psu, I noticed that the mains rectifier of the Switcher psu unit generates the majority of the heat from the power supply area , its easily detecable as a hot spot underneath .
Maybe a packaged bridge instead of individual diodes might be a good plan for longevity as all that heat getting conducted through to the first filter cap cant play out well for for its lifespan.

I tried the new version software via usb ,there seems to be some kind of issue for me with it, its kinda slow to load the UI and tends to lock up , anyway no big deal about that for the moment ,Im still waiting on the blue pill board and st link .I did get one cp2102 type programer ,is that any good for connecting to the fy signal board ? just tx rx and ground .

It seems to me a higher voltage op amp supply is probably a good thing .The extra headroom would for instance allow you output  20 volts while dialing in a dc offset without any clipping ,where with a 2x11.5 volt supply the moment you dialed in any offset at 20pp the signal was clipped ,some manufacturers run op amps at +/-18 volts although I saw +/-15 was the limit for the 3095 type.I would imagine the extra volts would play out well for THD figures at the higher output voltage settings in any case
So the 12 volt rails are in turn passed through two linear regulators to supply the OPA686N's ,how will these cope with having to loose the extra volts ,better heatsinking might be needed on the 7805 7905 ,the 16 volt caps on the signal board will need uprating to 25volts . So if we made the supply voltage +/-16.5 we'd get the abillity to set in a 5 volt offset on top of our 20 volts output and at the end of the day be able to swing 30 volts at the outputs .Seems like a worthwhile plan if you've already gone to the trouble of installing the 3095's and linear supplies .

Nice work Candid ,the seperate transformers for analog and digital rails looks like a good plan with maximum attenuation of any unwanted interactions and much quieter supply for the op amps than the standard switchmode unit.

powerpad ,Mine had the heat sinking on the underside of the 3095's, I just went ahead and soldered them on ,no kapton tape ,i think there is a small gap between the board and the chip normally ,but no problems so far in any case without extra insulation added.
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 07, 2018, 08:19:03 pm
If you have some time, I would appreciate when you can test the last modifications (calibration and ZLoad mode) on your system.

Oh, I forgot to respond: I did do the calibration and Z-mode yesterday.
Very nice, that low .1Hz nearly DC routine to calibrate using multimeter. Very nice and simple.


After calibration, when I next checked by putting out a 50Hz 1.41Vpp and 14.1Vpp sine on a TrueRMS multimeter, the voltages were slightly off, but better then before. From memory, I think the DDM gave 0.498 and 4.89Vrms, but I lost the piece of paper I wrote it down on. I think being within 2.5% is good enough for a device like this.


But still, While I appreciate the simplicity of the .1Hz nearly DC routine, I wonder you should not build the routine on a 50Hz sine.
The .1Hz routine only being usable for offset. And a 50Hz signal for amplitude. (Note that for a good sine, Vac and Vrms are the same, so a TrueRMS DMM is not even needed)


The DSO (DS1070Z-S) disagreed quite a bit with the DMM. Forgot the numbers, but at 50Hz at least 10% off. I assume the DMM is correct. But the DMM cannot be trusted above 400Hz or so, for 1MHz or 10Mhz signal it probably does not even see a signal at all.


So I am not sure if you plan to extent the calibration toward attenuation, but in that case, we'd have to come up with something smarter.
By lack of a smart idea, the only thing I can come up with is to read and use the error of the DSO at 50 Hz and next read the DSO at 1MHz, and first apply the 50Hz multiplier.
But not sure if that is reliable. Maybe we should for now not bother with attenuation correction.
I suspect you already went through this reasoning anyway.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on April 09, 2018, 09:37:25 pm
Thanks Cybermaus for sharing your positive experience with THS3095.
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1471111/#msg1471111 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1471111/#msg1471111)

I ordered 2 pieces on eBay, same seller.
Regards
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on April 10, 2018, 09:52:03 am
I finally got around to seeing about upgrading the PSU to a linear one. 

The transformer fits fine, the two regulator boards fit fine, the fused 3 pin IEC socket will fit fine.  There is no chance of them all fitting together in the case.

What I'm currently considering is putting the PSU into an external enclosure and using some 6 core cable to run a lead to a socket on the back. 

Of course the other option is to just use the existing switch/2 pin plug, not earth the transformer chassis and even then it will be highly cramped.  Maybe if I made my own regulator board combining the two I bought it would work.

Even going external, the largest enclosure I could find in maplin closing sale is not big enough :(  Not without things like the heat sinks being put against the insulated spade connectors for the mains IEC plug.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on April 10, 2018, 10:44:22 am
I finally got around to seeing about upgrading the PSU to a linear one. 

The transformer fits fine, the two regulator boards fit fine, the fused 3 pin IEC socket will fit fine.  There is no chance of them all fitting together in the case.

What I'm currently considering is putting the PSU into an external enclosure and using some 6 core cable to run a lead to a socket on the back. 

Of course the other option is to just use the existing switch/2 pin plug, not earth the transformer chassis and even then it will be highly cramped.  Maybe if I made my own regulator board combining the two I bought it would work.

Even going external, the largest enclosure I could find in maplin closing sale is not big enough :(  Not without things like the heat sinks being put against the insulated spade connectors for the mains IEC plug.

In this situation I'd go with everything inside without the IEC power plug.
Linear transformer/supply will be good with the original non-grounded plug and the outputs will be floating. You can always ground through the BNC.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on April 10, 2018, 10:44:48 am
If you use an external housing for the PSU I would look after a similar sized housing that can be used as a stand for the FY6600. Using the screw holes of the FY6600 housings' feet for mounting the FY6600 on the PSU housing and you can directly connect the wires. If the housing is beveled you also have a good viewing angle on the display of the FY6600. I would have made it like this if my solution would not have fit inside.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 10, 2018, 11:49:03 am
How about just putting a hard-wired power cable (with a strain relief)?
After-all, in reality we always put in a cable anyway. Not really needed to make the device cable-less unless it has a battery.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 10, 2018, 08:54:10 pm
It might be a tight squeeze for me to fit everything in too ,once I change over to transformer/linear setup psu.
One thing I did think of was the possibillity of mounting some of the psu components to the lid of the box ,that way it might make some more room on the ground floor so to speak.
I got two different kinds of bluepill boards and a USB to TTL convertor in ,still no sign of the St link unit though.
I had a wee look at the specs for the 3095's ,absolute max volts is 33 across the rails ,normally 30 volts is the recomended max.The two regs feeding the OPA686n's wont have a huge amount of current through them ,so Im guessing they'll be ok scrubbing off the extra volts .Another good thing I noticed was that THD rises with frequency ,so for audio which will be my main usage distortion comes in at around -80db below 1mhz,and probably even better down at lower frequencies. I did also get a chance to look at the noise floor which showed some spikes ,most likely it'll be a lot quieter once the linear goes in .

I did end up putting in for the competition ,but I have no twitter account ,so I probably dont qualify ,Id prefer to see the people with defective V3.1 units properly sorted out instead though. Im happy with my FY6600 ,it does blow the competition out of the water despite the few short comings , and the learning experience of upgrading the unit is a good thing in itself as well.

If anyone has found a good tutorial on blue pill and St link stuff they might post it here as Im more or less brand new to all of it .
I am very much looking forward to exploring all the functions and tweeks that Fremen has added , I think we'll have a very high spec machine that will compare favourably with units costing many times more money once we get to where were going .
Keep up the good work .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: paulca on April 10, 2018, 09:02:08 pm
I know this is off topic, but I can reuse the board mounting holes in the case to secure the important transformer, but is it acceptible to hot snot the regulator boards to the case?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 10, 2018, 09:07:04 pm
The transformer fits fine, the two regulator boards fit fine, the fused 3 pin IEC socket will fit fine.  There is no chance of them all fitting together in the case.


Try thinking laterally, people: there's no rule that says all the parts have to fit on the same side as the existing power supply!  There's plenty of space above the signal board for one of the modules, and enough space down the side of it for a couple of spacer legs to secure it to the case.  With one module out of the way there'll be loads of room to fit the rest in the free space - see my layout here:

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1430394/#msg1430394 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1430394/#msg1430394)

It looks from the photo as if the 5v module is sitting directly on top of the signal board, but it's actually 20mm above it, with 25mm hex spacers fixing it to the case at the left side, as viewed.  It doesn't really need anything else to secure it, but I put a couple of 20mm spacers at the other side of the module, just sitting on the signal board to stop it from possibly vibrating loose.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 10, 2018, 09:21:30 pm
I know this is off topic, but I can reuse the board mounting holes in the case to secure the important transformer, but is it acceptible to hot snot the regulator boards to the case?

Nothing to stop you, but spacers and screws are better.  Use nylon instead of metal and you won't have any risk of accidental shorts or shocks, and there'll be no problem with drilling the case for new holes as the insulation will be fully preserved. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 11, 2018, 04:52:15 am
..absolute max volts is 33 across the rails ,normally 30 volts is the recomended max...
Absolute max rating is where the device supposed to not yet burn, but there is no guaranteed or even documented behavior or fidelity at that voltage. It just means that if you bring it back from 33V to 30V, it should work again, whereas is you bring it back from 33.1V, it is allowed to be damaged. It will probably still work, but you are walking on a sharp edge with 33V.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 11, 2018, 05:36:36 pm
Thanks Cybermaus for sharing your positive experience with THS3095.
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1471111/#msg1471111 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1471111/#msg1471111)

I ordered 2 pieces on eBay, same seller.
Regards

The seller noticed the sudden boost in sales, and nearly doubled the price from $2.85 to $4.75

Interestingly, he did it in such a way that the listing appears to be down-priced: from $5 to $4.75
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 11, 2018, 06:40:44 pm
The price was indeed $5 each, I noticed last night.  Luckily, I bought a couple for the parts box at the original price last week. :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 11, 2018, 07:35:16 pm
He is probably going to be disappointed: Most people active on this thread have already bought it since original message on April 5. (http://offer.ebay.com/ws/eBayISAPI.dll?ViewBidsLogin&item=292350281588&rt=nc&_trksid=p2047675.l2564) Not many people left to buy, no more sales for the last 2 days. He may be too late with his price.....
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 11, 2018, 07:41:08 pm
My thoughts exactly.  The early birds have already caught their fill of worms....
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sdouble on April 11, 2018, 07:45:11 pm
I don't understand why you don't get them for free :
http://www.ti.com/product/THS3095/samplebuy (http://www.ti.com/product/THS3095/samplebuy)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 11, 2018, 11:00:52 pm
Well it does say this down in the small print ,
** A myTI login ID associated to a corporate domain is preferred for sample requests. Update your myTI profile

Maybe its worth a try saying your a student working on a project,but again you may need to prove a connection with a learning institution to qualify,maybe if you have a friend who works in the electronics industry  you could get them to do it for you  . You never know though ,if you come up with the right story they might just decide to send you out a pair of op amps anyway ,maybe a little window dressing ,like a webpage and an official sounding email address is all they want .Better still ,tell them you already have the 3095 in your fy6600 and you want to try the new 3491 op amp in So8 package.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on April 12, 2018, 12:23:02 am

Maybe its worth a try saying your a student working on a project,but again you may need to prove a connection with a learning institution to qualify,maybe if you have a friend who works in the electronics industry  you could get them to do it for you  . You never know though ,if you come up with the right story they might just decide to send you out a pair of op amps anyway ,maybe a little window dressing ,like a webpage and an official sounding email address is all they want .Better still ,tell them you already have the 3095 in your fy6600 and you want to try the new 3491 op amp in So8 package.

All to save $5??
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 12, 2018, 04:46:40 am
I tried that a few times. 3 times I believe. with 3 different vendors.
Got some chips once, but the other times they never responded, so I had forgotten about that route.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on April 12, 2018, 09:02:43 pm
My thoughts exactly.  The early birds have already caught their fill of worms....

ebel0410( 519)   2,85 USD   2   09-avr.-18 23:28:59 Paris

I'm the last buyer who got them at that price $2.85 !
No more sells since April 9th  :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on April 12, 2018, 10:03:54 pm
Plenty still available from Alibaba - starting at US $2.85.

I decided to wait for the new THS3491. It seems to be worth it :-)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 12, 2018, 10:54:46 pm

I decided to wait for the new THS3491. It seems to be worth it :-)

Given the huge improvements we've already seen with THS3095s, it's hard to see what extra goodness you're hoping for with the 3491s (whenever they become available).  A few extra mV on the outputs?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Cliff Matthews on April 13, 2018, 12:56:08 am
Just curious, is the DY6600 able to add its channels together?  (*edit maybe not, don't both channels share the same ground?)

I've considered upgrading my signal gen for a while and just today W2AEW showed a novel way of producing an adjustable 3-step signal for testing transistor rise and fall times. https://bit.ly/2HcPAuL (https://bit.ly/2HcPAuL)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on April 15, 2018, 02:32:16 pm
Hello,

Does the 3091/3095 THS have short circuit protection on the OUT (output) like the original THS3002 installed ?


Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 15, 2018, 05:17:41 pm
Comparing their datasheets:

Quote
THS3095:
Output current 350 mA [on 50 Ohm equivalent to 17.5V]
[no mention of current protection]
The THS309x incorporates automatic thermal shutoff protection. This protection circuitry shuts down the amplifier
if the junction temperature exceeds approximately 160°C.

THS3002:
Output current 175mA [on 50 Ohm equivalent to 8.75V]
The THS3001 incorporates output-current-limiting protection. Should the output become shorted to ground, the
output current is automatically limited to the value given in the data sheet. While this protects the output against
excessive current, the device internal power dissipation increases due to the high current and large voltage drop
across the output transistors. Continuous output shorts are not recommended and could damage the device.
Additionally, connection of the amplifier output to one of the supply rails (±VCC) is not recommended. Failure of
the device is possible under this condition and should be avoided. But, the THS3001 does not incorporate
thermal-shutdown protection.
Because of this, special attention must be paid to the device's power dissipation or
failure may result.

So, strictly it does not, but with the fact you'd have to drive it above 17Vmax, or thus 34Vpp to reach the allowed maximum current, and the fact it has thermal shutdown, and the fact it has two chips in stead of one, I think we are fine.


Edit: thinking about it a bit more, it is not the OpAmp, but the 50 Ohm resistors that we'd have to worry about:

Driving it at 20Vpp Sine or 7.1Vrms, the two build in 100 Ohm resistors have to dissipate 1/2W each.
Driving it at 20Vpp Square or 10Vdc the two build in 100 Ohm resistors have to dissipate 1W each.

I think regardless of 3002 or 3095, it is the resistors that will fail if shorted for a longer time at maximum output. So no change to the short-out protection of the device as a whole. Manual states: "All channels can work more than 60 seconds when the load is short-circuited."

But I don't think I want to run 1W or even 1/2W for a 60 seconds on those resistors
At lower voltages (5Vsq would be 0.01W; 10Vsq 0.25W) we should be fine
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on April 16, 2018, 04:32:33 pm
Hello,

Start up feeltech generator, plug in an oscilloscope on CH1 or CH2 to view a signal, and move your finger on the plastic of FPGA cyclone, the generator hangs, it must be turned off then on again to work again.

I noticed that.

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 16, 2018, 05:29:09 pm
Sorry,  not here. Touched it. Rubbed it. Firmly pressed on it. Keeps working.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on April 16, 2018, 10:27:29 pm
Does it do it if you wear a grounded wrist strap?
Is the Feeltech common floating or grounded?
Is the scope common floating or grounded?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: thedoc298 on April 17, 2018, 02:00:57 am
Another observation after the 3095s mod is that you can now get half decent output up to at least 100MHz using the two or three cycle sine wave trick.  However, attenuation of the output continues to increase with frequency - you don't get higher output amplitudes despite starting from a lower base frequency in the control software.

So just remove one 3002 and install 2 3095'S thanks info overload
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on April 17, 2018, 10:51:39 am

I decided to wait for the new THS3491. It seems to be worth it :-)

Given the huge improvements we've already seen with THS3095s, it's hard to see what extra goodness you're hoping for with the 3491s (whenever they become available).  A few extra mV on the outputs?

THS3491 is already available from the TI store and I ordered 2 devices - $10 each with free shipping :-)

Let's see how it performs compared to 3091/95. I hope it will improve even more the quality of the signal at the upper end of the frequency range.

BTW - I received my unit with 3.2.1 firmware and noticed that the output voltage is limited to 5Vpp above 20MHz. I believe this was not the case with the previous versions. Can someone confirm ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 17, 2018, 02:11:46 pm
So I finally changed my unit over to the transformer based supply , I had to mount the mains socket about 5mm behind the enclosure back panel and trim the connection tabs on it and the switch to make everything fit . I used the blue 317/337 dual rail supply fed by 2x17 volts ac winding ,that combination gives up to around +/-20 volts dc ,trimable to what ever voltage you like .For the 5 volt rail I added a bridge rectifier and a filter cap to the red two ic dc-dc convertor , fed from an 8 volt ac winding .The bridge rectifier and cap can easily be mounted at various angles in relation to the board making this quite a compact arrangement ,it also wastes very little in terms of heat .
Without any load on the output signal ,the transformer and the +/- regulators run cool .With a 50 ohm load and as you wind up the output voltage, transformer ,regulator heatsink and output heatsink all have to work harder ,for now Ive only run it with the lid off .
The extra weight of the transformer and other stuff gives the unit a much more solid feel ,it doesnt move around the bench when you press the buttons anymore .I'll do some more tests with the lid on and with the thermal probe ,but Im sure everything will be within a safe margin temp wise. I'll post a couple of pics once Ive had my coffee
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 17, 2018, 02:19:14 pm
BTW - I received my unit with 3.2.1 firmware and noticed that the output voltage is limited to 5Vpp above 20MHz. I believe this was not the case with the previous versions. Can someone confirm ?

Always been like that.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 17, 2018, 03:08:36 pm
Heres how it looks now ,I mounted the iec connector with long screws and an extra nut and washer to build it out 5-6mm from the back panel. The transformer comes in at around 30va which seems a lot,it must weight 1kg or so , but the board can suck maybe 500ma on the +/- rails when both output stages are driven into 50 ohms,that winding is rated for .75 amp ,so +50% capacity on top seems like a good number. Remains to be seen how it works with the lid on
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on April 17, 2018, 03:24:06 pm
Hello,

Why always talk about the THS3095, while the THS 3091 is identical (except PD [Power Down] pin which is useless), cheaper and certainly very available ?
----
Sheet metal transformers vibrate, toroidal transformers do not vibrate and enamelled wire can be wound to obtain additional voltage for the purpose.


Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 17, 2018, 04:19:46 pm
 A look through the spec sheet of the various op amps show paralleling output devices can increase the output current , but 250 or so mA per 3095 is more than adequate for most purposes . I think the original smps supply doesnt have the extra current required by the 3095,or other upgrade op amps to work very well.

Ive set my rails to 13volts for now.
The signal ground Ive left disconected from mains earth ,only the transformer case and the metal magnetic/ Rf screen between psu and signal board  are permanently bonded to earth.I'll add a few extra inductor cores in the supply wires also ,just to snuff out any rf .Just one or two final fitting adjustments and I'll try it with the lid on .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 17, 2018, 04:54:47 pm
Why always talk about the THS3095, while the THS 3091 is identical (except PD [Power Down] pin which is useless), cheaper and certainly very available ?
When I looked, the 3095 was either cheaper (for single units) or the 3091 completely out of stock (for single units)

And I bought some extra. With the 3095 disable pin defaulting to enable when left floating, it behaves the same while at the same time having more options.
So I'd rather have a few 3095 in the parts drawer then a few 3091.

But you are right, the 3091 is probably the default option, the 3095 the equally valid alternate choice.
Note that the newer 3491 also has a power down, so in that sense is more like the 3095.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Diabolo on April 17, 2018, 05:01:36 pm
Here is what I installed to have 2 separate AOPs ; THS3091 :
- https://fr.aliexpress.com/item/THS3091DR-THS3091-SOP-8/32786721972.html?spm=a2g0w.search0104.3.2.63f04d6cD4EYta&ws_ab_test=searchweb0_0,searchweb201602_2_10152_10151_10065_10344_10068_10342_10343_10340_10341_10698_10697_10696_10084_10083_10618_10305_10304_10307_10306_10302_10059_10184_10534_308_100031_10103_441_10624_10623_10622_10621_10620,searchweb201603_25,ppcSwitch_5&algo_expid=e1d2b25f-7a5b-4642-a647-02f098dfc3ac-0&algo_pvid=e1d2b25f-7a5b-4642-a647-02f098dfc3ac&priceBeautifyAB=0

Diabolo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 17, 2018, 11:22:09 pm
 I switched the output frequency to zero on my unit and scaled through the different amplitude  ranges 0-.6, .6-5volts,and 5-20 volts ,I measured the output noise on the high range,5.1volts or above (3095 engaged)to be 150microvolts ac rms (0.00015volts),that seems to translate into around 100db dynamic range refered to 20 volts output .I couldnt measure directly the noise on the two lower ranges with the meter . It would be interesting to compare this figure to other user's results .

I also monitored the output through a mixer with headphones ,there was no trace of hum or any kind of digital artifact
in the noise floor ,just the usual random resistance noise ,a good bit above the mixer noise floor. Be carefull not to touch the frequency setting while listening to the backround noise in the head phones *
I might give the original smps one last try for a comparative test for noise level at the outputs.
For now with the lid on and both channels 20 volts output into 50 ohms ,the transformer is starting to heat up a bit .


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 20, 2018, 01:10:33 pm
Im quite surprised by the amount of heat Im getting from the transformer ,its not burning up or anything ,but its certainly working towards the upper end of its capacity when the unit is driven . The fact that the enclosure is made of plastic means the transformer cant loose heat to it in the way it does with a metal box . I was thinking of adding an extra aluminium plate on the under side of the case ,secured in by the four bolts on the transformer ,just to try and loose a little more heat to the outside world ,I think the lower corner vents could breathe better as well  so Ill open these out a bit  .The dividing screen I put in effectively seperates the two sections thermally but doesnt help reduce the temp in the psu section much. A lot  of the extra capacity of the new psu ends up  having to be dumped as heat in the transformer and regulators ,but thats the cost of quiet supply rails I guess.

I think I read way back in the thread somewhere that 5 volts or below is a bit marginal ,if we make 3.3v from the five that only leaves 1.7 volts drop on the regulator ,maybe 5.3 volts might be better here .Wont make a huge difference to the temp of the 5volt supply board in any case ,I might need to find a way to thermally bond it to the metal plate that supports it ,while maintaining ground isolation  . The tabs on the regulator chips have their own isolated heat sinking sections on the back of the board ,but it seems these arent adequate in this instance , I need to find a way to mount the board and thermally couple the bridge and the ic's to the plate ,Any ideas welcome.
I'll post a couple of properly lit photos shortly  to illustrate better .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on April 20, 2018, 03:02:11 pm
Im quite surprised by the amount of heat Im getting from the transformer ,its not burning up or anything ,but its certainly working towards the upper end of its capacity when the unit is driven.
Have you checked the math (or measured) what is the conduction angle on the transformer?  That is, not too big filter caps so that the transformer can work during longer periods of the cycle leading to lower losses in it.  It is a compromise, though..

Quote
I think I read way back in the thread somewhere that 5 volts or below is a bit marginal ,if we make 3.3v from the five that only leaves 1.7 volts drop on the regulator ,maybe 5.3 volts might be better here.
This depends a lot on the particular regulator and the operating (max) current. For example, I have (currently only) plans where a linear regulator should end up working at around 80mV drop, when its basic advertised-single-parameter drop is 0.5V. (Yeah, low drop to start with, but I'm going to drive it at less than 10% of maximum current, and the datasheet was nice enough to characterize lower currents, too).  Then again, these kind of devices tend to have tiny regulator chips, and design leaves them to run near the max currents.

If you're already using DC-DC for the 5V generation, there isn't much more to gain in that. I'd concentrate on optimizing the higher voltage rails, and since without DC-DC the total regulation drop there decides the total heat to be wasted, and it is more about choosing how to spread it among components... Except for the transformer conduction angle; if you can allow more ripple before regulator (and possibly lower output voltage), that might help with the transformer heating and improve total efficiency.  Judging from the picture, there is only one (large) cap per rail, so the filter capacitance isn't likely too huge, but worth checking, perhaps.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 20, 2018, 10:52:34 pm
Hi soundtec,

I think the heat from your transformer is probably inherent in its construction (E-I type, lots of iron, lots of eddy currents, lots of waste heat).  For a comparison, I've just run mine for 30 minutes with both channels at 9MHz, 20Vpp into 50 ohms and the heat produced by the PS is:

R-core transformer (30VA, 15-0-15v, 9v, 0.5kg) - nothing that can be felt after removing the lid.
Regulators on 12-15v board (same type as yours) - barely warm (running at 13.5v).
Regulator on 5v board - hot (normally runs about 70C).
Case - still cold above the transformer.

This probably says a lot for the efficiency of R-cores over E-I types!  This project is the first time I've ever used one (or even heard of them, actually - I only came across them while searching for a suitable "regular" type), but they'll certainly be my first choice for similar jobs in the future.

Just some food for thought.

Dave



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on April 21, 2018, 11:47:54 am
Im quite surprised by the amount of heat Im getting from the transformer
I'd guess it's a cheaper transformer with a marginal amount of iron for the primary voltage. The core is probably saturating at peak, causing a current spike, hence dissipation, in the primary winding.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 21, 2018, 03:03:27 pm
Thanks Bugi ,Dave and PLB.
I kept the smoothing caps a reasonable size ,2x3300uf @ 50volts on the +/- rails ,and just 1000uf on the 5 volt rail . Electrically Im happy with it ,I am scrubbing off some extra volts on the regulators ,so I expect them to run  a bit hot. I think the reason the transformer heats a lot is theres no where for it to loose heat too, such as a metal chassis and open air to conduct the heat away . Interesting point you made Bugi about it being a matter of sharing the heat around among the different components , I could try some different low voltage drop diodes /bridges ,loose some dissipation in the transformer ,but then I end up having to push the regulators even harder due to the extra volts.

It takes an hour  before things start getting warm on my unit ,but it continues to rise upto four or five hours before leveling out, even with both channels in standby . Just shifting a little heat outside the box might be enough to keep things under better control ,I'll try the metal radiator plate on the underside of the case and see if that helps.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on April 21, 2018, 04:33:37 pm
Im quite surprised by the amount of heat Im getting from the transformer ,its not burning up or anything ,but its certainly working towards the upper end of its capacity when the unit is driven .
That is a typical problem with low power transformers: many get very hot. In one of my designs I replaced a transformer with a switching one which fits in the same footprint.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on April 21, 2018, 06:28:11 pm
What happened to I think it was rhb's ultimatum? Has FeelTech responded?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on April 23, 2018, 03:12:05 am
Soldering the TXCO modul is something you need patience for. I placed kapton tape on the bottom side of the module so that all the not needed pads were covered.

On the TXCO module, what do you do about pin 8? Do you cover it with kapton or solder it together with Vcc?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on April 23, 2018, 10:54:53 am
I only connected pin 4, 5 and 9. All others are covered by kapton tape.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on April 23, 2018, 11:08:29 am
I only connected pin 4, 5 and 9. All others are covered by kapton tape.

That is interesting, I wonder how it affects the operation of the device to leave the trip state buffer enable/disable pin floating. It doesn't mention that anywhere in the datasheet
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 23, 2018, 12:14:04 pm
Well it looks like an Fy6800 is on its way out to me .
I didnt actually ask if I get to keep the unit ,but I think that is the intention at the end of the day .
Of course I still very much hope the handfull with broken units get satifsfaction on repair or replacement ,and I did mention this in my reply to Feeltech also.
It'll be interesting to compare the units side by side and see exactly what changes have been made ,aside from the obvious physical differences .
Hopefully we can get back to a more productive discussion soon about improving the software.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ghislain on April 23, 2018, 01:50:38 pm
Their marketing team still has their job to do, the product description still mentions FY6600 everywhere (except for the Frequency table)  :palm:
http://en.feeltech.net/html/Signal%20generator/show_61.html (http://en.feeltech.net/html/Signal%20generator/show_61.html)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on April 23, 2018, 07:05:17 pm

That is interesting, I wonder how it affects the operation of the device to leave the trip state buffer enable/disable pin floating. It doesn't mention that anywhere in the datasheet

Note 5 on page 1 of the datasheet I downloaded states, "Output is enabled with no connection to Pad 8. Leave Pad 8 open if disable function is not required." 

I wish I'd spotted that when I did mine!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on April 23, 2018, 07:10:45 pm

That is interesting, I wonder how it affects the operation of the device to leave the trip state buffer enable/disable pin floating. It doesn't mention that anywhere in the datasheet

Note 5 on page 1 of the datasheet I downloaded states, "Output is enabled with no connection to Pad 8. Leave Pad 8 open if disable function is not required." 

I wish I'd spotted that when I did mine!

Thanks, I totally missed that tiny little note!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: andrewjessop on April 29, 2018, 05:34:44 am
Hey everyone,

What an interesting yet very long thread! I've just read through 50pages from beginning to end and finally finished :phew:

Two questions from me:
1. Is there any difference between the 15Mhz and 60Mhz versions - from both a hardware and FPGA bitstream point of view?
2. Any updates on the custom firmware?  Seems like everyone has gone quiet.

Cheers,
AJ
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 29, 2018, 01:35:50 pm
Hi AJ,
Physically the hardware is identical if you have a 15 or a 60 meg unit ,what changes is the firmware in the front panel ,that allows you access the higher frequencies on the FPGA board .

Yeah the thread has gone very quiet of late , as you can see from reading the entire thread ,some of the earlier units gave trouble ,theres around half a dozen still waiting on a fix ,Anything above firmware 3.2(which is what I have ) so far has worked fine as far  as I know .

As you will also see the model FY6800 is about to hit the shelves ,several of the suggestions made here have ended up incorprated into it ,like a three pin mains connection ,rubberised buttons on the front panel instead of polycarb bubble type. The firmware will also updateable by the user . No one has actually got their hands on the unit yet so probably some other surprises to come as well.

I was using the unit recently to generate audio tones and I noticed that on certain combinations of frequency and amplitude the aliasing previously described due to clocking frequency could be heard as an overtone or distortion on a relatively low audio frequency sine waves .Thats really our .5% thd limit ,  its got nothing to do with distortion in the output stages . Exactly as previously described the anomaly comes and goes depending on frequency the unit is set too ,but maybe the amplitudes of the original samples plays a role too . Maybe theres something simple we could do with the waveforms used to generate the tones to mitigate the aliasing issue .I think this is the weak point of the hobbist type sig gens vs the ones that cost many hundreds or thousands .Its a logic problem and I think the right approach in software can do a lot to help.

What would be amazing would be a auto calibration mode in software ,link each channel to the input ,run the calibrator and bang everything is needle flat from dc to 60mhz,and offsets are tweeked to avoid bad numbers from the dacs too .

Anyway hopefully the software side of this project continues ,I think all of the hardware mods are fairly well documented.

 





Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on April 29, 2018, 04:48:23 pm
The firmware will also updateable by the user
What makes you think that? Surely not that Chinglish promise at the start?

It is my firm believe it is not update-able, and the fact they did not respond to several questions about it in the FY6800 giveaway thread seems to confirm that.
Pretty sure it is a near identical device electrically, and I hope identical enough for a shared firmware project.

And yes, the custom firmware is a bit quite of late, but its a one man show, and its been good weather outside in France for the last few weeks, surely fremen67 has been positively distracted. I do hope though, in case he is completely busy with other stuff, he publicizes his sources. But even then, who else is going to spend all the time...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on April 30, 2018, 11:46:02 pm
Here is a new version v0.6 of the bluepill firmware with the sweep function, as well as the corresponding modified PC Software v0.6.

I did not gave up for those wondering  :). I am still working on it during my free time.

Sweeping was not a big problem but sweeping fast and accurately was not that easy.
Counting 999.99s in a 32bit word allows a minimun resolution of 10µs. That was my starting point.
After some optimization, sending a command through SPI @18Mhz  takes 5.6µs. My goal was then to be able to update a new value (Freq, Amp, Offset or Duty) in less then 10µs, that is computing the next value in less than 4.4µs where the original FY6600 updates values every 900µs...
 I had to face some more or less challenging problems, the biggests beeing:
- CPU has only 16bit counters
- with the standard C library a 64/32 bits division takes about 40µs (at least one needed)
- with the standard C library the x^y function takes more than 100 µs (one needed for logarithm  mode)
Plus the sweep parameters are not readable with the Feeltech protocol and the sweep functions in the PC Software were a pity so I had to rewrite them.
But it would have been too easy otherwise  >:D

So, as said, the sweeping time resolution is 10µs.
In sweeping mode, a new value can be sent every 9.2µs in linear mode and every 12µs in logarithmic mode.
Sync mode works well in sweeping mode with duty (add 5.6µs) but not so much with Frequency as the phase is not very stable at high frequencies.
I did not code Amplitude and Offset Sync in sweeping mode at the moment (with calibration values beeing different between channels , I can't send the same values for both channels, plus you can have different output limits between channels). May be later on if this is usefull.
I may also add later on calibration values for VCO IN.
I also wanted to add more diagnostic information on PC Software and modify init functions but this will be for the next time...
Also everything is ready for a sweeping function on channel 2. I will just need 2 more STM32 Timers that I prefer to have in spare for now.
I will now start the modulation module.
Any volonteer for an extensive quality check on the sweep module?
Thank you for your feedback!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on May 01, 2018, 05:24:14 am
^^HERO^^

I so want to test this function and sweep some 10.7MHz filters I have for my AKAI AT2400 Tuner. Vero board time for a opamp output buffer then :)

Thanks a lot for you effort again. I've off for a while but I need to update the schematic for the counter part. Still want to make a custom PCB for the PS though.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 01, 2018, 07:26:15 am
I am very busy this week (travel for work, visiting customers. All that annoying bread-on-the-table stuff.)
So alas, I may not give fast feedback.
However, I did last week get my new LA, so when I eventually do get to it, I will try that too.

(In fact, visiting your home: France, French Alps, Annecy, probably not even time for the Mont Blanc though)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on May 01, 2018, 11:40:37 am
I lost the negative 5V regulator for the second time. Now replaced with TO220 package as I did previously when I lost the positive 5V regulator. However the CH2 amplifier had also gone. It seems to be an AD8009, SOT23 package marked HJK. The replacement is on its way.
The attached photo shows the two AD8009s, each with two pots adjacent. Maybe these are for trimming the positive and negative half cycle amplitude, but I'm not sure enough to blunder in.
Does anyone know the function of these pots?
(Edit) The CH2 AD8009 on the right has been removed, pending replacement
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 01, 2018, 02:35:14 pm
I hope no one will be upset if I ask a few questions rather than search through the entire thread.  I have a V 3.1 unit I'd like to get working properly.  I now have some blue pills and STM-Link programmers and the connectors to fix the cable I borked.   I'm sure that the information is somewhere, but I've not been following the thread closely.

I got busy buying test gear which required a major reorganization of my work bench.  I still need to complete the new power distribution system as power strips became impractical because of the number of cords going to them.  Let's just say I decided to buy the bench of my dreams for my 65th birthday.  So I now have an HP 8560A 9 KHz to 3.2 GHz SA with TG among other toys.

What is the the granularity of the sample clock?  What sample rates are available for the output?

How long does it take to change the output sample rate?  That is, how quickly can the sample rate be changed?  The recent post by fremen67 suggests that we can change the sample rate in less than 1/3 the time it takes to output a full waveform.  But I may not understand what he means by updating in 10 uS.

I'd like more information about the 0.5% THD limit.  At what frequencies and sample clock rates are the spurious tones being created?

I've downloaded everything from github, but have not started reading it yet.  I'll start that this evening.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 01, 2018, 09:06:05 pm
I am not fully understanding your sample questions.

But Fremens67 software cannot (yet) be loaded onto the front-board. Only on bluepill
However, if you have a 3.1 unit, then all you have is a broken sine wave, right? Not the full corrupted screen. If so, all you need to do is flash the WinBond chip. Instructions for that are around page 40 or so. Your STM32 is still good. (or at least, I do not remember anyone reporting anything other then sine wave corruption on V3.1)

You'd need to update Winbond anyway, because even if you want to go BluePill, we discovered Fremens firmware only works with V3.2 of the WinBond. Its also posted on this thread somewhere, a couple of pages after the Winbond programming instruction.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 01, 2018, 11:09:42 pm
I'm sorry.  I've got V 3.0.   Will the blue pills not work with that?

My sample questions are related to the sweep feature.  I thought I'd see if I can contribute something to that.  Is fremen67's  stored waveform swept? I was thinking of writing a program that would  calculate waveforms so that one could load a couple of waveform registers alternately so that one got a smooth sweep by changing the sample rate and waveform register.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 01, 2018, 11:26:10 pm
Hi fremen, I've given the sweep module a good two hour workout and all appears well to me.  It wasn't a systematic test across all the ranges, more of a "does it do what I need it to do" play around, but it certainly works as expected.  Everything is silky smooth and glitch free, as far as I can tell.  I'll play some more with it over the next couple of days, and no doubt cybermaus will do his technical appraisal when he gets back from buying his loaf of bread.

Thanks again for all the work you've put in to get us this far!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 02, 2018, 04:18:55 am
I'm sorry.  I've got V 3.0.   Will the blue pills not work with that?
They should, but you'd still need to update your winbond to V3.2

It would actually be interesting to do so, I think no-one actually tried that yet on a corrupted V3.0 because we all assume the corruption is in the STM32, but there is a (very small) possibility the screen corruption is also driven from the Winbond flash and the STM32 is merely badly responding to weird input.

My sample questions are related to the sweep feature.  I thought I'd see if I can contribute something to that.  Is fremen67's  stored waveform swept? I was thinking of writing a program that would  calculate waveforms so that one could load a couple of waveform registers alternately so that one got a smooth sweep by changing the sample rate and waveform register.
Well, current sweep is only to sweep frequency, amplitude, PWM, and those are driven internally by the device STM32, no need to do it from the PC. Also, I think the PC connection is way to slow to do that seamlessly. Best try and get your BluePill based FY6600 running first.

Here is the link to the Winbond flash (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1352448/#msg1352448)
Here a couple  (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1444972/#msg1444972)of samples  (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1470609/#msg1470609)to BluePill wiring:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 02, 2018, 12:47:37 pm
Sigh..  More stuff to order from eBay.  So another delay while I wait for a Winbond programmer.

Any comments on these?

https://www.ebay.com/itm/New-USB-Programmer-CH341A-Series-Burner-Chip-24-EEPROM-BIOS-Writer-25-SPI-Flash/253056283240 (https://www.ebay.com/itm/New-USB-Programmer-CH341A-Series-Burner-Chip-24-EEPROM-BIOS-Writer-25-SPI-Flash/253056283240)

This seems to be the only thing that will ship from USA.

There are also these, but from China

https://www.ebay.com/itm/ALL-IN-1-Multifunction-USB-to-SPI-I2C-IIC-UART-TTL-ISP-Serial-Adapter-Module-S/202172849567 (https://www.ebay.com/itm/ALL-IN-1-Multifunction-USB-to-SPI-I2C-IIC-UART-TTL-ISP-Serial-Adapter-Module-S/202172849567)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 02, 2018, 04:59:08 pm
The black one works (I've got one), but I haven't seen the other before.  You can also get a clip on connector for the black one to make programming the chip in situ very easy.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 02, 2018, 05:15:29 pm
A 96.9% rating is pretty low though. I am never quite sure how well earned it is, or did the seller just have bad luck with a bunch of nagging buyers.
Then again, $7 will not brake the bank I assume?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 02, 2018, 05:58:25 pm
@DaveR  can you point me to the clip on connector?

@cybermaus  I hadn't looked at the rating.   I was really just asking about the device.

In many respects, I'm tempted to just punt on this turkey and let someone else play with it.  I've bought a bunch of early 90's vintage HP gear in the last few months and it's a much more satisfying experience.  A *lot* more money than Chinese stuff, but I'm about to turn 65 and decided it was OK to spend some money.  I've been very frugal my whole life, so I can both afford it and feel I deserve it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 02, 2018, 07:45:50 pm
Just search on ebay for "Soic8 Sop8 Test Clip for EEPROM In-circuit Programming" and lots will come up.  Get one with an attached cable and adapters for the CH341A, then it's all just plug in and go.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 02, 2018, 08:04:49 pm
@DaveR  can you point me to the clip on connector?

@cybermaus  I hadn't looked at the rating.   I was really just asking about the device.

In many respects, I'm tempted to just punt on this turkey and let someone else play with it.  I've bought a bunch of early 90's vintage HP gear in the last few months and it's a much more satisfying experience.  A *lot* more money than Chinese stuff, but I'm about to turn 65 and decided it was OK to spend some money.  I've been very frugal my whole life, so I can both afford it and feel I deserve it.

I feel your pain, and nobody would blame you for just chalking it up as a loss and moving on.

However, we do appreciate your contributions, and if you ever get that itch to fix something nigh unfixable, we'll be here  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 02, 2018, 08:54:17 pm
In many respects, I'm tempted to just punt on this turkey and let someone else play with it.  I've bought a bunch of early 90's vintage HP gear in the last few months and it's a much more satisfying experience.  A *lot* more money than Chinese stuff, but I'm about to turn 65 and decided it was OK to spend some money.  I've been very frugal my whole life, so I can both afford it and feel I deserve it.
Not quite 65 yet, but old enough to somewhat understand where you are coming from. I have also always been frugal (aka a cheap bastard) and am still amazed at myself how I buy a cheap Chinese AWG when a) I can easily afford the proper stuff and b) I seem to spend relatively high amounts on patching up said AWG with PSU, OpAmps, etc. Truth is, I think I enjoy the challenge and frustration of making things work for pennies on the dollar.

So, my advise, put it to the site when it gets too much, order the $6 programmer just in case, and maybe pick it up again later, or maybe not.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 02, 2018, 10:06:46 pm
Someone asked a while back about extra waveforms ,I found some wave drawing software called Easywave  it needed a component called Visa shared components from National instruments  to run , the files it makes are CSV, where I notice the wave files for the Fy6600 are a different format .I wonder is there a way to convert the format, looks a good bit more elaborate than the feeltech software . Im not sure if the FY6600 will talk to this program directly ,but it might be possible to use it to create waveforms all the same .Be interesting to hear from anyone with experience using this or other waveform creation software.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: spec123 on May 02, 2018, 11:08:52 pm
AFAIK the FY6600 PC software accepts CSV files. I normally make my waveforms using a spreadsheet program when I need a lot of detail, like for modulation waveforms.

Some weeks back I tried ArbExpress, a free AWG drawing program from Tek. It seemed to work well but there was a learning curve. Had some fun making silly waveforms to display on a scope.  Recall that you have to adjust some params in the program to fit the format of the FY6600 waveform. It seemed to work. You have to register with Tek to get the free drawing software.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ledtester on May 02, 2018, 11:11:18 pm
Wow this is an intense discussion - 51 forum pages in only 8 months!

Looks like a lot of hacking of this device is going on. Would someone be so kind as to provide a short summary of what people are doing?

Thanks!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 03, 2018, 12:44:15 am
AFAIK the FY6600 PC software accepts CSV files.


I'll have to check this out if that's the case.  I've also done waveforms in Excel, but just copied the final values into a text file with a '.fy' extension and uploaded it to the FY6600 with fremen67's control software, which works a treat.  I may be able to save a small step if you can upload a csv directly.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 03, 2018, 12:56:43 am
In many respects, I'm tempted to just punt on this turkey and let someone else play with it.  I've bought a bunch of early 90's vintage HP gear in the last few months and it's a much more satisfying experience.  A *lot* more money than Chinese stuff, but I'm about to turn 65 and decided it was OK to spend some money.  I've been very frugal my whole life, so I can both afford it and feel I deserve it.
Not quite 65 yet, but old enough to somewhat understand where you are coming from. I have also always been frugal (aka a cheap bastard) and am still amazed at myself how I buy a cheap Chinese AWG when a) I can easily afford the proper stuff and b) I seem to spend relatively high amounts on patching up said AWG with PSU, OpAmps, etc. Truth is, I think I enjoy the challenge and frustration of making things work for pennies on the dollar.
So, my advise, put it to the site when it gets too much, order the $6 programmer just in case, and maybe pick it up again later, or maybe not.

I'm going to order the needed bits and pieces.  I'd like to have them on hand whether I beat on the Feeltech or not.  i *thought* I had everything already, but had not followed things closely enough to notice the Winbond issue.

My TEC1-12706 Peltier devices came to day so I've started on an experimental build of a small chamber using two in series.

The true definition of wealth is being able to ignore the subject of money.  And the easiest way to achieve that is frugal habits and hard work.

A number of my closest friends have been highly impolite and died without prior permission in the last few years.  It's adjusted my attitude a bit.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 03, 2018, 01:03:43 am
Someone asked a while back about extra waveforms ,I found some wave drawing software called Easywave  it needed a component called Visa shared components from National instruments  to run , the files it makes are CSV, where I notice the wave files for the Fy6600 are a different format .I wonder is there a way to convert the format, looks a good bit more elaborate than the feeltech software . Im not sure if the FY6600 will talk to this program directly ,but it might be possible to use it to create waveforms all the same .Be interesting to hear from anyone with experience using this or other waveform creation software.

I should have read your message first, soundtec - yes, there is a simple method to convert CSV to FY files, just good old copy and paste.  If you've already produced a waveform or two in CSV format, can you post them up so I can see how well they translate?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 03, 2018, 06:14:11 am
Well I have finally finished upgrading the device, I stuck a switch mode power supply into it, along with some new output operational amplifiers, a ferrite for the power rails, and a new txco oscillator.

Other than a few accidental poor connections, everything went swimmingly.

However, I have noticed something rather unpleasant that has caught the attention of other forum members, namely the horrendous jitter when generating non-sinusoidal wave forms at frequencies that are not integer divisors of the 250MHz clock frequency. This jitter really hamstrings the usefulness of this generator.

Has there been a solution identified for this problem?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 03, 2018, 09:38:41 pm
divider of 250MHz, not 50MHz, I am sure you meant to write.
Jitter is 4ns (or indeed 1/250MHz) for vertical edges.

No solution, not even one proposed or speculated, its just part of the fixed PLL. Indeed I would expect the FY6800 to also have this.
Below 1MHz it is not noticeable, above 5MHz it makes your scope screen rather messy, I try to look past it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 03, 2018, 09:44:45 pm
divider of 250MHz, not 50MHz, I am sure you meant to write.
Jitter is 4ns (or indeed 1/250MHz) for vertical edges.

No solution, not even one proposed or speculated, its just part of the fixed PLL. Indeed I would expect the FY6800 to also have this.
Below 1MHz it is not noticeable, above 5MHz it makes your scope screen rather messy, I try to look past it.

Indeed, I meant to write 250 MHz, not 50 MHz.  Of course an integer divisor of 50 will also be an integer divisor of 250 (albeit different integer), but the point is moot.  4ns jitter is pretty ridiculous.  Is it known what aspect of the PLL is causing this jitter?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 03, 2018, 10:41:23 pm
Heres three waveforms created on easywave just to test ,the first two have 8192 samples ,the last has 16384.

What Im thinking is that ,maybe by somehow changing or rearranging the memory sample banks the fpga chooses from we could come up with better figures for THD, jitter or aliasing ,which ever you want to call it .  This thread is so long I often end up reading back stuff that Ive forgotten ,but Zov as far as I remember did suggest something along similar lines ,
could for instance starting and finishing a sample not at the zero crossing points but somewhere else in the cycle help , could different frequency samples be used when the frequency isnt set to a divisor or multiple of 250mhz . Its 14 bit at the end of the day I think best case scenario a signal to noise of about 80db is possible ,at an unfavarouble setting of the controls maybe this worsens to about 50-60db.

Just looking across the specs on the 6800 ,they say its now got resolution down to 100uV ,where the minimum step in the 6600 is 1mV, so maybe they have managed to squeeze something more out of it .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 03, 2018, 10:48:28 pm
CSV files arent allowed ,so I had to zip them
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 04, 2018, 07:53:06 am
Is it known what aspect of the PLL is causing this jitter?

How do you mean, what aspect?  It's simply the maximum resolution of the clock. Its like asking why a picture with a 1024 resolution has blocks that are 1/1024 width.
Of course, even a picture you can "anti alias", basically faking a fuzzy edge by playing with gray scale, and that is why the sine wave appears better. But hard edges are simply either on one tick of the 250MHz clock, or on the next tick 4ns later. Never in the middle.

To fix this (for hard edges) you'd need to vary the base frequency resolution along with the desired frequency, like with a programmable clock, or with a VCO based clock instead of a PLL based clock. Or heavily overshoot the clock resolution, like sample it on 1GS/s instead of 250MS/s. But that is all done in the FPGA.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scyte on May 04, 2018, 01:47:17 pm
@fremen67:
A few weeks ago you claimed you will put the source code in git-Repo if it is stable. I would say you should do it now: That would speed up the process and would allow other users to help you.
Don't blame of failures: open the source :D
Scyte
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 04, 2018, 03:32:08 pm
A bug report for the 0.6 firmware/software package:

Nothing wrong with the sweep module, but I used a different blue pill board for the 0.6 firmware and had to redo the calibration process.  Ch1 Amplitude went ok, but the control software crashed repeatedly while trying to do the Ch1 Offsets (see screen1.jpg).  Restarting the control software brought it back in the configuration in screen2.jpg, and resetting the blue pill brought it back in normal default mode.  I gave up on Ch1 and did Ch2 instead, both amplitude and offsets being set without a problem, then went back to Ch1 offsets, which also completed without further hiccups.  However, pressing either "End Calibration" button then causes another crash as in screen3.jpg (clicking "OK" shuts down the software).

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 04, 2018, 04:14:56 pm
Back on waveform files, the FY6600 will accept CSV files, but ONLY if the file contains nothing but the data values up to a maximum of 8192 points.  Clearing out the other cells and info left by wafeform creation software only takes a few seconds in the case of those uploaded by soundtec, so it's just the same as copying the data values into a new text file.  In fact, the software accepts *.txt files as well, so there's no need even ro rename them to *.fy.

I didn't bother uploading the files to the FY6600, soundtec, as the sinc-pulse and triangle waveforms you did are obviously going to display perfectly well from what I saw in the CSV files and the Waveform Window of the control software.  The big square wave file, naturally enough, became a DC waveform as only half of the file could be read in.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 04, 2018, 09:21:43 pm
Is it known what aspect of the PLL is causing this jitter?

How do you mean, what aspect?  It's simply the maximum resolution of the clock. Its like asking why a picture with a 1024 resolution has blocks that are 1/1024 width.
Of course, even a picture you can "anti alias", basically faking a fuzzy edge by playing with gray scale, and that is why the sine wave appears better. But hard edges are simply either on one tick of the 250MHz clock, or on the next tick 4ns later. Never in the middle.

To fix this (for hard edges) you'd need to vary the base frequency resolution along with the desired frequency, like with a programmable clock, or with a VCO based clock instead of a PLL based clock. Or heavily overshoot the clock resolution, like sample it on 1GS/s instead of 250MS/s. But that is all done in the FPGA.

That makes sense, excellent explanation thank you.  I'm assuming that a 1GS/s sample rate is out of the question for this particular FPGA part. Forgive my rather basic line of questioning, I'm not an expert in RF engineering.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 05, 2018, 06:33:20 am
There was this (I think) russian guy who said he was familiar with this FPGA and that it did have some possibly better clock options. But we have no source for the FPGA, so it would mean re-implement the entire FPGA firmware from scratch. Kind of like what Fremen67 is doing for the CPU. But that will be a massive undertaking so not likely someone with the right skillset picks that up.

Practically, I think you should accept the 4ns thing as a given fact.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gandalf_Sr on May 05, 2018, 09:52:56 am
... I have also always been frugal (aka a cheap bastard) and am still amazed at myself how I buy a cheap Chinese AWG when a) I can easily afford the proper stuff and b) I seem to spend relatively high amounts on patching up said AWG with PSU, OpAmps, etc. Truth is, I think I enjoy the challenge and frustration of making things work for pennies on the dollar.
I'm in the same category, I have a large box full of such half-assed projects but, this time, I was able to talk myself out of buying yet another prototype.  When I first saw this thread I thought "wow, a dual AWG for $100 but the additional cost in 'upgrades', shipping, and time probably triples that price.

If you want to generate dual arbitrary waveforms and have a good range of built-in useful waveforms (e.g. ECG), buy a debugged, working product like a Rigol DG1022Z (which I did for around $325.)

If you want to spend about the same amount of money (in the end), waste hours tinkering, changing ICs, waiting 3 weeks for cheap programmers to arrive from China, and end up with something that sort of does the job, buy the FY6600/FY6800.

Your choice.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 05, 2018, 10:09:22 am

I'm in the same category, I have a large box full of such half-assed projects but, this time, I was able to talk myself out of buying yet another prototype.  When I first saw this thread I thought "wow, a dual AWG for $100 but the additional cost in 'upgrades', shipping, and time probably triples that price.

If you want to generate dual arbitrary waveforms and have a good range of built-in useful waveforms (e.g. ECG), buy a debugged, working product like a Rigol DG1022Z (which I did for around $325.)

If you want to spend about the same amount of money (in the end), waste hours tinkering, changing ICs, waiting 3 weeks for cheap programmers to arrive from China, and end up with something that sort of does the job, buy the FY6600/FY6800.

Your choice.

Uhmm, a 60MHz Rigol is SEVEN times more expensive compared with the equivalent Feeltech, it has a sampling rate of 200Ms/s instead of 250Ms/s and in the end is still a Chinese product.
Also it doesn't have our Freemen excellent software that is getting better by the day  ^-^. and you have to put a lot of money in the linear PSU and op amps to gome even closer to 25% of the RIgol.

 Cheers,
 DC1MC



 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 05, 2018, 12:36:18 pm
If you are going to quote price comparisons, Gandalf, at least give like for like, eg at current UK prices:-

Feeltech FY6600 (60MHz) - £85

RIGOL DG1062Z (60MHz) - £654

My upgrades have cost me about £50 on top of the £85, so £135 in total: still only just over 20% of the cost of the RIGOL.  Yes, the RIGOL has a some extra features, but is it really worth five times as much??

If my FY6600 dies on me I can buy another and transfer the mods in an hour for nothing.  I'm happy with that, and so, I would imagine, are most of the users on here.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 05, 2018, 04:49:32 pm
If you want to generate dual arbitrary waveforms and have a good range of built-in useful waveforms (e.g. ECG), buy a debugged, working product like a Rigol DG1022Z (which I did for around $325.)

What I would find really interesting (not even out of spite or to counter arguments, but really I am interested to know) is if your Rigol also has this base-clock-resolution jitter problem. In other words, does your 200MS/s Rigol show 5ns jitter on vertical edges.

It may be a bit harder to tell, as you only have a 25MHz device, and you'd have to check on a non-dividable frequency, so not 20MHz or 25MHz but maybe 22MHz.
Do you see anything like the yellow wave in this post (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1335080/#msg1335080), but with 5ns distance instead of 4ns, on square waves or arbitrary waves with hard vertical edges?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on May 05, 2018, 05:29:26 pm
... I have also always been frugal (aka a cheap bastard) and am still amazed at myself how I buy a cheap Chinese AWG when a) I can easily afford the proper stuff and b) I seem to spend relatively high amounts on patching up said AWG with PSU, OpAmps, etc. Truth is, I think I enjoy the challenge and frustration of making things work for pennies on the dollar.
I'm in the same category, I have a large box full of such half-assed projects but, this time, I was able to talk myself out of buying yet another prototype.  When I first saw this thread I thought "wow, a dual AWG for $100 but the additional cost in 'upgrades', shipping, and time probably triples that price.

If you want to generate dual arbitrary waveforms and have a good range of built-in useful waveforms (e.g. ECG), buy a debugged, working product like a Rigol DG1022Z (which I did for around $325.)

If you want to spend about the same amount of money (in the end), waste hours tinkering, changing ICs, waiting 3 weeks for cheap programmers to arrive from China, and end up with something that sort of does the job, buy the FY6600/FY6800.

Your choice.
This isn't an entirely accurate statement. The Feeltech generators will do fine as a basic function generator. For many tasks you don't really need a generator with many bells and whistles so the Rigol and Siglent generators (which aren't free of flaws) are just not worth the money if all you need are basic waveforms.
However some go way overboard by fitting a completely new PSU and so on in their Feeltech generator turning it into a neat tinkering project. In the Feeltech FY3200S I have I fitted a grounded mains inlet and a wire from the earth connection of the PSU to earth to get rid of the leakage problem. That was a minor amount of work. The FY6800 seems to be a newer design with a grounded mains inlet so it is different compared to the previous generators. I guess we'll be seeing an FY6800 teardown pop-up in the near future.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: kahe40 on May 05, 2018, 07:09:07 pm
... some go way overboard by fitting a completely new PSU and so on ...

really funny, each time they connect the BNC-cable to their scope, or USB-cable to their PC,
it is grounded - gratis - no need for nothing.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on May 05, 2018, 07:46:10 pm
really funny, each time they connect the BNC-cable to their scope, or USB-cable to their PC,
it is grounded - gratis - no need for nothing.
Were those roughly 60 volts on the neutral part of the BNC on the generator imaginary too?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on May 05, 2018, 07:51:36 pm
... some go way overboard by fitting a completely new PSU and so on ...

really funny, each time they connect the BNC-cable to their scope, or USB-cable to their PC,
it is grounded - gratis - no need for nothing.
The problem is that until it is connected to ground you have 60V to 120V AC floating around and that will kill your circuits for sure.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 05, 2018, 08:48:41 pm
The problem is that until it is connected to ground you have 60V to 120V AC floating around and that will kill your circuits for sure.

That is a bit of an exaggeration. It is only capable of a few uA, and may kill the most sensitive of test circuits, but it is not a "sure" thing.

Any 2-prong power supply has this problem, it is not necessarily due to bad construction, but caused by the regulatory required Y Cap. They all will float in the middle at zero load, but even adding a DMM probe will pull it down from 115V (middle of 230V) to 60V or 40V or less, depending on how big a Y-cap and how much impedance your DMM has.

That is not to say I like this, hence I also added a 3 prong, rerouted the Y cap to that, and put on a 1M preload. But saying "kill for sure" is a bit too harsh a statement. That's like saying your USB chargers "for sure" kill all your devices (yes, most USB chargers also have this)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 05, 2018, 10:23:06 pm
I think if you've gone with the op amp upgrade its well worth doing something about more current on the +/- rails ,a pair of 3095's pull twice the current of the dual channel 30021 that its replacing . As far as using all three pads with two single channel and one dual op amp it would be do-able but external output mixing resistors for each op amp would have to be arranged and the final output padding resistor would need to be adjusted. With the new TI op amp  being able to draw 350ma paralleling op amps hardly seems nessesary unless you want super low load drive.

Still waiting on the 6800 and what ever surprises it brings ,
I might try a 1:1 isolation transformer on this chassis ,and maybe two seperate switched rails for 5V and +/- .

Dave's right , for the 55 euro's it cost (15mhz model)its well up with competition ,and the extra spend on psu is well worth it,the time ,well it depends on how much you have to hand

I'm having a look at different proprietry software relating to AWG's ,its all a bit samey,B+K Wave express ,Ultrawave (Rigol),Arbexpress(Tek) and Easywave (Siglent).

I found this ,Im not sure if its related to Feeltech or not ,I also cant figure out what its supposed to be doing,
https://www.spooky2.com/newmodel/ (https://www.spooky2.com/newmodel/)
Does look a bit like the fy2300 though, has someone reinvented it as a 'Tens' machine  or something ? theres all kinds of extravagant claims on the website about it being used for cancer treatment , :-//
Any voulenteers for some pwm alphawave experiments? a few crock clips and leads should do it  :D


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gregg on May 06, 2018, 02:15:04 am
First I would like to thank all of those who have actively participated in his thread and contributed toward making the FY6600 great (sometime, maybe). So far, it has been a great learning experience enabling my cheapskate self to possess a bargain signal generator. 
The last time eBay offered a 15% off coupon, I sprung for a US warehoused 60 MHz that had the latest firmware.  I had been eyeing them for some time, thanks to this thread.
I’ll have to post pictures when I get it back together after installing the THS3095 op amps and a better heat sink.  I managed to get everything in the case in a layout similar to the picture Dave posted including a 40mm 12v fan driven off the second 9v transformer winding.
 
Parts & Cost list:
$87.46 FY6600-60 eBay (with 15% off coupon) US stock V3.2.1
$21.08 30va R-core 18v 18v 9v 9v Transformer eBay (with 15% off coupon)
$6.99 LM317 LM337 ac to dc regulator kit eBay
$1.58 LM317 ac to dc regulator kit eBay
$7.66 two THS3095 op-amps eBay
$124.77 Total
40mm fan and rectifier, capacitor, resistor from my stock
C14 power inlet, fuse holder and fuse from my stock
Fasteners, stand offs, wire, etc. all from my stock
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 06, 2018, 10:48:00 am
Theres no doubt about it for the budget concious who dont mind doing a few uprgades the FY is a great deal .
It would be nice to see a like for like waveform comparison with the equivalent 60mhz Rigol unit and see if theres a difference .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gandalf_Sr on May 06, 2018, 01:18:51 pm
First I would like to thank all of those who have actively participated in his thread and contributed toward making the FY6600 great (sometime, maybe). So far, it has been a great learning experience enabling my cheapskate self to possess a bargain signal generator. 
The last time eBay offered a 15% off coupon, I sprung for a US warehoused 60 MHz that had the latest firmware.  I had been eyeing them for some time, thanks to this thread.
I’ll have to post pictures when I get it back together after installing the THS3095 op amps and a better heat sink.  I managed to get everything in the case in a layout similar to the picture Dave posted including a 40mm 12v fan driven off the second 9v transformer winding.
 
Parts & Cost list:
$87.46 FY6600-60 eBay (with 15% off coupon) US stock V3.2.1
$21.08 30va R-core 18v 18v 9v 9v Transformer eBay (with 15% off coupon)
$6.99 LM317 LM337 ac to dc regulator kit eBay
$1.58 LM317 ac to dc regulator kit eBay
$7.66 two THS3095 op-amps eBay
$124.77 Total
40mm fan and rectifier, capacitor, resistor from my stock
C14 power inlet, fuse holder and fuse from my stock
Fasteners, stand offs, wire, etc. all from my stock

Time: 10 hours at $130 per hour = $1,300.00
Shipping for all the above (est)    =     $50.00
Cost of parts                              =  $127.44
Total                                          = $1,477.44
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on May 06, 2018, 03:27:18 pm
First I would like to thank all of those who have actively participated in his thread and contributed toward making the FY6600 great (sometime, maybe). So far, it has been a great learning experience enabling my cheapskate self to possess a bargain signal generator. 
The last time eBay offered a 15% off coupon, I sprung for a US warehoused 60 MHz that had the latest firmware.  I had been eyeing them for some time, thanks to this thread.
I’ll have to post pictures when I get it back together after installing the THS3095 op amps and a better heat sink.  I managed to get everything in the case in a layout similar to the picture Dave posted including a 40mm 12v fan driven off the second 9v transformer winding.
 
Parts & Cost list:
$87.46 FY6600-60 eBay (with 15% off coupon) US stock V3.2.1
$21.08 30va R-core 18v 18v 9v 9v Transformer eBay (with 15% off coupon)
$6.99 LM317 LM337 ac to dc regulator kit eBay
$1.58 LM317 ac to dc regulator kit eBay
$7.66 two THS3095 op-amps eBay
$124.77 Total
40mm fan and rectifier, capacitor, resistor from my stock
C14 power inlet, fuse holder and fuse from my stock
Fasteners, stand offs, wire, etc. all from my stock

Time: 10 hours at $130 per hour = $1,300.00
Shipping for all the above (est)    =     $50.00
Cost of parts                              =  $127.44
Total                                          = $1,477.44
That $130/h depends on where one lives, what one does for work (or if one even has a work), etc., and is the price one would perhaps pay to some company to do it, less than that if it was someone being paid personally. When one does it by oneself, the cost of time should be the amount one would get less income, considering taxes and all.. Typically closer to $15/h :P  If I'd do just the main recommended changes as is, without more thinking, the total time would be somewhere between 3-5 hours (+perhaps 1 hour for cleaning up).  And of course, can you really put a "cost" on free time, especially if what needs to be done is the same stuff you'd do anyway as a hobby.  But, lets give it a rounded $75 worth (of my time).

E.g. a typical student hobbyist with no work, that "work time cost" would be zero.

Shipping for parts, in my case (on the competing product, but basically corresponding changes), has so far been zero. I even had to order another shipment after realizing a mistake in my first design, and none of the orders were from ebay with its flood of free shipping parts (mostly digikey, couple local stores). Still zero... Of course, the shipment costs are baked into the part costs, but the part costs listed already are close enough what I have been paying, so I'd assume those prices also include shipping, or at least could include.  Granted, I did order other stuff at the same time, pushing the order totals above the free shipment limit, but I'd think most hobbyist can and would do so, too.  (Third order/shipment is possibly on the works, but I have to test some things with the already acquired parts before choosing what (or if anything) I will still need. I have so much other parts in my "to buy"-queue that all my digikey orders will be free for the foreseeable future.)


So, for me, the total would be around $200 even with the "work cost" (though I would really consider it a hobby project, so that $125 is better, with zero shipping cost). As it would be for large share of students and all unemployed people, even if they would not consider it a hobby.

That nearly $1.500 estimate is just nonsense. The only case where it would apply is if one is doing just one unit in a company, spending workers' time for it. No sane company would do that, so it would be nonsense either way :P. And even then, it is actually not the "cost", but "cost + less potential income" - a difference, which, it seems, 99% of company leaders do not understand.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 06, 2018, 03:27:43 pm
Time: 10 hours at $130 per hour = $1,300.00
Shipping for all the above (est)    =     $50.00
Cost of parts                              =  $127.44
Total                                          = $1,477.44

Your salary is $270,000 dollars a year? Where exactly do you come up with $130 per hour?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on May 06, 2018, 03:30:55 pm
Time: 10 hours at $130 per hour = $1,300.00
Shipping for all the above (est)    =     $50.00
Cost of parts                              =  $127.44
Total                                          = $1,477.44
While I mostly agree with your reasoning, it would also mean I couldn't pick up a book or learn a new skill any more. I couldn't afford either.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gregg on May 06, 2018, 04:53:17 pm
Quote
Parts & Cost list:
$87.46 FY6600-60 eBay (with 15% off coupon) US stock V3.2.1
$21.08 30va R-core 18v 18v 9v 9v Transformer eBay (with 15% off coupon)
$6.99 LM317 LM337 ac to dc regulator kit eBay
$1.58 LM317 ac to dc regulator kit eBay
$7.66 two THS3095 op-amps eBay
$124.77 Total
40mm fan and rectifier, capacitor, resistor from my stock
C14 power inlet, fuse holder and fuse from my stock
Fasteners, stand offs, wire, etc. all from my stock

FYI: Shipping was included in the above list.
I am retired and can get part time consulting jobs that pay more than $130/hr they are few and far between; the upside is I get to pick and choose; but the extra income is welcomed.
I bought the FY6600 for entertainment and learning value at a reasonable price.  Plus I thought the REAL contributors to this thread were doing amazing work and the few naysayers didn't have good enough arguments not to go down this rabbit hole.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 06, 2018, 05:28:15 pm
Hey All,

I went through all (read most) of the pages but I couldn't figure out if Ver. 3.2 fixed the FP corruption issue. I apologise if I missed something.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 06, 2018, 09:03:19 pm
We're as sure as we can be that v3.2 fixed the problem.  No-one with a 3.2 device has ever reported any problems with it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 06, 2018, 09:36:37 pm
Gandalf reminds me of someone who used to post in another forum of which I'm a member - nothing to do with electronics, but still just a hobbyist group.  We'd be discussing the intricacies and techniques of putting together another project, which would usually involve some reasonably small outlay for various parts and materials, and a fair amount of time for cutting and assembly (you know, the "hobby" part of the project), and this character would invariably chime in with something along the lines of, "Why are you wasting your time doing this when you can buy one for xxx dollars?" and would usually end by shouting "I REPEAT, HOW MUCH DO YOU VALUE YOUR TIME?".  The concept of a hobby and making something for pleasure, and retired people having lots of spare time to use as they see fit, all of which is free of charge, was completely alien to him and utterly beyond his comprehension - every waking hour (and probably sleeping time, too) had to have a price on it. 

He disappeared eventually, after everyone stopped replying to his posts.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 06, 2018, 11:19:52 pm
We're as sure as we can be that v3.2 fixed the problem.  No-one with a 3.2 device has ever reported any problems with it.
Thanks,

Do you know if Banggood ships 3.2 or earlier?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 07, 2018, 01:24:46 am
I got my v3.2 last December, so I'd be very surprised if there are any earlier versions still in circulation.  v3.2.1 is the latest firmware, and it's been around for a couple of months as well.  The chances of getting a 3,1 from any supplier must be miniscule by now.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 07, 2018, 02:14:03 am
Thanks Dave!

I just ordered one from BG. We'll see. Damn, another improvement project.  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 07, 2018, 12:21:34 pm
...and retired people having lots of spare time to use as they see fit...
Well, this thread is good for my ego. I used to think of myself as one of the older guys, now I am starting to consider myself young... well, less old anyway.

But yes, its very simple, Gandalf_Sr is correct if your viewpoint is: "wasting hours tinkering" => this is not your device.
However, if you feel like "spending hours tinkering" => this may very well be a good device for you.

I do wish though he would answer the 200MHz/5ns jitter question for his Rigol.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 07, 2018, 01:52:31 pm
I do wish though he would answer the 200MHz/5ns jitter question for his Rigol.

I actually have an answer for your question: its in the datasheet!

Look at page 3 of the datasheet for the DG1022 (http://beyondmeasure.rigoltech.com/acton/attachment/1579/f-001b/0/-/-/-/-/file.pdf).

It states that the jitter for non-sinusoidal waveforms is 6 ns!  So we are actually better than the jitter for the Rigol 1022G instrument, which has a retail of $250-$300 with a maximum sine frequency of 20 MHz, and a 100 MS/s sample rate @ 14 bits of vertical resolution.

The DG1022Z has an RMS jitter of 200 PS (http://beyondmeasure.rigoltech.com/acton/attachment/1579/f-033c/0/-/-/-/-/file.pdf), and it costs $300-$360 with a maximum sine frequency of 25 MHz, a 200 MS/s sample rate, and a 14 bit vertical resolution.

For reference, our generator has a 60 MHz (90 with bluepill, if I remember correctly) maximum sine frequency, a 250 MS/s sample rate, 14 bit vertical resolution, and 4 ns jitter, and with upgrades it only costs ~$150.

That makes it better than Rigol's lowest cost generator on a performance per dollar level, and competitive with their mid range generators in terms of specs while significantly beating the price point.

I am certainly no longer worried about the jitter, as it appears to be a feature consistent with other generators in its class, and comes with a greatly reduced price point.

EDIT: Just as a comparison, the siglent generators are as follows:

SDG830 (http://www.siglentamerica.com/wp-content/uploads/dlm_uploads/2017/10/SDG800_DataSheet_DS02008-E02D.pdf) has 500 ps jitter, 30 MHz max sine freq, 14 bit vertical resolution, and 125 MS/s for $330

SDG1050 (http://www.siglentamerica.com/wp-content/uploads/dlm_uploads/2017/10/SDG1000_DataSheet_DS02010-E08A.pdf) claims 40 ps jitter @ 25 MHz in the datasheet (I dont believe that, because the jitter is 8 ns for pulses), 25 MHz max sine freq, 14 bit vertical resolution, and 125 MS/s for $509

Still winning against Rigol & Siglent.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 07, 2018, 04:17:55 pm
Thanks for that comparison SMB , so really theres not much to say other than the Feeltech is great value for money ,either stock from the factory or with your own chosen upgrades .I can understand people might try to knock the Feeltech after paying several times the price for units which on paper at least seem to have worse specs .To be honest even if money was no object the feeltech would still be top of my list ,its kinda forced us all to take account and learn more about whats going on inside ,where if we had top of the line, no expense spared gear we might not have learned nearly so much about ARB waveform synthesis.

Sure if your time is worth 130 bucks an hour ,why not just go out and buy the latest and greatest from a prestige mark ,but Ill bet most of us on lower wages or retired with time on hand ,wouldnt trade back the time for money, lessons learned and friends made here, I know I wouldnt . Must get my head stuck into blue pill soon to access the extra 'goodies' Fremen has programmed in for us .If someone can point me the location of the blue pill set up/wiring for the FY6600 that would be great.
Cheers all once again and many thanks for the good spirited contributions that made this project come together.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on May 07, 2018, 04:20:42 pm
Sure if your time is worth 130 bucks an hour ,why not just go out and buy the latest and greatest from a prestige mark
Why bother with building something at all if you make that kind of money? For $130/h you can hire someone to build the projects for you!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 07, 2018, 04:21:51 pm
Thanks SMB784. I guess I could have looked there myself.

So nothing special / smart in the Rigol.

The Siglents datasheet have 8ns for arbitrary, matches exactly their 125MS/s spec. But square seems very good with 500ps. Are they doing something smart?
It is possible the square and pulse are non-clock based, somehow. Maybe on an internal FPGA timer based (which is then internally a higher clock of course, but you cannot call that MS/s)

But no: I think no, just some spec trickery:
SGD800: 500ps + 0.001% (seems good) but 24ns rise/fall and 20ns asymmetric
So how do you measure a 500ps jitter if you have 24ns rise/fall as well as a 20ns PWM variation?


The timer based idea is a good one though. If I were to build a FPGA AWG from scratch, I may use that for square/pulse signals. Internal 1GHz (or higher) timer that drives the DAC with variable duration, so that even though only a 250MHz DAC, you can still have 1ns or better resolution.


----

Anyway, that means this is a good device, even with the tinker necessities. Except for the absolute and utter lack of support and warranty.
And to be honest, I think there is only one *must do* tinker necessity, and that is the grounding. The rest (crystal, opamp, psu) is only if you want to.
But to repeat: absolutely no warranty whatsoever.  If you want warrenty, go somewhere else.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on May 07, 2018, 04:25:39 pm
The Siglents datasheet have 8ns for arbitrary, matches exactly their 125MS/s spec. But square seems very good with 500ps. Are they doing something smart?
The first generation SDG1000 used a comparator fed with a sine wave to make a square wave. I doubt the newer models will be much different.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 07, 2018, 04:27:26 pm
Ah. Yes, that is also pretty smart. Yes, that may be it.
still makes the 500ps a bit of a statistical thing though.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 07, 2018, 04:38:30 pm
Ah. Yes, that is also pretty smart. Yes, that may be it.
still makes the 500ps a bit of a statistical thing though.

Do you think that is something that we could implement within the existing FPGA fabric?  Does anyone have any idea how much FPGA resources are left in the FY6600 generator's stock configuration?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 07, 2018, 04:51:42 pm
I am assuming we cannot do anything to the FPGA, other then program completely it from scratch.
But then again, I know pretty much nothing about FPGA programming. If you look at the start of this thread, I already made several FPGA assumptions that turned out to be false. (at least I learned a little)

What I do know is we can easily make a sine-into-gate wave ourselves. In fact, I think it is already there, on the TTL and/or SYNC-OUT ports.
We may need to replace the standard gate with a faster one, but after that we could add an extra OpAmp amplifier. Or even feed the gate output back into present opamp by means of an extra relay (so Fremen67 can control it with a spare GPIO, and the amplitude setting works)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 07, 2018, 05:42:51 pm
A bug report for the 0.6 firmware/software package:

Nothing wrong with the sweep module, but I used a different blue pill board for the 0.6 firmware and had to redo the calibration process.  Ch1 Amplitude went ok, but the control software crashed repeatedly while trying to do the Ch1 Offsets (see screen1.jpg).  Restarting the control software brought it back in the configuration in screen2.jpg, and resetting the blue pill brought it back in normal default mode.  I gave up on Ch1 and did Ch2 instead, both amplitude and offsets being set without a problem, then went back to Ch1 offsets, which also completed without further hiccups.  However, pressing either "End Calibration" button then causes another crash as in screen3.jpg (clicking "OK" shuts down the software).

Dave
Thank you for the feedback. I think I got it. It should not happen when you go first to the configuration tab and then only to the calibration tab. I wanted to speed-up the startup and only read configuration data when needed.... which I need in the calibration tab :-[. I will correct it in the next release  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 07, 2018, 08:24:42 pm
Anyone with a V3.2.1 able to dump the flash memory and post it?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Bob Sava on May 07, 2018, 09:07:08 pm
With all talk about upgrades I've been thinking why I should upgrade power supply and why?  From what I've been reading it seems to me that replacing power supply would only make visible difference after opamp upgrade for higher output current and rail voltages.

I understand that smps it pretty barebone with undersized or missing capacitors but what is the manifestation of it's shortcomings? 





Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on May 07, 2018, 09:37:06 pm
Replacing the smpsu by a linear one has the main reason in getting rid of the phantom voltage by keeping the floating ground. With the original setup you can measure high ac voltage from bnc ground to mains earth. This is because of the Y capacitors in a smpsu.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 07, 2018, 10:31:32 pm
If someone can point me the location of the blue pill set up/wiring for the FY6600 that would be great.

The wiring setup is here, soundtec - https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1441974/#msg1441974 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1441974/#msg1441974)

I assume you've got one of the aluminium shell USB dongles, and have downloaded the programming utility from the ST website?  A word about those dongles for the unwary - there are at least two types on sale, and I've got versions marked 'ST' and 'XTW' (as well as two other non-shelled variants).  At first sight the ST and XTW dongles look identical, but the pinouts are different, so any wiring diagram you see on the web may not apply to the one you've got.  Fundamentally, four connections are needed from the dongle to the blue pill board for the programming part: IO, CLK, 3.3v and GND, so just connect like to like and upload fremen67's firmware to the blue pill (five seconds to complete).  If you get any error messages, check your wiring, then check it again :)  Once the blue pill is programmed you don't need the dongle, so disconnect it and follow the wiring in the photos to connect the blue pill to the FY6600 main board - a single piece of 12 way M-F ribbon cable makes a nice tidy job and gives good connections (no need for breadboarding or veroboard with v3.2 boxes).  Lastly, don't forget the standard USB cable between the FY6600 and your PC, as I have on a couple of occasions  :-[   (Photos of my BP cable attached for reference.)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Bob Sava on May 08, 2018, 12:44:38 am
Is Stm32f103c8t6 what works with bluepill?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 08, 2018, 01:24:57 am
That's indeed the processor chip that's used on the blue pill boards.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on May 08, 2018, 04:06:44 am
With all talk about upgrades I've been thinking why I should upgrade power supply and why? 
Those were my thoughts too. Then I noticed the distortion of smaller signals caused by the SMPS interference. It radiates a lot, and maybe there are ground bounce or ground loops. A linear supply should eliminate the interference. The first attached photo shows the FY6600 output signal when the amplitude is set to zero. The second shows the distortion when outputting 1V p-p.
(Edit. Photos attached)

Question for those who have replaced the SMPS - what is an acceptable ripple voltage on the +/- 12V and +5V outputs?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 08, 2018, 05:33:10 am
@plb, holly crap,  :o this is really bad !!!

Not even with the original POS mine didn't have that bad output, something is VERY wrong, at 10KHz on a 50ohm terminator with a T and connected to the scope, the signal looks perfect, no distortion is visible to the naked eye.


 DC1MC
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 08, 2018, 06:18:23 am
Yeah, that is not a normal output, not even for a unmodified FY6600
You have an extra special bad one.

I never replaced my PSU, only moved Y-cap to ground and added 1M resistor, and my 1Vpp - 50 Ohm looks much better.
From memory, it looked much better before the Y-cap mod too.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on May 08, 2018, 06:39:54 am
Note, plb used apparently 10x probe, not 50ohm connection. (Also, if it indeed was a probe, how was it connected? With the ground clip "loop antenna" or with the small coil+spike?) That might explain some of the difference seen on the scope view. At least that is something I remember to be aware of from the videos about measuring power supply noise/ripple, and while this isn't a PSU, I think the idea still applies in this case.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 08, 2018, 09:59:24 am
Hi PLB ,If the amplitude is set to zero then the unit shorts the bnc connector to ground via relay , so what your measuring in any case is whats induced into the loop .
On the highest amplitude range ie 5 volts and above and frequency set to zero I was measuring 150 microvolts into hi z at the bnc connector, this measurment was taken after the psu was replaced .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on May 08, 2018, 11:58:19 am
From memory, it looked much better before the Y-cap mod too.
Thanks Cybermaus. This made me go back to basics. I had grounded the common as soon as I got the unit, and that was the configuration for those photos. When I removed the ground, the waveform improved significantly. I now have a 1K resistor in there that leaves the signal as clean as an open circuit.

Note, plb used apparently 10x probe, not 50ohm connection. (Also, if it indeed was a probe, how was it connected? With the ground clip "loop antenna" or with the small coil+spike?) That might explain some of the difference seen on the scope view.
Correct about the probe Bugi. However the SMPS frequency is 50KHz. Even considering harmonics, that's not really "loop antenna" territory.

Hi PLB ,If the amplitude is set to zero then the unit shorts the bnc connector to ground via relay , so what your measuring in any case is whats induced into the loop .
On the highest amplitude range ie 5 volts and above and frequency set to zero I was measuring 150 microvolts into hi z at the bnc connector, this measurment was taken after the psu was replaced .
Not quite, Soundtec. There is zero pickup by the "loop antenna" until I move it adjacent to the SMPS . Good point about the relay though. I hadn't noticed. Obviously what I'm seeing is being induced into the PCB and relay. Your result looks excellent though. Thanks.

Net result is that I'll stick to the Cybermaus solution, as modified, at least until I've finished my current project and am looking for something to do. Then I might consider a linear supply if someone can advise on what ripple is acceptable...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 08, 2018, 12:55:15 pm
Ok, but note I put a 1M resistor, not a 1K one.

The reason is that I want to be able to use the output as float if needed. I read somewhere even brand devices with floating output really do have a 1M~10M resistor in there.
I guess an unforeseen but pleasant extra advantage is it will indeed reduce any ground loop induction.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 08, 2018, 02:17:07 pm
Hi PLB ,If the amplitude is set to zero then the unit shorts the bnc connector to ground via relay , so what your measuring in any case is whats induced into the loop .
On the highest amplitude range ie 5 volts and above and frequency set to zero I was measuring 150 microvolts into hi z at the bnc connector, this measurment was taken after the psu was replaced .
Not quite, Soundtec. There is zero pickup by the "loop antenna" until I move it adjacent to the SMPS . Good point about the relay though. I hadn't noticed. Obviously what I'm seeing is being induced into the PCB and relay. Your result looks excellent though. Thanks.
Well, not sure there are relays for shorting the BNC connectors to ground. It does not show up on the schematics... When amplitude is set to 0, opamps have only a 0 setpoint...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: plb on May 08, 2018, 09:03:58 pm
Well, not sure there are relays for shorting the BNC connectors to ground. It does not show up on the schematics... When amplitude is set to 0, opamps have only a 0 setpoint...
There is a schematic available? Can you point me to it?
Somewhere back in the 54 pages of this thread there was a start made on a main board schematic. Did I miss the final result?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 08, 2018, 10:09:59 pm
Here it is PLB ,
might as well just post it again ,

if you look up github FY6600 Der Kami's page is there with most of the info
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 08, 2018, 10:20:14 pm
Just looking back on the schem ,maybe I was wrong about the outputs being grounded at zero HZ frequency output , depending on the range your using though the output attenuator might be engaged .So I wonder does the muting I hear when I switch frequency to zero happen digitally . I might be able to do some more meaningfull tests on my friends bench soon ,maybe a comparison between a modded fy6600 and an unmodded fy6800 might be a plan .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on May 08, 2018, 11:31:32 pm
Peeking in the thread, after some months... interesting guys, how far it has gone! Thank you for the schematic, that was a tough one I guess.

Seems the VCO BNC input is sampled by the ADC in the MCU on the front board?

Also, wazzup with the THS3002? It seems you can barely find a datasheet for it. (Old 1999 revision listed by only some Chinese site with a download speed of a dial up...)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 09, 2018, 05:26:09 am
you need to look for the THS3001 data sheet, the THS3002 is just the twin variant and described in the same document.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on May 09, 2018, 08:22:25 am
Nope. Texas Instruments website does not give shit about THS3002. Only 3001 is listed and the datasheet (last revision 2009) lists only THS3001, not THS3002.

The only place THS3002 is listed is in this datasheet from 1992, where it is listed as "product review". Guessing it never took off, was not produced, or only for a short time.

http://pdf.datasheetcatalog.com/datasheets/700/322243_DS.pdf (http://pdf.datasheetcatalog.com/datasheets/700/322243_DS.pdf)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on May 09, 2018, 09:11:29 am
This is because THS3002 has been discontinued long time ago - last datasheet is from 1999.

Anyway we now have 3091/95 and 3491 to play with :-)

No need to investigate further what happened to 3002. I even suspect it to be a knock-off of some sort but I do not have the time to compare the performance to two real 3001 on the same board.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 09, 2018, 10:03:50 am
This is the one that usually comes up for me: http://pdf.datasheetcatalog.com/datasheets/700/322243_DS.pdf (http://pdf.datasheetcatalog.com/datasheets/700/322243_DS.pdf)

It is from 1999, indeed, but not product review or anything. And 1999 is not so long ago guys. I remember it well. Y2K for business, new happy dawn of a new millennium, with communist/nuclear threat gone, brave new world with free information coming up and all.


Anyway, its not really important. Its 100% sure an old device, its 50% sure either a clone, or maybe cheap old stock. And its 100% sure we have better devices.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on May 09, 2018, 11:02:42 am
It took a while indeed, but worth the time. Still need to do the counter input though.  No prio with the nice weather here  8)

The VCO is indeed directly connected to the mcu. Just have a look here (https://github.com/DerKammi/FY6600-15-30-50-60M) for the frontpanel schematics also.

Peeking in the thread, after some months... interesting guys, how far it has gone! Thank you for the schematic, that was a tough one I guess.

Seems the VCO BNC input is sampled by the ADC in the MCU on the front board?

Also, wazzup with the THS3002? It seems you can barely find a datasheet for it. (Old 1999 revision listed by only some Chinese site with a download speed of a dial up...)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on May 09, 2018, 11:57:18 am
Well, had a brief look at the front schematic:  BOOT0 pin should NOT and NEVER float.  Maybe a connection to ground is missing in the schematic.  And the pullup on NRST is also not a recommended practice**. But anyway, thanks for the schematic also, I see how the VCO is implemented. However, they clamp it to a wrong level voltage using the BAV99. Should be clamped to 3V3 not 5V.

The whole generator thingy seems to be good to have a complete HW redesign - especially with regards to the PCB layout, which is a bit horrid in soem areas. (for exampel the DAC filters, etc..) It would certainly make it a tad better.

Y.

//EDIT: ** for STM32 micros, the pullup on NRST is not recommended.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 09, 2018, 12:06:28 pm
Stupid question, the blue pill board doesn't drive the display...yet, it's controlled from the PC only?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on May 09, 2018, 12:11:23 pm
Ohh sure there will be some mistakes in the schematic, no doubt :) I'll beep them out and correct the file when I can. The clamp diode sure make sense :)

I agree on the layout. The return paths are non existent in some parts of the board.

@Miti: Correct
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mozee on May 09, 2018, 06:40:02 pm
Amazing job guys!! Really this is the least one can say!
Did the FY6800 show up yet? where to buy it if so?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 09, 2018, 07:43:15 pm
I should be due a FY6800 once they become available ,but it doesnt look like there on sale to the general public just yet .
I also wonder about the plethora of rebranded Fy6600's doing the rounds of late ,Adoner(kebab?)and  Kuman are among them,I wonder are these knock offs or simply a rebrand made by Feeltech.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on May 09, 2018, 08:04:43 pm
Just to make sure, I did say correct, but this will hopefully change in the future as the plan is to replace the firmware of the unit with fremen his creation. But how and when it unknown.

Stupid question, the blue pill board doesn't drive the display...yet, it's controlled from the PC only?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mozee on May 10, 2018, 11:37:01 am
Did anyone try these rebrands (copies?)? I saw a listing of the same unit made by Kooletron if I'm not worng spilling it  :-//
anyways, If they offer a good warranty then that will be really good
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 10, 2018, 12:12:06 pm
The Koolertron units are rebadged JDS6600s, not Feeltech FY6600s, and are sold with a 33% markup in the UK.  The Kuman units are probably rebadged Feeltech products (they quote the same Feeltech model numbers in the descriptions, even though they don't appear on the cases), and again they have a huge markup over the Feeltech versions.  However, I don't imagine the electronics inside the boxes will be any different from the JDS and Feeltech originals.  The Kuman units still have the two pin mains connector on the back, so they are hardly "improved" Feeltech versions.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 10, 2018, 02:56:08 pm
What I do know is we can easily make a sine-into-gate wave ourselves. In fact, I think it is already there, on the TTL and/or SYNC-OUT ports.
We may need to replace the standard gate with a faster one, but after that we could add an extra OpAmp amplifier. Or even feed the gate output back into present opamp by means of an extra relay (so Fremen67 can control it with a spare GPIO, and the amplitude setting works)
Good idea indeed.
We don't have a lot of spare GPIOs, in fact only one from what I recall (PA6) and the wiring could be difficult. But should it happen, we can use the bluepill for extra GPIOs. We just have to leave it connected as it is now and add an extra ribbon between the bluepill and the front panel: either with a serial link or a SPI link. We have the choice.
Should we choose the serial link, than the FP would have a spare SPI port (the bluepill too...) and we could also connect something like this : https://www.aliexpress.com/item/For-Arduino-W5500-Ethernet-Network-Modules-For-Arduino-TCP-IP-51-STM32-SPI-Interface-3-3V/32673979144.html?priceBeautifyAB=0 (https://www.aliexpress.com/item/For-Arduino-W5500-Ethernet-Network-Modules-For-Arduino-TCP-IP-51-STM32-SPI-Interface-3-3V/32673979144.html?priceBeautifyAB=0)
If you see what I mean  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 10, 2018, 04:32:56 pm
Ethernet would be sweet. But I think we should take care not to get too distracted or carried away. Ideally your software should work on FP without any required hardware mods. Even my suggestion was maybe off-track a little.
But I ordered one of those ETH anyway. just in case. 

Programming by STLink seems best to me, as the header for that is already on the board, and with the ST tool, it is very simple, no commands, no linux, no nothing.

Also, sorry, my schedule is very full till middle June. lots of travel, so weekends too. Still wandering this board as a relaxation breather between other stuff, but I am really not going to be good for any proper testing.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on May 10, 2018, 11:49:26 pm
Jeez guys... Leave the Wiz*gizmos for arduino kiddies. If you that much need the ETH and want to spend the extra time and effort, do it properly using a MCU with integrated ETH/MAC. It is not magic to make a custom ETH application, just add the ETH/PHY chip and connect it up. It's not even complicated. There's enough code to get it up and going already written, no need to reinvent a TCP stack.
Leaves you debugging just one faulty firmware: Your's on the MCU, not two (MCU and the wizmo module).
In that case, I'd redesign the front panel PCB to accomodate for all the HW updates of the FP.

STLink is of course the recommended way, using the bootloader is just for the situations where you want to get mad quickly.
You could also use any of the free toolchains for STM32, no need for linux either. AC6 Workbench, Atollic,...  Will get you allso full debug support on the MCU - which I find mandatory when developing such complex applications.

Good night!  ^-^

PS: Yes, I hate those half arsed solutions.  >:D

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on May 10, 2018, 11:59:58 pm
Jeez guys... Leave the Wiz*gizmos for arduino kiddies. If you that much need the ETH and want to spend the extra time and effort, do it properly using a MCU with
Actually the W5500 chips work like a charm if the board layout is good. Messing around with a TCP stack in a microcontroller usually sucks and it won't be able to get rid of all the broadcast traffic you have on a network and you need an extra chip in the form of an ethernet PHY anyway so part wise you don't gain that much.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 11, 2018, 12:31:17 am
Ethernet would be sweet. But I think we should take care not to get too distracted or carried away. Ideally your software should work on FP without any required hardware mods.
Of course. This would be for future extension.

But I ordered one of those ETH anyway. just in case. 
That's wise  ;)

Programming by STLink seems best to me, as the header for that is already on the board, and with the ST tool, it is very simple, no commands, no linux, no nothing.
I would not use Ethernet for programming purposes. Only for remote connection.

Also, sorry, my schedule is very full till middle June. lots of travel, so weekends too. Still wandering this board as a relaxation breather between other stuff, but I am really not going to be good for any proper testing.
Same here.Though I usually not travel during weekends. I still have one kid at home. But I also really need this to change my mind.
But no worries. No customer will ask for penalties regarding production losses  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 11, 2018, 12:54:55 am
Jeez guys... Leave the Wiz*gizmos for arduino kiddies. If you that much need the ETH and want to spend the extra time and effort, do it properly using a MCU with
Actually the W5500 chips work like a charm if the board layout is good. Messing around with a TCP stack in a microcontroller usually sucks and it won't be able to get rid of all the broadcast traffic you have on a network and you need an extra chip in the form of an ethernet PHY anyway so part wise you don't gain that much.
+1
@Yansi
Even changing the FP MCU for one with integrated Ethernet won't do the trick. In sweeping mode the FP MCU is able to send updates every 10µs to the FPGA. If it starts doing other things it won't be able to cope.
With the current Feeltech design, the FP MCU has to refresh the screen plus doing real time stuff... not ideal.
Regarding the current price of the FY6600, re-designing the FP would be overkill.
Adding a second MCU would allow the FP to focus on non time sensitive tasks... and we already have a bluepill in the game.. why not use it?
We already spent 2$ in a Bluepill.. we may also afford to spent 3$ more in a W5500  >:D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Bob Sava on May 11, 2018, 05:57:46 pm
I'm curious, when using Bluepill would it be possible to use i2c programmable any-frequency generator to remove jitter?

https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdf (https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdf)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 11, 2018, 08:50:34 pm
I'm curious, when using Bluepill would it be possible to use i2c programmable any-frequency generator to remove jitter?

https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdf (https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdf)
The idea is interresting. Say we don't want any jitter between a frequency of 50Mhz (5 samples) and a frequency of 62.5 Mhz (4 samples). The idea would be to always have 4 samples in this range. That is to control continuously the sampling rate from 200Msample/s @ 50Mhz to 250Msample/s @ 62.5 Mhz. If the device is able to generate a frequency that would change precisely betwwen 40Mhz and 50Mhz that could work... provided that there is an easy way to find the correct parameters for the device in real time.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on May 11, 2018, 08:59:02 pm
I'm curious, when using Bluepill would it be possible to use i2c programmable any-frequency generator to remove jitter?

https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdf (https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdf)
The idea is interresting. Say we don't want any jitter between a frequency of 50Mhz (5 samples) and a frequency of 62.5 Mhz (4 samples). The idea would be to always have 4 samples in this range. That is to control continuously the sampling rate from 200Msample/s @ 50Mhz to 250Msample/s @ 62.5 Mhz. If the device is able to generate a frequency that would change precisely betwwen 40Mhz and 50Mhz that could work... provided that there is an easy way to find the correct parameters for the device in real time.
You can't switch these frequency generators without a hick-up in between.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 11, 2018, 09:26:30 pm
Would someone please point to *how* the sweep is implemented?  My question is about the algorithm.  My apologies if someone answered and I missed it, but this is a rather busy thread.  Go away for a few days and it's impossible to catch up.

How is the sample clock implemented?  is it done in the FPGA or a separate device?

For the level of work that has been expended, I think we could have an OSHW device of higher quality using a Zynq dev board for not a lot more money than the FY-6600 after the various upgrades and fixes.

I'm still waiting for my CH134A programmers to arrive.  I'm beginning to feel as if I am waiting for  packages from Godot.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 12, 2018, 12:55:45 am
I'm curious, when using Bluepill would it be possible to use i2c programmable any-frequency generator to remove jitter?

https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdf (https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdf)
The idea is interresting. Say we don't want any jitter between a frequency of 50Mhz (5 samples) and a frequency of 62.5 Mhz (4 samples). The idea would be to always have 4 samples in this range. That is to control continuously the sampling rate from 200Msample/s @ 50Mhz to 250Msample/s @ 62.5 Mhz. If the device is able to generate a frequency that would change precisely betwwen 40Mhz and 50Mhz that could work... provided that there is an easy way to find the correct parameters for the device in real time.
You can't switch these frequency generators without a hick-up in between.
Yes, I guess that this won't be a problem when setting manually the frequency... That would be a problem for the sweeping function as it changes fast but in that particular case, I think that jitter is not that important when sweeping. So we can just sweep frequency the normal way.
The Si5351 also can handle several clocks... maybe of some use when switching...

Would someone please point to *how* the sweep is implemented?  My question is about the algorithm.  My apologies if someone answered and I missed it, but this is a rather busy thread.  Go away for a few days and it's impossible to catch up.

How is the sample clock implemented?  is it done in the FPGA or a separate device?
The device can sweep Frequency, Amplitude, Offset or Duty. The sweeping source can be based on time or on external VCO Input (0-5V). This is the FP MCU which sends the values (Frequency, Amp, Offset or Duty) to the FPGA.
In the original FY6600, the values are updated every 900µs when time based.
In the bluepill firmware the values are sent only when they change and the time resolution is 10µs. So when sweeping on a time base, a new value can be sent every 10µs. The time reference is handled in the FP MCU by 2 internal timers that are chained.

For the level of work that has been expended, I think we could have an OSHW device of higher quality using a Zynq dev board for not a lot more money than the FY-6600 after the various upgrades and fixes.
Maybe but the original idea was to be able to replace the original firmware with a better one. As far as I am concerned, redesigning a new FP board is far beyond my goal but when someone wants to go that route, why not!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 12, 2018, 02:34:29 am
[
Would someone please point to *how* the sweep is implemented?  My question is about the algorithm.  My apologies if someone answered and I missed it, but this is a rather busy thread.  Go away for a few days and it's impossible to catch up.

How is the sample clock implemented?  is it done in the FPGA or a separate device?
The device can sweep Frequency, Amplitude, Offset or Duty. The sweeping source can be based on time or on external VCO Input (0-5V). This is the FP MCU which sends the values (Frequency, Amp, Offset or Duty) to the FPGA.
In the original FY6600, the values are updated every 900µs when time based.
In the bluepill firmware the values are sent only when they change and the time resolution is 10µs. So when sweeping on a time base, a new value can be sent every 10µs. The time reference is handled in the FP MCU by 2 internal timers that are chained.

For the level of work that has been expended, I think we could have an OSHW device of higher quality using a Zynq dev board for not a lot more money than the FY-6600 after the various upgrades and fixes.
Maybe but the original idea was to be able to replace the original firmware with a better one. As far as I am concerned, redesigning a new FP board is far beyond my goal but when someone wants to go that route, why not!

Somehow I'm failing to make myself clear. HOW is the sweep implemented?   Is a constant frequency sine wave being run with the clock sped  up each time or is a swept sine wave being stepped?

I was not referring t the FB.  I was referring to the FPGA board.  Except for the details of the FP hardware, you've implemented an alternative  FP from what I've read
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 12, 2018, 04:12:57 am
You can't switch these frequency generators without a hick-up in between.
It does clearly specify a "hitch-less" frequency change. Which would make it useable as clock for the FPGA

I was trying to figure out how precise the frequency can be changed. But the formula's are a bit complex for casual understanding.
Best I can figure its a 'devide by any number up to 512/512'  (which is also something already in the FPGA, but not used to its full potential)

This means we can increase the number of frequencies that are without jitter. But we cannot make jitter-free for all frequencies.
For example, if we have 25MHz jitter free by using a 50/250 clock, we ,may be able to make 24MHz jitter free by using a 48/240 clock. And probably also 24.5. But not 24.65.
I did not want to install the configurator software for that chip. So not completely free, but all 2-digits jitter free would already be very nice.


The idea is good, but I think the Sine-Through-Logic-Gate idea may be easier, and "good enough"

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 13, 2018, 03:52:05 pm
Here is revision 0.7 of the bluepill software with the corresponding modified PC Software.
- The Modulation functions are now working
- The SPI write times are improved (bypassing the STM libraries and new specific 32bit write)
- The FPGA write protocol has been improved (The FPGA protocol allows not to resend the Control Register number when the last used was the same)
- The sweep functions are faster, because of the 2 previous points (now 6µs potential update time instead of 10µs)
- The calibration bug found by DaveR has been fixed

Enjoy and thank you for your feedback!

Edit: Should it be usefull, Modulation functions and Sweep functions can work together ...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 13, 2018, 05:33:20 pm
Hi fremen67,

Great work, thanks! I can't wait to get my FY6600 and bluepill. Can I suggest that you add the connection diagram to every new package so is all in one place?
Thanks again.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on May 14, 2018, 05:40:29 am
Great work again fremen67, too bad I'm studying for my HAM exam this week :) Next week a bit more time for trying out your mega effort for this forum.

Edit: Should it be usefull, Modulation functions and Sweep functions can work together ...

NICE!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 14, 2018, 04:51:15 pm
So I hooked up the St link and processor board .

I did spend sometime messing round with an older version of the St link software but eventually found this ,
https://download.freedownloadmanager.org/Windows-PC/STM32-ST-Link-Utility/FREE-4.2.0.html (https://download.freedownloadmanager.org/Windows-PC/STM32-ST-Link-Utility/FREE-4.2.0.html)
worked first time ,updated the firmware ok ,and uploaded Fremens hex file perfectly .


theres some usefull info and links here ,
http://www.emcu.it/ST-LINKv2/ST-LINKv2.html (http://www.emcu.it/ST-LINKv2/ST-LINKv2.html)

The small board I couldnt get to work , I tried different jumper settings but no luck .
The other board has the 20 pin connector so it was more or less idiot proof .
Im not really sure what Im doing next, connections on the larger board are labeled PA,PB,PC etc followed by a number.Are the pins I need for the FY6600 available from the 20 pin header ? Is the front panel dissconnected  from the main board when the connection from the bluepill is installed or can they both co-exist?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 14, 2018, 07:31:12 pm
 I made another attempt with the smaller board later ,might have been the jumper settings that were messing it up . Seems all working correctly now .Its being recognised by windows after flashing and resetting .

Is there a connection diagram on the github ?

Looks like Pete's got his 6800, heres the article .
https://tech.scargill.net/fy6800-signal-generator/

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 14, 2018, 08:01:22 pm
Did you miss my post here, soundtec?

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1525054/#msg1525054 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1525054/#msg1525054)

You've got some soldering work to do to get the small board working - it should have come with a couple of 10 pin headers, and it should have a couple of jumpers on the pins in the middle of the board.  Wire it up as in mine or fremen's photos, then disconnect the cables from the front panel and connect the free ends to the wiring you've attached to the the blue pill.  As you've already got the big board programmed, follow fremen's wiring photos to work out what goes where, as the pinouts may be different.  If all blue pill boards are the same, it ought to work ok.  If it doesn't, you'll need to get the small board fitted out so that we're all using the same type.

EDIT - I've just compared the pinouts on your small board with one of mine, and they ARE different, so all the photos posted so far will only be a partial guide.  Still, it's not difficult to work out which pin connects to which FP cable socket hole, so you should be there by the end of the night :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 14, 2018, 10:49:45 pm
Is there a connection diagram on the github ?

In a way yes. Just use the normal FP diagram on the github.
both connectors are on the FP diagram with how they are wired to the CPU, and the BluePill is the same CPU and wired the same way as the original FP.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 15, 2018, 01:08:15 am
A simple way to explain the blue pill wiring is this:

Pull the plugs out of the front panel and look at them end on (ie wires running away from you) with the flat side of the plug uppermost.  Starting from the left side, connect each hole of the 8-pin plug to the following pins on the blue pill:  B15, B14, B13, B12, B11, A1, G, A0.  Doing the same for the 4-pin plug:  A3, A2, G, 5v.  The two jumpers on the BP should both be in the 0 position.

This "should" work for any variant of the blue pill board, assuming they are all electrically the same!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on May 15, 2018, 06:07:27 am
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1441974/#msg1441974 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1441974/#msg1441974)

Here is the schematic with yellow highlight how to connect a bluepill. I'll add it to the Git for future reference

https://github.com/DerKammi/FY6600-15-30-50-60M (https://github.com/DerKammi/FY6600-15-30-50-60M) added the different firmware revisions also as reference.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 15, 2018, 07:35:05 pm
Thanks for the help guys.
Had a powercut all day today ,so got everyting connected up with the larger board ,just a few extra pins needed to be soldered for 5 volts and ground . Might be later or tomorrow before I see what happens .

Ive been messing with an ESP8266 (wifi)breakout board ,it seems from what Fremen said that even wired lan connection is to slow to sweep the fy6600 every 10 uS ,could a routine for sweep be programmed and sent to something like an ESP8266's internal memory and then triggered  remotely and used to control the sweep parameters of the Fpga?  The ESP 8266 board I got only has four pins brought out ,but there are others available with more comprehensive i/o. There very cheap ,easy enough to program ,and would mean sweep routines could be uploaded to the device and run locally with no 'comms' delay  ,and no need for any processing on the controling pc . Wifi control of the generator would be an interesting possabillity though, anyway hopefully some ideas there ,thanks for the great work once again Fremen.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 15, 2018, 09:14:11 pm
Thanks for the help guys.
Had a powercut all day today ,so got everyting connected up with the larger board ,just a few extra pins needed to be soldered for 5 volts and ground . Might be later or tomorrow before I see what happens .
The larger board is a "STM32 Smart V2.0". I already used one in a previous project and the main advantage compared to the blue pill is that it has a 20pin JTAG connector. Compared to the basic bluepill, it has a 24c02 eprom onboard (connected to PB6 and PB7, not used by the blue pill firmware) and an extra switch, connected to PA0 which is used for VCO-IN. This should not be a problem at the moment.

Ive been messing with an ESP8266 (wifi)breakout board ,it seems from what Fremen said that even wired lan connection is to slow to sweep the fy6600 every 10 uS ,could a routine for sweep be programmed and sent to something like an ESP8266's internal memory and then triggered  remotely and used to control the sweep parameters of the Fpga?  The ESP 8266 board I got only has four pins brought out ,but there are others available with more comprehensive i/o. There very cheap ,easy enough to program ,and would mean sweep routines could be uploaded to the device and run locally with no 'comms' delay  ,and no need for any processing on the controling pc . Wifi control of the generator would be an interesting possabillity though, anyway hopefully some ideas there ,thanks for the great work once again Fremen.
The sweeping functions are done by the FP MCU. We don't need external connection for that. What I said is that the FP will have trouble handling sweep functions while spending time for other tasks like external communication (serial or ethernet for example if we add such a module) or even refreshing the display.
ESP8266 are interresting modules but then we would have to handle two different architectures with no reusable code.
If we need more CPU power for ethernet connection for example, the idea would be to use something like a bluepill as we could directly re-use existing code.

There would be several possibilities to connect this new board. We could for example just "daisy chain" this board between the existing USB/RS232 converter (4-wires ribbon) and the FP using RS232 link: no modification in the FP would be required. The new board would handle both existing external serial link and the new ethernet module, redirecting requests to a serial port connected to the FP..

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on May 16, 2018, 05:31:01 am
There would be several possibilities to connect this new board. We could for example just "daisy chain" this board between the existing USB/RS232 converter (4-wires ribbon) and the FP using RS232 link: no modification in the FP would be required. The new board would handle both existing external serial link and the new ethernet module, redirecting requests to a serial port connected to the FP..

I like this idea the best as the sweep needs to be perfect and fast in my opinion.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 16, 2018, 09:08:52 pm
Anyone with a V3.2.1 able to dump the flash memory and post it?
Hello everybody,
First, I am a newbie on this forum I used to follow, but up to now I didn't subscribe.
I'd like to say I have been impressed by the quality of the exchanges  and the work been performed herein.
Impressed also by the quality of the contributors, cybermaus, DC1MC, ebel0410, arthurdent, beanflying, soundtech, derkami and of course fremen67, ....and others (sorry for those I forgot)
It made me want to participate to this adventure, as expressed by cybermaus not for it worth but for the plaisure it provides. Thks to all of you.
Attached Flash dump of FY6600-30MHz flash memory.
Dominique
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 16, 2018, 09:53:14 pm
Hi Dom ,welcome ,

On account of the fine weather I put off trying the bluepill board again ,maybe tomorrow .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 16, 2018, 10:04:02 pm
Hi Dom ,welcome ,

On account of the fine weather I put off trying the bluepill board again ,maybe tomorrow .
Thks soundtech,
Just to explain where I am on the project:
I got a FY6600-30 release 3.2.1.
I changed the output amplifier with a pair of THS3091, I replaced SB 16V electrolytic caps with panasonic 25V low ESR ones,
The SMPS is for the moment emulated with a RIGOL lab PSU and the plastic box has been removed so I can perform  thermal measurements either at 12V or at 15V.
I put my footsteps in cybermaus' footprints to dump the flash memory, and in fremen67's ones  to flash a bluepill with his SW (the connections with the SB are in place).
Report in a few day.
Cheers.
Dominique.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 16, 2018, 11:20:01 pm
Hi,
Attached my first thermal measurements on the SB.
> PSU : +/- 12V, CH1=CH2= sine 10KHz, no offset, channels unloaded as there is no heatsink on output amplifier
My goal is to establish a thermal image of the board for further measurements. The measure is quite unprecised on a large chip like the cyclone as the laser spot is not always at the same place.
First impression :
- the 2 output amps have not identical temperatures (? :-//)
- T2 & T5 regulators dissipate quite a bit and could be at risk with a +/-15V PSU (to be tested)
- the cyclone should not request a heatsink
Further measurements to come with a heatsink on the output amplifiers as I will load them and applied square waves with offset
Any suggestion or remark is welcome.
Dominique.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 16, 2018, 11:45:54 pm
I just received mine today and it is ver. 3.3. Beside some cosmetic issues, it seems to be ok.
Sure enough, the output connectors float at around 46VAC, 5V is 5.00..V but both 12V are around 11.4V.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 17, 2018, 12:39:26 am
Well, that's the first 3.3 that we've seen - I wonder what's been tweaked this time?  What's the rev number on the main board (mine was 1.501) - just wondering if any hardware changes have been made as well?  The power supply looks identical to that originally fitted in mine, except that the version number has gone from 1.6 to 1.7 (maybe just a minor component value change).

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 17, 2018, 03:03:16 am
What's the rev number on the main board (mine was 1.501) - just wondering if any hardware changes have been made as well?  The power supply looks identical to that originally fitted in mine, except that the version number has gone from 1.6 to 1.7 (maybe just a minor component value change).

Regards,
Dave

Main board is V1.503. One thing I've noticed on the power supply comparing to other pictures in this thread, the yellow capacitor is gone and they added a fuse.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 17, 2018, 03:36:11 am
Ohh sure there will be some mistakes in the schematic, no doubt :) I'll beep them out and correct the file when I can. The clamp diode sure make sense :)

Hey DerKammi,

I think I just found a mistake in the main board schematic. The AS interface SV1 doesn't look like the one in the picture. I think you swapped some pins there.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 17, 2018, 01:42:59 pm
So the 6800 arrived today .
I just had a preliminary look at it so far ,the switch on the encoder shaft is gone ,replaced by the ok button on the front panel .
Sync options are now accessed via systems menu and VCO has its own dedicated setup page . Only difference I found was in the 6800 you get a realtime display of modulation frequency ,where in the 6600 theres nothing appart from start/stop buttons to tell you your sweep is running .

The rubberised keys are definately an improvement ,much lighter to the touch and doesnt send the machine skidding off the table .On the inside the front panel is new ,the main board is V1.51 and psu is v1.7.
Main board seems tidied up a bit ,from version 1.501,some of the unused stuff is gone and other minor changes in placement in components. One of the ground wires which used to connect psu board to signal board now returns to the mains earth instead ,and the back panel is now plastic . Looks like its the simple dual channel single op amp in place on the outputs ,but the extra pads for the upgrade op amps are still there .No sign of any firmware update button  that was hinted at previously by FT either. So Im wondering what happens if I swap out the front panels between 66 and 68 models ,does my 60 mhz unit then become a 15mhz and the 15mhz work upto 60mhz ?

It comes with a version 1.6 firmware and its the 60mhz model , The new badge on the front panel now reads FeelElec .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 17, 2018, 02:24:50 pm
So the 6800 arrived today .
I just had a preliminary look at it so far ,the switch on the encoder shaft is gone ,replaced by the ok button on the front panel .
Sync options are now accessed via systems menu and VCO has its own dedicated setup page . Only difference I found was in the 6800 you get a realtime display of modulation frequency ,where in the 6600 theres nothing appart from start/stop buttons to tell you your sweep is running .

The rubberised keys are definately an improvement ,much lighter to the touch and doesnt send the machine skidding off the table .On the inside the front panel is new ,the main board is V1.51 and psu is v1.7.
Main board seems tidied up a bit ,from version 1.501,some of the unused stuff is gone and other minor changes in placement in components. One of the ground wires which used to connect psu board to signal board now returns to the mains earth instead ,and the back panel is now plastic . Looks like its the simple dual channel single op amp in place on the outputs ,but the extra pads for the upgrade op amps are still there .No sign of any firmware update button  that was hinted at previously by FT either. So Im wondering what happens if I swap out the front panels between 66 and 68 models ,does my 60 mhz unit then become a 15mhz and the 15mhz work upto 60mhz ?

It comes with a version 1.6 firmware and its the 60mhz model , The new badge on the front panel now reads FeelElec .

The most important part: is the STM on the front panel locked permanently ? Does it come with a new PC software, has this one some update option ?
I'm really curious about the update option, if it's really possible, does these lock bits be disabled from the inside of the running firmware and then re-enabled or there there is actually no option to update the FW.
Questions, questions...  >:D

 Cheers,
 DC1MC

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 17, 2018, 03:54:49 pm
Hi,
Is this of any help ?
attached Sb to Blue pill wiring diagram.
Cheers.
Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 17, 2018, 04:27:47 pm
Hi DCMC ,
Well no sign of anything in the menu's that shows a way to firmware update . Just the box with the accy's was what I recieved ,so I presume software works the same as 6600 .

Thanks Dom, thats a usefull connection diagram for anyone who needs it .

any more questions ,dont hesitate to ask.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 17, 2018, 09:21:18 pm
Just wondering if it might be worthwhile extending this thread to cover the FY6800 too ,seems pointless to set up another topic when everything relevant to 6600 is also relevant to 6800 model.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: andrewjessop on May 17, 2018, 09:26:30 pm
Hi soundtec, I don't suppose you could take some pictures of the 6800 front panel PCB for us?  Would be interesting to see if they've switched some pins around on the STM32 processor.

Cheers,
AJ
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 17, 2018, 09:46:56 pm
Heres a couple of photos Andy,
I'll try and get better shots in daylight tomorrow ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 17, 2018, 09:48:04 pm
And another of the far side of the board ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 17, 2018, 10:19:35 pm
Just wondering if it might be worthwhile extending this thread to cover the FY6800 too ,seems pointless to set up another topic when everything relevant to 6600 is also relevant to 6800 model.

As the 6800 is effectively a 6600 in a different suit, I'd go along with that.

I know you're going to be busy with requests, writing reviews, etc., but does it look like the 3091/3095 mods are still simple drop in replacements for the 3002, or have the other components disappeared from the new board?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: andrewjessop on May 17, 2018, 10:30:05 pm
Thanks soundtec, very helpful! 

It doesn't look like any of the pin functions are changed from my very brief look.  I guess we can confirm with some better quality pictures + getting you to beep out a few pins/vias.

If the Signal Board comms/register protocol hasn't changed then I guess all of Freman67's work will still be of use for the FY6800 model as well.  Even if the protocol has changed it seems to still be using SPI so it would just mean more fun with the logic analyser  :)

AJ
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 17, 2018, 11:34:55 pm
Hi Dave ,
I didnt lift the heatsink on the new unit ,but as far as I can see the pads for the extra op amps are still there, everything runs in parrallel from the 3002 ,power ,inputs and outputs ,so I think that should be fine . Some other differences I noticed were U302 ,which was unpopulated on the 6600 board is now gone . Also the op amp for the input has been moved back from its original position ,I'll get some proper daylit closeups of the boards tomorrow and post them and I can nip around with the bleeper and see if the pin config on the STM tallys with the 6600.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 18, 2018, 12:12:42 am
Cheers, soundtec - you're a hero :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 18, 2018, 11:11:50 am
Heres a couple of shots of the boards ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 18, 2018, 11:12:43 am
And the front panel ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on May 18, 2018, 12:21:33 pm
I made a picture with the two mainboards for comparison. Looks as if the pcb is nearly the same and only little changes.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 18, 2018, 12:31:16 pm
Did you guys use the USB Blaster to read the FPGA flash or you had to remove it and use a programmer?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 18, 2018, 12:32:39 pm
I made a picture with the two mainboards for comparison. Looks as if the pcb is nearly the same and only little changes.

I was just about to make the same observation.  It looks more like a tidying up job than anything else.  As chip 11 has been removed, was it even doing anything in the first place, I wonder?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on May 18, 2018, 12:35:17 pm
It's not removed I think look to the left upper side on the FY6800 board. I cannot read the printings on the chip and did only check on basis of this low res pictures.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 18, 2018, 12:38:32 pm
Did you guys use the USB Blaster to read the FPGA flash or you had to remove it and use a programmer?

Cybermaus did this: https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1352448/#msg1352448 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1352448/#msg1352448)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 18, 2018, 12:41:27 pm
It's not removed I think look to the left upper side on the FY6800 board. I cannot read the printings on the chip and did only check on basis of this low res pictures.

Ah, yes - it looks like it's just been repositioned.  I should have looked harder!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 18, 2018, 02:52:16 pm
Just had a quick look around, and the 6800s are now on sale at Banggood, AliExpress and ebay, priced about the same as the 6600s.  The manual and software are also now on the Feeltech website.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gregg on May 18, 2018, 06:27:10 pm
Just had a quick look around, and the 6800s are now on sale at Banggood, AliExpress and ebay, priced about the same as the 6600s.  The manual and software are also now on the Feeltech website.
I just looked at ebay and Banggood and the front panels of the FY6800 say FeelElec on them.  Do you suppose it already has been cloned, or maybe FeelTech is trying to bury a bad image.  The Banggood one is pre-order; the only one I found on ebay one states it is US stock
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on May 18, 2018, 06:52:12 pm
FeelElec you can see on the original photos on FeelTech website.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 18, 2018, 07:14:05 pm
There is one on EBAY Europe now:

https://www.ebay.de/itm/FY6800-DDS-20-60MHz-2-channel-Generateur-de-signaux-de-Fonction-Signal-Generator/112994684205 (https://www.ebay.de/itm/FY6800-DDS-20-60MHz-2-channel-Generateur-de-signaux-de-Fonction-Signal-Generator/112994684205)

If anybody can confirm that the STM on the front panel is unlocked, I may get myself one and use the other for the experimentation.
If not, they can keep it, from the documents I've seen all the "upgrade" and "update" references have disappeared.

 Cheers and thanks for the pictures,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 18, 2018, 07:47:56 pm
I've looked through the manual, and there's no mention of upgrading that I can see.

There is a new feature statement on page 6, however: "All parameters can be calibrated by internal procedures", which looks interesting - except that there's no further mention of calibration either.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 18, 2018, 11:02:01 pm
Sorry I could have gone a bit higher on the res of those pics,was out all afternoon having a few summer pints of cider .
Its seems like some clarification on the part of Feeltech about firmware updates might be in order , I'll try sending an email asking about it  . Just found the documentation for the 6800 but cant see the software , I'll check for interoperabillity  between the 6600/6800 hardware and software tomorrow ,that should give us a good idea where were going with our own efforts. Fingers crossed it'll work just the same . Only difference I can see between the two machines so far is the VCO getting its own set up page and channel sync settings are now accessed via system menu instead of a dedicated button on the panel .

Its hard to know what the idea behind re-branding the product is , and its comming out at the same price as the 6600 in any case. Is there really any point in Feeltech producing the 6600 anymore ? I'll do a better visual comparison between the two boards tomorrow  ,looks to me the filters at the outputs of the dacs might have been re-jigged ,I certainly noticed differences in the components around that area.

I think Im limited to around 1mb for pic uploads here so maybe someone can suggest another way to host higher resolution images .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 18, 2018, 11:29:15 pm
I can try reading the firmware status on the front panel if you link me back to the methodology you used DC1MC, is there any special interface required or will a simple programmer do the job ? If it needs a proper logic probe to do it I could probably get the use of one if needs be.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 18, 2018, 11:37:17 pm
Talking about jitter, today I checked two generators that we have at work. An Agilent 33220A and a GW Instek SFG-2020. Agilent, no jitter whatsoever at any frequency, any duty cycle. Instek, clean up to 1MHz 50% duty but terrible jitter above 1MHz, or below 1MHz with duty cycle other than 50%.
The output BNC of the Agilent seems to be grounded through 1M.

I've also checked the supply current of the FY6600 with both outputs turned on but unloaded. The results:
5V - less than 360mA.
+/-12V - less than 60mA each.

So I wouldn't go crazy about replacing the power supply. Replacing the input connector with IEC, maybe cleaning it up  a bit but replacing it with a big one or with linear, doesn't really make sense.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 18, 2018, 11:42:16 pm
Just found the documentation for the 6800 but cant see the software , I'll check for interoperabillity  between the 6600/6800 hardware and software tomorrow

The software is in the "User Guide" package on the Feeltech website.  Unfortunately, it's got a Chinese installer, and I didn't bother putting it on my PC in case it created lots of files with Chinese characters in the names, which are a pain to delete.  Looking at the sample screens shown on Banggood and AliExpress, it's pretty much the same as the previous 6600 version, but with more legible fonts (probably copying fremen's efforts), and I'd be surprised if it doesn't work with both boxes.

I think the last of the 6600s will have already left the factory, and it'll be 6800s only from now on.

I think hi-res pics are out on this forum - 1Mb filesize and 2Mb max per post is just too restrictive - but those you posted eariler were fine for a first look inside the box.  I'd love to see what's under that heat sink, though :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 19, 2018, 12:02:58 am
We did find an internal calibration precedure a good while back ,maybe it was before you joined us Dave ,Im not sure .There was a certain hidden key sequence that led to calibration menus I did try it ,but never tweeked anything .Maybe thats whats refered to in the manual .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 19, 2018, 12:21:02 am
I just tried to fire up the Fy6800 software package ,couldnt access the archive or something ,
 After I tried the old V5.5 software and oddly enough there under help in the menu is a pc update option .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 19, 2018, 12:50:12 am
Here's FPGA V3.3 dump using USB Blaster. Device is EPCS16.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 19, 2018, 01:38:07 am
Hi soundtec - the calibration procedure you mention was for output frequency adjustment only.  It works well, but we never did find out if there were any other undocumented adjustments which can be accessed in the 6600.  If they are there in the 6800, they are still undocumented (maybe you can find out from Feeltech, now?).

The PC Update option in the control software appears to be only for an online update of the control software itself, not the 6600 or 6800, but even the software update doesn't work.

Try using 7-Zip to extract all the files from the downloaded file and you'll get the new software installer out ok.  If you get files full of ?.?.?.?.?.? in the names, you'll be needing the 7-Zip file manager to delete them.  I'll try runiing the installer in a VM in the morning to see what it produces, but the fact that the initial installer exe file contains Chinese characters (the ?.?.?.?.?) makes me suspect that Feeltech haven't yet got an English version of the software (or have forgotten to include it in the download package).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on May 19, 2018, 01:41:10 am
I may order one. where's ebay 25% off sale?

The coupon codes I've been seeing lately now have a pre-defined list of sellers. :--
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 19, 2018, 08:49:36 am
I can try reading the firmware status on the front panel if you link me back to the methodology you used DC1MC, is there any special interface required or will a simple programmer do the job ? If it needs a proper logic probe to do it I could probably get the use of one if needs be.
Hi @soundtec, the same programmer for the "blue pill" should be enough to read the status of the lock bits and eventually the firmware.
You just have to wire it carefully and don't "clean" the chip, or else a new development system is born  >:D, I will dig tough the thread to recover the instructions and come back.

In the meanwhile, here is the first seller shipping in EU that I've found on fleabay, the delivery time is not that bad, I'm waiting for the usual suspects to have some stock in DE, but maybe interests somebody:
 
https://www.ebay.de/itm/FY6800-DDS-20-60MHz-2-channel-Generateur-de-signaux-de-Fonction-Signal-Generator/112994684205 (https://www.ebay.de/itm/FY6800-DDS-20-60MHz-2-channel-Generateur-de-signaux-de-Fonction-Signal-Generator/112994684205)

EDIT:
Here's the (rather cumbersome) way to connect your programmer to the STM on the front panel:
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1355639/#msg1355639 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1355639/#msg1355639)

and here the thorough analysis of Cybermaus about being difficult to try the the published paper unlocking method on F0 to the F1:
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1420467/#msg1420467 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1420467/#msg1420467)



 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 19, 2018, 03:34:13 pm
Thanks for fishing out the links for me DC1MC .
Arrgh ,it does look a bit fiddly ,but do-able none the less ,its a magnifiying glass and tweezers job ,so Id have to ask my buddy for the use of his workshop for an hour or so, maybe next week sometime I can do it .

I want to send Feeltech a mail ,but Im unsure which address to send it .

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 19, 2018, 08:00:35 pm
Ild argue against that method.
Just use the STlink method. The header is on the Front Panel already, all you need to do is hook up the 4-pin header and use the STlink utility.

No tweezer soldering, and nice graphic tool, so less chance of mistakes.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 20, 2018, 01:37:17 am
Soundtec - I installed the FY6800 PC Software from the package on the FeelElec / Feeltech website, and the result is as per the screenshot.  It's supposed be v5.8, and the header bar and About box clearly show FY6600, but there is no v5.8 released for the FY6600 as yet, as it's still at v5.5 in the latest package online.  The only major change appears to be the Sweep panel, which has been changed to accommodate the FY6800's FP controls, but the software still works with the FY6600, as I tested it.  They've also tidied up the Help menu option - the Version Information button (as it would be if there were an English version) now brings up the "About" panel instead of the Waveform - Load File window!



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ds on May 20, 2018, 06:48:55 am
There is a hidden menu entry for a Firmware Upgrade in the FY6800 PC Software which should work for the FY6600 too. In fact this hidden command was there for quite a while.

The Firmware Upgrade loads the latest version from the Feeltech website and installs it. The latest version seems to be V 3.4. The firmware file itself seems to be encrypted, at least from a quick look.

If anyone wants to try out the Firmware Upgrade (maybe someone with a broken V3.0 unit) I have attached a patched version of the PC software with the enabled Firmware Upgrade command. The second menu entry in the right most menu is "Firmware Upgrade".

I haven't tried it (no FY6600 yet) so you are on your own and trying it might brake your unit.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 20, 2018, 06:51:21 am
There is a hidden menu entry for a Firmware Upgrade in the FY6800 PC Software which should work for the FY6600 too. In fact this hidden command was there for quite a while.

The Firmware Upgrade loads the latest version from the Feeltech website and installs it. The latest version seems to be V 3.4. The firmware file itself seems to be encrypted, at least from a quick look.

If anyone wants to try out the Firmware Upgrade (maybe someone with a broken V3.0 unit) I have attached a patched version of the PC software with the enabled Firmware Upgrade command. The second menu entry in the right most menu is "Firmware Upgrade".

I haven't tried it (no FY6600 yet) so you are on your own and trying it might brake you unit.

If this is true, than is the news of the year !!!

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 20, 2018, 07:06:13 am
Thats funny Dave ,I tried several methods of un-wrapping the installer and still no go for me . 6800 did work ok with 6600 software via regular usb host connection ,and Fremens 0.7 software did seem to default gracefully enough  to 'standard' usb comms mode without the bluepill unit installed.

Seeing as I have the Stm32 V2link  board ,I'll opt for the less invasive method of extraction of firmware update status bit , cheers Cyber ;)
So is it the four pin header on the front panel board I need to hook up to?

I think a straight swap between  the front panels of 66 and 68 series might be fun to try ,same time I dont want to be going back to Mr Feeltech with egg on my face and a couple of scrambled units ,so if anyone thinks this might be a bad idea speak forth now.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 20, 2018, 07:30:20 am

If this is true, than is the news of the year !!!

 Cheers,
 DC1MC

There is always hope, and yes, anyone with a broken V3.0 has little to loose.

But since this would have solved a big image problem for Feeltech, they would have mentioned this already.
My guess is it a remand of a feature they started work on, but never completed.
Biggest chance is it will simply not work, but there is a small change it may even break a device, so indeed, be careful to try it.

Anyone has a opp to post the link, or grab the supposed encrypted firmware file, before they remove it after reading this thread?
But do not simply post it as "firmware V3.4" please, to avoid people trying it without understanding the risk.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 20, 2018, 07:57:25 am
I have put my FY6600 V 3.1 device on-line, the update menu recognizes the firmware version 3.1 and shows the version 3.4, starts to load something and then comes to a halt with some message about "???? USB ???" and stop.

I'll try to see where this program is going by finding a windozian firewall program that shows what connections are open. if someone has better "hacking" skillz, I  have a win 7 laptop with the cadaver connected, that I can make accessible by remote, PM if you want access.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ds on May 20, 2018, 08:05:33 am

Anyone has a opp to post the link, or grab the supposed encrypted firmware file, before they remove it after reading this thread?
But do not simply post it as "firmware V3.4" please, to avoid people trying it without understanding the risk.

The parts to create the link are in the PC software, they look very similar to the way the
PC software update works. For the firmware file it is the following:

http://www.feeltech.net/software/updata/FY6600/download.php?vison=DDS&name=FY6600-DDS.FYbi (http://www.feeltech.net/software/updata/FY6600/download.php?vison=DDS&name=FY6600-DDS.FYbi)

The V3.4 Firmware file is attached, but as I already wrote, there is not much to see as it is most certainly encrypted.

I think that you can use the "Command 3" button of the Firmware Upgrade command to load it directly.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 20, 2018, 08:13:48 am
Downloaded it, tried it, same issue, it exits with some intraductible message about USB.
At least there seem to not be any damage to the device.
Now is about to time to look over the serial port traffic  >:D


Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 20, 2018, 08:29:55 am
Some little analysis with binwalk:

binwalk -E ./FY6600-DDS.FYbi  produces a very flat histogram, that is hinting strongly at some compression being used.

binwalk -X ./FY6600-DDS.FYbi detects a lot "Raw deflate compression stream"

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
187           0xBB            Raw deflate compression stream
432           0x1B0           Raw deflate compression stream
466           0x1D2           Raw deflate compression stream
762           0x2FA           Raw deflate compression stream
1180          0x49C           Raw deflate compression stream
1217          0x4C1           Raw deflate compression stream
... and so on ...



Let's see what is in this raw deflated things  >:D.

 Cheers,
 DC1MC


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 20, 2018, 09:09:47 am
The serial sniffer says:

<PrSTM32_START\r

after which the firmware doesn't reply at all :(, it seem the the fw blob has to be decoded, on v3.1 the update procedure seem to not be enabled.

 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 20, 2018, 09:22:10 am
There is a hidden menu entry for a Firmware Upgrade in the FY6800 PC Software which should work for the FY6600 too. In fact this hidden command was there for quite a while.

The Firmware Upgrade loads the latest version from the Feeltech website and installs it. The latest version seems to be V 3.4. The firmware file itself seems to be encrypted, at least from a quick look.

If anyone wants to try out the Firmware Upgrade (maybe someone with a broken V3.0 unit) I have attached a patched version of the PC software with the enabled Firmware Upgrade command. The second menu entry in the right most menu is "Firmware Upgrade".

I haven't tried it (no FY6600 yet) so you are on your own and trying it might brake your unit.

The serial sniffer says:

<PrSTM32_START\r

after which the firmware doesn't reply at all :(, it seem the the fw blob has to be decoded, on v3.1 the update procedure seem to not be enabled.

 DC1MC
A lot of interesting things these last days ;-)
I will try to find something too… I am on it
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 20, 2018, 10:32:16 am
The firmware update protocol is not working with v3.2 but using the bluepill I can try to make the PC Software send the firmware to me ;-)

The protocol starts as follows:

PC: <PrSTM32_START 0x0A
BP: START 0x0A
PC: IAPSTM32_2048_0_62596 0x0A
BP: 0x0A
PC: 2048 binary packet

At the end there should be something like:
PC: <PrSTM32_RST 0x0A
BP: BOOT 0x0A

There is also a command that the PC can send which is <PrSTM32_DO 0x0A. I will see later on.

At the moment I only have the first 2048 bytes but when I find the correct answer, I should receive the remining blocks.
I suppose that we may miss the 4096 remaining bytes of the bootloader at the end so this won't be usable like this. But one step at a time...
More after lunch ;-)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DerKammi on May 20, 2018, 10:48:29 am
How nice would that be, I see a hex file posted on the forums in short time :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ds on May 20, 2018, 12:24:54 pm
At the moment I only have the first 2048 bytes but when I find the correct answer, I should receive the remining blocks.
I suppose that we may miss the 4096 remaining bytes of the bootloader at the end so this won't be usable like this. But one step at a time...
More after lunch ;-)

You noticed that the data are just the bytes from the firmware binary file?

The decryption (if my assumption of encrytped data is correct) most certainy takes place inside the STM32 and not in the PC executable.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 20, 2018, 01:03:15 pm
I hope we can at least get the offsets and sizes of the encrypted/compressed packages. It will help with the decryption/decompression.

 Best of luck and if you need an extra pair of eyes/hands and a sacrificial device, I'm around  :box:.

I'm wondering if the update command doesn't activate when some certain key sequence are pressed on the front panel.

  Good luck,
  DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 20, 2018, 02:09:34 pm
I now got 49 packets: 48 packets of 2048 bytes and one of 1727, that is 100031 bytes

More details on the protocol:

PC: <PrSTM32_START 0x0A
BP: START 0x0A
PC: <IAPSTM32_PacketLength_PacketNumber_16bitChecksum0x0A
BP: 0x0A
PC: 2048 binary packet
BP: "WrEND" when write OK or "error"
PC: <IAPSTM32_PacketLength_Packet+1_16bitsChecksum 0x0A
…..
On "error" reply to a packet, PC Software retries 4 times then stops

After the last packet:
PC:<PrSTM32_DO 0x0A
… and I don't know yet what to reply ...

First packet is 0.

I suppose there is some kind of CRC Checksum so that the FP MCU can check the packet before writing it.

At the moment I only have the first 2048 bytes but when I find the correct answer, I should receive the remining blocks.
I suppose that we may miss the 4096 remaining bytes of the bootloader at the end so this won't be usable like this. But one step at a time...
More after lunch ;-)

You noticed that the data are just the bytes from the firmware binary file?

The decryption (if my assumption of encrytped data is correct) most certainy takes place inside the STM32 and not in the PC executable.

Yes the decoding seems to be made in the FP MCU.
When you remove a 13 bytes header in the firmware file, you get the same values as in packet 0.

I attached the first packet plus the capture of the whole tranfer made with my DSLogic analyser.

Edit: CRC replaced with Checksum
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 20, 2018, 02:26:54 pm
I hope we can at least get the offsets and sizes of the encrypted/compressed packages. It will help with the decryption/decompression.
Almost all the packet having the same size, and the decoding being done by the FP MCU, I would suppose there is no compression but rather some sort of XOR treatment with a constant key. The MCU has not a lot of power and it has to go fast.
If I am right and if the last parameter is a sort of 16bits CRC, than it would make sens to check the CRC and decode at the same time. Which would lead to a 16 bits key...

Best of luck and if you need an extra pair of eyes/hands and a sacrificial device, I'm around  :box:.
You are more than welcome! Not sure we need a sacrificial device for decoding. We have to think of some code or constants that might be in the update and that could lead to the key.
Constants like "FY6600_60M" may be in the bootloader but strings like "V3.4" could be in it… or many other  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tsman on May 20, 2018, 02:54:58 pm
Almost all the packet having the same size, and the decoding being done by the FP MCU, I would suppose there is no compression but rather some sort of XOR treatment with a constant key.
I'd expect there to be lots of repeated sequences if it was a simple constant key XORed with the data but there aren't any. A block cipher like AES is easily implemented in a STM32 so my guess is that it is encrypted but with something stronger that constant key XOR. ST uses the same STM32F103 in their ST-Link dongles and they use AES to encrypt the firmware as well. They've implemented it in a really bizarre way however and decrypt the binaries in the update tool then reencrypt it with a random key supplied by the ST-Link bootloader.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 20, 2018, 02:55:17 pm
Did a simple XORSearch  (https://blog.didierstevens.com/programs/xorsearch/)for strings that must be in there, to find it with common simple obfuscations like XOR, ROL, ROT, SHIFT, ADD. No luck
(tried case insensitive FeelTech, Wave, Sine, Freq as strings). No luck. So its a little more then so simple 1 byte obfuscation. Maybe a better 32 bit hash or so. Or they stacked 2 obfuscations.


Also I'd like to point out the file is 100048 bytes. Too much for a CPU update, too little for a CPU+FPGA update.
And of course, any proper update should be MCU+ FPGA (64K + 384K)

So if a 64KB firmware, then there is 32K+1744B too much.
Either they are using the "undocumented" 128KB of the MCU, or there is a lot of extra code for obfuscation.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tsman on May 20, 2018, 03:12:16 pm
Either they are using the "undocumented" 128KB of the MCU, or there is a lot of extra code for obfuscation.
I'd say this was nearly certain. There are enough manufacturers out there that don't care about the official specs by doing things like using a STM32F101 for USB even though that part doesn't officially support it. Exploiting the extra unofficial flash in a "64KB" STM32F103 is fairly common now. Supposedly there have been some STM32F103C8s found that do only have 64KB flash though. The GD32 clones don't but they're completely different inside.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ds on May 20, 2018, 03:48:43 pm
If I am right and if the last parameter is a sort of 16bits CRC, than it would make sens to check the CRC and decode at the same time. Which would lead to a 16 bits key...

The last parameter is just the 16-Bit sum of all the bytes in a block, so no real CRC.

I noticed that the last four bytes of the firmware image are so far not used, not sure if they have a meaning.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on May 20, 2018, 03:49:54 pm
I remembered there was this 256 byte count up from 01~FF in the WinBond firmware (position 0x0f0000) (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1353950/#msg1353950) and I found this common "rolling XOR" technique and decoder NoMoreXOR (https://github.com/hiddenillusion/NoMoreXOR) (more explanation here (https://digital-forensics.sans.org/blog/2013/05/14/tools-for-examining-xor-obfuscation-for-malware-analysis)), that typically uses these sort of 256 byte strings to decode.

But its a python script and python-yara does not want to install.
And I need to stop this, and start packing for my work trip.

So if anyone else want to explore this...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 20, 2018, 03:58:53 pm
If I am right and if the last parameter is a sort of 16bits CRC, than it would make sens to check the CRC and decode at the same time. Which would lead to a 16 bits key...

The last parameter is just the 16-Bit sum of all the bytes in a block, so no real CRC.
Well... basically that is already a CRC, even if you don't take the 2-complement. And there are a lot of different CRCs ...  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 20, 2018, 04:00:20 pm
Did a simple XORSearch  (https://blog.didierstevens.com/programs/xorsearch/)for strings that must be in there, to find it with common simple obfuscations like XOR, ROL, ROT, SHIFT, ADD. No luck
(tried case insensitive FeelTech, Wave, Sine, Freq as strings). No luck. So its a little more then so simple 1 byte obfuscation. Maybe a better 32 bit hash or so. Or they stacked 2 obfuscations.


Also I'd like to point out the file is 100048 bytes. Too much for a CPU update, too little for a CPU+FPGA update.
And of course, any proper update should be MCU+ FPGA (64K + 384K)

So if a 64KB firmware, then there is 32K+1744B too much.
Either they are using the "undocumented" 128KB of the MCU, or there is a lot of extra code for obfuscation.

FPGA update could come later on but for the moment I would go for CPU only: 100KB + Bootloader could also make 128KB …
I can't see how easily erasing and programming the whole CPU from the inside...

When analyzing the upgrade protocol, a flash write seems to occur every 2048 bytes block. As a page flash size is 1024 byte on the MCU, there are 2 possibilities: either it decodes 2048 into 2048 bytes and writes 2 pages, either it decodes 2048 bytes into 1024 and write only one page.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ds on May 20, 2018, 04:17:14 pm
Well... basically that is already a CRC, even if you don't take the 2-complement. And there are a lot of different CRCs ...  ;)

I don't think so. A CRC is based on polynomial division and not on an arithmetic sum, see https://en.wikipedia.org/wiki/Cyclic_redundancy_check

I am not sure if there is a polynom which would give the same result as the arithmetic sum, so maybe it is a special case.

Anyway, the difference is not really important here. Regarding encryption: AES would be easy to implement and is fast and small enough. And then of course there are many different other encryption algorithms which are more than good enough for this kind of application and which require less space than AES.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 20, 2018, 04:49:58 pm
Well... basically that is already a CRC, even if you don't take the 2-complement. And there are a lot of different CRCs ...  ;)

I don't think so. A CRC is based on polynomial division and not on an arithmetic sum, see https://en.wikipedia.org/wiki/Cyclic_redundancy_check

I am not sure if there is a polynom which would give the same result as the arithmetic sum, so maybe it is a special case.

Anyway, the difference is not really important here. Regarding encryption: AES would be easy to implement and is fast and small enough. And then of course there are many different other encryption algorithms which are more than good enough for this kind of application and which require less space than AES.
You are right, I should have said checksum. I will correct the protocol description post.

The problem I see now is that even if we are able to decode the firmware updates, there are chances that we won't be able to use them easily without the bootloader. That would require efforts that could be useless at the end.
As far as I am concerned, I will switch back to the bluepill firmware. We are almost at the GUI stage and that will be more rewarding I guess  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 20, 2018, 06:37:26 pm
Wow some interesting developments overnight .
I have to admit I'm way out of my depth with regards to encryption etc ,but you guys seem in your element trying to get this jack out of the box .

Does the appearance of this firmware file show that a way to upgrade the machine does exist already ?
I must re- read the last few pages again for it to sink in .

I'll send an email to Feeltech asking about any plans for firmware updates etc .
If theres any specific questions or points that you guys would like me to mention in the email just say and I can add them ,but hopefully Ive captured the general feeling in a few paragraphs for them at any rate .

Just reading back your latest post Fremen, do you think theres a hidden function accessed by front panel buttons that drops the unit into update mode?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on May 20, 2018, 06:50:24 pm
@fremen67 - the main purpose of this exercise is not to get hold of feeltech buggy crap, but to be able to offer a comfortable way to the people to upgrade the device without having to resort to extra programmers and even opening the device. And also offering a way back to the original firmware if needed (i.e. for warranty purposes).
This is why it's still interesting to try to get a hold of the firmware update process, load a custom fw to read and send back the bootloader, to see which key combination activates the update process and then managing the firmware updates will be much easier.

 Cheers,
 DC1MC

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 21, 2018, 12:23:01 am
Just reading back your latest post Fremen, do you think theres a hidden function accessed by front panel buttons that drops the unit into update mode?
I have no way to be sure but the v5.8 PC software did not required to do something special, appart maybe not to remove the USB cable during update. It just seems to be serial commands like other commands it uses (wave download for example). My V3.2 firmware did not respond to the update requests so I would guess that this function is at least not supported by device with firmware <= v3.2.
Wheter there is a special key combination to do before or not, I don't know...
@fremen67 - the main purpose of this exercise is not to get hold of feeltech buggy crap, but to be able to offer a comfortable way to the people to upgrade the device without having to resort to extra programmers and even opening the device. And also offering a way back to the original firmware if needed (i.e. for warranty purposes).
This is why it's still interesting to try to get a hold of the firmware update process, load a custom fw to read and send back the bootloader, to see which key combination activates the update process and then managing the firmware updates will be much easier.

 Cheers,
 DC1MC
I understand clearly the benefit of upgrading firmware for every one but as already said, even with a decoded upgrade firmware, we will still miss the boatloader to make the whole think work: the code which does the upgrade can't erase itself... and if the upgrade functionnality is not available with firmware < v3.2 at least, then none of use would have access to this bootloader. It would be easier to wait for someone to receive a v3.4 device and see if that function is available.
Once again, I don't say it is useless to try. I just say that as far as I am concerned, I have to focus on the bluepill/replacement firmware at the moment.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 21, 2018, 01:57:42 am
Can someone post the error message that you get when you try to upgrade? I have enough Chinese colleagues that can translate for me.
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Candid on May 21, 2018, 08:19:19 am
For me it was only several '?' and somewhere in between these the text 'USB' in a dialog (an ok/cancle dialog I think) directly after you hit the start button. There you hit the left button and then it runs for some seconds and you get a new error dialog with some '?' the text 'USB' and a '!'.

Looks like the software asks the unit to to do the update but the unit does not respond like expected concerning what we already know about the process of what you can read here.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 21, 2018, 09:49:55 am
For me it was only several '?' and somewhere in between these the text 'USB' in a dialog (an ok/cancle dialog I think) directly after you hit the start button. There you hit the left button and then it runs for some seconds and you get a new error dialog with some '?' the text 'USB' and a '!'.

Looks like the software asks the unit to to do the update but the unit does not respond like expected concerning what we already know about the process of what you can read here.

I think you need to install traditional Chinese characters to see anything meaningful... to a Chinese.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 21, 2018, 12:15:15 pm
On both my computers I had an issue running the new english fy6800 software installer , on the win 10 pc ,windows defender reports the installer contains a virus or pup ,and a minute later the unpacked installer is deleted by windows ,on an older os the archive cant be opened . I had to resolve a couple of dependencies ,two .ocx files needed to be added to windows before the chineese version update would run ,I tried the firmware update option and it seemed to be working first time around ,until the usb error message popped up . The version information panel now reports that I have my fy6600 15mhz connected, confirms that software update 5.8  is installed and that the firmware revision of the machine is at 3.2 . This panel never worked properly in any version of the software for me up until now,it just caused the waveform view window to pop up .

Could it be that in order for the fy6600 to receive the chinese firmware update it needs to be run in chinese language mode instead of english by front panel selection ? I dont know if it will make any difference ,but I might give it a try this afternoon for giggles and sh!ts
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 21, 2018, 01:37:44 pm
Did anything change on the display when you started the update?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 21, 2018, 02:02:52 pm
No change on the display of the unit ,I already tried swapping out ch340 drivers extracting feeltechs original infs ,but that was just the same , incidently running the machine in chinese language made no difference either  :-DD

I tried changing the baud rate of the com port ,no difference , I think there has to be a routine to drop the unit into boot mode that were missing out ,thats why they cant com , I wonder would translating the latest chinese released documents the give us any clues ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Jon.C on May 21, 2018, 02:16:42 pm
new version in pre-order     :o

https://www.banggood.com/FY6800-2-Channel-DDS-Arbitrary-Waveform-Signal-Generator-14bits-250MSas-Sine-Square-Pulse-VCO-Meter-p-1293929.html?rmmds=search&cur_warehouse=CN (https://www.banggood.com/FY6800-2-Channel-DDS-Arbitrary-Waveform-Signal-Generator-14bits-250MSas-Sine-Square-Pulse-VCO-Meter-p-1293929.html?rmmds=search&cur_warehouse=CN)


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 21, 2018, 02:31:34 pm
No change on the display of the unit ,I already tried swapping out ch340 drivers extracting feeltechs original infs ,but that was just the same , incidently running the machine in chinese language made no difference either  :-DD

I tried changing the baud rate of the com port ,no difference , I think there has to be a routine to drop the unit into boot mode that were missing out ,thats why they cant com , I wonder would translating the latest chinese released documents the give us any clues ?

That may be an indication that the device is not in upgrade mode. Try to power it up while pressing 1, 2 or more random buttons. You may find something.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 21, 2018, 04:01:34 pm
Try to power it up while pressing 1, 2 or more random buttons. You may find something.

The engineering mode for frquency calibration is entered by pressing and holding the front panel power and Ch1 buttons whilst turning on the main power switch at the back.  It's probably the same, or something very similar (Power + ?), to go into update mode (assuming v3.2 has one).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tsman on May 21, 2018, 05:52:34 pm
If there was a bootloader update mode in an old FY6600 then wouldn't FeelTech have already mentioned it by now? It would have fixed the various corrupted units and saved them a lot of bad PR. They posted here about how their next unit would have the firmware update ability.

It is possible that an update mode does exist but the old FY6600 bootloaders don't support encrypted firmware updates. Doesn't really help us now though because the FYbi file is decrypted inside the device so wouldn't be compatible.

*shrug*
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 21, 2018, 07:28:58 pm
Ive tried many different combinations of buttons with the on off switch ,I can of course get the frequency cal mode up by pressing standby and channel 1 button while hitting the power switch ,there only a certain number of combinations of two or three buttons otherwise it would require more than one person to do it , the only thing I can find is holding the power button on the front panel down prevents  the unit starting  up from memory .

The 6800 hooked up ok to the software ,it wanted to update to 3.6 also ,but it didnt work in the end either .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 21, 2018, 07:51:27 pm
Well, being generous to Feeltech, we could assume that the online update feature is stil a "work in progress" :).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 21, 2018, 09:01:58 pm
I cant get software 5.8 to work ,apart from the standalone version that comes with the firmware update.
its only in the latest version you get the command 3 button on and the software has no problem picking up either 6600 v 3.2 or 6800 v1.6 and it says which mhz the model you have is also. When I try to update v5.5 of the pc software it wants to go to v5.6 and tries to download something but it fails without executing the upgrade .It also appears to want to bring the firmware of the 6800 from 1.6 to  3.4 ,again it fails to update 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 21, 2018, 10:53:16 pm
I noticed some other quirks with the software, soundtec.  When I used the update software function on either 5.8 version, it said it was going to download v5.6, but when the new file was installed it was only v5.5.  This Chinese language version, however, had the firmware update option without the Command3 button, and downloaded the 3.4 firmware file but wouldn't install it (it just gave the USB errors previously reported).

Evidently, then, only the Chinese versions have the firmware update options, and only the Chinese versions will actually do a software upgrade (even though it's often a version downgrade).  But there are also two Chinese 5.8 versions - one with the firmware update option (which may be an internal engineering version) and one without, which is on the Feeltech website for public consumption.  The Command3 button in the former is simply to give the option of upgrading via a local file rather than via the internet.

I'm confident that Feeltech will have it all working smoothly by the time the FY7400 series is released, along with software version 9.6.

EDIT: added the v5.8 from the website (without firmware update option)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 22, 2018, 06:44:05 am
Just wondering did anyone have the same issue I had with the 5.8 installer from feeltech ,where its either  flagged as a trojan or the archive isnt able to open ?

later I found that by stopping advanced language services the 5.8 exe would run on xp  ,but in any case it had a garbled charachter set .
So there is no english language version of the new software yet as far as I can see .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 22, 2018, 12:59:16 pm
There's nothing fundamentally wrong with the archives, soundtec, nor with the CDs that some people said couldn't be read, it's just that "tight" OSs and aggressive anti-malware programs interpret them wrongly because they can't understand the Chinese characters inside them.  The trick with nested archives, where you have rar files within rar files, is to burrow inside them layer by layer amd simply remove any non-Roman characters from the filenames before you try to extract the contents of each layer.  This stops the Chinese characters from being replaced by strings of "?" and keeps the filenames "Windows legal", thereby avoiding all the error messages.

I suppose installing the Chinese language files using Windows Update would stop the problem as well (after all, the Chinese themselves obviously don't have the same trouble opening their own archives), but I've tried a couple of times to do that and Good Ol' Windoze has had other ideas about it!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 22, 2018, 01:50:28 pm
Yeah I had tried a few things to change the filenames ,but again didnt work as expected . I think theres a problem with the file feeltech put up in the english section  .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 22, 2018, 04:52:21 pm
No, there's nothing wrong with the file - I've downloaded it and extracted everything again to test it.  Use WinRar 5.30 or later, or 7-Zip 9.0 or later to rename and extract the files, but don't let the extractor create any folder names with non-English characters either.  Try disabling Windows Defender as well (in Windows10).   I've just done the whole thing on another PC and the downloaded v5.8 (without FW update option) "updates" the software to v5.5 (with FW update option).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 23, 2018, 03:07:54 am
 Yeah tried modern versions of rar and zip ,win 10 wont look at the file sideways ,I did eventually get XP to run the exe .
None of the previous .exe 's from Feeltech had any chinese charachters in the name and decompressed/ran fine .I eventually disabled the advanced language support tab in properties and bang the exe loaded up on xp ,but with a garbled charachter set . I can get v5.5 to run in English ok ,but v5.8 no.

Has anybody managed to run v5.8 in English so far ?
My view anyway is there's a few issues with English V5.8 that Feeltech need to fix ,every other software of theres ive used just seemed to work 

Overall things are going in a good direction ,it seems like online firmware updates are certainly on the way, I did send an email to Feeltech the other day with some generalised questions relating whats going on ,but no reply at all .








                                                                                                                                               
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 23, 2018, 04:13:03 pm
Fremen67, I tested  SW release 0.7 and I didn't find anything : it works fine. I still have to test SWEEP with VCO input.
I noticed 2 things:
1) when AM modulation is activated on Sine wave, CH1 amplitude decrease and the signal is not modulated. Then it works fine with CH2 activated.
see pic1-3 , carrier CH1 100KHz sine 2V ppk on 50 ohms, mod CH2 sine 1KHz on 50 ohms, both no offset
2) with FSK, ASK, PSK modulations, CH2 dutycycle is not taken into account
see pic4, CH1 = 100KHz 2V ppk on 50 ohms, HOP freq = 20KHz, CH2=1Hz 1.5 V ppk on 50 ohms

and a question : calibration must me performed in Hi-Z ?

Cheers
Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 23, 2018, 07:37:49 pm
Fremen67, I tested  SW release 0.7 and I didn't find anything : it works fine. I still have to test SWEEP with VCO input.
I noticed 2 things:
1) when AM modulation is activated on Sine wave, CH1 amplitude decrease and the signal is not modulated. Then it works fine with CH2 activated.
see pic1-3 , carrier CH1 100KHz sine 2V ppk on 50 ohms, mod CH2 sine 1KHz on 50 ohms, both no offset
2) with FSK, ASK, PSK modulations, CH2 dutycycle is not taken into account
see pic4, CH1 = 100KHz 2V ppk on 50 ohms, HOP freq = 20KHz, CH2=1Hz 1.5 V ppk on 50 ohms

and a question : calibration must me performed in Hi-Z ?

Cheers
Dom.
Hi Dom,
Welcome onboard and thank you for the feedback! I know that that kind of tests is really time consuming :-+
Regarding Modulation mode, except when VCO-IN is selected as source, the  blue pill only send configurations parameters to the FPGA and inits/starts/stops the process.
When VCO-IN is selected as input, blue pill also have to feed the FPGA with VCO-IN value as fast as possible.
That would be interresting when you could run the same tests directly on the FY6600 with the original firmware. That would allow to see where the problems comes from.
For Sweeping functions, most of the work is done by the FP MCU, that is by the bluepill with our firmware. Here also that would be interresting to compare with the original firmware.

Regarding calibration, the status of the fy6600 (wave, frequency, amplitude, offset, range,Hi-Z mode) has no importance as the bluepill willl select the correct configuration during the calibration process and restore the initial state afterward. The only important thing is not to have any real load on the output during calibration.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 23, 2018, 07:38:46 pm
Hi,

I completed my tests on BluePill & PC SW release  0.7 with VCO IN. I diddn't find any problem, works well.
Attached a picture of the combination of frequency sweep and amplitude modulation by a ramp on CH2.
Many Thks fremen67.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 23, 2018, 07:45:11 pm



[/quote]

That would be interresting when you could run the same tests directly on the FY6600 with the original firmware. That would allow to see where the problems comes from.
For Sweeping functions, most of the work is done by the FP MCU, that is by the bluepill with our firmware. Here also that would be interresting to compare with the original firmware.

[/quote]
Hi fremen67, I will do.
Cheers
Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 23, 2018, 08:06:22 pm
Hi,

I completed my tests on BluePill & PC SW release  0.7 with VCO IN. I diddn't find any problem, works well.
Attached a picture of the combination of frequency sweep and amplitude modulation by a ramp on CH2.
Many Thks fremen67.
You are welcome! :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 23, 2018, 09:18:32 pm
Here are complementary tests around the AM modulation with my 3.2.1 AWG version.
1) I went back to the original HW & SW : FP + Feeltech PC SW
CH1 = Sine 100 KHz 2Vpp on 50 ohms, no offset and CH2 = Sine 1000Hz 1.5Vpp Hi-Z, no offset
Vpp measured : 1.03V (normal) constant amplitude
click on AM button : nothing(100KHz carrier constant 1.03V amplitude)=> click on FM : nothing => click on FSK or PSK : ok  => click on FM : nothing => click on AM : nothing
same behavior with CH2 ON
Note: when I modify freq or amplitude parameter on the FP, nothing is reported to the PC screen, old freq or amplitude displayed
2) I use fremen67 PC SW anf FP - same channels configuration
CH1 unmodulated : 1.03V constant amplitude
click on AM button (green) 776mV constant amplitude
CH2 on : 1.03V constant amplitude on CH1
AM button : inactive
click on FM button : ok FM modulation on scope
I restart both AWG and fremen67 PC SW
same behavior but I click on AM button after FM and AM mod works !
during all the test, FSK or PSK works.
Not easy to find out one's way in this. :-/O
Did anyone report same problem with the original SW ? if not with what Feeltech version ? I use V5.5
Cheers.
Dom
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 23, 2018, 09:53:40 pm
OK, I recover on my mistake with the original Feeltech PC SW : I used to work with fremen67's one and I forgot the behavior and use of Feeltech's:

During my test, I ignored the "parameter" cell  so as I didn't define the AM modulation factor and so no way to get an AM modulation.

So now fremen67, I can say that I got the save behavior with Feeltech PC SW on AM modulation : as you guessed, it is not in the bluePill firmware :
CH1 = sine 100KHz 2Vpp on 50 ohms, no offset and CH2 = sine 1000Hz 1.5Vpp no offset
I set 50% as parameter.
I put CH1 ON and I get a 1.03V constant amplitude 100KHz sine wave on the scope.
I click on AM Mod : the amplitude decrease to a constant 528 mV pp amplitude
I put CH2 ON and the amplitude come back to a constant 1.03V pp amplitude
I click again on AM Mod button to get a 100 Khz modulated signal.

Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on May 23, 2018, 10:38:19 pm
OK, I recover on my mistake with the original Feeltech PC SW : I used to work with fremen67's one and I forgot the behavior and use of Feeltech's:

During my test, I ignored the "parameter" cell  so as I didn't define the AM modulation factor and so no way to get an AM modulation.

So now fremen67, I can say that I got the save behavior with Feeltech PC SW on AM modulation : as you guessed, it is not in the bluePill firmware :
CH1 = sine 100KHz 2Vpp on 50 ohms, no offset and CH2 = sine 1000Hz 1.5Vpp no offset
I set 50% as parameter.
I put CH1 ON and I get a 1.03V constant amplitude 100KHz sine wave on the scope.
I click on AM Mod : the amplitude decrease to a constant 528 mV pp amplitude
I put CH2 ON and the amplitude come back to a constant 1.03V pp amplitude
I click again on AM Mod button to get a 100 Khz modulated signal.

Dom.
Does it work correctly when using directly the FP,  without PC Software?
I had to add an ON/OFF button for each function on the PC Software because otherwise it was impossible to handle correctly the start and stop of these functions.
I just made a test on modulation function with PC Software v0.7 and the modulations seems to start each time I push the modulation ON/OFF button...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 24, 2018, 11:50:35 am
I got a reply from Eren at Feeltech ,

heres what he said ,

'Not all FY6600 support online updates, but FY6800 will fully support online updates. We do not recommend that users frequently update the firmware. If they are not handled properly, it is very likely that the signal generator will be damaged and cannot be used normally.'

He also sent me a corrected English version of the V5.8 installer , I suspect it will be posted on the site soon ,I'll find a way to post it here too but its over the maximum allowance for upload on EEV.

http://www.filedropper.com/fy6600pcsoftwarev58 (http://www.filedropper.com/fy6600pcsoftwarev58)




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 24, 2018, 08:53:55 pm
Hmm, so not all, but presumably some FY6600s, will support firmware updates - v3.4 then?  But don't update the firmware anyway, because you might brick the box!

No sign of firmware updates in the English v5.8 of the PC software, and the software online update feature still isn't working for English language users.

How's the review progressing, soundtec?  Have you got a deadline to meet, or is the committment fairly open ended?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on May 24, 2018, 10:35:56 pm

Does it work correctly when using directly the FP,  without PC Software?
I had to add an ON/OFF button for each function on the PC Software because otherwise it was impossible to handle correctly the start and stop of these functions.
I just made a test on modulation function with PC Software v0.7 and the modulations seems to start each time I push the modulation ON/OFF button...

Hi fremen67,
Yes it works the same way with the Front Panel:

PWR-ON : CH1=CH2=OFF
I entered the channels' parameters : CH1 = sine, 2 Vpp, no offset and CH2 = sine, 1.5 Vpp, no offset
Then I put CH1 ON and I measured 1.02 Vpp -100KHz signal on the scope
I pressed MOD : FSK mod OK, I pressed again MOD : ASK mod Ok, I pressed again MOD : PSK mod OK, I pressed again MOD : Burst mod OK
next is AM : I pressed MOD and I got a non modulated carrier 100KHz at 770 mVpp
at this step : 2 different cases :
1) I put CH2 ON  and the carrier was still unmodulated but at 1.03 Vpp,
    then I pressed MOD (which stayed on AM) and I got a modulated signal at 50% ( default value for modulation ratio parameter).
2) I pressed SOURCE and I got a 520 mVpp unmodulated carrier as was in "VCO_In mode" but w/o any signal on VCO_IN
    I pressed again SOURCE to come back with CH2 source and I got a 770 mV unmodulated carrier
    I put CH2 ON and I got a 1.03 Vpp unmodulated carrier
    I pressed MOD which stayed on AM and I got a 1.03V modulated signal
This behavior is very close to what I obtained with the PC software.
Hope it will help you.
Cheers.
Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 24, 2018, 10:48:19 pm
No presure from them at all Dave , Sure I could do somekind of review ,but end of day its almost identical to the old model ,so theres not much to add to whats being said here .

I think we kinda jumped one step ahead of ourselves with the firmware upgrade , as I said though my V3.2 looked like it wanted to download and upgrade to V3.4 ,and the 6800 V1.6 wanted to jump to 3.4 also . Im guessing at the factory they need to organise  a special update for each version of the machine and maybe also depending on what mhz of unit you have .Even though its early days being able to pull up machines V3.2 to 3.4 looks highly likely at this stage .

Yeah it appears the language was set wrong in the V5.8 on the website , it did lead to some hours researching the ways of changing the language codes in the installer ,but that didnt work in the end either ,I also tried to convert the standalone chinese v5.8 exe to english ,again it still only loaded up in chinese in the end. If anyone can figure out a way of changing the language  in the version with the firmware bootloader tab it would still be interesting to decode those usb and other windows that pop up when you try the update .What would be a lot less trouble was if we had a chinese Fy6600 owner translate for us directly the pop up windows .





Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 24, 2018, 11:06:34 pm
Today I found the guts to try the upgrade on my V3.3 but it won't go past about 10% of what I presume is the download part.  >:(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 25, 2018, 08:37:36 pm
Would be interesting to see if older firmware versions are recognised by the software update tab on the standalone chinese V5.8 software.
Fingers crossed the firmware updates will be effective for the V3 people who were affected by the memory corruption issue .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 25, 2018, 08:37:43 pm
What would be a lot less trouble was if we had a chinese Fy6600 owner translate for us directly the pop up windows .

We'd probably learn that the string of "?" in the pop ups translates as "Error."   ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 26, 2018, 03:12:41 am


Ok I managed to get the chinese version with the firmware upgrade to display properly , I captured both the messages that result from trying to update firmware ,picture quality is shocking ,but its hopefully good enough for your friend to read it Miti.

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 26, 2018, 06:42:27 pm
Well done, soundtec! There's nothing wrong with the picture quality at all - they're both very clear.  Out of curiosity, what settings did you need change / hoops did you have to jump through, besides installing the Chinese language packs, to get that result?  Windows7 is supposed to have Chinese support by default, but it doesn't work on my computers, and it's supposed to be a real pain to get it working in Windows10, from what I've read.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tsman on May 26, 2018, 07:08:40 pm
The big dialog box is asking if you want to upgrade the firmware? don't interrupt the firmware update process or you'll brick it.
The little dialog box is saying USB connection error.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on May 26, 2018, 07:42:16 pm
Just standard warnings and messages then - but what's the mention of USB in the big box, and why the USB error message when the USB connection is already working?  It looks like the whole process isn't quite ready for rollout yet.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 26, 2018, 08:04:22 pm
Thanks for the translation TSman.

To get the the chinese software to display properly in xp I had to go to control panel , regional and language options .then tick the box for east asian languages ,when you press apply you will be asked to insert the win xp installation disk . Some files copied over from the disk ,although I think I needed a couple of extra files that couldnt be accessed on the cd for some reason .
Once that is done then go to the advanced tab ,select chinese(prc) as the default language for non unicode programs , then reboot ,
Now your chinese software package should load up ok with the correct fonts . Windows 7 is very similar so its almost the same procedure. Win 10 I dont know how to fix ,but it should be possible .

I did also have a go at trying to make the chinese installer display in English , I tried loads of ways to do it including Indigo rose setup factory trial,resource hacker ,resource tuner and microsoft applocale ,none of these programs made  the program display in English though. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tsman on May 26, 2018, 09:38:23 pm
what's the mention of USB in the big box
It says during the upgrade, make sure not to disconnect the USB connection between the computer and the signal generator.

The two dialog boxes don't give any useful information about the upgrade process or the bootloader unfortunately.

why the USB error message when the USB connection is already working?
As you said, it is just a generic error. It must be expecting a specific response and it isn't getting it so just says USB connection error. The actual USB connection itself is okay.

It might be worthwhile to run a USB sniffer like Wireshark and work out what exactly it is sending. Working out the expected response may not be easy without disassembling the PC tool or sniffing the traffic on a FY6800 unit if that does accept an upgrade.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 28, 2018, 03:45:15 am
Does anyone have a comparison of the HP 33120A to a F***Tech FY-6600?  In particular jitter, but general performance also.

The last few months I've bough a bunch of 90's vintage HP gear.  The user experience is so much better that I really don't  feel much like messing with this turkey.  My programmers arrived, so  I can repackage the thing into a PC interface unit, but I'm increasingly beginning to despise Chinese T & M gear.

If anyone in the US is interested in a V 3.0 60 MHz FY-6600 PM me so we can discuss.  I mounted a 3 wire IEC socket the day before it borked itself.  Ran great for 2-3 hours.  I turned it off and went to bed.  Next day it had the classic screen corruption.

I look at 2 shelves of HP gear and I look at the F***Tech and I'm left thinking WTF am I doing with this?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 28, 2018, 05:56:25 am
Does anyone have a comparison of the HP 33120A to a F***Tech FY-6600?  In particular jitter, but general performance also.

The last few months I've bough a bunch of 90's vintage HP gear.  The user experience is so much better that I really don't  feel much like messing with this turkey.  My programmers arrived, so  I can repackage the thing into a PC interface unit, but I'm increasingly beginning to despise Chinese T & M gear.

If anyone in the US is interested in a V 3.0 60 MHz FY-6600 PM me so we can discuss.  I mounted a 3 wire IEC socket the day before it borked itself.  Ran great for 2-3 hours.  I turned it off and went to bed.  Next day it had the classic screen corruption.

I look at 2 shelves of HP gear and I look at the F***Tech and I'm left thinking WTF am I doing with this?

I can't speak to the user interface quality of the HP, but the specs from the FY6600 are undoubtedly better than the 33120A.

The FY6600 has a 6 times larger sample rate, more than 10 times more waveform storage, 2 more bits of amplitude resolution, 4 times higher sine wave bandwidth and much better square wave bandwidth, and 6 times better jitter on triangle/arb waveforms. The HP doesn't list square wave jitter specs, but if it operates at all like the FY6600, I would wager that is jitter is also one sample clock, so probably 25ns on the square edge, which is also 6 times worse than the FY6600.

The harmonic distortion figures and spectral purity may be better, I don't know the FY6600 specs offhand, and the HP may also be better at modulation, but overall the FY6600 absolutely blows the HP out of the water specs wise, and at the price point is basically impossible to beat.

You would likely be better served just buying a new FY6600/6800 and modding it.

If you are curious, here is the spec sheet for your HP device:
HP 33120A Datasheet (https://www.keysight.com/main/redirector.jspx?action=obs&nid=-536902324.3.00&lc=eng&cc=US&ckey=1000032746%3Aepsg%3Adow&pubno=5968-0125EN&ltype=LitStation&ctype=EDITORIAL)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 28, 2018, 11:16:40 am
Try to power it up while pressing 1, 2 or more random buttons. You may find something.

The engineering mode for frquency calibration is entered by pressing and holding the front panel power and Ch1 buttons whilst turning on the main power switch at the back.  It's probably the same, or something very similar (Power + ?), to go into update mode (assuming v3.2 has one).

I tried pressing Power and Ch1 while turning the power on, but I just hear the relays clicking and it goes in stand by mode. What's the procedure to do the frequency calibration? Is it done through the FP or PC?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on May 28, 2018, 01:18:12 pm
They quote a figure of .5% for thd in the fy6600 ,at audio frequencies its probably bit better .

Hi Miti , its the fp you use to get the freq cal mode , Hold fp powerbutton and ch1 down ,then switch on the power at the back of the unit ,hold the buttons for a second or two and release , now when you enter the system mode you'll see the freq cal in blue at the end of the screen .Once you've adjusted your offset power it off and back on .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on May 29, 2018, 12:05:42 am
Thanks soundtec! I just want to mention that I had to long press the encoder button for it to save the calibration.
Boy, that's much better but the amount of jitter in that oscillator is unbelievable.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on May 29, 2018, 12:14:13 am
Boy, that's much better but the amount of jitter in that oscillator is unbelievable.

Interestingly enough, the square wave (jitter only arises in square wave signals) jitter specs are competitive with if not entirely better than any of the lower spec (but much higher price) signal generators from HP, Rigol, and Siglent
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on May 29, 2018, 01:42:57 am
FWIW The Keysight 33622A jitter is <1 pS.   Of course, even used it is ~30x the price.

And jitter *will* be applicable to *any* AWG output.  But perhaps not as noticeable.  On a sine wave it will show up as THD and phase noise.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on June 01, 2018, 02:17:37 am
The sweep of a 10.7MHz ceramic filter using FY6600.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on June 07, 2018, 05:10:14 pm
Hi Derkammi,
You performed a real great job on the schematics.

About the FP, on my board I noticed  :

R2 = RT1 = 1K

and I have a slight difference with R3 & R4 : 5.1 K (see attached pic) measured 5K

Thks.
Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on June 07, 2018, 06:46:30 pm
Just for the sake of comparison I measured R3/R4 in my 6800 , 5.15 and 5.13 kohms .
Went back and measured R3/R4 in the 6600 found both were 5.02 kohms .
Im not sure if precision is really required here , I need to refer back to the schem.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on June 08, 2018, 01:44:54 am
Fremen67,

I just received my bluepill. It doesn't seem to work for me. It is detected, I can adjust things, I hear the relay clicking when the amplitude reaches about 5V but there's nothing coming out of either channel. FY6600 Ver. 3.3 with bluepill V0.7.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on June 08, 2018, 09:27:55 pm
Fremen67,

I just received my bluepill. It doesn't seem to work for me. It is detected, I can adjust things, I hear the relay clicking when the amplitude reaches about 5V but there's nothing coming out of either channel. FY6600 Ver. 3.3 with bluepill V0.7.
Hi miti,
Thank you for the feedback,
I converted and flashed your v3.3 dump to my test 6600 and had the same behaviour.
DC is still working for me. Can you confirm that it is still working for you? If you have time, you can try flashing your 6600 with a v3.2 flash dump. It should work.
I also tested bluepill on the 6800 I received today (v1.6) and have the same problem. Only DC is still working with bluepill. I should be able to find the protocol modifications with my LA. Hopefully they will be the same on 6600 v3.3.

@cybermaus: As my minipro was connected to the FY6600 I also tried with a v3.1 dump. I can also reproduce the problem you have. It comes from the FPGA continuously reporting after the init that the flash is busy, which blocks the flash read test. A time-out will solve the problem in the next blepill version.
I attached the converted v3.3 flash dump plus a photo, just for teasing ;-)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on June 09, 2018, 05:28:27 am
Hi fremen67,

Yes DC seems to respond but the level is way off. It is almost double of what I set.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on June 09, 2018, 12:49:35 pm
Hi fremen67,

Yes DC seems to respond but the level is way off. It is almost double of what I set.
OK. Strange. Did you use 50 ohms output load ?

Just for the records. A FY6800 v1.6 flash dump.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: LeSilverFox on June 09, 2018, 01:25:03 pm
@Miti

May I ask about your setup for the swept filter pictures you posted. Is your 6600 model with the blue-pill board? and are you creating a ramp signal on CH2 and feeding it into vco-in?
I can’t seem to get it right with my unmoded 6600. If I use an external ramp, can get it similar waveform but not with the 6600 alone. Admittedly, not very experienced in this field.
Thanks for any hints.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on June 09, 2018, 07:01:16 pm

OK. Strange. Did you use 50 ohms output load ?


Nope  :-[ I did not. But now that I did is still off. Below is a list of DC voltages with and without 50 ohm load.

Set  Measured 50Ohm  Measured HiZ
1V   0.76                      1.53
2V   1.52                      3.03
3V   2.37                      4.70
4V   3.45                      6.26
5V   3.95                      7.79
-1V  -0.75                    -1.5
-2V  -1.50                    -3.01
-3V  -2.34                    -4.64
-4V  -3.11                    -6.17
-5V  -3.89                    -7.71

Using the FP I get about half of the set value which is weird. I would expect the value on the display to be the real output voltage and not a would be peak to peak ... which doesn't happen since we're talking DC.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on June 09, 2018, 07:13:15 pm
@Miti

May I ask about your setup for the swept filter pictures you posted. Is your 6600 model with the blue-pill board? and are you creating a ramp signal on CH2 and feeding it into vco-in?
I can’t seem to get it right with my unmoded 6600. If I use an external ramp, can get it similar waveform but not with the 6600 alone. Admittedly, not very experienced in this field.
Thanks for any hints.

No and no, it is a 6600 using the front panel and I'm not creating any ramp, is way easier than that:

Set CH1 of 6600 to SINE, 10.7MHz and connect it to the input of the spectrum analyzer.
Set the output level to get about 0dBm on the SA.
Set the 6600 to sweep between about 9.5MHz and about 12MHz (for a 10.7MHz filter)
Set the SA span to match the generator sweep.
Turn on MAX HOLD on your SA and observe that it generates a flat response
Now insert the filter between the 6600 and the SA, disable MAX HOLD to clear the trace and enable it again

After few minutes you'll see the filter response. It is not 100 accurate though, the ceramic filters are not 50Ohm but is close enough.[/list]

Edit: I forgot about setting the SA span to match the generator sweep.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on June 09, 2018, 10:17:22 pm
Below is a list of DC voltages with and without 50 ohm load.

At least it has almost 50 Ohm output impedance  :)

Code: [Select]
SET 50 Hi-Z Z [Ohm]
1V 0.76 1.53 49.67
2V 1.52 3.03 50.17
3V 2.37 4.7 50.43
4V 3.45 6.26 55.11
5V 3.95 7.79 50.71
-1V -0.75 -1.5 50.00
-2V -1.5 -3.01 49.83
-3V -2.34 -4.64 50.43
-4V -3.11 -6.17 50.41
-5V -3.89 -7.71 50.45
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on June 09, 2018, 10:53:13 pm
Below is a list of DC voltages with and without 50 ohm load.

At least it has almost 50 Ohm output impedance  :)

Code: [Select]
SET 50 Hi-Z Z [Ohm]
1V 0.76 1.53 49.67
2V 1.52 3.03 50.17
3V 2.37 4.7 50.43
4V 3.45 6.26 55.11
5V 3.95 7.79 50.71
-1V -0.75 -1.5 50.00
-2V -1.5 -3.01 49.83
-3V -2.34 -4.64 50.43
-4V -3.11 -6.17 50.41
-5V -3.89 -7.71 50.45

After replacing the op-amps with THS3095. I haven't checked before.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on June 10, 2018, 02:35:22 pm
@cybermaus: As my minipro was connected to the FY6600 I also tried with a v3.1 dump. I can also reproduce the problem you have. It comes from the FPGA continuously reporting after the init that the flash is busy, which blocks the flash read test. A time-out will solve the problem in the next blepill version.
I attached the converted v3.3 flash dump plus a photo, just for teasing ;-)

I just got back from all my work-trips yesterday, should be trip-less for a few weeks, so maybe I can participate again.
As to the 3.1: Good to know, thanks. However, I still have it on 3.2 Winbond, with no averse effects, so I will keep it like that.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rf-loop on June 11, 2018, 08:26:30 am
Boy, that's much better but the amount of jitter in that oscillator is unbelievable.

Interestingly enough, the square wave (jitter only arises in square wave signals) jitter specs are competitive with if not entirely better than any of the lower spec (but much higher price) signal generators from HP, Rigol, and Siglent

Facts and fictions are not often equal. Do you have any data behind your claim or is just trumpth instead of truth.
Manufacturer is perhaps not interest about facts (ref. published some kind of details/specs) but if any other have facts, please do not hide facts.


Where I can find manufacturer published FY6600 jitter specifications based to reliable measurements for Square wave (or what ever wave) or even somehow trusted third party measured data.

Example Siglent low end SDG1000X series:'
Square wave and Pulse Max (aka worst case)
Jitter (rms), Cycle to cycle 300 ps + 0.05 ppm of period


(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=453376;image)
In this image just one real measurement for simple example. (freq selected so that it is not any "golden" freq related to reference and/or sampling rate (what is 150MSa/s in SDG1000X)
Of course Arb have cycle-cycle peak peak jitter 6.7ns (1000/150) excluding some "golden" special frequencies. Also triangle wave have this jitter. This is more (worse) than 4ns what is sampling period based jitter in FY6600 (what is FY6600 real total cycle-cycle jitter is unknown least for me without any real trusted measured data)
Note that in example image have sum of all errors, not only generator. With this level of jitter there come also oscilloscope trigger jitter, noise and timebase jitter must be taken into account. Only what can say is that SDG jitter is unknown amount less than total jitter displayed in image.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on June 11, 2018, 03:54:10 pm
Boy, that's much better but the amount of jitter in that oscillator is unbelievable.

Interestingly enough, the square wave (jitter only arises in square wave signals) jitter specs are competitive with if not entirely better than any of the lower spec (but much higher price) signal generators from HP, Rigol, and Siglent

Facts and fictions are not often equal. Do you have any data behind your claim or is just trumpth instead of truth.
Manufacturer is perhaps not interest about facts (ref. published some kind of details/specs) but if any other have facts, please do not hide facts.


Where I can find manufacturer published FY6600 jitter specifications based to reliable measurements for Square wave (or what ever wave) or even somehow trusted third party measured data.

Example Siglent low end SDG1000X series:'
Square wave and Pulse Max (aka worst case)
Jitter (rms), Cycle to cycle 300 ps + 0.05 ppm of period


(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=453376;image)
In this image just one real measurement for simple example. (freq selected so that it is not any "golden" freq related to reference and/or sampling rate (what is 150MSa/s in SDG1000X)
Of course Arb have cycle-cycle peak peak jitter 6.7ns (1000/150) excluding some "golden" special frequencies. Also triangle wave have this jitter. This is more (worse) than 4ns what is sampling period based jitter in FY6600 (what is FY6600 real total cycle-cycle jitter is unknown least for me without any real trusted measured data)
Note that in example image have sum of all errors, not only generator. With this level of jitter there come also oscilloscope trigger jitter, noise and timebase jitter must be taken into account. Only what can say is that SDG jitter is unknown amount less than total jitter displayed in image.

I understand your reticence to believe what I said about the jitter specs, but what I am saying is not just pulled from my ass, it's read directly off the data sheet of the devices that I have listed (and provided links to) in my posts.

Those are the maximum jitter specs claimed by the manufacturer. If you actually possess those devices (ideally multiple devices of the same model number for each model number) please test them, your input on the jitter specifications would be most valuable. After all, more data is better than less data.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: kahe40 on June 11, 2018, 04:56:25 pm
seems like the Siglent-dealer parse this entire board,
and whenever the single magic word 'Siglent' is spoken,
they are on board and enlighten you...

@rf-loop takes the new SDG1060X (X suffix!!!) worth 500€
and compares it to 85€ FY6660 - makes it sense?
OK, Square has nearly no jitter, other Waves have ~7ns ,
Feeltech has 4ns and this is less, or not?
So @SMB784 is right, this is 'entirely better'

And all the allready sold old Siglent 800 or 1000 without 'X'
and Rigols and so on with 100 or 150 MSa/s
are worser than Feeltech with 250 MSa/s.
This is exactly what @SMB784 said.

This is what Siglent says:

edit, image added
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rf-loop on June 11, 2018, 06:31:46 pm
seems like the Siglent-dealer parse this entire board,
and whenever the single magic word 'Siglent' is spoken,
they are on board and enlighten you...

@rf-loop takes the new SDG1060X (X suffix!!!) worth 500€
and compares it to 85€ FY6660 - makes it sense?
OK, Square has nearly no jitter, other Waves have ~7ns ,
Feeltech has 4ns and this is less, or not?
So @SMB784 is right, this is 'entirely better'

And all the allready sold old Siglent 800 or 1000 without 'X'
and Rigols and so on with 100 or 150 MSa/s
are worser than Feeltech with 250 MSa/s.
This is exactly what @SMB784 said.

This is what Siglent says:

edit, image added

Square wave. My comment was, as I underlined in my answer just for Squarewave. Because  this was told is as good as in Siglent or far better. And this was false. (exewpt some ancient many years old models)
And then I also told that pulse also have this low jitter. (wjat jitters are not even specified in FY information.
Also, if you have read, I tell that Triangle and Arb have more jitter, 6.7ns vs 4ns in FY6600.  Of course this one clock jitter (what is only part of total jitter)  in FY6600 is better due to higher samplerate. (if Arb is important). In my world, most important is Sine, Square and pulse functions signal quality. (including pulse width fine adjustmet and rise and fall times adjustment with low jitter.)
btw, it was not SDS1062X. How you think so? There on front panel read 1032X. Price 339 EUR. Worth for every cent. Also it have CE cerified (and in this case it is not only manufacturer own promise, it is fully inspected in independent accredited laboratory with full documents what is base for CE certification, what makes it possible for EU area markets. It is also safety question. 
FY6600 have not passed any this kind of inspections as far as I know. It is only lazy customes officers these can flow inside EU area.
This is also (just one) reason why there is not any company in EU who sell these to end users.

I have not told that FY6600 is total crap junk and not worth for its price in low end hobby use /if user take full care about electric safety) but, wrong claim is wrong claim and they are good to correct. And it was about square wave jitter. NNC

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: kahe40 on June 11, 2018, 06:51:37 pm
Thanks, rf-loop. Price was for 60MHz model to compare, anyway as you sayed,
for hobby or as a toy, it is worth the pain.

By the way, do you know more about the EasyWave technology from Siglent ?
How can they avoid this clock-jitter ?

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on June 11, 2018, 07:13:44 pm
Here is a short explainer on Siglent's EasyPulse technology that reduces Jitter (and other things): Siglent's EasyPulse (https://www.siglentamerica.com/operating-tip/easypulse-technology/)

Maybe we can figure out how they do this. Maybe it's in the FPGA firmware, maybe it's a separate hardware module. Either way, maybe we can make it ourselves!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 20, 2018, 11:09:48 pm
Well, after 7 months.  I finally got a replacement front panel.   With V3.1 FW!!!!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on June 21, 2018, 09:38:07 am
Glad you finally got a result RHB, better late than never as they say , that was a hell of a lot of  |O , takes persistance ,hopefully it all works out from here on.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on June 21, 2018, 10:27:47 am
Amazing. That you got a front panel at all.

That it is not the latest but V3.1 is annoying of course, but so is mine, it works fine. Disspite what people keep saying, only V3.0 has the self-destruct. V3.1 only ever had reports of loss of Sine, but that is recoverable.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 21, 2018, 11:07:16 am
I had to lean on them very hard, which is something I dislike doing.  I'd like to get a PM from anyone who has a V3.0 unit.  I don't want to explain publicly.

I bought a used 33622A from Keysight's eBay store.  If F***Tech will replace the front panel for the other people with V3.0 devices, I'll do a detailed performance comparison of the FY6800.  In light of the roughly 60x price differential the unit should come off looking very attractive.
But I am completely unwilling to do anything that would increase their sales until they behave better.

The really sad part is that if they provided decent support and entered into exclusive distributorship arrangements in NA, EU and a few other areas, they could sell it at $200-250 retail as fast as they could make them.  They would leave Rigol, Siglent and  Instek scrambling to recover.  The F***Tech is an interesting commentary on the unit margins for making low end Chinese T&M gear.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on June 21, 2018, 11:21:53 am
Nasty surprise in the mail this morning ,a letter from Fed-ex demanding I pay import tax/duty on the free FY6800 I got from Feeltech.
Does anybody here have any idea of the legalities of this situation I find myself in ?
Posession is 9/10 th's of the law ,I paid zero for this machine, it was a prize and there is no bill of sale or invoice.
I could try arguing my case with fed-ex or I could just put the letter in the bin and see what happens ,they of course could set debt collectors on my trail ,which wouldnt be much fun ,but my guess is there chancing their arm trying to pin this on me ,maybe they should give Feeltech a shout with a demand for money and see how they get on  :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 21, 2018, 11:57:50 am
I don't know Irish law, but generally ignoring such things is not a good strategy.  I'd suggest responding that you received the item  to do a review of its performance and that as a consequence there is no invoice.  Generally a "prize" is often taxable.  I'd suggest a letter  along the lines of:

To whom it may concern:

I received this unit from the maker for the purpose of  an extended  technical review of its performance.  As a consequence there is no bill of sale or invoice.  I do not think it should be subject to customs duties.

Regards,


Basically, tell them it's on loan from F***Tech.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on June 21, 2018, 12:09:04 pm
Thanks for the advice RHB ,that sounds like a good approach , I'll fish out a few more opinions before making my mind up in any case ,
Cheers,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on June 21, 2018, 12:56:08 pm
How much are they asking for?  For the sake of 20 euros or so, I'd be inclined to save the potential aggravation this could cause and just accept that you got a nice new FY6800 very cheaply.  The 60MHz unit is currently selling for £100 - £110 on ebay from UK suppliers, so paying just 20% of that is still a damn good bargain.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on June 21, 2018, 02:16:29 pm
Thanks Dave,
Yeah ,the actual value is misquoted on the packaging ,in my favour ,but it still comes to 30 euros or so , I could just pay up and be done with it ,but if theres a creative accounting solution I would rather save myself the thirty eurobucks anyday.
Due to a dispute with the dept of social welfare here over biometric recognition , the suplementary payments I was getting on top of what I earn from self employment have been cut off completely for well over a year now ,of course the two things are completely seperate issues , but I loath paying over a red cent to a government who hood winked almost the entire population into being on a biometric database for which there seems to be no legal basis . Data protection comissioner was supposed to issue a report on the legality of this biometric system and the id card that goes along with it over six months ago ,but the release of the report keeps getting bounced down the line ,as far as I can see because it could show that the government were wrong on this.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on June 21, 2018, 04:09:31 pm
I understand your position entirely, soundtec!!  It sounds like the ID card scam the gov here were trying to inflict on us a few years back - £35 for a compulsory bio ID which would have been a colossal failure from the outset due to being too easy to duplicate - a fraudster's dream come true!  Fortunately, it was kicked into touch in 2010, but noises are now being made about resurrecting the scheme :(
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 21, 2018, 04:31:31 pm
An alternate phrasing:

"This unit is a factory demo unit provided for an extended technical evaluation."

That puts the problem in their lap.  And it's a factually true statement.  That is why you received it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on June 21, 2018, 05:23:44 pm
Yeah I did attend a public meeting late last year ,and there was a Scottish professor explained to the group all about the id card system in the Uk and how it fell apart. A government spin doctor had the gall to show up at the meeting too ,asking the question of the panel ,'Is there any right way of implementing this biometric data/card system ?' the panels response was a loud and clear no . Just as the meeting was winding up I asked the spin doctor ,'and your personal interest in this id/card system is ?' he looked up to heaven and walked out of the room ,much to the amusement of the panel ,was only later I realised he was one of the Taoiseachs(prime minister) chief advisers. :-DD

'factory demo unit' and 'extended technical evaluation' definitely two phrases I can use ,cheers RHB

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 21, 2018, 05:42:02 pm
FWIW

I've been looking at sine wave Lissajous patterns of the F***Tech and a 33622A at 10 MHz.  I see no conspicuous jitter, but the F**Tech frequency drifts quite a lot even over very short periods of time.  If I get them matched to 0.01Hz it drifts away in a few seconds.

I just checked using a square wave with the same result.   The 33622A spec is jitter <1 pS.

Obviously this is not a rigorous test, but it does suggest that the chief culprit is the reference oscillator and that a DIY oven would probably make a big improvement.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on June 21, 2018, 06:54:48 pm
I found it tends to stabilise after about 30 minutes ,and gets better when left on longer ,theres a few here who tweaked the clock alright ,definately seemed to improve matters .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 21, 2018, 09:15:27 pm
I'm letting it warm up now hooked up to my 5386A  frequency counter.  I plan to make some observations over a couple of hours.  I wish I had a GPIB interface to automate readings.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on June 21, 2018, 09:16:03 pm
Are you using the stock oscillator in the FY6600? Upgrading to a TXCO really cleaned mine up
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 21, 2018, 09:50:31 pm
Yes this is the stock oscillator. and it is quite unstable.  What TXCO did you use?  How difficult was the installation?

I no longer really need the F***Tech, but it might prove handy to have if it is more stable.  It has certainly consumed a lot of my time.

The Keysight 33622A is really impressive, but it was over 30x more expensive and that was used from Keysight.  It's 1 GSa/S and goes to 120 MHz.  So really only suitable for professionals with business justification and old hobbyists with adequate discretionary funds.

I *really* wish that F***Tech would figure out that T & M gear and bare LCDs are not the same type of business and have to be conducted differently.  I think a 60 MHz FY6800 with proper support (i.e. repair depots in US, EU, etc.  real warranties rather than empty promises, etc)   would easily be worth $200-250  US retail.  But with their current business model,  buying one is just gambling.  There are not enough FY6800s in the wild to know how good they are.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on June 21, 2018, 11:41:18 pm
I used the D75J (https://www.digikey.com/product-detail/en/connor-winfield/D75J-050.0M/CW657CT-ND/1965865) and it is rock solid. I will take some measurements with my spectrum analyzer and post it here tomorrow. It's an absolutely essential upgrade, and puts this device in the same class as many much more expensive devices from the other Chinese (or Taiwanese) manufacturers like Rigol, Siglent, and Instek.

A good switch mode power supply and ferrite, new output opamps, and a nice stable oscillator will run you about $50 and really put this device in a class of it's own
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 22, 2018, 12:44:43 am
Did you post photos of the install?  The thread is beginning to compete with the $20 LCR tester ;-)

Not quite 33622A class though.  But I agree very good and much more affordable for the under 65 set.  I'll be very curious to see what people report about the 6800.  I *so* wish F***Tech would get their act together.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on June 22, 2018, 02:39:32 am
I did the following modifications, see the pictures:

1. Replaced the output op-amps
2. Replaced the power entry port
3. Replaced the stock oscillator with D75J
4. Replaced the 10uF/450V in the power supply with 33uF/400V Rubycon
5. Added one more safety cap in series with the existing one and connected the common point to earth GND
6. Added a 1M resistor from earth GND to GND
7. I added ferrite beads on +12V and -12V
8. Replaced the stock rectifier diodes with Schottky diodes

I tried to increase the capacitors in the power supply but it has a hard time starting, too much inrush and apparently this chip doesn't really have a good soft start.
The effect of all these changes, the jitter went way down to very acceptable values, the output BNC is at almost 0V with 1M to GND as I see in Agilent, the output level goes higher. Unfortunately the +/- 12V on my unit are only around +/- 11.4, otherwise it is not too bad. It can even supply an oven oscillator that I intend to add in the future.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on June 22, 2018, 01:21:53 pm
Thanks.  All clear except the last photo.   What does that show?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: sorin on June 22, 2018, 01:32:36 pm
See the 2 smd inductors on the on the left.

Sent from my Redmi Note 4 using Tapatalk

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scratch.HTF on June 23, 2018, 07:50:40 am
With regard to the high speed DACs where their markings have been sanded off, they correspond to the pinout of the DAC904, but are overclocked given that the DAC904 has a typical output update rate of 165 MSPS @ 3.3V (these DACs are powered by 3.3V in the FY6600) and 200 MSPS @ 5V and that I cannot find a 250 MSPS (or faster) DAC with the same pinout (and interface) as the DAC904 on the Texas Instruments website.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mozee on July 02, 2018, 03:37:55 pm
Thanks a lot Val , but what about calibrating the frequency on FY6800 also the DC offset is way off!!!! how to calibrate those?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 12, 2018, 09:19:40 am
Hi (from France),

I've bought the FY6600 some weeks ago.
Big thanks to all members for very usefull information about this product.

I've done lot's of update :
- Build linear power supply
- Change output amplifiers with a couple of THS3091
- Removed 5th order filter (currently designing a new 11th order filter)
- Added some ESR capacitors

The used DAC seems to be a custom or modified DAC904 or a special "low-cost" and high speed version of the AD9744.
On the original DAC904, adding a 100nF on BW pin limits the badwidth at 1.3MHz (I've tryied this without any succes on my FY6600).

The buffer (LNS1/LNS2) after DAC904 seems not be OPA686 (marking "A86") on my FY6600 but a LMH6702 (marking is "A83A")
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1340574/#msg1340574 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1340574/#msg1340574)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=366988;image)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pa3hfu on July 12, 2018, 10:32:33 am
I cut a peace of tube (bicycle) of 5 mm wide. It goes straight on the knob and it turns much better now!  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scratch.HTF on July 12, 2018, 12:02:33 pm
My tests reveal that the THS3002 has approximately 36 ohms of dynamic resistance with a +/- 12V supply driving a 1 kHz 10V pulse into 100 ohms (50 ohms/50 ohms source/termination) while the AD8009 (HKJ marking) has practically no dynamic resistance driving a 1 kHz 2.5V pulse under the same source/termination conditions.

I also measured losses in the sine shaping filter:
Positive and negative peaks within 2.5V from zero (dB loss/MHz) - AD8009 output used: 0.066/1, 0.132/5, 0.233/10, 0.472/15, 0.648/20, 0.755/25, 0.864/30, 1.159/40, 1.427/50, 1.583/60
Positive and/or negative peaks over 2.5V from zero (dB loss/MHz) - THS3002 output used: 0.067/1, 0.326/5, 0.789/10, 1.339/15, 2.052/20 - firmware limits frequency to 20 MHz under this condition
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on July 13, 2018, 11:57:54 am
I bought a Keysight 33622A just before I received a replacement front panel for my 6600.  Here are a couple of photos of my 8560A with both.

7146 - 6600
7147 - 33622A

Both were set to the same output level using a scope (640 mV after 50 thru terminator).  Mostly the spurs are the output amp in the 6600.  At lower output levels it cleans up.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: VE2UM on July 14, 2018, 05:43:49 pm
This forum is totally CRAZY !!!!!

I just discovered that the main proble with my FY6600 was .... the 50 MHz reference oscillator. I came here and you already found and published it !!!!!

So, my next step is to find a better 50 MHz reference !

The reference provided with the 6600 is so awful, just puting my finger on the epoxy body causes a huge amount of 60 (50) Hz FM humm  !

Furthermore, full of infos about modifications (i seriously thought about a three-prong IEC C14 connector..

Also, i've ordered some stick-on heatsinks for a Raspberry-Pi. I'll put-on one on the ALTERA FPGA.

But with over 60 pages to read, i'll have full of infos !

Again, thanks !
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 15, 2018, 09:04:58 pm
After doing lots of hardware tests and updates, I’ve found a bug.
If a set an output frequency of 5MHz (250MHz div 50), the signal is perfect.
If the output frequency is 6MHz, the signal is awfull and totally unstable.
Duty cycle and phase work less and less as frequency increase.

Why ? Because the output sampling does not use a shift phase sampling algorithm (oversampling/undersampling technique).

I don’t know if the Altera Cyclone IV could provides enough power to implement a shift phase sampling algorithm.

Personnally I’ve always implement this type of algorithm in many audio engine. Feeltech has done a mistake and some functions does not work at high frequency !

Eeerkk !!!

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on July 16, 2018, 06:57:08 am
That would be square wave or sampled wave with hard vertical edges right?

Yes, the sample jitter has been discussed quite a bit already.
But Sine is OK, showing they are in fact shifting the phase during the waveform construct.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 18, 2018, 07:11:50 am
I've tested the output with a spectrum analyser and finishing the design of the new output filter.
I'm going to implement the filter in the next few day.
I also found that my current version of the FY6600 generates lots of harmonics beyond 2Vpp.

Here's theorical frequency response and 10MHz square signal.
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=478616;image)

Linearity between 1M and 120M
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=478622;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on July 18, 2018, 10:20:35 am
I guess all the good weather has the people minds on other things  ,either way its seems to have gone very quiet lately ,
I had trouble even accessing the post as its gone from the top of the test list ,and the search didnt find it .I needed to browse to the webpage on another tab to find the post while already logged in another tab

Anyway good to see some progress Alexvg,
Will you implement the new filter on the existing pads on the board?
designing a small smd based daughter board might be a nice idea if your design works out ,
Presumably you intend better roll off of the out of band frequency ripples and also more linear behaviour over the wanted range .
I'll be very interested in the results of your tests ,how does the new filter design look in the modeling software?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 19, 2018, 05:41:01 pm
Here is a simple test with 2 capacitors of 69pF (to validate the 50R output impedance of the DAC)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=479537;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 19, 2018, 10:49:42 pm
Some measurements...

Channel 1 without 5nd order filter at 2Vpp and 8Vpp
Channel 2 with 1st order filter at 46MHz instead of 5th order filter, tested at 2Vpp and 8Vpp
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=479726;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 22, 2018, 12:53:33 am
I've done the output 11th order filter with SMD components.

(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481091;image)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481097;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 22, 2018, 12:55:18 am
All tests have been done with 50R load.

Sine sweep 0.5-30MHz - Spectrum 1-500MHz lin - 10dB/div - No filter (yellow) vs 11th order filter (magenta)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481547;image)

Sine sweep 0.5-30MHz - Spectrum 1-50MHz lin - 1dB/div - No filter (yellow) vs 11th order filter (magenta)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481553;image)

Sine sweep 0.5-30MHz - Spectrum 0.1-50MHz log - 1dB/div - No filter (yellow) vs 11th order filter (magenta)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481559;image)

Multitone sweep 0.5-12.45MHz - Spectrum 0.1-50MHz log - 1dB/div - No filter (yellow) vs 11th order filter (magenta)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481565;image)

Multitone sweep 0.5-12.45MHz - Spectrum 0.1-500MHz lin - 10dB/div - No filter (yellow) vs 11th order filter (magenta)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481571;image)



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 22, 2018, 12:57:28 am
All tests have been done with 50R load and 20dB att.

Yellow : no filter
Magenta : 11th order filter

1MHz square output
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481118;image)

5MHz square output
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481124;image)

10MHz square output
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481130;image)

25MHz square output
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481136;image)

30MHz square output
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481142;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 22, 2018, 02:43:13 am
Final measurement... with 50R load.

1MHz signal (blue = no filter, green = 11th order filter)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481160;image)


1MHz signal without any filter (yellow)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481166;image)

1MHz signal with 11th order filter (magenta)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481172;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 22, 2018, 02:55:14 am
Result
The filter is not shielded some DAC harmonics could not be correctly filtered. These harmonics and parasitics frequency cound be measured on the output.

Next time ?
Replace 50MHz oscillator with a new one (+/-1ppm).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on July 22, 2018, 07:09:02 am
In the first results measurement, with sine and multitone with linear and log graphs, I think you accidentally swapped the markings between filter and no filter sine curves between the linear and log graphs. At least they would match each other correctly if either screenshot swaps those two. I'd guess the linear should do the swap as it currently claims that the 11th order filter has less loss than no filter.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 22, 2018, 09:29:26 am
Edit: Previous measurements are corrected.

Crosstalk measurement
The crosstalk occurs after the filter, between LNS1/LNS2 and final output.

Yellow curve - CH1 with multitone 0.5-12.45MHz (no filter)
Magenta curve - CH2 off (11th order filter)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481835;image)

Yellow curve - CH1 off (no filter)
Magenta curve - CH2 with multitone 0.5-12.45MHz (11th order filter)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=481829;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 23, 2018, 12:45:00 pm
I'm working on a highly optimized 5th order filter and simple to build to replace the complex 11th order filter which could be hard to build for the beginner.
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482183;image)
or
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482288;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 24, 2018, 09:03:14 am
I've done the schematic of the new filter at build it... With 5% capacitors and inductances (without any sort).

I've currently working on the same filter but with selected capacitors and inductances.

The schematic
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482885;image)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482801;image)

The circuit
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482873;image)
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482879;image)

Multitone sweep -11th (magenta) vs 5th (yellow) order filter, 1dB/div, 100MHz lin
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482807;image)

Multitone sweep -11th (magenta) vs 5th (yellow) order filter, 5dB/div, 100MHz lin
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482813;image)

Multitone sweep -11th (magenta) vs 5th (yellow) order filter, 3dB/div, 125MHz lin
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482819;image)

Multitone sweep -11th (magenta) vs 5th (yellow) order filter, 6dB/div, 125MHz lin
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482825;image)

Multitone sweep - 11th (magenta) vs 5th (yellow) order filter, 10dB/div, 500MHz lin
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482831;image)

Sine sweep - 11th (magenta) vs 5th (yellow) order filter, 1dB/div, 50MHz lin
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482837;image)

Sine sweep - 11th (magenta) vs 5th (yellow) order filter, 10dB/div, 500MHz lin
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482843;image)

Square signal at 2.5MHz - 11th (magenta) vs 5th (yellow) order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482849;image)

Square signal at 5MHz - 11th (magenta) vs 5th (yellow) order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482855;image)

Square signal at 10MHz - 11th (magenta) vs 5th (yellow) order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482861;image)

Square signal at 25MHz - 11th (magenta) vs 5th (yellow) order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482867;image)

Channel crosstalk
Yellow : measurement on 5th order filter channel at off state, 11th order filter channel with multitone sweep.
Green : measurement on 5th order filter channel at off state, 11th order filter channel with multitone sweep at off-state !!!
Magenta : measurement on 11th order filter channel at off state, 5th order filter channel with multitone sweep.
Blue : measurement on 11th order filter channel at off state, 5th order filter channel with multitone sweep at off-state !!!
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=482891;image)

Pro and cons of this 5th order filter "1st version"
- Need to select with high precision the capacitors and inductances
- Very simple and fast to install
- The compensation filter provides excellent linearity
- The square signal is more raw with lot of harmonics than soft square signal with the 11th order filter

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Ebel0410 on July 25, 2018, 08:58:34 am
Hi Alex,

That's a wonderful and helpful hack you did here, many thanks.
Work in progress I would say...

I didn't see the schematics of the 11th order filter published, could you please provide it us with de components values ?
(what filter designing soft are you using, Qucs?)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on July 25, 2018, 12:48:46 pm
Very interesting work.  It got me to wondering if one could load a predistorted waveform instead.  I'd like to have a go at it.

Can someone point me to the instructions for loading ARB waveforms?  The thread is so long now we need an index page.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on July 25, 2018, 11:37:05 pm
Here is the schematic of the first filter implemented (11th order filter without the compensation filter).
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=483923;image)

To design the filters, I use :
- Iowa Hills RF Filter Design v2.2 (http://www.iowahills.com/9RFFiltersPage.html (http://www.iowahills.com/9RFFiltersPage.html))
- RF Tools - LC Filters Design Tool (https://rf-tools.com/lc-filter/ (https://rf-tools.com/lc-filter/))
- LTspice XVII (most of work is done with this software)

To measure the FY6600, I use :
- Rigol DS1054Z (oscilloscope)
- Siglent SSA3021X-TG (spectrum analyzer)
- UNI-T UT181A (multimeter)
- 50R terminators, 20dB attenuator, 2GHz+ BNC/BNC cable...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on August 03, 2018, 10:32:49 am
I've done the new 5th order filter with sorted components : +/-1nH inductances and 0.3% capacitors.
I've changed the 50MHz oscillator with this model : Connor-Winfield D75J-050.0M (+/-1ppm)
https://www.digikey.fr/product-detail/fr/connor-winfield/D75J-050.0M/CW657CT-ND/1965865 (https://www.digikey.fr/product-detail/fr/connor-winfield/D75J-050.0M/CW657CT-ND/1965865)

The schematic is highly optimized with the components I have and PCB parasitics inductance/capacitor.
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489461;image)


This curve result provides 60dB SPUR with the new 5th filter than 50dB with 11th order filter.
Yellow : New 5th order filter
Magenta : 11th order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489467;image)

The lineary between new 5th order filter and 11th order filter
The new 5th order filter provides very good linearity for sine signal (+/-0.3dB 0-30MHz) and multitone signal (+/-0.35dB 0-60MHz)
Yellow : New 5th order filter with sine sweep 1MHz to 30MHz
Magenta : 11th order filter with sine sweep 1MHz to 30MHz
Green : New 5th order filter with multitone sweep 1MHz to 12.45MHz
Blue : 11th order filter with multitone sweep 1MHz to 12.45MHz
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489473;image)



The rejection of multiple points of this new 5th order filter
125MHz at -32dB
146MHz at -41dB
250MHz at -58dB
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489479;image)

The same curve compared to old 11th order filter
Yellow : New 5th order filter
Magenta : Old 11th order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489485;image)

1MHz square signal comparison
Yellow : New 5th order filter
Magenta : Old 11th order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489491;image)

5MHz square signal comparison
Yellow : New 5th order filter
Magenta : Old 11th order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489497;image)

10MHz square signal comparison
Yellow : New 5th order filter
Magenta : Old 11th order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489503;image)

25MHz square signal comparison
Yellow : New 5th order filter
Magenta : Old 11th order filter
(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489509;image)


Conclusion of this new 5th order filter

Pro :
- Simple to implement
- Very good SPUR
- Very good rejection
- Very good linearity

Con :
- The square signal is awfull, probably due to lots of phase variations.

Note:
I use the term SPUR for SPUR, harmonics and artefacts (provides by sine sampling/phase error...)


Next ?
I'm going to remove the implemented new 5th order filter using 0805 SMD.
I'm working on a little more complex 7th order filter using 0603 SMD.
The goal is to provide more better features with a quasi-linear phase (useful for square signal).

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexvg on August 03, 2018, 09:05:48 pm
I've performed a measurement of the frequency response of provided cables.

Yellow : BNC/BNC short cable
Green : BNC/Banana => Banana/BNC cable.

(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/?action=dlattach;attach=489836;image)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 04, 2018, 11:09:13 am
Theres a new version 6 software become available for the fy6800 from feeltech,looks like it has the firmware update option too ,might try it later on .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 04, 2018, 01:55:58 pm
So I tried the update on the 6600 ,no luck ,wanted to jump too version 3.4 but it wasnt happeneing ,
I did the update with the 6800 ,it worked ,its now at Version 1.7 , no visual difference from version 1.6 ,but there must be some difference somewhere .

the 6800 drops into update mode automatically, it seems to reboot a couple of times , its all done in a matter of a few minutes.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on August 04, 2018, 05:34:10 pm
Sounds like a nice improvement.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 12:11:29 am
Has anyone successfully downloaded an arb into the FY6x00 ?
I created .CSV files of my most-used arb waveforms, tried loading them into the FY6800, and the software does not like them, it terminates with "Run-time error 380:  Invalid property value".
The files are simple ASCII real numbers scaled from 0 to 1, which is what most arb software I've used wants to see.
There is nothing in the download from the Feeltech website that gives any details about the file format for arb waveforms.

BTW, this is the same error message generated when I click on the question mark icon for Help in the arb edit mode. There is no help...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 01:18:32 am
I believe you need to re-label the csv files into something else and its as simple as that ,there was a post by Dave R dealing with it somewhere way back if you can find it .Try renaming the files  .fy
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 01:35:59 am
Thanks soundtec. I think this is the post you were referring me to.

Back on waveform files, the FY6600 will accept CSV files, but ONLY if the file contains nothing but the data values up to a maximum of 8192 points.  Clearing out the other cells and info left by wafeform creation software only takes a few seconds in the case of those uploaded by soundtec, so it's just the same as copying the data values into a new text file.  In fact, the software accepts *.txt files as well, so there's no need even ro rename them to *.fy.

The CSV file I created fits that description exactly, but the FY6800 software will not accept it. I've attached the file I was trying to load in, 4096 time domain data points with voltages scaled from 1.0 to -1.0 . Renaming it to .TXT (as it is attached) made no difference.

EDIT : I just saw that your data files had X,Y data pairs per point. So I recreated mine that way. It still bombs with the same error.

(rant: requiring a time value for each data point is stupid, all it should need is the time per point...once...)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 02:08:16 am
you need a sample 8192 long for it to work ,I think there was a problem with other numbers .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 03:47:03 am
OK, so it doesn't want X,Y pairs, only the data points.
I can open the file, it reads in 8192 points. But when I click "Load Data" it gives an overflow error and bombs.
This software is buggy as hell. What a waste of time.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cybermaus on August 05, 2018, 06:19:32 am
I've uploaded several (to the FY6600), never a problem.

I also manually edited one, they are not CSV, they are normal TXT files!
Did you try making one with the tool?

The tool can produce a *.FYC file, which is a "descriptive form" or "a definition" of a wave form. Like "add 1 sine of amplitude 1 to 1 triangle of amplitude 1 and double frequency"
This *.FYC file is next used to calculate the actual points in the waveform numerically, which is in the *.FY file. The latter is just a list of 8192 floating point values between -1 and 1
I attached 1 set as example (4 Sine waveforms added together)


When I manually changed those points, it worked for me, but I admit, I always started with a FY file that was first generated, and then modded it using notepad++. I guess it may matter if you terminate with CR or CR+LF or LF+CR, and using another tool like normal notepad or XLS may mess up those line terminations. Especially if you think its a real CSV and you are using Excel. It's not, it's a flat txt. Just just notepad++

Edit: I checked: all values are suffixed by x20 x20 x0d x0a
meaning <space> <space> <cr> <lf>
The last line is padded with an extra empty line x0d x0a
(https://i.imgur.com/klFvazI.jpg)

When I run it through for example XLS, it indeed drops those extra 2 spaces, so that could be the reason
Just use a more flat editor, like notepad++

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on August 05, 2018, 10:04:45 am
And if everything else fails, look at the file with a hex editor. Sometimes weird things creep in to files with some software, like unnecessary (invisible) BOM characters in the begin, or accidental "phantom spaces" (characters that are rendered as space, but are not considered whitespace by most parsers), etc.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 11:55:50 am
Maybe a more general search of the board is nessesary . Ive done a bit of fooling around with the various big name waveform generation software available ,easywave ultrawave etc . Which is the best of the lot and will make usable waveforms for the FY66,6800 is there any of these packages offer a library or pre-made waveforms that can be uploaded to the feeltech?

Is it possible to modify the name of this post to include the FY6800 version ,so that when someone browser searches Fy6800 this topic shows ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 05, 2018, 01:14:04 pm
precaud - don't use the Feeltech software to upload the data files, use one of fremen67's versions of the control software, which gets rid of the unneccesary and confusing Chinglish options.

If you start with a csv file, open it in a spreadsheet and copy and paste JUST the 8192 data values into a blank text file with either a .txt or .fy extension.  Use Notepad so that you don't get any hidden formatting information saved in the file.  As bugi says, you've probably got an invisible character in the file which is causing the problem.

Try a couple of mine to make sure your software is working ok.

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 01:17:56 pm
Thanks for chiming in, cybermaus.

I also manually edited one, they are not CSV, they are normal TXT files!

For those who may not know, CSV = "Comma Separated Values". It's just a list of data points, separated by a comma or other commonly-used separator. If there's only one data point per line, then CRLF substitutes for the comma.
Excel .CSV files are a little different, they have a few lines of descriptive header before the data points.
But the main feature is, they are simple text files of ASCII-encoded decimal values between +1.0 and -1.0
That is what my software generates. (Actually, its HP's software from the 90's...)
From the FY6x00 software POV, there is no difference between .CSV and .TXT or .SUX, it doesn't care what the file type designator is, as long as the data format is correct, it will read it.

Quote
Did you try making one with the tool?

No. Once I saw that the file format is the usual list of data points, I saw no point (pun intended!).

Quote
This *.FYC file is next used to calculate the actual points in the waveform numerically, which is in the *.FY file. The latter is just a list of 8192 floating point values between -1 and 1
I attached 1 set as example (4 Sine waveforms added together)

Thanks. My files are identical to yours, except a) yours has a blank line at the end (where point 8193 would be is just CRLF), and b) mine uses a small-case "e" for the engineering notation. I wonder if that's making a difference. The blank line isn't likely causing the problem, because the software reads the file in fine, the error comes when loading it into the waveform buffer.

I created a 4096-point version. It reads it in and loads it into the edit buffer. While doing so, it expands it to 8192 points by duplicating every data point. I sent that file to the 6800 and it plays back fine (if duplicated data points is what you want...)

I then edited off one data point from the 8192-point version. The software reads it in, counts the # of data points correctly (8191), and displays the waveform correctly in the graphics box to the right. Clicking "Load Data" loads the waveform into the edit buffer but imposes an ascending ramp modulation on the data and multiplies it way out of bounds. Wierd.

Quote
Edit: I checked: all values are suffixed by x20 x20 x0d x0a
meaning <space> <space> <cr> <lf>
The last line is padded with an extra empty line x0d x0a

Thanks. All mine are CRLF terminated too. No empty line at the end, though.

I'll try making the "e" an upper case and see what happens.

But this has raised two larger questions.
First: I bought this thing mostly for its arb capability. As I wrote in a thread started a couple months ago, I wanted to see if higher-resolution (14-bit) arb could make up for the lack of a real output filter and reduce the clock noise that is created when inevitable waveform delay shifts the samples and puts the stair-step at the center of the sampled point in the FFT. Some here opined that it would. My hunch was (and still is), no, it won't, there's no substitute for proper output filtering. This was a cheap way of testing it out, so I went for it.

Second: Only now have I learned that all waveform files have to be 8192 points. Can I live with that? I already know the answer: No. I need the flexibility of point-by-point waveform playback of any number of data points. Not all digitizers use power-of-two-based time record lengths.

So I'll try changing the "e"s to "E"s. But even if/when the data format issue is solved, it appears this unit is not going to do what I want.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Philipp F. on August 05, 2018, 01:52:03 pm
Hey,
I am a somewhat inexperienced electronics hobbyist and I'm in the market for a signal generator for testing various things and circuits because my cheap Chinese 3 knob signal generator kit isn't cutting it anymore.

I really want to get the FY6800 because of all its functions (the VCO and sweep stuff really interests me) and it costs about right what I can spend, but all this talk is kinda deterring me...

Is it worth getting or do I risk ending up with a 115€ brick?
I can get it shipped from a Germany warehouse, so I could at least hope for a basic 2 year warranty (and the seller also advertises 2 year warranty).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 05, 2018, 02:34:51 pm
precaud - I've just spotted the file you posted, and it loads into fremen67's 0.7 version of the control software, so it should upload to your 6800 ok (although what it will do to the 6800 when you run it is anyone's guess  :)).

Regards,
Dave

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 02:42:26 pm
@Phillip F., you can ignore all this talk, we're just getting into the weeds on some details.

So I changed the "e"s to "E"s, put a blank line at the end of the 8192-point file, and just for the halibut, renamed the file with a .FY extension. The software reads it in fine. Clicking "Load Data" generates the same error as before, "Run-time error 6 : Overflow".

There are no data points in the file larger than 1.0 or smaller than -1.0 . In fact, there are no data point equal to those values, either. The data conforms to all the rules. So the raw data is not the cause of the overflow.

This is the arb waveform I use more than any other. If it won't work with this, there's no point to me going further with it.

I've attached the file (with extension .ASC) if you're interested to see it.

DaveR - I just saw your post. That file is 4096 data points. It loads into the 6800 fine for me too, except every point is duplicated. Try the attached one and see if that works. Meanwhile, I'll look for fremen67's 0.7 version and try it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 02:43:54 pm
Im just having a look at bitscope data aquisition ,seems really good whats going on here .

http://bitscope.com/news/ (http://bitscope.com/news/)

I just downloaded the software to have a look , the idea of using a farm of rasberry pi's for data aquisition /processing looks nice
Theres a guy I know who runs a reseach project for one of the universities here ,he's invloved in siesmic data aquisition  from sea bottom tranducers around the coast ,I bet he could save massively on his overheads by creating his own supercomputer from PI's.

Thats great you had time to consider waveform generation as a way of improving the performance of the Fy66/6800 Precaud,
its a question we debated a bit over the time on this topic.

Theres a few small additions on the Feeltech version 6 software that would improve it  , one is the addition of a refresh button like Fremens put on so any changes in values on the instrument itself can update the software display values,in any case toggling the 'auto connect' option reloads the values from the front panel ,  would it be possible to make a push of the encoder wheel button to get  the FY  to transmit the data from the unit to the software or could it be made to do that automatically ? seamless integration between front panel and software would just make life a small bit easier and would make whats already a very intuitive machine  really sweet. Maybe Fremens could take another crack  at hot roding Feeltech Version 6 software ,the bluepill idea is nice and allows a lot more flexibillity ,but I dont see how front panel and software can live side by side in that scenario .

 I very much like the idea of using both my  66'&68' series as four channels of audio tone generation, run from a midi sequencer  tones could be layered up to  tracks and effects and gating on the analog end could be used to produce large musical 'swirlls'.
I have a pair of boss Ce-5 chorus's run in stereo, by flipping the phase of the clean and effect return a whole load of subtle to mad wobulation type effects are possible ,flange, phase, chorus and vibrato can all be had with different panning and phasing arrangements , add in tube driven spring reverb and speed controlled mk2 Watkins copicat for tempo synched delays ,hitting one key you can sound like Vangelis or Jean Michel Jarre ,same effects chain sounds absolutely great on an open tuned guitar set up for bottle neck slide ,Id be interested to hear from any others who are already using their FY for sound and music purposes ,the foundations of electronic music were born out of laboratory equipment after all .

That last one you sent loaded up fine for me in version 6 Precaud,


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 05, 2018, 02:45:32 pm
Is it worth getting or do I risk ending up with a 115€ brick?
I can get it shipped from a Germany warehouse, so I could at least hope for a basic 2 year warranty (and the seller also advertises 2 year warranty).

No-one has reported a brick this year, as far as I can recall, so you can feel pretty safe with the latest versions of the 6600 or 6800.  Most of the talk on here for a long time has been about making the 6600 a better machine, which we've succeeded in doing, but the 6800 will be fine out of the box as it already includes some of the improvements which were required.  (And it will be in a different league compared with those you've used so far.)

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 02:54:33 pm
That last one you sent loaded up fine for me in version 6 Precaud,

Interesting, soundtec. That's the version I'm using...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 05, 2018, 02:56:57 pm
DaveR - I just saw your post. That file is 4096 data points. It loads into the 6800 fine for me too, except every point is duplicated. Try the attached one and see if that works. Meanwhile, I'll look for fremen67's 0.7 version and try it.

Loads fine for me - see attached.  (Just renamed it to chrp8k.txt and in it went!)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 03:07:01 pm
OK thanks guys, I guess I need to download and reinstall the software again.

BTW, the way to detect if data integrity is maintained is to load it into the text window first. That's where I saw it was duplicating points onthe 4096-point file.

Is there a link to the fremen67 version? I looked through this volumnous thread and found lots of talk but no link.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 03:16:14 pm
Here's Fremens last few versions ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 03:18:54 pm
Ive just downloaded an old version of picoscope for free to try and see if it will allows waveform selection from a library usable with the FY6600.

https://www.picotech.com/downloads (https://www.picotech.com/downloads)

drawing a waveform could take ages ,surely theres a repository for such waveforms and you could have an endless variety 

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 03:50:11 pm
I downloaded the software again (this time from Google Drive), reinstalled, ran, and got the same error as before. It loads into the "Extraction" Window, but when loading it into the Waveform Window, it bombs (see attached). IIRC, this software is Visual Basic code. Maybe it needs a later version of VBRUN than I have?

I then installed the 0.7 version of fremen67's software (thanks, soundtec). It loaded the file directly into the Waveform Window and uploaded it to the 6800 fine (I think, I haven't looked at the output yet).

To verify the data is correct, I tried loading the file into the Text Window (using Loading Area 2) so I could examine the data and see if it was being converted correctly. This window does not work correctly, it displays all values as 0, 1, or -1. I turned off "auto-resize data", with the same results. I then tried sending the data to the 6800 (loading Area 2 goes to ARB2 waveform). The waveform sent was the same array of 0, 1, and -1 values. So loading into the Text Window destroys the data, and there's no way to verify that the data values are being converted correctly.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 05, 2018, 04:27:34 pm
To verify the data is correct, I tried loading the file into the Text Window (using Loading Area 2) so I could examine the data and see if it was being converted correctly. This window does not work correctly, it displays all values as 0, 1, or -1. I turned off "auto-resize data", with the same results. I then tried sending the data to the 6800 (loading Area 2 goes to ARB2 waveform). The waveform sent was the same array of 0, 1, and -1 values. So loading into the Text Window destroys the data, and there's no way to verify that the data values are being converted correctly.

I never could understand what the Text Window was supposed to be doing - even fremen's version seems to just convert all the data points to integers (try loading the sinc-pulse file I uploaded earlier, and you'll see the waveform in block form with values -1 to 5). 

If you upload to Loading Area 2, won't you overwrite the factory-stored square wave there?  The empty loading areas are from 64 back to ?? (can't remember offhand).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 04:29:50 pm
 I looked at the output waveform (with an 8-bit scope) and the data transferred from the Waveform Window using fremen67's program appears to correct. None of the duplicate time data points that I saw before. So this can be a realistic basis to my comparison tests. Thanks for your help in gettin g this sorted out!   :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 05, 2018, 04:34:05 pm
I never could understand what the Text Window was supposed to be doing - even fremen's version seems to just convert all the data points to integers (try loading the sinc-pulse file I uploaded earlier, and you'll see the waveform in block form with values -1 to 5). 

With ver 6 SW, it showed the data values scaled to signed 14-bit integer values. I would think that is what it is supposed to show.

Quote
If you upload to Loading Area 2, won't you overwrite the factory-stored square wave there?  The empty loading areas are from 64 back to ?? (can't remember offhand).

Could be - I wasn't paying attention to that  :)  I assume there's a way to reset the unit and restore the original factory waveforms?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 05, 2018, 04:57:16 pm

Theres a guy I know who runs a reseach project for one of the universities here ,he's invloved in siesmic data aquisition  from sea bottom tranducers around the coast ,I bet he could save massively on his overheads by creating his own supercomputer from PI's.


Who is it?  I'd like to look into it.

FWIW Intel and AMD CPUs are more cost effective than any of the alternatives.  The basic problem is tuning the software to particular architectures.  Most algorithms are trivially parallel so everyone just runs 10-20,000 cores for a week or two for industrial work.

Seismic is both CPU intensive *and* I/O intensive.  For example, Kirchoff migration requires summing 10e5-6 points into 10e12-14 points.  And that's the *fast* algorithm.  The serious stuff is an order of magnitude more work. I have an MPI based Kirchoff code I'd be happy to give to him.  I wrote it as a commercial project when I got laid off in '98, but faced with the cost of selling it vs a job I was offered, I took the job.

If he's using the CWP SU package then he will know who I am. I did a lot of work on it for many years and also arranged for the SLT SU version to be donated to MInes. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 05, 2018, 05:09:02 pm
If you upload to Loading Area 2, won't you overwrite the factory-stored square wave there?  The empty loading areas are from 64 back to ?? (can't remember offhand).

It's ok - just my memory fading again!  There are 97 slots in all, 33 for presets and 64 for User / ARB.  The first 32 ARB slots already contain copies of most of the presets, which can be overwtitten, and slots 33 - 64 are empty.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 05:35:56 pm
Thanks for that Rhb, :clap:

I'll certainly tell him next time I see him ,he was supposed to be in touch about his music projects but I didnt hear back ,I dont have a number for him but I'm likely to see him or one of his brothers in the neighbourhood at some point . Like all research he has to justify his budgets ,something neat and tidy like PI/Bitscope data aquisition farm might allow him to get very good number crunching horsepower for small money , I think it probably takes time to interpret the data the way he's set up now ,but the possibility of realtime or near realtime processing sounds very exciting . A portion of the work involves the use of gps synchrous clocking and triangulation  to work out very precisely the locations of the under sea Hydrophones ,then precise sum and difference calculations can be done to determine the depth as well as latitude and longitude of siesmic events. Its easy to see why such a system could be of value for coastal patrol/protection too, but they do say even the ocean has had ears for years and years ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 05, 2018, 07:16:16 pm
Sounds very cool.  I'd love to do some  seismic work again even if I didn't make any money as long as it presented a new and different problem.  It sounds as if your friend has one.

I got 3 HP Z400s with 6 GB of ECC DRAM and quad core 2.9 GHz Xeons for $300 plus shipping via eBay.  That's probably several million times the compute that I shared with the entire department in grad school in Austin.  There's no way $300 worth of Pis will touch that for seismic processing.

Ask your friend if he uses Seismic Unix from CWP.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 08:02:07 pm
Ive been trying out a few of the proprietary wave editors again ,no success as far as getting V6 SW to read waveforms produced by either easywave or TTI waveman, it either stalls or crashes the Feeltech software . I only managed to reload a previously stored waveform created on V6 . Maybe Feeltec need to re-look at the compatibillity here as well .I still cant find a library of waveforms that I can easily slot into the 66/68 hundred
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 05, 2018, 08:06:38 pm
Post  the available info on the formats.  I lost count of the number of format convertors I've written 20 years ago.  There were times I felt as if that was all I ever did.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 05, 2018, 08:39:05 pm
I don't think we need a format converter, rhb, the waveform files are just lists of numbers in plain text, but Feeltech appear to have introduced a bug into the latest version of their PC Control software which causes a crash when the files are loaded.  It's not a great problem because fremen67's software does a better job of waveform uploading than Feeltech's anyway; either software can be used for PC Control, and Feeltech's is only really required for occasional firmware upgrading of the 6800.  They might get the bug sorted out eventually, but it's hardly a showstopper in the meantime.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 05, 2018, 09:28:48 pm
Ive been trying out a few of the proprietary wave editors again ,no success as far as getting V6 SW to read waveforms produced by either easywave or TTI waveman, it either stalls or crashes the Feeltech software . I only managed to reload a previously stored waveform created on V6 . Maybe Feeltec need to re-look at the compatibillity here as well .I still cant find a library of waveforms that I can easily slot into the 66/68 hundred

The editor in Picoscope is the best one I've tried so far, Soundtec - very easy and accurate to draw with, nothing complicated about it, all the controls are obvious and straight to hand, and output in csv format goes straight into fremen's software as is.  If I was going to be doing any freehand waveform design, I think this is the one I'd use.  Is there anything in particular you are looking for?  The only waveform library I've come across is Picotech's, but I guess car engine fault tracing isn't what you had in mind?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 09:57:57 pm
I got picoscope alright ,but didnt get stuck into it yet ,
Im not sure I'll be free handing waveforms ,but now you mention automotive scopes and such things it seems like a good place to try .There seems to be some kind of wave format management in labview ,but thats way to heavyweight a program for me to get stuck into.

I might try copy and pasting the contents of a file created in pico or wave into a .FY style container , I think I did find one way of transfering the contents earlier in the day but forgot again when I changed to different programs ,I'll have another look .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 05, 2018, 11:58:31 pm
I did manage to get Fremens program to make a waveform and it displayed in SW V6 although the phase was reversed . When I tried a waveform created in SW V6 on Fremens again it displayed out of phase also. I havent been able to get a single waveform from any of the other programs to work on the feeltech .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 06, 2018, 01:13:14 pm
With TTi wavemanger I was able to produce a waveform as .asc which would load into Fremens 0.7 software ,then I 'saved as'  and it sucessfully loaded and displayed in the Feeltech software . The waveforms in the TTI are based on .wfm files so maybe some kind of library exists already ,but I could only find a few extra examples of waveforms .I might try filling some of the blank spaces in the memory of the FY later on .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 07, 2018, 01:04:40 am
Does anyone have anecdotal experience on where is currently the best place to buy a FY6800?  Amazon US doesn't have any yet, and something tells me this is not the time for me to start randomly selecting *Bay vendors and trusting to luck.   :P
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on August 07, 2018, 01:14:58 am
Banggood.

https://www.banggood.com/ (https://www.banggood.com/)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: precaud on August 07, 2018, 01:39:11 am
Does anyone have anecdotal experience on where is currently the best place to buy a FY6800?  Amazon US doesn't have any yet, and something tells me this is not the time for me to start randomly selecting *Bay vendors and trusting to luck.   :P

I'll sell you the one I just got. I only bought it to test 14-bit arb vs 12. PM me if interested.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 07, 2018, 10:18:35 pm
I finally got the 5 volt regulator down to a proper working temperature ,I needed to heatsink the ic's and the bridge. Excess heat is directed into to metal screen between powersupply and signal board .I wound the +/- rails up 13.7 volts for a bit more headroom at high output amplitudes ,where clipping was apparent with the original Feeltech power supply of 11.5-12 volts, and as little as 100mV of DC offset caused hard clipping of the output op amps .

I was hoping I could simply swap over the main board and front panel from 6800 to the powersupply and enclosure of the 6600 with the linear supply ,but the recessed screen on the 6800 makes that impossible .

I'll most likely try a dual switchers one for op amp rails and another for 5volts ,for simplicity and size I might reuse the second Feeltech switcher and maybe try adjusting resistor values to increase the dual rail section while leaving the 5volt unloaded completely tends to raise the other rails to some degree as well ,any ideas on that would be greatly appreciated . I was thinking of trying an expanded aluminium mesh as a RF cage for the powersupply to prevent any Rf gash .

I also noticed on my 6600 with the linear that the negative rail measures just 2.2mV ac, the positive rail measures 103mV ac and the 5 volt measures 80mV ac ,is it because of other supplies being derived from the 5volt and 12 volt + that this extra noise exists?
Exactly the same readings from the unmodified 6800 ,so it has to be coming from the signal board


I decided to try the 6600 (15mhz) front panel on the 6800(60mhz) and vice/versa .
Both machines loaded fine ,appart from the waveforms preview being garbled ,the mhz on the 6600 main board now went up to 60 mhz with the 6800 V3.7 front panel and board of the 6800 only went as far as 15mhz with 6600 front panel . One difference I noticed in the 6800  was now when you change between channels if you were previously on say amplitude on ch 1 if you select ch 2 and go back to ch1 it retains the relevant page on both channels  ,where in the 6600 as soon as you change channels it reverts to frequency adjustment by default ,very anoying , Its a minor detail but it does make it nicer to use .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Scratch.HTF on August 08, 2018, 11:15:19 pm
Good idea, but the filter should be able to be switched in and out via a DPDT telecom relay (it can be controlled via a mechanical switch).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 09, 2018, 06:46:09 pm
So I tried using two feeltech switch modes to power the 6800 ,one for 5 volt rail the other for +/- rails .
When I drew no current from the 5 volt rail ,the +/- rails oscillated up and down and were way below the volts they should have been .
I tried adding 40 ohms across the 5 volt rail to draw some current ,and this stabilised the +/- , up around 12 volts but only with a 20 ohm resistor ,it got quite hot . Just goes to show if theres any moments of high current draw on the 5 volt line it can modulate the +/- rails ,not great really .

I guess I could split the 5 volts supply on the main board ,and run some current from both switchers 5 volt lines to stabilise things ,but then my 12 volt rails are too low . Ac milivolts on the supply rails stayed around the same in any case around 100 mV on the positive 12volts around 4 mV on the neg 12 volts line and around 80 mV on the 5 volts rail . The noise must be coming back through the 1117 regulators from somewhere else down the line . Maybe 80-100 mV is nothing to worry about in this situation.

ln the end I ended up reverting to a 2x12volts +  5 volts supply from an old satelite tv box ,bit more juice than the original item .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 09, 2018, 11:47:34 pm
I guess we're still using this thread to comment on and possibly offer feedback to the functionality of the FY6600 and FY6800 units?

I've been playing around with my new FY6800 (thanks to precaud!) and it seems to be able to be coerced into doing everything the manual says; bottom line, it's a great value and will get a lot of use on my bench.  But the frequency units display is rather tedious to decode while trying to quickly enter values.  I was trying to generate an AM modulated signal and it took a couple of tries to get carrier and modulation frequencies which were appropriate to generate the display I was looking for because I was trying to parse uHz on one channel and MHz on the other during the setting procedure.

It seems that the units suffix (Hz, MHz, etc.) is usually updated to a more sensible value after you complete entering the frequency and hit OK.  That's good, and desirable; although I've been able to trick it into displaying 100 KHz as either 0.1 MHz or 100000000 uHz depending on the order in which I entered the data and hit OK.  That's not so good, and could be improved if FeelTech is interested. 

What would make sense to me would be if, as you selected the appropriate frequency digit to change, the unit suffix were to change color, or blink, or something, and indicate the range of the decade you were manipulating.  Ex: as you moved into the digit group setting kHz it could blink "kHz", and if you moved past that into the group covering Hz it could blink "Hz" and then return to a steady indication of the appropriate units after you hit OK and the software was able to determine the value of the highest digit.  As it stands, you could be looking at something silly like "uHz" even while you're in the process of setting 10 MHz, or "MHz" while you're trying to set a frequency of 10 Hz.  More mental effort required on what should be a simple setting.

It's kind of like my soldering stations - I have one which is fixed to display in F and another which is only in C. I can do the math in my head while setting values, but it's something which could be made a little easier for the user.  It would be easier still for the FY6800 user if the software dynamically shifted the frequency display left or right and calculated units as you set the digits, but that would take considerably more effort for the coder to implement - I've done such in the past, so I have a hint of the effort.

I don't know if FeelTech would consider a similar change for future revisions, but I think it would substantially improve the usability of what is already a superb value in test equipment.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 10, 2018, 06:41:07 am
Hi Greg,
Thats great you managed to pick up an unloved Fy6800 from Precaud. There really isnt much to be said against these units in terms of value for money ,and of course you can do many simple mods ,which make it even better .

On the 6600 the encoder has a push switch button ,this allows you to change the display to  uHz Hz Mhz etc , its the OK button on the 6800 does that ,I wasnt sure from your post if you had figured out how to toggle Mhz/hz in the display or not .
And yes do keep posting your thoughts or possible improvements here .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 10, 2018, 07:48:13 am
On the 6600 the encoder has a push switch button ,this allows you to change the display to  uHz Hz Mhz etc , its the OK button on the 6800 does that ,I wasnt sure from your post if you had figured out how to toggle Mhz/hz in the display or not .
And yes do keep posting your thoughts or possible improvements here .

 :palm: Wow, do I feel like a numpty now.  You're absolutely right; I assumed that feature was missing because the encoder doesn't have a push switch (the manual is a hasty conversion from the FY6600 manual, and some things are confusing).  But "OK" cycles through the units very nicely with the decimal point shifting to accommodate and you can quickly enter the desired range/value.  Not necessarily the procedure I would have coded but easy to work with nonetheless!  Once I get accustomed to it there should be no problem.  Hopefully the manual will be updated eventually to make that and a few other small details clearer.

I'd like to see a platform-agnostic interface to upload arbitrary waveforms rather than a PC-only program; that's probably do-able and would allow you to use pretty much any tool to create the data list.  All my computers are Macs, but fortunately I can get by with the predefined waveforms so I'm not bothered by this for now.  FeelTech have provided a pretty thoughtful list of arbs already.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 12, 2018, 01:38:54 pm
Hz,khz etc was one of the  functions I needed to refer to the manual about when I first got the 6600 so nothing to be ashamed about .

Im still only managing 11.6 volts on the +/- with the switcher ,I see the rectifier diodes on the outputs are common In 400x ,could I get a few hundreds of milivolts by using low forward drop diodes here ? or are there easier ways to increase output voltage of switchers ?
Id like to seperate both 5 and +/- onto two different supplies , but the only way I can get the opamp  rails stable and with enough voltage is by using a large resistor to burn off current on the 5 volt line , in the case of a single unit ,could adding more load to the 5 volt line bring up the rail voltage ?

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: svetlov on August 12, 2018, 07:18:36 pm
 Hello Dear Friends   :) which operational amplifiers are installed at the output of the generator? they are different in the models 6600 and 6800?
Thank you  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 13, 2018, 03:52:25 pm
Hi Svet,
Here's a link to an old post ,theres lots on the output stage to be found if you try search in this topic.
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/1150/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/1150/)

I havent lifted the heatsink on my 6800 yet ,there does at least seem to be a change in output op amp package style in the 6800 ,as you will see from my post ,in the original 6600 there was a mismatch in height between the two op amps under the heatsink ,so the heatsink wasnt very effective and was on crookedly .  A couple of layers of heat sink rubber pad fixes this in the 6600.

There is a brand new op amp (THS 3491)suitable for use in the 66/6800 ,only issue was compatibillity with the package/pinout ,I did read that even though its had a different package to the 3002/3095 it was still compatible .The THS 3491 can draw upto 350ma at full output ,so if you decide to try it you will need a bigger psu and output stage heatsink to get any benefits . The other possibility is to populate all three pads in the output section ,two single channel op amps and one dual ,this is easily do-able ,but output padding resistors would need to be re-arranged also.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 13, 2018, 06:35:05 pm
In the above zip you'll find some stuff on the 66/6800 in one place ,instead of having to scan the entire post .Fremens V .5,.6,.7,schematics ,and driver ch340.

Thurlby Thandar Wavemanager 4.10 is nice package thats compatible with Fremens software ,the functionality of the program isnt hampered by not having a TTI device connected ,and theres no nag screens . Requires NI Visa runtime installed . The waveform creation allows a much better range of math functionality,including adding subtracting and multiplying waveforms together .As you create each wave type a selection of parameters becomes available ,the 'heartbeat' wave having around 10 parameters to adjust . Ive created a few interesting paterns with stairstep  mixed with other waves . It will be interesting to hear how these waveforms end up sounding in the audio range . I really want to explore the possibilites of using my 66/6800 for sound and music creation in a modular type setup .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 13, 2018, 10:19:43 pm
I had a spot of trouble with my FY6600 over the weekend, when C82 blew and took the -12.5v rail down to -1.25v.  It happened while I left it running as I went into the garden for ten minutes, and I got back inside to find the scope display scrambled, and the mains transformer and LM337 regulator very hot instead of their usual slightly warm.  I can't see any reason for C82 going bad other than it  being just a faulty capacitor (which turned into a 63 ohm resistor), but fortunately it doesn't seem to have caused any damage to anything else, as all is fine again with a new cap in place.  Maybe it would have been a different story if I was still using the original power supply?

Whilst using Der_Kammi's schematic to trace the fault (C82 is one of the 100nF bypass caps to the IC5A/B op amp, half-under the heatsink on the main board), I noted that the schematic shows IC5 as a JRC 4558DD, whereas my v1.501 board has a JRC 4556A there.  From the datasheets it looks like the 4556 is something of an upgrade over the 4558.

Soundtec - thanks for the Wavemanager 4.1 tip: I've downloaded it, but haven't tried it out yet.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on August 14, 2018, 10:29:01 am
... I can't see any reason for C82 going bad other than it  being just a faulty capacitor (which turned into a 63 ohm resistor), ...

... (C82 is one of the 100nF bypass caps to the IC5A/B op amp, half-under the heatsink on the main board), ...
Would that C82 happen to be an ordinary cheap ceramic SMD? Under a supposedly hot spot? Perhaps uneven thermal expansions, ceramic or its ends breaking, leading to a broken cap? (Certainly the cap could have been bad to start with, or partially damaged from e.g. soldering process, add some extra stress later...)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 14, 2018, 01:41:57 pm
Yes, the very same ultra cheap SMD, but it wasn't actually under the hot spot - which isn't that hot anyway - so thermal stresses would have been minimal.  Under the magnifier you can see that a groove has been burned across one face, and one end is brown and pitted (which is what caught my eye initially).  Just bad to start with, or a bad soldered joint, probably.  I'm waiting to see if its twin, C81, blows as well, as I've now got 49 spares to replace it with :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: danco on August 18, 2018, 11:08:43 am
Hi guys, I,ve been reading this thread all from the start, in the meantime my fy-6600 has arrived, v.3.3. First thing, even before testing it thoroughly, I was swapping the 3002 with 2 pcs. 3091 I bought from aliexpress. All seemed fine until recently I got time to play a bit with it and found that over 5V level a relay made a "click" and the signal at the outputs vanishes. In fact, channel 1 outputs a -11.7V DC, channel 2 outputs 0 V. Consulting the schematic I see that the final stage is switched in by a relay (most likely over 5 V output amplitude) so I think both my aliexpress chips are dead. Switched back to the original 3002 and everything back to normal (in certain limits). Can anyone confirm all this is plausible or I could have made something wrong myself? The chips look genuine, came in original tape cut, but were only $2.79/piece. Any thoughts?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on August 18, 2018, 12:32:52 pm
The THS output is switched for signals over 5V so your assumptions is correct. Most probably the aliexpress parts are a dud.

I decided to go for the TI's original THS3491 which cost me $10 a peace direct order - $20 total with free shipping.
The have been working perfectly so far.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: danco on August 18, 2018, 03:14:32 pm
Where did you buy in BG with free shipping, my suplyer of choice (TME) doesn't seem to stock it?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 18, 2018, 06:39:07 pm
Heres a comparison between the chips I have in my 6600 and the ths 3491, shows very much improved linearity and bandwidth ,I might order the 3491's for my 6800 ,upto 420ma of current x2 ,did you replace the power supply too Bdivi? looks like these new chips could signifgantly reduce harmonics by up to 10 db,the specs quote harmonics for the 3491@50mhz and the 3091@10mhz so if they were measured on a like for like basis you would expect very much improved performance from the 3491 .Which component package is the most appropriate for the upgrade?

Have you done any comparisons before and after the op amp upgrade Bdivi ,to confirm the much reduced distortion of the waveform ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 19, 2018, 04:11:51 pm
Hi soundtec - I think you forgot to post the comparison you mentioned.

By coincidence, I've just received a 6800 which I ordered a week ago, just before C82 blew on the 6600.  It's got a KKMoon logo on the front instead of FE, but it's still a Feeltech instrument - just 20% cheaper!  I was just about to use the £20 saving to buy a D75J oscillator for it, and replace the THS3002 with 3095s as in the FY6600, but then I thought I may as well try the 3491s instead to see what happens.  They'll be a big improvement over the 3002, I know, but now I'll be able to do a comparison against the 3095s as well, where the difference might not be so visible.

The under-load voltages from the SMPS are 4.958, +11.792 and -11.953, so pretty good except for the +ve rail being a bit low.  I'll see how it gets on before I consider any mods to the PS this time.

The D75J is an essential though - I did a frequency stabilty test starting them both from cold, and the FY6800 took over 50 minutes to settle down, compared with just 10 minutes (probably less) for the FY6600.  The total deviation was 41ppm for the FY6800 and just 1.5ppm for the FY6600, so it was a no-contest.

Amusingly, the FY6800 came with a non-UK mains lead and an adapter plug - which has a plastic earth pin!!  I suppose the seller would claim he just sells them, and doesn't have to know anything about them?!

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 19, 2018, 07:26:36 pm
http://www.ti.com/product/ths3491# (http://www.ti.com/product/ths3491#)

Thats the link to the comparison chart with the 3095 , I forgot to post it
Thats a night and day difference with the DJ75J too ,I might get a pair of them in .
I swapped out the diodes in the switcher I use on my 6800 ,with low forward drop diodes on the outputs of the rails +/- ,I instantly got a much better voltage balance across the rails ,the difference now is only a few tens of millivolts ,and I also gained a couple of hundred millivolts bringing my rails to 11.9 volts , might be a simple worthwhile mod for others too .,
In the case of the ths 3491 I fairly sure the heatsink will need attention ,even with the 3095 with both channels flat out into 50 ohms ,quite a bit of heat is generated ,with 3491 its almost double the current and the heat.

It is a bit funny that the cost of the upgrades ,2x3491 and DJ75J arent too far off the cost of the unit itself maybe the 15mhz model at least ,still very much worth the effort for me though . My guess is the upgraded 66 or 68 measures up well against even machines at multiples of price ,you'd probably need to get a sig gen with variable clocking to get much better performance and they usually cost 1000$'s.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 20, 2018, 12:16:33 am
Is this thread about the FY6800 now too? Maybe it's a good idea to change the title to represent this. :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on August 20, 2018, 12:18:14 am
Unfortunately, the thread was started by someone not actually interested in being a forum member.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 20, 2018, 12:25:47 am
Unfortunately, the thread was started by someone not actually interested in being a forum member.
Nothing a moderator can't fix.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on August 20, 2018, 12:56:16 am
It'd be ideal to re-assign the ownership of the OP to one of the members actively working on the 6600/6800.

A less-elegant alternative would be to start a new thread and cross-link them.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 20, 2018, 02:19:58 am
It was decided a while ago to keep the same thread going as the FY6600 and FY6800 are essentially the same item, and anything discussed about one applies to the other.  A new thread for the FY6800 alone would potentially result in masses of accumulated information being missed by new searchers who aren't aware of the history of the two devices.  Likewise, questions posted in an FY6800 thread would get missed by knowledgeable FY6600 owners who could otherwise provide help and answers.

If this was a car forum, would you have one thread discussing the engine performance of a blue version of a certain car, and another thread discussing the same thing about the red coloured version of the same car?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on August 20, 2018, 03:25:55 am
It was decided a while ago to keep the same thread going as the FY6600 and FY6800 are essentially the same item, and anything discussed about one applies to the other.  A new thread for the FY6800 alone would potentially result in masses of accumulated information being missed by new searchers who aren't aware of the history of the two devices.  Likewise, questions posted in an FY6800 thread would get missed by knowledgeable FY6600 owners who could otherwise provide help and answers.

If this was a car forum, would you have one thread discussing the engine performance of a blue version of a certain car, and another thread discussing the same thing about the red coloured version of the same car?
We can decide all we want, but the thread isn't going to be found by people interested in the FY6800 very quickly if they weren't already familiar with the thread. I've asked a moderator to rename the thread.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 20, 2018, 03:26:28 am
I've been using my FY6800 pretty much as the generic test signal source for my troubleshooting and repair efforts; it's nice to be able to check gear with swept frequency and amplitude as well as single frequency input. 

I use mine almost exclusively for audio.  Running it into my HP331A I see that the distortion in the range under 100KHz is moderate - about 0.25% or so.  Honestly I'm not interested in extending the bandwidth or output level of my generator per se; but has anyone seen or tested a mod which will reduce the distortion at audio frequencies into normal 10K-100KΩ loads?  That's about the only thing which would be handy for the work I do. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: JS on August 20, 2018, 05:12:58 am
I've been using my FY6800 pretty much as the generic test signal source for my troubleshooting and repair efforts; it's nice to be able to check gear with swept frequency and amplitude as well as single frequency input. 

I use mine almost exclusively for audio.  Running it into my HP331A I see that the distortion in the range under 100KHz is moderate - about 0.25% or so.  Honestly I'm not interested in extending the bandwidth or output level of my generator per se; but has anyone seen or tested a mod which will reduce the distortion at audio frequencies into normal 10K-100KΩ loads?  That's about the only thing which would be handy for the work I do.

How low do you want? I guess your only option is filtering, if you are interested in a particular frequency a fixed filter would do. Otherwise, you are likely better to use a sound card or a dedicated sinewave generator but sweeping is hard-ish for an easy DIY project. The best option could be a tracking filter, which you could do. There is an article of a THD analyzer by Robert Cordell from '81 with a residual THD down to 0.0003% for a certain condition where you could find a few useful blocks. I don't attach it here as it weights about 5MB and I don't have a link but google will help you I guess.

JS
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 20, 2018, 06:05:02 am
I don't really want to kludge a filter or other device on the generator that isn't transparent to its basic operation.  If I want low distortion at a single frequency, I guarantee my Heathkit will outperform most anything that isn't a professional series oscillator (somewhere around 0.01% over its operating range).  I was just curious whether someone had investigated a mod which would improve the audio band distortion of the FY6x00 series.  If no one has, that's OK; I just didn't want to overlook an easy mod.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on August 20, 2018, 06:20:28 am
It was decided a while ago to keep the same thread going as the FY6600 and FY6800 are essentially the same item, and anything discussed about one applies to the other.  A new thread for the FY6800 alone would potentially result in masses of accumulated information being missed by new searchers who aren't aware of the history of the two devices.  Likewise, questions posted in an FY6800 thread would get missed by knowledgeable FY6600 owners who could otherwise provide help and answers.

Certainly, a new thread for the 6800 alone wouldn't make sense and that isn't being suggested here.

A common way to handle it is to have an active member create a new thread (correctly labeled for both models, unlike this one), link from this one to the new one (and vice versa so that people know where older info is located), and continue in the new thread (locking this one as archival).

Another option is if one of the primary contributors to this thread messages gnif or Dave to rename the thread so that it's more accurate. It's the most elegant solution.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 20, 2018, 10:16:40 am
Its a good plan to include the Fy6800 in the title somehow ,but now when I search FY6600 this post and this forum come up top everytime . I guess we dont want to loose top billing in browser search for our thread ,so how would we make sure our search priority wasnt affected by a thread namechange ,maybe leaving the main name of the thread unchanged and adding (including FY6800 model) in brackets ,really we need to find out the implications it might have before changing the name .

Im wondering is the limits in terms of distortion in the FY 66/6800 due to the dac/filter and the bits , in which case Im not sure if theres much benefit in distortion terms from changing out the op amps , surely though if you wanted the highest quality signal from the unit ,say for audio testing which often will require smaller signal voltages ,you'd be better off using the sig gen to make a large amplitude signal ,then using a passive attenuator network to attenuate that to a level suitable for your purpose , in otherwords does producing a smaller output voltage in the FY limit the bit rate of the output signal ?. Could a specially made switched attenuator, optimised for 50 ohms, used after the generator  allow an improvement in distortion ? I know that in the case of using a sound card for audio testing a couple of the smarter people in another forum I visit made up a special attenuator allowing attenuation in Db ,the signal generator is then run at 0db Fs digital for minimum digital artifacts. If at higher levels in the 66/6800distortion of the output stage is the limiting factor then power supply and op amp upgrades are worthwhile. For most audio testing the small distortion in the output signal of this unit is of no consequence ,it only comes into play really if its distortion  your trying to measure . I guess a computer and high quality dac /attenuator is a better option for producing signals in the audio range with very low distortion in any case .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 20, 2018, 03:14:58 pm

We can decide all we want, but the thread isn't going to be found by people interested in the FY6800 very quickly if they weren't already familiar with the thread.

Eh???  Just try typnig "FY6800" in the search box and see how many hits to this thread come up!

It's the most elegant solution.

Solution to which problem, exactly?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 20, 2018, 04:36:58 pm

Im wondering is the limits in terms of distortion in the FY 66/6800 due to the dac/filter and the bits , in which case Im not sure if theres much benefit in distortion terms from changing out the op amps , surely though if you wanted the highest quality signal from the unit ,say for audio testing which often will require smaller signal voltages ,you'd be better off using the sig gen to make a large amplitude signal ,then using a passive attenuator network to attenuate that to a level suitable for your purpose , in otherwords does producing a smaller output voltage in the FY limit the bit rate of the output signal ?. Could a specially made switched attenuator, optimised for 50 ohms, used after the generator  allow an improvement in distortion ? I know that in the case of using a sound card for audio testing a couple of the smarter people in another forum I visit made up a special attenuator allowing attenuation in Db ,the signal generator is then run at 0db Fs digital for minimum digital artifacts. If at higher levels in the 66/6800distortion of the output stage is the limiting factor then power supply and op amp upgrades are worthwhile. For most audio testing the small distortion in the output signal of this unit is of no consequence ,it only comes into play really if its distortion  your trying to measure . I guess a computer and high quality dac /attenuator is a better option for producing signals in the audio range with very low distortion in any case .

That's right, the DAC is used to generate the output and it's just buffered by the op amps;  using it to generate a lower level signal will effectively use fewer bits.  Running the output at max level and putting a post attenuator on the FY6800 ought to lower the distortion quite a bit due to (1) reduced quantization errors and (2) linear scaling of the signal.  I should have thought of that, and I will try it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on August 20, 2018, 04:38:56 pm
I just did a search in the forum for "FY6800" and none of the top six results are this thread, five of which have "FY6800" in the thread title.

Anyway, that's all. Carry on.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 20, 2018, 06:02:33 pm
OK, that worked well.  I maxed out the FY6800 at 20V, ran it into the 331A through the attenuator, and measured a THD+N of approximately .03% - close to the theoretical limit for a 12-bit system.  That's more than sufficient for anything I'm doing, and not far from my IG5218.  Color me suitably impressed.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 20, 2018, 06:08:15 pm
I like the filter approach suggested by JS ,you needen't butcher the internals of the 66/6800 ,it  could easlity be made into a passive box and placed on the output of the sig gen with a known amount of attenuation of signal .into a given load impedence ,maybe with switchable centre frequencies , Bruel & Kjaer make some very nice passive attenuators/filters for audio measurement work ,I wonder if one of these would be a good off the shelf add on to a sig gen setup , the units themselves seem to be for interface with certain other B&K gear ,but adding some BNC's would surely be an option .


https://www.ebay.de/itm/Bruel-Kjaer-1616-1-3-Octave-Filter-Set/123213621878 (https://www.ebay.de/itm/Bruel-Kjaer-1616-1-3-Octave-Filter-Set/123213621878)

https://www.ebay.de/itm/Bruel-Kjaer-Logarithmic-Potentiometer-ZR-0003-92C-3/140942018492 (https://www.ebay.de/itm/Bruel-Kjaer-Logarithmic-Potentiometer-ZR-0003-92C-3/140942018492)

Im not sure about the impedences these B&K units are designed for .



Maybe an even simpler solution would be a series of inline filters with set frequencies,  a bnc female to male adapter could be used to house the components ,no switches no pots ,a handfull of preset values might have you covered .We know that at certain whole mulptiples or divisors of the clock frequency the performance of this generator is better ,so why not create a set of filters that corresponds to these sweet spots on the 66/6800, ensuring best possible performance from each range .


Is there software that would help calculate component values for audio filters with defined requirements in terms of impedence and insertion loss in db etc? Ive seen a few of these type programs but never got the hang of them ,or they were not dedicated to audio specifically. Im also not MSoffice aware so I didnt try spread sheets

From what I can gather the 3491 is capable of swinging a handfull more volts at the output for a given rail-rail supply than 3091/95 , all the better if we need to drive passive filters with attendant losses . With the stock switcher psu and the stock output ic ,I see around 600millivolts drop across the rails at full output into 50 ohms both channels driven , thats pretty bad regulation by anyones standards ,simply bolting on the extra horsepower of the 3491 will cause an even larger modulation of the powersupply rails . Peak current of two 3491's is likely to be in the region of 1A and to get best performance your going to want good voltage regulation right through the current range .

I know someone who designed an attenuator specifically for sound measurement ,designed to be placed on the output of the soundcard ,therefore completely avoiding digital attenuation of any kind ,digital out is always hitting 0db fs ,you then have a coarse and fine resistor attenuation network say 5 coarse steps of 10db and fine scale of +/-5db ,using selected or hi-stability resistors very close tollerance attenuation can achieved over a wide range. I'll look up the post and make a link to it
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 20, 2018, 06:21:31 pm
That would be interesting, thanks!  There are some online filter calculators which work nicely; I've used a couple of them to design both active and passive crossovers for my stereo.

For what I'm doing, .03% is perfectly fine - I'm just using it as a quick performance check on amplifiers when I'm setting bias; and none of the amps requires an input voltage of more than 1.5V for full output, so attenuator losses could be pretty severe and not hurt the measurements.  But ultimately I'll need a separate box because all I did here was run directly into the HP331A and it has a full range attenuator on its input already.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 20, 2018, 07:21:11 pm
Thanks for testing the theory Greg ,my suspicions were correct ,
.03%, thats impressive , As you suggest thats an equivalent figure for a 12 bit system.  Maybe distortion in the 3002 op amp is the limit your seeing at 20 volts swing ,are you running standard parts,voltages in your unit ?If it is, my guess is the 3491's distortion should be an order of magnitude lower than what were seeing now and maybe the full 14 bit resolution is just achievable .

With the use of the afore mentioned attenuator ,mods and maybe JS's filtering idea its seems likely the 66/6800 could generate very high quality audio waveforms ,good enough for distortion measurements in other equipments . Its kind of interesting in that we spent a good deal of time thinking about ways of improving the signal quality  in the digital domain ,in fact the answer was make best use of the bits we have  .I wonder with a filter to supress the harmonics could we exceed the theoretical limits of the 14 bit convertors .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on August 20, 2018, 07:51:09 pm
Yes, though that's at full output, 10 KHz only, it's a completely standard unit as far as I'm aware.  Latest firmware. 

Keep in mind that I don't have a super-quiet bench and that 331A is only spec'ed to a residual THD+N of 70 dB at audio frequencies, so I'm likely just measuring the meter's residuals here.  That's why super-low distortion is not a big concern to me at this time.  Now maybe when I find that minty Sound Technology 1700B at a hamfest...  :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on August 21, 2018, 06:08:45 pm
Where did you buy in BG with free shipping, my suplyer of choice (TME) doesn't seem to stock it?

Direct order to TI - store.ti.com
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: danco on August 21, 2018, 06:13:45 pm
Thank you, I'll try it myself.
Where did you buy in BG with free shipping, my suplyer of choice (TME) doesn't seem to stock it?

Direct order to TI - store.ti.com

Sent from my MI 5s Plus using Tapatalk

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 21, 2018, 08:09:30 pm
I see in the THS3491 specific resistor combinations are recomended for  gain setting. What is the gain in the original fy6600's final op amp output? ,surely if we want the display to show a meaningfull output voltage  the right resistor combination needs to be used to set the gain the same as the original op amp set up ,simply leaving the originals in place will no doubt  means the gain wont be a whole number  .It seems setting the gain higher impacts on the distortion produced by the output stage in any case .Maybe someone can test the output stage gain on a machine with 3491's installed , I have a vague recollection the original setting on the unit is x3 gain for the 3002 op amp .

The spec sheet for the 3491 shows Rg and Rf to be 200 and 798 ohms for a gain of 5 ,2.1k and 2.1k gives a gain of 2 .
On the FY66/68 we have 499 and 1.5k in these positions . Tables are available for each op amp giving the optimum resistor values and gain .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 21, 2018, 10:09:37 pm
THS3491:

Gain           rg            rf   
   2             2.1k      2.1k
   5             200       798 ohms
  10            78.7      704 ohms

THS3095:
Gain           rg            rf
   1              -             1.78k
   2            1.21k        1.21k
   5             249          1k     

THS3002
Gain          rg             rf
   1                            1k
   2                           680ohm
   5                           560ohm

So with 1.5k rf on the unit, a gain of less than 1 would be expected  ,3095 users would have a gain somwhere around 1.5 and 3491 would have a gain of around 3 .

So I setup the generators for 5.1volts 1khz sine,this should be 1.803  vrms

Fy6800(standard 3002 output stage)
Ch-1  1.7966 vrms
Ch-2  1.7815 vrms
Fy6600 (3095 x2,same Rf Rg)
Ch-1  1.7750 vrms
Ch-2  1.7735 vrms
at 0.51 volts (opa-686)
Ch-1  178.53mVrms
Ch-2  179.45mVrms

So not a big descrepency between the two opamps . I set the 6600 to .51volts output and used trimmers W3 and W5 to bring my output levels on both channels  to .1803 volts.
Now when I engage the 3095 at 5.1volts I measure 1.7935  on channel one and 1.7822 volts on the other channel so 10mV low on channel one and 21mV low on ch2 ,maybe its normal for the opamps to differ to that degree. I might check tomorrow  if the tollerances of the impedence/feedback setting components on the output play a part in the difference between channels .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 22, 2018, 06:00:02 pm
SO a couple of ohms difference between the main 50 ohm output series resistor after the 3095 ,into 1Mohm meter input I cant see this making much or any difference, the output attenuation network is matched very precisely between channels  , so maybe theres either a difference between op amps or a slight variation on the feedback resistances between stages . Maybe a small gain control preset pot on the final opamp  output stage feedback network in order to match the gains exactly might be a good plan for the next revision of the machine from  Feeltech ,it would also facillitate setting up alternative op amps.It would certainly allow for much more precise calibration of the output amplitude at higher levels . As we stand all the amplitude decimal places below .00 are worthless ,an ability to calibrate the outputs would make lots of sense for the precision of the machine .The way things are you can calibrate either low or high range output precisely ,but once you change to the other range  its no longer calibrated

Thanks for the link to Robert Cordell JS ,bound to be some good stuff in there ,just downloaded and getting stuck in ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on August 23, 2018, 12:26:05 pm
Soundtech, If I may help :

 The gain of the output stage is 4
It is  G = 1+ rf/rg so G = 1 + R63/R45 on the original board gives 1 + 3

The difference you measure comes from resistors. But no need to adjust it alone as all the chain gain can adjusted by W05(CH1) and W03 (CH2).

I have replaced trimmers with Bourns SMD 1K 11turns 3224W-&-102E found on eBay
W26 : DC_AMPL_CH1_OFFSET
W05 : DC_AMPL_CH1_GAIN
W16 : DC_AMPL_CH2_OFFSET
W03 : DC_AMPL_CH2_GAIN
W01 : DC_OFFSET_CH2_CAL
W02 : DC_OFFSET_CH2_CAL

Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 23, 2018, 04:07:09 pm
Hi Dpa31,

If you look at the schematic the gain control pot is in the feedback loop of the OPA686 ,when I calibrate the output below 5 volts with W3 and W5 I can get it very close ,but as theres no fine tune of the final output IC's your either calibrated to high or low level signals ,but it cant be right at the same time on both .

The idea of using ten turn pots came to mind with me a good while ago ,Im glad someone did it ,I'd imagine its a lot less fiddly now to set things up accurately .Was there any trouble fitting the ten turn pots? ,I didnt know there were smd types of ten turn pot available . Are they pin compatible with the existing presets?



 

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 23, 2018, 04:10:52 pm
Soundtec - are you getting the values of R45 and R54 from the schematic, which shows them as 499 ohms?  On my two boards, and in the high res photos posted in May, the values are 68 ohms, which would give a gain of 23, not 4.  Either the schematic values are wrong, or there was a redesign carried out by Feeltech in late 2017.  I was thinking I might change R74 and R83 to 1k to give a more conservative gain of around 16 if I put 3491s in (or do one channel to see if there's any real difference).

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 23, 2018, 05:54:30 pm
I didnt measure them on my board ,but just relied on the schematic ,

with either standard output stage or upgraded op amps Im getting more or less the same from both units within 10 to 20 mV, . A buddy just explained to me the gain is very little to do with the opamps themselves and more to do with the proportions of the feedback and other resistor than goes to ground . Id still like to see a pot on the feedback path to the final op amp ,just for fine tuning .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on August 24, 2018, 09:29:30 am
Hi Sountech, Hi Dave,
 
I verified R45 & R54 resistors on the SB: they are coded 68A that is 499 ohms.
just in case : http://www.resistorguide.com/resistor-smd-code/ (http://www.resistorguide.com/resistor-smd-code/)

@Sountech

 Yes trimmer footprints are compatible with the pads on the PCB. see attached picture.

Can you describe the measure you would like me to do : 5V sine both channels, frequency ? You measure mV on both channels with ?

Cheers.
Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 24, 2018, 11:17:36 am
They fit in nice Dom , I'll have to do that mod myself for extra tweekage.

What you could try is dial in 5.1 p-p (sine)on the unit ,now with your RMS multimeter measure the output voltage , it should  read approx 1.803 v rms.
Now if you repeat the same test but with an output voltage of .51 volts ,this will mean only the opa686 is engaged ,now measure again your rms volts at the output ,you should be seeing .1803 volts rms . On the lower output range you could tweek the adjust pots on the opa686  to get exactly .1803 volts ac ,but this inevitably means your high range (over 5 volts output) will be off by a margin . Having adjust pots on the final high level output stage would allow an extra measure of accuracy to be tweeked in . So it looks like our feedback network on the high level output stage uses 1% tollerance components ,maybe upping these to .1% would be a worthwhile exercise .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 24, 2018, 12:05:15 pm
Thanks for that info and link, Dom - I thought it was 68R I was seeing, so just assumed it was 68 ohms.  You live and learn!!  :)

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on August 24, 2018, 04:26:28 pm
I got it  |O, Thks Soundtec.

I forgot the switch relay effect on range over 5V

@ 50Hz I measure 0.181 Vrms for 0.5 Vpp  but 0.177 Vrms for 0.51Vpp
                           1.769 Vrms  for    5 Vpp but 1.766 Vrms for  5.1 Vpp

I envisage to put a  piggyback SMD resistor in parallel either on R63 & R74 (1.5 K) or R45/R54 to adjust THS3091 outpout stage gain. But it will not correct the DAC non-linearity. So the question is at what frequency and what amplitude to adjust the final stage ?

BTW I 've got an adjustment range of 24 mV for half a turn on the gain trimpot on a 5V amplitude signal. I was able to adjust equally the gain of both channel.

Another point : what is the purpose of DC_OFFSET_Channel_CAL pot ? Does anyone know or test it ?

Cheers.

Dom.



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 24, 2018, 08:02:19 pm
Hi Dom,

As far as I could tell when I adjusted mine a few weeks ago, the DC_OFFSET_Channel_CAL pot adjusts the vertical symmetry of the sine or square waves.  I used it in conjunction with the GAIN pot to get the waveforms on both channels identical by overlaying them on the scope.  Only the top half of the waveform was affected by adjusting it, and its range was quite small, but it served its purpose (if that's what it's meant for).  The name on the schematic is rather cryptic, but it's safe to give the pot a wiggle and watch what happens.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 24, 2018, 08:49:58 pm
Ok thats all good information to get in ,
Word from the mouth of someone with 60 years experience in electronics is you use finer tollerance resistors to make up the potential divider across the output IC . Each IC has a range of specific resistor values ,not simply any resistors of a certain ratio,that ensure best performance ,generally between gains of about 2 and 5 best performance is had . 

When the drive to the 3095 is engaged the signal is fed from the opa686 outputs , my guess is theres an offset built into the software calibration which tries to make up for the slight gain differences as you switch between high and low range ,if we have calibration 'flat' and can adjust amplitudes independantly between opa and ths op amps externally we could essentially do away with using some calibration features in the digital domain ,maybe this is the issue as when you switched to 5.1 volts the output level actually went down DPA31.

So were essentially getting 12 bit performance , good op amp technique should be able to squeeze those last two bits out easy ,better sorting the amplitude differences between ranges in the analog domain as much as possible and not relying on bit munching internal calibration .

Theres a few nice theories for you to mull over in any case ,

Your idea to piggy back two resistors has merrit too Dom , if you picked x2 the required values ,then selected from a bunch of 0.1% tollerance in both rg and rf , you could get the resolution of the display to read bang-on to better than what we see now , if the range was a few mV off you could simply select from your bag of components a marginally lower value for each channel individually until its right 'on the money' ,in the words of Zappa .

Kindest regards Gents ,
Its Friday and the beer is flowing ,I hope your taking a dose of your fav poison and kicking back like me ........



as is as we saw its maybe a few tens of mV off across the ranges at a volt or two amplitude .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on August 25, 2018, 08:08:32 am
Hi,

BTW, another mean for adjusting the gain had been described before in the blog:

"With regard to the circuit FY6600_Main_A0.pdf  at the THS3002 amp, the gain figure is 3.986 with a 10K input termination resistor and 4.006 without this resistor; changing this resistor to 33K results in a 3.999951 gain factor which is very close to a perfect 4."

These 10K are R44 & R53.
They act as a voltage divider on the THS 3095 input. The effect is very light.

Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 25, 2018, 12:39:57 pm
Yeah I can see the effect your talking about alright Dom . Thing is,  raising the input impedence of the 3002 wiring and all its associated components to 33k will most likely effect the high frequency performance to some degree ,higher load probably does reduce harmonic distortion from the opa686 to some degree but the effect of any stray capacitance in the wiring etc could be magnified .

My guess is pots over time and temperature are subject drift , probably a lot more than a 0.1% resistor , if we use the doubling up or paralelling idea for the resistors we might be able to select much much better than 0.1% tollerance .The two 100 ohm resistors in parralel at the output of the 3002 are pretty low spec ,into high impedence like a meter a few ohms difference here wont make any odds ,but say if your driving 50 ohms ,or the relay clicks in the output attenuator ,any minor discrepency in the 50 OHm value will cause an error in the values displayed .

the use of 499ohms and 1.5k seems like a reasonable compromise value that works with most op amps  ,but I wonder to get the very best performance  in 3095 or 3491 op amps do we need other values with a 3:1 ratio .

What tollerance are you guys seeing on the 499, 1.5k ,10kand 50(2x100ohm)  parts ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 25, 2018, 08:20:58 pm
Page 35 of the THS 3491 data sheet explains things clearly in relation to rF and rG, layout and incidental capacitance etc .
An adjustment pot could cause extra pF's to be added to the feedback network and hamper high frequency stability .
Maybe a bag of 50 each value 1.5k and 499ohm 1% parts could be selected down into matched pairs with very close to 1:3
ratio or I do see some 0.1% in batches of ten that might be worth a try . Im unsure of the wattage rating and size of the resistors needed also.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on August 25, 2018, 09:13:09 pm

What tollerance are you guys seeing on the 499, 1.5k ,10kand 50(2x100ohm)  parts ?

Hi Soundtec,

Here are the resistor values measured in situ on channels 2 & 1:

498 & 497
1492 & 1485
10.15 K & 9.99 k
50.4 both

Dom.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 26, 2018, 12:58:14 pm
Those figures are interesting Dom ,thanks .
I think it shows why the output from the final stage is off by a margin , slightly low compared to where it should be .
To be honest Im not very wall practised in SMD rework , I look at the size of those resistors and the density of components I the area ,and get a bit scared by thinking about how easy it would be to mess up the board . Still I very much would like more accuracy from the amplitude display ,so Im strongly cosiddering upgrading all the resistors to 0.1% or better if I can through selection of components .

In the mean time ,I put together an enclosure for my post attenuator , it has a toggle switch with  three positions , -10db, -20db, -30db , I also have  a rotary two pole switch with 12 positions I'll set up as 10 single steps of 1db , a unity gain position ,and an off position that shorts the DUT input to ground through a 150 ohm resistor for noise testing . As far as precision is concerned ,if I can make the 10 db ranges accurate ,I dont really mind some 'slop in the gears' on the 1db range switch .

As you will see from the photos Im all done with the casework and constructional side ,she's looking good  ,I have an idea the form the attenuators will take in my head but Im still not sure which is the most appropriate style of attenuation ,ladder or H network etc .
I also found a very neat stepped attenuator calculator ,you fill the blanks in terms of charachertistic impedences and attenuation  you want and the software calculates the values , I think you can model several different kinds of attenuator topologies with it too . I'm unsure about the exact form both attenuation circuits need to be to function properly in series , and any advice people can offer would be welcome .

Its all a bit chicken and egg  as far as choosing impedences , I need it for audio signals primarily ,but Id also like the attenuator to be usable at least up to a couple of hundred khz sine, I'll need to be able to feed single ended line level audio inputs of 10 or 20 kohms as well as high impedences  directly from the output ,in the case of balanced connection  being required a mumetal transformer can be used across the outputs ,I have a 1:1 10k-10k sowter transformer thats good up to about +10dbu and 50khz of bandwidth feeding 20 kohms input impedence. For mic level inputs which are around 3kohms normally, maybe a mic input transformer used in reverse(10k-600ohm) might work well.


I need more specific advice before I start building the attenuators really  ,so I dont end up having to re-do it again ,you know the old saying 'measure twice cut once' , but my head is a little fuzzy on the maths   :palm:

Pictures to follow soon , coffee time . I'l post too another forum about the specifics of the impedences and see if anyone likes the idea enough to fill in the blanks for me .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on August 26, 2018, 02:33:53 pm
Hi Soundtec,

You have an interesting project. Could you please put the link for your attenuator calculator.

You mentioned attenation of -10dB, -20db, -30db : are they dBV (20lov V2/V1) or dBW (10log V2/V1).
I understand you keep 50 ohms as output impedance, am I right ?

To continue on THS3095 gain adjustment :
I set 5.0V sine 50Hz and I measure 1.768Vrms that is 5V pp
Then I set 5.1V and I got 1.7655 V but at OPA 686N output I got only 0.446V rms which multiply by gain 4 gives only 1.784Vrms instead of 1.803V rms. Before to

Dom.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 26, 2018, 03:26:13 pm
 A little passive test Jig set for audio signals comprising the attenuator ,a transformer , switchable low pass filter  (to improve matters when making THD measurments) and some patch cables makes a nice addition to the FY6800  .

Maybe a simple LC low pass could be integrated into the 10,20,30db attenuator network ,then either switched to one of an handfull of known frequencies or out of circuit as required ,might afford a reduction in the harmonics of 40-50 db or more from the raw sig gen output. If we're at .03%THD at full output from the gen  ,if we could mange 60 db of attenuation say at 2 khz ,driving a 1khz signal ,wouldn't that give us .00003%THD (with some attendant insertion loss in amplitude terms of course).

Im not sure  100% sure about setting the characteristic impedence of the attenuator ,50 ohms ,its always handy to have low -Z output capabillity ,but this will come at some penalty in load on the output IC's and distortion produced  , it will also cause -3db output due to the series output resistor ,on the plus side with a 50 ohm characteristic bandwidth will probably be in the many hundreds of khz. Maybe 600 ohm might be a good compromise for general audio work , I do see an implementation of the 3491 with 2,3 and 4 op amps per channel in the spec ,at high frequencies the thd is reduced by more than 30-40 db over the case of a single chip , thats at 50 ohms ,if your opperating into higher impedences at audio frequencies THD dissappears off the scale to -100db or more down from fundamental .

dbu or dbv might be the correct expression,  I think dbu relating to a given impedance and reference level,dbv relating purely to voltage  ,Im a bit sketchy about that ,so double check for yourself in anycase .

I think the effect your seeing on the output levels is the purely down to 1% components on the network surounding the output ic  Dom ,broadly the results of the voltage checks agree with the ohms your measuring on the individual components . Im just looking for a bit of software I found last night which allowed allowed statistical evaluation of rF and rG and its outcome on the accuracy of op amp gain setting. It looked really usefull for us ,I'll find it again dont worry ,and the attenuator step calc  |O

Good to see a few old regulars turning up for a look at the topic again ,no need for names , :phew: ,saluts .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 26, 2018, 06:54:39 pm
Im just trying to visualise the circuit ,
Its essentially three -10db sections ,with the 1db range always in circuit , seeing as the rotary switch is 2x12pos I was thinking h pad type network on the 1db range ,then the three way toggle switch offers gain ranges of, unity to -10 db , -10 to -20db and -20 to -30db in one db steps.
Maybe frequency switchable  low pass LC sections could be cut in and out across the three attenuation  ranges ,that way the more attenuation you can live with, the better the out of band rejection of the harmonics .

Little passives gadgets that 'do exactly what they say on the tin', are uncomplicated and instantly feel intuitive to use , Im a huge fan of .
I could think about making a small smd board kit including toggle switch coarse range ,1db fine range control ,frequency cutoff control ,enclosure ,bnc's and maybe selected or even paralelled 0.1% resistors throughout  . Might not be too difficult to to end up with a very close tollerance network that fits on a postage stamp ,good layout with low incidental capacitance would ensure flat frequency responce to very high frequencies .It would  be possible  to use Lorlin rotary 1x12way for fine and 2x6 for frequency cutoff controls ,
hardwired 0.1% throughhole resistors  could be used without having much effect at multiples of any audio frequency of interest .An analog attenuator post output definately beats any form of digital control of output level ,if levels less than -30 db are  required you could always add an inline attenuator with a given loss ahead of the unit, and you'd still have your precise 1db steps .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DPA31 on August 26, 2018, 07:14:33 pm
Hi Soundtec,

I see your project is progressing. Nice cabinets.

On my side I have finalised THS3091 with 18k and 27 K in piggy back mods on R54 and R45. see attached picture.

I am now looking at the output attenuator for 0-0.5 V range.

Looking forward to seeing your progress Soundtec.

Dom.

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 26, 2018, 10:13:35 pm
Added a  scale ,poor quality print as you can see,and there are some mistakes ,but for now it will do .



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 28, 2018, 01:03:19 pm
Just looking at the schematic , I see the gain and dc adjust pot are symetrical on the OPA686 ,this means the extra capacitance should balance out and have little effect on the signal .

Simply putting a pot in place of our 1.5k feedback resistor on the 3095 or 3491 would cause extra capicitance that might upset our output stage . What if we   replace the 499ohms with 470 +  a 50 ohm preset to ground, now any extra capacitance caused by the pot is 'hidden'   by the ratio of resitance  of  30:470 ohms  and it allow us precisely trim the output stage gain so whats coming out of the generator on both ranges corresponds exactly to the numbers on  the display.

Heres a nice attenuator calc that allow you specify impedence and it works out the values in the chain, you can rejig the impedence to get it to coincide better preferred resistance values.Shunt calc by the same author. 

http://rssconsultancy.co.uk/atten.html (http://rssconsultancy.co.uk/atten.html)

I found an good op amp gain calculator here ,  its quite comprehensive compared to most ,

https://www.allaboutcircuits.com/tools/op-amp-voltage-and-gain-calculator/ (https://www.allaboutcircuits.com/tools/op-amp-voltage-and-gain-calculator/)

You can easily add in the measured values from your Fy6800 and calculate the discrepency to expect . This software computes in the effects  of series and input to ground resistor too ,in our case 50 ohms and 10k , even 1% tollerance components in this position  will have  a very little effect on the circuit calibration, as pointed out earlier . A perfect 499:1500 ohms resistor set will have a margin of error ,but as little as a few ohms either way in the resistors can get you an exact gain of four . maybe if you had a batch of 1.5k and 499 ohm resistors to choose from you could find  closely matched pairs ,so that if you have a high 499 ohm you could match it with a slightly high 1.5k to maintain our 4:1  gain ratio.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on August 28, 2018, 08:40:12 pm
I found some very high spec resistors at 1.5k ohms , .02% Beyschlag mini melf,
The op amp calculator shows with exactly 1.5k in rF position with 50ohm series resistor and 10k input loading a 497 ohm is needed in rG for a  perfect x4 gain .
Maybe a batch of 499 1% could be selected from to find 497 ohms +or- a margin that works with our fine tollerance component  to produce a very tight calibration on the output of the FY66/6800 . Set and forget with very low drift components (15-50ppm)beats even a preset ten turn adjustment ,Its probably less that 10 euros worth of parts and a little work to make the FY into something approaching a voltage reference , so Im gonna give it a try,  as someone way back at the start of this forum page  asked,
'Whats the point in a screen displaying  10.0000 volts if the last few digits are are garbage?'

I found an op amp noise calculator last night ,it allowed tuning in of the circuit values and noise parameters of the op amp ,I tried a THS 3491 in the circuit of the FY66/68 , I got a whopping noise figure of around  -128 db with x 4 gain ,thats within a few db of the theroretical limits imposed by the laws of physics itself , it also means any noise contribution from the op amp is very much below whats produced by the dacs ,always a good thing .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: kirys on September 05, 2018, 08:18:27 am
is the ghost voltage gone on the 6800?
I read from this review (see the comments) https://tech.scargill.net/fy6800-signal-generator/ that the 6800 still has the ghost voltage, can someone confirm this?
Thank You
K.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 05, 2018, 02:00:38 pm
I did read Ted's blog and wondered if the mains ground was good in his holiday home where he did the initial test .
The y cap and 1meg resistor were removed from the powersupply of the 6800 and probably newer 6600's too ,and with it all grounding through the plug I see no safety issue. I own both 66 and 68 hundred's
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 06, 2018, 11:28:43 pm
This guy does a good review and tear down of the 6800 ,he also does a tutorial of each of the functions of the Fy6800  and measures the leakage voltage too .

https://www.youtube.com/watch?v=5_iJEOffikA (https://www.youtube.com/watch?v=5_iJEOffikA)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: chrisjn52 on September 18, 2018, 12:16:58 pm
I am interested in purchasing an FY6600 or FY6800 Function Generator with a view to PC control via the NI-VISA drivers and the SCPI command language using Python & PyVisa.

As one might expect for such a low cost instrument, it does not conform to the SCPI or IEEE 488.2 specifications but I would appreciate
it if someone with more experience than I could confirm whether there would be any major issues?



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on September 18, 2018, 05:42:25 pm
I may have mentioned it in an earlier post, but my 6800 has a nice IEC inlet, a fuse holder, and I measured no leakage on the outputs.  I've used it on numerous occasions and never experienced any issues with other test gear or equipment under test.  I do wish it was a little heavier so it doesn't slide when you press the buttons.   ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Supernick on September 18, 2018, 10:42:56 pm
Hi all, please help

i buyed fy6800 on ali, but on the all frequencies (excl 5.000Mhz) i have a static jitter.

1) checked oscillator - all ok. good sine, freq 50.0007 on oscilloscope. Amplitude is good.
2) checked direct lines from ALTERA - jitter is present.. and on the control point (T1.. T2..) signal with static jitter

from ch1 and ch2 signal is splited


what is it? how to fix? what the check?

ps. i tryed rewrite my flash (winbond). Dumps from this thread. Device or does not work or non stable and without signal on chanels


MODEL: FY6800-60
BOARD: 1.51
FW: 1.7
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on September 20, 2018, 03:22:22 am
That jitter is both normal and expected. In fact you will find that for non-sinusoidal waveforms, all frequencies above 5MHz that aren't an integer multiple of the sample frequency of 250MHz will have a 4 ns jitter (4ns=1/250MHz).

At the moment there is no known way around this issue, and it appears to simply be a feature of the generator.

Maybe in the future it will be possible to correct it with software, but for the moment it's just something you have to deal with. Also, according to the spec sheet for other similar generators like the more expensive and less capable models from siglent, rigol, and gw instek, their jitter is as bad or worse for non-sinusoidal waveforms
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Supernick on September 20, 2018, 05:47:43 pm
thank you for your reply!

but in fy6600-30Mhz all supergood. any signal forms without jitter on any freq
and other FY6800 owners (I asked) confirmed that they have a signal without a jitter

why?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Supernick on September 20, 2018, 05:49:41 pm
also.. jitter is present on all range. from 10KHz.. Mhz
only 5MHz without jitter  |O
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on September 20, 2018, 06:00:51 pm
Try the following square wave frequencies: 60 MHz, 50MHz, 30MHz, 25MHz, 15MHz, 12.5 MHz, etc. Then try them with sine waves, and see where the jitter appears
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Supernick on September 20, 2018, 08:13:14 pm

Sine is cool - on the full range.
square is bad from start range..

please look

PS. jitter is 4ns, it's true. But why in fy6600-30M jitter is not present?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rf-loop on September 20, 2018, 09:15:15 pm
Also, according to the spec sheet for other similar generators like the more expensive and less capable models from siglent, rigol, and gw instek, their jitter is as bad or worse for non-sinusoidal waveforms

As far as I know square wave and rectangle wave is not sinusoidal.
What Siglent model have this kind of jitter with Square/Rectangle (other than 50% square)

But then yes, if look Triangle/saw, pulse, arb, there is jitter related to clock. (and example cheaper Siglent models may have example 150MSa/s clock what mean 6.7ns cycle to cycle jitter exept some "golden" frequencies.

But as seen here some previous example images about FY6600 using square have lot of jitter, cheap Siglent model 1000X do not have this type of jitter ancluding also rectangle waves = square duty other than 50%  (not even with 0.001% duty what can also call as "pulse" but in this mode rise and fall time or pulse width can not adjust using 0.1ns adjust steps) My opinion is that Square and Sine need do so that they do not have 1 clock jitter.  Other waveforms can perhaps accept more in cheap simple equipments.

Siglent do not have this "1 clock" square jitter in real life and also -- not in specs sheet (exept pulse mode, triangle and arb)
Is it better to stay with facts and not trumpths.


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: SMB784 on September 20, 2018, 11:50:46 pm
Also, according to the spec sheet for other similar generators like the more expensive and less capable models from siglent, rigol, and gw instek, their jitter is as bad or worse for non-sinusoidal waveforms

As far as I know square wave and rectangle wave is not sinusoidal.
What Siglent model have this kind of jitter with Square/Rectangle (other than 50% square)

But then yes, if look Triangle/saw, pulse, arb, there is jitter related to clock. (and example cheaper Siglent models may have example 150MSa/s clock what mean 6.7ns cycle to cycle jitter exept some "golden" frequencies.

But as seen here some previous example images about FY6600 using square have lot of jitter, cheap Siglent model 1000X do not have this type of jitter ancluding also rectangle waves = square duty other than 50%  (not even with 0.001% duty what can also call as "pulse" but in this mode rise and fall time or pulse width can not adjust using 0.1ns adjust steps) My opinion is that Square and Sine need do so that they do not have 1 clock jitter.  Other waveforms can perhaps accept more in cheap simple equipments.

Siglent do not have this "1 clock" square jitter in real life and also -- not in specs sheet (exept pulse mode, triangle and arb)
Is it better to stay with facts and not trumpths.

I never specified which models I was referring to.  In fact for the SDG830 (https://www.siglent.eu/siglent-sdg830-functiongenerator.html) (>$300) there is 1 clock cycle (8ns) for arbitrary wave forms, which are non sinusoidal. Nothing that I said was untrue.

The main point of what I was saying is that the 4ns jitter in the FY6600&6800 is to be expected, and is actually less than that of competing generators in some modes.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rf-loop on September 21, 2018, 05:09:16 am
Also, according to the spec sheet for other similar generators like the more expensive and less capable models from siglent, rigol, and gw instek, their jitter is as bad or worse for non-sinusoidal waveforms

As far as I know square wave and rectangle wave is not sinusoidal.
What Siglent model have this kind of jitter with Square/Rectangle (other than 50% square)

But then yes, if look other non sinusoidal as example triangle/saw, pulse, arb, there is jitter related to clock. (and example cheaper Siglent models may have example 150MSa/s clock what mean 6.7ns cycle to cycle jitter exept some "golden" frequencies.

But as seen here some previous example images about FY6600 using square have lot of jitter, cheap Siglent model 1000X do not have this type of jitter ancluding also rectangle waves = square duty other than 50%  (not even with 0.001% duty what can also call as "pulse" but in this mode rise and fall time or pulse width can not adjust using 0.1ns adjust steps) My opinion is that Square and Sine need do so that they do not have 1 clock jitter.  Other waveforms can perhaps accept more in cheap simple equipments.

Siglent do not have this "1 clock" square jitter in real life and also -- not in specs sheet (exept , triangle and arb)
Is it better to stay with facts and not trumpths.

I never specified which models I was referring to.  In fact for the SDG830 (https://www.siglent.eu/siglent-sdg830-functiongenerator.html) (>$300) there is 1 clock cycle (8ns) for arbitrary wave forms, which are non sinusoidal. Nothing that I said was untrue.

The main point of what I was saying is that the 4ns jitter in the FY6600&6800 is to be expected, and is actually less than that of competing generators in some modes.

As I told Square and rectangle  are not sinusoidal and Siglent (not even SDG800 serie or SDG1000X serie) do NOT have this jitter as FY have. And not even in Pulse mode. You told that not sinusoidal have. So it was wrong.  It is surprice that FY have this one clock jitter in Square or rectangle in square mode. And btw, also SDG800 series do not have it in square/rectangle mode. Square is one typically most important to be low timing jitter after sinewave. 
Totally different things are other wfms like arb, triangle, pulse in fixed clock system. There also in Siglent is one clock jitter and in 125MSa/s models it is 8ns and in 150MSa/s it is 6.7ns and so on as every school kid can calculate ans also told in datasheets.


Quote from: SMB784
Also, according to the spec sheet for other similar generators like the more expensive and less capable models from siglent, rigol, and gw instek, their jitter is as bad or worse for non-sinusoidal waveforms

Simplified:
If you talk non sinusoidal wfms it include all but not sine. (sentence logic!)
The argument is false, even if you try explain you did not say or mean wrong.

It is true only with FY

If look square, rectangle and pulse mode in Siglent SDG800 and SDG1000X they both outperfom FY just hands down and specially with this jitter. Siglent do not have one clock jitter in Square, rectangle and pulse mode, using what ever user-defined pulse width and or with what ever user-defined pulse rise and fall times or duty% if talk Square function. Including all frequencies.

Square(including rectangle)  and  Pulse
800 series is worst but  even it have specified max 500ps +0.001% (10ppm) period
1000X series max 300ps +0.05ppm period
And typically much less.

This is why they use own developed "EasyPulse" technology what make possible to do these without 1 clock jitter in this kind of simple DDS generator and what FY can not do.

Even oldest SDG1000 serie do not have 1 clock jitter with square/rectangle what is derived by hardware from internal sine.

Arb is different, it is simple way produced from arb memory.
Also triangle have 1 clock jitter.

---------
(and even in this el cheapo FY it is really strange when they still can produce normal almost ok sine and then they can not do it with square without one clock jitter.  Other waveforms than sine and square are bit different things and in simple principle DDS generators it can understand these have one clock jitter (+ small amount other origin random jitter))
NNR
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: thielj on September 23, 2018, 12:40:39 pm
I bought the FY6800-60 and the display stopped working after the 3rd use (backlight lights up, but display simply stays white/blank, while the unit, all buttons, signal generator etc is still working). After some discussions, the seller promised to send me a display board to exchange myself but nothing has arrived yet.

I've now opened the case and checked all the connectors etc. Is there anything obvious that could cause the display to stay blank that I would be able to fix myself?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 24, 2018, 10:11:34 am
Hi TheilJ ,

Didnt hear about that fault before , could be an issue with the Stm32 . You could try controling the signal board directly with a ch340 usb dongle as detailed earlier in this topic , and check your main board is still good . Also in the newest software from Feeltech contains a firmware upgrade option via USb ,maybe that might overwrite some corrupted part of the memory in your machine, definately worth a try .

I was sent a free FY6800 due to my contributions here ,  it arrived via fe-ex ,no import duty was collected at the time of delivery , later I was sent a letter by Fedex demanding the import duty for the machine ,ive refused to pay, they waved their fee ,but they still want the basic of duty payable to customs and revenue on my behalf  , now they threaten with legal action . I contacted Feeltech ,explained the situation ,got a reply, but heard no more from them after  :(

Win loose or draw the debt is in my name , it looks like debt collectors will be sent on Fedex's behalf if I dont stump up the cash ,Only way I could get out of paying is if I surrender the item and it becomes property of Customs and excise or choose to mount a legal defense of the situation. I wonder can I settle the cost directly with Customs and excise  and allow Fed-ex(torsion) to recover their own funds  ;D
I still do think its Feeltech is liable for the import duty ,Ive tried to explain the situation to them in simple language ,but Im not sure they care  :=\
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on September 24, 2018, 01:52:52 pm
About the taxes and customs for gift, and with caveat of not being a lawyer, but with my limited knowledge on how the processes and regulations typically go in EU...

If the carrier has already paid the customs fees & VAT to customs (i.e. government), they can not any more let you handle it by yourself with the customs (in the customs eyes, all is good already, the trouble is now between you and carrier company). If they have already agreed to drop their extra fee for the process (as they should if they didn't ask your permission beforehand), then all you have left to pay is what the government wants (and is also partially regulated by EU directives). Note that the tax/customs is based on the usual value of the product when the declared price is not reasonable (in this case free); again government/EU regulation, not dictated by the carrier company.

It is, AFAIK, quite common for non-EU country companies/organizations to send gifts as "receiver is responsible for any fees, customs, taxes, etc."; the company only wants to send the item, and not send any money or do other paperwork. For example, it is quite common for certain type and level of sport people to refuse their winning items (e.g. cars, not the medals), because even if they are free/gift, the taxes would be higher than what they could afford to pay :P  (Much better for them to receive just simple money; government can take their tax from that winning money.)

Feeltech might indeed not care. Sort of "we sent you an item for no payment to us, pay the taxes and customs if you want it, or let customs have it, choice is now yours".

For only customs and fees cost, that would be one very cheap device (even if not fully free).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 24, 2018, 02:15:15 pm
Thanks for clairifying that for me Bugi ,
I was coming to the realisation the buck stopped with me ,and either way Im stuck with the charge . :horse: ;
I was expecting  for Feeltech to cover any costs associated ,which I think is only fair really ,looks unlikely at this stage though.
Maybe the next package Fed-ex delivers I can produce the invoice and pay them on the spot in cash. :D

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Mr. Scram on September 24, 2018, 05:21:02 pm
Hi TheilJ ,

Didnt hear about that fault before , could be an issue with the Stm32 . You could try controling the signal board directly with a ch340 usb dongle as detailed earlier in this topic , and check your main board is still good . Also in the newest software from Feeltech contains a firmware upgrade option via USb ,maybe that might overwrite some corrupted part of the memory in your machine, definately worth a try .

I was sent a free FY6800 due to my contributions here ,  it arrived via fe-ex ,no import duty was collected at the time of delivery , later I was sent a letter by Fedex demanding the import duty for the machine ,ive refused to pay, they waved their fee ,but they still want the basic of duty payable to customs and revenue on my behalf  , now they threaten with legal action . I contacted Feeltech ,explained the situation ,got a reply, but heard no more from them after  :(

Win loose or draw the debt is in my name , it looks like debt collectors will be sent on Fedex's behalf if I dont stump up the cash ,Only way I could get out of paying is if I surrender the item and it becomes property of Customs and excise or choose to mount a legal defense of the situation. I wonder can I settle the cost directly with Customs and excise  and allow Fed-ex(torsion) to recover their own funds  ;D
I still do think its Feeltech is liable for the import duty ,Ive tried to explain the situation to them in simple language ,but Im not sure they care  :=\
FedEx is correct and you owe them the duties. As a large company they also have a lot of experience with getting unwilling people to part with their money. You won't win and it'll be a major headache. Just pay.

Do I understand correctly that you're complaining about getting a device for free and having to pay some duties? Or was the device a replacement for a faulty one?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: thielj on September 25, 2018, 01:43:26 pm
Didnt hear about that fault before , could be an issue with the Stm32 . You could try controling the signal board directly
The main board and front panel buttons work, it's just that the display stays blank (white). I suppose it maybe a connection issues or faulty display. Is there a schematic for the front panel / display connection somewhere?

I was sent a free FY6800 due to my contributions here ,  it arrived via fe-ex ,no import duty was collected at the time of delivery , later I was sent a letter by Fedex demanding the import duty for the machine ,ive refused to pay, they waved their fee ,but they still want the basic of duty payable to customs and revenue on my behalf

You would need to check the rules for commercial samples applying to your country. You're probably responsible for items you import, so think twice; if paying customs and VAT isn't worth it, you always have the option to return the item; or hand it back to FedEx, as they have paid before letting you inspect it (which is, as far as I know, against the rules).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 25, 2018, 07:37:19 pm
All the schematics are here , along with other information about mods etc .

https://github.com/DerKammi/FY6600-15-30-50-60M

find schematics in 'hardware' section.

Check the soldered ribbon between the front board and the screen ,could be an issue there .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: svetlov on September 27, 2018, 08:41:02 am
Hello Dear Friends! there is a small video  :) model 6800
https://www.youtube.com/watch?v=wg2_h8T7cUA (https://www.youtube.com/watch?v=wg2_h8T7cUA)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 27, 2018, 11:56:52 am
Hi Svetlov,

I watched your video ,unfortunately my Russian language skills arent good ,so I didnt understand much .
I noticed you improved the psu caps , and later in the video you seemed to be adjusting the calibration ,
Did you find anything interesting ,or ways to improve accuracy ?

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: svetlov on October 01, 2018, 09:06:43 am
hi dear :) soundtec :) ! sorry for the delay in response  - this is not my video
 the author of the video says - after replacing the capacitors - significantly reduced voltage ripple but regular chokes severely limit the current to 5 volt power bus-and in his opinion require replacement-would need Chokes are more powerful, rated for a larger current
 -but he himself in the future intends to replace the switching power supply to a linear
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cpposteve on October 05, 2018, 10:55:38 pm
Hi all. Very late to the party here. So late everyone’s probably gone home 🤔. Anyway. I bought one of these nearly a year ago. Used it a few time for say half hour. Put it away and forgot about it until now (10 months on)
I today took it out of the box. Powered it up and to my horror nothing on the screen or front panel all together. I get the couple clicks on power up but nothing on the front end. Checked psu voltages and both 5v are spot on. -12 is -13.1 and 12v is 13.1v. Any help would be very helpful. I was following this thread up until 8 months ago and seems a lot of trawling through. Cheers.

Steve
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: svetlov on October 07, 2018, 10:41:07 am
the continuation of the story Replacing the power supply  :)
https://www.youtube.com/watch?v=sRIVwqfqpu8 (https://www.youtube.com/watch?v=sRIVwqfqpu8)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 07, 2018, 09:14:49 pm
That was interesting , I liked the 'hard wire' regulator approach , fast, simple and rugged .
10/10 for for a really fast upgrade to the Fy6600 , no Pc boards just point to point , a couple of nylon p clips to secure the capacitors to deck would have been the icing on the cake , but epoxy probably does as good  .\subtitles would be great
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: svetlov on October 08, 2018, 09:17:32 pm
after changing the switching power supply to the linear one, the voltage ripple was significantly reduced  up to 3 millivolts approximately
square wave noticeably improved
The author of this video is delighted with the fact that when using linear voltage regulators to power the generator, the waveform noticeably improved
but in this generator at some frequencies the jitter is noticeable
in the next video, he plans and tries to get rid of jitter ::)

for the model 6800 generators released a new firmware 1.7
I have already changed the version of the firmware of my generator :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on October 09, 2018, 02:05:05 am
Thanks for the English-language summary, svetlov. :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: yo0 on October 15, 2018, 01:13:28 am
Hello Dear Friends! there is a small video  :) model 6800
https://www.youtube.com/watch?v=wg2_h8T7cUA (https://www.youtube.com/watch?v=wg2_h8T7cUA)

very interesting, thank you!. by the way wich version of firmware come from factory? it is upgradable? i ask because i plan to buy a fy6800 and appears kkmoon is cheap than feeltech (feelelec), feltech seems to have  firmware 1.6 maybe upgradable to 1.7. thats the reason to know kkmoon version of firmware.

thank you in advance.

best regards

Pio
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArsenioDev on October 15, 2018, 08:30:27 pm
Hmmmm I might try my hand at making a nice open source linear drop in power supply module circuit board.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 16, 2018, 12:47:11 am
Hi Pio,

The KKMoon and Feeltech versions are the same product, except for the badge on the front.  The mainboard is marked 'Feeltech' in both units.  Firmware in both models on sale is probably still at 1.6 at the moment, but the latest models from the factory may already be at 1.7.  Updating from 1.6 to 1.7 is quick and simple - the KKMoon model connects to the Feeltech server and the update process is automatic once you start it via the control software.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: leftcliq on October 19, 2018, 01:50:24 am
Hi,

   Great forum.

   I know this will be a newb question but I am having a hard time changing the frequency units on the Feeltech FY6600.  Can someone please tell me button by button how I change the frequency units?  I asked the Feeltech support but go no response. 

Thanks in advance,
Dale.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on October 19, 2018, 07:40:52 am
You have to push the knob when in frequency mode.

That is you first press F1 in group 3 on your diagram and then press 6. It should change between uHz, mHz, Hz, kHz, MHz.

Cheers
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 20, 2018, 01:20:03 am
Hi Dale - page 8 of the manual, under "ADJ Knob" :)

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: yo0 on October 29, 2018, 02:38:02 am
Hi Pio,

The KKMoon and Feeltech versions are the same product, except for the badge on the front.  The mainboard is marked 'Feeltech' in both units.  Firmware in both models on sale is probably still at 1.6 at the moment, but the latest models from the factory may already be at 1.7.  Updating from 1.6 to 1.7 is quick and simple - the KKMoon model connects to the Feeltech server and the update process is automatic once you start it via the control software.

Regards,
Dave

thank you, what if the unit comes with 1.5 version? do you think it is upgradable?

best regards.

Pio
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 01, 2018, 09:26:04 pm

thank you, what if the unit comes with 1.5 version? do you think it is upgradable?



Have you actually got one with v1.5?  I thought the first versions on sale started at 1.6, but as the FY6800 was designed to be upgradeable, v1.5 (if there are any) should be as well.  Soundtec had one of the very first 6800s from the factory and his has been updated ok, from whichever firmware version it started with.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: yo0 on November 02, 2018, 04:32:41 pm

thank you, what if the unit comes with 1.5 version? do you think it is upgradable?



Have you actually got one with v1.5?  I thought the first versions on sale started at 1.6, but as the FY6800 was designed to be upgradeable, v1.5 (if there are any) should be as well.  Soundtec had one of the very first 6800s from the factory and his has been updated ok, from whichever firmware version it started with.

No, i ask about 1.5 version because ebay advertising shows screens with v1.5. In many fy6800 offerings.

Example:

https://www.ebay.com/itm/FY6800-60MHz-Precision-Digital-DDS-Dual-channel-Function-Signal-Generator-M2K6/302793047829?epid=10008503115&hash=item467fdf3f15:g:nf4AAOSwbb9bPE3l (https://www.ebay.com/itm/FY6800-60MHz-Precision-Digital-DDS-Dual-channel-Function-Signal-Generator-M2K6/302793047829?epid=10008503115&hash=item467fdf3f15:g:nf4AAOSwbb9bPE3l)

Best regards.

Pio
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: josh bowman on November 02, 2018, 05:09:32 pm
2 questions about the FY6600, I'm sure it's somewhere buried in this forum, but I can't find it.

When you select Mod button and choose FM modulation, what is Bias??

Is there any way to change the default voltage to something lower than 5 volts?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 04, 2018, 01:33:58 am
Hi Pio - those screenshots are probably just taken from an early model as the 6800 went into production, and still used as examples for advertising on ebay etc..  I doubt very much whether you'll get anything other than v1.6 or 1.7 if you buy one now.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 04, 2018, 02:28:29 am
Hi josh - BIAS is just the screen shorthand for the modulation frequency of the output, which can be set from 1uHz up to 1MHz.  As for the default output voltage, there is no way to change it from the front panel, but it could be changed by tweaking presets W5 (for Ch1) and W3 (for Ch2) on the main board.  I couldn't say offhand over what range you'd be able to adjust it, though, and you'd obviously have to live with incorrect screen vs actual figures until you recalibrate it.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: yo0 on November 04, 2018, 04:36:31 am
Hi Pio - those screenshots are probably just taken from an early model as the 6800 went into production, and still used as examples for advertising on ebay etc..  I doubt very much whether you'll get anything other than v1.6 or 1.7 if you buy one now.

Regards,
Dave


Thank you Dave!!

Best regards.

Pio
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 18, 2018, 01:59:41 pm
Hi, cybermouse,
Just to be sure, I tried powering the modified board with new op amps from the original switching power supply. Sure enough, the waveform is clipped and heavily distorted in high amplitude settings. So, the voltage from that supply is not enough. +-15V is a must (no wonder, this is to be expected).

 That's a surprise considering the 5v p2p limit above 20MHz. I wouldn't have thought the +/- 11.5 ish volts of an unmodded PSU board would have been a problem at a mere 5v Pk to Pk setting. The voltage swing limits pretty well just about save the generator from gross distortion of the sine wave output even for the THS3002 dual current feedback opamp chip that Feeltech have stuck with 'through thick and thin' despite the need to swap over to the later single CFB opamps they'd made provision for in the unpopulated U21 and U22 locations on the main board once they went beyond the original 15MHz limit in the first version of the FY6600.

 Apologies for the *very* late response (and first posting) but I didn't discover this EEVblog forum until about a fortnight ago as a result of a posting in the sci.electronics. design (sed) news group (Usenet) under the thread titled: "amazing ARB pricing" way back in October 2018 (the 25th) where my initial contribution had been to seek advice on sourcing a cheap oscilloscope.

 This set me off on a quest to buy myself a cheap Chinese 2ch DSO which I resolved by purchasing a nice SDS1202X-E from Siglent's UK agent (Labtronix) just 5 days later which was delivered just two days after that. It was only then that it occurred to me that a signal generator might be worth obtaining as a useful accessory to my DSO purchase, hence my taking note of the link to this forum that had been provided by the OP in the sed "amazing ARB pricing" thread.

 At that point, this forum thread had grown to a massive 69 pages and I read every last page (three days!) before deciding, in spite of the few serious negatives with the earlier firmware, to purchase an FY6600-60M model for the princely sum of £75.66 delivered.

 FYI, the model I received reports firmware version 3.3 which seems to have addressed a lot of the issues mentioned such as the long press of the "OK" button (the rotary control knob) to set the current settings as subsequent defaults on power up failing to provide a feedback 'beep' - it now does so (after about one second's worth of keeping the knob pressed).

 The first mod I applied was to add a 47K resistor to the PSU to boost the 4.95v (loaded) to 5.49v so as to raise the 12v rails from circa 11.5 up to circa 12.5 volts. A few days after that I decided it might be a good idea to replace the 12v rectifier diodes with something better than those 1N5819s (not the best  choice imo) with some proper 30A 45v rated dual shotky rectifiers (TO220 package - it was a bit of a tight squeeze!) recovered from scrapped smpsus which gave me a quite surprising boost to 13.7v on the +12v rail and 14.05v on the slightly less loaded negative rail.

 I didn't bother improving the 5v diode since this will reduce the +/-12v rail voltages. The just below 9 watts consumption 'flat out' has now dropped by about a 100mW in spite of the voltage boost which indicates a reassuring improvement of PSU efficiency.  :)

 I haven't bothered trying to tackle the half mains voltage 'tingle current' issue since I know this is the inevitable consequence of the mandatory EMC 'grounding capacitor' (typically a 1nF Y class) in a class II double insulated PSU. The best solution imo, is to track down a better class of smpsu where the need for such a capacitor has been obviated by the use of an HF ferrite switching transformer with the necessary screening foil built in to shield the secondary winding(s) from the HF voltage switching transients on the HV primary.

 In a class II double insulated PSU, this shielding foil will still be connected to the 'half mains' voltage grounding reference but will only present a few pF  of leakage coupling of the 50/60Hz half mains voltage rather than the 470pF or higher of a class Y capacitor.

 Since I did these PSU mods prior to recording my DSO traces as a 'before the opamp upgrade' record, I can only show attached jpg images for the 20Mz at 20v into 50 ohm load after having improved the PSU, so I have no proof that my mods are of any benefit with the existing opamp chips. Nevertheless, I've attached them for reference.

 I ordered a couple of THS3491 opamp chips from Farnell/E14 last Thursday and I'm expecting them to finally get here, as promised by UPS, this Monday ("By the end of the day"). It'll be interesting to see whether these will offer any further improvement over that seen with the lower spec THS3095s that had been used by one of the posters to this thread earlier this year.

 The problem in this case being the performance limitations of the OPA 686N chips driving them and the relay switching which bypassess the THS3002 (or 3091/3095/3491 upgrade) for frequencies above the 20MHz limit. It could well be that the crafty relay switching employed in Feeltech's design to minimise the shortcomings of the THS3002 chip will probably turn the THS3491 upgrade into an 'overkill solution'. Still "Better safe than sorry.", after all, there wasn't that big a price premium in opting for the 3491s over the slightly cheaper 3091 or 3095 chips and, who knows, I or someone else might come up with a mod to take full advantage of these opamp upgrades.  :)

 Regards, Johnny B Good
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 19, 2018, 10:30:54 pm
Hi, cybermaus,
The problem is mostly due to the "30021" op amp. As you say, it is only just above 7Vpp into 50 ohms. And I had tried at first powering the generator from my lab supply with +-15V. The improvement was miserable if any. So, it must be the op amp.

With the THS3095 the generator easily outputs 20Vpp (10Vpp into 50R), no problem. Still, if to be picky, the behavior of the THS3095 is in line with what the manufacturer shows in their datasheet for the component. The pictures bellow are taken from the datasheet. At high frequencies, as those graphs also show, I see some distortion (not clipping though but exactly the same as manufacturer graphs show). The manufacturer suggests properly paralleling two op-amps for each channel (second picture) to remove most of the distortion. That is what major manufacturers, like Siglent, and others do in their designs. For the sake of interest, I might have a look at that later (accidentally, I do have two more THS3095s in my drawer). By the way, Texas Instruments have recently introduced a new power opamp - THS3491. If what they say is true, that one is a real beast with unmatched performance. But they do not have them yet.

Sure, the generator steps down to 5Vpp at 20MHz. But that is to be expected. Normal behavior. Difficult to achieve frequent swings at high voltages.

 Although the subject of replacing the THS3002 dual opamp seems to be just over a year old (I've not been able to track down later opamp references), rather than directly follow up on my previous, first time post,  I thought a 'reply' to this post would be quite apposite in view of the fact that I've just replaced the stock 3002 opamp in my FY6600-60M (purchased almost three weeks ago) with a pair of THS3491s and so can verify that 'what they say' is indeed true! :-)

 I've taken the liberty of reposting Vytautas's  oscillographs showing the improved 20MHz, 20V p2p waveforms along with my own 'before and after pics' which do show a further quality improvement over the earlier 3001 and 3095 chips. Unfortunately, this modification doesn't improve the quality of square waves beyond what was available with the original dual opamp. I can only suppose this is a limitation imposed by the anti-aliasing filter.

 Regards, Johnny B Good

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 20, 2018, 12:36:28 am
Welcome to the 6600 Club, Johnny!  You've just reminded me that I still haven't got round to fitting the 3491s I bought for my FY6800 several weeks ago.  I'd always planned to do a side by side comparison with the 3095s I put in the FY6600, but I got sidetracked onto other projects and forgot about it.  It's now back on the list of jobs to be done!  I'd recommend doing the D75J TCXO upgrade to your 6600 as well - it gives a huge improvement to frequency accuracy and stability.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 20, 2018, 05:34:28 am
Welcome to the 6600 Club, Johnny!  You've just reminded me that I still haven't got round to fitting the 3491s I bought for my FY6800 several weeks ago.  I'd always planned to do a side by side comparison with the 3095s I put in the FY6600, but I got sidetracked onto other projects and forgot about it.  It's now back on the list of jobs to be done!  I'd recommend doing the D75J TCXO upgrade to your 6600 as well - it gives a huge improvement to frequency accuracy and stability.

Regards,
Dave

 Hi Dave and thanks for that welcome.

 I've had the benefit of a lot of hindsight (over 12months of it!) by the time my interest had turned to the FY6600. :-)

 Reading all 69 pages took about 3 days on my initial full read through in order to glean as much guidance in my decision as to which cheap Chinese ARWG to blow my hard earned upon (it was quite a compelling read!). I really owe everybody who has contributed to this discussion over the past 12 months or so a debt of gratitude so, thanks to everybody for your invaluable insights and suggestions. As a matter of interest, after having gotten hold of an FY6600-60M, I reread the whole of this discussion thread again! I just wanted to clarify a few of the points made in the various upgrades I was interested in.

 I might be an old hand on Usenet but I'm a bit of a newbie when it comes to web based forums (fora). My one experience of participating in web forums was about a decade ago when I tried to stay in contact with the exiled zetnet clientèle after Breathe Networks Ltd (BNL) hoovered up the last of the decent small ISPs when the original owners were forced to sell up/their customers down the river (take your pick).

 Zetnet had set up several private news groups on their news server (this was back in the day when many such small ISPs ran their own news servers complete with a few private news groups to serve their customers needs). Zetnet had its own USP to which BNL were entirely oblivious, so much so that I got myself a whole year's worth of free service through their total and utter technical incompetence.

 Zetnet had a very loyal following in their customer base of which a large part had developed a strong sense of community through the private/closed zetnet news groups. When the end finally came, a web forum had been set up for the "Zetnutters", as we referred to ourselves, to maintain contact. The problem was, as it generally is, the rather klunky interface and the need to log on every time. Web fora are, in general, a piss poor substitute for Usenet imo, and I soon gave up on this rather klunky substitute for the old zetnet news groups.

 Since then, my main experience of web forums has been in the form of anonymous guest read only sessions typically as the result of a google search for answers to various technical issues, where, as a silent witness, I''d often find myself screaming inside my mind at the abysmal lack of expertise and ignorance being demonstrated before my very eyes. Sometimes I'd find inspiration for solving a problem but most times, I'd just find the experience an exercise in frustration and move on.

 Even where I feel I could join in simply to straighten out a few misconceptions, there was very little point since the thread I'd tracked down through a search had run its course, often several years earlier, leaving me with a sense of frustration that I've since come to terms with as the unfortunate side effect of such guest visits.

 Here, in this case, the situation is very different. For one thing it wasn't the result of a search engine's attempt to direct me to a particular topic - it was a side note in a usenet posting in SED about the remarkably cheap price point of modern Chinese AWG signal generators where one of the contributors (possibly the OP himself) had posted a link to this discussion thread. The other point being that despite this thread's remarkable age, it was quite obviously still ongoing and a quick skim had revealed a very high signal to noise ratio with a high quality of technical competence which, for me at least, is an extremely unusual experience when it comes to web forums.  Anyhow, here I am, actually participating (in my own gauche way) in a web forum! :-)

 This leads me to explain that I'm currently seeing an error message (which I suspect is no longer actually relevant - I hope!) in this reply form, stating:-

 "The following error or errors occurred while posting this message:
The message body was left empty."

 as a result of my wanting to cancel my reply so that I could go back to click on the "Insert Quote" button by way of starting over again. Having opened the reply page, I could see no way of adding 'quotage' (hence this attempt to start over) other than to ignore the 'error message' and go back to your post and click the "Insert Quote" button in the hope that it would clear the error message - which it hasn't. I figure this is a a basic bug or 'feature' of the data entry input system that's handling the 'reply to function'. It's probably waiting on my hitting the 'send button' to recheck for content before clearing the error message. [Actually, all it needed was for me to press the preview button after having written something for it to display. :-)]

 The point I'm making is that you might be (actually, you are!) reading a copy of what I've been typing into the message reply box (I'm going to copy and paste my efforts into a backup text file just in case :-) ). Also, of course, in my haste to make my first posting, I'd been anxious to get something written up to test my understanding of the reply mechanism, hence the terse nature of my introduction to the group.

 Anyhow,  now that I've explained my distracted first posts and sorted out the distracting error message in this attempt to reply, I can provide a little more info about my opamp upgrade. Having managed to cobble a special de-soldering bit (short length of 2.5mm solid copper wrapped around the heating element of my 25W Antex) to retrieve the original 3002 chip non-destructively (I did manage to slightly dislodge a tiny smd resistor in the removal process but I was able to  to resolder it back in place with the aid of a tooth pick and my 18W Antex). I was able to solder the 3491s onto the U21/U22 locations with some difficulty (and trepidation) using my smaller 18W Antex.

 I was aware of the issue with the extra Vref and /PD pins on the 3095 and the 3491 chips occupying isolated pads on the board. Not a problem for the 3091 but a problem certainly for the 3491 (can't recall if it was the same for the earlier 3095 chip) so I had a very careful read of the data sheet to confirm that whilst the /PD could be left floating, the Vref pin couldn't - it must be connected to ground or -Vss - I chose to strap it to the -Vss pin.

 The 3491 has the added complication of the thermal pad on its underside. I was considering cutting out a tiny piece of thermally conductive silicone rubber to act as a 'gasket' but decided this was an unnecessary complication since it's electrically isolated anyway (although there is a circuit track or two in the landing zone that would only have the solder mask to electrically insulate them from the thermal pad - not a problem once the chip is firmly soldered into place) so I decided the best compromise was simply to place a very thin coat of heatsink compound in the landing zone between the solder pads. I also dabbed tiny blobs of heatsink paste on the opamps and the third chip covered by the heatsink prior to reassembling it back to the board. It's worth noting that the heatsink just about fully covers the U21 and U22 chip locations rather than just 60% of the original dual opamp chip - just as well since at full chat (20Vp2p 50 ohm load at 20MHz) the total mains input wattage has gone up from 8.8W to 9.9W measured with my trusty Metrawatt analogue watt meter.

 I've more or less had the FY6600 running flat out since I completed the mod around 3:30 Monday afternoon which, as I type this, represents a 12 hour 'soak test'. It runs a little warmer but I've seen no sign of the 3491's fabled thermal protection kicking in.

 Using a cheap IR thermometer, I got readings of 50 or so deg C off the base of the heatsink as well as the top of the Cyclone FPGA. Aluminium has a lower surface IR factor than most other materials hence my pointing the IR thermometer at the base where I'm probably picking up the PCB temperature (closed up, the base of the case feels just as warm as the two warm spots on the lid). I can touch the top of the FPGA with my finger without any discomfort but the aluminium heatsink is almost too hot to maintain finger contact with - but this is to be expected anyway, even when both items happen to be the same temperature.

 With regard to that D75J TCXO upgrade, that's also on my to do list. I've been checking out availability of 0.1ppm 50MHz TCXOs and the cheapest units on Ebay claiming 0.1ppm, are all from the same Chinese based trader, yuyan-industrial with 3 different models ranging in price from £17.90 to £22.0). The question in my mind is, "Are there such TCXOs with 0.1ppm stability and accuracy to be had from Chinese suppliers via the auspices of Ebay, or is it case of the impossible  AH claims made for Surefire 18650 Lithium cells and I simply land up with a 5 or 10 ppm "TCXO" (if I'm lucky)?".

 TBH, I don't want to rush into spending any more money just yet until that FY6600 has survived the "Infant Mortally" phase of its service lifetime. Those THS3491IDDAT chips from Farnell/Element14 have already added an extra £27.36 onto the original £75.66 I paid for the sig generator in the first place, turning it into a £103.02 sig generator (still cheap for the improved performance, mind you). A two or three orders of magnitude improvement in frequency accuracy and stability would be a nice touch, especially if it can be done using a simple drop in replacement for the existing clock generator module. Shoehorning an OCXO module into the box is something I'd prefer to avoid if possible.

 I think I should be looking for a better quality smpsu which uses the slightly more expensive type of ferrite isolating transformer with a screening foil layer to shield the secondary windings from the HV switching transients that get capacitively coupled onto the output terminals rather than rely on the EMC capacitor bodge responsible for the unconscionable levels of half mains voltage leakage current.

 The real hazard of using the EMC cap bodge lies with its potential (pun intended) to discharge a high voltage into the DUT at the moment of contact - the 'half live tingle current' is merely an annoyance otherwise. If you want to retain the option to eliminate ground loop currents by letting the generator float free of any local safety earth connection, a properly designed smpsu is the best way to go imo (even if you do intend to make this a switchable option). I suspect the existing smpsu is now running close to its maximum rated output so worth an upgrade anyway.

 Right now, I'm looking to source cost effective TCXO modules (preferably 'drop in replacement if possible) and a decent 15 to 20 watt rated three rail smpsu so I'd welcome any advice in regard of achieving those goals. :-)

Regards, Johnny B Good

[EDIT for future reference 2019-10-22]

 A lot of water has since flowed under the bridge and many discoveries from hard won experience have led to a change of mind over wasting time in a holy grail search for any type of class II smpsu that exchanges the cost of a class Y2 cap for that of the penny expense of a shielding foil in the HF ferrite stepdown/isolating transformer to eliminate this common mode interference on the outputs free of any such 'touch voltage leakage' from the mandated by EMC directive Y cap to short the high voltage switching transients back to their origin to attenuate such unwanted switching noise by some 10 to 20dB (if you're very very lucky!).

 In the end, after trying out some rather fanciful 'nulling out' schemes, done in the name of avoiding an earth loop issue, it became all too obvious that the only practical way to "Have your cake AND eat it!" was to fit a 3 pole mains socket (C6 or C14 - I chose a C6 to minimise the "Tail Wags Dog Effect"(tm) with this extremely lightweight signal generator) purely to give access to a connection to ground to permit a 3 to 10KR 'static drain' resistor connection to the common return rail (0v and BNC shield ground returns).

 On a 240v mains supply, this knocks the 80 to 90vac leakage voltage seen with a typical DMM down to just half a volt rms (and less with a 3K resistor). There is absolutely no need for a hard earth connection in this class II mains powered device and the 10 to 3KR 'drain resistor nicely drops the Y cap leakage voltage to well below the safe limits for even the most delicate of electronic components you might otherwise damage with a 170 to 340vdc transient discharge from that accursed Y cap at the moment of contact at the worst possible point in a cycle of 50 or 60Hz mains voltage.

 Assuming a BNC cable shield resistance as high as one ohm between the signal generator and the DUT's ground reference points, a 10KR will give you some 60dB and a 3KR some 50dB reduction in unwanted earth loop interference from noise sources in the mains earth wiring (neutral to ground potential difference voltages due to volt drops from the total house load current on the incoming supply, including possible thermocouple effects from hot junctions and the more likely galvanic dc sources of interference through electrolytic corrosion from damp ingress which could easily compete with any dialled in DC offsets in the tens of millivolts range).

 Also, it's worth pointing out that the 'static drain' resistor will also attenuate any common mode switching transients being conducting back into the mains safety earth wiring, reducing radiated interference from the HF switching transients leaking onto the output ground return via the smpsu's transformer's inter-winding capacitance.

 If you want to avoid replacing the existing smpsu board with an analogue bodge psu (for the time being at any rate whilst you choose the most optimum analogue based design), I suggest you upgrade the output rectifier diodes to proper Schottky types, double up the 220μF 16v caps on the +/-12v rails to 470μF 16v 105 deg C types (voltage rating _isn't_ the issue here) and wind a single turn buck winding on the transformer to buck the 5v winding voltage (half a dozen single turns of thin insulated wire in parallel to give better coupling and minimal loss) which neatly forces the +/-12 rails to something like 13.5v each on load without resorting to increasing the 5 volt rail to 5.5v as per the earlier trick to get a decent voltage level on the 12v rails. You may have to reverse the connection between the lifted out cathode of the 5v diode and the pcb hole it was disconnected from.

 The details were posted here, with pictures on page 74 of an 86 page (at the time of this edit) topic thread:

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2310768/#msg2310768 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2310768/#msg2310768)

 I'm still using the original (if many times modified smpsu board) at this time but I do have plans to replace it with an analogue hybrid (classic 3 terminal voltage regulators for the +/-13.5v rails powered from 15 or 16vac secondary winding(s) for lowest ripple noise on the analogue voltage rails with a 5v 1.5A rated output dc-dc converter connected to any ac winding voltage in the range 7 to 18 volts (to give me more transformer secondary options - ideally a separate 8vac winding to maximise isolation of the digital and analogue rails and optimal voltage choice for use of a 7805 regulator if deemed beneficial in spite of the modest additional heat load this would introduce).

 However, I do want to test the benefit of completely eliminating the switching noise of the existing psu by putting a recently acquired pair of 6v carbon zinc lantern batteries in series for the -12v rail and a 12AH SLA to power the +12v rail and a 7805 regulator for the 5v rail to provide noiseless sources of dc power to allow me to determine the potential benefit of an analogue psu upgrade. It's now just a matter of finding a Round Tuit to run such a test setup.:)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 20, 2018, 01:52:13 pm
Hi Johnny,

That's quite a tome you've just sent: forgive me for not replying in detail, but it sounds like you're an old-time tinkerer like myself.  I started off on various bulletin boards in the very early days of the internet, before the likes of Compuserve and AOL appeared, and well before the WWWeb took off.  Usenet served me well for years, but with everything being web-based now, you just have to accept the quirks and foibles that come with it.  You soon grow into it!

Back to business, no-one has come up with anything better than the D75J TCXO so far.  It's cheap, but the only place you can get one is Digikey (order in the UK, get it in a couple of days from the US, but postage doubles the cost unless your order is over £40), and it is a drop in replacement - but you'll need a hot air gun to remove the old one unless you can rig up a piece of wire on your soldering iron to melt the four contacts at once.  I remember looking at those Chinese TCXOs a few months ago, but they are rather expensive to take a chance on, and they'll probably need mounting on stilts, or a daughterboard, as there'll be no room on the PCB for them.

On the subject of soldering irons, my 18W Antex bit the dust about 5 years ago and I had to continue with the 30W Antex I bought in the 1980s, using a bit that was too large for most modern needs.  A couple of years ago I switched to Hakko T12 stuff - it was like driving a new Jag after getting out of a Ford Anglia.  Even the Chinese clones are good, and the right tools make modding a breeze!

I need to have a read of the 3491 datasheet again, going by what you say, as I was sure they were a simple direct replacement for the 3091/3095 even with the floating pins.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on November 20, 2018, 02:06:41 pm
BTW, I will do a Digikey Germany order by the end of the week, if someone needs a TCXO or anything else, he can PM me.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on November 20, 2018, 10:08:47 pm
...but you'll need a hot air gun to remove the old one unless you can rig up a piece of wire on your soldering iron to melt the four contacts at once.
Commenting on the basis of only looking at tear-down photos of it, I have to guess which components is the osc. But if I guessed right, it seems to have 4 exposed pins/pads. In such case, the Chip Quik removal alloy might also work. I've used it couple times, and it worked really nicely, though I have only used it up to an SO-8 package so far. It worked so nicely with the small "kit" I bought first, that I bought a bigger bunch of it soon after.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 21, 2018, 12:03:27 am
Yes, bugi, you're right - it would be a good alternative in this case.  After watching a video of it in use a couple of weeks ago I almost bought some myself, until I saw the price for a couple of strands of the stuff :).  I suppose the hot air gun has the advantage that you don't have all the cleaning up and re-tinning to do after the chip removal, and you can use it to attach the new chip as well in most cases - the D75J possibly being the exception as the contacts on its underside don't quite match the pads on the PCB.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on November 21, 2018, 08:37:44 am
The cleaning afterwards is quite easy, at least if the area is not tight, but it still needs to be done. Price is indeed high, so one needs to consider the price of the device being "fixed" (or modded) and prices of other solutions. However, I think in this case the device is valuable enough that using a bit of that alloy would be justifiable.

If one already has a nice hot air station, then that would likely be simpler solution.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 21, 2018, 08:45:04 pm
Hi Johnny,

That's quite a tome you've just sent: forgive me for not replying in detail, but it sounds like you're an old-time tinkerer like myself.  I started off on various bulletin boards in the very early days of the internet, before the likes of Compuserve and AOL appeared, and well before the WWWeb took off.  Usenet served me well for years, but with everything being web-based now, you just have to accept the quirks and foibles that come with it.  You soon grow into it!

Back to business, no-one has come up with anything better than the D75J TCXO so far.  It's cheap, but the only place you can get one is Digikey (order in the UK, get it in a couple of days from the US, but postage doubles the cost unless your order is over £40), and it is a drop in replacement - but you'll need a hot air gun to remove the old one unless you can rig up a piece of wire on your soldering iron to melt the four contacts at once.  I remember looking at those Chinese TCXOs a few months ago, but they are rather expensive to take a chance on, and they'll probably need mounting on stilts, or a daughterboard, as there'll be no room on the PCB for them.

On the subject of soldering irons, my 18W Antex bit the dust about 5 years ago and I had to continue with the 30W Antex I bought in the 1980s, using a bit that was too large for most modern needs.  A couple of years ago I switched to Hakko T12 stuff - it was like driving a new Jag after getting out of a Ford Anglia.  Even the Chinese clones are good, and the right tools make modding a breeze!

I need to have a read of the 3491 datasheet again, going by what you say, as I was sure they were a simple direct replacement for the 3091/3095 even with the floating pins.

Regards,
Dave

 Hello Dave,

 I didn't get started with the internet (and usenet) until around 1996 when I joined up via a dial up service to a small, highly recommended ISP (based in, of all places, the Shetland Islands!) known as zetnet. For the first 4 or 5 years, I was totally reliant on their dial up PoP until my teenage daughter paid NTL to install their cable TV service with 512Kbps broadband at the behest of her boyfriend / fiancée (now our SiL) who was/is a web developer with some expertise in Linux. I assembled a lowest power consumption PC and had him install a Linux based router/firewall/gateway OS so the BB could be shared to the Cheapernet(tm) cabled house LAN for all to access with a tenner a month towards their rental costs as the inducement.

 This was just about the time when zetnet's resident wizard (Tim Cole, RIP) had added additional connectivity to the custom email/usenet client, ZIMACS to allow authenticated connections via other dial up access points provided by the likes of Freeserve et al, allowing me to connect via the NTL BB cable connection, neatly eliminating the cost of a dial up connection (zetnet had started offering ADSL packages by then to their customer base). I learned soon enough of the crapiness of ADSL compared to the real deal of a cabled broadband connection from all of the ADSL connection woes being endlesly reported in the zetnet groups for the next 5 or 6 years).

 When my daughter left home, I took over the NTL account just at the time when they first offered broadband internet connectivity as a stand alone service sans what had been a mandatory pre-requisite of TV and broadband. Having discovered I was paying an extra 20 quid a month for an unnecessary TV and BB service, I ordered a cessation of the TV package and transfer to BB only (at the minimum speed of 128Kbps 15 quid a month service).

 Unfortunately, their 'engineers' (two of them) turned up whilst I was in hospital as a result of an emergency admission and simply recovered the Pace STB without replacing it with the Ambit modem to effect the change-over to BB only. So through no fault of my own, when I finally got home after a fortnight or so's stay in hospital, I found myself without a connection and had to wait another month for NTL to schedule another visit to correct their cockup. However, I did receive compensation for not only the month or so I'd been without service but also another few months' worth for free. If I had been on hand at the time of the first 'engineers' visit, I would have stopped them taking the Pace box away until they'd returned with the required Ambit modem to complete the task as per my request.

 Other than that major cockup of a simple change of service request, NTL (now Virgen Media) have provided a very reliable service that puts to shame the service typically experience by many relying on ADSL over their phone lines. Over the years, what had started out as the slowest basic broadband service (initially 128Kbps for 15 quid a month until they decided to bring it in line with the 600Kbps upgrade of their next higher level of 512Kbps service by increasing it to 150Kbps as a ruse to charge an inordinate 3 quid increase) has enjoyed "free upgrades" which have, so far, culminated in a speed boost to 80Mbps down, 5Mbps up. Mind you, inflation has just about doubled the monthly rental to £37.74. Still, I suppose a connection speed increase of 640 times for a mere doubling of cost is hardly a basis of complaint.  :)

 Mind you, I wasn't entirely new to the concept of Usenet since I'd been making use of the radioham BBS packet radio service since the mid 80s prior to gaining direct access to the internet. The transition to Usenet was a natural upgrade on the radioham BBS packet radio based setup. It's these web based forums that seem so alien and klunky by comparison.  :(

 Anyway, back to the topic. I took note of the D75J TCXO reference and googled it (I wasn't sure whether it was an actual part number or named after its proponent (like the classic G5RV antenna)). I see that it's merely a 1ppm part rather than the 0.1ppm ROJON TCXOs being offered by Chinese only sources (the cheapest option yet is a small PCB module containing a TCXO for approximately £15.59 now (yesterday, it had been approximately £15.42) available here: <https://www.ebay.co.uk/itm/1pcs-50MHZ-hifi-TCXO-0-1ppm-Ultra-precision-Golden-Oscillator-CLOCK-power-supply/132652757688?hash=item1ee2b872b8:g:zFoAAOSwlgNbGBqS:rk:5:pf:0> or https://tinyurl.com/y8he5bqa (https://tinyurl.com/y8he5bqa)).

 If it wasn't for the fact that I'd like to have a decent very low leakage high efficiency smpsu based PSU with a little more margin in hand, I'd have ordered it there and then. However, one step at a time - I don't want to find that by the time I'd received the TXCO, mid January 2019 (knowing my luck), my FY6600 had suffered a horrible infant mortality failure no longer insured by its warranty due to my modifications to date. An ultra low leakage three rail class II smpsu can always be found a use elsewhere, the 1 or 0.1 ppm 50MHz TCXO, otoh, is a rather more niche item to repurpose.

 This leads me to the problem of tracking down an affordable 3 rail ultra low leakage class II smpsu PCB module. Try as I did last night - the reason I'm only replying just now - I couldn't find anything remotely suitable. Such low leakage class II smpsus are possible - I've actually got one in the form of a Nokia 5.7v 800mA "For LTE use only" phone charger 110 to 240vac wallwart which only shows as 12.5vac leakage voltage to ground with my DMM (presumably 10 or 11Mohm impedance) versus the more typical 75-79vac seen with the Feeltech and almost every other wallwart smpsu I have to hand. Better yet, its no load consumption is circa 50mW (barely perceptible when viewing the mirror backed 100 watt scale of my Metrawatt analogue wattmeter with a magnifying glass) which bodes well for its efficiency.

 It looks like my best bet is to track down a low leakage class II 90 to 265vac 5v 3 or 4 amp smpsu and hang a couple of dc-dc 5v to 15v (one plus, the other minus) boost converter modules onto its output. Low leakage 3 rail PSUs seem to be about as rare as unicorn droppings.  >:(

  With regard to my soldering kit, I'll just carry on with my existing 18 and 24 watt Antex irons and copper wire adaptor bodges for now. I'll consider soldering tool upgrades when (and if ever) I get a decent workshop sorted out (we're considering moving from this large 6 bedroom, with basement, Victorian semi-detached house, to a decent sized 3 bed bungalow with an outhouse or two (or space to build a decent workshop)) so I'm in a bit of a Limbo situation right now.

 Regarding the need to tie the Vref to ground or -Vs on the THS3095, I think the advice (emphasised so clearly in the THS3491 data sheet but overlooked in the THS3091/3095 data sheet) to NOT let the Vref float still applies. If you read the description on page 26 of the 3095's data sheet, you'll see the need to tie the Vref to ground or -Vs rail since this would otherwise float to the V+ rail, some 4 volts above its recommended voltage level. The /PD can be left floating since this also swings to the Vs+ rail. The /PD pin has to be 2v or more positive than the Vref pin in order to guarantee enabling of the amp. This condition is clearly impossible when both pins float to Vs+, hence (in the 3491 data sheet) the exhortation to NOT let the Vref float free.

 The residual distortion shown in the DSO trace of the THS3095's output waveform at 20v P-P 20MHz may simply be a symptom of allowing the Vref pins to float. I chose to tie the Vref to Vs- rather than ground since it saved scraping through the solder resist to solder onto a groundplane and a handy VS- connection lay only three pins away from the pin 1 Vref on pin4 of the chip (also if I must rely on just letting the /PD pin float in a vulnerable  hiZ state to the VS+ rail, the extra voltage margin wouldn't hurt).

 If I were you, I'd be inclined to strap pins 1 and 4 on each of those 3095s and repeat the waveform tests at 20Mz 20v P-P both in HiZ and 50 ohm terminated conditions to compare against the earlier tests. You might not need to upgrade to the 3491s (unless you're planning on doing a mod that over-rides the crafty relay switching designed to mask the 3002's shortcomings).

For anyone who might be contemplating some of the modifications that have successfully been applied by members of this discussion thread, It seems to me that the best order to follow is firstly to modify the existing PSU to improve its efficiency on the +/- 12v rails by replacing the shoddy RF1007 diodes with proper 20 or 30 amp 40v PIVr rated dual shottky TO220 rectifiers and  fit a 100K or 47K resistor across the lower arm of the 10K+10K divider network to raise the 5v line from 4.95 to 5.25 or 5.49 volts to take the 12v rails another half to one volt higher again.

 It's a simple and effective mod but it doesn't address the HiZ half mains voltage leakage issue. The solution to that problem needs a better class of class II PSU, analogue if you must but preferably a good quality smpsu which uses an HF ferrite transformer with the required shielding foil layer between the high voltage primary and the low voltage secondary windings to obviate the need to bodge an EMC countermeasure in the form of that 1nF class Y cap.

 Secondly, upgrade the existing dual opamp setup to a pair of single opamps using either THS 3091, 3095 or 3491 SOT8 chips, remembering to strap pins 1 and 4 together in the case of the 3095 and 3491 chips.

 Thirdly, if you feel the need to match the existing 50MHz 100ppm frequency reference to the counter's display resolution, then install a 50MHz 0.1ppm TCXO (if you're going to bother at all, why only take half measures with a mere 1ppm rated TCXO when you can get hold of a 0.1ppm ROJON part from a Chinese supplier on Ebay for as little as 15 or 16 quid?  :)).

 Fourthly, if the issue of mains leakage still troubles you, replace the PSU board with a class II unit (analogue or smpsu) that only has a few pF's worth of half mains voltage leakage (mains transformer 50/60Hz leakage of analogue PSUs or ditto for the foil layer screen connection via a 10nF capacitor to the half mains voltage virtual ground in a high quality ferrite transformer used in properly designed smpsus free of the need to include that abomination of the classic 1nF EMC bodge capacitor).

 The classic analogue mains PSU has the charm that such low leakage is inherent without having to specify it explicitly whereas the smpsu needs to have this requirement clearly spelled out in its specifications - good luck in finding such smpsus by design.  :(


 [EDIT 2021-11-25] Please disregard my rather pompous advice above :-[ and take note of the edit below.  ::)

Regards, Johnny B Good

[EDIT 20190425]  I eventually changed my mind about replacing the PS board with a medical grade low leakage smpsu just to avoid having to upgrade to a 3 pin socket and thicker, "Tail wagging dog" mains lead some two or three months later.

 I eventually realised that even with such low leakage, there'd still be enough residual leakage voltage with a potential to destroy the more electrically fragile DUTs I might land up testing. In the end, the pragmatic solution also proved to be the most optimal. However, I used an 11KR resistor (three 33KR resistor in parallel) as a low impedance static drain which knocks the 90vac down to a mere 500mV without introducing earth loop effects which the 100nF capacitor option used by others would introduce at high frequencies.

 All the PE connection was doing was to provide a convenient way to automatically connect an 11KR static drain between the zero volt reference and ground. The PS board is still a class II double insulated smpsu so a 'hard' protective ground connection is not needed (nor desired). Leakage voltage risk suppressed without the introduction of a troublesome grounding loop as per Feeltech's bodgery with the FY6800.

 The details of this are in my later posts - I'm mentioning it here for anyone who may be plodding their way through this thread for the very first time. :-)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on November 21, 2018, 10:32:06 pm
Hi Johny ,welcome.

Wow a three day read through , and then a re read .

I probably read each post at least twice by now , but in small chunks ,

I have both 66 and 68 hunderd , the 68 was a won in a competition held by Feeltech itself , there was several other people very worthy of a free machine for their contributions ,but if your not in you cant win .

Ive recently got myself a pair of Hewlett Packard HP200cd tube sine oscillators , in the 50's these were state of the art and in fact the product line lasted well into the mid 80's tubes and all , they did drop the tube rectifier in the later models though ,about .5 % thd was as good as they do normally , now with the Feeltech I can easily get very very low distortion audio frequency sine waves ,the key to this is to use an external attenuator and run the unit full throttle ,thus minimising any digital artifacts and using up the full bit rate of the unit . Theres no doubt the original power supply would be marginal with higher powered op amps and under volted too .Any offset dialed in at 20v pk-pk instantly clips the outputs , theres no margin .
I went linear ,with a transformer and regulators ,just like a conventional op amp audio set up .
I did fool around with a few other switchers as well , I tried to run the original psu with the 5 volt unloaded but the  +/- rails dropped way low .
Deriving the three voltages from one switch  psu I dont like , you'll find that under load the original psu droops under high voltage swing on the +/- rails , thats no good at all for fidelity. There have been a handfull hoping to make further improvements , including the custom software from Fremens, he ironed out some of the waveform compatibility issues for us in the Feeltech package , and of course allowed further tweaks if you used a programed STM32 microcontroller . I guess everyone's just settled into using their units now and are happy with the improvements they made , I would seriously think about a larger heatsink for the newer TI op amps though maybe even extra wings of aluminium extrusion screwed into the original .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 22, 2018, 04:03:31 am
Hi Johny ,welcome.

Wow a three day read through , and then a re read .

I probably read each post at least twice by now , but in small chunks ,

I have both 66 and 68 hunderd , the 68 was a won in a competition held by Feeltech itself , there was several other people very worthy of a free machine for their contributions ,but if your not in you cant win .

Ive recently got myself a pair of Hewlett Packard HP200cd tube sine oscillators , in the 50's these were state of the art and in fact the product line lasted well into the mid 80's tubes and all , they did drop the tube rectifier in the later models though ,about .5 % thd was as good as they do normally , now with the Feeltech I can easily get very very low distortion audio frequency sine waves ,the key to this is to use an external attenuator and run the unit full throttle ,thus minimising any digital artifacts and using up the full bit rate of the unit . Theres no doubt the original power supply would be marginal with higher powered op amps and under volted too .Any offset dialed in at 20v pk-pk instantly clips the outputs , theres no margin .
I went linear ,with a transformer and regulators ,just like a conventional op amp audio set up .
I did fool around with a few other switchers as well , I tried to run the original psu with the 5 volt unloaded but the  +/- rails dropped way low .
Deriving the three voltages from one switch  psu I dont like , you'll find that under load the original psu droops under high voltage swing on the +/- rails , thats no good at all for fidelity. There have been a handfull hoping to make further improvements , including the custom software from Fremens, he ironed out some of the waveform compatibility issues for us in the Feeltech package , and of course allowed further tweaks if you used a programed STM32 microcontroller . I guess everyone's just settled into using their units now and are happy with the improvements they made , I would seriously think about a larger heatsink for the newer TI op amps though maybe even extra wings of aluminium extrusion screwed into the original .

 Thanks for persevering.  :)

 I had a lot of material to work with (69 pages!) and a lot of points I wanted to address. Sorry for unloading it all in two large lumps, so to speak. Hopefully, I can dial my post lengths back to more manageable portions now that I've got most of the comments and observations I've had bottled up over the past couple of weeks since I read through the whole thread off my chest.

 Congratulations on winning the 6800 btw. I guess that makes you our "Go to Guy" for comparing these two Feeltech products.  :)  It's an interesting point you've made about the HP200CD only managing a half percent THD. Considering the revived interest in all things tubed (valved) by the HiFi fraternity, that must come as a bit of a disappointment for the more extreme proponents of tubed kit. TBH, it's a bit of surprise to me that valved test gear couldn't do much better.

 Understand about the point of setting the output level to the 'sweet spot' and applying attenuation to get the required level (and minimise amplifier noise into the bargain as well). As you (and everyone else) have observed, the PSU in the FY6600 is barely up to the job even with the modifications suggested here (does the FY6800 suffer the same deficiency I wonder?). Reducing the loading on the +5v doesn't do the +/-12 volt rails any favours.

 It's an old problem with multi-rail power supplies. The original PC and XT then the AT and now the ATX psus suffer exactly the same effect but in the case of desktop PC supplies, the variation on the 12 rails was never an issue, they just had to remain within the wider +/-10% tolerance that was allowed on those rails. In this case, it's the +/-12 rails that are the more critical rather than the 5v which seems to be used to power the 3.3v and 2.5v (and 1.5v?) regulators on the main board. Hopefully, the 3.3v regulator is a low dropout version (I haven't checked but it doesn't matter so much to me since I raised the 5v to 5.49 volts purely to increase the 12v rail voltages).

 Putting my FY6600 into standby mode only saves just under 4W - it drops from a high of a gnat's dick shy of 10W to similarly just over the 6W mark. I'd say at least half the power supplied by its tiny PSU must be via the 12v rails when it's driving 50 ohm loads at the 20v p-p limit. Like yourself, I did observe quite bit of sag on the 12v rails between the zero and the maximum output levels. It could certainly do with a better quality PSU, preferably a higher efficiency smpsu to minimise the heat load. Small smpsus like the one used here by Feeltech, typically have an efficiency of 80% at full output so I figure the PSU is contributing a bad two watts to the heat loading inside that not very well vented case.

 With only half a watt total being accounted for in the 50 ohm dummy loads, that leaves a balance of a further 7.5 watts of waste heat being generated by the front panel and main board. Going by the noticeably hotter feel of the underside of the case compared to the two 'Hot Spots' (fsvo 'Hot') on the topside, I'd guess a good (or bad if you prefer) 6 watts or so must be coming from the main board. I think drilling holes in the underside of the case below the main board would be the best place to make a start if you want to improve the ventilation.

 From my experience of running a 24 hour heat soak test, drilling vent holes in the underside of the case will likely be enough to save the opamps from cooking themselves to death. Allowing some airflow round the underside of the main board will likely reduce the board and the heatsink temperatures by a noticeable amount. You might not need to add any extra metal to the existing heatsink.

 BTW, from what further research I've managed to do into this question of mains leakage currents in class II smpsus, it seems the problem isn't an easy one to fix without increasing the level of common mode conducted switching noise on the output wiring. One treatise (see attached pdf) did note that the use of a screening foil layer between the primary and the secondary windings was the most cost effective way to deal with this 'conflict of interest' between mains leakage and EMC requirements.

 The Y cap is simply a means to press the secondary into service as a shield against the high frequency switching transient voltage capacitively coupling into the output as a common mode conducted interference signal. Unfortunately, since the 'ground reference' is tied to a source of half mains voltage, the half to 2 nF class Y cap also provides a Hi Z leakage path for this voltage to manifest itself on the output terminals. Using a separate shielding foil between the primary and secondary windings as a dedicated screen where the capacitive coupling to the secondary windings is reduced to a mere 40 or 50 pF instead of the 500 to 2200 pF of a Y cap reduces the half mains voltage coupling considerably without compromising the EMC requirements.

 As I see it now, I think my best approach may be to get hold of a low leakage class II 3 or 4 amp rated 5v smpsu and add a couple of DC-DC converters to generate the 14 or 15 volt rails. However, I'm still mulling over alternative solutions to this conflicting requirement of EMC and low mains voltage leakage.

 Regards, Johnny B Good
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 22, 2018, 04:19:43 am
Hi Johnny,

Have you seen these SMPSUs?
https://www.ebay.co.uk/itm/SMPSU-Switched-Mode-Chassis-Power-Supply-12v-0-3A-12v-0-2A-5v-2A-SMPS1-432-/141117111577?var=&hash=item667e84f884 (https://www.ebay.co.uk/itm/SMPSU-Switched-Mode-Chassis-Power-Supply-12v-0-3A-12v-0-2A-5v-2A-SMPS1-432-/141117111577?var=&hash=item667e84f884)
https://www.ebay.co.uk/itm/SMPSU-Switched-Mode-Chassis-Power-Supply-5v-2A-15v-300mA-15v-200mA-Toko-783-/361575419603?hash=item542f930ed3 (https://www.ebay.co.uk/itm/SMPSU-Switched-Mode-Chassis-Power-Supply-5v-2A-15v-300mA-15v-200mA-Toko-783-/361575419603?hash=item542f930ed3)

They look the part, if nothing else, but the seller is an anus - so caveat emptor!!  See the negative feedback on him (which I can corroborate from personal experience.)

That TCXO module you found must be a new one, and it's cheaper than the oscillator by itself from other suppliers.  There's also a Rojon mini TCXO for £22 if you want to be really extravagant:
https://www.ebay.co.uk/itm/Mini-TCXO-50-000MHz-50MHZ-0-1ppm-Ultra-precision-Oscillator-audio-DIY-GQ1-XH/382556866867?hash=item59122a8933:g:nIwAAOSwA3dYL7Cj:rk:3:pf:0 (https://www.ebay.co.uk/itm/Mini-TCXO-50-000MHz-50MHZ-0-1ppm-Ultra-precision-Oscillator-audio-DIY-GQ1-XH/382556866867?hash=item59122a8933:g:nIwAAOSwA3dYL7Cj:rk:3:pf:0)

I can't see a problem with leaving pins 1 and 4 floating in the case of the 3095: both pins are unconnected on the PCB, so both will float to Vs+ and the device will be permanently enabled (no differential just means no power down control, but the default state is enabled, as would be expected).  In the case of the 3491, although the datasheet doesn't recommend leaving PD floating, the device will still be permanently enabled if it is (subject to a probably unlikely stray signal event :)).  I wasn't intending to upgrade the 3095s in my FY6600 to 3491s - I was planning to install them in my FY6800 (when I get round to it!) to get a direct comparison between them and the 3095s, more for curiosity and experimentation than anything else.  If there happens to be a problem with them I've got spare 3095s I can drop back to as the upgrade from the single 3022.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 23, 2018, 02:27:47 am
Hi Johnny,

Have you seen these SMPSUs?
https://www.ebay.co.uk/itm/SMPSU-Switched-Mode-Chassis-Power-Supply-12v-0-3A-12v-0-2A-5v-2A-SMPS1-432-/141117111577?var=&hash=item667e84f884 (https://www.ebay.co.uk/itm/SMPSU-Switched-Mode-Chassis-Power-Supply-12v-0-3A-12v-0-2A-5v-2A-SMPS1-432-/141117111577?var=&hash=item667e84f884)
https://www.ebay.co.uk/itm/SMPSU-Switched-Mode-Chassis-Power-Supply-5v-2A-15v-300mA-15v-200mA-Toko-783-/361575419603?hash=item542f930ed3 (https://www.ebay.co.uk/itm/SMPSU-Switched-Mode-Chassis-Power-Supply-5v-2A-15v-300mA-15v-200mA-Toko-783-/361575419603?hash=item542f930ed3)

They look the part, if nothing else, but the seller is an anus - so caveat emptor!!  See the negative feedback on him (which I can corroborate from personal experience.)

That TCXO module you found must be a new one, and it's cheaper than the oscillator by itself from other suppliers.  There's also a Rojon mini TCXO for £22 if you want to be really extravagant:
https://www.ebay.co.uk/itm/Mini-TCXO-50-000MHz-50MHZ-0-1ppm-Ultra-precision-Oscillator-audio-DIY-GQ1-XH/382556866867?hash=item59122a8933:g:nIwAAOSwA3dYL7Cj:rk:3:pf:0 (https://www.ebay.co.uk/itm/Mini-TCXO-50-000MHz-50MHZ-0-1ppm-Ultra-precision-Oscillator-audio-DIY-GQ1-XH/382556866867?hash=item59122a8933:g:nIwAAOSwA3dYL7Cj:rk:3:pf:0)

I can't see a problem with leaving pins 1 and 4 floating in the case of the 3095: both pins are unconnected on the PCB, so both will float to Vs+ and the device will be permanently enabled (no differential just means no power down control, but the default state is enabled, as would be expected).  In the case of the 3491, although the datasheet doesn't recommend leaving PD floating, the device will still be permanently enabled if it is (subject to a probably unlikely stray signal event :)).  I wasn't intending to upgrade the 3095s in my FY6600 to 3491s - I was planning to install them in my FY6800 (when I get round to it!) to get a direct comparison between them and the 3095s, more for curiosity and experimentation than anything else.  If there happens to be a problem with them I've got spare 3095s I can drop back to as the upgrade from the single 3022.

Regards,
Dave

 Thanks for the links to those PSUs,

 I've just looked them over. Unfortunately, the first thing that strikes me is the marginal current rating of the 12 and 15 volt rails (0.3 and 0.2 amps) which I suspect won't be enough to support the demand from the opamps.

 I noticed the use of a couple of HT smoothing caps (presumably 200 or 250 volt rated ones wired in series) with a flylead jumper on the 12v version for the 120/240 volt mains voltage selector which is a bit of a spoiler (meaning user intervention is required when moving between mains voltage standards - no automatic handling of mains voltage adjustment).

 The 15 volt version is using a single 400v rated 68μF smoothing cap suggesting that it's probably a "Universal" smpsu type. That doesn't preclude the possibility that it may be 200-240 volt only of course, but that seems rather improbable given the extra cost over the optimum choice of 22μF since a 68μF would provide ample smoothing even for a 60W 100v 60Hz supply working off the apparent design rule of a microFarad per watt's worth of loading on a 100v 60Hz supply.

 TBH, neither of them are, imo, suited for the task. I think the best option in this case (looking for a psu system with the lowest possible level of half mains voltage leakage current with good voltage regulation on all three rails) is to find a 15 or 20 W rated 5v low leakage smpsu and use dc-dc converter modules to derive the two independently regulated 15 volt rails rated for 500mA each. This way, you only need to track down one low leakage psu and not have to put up with the indifferent regulation typical of secondary 12/15 volt rails loosely tied to a precisely regulated 5 volt primary output rail courtesy of secondary turns ratio alone.

 I started writing this reply about 12 hours ago but "Real Life"(tm) got in the way and I was still distracted by the, now seemingly impossible task of tracking down a suitable 15 to 25 watt rated Class II 5v smpsu containing a shielded transformer and no frelling Y1 class capacitor (as per that Nokia 5.7v 800mA phone charger that proved to be totally devoid of such vandalism yet was virtually free of the half mains voltage leakage).

 I'm still mulling this problem over but for now, I've changed my mind and decided to upgrade the shite rectifier diode in the FY6600's psu. I've just discovered that at 100Khz 20v p2p, I can offset the voltage by +2.9 and -3.6 volts before clipping becomes evident suggesting  that I can afford the resulting drop on the 12v rails as a result of such an upgrade to the 5v rail after all!

 Regarding TI's advice in the THS3491 data sheet about not letting the Vref pin float, perhaps the absence of such explicit advice in the 3095 data sheet is because it doesn't matter after all... perhaps. I just felt it was a point worth raising considering the distortion at a mere 20MHz that was evident in your(?) 'scope traces.

 Bear in mind that the similar distortion shown in the data sheet was for 32MHz 20v p2p with 100 ohm loading. The adjacent 32MHz trace was with two of them paralleled up to demonstrate the effect of halving the load on each amp to the equivalent of a 200 ohm load per amp, the benefit of which was even more starkly demonstrated in the 64Mhz plots. I'm just sayin' is all.  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 23, 2018, 03:13:02 am

 Thirdly, if you feel the need to match the existing 50MHz 100ppm frequency reference to the counter's display resolution, then install a 50MHz 0.1ppm TCXO (if you're going to bother at all, why only take half measures with a mere 1ppm rated TCXO when you can get hold of a 0.1ppm ROJON part from a Chinese supplier on Ebay for as little as 15 or 16 quid?  :)).


I bought one of these not long ago:
https://www.ebay.co.uk/itm/External-TCXO-clock-PPM-0-1-for-HackRF-one-GPS-Applications-GSM-WCDMA-LTE/173432677234?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 (https://www.ebay.co.uk/itm/External-TCXO-clock-PPM-0-1-for-HackRF-one-GPS-Applications-GSM-WCDMA-LTE/173432677234?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)

and have just looked up the spec in the seller's listing: I thought it was 1ppm, but it's shown as 0.1ppm in the headline, and referred to as 0.1 - 0.5ppm in the description.  It's Rojon, but only half the price of those referred to earlier.  I wonder how much confidence you can have that 0.1ppm means anything like that accuracy, or that the £15 and £22 TCXO cans contain anything different to this £8 one?  The answer, of course, is "none".  Caveat emptor, again!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 24, 2018, 12:37:33 am

 Thirdly, if you feel the need to match the existing 50MHz 100ppm frequency reference to the counter's display resolution, then install a 50MHz 0.1ppm TCXO (if you're going to bother at all, why only take half measures with a mere 1ppm rated TCXO when you can get hold of a 0.1ppm ROJON part from a Chinese supplier on Ebay for as little as 15 or 16 quid?  :)).


I bought one of these not long ago:
https://www.ebay.co.uk/itm/External-TCXO-clock-PPM-0-1-for-HackRF-one-GPS-Applications-GSM-WCDMA-LTE/173432677234?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 (https://www.ebay.co.uk/itm/External-TCXO-clock-PPM-0-1-for-HackRF-one-GPS-Applications-GSM-WCDMA-LTE/173432677234?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)

and have just looked up the spec in the seller's listing: I thought it was 1ppm, but it's shown as 0.1ppm in the headline, and referred to as 0.1 - 0.5ppm in the description.  It's Rojon, but only half the price of those referred to earlier.  I wonder how much confidence you can have that 0.1ppm means anything like that accuracy, or that the £15 and £22 TCXO cans contain anything different to this £8 one?  The answer, of course, is "none".  Caveat emptor, again!

 Hi Dave,

 I had I a reply nicely typed up and waiting to go until I decided to hit the refresh whilst previewing my missive. Apparently, hitting the refresh button is a shortcut to sending replies to the bit bucket.  Whoops! I did it again (but not without copying  my text beforehand). There's no doubt about it, hitting refresh is a sure fire way to lose a nicely typed out reply...  :'(

 Apologies but you're gonna have to wait a little longer for a proper reply. I'm done with this klunky bug ridden system for today. I'll leave it till tomorrow (er, later today - it's already "tomorrow").

 Regards, Johnny
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on November 25, 2018, 06:16:11 am
Hi Johnny ,
Its does happen on many Blogs ,Ive found ,long and carefully typed responses can simply end up gone .
A very simple way to help prevent loss is to type into a text file on the desktop ,then once your done ,copy and paste to the Blog page . Alternatively before hitting send , copy and paste what you've written to a text file and save .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 25, 2018, 12:32:55 pm
 
Hi Johnny ,
Its does happen on many Blogs ,Ive found ,long and carefully typed responses can simply end up gone .
A very simple way to help prevent loss is to type into a text file on the desktop ,then once your done ,copy and paste to the Blog page . Alternatively before hitting send , copy and paste what you've written to a text file and save .


 Sensible advice. In this case, it's best to save the text before even taking a chance with the preview button (in my case, just in case I forget the lesson about refreshing the view being so terminal). I'm typing this into a text file rather than into the rather cramped reply box. I suspect this is probably what many of the longer established members do.

 Anyway, it was probably for the best. I was going to suggest converting the seemingly bi-phase half wave rectified 12v circuit on the PSU to full wave, forgetting that with the simpler (and cheaper if you discount the need for a doubling up of the transformer rating compared to that needed in the more efficient but complex push pull circuit) single ended drive smpsu topology, only half wave rectification can be used as I discovered to my chagrin, luckily without damage when I tested my hypothesis that this would give a small boost in voltage without the need to add a couple of turns to the 12v bi-phase secondary winding, along with a halving of the ripple voltage.

 I tested my adaption with the PSU fully connected up, voltmeter poised, eye on the wattmeter scale ready to hit the off switch should it go north of the 10W mark. Switching on showed a mere 2W reading as if the PSU had gone into current foldback due to an overload. The 5v was showing just 2.5 volts and the 12v lines, afaicr, less than 6 volts (possibly just 2 or 3 volts).

 Thinking I'd miswired the extra diodes, I removed the PSU to my 'bench' for a closer look but as far as I could tell from visual and electrical inspection, I had managed to create a full wave centre tapped bridge circuit exactly as planned so back it went into the sig generator for another test where it did the same thing.

 More curious now, I left the output disconnected to try again and observed some 21 volts on the 12v rails (the 5v was still its usual 5.48 and the wattage was still the 2 watts of earlier. Needless to say, I didn't stop and stare at this marvel of excess voltage and hit the off switch quick smart.

 What I'd seen as a rather curious abuse of a bi-phase secondary winding where the opportunity to use either a single winding to generate a centre tapped voltage doubled supply or else a missed opportunity to use the bi-phase winding to create a centre tapped full wave bridge circuit, turned out to be simply a means to allow all three rectifiers (the +5 and 12 and -12 volt rectifiers) to conduct on the same phase as the active single ended drive pulses. Lucky for me that my "Bull in a China Shop" approach hadn't resulted in a fatal mistake. :-)

 I realised my 'skoolboy howler' during my musings of the problem whilst waiting for the iron to warm up for the diode-ectomy. This led me to wonder whether replacing the extremely efficient 30A per diode element 45Vrrm rated diode on the 5v winding with a slightly less efficient SB340 (3A average 40Vrrm DO-201AD) I'd recovered from an old external HDD power supply would provide the slight lift on the 12v rails to give a little more than just a tenth of a volt's worth of postive offset range at the 20Vp2p into 50 ohm loads I'd been getting with the +12.35v/-12.7v rail voltages after the transformer mod. Since it looked like the component symbol printed on the PCB, I swapped out the giant 30&30A diode and mounted my prize diode in its stead.

 Retesting revealed a rather surprising boost of the 12v rails to +13.55 and -13.70 volts which proved sufficient to let me go +2.0v and -2.3 volts on the offset adjust without clipping. A rather ample margin for such a modest boost on the 12v rails. The maximum power consumption after the diodes have warmed to a more efficient operating temperature (takes about a minute or two from the 10.25 watt initial cold switch on state) is now just a whisker over the 9W mark.

 I reckon this final modification to the PSU is just about the optimum between its improved efficiency and the overall energy consumption, the vast majority of which results in raising the internal temperature of the generator. It can be reduced by another watt but this leaves you with no offset margin.
 
 For anyone else interested in modding the PSU for better efficiency and voltage stability on the 12v rails, it's sufficient to replace all three rectifier diodes on the outputs with SB340s all round. For those of a less nervous disposition, a nice finishing touch is to lift the transformer out to add a couple of extra turns to each end of the bi-phase secondary winding which serves the 12v rectifiers.
 
 This, of course assumes the obvious addition of the 47K resistor across the lower 10K resistor of the 5v sense network to raise the 5v (and the 12 volt rails tied to it via the transformer winding ratio) to 5.49v (still just within the +/- 10% Vcc spec for 5 volt logic chips).

[EDIT 20190330]

 I've since undone that transformer mod (removed the two turns from the 12v windings) and added a single turn over-wind on the bobbin, made up with 4 separate single turn windings in parallel for better coupling and minimum I sq R loss and leakage inductance to wire in series with the 5 volt diode to buck the transformer output voltage (effectively removing one turn from the 5v secondary winding).

 This forces the switching module to raise the 12v rails as it compensates for the effect of the lower transformer output to the 5v rectifier and smoothing circuit which drives the voltage feedback for all three rails. It's a far more elegant method to rebalance the voltage distribution between the regulated 5v rail and the "we'll take pot luck" turns ratio mediated voltage output level on the "Twelve Volt" plus and minus rails.

 Adding this single turn to buck the voltage on the existing 5v winding which lies beneath the HT windings, neatly avoids interference to any of the existing windings and their connections (very unlike the case with my first transformer mod) since it simply terminates directly onto a vacated PCB connection and the lifted out anode of the 5v rectifier diode.

 The only gotcha with this is that you may have to reverse the connections to achieve the buck winding state. When I tried this earlier today, that was exactly how it went -Sod's holds its sway as per usual. What made it a little more awkward for me was my choice of needlessly heavy gauge wire which obliged me to unsolder the transformer again in order to preform the ends after reversing the polarity in order to refit it back to the board.

 Just because there IS ample room on the bobbin, that's not a valid reason to try and fill the gap with heavy gauge wire when thinner and more flexible wire will be more than adequate to keep the I sq R losses vanishingly small anyway. It would have been trivial, given a more sensible choice of wire gauge, to reverse the buck winding connections without having to lift the transformer from off the PCB. Indeed, the whole mod can be done without removing the transformer at all if sufficiently flexible wire is used. If it hadn't been for the need to undo my earlier mod, I'd most likely have made a better choice of wire to begin with.

 Anyway, this alternative solution DOES work, and rather well at that! :) Before starting this modification work, I measured the voltages provided by the previous modifications (diode upgrades, the two turns add ons to the + and - "12v windings" and the 47k shunt of the voltage feedback potentiometer lower arm to raise the original 4.95v to 5.49v just to get a an extra boost on the 12v rails). The voltages were +5.46, -13.78 and +13.60 volts. After reverting the transformer to its original state and adding a single turn to buck the 5v secondary and removal of the 47K resistor, I then got the following voltages, +4.94, -12.98 and +12.83. I then fitted a 200K resistor to bump the +4.94v rail to a less marginal (for the 12v cooling fan) 5.07 volts which boosted the "twelve volt" rails to -13.29 and +13.13 volts which still provides a useful DC offset margin at the 20v p-p level.

 One final thing I can add before ending this edit, is that you can forget what I said about upgrading to 'medical grade' class II smpsu modules using transformers blessed with a proper foil shield layer as the ONLY effective solution to the problem of the half live mains 'touch voltage' and the risk of ESD damage to any fragile devices being tested.

 In the end, I realised that such ESD hazards still existed even with such medical grade' psus and after trying several schemes to cancel out this touch voltage whilst avoiding the use of an earth connection which would, as it does in the case of the FY6800, introduce troublesome mains earth loop interference, I finally admitted defeat in achieving such an impossible ideal and rather pragmatically, replace the IEC C8 connector with an IEC C6 (trefoil) connector just so I could link the zero volt rail via an 11K drain resistor to flatten down the 90vac half live mains touch voltage to a mere 500mV ac which nicely solves the ESD risk issue yet avoids the earth loop issue that stupid, stupid Feeltech have introduced into their FY6800 - Fools that they are!

[END_EDIT]


 Anyway, back to the point that Dave made regarding the TCXO upgrading options, I had been about to mention (as a result of my original transformer mod prior to my doomed bridge diode mod) that I'd changed my mind about hanging fire on ordering that £15.53 "50MHZ hifi TCXO 0.1ppm Ultra precision Golden Oscillator CLOCK power supply" with its JYEC TCXO (the object of my desires).
 
 It's a simple enough job to transplant the TXCO from the board onto the FY6600's main board to directly replace the original cheap 100ppm XO module and the little circuit board it came with won't be going to wast since I have several XO modules to hand that I can test on this board (I'll fit a set of gold turned pin sockets to the board to turn it into a plug in XO test rig).

 The order went in on Friday and I have an estimated 3 to 8 weeks delivery (12 Dec to 25 Jan). Just as well I'm not in a blazing hurry to upgrade this aspect of the FY6600-60M. :-)

 Regards, Johnny B Good
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 25, 2018, 03:38:51 pm

 Thirdly, if you feel the need to match the existing 50MHz 100ppm frequency reference to the counter's display resolution, then install a 50MHz 0.1ppm TCXO (if you're going to bother at all, why only take half measures with a mere 1ppm rated TCXO when you can get hold of a 0.1ppm ROJON part from a Chinese supplier on Ebay for as little as 15 or 16 quid?  :)).


I bought one of these not long ago:
https://www.ebay.co.uk/itm/External-TCXO-clock-PPM-0-1-for-HackRF-one-GPS-Applications-GSM-WCDMA-LTE/173432677234?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 (https://www.ebay.co.uk/itm/External-TCXO-clock-PPM-0-1-for-HackRF-one-GPS-Applications-GSM-WCDMA-LTE/173432677234?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)

and have just looked up the spec in the seller's listing: I thought it was 1ppm, but it's shown as 0.1ppm in the headline, and referred to as 0.1 - 0.5ppm in the description.  It's Rojon, but only half the price of those referred to earlier.  I wonder how much confidence you can have that 0.1ppm means anything like that accuracy, or that the £15 and £22 TCXO cans contain anything different to this £8 one?  The answer, of course, is "none".  Caveat emptor, again!

Hi Dave,

 That would require the addition of a 5 times pll multiplier since it's the all too ubiquitous 10MHz 0.1ppm TCXO that I kept bumping into in my search for a 0.1ppm 50MHz unit. That £15.53 JYEC TCXO on a handy test board is worth shelling out the extra 7 quid for imo in order to avoid the extra cost and work of adapting a 10MHz reference to the requirements of the FY6600 so, as I mentioned in my reply to Soundtec just now, I've got that module winging its way to me as I type.

 A point I was making in the original posting attempt that fell foul of the refresh button was my observing that every picture of a 0.1ppm TCXO I'd looked at showed a trimmer adjustment access hole in the can. Since I didn't observe any such hole in the cans of the 1ppm TCXOs I'd seen pictures of, I think one can safely conclude that if there is such a hole, it's got to be a 0.1ppm part.

 That discrepancy between the headline +/-0.1ppm and the wider +/-0.5ppm accuracy/stability figures is just a matter of the wider -10 to +60 deg C range compared to the less arduous room temperature range of 0 to 25 deg C.

 In the case of the part I've just ordered, I notice a degradation of temperature stability over the -10 to +60 deg C range to just +/-0.2ppm versus the more typically quoted 0.5ppm value. Hopefully, the TCXO module is actually as good as this. The internal temperature of the FY6600 is more likely to be 40 to 50 deg C rather than the 25 degrees C upper limit on its 0.1ppm rating and I can't see any easy way[1] of ensuring it stays at or just above typical room temperature.

 Since the degradation of temperature coefficient in this case would appear to be only an extra 0.1ppm rather than the more usually quoted 0.4ppm worsening, it shouldn't be too difficult to trim it to better than 0.1ppm at the elevated temperature in any case.

Regards, Johnny B Good

[NOTES]
 
[1]  I can see a hard way to achieve 'room temperature' operation for the TCXO which involves cutting a 47mm diameter hole in the base, fitting a slimline fan[2] and adding a deflector to divert the incoming fresh air straight towards the TCXO end of the main board. This would probably be a good thing to do regardless if only for the sake of everything else in the box but I suspect a tweak of the trimmer to compensate for the higher temperature will produce a result almost indistinguishable from that of the 0 to 25 deg C operational temperature range.

[2] Yep! A footnote to a footnote.  :)

 I just found a neat little 50mm square 10mm deep 12v 120mA cooling fan in an icecream tub marked "Fan Cooler Bits" that's been sat on a cupboard shelf in my 'Office' for probably the past two decades. A quick test with a 5v wallwart proves it will run reliably (and, of course, almost silently) at this low voltage and draws just under 43mA so won't be any strain for the under-utilised 5v rail. If anything, the extra 43mA on the 5v rail should provide a small but welcome boost to the 12v rail voltages.

 There is room between the back panel and the PSU board to mount this fan onto the base of the case but, just to present myself with a bit of a quandary, I also found a 60mm square 13mm deep cooling fan which only draws 35mA from the 5.15v wallwart despite its higher 170mA at 12v rating. Obviously, its larger size provides more airflow per mW but the only place it could be installed would be the top cover just over the area between the heatsink and the TCXO location. This would have the bonus of eliminating the complication of ducting but would spoil the top cover with a wire finger guard covering a 57mm diameter hole.

 This leaves me with the choice of style over function versus function over style - decisions, decisions. This is something I'll have to give some consideration to. Oh, and BTW, I found yet another 50mm square 10mm deep fan that draws just 28mA from the wallwart ( a mere  144mW) and seems to offer about the same CFM. I don't seem to be short of cooling fan options at any rate.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on November 27, 2018, 02:18:39 am
Hi Johnny,

I wasn't suggesting that you could use one in the FY6600, just alluding to the same item being on sale for wildly different prices from different suppliers.  As for the 10MHz one I bought for £8, I've tested it against RWM on 9996kHz and it comes in at 0.2ppm, which I'm not going to complain about, and I've had a look in the trimmer hole and the trimmer is there, so it's identical to the £18 version here:
https://www.ebay.co.uk/itm/TCXO-10MHz-10-000000MHz-0-1ppm-Ultra-precision-Crystal-Oscillator-DIY-AUD-GC1-XH/381746677180 (https://www.ebay.co.uk/itm/TCXO-10MHz-10-000000MHz-0-1ppm-Ultra-precision-Crystal-Oscillator-DIY-AUD-GC1-XH/381746677180)

I've also put a piece of kapton tape over the can, so now I've got the golden version as well!  ;D

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 29, 2018, 03:36:22 am
Hi Johnny,

I wasn't suggesting that you could use one in the FY6600, just alluding to the same item being on sale for wildly different prices from different suppliers.  As for the 10MHz one I bought for £8, I've tested it against RWM on 9996kHz and it comes in at 0.2ppm, which I'm not going to complain about, and I've had a look in the trimmer hole and the trimmer is there, so it's identical to the £18 version here:
https://www.ebay.co.uk/itm/TCXO-10MHz-10-000000MHz-0-1ppm-Ultra-precision-Crystal-Oscillator-DIY-AUD-GC1-XH/381746677180 (https://www.ebay.co.uk/itm/TCXO-10MHz-10-000000MHz-0-1ppm-Ultra-precision-Crystal-Oscillator-DIY-AUD-GC1-XH/381746677180)

I've also put a piece of kapton tape over the can, so now I've got the golden version as well!  ;D

Regards,
Dave

 Actually, Dave, that would have been a better idea. I could have used Arthur Dent's technique of using an NB3N502 14 MHz to 190 MHz PLL Clock Multiplier to generate the 50MHz clock from the 10MHz OCXO that he'd installed into his Fy6600[1]. In my case, substituting the OCXO with the less power hungry 0.1ppm 10MHz TCXO instead.
 
 I've taken another IR thermometer survey of the main board, in particular the area adjacent to the 50MHz clock chip packed out with three linear voltage regulator chips raising the board temperature to circa 70 deg C, leaving the clock chip, as best as I can determine, at a rather toasty 50 deg C. My airflow deflector idea just ain't gonna fly in this case.

 Closer inspection of the picture of what I've ordered  suggests a circuit board size of 50 by 35 mm which will sit nicely over that 28mA @5v 50 x 50 x 10 mm fan that I plan on fitting into the bottom of the case in the space adjacent to the main board between the PSU and the rear panel. It looks like I won't be recycling that little PCB as a test mount for other XO clock generators after all since I've decided that, in this case, it'll be easier "To bring Mohamed to the Mountain".

 JOOI, I'm looking at a 3N502 chip right now on Ebay for £3.49 delivered from a London based warehouse <https://www.ebay.co.uk/itm/NB3N502DG-Frequency-Multiplier-8-Pin-SOIC/173385949750?epid=648417593&hash=item285e9ba236:g:psUAAOSwxDtbNlVW:rk:3:pf:0>

(https://preview.tinyurl.com/y8mosmkv (https://preview.tinyurl.com/y8mosmkv)).

 Of course, now that I've ordered the 50MHz part, the die is set and there's little point in my ordering a 3N502 frequency multiplier chip. However, since a 10MHz 0.1ppm TCXO is a damn sight cheaper to buy than a 50MHz TCXO, plus the fact that it's better to relocate the replacement TCXO away from the heat of those three voltage regulators anyway, for anyone else contemplating a similar TCXO upgrade, the 10MHz TCXO plus freq multiplier chip is not only cheaper, it's also the better option imo even if you aren't planning on fitting a small cooling fan.

 Nice touch BTW, using kapton tape to 'upgrade' your TCXO to a 'Golden' version. :-)

 I noticed that the 10MHz TCXO you linked to is from the same trader that sells those three 50MHz TCXOs I mentioned earlier, ranging from £17.90 (9p cheaper than that 10MHz example you mentioned) to a top end of 22 quid for one in a square can. When it comes to 50MHz 0.1ppm TCXOs on Ebay, it's a very small world indeed.

 I had to google "RWM". I'm more familiar with WWV which operates 4KHz above RWM's frequency allocations at precisely 5, 10 and 15 MHz with the additional frequencies of 2.5 and 20 MHz. I've used the 10MHz WWV signal in the past (some 20 odd years ago now) to calibrate my Kenwood TS140S HF transciever which I recently rescued from a damp and neglected basement radio shack come workshop.

As far as I can tell, its frequency calibration appears not to have suffered in spite of the decades of neglect but I no longer have an external antenna by which to tune into the 10MHz WWV signal to confirm this. Even with a good antenna, it wasn't always possible to get a good enough signal from WWV to perform such calibration checks.

As far as I remember, I only had to recalibrate it the once shortly after I'd purchased it. Aside from the initial warm up from cold, it remained within one or two hertz of the 10MHz signal, demonstrating remarkable frequency stability for a late 80s example of radio technology.

 Regards, Johnny B Good
 

[NOTES]

[1] Reply #151 Posted just over a year ago (page 7).

[2] I've just had another look at the description of this "oscillator clock power supply". The dimensions given are "size: 20.8 x 13.2 x 15mm" which is clearly a nonsense unless they're that of the bare TCXO itself which, now I think about it, seems more likely. Double checking against the 74HC04D chip on the board to get a sense of scale confirms I was in the ball park with my original size estimate.

 My new estimate of the board's dimensions are now ever so slightly revised downwards to 45 by 30 mm which gives me a touch more leeway on exactly how I'll be mounting it over the fan to catch the incoming airflow without creating unwanted turbulence near the fan blades (which is a sure fire way to drastically reduce the efficacy of these high volume/low pressure axial fans).

 I'll want to provide ducting to divert the incoming air past the oscillator board and towards the front in order to minimise losing too much of that hard won cooling air straight out of the rear panel vents which I don't want to block off. I need all the exhaust venting cross sectional area I can recruit to exhaust the warmed over air, hence the ducting so that what does escape via the rear panel vents has already managed to pick up and carry away some heat from the innards of the box.

 I've got a few more weeks to install the fan before that TCXO board arrives anyway so I might as well do some testing to make absolutely sure there's not going to be a problem in stealing power from the 5v rail to drive the fan before I start cutting holes in the bottom of the case. I rather doubt there will be a problem but you can't take this stuff for granted. The most likely side effect I'm expecting is a slight boost in the 12v rail voltages which, in moderation, will be no bad thing in this case.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 29, 2018, 11:04:21 pm

=====bulk of previous reply snipped====

[NOTES]

[2] I've just had another look at the description of this "oscillator clock power supply". The dimensions given are "size: 20.8 x 13.2 x 15mm" which is clearly a nonsense unless they're that of the bare TCXO itself which, now I think about it, seems more likely. Double checking against the 74HC04D chip on the board to get a sense of scale confirms I was in the ball park with my original size estimate.

 My new estimate of the board's dimensions are now ever so slightly revised downwards to 45 by 30 mm which gives me a touch more leeway on exactly how I'll be mounting it over the fan to catch the incoming airflow without creating unwanted turbulence near the fan blades (which is a sure fire way to drastically reduce the efficacy of these high volume/low pressure axial fans).

 I'll want to provide ducting to divert the incoming air past the oscillator board and towards the front in order to minimise losing too much of that hard won cooling air straight out of the rear panel vents which I don't want to block off. I need all the exhaust venting cross sectional area I can recruit to exhaust the warmed over air, hence the ducting so that what does escape via the rear panel vents has already managed to pick up and carry away some heat from the innards of the box.

 I've got a few more weeks to install the fan before that TCXO board arrives anyway so I might as well do some testing to make absolutely sure there's not going to be a problem in stealing power from the 5v rail to drive the fan before I start cutting holes in the bottom of the case. I rather doubt there will be a problem but you can't take this stuff for granted. The most likely side effect I'm expecting is a slight boost in the 12v rail voltages which, in moderation, will be no bad thing in this case.

 Apropos of installing the whole "oscillator clock power supply" PCB into the case as a sort of airflow deflector rather than just transplant the actual TCXO onto the main board in place of the original XO chip, I completed the electrical tests with both the 28 and 43 mA at 5v fans to check the effect on voltages and power consumption.
 
 As expected, the 12v rails enjoyed a modest 30 to 40mV boost with the 28mA fan whilst the 5v rail dropped about 10mV with the overall consumption rising by just under half a watt to the 9.5W mark when driving 50 ohm loads at the 20MHz 20v P2P amplitude setting (maximum consumption conditions). Thus encouraged, I've cut out the hole and fitted the fan exactly as I described in NOTE 2 above (except, of course, for the fan ducting).
 
 With the lid perched loosely to allow convenient test access, the temperatures do appear to have dropped a good 10 deg C all round despite a lot of the incoming air getting blown straight out of the rear panel vents. I've now clipped the lid into place to seal up the gaps and, for the time being, I've taped over the rear vent slots to increase the cross flow air circulation over the main board.
 
 The "Hot Spots" on the top of the case are now merely perceptibly warm spots and even the underside hot area is now significantly cooler than before and I'm now inclined to permanently block the rear vents and open up the RHS vent slots to increase the airflow across the main board rather than faff around with additional fan ducting. Those rear vent slots are now more trouble than they're worth (and they were pretty worthless to begin with imho).
 
 I'm still planning on mounting the oscillator board over the fan to both keep it at little more than ambient and to act is a deflector to direct the incoming air towards the front panel. I think this is likely to prove just as effective a solution as the more fiddly ducting idea I'd had to prevent the rear vents from exhausting incoming cooling air straight out the back.
 
 It can be all too easy to overthink things when trying to find an optimum solution. Initially, it seemed a shame not to put the rear vent to good use but they were a horrible half hearted exercise in passive ventilation to start with, being as they are in a far from ideal location, especially considering the built in tilt to the case before it's made even worse by being propped up by the pull out front support stand.
 
 The kindest thing I could do after addressing the woefully inadequate passive ventilation with a cooling fan was to block this vent and look to improving the existing right hand side vent (the LHS one is perfectly fine as it is). However, I'll deal with that when I finally get hold of the oscillator board.
 
 As things stand right now, simply adding a  five volted 50mm fan and blocking the rear vent slots has considerably reduced the internal temperatures so yet another upgrade that's well worth adding to the list. There's no need to be concerned about 'fan noise' since it's barely audible against the louder fan noise of the Siglent SDS1202X-E DSO which is whisper quiet just as had been remarked upon by most, if not all, of the reviewers who'd checked it out.
 
 IOW, I had to shut the Siglent down before I could ascertain the level of fan noise coming from my modified FY6600. Even then I had to pick it up to place it close to my ear before I could hear any noise. Unless every other bit of kit in your workshop is passively cooled, you'll be hard pushed to detect fan noise from the FY6600 (assuming, of course, that you haven't used the crappiest 50mm fan from your Junk Box collection).
 
 Now that I've had it running for a good half hour or so since I clipped the lid back into place, I can no longer detect any warm spots other than on the underside of the case. That, I have to say, is a remarkable improvement for a relatively simple modification. Opening up the RHS vent slots as a final touch should noticeably improve the effectiveness of this forced ventilation modification to the benefit of significantly improved reliability and an extended service life.
 
 It looks like it's going to be several weeks before I'll have anything new to report so I'll take this opportunity to wish everyone still monitoring this thread a Merry Christmas and a Happy New Year. :-)
 
Johnny B Good.
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on November 30, 2018, 05:44:57 pm

====snip====
 
 Now that I've had it running for a good half hour or so since I clipped the lid back into place, I can no longer detect any warm spots other than on the underside of the case. That, I have to say, is a remarkable improvement for a relatively simple modification. Opening up the RHS vent slots as a final touch should noticeably improve the effectiveness of this forced ventilation modification to the benefit of significantly improved reliability and an extended service life.

====snip====
 

 One final final post for this year (unless that oscillator board arrives early). I couldn't resist taking another look at improving the RHS vent slots this afternoon. Although there is the potential to open them up without altering their external appearance, the job looked just too fiddly and time consuming to be worth all that effort, not to mention the risk of spoiling the appearance of the case, so I decided against it.

 However, I did spot the gaps where the front panel clips onto the bottom half of the case so, with careful application of a small file, I bevelled the inside of the RHS engagement slot to increase the effective CSA without obviously altering its external appearance and used BluTak(tm) to seal the gap in the LHS engagement slot.

 This represents a compromise between riddling the base under the opamps with a dozen or so 4mm holes to encourage additional airflow under the main board as I'd suggested in an earlier post and improving the existing airflow accidentally provided by the gap in the RHS securing slot.

 Having applied BluTak(tm) to seal up the LHS securing slot in order to favour the improved RHS with more airflow, you might well ask why I didn't block or partially block the LHS vent slots to favour the RHS slots. Well, the answer is that you can overdo this balancing act when restricting airflow in one part without reducing the restriction elsewhere since the increased back pressure can significantly reduce the efficacy of a high volume low pressure axial fan to such an extent as to become counter-productive not just to the total flow of air through the whole box but also to the targeted areas of concern.

The LHS vents might be letting out cool air, seemingly in an unproductive fashion but it's still allowing a higher speed of airflow within the confines of the box to encourage better heat transfer to the circulating air some of which heat energy, whilst diluted, will still escape via the LHS at a reduced temperature whilst the air exhausted via the RHS vent will be carrying more energy as a result of its higher temperature, courtesy of the improved energy transfer from the faster air speed within the box around the heatsink and the main board and its components.

 One might also wonder why I agonised over drilling a dozen 4mm holes in the base after cutting out a whacking great 47mm diameter hole for a cooling fan. Well, TBH, the 47mm hole is an inescapable consequence of blessing the box with a much needed active cooling system, aka, a fan and, as such, is as much a statement as a necessity whereas a bunch of 4mm holes, let's face it, just looks a little naff.  :)

 I reckon I've done about as much as I can to reduce component temperatures short of lending the case a 'Swiss Cheese' look. Installing the oscillator board (once it finally arrives) over the fan location at a jaunty angle to better deflect the airflow towards the front panel should offer a further, if modest, improvement in the efficacy of my active cooling modification.

 Before I forget, I think it's worth noting that despite the optical illusion, that little heatsink is actually square (19mm by 19mm in my case). Whilst I'd had the main board out to modify the retaining slot, I'd thought to check the dimensions with a view to reorientating it to favour the anticipated cross flow of air.

 When I'd first refitted it after the opamp upgrade, I'd replaced it in its original orientation with the fins aligned front to back, thinking it might not completely cover the opamps if I did otherwise (yet another ASS U ME moment). It now sits on the board with the fins parallel with the front and rear panels which should improve heat transfer under the new regimen of my active cooling system.

 Indeed, I think it can even be fitted at +/-45 deg without fouling anything and still cover the opamps if that gives a better alignment with the airflow direction wherever you might choose to locate a cooling fan. Obviously, you need to determine or guestimate which direction the airflow will be taking in order to make an effective choice but at least you have room for manoeuvre to maximse the heatsink's efficacy. In my case, I've simply guestimated that, on balance, an east west orientation rather than the original north south one is the better choice for my setup.

 Anyhow, that's the latest development for the time being. As modifications go, it's been one of the most satisfying ones I've done so far (it's right up there with the opamp upgrade with the PSU mods not too far behind - all vital and worthwhile improvements imo).

 Not only does this mod improve reliability and extend component life, it's also an essential part of the 50MHz clock oscillator upgrade since it should hold the temperature of the TCXO to within a degree or two above room ambient rather than have it subjected to 50 or 60 degree temperatures. There'll be virtually no warm up delay from switch on as a result which is a nice touch to my mind.  :)

 Well folks, that's all for now. Have a Merry Christmas!

 Johnny B Good
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on November 30, 2018, 11:14:00 pm
I lost track of this thread long ago.  Is there FOSS  FW available that can be loaded on an STM32F103 that  will make borked units work when installed on the front panel?  I'll buy a socket and program some chips if it can be done.  Mostly because I despise F***Tech.

My last recollection was that fremen was using a blue pill, but it required a PC to control it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tsman on December 01, 2018, 03:18:34 am
Is there FOSS  FW available that can be loaded on an STM32F103 that  will make borked units work when installed on the front panel?
I don't think there is anything. fremen67 hasn't been around for months either so no source or newer builds for that avenue.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on December 01, 2018, 03:45:35 am
I lost track of this thread long ago.  Is there FOSS  FW available that can be loaded on an STM32F103 that  will make borked units work when installed on the front panel?  I'll buy a socket and program some chips if it can be done.  Mostly because I despise F***Tech.

My last recollection was that fremen was using a blue pill, but it required a PC to control it.

 I don't think any more progress was made on that front I'm afraid. I've read the whole of this thread twice now plus some reprising of some of the earlier hardware related sections. Once the problem 'went away' with the later production models from Feeltech, I lost interest in what was obviously a doomed firmware repair project due to the uncrackable protection that prevented retrieval of the binary code for reverse engineering a fix.

 I bought mine in the first week of November and it arrived on the 9th sporting the 3.3 version of firmware which seems to have addressed several issues aside from the major bug that caused it to brick itself as yours did. Fingers crossed that version 3.3 doesn't have a similar bug quietly waiting in the wings for just exactly the right moment to take centre stage to wreak similar havoc and mayhem.

 I can entirely understand your attitude to Feeltech and I sympathise but, as others have pointed out, when it's this cheap, cash strapped hobbyists are going to take a punt on it, especially if they've read through this EEVblog thread to discover that the fatally flawed firmware version is now ancient history.

 It seems, in view of the warranty voiding mods you'd already applied, that the best you can hope for is to try and sweet talk Feeltech into sending you a replacement front panel at cost price by way of a compromise as a gesture of good will since the fault seems to have resulted from a fatal flaw in the firmware they had supplied it with. Other than that, you're pretty well stuck with a mid priced paperweight if the PC based work around doesn't appeal.

 Regards, Johnny B Good
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 01, 2018, 01:26:02 pm
Thank you.  I couldn't face reading 60 pages.  I'd mostly dropped out by page 20 or 30 as I did not have a programmer or blue pill.  But I do now.

I got a replacement panel with V 3.1, but not by "sweet talk".  But at least 4 others did not.  I'd like to help them.  In a classic twist of irony I got a front panel  after I had purchased a Keysight 33622A from the Keysight eBay store.

I offered to do a review of the FY6600 against the 33622A and attached some 8560A spectrum analyzer plots.  But that did not result in the other 4 members with 3.0 units getting relief.  Nor did a 2nd less friendly approach.  So it's time for me to carry through with what I said I'd do if they did not supply new FPs to the other 4.  It will likely prove *far* more expensive than sending out 4 FPs.

If we have the bus protocol worked out I ought to be able to write the front end UI part.  It would be a good warm up exercise for writing FOSS DSO FW for Zynq based scopes (e.g. the Instek 2000E and the Siglent 1000X-E).  And  a pleasant diversion from reverse engineering the DSOs which are rather more complex.

I've sent a PM to fremen67.  My concern was that it might have already been done.

Subsequent to my V 3.0 adventure I bought a very nice set of bench gear, mostly early 90's HP  gear.  I'm 65 and finally gave myself permission to spend the money.  But I have many painful memories of when I couldn't afford test gear.  My first good scope was a Dumont 1060, a very nice dual trace analog scope which I bought from Tucker Electronics in 1991 for $325 with a 30 day warranty.  The horizontal sweep died about day 35.  Eventually I traded a couple of spare 144 MB ESDI drives for a wonky 465 which worked well enough to let me fix the Dumont which then let me fix the 465.

After that moves and the turmoil of life left me without a bench setup.  I was starting to rebuild a bench as all my other gear has died of old age and will require repairs.  But I was still in the penny pinching mode I was taught growing up so Rigol DSO, F***Tech AWG, Tenma 4.5 digit DMM etc.  But several friends dying and in particular watching my brother in-law deteriorate from Parkinson's dramatically over 9 months changed my attitude.  Though my goals are still the same,  good quality low cost T&M gear.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on December 01, 2018, 10:23:28 pm
Thank you.  I couldn't face reading 60 pages.  I'd mostly dropped out by page 20 or 30 as I did not have a programmer or blue pill.  But I do now.

I got a replacement panel with V 3.1, but not by "sweet talk".  But at least 4 others did not.  I'd like to help them.  In a classic twist of irony I got a front panel  after I had purchased a Keysight 33622A from the Keysight eBay store.

I offered to do a review of the FY6600 against the 33622A and attached some 8560A spectrum analyzer plots.  But that did not result in the other 4 members with 3.0 units getting relief.  Nor did a 2nd less friendly approach.  So it's time for me to carry through with what I said I'd do if they did not supply new FPs to the other 4.  It will likely prove *far* more expensive than sending out 4 FPs.

If we have the bus protocol worked out I ought to be able to write the front end UI part.  It would be a good warm up exercise for writing FOSS DSO FW for Zynq based scopes (e.g. the Instek 2000E and the Siglent 1000X-E).  And  a pleasant diversion from reverse engineering the DSOs which are rather more complex.

I've sent a PM to fremen67.  My concern was that it might have already been done.

Subsequent to my V 3.0 adventure I bought a very nice set of bench gear, mostly early 90's HP  gear.  I'm 65 and finally gave myself permission to spend the money.  But I have many painful memories of when I couldn't afford test gear.  My first good scope was a Dumont 1060, a very nice dual trace analog scope which I bought from Tucker Electronics in 1991 for $325 with a 30 day warranty.  The horizontal sweep died about day 35.  Eventually I traded a couple of spare 144 MB ESDI drives for a wonky 465 which worked well enough to let me fix the Dumont which then let me fix the 465.

After that moves and the turmoil of life left me without a bench setup.  I was starting to rebuild a bench as all my other gear has died of old age and will require repairs.  But I was still in the penny pinching mode I was taught growing up so Rigol DSO, F***Tech AWG, Tenma 4.5 digit DMM etc.  But several friends dying and in particular watching my brother in-law deteriorate from Parkinson's dramatically over 9 months changed my attitude.  Though my goals are still the same,  good quality low cost T&M gear.

 Glad to oblige, I'm probably the only member who's read the whole 69 pages (now 70 thanks to my recent efforts) within the past fortnight or so who could answer your question off the top of their head.  :)
 
 So you did manage to get a replacement panel then. Pity about the other four members who've had to go without or use the PC control software work around. I'm interested in how you finally managed to get Feeltech to 'do the right thing' (or did they?). I can imagine the irony of fixing your cheap FY6600 after spending some $5K plus on an all singing all dancing Keysight AWG.

 Curiosity got the better of me and I found a review of the 33622A. I was rather surprised at just how small it was (not all that much bigger than the FY6600 as far as I could make out from the pictures). Obviously better made and a significantly more substantial piece of kit but quite bijou just the same.

 I can quite understand the appeal of Feeltech's "Poor Man's 33622A" with its order of magnitude lesser specification at around a two orders of magnitude cheaper price point aimed at cash strapped hobbyists who can work around the lack of the refinements of a 5 grand AWG. I think Feeltech know their market demographic far far better than it knows itself.

 If I had to describe Feeltech's marketing strategy using a simple to understand comparison, I'd say they're rather like a realtor (estate agent) specialising in fixer upper (run down) properties located amongst prime housing stock (up market areas), where the idea is not to waste money bringing the property up to the standard of its surroundings, an investment you'll have difficulty in recovering because you've excluded the wider market demographic, but to leave it open to a wider market of first time buyers trying to get on the property ladder who can see it as a low price ticket into an upmarket area.

 It's just a pity that they don't quite understand the value of good customer relations (in particular the notion of 'Good Faith' and the concept of 'Good Will'). Whatever you have in mind to effect an attitude adjustment at Feeltech, I wish you all the best success.

 It's not exactly clear but I assume your offer to review the FY6600 against the 33622A was to Feeltech rather than Keysight (the other way round wouldn't make much sense imo - Keysight, I imagine, would regard such a comparison as an insult, and one which would dent their sales figures). If Feeltech didn't jump at the chance of such a comparative review, they've either not got a customer relations/marketing department or else one that's totally oblivious to the value of such a priceless PR/marketing exercise.

 Interesting that you still want to write a UI from scratch for that FY6600 in spite of what's gone on and after all this time. I'm guessing, in part at least, that you're trying to spite Feeltech for their lack of support. I do hope you succeed in this FOSS project.
 
 However, you do realise that this will benefit Feeltech more than it will you since it will expand its appeal as a poor man's Keysight AWG even more. Still, a challenge is a challenge I suppose (and those four luckless members will no doubt offer profuse thanks for your efforts). Remember what I said about Feeltech knowing us better than we know ourselves? Well, I rest my case.  :)

 With regard to treating ourselves after a lifetime's frugality, I understand totally. Witness my blowing a whole £365 on a brand new SDS1202X-E DSO just the week before I then blew a whole £75.66 on that Feeltech AWG. Spending that sort of cash on test gear was something I'd have never dreamed of doing before. It's a whole new ball game now!  ;D

 I'm now in my late 60s (I have to recalculate my age from the current year just to keep track - the novelty of birthday celebrations wore off decades ago) and it's finally dawned on me that I might as well "spend the children's inheritance" on myself rather than let them squander it on smart phones, smart TVs and other such trash - they're all well enough off to manage from just the sale of the house as 'our final parting gift' once the missus and I have popped our clogs.

 Like you, I want good/serviceable quality T&M gear at the less than obscene, eye wateringly high prices still surprisingly being commanded by the Likes of Tektronix and Keysight. I enjoyed your tale of using a wonky 465 to repair that Dumont scope in order to fix up the 465. It reminds me of the sort of things I used to do and it demonstrates that perfection in T&M gear isn't as important as knowledge and experience and a proper understanding of the limitations of the less than perfect test gear you already possess or can aspire to.

 As if to demonstrate that principle of "boot strapping" a repair using 'damaged goods' (and getting back on to the topic of improving my FY6600), I've been observing a rather curious variation in the wattage readings of the AWG's power consumption which I suspect may be due to one or more of the smoothing caps in its PSU board.
 
 The readings during the past few days since I fitted the cooling fan have varied from just over the 9 watt mark to a gnat's dick short of the 10 watt mark on the mirror backed 100W scale on my Metrawatt analogue wattmeter (around a 6 to 7 percent variation).

 Switching PSUs don't respond to mains voltage variations in the way that analogue PSUs do. Indeed, I wouldn't expect to be able to observe any variation whatsoever even if it varied between 200 and 265 volts, let alone the typical 239 to 246 volts we experience at this location, so I know that it has to be caused by changes taking place inside the box.
 
 Since I've got the AWG set up for 20MHz 20vp2p driving 50 ohm loads with my DSO hooked up in order to monitor the output and nothing has changed this configuration during all the time I've been monitoring the power consumption, my number one suspect is the PSU board with the main board and front panel as secondary suspects (I can't completely rule them out) and caps are the most likely culprit for such subtle strangeness in smpsu behaviour - I've got to make a start somewhere.

 I've built up a nice little collection of fine looking caps salvaged from scrapped MoBos over the years but, despite having no comebacks from repairs to PC MoBos using such recovered caps, there's still the possibility of the odd one or two bad ones hiding amongst all the good so I do need to test my most suitable candidate replacement caps to avoid my repair attempt making things worse.

 It's rather lucky then that I happen to have a 'scope and a sig gen on hand to perform some basic ESR tests to weed out any duds from my collection of salvaged capacitors before I use them to 'improve' the PSU board.  ;D  If I'd had another sig genny to hand, I could've tested the caps in situ and perhaps avoid swapping them out for testing later but, as it happens, I don't, so the job has to be done this way.

 You may well ask why I don't suspect the last item I'd added as extra loading on the PSU and the answer is that the fan has never faltered and when I do stall it to see whether it has any effect on the wattage reading, all I can observe is a barely perceptable increase of no more than a quarter at most of the slow variation I've witnessed so far (plus, I've had a notion that it had been doing this even before I added the fan). If a cap change makes no difference, then I'll have to test the PSU board with a resistor dummy load before I can cast my suspicions further afield.

 There's even an outside chance that this might be 'normal behaviour' for this AWG unlikely as that seems (it's Feeltech, so who knows what's possible?). However, I can't imagine too many of Feeltech's customer demographic will even have an analogue wattmeter or an expensive bench wattmeter capable of measuring in increments of 10mW or better in order to observe such subtle power consumption behaviour (analogue wattmeters are rarer than unicorn droppings as of over a decade ago), so I don't expect anyone here to pipe up with a similar observation even if they wanted to test for it with their "Kill-A-Watt meters" since a digital readout to one tenth of a watt accuracy will make such subtle variations quite hard to distinguish from the "dance of the digits" typically performed by such plug in energy consumption meters.

 Still 'n' all, if anyone is intrigued enough to try and repeat my observations, what I've observed has been a slow variation between, in my specific setup, just over the 9 watt mark increasing slowly and, as far as I could ascertain, smoothly to just short of the ten watt mark over a period of an hour or more with no sudden jumps before going the other way after perhaps an hour or so at the 9.9 watt level. I'd estimate a variation of around 750mW, roughly a 7% variation on a nominal 9.5W load. It's only a small variation but I can't see any obvious reason why such a variation should exist at all.

 Clutching at straws, assuming the FPGA comprises mostly of NMOS logic rather than CMOS, it's just possible that the average current consumption might be being modulated by the processing of a 20MHz sine wave at the 20vp2p level setting but I've not been able to find sufficient detail about the gate technology actually used in a modern day FPGA so that's just an educated guess with no hard evidence to support such a hypothesis. With any luck, a recapping of the PSU board may solve this riddle anyway.  :)

 Regards, Johnny B Good

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 02, 2018, 12:36:14 am
I sent F***Tech 4 photos taken of the screen of an HP 8560A SA of the output of the 33622A and the FY6600 without identifying which was which.  I deliberately chose the output levels so that they looked almost identical.

The 33622A was used from Keysight's eBay store, so not as much, but still 30X the 6600.  But also 120 MHz rather than 60.

F***Tech told me I had lifetime support and similar BS for about 6 months without actually doing anything about the problem.

Not too sure that FOSS FW for the 6600 will help F***Tech.  Relative to a DSO the FPGA code is simple.  So writing a complete FOSS FW suite might well lead to a lot more competition.  To date I've spent over $1k setting up for the DSO FW project.  Right now I'm debating whether to also get a 1102X-E now or later. I already have an Instek GDS-2072E for testing. But long experience has convinced me that writing and testing SW on multiple platforms in 50-100 line increments avoids lots of bugs and other problems..

In a JDS6600 thread, a poster purporting to be with JDS said that they hired the guy who developed the F***Tech AWG who with another member of their staff designed the JDS6600.  Interestingly, the FY6600 uses a DAC and the JDS6600 uses an R2R ladder.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on December 02, 2018, 04:37:39 am
I sent F***Tech 4 photos taken of the screen of an HP 8560A SA of the output of the 33622A and the FY6600 without identifying which was which.  I deliberately chose the output levels so that they looked almost identical.

The 33622A was used from Keysight's eBay store, so not as much, but still 30X the 6600.  But also 120 MHz rather than 60.

F***Tech told me I had lifetime support and similar BS for about 6 months without actually doing anything about the problem.

Not too sure that FOSS FW for the 6600 will help F***Tech.  Relative to a DSO the FPGA code is simple.  So writing a complete FOSS FW suite might well lead to a lot more competition.  To date I've spent over $1k setting up for the DSO FW project.  Right now I'm debating whether to also get a 1102X-E now or later. I already have an Instek GDS-2072E for testing. But long experience has convinced me that writing and testing SW on multiple platforms in 50-100 line increments avoids lots of bugs and other problems..

In a JDS6600 thread, a poster purporting to be with JDS said that they hired the guy who developed the F***Tech AWG who with another member of their staff designed the JDS6600.  Interestingly, the FY6600 uses a DAC and the JDS6600 uses an R2R ladder.

 I'm quite surprised F***Tech didn't gift you a new AWG with the latest firmware for you to review alongside of the 33622A. Any company with a functioning marketing division wouldn't have let such an advertising opportunity slip through their fingers like that.

 BTW, the penny has only just dropped regarding your use of F***Tech.:) At first I just thought you were avoiding the use of their name to signify your reluctance to give it the "Oxygen of Publicity" but I guess you're simply expressing an expletive variation where the F*** is an anagram of FCUK (another company where their Branding division realised they could create a suggestive and memorable acronym from the initial letters of their company name, "French Connection UK").

 Sounds like you bought the 33622A for around half price. Here in the UK, RS and Farnell/Element14 are selling it for £5854.80 after the VAT is added on, some 77 times more than I paid for the FY6600-60M. JOOI, I checked Newark element14's one off price which was $6,856.00. I've no idea whether that was a tax paid price or not but I'd seen more than enough to make my eyes water (only metaphorically you understand - I'm not made of money so there's no way I'm going to spend 77 times more for a box that's by volume no more than 50% bigger).

 They say it's money that makes the world go round. If that's true, all I can say is that Keysight Technologies seem to be going above and beyond in keeping the world in a spin (mind you, Tektronix are no slackers in this endeavour either).

 I'll take your word on the simplicity of coding a FPGA. My coding expertise only extends to BASIC and Z80 assembler and I haven't done any coding since the mid 80s. You might want to put off getting the Siglent till later (and maybe pick the SDS1202X-E instead ;D).

 There's a damn good reason as to why the JDS6600 is cheaper (just!), the lack of a dedicated 14bit high speed DAC with laser trimmed resistors in its ladder network to maintain monotonicity throughout the whole range of sample values, is its downfall. I've seen the youtube review showing the artefacts on its sine wave output as a result of this nasty bit of cost cutting.
 
 There's cheap and then there's so cheap it not only can't be any good, it actually isn't any good. The FY6600 falls into the former category whilst the JDS6600 is most firmly stuck in the latter.

 Mention of 'interesting facts' raises the question as to why a seven thousand dollar, less a bit of pocket change, AWG comes with only a 2ppm XO as standard with a 0.1ppm OCXO as an optional upgrade. At that price point you'd expect to see a 0.1ppm TCXO as standard with an option to upgrade to a 3ppb OCXO at the very least. In fact, at a factory fitted option price of $715 why isn't the OCXO a 3ppb rated one? It seems, on that basis, that my 20 dollar 0.1ppm TCXO board is too good a bargain to be true. I sincerely hope that's not the case. BTW, do you happen to know which timebase option is installed in your 33622A? You may have got a better bargain than you'd thought.

 One final item I feel is worth mentioning, in view of my earlier ramblings about the anomalous power consumption readings I'd noticed in recent days, is that the problem has definitely progressed in that the average power consumption has increased ever so slightly with it spending more time now consuming exactly 10 watts. It now looks more and more like a mundane crappy PSU smoothing cap issue than the result of some rather exotic anomaly in the main and front panel boards.
 
 I guess it's time I stopped talking about testing the caps and actually get some testing done before it's too late and I'm left with no choice but to fit untested replacements.

 Regards, Johnny B Good

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 03, 2018, 09:22:25 pm
I'm surprised you didn't catch the F***Tech allusion sooner.

I was quite surprised that I offered to do several thousand dollars of consulting and marketing for under $400 and they ignored it.  That's when I started referring to them as F***Tech.

It's really easy to store corrected coefficients at final test.  But you have to care.  Why do you rate the JDS below the F***Tech?  I've not seen a good comparison, despite a number of people in this thread having both.

The 33622A is the only one of my HP instruments that does not have the OXCO option.  But as I'm about to hook everything to a GPSDO it shouldn't matter.

Subsequently I saw Keysight offering a 33622A for about $2800.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on December 04, 2018, 04:04:17 am

====snip====

 One final item I feel is worth mentioning, in view of my earlier ramblings about the anomalous power consumption readings I'd noticed in recent days, is that the problem has definitely progressed in that the average power consumption has increased ever so slightly with it spending more time now consuming exactly 10 watts. It now looks more and more like a mundane crappy PSU smoothing cap issue than the result of some rather exotic anomaly in the main and front panel boards.
 
 I guess it's time I stopped talking about testing the caps and actually get some testing done before it's too late and I'm left with no choice but to fit untested replacements.


 Following up on the above, I picked out a couple of 16v 470μF caps to replace the 220μF ones used by the 12v rails and a nice pair of 6.3v 1500μF (actually proved on testing as 1860 and 1920 μF) from my salvaged caps collection to replace the 10v 1000μF and the 16v 220μF used in the Pi network filtering on the 5v rail.
 
 Unfortunately, the PSU switching chip didn't take kindly to all this extra capacitance and refused to start up (similar overload current foldback symptoms I'd seen with my fullwave rectification upgrade experiment).

 After double checking I hadn't bridged any tracks during my resoldering of the replacement caps, I figured that maybe I'd placed too much smoothing capacitance into the secondary circuit so replaced the 1500μF cap on the output of the 5v Pi filter with one of the 220μF caps and tried again (the tall 1500μF cap had made accessing the output header a little awkward, making it my first choice for reverting to the original value).

 This proved a sufficient enough remedy to allow the PSU to fire back up and, since the wattmeter showed no change for the worse, I boxed the job off to carry out ESR tests on the other three caps that I'd pulled from the PSU board. They tested ok on ESR compared to the other caps I'd used as replacements so they're no longer suspect. The one I was obliged to revert to and wasn't able to test seems to also be ok since I haven't seen the wattmeter readings get any higher than about 9.8W, typically varying between 9 1/3 W and that high water mark.

 That happened last night and this morning, I managed to catch a glimpse of the power level suddenly, yet smoothly, transitioning upwards by a tenth of a watt from just over the 9 1/2 watt mark. Over the next 5 or 6 hours it remained clear of the 10 watt mark by a good 5th of a watt whilst I was running some more tests on the AWG. However, after shutting it down so as to restart it with my last default settings, it refused to power up in a repeat performance of the excess capacitance episode.

 It was only after allowing things to cool down for 20 minutes that it started up again so I knew I'd have to pull out the remaining "1500μF" cap and revert to the original 1000μF cap so yet again I'd have to delve into the AWG's innards.

 I realised several days ago now that I'd best not bother refitting those four long screws that hold the case halves secured lest I totally wear the screw threads out by the time I've finished all of my planned modifications, so it's now just a matter of unclipping the top of the case from the front panel. I've gotten quite adept at this now with all the practice I've had recently with half of a cut up credit card as a spudger. :)

 Anyway, this latest modification to my last PSU modification seems to have dialled the capacitive loading back to a more tolerable level for the controller chip to get on with its job. I've had it running flat out for the past 5 or 6 hours and my hot power up tests checked out ok so it looks like I've modded that PSU to within an inch of its life (hopefully... I don't want to do any more back pedalling or I'll be right back where I started. high performance rectifier diodes upgrade and transformer mod aside). :)

 That brings me to a rather curious feature of Feeltech's design wherein the relay switched attenuator network creates a horrible impedance mismatch when it cuts in at P2P levels of 500mV and below. I noticed this effect, which only produces a discontinuity when driving into a 50 ohm load, after I'd been perusing the reverse engineered circuit diagram of the main board trying to work out exactly just how the relay switching was meant to function.
 
 What happens is that for levels at or below 500mV, the THS3002 (or replacement 3091 or 3095 or 3491) opamp(s) are bypassed and the output from the OPA686N is routed to the output sockets via a kakmaimee attenuator network consisting of two 100 ohm shunt resistors linked with a 510 ohm series resistor element. When I first saw that suspiciously high value resistor, I had to assume it had been a transcribing error for a 51 ohm resistor even though that would still have resulted in a 10% mismatch error of 45 ohms.

 When the AWG is driving a 50 ohm load, there's a huge jump in output voltage at the transition from 500.0mV level to 500.1mV level and beyond. When I repeated this test without the 50 ohm dummy load, the transition was seamless. Intrigued by this, I tested the output impedance with a DMM to measure the resistance of the output channels either side of this transition level and obtained readings of 52.7 and 84.7 ohms on channel 1 and 54.7 and 85.9 ohms on channel 2 for settings above and below the critical 500mV mark respectively.

 No wonder there was such a discontinuity in level when driving 50 ohm loads! It turns out that the series element of this attenuator is 510 ohms after all, rather than 51 to the zeroeth power of ten as I'd thought would be the more likely scenario. Those measured resistance values were in close agreement with my calculated value of 84.45 ohms for the resistor values shown on the circuit diagram.

 Anyone using this AWG only for driving Hi-Z loads at audio frequencies would never notice this "Skoolboy Howler" in the design of this final attenuator resistor network which Feeltech chose to "fix in the firmware" and hope nobody would notice their sleight of hand rather than sort it out properly with a new BoM for the attenuator resistor network.

 Luckily, for those with an interest in radio frequency work requiring properly terminated loads, this mismatch effect doesn't effect signal level settings above the 500mV mark. The obvious work around when millivolt test signals are required is simply to employ an external 20dB/40dB attenuator instead of the rather shoddy built in one.

 I did, btw, figure out that the other relay switching was to bypass the high voltage output current feedback opamp stages for output levels of 5V p2p or less. These high output opamps are only used for outputs when p2p levels above 5v are selected otherwise the OPA686N chips drive the output terminals directly or via those kakmaimee attenuator resistor networks.

 I did notice a problem with sub 50mV level signals with common mode interference from the PSU board (if it had been switching ripple on the voltage rails it would have reappeared when the attenuator cut out at the the 500mV transition point). Most likely a problem exacerbated by my 'curing' the half live mains leakage issue when I removed that class Y1 EMC bodge capacitor the other week.  :(

 BTW, I still think the JDS6600 is a bag of shite. It's merely a tarted up poor man's FY6600 imho and not worth its £62.48 plus £6.99 economy delivery price tag.


Regards and a merry Xmas, Johnny B Good

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 04, 2018, 01:01:17 pm
....snip...

 BTW, I still think the JDS6600 is a bag of shite. It's merely a tarted up poor man's FY6600 imho and not worth its £62.48 plus £6.99 economy delivery price tag.

Regards and a merry Xmas, Johnny B Good

I'm going to have to read through all your ramblings on the F***Tech.  It's both entertaining and educational.  But you still didn't give a reason for your denigration of the JDS.

Still, it's a great pleasure to encounter someone who both knows what they are writing about and writes well.  My BA is in literature, so I have done a lot of reading.

If I didn't have an Instek GDS-2027E sitting open on my bench while I try to sort the JTAG and TTY port I'd have the F***Tech open and follow along.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on December 05, 2018, 03:23:48 am
....snip...

 BTW, I still think the JDS6600 is a bag of shite. It's merely a tarted up poor man's FY6600 imho and not worth its £62.48 plus £6.99 economy delivery price tag.

Regards and a merry Xmas, Johnny B Good

I'm going to have to read through all your ramblings on the F***Tech.  It's both entertaining and educational.  But you still didn't give a reason for your denigration of the JDS.

Still, it's a great pleasure to encounter someone who both knows what they are writing about and writes well.  My BA is in literature, so I have done a lot of reading.

If I didn't have an Instek GDS-2027E sitting open on my bench while I try to sort the JTAG and TTY port I'd have the F***Tech open and follow along.

 I had to google "GDS-2027E" to check what it was you were working on. No sensible results until I tagged "DSO" on the end. First hit was Farnell/E14's details page on this stock item (one in stock at £462 plus the 20% VAT). Now that's more within my spending range!  :) However, now that I have an SDS1202X-E (a snip at £365, VAT and free delivery included), I'm not in the market for another 70MHz DSO.

 The big downside to the JDS version is the use of R2R ladder networks to save the cost of a couple of high speed 14 bit DAC chips. I did see the expected artefacts demonstrated in a tear down video but can't find it on Youtube. Almost certainly it was a link in an EEVblog posting but a quick search for threads mentioning the JDS6600 failed to reveal where I'd seen that particular video and another search on youtube was just as fruitless as was a search through my browsing history.

 If you want your full amplitude sine waves to be free of glitches at the zero crossing and half amplitude points, it's best to avoid assembling an R2R ladder network out of even the highest precision resistors available unless you're only going for an 8 bit resolution in your DAC circuit (you'll need to specify resistor values to a precision better than 0.1% for the ninth bit then 0.05% for the tenth and ever tighter by a factor of two each time you add successive bits of resolution to your R2R ladder network).

 You wouldn't expect any sane EE to try and outcheap Feeltech's FY6600 design but the JDS6600 represents a reduced BoM costed version that sacrifices performance out of all proportion to the minuscule cost savings involved (it's essentially the core of the FY6600 with the DAC chips substituted for by four dozen or so (high precision?) resistors.

 Just how cheap do you want your poor man's version of a £360 Siglent dual channel 30MHz AWG to be? I'd happily pay another tenner for a version of the JDS6600 that used proper 14 bit DAC chips... oh wait, I did!  :) Not quite an extra tenner though, just an extra 6 quid as it happened.  :)

Regards, Johnny B Good

PS  I've not had any more problems with the PSU board since I dialled the capacitor upgrade back a couple of notches (the 470μF substitutions for the original 220μF caps on the 12v rails don't seem to causing any problems for the driver chip). That's not to say I've stopped seeing that small third of a watt variation in its consumption. It just means I'm happy to accept that it's a characteristic of the generator's operation when supplying steady output signals into 50 ohm loads rather than some sign of impending PSU failure.

PPS  That kakamaimee output attenuator resistor network seems to have been designed as a 20dB pad for an 85 ohm impedance line. :wtf:  The firmware mediated compensation for the insertion of this pad for 500mV and below is only correct for the unloaded Hi Z case. What is required is to calculate the voltage attenuation ratio for this Hi Z case and design a 50 ohm attenuator pad that gives the same unterminated output voltage level and the extra 6dB of attenuation that's expected when properly terminated. I've only gotten as far as determining that it's an 84.755 ohm line attenuator.

 I'll try doing the rest of the calculations later on. I should be able to come up with a corrected BoM list for the attenuator resistor network compatible with  their 'quick fix' firmware compensation for the Hi Z error condition[1].

[1] They were probably aiming to introduce a 20dB drop in output level, ie a reduction to 10% of the (terminated) output voltage with an expected reduction of attenuation to 20% in the Hi Z case. What they actually got was a much greater reduction to 10.33% in the Hi Z case which they must have 'corrected' for in the firmware (but only good for the Hi Z output case). the 6dB drop expected with a 50 ohm load becomes an 8.6 dB drop in this case (I think).

 Trying to reconfigure for a 50 ohm attenuator pad that provides the same open circuit voltage attenuation and hence the expected 6dB drop when terminated with a 50 ohm load is doing my head in, even with the help of an on line dB calculator and a Matching Pi Attenuator Calculator. Never mind, I'm sure I'll find a solution... eventually!  :-\

[EDIT 2020-04-14]

 I did find a solution! It turns out I'd been overthinking the problem and giving F***tech far too much credit for ingeniously disguising the cheap choice of resistors used in their attenuator networks (RS1 to 6) by a 'firmware bodge' when in fact all they'd done was simply pick a cheap resistor combo that would provide the 20dB voltage reduction in the Hi-Z out[put case only (and let the Devil take the hindmost - those users relying on the output remaining at a 50 ohm impedance - for settings at or below the 500mV p-p mark).

 Using preferred values from the more expensive E192 range, substituting the 510 ohm with a 249 ohm series element and each of the 100 ohm shunt elements with 61.2 ohm resistors produces a 20.03dB @50.11 ohm attenuator pad. Even relying on the +/-0.5% tolerance of the E192 range limits the variations to a worst case  low of 19.96dB @50.28 ohms and a worst case high of 20.1dB @49.94 ohms, still plenty good enough for use as 'drop in' replacements.

 Anyone looking for a 'quick fix' to this 85 ohm attenuator issue, only needs to know that the required replacement is exactly a 20dB @50 ohm attenuator pad. The existing resistors (W1 to 6) can be shunted with additional smd resistors (easily calculated) soldered over the top, saving having to deal with the ticklish business of extracting the originals without risking harm to the board. At the modest 60MHz upper frequency limit, the small additional stray capacitance introduced by doubling up resistors in this way can safely be ignored.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on December 05, 2018, 08:37:06 am
If you want your full amplitude sine waves to be free of glitches at the zero crossing and half amplitude points, it's best to avoid assembling an R2R ladder network out of even the highest precision resistors available unless you're only going for an 8 bit resolution in your DAC circuit (you'll need to specify resistor values to a precision better than 0.1% for the ninth bit then 0.05% for the tenth and ever tighter by a factor of two each time you add successive bits of resolution to your R2R ladder network).
I have some vague memories of reading mentions that the resistor network on JDS isn't all R2R, but something else at one end, apparently exactly for the reason to make it a bit more accurate.
Also, IIRC, the manufacturer itself mentioned something about them doing something with the R2R/resistors stuff so that the accuracy would be better than expected with standard way to putting one together. Which I read in between the lines that either it refers to that something-else-than-R2R, and/or perhaps they use binned components (i.e. higher tolerance relative to each other, but not necessarily closer to the nominal value). Maybe... maybe just marketing talk.
I bought such JDS unit (didn't even know about the FY-stuff at the time). The little I have used it so far, the biggest problem isn't tiny errors in the DAC, but larger issues at higher frequencies/amplitudes caused probably by the amplifiers, and power supply noises etc.  But I guess the biggest issue depends on what the device is used for.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ledtester on December 05, 2018, 10:54:17 am
On the subject of replacing the power supply, here's a video of one guy experimenting with using DC-DC converters:

https://www.youtube.com/watch?v=FF2lk03mNto (https://www.youtube.com/watch?v=FF2lk03mNto)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on December 05, 2018, 05:21:42 pm
If you want your full amplitude sine waves to be free of glitches at the zero crossing and half amplitude points, it's best to avoid assembling an R2R ladder network out of even the highest precision resistors available unless you're only going for an 8 bit resolution in your DAC circuit (you'll need to specify resistor values to a precision better than 0.1% for the ninth bit then 0.05% for the tenth and ever tighter by a factor of two each time you add successive bits of resolution to your R2R ladder network).
I have some vague memories of reading mentions that the resistor network on JDS isn't all R2R, but something else at one end, apparently exactly for the reason to make it a bit more accurate.
Also, IIRC, the manufacturer itself mentioned something about them doing something with the R2R/resistors stuff so that the accuracy would be better than expected with standard way to putting one together. Which I read in between the lines that either it refers to that something-else-than-R2R, and/or perhaps they use binned components (i.e. higher tolerance relative to each other, but not necessarily closer to the nominal value). Maybe... maybe just marketing talk.
I bought such JDS unit (didn't even know about the FY-stuff at the time). The little I have used it so far, the biggest problem isn't tiny errors in the DAC, but larger issues at higher frequencies/amplitudes caused probably by the amplifiers, and power supply noises etc.  But I guess the biggest issue depends on what the device is used for.

 It's easy for me to point out the deficiencies of the poor man's version of the FY6600 (not that that didn't have its own defects including the very serious issue of the early firmware version 3.0 bricking the AWG). However, since people are still being tempted by its lower price point (about £6 cheaper than what I paid for my FY6600 just over a month ago) and improved 'haptics', ignoring the loss of the additional features of the FY6600, I think it's well worth reminding anyone, who has yet to sample one of these gloriously cheap AWGs for themselves, of this particular deficiency for which no practical DIY remedy exists (unlike the other issues of the PSU, the clock chip, the high voltage output opamp and the kakamaimee output attenuator that's automatically switched in for the sub 501mV p-p output amplitude range - not forgetting the need to add a small 40 or 50 mm cooling fan to stop it cooking itself into an early grave).

 I most definitely saw a video where the entirely predictable glitches at the zero crossing and half amplitude points of its sine wave output being unambiguously displayed on a 'scope trace and commented on by the reviewer. Unfortunately, I haven't yet been able to track down this review and tear-down video for all to see for themselves rather than simply just having to take my word for it.  >:(

 Regards, Johnny B Good
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on December 05, 2018, 06:51:49 pm
On the subject of replacing the power supply, here's a video of one guy experimenting with using DC-DC converters:

====link removed====

 I've seen this guy's earlier videos on the subject. I can't recall watching this video before so thanks for that link. It was an interesting insight into how a project can get out of hand (BTDT&GTBTS!). This is yet another video on how not to eradicate the half mains leakage of a cheap class II smpsu free of the HF switching transients that get through via common mode conduction path on the output wiring when you remove that bloody 1 or 2nF class Y capacitor responsible for the problem as a "quick 'n' dirty fix".

 He's on the right lines but I do have to question the wisdom of incorporating the mains transformer and rectifier pack inside the box. It strikes me that a better solution would be to use an external 16 to 20 vac 15VA transformer supply, leaving the rectifier and smoothing inside from which to feed the +/-12 or 15 volt and +5v dc-dc converter modules.

 Such modules are quite tiny so could be mounted clear of the original PSU board to leave the way open for an improved smpsu board equipped with a ferrite transformer blessed with the shielding foil layer to screen the secondary windings from the high voltage switching transients on the primary winding, neatly obviating any need for that accursed class Y emc bodge capacitor to produce a supply with a similar to, if not better than, isolation of a supply using a small conventional mains transformer.

 If he'd taken that approach to keep his future PSU upgrade options open and placed the dc-dc converter modules in the space between the existing PSU board location and the front panel, he could have made a neater job of adding fan cooling as I've previously described using a slimline 50mm 12v fan powered off the 5 volt supply mounted onto the base between the PSU and the rear panel (and blocking off those useless rear vent slots for good measure).

 The side vents are actually quite effective once you remove reliance upon the thermo-siphon effect alone as a passive cooling solution and provide just a modicum of forced ventilation in this way. It also helps to "gasflow" the accidentally provided exhaust leakage path provided by the RHS front panel clip slot in the base of the case to help dissipate the heat which builds up under the main board.  :)

 Regards, Johnny B Good

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on December 05, 2018, 11:47:27 pm
I replaced that crappy cheap power supply with a transformer and linear stabilizators . Doesn't matter if the transformer is inside or not , as long it's a good one ( with some shielding ) .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on December 06, 2018, 02:12:03 am
There's nothing wrong with the power supply other than the stray voltage that can be easily corrected. But if you're having fun, sure, why not?

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/1525/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/1525/)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 06, 2018, 02:50:14 am
I sent a pitch to @"Siglent America" for an SDS1204X-E loaner for 2-3 months to do a side by side comparison to the GW Instek MSO-2204EA a couple of days ago.  No response yet.  They are both Zynq based DSOs with comparable features.  The Siglent being about 1/2 the price of the Instek once you buy the LA and AWG options.

The FY6600  FP FW is looking unlikely as a PM to fremen67 did not produce a reply about getting the source code.  But people do travel on business or take vacations, etc.  So it might still happen.

The FP is  a pretty simple state machine.  My experience is almost entirely exotic DSP routines running on high end workstations and larger.  But I don't see anything that worries me.  It's just another thing I've not done before.  That was my stock in trade my entire career.  And the thing that made going to work so much fun. But at 65 with $50/bbl oil I can't ever go back to that.

Now visual persistence on a DSO, *that* scares me.  My LeCroy DDA-125 has up to 32 S of persistence and then infinite.  The latter is easy, but I can't figure out how you subtract what came in 32 S ago and remove it without eating a huge amount of resources.

All of this is tightly intertwined with the corruption of higher education and the cost of even a very modest test bench.  Most of my electronics efforts were when I had only a Heathkit IO-18 5 MHz recurrent sweep scope and Radio Shack VOM and DMM.  All my signal sources were built from datasheet circuits on perfboard.

Realistically, less than 5% of the population is university level science, engineering and math material.  And that's all we need as a society.  We need similar proportions of mechanics, plumbers, carpenters, machinists and such.  But the mania for trying to make silk purses out of sow's ears has destroyed education for all except the autodidact.

Unfortunately, lathes, milling machines, table saws, wrenches,  DSOs and such are so expensive as to be out of reach for most and  a serious barrier to the autodidact.

The Zynq and Gnu/Linux have been strong drivers in reducing the cost of DSOs.  A FOSS FW stack would reduce the NRE costs.  If I can write Verilog code which is portable across the Zynq and Cyclone V, the two FPGA lines with embedded ARM cores, then the barrier to market is lowered substantially and bug fixes become much easier.  During the workstation wars in the early 90's I ported 500K lines of VAX FORTRAN to six different Unix systems. After doing the first 4, the last two took 4 hours.  That was arguably the most important lesson of my career.  Develop and test simultaneously on as many systems as you can a hundred lines or so at a time.  I wrote two 15,000 line libraries on that contract that never had a bug reported in over 6 years. Though the test system did catch when Sun failed to set errno properly after a call to getcwd(3C).

Fundamentally I am doing what research scientist/programmers do.  Things I've never done before.  That's why it's so much fun.

And the pain of having limited financial resources, doing all the HW upgrades on a V 3.0 FY6600 and then it borking itself is quite palpable. 

But, Johnny, be good.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on December 08, 2018, 05:04:24 am
I replaced that crappy cheap power supply with a transformer and linear stabilizators . Doesn't matter if the transformer is inside or not , as long it's a good one ( with some shielding ) .

 That's true enough. The point I was making was that the bulky transformer(s) could be kept outside of the case, allowing the rectifier and smoothing cap to sit where the original smpsu had sat, leaving ample space for the three converter modules in the space between the front panel and the PSU location and still allow a 50mm cooling fan to be fitted in the bottom of the case in the remaining space to the rear of the PSU location, above which said fan, would be the ideal location to fit a 0.1ppm oscillator board (10MHz with the original clock on the MB replaced with a 5x pll multiplier chip or else as I've done, a 50MHz unit feeding the now vacated clock chip location) mounted at a rather jaunty 45 degree angle to keep it well ventilated with the incoming cooling air and free of the heat pollution it would otherwise suffer if mounted in the original clock chip location. In my case, this also improves the internal airflow by virtue of it acting as a deflector to direct the airflow more forcefully towards the front so as to increase the amount of air flowing past the heatsinked opamps.

 This leaves the option to fit a better grade of smpsu with a shielded transformer that obviates the nonsense of connecting the output ground return rail to the half live mains voltage via a 1 or 2 nF Y class capacitor as is, annoyingly, an all too common practice with such small Class II smpsu wallwarts and commodity PSU boards used in low wattage mains powered devices.

 The quest to find a suitable low leakage 12 to 15 watt rated wallwart is pretty hopeless but amongst my collection, I did discover three Nokia 5.7v 800mA phone charger wallwarts which read only 6.5 to 10.5vac on my 10Mohm DVM with respect to ground. I actually broke open the one of the three ever so slightly different implementations which had been not only screwed together but also glued (the other two were held together by only three screws in one case and two screws and a clip release in the other). Stupidly, I had assumed all three were identical in the finer detail of their construction, choosing on the basis of the one with the lowest leakage voltage reading only to discover that this was the one that not only needed the two screws to be remove but also the use of a junior hacksaw and some leverage with a screwdriver to crack it open. >:(

 Never mind, I can use it to replace a similar wallwart cct board that I'd fitted into an ITX 140W PSU box to beef up its weedy 100mA 5VSB rail. The extra 0.7v will nicely compensate for the anti backfeed diode I used to stop the existing 5VSB from causing this supplementary 5VSB cct board to go into an overvolt shutdown state. It can go into my FreeNAS spares box for now.  :)

 What I haven't yet done is check for the presence of common mode induced switching hash on the output lead. Looking at the one I broke open, it's not obvious as to whether the transformer is one with a screening foil layer between the primary and secondary windings to properly account for the lack of that dreaded Y class 1nF emc bodge capacitor.

 It'll be interesting to see whether it's a manufacturer's decision to simply omit the capacitor to emulate the capacitorectomy mod I've already done with the original PSU or whether they've actually justified such omission legitimately by using a screened transformer to meet the EMC directive. From what I've seen, I suspect not.

 I think I might land up attempting to rewind the low voltage secondary of an existing 12v 1.5 or 2 amp wallwart transformer so as to insert a screening foil of my own. I've certainly got plenty of such wallwart smpsus to experiment with.  :)

 Regards, Johnny B Good
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 13, 2019, 05:47:14 am
Interesting reading back on this flawed but really good value for money Box as it gets to EOL. There are some very cheap 50MHz units on evilbay at present if anyone is in the market with not to many $$ to spend as of today.

Mine after 15 months or so is about to get mothballed (Replacement is a Siglent 2000X) rather than sold for the few $ I might get for it so I chased up the last versions of the Windoze software and any updated Labview drivers and such to pack away with it.

Overall unlike some here my experience has overall been a positive one after sorting out the floating power supply and with a little trial and the correct tongue angle improving some levels on the board. Frequency has always been out by a bit but generally this is a non issue and if it was I checked and tweaked a few counts if needed.

Sub 10Meg for the complete software package that allows Arb Signal creation and driving the front panel via USB kicks the butt of the Siglent by comparison and as per the couple of comparison waveforms @30MHz Sine and 10MHz Square it holds up fairly well against a Generator at current pricing 10 times more $$. Coin toss for the Sine and suffering a little on the square.

Remembered fondly as it goes to the 'cupboard' to maybe never return  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GregDunn on January 13, 2019, 07:14:57 am
It sure does what I need with plenty of room to spare; mostly audio functionality testing, swept frequency, IM, etc. etc. and it can be quickly set up from the front panel to do rather complex stuff.  If I need low distortion, I use my Heath IG-5218, and if I just need a signal at an approximate frequency to spot-check something, it's the Wavetek 182 (the two of which together cost even less than the FY6800).  No, it's not a pro generator, or a real RF tester, but that's not what I expected when I bought it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on January 14, 2019, 12:34:41 am
Interesting reading back on this flawed but really good value for money Box as it gets to EOL. There are some very cheap 50MHz units on evilbay at present if anyone is in the market with not to many $$ to spend as of today.

Mine after 15 months or so is about to get mothballed (Replacement is a Siglent 2000X) rather than sold for the few $ I might get for it so I chased up the last versions of the Windoze software and any updated Labview drivers and such to pack away with it.

Overall unlike some here my experience has overall been a positive one after sorting out the floating power supply and with a little trial and the correct tongue angle improving some levels on the board. Frequency has always been out by a bit but generally this is a non issue and if it was I checked and tweaked a few counts if needed.

Sub 10Meg for the complete software package that allows Arb Signal creation and driving the front panel via USB kicks the butt of the Siglent by comparison and as per the couple of comparison waveforms @30MHz Sine and 10MHz Square it holds up fairly well against a Generator at current pricing 10 times more $$. Coin toss for the Sine and suffering a little on the square.

Remembered fondly as it goes to the 'cupboard' to maybe never return  :)

 Hi Beanflying,

 I was beginning to think the next post would be another follow up from me. It seems a shame to retire your Feeltech AWG to the toy cupboard after all the fun times you've had turning it from a sow's ear into a silken purse. I guess you didn't put in quite as much effort as I did to be able to throw it aside like that (I can't remember just how much work you did put into it this past year, I just know you were a regular contributor to this ongoing thread). Mind you, new toys and all that, perhaps I'd do exactly the same if (when) I bought a more upmarket replacement. :-)

 Anyway, it's been a remarkable 'Bean counteritus mitigation upgrade project' that makes all previous such projects I've had over the past 40 odd years pale into insignificance. I never realised there could be so many ways to waste a perfectly good AWG main circuit board by rampant beancounteritus. It's almost as if Feeltech could read the minds of their target market and went all out to give it the upgrade project of the century.  :)

 After spending a few weeks obsessing over the calibration accuracy of the 0.1ppm 50MHz TCXO module upgrade and lamenting the lack of any WWV transmissions (notably the 10MHz broadcast), I finally decided to tackle the PSU issue once and for all.

 I've spent the past two or three weeks searching for low leakage smpsus I could use with or without add on DC-DC converters to create an ultra low leakage three rail PSU. I even considered medical grade 12W (5 or 15 volt) wall warts from which to extract the smpsu board but gave up when I realised the price premium on something that only cost a penny or two more for its shielded transformer would make a mockery of my penny pinching signal generator purchase.

 The penultimate nail in the coffin of that "Holy Grail" search came when I discovered a complete lack of suitable DC-DC converter modules I could drive from a conventional mains transformer and rectifier smoothing pack to obviate the accursed Y cap. The final nail was when I discovered just how inefficient those specialised mains isolating transformers were as a consequence of their split bobbin construction.

 This was when I decided to 'Think Outside The Box' and came up with the clever idea of linking the common zero volt rails of a pair of smpsus wired to the mains in 'anti-phase' so their leakage currents would cancel (I was thinking of using the original for the +/-12v and an additional one for the 5v rails). I was so convinced that this 'neat solution' would work, I jumped out of my bed in the middle of the night to put my clever hypothesis to the test. Sadly, it didn't work because it was based on faulty reasoning so was doomed from the beginning.

 Never mind, I had another neat idea concerning a method to 'null out' (or buck) the unwanted half live mains leakage voltage. This idea was based on using a 1VA pcb mount 240 to 120 volt isolating transformer to provide an oppositely phased source of half live mains I could use to cancel out the unwanted touch voltage. Unfortunately, this was also doomed to failure (and for essentially the same reason that my "two smpsus in anti-parallel connection to the mains supply" hypothesis had been doomed).

 In both cases, bucking (or nulling out) the unwanted leakage voltage relies upon tying the anti-phase generator to the neutral line wrt to the supply rather than to an arbitrary mains input wire on the smpsu(s) concerned as I'd originally considered. The key to such a scheme is that you need to identify the neutral by which to reference your anti-phase source in order to successfully cancel out the leakage voltage. Although it's not too difficult to automatically detect which way round the supply is connected and automatically correct the polarity so as to ensure such nulling out exercises will succeed, such complexity is needless.

 The whole nulling out process becomes somewhat redundant since you can simply bridge the 0v rail to the neutral via a 100K high voltage safety resistor which will bog down the half live mains voltage on a 240v supply right down to a mere 7.5v - low enough not to harm any ESD sensitive devices under test. With that in mind, it then begs the question as to why invoke all the extra complications just to link the 0v rail via a safety resistor to a ground referenced connection (the neutral) to shunt the leakage voltage to a safe level when one might just as well use the safety earth to achieve the same effect without such complexity and less risk of a non-fatal but unpleasant electric shock when Sod's law inevitably messes up the auto polarity detection. Better yet, a real earth lets you use a 10K resistor, still large enough to avoid hum loops but even lower so as to reduce the leakage voltage to just half a volt on a 240v supply.

 It was this which led me into finally using my variant of the "Upgrade from class II to a class I earthed" configuration by adding a 3 wire IEC connector (C6 or C12/13) solution which most everyone else had chosen as one of their very first modifications to the FY6600, typically electing to use a 10 to 100nF capacitor in place of my 10K leakage voltage suppression resistor or else directly bond the safety earth connection to the common ground rail, sometimes using a "Grounded/Floating" option switch to obtain the best of both worlds (risky if the switch isn't bridged by a leakage mitigation resistor in the range of 10K to 100K and also prone to operator forgetfulness).

 I chose the slightly more tricky C6 socket option to avoid the "Tail wagging the dog" syndrome of hanging a 700g box on the end of a 10A 3 core mains lead, spending most of yesterday's free time fabricating the aluminium reinforcement and support plate required to accept the slot in C6 connector I'd recovered from a scrapped laptop charging brick. Unlike others' socket upgrades, this plate is simply bolted onto the flimsy rear panel which measure is more than adequate to prevent it bending and popping out of the case half retaining slots.

 It's taken me this long to get around to doing this job because I wanted to avoid this messy business of a brute force and ignorance pragmatic fix since I'd once held out hope of a more refined and elegant solution to eliminating the half live mains leakage hazard. It's only now, after days of fruitless searching for affordable low leakage smpsus and trying to think up cunning ways around the problem that I've come to realise that the pragmatic brute force and ignorance approach turns out, in this case, to be the one and only sensible option after all. Who (honestly) knew? :-)

 Following on from that, this modification seems to have cured a rather annoying feature whereby it would stop generating signals on both channels whenever connecting anything earthed produced an ESD event depending on the charge state of the Y cap at the time of connecting. TBH, I'm not sure whether this new symptom is a consequence of the TCXO modification or an existing feature that I only happened to notice after doing the TCXO mod.

 Anyhow, as I'd been hoping, the PSU leakage fix does seem to have cured this annoying habit of disabling both channel outputs whenever connecting up to an earthed device under test (and even when disconnecting) requiring a power down restart to restore the signal. I've just assumed that this is an unmentioned foible of the FY6600 series in general as a consequence of the psu leakage current issue, perhaps largely limited to those of us running it from a UK 240 or a European 220v mains outlet. I wonder whether anyone else has noticed this particular quirk?

 Incidentally, whilst on the question of funny quirks, has anyone else experienced the random loss of digit selection when using the left and right arrow digit selection buttons? This one is less annoying only because a simple disable/enable sequence on the channel select buttons restores the digit selection operation rather than require a power down/up reset. It's just a possibility that it might also be related to the psu leakage issue but I won't know whether this is the case until I've done some more testing.

 I think the only outstanding issue now is that of the attenuator used to handle the 1 to 500mV output range using the wrong resistor values, causing a terrible mismatch to 50 ohm loads. Feeltech have fudged this in the firmware by compensating for this error when driving Hi-Z loads. I did look into fixing this one with a change of the resistor values after working out what would be needed to create a 50 ohm pad with an attenuation that matches the Hi-Z loading condition they've actually compensated for (ie one that results in the 6dB drop when loaded with a 50 ohm load). Since this involves reworking smd components, I only want to do this job the once and get it right first time round so I've put it on the back burner for now until someone else can offer a sanity check on my recalculated resistor values. Has anyone else tackled this particular quirk?

 The resistor values they've used are a 510 ohm series element with a couple of 100 ohm shunt elements which turns out to be a 22.26dB attenuator for an 84.456 ohm impedance line. I suspect they were aiming for a 50 ohm 20dB attenuator using 56 ohm shunt resistors with the 510 ohm series element and somehow landed up  placing 100 ohm resistors instead of the specified 56 ohm ones through some sort of cockup in the manufacturing process and, rather than rework the boards with the correct resistors, they've chosen to compensate for the Hi-Z condition in the firmware and hope nobody important notices this blatant manufacturing error.

 Luckily, there is a hardware fix for this cockup (just as well seeing as we're not likely to see a firmware plus hardware fix out of Feeltech support) which involves calculating a new 50 ohm attenuator network that produces an attenuation figure 6.02dB lower than the Hi-Z attenuation factor of the current attenuator network for which they applied their firmware compensation fix. I think, going from my rough notes on the back of an envelope (literally!), this calls for a 25.71dB 50 ohm attenuator network to correct the problem with the current firmware left unchanged.

 Plugging the appropriate values into an on line matching Pi attenuator calculator, the ideal resistor values are 55.465 for the shunt elements with a 481.141 series element. trying alternate 'preferred values' in the hope of minimising the reworking, leaving the existing 510 series element as is and replacing the 100 ohm shunts with 56 ohm resistors will produce a reasonably close match giving a slightly higher attenuation value of 26.09dB with a 50.706 ohm matching impedance. Although this will produce a slight departure from monotonicity (not obviously apparent under Hi-Z conditions as things currently stand) as the level is stepped through the 500mV threshold, the very obvious discontinuity under 50 ohm loaded condition should all but vanish. I haven't delved any deeper into a more precise analysis to check just how big a glitch in voltage amplitude this might represent using those preferred 'quick fix' values. I'll leave that as an exercise for the interested reader to tackle. :-)


 Regards, Johnny B Good

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 14, 2019, 01:25:15 am
Putting in the cupboard and moving on is really an extension of gaining some more accurate equipment that you 'know' will output or input closer to the truth and provide a better series of ranges.

I made do for a very long while without one at all. Having one made life easier and saved me time using bread boarded or lashed up worse performing oscillators. So for someone without they are still a good thing with a simple mod to the power supply to improve the floating outputs. Much beyond that time and money spent to still get a box with still questionable accuracy and output limits doesn't make logical sense to me.

On a budget or after a first Sig Gen you can do way worse for more money.  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on January 16, 2019, 04:08:18 am
Putting in the cupboard and moving on is really an extension of gaining some more accurate equipment that you 'know' will output or input closer to the truth and provide a better series of ranges.

I made do for a very long while without one at all. Having one made life easier and saved me time using bread boarded or lashed up worse performing oscillators. So for someone without they are still a good thing with a simple mod to the power supply to improve the floating outputs. Much beyond that time and money spent to still get a box with still questionable accuracy and output limits doesn't make logical sense to me.

On a budget or after a first Sig Gen you can do way worse for more money.  :)

 Hi Beanflying,

 I do take your point but, right now, I'm not at that stage where I'd care to invest double what I paid for my Siglent SDS1202X-E dso just to get a slightly more refined version of my modded FY6600-60M signal generator (actually, as far as the front panel buttons go, hugely refined! - it's only the 600 quid saving which makes this lack of refinement acceptable... for now).

 If I was relying upon such T&M gear for my living, I'd certainly be prepared to make a greater financial investment but I'm now three years retired from the business of repairing desktop PCs, a trade which more or less died off some 4 or 5 years before I finally called it quits to collect my pension. Whilst I do have a reasonable lump sum languishing in low interest rate accounts to be burnt through, I can't really justify blowing some 10 to 15 grand of it on 'low end' decent gear, at least not right now.

 As you say, it's best to just shelve the FY6600 as a "get you by spare" rather than just sell it off for a paltry sum, especially when you've invested some time and effort improving its performance into the low end quality gear territory with price tags an order or two of magnitude greater. The factory upgrade option to a 0.1ppm TCXO on the Keysight 120MHz AWG is 700 quid alone which rather puts my 15 quid investment to do the same upgrade somewhat into perspective.  ;D

 I've applied several mods in the past two months since I purchased the unit last November. The list (in order of priority with the benefit of hindsight rather than the actual order I did them in) is:-

 Add a cooling fan, a highly desirable upgrade on the woefully inadequate passive ventilation, destined to cook it into an early grave.

 Add a C6 mains socket (in preference to the larger C12/13 socket if wish to avoid the "Tail wagging the dog" effect) and use a 10K resistor (not a 10 to 100nF cap) to link the 0v line to the protective earth pin to kill the unwanted half live 'Touch Voltage' without creating an earth loop problem,

 Modify the PSU to raise the 5v rail (4.95v measured) to 5.49v in order to raise the +/- 12 rails from the 11.4v mark into 13.7v territory upgrading the 12v rectifiers to heavy duty 20A rated dual shotcky rectifiers, leaving the 5v diode as is to maximise the voltage boost obtained by winding an extra two turns per "12volt" winding on the transformer (don't bother fitting 25v caps) and definitely don't try converting the 12v rectifier into a fullwave bridge by adding the 'missing' diode elements, DAMHIK, IJK.  :-[

[Edit 20190722]
 I found a much better alternative (which I described in a later posting) to adding two turns onto each end of the 12v windings - leave the 12v secondary untouched (I'd had to undo this modification) and wind a single turn to buck the 5v winding output voltage (easily accomplished without the need to remove the transformer).

 I'd used thicker wire than was needed, making a rod for my own back when Sod's Law ensured I'd connected it the wrong way round - put half a dozen single turn windings wired in parallel (plenty of room on the bobbin) to get a well coupled low resistance/leakage single turn winding to connect in series with the 5v rectifier diode (lift the anode out, wire one end in the vacated hole and the other end soldered to the lifted out anode lead).

 In spite of the voltage increase on the +/-12v rails (now at +/-13.7v mark), the power consumption actually dropped a fraction of a watt. Mind you, I'd replaced the 47K resistor in the voltage feedback network with a 200K to reduce the 5.49v on the 5v rail down to 5.09v which would have made some modest contribution to the achieved energy savings but I suspect most would have come from the efficiency improvement I'd achieved over the original adding of two turns at each end of the 12v winding modification.
[EndEdit]


 Upgrade the single THS3002 dual opamp to a pair of THS3001 (at a minimum) or, better yet,  THS3095 or ( a little OTT)  THS3491 opamps to eliminate sine wave distortion at 20V p-p when close to the 20MHz limit and driving 50 ohm loads.

 Upgrade the really shitty little commodity 20ppm rated 50MHz clock chip to a 0.1ppm TCXO module that can be located away from the vicinity of the three analogue voltage regulators that raise the board temperature up to 70 deg C, causing the original shitty oscillator chip to run at 50 deg C - the TCXO module can be located in the incoming airflow provided by the cooling fan.

[EDIT 2020-04-14]

 Finally, correct the output attenuator network that's used to reduce DAC and amplifier noise in the voltage output range of 1 to 500mV by...

paralleling each of the four 100 ohm shunt resistors (marked RS 1,2,5,6) with 124 ohm resistors and placing an 8K2 resistor in parallel with each of the two 510 ohm series elements (RS 3,4).

 You can use 120 ohms instead of the 124 ohm values since you'll likely have to trim the 8K2 resistors anyway to get an exact match to the unloaded attenuation corrected for by the firmware for the original 84.46 ohm impedance 22.26 dB attenuator that had been erroneously created (it looks like the 100 ohm shunt elements were placed in error for 56 ohm resistors which would have created a 26dB 50.706 ohm attenuator with that 510 ohm series element value). You can compensate such an error in the firmware but only for either the terminated condition or the unterminated Hi-Z condition, not both, so it looks like Feeltech opted to compensate for the Hi-Z condition with their firmware fix and hope no one notices the glaring error in the terminated case.

 I'd originally envisioned this modification as an smd reworking task but, after looking at pictures of the mainboard, realised it could be done using the smallest of wire ended resistors in parallel with the existing smd resistors which otherwise would have been replaced with lower value smd resistors (480 ohm series element resistor with a pair of 55.36 ohm shunt resistor elements per attenuator pad assuming 0.1% tolerance resistors in the original circuit). Since it's highly likely Feeltech only used 1% tolerance resistors at best, a better way to make sure of a good match to the original Hi-Z attenuation, they seemed to have precisely compensated for in the firmware, is to wire up a variable 10K resistor across the series element after soldering in the 124 or 120 ohm shunt resistors into the circuit and adjust for no discontinuity in level as you transit the relay switching point at the 499/500/501 mV mark other than the selected mV setting. This test should be done at a low frequency (say 1KHz) so that the stray L and C in the foot or so of wire between the board and the 10K pot have no detrimental effect - we're just finding the exact resistive value required in order to pick out a fixed value resistor by selection testing suitable candidates from our parts collection.

 The same 'select on test' procedure could be used to gather the desired 124 ohm 'rogues' from the 120 ohm parts bin - desirable but not essential although avoiding samples that are on the minus side of the tolerance range are best weeded out just the same.

 This might seem to some as rather a lot of trouble to go to (selecting on test and a variable resistor to tweak to a precise Hi-Z attenuation value) but if you're going to have a go at fixing this manufacturing defect at all, that extra faffing about is a trivial thing compared to the process of soldering in the additional wire ended resistors. After all, if a job's worth doing, then it's worth doing well or not at all. The motivation in this case being a more tightly specced output impedance than you typically see in gear costing one or two orders of magnitude more.  :)  Any EE (amateur or pro) with any pride at all wouldn't need reminding about the worth of doing a job well.


 Forget all that tosh. The design and its firmware had been predicated on the multiply by 10 add 20dB rule. That cockamamie 85 ohm attenuator just happened to be the cheapest way to get 20 dB in the Hi-Z load case. It had replaced the proper 20dB 50 ohm attenuator pad originally specified and made up from the most expensive E192 (0.5% tolerance) preferred values range using 61.2 ohm shunt resistors with a 249 ohm series pass element. I guess the chief bean counter must have threatened the chief designer with the sack if he didn't find a seriously cheaper alternative (meaning anything that could substitute for a real 20dB attenuator in the Hi-Z loading case and forget all about maintaining any semblance of 'Technical Standards').

[END_EDIT 2020-04-14]

 The final improvement I may end up attempting, would be to improve the action of the rather horrible front panel buttons, in particular the left and right arrow ones beneath the rotary encoder with the emphasis on the right-hand button which still causes the selected digit cursor to vanish from time to time, necessitating a cycling of the channel select button to get it back (at least it doesn't require a power cycling reset like the esd earthing contact transient used to do prior to my mains socket and 11k earthing resistor mod).

 The problem seems to be the result of the excessive force required in just the right place on the arrow button to get it to register the key-press possibly causing a cracked solder joint (hopefully not a cracked trace) nearby to open up on the front panel PCB causing a glitch in the cursor positioning subroutine. Whilst the left hand button produces a satisfyingly tactile toggling effect, the RHS one lacks such tactility, suggesting a faulty switch behind the membrane (hopefully an actual solderable into/onto the board micro-miniature momentary contact pcb mounted switch rather than a rubber membrane switch with a carbonised tip to bridge contact traces on the underlying PCB after the fashion of a cheap TV remote controller).

 The front panel is the one component I've not removed for closer inspection since, until recently, I've not had cause to apply an 'upgrade' to it. It's only now that I'm considering taking a closer look, not so much as an upgrade exercise (although a repair could be deemed as an upgrade from 'not working' to 'working') so much as a repair job, so I'm in blissful ignorance as to what lies beneath the actual switch locations underneath the membrane bumps. Has anyone taken a closer look at the front panel switches?

 At some time in the not too distant future, I'll be taking a very close look at the 'arrow' buttons with a view to 'upgrading them (or at least the RHS one) into a properly working condition. I don't know what awaits such a close examination so there's a chance that nothing short of a replacement front panel will resolve this issue. Since the FY6800 model appears to be an FY6600 with an upgraded front panel, I might, in that eventuality, land up buying a 60MHz version from which I may elect to cannibalise its front panel as a replacement for the FY6600 in view of all the work that's already been invested thus far. However, that does rather depend on just how similar the main boards actually are between the two models. If the front panel transplant proves to be impractical, that just means I'll be treading a well worn upgrade path to bring the FY6800 up to scratch.

 I'm not quite ready to 'throw in the towel' and splurge 700 quid on a Siglent SDG2122X  just yet!  :)

Regards, Johnny B Good
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on January 23, 2019, 07:55:33 pm
Ist it worth to get a FY6800 if you already have a Toellner 7401 and the build in AWG from Rigol MSO5000?

Or better a old wavetek Model 275? I think the wavetek is to old or? Waveform has to be tipped in over the buttons because i don't have a GPIB..
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on January 24, 2019, 11:32:17 pm
Ist it worth to get a FY6800 if you already have a Toellner 7401 and the build in AWG from Rigol MSO5000?

Or better a old wavetek Model 275? I think the wavetek is to old or? Waveform has to be tipped in over the buttons because i don't have a GPIB..

 Hi, Noy,

 The answer to that question rather depends on what you need. Not being familiar with those items of test gear, I had to search for information and landed up spending pretty well all day looking not only at youtube vids and other eevblog postings about the gear you mentioned but also distractions on frequency standards kit such as gpsdo projects and kits, taking note along the way that I might want to buy myself a u-blox NEO‑M8N gps module and have a go at making my own gpsdo reference or else blow 149 euro on a GPSDO2 from SV1AFN. Anyhow, all that aside, the conclusion I came to was that an FY6800 would, in several respects be a significant upgrade over all of the test gear you mentioned. Considering the cost of the MSO alone, an extra 100 dollars US on Feeltech's offering seems to be well worth considering if you want to go beyond the limits of a single channel basic 2MHz sig genny or the 5v p-p limits of the MSO's built in dual channel AWG.

 Regarding my own speculation on the possible need to replace the front panel of my much modded 6600 by cannibalising the front panel from a brand new FY6800, I finally got round to taking a closer look at the front panel which revealed actual soldered in switches and the possible reason for my losing the digit cursor highlighting in the shape of a badly soldered in encoder module.

 I re-sweated the solder joints (3 stand off pins top and bottom of the rotary encoder board which joined it to the front panel pcb) to get rid of the downward droop and reflow a suspect joint. Then I removed the offending right arrow switch and swapped it with the "CH2" switch where the extra stress would be better tolerated away from the extreme end of the panel's PCB and the better action of the "CH2" switch, now sat in the right arrow switch location would reduce the forces being applied to the extreme RHS of the front panel PCB.

 I can no longer see any misbehaviour no matter how hard I try to provoke it, so it seems the switch swap (and resoldering the encoder connections) has nicely solved this issue. The original right arrow switch works just fine in its new "CH2" better supported location under the larger and easier to press square shaped button dome. Also, I noticed the use of only two fibre washers between the display/switch panel and the cpu board so fitted fibre washers to the other 3 or 4 fixings to try and balance it up. I used thinner fibre washers by way of a compromise in case there was an actual reason for Feeltech choosing only to fit two washers.

 Although I'm not overjoyed by the use of membrane operated switches, I'm happy enough that the right arrow button does now operate tolerably well (by the standards of membrane switches) and no longer suffers random loss of the digit cursor which is a relief seeing as how frequently the cursor positioning switches will be operated compared to all the others.

 The reason for my taking the front panel apart was on account of my stripping the whole contraption down in order to improve soldering iron access to modify the output attenuator from an 85ohm pad into something approximating a 50 ohm pad. I shunted the 100 ohm shunt elements with 120ohm smd resistors and wired some ancient multiturn pots across the 510 ohm series elements to let me trim the unterminated attenuation to match the original calibration Feeltech had applied to hide their goof.

 It seems I miscalculated the new resistor network values and found myself needing a much lower value across the 510 ohm series elements than my 8K2 estimate, landing up with trimpot values of 339 and 350 ohms, resulting in a 44.5 ohm pad rather than the desired 50 ohm pad. Still, whilst not perfect, it'll do for now (a 5.5 ohm discrepancy is a considerable improvement over the original 35 ohm discrepancy). I've subsequently had two more goes at calculating replacement resistor values and I'm just getting more confused as to which two sets of values are closest to being correct, so I'm putting further refinement effort to one side for now.

 After using my HF transceiver to listen to the 20MHz carrier being produced by the AWG, I'm once more looking for a better PSU solution since I'm convinced that what others have described as 'appalling sideband/phase/jitter noise is nothing more than modulation from voltage rail ripple. I need to make up a battery supply (two 12v SLAs with a 5v regulator to provide the three rails) to test this hypothesis before I spend Ghod knows how long to track down a suitable well screened three rail power supply solution. All I know at this stage is that there actually are suitable "designed for test gear" ultra low noise dc-dc switching converter modules available - I just haven't dared to seek a price quote.  :scared:

 One final point. When I replaced the crappy C8 mains connector with a C6 last week, I used a two pole rocker switch. Unfortunately, it wasn't one rated to survive soldering wires to its tags and I damaged it. It still worked at that time but I wasn't entirely happy about it. Nevertheless, I'd spent enough time sorting it out so wasn't in the mood to wire up another switch so accepted it as the best of a bad job.

 A couple of days ago, that came to bite me in the backside when, after unusually having left it switched off overnight, I came to turn it on early in the morning to check out its frequency drift from cold, it didn't power up until I held the rocker switch pressed in the on position. Having proved my doubts about its long term survival of the soldering iron abuse, I had no choice but to pick out another rocker switch replacement from my assortment of salvaged single pole rocker switches (that damaged switch had been the only two pole example of the breed I'd had in my possession).

 This meant I had to recover the original plug in switch flylead from its repurposing as a jumper plug courtesy of a crimp on silicone grease filled connector and hope it was still long enough for the job (it was, but only just!) and thin out the lower flange of the switch so it could overlap the top of the slide in C8 connector without fouling by use of a junior hacksaw and a small file (hence my original reluctance to replace the damaged switch to begin with).

 Anyhow, I successfully soldered the flylead onto the replacement switch's solder tags without damage this time (I guess the plastic used by this one must have been rated for soldering temperatures - I'd had to unsolder the cut off remains of the original wires before I could repurpose it and that went ok). Thankfully, the flylead was just long enough to reach the psu connector so all was well with my repair and I was finally able to start my "Frequency Drift from Cold" test of the 0.1ppm 50MHz TCXO module using the BBC Radio 4 LW transmission on 198KHz as my Rubidium frequency reference.

 It does have a strange power on drift characteristic from an ambient of 17deg C where it starts some 30ppb off frequency transiting the 0ppb mark some 5 minutes or so later before settling on a 15 to 20 ppb error some 30 to 40 minutes after that. Once the ambient reaches 21 to 22 deg C it settles to within +/- 5ppb of the 198KHz Rubidium reference frequency. This behaviour (settling to within +/-5ppb at 21/22deg C at any rate) seems consistent from day to day which is quite gratifying for a 100ppb rated TCXO module which had cost me less than 16 quid delivered.  :)

 For me, the Feeltech FY6600 has been a very cost effective investment indeed. The only other T&M kit I've ever possessed have both been boat anchors of 1950s vintage. A Marconi signal generator and a 5MHz 'scope which I last used over quarter of a century ago, now languishing in my rather neglected basement radio shack come workshop.

 Indeed, it's been so long since I last used them, I can't even recall the frequency range of the sig genny nor whether the 'scope was single or dual beam. Furthermore, I'm not even sure I have enough strength to manhandle the 'scope off the dexion shelving to set it up on a bench for testing. The Marconi sig genny I think is a little lighter and also sat on a lower shelf so I think I could just about manage to drag it out and onto a test bench... but only if I had a mind to do so.

 Quite frankly, as much as I'd like to, I would have to be out of my mind to even attempt such a strenuous exercise just to satisfy casual curiosity, besides which, I'd have to find somewhere else to stack the stuff already piled up on my basement test bench just to make room for said boat anchors - I wouldn't want to be lugging them about any more than I'd absolutely have to if curiosity were to ever overcome my sense of self preservation.

 Anyhow, now that I've upgraded those boat anchors to a Siglent SDS1202X-E and the FY6600, they're now well and truly relegated to the status of vintage T&M curiosities. There's been considerable development in T&M kit over the past half century or so since that vintage T&M gear was last manufactured, thank Ghod!  :)

 Regards, Johnny B Good.
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on January 29, 2019, 10:08:27 pm
Hi, got a FY6800 now..

Managed somebody to run the software in Linux? Maybe with wine? Which special things do i have to install in wine(winetricks)?

Is there another Linux software around?

Which hacks are worth to do on the fy6800?
Adding THS3095 / THS3491 ? Although switching to another 50MHz TCXO? Which one will fit directly in the pcb? There are some 0.28ppm 50MHz available at mouser? Or a bit cheaper 2.5ppm. Both better than 100ppm
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on January 30, 2019, 08:04:30 pm
Hi, got a FY6800 now..

Managed somebody to run the software in Linux? Maybe with wine? Which special things do i have to install in wine(winetricks)?

Is there another Linux software around?

Which hacks are worth to do on the fy6800?
Adding THS3095 / THS3491 ? Although switching to another 50MHz TCXO? Which one will fit directly in the pcb? There are some 0.28ppm 50MHz available at mouser? Or a bit cheaper 2.5ppm. Both better than 100ppm

 Hi, Noy

 Can't help with the software since I still haven't gotten round to setting up the USB pass through for my winXP VM (VBox) and, afaiaa, there isn't any *nix version of the Feeltech SW being offered so it's either wine or a windows VM solution.

 The opamp upgrade is worth doing. Even the THS3001 opamps would be an improvement over the 3002i originally fitted. The 3095, if still available will be fine otherwise use the latest 3491 chip which, TBH, is a little over-specified for this application.

 Fitting a drop in TCXO replacement for the XO chip is not a good idea since your replacement is likely to land up running at 50 deg C just like the original chip did on account of its proximity to the three analogue voltage regulators raising the PCB temperature to 70degC! You really do need to install a cooling fan before upgrading the XO chip or else the 20 to 30 deg C delta from switch on will make a mockery of your 0.1ppm 50MHz TCXO upgrade by hiking its temperature well beyond the 0 to 25 deg C operating range typically specified in order to meet the 0.1ppm stability rating. Typically, the spec degrades to 0.5ppm in the sub zero and the 25 to 65 deg C temperature ranges (mine only claimed a degradation of 0.2ppm for this extended range as it happened).

 A much better option is to buy a TCXO clock module, similar to this 100MHz one here,  <https://tinyurl.com/ycsqvlml> (it seems this seller has now sold all of his stock of 50MHz oscillator modules) so you can mount it well away from the heat. I've got mine mounted at a jaunty 45 degree angle above the 50mm fan I'd installed into the base of the case between the back panel and the psu board, adjacent to the main board. This not only acts as a deflector to direct the airflow towards the front of the case, it also receives the full benefit of the incoming cooling airflow to isolate it from the heat within. Even so, there is still a small amount of heat pollution to raise the oscillator board temperature a degree or two above room ambient but at least it's a vast improvement over the more likely 10 to 20 degree rise in even the coolest part of one without the fan modification.

 I chose the 50MHz board simply because it was the cheapest way to get hold of a 0.1ppm 50MHz TCXO. I was just going to remove the TCXO from the board and transplant it directly to the original XO chip location but, when I measured the temperatures on and around the XO with my IR thermometer, I had a complete change of mind and decided to make use of the whole oscillator board as supplied.

 In retrospect, it would have been better to have used a 10MHz TCXO and replace the XO chip with an NB3N502 14 MHz to 190 MHz (output) PLL Clock Multiplier chip wired up to multiply it back up to 50MHz. The 10MHz TCXO modules are more available than the rarer 50MHz ones so can often be had below the 20 dollar price I paid for mine, plus, you then have the option of fitting an external 10MHz clock socket and a switch giving you the option to feed it from an external GPSDO or Rubidium clock reference.

 If you're not planning on replacing the smpsu board with something better but want to raise the 11.5 ish volts on the nominal +/-12 volt rails to a more useful 13.5 to 14 volts to make more effective use of an opamp upgrade and give you a couple of volts margin on the DC offset range (literally none whatsoever at the 20Vp-p output setting!), then the most efficient way to achieve this is to wind a single turn secondary on the transformer (there's ample space to wind 3 or 4 such turns in parallel with the existing transformer using ordinary 0.6mm solid core hook up wire and it should be do-able without unsoldering the transformer as I had to when I added two turns aiding to each end of the 12v windings). This then can be used to buck the 5v winding, saving the need to raise the 4.95 volts to the 5.49 volt mark just to increase the 12v rail voltages.

 You can lift the anode end of the upgraded diode used for the 5v rail so as to wire in this single turn in series with the original transformer connection to said diode. If you connect it series aiding, the 12v rails will drop by a couple of volts, indicating the need to reverse the connection. This provides a less lossy way to raise the 12v rails to a more useful voltage level and reduces the extra heat generated on the main board with the 10% boost on the 5v rail applied only for the sake of raising the 12v rail voltages. Unlike the "Add two turns onto each end of the 12v windings which involved unsoldering the windings from the tags and soldering the extra wire onto the released ends of those windings, this transformer mod completely eliminates the risk of transformer damage and is readily reversed. Regardless of this, it's still worth upgrading the original crappy rectifier diodes with better suited types which makes the additional single turn buck winding mod a trivial side task to the work involved in replacing the diodes.

 Of course, you can simply replace the whole PSU with a ready made unit of better specification since, even with the fitting of a cooling fan in the base to the rear of the original PSU, there's still ample space to fit a larger PSU module. I have a suspicion that the switching ripple noise of the original psu board is the real culprit behind the claims of 'horrendous jitter' when using it as an RF signal generator with HF radio equipment but I haven't yet gotten round to making up a + and - 12v battery supply feeding a 7805 regulator to provide the 5v rail entirely free from any such PSU noise to verify this suspicion that what I hear using an HF transceiver on a 20MHz sine wave output setting is simply amplitude modulation from the psu ripple voltage. Hopefully, this noise is due to supply ripple voltage rather than something more fundamental to the mainboard itself.

 IOW, I'm now reconsidering the analogue PSU option as a possible requirement to eliminate this defect in spite of my reservations over the additional waste heat such a supply will inject into the box. There are, apparently, such things as ultra low noise DC-DC switching converter modules designed with the needs of T&M gear specifically in mind. These can be used with a conventional transformer and rectifier setup in place of the heat generating anaolgue voltage regulators, neatly avoiding the regulator waste heat issue but I haven't yet dared to get any quotes on pricing since I've yet to prove my suspicions about the existing smpsu board. In any case I may yet be able to get hold of a three rail screened smpsu with low noise and ripple specifications similar to those dc-dc converter modules.

 Although the FY6800 is already blessed with an IEC C13/14 connector to start with, neatly addressing the thorny issue of half live mains leakage voltage, I'm not impressed with the way they gone about connecting the safety earth from what I've seen of published photos of the vandalising of the PSU to main board connecting cable where they've rather pragmatically simply chopped one of the two ground wires to join the safety earth connection to, leaving the other end disconnected, thus compromising the ground connection between the psu and the main board. I suggest you join that loose grounding wire back onto the joint used by Feeltech to bodge the safety earth connection.

 Such bodgery by Feeltech isn't unusual, witness the firmware bodgery employed to correct the mistake made in the board's manufacture where they placed 100 ohm shunt resistors in error for the (most likely) 56 ohm resistors required to create a 20dBish 50 ohm attenuator pad in place of the 85 ohm pad they landed up with as a result of that cockup. Since the FY6800 is supposed to be an improved version of the FY6600, I'm wondering about whether or not that extends to correcting this manufacturing cock up.

 It's a fairly trivial matter to test what happens to the output voltage when the relay clicks in at the 500mV setting under terminated and unterminated conditions. There might be a small discontinuity in the change of voltage level in each case but if they've corrected this issue, it should be similar in both cases (open circuit or terminated). With the Fy6600, the discontinuity in the open circuit case was imperceptible but repeating this test with a 50 ohm termination in place produced a massive level change as the relay switched the attenuator in and out of circuit. Perhaps you can repeat this test and let us know your findings?

 Anyway, that's quite a chunk of 'things to do' so I'll summarise the list here and in order of priority as I see it:-

1:  Install a small cooling fan. Natural convective cooling with the current vent slots arrangement does nothing for the cooling, especially when tilted up on its prop stand where you'll get just about the same cooling effect as if no vents whatsoever had been provided. Those vents will only be a benefit with the addition of forced air cooling.

2:   Upgrade the PSU (modify or replace) and, in the case of the FY6600 (not needed for the FY6800), fit an earthed mains socket (preferably an IEC C6 if you want to reduce the "Tail Wags Dog" effect). You can use a 10K resistor to link the 0v rail to the safety earth pin if you just want to kill the half live mains voltage without introducing troublesome mains earth grounding loops and the need to incorporate a "Grounded/Floating" option switch.

3: Once you've dealt with points 1 and 2 above, you can upgrade the rather weedy THS3002i opamp with a pair of THS 3001/3095/3491 opamps (take your pick, any of them will be better than what it was cursed with).

4:  Remove the rather execrable XO chip from its rather toasty 50 deg C location and install a 0.1ppm 50MHz TXCO module in the coolest part of the case or use a 10MHz TCXO module with  an NB3N502 PLL Clock Multiplier chip soldered onto the original XO location (it won't mind the 50 deg C temperatures - just make sure the TCXO module is kept away from the heat!).

[EDIT 2020-04-14]

5: Depending on whether there is still the issue of the 85 ohm attenuator pad to contend with in the 'Improved' FY6800 model, you might find yourself impelled to repopulate with resistors recalculated to create a 50 ohm pad that has the same unterminated voltage attenuation as the 85 ohm one to match the correction applied by the firmware fix.

 Working out the required resistor values isn't quite so easy to do, even with the assistance of on line dB ratio and attenuator resistor network calculators. I landed up with a 45 ohm attenuator pad after adjusting the series element resistance with multiturn trimpots after putting 120ohm resistors across the 100ohm shunt elements to get a precise match to the Hi Z impedance attenuation of the original. I'm still confused by the results of my two subsequent attempts to calculate the required resistor values so I've left that as a minor annoyance to be dealt with at a later time. The resultant 45 ohm attenuator is at least some improvement over the original (but it's still not ideal).

 If you do test the output levels around the 500mV setting where you can hear the relay click in and out, please let us know your results.


5: Ignore all the tosh above and replace those cockamamie 85 ohm resistor networks with a bog standard 20dB 50 ohm pad by replacing the 100 ohm shunt resistors with 61.2 ohm resistors and the 510 ohm series elements with 249 ohm resistors (both from the more expensive E192 preferred values 0.5% range). You can use an on-line Pi attenuator calculator to try alternative preferred values such as this one here:-

https://chemandy.com/calculators/pi-attenuator-calculator.htm

Regards, Johnny B Good.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on January 30, 2019, 08:25:53 pm
Thx for the summary. I will test it and give a Report.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on January 30, 2019, 08:33:57 pm
Thx for the summary. I will test it and give a Report.

 Thanks for the swift response and I look forward to your report.

Regards, Johnny B Good.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: MT on January 30, 2019, 10:27:32 pm
FY6800 test and teardown.
https://www.youtube.com/watch?v=5_iJEOffikA (https://www.youtube.com/watch?v=5_iJEOffikA)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on January 31, 2019, 12:06:02 am
I've seen it already! Oh God, how I've seen the start of it so many fekin' times in my search for more informative reviews that I've lost count. >:(

 What's particularly annoying about that video is the use of "Rockyvision"(tm). I'd imagine motion sickness sufferers would have a hard time trying to watch that video. Why the hell didn't he fix the rocky table before recording his review? I'll often watch repeat videos to pick out stuff I may have missed the first (or even second) time round but not this one.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: MT on January 31, 2019, 12:43:41 am
You may have seen it but perhaps others may not!  :)  i just wonder if FY68 is as terrible as FY66!? Very few seams dare buy one! ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on January 31, 2019, 12:57:30 am
You may have seen it but perhaps others may not!  :)  i just wonder if FY68 is as terrible as FY66!? Very few seams dare buy one! ;D

Sorry but that statement is  :bullshit: in spite of the attempted humour. The FY6600 was a flawed product certainly and some had failures but a lot more didn't and it represents great value. There has been a lot more paid for products with much worse performance and issues. The main failing was Feeltech themselves putting up the shutters and not resolving or providing a mechanisim to fix those issues of some customers (firmware support).


Best not to add to much detail on the FY6800 here as there is already several threads with that in the title so it will get lost over time.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gege34 on January 31, 2019, 08:44:17 am
Johnny B Good thank you very much for this great description to improve the FY6800 :-+.
I have the FY6800 from KMoon (firmware 1.7.1 but reported as 1.7 with the PC software).

1. Could you please make a picture of the internal modded device to see were you put the fan and the TCXO.

2. About the power supply upgrade, to summarize, what is the easiest way to improve the original one?

4. About the TCXO how to properly connect it (cable to use, ...) to the main board?
I have found the 50MHz version here (https://fr.aliexpress.com/item/50MHZ-hifi-TCXO-0-1ppm-Ultra-precision-Golden-Oscillator-CLOCK-power-supply/32962398016.html?spm=a2g0w.10010108.1000016.1.3d7654acJNShIc&isOrigTitle=true) (several of available).

Thank you
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: MT on January 31, 2019, 05:10:10 pm
You may have seen it but perhaps others may not!  :)  i just wonder if FY68 is as terrible as FY66!? Very few seams dare buy one! ;D

Sorry but that statement is  :bullshit: in spite of the attempted humour. The FY6600 was a flawed product certainly and some had failures but a lot more didn't and it represents great value. There has been a lot more paid for products with much worse performance and issues. The main failing was Feeltech themselves putting up the shutters and not resolving or providing a mechanisim to fix those issues of some customers (firmware support).
Best not to add to much detail on the FY6800 here as there is already several threads with that in the title so it will get lost over time.

FY66 is not bad? From what i learned form this thread the firmware seams to freeze for some people making the unit non working while FY as you said your self dont provide any means at all to fix this nor allowing a third part, which inhibits my self to buy a FY66 and as such i consider that a failed product. Or have i missed /misinterpreted something else what you said is infact contradictory :bullshit:?

On that base i have serious constraints into buying a FY68. How do i know the FY68 is not flawed with problems?  :-//
Other people in this thread have said "dont by a FY product until they fix FY66", well thats a fair statement i think.

However i do concur that FY68 deserves its own thread i hope will just contain 1 page not 71 as FY66 got! ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on January 31, 2019, 05:12:23 pm
I ordered some samples from ti for the ths3491. Hope the advertising of "more headroom" and so on is true. Maybe then there is no need to build a new power supply. Even If a linear one would be great.
Also i will check If its possible to twaek the original Power supply to 13-14 V maybe some other feedback resistors?

Fojnd the same txco and ordered it (directly from Ali).
Need to Check the supply from it (12V to high and 5V too Low.) and If the 5V Out is ok or maybe i have to adjust it to 3.3V?

I think it is an easier way instead of using a pll Chip. And i don't have a gpsdo so i don't need an external clock in.
Maybe i will use a si5351A? But i think it is even more  worse than the original Crystal?



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on February 01, 2019, 10:39:39 pm
So i tried to find your 50 Ohm issue.
For me IT IS not totally clear for me what i should See or mit See. Can you explain it a Bit more? I looked at the output with 0.6 and 0.5 Amplitude. And checked it with 50 Ohm termination and without..

Only issue i swa ist a small dc offset as Soon as i Switch the Mains on... Can i recalibrate it?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: gamerpaddy on February 03, 2019, 12:36:52 am
What's particularly annoying about that video is the use of "Rockyvision"(tm). I'd imagine motion sickness sufferers would have a hard time trying to watch that video. Why the hell didn't he fix the rocky table before recording his review? I'll often watch repeat videos to pick out stuff I may have missed the first (or even second) time round but not this one.

i did that on purpose, just for people like you   ;D


Ive got 3 of the fy6800 units now, two of which i bought broken.  20, 30 and 60mhz model all of them share the same internals (v1.7 board) but different software-config.
one was a easy fix, just a connector was unplugged
the other one had its Powersupply break. (IC blow, main capacitor a bit on the low side, pcb cracked. Fuse(c)apple inc intact . 
the numbers have been rubbed off but i figured out its a THX203H IC
before i order a buch of them, id rather make myself a drop-in replacement pcb with linear regulators

time for somone to write a custom firmware, id rather need a sweep trigger than a sync/uplink IO

(https://i.imgur.com/9APdcef.jpg)

(https://i.imgur.com/iuuFd7O.jpg)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: lmsele on February 03, 2019, 11:47:48 pm
 I found that loading a file length @ 8193 prevents the run time shut down error.

Here is what I did:
1. generate 8192 length .csv
2. Rename it to .fy; press the waveform window tab
3. Go to file at top of main window; press open
4. Open your file (length 8192)
5. The "extraction data" window opens.
6. Click the "open file" button in the extraction window
7. Your waveform should be visible in the extraction window.
8. There will be several dialog boxes open in the extraction window data length, fetch length, start, end.
9. Enter 8193 into the "end" dialog box
10. Your waveform will now be visible in the waveform window.
11. Upload to your desired memory location
12 Your waveform will be visible on your oscilloscope.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: gamerpaddy on February 04, 2019, 12:42:24 am
just to note,
 the pc software asks the device for its firmware by sending
Code: [Select]
UVE\n, the device responds with for example
Code: [Select]
v1.7\n\n
the firmware downloaded by the pc software is this:
fy6800:
http://feeltech.net/software/updata/FY6800/download.php?vison=DDS&name=FY6800-DDS.FYbi (http://feeltech.net/software/updata/FY6800/download.php?vison=DDS&name=FY6800-DDS.FYbi)

fy6600:
http://feeltech.net/software/updata/FY6600/download.php?vison=DDS&name=FY6600-DDS.FYbi (http://feeltech.net/software/updata/FY6600/download.php?vison=DDS&name=FY6600-DDS.FYbi)

not sure how its converted / flashed. forgot to run my logicanalyzer when updating my unit.  gotta figure out how to trick the firmware check that theres a newer version.
it also doesnt contain the typical \x00 \x50 \x00 \x20 header i find in all stm32f103 .bin's  maybe its decrypted.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on February 04, 2019, 04:40:10 pm
That is NOT a header. If you have a direct binary image file of any ARM Cortex M processor, the first 32bit word is the address where SP (stack pointer) should be place. Second  32b word is where the reset vector is located.

There is nothing "typical" other than SP is typically in internal SRAM, which begins at 0x20000000.  So your byte quartet is indeed a SRAM address of 0x20005000 - which kind of makes sense.  (Remember that Cortex M is little endian).

(Which also by the way, is a pointer to the END of SRAM in STM32F103, where there is 20kB (0x5000) of SRAM).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 05, 2019, 04:34:01 am
 To Noy: You need to adjust by a millivolt at a time. I can't recall whether the relay switches the attenuator in and out between the 499 and 500mV mark or between the 500 and 501 mV mark. However, you should hear the relay click (you might need to disable the beep in order to hear the relay).

 When driving a high impedance load, the change in level should be just about what you'd expect. If this attenuator network hasn't been corrected from its 85 ohm form in the FY6600 to a proper 50 ohm one in the FY6800, you'll see a much greater change at the relay switching point when driving a 50 ohm load.

HTH

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 05, 2019, 04:40:47 am
Johnny B Good thank you very much for this great description to improve the FY6800 :-+.
I have the FY6800 from KMoon (firmware 1.7.1 but reported as 1.7 with the PC software).

1. Could you please make a picture of the internal modded device to see were you put the fan and the TCXO.

2. About the power supply upgrade, to summarize, what is the easiest way to improve the original one?

4. About the TCXO how to properly connect it (cable to use, ...) to the main board?
I have found the 50MHz version here (https://fr.aliexpress.com/item/50MHZ-hifi-TCXO-0-1ppm-Ultra-precision-Golden-Oscillator-CLOCK-power-supply/32962398016.html?spm=a2g0w.10010108.1000016.1.3d7654acJNShIc&isOrigTitle=true) (several of available).

Thank you

 Sorry about the delay in responding. I had hoped to get the chance to take some photos to post here rather than having to say, as I now am, that I'll post some up as soon as I get another chance to open it up. Right now, I'm rather preoccupied with a little DIY GPSDO project to let me more accurately and swiftly calibrate the 50MHz 0.1ppm TXCO upgrade. As soon as I get the chance, I'll be only too happy to post the photos here and do a little showing off.  :)

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on February 05, 2019, 08:44:59 pm
So tested it:
Amplitude 500mV with no DC offset -> 528mV and 100mV DC Offset Into high impedance.
1mV change (501mV) at the generator (relay clicked) caused  512mV and 84mV DC Offset Into high impedance.

Same with 50Ohm Input:
500mV -> 200mV and 44mV DC Offset.
501mV -> 256mV and 44mV DC Offset.

And why is there a 100uV Digit? 😂


20mV DC Offset with Output Off Into 50Ohm 50mV Into high impedance...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on February 05, 2019, 09:16:29 pm
Found this:
https://github.com/DerKammi/FY6600-15-30-50-60M/blob/master/Hardware/FY6600%20PS%20schematic%20V1.pdf

I think i will try to "upgrade" the supply If the ths3491 isn't enough.

Any suggestions for another/better pincompatible  DAC?
DAC904 in fy6600 regarding the Link but dac904 are 165Msps Not Like Advertisement 250Msps. In my FY6800 are two AD8009 instead of the OPA686. Also any better suggestions? AD8000?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Yansi on February 05, 2019, 11:51:40 pm
I think that changing these variables (DAC and OPAs) will not improve anything marginally, just a tiny bit at best.

The layout of the PCB is just horrid, that should be fixed first I think for any significant spec improvement to occur.

/* Just wanted to say Hi! Haven't watched this thread for a while (my taste for the FY6600 has gone) an am impressed by how far have you got so far */
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 06, 2019, 02:09:51 am
Johnny B Good thank you very much for this great description to improve the FY6800 :-+.
I have the FY6800 from KMoon (firmware 1.7.1 but reported as 1.7 with the PC software).

1. Could you please make a picture of the internal modded device to see were you put the fan and the TCXO.

2. About the power supply upgrade, to summarize, what is the easiest way to improve the original one?

4. About the TCXO how to properly connect it (cable to use, ...) to the main board?
I have found the 50MHz version here (https://fr.aliexpress.com/item/50MHZ-hifi-TCXO-0-1ppm-Ultra-precision-Golden-Oscillator-CLOCK-power-supply/32962398016.html?spm=a2g0w.10010108.1000016.1.3d7654acJNShIc&isOrigTitle=true) (several of available).

Thank you

 Sorry about the delay in responding. I had hoped to get the chance to take some photos to post here rather than having to say, as I now am, that I'll post some up as soon as I get another chance to open it up. Right now, I'm rather preoccupied with a little DIY GPSDO project to let me more accurately and swiftly calibrate the 50MHz 0.1ppm TXCO upgrade. As soon as I get the chance, I'll be only too happy to post the photos here and do a little showing off.  :)

JBG

 Well, after finding a remarkably easy fix for the extreme deafness of the on-board patch antenna on my "Ublox-NEO-M8N GPS navigation signal amplify module for arduino Rasppery PI" I bought from here: <https://tinyurl.com/y7ypyhnn> (ordered last Thursday, promised to arrive Tue or Wed, and in my hands the Saturday morning!), which simply consisted of a 14cm length (3λ/4 antenna) of wire poked into the SMA socket, I was able to justify popping the lid of the signal generator to tweak the TCXO module to within a couple of ppb of the 30MHz test signal I was beating against the third harmonic from the GPS module I'd programmed to output 10MHz on its PPS line. I'd already splashed out three quid on a mag mount active GPS antenna with 5 metre cable and the appropriate SMA male connector but I thought I'd have to wait on its delivery later this week before I could start locking onto any satellites, so it was an extremely pleasant surprise when my second attempt to use a simple wire antenna produced such copious quantities of useable satellite signals (10 to 14 decodable sats at any one time - I guess the magic charm was in using a 3λ/4 instead of a λ/4 antenna wire - who'd have thought that extra 10cms would be so important!).  :)

 Anyhow, buoyed up with such joy (and armed with a valid excuse to delve once more into my "Box of Tricks"), I remembered the request for some pictures and set up a photo-shoot. The picture quality could have been better but I was concerned about the file size limits in this EEVBlog forum. Still, I think they'll suffice for an initial look at what I've done to my FY6600.

9493 is a top down view

9499 looking over the front panel towards the rear panel

9501 Attenuator mod to convert from an 85 ohm to a 50 ohm impedance attenuator pad (it still needs more work to get it right though).

9502 XO location, right next to a source of 70 deg C heat (the three regulator chips to the left). The co-ax runs to the module to the left.

9503 The TCXO module mounted at a jaunty 45 deg angle above the fan to both act as a deflector and to remain the coolest item in the whole box so as to keep it within (just!) its 0 to 25 deg C range specified to meet its 0.1ppm rating and to shorten its warm up time.

9504 I needed to move the feet to both clear space to mount the fan but also, (and more importantly - requires the hard rubber feet to be replaced with something far more 'grippy' for best effect) to move them nearer to the back edge so that tilting it up on its tilt stand doesn't leave said feet dangling as the back edge of the case usurps the function of said feet.

 You'll note the additional 8mm dia holes on the LHS of that image to supplement the existing vent slots and the opening up of the rectangular front panel clip retaining aperture just to the right of the leftmost foot near the front panel. You can't tell from that photo since I opened the rectangular aperture by bevelling its sides so as make such enlargement all but invisible to cursory examination. This helps reduce the heat that accumulates under the main board from the opamps's dissipation into the PCB (heat doesn't just choose to leave only via provided heatsinks. Heat's not fussy about how it escapes, It'll go via any and every route possible).

9506 and 9507  are side views to show how the issue with the badly placed rear feet was resolved.

9508 Shows the IEC C6 trefoil mains socket (less of the "Tail Wags Dog" effect risk that the thicker and stiffer C13/14 alternative entails).

9510 Is a shot showing the ducting over the rear vents to put them back into use as an effective contribution to exhausting warmed air instead of having to block them to stop freshly impounded air venting straight out the back unused. Its presence also assisted the deflection provided by the TCXO board in pushing the airflow towards the front from where it could traverse the main board in the region of the heatsinked opamps.

 Regards to all, JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Gege34 on February 06, 2019, 02:06:19 pm
Thank you Johnny B good for the picture.

Where did you put the minus of the TCXO power supply TCXO (it's seems to go the the earth) and why there resistor (and value)?

Have you made any changes on the power supply (except the ferrite)?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 06, 2019, 07:52:14 pm
Thank you Johnny B good for the picture.

Where did you put the minus of the TCXO power supply TCXO (it's seems to go the the earth) and why there resistor (and value)?

Have you made any changes on the power supply (except the ferrite)?

 Hi Gege34,

 I used the co-ax braid for the ground return (-ve) to avoid ground loops. The white wire is the 5v feed picked up from the +5v pin on one of that group of regulator chips. The resistors you can see are a bunch of three 33K resistors in parallel using the -ve screw terminal on the module as a convenient connection point with the other end of the resistors wired to the safety earth pin on the mains socket (it knocks the 90v leakage right down to just under half a volt and neatly avoids mains earth loop issues.

 As far as the smpsu board goes, I've lost count of the number of times I've had it out on the bench for the various modifications I've tried on it. However, the first mod was to wire a 47K across the lower half of the voltage feedback potentiometer formed by the two 10K resistors between the +5v and the 0v rail to boost the 5v to 5.5v in order to raise the 11.5 volts on the "12 volt" rails to somewhere around the 12.7v mark. This wasn't quite enough, even after replacing the weedy rectifier diodes with 20A dual shotky rectifier diodes so I ended up modifying the transformer to add an two extra turns on each end of the 24v centre tapped winding feeding the 12v rails. This raised the voltage to somewhere in the region of 13.7v or so.

 In hindsight, I should have just upgraded all three rectifiers and then added a single turn overwinding to the transformer to buck the 5v winding, forcing the switching IC to compensate and so neatly increase the 12v rails without altering the 5v rail voltage and avoid modifying the transformer since there is ample room to thread (three or four lots in parallel of) the single turn of wire around the existing windings without having to remove the transformer from the PCB as I'd had to in order to to access the ends of the 12v windings in order to unsolder them from their solder tags so as to extend each winding another two turns each.

 Connecting this one turn buck winding is just a matter of lifting the anode end of the 5v diode from the board and connecting the ends in series with the diode's anode and the vacated hole on the PCB. If you connect it series aiding on your first attempt (a matter of dumb luck), all that will happen is that the 12v lines will drop in voltage, leaving the 5v untouched which simply means you need to flip the one turn winding connections round to buck the 5v, forcing the 12v rails to increase in voltage.

[EDIT 2019-03-31]

 I finally got round to undoing the original transformer mod yesterday afternoon to try out the single turn winding to buck the 5v secondary's output voltage as per the above. Not surprisingly, I had to reverse the connections to make it buck the 5v secondary.

 It worked just as I'd hoped it would. However, when it was connected 'aiding' the 5v didn't get above 3.96v (I suspect maybe due to too large a smoothing cap on the 5v rail) leaving the 12v rails  registering just over 8 volts each. Undismayed, I reversed the connections and tried again. getting +4.94v (I'd removed the 47K voltage boosting resistor), -12.98v and +12.83v. I wired in a 200K voltage boost resistor which then gave me +5.07, -13.29 and +13.13 volts which seemed to be close enough to the optimum. I didn't want to go much above the 5v mark in order to reduce the dissipation in those three very hot running LDOs on the main board and the 3.3v LDO on the 50MHz 100ppb TCXO oscillator board itself.

[END_EDIT]

 Adding a single turn overwinding to the transformer (use three or four single turns in parallel for more efficient coupling), avoids leaving any evidence of alteration should you decide to remove it to restore it back to its pristine state and neatly raises the 12v rails without having to raise the 5v rail to achieve a similar result. In this case, it reduces power consumption and hence the waste heat produced by those ghastly regulator chips. The loss introduced by that single turn buck winding is so slight as to reduce the waste heat produced by the PSU itself simply by virtue of the reduced loading on the 5v rail.

 As for the troublesome 'Touch Voltage' leakage introduced by the EMI bodge capacitor (the class Y 1 or 2.2 nF cap), the only effective remedy is to replace the IEC C8  two pin non polarised mains socket with a 3 pin earthed connector, preferably a C6 trefoil type rather than the C13/14 connector to keep the "Tail Wags Dog" effect to a minimum and link the protective/safety earth pin on the socket via a 10K resistor to the chassis ground rail. This will suppress the Touch Voltage without introducing a low impedance mains earth loop.

 This, of course, only applies to the FY6600, the FY6800 is already equipped with a rather brutal C13/14 socket with a full galvanic connection to the earth pin socket bodged into the PSU to Mainboard ribbon cable connector, sacrificing one of the two zero volt rail connections as a result of this bodgery. FY6800 owners might want to fix Feeltech's earthing bodge if only to restore the zero volt rail connection back to its original integrity.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 10, 2019, 05:11:24 pm
I just got a FY6800 60Mhz and I observe, right off the bat, that:

i) Maximum output amplitude of 20V pk-pk for the sine wave is attained only up to around 3Mhz. After that, maximum amplitude is gradually attenuated (12V pk-pk at 10Mhz, 5V pk-pk at 20Mhz, 2V pk-pk at 30Mhz). It seems way out of specs (20V pk-pk up to 10Mhz, 10V pk-pk up to 20Mhz and 5 Vpk-pk after 20Mhz).

ii) At lower amplitides there is a noticeable offset: for example at 1Mhz, 100mV pk-pk I measure a 20mV vertical offset.

Is all this to be expected or did I get a lemon?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on February 10, 2019, 05:46:23 pm
Amplitude attenuation is not normal , but 20Vpp is only available below 20MHz , after that 5Vpp is the maximum allowed .
Maybe you did some simple mistakes in your measurement , like using 20MHz bandwidth limit in your oscillocope ...

The offset can be an issue ... it is possible to be adjusted and calibrated from the pots inside if you read this thread , but is somewhat laborious.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 10, 2019, 05:55:04 pm
Amplitude attenuation is not normal , but 20Vpp is available only below 20MHz , after that 5Vpp is the maximum allowed .
Maybe you did some simple mistakes in your measurement , like using 20MHz bandwidth limit in your oscillocope ...

The offset can be an issue ... it is possible to be adjusted and calibrated from the pots inside if you read this thread , but is somewhat laborious.

I guess I'd better return the damn thing...man...everytime I try to save some money I end up with some crap giving me endless headaches and making me regret not having spent more
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 10, 2019, 09:36:13 pm
 Could the problem lie in the fact that my scope doesn't have 50ohm termination, and I'm using the regular 1Mohm input?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on February 10, 2019, 09:49:09 pm
No, with 50Ohm its only 10Vpp. With high impedance 20Vpp...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 10, 2019, 10:20:51 pm
Ok, I must make some correction to what I wrote. I admit my inexperience in the field so please be gentle with me.

i) I was probing the output from the FY6800 with regular 1x passive probes, connecting the red awg terminal to the probe tip and the black awg terminal to the probe ground. Apparently, this was the cause of the attenuation. Instead, if I use the BNC-BNC connector from the awg directly into the scope, I observe much less attenuation and what I see is in agreement with the specs of the device. Why using regular probes gives me issues?

ii) with low amplitude settings (less than 100mV) I observe more and more dc offset (the lower the amplitude the higher the offset). If I use my scope in AC coupling mode, no offset is observed. Can I consider this a normal behaviour of the device? For your reference, with a sine wave 100mVpp I measure a 10% offset.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on February 10, 2019, 10:47:09 pm
For DC offset my 6600 was off by a bit. Either search the thread or go a page or two either side of this link where there was some discussion about tweaking them while stroking our grey beards with the correct tongue angle ...... Naked or not I will leave it to your imagination  >:D https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1351221/?topicseen#msg1351221 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1351221/?topicseen#msg1351221)

Not a perfect solution but it got mine closer to the truth.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 10, 2019, 10:59:33 pm
And why using scope passive probes to measure the signal I read an attenuated signal from 3Mhz onward, whereas using BNC-BNC cable the signal maximum amplitude is in agreement with specs up to 30Mhz?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on February 10, 2019, 11:12:32 pm
And why using scope passive probes to measure the signal I read an attenuated signal from 3Mhz onward, whereas using BNC-BNC cable the signal maximum amplitude is in agreement with specs up to 30Mhz?

Have a look at this and some of the other W2AEW videos on scopes but basically don't use 1X probes :)

https://youtu.be/SX4HGNWBe5M
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on February 11, 2019, 12:23:37 am
I forgot to mention that tweaking those pots for DC offset could decalibrate the amplitude of the signal , so you have to have a good calibrated AC multimeter or oscilloscope before attemting . This is not for beginers , you have to know what are you doing .
Anyway this offset is best measurable with a DC multimeter ... I would not trust an oscilloscope
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on February 11, 2019, 12:29:12 am
Agreed you can't use the Scope (a few percent accurate) with any real accuracy for this job. I chased mine with my 34401A and sanity checked the results on the scope as the Agilent runs out of legs at 1Meg.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 11, 2019, 03:05:59 pm
Andreax1985,

I've got an FY6800. I set the  waveform to DC on both channel 1 and 2 and connected  up two fairly good DVMs using the croc-clip BNC lead, measuring each channel in turn. Altering the Volts, setting from zero, I found the FY6800 was pretty much spot on, given the expected limitations of the FY6800 and the DVMs with 200mV ranges. I also tried setting the mode to sine, with frequency and amplitude zero, the offset shown on the meters agreed well with the offset set on the FY6800. The offset was probably less than 1mV and certainly nothing like 20mV.

Using a new digital scope I see anywhere between a 1.5 mV and an a 3mV offset using a 100mV amplitude sine at 1MHz. That's almost all down to the scope, which shows an offset with a 50Ohm terminator connected on the BNC input.

I may have a particularly well calibrated FY6800, or I may have caught it when its thermal drift was just right, but I doubt it.

I'm not sure what the specification is for offset. 20mV sounds rather high, but before you send it back, or try to adjust it,  I think you should measure it with a DVM rather than a scope.

Generally I've been impressed with the FY6800, especially for the price. It's got some irritating faults, such as an almost useless sweep function. If you judge it by the standards of a quality RF signal generator, it's not great. If you judge it by the standards of a low distortion audio oscillator, it's a joke. But if you judge it as a function generator, especially against analogue function generators, it's a miracle of modern technology. The other way of judging is is in terms of what else you can get for the same money, and I doubt there's anything much better out there now.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 12, 2019, 12:18:13 am
 The traffic in this thread has all the characteristic of a bus service. You know, you wait at the bus stop for the next one due in 10 minutes and, an hour later, three arrive at once! In this case, it's a week and 11 posts suddenly materialise!  >:(

 Ok, I'm not going to attempt to say who said what, just address the points raised here - as I can recall them - this, sadly, isn't usenet.  :( .

 Firstly, in spite of the extremely low price of these AWGs (6600 and 6800 models), they're surprisingly high spec, comparable in many ways with kit costing some 7 to 50 times more. Secondly, most of their more glaring deficiencies arising from such product design and production techniques aimed at keeping the final price to the minimum possible, can be fixed with fairly trivial component upgrades as described over a year back in this thread.

 Their shortcomings due to every penny pinching trick in the book being applied are to be expected. As others have pointed out, what is remarkable is just how much functionality you're actually getting at such a low price point. However, the cynic in me suggests the penny pinching was inflicted on these AWGs by careful design rather than just the more usual simple mindlessness of letting accountants dictate the design to shave their pennies off the BoM and production line costs.

 When you think about it, these products are clearly aimed at a market dominated by cash strapped hobbyists rather than professionally run high tech businesses, a market demographic made up largely of people prepared to analyse and remedy the worst excesses of Feeltech's penny pinching compromises to demonstrate just how cheaply these "Sows' Ears" can be turned into "Rayon Purses" for the want of careful calibration of presets or replacement of the crappy dual opamp with THS3001s or better, or ripping out the nasty little XO chip to replace it with a TCXO board[1] well clear of the 70 deg C neighbourhood of the original XO location with options to modify or replace the PSU board and maybe even sort out the Skoolboy Howler error of the 85 ohm attenuator pad which Feeltech CBA to correct on the main board, electing instead to use a firmware fix that can only work in the Hi Z case (hopefully, sorted in the FY6800 but that assumption has, to my knowledge, yet to be tested).

 Those unpopulated opamp spots on the main board are a positive incitement to upgrade the single dual opamp chip and, in so doing, neatly void the Chinese warranty, reducing warranty claims or sales returns to an absolute minimum, virtually all but eliminating Feeltech's customer support costs. It's a win win situation all round. Feeltech are supplying not only an extremely affordable item of test gear, it's also a nice little 'fixer upper' project for most of the market demographic this was squarely aimed at. Not only does the end customer get a 'nicely priced' signal generator, he gets a self improvement project all wrapped up in one neat package as well.  :-\

 Let's face it, anyone even so much as contemplating the purchase of such temptingly cheap test gear must at least be of an enquiringly enough mind to further their knowledge of electronics just by virtue of their recognising the need for such an item, no matter how limited its performance and accuracy might be. Remember, even professional test gear has its own limitations which the user has to be mindful of - you just have to be more mindful in the case of Feeltech's products is all.  :)

 Next, we come to the correct use of oscilloscopes, notably the business of 'scope probes. At audio frequencies, the problem of capacitive loading from the 'scope probe lead only becomes an issue when measuring high impedance points in the circuit, a situation more likely to be met in vintage valve (tube) gear, less so in modern solid state kit.

 However, probe lead capacitance becomes a serious issue with MF and and HF frequencies used in radio equipment. The 10x probe setting on the typical standard 'scope probe is the solution to this problem as described in that video (one of the better instructional videos BTW). Even so, the use of unterminated probe leads with 1M ohm/20pF channel amplifier inputs is a bit of a puzzle to me. Unless the probe cable is some special Highish Z high loss cable, I can't see how this can work.

 To explain how the 10:1 20dB lossy probe tip was originally conceived, you need to understand some basic transmission line theory. If you use even a short length of 50 or 75 ohm co-ax to directly connect the RF test point to an oscilloscope's Y channel input, you introduce not only unwanted additional capacitive loading (circa 100pF per meter for 50 ohm co-ax) but also the effects of an unterminated length of transmission line which can represent anywhere from very high impedance to almost a dead short depending on whether a half or quarter wavelength's worth of probe cable is involved.

 Originally, for RF work, the scope input would always be terminated in the probe lead's characteristic impedance, ime, typically 75 ohm. The tip itself was connected to the end of the probe cable using a 675 ohm resistor with a low value trimmer in parallel. The trimmer capacitor was there to match the resistive 10:1 impedance ratio to the same 10:1 probe to cable capacitive ratio. Whilst the probe tip loading of such 10:1 (20dB loss) probes did introduce some additional loading at the test point (a mere 10%), it neatly isolated it from the undesired effects of adding an unterminated length of transmission line which could introduce unwanted ringing from reflections and, at critical frequencies, lead to an effective short circuit loading.

 So, that's the theory behind the (passive) 10:1 (or 100:1 and higher) probe tip as used when probing high frequency signals to display on an oscilloscope. However, as I've already mentioned, the use of 1Mohm with circa 20pF Y amp inputs on modern 'scopes, seems at odds with that basic working principle. The probe tip 9Mohm resistor with a 4pF trimmer follows the same basic principle but it's the lack of termination for the co-axial probe lead itself that leaves me puzzled and I can only guess that the probe lead co-ax must be some special high loss cable designed to eliminate unwanted reflections.

 After reading the wikipedia article here:-  <https://en.wikipedia.org/wiki/Test_probe> , it seems my supposition about the use of special hi impedance lossy co-ax cable with typical passive 10:1 probes normally supplied with modern 'scopes was just about spot on. My knowledge as it related to probing RF frequency amplifier circuits refers to the use of "Lo Z probes".

 You might think that a transmission line (75 ohm co-ax in this case) would need to be terminated at both ends with an impedance matching the cable's characteristic impedance but that's not actually required with a unidirectional signal flow. It's only the receiving end that needs to be matched to eliminate unwanted signal reflections and standing wave voltages. The signal source in this case can be anything from zero to infinite (constant current) ohms. the probe end of the cable will still look like a 75 ohm impedance regardless, provided the scope end remains properly terminated.

 Matching the amplifier's output impedance to that of the load is purely a matter of maximising the coupling of its output energy into the load. A properly terminated cable, no matter how long, will always look like a resistive load equal in ohmic value to that of its matched characteristic impedance. Indeed, the longer the cable, with consequently greater loss, the more accurate the match to its characteristic impedance it will have until, given a long enough cable length and therefore attenuation, the termination impedance becomes totally irrelevant (eg 50dB loss becomes a 100dB attenuation of any energy reflected from an open or short circuit load at the far end.

 Anyway, here's the 'thing'. Unless you're dealing with lengths of 50 ohm co-ax shorter than a tenth of a wavelength of your signal generator's output frequency between the generator and the 'scope input socket, as well as the capacitive loading effect of the cable, you're going to see the effect of unterminated transmission line reflections introducing variations in the voltage levels at the 'scope input unless you introduce a 50 ohm terminator at the scope end of the cable (either a built in option on the 'scopes Y input socket or the use of a through line terminator or a T adapter with a 50 ohm terminator plugged into it).

 If you want to have some fun, checking the frequency response of your FY6800 using  just a standard unterminated RG58 BNC lead, try various lengths of such leads (2, 5 and 10 metre lengths being typical offerings available) and you can observe the response peak at frequencies corresponding to odd numbers of quarter wavelengths of the test frequencies being used.

 If, after using the correct methods of measuring the performance of the FY6800, you still feel it falls way short of its advertised specification, you'd be well advised to return it, unmodified in any way, as "Not as described" to get a full refund and look to spending, for example, some 600 quid on a Siglent SDG2082X Signal Generator


[Notes]

[1] This  is a fine example of just how cheap the FY6600 is compared to the 120MHz (sine wave) dual channel Keysight AWG when it comes to upgrading their original XO references (admittedly, the Keysight reference XO was far superior to that of the Feeltech's to begin with) to 0.1ppm TCXO modules.

 For a mere 23 quid and a modest investment of my time, I was able to do the same upgrade that would have cost 700 quid as a return to factory upgrade option for the Keysight. The cost of the Keysight TCXO upgrade alone was nine times more than what I'd originally paid for the FY6600 in the first place!

 JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on February 12, 2019, 02:01:58 am
Could the problem lie in the fact that my scope doesn't have 50ohm termination, and I'm using the regular 1Mohm input?

yes, it will leads to unmatched RF line. So your coax cable will turn into RF transformer, which transformation ratio will depends on wave length, cable length, input impedance and cable impedance. The shorter the wavelength (the higher the frequency), the higher measurement error you will get.

For low frequency (long wavelength) it doesn't play a big role, since wavelength is much longer than cable length, so measurement error will be too small. But for higher frequency (more than 2-5 MHz), the error will be noticeable. For more than 7-10 MHz you cannot use 1 m unmatched line (I think you're used 1m cable to connect oscilloscope), because measurement error will be too high.

For high frequency you're need to add pass-through terminator at the oscilloscope input, in order to avoid the standing waves effect on measurement result. This terminator should be the same value as cable impedance. I think you're using 50 Ohm cable, so you're need to use 50 Ohm pass-through terminator at oscilloscope side. This is needed to match your RF line.

Without this termination you will get random amplitude on oscillsocope. And this random amplitude will depends on frequency and cable length.

And this is why generator output should be 50 Ohm impedance and calibrated for 50 Ohm impedance. Otherwise you will not be able to predict amplitude on the 50 Ohm cable end.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on February 12, 2019, 07:46:19 am
It is not the lack of 50ohm termination the cause , with 1Mohm impedance oscilloscope ( used correctly )the output of FY6600 is allmost flat until 60MHz ...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 12, 2019, 09:57:31 am
I did some testing. Here's what I got:

i) If I use my multimeter and set the FY6800 to DC I get almost perfect agreement at all voltage levels (+/- 2%, but my multimeter is a 15euro unbranded device, so nothing to heavily rely upon).

ii) If I use my DSO (Siglent 1104X-E, 1M input) with 1X probe onto the FY6800 BNC input, I get attenuation starting from 3MHz onward, but this is to be expected. Every 1X probe is strongly bandwidth limited.

iii) If I use my DSO (1M input) with 10X probe onto the FY6800 BNC input, I get no attenuation until 60Mhz. I observe a 10mV DC offset.

iv)  If I use my DSO (1M input) with the BNC-BNC cable supplied with FY6800, I get slight attenuation at higher frequencies (as expected, I think, from this kind of cable), and only slight 1-2mV DC offset (as experienced by Zenith).

So: are my probes (or my DSO) not so good? Should I get better quality 10X probes?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 12, 2019, 12:39:39 pm
Andreax1985,

I redid the measurements using my Siglent SDS 1102CML+.

I had the scope do its auto calibration. I set both channels to 2mV/div and  set acquisition to averaging over 16 readings (which gets rid of rapid fluctuations in readings) then called up all voltage measurements. Channe1 1 gives Vpp of between 0.08mV and a mean of -0.08mV. Channel 2 gives Vpp between 0.16mV and 0.24mV with mean between 0.00mV and -0.08mV. The scope looks as if it only deals in voltage steps of 0.08mV on that range.

A 10mV, 0.000mV offset, 100KHz  sine from channel 2 of the FY6800 gives a Vpp of 9.4mV and a mean of 1.04mV. Changing the coupling on the scope to AC gives a Vpp of 9.4mV and a mean of zero. Changing back to DC and setting the offset on the FY6800 to -0.001V changes the mean to -0.016mV. Changing the amplitude on the FY6800 to 100mV and offset zero, gives Vpp 0f 102mV and a mean of 1.6mV. A square wave produces near identical results. Note that the mean doesn't change much with amplitude.

I'm inclined to believe that the output of the FY6800 has an offset of about 1mV and that maybe the waveform isn't quite symmetrical, but these are measurements on the limits of what both the scope and DVMs can do. The offset is nothing to worry about, in fact it's pleasantly small, and it's certainly not worth trying to adjust it down further. It seems as if your FY6800 has a similar small offset. If you have some particular need to get the offset down further, you can reduce it by setting the offset on the FY6800.

I had doubts about the 100MHz probes which came with the Siglent, so I compared them against an HP10040A probe using an HP8640A sig gen. The conclusion I came to is that the supplied probes are up to the job. Sometimes they need wiggling so they make a good contact. Top flight probes are nice, but expensive. From what you've said, I think you should spend the money on a better DVM instead.

Generally, I've found my Siglent scope to be surprisingly good and well worth the money, although it has the odd quirk. There's no doubt if you pay more, you get a more capable scope, but I see no need to sell mine and get a better one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on February 12, 2019, 12:45:23 pm
iii) If I use my DSO (1M input) with 10X probe onto the FY6800 BNC input, I get no attenuation until 60Mhz. I observe a 10mV DC offset.

This is because your oscilloscope probe has circuit to correct impedance mismatch on both sides of probe cable. And standing waves in the cable doesn't affect measurement. Because probe designed to work in such way.

iv)  If I use my DSO (1M input) with the BNC-BNC cable supplied with FY6800, I get slight attenuation at higher frequencies (as expected, I think, from this kind of cable), and only slight 1-2mV DC offset (as experienced by Zenith).

This slight attenuation appears because your cable isn't terminated properly and you're see effect of increasing/decreasing amplitude due to standing waves in the cable. These standing waves appears due to reflections from non-matched cable end. When there are standing waves in the cable, your amplitude measurements will depends on the cable length and wavelength of signal. So, if you will increase frequency, or reduce cable length the amplitude will be changed.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 12, 2019, 02:30:26 pm
Thanks! And why DC offset is higher with X10 probe than with the unterminated BNC-BNC cable?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on February 12, 2019, 03:30:24 pm
The DSO is switching ranges between 1:1 and 1:10 ( and it is not the simple divider found in multimeters ) , so it is not the cable ... thats why I said don't trust the oscilloscope for small offsets.
But you can investigate this by using a small DC variable voltage , a battery and a potentiometer for example .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 12, 2019, 07:14:25 pm
Andreax1985,

I redid the measurements using my Siglent SDS 1102CML+.

I had the scope do its auto calibration. I set both channels to 2mV/div and  set acquisition to averaging over 16 readings (which gets rid of rapid fluctuations in readings) then called up all voltage measurements. Channe1 1 gives Vpp of between 0.08mV and a mean of -0.08mV. Channel 2 gives Vpp between 0.16mV and 0.24mV with mean between 0.00mV and -0.08mV. The scope looks as if it only deals in voltage steps of 0.08mV on that range.

A 10mV, 0.000mV offset, 100KHz  sine from channel 2 of the FY6800 gives a Vpp of 9.4mV and a mean of 1.04mV. Changing the coupling on the scope to AC gives a Vpp of 9.4mV and a mean of zero. Changing back to DC and setting the offset on the FY6800 to -0.001V changes the mean to -0.016mV. Changing the amplitude on the FY6800 to 100mV and offset zero, gives Vpp 0f 102mV and a mean of 1.6mV. A square wave produces near identical results. Note that the mean doesn't change much with amplitude.

I'm inclined to believe that the output of the FY6800 has an offset of about 1mV and that maybe the waveform isn't quite symmetrical, but these are measurements on the limits of what both the scope and DVMs can do. The offset is nothing to worry about, in fact it's pleasantly small, and it's certainly not worth trying to adjust it down further. It seems as if your FY6800 has a similar small offset. If you have some particular need to get the offset down further, you can reduce it by setting the offset on the FY6800.

I had doubts about the 100MHz probes which came with the Siglent, so I compared them against an HP10040A probe using an HP8640A sig gen. The conclusion I came to is that the supplied probes are up to the job. Sometimes they need wiggling so they make a good contact. Top flight probes are nice, but expensive. From what you've said, I think you should spend the money on a better DVM instead.

Generally, I've found my Siglent scope to be surprisingly good and well worth the money, although it has the odd quirk. There's no doubt if you pay more, you get a more capable scope, but I see no need to sell mine and get a better one.

 I bought my Siglent SDS 1202X-E from their UK agent (Labtronix, if anyone's interested) a lttle over 3 months ago as a result of my attention being drawn to this thread by a usenet posting into SED. It was the startling revelation of the amazingly low prices for brand new modern T&M kit that prompted me to replace my very neglected "Boat Anchor" 'scope and sig generator with high performance replacements I could carry around one handed.

 A week after getting hold of the 'scope, I realised I needed a signal generator to complement it so seriously contemplated Siglent's SDG1032X (just a fiver shy of the 365 quid I'd already shelled out on the 'scope). When I compared the specs, I realised I could get a poor man's version (the FY6600) which offered similar features (some better, others not quite so good) for just 21% of the SDG1032X's asking price, so re-read the whole of this thread... (twice!) before placing an order with a Chinese supplier who held stock in the UK and less than a week later, I had myself an AWG of my own. From then on it was downhill into the depths of DIY electronics improvement.  :-\

 As you've noted with the supplied 'scope probes, they leave a little to be desired (certainly with regard to their BNC adapter tips) but aside from that niggling shortcoming, they (and the 'scope itself) appear to meet their specifications just fine. Of course, as I've pointed out several times here and elsewhere, all test kit has limitations, even the expensive kit costing ten to a hundred times more.

 With regard to the limited resolution of the voltmeter function, that's inherent to the 8 bit high speed ADCs used in these DSOs to capture the signal waveforms. With only 8 bits resolution, you're only going to see a maximum of 256 steps (twos complement signed integer - -128 to +127) in the Y axis of the 'scope's display. The ENOB setting using oversampling can extend the resolution by another 1 to 3 bits but that introduces a compromise which may or may not be acceptable depending on which aspects of the waveform you're trying to examine.

 Luckily, for the purpose of displaying a waveform on the screen, this is generally ample resolution. Even luckier in the case of DSOs, if you need to see finer detail, you can alter the gain and dc offset so as to concentrate the view over a limited Y axis range of interest in the waveform. However, as I've already mentioned, this technique has its limits and is yet another compromise (one, however, which does extend the capability beyond that of the traditional CRT based scope).

 Although my FY6600 has some DC offset, it's mercifully only a matter of a millivolt or so in the sub 500mV range (the range where that silly 85ohm pad is switched into the output circuit) and still low enough to be insignificant at the higher output ranges so I've never been tempted to tweak the trimmers (let sleeping dogs lie undisturbed lest they bite you in the bum). I may have a go at trimming out such residual offsets later on when I'm better tooled up to make sense of any such adjustments but, for now, they're not a problem and I don't see any benefit in taking the risk of making things worse.  ;)

 Being mindful of what I'd said in my previous post about the impedance of the generator being immaterial when driving a load matched to the impedance of the connecting transmission line (in this case, a 50 ohm dummy load hanging off the BNC T adapter plugged into the 'scope's Y channel input socket using the very short 50 ohm BNC patch lead supplied with the FY6600), I've just checked the frequency response of my FY6600 and see 74 and 75 percent of the amplitude (or, in this case, the Peak to Peak) at the 60MHz limit compared to the amplitude produced at 1MHz (the 100KHz amplitude was just a tiny fraction higher by way of a sanity check).

 This is less than the 29% drop associated with the -3dB bandwidth point of 70.70707% voltage amplitude. Since this frequency is well within the 'scope's claimed 200MHz bandwidth, it would seem that my FY6600 example comfortably meets its own bandwidth specification. However, I'm just waiting for the half hour screen saver setting to time out before running the self calibration routine to repeat those tests (which event has occurred just now). I'm now waiting for the self calibration to complete and I can then repeat the bandwidth test...

 I've gotten pretty well the same figures on both channels of the generator and ditto for the 'scope channels, doing only one channel at a time. If anything, there seems to be a slight discrepancy with the 'scope's frequency response where it rises slightly below the 1MHz mark on the Y2 channel compared to the Y1 channel. Just a small fraction of a dB, nothing to get worked up about.

 All in all, the FY6600 seems to be performing to its specification on sine wave bandwidth at least. Since the PSU, opamp and TCXO mods, it now exceeds its original DC offset/signal clipping limits and frequency stability capabilities (and the impedance mismatch below the 500mV setting isn't quite so shabby as it originally was - 45 ohm versus the original 85 ohm, whilst still not ideal, is a noticeable improvement just the same).

 Since the FY6800 is essentially a revamped FY6600, I'd expect that to likewise exceed its sine wave output bandwidth claims, barring any out of the ordinary manufacturing defects (they have enough ordinary cost cutting induced deficiencies to begin with).

 I've only addressed the matter of the frequency bandwidth aspect, ignoring the question of output voltage level calibration which seems to be within +/- 10% (according to my 'scope which, for the moment I'm assuming to be within its own +/-3% tolerance range - ICBA to knock up a simple peak voltage detector using a point contact diode to sanity check the voltage levels right now).

 It's all too easy to obtain misleading results when checking out such kit when you overlook the transmission line effects of the connecting cables at radio frequencies and neglect the need to terminate the cables with a resistive impedance matching that of the cable (50 ohm dummy loads with 50 ohm BNC cables). It's also worth keeping in mind the limitations of your test and measuring equipment (DSOs don't, for example, make a very good substitute as a digital voltmeter).

 If you're seeing unexpected results when checking out new kit, it's more than likely you have overlooked something vital like properly terminating a test cable. Take a pause from what you've been doing and consider the possibility that you've overlooked something in your test setup before concluding you have been 'sold a pup'.  If that doesn't resolve the issue, you can always seek advice from any technical discussion group, whether it's EEVBlog or a usenet group just as Andreax1985 has done in this case. There's nothing wrong in seeking expert advice or a second opinion from your peers.

JBG

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on February 12, 2019, 08:55:53 pm

 If you're seeing unexpected results when checking out new kit, it's more than likely you have overlooked something vital like properly terminating a test cable. Take a pause from what you've been doing and consider the possibility that you've overlooked something in your test setup before concluding you have been 'sold a pup'.  If that doesn't resolve the issue, you can always seek advice from any technical discussion group, whether it's EEVBlog or a usenet group just as Andreax1985 has done in this case. There's nothing wrong in seeking expert advice or a second opinion from your peers.

JBG

I'd like to add that if you are using cables and connectors which are not *known* to be good you give that careful scrutiny.  I bought 10x 50 ohm BNC jumpers on eBay, 5x from two sellers.

When I plugged them into my 8560A and swept them with the TG there was a sharp notch around 50 MHz on all the cables.  So I cut one open.  Despite being screw on shield clamp connectors, the OEM had twisted the braid and soldered it at one point.  So except for use as a power feed for my RF Design RFD 2305 they are useless because the notch is not even stable.

So regardless of price, buy at least 1 or 2 name brand devices of anything so you have a reference to compare to.  But watch out.  Chinese SMA-M connectors are known to often have out of spec pins which are oversize. So if you connect one to a good quality SMA-F it's destroyed.

The only way to address that that I can think of at the moment is to buy a Pasternak or similar SMA-F and
 mount it with a little spring scale so you can push it into a Chinese SMA-M and if the SMA-M is oversize the spring scale will warn you to throw it away.  If anyone knows of a source of steel gauges for checking connectors please post a link.

All cheap Chinese connectors, adaptors and cables have to be swept over the intended operating range on receipt.  I didn't believe it was as bad as it is, but I now have personal experience and an unknown amount of scrap metal bought at inflated prices.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on February 13, 2019, 12:56:49 am
And why DC offset is higher with X10 probe than with the unterminated BNC-BNC cable?

Let's assume that generator output impedance is 50 Ohm, and we set it's output to 1 Vpk on 50 Ohm load. It means that we have 0.5 divider, because input and output impedance is the same = 50 Ohm. So Vpk on Hi-Z load (no load) will be 2 Vpk.

For 1 MOhm oscilloscope with BNC-BNC cable, there is 1000000/(1000000+50) = 0.99995 divider and we will have Vpk1MOhm = 2 * 0.99995 = 1.9999 V.

For 10 MOhm with x10 probe, there is 10000000/(10000000+50) = 0.999995 divider and we will have Vpk10MOhm = 2 * 0.999995 = 1.99999 V.

The difference is 1.99999 - 1.9999 = 90 uV. You cannot measure so low difference with oscilloscope.

So, I think this is definitely related with RF interference and oscilloscope accuracy, because 10 MOhm input is more sensitive for RF interference, than 1 MOhm input. And there are other issues that may affect on the result, because 10 mV is too small value on the background of oscilloscope and probe accuracy.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on February 13, 2019, 01:10:18 am
All cheap Chinese connectors, adaptors and cables have to be swept over the intended operating range on receipt.  I didn't believe it was as bad as it is, but I now have personal experience and an unknown amount of scrap metal bought at inflated prices.

yes, I completely agree. Also it's better to avoid these "golden plated" yellow SMA, because they tinned with thin foil of some unknown metal (it's probably titanium nitride or something like that) and it peels off and contaminates the connectors. It's better to buy Chinese "nickel-plated" SMA, because it's much better - it has better contact and don't contaminates the connectors with small pieces of titanium nitride.

Also I noticed that all RF things sold on aliexpress has much worse specs than it's claimed on product description page. You can divide all specified dB at least by half. :)

I also bought 1 meter LMR195 cable with PL239 connectors and get SWR=1.2 on 27 MHz with this cable!
For comparison I have SWR=1.01 with the same conditions on 1 meter of RG58 cable.
I even don't have idea why it has so high SWR, there is just 1 meter of cable...
I tried to heat connectors of this cable with soldering iron (I think there is a bad contact somewhere), but it doesn't helps.
The seller sent me replacement, but it has the same bad SWR.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on February 13, 2019, 03:24:52 am

The thing that *really* makes me mad is the US owned the electronics industry after WW II. And we *gave* it to the Chinese so that a small number of people could accumulate more money than they can ever spend.

We taught the Chinese how to do it *and* paid for the factories!

The USA has done more for the benefit of the Chinese than it has for its own people.  All so a few people could add digits to 9 figure bank accounts. I am proud that we have raised the standard of living in China, but I am disgusted that this was done to the detriment of many for the benefit of a few.

Given the disasters of the "Great Leap Forward" and the "Cultural Revolution"  and the long history of abuse and exploitation of the Chinese by Western countries the Chinese population deserved help.  But not at the expense of bankrupting the American public.

We need an analogue to Shenzen in the US. Silicon Valley was at one time, but now almost nothing is made in the US.  And if you're not working for a big corporation, you can't obtain exotic parts.  In Shenzen, you just wander to the right part of town and anything you want is available at good prices in quantities from 1 to 1 million.  They give you a good deal on 1 in hopes you'll succeed and buy 1 million.

But we all get what we deserve whether we want it or not, either as individuals or members of a group.  Sometimes this is as punishment and sometimes it's a blessing.  Which is always ambiguous and depends entirely upon what we do next.

I hope Dave and Simon will forgive my transgression.  But I really feel this needed to be said.  The Western world transferred opportunity to China so the rich could become even richer.  Just because they only care about their position in the Forbes rankings.  Personal reputation is just another  commodity they buy from a PR firm.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on February 13, 2019, 04:23:26 pm
O dear... I thought American people have no clue they were doing this... Considering they keep doing it after they realize the mess they're in...  It's sad.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 13, 2019, 04:30:39 pm

 I bought my Siglent SDS 1202X-E from their UK agent (Labtronix, if anyone's interested) a lttle over 3 months ago as a result of my attention being drawn to this thread by a usenet posting into SED. It was the startling revelation of the amazingly low prices for brand new modern T&M kit that prompted me to replace my very neglected "Boat Anchor" 'scope and sig generator with high performance replacements I could carry around one handed.

I hadn't taken much interest in electronics for about five years. The scope I used most was a Tek 475 which is a beautiful instrument, but it's failed and I've had to fix it a couple of times and it's a bit big. I really ought to get a scrapper as a spares mine, as some of the parts are becoming hard to find. The same as you, I looked around and found that DSOs had come of age were quite cheap, also CRT based scopes are disappearing from the market.

I bought the Siglent for about £275 because 100MHz is enough for most things, and the Tek goes to 200MHz if needed. The Siglent offers a lot for the money, but most importantly, they seem to have a good reputation for reliability. I might have spent more and bought one with higher bandwidth, protocol decoding and four channels, but I don't find myself hankering after that. The only real problem is that sometimes it becomes confused and only shows what looks like a distorted 50Hz signal, but the Default Setup button clears that.  The manual could easily be better.

A week after getting hold of the 'scope, I realised I needed a signal generator to complement it so seriously contemplated Siglent's SDG1032X (just a fiver shy of the 365 quid I'd already shelled out on the 'scope). When I compared the specs, I realised I could get a poor man's version (the FY6600) which offered similar features (some better, others not quite so good) for just 21% of the SDG1032X's asking price, so re-read the whole of this thread... (twice!) before placing an order with a Chinese supplier who held stock in the UK and less than a week later, I had myself an AWG of my own. From then on it was downhill into the depths of DIY electronics improvement.  :-\
I have a number of signal generators and a couple of analogue function generators. I bought the FY6800 largely because I wanted a sweep generator for the visual alignment of the IF stages of valve comms receivers. I've never seen much in the way of sweep generators on the second hand market. I've come across various wobbulator projects, but they seem limited and a lot of trouble for not much. The analogue function generators won't cut it. I could just cut to the chase and buy a spectrum analyser with tracking generator, but it seems a lot to pay for the amount I'd use it. Apart from that the FY6800 is a nice, compact and versatile signal source. Function generators are things I've always regarded as handy, but rough and ready. The FY6800 by comparison with analogue function generators, is very accurate and very stable.

The sweep function on the FY6800 looks like a marketing feature. No output sweep waveform, not even a sync pulse and you can't supply a sweep. Not much use really, unless I've overlooked something.

The VCO function is getting there, but it's not quite linear, so it would involve a custom non-linear sweep to compensate, which can be done. Here, the desperately bad PC software has enough functionality to be able to load a text file created by a program and load it as an arbitrary waveform. Also the VCO, on my FY6800 does not work from 0 to 5V, it works from around -0.9V to about 5.3V. A lot of effort to get it to work, but practical.

The FM function seems to work extremely well and is the answer. Using an 11 step staircase sweep arbitrary waveform created via a C program and the ropy PC software, and a frequency counter says that that for a sweep from 400KHz to 500KHz, all the points are where they should be to within close limits. Furthermore the modulation source can be Ch2 routed internally, so there isn't the slight nuisance of using a cable to connect to the VCO connector. I think it will do what I want.

It's this thing all over, like the 85 Ohm pad, the rubbish software and all the rest. It's a mixture of the outstanding for the price, and ridiculous failings caused by extreme penny pinching or thoughtlessness.

As you've noted with the supplied 'scope probes, they leave a little to be desired (certainly with regard to their BNC adapter tips) but aside from that niggling shortcoming, they (and the 'scope itself) appear to meet their specifications just fine. Of course, as I've pointed out several times here and elsewhere, all test kit has limitations, even the expensive kit costing ten to a hundred times more.
The probes are justifiably described as 100MHz and they were thrown in with the scope.  There are limits to what you can reasonably expect for a certain price. I don't know what Keysight, LeCroy and Co., throw in as probes. A pair of decent quality leads for an inverter welder will cost £40 and up. Cheap to moderately priced welders come with leads which are grudgingly up to the job. Expensive models often come with no leads, because "our customers are very discerning as to leads and electrode holders and prefer to source their own". Penny pinching IMHO.

With regard to the limited resolution of the voltmeter function, that's inherent to the 8 bit high speed ADCs used in these DSOs to capture the signal waveforms. With only 8 bits resolution, you're only going to see a maximum of 256 steps (twos complement signed integer - -128 to +127) in the Y axis of the 'scope's display. The ENOB setting using oversampling can extend the resolution by another 1 to 3 bits but that introduces a compromise which may or may not be acceptable depending on which aspects of the waveform you're trying to examine.

 Luckily, for the purpose of displaying a waveform on the screen, this is generally ample resolution. Even luckier in the case of DSOs, if you need to see finer detail, you can alter the gain and dc offset so as to concentrate the view over a limited Y axis range of interest in the waveform. However, as I've already mentioned, this technique has its limits and is yet another compromise (one, however, which does extend the capability beyond that of the traditional CRT based scope).
Scopes don't make great voltmeters, despite what teachers said in A Level Physics years ago,  but the feature on digital scopes is damned convenient and by playing with the offset as you describe, they can produce better resolution. For instance, I have a Li-ion battery that a meter says is at 3.98V. Casually checking with the scope gives between 3.92 and 4.00. Averaging gives 4.00. increasing V/Div and putting in an offset of 3.0V and the scope says 3.98V, but it's a bit of messing around. If you used an analogue scope to do the same, you'd probably say it's at 4V, rather than 3.8 or 4.2 and leave it at that, as a quick and dirty measurement. One feature I'd like to see on this scope is a coarse vertical shift control setting.

The number of digits after the decimal point offered by digital scopes and instruments like the FY6800 tend to seduce you into taking them at face value, but when you look closer, it's different story.



 Although my FY6600 has some DC offset, it's mercifully only a matter of a millivolt or so in the sub 500mV range (the range where that silly 85ohm pad is switched into the output circuit) and still low enough to be insignificant at the higher output ranges so I've never been tempted to tweak the trimmers (let sleeping dogs lie undisturbed lest they bite you in the bum). I may have a go at trimming out such residual offsets later on when I'm better tooled up to make sense of any such adjustments but, for now, they're not a problem and I don't see any benefit in taking the risk of making things worse.  ;)

A 100mV ptp unterminated signal is reduced to about 39mV when a 50 Ohm terminator is added. That's consistent with an 85 Ohm output impedance. A relay cuts in at over 500mV and the ptp on the scope jumps up to half the ptp given by the FY6800, so the silly 85 Ohm pad is still there.

It's my experience that messing about trying to get rid of something like a 1mV offset, which you can live with, is likely to end in tears. You adjust the pot and get 15mV, then adjust it and get -11mV, then with safecracker fingers you can dot around zero, but never hit zero, and eventually settle for something over -2mV, which is worse than when you started. Then you can break something, involving much more work, or you find that the offset drifts over time because of thermal effects etc.


Being mindful of what I'd said in my previous post about the impedance of the generator being immaterial when driving a load matched to the impedance of the connecting transmission line (in this case, a 50 ohm dummy load hanging off the BNC T adapter plugged into the 'scope's Y channel input socket using the very short 50 ohm BNC patch lead supplied with the FY6600), I've just checked the frequency response of my FY6600 and see 74 and 75 percent of the amplitude (or, in this case, the Peak to Peak) at the 60MHz limit compared to the amplitude produced at 1MHz (the 100KHz amplitude was just a tiny fraction higher by way of a sanity check).

I have a collection of BNC patch leads, terminators and I usually terminate things properly. Are we going to see much in the way of transmission line effects with a 100KHz signal and about 1 metre BNC cables?

This is less than the 29% drop associated with the -3dB bandwidth point of 70.70707% voltage amplitude. Since this frequency is well within the 'scope's claimed 200MHz bandwidth, it would seem that my FY6600 example comfortably meets its own bandwidth specification. However, I'm just waiting for the half hour screen saver setting to time out before running the self calibration routine to repeat those tests (which event has occurred just now). I'm now waiting for the self calibration to complete and I can then repeat the bandwidth test...

 I've gotten pretty well the same figures on both channels of the generator and ditto for the 'scope channels, doing only one channel at a time. If anything, there seems to be a slight discrepancy with the 'scope's frequency response where it rises slightly below the 1MHz mark on the Y2 channel compared to the Y1 channel. Just a small fraction of a dB, nothing to get worked up about.

 All in all, the FY6600 seems to be performing to its specification on sine wave bandwidth at least. Since the PSU, opamp and TCXO mods, it now exceeds its original DC offset/signal clipping limits and frequency stability capabilities (and the impedance mismatch below the 500mV setting isn't quite so shabby as it originally was - 45 ohm versus the original 85 ohm, whilst still not ideal, is a noticeable improvement just the same).

 Since the FY6800 is essentially a revamped FY6600, I'd expect that to likewise exceed its sine wave output bandwidth claims, barring any out of the ordinary manufacturing defects (they have enough ordinary cost cutting induced deficiencies to begin with).
As far as I can tell after checking with an HP8640A sig gen, which has not been calibrated for many years, this scope exceeds the maker's bandwidth claim and I recall was pretty much flat up to about 60MHz. According to the scope the FY6800 is 1.7dB down at 60MHz and 1.1dB down at 40MHz. I find that remarkable for a unit at this price.

I must look into the the PSU, opamp and TCXO mods. There's something about this contraption that starts the urge to tinker. I think it's because in some ways it's outstanding, but it's got so many daft faults. It's a bit like the £3 radio sold in SuperDrug a few years back. People started reverse engineering it and fitting product detectors and so on. There was also an astronomical telescope sold by Lidl for about £50, which had people doing detailed investigations and finding various ways to improve it.

I've only addressed the matter of the frequency bandwidth aspect, ignoring the question of output voltage level calibration which seems to be within +/- 10% (according to my 'scope which, for the moment I'm assuming to be within its own +/-3% tolerance range - ICBA to knock up a simple peak voltage detector using a point contact diode to sanity check the voltage levels right now).

 It's all too easy to obtain misleading results when checking out such kit when you overlook the transmission line effects of the connecting cables at radio frequencies and neglect the need to terminate the cables with a resistive impedance matching that of the cable (50 ohm dummy loads with 50 ohm BNC cables). It's also worth keeping in mind the limitations of your test and measuring equipment (DSOs don't, for example, make a very good substitute as a digital voltmeter).

 If you're seeing unexpected results when checking out new kit, it's more than likely you have overlooked something vital like properly terminating a test cable. Take a pause from what you've been doing and consider the possibility that you've overlooked something in your test setup before concluding you have been 'sold a pup'.  If that doesn't resolve the issue, you can always seek advice from any technical discussion group, whether it's EEVBlog or a usenet group just as Andreax1985 has done in this case. There's nothing wrong in seeking expert advice or a second opinion from your peers.

JBG

I started messing with this after seeing Andreax1985's problem with the offset, which seemed a lot to me. I'm fairly new to DSOs and looked into it in a fairly lazy way, using the cursors, forgetting to force the scope to recalibrate first. The DVMs with a DC waveform (which I've found useful) showed an offset of under 1mV. I assume the offset is independent of the waveform. Returning to it with the scope and proceeding more carefully and using the voltage measurements, it seemed to be about 1mV. I learned something about the scope and the FY6800, and I hoped my observations were useful to Andreax1985, at least in that he didn't send back a sig gen which was behaving as expected.

It's my experience that when investigating things with a scope on its highest sensitivity range, you can see strange things, like differences between two BNC patch cables of the same length. That's at DC. It wouldn't take much say, by way of a voltaic effect to do it. Cheap Chinese BNC cables are definitely suspect.

EEVBlog looks like a thriving community full of knowledgeable people and I shan't hesitate to either ask advice or give advice when I think I have something to contribute.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 13, 2019, 10:54:23 pm
Thanks all for your suggestions, a lot of food for thought. So I did some further testing and I gathered the following evidences:

FY6800 set to DC, 10.0mV output. Here my measurements:

i) My cheapo digital multimeter: 9.5mV
ii) My DSO using a (cheap) direct BNC-BNC coaxial cable: 11.49mV
iii) My DSO using a (cheap) 1X probe, clipping the probe ground lead to FY6800 CH1 BNC ground and touching the FY6800 CH1 BNC signal lead with the probe tip: unable to get a stable measure, I read from 16 to 23mV, depending on where exactly I clip the probe ground lead on FY6800 CH1 BNC ground.

FY6800 set to DC, 0.0mV output. Here my measurements:

i) My cheapo digital multimeter: 0.2mV
ii) My DSO using a (cheap) direct BNC-BNC coaxial cable: 1.70mV
iii) My DSO using a (cheap) 1X probe, clipping the probe ground lead to FY6800 CH1 BNC ground and touching the FY6800 CH1 BNC signal lead with the probe tip: unable to get a stable measure, as before

Questions:

1) Method iii) appears totally unreliable: why?
2) First thing that comes to my mind is that if my multimeter is right, my scope has around 2mV DC offset (which, btw, is within the specs). But then why, if I switch off FY6800, the scope correctly measures around 0.1mV (whereas when FY6800 is on and set to DC 0.0mV the scope reads 2.10mV)??
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 14, 2019, 01:23:55 pm
I see much the same. Try lengthening the earth lead from the probe with a jumper and you get some really strange results. The answer is that although it's easy to assume that ground is ground and all at the same potential, but conductors act as antennas and the longer they are, the more RFI and induced voltages they can pick up. If you are looking at the waveforms produced by a 555 oscillator at a few volts it doesn't matter, but if you are looking at low level signals, you have to pay attention to earthing and ground loops. There's a reason why they include the little spring earth connector with scope probes and there are Tektronix technical notes on probing.

As for using a DVM with unshielded leads connected to a BNC/croc clip cable, that's not really ideal for looking at voltages of around 1mV. We have to work with what we have and it seems to work fairly well, but if there are a few inconsistencies we shouldn't be surprised.

I've also noticed that it's as well to self-calibrate the scope regularly. Every time it recalibrates the no signal levels can be very slightly different. Don't forget that we are talking about measuring voltages towards the limits of what the scopes and normal, cheap DVMs can do.

What I have seen is that sometimes the FY6800 gives about a 13mV offset according to the DVM. The scope shows the same as a mean of about 13mV with a noisy waveform superimposed. The noisy waveform has spikes at around 65KHz. Powering off the FY6800 for a minute then powering it up clears it and it returns to having an offset of around 1mV. It reminds me of your original post about a 20mV offset and it looks like a definite flaw in the product. I wonder if it's been covered somewhere in this long thread.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 14, 2019, 01:37:24 pm
I see much the same. Try lengthening the earth lead from the probe with a jumper and you get some really strange results. The answer is that although it's easy to assume that ground is ground and all at the same potential, but conductors act as antennas and the longer they are, the more RFI and induced voltages they can pick up. If you are looking at the waveforms produced by a 555 oscillator at a few volts it doesn't matter, but if you are looking at low level signals, you have to pay attention to earthing and ground loops. There's a reason why they include the little spring earth connector with scope probes and there are Tektronix technical notes on probing.

As for using a DVM with unshielded leads connected to a BNC/croc clip cable, that's not really ideal for looking at voltages of around 1mV. We have to work with what we have and it seems to work fairly well, but if there are a few inconsistencies we shouldn't be surprised.

I've also noticed that it's as well to self-calibrate the scope regularly. Every time it recalibrates the no signal levels can be very slightly different. Don't forget that we are talking about measuring voltages towards the limits of what the scopes and normal, cheap DVMs can do.

What I have seen is that sometimes the FY6800 gives about a 13mV offset according to the DVM. The scope shows the same as a mean of about 13mV with a noisy waveform superimposed. The noisy waveform has spikes at around 65KHz. Powering off the FY6800 for a minute then powering it up clears it and it returns to having an offset of around 1mV. It reminds me of your original post about a 20mV offset and it looks like a definite flaw in the product. I wonder if it's been covered somewhere in this long thread.

I think I got around the 13mV offset, try if this works for you:

i) Make sure that in your "SINE" waveform settings, the default value for amplitude is 5V.
ii) Switch off FY6800 using the main switch on the rear (not the standby button on the front).
iii) Switch on FY6800, then select the "DC" waveform (using the wave button). Set "volt" to 0.000mV.
iv) Read the actual voltage with your multimeter: you should read the infamous 13mV offset.
v) Now select the "SINE" waveform (using the wave button). Set "amplitude" to zero (and while you are at it also set "offset" to zero).
vi) Go back to "DC" waveform (using the wave button). Set "volt" to 0.000mV.
vii) Read the actual voltage with your multimeter: the abnormal offset should be gone and you should read around 0mV as expected.

So, this seems a firmware flaw to me (I'm using 1.7.1 fw). Can anyone confirm?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 14, 2019, 02:07:34 pm
It didn't work at first. Then I remembered my FY6800 does not power up with factory defaults, so I set it to do that and it's as you describe, apart from being an 8mV offset on the DVM and I recall a 9mV offset on the scope. The rest of it is exactly as you said. However, there isn't the noise superimposed on the offset as I saw before. Firmware is V 1.7.1.  An offset which can appear depending which settings the system boots with? It has to be a firmware bug.

If I remember correctly, nothing but power cycling got rid of the 13mV noisy offset, so it could be two different fw problems.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 15, 2019, 06:22:08 am
To Zenith

 I chose the 1202 since, for my immediate needs, it seemed the "Best Bang for my Buck" option. The 1204 was just 30 quid shy of double the price at 700 quid and a 4 channel 'scope was one luxury I could happily forego for my immediate needs. If I needed a better 'scope in a year or three's time, I'd probably be considering something much better than the 1204 anyway.

 I ran into the "'scope gets all confused issue" too. The first few times, I just switched it off and back on again (windows PC syndrome - usually my customers', rarely my own win2k setup) before I noticed the big blue "Auto Setup" button.  :-[  Strangely, "confusion" doesn't seem to happen quite so often these days. TBH, I'm not sure whether or not I've tried the default button. Possibly I have but hitting the blue button usually sorts things out.

 All manuals, as a rule. could be better written but with something as complex and fully featured as a DSO, it's no easy task for the author to get a nice balance between simple and complex. As technical manuals go, the Siglent one isn't so bad. I've seen far worse with other (even less complex) kit.

 As for my own "Boat Anchors", they're both languishing in my basement workshop come radio shack. The scope, as you can see from the attached photos, is parked on a currently inaccessible shelf (I can't even gain enough access to unclip the cover to reveal the CRT face and controls, let alone haul it out to look for a make/model name plate).

 AFAICR, it's a 5MHz BW 'scope, possibly even dual beam - it's been more than a decade since it was last used). The Marconi signal generator has probably not been used in over two decades (but at least it's more accessible) so these recent T&M kit purchases have been a very welcome upgrade on what may well be non functional kit, never mind an upgrade specifications wise (apart from the 310MHz top end of the Marconi sig genny - assuming it could still stretch itself to such a giddy frequency limit).

 Whilst the FY66/6800 generators are, in many ways, a vast improvement over older kit that's even younger than those boat anchors of mine, I rather think you'll find the frequency stability rather leaves a lot to be desired. Before I turfed out the rather cheap 'n' nasty commodity CD player 50MHz reference oscillator chip it had been cursed with, I tested several  of my stock of standard DIL packaged oscillator modules recovered from various scrapped electronic kit over the past three decades (mostly PC boards), comparing their frequencies against the FY6600 using the siglent 'scope.

 Trying to get the 6600 to match frequency was like chasing "Wil 'o' the Wisp". When I did manage to get a meaningful display, it only took a gentle breath (literally!) of wind on the Oscillator under test to send the waveform racing ahead/behind, neatly demonstrating just just how precise you had to be to match them up.

 When I repeated this exercise after the TCXO upgrade, there was far less chasing "Wil 'o' the Wisp" and the effects of small temperature changes on my oscillators under test were far more predictable and stable. Now that I've gotten hold of a u-Blox M8N Arduino/RasPi GPS module to generate a 10MHz reference directly from its PPS pin, I can see that the TCXO stays within 20 ppb from cold startup to a nice toasty room temperature of around 23 deg C and settles to within 10 ppb of frequency ( it's currently just over 7.5ppb in error at 22 deg C at 0100 hours UTC).

 No doubt the fact that the TCXO module is in the direct firing line of the small cooling fan to hold it to within two or three degrees of room temperature (instead of running at 50 deg C like the original oscillator chip did) contributes to its rapid "warm up" since it doesn't have to do very much warming up to reach thermal equilibrium. Even so, there is still the issue of 'self heating effect' to account for but this is negligible compared to what the original oscillator chip was subjected to by being within 1cm of a 70 deg C heat source (the three analogue voltage regulators or "Stooges" as they might best be named in this joke of a main board layout).

 I tend to leave the signal generator running 24/7 (it only consumes 8 watts at its current settings) and for the past three "mornings", my initial frequency check has shown it unaccountably running within 0.5 ppb of the GPS reference. However, within minutes of taking stopwatch timings, it will start to drift off, typically showing all the signs of passing through the exact frequency of 30,000,000.000Hz (I'm monitoring the third harmonic) before it drifts to an initial offset some ten to fifteen minutes later of around 4 to 5 ppb where it will then very slowly drift by another 3 to 5 ppb over the rest of the day.

 This 'morning behaviour' is a little 'spooky' since it implies it can sense my mere presence in the room. My best guess is that it's not so much my presence as the effect of powering up the adjacent TS140S HF rig and the 10A 13.8v psu made up from a couple of 40 year old 5v smpsus strapped together in series and maladjusted to 6.9v each. The HF rig consumes 14W in Rx mode with the PSU raising the 'from the mains socket' load to 25 to 30 watts. It seems unlikely to be convective heat polluting the fan intake and I can't see the slightly increased loading on the long but heavy duty mains extension cable having any effect on the FY6600's smpsu voltages sufficient to upset the 3.3v regulator on the oscillator board so my best guess is that it must be responding to infra red energy from the 13.8v PSU and the HF rig (not forgetting my own small contribution, assuming this IR hypothesis has any validity).

 I can now see the motive behind adapting these generators to utilise an external GPSDO 10MHz reference. A 0.1ppm TCXO whilst undoubtedly a vast improvement over the commodity XO chip, is still some three or four orders of magnitude short of GPSDO perfection. Anyone motivated enough to put Feeltech's 'wrongdoings' to rights is going to find the challenge to achieve the best possible frequency accuracy and stability irresistible.

 Until I got my hands on the u-Blox module and active antenna, I was still thinking that Arthur Dent's posting a year or so back regarding his replacement of the XO chip with a 10MHz OCXO and a low jitter PLL chip to mulitply it up to 50MHz, along with a change over switch and external BNC socket to plug an external 10MHz reference source into the FY6600 was a little OTT to say the least.

 I can see his point and I'm now sorry I didn't use an easier to obtain 10MHz TCXO to use with a PLL chip rather than aim for a 'drop in replacement' 50MHz TCXO. Never mind, I daresay I'll be able add the PLL chip and automate the changeover on sensing the presence of a valid 10MHz reference on the external reference socket to minimise the switching glitch between local and external references. I suspect any nasty glitching on the 50MHz clock signal might crash the main board so this might be more complicated to achieve, especially in the event of loss of the external reference, whether by unplugging it or just simply due to a loss of the feed for any other reason.

 Anyhow, that's a new adventure for my own satisfaction. Returning to the business of the 85 ohm attenuator pad still being present on the FY6800 main board, that does rather suggest a deliberate action on Feeltech's part since they've had ample opportunity to put this particular "Skoolboy Howler" well and truly behind them with the new iteration of the main board.

 Either they're still leaving temptation to tinker so as to minimise after sales service costs (voided warranties) or else are bowing to pressure from the likes of Rigol and Siglent to retain such annoying defects so as not to seriously dent their own sales, otherwise I can't see how they could have missed the opportunity to correct this error with the reworked board designs. They must have become aware of the problem straight from day one since they've obviously applied a fix in the firmware - admittedly one that could only be effective in the Hi Z condition they elected to correct for.

 It's not a fatal flaw so much as an egregious annoyance. You can get round the issue of generating sub 500mV signals by never going below the 500mV setting and using an external 20dB 50 ohm pad instead. Aside from such limitations and seemingly deliberately included annoyances, these Feeltech products are otherwise excellent value for money test gear.

 Sure, the penny pinching effects are there but I don't think all of the deficiencies are down to random penny pinching alone. A lot of it seems to be down to 'defective by design' since not all defects are the result of saving a penny or two. That 85 ohm pad cost them just the same to implement as a proper 50 ohm pad would have.

 When it comes to accessories like 'scope probe leads and welding cables, it is just a matter of 'penny pinching'. The decisions taken by manufacturers are rather dependant on what their customers' needs are. For a budget item where expectations are low, the manufacturers see a chance to bundle cheap but serviceable accessories to provide 'instant gratification'. With high end kit, the manufacturers will often take the view that it's better to let their customer decide what to spend on their own accessories which may be nothing at all if they already own high quality accessories to begin with rather than spend a small fortune supplying accessories of a quality that matches that of the product which their customers may not need or even wish to use.

 Regarding the lack of a coarse voltage offset adjustment, I think you'll find it in the form of a rate control where it jumps in bigger increments if you twist the control fast enough. However, it tends to result in overshooting the mark. I guess familiarity from lots of practice in its use helps mitigate this problem.  :)

 I guess a firmware update might tame this "All or Nothing" effect of the rate control. Unlike the volts per division setting control where the push action toggles between coarse and fine, the push action on the offset adjustment is used to reset back to zero offset, leaving rate control as the only convenient alternative way to increase the step size of the increments. Short of adding a separate push button or adding it as "pull" action on these knobs, there's really no easy solution. Although it is a little hit and miss, I don't find this is that much of a problem.

 As for the staggeringly high digit count on the FY66/6800 frequency setting (14 digits worth! And all of them valid), not even the best frequency reference standards (Rubidium or GPSDO) can match that amount of resolution. They might all be valid but even with the best available atomic clock derived laboratory frequency reference, the last digit or two will be meaningless or, at best, only meaningful for frequency settings lower than 1MHz.

 You can take some comfort from the fact that a lack of digits won't limit its ultimate frequency setting precision, not even when fed from a Rubidium or GPSDO reference clock. The fact that its original XO chip makes a complete mockery of the nine least significant digits in the display is neither here nor there. Once you're familiar with your test gear's limitations, such 'anomalies' cease to be an issue. However, in this case, the desire to upgrade the XO to a decent TCXO or OCXO (with or without an external atomic frequency standard clock drive option) can become an irresistible challenge.  :-\

 Regarding the various mods to the FY6600, most of the more interesting ones started to appear around page 8 of this 73 page forum. I've already mentioned most of them in recent posts in the last three pages or so but if you're interested, it's well worth a skim through the early pages to pick them up. Be warned though, you could land up spending a solid couple of evening's worth trying to plough through them all. Obviously, you can skip the discussions and progress reports on fixing the firmware issues that sadly afflicted some of the early adopters stuck with bricked firmware (versions 3.0 AFAICR).  :( >:(

 Mention of the 3 quid radio and the Lidl astronomical telescope modding exercises, that reminds me of my own, paused project to add an electric starter function to the Parkside PGI 1200 B2 inverter generator which Lidl were selling last April and May for just £99.95. I bought one, returned as faulty for an exchange for one that also had a fault and landed up with a refund since they had no others in stock to exchange.

 Frustratingly, I'd discovered by then that both faults were the result of handling 'damage' from the endless motorway road trips they were routinely being subjected to whilst being shunted from store to store or central depot because the shop floor also had to double as the shops' stock rooms and each new "This Week's specials" which had to have space cleared to display them, they'd be shipped out of the store.

 These 'stock faults' (quite aptly named in this case) were quite trivial to fix since it was either a stuck oil level float or else a dislodged connector on the inverter module both of which could readily be fixed. About a week after that episode, I tried a less likely Lidl shop in the unlikely hope that they'd also received a delivery of these excellent little generators and very much to my astonishment, they had three in stock.

 I picked the two with the least scuffed boxes to take to the checkout. I just wanted to do any returns wholesale rather than piecemeal one at a time. As it happened, both proved fault free so I had to choose which one to return to the store for a full refund. Unfortunately, I hadn't thought to verify the 1KW overload limit settings and I landed up with the one that regarded 980W as the trip point instead of the expected 1030 or 1050 watt setting (whether the one I returned did have a higher set point remains an unknown).

 Unfortunately, unlike every other inverter module I've ever seen pictures or videos of, these Parkside ones don't have any of the otherwise ubiquitous trim pots to adjust such niceties as overload current trip points and voltage settings - not one single trim pot! I guess the adjustments are flashed into the controller's firmware, never to be accessed with something as simple as a trimtool.  >:(

 Never mind, when these come back into stock again, as they must, I'll snag a couple more to use as donors to replace the ungenerously set unit in mine, assuming at least one is more generously configured with regard to the overload trip point. If both are good in this respect, I'll keep one and return the donor machine for another full refund. At just £99.95 each, it's worth keeping an extra one just as a spare.

 Anyway, after struggling with the recoil starter to get it up and running on account the fuelling system not being the simple gravity feed type where you can use a float tickler to flood the carb to ease starting but one relying on an engine vacuum driven fuel pump which after running the float bowl dry to prevent it gumming up means you have to crank it several times to prime the carb float bowl, I considered how I might be able to add some sort of electric starter to it. There was no easy way to add a conventional starter motor and since the inverter module blocked access to the end of the crankshaft where the common trick of using a cordless electric drill with a suitable socket spanner to engage the retaining bolt so as to spin it up, I started to think 'outside the box' when I realised that the 6 or 7 pole pair three phase permanent magnet 380v alternator was nothing more than a BLDC motor in disguise simply waiting to be turned into a starter motor by a genius like myself.  ;D

 I have to say, I've managed to get as far as testing with a 60v rated BLDC scooter motor controller and 48 volt's worth of battery, proving the concept. Unfortunately, sensorless control option just doesn't cut it with such mechanical loadings. I could get it to spin up with the spark plug removed just fine but even just blocking the spark plug hole with a finger tip was all that was needed to confuse the sensorless control algorithm and stall it.

 However, fitting an angular position sensor to the end of the crankshaft will overcome that problem once I finally get around to figuring out the pole pair count so I can order a unit programmed to emulate a hall sensor drive signal more accurately than even the best conventionally hall sensored BLDC motors can achieve. The project is paused because I'm waiting for another Round Tuit. Besides which, I'm still busy fettling the test gear needed to test and configure my electric start system.

 Harking back to Andreax1985's problem with the offset voltages he's seeing, I suspect it's probably more to do with thermocouple effects or galvanic corrosion within the hard mains earth loop between the 'scope and generator grounds. Compared to such a low impedance ground loop circuit, the scope lead's shielding resistance and that of the crocodile clip contact resistance is far too high to shunt such low impedance voltage sources effectively. If he can bring himself to disconnect the safety earth and cross bond any of the FY6800's BNC grounds to his scope, he may well find a significant reduction in this offset voltage. This was one of the reasons why I used an 11K resistor in series with the signal ground and the mains protective earth on the C6 socket (although, to be fair, I hadn't considered DC offsets, just ac induction voltages).

 Regarding the photos. Apologies for the low resolution but I'd forgotten about the 640 by 480 setting from when I hadn't wanted to exceed the 2MB limit in a previous posting. Also the two offset angle views of the Marconi signal generator were required to avoid reflection from the on camera flash burning the image out.

 The scope shot is the best I could do on account of the foreground clutter as shown in the next image (the scope is at the top in that picture). I thought the Min/Max thermometer would give you some idea of the storage environmental conditions. Whether any of this kit is still serviceable after spending some three decades in my basement remains an unanswered question although the remarkably good condition of my HF transceiver, which had spent just two decades there, does offer some hope.

 JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andreax1985 on February 15, 2019, 05:00:48 pm
I decided to float my scope (ok, I know it's not advisable, but considered the particular application I felt safe in doing so) in order to break possible ground loops. I can confirm that the residual dc offset was due to ground looping and now my readings are perfect. My device is working properly and I'm not going to return it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 15, 2019, 11:43:56 pm
I decided to float my scope (ok, I know it's not advisable, but considered the particular application I felt safe in doing so) in order to break possible ground loops. I can confirm that the residual dc offset was due to ground looping and now my readings are perfect. My device is working properly and I'm not going to return it.

 Excellent news! Thank you for that feedback. I'm so glad my 'educated guess' actually "nailed it" for you.  ;D

 Since you're planning on keeping hold of the generator, does that mean you're going to modify its earthing circuit with a 10K or so resistor to avoid the low impedance earth loop problem but still suppress the half live mains touch voltage issue (that so many of us here were bitterly complaining about with the FY6600) to a more acceptable half volt or less? The PSU is still essentially a class II double insulated type intended to be used without any need for a safety earth connection.

 Looking at this, it seems Feeltech had a just, if flawed, reason not to encumber the FY6600 and its predecessors with a safety earth connection. The flaw being the penny pinching profit motive and the justness being the avoidance (more by accident than design) of this earth loop problem.

 In responding to all the demands to eliminate the half live mains touch voltage issue, it seems they've created another issue by hard wiring the internal ground rail to the safety earth connection rather than choose the sensible compromise of a resistive connection to reduce the touch voltage to an acceptably low value without introducing a low impedance ground loop problem.

 It would seem that FY6800 owners can add yet another modification to their "To Do List", adding a 10K or so resistor to the earth connection being the second of the earthing related mods with the first being to rejoin the cut off  0v rail wire in the ribbon cable linking the PSU to the main board to double up the 0v rail wires again as per the original FY6600 arrangement.

 I do have to wonder at this demonstration of utter ineptitude on Feeltech's part. After all, a safety earth connection isn't actually required with the cheap commodity three rail class II smpsu board they're using so a 10K resistive link to avoid earth loop issues yet reduce the touch voltage from a high of 90 odd volts to an insignificant half volt wouldn't have been deemed inappropriate on the grounds of safety.

 There's clearly three hierarchical levels within the T&M ecosystem with the likes of Keysight occupying the top slot, Siglent the middle and Feeltech the bottom and I can't help imagining conversations between Keysight and Siglent over the fine art of not treading on toes with Siglent then passing on this favour to their own underlings, Feeltech being one of them in this case. Such an imagined scenario offers a compelling rationalisation of the apparent "Shooting oneself in the foot" exercises that Feeltech seem to be so fixated on repeating at every opportunity that comes their way to improve their products for very little to zero out of pocket expense. The persistence of the 85 ohm pad into the FY6800 model being a prime example of such missed golden opportunities to correct the mistakes of earlier production runs.

 Quite frankly, it's impossible to shake off the feeling that there's an element of design to the penny pinching practices at Feeltech since most of the resulting shortcomings are amenable to relatively easy fixes on the part of a reasonably skilled end user prepared to void the warranty.

 If you include enough such warranty voiding enticements in your product, you may never have to deal with a single warranty return. This is a prospect made all the more likely by the rock bottom pricing and the one way export shipping subsidy adding the barriers of return shipping costs and delays to the headaches of collecting on a Chinese warranty. I do have to wonder whether anyone has ever managed to collect on Feeltech's warranty without being left out of pocket.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 16, 2019, 12:35:32 am
@ Johnny B Good,

I've always thought specsmanship crept into scope choices far too much, especially when a company is paying for them.

The scope has gone out to lunch problem caused some worry at first, What was going on? Would there be the hassle of sending it back? And so on. It seems to happen after using slow sweep speeds, but it's not a frequent thing and when it dawned that pressing the Auto button or the Default button clears its head, it's an occasional minor nuisance.

My Boat Anchors are something like 15 valve comms receivers, and a dozen valve scopes. There are also about 20 or 30 items of test equipment mainly from the 70s and 80s. I don't recognise that Marconi sig gen. I have a Marconi TF144 which I eventually started taking to bits and it's now in the garage. It was was one problem after another, dead meters, sealed and not easily fixed with similar meters, a dead double tetrode, which took ages to find a replacement for, and a host of other things. It really was a boat anchor. I have an HP8640A, which is excellent, apart from the silly plastic gears.

The FY6800 had been running for a day or so. I have a couple of Racal frequency counters with overnised crystals, which haven't been calibrated for probably 20 years and so probably wouldn't agree closely with a precision standard, but I'd bet are stable. I connected the FY6800 to one of the frequency counters and the scope, terminated. I set the FY6800 to a 10MHz sine at 2 volts. The frequency counter said 9.999923MHz , a couple of hours later, 9.999922MHz and ten minutes later, 9.999924MHz. A couple of hours after that it was reading 9.999917MHz. The scope said 9.99996/7MHz. I see the frequency measurement on the scope as a convenience more than anything else.

So an accuracy of maybe 100Hz in 10MHz setting and drifting through less than 10Hz in 10MHz over a few hours - this is assuming that the Racal wasn't drifting and isn't wildly out. I'd expect that from a decent quality, but not special crystal module in the FY6800. I'd say it's enough for most needs, but I'm inclined to get hold of a  u-Blox M8N Arduino/RasPi GPS module you mention and do the frequency module upgrade. As you said previously, the FY6800 is likely to be aimed at the hobbyist.

What's behind some of the strange decisions in evolving the FY6800 from the FY6600 is open to all sorts of theories. Some bizarre culture in FeelTech. They got it working but it was all so skin of the teeth that they were frightened to modify anything too much. The lead engineer who came up with the design got another job, or left to form his own company, and they were left with no one who really knew what they were doing.  One aspect I find odd is the PC software where some features don't appear to work at all. If you enter data in the wrong way in some fields, the program crashes and there's the almost unusable feature for drawing an arbitrary waveform. I get the impression that someone with no knowledge of, or enthusiasm for, software was presented with a PC with a VB system and told to write the software. They cobbled up something which could be described as the software, Feeltech had something they could include as the software, and whoever wrote it went back to their regular job with a sigh of relief. Of course, it could be as you say; they've generated a following and a lot of publicity for the product by its defects creating so much interest in retrofitted improvements.

OTOH, my TTI 5MHz function generator, calibrated according to the manual, has a very inaccurate scale and can only be set to 455KHz by using a frequency counter and gentle caressing the frequency control to get close to 455KHz. Half an hour later it can be at 457, half an hour after that, 454.  I came across a Maplin catalogue from 2011/12. They had two function generators, both up to 3MHz. One was £145 and the other £205. I doubt either would bear comparison with the FY6800, for all its little faults.

I saw the generators in Lidl but I have no real need for one. Aren't they 2 stroke?  My impression of Lidl and Aldi specials is that they are always interesting and sometimes remarkable for the price. I had a need for some 1 metre SDS drills a few years back. Wickes were £15 and upwards each. Aldi were selling three for a tenner. I thought we'd do the job with the Aldi drills, after which they'd be knackered, but we'd be a fiver in, so why not? As it was there was about five times as much work as we thought. We mainly used one drill and when we finished it was as good as when we started. It's a strange thing to find 1 metre SDS drills in a grocery store, but they do them quite often and they always seem to sell.

If you have equipment which has been kept in the damp for a time, it's very good idea to leave it in the airing cupboard, or somewhere similarly warm and dry, for at least a fortnight. Then it's worth reforming or replacing electrolytic caps and being generally cautious about powering it up. Bunging it on the mains can cause some unpleasant surprises.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on February 16, 2019, 01:07:48 am
From memory mine was always always about 30+ Hz high at 10Meg against my GPSDO and I think early on in the thread there is some mods done on the time base if you look for them with different TCXO's fitted.

What all of this shows is that they were chasing the bottom line against 'their' competitor in JDS instead of focusing on being best in class. What they failed to see is there is a huge gap to anything better they could have played in.

Better Power Supply
More accurate Time base
Better Op-amps and trimming in the factory
Upgradable Firmware
Maybe $20-30 retail needed to get it done right?

Compared to most likely hundreds of hours of 'fun', speculation and tinkering by us all. Still great bang for your $  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 16, 2019, 02:27:57 am
What all of this shows is that they were chasing the bottom line against 'their' competitor in JDS instead of focusing on being best in class. What they failed to see is there is a huge gap to anything better they could have played in.

Better Power Supply
More accurate Time base
Better Op-amps and trimming in the factory
Upgradable Firmware
Maybe $20-30 retail needed to get it done right?
Yeah. Conspiracies exist, and a few conspiracy theories have been proven true, but I think the cock up theory usually wins out over the conspiracy theory.

So thinking about the history of the instrument business, I don't see JBG's view of the hierarchy ringing true.

Look you lot are educational and skint hobbyist, see? A nice little function generator you've got here. Too nice. You're getting above yourselves. So we'll have a crappy 85 Ohm pad in here. Your choice of op amps is unfortunate, and could prove unhealthy. Change it. As for that TXCO and the option for an OCXO and an external reference, err, no. Now if you can't see the logic of these design improvements we have associates who will explain them more clearly. They are persuasive if not altogether civiliised.

This is a cock up.

Compared to most likely hundreds of hours of 'fun', speculation and tinkering by us all. Still great bang for your $  :)

Better value than going to the pictures.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 16, 2019, 06:11:10 am
@Zenith

Specifications are an important marketing tool, especially in such a competitive market as this where the feature set can be overwhelmingly complex with modern DSO and MSO kit so 'Specmanship' is going to be inevitable.

 My first experience of the Siglent going into a fugue was a little disconcerting at first but bearing in mind all the microprocessor control and digital processing used in a modern DSO, I instinctively applied the 'switch it off then on again' technique the first two or three times this happened before it occurred to me to try the 'Default' and 'Auto setup' (amongst other) buttons to avoid the protracted power cycling method which provided reassurance that these episodes were more a case of 'Operator Error' than any indication of something more serious. These buttons are obviously provided to back out of any conflicted settings that may have been applied by operator abuse.

 I had hoped to be able to discern the model number of the Marconi signal generator from the photos, forgetting I still had the camera set to the 640 by 480 setting from a previous photo shoot to minimise the risk of going over the 2MB attachment upload limit when posting images of the u-blox GPS module to [urlhttps://www.eevblog.com/forum/projects/ublox-neo-m8n-gps-navigation-signal-amplify-module-for-arduino-rasppery-pi/][/url]

 Hopefully, that link hasn't been mangled too badly (if at all - I'm not quite sure how you're meant to use the "Insert Hyperlink" button in the compose a reply window). It looks ok here so that will take you to a thread I started some 2 1/2 weeks ago trying to get some advice and opinions over its suitability as the basis for a homebrewed GPSDO.

 I think I must have bought the sig genny at an amateur radio rally some thirty years ago. The scope was an earlier purchase from a local government surplus shop afaicr some time around 1972/73 to let me record oscillographs of test waveforms of a 200W per channel (RMS per 4 ohm loads) PA amp I'd been commissioned to design and build by a friend who played in a local band. The need to photograph the CRT display led me into the amateur photography hobby, something I'd previously never had any interest in. It's surprising how one thing leads to another.  :)   Anyway, the one of each item, 'scope and signal genny, was all I needed and could afford so I neatly avoided accumulating any more 'boat anchors'.

 Your frequency calibration checks of the FY6800 appear, on the face of it, to be fairly respectable considering how Feeltech cheaped out on the XO chip. You'd expect OCXO s to be pretty stable even if they're in need of recalibration after twenty years. Mind you, if they've not been used very often, they might not be all that far off frequency even twenty years later. The hardware frequency counters built into these Siglent 'scopes aren't remarkably accurate. Mine, after 8 or more hours of warm up was adrift by about 4.33ppm (it read high on frequency to the tune of 130Hz on a 30MHz signal afaicr). Not very impressive at all imo but, as you've observed, more a courtesy feature to get a ball park figure.

 Your own thoughts on what's going on at Feeltech are possibly closer to the truth of the matter. The cynic in me tends to nurture conspiracy theories since I prefer to look for less chaotic reasons for such otherwise inexplicable behaviour. Whatever is going on, they're certainly not doing themselves any favours, more's the pity.

 There's no doubt that the Feeltech generators, as cheap as they are, are in a totally different league to even modestly vintage test gear that wasn't made by Hewlet Packard.

  If the generators you saw in Lidl last year were either the very retro styled PGI 1200 A1 (still surprisingly carrying their original £129.95 price tag of the previous year) or the more suitcasey styled PGi 1200 B2 at just £99.95, they're both 4 stroke powered in spite of the A1's rather retro two stroke styling with its top mounted gravity feed fuel tank and open frame with plastic panels slung around the sides to disguise its open framed nature.

 It's rather surprising that an earlier version of the B2 model should be placed on sale about a month after the B2s had been on sale with a 30 quid higher price tag. Hopefully, the B2 models will reappear again come the Spring and I'll be able to pick myself a couple of donor machines to resolve the irritatingly low overload trip point on my current acquisition.

 My interest is in their use as an alternative to investing several hundred quid in SLA battery packs just to extend the autonomy of my APC SmartUPS2000 an extra 6 to 8 hours. Basically, it's a backup to the UPS. As an autonomy extender, it's a far less expensive option to installing a bigger battery pack which, at the end of the day, is just an expensive consumable.

 With only a 1KW rating (30 seconds surge rating of 1200W), it's a little on the marginal side but the 2KW rated Workzone inverter gensets that Aldi had on sale about a month or so after I'd acquired the Parkside unit proved to be total shite, to put it mildly (and I should know since, optimist that I am, I tried three of these before giving them up as a lost cause).

 Compared to the Workzone units, the Parkside ones are inverter genset perfection, not the slightest hint of engine revs dropping on application of full load in the eco idle setting, unlike the Workzone units which threatened to completely stall out when subjected to full load from the half loaded state. AFAICR, the Workzone units were permanently in eco-mode with no option for 'normal mode' so there was no way to mitigate the problem like there was with the Parkside units to reduce the risk of a stall whilst they were warming up from stone cold (the only time I managed to stall a Parkside unit was switching straight to eco-mode after startup followed immediately with the application of full load - restarting it and giving it a couple of minutes to warm up solved the problem).

 Take it from me, those little Parkside PGi1200 B2 suitcase gensets are well worth the money, even if they hike the price up to that of its predecessor. The Aldi Workzone units otoh, aren't worth touching with a ten foot bargepole so take note.

 I hear what you're saying about the effects of prolonged damp on electronic kit, particularly when bias voltages of two or three hundred volts are involved. As it happens, I do have a small 180VA Variac but it's a a panel mount unit and I don't have a suitable box to mount it in. Also, I'm not sure whether a 180VA rated unit would be up to the demands of an ancient scope or even the Marconi sig genny but I guess it might be able to cope with the overload for the few minutes it would take to bring the voltage up slowly enough for the electrolytics to reform.

 Otoh, I might just say "Bugger it! I'll just switch them on and take my chances.". If either or both go bang, then so be it. That'll just be a boat anchor or two less to clutter up my storage space. They're so ancient that at best they'll simply be electronic curios to admire for their sheer chutzpa at even pretending to be test gear. Life's just too short to be trying to repair such ancient kit of limited utility, hence the fatalistic attitude to the problem. Apologies if that sounds a little cavalier but that's just the way things are right now.

JBG
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on February 16, 2019, 02:18:08 pm
So today i put the THS3491 into the generator and put a new proper heatsink pad below the Heaspreader.
Now i can get 22 Vpp with 20 MHz sine.

But i get now an overshoot with square wave If i go above 500mV Independent of high impedance or 50 Ohm termination...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 16, 2019, 08:19:30 pm
So today i put the THS3491 into the generator and put a new proper heatsink pad below the Heaspreader.
Now i can get 22 Vpp with 20 MHz sine.

But i get now an overshoot with square wave If i go above 500mV Independent of high impedance or 50 Ohm termination...

 Remind me please, Noy. Is this the FY6600 or the FY6800? I've lost track of who has what.  :-//  Also, can you provide some details about the 'scope and the way you've got it connected up to the generator. If you can post a screenshot or two of the relevant traces, that'll help us to work out what's actually happening.

 I'm a little puzzled as to why you're getting 22v p-p. This is 10% above the 20v p-p limit of the generator's amplitude range which begs the question as to whether this is a calibration issue or a voltage magnification effect due to the use of a few metres of unterminated 50 ohm BNC patch cable.

 Out of curiosity, I repeated your tests using the half metre BNC patch lead that was supplied with my FY6600. I wanted to verify whether the square wave was limited to a 5 or 10 volt p-p level or not at 20MHz and lower frequencies since, if it had been (it isn't - the 5v p-p limit only kicks in for frequencies above 20MHz), that would have excluded the THS opamp from the circuit (that only gets switched into circuit for p-p settings above the 5 volt mark).

 That reads like you've installed just the one THS3491 (U21 and U22 showing the THS3001 locations) and left the original THS3002i chip (U5A and U5B) in place. The reason why I'm querying this is because the reverse engineered circuit so kindly provided by ebel0410 last year (which he uploaded to the Github repository)  implies the simultaneous presence of the original dual opamp along with the additional single opamps. That's a little confusing to say the least although most would realise that it's either just one or the other arrangement (just the original 3002i in the U5A/U5B locations with the U21/22 left empty or else the original 3002i removed with either 3001, 3095 or 3491 ICs fitted in the U21/22 locations.

 Hopefully, what you actually meant was that you'd removed the original THS3002i chip and fitted a pair of THS3491 chips into the vacant U21/22 locations. Assuming this to be the case, one possibility for the overshoot could be the need to tie the Vref pins to a voltage 5 volts or lower than the V+ rail voltage, typically either to ground or else the V- rail. Provided this is the case, the /PD pin can be left to float as with the earlier 3495 chips. The easiest way to meet this requirement, is simply to strap pins 1 and 4 together (the data sheet insists that the Vref pin (pin 1) should not be allowed to float).

 I've attached some screen shots for you to compare with yours. The first two are from the end of last year just after I'd upgraded the opamp. The second pair were done just now, using the half metre of supplied BNC patch cable, without termination (the terminated traces looked virtually the same only, of course, at half the p-p voltage).

 JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 17, 2019, 03:58:55 pm
@Johnny B Good

The link was garbled but I found the thread with a search. Thanks for trying.

Boat anchor receivers are sought after and some people like to restore them to as issued in WWII condition. Boat anchor test equipment has much less of a following and people don't seem sentimental about old sig gens. If they work, fine, but the size and weight is a pain. It they break and can be fixed easily, fine. If they are too much of a PITA, they go. It's a shame, because the standard of construction can be very impressive.

My valve scopes are from the 60s mainly. They are not quite boat anchors, they are usable as scopes and occasionally I fire them up and use them. I've really enjoyed sorting out their problems and getting them working properly. I think the interest there is that I wanted one as a kid in the 60s, but they were completely unaffordable.

Feeltech may have put in a slightly better crystal lately, or maybe I got a good one. The accuracy is fine for what I bought the FY6800 for, sweeping IF stages for visual alignment, and for that purpose the drift is essentially non-existent. I'm still tempted to tinker 'though.

I've always found the Racal frequency counters very useful and very reliable, and they're quite small. Looking on ebay, I saw a couple for about £30.

From what you say, you have a perfectly good reason for buying the Parkside generator. I'm sure a lot of people buy the Lidl/Aldi specials because they can't resist a bargain and wonder whether they need it afterwards. I've fallen into that trap once or twice. You're probably aware of this, but petrol can go stale and it's hard to start an engine with stale petrol. I think what happens is that volatile fractions, which allow  a spark to ignite the fuel, oxidise. This can be a real problem with engines which aren't used for months, but you expect to start with little trouble when they are needed. However, you can buy fuel stabilisers which stop the fuel going stale. I believe a lot of two strokes oils contain some stabiliser.

It's just possible that your boat anchors have some very desirable parts, such as the rectifier and possibly a KT66 used in a stabilised power supply.



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 18, 2019, 06:32:32 am
@ Zenith

 By the time I could have afforded any of those boat anchor radios, I had other priorities, namely the acquisition of a decent HF transceiver, hence the TS140S (the first of Kenwood's modern synthesiser tuned budget HF transceiver models). I bought it at a radio ham rally nearly thirty years ago. It had a 750 quid price tag but I managed to do a part exchange deal which reduced the damage to a mere 500 quid. The strange thing is that I can't recall just what it was I'd offered in part exchange (and I've tried my best to recall just what it had been over the past year or so).

 I suspect it may have been a customer return on account half of the commands in the PC control software didn't work. Weird things like the RIT would only tune upwards, the downwards RIT tuning command being ignored amongst similar oddities.

 Luckily for me, it used the Z80 cpu in its controller board and I was able to pull the eprom out and copy it to a file which I could run my home brewed Z80 disassembler on to get a full listing from which I was able to track down the command interpreter routine and its look up table. The table search loop counter value had been corrupted to half its intended value, probably by a single bit error in the eprom so was a very easy fix - just a matter of burning another eprom (or two just to make sure of having at least one good spare) and dropping it in as a replacement, after which, the radio worked perfectly with the PC controlling software.

 As for the excellent standard of construction in such vintage kit (radio and test gear), it had to be in order to achieve the best possible frequency/timing stability out of the analogue tuning systems employed. Nowadays, it's really only the TCXO or OCXO reference oscillators that need to be protected from mechanical stresses and only when ppb accuracies are demanded. When the requirements demand just a mere 1ppm level of accuracy, the XO module can even be placed directly on the main board, right next to a bunch of analogue voltage regulators if that's a manufacturing convenience where heating it up to 50 deg C isn't deemed any great detriment.  >:(

 As for the desire to "Tinker", even now, I'm wondering where it'll all end. The GPS module was acquired simply because the R4LW transmitter is at too low a frequency for attempting to trim the TCXO (it's good enough for checking the calibration directly but I'd have to build a 10MHz disciplined reference receiver to turn it into a useful calibration aid) and the 10MHz WWV broadcasts can't be received due to propagation conditions being at an all time low (we're currently in a sunspot minima right now). As things stand, with talk of the R4LW losing its NPL reference status in the next few years, the GPSDO project seemed to be the better option than making a special frequency reference receiver based on the 198KHz broadcast.

 Just as it stands, without adding a disciplined 10MHz OCVCXO to it, the 10MHz output on the PPS pin provides a far more stable reference calibration source than the WWV broadcast, free as it is of fading and phase distortion from skywave propagation effects. Indeed, programming it to output 198000Hz to beat against the R4LW transmission as a sanity check that this still justifies its status as an NPL grade reference, revealed no discernible phase shift over the space of 90 minutes. As a sanity check that this zero beat effect was actually real, I'd actually programmed the gps module to output a 1Hz offset each side of the frequency (it can only be programmed in 1Hz steps) to time 60 beats in exactly 1 minute each time (to within 50ms according to my Smiths stopwatch with its 30 seconds per sweep of the dial calibration and high speed escapement).

 For the past week or so, I've been monitoring the frequency drift of the signal generator against the third harmonic of the GPS 10MHz output which reveals a small drift with temperature somewhere in the region of plus or minus 5ppb with the odd random shift of one or two ppb every so often (and a spooky reaction to my presence in the morning as I check its overnight drift).

 The stability of the TCXO was threatening to become an obsession but I think I've collected enough data to convince myself that it's just about as close to calibrated as a 0.1ppm TCXO can get. The next obvious step is to turn the GPS module into a self contained reference (with or without a 10MHz VCOCXO for it to discipline) with buffered outputs from which I can feed to the generator as a frequency reference locked to the GPS atomic clock standard.

 The TCXO module is at least two and half orders of magnitude more accurate and stable than the original XO chip so I'm satisfied that its self contained reference source easily exceeds the accuracy of any other kit I have which might be in need of a calibration check. Any later kit that might boast sub 0.1ppm frequency accuracy will almost certainly be equipped with an external 10MHz reference input socket of its own anyway (as will the FY6600 when I've finished modding it).

 To be fair, we've only suffered one 4 hour prolonged outage of supply in the thirty odd years we've lived at our current address and that was just about thirty years ago. I did happen to have my first Emerson30 UPS back then (I still have it but it's currently without a battery pack - two 7AH SLAs).

 The power went out in the early evening just as I was about to head off to the radio club so, after shutting down my PC, I moved it onto the first half landing to power a floor standing lamp with a Philips SL13  to keep the hallway and stairs illuminated as a safety measure. I had to leave it running since it couldn't be "Black Started". I don't think we had a downstairs toilet back then, just the one toilet on that half landing. It kept that lamp burning right through the outage, during which the children had used it to do their homework by. The power was back on by the time I returned and we've never suffered any further outages since (just one or two briefly lived brown out events and the odd brief dropout over the years).

 On the face of it, there seems very little justification to even keep a UPS up and running but I prefer to have such protection in place even against all perceived need. I know that Murphy will do his best to make my investment in UPS battery packs seem like a complete waste of money but the cost of a set of four 7AH SLAs, especially when the float charging voltage is turned down to the life prolonging 13.5v per 12v SLA from the life sacrifing for maximum autonomy of a brand new battery pack 13.8 volts that not just APC inflict as a default float charging voltage level is a small price to pay.

 Looking at how tight the reserve margin has become for winter demand on our national grid due to wilful neglect by recent governments since before the millennium, I'm thinking about the very real possibility of load shedding during our next severe winter. Whilst the SmartUPS2000 can handle extended battery run times given a larger battery (unlike the tiny 500VA rated units which rely on the small battery capacity to save them from burning out), the investment required in a battery capable of providing autonomy for 5 or 6 hours is way too high for my liking when taking into consideration their status as a "Consumable", even when the float charging voltage is chosen to extend the battery life.

 A 17AH battery pack as specified by APC for this UPS, would cost 150 quid or more so at just under a hundred quid, that inverter genset was an absolute bargain since it can run for over 5 hours on just a gallon of fuel. TBH though, I'd bought it to prove a point, the point being that it would be free of the overvolting effect on the AVR of a standard 2.8KVA unit by the pair of 4.7μF capacitors effectively in parallel across the mains input of the UPS which gets switched out when running on battery power.

 On the face of it, the 2.8KVA genset should have been the solution to providing longer term backup power via the UPS instead of being the problem it turned out to be. All this nonsense about "Poor Quality Power" from a small petrol powered generator was just total and utter bullshit. The real problem was this gross overvolting effect (north of the 275v mark) when presented with any loads possessed of the slightest hint of leading current (a single 4.7μF fluorescent lamp PFC capacitor was all it needed to induce overvolting). The excuse of off frequency and distorted waveforms was total bollix. I discovered just how tolerant of "Poor Quality" these UPSes can be. When you think about the horribly distorted mains waveform, this should really come as no surprise - the sine inverter output of a UPS or an inverter genset is purity personified compared to the mains supply.

 Having eventually proved my point (that only the inverter type of emergency genset can be trusted to be free of this overvolting issue), I realised that my underpowered generator may not be all that underpowered after all since virtually all of the lighting load had been upgraded to LED to such an extent that not only could I keep my IT kit running, along with the main TV set, I could light up every light in the house with power to spare for the central heating circulation pump.

 The only fly in the ointment was that the fridge would probably trip the generator, leaving the UPS to handle the surge and then start draining the below spec battery pack, necessitating a quick dash to the genset to trick it out of reset by killing the engine until it was almost stopped before unkilling it in the hope the inverter module had reset itself before the engine had actually come to a standstill.

 The trick works but it's a close run thing and hard to get right. If it does actually stop, it just means another go on the recoil rope starter. I've considered making up a current sensing relay that sheds any overload that risks an inverter shut down for the 20 seconds or so for the UPS to deal with the fridge compressor startup surge before restoring the power. Assuming such trickery will work, that just leaves the chest freezer to be managed if we have to ride out any prolonged outages lasting more than a day.

 A neat way to solve the fridge compressor startup surge issue is to upgrade to one using a VFD compressor but I haven't seen such technology used in anything but high end overpriced fridge/freezers. Since I'm not ever going to give house room to any such atrocity as a Fridge/Freezer of any sort, it looks like I won't be solving this little problem quite so neatly as the VFD compressored fridge solution.  >:(

 Those 2KW rated Workzone inverter gensets that Aldi started selling last year for nearly 300 quid looked like a more suitable alternative despite them costing some 50% more per watt of output. However, they turned out to be utter shite as I was finally forced to conclude after returning the third unit as "Not Fit For Purpose". Aside from the very serious issue of almost stalling when the 50% loading is increased to 95%, the other failing is that the fuel shut off is linked to the ignition kill switch so short of modifying the ignition kill switch wiring, you have no means of running the float bowl dry prior to putting it back into storage.

 The Parkside units very sensibly kept the ignition kill switch separate from the fuel shut off valve which endowed it with two features absent in the Workzone units. The first being the obvious benefit of running the float bowl dry with the less obvious one being that you could crank the engine on the pull cord with the engine kill switch turned off without fear of snatch back as you primed the float bowl using the vacuum operated fuel lift pump driven from the engine. Mind you, a fuel priming bulb to activate the fuel lift pump pneumatically independently of engine vacuum impulses would have been a nicer touch but at least you had a snatch back free option to do this on the pull cord.

 Mention of the fuel going stale and the need to dose it with a product like "Stabil" to extend its life, reminds me that it's been several months now since I last fired the Parkside up. Presently, it's sat in the unused front room with an almost full tank of fuel. There isn't anywhere else where I'd care to store it right now. Luckily, there's very little venting of petrol vapour so there's just the smallest hint of the smell of petroleum spirit to suggest the presence of some 4 litres of petrol in its tank. If the deterioration is due to the loss of the more volatile fractions, that bodes well for its long term fuel storage.

 Normally, I'd prefer to run it up for half an hour per month to run fresh fuel through the carb as well as make sure that it's ready to go and not developing any hidden problems through lack of use. I've been a little pre-occupied of late but I'll take the next opportunity to fire it up when the missus can't complain that I'm disturbing our neighbours' peace and quiet on a Saturday or Sunday afternoon. A weekday afternoon seems the least likely time to offend any of our immediate neighbours who may be cursed with overly sensitive hearing. That won't stop 'Her Indoors' from protesting, unasked, on their behalf, it just means I can better demolish her objections just as I have on previous occasions.

==========================================================================================

[EDIT 2020-04-15]


 I've been browsing these ancient posts trying to track down the point in time when I first mentioned the 85 ohm attenuator issue. Just like "Cat" in "Red Dwarf", I find myself distracted by these old posts of mine in much the same way that Cat gets distracted by every mirror reflection of himself, hence this edit for the benefit of others who may have recently discovered this topic thread and only now, some 14 months late, are acquainting themselves with the gory details of this "Fix-It-Yourself" function generator project so kindly provided by Feeltech.

 Today has been a rather pleasant sunny spring Wednesday (the third week , iirc - I've lost track- of the imposition of the Covid19 lockdown/social distancing measures here in the UK). This seemed an ideal opportunity to exercise both myself and that aforementioned Parkside emergency inverter generator (the very same unit - Lidl still haven't gotten round to offering these again as has been their normal annual practice).

 It must have been over six months since it was last given an outing and with a refuelling some 6 to 9 months earlier. Mindful of its nasty "Kickback" habit, as all such recoil started gensets are prone to, I turned the fuel on, set the 'eco' switch to 'non-eco', left the kill switch in the off position (no such luxury with that Workzone bag o' shite I'd sampled three of from Aldi before giving up my attempt at a cheap upgrade to an 1800W / 2000W peak output inverter genset) before turning it over a few times on the pull cord, ready for an actual starting attempt with the kill switch in the run position.

 It failed to fire up. Only then did I think to check if the choke lever had been moved back to the cold start position. Naturally enough (this is The Lord Murphy's playground, after all!) it hadn't. I moved the choke lever and turned the switch to "kill" before giving the starting cord another two yanks for good measure before setting the kill switch back to the run position for a second attempt. This time (and rather gratifyingly) it fired up on that "very first pull". It had proved no harder to startup than when I'd last run it up from a dry carburettor bowl state, indicating that the fuel hadn't suffered much (if any) deterioration whilst stored in the genset's tank (possibly a testament to how well sealed against loss by evaporation the filler cap provides)

 After a couple or three seconds, I took the choke off and left it to warm up for another half minute or so before setting it into 'eco' mode to enjoy a quieter no-load "idle" (a comparative term - full bore or non-eco mode is a matter of 4,600rpm versus the eco idle speed of 3,100 or so rpm) before carrying it to its allocated spot between the rear of the garage and the back wall.

 Surprisingly, as is typical of mid-week in normal times (these aren't normal times), none of our neighbours happened to be out and about in the surrounding back gardens to be slightly disturbed by what little noise could hop over the brick boundary wall from my strategically located 'generator slab'. Despite this, and as I've already mentioned, "Her indoors" played "Devil's Advocate" on behalf of those absent neighbours, suggesting that I relocate it to our front garden which, in order to avoid a pointless argument (men rarely never win such arguments), I did.

 To be honest, this was as much to satisfy my curiosity as it was to satisfy "'Er Indoors"'s demands since this was the one location I hadn't already tested out. This proved convenient for passing an extension lead through the basement window to reach my earth and neutral bonding point (an ex-mains filter plug fitted with a C14 socket repurposed to accept a C13 ended feed cable and pass the generator live and the local supply's ground and neutral connections cross bonded to those of the genset to the 13A "Filtered output" socket.

 This 'generator access point' is kept plugged into a handy unswitched twin outlet socket with the mains plug of the SmartUPS2000 plugged into the remaining socket to allow a swift manual transfer from mains supply to emergency generator supply. Having got everything set, I took a deep breath and transferred the UPS plug across to the genset access point socket and then strolled upstairs to check that this procedure hadn't crashed my desktop PC in my first floor office/workshop. The transfer from mains power to genset power had gone as smoothly as I'd expected with the UPS in this mix specifically to make such transitions seamless (the protection against supply outages is a given).

 APC specify a 17 or 18 AH 48v SLA battery for their SmartUPS2000 and I had recommissioned it back into 'Protected Supply' service almost two years ago with a set of 7AH SLAs simply as the cheapest possible way to run my inverter genset test to prove the absence of overvolting effect from capacitive (leading current) loadings that afflicts conventional gensets which boast the advantage of AVR.

 Despite my taking the precaution of reducing the life shortening float charging voltage setting of 13.8v per 12v SLA to a life prolonging 13.5 volt setting, I wasn't sure how well this 7AH battery pack had held up in its past two years of service. After strolling across the road to experience just how quietly the genset was running whilst supplying a 200W load, followed by a stroll up and down the road to look for any possible 'hot spots' noisewise, I had the pleasure of hearing a distant petrol chainsaw (maybe 100 or more yards distant) drowning out the genset noise at a distance of just 30 to 40 yards.

 When I got back to my office/workshop, I decided to try plugging in a 3x150W tungsten filament lamp load whilst listening to its effect on the generator through an opened window. Initially, I added each lamp load one at a time and heard the generator getting a little louder each time. This test confirmed that the mains extension feed to my 'workbench' was powered off of the 'protected supply' after all (I hadn't been sure since the tangle of cables had made it difficult to identify what was plugged into what by visual examination alone).

 A while later, I repeated this test with all three lamps plugged into their sockets which caused the UPS to sense the drop in supply voltage from the genset and switch to battery power, shedding its loading on the supply before the genset could react and sabotage the whole enterprise. The UPS would then restore the emergency genset connection after a few seconds delay to verify a restored supply and sync itself to the incoming supply frequency to effect a glitchless change-over.

 This was an unexpected bonus arising out of the use of a 2KVA 1.5KW UPS between the genset and its load. Not only did it afford protection against the genset giving up and falling over from a modest overload that exceeded its 1200W for 30 seconds rating overload trip out point, it also prevented the genset reacting immediately to greater transient overloads that would otherwise have immediately shut the inverter down, leaving the prime mover idling with no load.

 Unfortunately, this doesn't protect against modest sustained overloads in the 980 to 1180 watt range which would cause the genset to disable its inverter after 30 seconds, allowing the prime mover to keep running indefinitely and the UPS to exhaust its battery pack if the situation isn't remedied within a matter of minutes.

 That behaviour might well overcome the fridge's and the freezer's transient compressor starting overloads inducing a genset shutdown. The normal power demand of the fridge (and also very likely that of the chest freezer) is only some 70W or so at a 50% duty cycle (2 hours run time with 2 hours idle time having been noted for the fridge).

 The freezer can be manually managed by scheduling when it's allowed to run so we can shut everything off in the daytime for the brief period required to allow the freezer to successfully start up and then run it for the few hours required to bring the temperature down to -28 deg C so we can leave it disconnected for the rest of a 24 or possibly 48 hour period between scheduled restarts. The fridge is a little trickier to manage since it has less temperature margin to play with (1 to 8 deg C range at most if we want to avoid freezing stuff that should not be allowed to freeze - normally a 5 to 8 deg range).

 I have the impression that our fridge is near to the end of its life. I might replace it with a modern design that uses a VFD compressor that completely lacks this compressor startup surge current demand. Unfortunately, when I last looked at VFD based fridges just over a year ago, there were none. You had to resort to overly priced fridge/freezer models to take advantage of this technology (you pay one hell of a premium over and above the additional manufacturing costs + rational profit margin for this privilege).

 The main point of this edit is that provided you shut off the fuel feed and let the generator run the carburettor float bowl dry before storing it away for another 6 to 12 months, you're less likely to be faced with a 'gummed up' carburettor next time you come to use it. Also, the issue of fuel left in the tank going stale appears to be non-existent over periods of 12 months or so (at least in this case).

 As for the 20 litre jerrycan of unleaded, I'm hoping that'll remain viable for several more years yet. The seal on the filler seems to be gastight - there's not the slightest hint of petroleum vapour fumes to be had which bodes well for a long shelf life.

 As for our hoped for house move, we're still looking to relocate to a nicer locale and property. However, this Covid19 business has rather put a stop to casual house hunting excursions - we could well land up leaving our current property in a box or two for all we know. :-\  :(  >:(

[END_EDIT 2020-04-15]  I now return you back to the distant past  :)======================================


 If it comes to the matter of scrapping my boat anchors, I'll certainly be retrieving the valves to add to my existing, though modest, collection (along with anything else that might come in handy). However, that may be some years off. We're currently considering a move from this six bedroom semi-detached Victorian house into a more modestly sized house or bungalow (empty nest syndrome) with a garage/shed suitable for conversion into a workshop.

 The problem is that we're in a reasonably good area with good access to local amenities and we're undecided whether it's worth all the hassle and expense of moving to a smaller property in a nicer but less well served area or stick with the Devil we know and replace the garage (which was already a ramshackle affair when we moved in over thirty years ago and now in danger of collapsing in the next big winter gale) with a more substantially constructed garage come workshop that's actually fit for purpose.

 It's a rather frustrating position to be in but staying or leaving is a major lifestyle decision worthy of more than just casual thought. We've looked at several properties, mostly from the outside it has to be admitted - but there seems little point in proceeding to the guided tour unless you're happy with the surrounding area and the property's setting. Further developments along the line of fitting out a decent workshop are basically on hold for the time being.

 I'm reduced to tinkering about in a spare bedroom I'd commandeered as an office come computer repair workshop just over twenty years ago when going it alone as a sole trader in the business of assembling, selling and repairing desktop computers seemed such a good idea. Since I retired from this business some two years ago to collect my pension, the room has now become my "Man Cave". Hopefully, we'll arrive at a decision on whether to stay put or move onto greener pastures in the next few months to break the impasse we're currently facing.

 JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Zenith on February 20, 2019, 10:35:05 pm
@ Johnny B Good,

The boat anchor thing started over 20 years ago when a work colleague had to have his mother move in with him and had to get rid of much of his junk. He knew I had an oscilloscope and liked to mess about, so I ended up buying an AR88, spare valves and manuals for £50. After that the temptation was too much and came all the British WWII stuff, Eddystone, Hammarlund, Racal. It was mostly about £50 a pop and then came the test equipment and chasing down spare valves at radio rallies.

The test equipment followed and was fun to fix and use - for the most part. I have a Schlumberger sweeper which I've had a long rest from, but it will not defeat me.

There's a vintage domestic radio scene which seems healthy and organised, but I find the radios boring. It and the amateur radio scene fit into a boat anchor radio scene. There's a vintage telly scene, which I can see the point of, but don't want to be involved in. There's a vintage radar scene, which apparently involves big bucks. There's a juke box scene, I can see the point of, but it's big bucks and you need a lot of room. Test equipment is generally regarded as functional and complicated, so it's easily junked when something better comes along, which it does. Look at these DSOs and the FY6800. So it goes quite cheap, which suits me.

Then of course, there's the vintage audio scene, which rapidly merges into audiophoolery and nonsense on stilts. I despise it.

I have a couple of Z80 boards and they remind me of a kinder, gentler time, although it didn't seem like that then. A nice one fixing that 'though.

Yes, the old high performance stuff had to use expensive precision construction. A good engineer can do for a shilling what any damned fool can do for ten quid, but these people were good engineers. Times have moved on and we've found better ways of doing things, but what they did is still magnificent. HP and Tek in particular, seemed to go a bit overboard when it came to doing things right, but their gear usually seems to stand the test of time best.

As for the desire to tinker and time standards. Some amateurs have spent a lot of time and money on this. I'd like an off-air standard good for 0.1ppm at least. Don't R4LW receivers need a 198KHz crystal, which can probably be custom made for surprisingly little (£40???) and then you may as well use a published design and buy the circuit boards. A ton at least? I think I'll look into the GPSDO option.

As for where it will all end, I can't see it matters as long as you enjoy it and it doesn't impact others in your life; kids going barefoot to school because daddy has blown the loot on a caesium beam standard.

An energy policy constructed without a power generation engineer in sight is worrying. Also, energy policy is long term and so can't very well accommodate the fads of the hour. Most shops these days couldn't open without electricity. Your comments on this have made me reconsider things. In January, with a blocking high for a couple of weeks, things could get miserable. I suppose the least I'd need is 240V AC to produce  a maximum 50W to keep the central heating system going for a few hours. It could come from an inverter and the car battery. The Lidl generator is well worth a thought.

The stale fuel and generator idea came from a friend whose daughter ran a chicken farm. It had an emergency generator which was petrol fired, but when the power went off, always in the winter, daddy was called out to fix it, and the problem was stale fuel.

As for the house moving business, I've gone through the same process and have decided to go home, where property is cheaper, I can be with the folks I dig and can catch up on some fishing and shooting. It's a lot of work and a big decision, but the older you get the harder it gets.

It's been a pleasure to correspond with such a thoughtful person.

For anyone else following this long and possibly completely irrelevant post I'll bring it back to the FY6800.

IMHO it's a remarkable product for the money. It's a shame Feeltech haven't chased up some of the observations and improvements made and maybe incorporated them in a deluxe version or options at extra cost, then they could have had a killer product.

I'd recommend it without hesitation for anyone wanting a function generator and judging it by the standards of function generators. Features such as the burst function and arbitrary functions I can see being useful in sorting out knotty problems. It wouldn't cut the mustard compared to a halfway reasonable RF or decent low distortion AF sig gen. If you are interested in low level signals it's questionable.

Generally well worth the money.


 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 26, 2019, 09:24:12 am
@ Johnny B Good,

The boat anchor thing started over 20 years ago when a work colleague had to have his mother move in with him and had to get rid of much of his junk. He knew I had an oscilloscope and liked to mess about, so I ended up buying an AR88, spare valves and manuals for £50. After that the temptation was too much and came all the British WWII stuff, Eddystone, Hammarlund, Racal. It was mostly about £50 a pop and then came the test equipment and chasing down spare valves at radio rallies.

The test equipment followed and was fun to fix and use - for the most part. I have a Schlumberger sweeper which I've had a long rest from, but it will not defeat me.

There's a vintage domestic radio scene which seems healthy and organised, but I find the radios boring. It and the amateur radio scene fit into a boat anchor radio scene. There's a vintage telly scene, which I can see the point of, but don't want to be involved in. There's a vintage radar scene, which apparently involves big bucks. There's a juke box scene, I can see the point of, but it's big bucks and you need a lot of room. Test equipment is generally regarded as functional and complicated, so it's easily junked when something better comes along, which it does. Look at these DSOs and the FY6800. So it goes quite cheap, which suits me.

Then of course, there's the vintage audio scene, which rapidly merges into audiophoolery and nonsense on stilts. I despise it.

I have a couple of Z80 boards and they remind me of a kinder, gentler time, although it didn't seem like that then. A nice one fixing that 'though.

Yes, the old high performance stuff had to use expensive precision construction. A good engineer can do for a shilling what any damned fool can do for ten quid, but these people were good engineers. Times have moved on and we've found better ways of doing things, but what they did is still magnificent. HP and Tek in particular, seemed to go a bit overboard when it came to doing things right, but their gear usually seems to stand the test of time best.

As for the desire to tinker and time standards. Some amateurs have spent a lot of time and money on this. I'd like an off-air standard good for 0.1ppm at least. Don't R4LW receivers need a 198KHz crystal, which can probably be custom made for surprisingly little (£40???) and then you may as well use a published design and buy the circuit boards. A ton at least? I think I'll look into the GPSDO option.

As for where it will all end, I can't see it matters as long as you enjoy it and it doesn't impact others in your life; kids going barefoot to school because daddy has blown the loot on a caesium beam standard.

An energy policy constructed without a power generation engineer in sight is worrying. Also, energy policy is long term and so can't very well accommodate the fads of the hour. Most shops these days couldn't open without electricity. Your comments on this have made me reconsider things. In January, with a blocking high for a couple of weeks, things could get miserable. I suppose the least I'd need is 240V AC to produce  a maximum 50W to keep the central heating system going for a few hours. It could come from an inverter and the car battery. The Lidl generator is well worth a thought.

The stale fuel and generator idea came from a friend whose daughter ran a chicken farm. It had an emergency generator which was petrol fired, but when the power went off, always in the winter, daddy was called out to fix it, and the problem was stale fuel.

As for the house moving business, I've gone through the same process and have decided to go home, where property is cheaper, I can be with the folks I dig and can catch up on some fishing and shooting. It's a lot of work and a big decision, but the older you get the harder it gets.

It's been a pleasure to correspond with such a thoughtful person.

For anyone else following this long and possibly completely irrelevant post I'll bring it back to the FY6800.

IMHO it's a remarkable product for the money. It's a shame Feeltech haven't chased up some of the observations and improvements made and maybe incorporated them in a deluxe version or options at extra cost, then they could have had a killer product.

I'd recommend it without hesitation for anyone wanting a function generator and judging it by the standards of function generators. Features such as the burst function and arbitrary functions I can see being useful in sorting out knotty problems. It wouldn't cut the mustard compared to a halfway reasonable RF or decent low distortion AF sig gen. If you are interested in low level signals it's questionable.

Generally well worth the money.


@ zenith

 Apologies for the tardy response but I've had several distractions consuming my 'spare time' of late.

 I never became a 'collector' since I didn't have the space for more than the most basic of signal generator and 'scope kit, hence my only owning just two boat anchors. Of course, now that modern T&M kit is not only so relatively cheap but compact and lightweight, there is now a real danger of expanding my T&M gear into a collection that goes beyond my cheap (but excellent value) Siglent DSO and the even cheaper (and supremely excellent value) FY6600.

 Perhaps I will eventually land up investing in an SA and perhaps even a LA, keeping the existing T&M kit as backup to yet more highly specified versions that I might feel justified in splashing out on in the event that the needs of future projects will justify such extra expenditure. It's never a good idea to invest in T&M upgrades whilst the existing T&M kit can still serve its purpose even if not so conveniently as an overdue upgrade would do. Like desktop PCs, it's always best to wait until you can feel a tangible benefit from the upgrade rather than doing such purely for the 'bragging rights'. The longer you can put off an upgrade, the more value you'll get from the investment.

 As for vintage audio gear, whilst I respect it for the qualities that old fashioned valves (tubes) could offer (600v/microsecond slew rates versus the 2 to 10 volts per microsecond slew rates of 2N3055 power transistors) which belatedly revealed itself as SID in the first of the "modern solid state" power amps (the electronic equivalent of tracking distortion with pick up cartridges that were either set up with too little down force or else simply had too large an effective tip mass for even down force settings at the highest allowable limit could fix), the time has long since passed by where this is true. I don't see too much virtue in using such ancient valved gear other than as expensive (to both own and run) space heaters.

 I must admit to hankering after the simpler times of coding in Z80 assembler but I'm faced with a broken Transam Tuscan S100 bus home built from a kit desktop computer that had fallen victim to the damp basement environment I'd kept it in for two decades. I've got a spare main board which had been stored in a dryer and warmer part of the same basement which I'm planning on using, assuming I ever get round to testing it before applying all the necessary hardware mods required to undo the many "Skoolboy Howler" design errors that had been inflicted upon it (address decoding faults and tuning the modem chip used for the original tape interface to the 300 baud rate rather than the 1070/1270 Hz carrier frequencies used in the echo mode it was set up for (echo mode being required for tape storage use) being just two examples that come to mind right now - I'm sure there were other similar design errors).

 I don't think there are any cost effective Z80 versions of the cheap as chips Arduino Nano board I shelled a whole 3 quid out on just on the off chance that I might actually get to use it with my u-blox GPS module. If there were, I'd be into it in a shot since I'm so familiar with Z80 assembly, it's like an old friend. I guess I'll just have to resume my studies into C (actually open and read the "Beginning C" book I bought nearly three decades ago). They say, "You're never too old to learn.". Perhaps the Arduino Nano might give me enough motivation to demonstrate whether that saying has any validity or not (the three quid investment should, in my case, provide ample motivation!).  :)

 You don't need a 198KHz crystal to make up a 198KHz R4LW locked reference. You can use an old transistor radio with LW and a bunch of cmos ttl logic (divider chips) to generate a 2KHz tone locked to the 198KHz to mix with the 198KHz signal to generate a 200KHz reference from which to phase lock your 10MHz OCVCXO module at a 50:1 ratio as per the original 200KHz frequency standard that was used prior to the 9KHz channelising of the long wave broadcast band in (iirc, the late 60s) which so inconveniently resulted in the 2KHz drop in frequency that applies to this day.

 You can search for the original construction articles which will provide the necessary BoM by which to construct such a frequency reference but if your time is precious, you might do better to go the GPSDO route and create a more futureproof solution. The 10MHz OCVCXO will still be in the BoM list if you want to create a nice clean and steady jitter free 10MHz reference. Otoh, it is possible to use the 10MHz output from the u-Blox NEO M8N module directly as a frequency calibration source if you don't mind the low level of noise modulation (weird beeps) and the periodic 'ticking' at just under 1Hz which can be heard alongside of the 10MHz or its third harmonic when zero beating an HF rig to precisely the required frequency. Despite all these "Noises Off", it still makes a much better alternative to the 10MHz WWV broadcasts you just might be able to receive in around five years time.

 For the very first time today (yesterday in fact), I finally set my 'scope up on that pesky desk that sits in the window bay, close enough to let me connect to the GPS module's PPS output pin so as to actually get a picture of the waveform. It's a surprisingly accurate square wave shape at 10MHz allowing for the inevitable jitter you get from dividing the module's own internal 48MHz TCVCXO down to a non integer 10MHz output and the ringing created by using the longish "Ground Wire" connection to the probe tip circuit.

 I can eliminate the jitter by choosing frequencies of 12, 8, 6, 3 or 2 MHz so an obvious way to obtain a jitter free 10MHz reference would be to set it to output 2MHz and multiply back up to 10MHz with an ultra low jitter PLL chip programmed to give a 5 times multiplication. Indeed, there's little to stop me using the same jitter free PLL chip to multiply up from even lower frequency options which may well completely sanitise my 10MHz of all of the modulation noises including that weird not quite synchronised to once a second 'ticks' that appear in the modulation noise pollution. Using a PLL is a good way of filtering out such noise leaking onto the PPS output pin from the rest of the GPS module's digital processing activity.

 I managed to short out the gnd and 5v Vcc line with my 'scope probe which corrupted the antenna power settings, dropping the sat signals by some 30dB. The antenna settings, as usual, failed to be accepted until, as before, I programmed the module back to defaults, requiring me to reprogram its PPS line to 10MHz output and to reprogram the antenna power settings to get back to the 30 to 55 dB C/N levels I'd been getting prior to this little 'accident'. Just out of curiosity, I pulled the external antenna to see whether I could get usable signals from the module's built in patch antenna with microscopic LNA chip and found it was receiving almost as many satellites though barely strong enough to decode usable fix and time data. It seemed to be stable so I left it alone for a half hour or so only to find it had stopped receiving any satellites strongly enough get a lock on so had to reconnect the external antenna again.

 This issue with the built in patch antenna is a rather strange one which looks like it may just be a cock up in the reference circuit used with the microscopic LNA chip. I'm beginning to wonder whether a strategically placed resistor might restore a missing bias current/voltage to the LNA. This delayed failure has all the signs of a charge on a coupling capacitor biassing an ultra high impedance pin slowly decaying away, resulting in the LNA becoming disabled. You've read the other thread so you'll be aware that this is a problem that has been seen with at least one other similar M7N based u-blox module.

 Luckily, this isn't a "Show Stopper", just an irritating feature of a non functioning built in patch antenna that, by all accounts, could prove a serviceable alternative, given suitable reception conditions, to the use of an outside antenna. It would have been far better if the manufacturer had decided to forego the built in patch antenna option altogether and reduce their BoM costs (and, hopefully its final selling price).

 I've mentioned this before but I'd thought I'd raise the subject again. I've noticed (but only after doing the TCXO upgrade) that my FY6600 is sensitive to any HF transients causing it to effectively disable its outputs. Initially, almost every time I connected a grounded DUT to the BNC ground shields as it shorted out the voltage from the Y cap. Fitting the C6 mains connector and wiring the ground rail to the mains earthing pin via an 11K resistor cured this particular issue but I've recently discovered that it's still possible to recreate this effect by switching a lamp plugged into the same mains extension lead 4 way socket that serves the FY6600 with mains power on and off several times until the signal generator finally succumbs, disabling both channel outputs.

 The sensitivity to such mains borne transients is still there, it just needs more effort to recreate an effect I could guarantee almost every time just by simply connecting a grounded DUT to the signal generator. I suspect it's an issue that would go away whenever the generator is plugged directly into a ring main fed wall socket (or at least plugged into a mains extension lead that's not also serving any other potential switching transient  sources). I'm just wondering whether anyone else has witnessed similar sensitivity to such transients or whether either my TCXO mod has introduced such sensitivity or I've been just plain unlucky in landing up with a unit that was cursed with this defect to begin with.

 With regard to the residual distortion of the AWG at audio frequencies, this isn't necessarily a show stopper when it comes to determining distortion levels in audio gear since you can use what was once a common technique of nulling out the signal generator's signal voltage waveform from that of the output from the amplifier under test and look at what's left over (which is essentially the distortion signals introduced by the amplifier itself). Whilst a distortion free test signal is nice to have, it's not an essential requirement for measuring distortion levels in an amplifier.

 AFAICR, the distortion levels at audio frequencies are less than half a percent with these signal/function generators which is better than a lot of the older and venerated HP signal generator kit and more than adequate to get high quality measurements with. I wouldn't be too concerned with the distortion figures for a device intended to serve the needs of the hobbyist rather than that of a busy professional audio testing lab where time is money and speed of measurement is of the essence. The hobbyist user has the luxury of time by which to get results matching those of a professional testing lab which can justify the time saving costs of a 'distortionless' signal generator.

 Incidentally, when I came to run some tests with the Parkside genset a few days ago, involving the refrigerator as the test load, I discovered a fault that stopped it generating output from its inverter module. The symptoms are entirely indicative of a poor contact in the plug/socket connection between the PM generator output and and the inverter input. I've no doubt that this is simply the result of my 'starter motor' testing forcing the plug connectors open when I inserted the solid core wires obtained from a length of 2.5mm flat twin and earth mains cable to connect it up to the BLDC controller module I was using.

 I didn't bother to sort it out since I plan on doing yet more testing once I've determined the pole pair number of the PMG (which is where the 'scope earns its keep) and purchase a pre-programmed Adapter Board with AS5047P rotary encoder chip to provide the "Hall Effect" commutation signals to drive the BLDC motor controller with commutation signals that are hard locked to the rotor position (sensorless mode just doesn't cut the mustard in this application - the mechanical loading is far more difficult than that of a predictable fan or propeller load for a sensorless control algorithm to handle). The refrigerator load test can hang fire for the time being whilst I get things organised to verify the PMG pole pair number and place an order for that adapter board with pre-programmed chip.

 I had, rather optimistically, hoped I could get away with sensorless operation for my add on BLDC controller but tests revealed the stark truth that in this usage case, I have no choice but to use commutation signals that are positively locked to the rotor position after the fashion of a purpose made BLDC motor with Hall Effect sensors built in by design.

 The only consolation with retrofitting the PMG with HE signalling using the programmable AS5047P rotary encoder chip is that I get a superior position sensing system that outperforms that of even the best purpose made BLDC motor with HE sensors built into it by design. It involves a little more modification than that of merely adding extra electronic components, without gross mechanical modifications as I'd originally hoped, in that I now have to attach a magnetic disk to the end of the crankshaft and attach the sensor PCB to the crankcase mountings, positioned so as to detect the magnetic field from the sensor magnet.

 Sensorless operation only worked when the sparkplug was removed by way of testing that it was actually possible to run the PMG as a motor but as soon as I blocked the sparkplug hole with a finger, the extra load was enough to confuse the sensorless algorithm and put the controller into a stalled state. The test confirmed that, given a reliable position only dependant commutation feedback system, there was every chance that I could utilise the PMG as a starter motor - it just wasn't going to be quite so simple a task as merely adding a bunch of electronic components alone in order to achieve this.  :(

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: d3m0 on March 07, 2019, 06:13:43 pm
Hi everyone, I found this post looking for a cheap DDS. I read a few pages but my lack of knowledge makes me lost sometimes. My short question is: should I go for 6800 or 6600 model? both are kind same price....

Regarding to improving them What are necessary / recommended mods?

I catch:

  - Linear 317 337 PSU
  - Heatsink every chip gets hot
  - adding / changing opamps  <-- is there a specific post that explains it for a kid?  ;D


anything else? can be upgrade max frequency? I think 60Mhz for me is enough but if it's free.....  ::)


Thank you very much, great effort everybody.
 

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 08, 2019, 12:02:22 am
Don't get the 6600 as it has mains leakage voltages on the BNCs.

The sine wave performance of my 6600 at low output voltages compares very favorably to my Keysight 33622A which is a 120 MHz, 1 GSa/S AWG with a list of around $6500.  I got a used one from the Keysight eBay store for 1/2 that, but still my most expensive piece of T&M kit.  Ironically, I got a replacement front panel to fix my borked V3.0 unit just after I got the 33622A.  After 9 months of trying to get F***Tech to replace it.

At the moment I've got my 6600 which only has the grounding mod generating a 10 nS pulse at 1 V (2 V setting) into 50 ohms on a 1.5 GHz Lecroy DDA-125.  It's got a little bit of ringing, but the pulse is clean enough to use for time domain reflectometry and vector network analysis using a DSO with 10 Mpts or better sample depth.

That setup will give about 70-80 dB of dynamic range with an 8 bit DSO and suitable software which I plan to write.  It will provide VNA functionality up to the 6 m ham band at 50-54 MHz.  The same software will provide similar quality spectrum analysis.  It will only run on a PC, but it will do the job, albeit somewhat awkwardly.

A more ambitious project of mine is to develop FOSS DSO FW for COTS DSOs based on the Zynq and Cyclone V chips.  That will take a couple of years.  Right now I'm working on getting the data from the BNC to  memory with pipelined math operations in the FPGA PL on the way.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on March 08, 2019, 01:11:43 am
There is still some very good deals on what I assume is the last of the 50MHz 6600's on evilbay if your budget is lean. Forget the Linear supply upgrade and earth it like I did on about page 6 of this thread (I think about there). Treat it as a 'reasonable' Signal Generator and don't waste to much time and money on trying to make Champagne from Pig Swill.

Otherwise head for the 6800 as it seems to be firmware upgradeable at least  :horse:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: d3m0 on March 08, 2019, 11:42:40 am
Quote
Treat it as a 'reasonable' Signal Generator and don't waste to much time and money on trying to make Champagne from Pig Swill.

Yeah of course I'm conscient of what I'm buying. I don't want to waste time and that's why I'm asking here. I think changing opamps for a few bucks is worth the time and money. The improvement looked in pictures I think is great.

So... going for a 6800 and only change opamps? What about firmware upgrade and open  bandwith?


Thanks again!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on March 12, 2019, 01:34:22 pm
Neither the 6600 nor the 6800 is a waste of time or money (negative comments on here usually relate to problems with the earliest 6600s from 2017), but both can be improved quickly and cheaply.  Go for the 6800 (it has a better front panel) and fit new opamps.  Also fit a TCXO to give much better frequency accuracy and stop drift.  If you want to push the boat out, modify the existing power supply or fit a linear.  The upgradability is nice, but it's only relevant as long as Feeltech bother to produce new firmware for it, which probably won't be for very long - but there's nothing wrong with the existing firmware, so why worry about it?  That's really all there is to consider, unless you want to pay several times as much for a "branded" item which does much the same things.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on March 13, 2019, 02:25:00 am
Quote
Treat it as a 'reasonable' Signal Generator and don't waste to much time and money on trying to make Champagne from Pig Swill.

Yeah of course I'm conscient of what I'm buying. I don't want to waste time and that's why I'm asking here. I think changing opamps for a few bucks is worth the time and money. The improvement looked in pictures I think is great.

So... going for a 6800 and only change opamps? What about firmware upgrade and open  bandwith?


Thanks again!

 It all depends on what you're planning to use it for. If it's just for audio work or you're hardly going to push it beyond the 5v p-p level, upgrading the opamp and the PSU will largely be wasted effort. The dual THS3002i opamp only gets switched into circuit at settings above the 5v p-p "amplitude" mark and the 11.7ish volts on the +/- "12 volt" rails only becomes an issue with amplitudes close to the 20v p-p limit when you need to apply DC offsets of more than half a volt or so.

 At audio frequencies, the existing 50ppm rated XO chip is more than adequate for the job so upgrading that to a 0.1ppm TCXO would offer very little tangible benefit. However, regardless of all this, what is worth doing is the fitting of a small cooling fan to reduce the rather high internal temperatures due to the vent slots not being placed to make use of passive convective cooling to any effect (tilting it up on its kick stand actually makes the situation worse in this case).

 Although Feeltech seem to have taken notice of all the vociferous complaints about the issue of the half mains live 'touch voltage' and "done something about it" by upgrading the mains socket from the cheap 'n' cheerful IEC C8 unpolarised two pole connector, I'm afraid to say they've been a little slapdash over inflicting a heavy duty IEC C13/14 3 pole earthed connector on this 'tiny little doggy', giving it a tail that will wag it rather than it doing the tail wagging.

 Worse still, not only have they introduced a low impedance earth loop with its stray interference voltages and DC offsets from galvanic and thermocouple effects at millivolt output settings, they've compromised the ground return connection between the main board and the PSU zero volt rail by simply chopping one of the two ground wires to divert to the safety earth pin of the mains connector. It's as if they have no understanding of the pros and cons of the original floating class II arrangement, concentrating on fixing the "con" at the expense of the "pro".

 What this means for someone purchasing an FY6800 is that they need to undo the damage inflicted by Feeltech's bodging of the IEC C13/14 connector if they want to avoid seeing the mystery DC offsets (and ground loop interference) that Andreax1985 had reported when checking out his recently acquired FY6800.

 In short, this means disconnecting the safety earth wire from its connection into the chopped wire in the ribbon cable connector between the PSU and the main board, making good the damage inflicted by Feeltech by rejoining the cut ends. At this point, you can either add a 10K resistor between this joint and the disconnected earth wire from the IEC C13/14 connector's earth pin or else, find a better way to connect this resistor to the zero volt/ground rail to free this ribbon cable of Feeltech's bodgery.

 The PSU is still a class II item as before so doesn't require such a safety earth connection. All that was ever required of a polarised 3 pole mains connector upgrade with the FY6600 (and the FY6800) was a means of eliminating the half mains 'touch voltage' leakage via the EMC mandated Y class capacitor.

 In this case, a 10K resistive connection serves this function very nicely, attenuating as it does, the unwanted stray galvanic dc voltages and mains borne interference by some 60 to 80 dB, neatly limiting the half live mains voltage to, worst case on 240v mains, just half a volt ac which neatly addresses the issue of damage to any devices being tested through high voltage discharge from the class Y emc bodge capacitor in the PSU.

 If you feel that even half a volt ac is still too much of a risk, you can use a 1K resistor instead to get this down to 50mV ac and still attenuate the earth loop induced galvanic and noise voltages by some 40 to 60 dB. This resistive earth connection is essentially a very low impedance static discharge drain connection rather than a class I (III?) protective earth.

 Of course, the problem of doing any mods like this, no matter how urgent or essential, is the issue of "Voiding The Warranty". Unless you've bought this via a local Agent bound by your country's consumer protection laws, even when you have a valid warranty claim, the extra pain of dealing directly with Chinese suppliers can be sufficient to put you off making a claim when the original cost is so low as to make any out of pocket expenses (whether temporary or not) look out of all proportion to the benefit.

 Although the cost of these products is 'chump change' compared to the cost of  just the next quality level up (Siglent territory), it's right on the edge when it comes to deciding whether  to "Collect on the warranty or just write it off?". The sensible approach in this case would be to allow enough time for any manufacturing defects to show themselves within the 30 or 60 day return period before embarking on any warranty voiding modification work even if you've already decided that you'd write it off rather than face the hassle of trying to collect on a "Chinese Warranty" in the event it fails outside of that initial period.

 Although the earth loop and fan cooling mods are urgent and necessary mods, you can provide non invasive fixes by making up a special mains (extension) lead with a 10 or 1 K resistor in series with the earth wire and use a small desk fan to blow cooling air over the back of the generator to mitigate the excessive temperatures until you're ready to take the plunge into more elegant, yet warranty voiding, fixes once the honeymoon period is over.

 All of the improvements that were applied to the FY6600, are all equally applicable to its successor (including the half live mains leakage earthing mods - the bulk of the effort has already been applied by Feeltech, it just needs to be refined to eliminate the mains earth loop issue they'd introduced). It's basically just a question of deciding which, if any, of those mods are worth doing.

 Regarding the possibility of firmware updates/hacks to expand the frequency range past the current 60MHz limit, that seems rather doubtful since beyond 60MHz, you'll need to modify the 5th order anti-aliasing LPFs on the main board to nudge them closer to the 125MHz Nyquist limit.

 Being an arbitrary wave function generator, there's nothing to stop you loading a sine wave that's all 2nd harmonic and no fundamental to double up the output frequency to test the response of the on board LPF to identify exactly where the cut off frequency has been set to. ISTR a figure of 75MHz being mentioned a year or so back in this thread.

 This trick of loading a custom sine waveform into one of the arbitrary wave slots might be a handy work around to the 60MHz limit to get a useful signal output in the 4 metre amateur radio band (and possibly even into the VHF/FM broadcast band if all you need are a few tens of millivolts of signal output).

 The chances of Feeltech ever doing a firmware upgrade to raise the frequency limit to 75 or 80MHz seem pretty slim in view of the existing LPF's turnover frequency somewhere around the 75MHz mark. If they CBA to fix their 85 ohm attenuator goof, what chance is there that they'd modify the LPF filter components? In any case, such a raising of the turnover frequency would also require a steeper roll off to avoid aliasing problems above the 125MHz Nyquist limit so they'd need to upgrade it from its current 5th order design to a 7th or 9th order design which would probably only be practical using separate filter modules in place of the existing filter network components.

 Experimenting with a custom arbitrary sine waveform to explore the frequency response of that filter should give you some hint as to whether Feeltech are likely to extend the frequency limit with a firmware change in a later version of the FY6800 as they've done in the past with the FY6600 models. The existing filter might just allow Feeltech to offer a 75 or 80 MHz option but don't expect to see a 120MHz version in the same sort of price bracket any time soon.

 At the end of the day, these Feeltech signal generators are what they are, damn good value for the money 'wartified' versions of their more expensive cousins with the bonus of being amenable to several cost effective enhancements to cure it of the worst of its wartiness.

 The biggest danger for most of its users is that of getting carried away with the scale of these attempts to turn this particular "Sow's Ear" into a "Silk Purse". If you can dial your ambitions down from "Silk Purse" to "Rayon Purse" in this particular pursuit of perfection, that should save you from losing all sense of proportion and getting sucked into a never ending upgrading project that's taken on a life all of its own.

 The trick to this is knowing when to call time on the project and say, "Enough is enough! My work here is done.". For something as cheap as this, I'd say a good rule of thumb to apply is that once you realise that you've spent as much on the upgrade components as you've done on the whole generator itself, you've gone about as far as is sensible, if not further, and it's now time to insert those long case screws (mine have been a permanent workbench exhibit for the past 4 months now) for the very last time and be done with it.

 If your requirements for perfection increase with more ambitious projects later on, let the quote from the "Jaws" movie, "We're going to need a bigger boat" be your guide as to the solution and move upmarket to something better again. Your old,Feeltech AWG can always be boxed up and put into storage as an emergency generator - after all, it's not exactly a "Boat Anchor" that's likely to give you a hernia in ten years' time when you're eventually forced to have a clear out. :-)

 BTW, I thought I'd attach a picture or two of interest. The first one shows my permanent bench exhibit of the four case screws to the bottom left in the foreground. The u-Blox NEO M8N GPS module is just to the right, powered from a 5v wallwart with a 14cm  3/4 wavelength wire antenna plugged into the SMA socket (the built in Patch antenna only works sporadically due to a suspected error in the LNA 'reference circuit' used by the manufacturer) to receive some 6 to 12 satellites whilst a good 16 feet away from the window.

 It's set up this way because the eight metre (correction: 5 metre) active antenna cable won't stretch to the workbench. The scope is displaying a perfectly jitter free 2MHz squarewave on the PPS line. The 'ringing' as anyone observant enough to spot, arises out of the excess 10 inches' worth of earth clip lead between the probe and the zero volt rail of the GPS module.

 The second photo is a screen capture showing the rather horrific level of jitter you get when dividing a 48MHz TCVCXO clock  down with a non-integer division ratio to obtain a 10MHz clock. This demonstrates why I have three ON SEMICONDUCTOR - NB3N502DG - PLL CLOCK MULTIPLIER, 8SOIC chips winging their way to me as I type.

 The plan being to multiply the already jitter free 2MHz back up to 10MHz with just a mere 40ps p-p jitter on the clock multiplier's output (interestingly, with rise and fall times specified at just 1ns) to make a "Poor Man's GPSDO frequency calibration reference source" that's good enough to use as an external 10MHz clock supply for anything that has such an external 10MHz reference socket (currently nothing right now until I modify the FY6600 with such an option).

JBG

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 13, 2019, 11:08:43 pm
Absolutely fantastic post!

With regard to the frequency response of the factory units, my FY6600 will produce a clean 10 nS pulse at a 10 MHz repetition rate.  I've not looked at it on my LeCroy DDA-125yet, just an Owon XDS2102A I bought for the sake of the 12 bit 500 MSa/S ADC and 20 Mpt buffer depth.  The Owon showed a bit of ringing after the impulse, but until I do some more testing I don't know which is responsible, the DSO or the AWG. The Owon does not have a 50 ohm input, so the thru terminator may be a factor.

I've got a Tek 11801 supposed to arrive Friday.  I received a pair of 12.5 GHz, 23 pS rise time SD-22 sampling heads today.  So with  a bit of luck and hard work I might have some good data on the F***Tech next week. Then I have to contend with how to test things like the SD-22, or worse yet, an SD-32 with a 7 pS rise time.  I started a thread in Metrology on generating <3 pS rise time steps. I swore I'd stop at 3 GHz, but TEA got me anyway.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on March 19, 2019, 12:46:46 am
Absolutely fantastic post!

With regard to the frequency response of the factory units, my FY6600 will produce a clean 10 nS pulse at a 10 MHz repetition rate.  I've not looked at it on my LeCroy DDA-125yet, just an Owon XDS2102A I bought for the sake of the 12 bit 500 MSa/S ADC and 20 Mpt buffer depth.  The Owon showed a bit of ringing after the impulse, but until I do some more testing I don't know which is responsible, the DSO or the AWG. The Owon does not have a 50 ohm input, so the thru terminator may be a factor.

I've got a Tek 11801 supposed to arrive Friday.  I received a pair of 12.5 GHz, 23 pS rise time SD-22 sampling heads today.  So with  a bit of luck and hard work I might have some good data on the F***Tech next week. Then I have to contend with how to test things like the SD-22, or worse yet, an SD-32 with a 7 pS rise time.  I started a thread in Metrology on generating <3 pS rise time steps. I swore I'd stop at 3 GHz, but TEA got me anyway.

@rhb

 It's very kind of you to offer your thanks for that post. The more usual response I've had to similar posts made in usenet groups in the past have tended to be of the "TL:DNR" kind, leaving me feeling as though I'd just been casting pearls before swine.  :(

 What I miss in posting into a web forum is usenet's ease of use. However, what I definitely don't miss in posting to this web forum is all the back biting, personality clashes and outrageous displays of personality disorders and the out and out troll postings so typical of usenet.

 It's such a refreshing change not to have one's efforts at making a positive contribution to a discussion being disparaged for its "full and comprehensive coverage". To some extent, I do see their point when in retrospect, I attempt to read out my paragraph length sentences out loud without turning blue from lack of breath.  >:D I guess the folks here must have much longer attention spans (and not have to move their lips when reading).  ;)

 In any case, I post not to seek glowing testimonials for my prose so much as simply to try and contribute something useful or interesting to the discussion so no further thanks are sought nor desired. However, do feel free to pull me up whenever I make any errors or commit omissions. I'm not seeking to lay down ground rules to insulate me from receiving any well deserved criticisms for such errors and/or omissions whenever I might be so careless.  :)

 Having dealt with the "Thank you" for the "Thank you" note, it's back to the business in hand, namely the pulse performance of the FY6600. I'd assumed you'd been referring to the 'impulse' waveform and so tried it with my AWG for comparison. I must have misinterpreted your meaning of the waveform but this is one that's always been problematical for me (presumably because I failed to take note of the much lower upper frequency limit that applies). However, at exactly 2MHz, the impulse waveform disappears. It was only after trying lower frequencies such as 10 and 100 KHz that I realised that there seems to be a bug in that at exact multiples of 100KHz, the impulse disappears completely!  :-//

 Further investigation reveals that it stops producing predictable pulse repetition rates above the 32KHz setting. After checking the specifications given in the user guide appendices, I see that the upper frequency given for pulse waveforms is quoted as 10MHz. However, the minimum pulse width is specified as 20nS which seems to be at the heart of the 32KHz limit for the impulse waveform since it reduces below this limit at a mere 8KHz, growing fatter as the frequency is reduced until at 10Hz, it becomes a 120 microsecond wide impulse, reducing in proportion to the period of the pulse repetition rate before it hits the 20ns limit at 8KHz dropping to 10ns at 15KHz before finally dropping to a reduced amplitude pulse at the limiting width of 8ns at 32KHz after which, the repetition rate just goes to pot.

 I guess that's simply the consequence of trying to provide an impulse waveform from an arbitrary one loaded into the predefined memory slot labelled "Impulse" which makes it one of the least useful of the preloaded waveform options in the machine if you're regularly working with frequencies beyond the audio range. I ended up using the Sinc waveform at 2MHz to trigger my scope when I was comparing the 2MHz PPS signal from my GPS module.

 Having run all those tests on the impulse waveform, it has now become quite clear that you weren't referring to this one but most likely the square waveform, possibly at the 10% duty cycle, assuming you were referring to the width and not the Tr and Tf times which on a 20% duty cycle on mine, gives a clean 20ns wide pulse with Tr and Tf times of 6.8ns according to my Siglent SDS 1202X-E.

 My ambitions to owning fast rise and fall time square wave/pulse generators are rather more modest than yours. For my immediate needs, sub nanosecond will do me for the time being since I'm only interested right now in verifying Siglent's claim of Tr and Tf figures of 1.8ns for the 1202X-E. The FY6600 can only offer at best a mere 4ns or so with a following wind so nowhere near anything to tax the scope.

 The 1ns rating for the NB3N502 clock multiplier chip and the quad clock buffer chips is just quick enough to verify the validity of Siglent's claim which is why I mentioned it. One nanosecond is just the beginning of my possible adventures into the world of picosecond timings.

 Regarding the 3N502 chips, I might have goofed with that choice of clock multiplier since, deep within the pages of the data sheet, there is a reference to a minimum lower frequency limit of just 14MHz on its output. I'd overlooked this fact when seeing the minimum multiplier option of 2 along with a minimum clock input frequency of 2MHz so I could find myself having to multiply the 4MHz PPS output to 20MHz and follow it with a divide by two flip flop chip if it turns out that 10MHz is actually too far beyond the range of the 3n502's lower frequency output limit to work or work reliably. I've got some more testing to do.

 In the meantime, in case you've not read my latest postings to the u-blox GPS module thread, I've managed to successfully divorce the ornamental Patch antenna from the module and repurpose it as a plug in passive antenna, proving that there wasn't anything wrong with it, other than the very strong possibility that it should never have been glued to a groundplane containing some signal carrying tracks in the first place.

 Indeed, it works noticeably better than that 3/4 wave wire antenna I'd made up to test the module whilst awaiting delivery of an active mag mount patch antenna with a 5 metre SMA male plug terminated cable (bargain of the year at a mere 3 quid from a UK supplier apparently, since I couldn't find anything as good for less than a fiver - even passive patch antennas from China were only a quid cheaper!).

 Anyway, now that I've sorted out the mystery of the useless patch antenna, I can procrastinate no longer over the question of the 3N502 chips and 10MHz output. I'm finally going to assemble one into a test jig on a plug in breadboard and face the consequences.

JBG
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 19, 2019, 02:27:31 pm
JBG

As a practical test instrument one of Leo's 40 ps square wave units is the way to go unless you  insist on building it yourself.  Leo is using a Maxim 3949 LED driver with 22-36 ps Tr and Tf.  There is a moral hazard in buying one though.  After you look at the plot of your unit made with Leo's CAS803 using and SD-30 head you may want one for yourself.

Interestingly, my quest for a really fast edge has brought me full circle to the problem of reverberation due to a source embedded in a layer with a perfect reflector at one boundary.  Which also turns out to be the same problem as constructing an ultra wide band antenna using an unbalanced feedline.

I'm using the F***Tech FY6600 V 3.1 "Adj Pulse".  The settings for the attached figures are:

10 MHz frequency
2 V amplitude
10 ns pulse

I've not observed any repetition rate issue other than the BW limitation of the output.  I was able to raise the repetition rate to 60 MHz.  I think it worth noting that CH1 stopped producing output when set to "Adj Pulse".  I then tried CH2, but it does not have "Adj Pulse".  However, when I went back to CH1 and changed the waveform settings the 10 ns pulse returned.

I tried the "Impulse" and it is very poor relative to the Adj Pulse.


I'm using an Instek MSO2204EA with a 50 ohm thru termination taking the outputs with a 2 ft piece of RG-58.

DS0004 & DS0006 are the FY6600 going as fast as it will go.  DS0005 is a Keysight 33622A going as fast as it will go.

DS0004 is with the amplitude at 2 V and DS0006 is with it set to 0.5 V.

DS0007 is my 100 ps pulser from Leo.  Leo-spike is the CSA803 & SD-30 (9 ps Tr, 40 GHz BW) results.

The Keysight is clearly *very* good, but at a list of 60x the F***Tech.  The apparent ringing on Leo's impulse generator is the result of Instek using a zero phase sinc(t) interpolator instead of the correct minimum phase interpolator.   Setting dot mode turns off the interpolation and with infinite persistence you get the result shown in DS0008.

BY digitizing the plots Leo provided and DS0008 one could derive the transfer function of the Instek AFE.

I think it worth noting that for testing scopes, Leo's square wave unit is a better choice.  I have both.  The impulse unit is much more convenient for TDR work.

Have Fun!
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on March 21, 2019, 12:54:14 am
JBG

As a practical test instrument one of Leo's 40 ps square wave units is the way to go unless you  insist on building it yourself.  Leo is using a Maxim 3949 LED driver with 22-36 ps Tr and Tf.  There is a moral hazard in buying one though.  After you look at the plot of your unit made with Leo's CAS803 using and SD-30 head you may want one for yourself.

Interestingly, my quest for a really fast edge has brought me full circle to the problem of reverberation due to a source embedded in a layer with a perfect reflector at one boundary.  Which also turns out to be the same problem as constructing an ultra wide band antenna using an unbalanced feedline.

I'm using the F***Tech FY6600 V 3.1 "Adj Pulse".  The settings for the attached figures are:

10 MHz frequency
2 V amplitude
10 ns pulse

I've not observed any repetition rate issue other than the BW limitation of the output.  I was able to raise the repetition rate to 60 MHz.  I think it worth noting that CH1 stopped producing output when set to "Adj Pulse".  I then tried CH2, but it does not have "Adj Pulse".  However, when I went back to CH1 and changed the waveform settings the 10 ns pulse returned.

I tried the "Impulse" and it is very poor relative to the Adj Pulse.


I'm using an Instek MSO2204EA with a 50 ohm thru termination taking the outputs with a 2 ft piece of RG-58.

DS0004 & DS0006 are the FY6600 going as fast as it will go.  DS0005 is a Keysight 33622A going as fast as it will go.

DS0004 is with the amplitude at 2 V and DS0006 is with it set to 0.5 V.

DS0007 is my 100 ps pulser from Leo.  Leo-spike is the CSA803 & SD-30 (9 ps Tr, 40 GHz BW) results.

The Keysight is clearly *very* good, but at a list of 60x the F***Tech.  The apparent ringing on Leo's impulse generator is the result of Instek using a zero phase sinc(t) interpolator instead of the correct minimum phase interpolator.   Setting dot mode turns off the interpolation and with infinite persistence you get the result shown in DS0008.

BY digitizing the plots Leo provided and DS0008 one could derive the transfer function of the Instek AFE.

I think it worth noting that for testing scopes, Leo's square wave unit is a better choice.  I have both.  The impulse unit is much more convenient for TDR work.

Have Fun!
Reg

@rhb

 Thanks... I think.  :)

 It took me several minutes to tie the descriptions to the scope trace captures before I could appreciate what they were showing me. Not a criticism, just a reflection on the complexity of describing the results even with "pictures that (are supposed to) say a thousand words" and the fact that I wasn't at my sharpest at five in the morning. I'm a Night Owl but even I have my limits which I all too often exceed.  :(

 I happened to be using CH2 of the Feeltech (it's less of a stretch for my half metre RG58 BNC lead to reach the scope's CH1 input) to trigger the scope against the 2MHz square wave on the PPS line being displayed on CH2 so I too fell foul of the 'missing adj pulse' option until I re-read your experience and repeated those same steps to discover, as you did, that extra option that curiously only exists in the Feeltech's CH1 wave menu.

 I didn't go all the way to 60MHz, just the 10MHz point but I could see no difference in the pulse shape between 10 and 2 MHz so figured I wasn't going to discover anything new at the 60Mz setting. I got similar rise and fall times (just over 4.5 and 4.6 ns) which didn't alter with pulse width (I tried 10 and 20ns - the latter looks like a nice approximation to a square edged pulse on the Siglent). I didn't see any change either in the timings with amplitude settings right up to the 20vp-p limit (I guess I have the THS3491 opamps to thank for that) so set it to 5vp-p for the rest of my tests.

 Rather intriguingly, the GPS module's drop/add of a 20.8333ns pulse from the 48MHz TCXO clock to keep it in sync with GPS time displayed a hiccup effect on its once per half to five second correction interval I'd been observing over the past few days that I've been assessing the module's suitability to directly generate a 10MHz reference even with the help of that 3N502 clock multiplier chip (if it'll function at such a low output frequency) to get rid of the horrendous jitter that arises out of trying to directly divide down to 10MHz from a 48MHz clock.

 Going back to the Sinc waveform eliminated this hiccup effect, taking it back to its normal synchronising behaviour. Presumably, there's something going on with the adj pulse that's introducing this hiccup effect but I haven't had a chance to investigate this oddity any further. As for the impulse wave option, that's barely good enough for use in the audio frequency range being somewhat useless at any frequencies beyond the absolute limit of 32KHz. You can get output in the MHz range but you need to be aware of it's random repetition rate and the fact that it disappears entirely at exact multiples of 100KHz.

 The NEO M8N module I'm experimenting with is endowed with a 48MHz TCXO rather than a simple XO but it's not adjusted in frequency to keep it locked to the GPS clock signal as I'd originally and rather naively thought had been the case. It's quite clearly left to run at whatever frequency the TC happens to adjust it to and the control is merely a matter of dropping or adding an extra cycle to keep the PPS synced to GPS time regardless of the chosen frequency it's been programmed to run at.

 The lower the frequency, the smaller these phase shift adjustment steps become. I programmed the PPS to 12MHz (another jitter free division ratio) and saw the expected 90 degree jumps, confirming my estimated 15 degree jumps at 2MHz (I plan to multiply this back up to a jitter free 10MHz with the 3N502 chip - or failing that, 20MHz followed by a divide by two flip flop).

 Depending on the time constant used in the 3N502's PLL circuit, this might give me a sufficiently sanitised 10MHz clock reference suitable for use by T&M and communications kit, possibly helped by filtering to a pure sine wave output. This is something else for me to investigate once I've steeled myself to set up the clock multiplier chip add-on.

 I suspect the only way to overcome these phase shift jumps will be to throw a VCOCXO module into the mix but I'd like to justify this expense for myself before shelling out on one. I don't mind the expense of a component when I know without any shadow of a doubt why the component in question is absolutely indispensable to the whole project.

 The mention of my GPSDO project above might look like 'topic drift' but it is germane to my plans to modify the FY6600 to accept an external 10MHz frequency reference as per Arthur Dent's contribution to this thread over a year ago. At least one of the three 3N502 chips I bought will be getting put to good use in this planned modification.  :)

 Obviously, there's no point in adding a 10MHz external clock option without there being a realistic chance of acquiring or fabricating a GPSDO to drive it. I could run the two jobs side by side but I'd prefer to get the GPSDO sorted out (if not fully completed) first before attacking the FY6600 with yet another modding effort. As dramatic an improvement to the frequency stability and accuracy as I've made to my FY6600 with that 50MHz 0.1ppm oscillator board, that's just been a taster of what can be achieved with a GPSDO reference.

 That basic oscillator upgrade had allowed me to run tests with the current GPS module that would have been virtually impossible with the original oscillator chip which had turned the business of trying to compare frequencies with the 'scope into a game of "Chase Will 'o the Whisp". As good as it now is, I just want the even better frequency accuracy and stability that only a GPSDO can provide.

 I completely understand your own TEA issues. I might think I'm not going to be going to the same "extreme" right now but, after reading, back in November, Arthur Dent's OCXO mod with the intention of adding a 10MHz external reference socket and thinking it was rather an OTT modification and electing to go the cheaper TCXO route instead yet now finding myself going to the same "extreme" of adding an external 10MHz reference socket, I'm not quite so sure I'm as immune to TEA as I think I am after all. :-\

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 21, 2019, 02:05:37 am
There were 3 signal sources,  The 6600, the 33622A and Leo's 100 ps impulse.  The DSO sinc(f) issue is *only* visible on the 100 ps signal when the DSO is sampling at 1/10th of the pulse duration.

I have one of Leo's two  channel GPSDOs which has been extremely satisfactory.  The single channel version is cheaper.

I bought a 6 output 10 MHz GPSDO from Roadrunner, but have not yet gotten around to testing it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: TheDefpom on March 22, 2019, 04:52:58 am
In case it is helpful here is my review of this unit, I didn't see it posted in here already.

https://www.youtube.com/watch?v=aNgRuEJ0rF0 (https://www.youtube.com/watch?v=aNgRuEJ0rF0)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on March 31, 2019, 07:39:47 pm
Thank you Johnny B good for the picture.

Where did you put the minus of the TCXO power supply TCXO (it's seems to go the the earth) and why there resistor (and value)?

Have you made any changes on the power supply (except the ferrite)?

 Hi Gege34,

 I used the co-ax braid for the ground return (-ve) to avoid ground loops. The white wire is the 5v feed picked up from the +5v pin on one of that group of regulator chips. The resistors you can see are a bunch of three 33K resistors in parallel using the -ve screw terminal on the module as a convenient connection point with the other end of the resistors wired to the safety earth pin on the mains socket (it knocks the 90v leakage right down to just under half a volt and neatly avoids mains earth loop issues.

 As far as the smpsu board goes, I've lost count of the number of times I've had it out on the bench for the various modifications I've tried on it. However, the first mod was to wire a 47K across the lower half of the voltage feedback potentiometer formed by the two 10K resistors between the +5v and the 0v rail to boost the 5v to 5.5v in order to raise the 11.5 volts on the "12 volt" rails to somewhere around the 12.7v mark. This wasn't quite enough, even after replacing the weedy rectifier diodes with 20A dual shotky rectifier diodes so I ended up modifying the transformer to add an two extra turns on each end of the 24v centre tapped winding feeding the 12v rails. This raised the voltage to somewhere in the region of 13.7v or so.

 In hindsight, I should have just upgraded all three rectifiers and then added a single turn overwinding to the transformer to buck the 5v winding, forcing the switching IC to compensate and so neatly increase the 12v rails without altering the 5v rail voltage and avoid modifying the transformer since there is ample room to thread (three or four lots in parallel of) the single turn of wire around the existing windings without having to remove the transformer from the PCB as I'd had to in order to to access the ends of the 12v windings in order to unsolder them from their solder tags so as to extend each winding another two turns each.

 Connecting this one turn buck winding is just a matter of lifting the anode end of the 5v diode from the board and connecting the ends in series with the diode's anode and the vacated hole on the PCB. If you connect it series aiding on your first attempt (a matter of dumb luck), all that will happen is that the 12v lines will drop in voltage, leaving the 5v untouched which simply means you need to flip the one turn winding connections round to buck the 5v, forcing the 12v rails to increase in voltage.

[EDIT 2019-03-31]

 I finally got round to undoing the original transformer mod yesterday afternoon to try out the single turn winding to buck the 5v secondary's output voltage as per the above. Not surprisingly, I had to reverse the connections to make it buck the 5v secondary.

 It worked just as I'd hoped it would. However, when it was connected 'aiding' the 5v didn't get above 3.96v (I suspect maybe due to too large a smoothing cap on the 5v rail) leaving the 12v rails  registering just over 8 volts each. Undismayed, I reversed the connections and tried again. getting +4.94v (I'd removed the 47K voltage boosting resistor), -12.98v and +12.83v. I wired in a 200K voltage boost resistor which then gave me +5.07, -13.29 and +13.13 volts which seemed to be close enough to the optimum. I didn't want to go much above the 5v mark in order to reduce the dissipation in those three very hot running LDOs on the main board and the 3.3v LDO on the 50MHz 100ppb TCXO oscillator board itself.

[END_EDIT]

====snip====


 This is just a follow up on the latest version of my PSU modification exercises showing some pictures for the benefit of anyone else who may be contemplating a similar modification. I wish I'd had this "Brilliant Idea"(tm) before I blundered in with my not quite so clever idea of adding two extra turns onto the 12v windings - it would have simplified the whole process and saved a lot of solder into the bargain. Never mind, better late than never. I guess the electronic version of the saying, "Measure twice, cut once!" must be "Think Twice, solder once!". :-[

 The first picture is a view of the overly heavy gauge wire used to overwind four single turn windings in parallel, I could have (and should have) used much thinner wire. It would have eased the job significantly but the temptation to fill that vast clearance around the bobbin overcame common good sense. :(   If I'd used thinner wire, the job of reversing the connections would have been a lot easier (I'd had to unsolder the transformer yet again just to reverse and preform the tails to go back into the hole on the board and line up against the lifted out diode lead).

 The ideal way to form this additional one turn winding is to take suitabley gauged insulated wire (in hindsight some 6 to 8 pieces of much thinner wire) long enough to let you strip only the starting ends with ample to spare to allow them to be trimmed to length and stripped once all the ends of each turn have been twisted tightly together to hold the turns in place to create a low leakage inductance link to the diode and the vacated hole in the PCB. The already stripped ends, identifying the start of each turn can then be picked out and further twisted together and tinned ready for the final connection, allowing the untrimmed ends to be likewise gathered together, trimmed , stripped, twisted together and tinned ready to make the other remaining final connection.

 Provided you've chosen a suitably flexible wire gauge, in the event that the connections need to be reversed, this final corrective task should be fairly trivial with no need to remove the transformer at this or any other stage of this modification. As you can see, I didn't choose my wire gauge wisely, making a rod for my own back when Murphy pounced.  :-[

 The second picture is an attempt at showing the connections to the PCB and the lifted up diode lead, showing just how little clearance there was between the solder blobbed PCB wire and the diode lead. I'f I'd spotted this blob of solder at the time, I would have inverted the board and sweated out that surplus solder to increase the gap (just as well it's only a matter of 10 or 15 volt peaks rather than the 350 v peaks of 240v mains).

 The last picture is essentially just a wider view to provide context (it also shows where I added the 200K resistor to lift the +4.94v to 5.07v to give a little extra boost to the 12v rails (now -13.29 and +13.13 volts with a very light loading). Subsequent testing, driving both channels into 50 ohm loads at the 20v p-p setting at 20MHz reveals a +1.8 and -1.9 volt dc offset range before any hint of clipping starts to appear on the peaks of the sine wave, a vast improvement over the original setup which had zero dc offset tolerance under the same limiting conditions.

 Also worth noting is the 1.2W reduction in energy consumption when each channel is driving a 50 ohm load at the 20v p-p setting with sine waves at 20MHz. Previously, I'd witness a power reading of 9.9 to 10 watts under these conditions whereas now it only tops out at 8.7 watts.The only way to top these consumption figures is to select the square waveform option which increases demand by another half watt.

 This final modification is in addition to the diode upgrade to get rid of the totally unsuited originals. The pair of back to back T220 devices visible in the second and in the background of the last picture are the 20A 45v PRV rated dual shotky low forward volt drop high speed rectifier diodes I used to replace the 12v rail diodes. The 5v rail diode in the foreground of the last image is a 3A Shotky rectifier diode upgrade on the original 1A rated "fast" diode it had been cursed with.

 The diode upgrades not only provide a voltage boost on the 12v rails (nearly an extra half volt) they also reduce the losses in the PSU board contributing to the overall reduction of 1.2W (about 12%) which might seem trivial but anything that reduces both thermal and electrical stress in such a compact piece of test gear is both a very useful and much welcomed side effect in this case.

HTH & HAND  :)

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: JBeale on April 09, 2019, 04:28:10 pm
I notice that www.feeltech.net (http://www.feeltech.net) has for the past few days at least provided the less than useful response:
Code: [Select]
HTTP Error 502
Bad gateway
76.115.100.230/6bedf6a
2019-04-10 00:26:25
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bugi on April 09, 2019, 04:42:16 pm
I notice that www.feeltech.net (http://www.feeltech.net) has for the past few days at least provided the less than useful response:
Code: [Select]
HTTP Error 502
Bad gateway
76.115.100.230/6bedf6a
2019-04-10 00:26:25
Seems to work for me right now. At least it shows something I'd expect, instead of 502.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on April 09, 2019, 06:42:25 pm
http://en.feeltech.net/ (http://en.feeltech.net/) works (still 85% in Chinese  :palm:).

 Chers,
 DC1MC
Title: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: wasyoungonce on April 13, 2019, 12:29:59 pm
Quick stupid question.  Can the fy6600 fy6800 or dy5300 output dual encoder type pulses to simulate a dual channel encoder. 

Let’s say ttl pulses ch a leading b by 90degrees or b leading a.

I wanted to simulate an encoder that seperates the pulses by 90 degrees but I’d also need to alter pulse period and keep same phase split.

I know I could do the pulses but not sure about locking the phase split relationship

????



Sent using iPhone
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on April 13, 2019, 06:22:37 pm
Yes, it can. You set the wave to CMOS, phase to 90 or 270 degree then press SYNC. Now if you press CH1 > FREQ, you can adjust the frequency on both channels simultaneously and the phase will stay the same. Same procedure for DUTY.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: wasyoungonce on April 14, 2019, 12:40:37 am
Excellent thanks miti.... I’ll read all the thread to get a full picture but as said need to simulate encoder channels ....plus other uses.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on April 14, 2019, 03:03:12 pm
I performed a few audio tests on my 66' and 68' hundred.
I used a program called 'visual analyser' ,which does Scope FFT and spectrum , thd+noise etc. 'Room Eq Wizard' is another software that can do this ,it will even list the % points of the individual Harmonics 2,3,4,5,6th  , for this test I went with 'VA' for simplicity of setup ,and I felt thd+ noise was adequate for the purpose of the test.

What I noticed was , well what we'd always known , that certain spot frequencies along the way , 3.5khz being one, perform very  much better in terms of THD than other frequencies , it looked like a comb filter effect. as I went up or down the frequency range , the distortion rises and falls in a fairly predictable manner , across most of the middle audio frequencies it reads within spec of .5% ,but at fairly regular intervals along the way it drops to a very much lower number like .002% or even less. The effect of amplitude on distortion wasnt nearly as big a concern as I had thought it might be either ,as expected at very low output levels a higher contribution of noise pushes up the thd+n numbers , the usb sound card input tops out somewhere well down below full output of the gen ,harmonic spikes are visible the moment the sound interface is over driven .

Now supposing we want to make a very low distortion audio 'frequency stepped' test tone on the fy 6600 , by choosing the individual frequencies of the stepped waveform from the bands of sweet spots across the frequency range we could do very much better than .5%thd  of the spec . 
I should have plotted the frequencies  , its obviously a function of DSP clocking frequency ,there must be at least 50 points across the band 20hz -20khz , its easily visible on an FFT though , when you hit the sweet spot all forms of noise and distortion dramatically drop , as much as 20-30 db over worst case .

Hopefully someone  will be able to confirm my results , 





 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Cliff Matthews on April 14, 2019, 03:11:57 pm
..I used a program called 'visual analyser' ,which does Scope FFT and spectrum , thd+noise etc.
Thanks! Interesting software. http://www.sillanumsoft.org/news.htm (http://www.sillanumsoft.org/news.htm)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on April 15, 2019, 02:15:07 am
There were 3 signal sources,  The 6600, the 33622A and Leo's 100 ps impulse.  The DSO sinc(f) issue is *only* visible on the 100 ps signal when the DSO is sampling at 1/10th of the pulse duration.

I have one of Leo's two  channel GPSDOs which has been extremely satisfactory.  The single channel version is cheaper.

I bought a 6 output 10 MHz GPSDO from Roadrunner, but have not yet gotten around to testing it.

 I realise it's been over three weeks since you posted this but I was just reviewing the last page of this forum after checking out ebay for cheap GPSDOs and reading the other EEVBlog BG7TBL forum discussion so your remarks about Leo's GPSDO units rather caught my attention this time round.

 After what I'd read about the BG7TBL units and the fact that they seem to be based on an FLL rather than a PLL (accounting for the almost insignificant 0.15Hz frequency error in these units), I decided to take a fresh look at alternative "cost effective" GPSDOs and landed up on Leo's web site, scrutinising his GPSDO offerings which looked rather nice for the money.

 However, the big turn off for me is the use of a VCTCXO rather than a VCOCXO, so as nice as they looked for the money, they don't quite meet my expectations. They might stay locked to GPS time, unlike those BG7TBL units, but, again unlike the BG7TBL units, won't have the short term stability of a half decent VCOCXO based unit.

 I was only browsing on the off chance of finding a cheap bargain basement unit to tide me over the next fortnight before I get my chance to pick up a  VCOCXO or two at a radioham rally (along with a few other bits 'n' bobs needed for my GPSDO project). I'm seriously thinking of having a go at building that diy-gpsdo-with-arduino-and-1ns-resolution-tic designed by the late Lars Walenius who, rather sadly, passed away on the 28th Dec last year.

 <https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/>

 I'd already (rather speculatively) bought myself an Arduino Nano module when I bought the GPS module, both purchases inspired by Scully's youtube tutorial videos <https://www.youtube.com/watch?v=lbns-FvpzK4>.

 The Lars version will put the Arduino Nano to a less demeaning use than the one it was fated for in the Scullcom GPSDO project which was basically just a cheap 'n' cheerful frequency calibration standard offering no better performance than the bare NEO M8N module I'd bought.

 It's taken me several weeks of pissing around with the GPS module, a sig genny and a 'scope to realise that the heart of any decent GPSDO is its VCOCXO module. That comes first and foremost in the BOM. The rest of the BOM is just the after-market paraphernalia required to bolt whatever choice of GPS that happens to conveniently suit the task (virtually any of the more recent units possessed of a 1PPS output signal) and, optionally, provide "Das Blinken Lights und Switchen"(tm).

 Between my own experiences with TCXOs (the one I'm using in the Feeltech and the one in the u-blox M8N module) and from what I've read on the subject, I know that VCTCXOs aren't in general a good substitute for the VCOCXOs normally used in GPSDOs. That being said, I'm wondering whether you've had a chance to compare that Bodnar unit against any other GPSDOs, possibly that Roadrunner unit you hadn't gotten round to using as of  three weeks ago.

 I know that testing the performance of GPSDOs can be rather time consuming but I reckon it's something worth doing with that Bodnar unit even if it's merely to satisfy idle curiosity about the VCTCXO versus VCOCXO debate in their use as a GPS disciplined oscillator reference source for driving (to keep it on topic) a modified FY6600 for example.  :)

 I just did a quick search for reviews of these Bodnar units and discovered this interesting document file:-

<http://leobodnar.com/files/Informal%20Evaluation%20of%20a%20Leo%20Bodnar%20GPS%20Frequency%20Reference.pdf>

<https://tinyurl.com/y4fgs8oz>

 It gives a fair assessment these TCXO based units with no surprises. A couple of months back, I might have bought the single channel version. I guess my naivety which had led led me to believe I could maybe knock up a poor man's GPSDO version sans the expense of a VCOCXO for a fraction of the price must have put me off buying one.

 TBH, I was seriously considering ordering the £99.99 one just now since, in spite of the compromised phase noise performance, it's still a well made handy little test and calibration unit for very little money but sense prevailed after reading through that report. At the end of the day, it isn't quite up to the standard I'm hoping to ultimately achieve with my own DIY GPSDO project.

 Don't get me wrong, it's a vast improvement over what I'd been hoping to initially achieve but now that "I've seen the light"(tm), I don't want to take any prisoners in my quest to assemble a home brewed GPSDO of my very own manufacture. I've just got to sit tight for the next two weeks in the hope that I'll be able to do a face to face deal at the radioham rally on a used but good quality VCOCXO module or three (and likewise for the other bits needed to glue it all together).

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on April 17, 2019, 04:43:22 pm
OK, this tops it all!!!

I just got the May/June 2019 issue of QEX.  On the front page is an FY6600 which was converted into a WSPR transmitter by the author.  The article references this thread, so hopefully he'll see this and share some details of the project for readers who don't have access to QEX.

He did the TXCO, output amp and mains cord modifications.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: 2N3055 on April 17, 2019, 05:27:38 pm
OK, this tops it all!!!

I just got the May/June 2019 issue of QEX.  On the front page is an FY6600 which was converted into a WSPR transmitter by the author.  The article references this thread, so hopefully he'll see this and share some details of the project for readers who don't have access to QEX.

He did the TXCO, output amp and mains cord modifications.

That article is free sample on arrl.org

http://www.arrl.org/files/file/QEX_Next_Issue/May-June2019/Steber.pdf (http://www.arrl.org/files/file/QEX_Next_Issue/May-June2019/Steber.pdf)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on April 17, 2019, 07:29:32 pm
Very cool!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on April 19, 2019, 11:08:37 pm
After what I'd read about the BG7TBL units and the fact that they seem to be based on an FLL rather than a PLL (accounting for the almost insignificant 0.15Hz frequency error in these units), I decided to take a fresh look at alternative "cost effective" GPSDOs and landed up on Leo's web site, scrutinising his GPSDO offerings which looked rather nice for the money.

If you're looking for cost effective GPSDO take a look at this
https://www.eevblog.com/forum/projects/my-u-blox-lea-6t-based-gpsdo-(very-scruffy-initial-breadboard-stage)/msg929949/#lastPost (https://www.eevblog.com/forum/projects/my-u-blox-lea-6t-based-gpsdo-(very-scruffy-initial-breadboard-stage)/msg929949/#lastPost)

I tested it on a breadboard and it works really well.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on April 20, 2019, 01:12:41 am
I bought one of Leo's two output units.  It's *really* nice.  A bit of a hassle to program, but support is good and I'm very happy with it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on April 25, 2019, 12:07:52 am
After what I'd read about the BG7TBL units and the fact that they seem to be based on an FLL rather than a PLL (accounting for the almost insignificant 0.15Hz frequency error in these units), I decided to take a fresh look at alternative "cost effective" GPSDOs and landed up on Leo's web site, scrutinising his GPSDO offerings which looked rather nice for the money.

If you're looking for cost effective GPSDO take a look at this
https://www.eevblog.com/forum/projects/my-u-blox-lea-6t-based-gpsdo-(very-scruffy-initial-breadboard-stage)/msg929949/#lastPost (https://www.eevblog.com/forum/projects/my-u-blox-lea-6t-based-gpsdo-(very-scruffy-initial-breadboard-stage)/msg929949/#lastPost)

I tested it on a breadboard and it works really well.

 Hi Miti,

 I was just reprising the whole of this thread (Again!) and had reached page 60 where you and the others had been discussing the various firmware update possibilities almost a whole year ago (My! How the time flies by!) when I noticed that you and two other guests were watching this thread so jumped to the last page (74!) to catch up with the latest postings.

 I realised, after looking at the short thread you linked to, started by Gyro on his "My u-blox LEA-6T based fast locking GPSDO [experiment]", that I owed you a vote of thanks. The radioham rally is almost upon me (this coming Sunday the 28th at Blackpool) where I'm hoping to get some face time with actual electronics traders who sell this sort of stuff (OCXOs, ICs and pretty well anything that remotely relates to radio ham activities) and I've added a few more items mentioned by Gyro to my "Shopping List" which includes small 12 to 15 W triple rail +5, +/-12 or 15 volt psu boards (impossible to locate with google/ebay searches) amongst many other parts needed to upgrade my FY6600 and complete my GPSDO project.

 Apologies! I've just realised that I've written yet another 'marathon sentence' that can't be read out aloud without risking asphyxiation.  :-[ I guess the art of packing "everything but the kitchen sink" into one "small sentence" doesn't translate quite so well from that of packing two adults and three small children and luggage into a 1965 Volkswagen Beetle for a 200 mile cross country one week's holiday trip that I still have fond memories of thirty years on. :(

 Anyway, having refreshed my memory in regard of the perceived shortcomings of Feeltech's finest which we had all been obsessing over, I feel that the benefit of (my) hindsight might provide a useful perspective on this long drawn out saga of a thread.

 Putting aside the several pages of commentary needed just to to explain in a nut shell the global geo-politics that's lead us to this point in time where we all seem to be headed for world catastrophe, it's quite clear that Chinese traders using Ebay haven't got the first clue about marketing to the western consumerist societies whose governments will, at the drop of a hat, prosecute wars in 'far away lands' in the pursuit of 'natural resources' to keep their source of income (tax paying consumers) sufficiently satisfied to avoid outright civil unrest and so maintain the status quo of the whole fatally flawed system upon which they rely for a trouble free life of luxury.

 Sorry about mentioning "The Bleedin' Obvious" but I thought it best to remind ourselves of the underlying situation before slagging off our Chinese Suppliers of cheap and surprisingly good (in the main) test gear of which the FY6600 (and its successor, the FY6800) is a shining (fvsvo 'shining') example.

 The most serious complaint we can legitimately raise, is the obvious lack of 'Good Faith" in the Feeltech camp when it comes to customer relations (eg. the lack of interest in putting right the issue of faulty firmware that was 'bricking' the FY6600 units cursed with version 3.0 firmware).

 The rest of this product's shortcomings can be more sympathetically viewed as simply the inevitable consequence of cost cutting trade offs which should be taken almost for granted at the pricing levels involved. A crap product is better than no product at all at this sort of pricing level set to attract an otherwise ill served hobbyist market where such shortcomings can be worked around by a less demanding but more resourceful customer demographic. In this regard, Feeltech's targeting of their 'market' could hardly be bettered (putting aside the obvious shortcoming of customer relations in regard of the V3.0 firmware issue).

 The main obsession appears to have been that of the half mains live 'touch voltage' that exists with any such kit powered from class II smpsus relying upon the mandated EMC bodge of the Y class capacitor to hold conducted common mode switching noise pollution at bay.

 It turns out that the optimum solution to this problem (risk of ESD to a DUT) is simply to use a 3 wire mains cord with a 3 pole mains inlet socket to provide access to the PE to allow a low impedance (10KR) static drain connection to attenuate this half live touch voltage to half a volt or less whilst neatly avoiding the issue of earth loop induced interference at millivolt output levels (both millivolt DC and AC voltage offsets from induction and galvanic/thermocouple effects in the PE earth and mains supply wiring).

 The alternatives of using analogue supplies or mains frequency isolating transformers to eliminate such 'touch voltage' effects without the use of a PE connection are ultimately doomed since it's impossible to completely eliminate capacitive coupling which is responsible for the problem in the first place. The risk may have been reduced (a 1000pF's worth from a Y capacitor reduced to a matter of 50 to 100pF's worth with a small 10 to 20 VA mains transformer - possibly much less with a special isolation transformer, the cost of which being a reduction of efficiency from 95 to 98 percent down to around 70%) but, nevertheless, a risk still remains.

 Pursuing extremely low levels of capacitive coupling to mains voltage interference with special isolation transformers simply to avoid the use of a stiffer three core mains cable and a mains socket upgrade carries the penalty of extra heat dissipation within an already ill ventilated plastic case that's raising component temperatures perilously close to their upper limits for their life ratings (capacitors which may only be good for a few thousand hours at these temperatures versus several tens of thousands of hours by running just a mere 15 to 20 degrees cooler).

 This issue of operating temperatures within the box takes on even greater importance when, for the sake of frequency stability, it is common practice to leave it switched on 24/7 so the avoidance of a low efficiency PSU becomes an ever higher priority requirement.

 The existing smpsu board used by Feeltech turns out to be a much better optimised design than all of the similar three rail smpsu alternatives on offer via Ebay suppliers in that, unlike those offerings, the 12 volt rails have symmetric output capability (the Ebay offerings typically specify 1.5A on the positive rail whilst offering a mere 400mA or even less on the negative rail).

 I've searched and searched Ebay till my eyes bled but haven't (so far) managed to find any dual output (let alone three rail) smpsu boards in the 10 to 20 watt range which offer symmetric current ratings on the 12 or 15 volt rails. In view of the utter simplicity in achieving such symmetry, as demonstrated in the Feeltech design, I'm rather at a loss as to why this should be the case.

 The only shortcomings of the existing PSU board are the lack of screening and filtering and the insufficiency of voltage output on the "12 volt" rails[1]. I've so far managed to address the low 12 volt rail voltage issue by upgrading to proper high speed, low forward volt drop Shotky barrier rectifier diodes and adding a single turn winding to the transformer to buck the 5 volt winding to balance up the voltage distribution between the 5 and 12 volt rails (along with higher value smoothing caps - but only to a limit; too much capacitive loading causes the switching chip to go into an overload state).

 The next step is to add 100nF ceramics across the input caps and mount the board into its own ventilated metal case with room to add additional LPF filtering on the output rails (using large value series input inductors with large value output shunt capacitors to suppress the HF switching ripple noise without inducing an overload response from the switching chip).

 The ventilated metal case being a Faraday shield only requires an "earth connection" to the common ground rail and should avoid a low impedance connection to the PE - being a class II rated PSU, such a PE connection is  not a safety requirement so the risk of ground loop induced interference can remain at bay, courtesy of the 10K static drain connection which nicely serves to suppress the half mains live touch voltage.

 Bypassing this 10K drain resistor with a 100nF capacitor merely reintroduces the risk of earth loop induced HF interference and becomes somewhat of a folly in this case. Mention of which, when it comes to additional mains input filtering, we only need a series common mode inductor between the mains socket and the smpsu mains input live and neutral terminals. Live to neutral capacitors are ok but what we definitely don't require are any additional live and neutral to protective earth capacitive connections. Any such capacitors should have their grounding connection point left disconnected since they'll undo all the good work of the 10KR drain resistor in attenuating unwanted ground loop effects[2].

 Ideally, we should likewise screen the main board if we wish to reduce direct radiation of the higher frequency signals used in testing HF radio gear but this becomes a task of far greater difficulty than that of merely containing the switching hash within the confines of a PSU screening box so is best left alone unless you're the type to see such effort as a challenge to be overcome at any cost.  :) The benefit to cost ratio in filtering and screening the PSU will imo, be a good two orders of magnitude greater than trying to do likewise for the main board so is worth the modest effort involved.

 By all means, replace the existing PSU board with a ready made solution... if you can actually track one down, that is! (good luck with that search for unicorn droppings).

 Turning to the issue of the original frequency accuracy and stability (lack thereof) of the smd XO chip, most of the problem seems to stem from the fact that it was located within just 10mm of the three LDO regulators which were, in my case, running at close to 70 deg C raising the XO chip to 50 deg C according to my IR thermometer. Now that I've reduced the 5v rail from the original boost to 5.49v, in my original effort to get the 12v rails above the 12v mark, back down to 5.07v, those LDO chips are probably now running a degree or three cooler.

 It was no surprise to me when it was reported that just blowing over the XO chip caused a noticeable frequency shift. Indeed, it was this unconscionably high temperature which made me change my original plan to transplant the TCXO from the PCB it came supplied on (cheapest Ebay option for a 0.1ppm 50MHz TCXO) as a direct replacement to using the oscillator board as is and mount it at a jaunty angle over the 50mm 12v fan I had fitted into the base of the case and powered off the 5v rail in order to keep it in the 0.1ppm temperature zone and minimise power up warm up time.

 Prior to that upgrade, trying to compare DIP XO frequency traces against the FY6600's frequency had been a game of "Chase Wil 'o the Wisp" due to that execrable smd XO chip's lack of anything that could be described as 'stability' by even the greatest stretch of the imagination.

 Now, I am able to use it to compare the 8MHz output on the GPS module's PPS line, observing what I now understand to be the infamous "Saw Tooth" corrections being applied to the module's 48MHz TCXO generated clock pulses (20.8333ns jittering at anywhere from 10 per second to once every half minute or so).

 Without such an upgrade to the FY6600, I'd have not been able to observe the actual mechanism by which a typical GPS module disciplines its internal clock to keep its 1PPS output synchronised to GPS time. IOW, this was a modification that was more than well worth my investment in both time and the 16 quid I'd spent on the "clock power board".

 Another modification that's well worth the time and effort (unless you had no intention of generating MHz signals above the 5Vpp mark into high impedance loads[1]) is the replacement of the rather weedy THS3002i dual CFB opamp with a pair of THS3091/3095/3491 CFB opamp chips which will nicely eliminate the gross distortion when trying to produce sine wave outputs into 50 ohm loads at 20Vpp settings (10Vpp into 50 ohms) up to the 20MHz frequency limit before this limit is reduced to 5Vpp at frequencies beyond 20MHz (effectively disabling the use of the THS3002i or its replacements by bypassing it/them for signal levels at or below this 5Vpp limit).

 The only remaining modification that comes to mind that isn't simply a matter of tweaking some preset trimmers on the main board, is that of reworking the 85 ohm attenuator pad into a 50 ohm pad which gets switched into the output by a relay whenever sub 500mV levels are selected. Feeltech are completely aware of this "Skoolboy Howler" since they've compensated for its effect in the High impedance case in the firmware. It cannot, of course, compensate both the high and 50 ohm terminated impedance states since it can only be one or the other. In this case, it's the Hi-Z case since this is unlikely to be noticed by anyone using the generator for audio frequency work since they rarely work with 50 ohm transmission lines and largely deal with feeding signals into 10K or higher impedances.

==========================================================================================

[EDIT 2020-04-16]


 With the benefit of 12 month's worth of hindsight, Feeltech's bean counter knew exactly what that 85 ohm attenuator pad nonsense was all about (reducing manufacturing costs at any price).

 It's obvious now that the design had been based on the industry standard practice of adding a 20dB attenuator and compensating by bumping the signal voltage up by one order of magnitude as you carry on selecting lower output levels in order to hold the effect of quantisation noise at bay for sub 50mV signal levels.

 This was no 'Skoolboy Howler' with some clever firmware patch to compensate for a BoM error to get it to work in the Hi-Z loading case. It was simply an elimination of the more expensive E192 series resistors required to create a 20dB 50 ohm attenuator pad by replacing the 61.2 ohm shunt elements with 100 ohm cheapies and likewise, substituting the 249 ohm series resistor with another 510 ohm cheapie. The values had been selected solely to achieve precisely the same attenuation as the proper 20dB 50 ohm pad it had been designed to work with but only in the Hi-Z case.

 The solution eventually proved to be as simple as "Just fit a 20dB 50 ohm pad, dummy!" after it was discovered that the FY6900 had exactly the same 85 ohm pad and testing the output of the primary opamp driving this attenuator proved that  an order of magnitude step change was being applied at the 500/501mV threshold the attenuator was being switched into or out of the circuit with subsequent testing of my own FY6600 revealing exactly the same order of magnitude step change in voltage associated with the use of a 20dB attenuator just like every single signal/function generator on the market regardless of make.

 The following text (which I've struck through) can therefore safely be ignored as pure speculation.

The lowest impedances they might deal with are likely to be 300 or 600 ohms where the expected discrepancy between 50 ohm source and 300 or 600 ohm sinks will be very close to what they'll observe in this case with an 85 ohm source. The truth of the matter will only come to light if the audio 'engineer' bothers to make the necessary and basic computations to verify the readings.

 This annoying "Skoolboy Howler" with Feeltech's infamous 85 ohm attenuator (the FY6800 remains so afflicted despite the excellent opportunity that Feeltech wasted by not revising the BOM on this newer model's main board), is more likely to become swiftly apparent to those working at RF where the use of terminated transmission lines is more or less obligatory simply to avoid anomalous voltages where cable lengths are often a sizeable fraction of the wavelength of the frequencies involved.

 Indeed, when working with impedance matched circuits, a standard technique for checking whether or not we have a proper impedance match is to observe the expected 6dB drop when connecting to a matched impedance (in this case, 50 ohms). The last thing any RF engineer expects to be doing is to account for an impedance change from 50 to 85 ohms just because the "Amplitude" setting had been reduced to 500mV or lower. Diagnosing problems is difficult enough when the test gear is within specification. Having it change its characteristic impedance just because of a change in output level is an unwanted and unnecessary evil that should never have been there in the first place.

 I've had a go at fixing this annoyance but it turns out to be a lot more difficult to conjure up a 50 ohm impedance attenuator pad that matches the High impedance condition volt drop expected by the firmware bodge. I thought I'd gotten it properly sussed out but after tweaking the temporary trimpots I'd wired up to fine tune my calculated pass element value a lot more than I was expecting to, I'd landed up with a 45 ohm attenuator pad. Close but, as the saying goes, "No Cigar". It was, at the very least, an improvement but I'd like a much better improvement than that but, TBH, by the time I'd finished with all the calculations both pre and post the modification, I'd had more than my fill of attenuator calculations to last me for quite a while.

 I'm still recovering from all that brain bursting effort even now, several weeks on. I figure that if I take a long enough breather, I might succeed with my next attempt at figuring out a new BOM solution. Basically, I'm just working to my main strength which is the art of procrastination. If anyone else fancies having a go at generating a new BOM for these attenuator pads, please, be my guest.

 The key point to this is you have to aim for a 50 ohm attenuator pad which will match what the current pad gives under open circuit loading but only drop 6.02dB when driving a 50 ohm load instead of circa 8.6dB as it currently does. Somehow or other, I'd managed to screw up the calculations and I couldn't come up with consistent results each time I tried. It does look as though a 20dB 50 ohm attenuator pad had been the original design target but the firmware embedded correction to what I presume had been a BOM error means we can't fix it by simply dropping in a 20dB 50 ohm pad.  :(


 This last conclusion where I'd assumed that a firmware kludge had been required to compensate for a "Skoolboy Howler" turned out to be tragically wrong. Dropping in a 20dB 50 ohm pad turned out to be exactly the right solution as I could have determined if only I had thought to test my assumptions by verifying the voltage step change ratio with actual measurements. :palm:

[END_EDIT 2020-04-16]

==========================================================================================

 To summarise, the modifications I think would be considered worth doing by most contributors in this thread (if they haven't done most of them already) are as follows:-

 Upgrade the C8 mains connector to a C6 (allows a thinner cable to be used) or a C14 (tail wags dog effect) in order to connect the zero volt rail to the protective earth connection via a 10KR (or 1KR if 250 to 500mvac is still too much to stomach as an ESD risk) in order to kill off the half mains live voltage (50 to 90vac as measured with a typical DMM) on the BNC shields. Don't directly connect the PE to the zero volt rail - the PSU is still a class II device not requiring any such PE connection. We don't want to make the mistake that Feeltech did with the FY6800's earth connection by introducing an unnecessary grounding loop. This is a modification that everyone will benefit from regardless of their level of interest in frequencies beyond the audio frequency range.

 Install a cooling fan - a small 50x50mm square by 10mm deep 12v fan run off the 5v rail will be more than sufficient to shift the heat out of a box that's not been vented with convective cooling in mind (tilting it on its prop stand actually aggravates the overheating effect!).

 Replace the crappy commodity 50MHz smd XO chip with a half decent TCXO module, preferably, as others have done, by mounting it on a separate board remote from the original's hot spot on the main board. You could choose an OCXO if you're prepared to provide the additional 3 or 4 watts from an extra PSU board (if it's a 5v OCXO, you could utilise the innards of a cheap 2.1A USB wallwart for this task which will run even cooler once extracted from the confines of its unventilated wall plug shaped enclosure).

 If you're planning on an opamp upgrade, then either modify the existing PSU board or else replace it with something better (good luck in finding a suitable replacement though). Apropos of which, the asymmetric nature typical of the current ratings on the +/-12 or 15 volt rails on most of the Ebay offerings could prove a boon if you're planning on fitting a 12v OCXO.  :)

Upgrading the existing dual CFB opamp to a pair of the later spec THS 3091/3095/3491 opamps is a worthwhile modification unless your interests are essentially confined to low frequency audio work or you don't need "Amplitude" settings greater than 5Vpp.

That 85 ohm attenuator annoyance can, of course be worked around with an external 20dB attenuator but if you're regularly working with 50 ohm impedances, then replacing the resistors in that attenuator pad to convert it into a 50 ohm pad will provide a welcome benefit. Unfortunately, I can't offer much help there right now. My previous attempts only got me closer to the nominal 50 ohm than the original 85 ohm impedance match rather than close enough for me to tick it off my to do list.  :(

 Just convert that 85 ohm attenuator into a 20dB 50 ohm pad by using E192 series resistors (or combinations of E24 or E48 series that will give you the required 148 and 61.2 ohm resistance values with some selecting on test if required). The solution is that simple! I'd over-thought the problem but it turned out that the chief beancounter had told their designer to jump and the designer had simply asked "How high?"

 I think that just about covers everything with regard to upgrading this sow's ear into a rayon purse. If I've missed anything, just speak your piece on the matter. I've not mentioned the 4ns jitter on square waves simply because it's inherent to the DDS technology used here and in other far more expensive AWGs, only alleviated in the later yet even more expensive famous brand named test kit. In view of its very low price, I think it's a relatively minor 'defect' we can all (learn to) live with.

JBG

[NOTES]

[1] Unless you're planning on upgrading the THS3002i dual CFB opamp with a pair of THS3091/3095/3491 opamp chips to eliminate distortion of the sine wave output at 20Vpp settings into 50 ohm loads in the frequency range 5 to 20 MHz, there's little point in doing the 12 volt rail voltage boosting mods. Indeed, if you don't select "amplitude" settings above the 5Vpp mark, the CFB opamp chip(s) never even get switched into circuit by the relays. This just leaves you with the business of upgrading the IEC C8 mains inlet socket to a 3 pole socket (C6 or C14 type) to provide a PE termination point for the grounded end of the 10 or 1 K ohm 'drain' resistor to eliminate the ESD risk posed by the Y capacitor.

[2] A perfect common mode choke would be made using bifilar winding but, aside from the mains voltage stresses on the inter-turn winding insulation, the separation of the live and neutral windings which eliminates this risk of insulation breakdown is also utilised to provide leakage inductance which is put to good use to create an effective transverse LPF by the use of additional capacitors across the live and neutral to suppress HF noise ripple voltages riding on top of the mains waveform using the live/neutral pair as a transmission line to reach vulnerable devices and unbalanced parts of the house wiring (eg. lighting switch drops) from where they can re-radiate as interference to wireless devices.

 Most such ready made filters are designed for a LNE setup where a pair of Y caps are wired in series across the L&N X capacitor with the join intended to be connected to the PE, typically via a screening can connection. In this case, such Y capacitor earthing connections are redundant because they now become counterproductive to the need to keep mains half live touch leakage current to a minimum and avoid creating an unwanted earth loop at high frequencies.

 If anyone wants to improve the common mode choke filtering between the PSU board and the mains socket, all that's needed is just a common mode choke or three, similar to the one already on the PSU board (scrapped smpsu wallwarts and the like are a good source). cascaded with X caps across the L & N connections of each section.

 A shielded filtered mains socket where the Y caps are soldered to the PE connected shielding can still be used provided the earth tag is only used to connect to the 10KR drain resistor and not directly to the zero volt rail of the main board.

 Having said all that, the real priority on 'filtering' lies with those LPFs between the DC voltage rails and the main board connections. If you're short on space within the PSU screening box, it's this LP filtering on the DC rails that gets priority. If you've room for both, you can leave the additional common mode choke filtering modification on the mains input side for later once you've verified the effectiveness of the DC filtering mod.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on April 26, 2019, 10:55:44 pm
Voltages and power draw measurement figures for a modified FY6600 on 240v 50Hz mains supply

 As a result of my previous TL:DNR posting, it occurred to me that I didn't have a comprehensive set of test voltages since doing the last PSU modification so I popped the lid off the box (yet again!) and poked at the PSU connector header with my DMM test lead probes whilst twiddling with various settings. I got some interesting results which I think you might be interested in (at least they were interesting enough for me to open the main board circuit diagram pdf to look up the data on those EA2-5 miniature relays and check the THS3491 data sheet).

 For starters, I configured the sig generator for "Maximum Smoke" which simply means driving 50 ohm loads at 20MHz with a "20Vpp" square wave. The 5 volt rail remains at a rock steady 5.06 volts throughout every test and I'd synchronised CH2's wave type, frequency, amplitude, offset, duty and phase settings to CH1's settings so I only need to list the "12 volt rail" voltages which, in this case were -13.03 and +12.87 with a maximum power draw of 9.2W from the mains socket.

For a 20Vpp Sine, the figures were -13.15, +12.97 and 8.7W.

 I didn't waste time on the open circuit, Hi-Z case, preferring to concentrate on finding the least demanding loading state for the PSU which was for a frequency so low it might as well have been zero Hz, aka 10KHz (100 or 1000KHz producing the same results) and a zero voltage output level. Strangely, this isn't the least power consumptive state (although it offered higher "12v rail" voltages of -13.18 and +13.05) with a power consumption level of 5.6W.

 When I increased the amplitude to 0.6v the power consumption dropped to 5.3W as the attenuator relay was released. Curiously, the amplitude setting effects the standby consumption which for me is a minimum of 5W (actually, just a smidgen less on closer inspection) when placed into standby from any amplitude setting greater than 500mV or less than or equal to 5.00V.

 You might well think the relay clicks on switching into standby would be due to any operated relays being released. They may be being released, but only for a brief moment as their previous state is immediately restored as part of the sequence of going into standby mode. What this means is that if you wish to minimise the standby consumption, you need to make sure the amplitude settings are higher than 500mV and less than or equal to 5.00v before pressing the standby power button.

 Of course, the power saving is a rather petite 150mW per relay (300mW maximum) so is unlikely to motivate anyone to worry enough to bother themselves over the amplitude setting whenever they avail themselves of the standby function. However, this behaviour which has an effect on the 12 volt rail voltages, sparked my curiosity as to how much of a load they were presenting to the 5v rail to exhibit such a detectable change in the watt meter readings so I tracked down the data sheet for these relays and found out.

 It turns out that they have a coil resistance of 178 ohms (28mA 144mW loading on the 5 volt supply). Rather spookily, exactly matching the loadings presented by my add on 5 volted 12v cooling fan and that of the 0.1ppm 50MHz TCXO 'oscillator power board' (28mA each) I'd installed to replace the rather shite SMD XO chip that Feeltech's bean counters had cursed the main board with. What a concidence!  ;D

 Although the boost given to the 12v rails by the relay loads on the 5v rail is a bit of a waste when it involves the attenuator relays, it becomes a welcome side effect when the 12dB boost amplifier relays are involved. The 5V rail only has to power a maximum of two relays at any one time since, on a per channel basis, it is an 'either one or the other' or 'neither' usage case, never both at once.

 Discovering the most extreme voltage variation limits of the 12V rails led me to conclude that the maximum values were -13.24 and +13.08 volts for my own particular configuration which event arises out of setting the amplitude to zero volts.

[EDIT] Discovered a slightly higher set of voltages at the 5.1v amplitude setting, -13.27 and +13.10 volts. Presumably due to the absence of any attenuator loading on the THS3491 opamp outputs when the generator's outputs are not connected to anything.

 That represents a peak to peak variation of just 240mV on each rail which is a mere 1.8% on a nominal 13 volt (or a +/-0.9% on a 13.1v mean voltage). That represents a far better voltage regulation than you typically see on the +12v rail with ATX PSUs!

 We might complain about the crapiness of Feeltech's "Special" PSU board but, after undoing the penny pinching effects of their bean counters, it turns out to be an excellent match to its task (pity they didn't get the secondary windings turns ratio better optimised between the 5 and 12 volt windings though - fortunately, quite amenable to a simple single turn buck winding fix on the 5v output).

 Since no one, afaicr, has reported test results after replacing the PSU board with either a shielded high quality low noise smpsu or an analogue PSU to demonstrate the benefit of reduced ripple and noise on the generator's outputs, it's only a guess as to whether installing the original, now improved, PSU board into its own ventilated shielding box with additional LPFs on its outputs will be worth this additional effort. All we can be certain of is that it won't make the situation any worse (provided the job isn't cocked up by well intentioned but misguided improvement attempts such as using a 100nF capacitor to link the zero volt rail to the PE in order to quell the half live mains touch voltage).

 With regard to the minimum voltage requirement on the 12V rails, I took a closer look at the THS3491 data sheet and located the "Headroom" voltage figures. These are listed as 1.2v minimum, 1.5v typical and 1.7v maximum which implies that a +/-12 volt rail will provide a margin somewhere between 800 and 300mV on a 20Vpp output level. In view of the fact that I was able to apply offsets of circa +/- 1.8 volts with a nominal +/-13v supply, it looks like the 1.2v headroom figure  applies in my case.

 I suspect the DC offset adjustment is more likely to be used to zero any offset drift rather than apply a desired DC offset. For anyone needing to actually apply a deliberate DC offset on a 20Vpp signal, it's highly likely they'll be looking for volts rather milivolts of offset. In this case, the simple answer is to invest in a set of cheap alkaline cells and just put it/them in series with the BNC ground return connection (the 10KR drain resistor won't mind unless you're looking to apply significantly more than a 50v dc offset voltage).

 Basically, what I'm saying is that a +/-12 volt supply should suffice to drive a pair of THS3091/3095/3491 opamp chips just as long as it can supply a minimum of 250mA to the opamp rails (worst case scenario 20Vpp square wave outputs plus allowance for the OPA686 opamps which are powered via 5v LDOs fed from the 12v rails).

 Incidentally, that modest voltage imbalance on the 12v rails looks to be a simple mismatch between the transformer windings rather than due to additional loading of the +12v rail as I'd originally supposed. I've scrutinised the main board circuit diagram extremely carefully now and I can't see any additional loading on the +12v rail to account for this minor voltage imbalance.

 I took great care in matching the pair of TO220 dual 20A 45v PRV Schotky rectifier diodes I used, so I'm forced to conclude that there must be some imbalance between the two 12v windings, possibly aggravated by some residual diode forward volt drop mismatch. I rather doubt the two 12v windings were bifilar wound in this case due to the high inter-turn voltage stresses this would impose. They'd have been wound in two separate layers which is likely what accounts for most, if not all, of this modest voltage imbalance even when wound to exactly the same turns count. The mismatch is a fairly consistent 160mV which represents an error of just 1.23%.

 This little PSU board, like everything else in the box, is merely the victim of rampant bean counteritis (and a minor miscalculation of the secondary turns ratio). Feeltech were stuck between a rock and a hard place as far as the provision of DC power was concerned. An overspecified off the shelf unit would have generated excess heat which, in this case of abysmal cooling provision along with overclocked DAC chips, would not have contributed to its reliability in spite of the extra expense involved. It seems (at least after applying some basic anti-bean counteritis remedial repairs), that they found the perfect pebble to wedge between said rock and the hard place - a 'little gem' one might be tempted to say.  :)

 I'm going to measure up the space in my generator for candidate screening boxes to add to my shopping list. If I can't find any suitable ready made three rail smpsus at this Sunday's radioham rally, then by God, I'll get my hands on any suitably sized unit at the cheapest price possible just for an enclosure in which to transplant the Feeltech PSU board and chuck the useless innards onto the scrap pile. There's more than one way to skin a cat!  >:D

 This will probably be one job that'll be left on the back burner to stew for a while but at least any delay won't be for a lack of materials.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Grillbaer on April 27, 2019, 12:57:41 pm
Hi there,

Does anybody know how to get a sweep start trigger signal from the FY6800? The "sync out" connector on the backside only outputs a square wave with the current signal frequency, not a sweep start signal.

I did not find anything about it in the manual.

Regards
Holger
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fisafisa on April 30, 2019, 06:36:26 pm
Hi
What is the state of the bluepill sofware for Fy6600?

I was thinking to make a version for a STM32 discovery board.
Any chance to get hold of the source code?

Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on April 30, 2019, 06:49:12 pm
Hi
What is the state of the bluepill sofware for Fy6600?

I was thinking to make a version for a STM32 discovery board.
Any chance to get hold of the source code?

Thanks

Sadly freemen67 suddenly disappeared in the middle of a conversation and never posted or even accessed the forum since then, I really fear for the worst  :(.

 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fisafisa on April 30, 2019, 08:50:04 pm
We all have bad periods in our life.
Hope he is fine.

Filippo
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on May 19, 2019, 03:50:05 pm
 Well, it's been three weeks since that radio ham rally event in Blackpool that I mentioned in my last marathon posting about the voltage tests on my PS board modifications. I'm afraid to report that it failed to live up to my hopes regarding my desire to accumulate OCXOs and the other bits 'n' bobs I was hoping to acquire in face to face deals with the various traders who attend such events.

 It wasn't a complete wash out since I did manage to get my hands on a 13MHz CQE branded OCXO for just 4 quid that I'd spotted amongst a rather random collection of stuff laid out on one of the trader's tables. It wasn't the desired 10MHz but, for a mere 4 quid, I was confident I'd be able to use it as a 13MHz sourced 10MHz clock supply (it was an OCXO - the only OCXO I'd managed to spot for sale- and was only 4 quid!  :) ).

 Typically, whenever I enquired about OCXOs (and other items) that any trader looked like they might normally hold stock of, yet unconscionably failed to have on display, the answer was often, "Yes, I have them back at the shop but I didn't bother to bring any due to limited space in the van." or similar such lame excuse.

 I do appreciate the limited carrying capacity of their transport (and the strain on their backs in carting such stock from the van to the table(s) and then back again) but, for an event like this, especially these days, I'd have thought such items as high precision frequency components like OCXOs and RRIO opamps and PLL and divider chips and so on would have been high priority stock items on such outings.

 I can only presume that this is a sad reflection of the state of the hobby now being one of cheque book solutions to the advancement in building up the contents of a modern day radio shack rather than via technical expertise in home brewing or DIY modification of existing commercial amateur radio kit as was once the case several decades past.  :(

 Anyway, all that sadness aside, I did manage to grab hold of a pitifully few other bits 'n' bobs before having to admit defeat and call it a day. Needless to say, I failed to find even a suitable PSU enclosure to re-home the FY6600's PS board into with most of my purchases being more along the lines of speculative "might prove useful" items such as a couple of 10MHz crystals which did prove surprisingly useful in creating a crude filter to clean up the PPS 10MHz output from my u-blox M8N based GPS module I'd bought a few months earlier.

 That 13MHz OCXO that I'd managed to snag so cheaply didn't have any information regarding its pin out or any hint of whether it was a 5 or 12 volt part (the trader professed a total ignorance as to any such information - probably why he was happy to accept my offer of just 4 quid for its purchase). The best I could do in my on line searches for any sort of a data sheet was a single page image of a 13MHz 12 volt Vectron clone. I got the pin out details ok but I had my doubts as to whether my CQE version was, likewise, a 12 volt part. Discretion proved the best part of valour in my subsequent voltage probing tests from which I was eventually able to conclude that, rather unusually, it was a 5 volt rather than the more common 12 volt part.

 I lashed up a breadboarded circuit to generate a 10MHz signal via a doubler to feed a divide by 13 with 26 MHz which then fed the resulting 2MHz into a second clock multiplier chip to generate the required 10MHz (the 3N502's minimum input clock frequency being 2MHz, hence the multiply by 2, divide by 13, with a multiply by 5 sequence to convert 13MHz into a perfect 10MHz square wave signal).

 Since this was all powered from a single 5 volt rail, I was tempted to use this as a replacement to my original TCXO upgrade but although the peak current demand by the OCXO alone of 280mA (reducing to around the 170mA mark once up to temperature) looked likely to be just within the limits of the FY6600's 5v PSU rail, I rather thought the additional 70 to 90mA from the multiplier, divider, multiplier chips would break this particular camel's back.

 Further searches for a more specific data sheet for my 5 volt 13MHz CQE OCXO eventually disclosed a cheap source of 10MHz CQE clones at just £4.99 each from the following supplier:

<https://www.ebay.co.uk/itm/CQE-CRYSTAL-OSCILLATOR-10MHz-REDUCED-TO-CLEAR/253081992039?hash=item3aecdcbb67:g:x1gAAOSw~qNZh2rl>

<https://tinyurl.com/y6pl2xvk>

 I initially bought three of them just over a week ago before committing to another four to provide myself with a "Lifetime's Supply" at a bargain basement price. I hadn't wanted to disperse the news of my bargain of the century find for fear of creating a stock depleting demand on the supply. Having now secured my supply, I'm only too happy to now spread the good news as a "Public Service Announcement" to all and sundry here.  :)

 Be aware though, the stock is slightly mis-described as "unused NOS" when in fact on close inspection (of the last four examples in my case) they're obviously used stock - two of them clearly had remnants of a through plated hole clinging onto a pin or two. All seven have proved to be in excellent working condition and showed no sign of the more usual cosmetics typical of some Chinese recovered offerings which often hint that they'd been dislodged from their PCBs with a hammer before being slung into a skip.

 Quite frankly, why the trader in this case felt it worth the risk of damaging his credibility by claiming "Unused NOS" in the description on an item he could easily have sold for twice the asking price even when correctly described as "Used stock", is a mystery to me. Force of habit, maybe? Anyhow, they seem to be well worth taking a chance on as a dirt cheap bargain basement 10MHz 12v OCXO clone of the Vectron units described in that photocopied data sheet page I posted in my u-blox M8N GPS module thread. The only discrepancy being the 4Vpp ac coupled sine wave output versus the 4Vpp squarewave output described in the Vectron data sheet.

 In spite of the complication of adding an extra 12v 300mA smpsu board (recovered from a small wallwart), I decided to utilise one of these 10MHz OCXOs to upgrade my FY6600 instead of the original 13MHz 5 volt only unit. The extra power demand by the 10MHz OCXO and its smpsu once at temperature is just a mere 1.3W which additional thermal loading is no longer an issue once the signal generator has been blessed with a small cooling fan as it has been for the past 5 months with my own generator (for anyone contemplating modifications to their FY6600/6800s, a cooling fan must take the highest priority - I used a 50mm square by 10mm deep 12v fan powered off the 5v rail in my case, very quiet yet so very effective at dispersing the heat build up).

 Going the "12v OCXO plus additional 12v smpsu add-on" route proves a very effective way to apply such an upgrade. Unlike Arthur Dent, I chose to connect the little 12v 300mA smpsu board directly to the mains inlet socket connections so I could keep the OCXO powered up whilst plugged into a mains supply even when the whole generator is switched off by its back panel on/off switch rather than burn the additional 5 watts of standby power it consumes when placed into standby mode on the front panel button.

 Also, unlike Arthur's use of a change over switch arrangement with the external 10MHz reference input socket he'd fitted to his unit, I plan on using the "injection locking" technique to synchronise the internal 10MHz OCXO to an external GPSDO 10MHz reference sans the complication of a change-over switch and the risk of disruptive glitches which could confuse the FPGA logic into a locked up state.

 The only problem with this 'neat idea'(tm) despite my on line researches, being that I need to experimentally figure out an injection locking circuit to achieve this goal. It's a well document technique (often discussed in the context of avoiding unwanted injection locking of XOs of any type to external interference from close in frequency clock sources - so, "How hard can it be?").

 Unfortunately,  I haven't been able to find any example circuits with real world OCXOs so I'm on my own with regard to solving this particular mystery. I started a new thread a couple of days ago entitled:- " Injection locking the 10Mhz OCXO to external reference (upgrading a FY6600)" but so far, haven't had any 'takers' despite the attached images having been viewed 14 and 13 times so far. Don't worry, I do plan on eventually presenting a report on this new tangential approach to adding an external 10MHz reference to the FY6600/6800 AWGs we all seem to have a love/hate relationship with. I don't know how long it will take to develop a working solution so don't wait with bated breath on this.

 In the meantime (in the tradition of my recent posts into other threads), here are a couple of attached photos for those who may not have seen them already. The first shows my collection of OCXOs, sans the one fitted into the FY6600, and the second shows the effect of my crude two crystal and 4K7R 'T' 10MHz filtering of the GPS's PPS signal on the 'scope traces when comparing the 10MHz output from the signal generator.

 There's, hopefully, just enough resolution to reveal sufficient detail in what's going on. The picture is a fair representation of the reduction of the non-integer division induced jitter of a 48MHz clock down to a 10MHz sine wave although it can't show its mitigation of the sawtooth jitter to something less jittery and more wavery in character which makes attempts at calibrating a 10MHz OCXO to within 100ppt a little less fraught.

 Unfortunately, such filtering is no substitute for a disciplined OCXO since the filtered raw PPS signal still contains the +/- 10 to 12ns variations reflected in the Deviation Map window in the u-centre app which typically shows excursions of 3 to 4 metres from a median position (which itself wanders around). It's this effect which makes the matter of getting the OCXO calibrated to better than 50ppt a matter of pure dumb luck. Clearly, there's no substitute for a GPSDO when it comes to sub ppb precision in calibrating OCXOs. Anyway, enjoy the pictures!  :)

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Jacon on June 08, 2019, 07:55:36 am
Seems to be new, slightly updated version (new case with back cooler):

https://www.banggood.com/FY6900-Dual-Channel-DDS-Function-Arbitrary-Waveform-Signal-Generator-Pulse-Signal-Source-Frequency-Counter-Fully-Numerical-Control-20MHZ30MHZ50MHZ60MHZ-p-1495502.html?akmClientCountry=PL&utm_design=41&utm_source=emarsys&utm_medium=Mail_weekend59_value&utm_campaign=newsletteremarsys&utm_content=leander&sc_src=email_3710845&sc_eh=3bf0b16dc5eaba9b1&sc_llid=242038&sc_lid=150870100&sc_uid=F2mev8eN8t&ID=53053147184&cur_warehouse=CN (https://www.banggood.com/FY6900-Dual-Channel-DDS-Function-Arbitrary-Waveform-Signal-Generator-Pulse-Signal-Source-Frequency-Counter-Fully-Numerical-Control-20MHZ30MHZ50MHZ60MHZ-p-1495502.html?akmClientCountry=PL&utm_design=41&utm_source=emarsys&utm_medium=Mail_weekend59_value&utm_campaign=newsletteremarsys&utm_content=leander&sc_src=email_3710845&sc_eh=3bf0b16dc5eaba9b1&sc_llid=242038&sc_lid=150870100&sc_uid=F2mev8eN8t&ID=53053147184&cur_warehouse=CN)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on June 08, 2019, 05:21:41 pm
Interesting mimic of the old Rigol case design. It looks like the "bumpers" are just part of the plastic enclosure.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: wasyoungonce on June 09, 2019, 05:03:57 am
Wonder what the DIL socket on the back is?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on June 09, 2019, 05:17:14 am
Wonder what the DIL socket on the back is?

The 6600 has a TTL port so 99.99% sure it will be the same.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: wasyoungonce on June 09, 2019, 05:24:56 am
Thanks tried to get manual but it’s not uploaded yet
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on June 09, 2019, 06:51:02 am
Yeah, looked like a TTL port in the Banggood pic, though it's pretty hard to read the raised white lettering on the white back panel. I guess ink is expensive. ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Jacon on June 09, 2019, 07:41:35 am
Thanks tried to get manual but it’s not uploaded yet
This link:
http://myosuploads3.banggood.com/products/20190606/20190606070659FY6900SeriesUsersManualV1.0.doc (http://myosuploads3.banggood.com/products/20190606/20190606070659FY6900SeriesUsersManualV1.0.doc)
worked perfectly for me, yesterday & today.

It's a MS Word docu, titled:

FY6900 Series Fully Numerical Control
Dual Channel Function/Arbitrary Waveform Generator
User’s Manual
Rev1.0     May,2019
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: wasyoungonce on June 09, 2019, 07:48:05 am
Ahhh ok thanks tried to open it on iPhone. Wot an idiot! :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on June 09, 2019, 11:07:18 am
Oooohh, look at the big fat 3-pole power connector on the back  :-DD, some lessons were learned  :-+ !!! But where is the software ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on June 09, 2019, 11:15:14 am
You are assuming the big fat Earth pin is connected inside the box  :-DD  :horse:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Jacon on June 09, 2019, 11:30:57 am
.... But where is the software ?
When the item will be available, I assume.

Today they are in pre-order state(21 pcs reserved already), which should be processed in ten days...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on June 09, 2019, 01:43:35 pm
Any difference to FY6800 already known?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on June 09, 2019, 07:19:12 pm
'Rigol' sprung to mind when I saw the 6900 too.

Maybe we will finally see a more usable version of the software from  FT soon ,

Just looking at the new manual now ,not sure if theres much difference , but hard to know for sure .
Maybe it has an improved clock ,output op amps, better supply ,and more accuracy across different output voltage ranges.

I see a few posts around in here relating to developing a software for these series of machines , basically external control ,
Id quite like a way of generating a series of audio tones for testing in conjunction with 'REW FFT' software to look at %THD .
I was able to get reliable sine waves at certain frequencies down to a THD of around 0.003% , less favourable frequencies show upto around the specified 0.5% of distortion .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Cliff Matthews on June 10, 2019, 12:54:21 am
For those thinking a PDF might have been a better idea..  :-/O
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 10, 2019, 02:35:09 pm
The only differences I see are the increased max Vp-p of 24V and the elimination of the 100uV step in the amplitude setting.  I guess we'll wait for a teardown to see what they've done for the power supply this time--but I'm not expecting much!  Meanwhile, the prices of the FY6600-60MHz have hit $40 on eBay, so if you like the idea of multiple synced units, now is the time to pick some up.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on June 10, 2019, 02:53:15 pm
You are assuming the big fat Earth pin is connected inside the box  :-DD  :horse:

 They've most likely repeated the mistake they made with the FY6800 and created a hard connection to the BNC grounds.  If they're still monitoring this thread, then they may well have used a link to the PE via a 1KR to 10KR "drain resistor" to squash the half live touch voltage down from 90 to 110vac  to 50 to 500mV 50Hz on a 240v supply without introducing the evil effect of an unwanted mains routed ground loop, a feature which hadn't cursed the earlier FY6600 (but at some risk of ESD damage to any devices under test).

 It will be interesting to see whether they fixed their skoolboy howler with the earthing of the FY6800 where they not only created an earth loop issue but had also, to add insult to injury, hijacked one of the two ground returns in the PSU to main board ribbon cable connector on account it was just the right length to reach the PE tag on the mains socket.

 Assuming the PSU board is still the same class II double insulated job used in the previous 6600 and 6800 versions it also won't requre a hard protective earth anyway. Providing a hard protective earth connection in the 6800 did more harm than good. One can only hope they've learn't their lesson by now. Has anyone managed to get hold of an FY6900 to check this out yet?

JBG

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GerryR on June 10, 2019, 02:59:27 pm
Hello, new here to this forum.  I had just purchased an FY6800-60M and ended up returning it.  The DC offset was over 35mV when set to 0.  There was a lot of jitter in frequencies above 20 MHz or so.  Amplitudes were way off into a 50 ohm load; there was considerable distortion in the output into a 10 k load.  Square waves started to look more and more like sine waves as frequencies got past 15 MHz.  Etc. Etc. Etc.   I haven't read all the posts in this thread yet, so I don't know if any of these problems have been experienced by others, but I am curious to know what others have found in actual use, i.e. tied to a real circuit and not just an o'scope.  Any input will be appreciated.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: StillTrying on June 10, 2019, 03:43:07 pm
Seems to be new, slightly updated version (new case with back cooler):

00'010.000'000'000KHz

It looks like the 10kHz is very accurate, +/- 0.1ppb. :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Cliff Matthews on June 10, 2019, 03:49:15 pm
You are assuming the big fat Earth pin is connected inside the box  :-DD  :horse:
Has anyone managed to get hold of an FY6900 to check this out yet?
AFAIK, they're still only pre-booking orders.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 10, 2019, 04:09:38 pm
Hello, new here to this forum.  I had just purchased an FY6800-60M and ended up returning it.  The DC offset was over 35mV when set to 0.  There was a lot of jitter in frequencies above 20 MHz or so.  Amplitudes were way off into a 50 ohm load; there was considerable distortion in the output into a 10 k load.  Square waves started to look more and more like sine waves as frequencies got past 15 MHz.  Etc. Etc. Etc.   I haven't read all the posts in this thread yet, so I don't know if any of these problems have been experienced by others, but I am curious to know what others have found in actual use, i.e. tied to a real circuit and not just an o'scope.  Any input will be appreciated.

I think your issues are a combination of mediocre quality and unreasonable expectations on your part!  I don't know about the DC offset thing, my FY6600 is about 500uV offset so 35mV seems like a lot. The amplitude into 50 ohms will be lower than the front panel setting by about 1/2.  I can't address the HF jitter, mine is the 15MHz version.  The device has an output bandwidth of about 75MHz and at 250MSa/s, 100MHz would be the absolute ceiling anyway--therefore a 15MHz sine wave is only going to have the 3rd and 5th harmonics and that will look pretty rounded.  I realize that the settings allow you to select "square wave" up to 25MHz, but realistically 10MHz is about all these will put out that even resembles a square.  This is not a defect, simply a characteristic of a device with bandwidth limitations.

Yes, we've all had these issues and more.  However, I doubt you can find a better product at this price point.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GerryR on June 10, 2019, 05:45:25 pm
bdunham7, thanks for your input.  I'm coming from a background where I have been using very high quality equipment, HP, Fluke Keithley, etc. so having to do a lot of fiddling to use an instrument is rather frustrating for me.  I don't think I was expecting too much after reading the specs of the instrument, but when you go back to the specs, you see that they left out some important info, like the output load for the specs given.  There is no "jitter" (edge, period) spec at all.  My fault for not looking a little deeper before purchasing.  I do agree that it is a lot of generator for the money, if you don't mind the fiddling, and from what I've seen, they would be better off just selling them as 20 MHz function generators with "some useful outputs to 60 MHz.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on June 10, 2019, 07:11:22 pm
Thanks tried to get manual but it’s not uploaded yet
This link:
http://myosuploads3.banggood.com/products/20190606/20190606070659FY6900SeriesUsersManualV1.0.doc (http://myosuploads3.banggood.com/products/20190606/20190606070659FY6900SeriesUsersManualV1.0.doc)
worked perfectly for me, yesterday & today.

It's a MS Word docu, titled:

FY6900 Series Fully Numerical Control
Dual Channel Function/Arbitrary Waveform Generator
User’s Manual
Rev1.0     May,2019


 Thanks for posting the link. I've just downloaded and added it to my FY6600 folder for reference and having read through it I'm not particularly impressed. That increase to a 24Vpp only covers the frequency range DC to 5MHz. It would seem to be a "One Upmanship" exercise against the big players who are quite happy to regard the 20Vpp limit as the accepted "Industry Standard" (if you need more voltage amplitude, just add a linear amp).

 However, I did notice a downgrade of the 20Vpp limit over the range of 0 to 20MHz that applied with the FY6600 (and the FY6800 istr) to just 10Vpp from 10 to 20MHz. The FY6900 now adds the range 5 to 10MHz where the 24Vpp is reduced to 20Vpp before reducing the pp limit to 10V from 10 to 20MHz. It's quite obvious that this is their way to eliminate the gross distortion of their vast stock of THS3002i ICs they're still trying to use up.  >:( Since these limits are burnt into their proprietary firmware, this means you're going to see even less benefit out of an opamp upgrade to a pair of THS 3001/3095/3491s than was the case with the FY6600 and FY6800 models.  >:(

 I also noticed in their specifications a claim of less than 5 watts consumption which, imho, is an outright lie. I rather doubt they've managed to reduce the power consumption from the more typical 7 or 8 watts with the silicon upgrade required to achieve this reduction. Although a much improved smpsu board might gain some reduction, it's hard to see how they could trim off two watts worth on a 10W rated smpsu with the typical 80% efficiency rating for full load without raising the efficiency to 99%!  ::) This all seems extremely unlikely when you consider that their implementation of the power saving standby mode still consumes some 5 to 6 watts (a saving, afaicr, of only 1 watt or so at best).

 TBH, I think the FY6800 is the best OOTB product between the 6600 and this 6900 abomination. If they were to open source the firmware (unlikely in the extreme imo) or a keen enthusiast writes a replacement firmware (also unlikely but a more realistic scenario), this still leaves it lagging behind the performance of a fully modified FY6600/6800 even after it too has been fully modified.

 If I ever fancied getting my hands on another Chinese Cheepy, I'd choose the FY6800 since it's essentially an FY6600 with better front panel controls and the bulk of the earthed mains socket upgrade already completed (just needs some remedial work with a 10KR 'static drain' resistor and the damage to the ribbon cable making good).

 To my mind, after reading through the manual, this new FY6900 just looks like a downgraded version of its predecessors.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on June 10, 2019, 07:18:47 pm
You are assuming the big fat Earth pin is connected inside the box  :-DD  :horse:
Has anyone managed to get hold of an FY6900 to check this out yet?
AFAIK, they're still only pre-booking orders.

 I thought this was the case but I wasn't sure so I posed the question anyway.  :-\  :)

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on June 10, 2019, 08:15:20 pm
Hello, new here to this forum.  I had just purchased an FY6800-60M and ended up returning it.  The DC offset was over 35mV when set to 0.  There was a lot of jitter in frequencies above 20 MHz or so.  Amplitudes were way off into a 50 ohm load; there was considerable distortion in the output into a 10 k load.  Square waves started to look more and more like sine waves as frequencies got past 15 MHz.  Etc. Etc. Etc.   I haven't read all the posts in this thread yet, so I don't know if any of these problems have been experienced by others, but I am curious to know what others have found in actual use, i.e. tied to a real circuit and not just an o'scope.  Any input will be appreciated.

 Others have already mentioned the jitter and rounded square waves issues so I'll only address the issue of "DC offset error". I've put this in quotes because there's every chance that Feeltech introduced the problem when they upgraded the mains socket to a 3 pole earthed one to address the howls of rage over the half mains live voltage leakage with the FY6600 inevitable with any class II smpsu, courtesy of the 1nF EMC bodge capacitor mandated by EEC regulations, and made the skoolboy howler of hard linking the ground rail to the protective earth instead of using it to suppress the 100 or so volts of 'touch voltage' when powered off a UK/European 240/220 volt supply.

 If they'd inserted a 1K to 10K "drain" resistor between chassis ground and the protective earth tag on the mains socket to load down the touch voltage to either 50mV (1KR) or 500mV (10KR) with such a 'static drain resistor', this would have neatly  attenuated such external galvanic and/or thermo-couple generated DC offset voltages via the unfortunate effect of the mains earthing ground loop circuit whilst attenuating such unwanted effects by some 60 or 80dB, allowing you to actually see the millivolt or so of DC offset produced by the FY6800 itself.

 It's a pity you didn't discover this thread before going to the trouble of shipping your FY6800 back to the vendor. You may have saved yourself the trouble as a previous contributor did some months back when he followed our advice to test with the safety earth disconnected and discovered the true source of his high "DC voltage offset" problem. :)

[Edit]  Found the relevant post here:

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2202948/#msg2202948 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2202948/#msg2202948)

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GerryR on June 11, 2019, 11:19:48 am
Thank you for finding that; a very interesting read.  With all the free engineering that has been done here for FeelTech, maybe the YF6900 will not have these same issues!  :-//
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on June 11, 2019, 02:42:38 pm
Thank you for finding that; a very interesting read.  With all the free engineering that has been done here for FeelTech, maybe the YF6900 will not have these same issues!  :-//

 It's just possible but looking at the way they implemented the C14 switched socket upgrade on the FY6800, I rather doubt it. In view of my observations on the changes to the Pk - Pk voltage limits shown in the 6900's manual, I'd rather take my chances with a 6800 where I know I won't be swindled out of a 20Vpp capability that goes up to 20MHz rather than with a 6900 model which may or may not suffer from the same (very fixable) ground loop issue but be swindled on the Pk -Pk capabilities in the 10 to 20MHz range (extremely unfixable).

 The rather questionable (have they upgraded the PSU board to one with +/-15v voltage rails?) 24Vpp rating (who would benefit from that?) in the DC to 5MHz range is just a marketing exercise imho to distract their customers from the more serious limitations they've now imposed to disguise the shortcomings of their over-stock of the very shite THS3002i dual opamps they're seemingly determined to use up come Hell or High Water.

 TBH, that downgrade on Pk to Pk voltage capability is such a detriment that even the original FY6600 would be a much better bet as a "Fixer Upper". There, at least, all the shortcomings are fixable. When the 20Vpp frequency range goes up to 20MHz, an opamp upgrade is well worth the effort but when it falls woefully short at just 10MHz, there's very little point in attempting such a marginal improvement. As I said, it looks like they've elected to downgrade the spec rather than upgrade the opamps. What's the betting that this new 6900 abomination will also sport an 85 ohm attenuator to serve the 0 to 500mV output range?  >:D

[EDIT]

 When it comes to the voltage output specifications published in the two FY6600 manuals and the single FY6800 manual, Feeltech (Feelelec) appear to have perpetrated a mistake since they all quote exactly the same levels and frequency limits (excluding the FY6900's 24Vpp upgrade in the 0 to 5MHz frequency range), despite the truth being a 20Vpp limit extending all the way from 0 to 20MHz for the sine and square wave forms at least.

 In this case, the manuals can't be relied on as authoritative guides to their performance and this might well (probably does) apply to the FY6900 as well. Obviously, we won't know until someone finally manages to acquire an FY6900 to test the actual frequency limits that apply to the 20Vpp setting and report their findings here or the other FY6900 thread that was started just two days ago.

 https://www.eevblog.com/forum/testgear/fy6800-vs-fy6900/msg2521413/#msg2521413 (https://www.eevblog.com/forum/testgear/fy6800-vs-fy6900/msg2521413/#msg2521413)

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on June 11, 2019, 04:53:03 pm
The only differences I see are the increased max Vp-p of 24V and the elimination of the 100uV step in the amplitude setting.  I guess we'll wait for a teardown to see what they've done for the power supply this time--but I'm not expecting much!  Meanwhile, the prices of the FY6600-60MHz have hit $40 on eBay, so if you like the idea of multiple synced units, now is the time to pick some up.

 If you ignore the rather questionable 24Vpp "upgrade" for the DC to 5MHz range, it basically amounts to a downgrade on the FY6600, let alone the FY6800 (which is basically just an FY6600 with a C14 switched socket and a revamped front panel with nicer to touch buttons - most likely still using the same SMD momentary action switches underneath though, but at least they can be replaced if any get worn out).

 The 24Vpp rating does suggest the possibility that the PSU board now sports +/-"15v" rails as opposed to the +/-"12 volt" (+/-11.7 volt actual) rails of the earlier models. However, that rather flies in the face of the claim of 5 watts or less consumption when the previous models typically consumed some 7 or 8 watts (un modified) against the previous 10W maximum claim. Does anyone get the feeling that their "Marketing Department" is doing what all marketing departments do as a matter of routine, which is making up their own figures without regard to actual test measurement data?  >:D

 Anyhow, regarding your mention of those forty dollar FY6600s on Ebay, I was intrigued enough to investigate what was on offer for myself. I did check out the prices on the FY6800s btw, before placing an order just half an hour ago on a FY6600-60M from Hong Kong for a mere £40.41p (just over half of the £75.66p I'd paid for my now much modded unit some seven months ago).

 I didn't fancy paying a 30 quid premium just to get a slightly nicer revamped front panel and a big butch switched C14 socket on what is essentially still an FY6600 inside. Besides which, it's a case of "Better the Devil you know." and it makes for a very cheap "Spare". The only concern with these "last available FY6600s" being whether they're unsold stock of all those models which had been afflicted by the version 3.0 firmware bug. :-\ Hopefully not but I should be able to determine that in some two to three week's time.  ;)

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: vince53 on June 11, 2019, 07:18:52 pm
I was fortunate to be able to retire a few years ago and one of the first missions was to set up a basic electronics bench for playing with radio control planes and amateur radio.  It didn't take long before I missed the resources and expertise I had enjoyed for decades, test equipment, metrology lab, machine and sheet metal shop.  One purchase was an old 5MHz function/ sweep generator.

I used it to align some AM radios but now I wanted to align the 10.7MHz IF sections.

So I recently purchased an FY6800.  After verifying it worked I ordered an assortment of upgrade parts.  I installed a linear 15vdc supply, installed new op amps and replaced the encoder so I could have a larger knob.  Next was to figure out how to get a repeatable setup for FM IF sweeps and contribute to the thread.

I'm testing and hear a high pitched squeal.  The LM337T failed and blew out one of the new op amps.  I reinstalled the original op amp .  Currently running off a bench supply with the board sitting an a cardboard box.

It appears to work like new.  So I'm back to playing with the sweep.  For now, it's not raining so outside I go.

It's been a pleasure to read all of this thread.  KC8AAC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 11, 2019, 11:47:51 pm

 Anyhow, regarding your mention of those forty dollar FY6600s on Ebay, I was intrigued enough to investigate what was on offer for myself. I did check out the prices on the FY6800s btw, before placing an order just half an hour ago on a FY6600-60M from Hong Kong for a mere £40.41p (just over half of the £75.66p I'd paid for my now much modded unit some seven months ago).

 I didn't fancy paying a 30 quid premium just to get a slightly nicer revamped front panel and a big butch switched C14 socket on what is essentially still an FY6600 inside. Besides which, it's a case of "Better the Devil you know." and it makes for a very cheap "Spare". The only concern with these "last available FY6600s" being whether they're unsold stock of all those models which had been afflicted by the version 3.0 firmware bug. :-\ Hopefully not but I should be able to determine that in some two to three week's time.  ;)

JBG

I agree that it looks like the original FY6600 with the latest firmware is the best option at this point--unless a teardown of the FY6900 reveals a new level of excellence.  I actually ordered two with the cheapest-option AU plug since I plan on converting them to  US/C5-C6 and adding a 10K resistor to the existing Y-cap and running it to ground.  Then I'll see how it works and if my EMI and noise is acceptable.  I have a use case for two--or three--using either the sync feature or using one to control the other thru the VCO port.  I paid a total of US$84.86 for two, shipped, so I can't imagine a better deal.  I can live with the output limitations--20Vp-p at 20MHz (let alone 60) is pretty hard to do with an inexpensive op amp.  And this thing has two channels!  I'd like to see a comparison with more expensive DDS AWG models--I've seen some at over 10X the price that don't seem to do as well as the lowly (and now dirt cheap) FY6600. If I need more power I'll get or make an amplifier.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 11, 2019, 11:52:29 pm

I used it to align some AM radios but now I wanted to align the 10.7MHz IF sections.

So I recently purchased an FY6800.  After verifying it worked I ordered an assortment of upgrade parts.  I installed a linear 15vdc supply, installed new op amps and replaced the encoder so I could have a larger knob.  Next was to figure out how to get a repeatable setup for FM IF sweeps and contribute to the thread.


I also want to repair/restore/adjust/align/fiddle with some FM receivers.  I'd be interested how you make out.  Is it necessary to have such high outputs that new power supplies, op-amps, etc are needed? 
Also, I'm trying to synthesize a usable FM multiplex stereo test signal.  I have an RF signal generator with an FM function, but the multiplex signal is complex and I'm still trying to figure out the best way to do it.  Any ideas?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on June 12, 2019, 01:53:04 am

====snip====

So I recently purchased an FY6800.  After verifying it worked I ordered an assortment of upgrade parts.  I installed a linear 15vdc supply, installed new op amps and replaced the encoder so I could have a larger knob.  Next was to figure out how to get a repeatable setup for FM IF sweeps and contribute to the thread.

I'm testing and hear a high pitched squeal.  The LM337T failed and blew out one of the new op amps.  I reinstalled the original op amp .  Currently running off a bench supply with the board sitting an a cardboard box.

It appears to work like new.  So I'm back to playing with the sweep.  For now, it's not raining so outside I go.

It's been a pleasure to read all of this thread.  KC8AAC

 I'm sorry to hear of your misfortune with the blown supply and one deceased opamp. Those analogue regulators are supposed to have over-current/temperature protection to prevent such disasters. Did you install a cooling fan btw. Most (possibly all) of the previous PSU modders took the precaution of fitting a fan once they realised just how hot these generators were getting even before having the extra thermal loading from an analogue PSU upgrade imposed upon them.

 Indeed, I'll be fitting a 50mm cooling fan to my 40 quid prize once I've allowed a few months of "hard use" to prove it isn't harbouring any "Infant Mortality" failure mechanisms. I don't want to risk invalidating the warranty or the Ebay money back guarantee too soon like I did with the first one. A cooling fan mod should take priority over any other mods you might be contemplating imo.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Andbro on June 12, 2019, 11:39:06 am
Hi,

If the 6600 to 6900 are not good. Do you have any suggestions???

Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GerryR on June 12, 2019, 05:55:15 pm
Personally, I didn't think that the 6800 that I had purchased wasn't worth much past 20-to-25 MHz (As mentioned above, I ended up returning it.).  I found a descent BK Precision 4045B (20 MHz unit) on ebay for a few dollars more than the 6800.  It doesn't have all features claimed by the 6800, but what it does have works!  I must admit that I am a little bit funny about my test equipment; if something doesn't perform to the mfg's spec, I lose confidence in the whole instrument.  It's OK to make a hobby project out of an instrument, but .....
I had an HP34401A multimeter that I paid $1100.00 for about 18 years ago.  While working on a project, I found that it couldn't measure the DC offset of a sine wave.  My cheapo hand-held meters could make the measurement, but this fancy piece of gear couldn't!  The people at HP (now Keysight) said it was a "quirk" that I ran into, and I should just trade it in on something newer.  Lost all trust in the meter...Up for sale!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 12, 2019, 06:34:22 pm
Hi,

If the 6600 to 6900 are not good. Do you have any suggestions???

Thanks

I think the best choices are:

A.  Buy a 6600 and use it in the grounded configuration and don't expect more than 10Vp-p output.

B.  Buy a 6600 and modify it if you absolutely need floating configuration.

C.  Spend a LOT more money and maybe get something that really isn't any better.

These are not precision function or pulse generators or low distortion audio signal generators, they are versatile and useful Arbitrary Waveform Generators.  They are very handy for a wide variety of things.  There may be a few bugs, quirks, anomalies or shortcomings, but I've seen equipment that costs 1000X as much have just as many issues.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 12, 2019, 06:55:09 pm
Personally, I didn't think that the 6800 that I had purchased wasn't worth much past 20-to-25 MHz (As mentioned above, I ended up returning it.).  I found a descent BK Precision 4045B (20 MHz unit) on ebay for a few dollars more than the 6800.  It doesn't have all features claimed by the 6800, but what it does have works!  I must admit that I am a little bit funny about my test equipment; if something doesn't perform to the mfg's spec, I lose confidence in the whole instrument.  It's OK to make a hobby project out of an instrument, but .....
I had an HP34401A multimeter that I paid $1100.00 for about 18 years ago.  While working on a project, I found that it couldn't measure the DC offset of a sine wave.  My cheapo hand-held meters could make the measurement, but this fancy piece of gear couldn't!  The people at HP (now Keysight) said it was a "quirk" that I ran into, and I should just trade it in on something newer.  Lost all trust in the meter...Up for sale!

I saw the 4045Bs on eBay, that is a lot off the new price for a 'current' unit.  But how does the square wave actually look??  They list a 20ns rise time, which is more than 3x worse than the FY6600.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GerryR on June 12, 2019, 08:26:29 pm

I saw the 4045Bs on eBay, that is a lot off the new price for a 'current' unit.  But how does the square wave actually look??  They list a 20ns rise time, which is more than 3x worse than the FY6600.

My Rigol DS1102D shows the rise and fall times to be about 13 ns;  Square wave looks good to about 15MHz and gets very "siney" after that, though rise and fall times remain around 13 ns out to 20 MHz.  The 6800 square wave got  looking like a sine wave around 15 MHz, as well.  Everything I've checked on the 4045B, so far, is dead on.  Good price from one seller on ebay ($124.95 shipped) and the unit I received looks new.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 13, 2019, 12:35:16 am

My Rigol DS1102D shows the rise and fall times to be about 13 ns;  Square wave looks good to about 15MHz and gets very "siney" after that, though rise and fall times remain around 13 ns out to 20 MHz.  The 6800 square wave got  looking like a sine wave around 15 MHz, as well.  Everything I've checked on the 4045B, so far, is dead on.  Good price from one seller on ebay ($124.95 shipped) and the unit I received looks new.

My FY6600 gives me 8 ns or so and still looks pretty square.  Perhaps your FY6800 underperformed--or how did you connect it?  I have a 50cm RG316/BNC cable direct from AWG to DSO.

However, there is a jitter issue with high frequency square waves with a period that is not a multiple of 4 ns!  See second photo.  I think this is just an unavoidable result of a 250 MSa/s DDS.  If you need a precise, low jitter square wave, this limitation would be significant.

Does the BK unit appear to not have this issue?  It only has 50 MSa/s, so if it can produce a reasonable 9.999999 MHz square wave, then is must not be using the DDS for the basic sine/square/triangle/ramp functions.   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GerryR on June 13, 2019, 01:08:55 am
The Spec sheet says the following:

"The true arbitrary waveform section generates point by point waveforms with lower jitter, high
resolution, and true representation of the required waveform."
"Due to the arbitrary waveform capability of the 4045B, the instrument is able to generate low-jitter square waves with greater edge
stability. The improved signal integrity allows these generators to be used for simulating reliable clock signals, generating triggers, or
validating serial data buses."

I haven't been inside it yet to see what is going on, but I don't see any jitter on through 20 MHZ, unlike the 6800, and the jitter I saw on the 6800 got really bad at the higher frequencies.  I may have gotten a poor unit, but it did have the 1.7.1 firmware.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 13, 2019, 01:11:14 am
So to answer my own question, it appears the BK 4045B uses a 50MSa/s DDS for "general" AWG duty and a "True AWG" with a variable clock (probably up to 50 MHz) for the advertised low-jitter sine/square/triangle/ramp functions.  I might just "need" one.  BK Precision does have some nice stuff if you can get it cheap enough.  ;)

https://bkpmedia.s3.amazonaws.com/downloads/datasheets/en-us/4045B_datasheet.pdf (https://bkpmedia.s3.amazonaws.com/downloads/datasheets/en-us/4045B_datasheet.pdf)

https://www.tegam.com/wp-content/uploads/2015/10/AN4011.pdf (https://www.tegam.com/wp-content/uploads/2015/10/AN4011.pdf)
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdunham7 on June 13, 2019, 01:12:54 am

I haven't been inside it yet to see what is going on, but I don't see any jitter on through 20 MHZ, unlike the 6800, and the jitter I saw on the 6800 got really bad at the higher frequencies.  I may have gotten a poor unit, but it did have the 1.7.1 firmware.

Were you looking at sine or square waves?  Square waves (and others) will have the jitter I described just because of the way DDS works, but on mine the sine waves are rock steady.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: GerryR on June 13, 2019, 11:04:54 am
I'm talking about square waves; sine waves are clean, triangle waves show some distortion at higher amplitudes on the down slope(frequencies are fine).  I haven't done a full inspection of all it is supposed to do, but so far, it looks pretty clean.  I am going directly from the generator to the scope thru a 50 ohm terminator at the scope.  Oh, the DC offset, when set to "0," is about 1.35 mV, much better than the 35 mV of the 6800, which of course, there is a remedy for by some hacking.

At $125.00, you surely do need one!  ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: vince53 on June 13, 2019, 10:38:27 pm
FM IF Sweep.

Getting this working was more about learning how my scope worked than my FY6800.
I produced these nice filled traces by using infinite persistence and adjusting the number of points.  I suspect other scopes may need to be adjusted differently.

First photo:  The purple trace is the generator output from channel #2, 1kHz sine wave with the amplitude at 6.2v and offset at 2.7v
Green trace: sweep of 10.2MHz to 11.2MHz using VCO mode with a cable from output #2 to VCO In at the back of the generator. 
Red trace:  FFT math function of green trace.

Second photo: Purple trace, input to VCO IN
Green trace: 1MHz wide sweep with the center at 10.7MHz.  The signal is fed through a Yaesu receiver prefilter.

Third photo: measurements for the control ramp.  DC coupling.  6.2v peak to peak, with 5.7 volts for the positive peak and and -0.57v for the negative peak.
The spec for the VCO In is 0-5vdc.  To get the full sweep I needed to start below 0vdc and ramp to about 5.3vdc.  This is consistent with an earlier post.  To get the full sweep I had to use 6.2v for the amplitude and 2.7v for the offset.  VCO IN maximum frequency is 500Hz but I had to go higher to get the trace on the scope.  Values may vary but it can be made to work.
1 Megohm input impedance of the scope was used. 

I couldn't figure out how to use the "Insert Image" tool so I'll try Attachments.

Vince KC8AAC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on July 05, 2019, 10:27:54 pm

 Anyhow, regarding your mention of those forty dollar FY6600s on Ebay, I was intrigued enough to investigate what was on offer for myself. I did check out the prices on the FY6800s btw, before placing an order just half an hour ago on a FY6600-60M from Hong Kong for a mere £40.41p (just over half of the £75.66p I'd paid for my now much modded unit some seven months ago).

 I didn't fancy paying a 30 quid premium just to get a slightly nicer revamped front panel and a big butch switched C14 socket on what is essentially still an FY6600 inside. Besides which, it's a case of "Better the Devil you know." and it makes for a very cheap "Spare". The only concern with these "last available FY6600s" being whether they're unsold stock of all those models which had been afflicted by the version 3.0 firmware bug. :-\ Hopefully not but I should be able to determine that in some two to three week's time.  ;)

JBG

I agree that it looks like the original FY6600 with the latest firmware is the best option at this point--unless a teardown of the FY6900 reveals a new level of excellence.  I actually ordered two with the cheapest-option AU plug since I plan on converting them to  US/C5-C6 and adding a 10K resistor to the existing Y-cap and running it to ground.  Then I'll see how it works and if my EMI and noise is acceptable.  I have a use case for two--or three--using either the sync feature or using one to control the other thru the VCO port.  I paid a total of US$84.86 for two, shipped, so I can't imagine a better deal.  I can live with the output limitations--20Vp-p at 20MHz (let alone 60) is pretty hard to do with an inexpensive op amp.  And this thing has two channels!  I'd like to see a comparison with more expensive DDS AWG models--I've seen some at over 10X the price that don't seem to do as well as the lowly (and now dirt cheap) FY6600. If I need more power I'll get or make an amplifier.

 Hi bdunham7,

 Apologies for the tardy response. I'm not sure how I overlooked your reply but, after reviewing the recent postings here, I realised my oversight hence this response.

 One thing that did catch my attention was your reference to attaching a 10KR to the Y cap. Presumably (just to be absolutely clear on this point), connecting the resistor between the protective earth pin on the C6 connector and the side of the Y cap going to the zero volt rail and the BNC grounds rather than across it.  :)

 The Hong Kong dealer I bought mine from was out of stock of the UK plug versions so, since the crappy UK plug with C8 lead was destined for the scrap bucket anyway, I chose the (no doubt equally crap) US option (sadly, no additional discount for this cheaper mains lead option).

 At an effective price of $42.43 each, you got an even better bargain than my own £40.41 'prize' which equates to a 49 dollar price tag (give or take a dollar or two). However, we Right Pondians have long since come to accept this disparity in pricing between the US and UK markets for 'foreign goods' so it still represented a massive reduction on the £75.66 I'd originally paid for the first one some seven months earlier.

 I had hoped to be able to report on the firmware loaded into my unit by now but it hasn't arrived yet, some two days after the latest of the estimated delivery dates. It looks like a cheap MESTEK 9999 Counts Digital Multimeter I ordered just four days ago is likely to arrive before the signal generator according to Yodel's tracking info[1] - there's no tracking option for the generator so its delivery is a matter of blind faith.  :( I guess I'll have to give it another week before I start pestering the seller/ebay over this delay.

 I have just one other ebay order in the pipeline race to my front door but that's just a 99p order for a pack of 10 SN74HC14Ns due to arrive by the 25th. Unbelievably, there's even a tracking number on this 99p order but ICBA checking the progress of a 99p package that will probably arrive before the ETA expires anyway and isn't holding up progress on any of my current projects (at least not yet!).

 Regarding whether the FY6900 actually shortchanges you on the 20Vpp in the 10 to 20MHz frequency range or not remains an open question since (apart from the 24Vpp claim for the FY6900), the same limitations are quoted in the manuals for the 6600 and 6800 models making the specifications published in the manuals rather suspect to say the least. We're not going to know the truth of the matter until someone finally gets hold of one to report actual test figures.

 As for the business of 24Vpp for the DC to 5MHz range, that appears to be an attempt at one-up-man-ship in the specifications battle. It seems to me a rather pointless distraction since, as you mentioned, this is nothing a linear amplifier couldn't address more effectively anyway if higher outputs are needed. The only thing about the 24Vpp figure, along with the extended +/-12v dc offset specification, is the implication that they've raised the PSU board's +/-12v rail voltages to +/-15v which may or may not be a good thing, depending on how they've achieved this.

 It seems rather doubtful that they've moved from a switching psu board to an analogue one if this is the case. The extra voltage will provide more margin but if they've simply rejigged the existing transformer windings to raise the voltage without using a beefier HV switching chip or adding a discrete HV switching transistor to take the load off the existing chip, this could all end up in 'Tears Before Bedtime' as far as the service life of the PSU board goes. I can't wait to see a competent tear down review video on this latest version of the FY6600 from Feeltech / Feelelec when it's eventually released to the market.  >:D

[1] I just had another look at Yodel's tracking website and it's now, at long last, offering an ETA of Saturday the 6th (tomorrow) for that Mestek DMM so it looks like the result in the "Slow Boat From China" race as far as that FY6600 is concerned is going to be a draw at best. My money's on the Mestek winning this race but the possibility of a "dead heat"  for all three orders still remains intact, making this Saturday a little on the special side for me to look forward to.  :popcorn:

[EDIT]  The DMM arrived at 1pm but I'm still waiting on the cheap FY6600 and that pack of hex inverters.

JBG

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: battlecoder on July 14, 2019, 12:34:50 am
Has anyone gotten the firmware update to work with PC Software version 6.0?
My FY6600 has firmware 3.1, PC Software says that the latest available firmware is 3.3, but when I click "update" it seems to download something but then it immediately throws the error "USB linkage fault".
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aneevuser on July 16, 2019, 07:21:36 pm
I've attached an image of the signal that I get from my FY6800, channel 1, with the unit on, but with channel 1 disabled. There's noise at about 44 kHz of about 40 mV pp, which I'm guessing is from the SMPS.

My question is: is noise of this magnitude expected from this unit?

I'm finding that it's making it rather tricky to trigger on signals below about 100 mV reliably, but I'm too much of a noob to know if this is standard for a SMPS, or if I've got a dodgy device.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: FuzzyOtter on July 16, 2019, 07:31:09 pm
I don't have one of these devices, but what does the scope show you with the unit powered off entirely? Is it the same, or does some/all of the measurement clean itself up? Just curious to know if it's actually coming from the unit, or if it's radiated from somewhere else.

You might try enabling the 20MHz bandwidth limit on the scope to knock some of the noise down if those spurs are giving you trouble with triggering.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aneevuser on July 16, 2019, 07:44:59 pm
I don't have one of these devices, but what does the scope show you with the unit powered off entirely? Is it the same, or does some/all of the measurement clean itself up? Just curious to know if it's actually coming from the unit, or if it's radiated from somewhere else.
It's coming from the unit: I've attached an image of the same setup but with the FY6800 switched off at the mains.

Quote
You might try enabling the 20MHz bandwidth limit on the scope to knock some of the noise down if those spurs are giving you trouble with triggering.
Yes, I've tried that but it doesn't really clean things up enough. I'm not sure if this is just something that I have to live with. It's a bit of pity if so, as the device itself can generate sub 10 mV signals, but they're swamped in the SMPS noise.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: battlecoder on July 17, 2019, 01:33:59 am
I don't have one of these devices, but what does the scope show you with the unit powered off entirely? Is it the same, or does some/all of the measurement clean itself up? Just curious to know if it's actually coming from the unit, or if it's radiated from somewhere else.
It's coming from the unit: I've attached an image of the same setup but with the FY6800 switched off at the mains.

Quote
You might try enabling the 20MHz bandwidth limit on the scope to knock some of the noise down if those spurs are giving you trouble with triggering.
Yes, I've tried that but it doesn't really clean things up enough. I'm not sure if this is just something that I have to live with. It's a bit of pity if so, as the device itself can generate sub 10 mV signals, but they're swamped in the SMPS noise.

I tried with my unit and the freerunning waveform shows some peaks of around 30mV. That goes down to around 14mV with 20MHz BW limit.
If I trigger on the spikes, and zoom into the periodic "noise", I'm getting a 10mV, 6-7Khz nonsense.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on July 17, 2019, 01:43:35 am
Just how are you getting the signal from the Feeltech into your Rigol? It matters!

Some time ago I built a BNC - Probe adapter (can also be brought online) https://www.eevblog.com/forum/beginners/o-scope-probe-to-bnc-adaptor-(dave-uses-on-in-642)-where-to-findbuy/msg2287812/#msg2287812 (https://www.eevblog.com/forum/beginners/o-scope-probe-to-bnc-adaptor-(dave-uses-on-in-642)-where-to-findbuy/msg2287812/#msg2287812)

Fixes a bunch of induced noise source issues compared to incorrectly terminated scope inputs.
(https://www.eevblog.com/forum/beginners/o-scope-probe-to-bnc-adaptor-(dave-uses-on-in-642)-where-to-findbuy/?action=dlattach;attach=684120;image)

Have a trawl through this youtube search too https://www.youtube.com/results?search_query=oscilloscope+termination (https://www.youtube.com/results?search_query=oscilloscope+termination)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on July 17, 2019, 06:31:09 am
I've attached an image of the signal that I get from my FY6800, channel 1, with the unit on, but with channel 1 disabled. There's noise at about 44 kHz of about 40 mV pp, which I'm guessing is from the SMPS.

My question is: is noise of this magnitude expected from this unit?

I read that other users also have experienced with such noise from switching power supply. It may leak through ground wire, so it may be  hard to get rid of it. I think the only way is to replace it with linear power supply, but it will require better ventilation in order to cool down power supply.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aneevuser on July 17, 2019, 09:08:44 am
Just how are you getting the signal from the Feeltech into your Rigol? It matters!
I'm not sure how that is relevant to my problem, though.

I'm typically taking the signal to a breadboard with the BNC-croc clip cable provided with the FY6800. However, the noise that I see is present at the BNC connector on the device itself; it's not radiated noise that is picked up by the cable. So I can't see how any different cable would improve the situation (unless there's some kind of fancy filtering on it, and I don't think that you're suggesting that?). Maybe I'm misunderstanding you though.

Anyway, the figure posted earlier by battlecoder suggests that this noise is not untypical, so I guess I'll have to live with it, unless I can figure out how to replace the power supply.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aneevuser on July 17, 2019, 09:11:19 am
I tried with my unit and the freerunning waveform shows some peaks of around 30mV. That goes down to around 14mV with 20MHz BW limit.

Thanks. Not different from what I see. I guess that it's a design problem, rather than a one off quirk of my unit.

Quote
If I trigger on the spikes, and zoom into the periodic "noise", I'm getting a 10mV, 6-7Khz nonsense.
Not sure what you mean here - what's the "nonsense"?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on July 17, 2019, 09:16:16 am
Fairly simple you are blaming the source without considering the measurement tool and the cable leading up to it as the potential problem. Incorrectly terminated transmission lines (not impedance matched) not to mention breadboards SUCK and are as noisy as ......
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on July 17, 2019, 09:46:56 am
unless I can figure out how to replace the power supply.

Here is experience of one user to replace power supply with linear one. It helps a lot to remove such noise.
It is in russian, but I'm sure you will understand all from pictures.

https://www.nickbel.com/2018/10/05/zamena-bp-na-lineynyy-transformatornyy.html (https://www.nickbel.com/2018/10/05/zamena-bp-na-lineynyy-transformatornyy.html)

https://www.youtube.com/watch?v=sRIVwqfqpu8 (https://www.youtube.com/watch?v=sRIVwqfqpu8)

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aneevuser on July 17, 2019, 12:15:59 pm
Fairly simple you are blaming the source without considering the measurement tool and the cable leading up to it as the potential problem. Incorrectly terminated transmission lines (not impedance matched) not to mention breadboards SUCK and are as noisy as ......
Well, it's always worth considering alternative explanations but if this were a transmission line problem, would it not be strongly frequency dependent? I see precisely the same noise signature from DC up to 1 MHz. In addition, as I mentioned earlier, it's present directly at the BNC output of the device so the presence of the cable or breadboard is irrelevant.

I'm not convinced this has anything to do with transmission line problems.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aneevuser on July 17, 2019, 12:24:15 pm

Here is experience of one user to replace power supply with linear one. It helps a lot to remove such noise.
It is in russian, but I'm sure you will understand all from pictures.


Thanks. Looks useful. My Russian isn't too bad, so with the autogenerated subtitles, I should be able to understand a fair bit of that. I guess that there'll be others on Youtube as well, if this is a known problem with the device.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on July 17, 2019, 09:02:18 pm
You don't have to know russian , if you have patience to read this thread you will find that for a long time users have replaced that crappy cheap SMPS with a transformer + linear regulators and how they did it .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on July 25, 2019, 04:57:16 am
For those suffering with blown or broken units this may offer a possible way out FINALLY after some kicking :palm: Taken from the spriuking 6900 thread in the For Sale section.

Personally I think their way out should be firmware release but this may at least provide an option better than has been available in the past.

You simply FAIL to comprehend your past. About the only way forward to start to remedy this is release the firmware for the FY6600 and the method to repair damaged units. Either that or consider sending 'review samples of your new one to those affected that have dead units. Return shipping and freighting units is just not on unless YOU are paying for postage both ways.

Both of the member quotes above were from your most recent spruiking of the 6800. And surprise surprise went unanswered.
This Link https://www.eevblog.com/forum/contests/feeltech-fy6800-signal-generator-free-trial/ (https://www.eevblog.com/forum/contests/feeltech-fy6800-signal-generator-free-trial/)

We have no staff to take charge of this forum account before. We have not landed in this forum for a long time. We apologize for the vacancy in our work. At the same time, we will compensate the damaged customers. From now on, our account is in the charge of a special person, we will maintain the forum. Customers who have purchased version FY6600 V3.0 before will send the firmware chip downloaded version V3.1 free of charge as long as they contact us. At the same time, if these customers intend to purchase FY6900 series products, our company will return all the profits of the machine to customers, charging only the cost of equipment and transportation costs. Please contact us in EVVblog or Email.

Email address: service@feelelec.com

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on July 25, 2019, 05:15:13 am
Interesting development. Of course, the proof in the pudding is in the eating. So, it's time for all the V3 owners to put FE to the test.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: beanflying on July 25, 2019, 05:17:39 am
Interesting development. Of course, the proof in the pudding is in the eating. So, it's time for all the V3 owners to put FE to the test.

I dropped Fremen67 a PM. Offhand I can't recall others with dead or partially dead units but if others do hit them up.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: FeelElec on July 25, 2019, 07:27:36 am
Has anyone gotten the firmware update to work with PC Software version 6.0?
My FY6600 has firmware 3.1, PC Software says that the latest available firmware is 3.3, but when I click "update" it seems to download something but then it immediately throws the error "USB linkage fault".

Dear Customers,
3.3 began to add online upgrade function, 3.1 does not support online upgrade.
If you have any problems with version 3.1, please feel free to contact us.

FeelElec
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: battlecoder on July 25, 2019, 02:03:51 pm
Has anyone gotten the firmware update to work with PC Software version 6.0?
My FY6600 has firmware 3.1, PC Software says that the latest available firmware is 3.3, but when I click "update" it seems to download something but then it immediately throws the error "USB linkage fault".

Dear Customers,
3.3 began to add online upgrade function, 3.1 does not support online upgrade.
If you have any problems with version 3.1, please feel free to contact us.

FeelElec


Oh. That's quite unfortunate.
Thanks for the answer, though.
Do you have a changelog of what was updated, changed, or fixed in version 3.3 so I can see what I'm missing?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on July 25, 2019, 08:07:18 pm
Interesting development. Of course, the proof in the pudding is in the eating. So, it's time for all the V3 owners to put FE to the test.

I dropped Fremen67 a PM. Offhand I can't recall others with dead or partially dead units but if others do hit them up.

 His last posting to this thread was back in June last year

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1597255/#msg1597255 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1597255/#msg1597255)

 and he hasn't been heard from since. A few have expressed concerns over his sudden disappearance in the middle of answering questions and providing feedback, fearing the worst for his health and well being. If you do hear from him, I'm sure many others here will appreciate any further news you might glean from this recent PM attempt. I believe others tried to PM him but without reply. Hopefully, you might strike lucky this time.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: FeelElec on July 26, 2019, 12:35:44 am
Oh. That's quite unfortunate.
Thanks for the answer, though.
Do you have a changelog of what was updated, changed, or fixed in version 3.3 so I can see what I'm missing?

Dear Customers:
This is the answer: 3.3 Added offline upgrade firmware function, other functions are consistent with 3.1.

FeelElec
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: MikeLud on August 03, 2019, 04:27:44 am
I need some help with my FY6800 power supply upgrade. |O I did most of the upgrades shown in this schematic https://github.com/DerKammi/FY6600-15-30-50-60M/blob/master/Hardware/FY6600%20PS%20schematic%20V1.pdf (https://github.com/DerKammi/FY6600-15-30-50-60M/blob/master/Hardware/FY6600%20PS%20schematic%20V1.pdf). The only difference is I did not change D9 and instead of changing R6 I replaced the two 10K voltage divider with a 20K Multiturn Trim Pot wire the same as a voltage divider so I can adjust the output voltage. Also instead of using a 68uF 400V for C2 I used a 33uf 400V. Now the FY6800 intermittently turns on by having to turn it on and then off several times using the switch in the back. When it does turn on it works fine, with the power supply voltage at -13.6V, +13.5V, and +5.0V. and the on/off button in the front work fine as long as I do not turn it off with the back switch. Any help will be appreciated.

Thanks,
Mike
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on August 03, 2019, 06:11:02 am
I don't think that power supply is worth upgrating , just replaced with a linear one .
Anyway you should measure your pot resistance and see if  it works ok with the old value 10k , in a such SMPS you can't change the voltage by much or could become unstable . Even if it's 12K as the autor say it works , because of various tolerances is not certain that in every case  will work
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: FeelElec on August 03, 2019, 10:07:14 am
I need some help with my FY6800 power supply upgrade. |O I did most of the upgrades shown in this schematic https://github.com/DerKammi/FY6600-15-30-50-60M/blob/master/Hardware/FY6600%20PS%20schematic%20V1.pdf (https://github.com/DerKammi/FY6600-15-30-50-60M/blob/master/Hardware/FY6600%20PS%20schematic%20V1.pdf). The only difference is I did not change D9 and instead of changing R6 I replaced the two 10K voltage divider with a 20K Multiturn Trim Pot wire the same as a voltage divider so I can adjust the output voltage. Also instead of using a 68uF 400V for C2 I used a 33uf 400V. Now the FY6800 intermittently turns on by having to turn it on and then off several times using the switch in the back. When it does turn on it works fine, with the power supply voltage at -13.6V, +13.5V, and +5.0V. and the on/off button in the front work fine as long as I do not turn it off with the back switch. Any help will be appreciated.

Thanks,
Mike

Dear Customers:

If you want to cut off 220V power supply, you can only turn off the power switch in the back. It is not recommended to change the power parameters. Replacing linear power supply can reduce the noise of small signal.

FeelElec
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on August 03, 2019, 10:23:51 pm
I need some help with my FY6800 power supply upgrade. |O I did most of the upgrades shown in this schematic https://github.com/DerKammi/FY6600-15-30-50-60M/blob/master/Hardware/FY6600%20PS%20schematic%20V1.pdf (https://github.com/DerKammi/FY6600-15-30-50-60M/blob/master/Hardware/FY6600%20PS%20schematic%20V1.pdf). The only difference is I did not change D9 and instead of changing R6 I replaced the two 10K voltage divider with a 20K Multiturn Trim Pot wire the same as a voltage divider so I can adjust the output voltage. Also instead of using a 68uF 400V for C2 I used a 33uf 400V. Now the FY6800 intermittently turns on by having to turn it on and then off several times using the switch in the back. When it does turn on it works fine, with the power supply voltage at -13.6V, +13.5V, and +5.0V. and the on/off button in the front work fine as long as I do not turn it off with the back switch. Any help will be appreciated.

Thanks,
Mike

 Hi Mike, and welcome to the FY66/68 hundred modders' house of fun and pains. >:D

 I had several criticism regarding those modifications when I looked them over for inspiration on 'improving' the PSU board in my then newly acquired FY6600-60M way back in November last year just before I made my very first post to this forum. I've inserted a link so you can see my initial modifications to the PSU board (I've lost count of the all the other mods I've tried with that PSU since then).

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1973777/#msg1973777 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1973777/#msg1973777)

 For starters, the value of the mains smoothing cap was over-specified by almost a factor of seven. The original 10μF 450v is entirely adequate for a 10W rated smpsu designed to operate on mains voltages in the 86 to 365 vac range (1μF per watt appears to be based on a universal design rule for all such universal mains voltage smpsus - I've yet to come across any exceptions to this 1μF per rated watt rule).

 If you're only using it on 220v or 240v mains supplies (the harmonised 230v mains specification in all its guises of practical reality) without any thoughts of ever using it on 110/120v supplies, there's absolutely nothing to be gained by such an 'upgrade'. Indeed, the reduced voltage rating from 450 to 400 volt of the suggested replacement places the logic of replacing the 220μF 16v caps on the 12v rails with 25v rated 220μF caps in some doubt.

 Whilst the 400v rating is perfectly fine for this task, the voltage rating upgrade on those 16v 220μF caps would equate to increasing a 400v smoothing cap to 625v (or the original 450v cap to a 700v rated one - it makes very little sense when the PSU is operating under its designed conditions (never disconnected from the load whilst powered up for prolonged periods of time) to uprate those output caps to 25v. A far more useful upgrade would be to replace them with 470μF 16v caps - the voltage isn't the issue here (it really isn't - trust me).

 However, when it comes to improving the smoothing on the 5v supply, it can be all too easy to get carried away (replacing the 470μF with an 1800μF 6.3v cap and replacing the 220μF with a 1000μF 6.3v cap) and overload the dinky little high voltage switching IC on startup causing it to sulk in a shutdown standby state. In the end, I landed up reducing these capacitor upgrades in two stages before I could eliminate the hot restart issue that had appeared after I'd cured the cold startup issue. Effectively, I'd dialled back the 1800μF to a mere 1000μF and restored the original 220μF.

 You could say (as indeed someone did) that I'd upgraded it to 'capacity'. If I hadn't already upgraded the 12v rail caps to 470μF ones, I might have gotten away with the 5v rail capacitor upgrade. However, using up my capacity margin on the 12v rails was the best option anyway - less ripple on the analog supplies (all derived off the 12v rails) where it really matters - the 5v rails can go hang, it's only used to power the three LDO regulators anyway (3.3, 2.5 and 1.8 volt rails) on the main board.

 The diode upgrades are a definite requirement to both improve the 12v rail voltages and the efficiency of the PSU (apropos of which, install a small cooling fan if you don't want to be faced with a recapping job in 12 to 18 months time - the vent slots are counterproductive to passive cooling, a small vent fan is an absolute must imho). If you read that first posting of mine, you'll note I went a little overboard on the diode upgrade (well, I had them to hand, so why not already? :) ).

 Much later on, I'd worked out an optimal solution to increasing the voltages on the 12v rails far more effectively than my 47k 10% boosting bodge on the 5v rail to likewise boost the 12v rails (over and above the extra two turns I'd added to each of the two 12v windings I'd applied in a previous modding session). ebel0410's mofification to the voltage feedback network raised a wry smile by the fact that he'd made more work for himself by removing R6 and replacing it with a 12K rather than use the quicker and slightly more effective shunting of the other 10K in the voltage divider with a 47K to get virtually the exact same result. When it comes to this sort of modding work, there's usually more than one way to skin the cat. >:D

 You can view my description of my final PSU mod here:-

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2310768/#msg2310768 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2310768/#msg2310768)

 And, you might find this earlier posting of some interest too.

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2182397/#msg2182397 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2182397/#msg2182397)

 For all its faults (high ripple noise - on a par with any commodity smpsu to be fair), the one thing Feeltech's tiny smpsu board doesn't suffer from is imbalanced current output ratings on its +/-12v rails, unlike every single example of dual rail commodity smpsus I've ever seen on Ebay (whether just a naked PCB or an enclosed unit).

 Looking on Ebay for dual rail smpsus designed to satisfy the requirements of dual rail opamps is on a par with tracking down Unicorn droppings (never mind the Unicorns themselves! >:( )  Typically, such small dual rail smpsus will specify a +12v rated at 600mA whilst the -12v rail is only rated for 150 to 250mA at most, often with the requirement that the +12v be loaded to a minimum level to bring the -12v to within 10% of its nominal voltage spec.

 Mind you, if you happen to be planning on adding a 12v 10MHz OCXO (with a 3N502 clock multiplier chip replacing the shite smd XO chip on the main board), such an imbalanced spec might be just the ticket!  >:D

 Obviously, there are suitable smpsu modules available which have balanced ratings and very low switching noise but you won't find any on Ebay. You have to deal with the manufacturers or their agents directly and put in a request for a quote on pricing and you know what they say about that... "If you have to ask, then you probably can't afford it." :(

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: MikeLud on August 03, 2019, 10:35:56 pm
I decided to go with replacing the SMPS with a linear power supply. I found a LM317/LM337 and LM317 linear regulator in country at a reasonable price, below are the links to the ones I will be using. To feed the linear regulators I am going to use a 30W R-Core Transformer 15V+15V 9V+9V.

https://www.parts-express.com/adjustable-voltage-regulator-power-supply-board-----125v-to-37v-dc-output-lm317-lm337-desig--320-616 (https://www.parts-express.com/adjustable-voltage-regulator-power-supply-board-----125v-to-37v-dc-output-lm317-lm337-desig--320-616)
https://www.parts-express.com/positive-voltage-adjustable-power-supply-board-ac-dc-in-dc-out-based-on-lm317t-regulato--320-614 (https://www.parts-express.com/positive-voltage-adjustable-power-supply-board-ac-dc-in-dc-out-based-on-lm317t-regulato--320-614)

Thanks,
Mike
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on August 03, 2019, 11:05:23 pm
I don't think that power supply is worth upgrating , just replaced with a linear one .
Anyway you should measure your pot resistance and see if  it works ok with the old value 10k , in a such SMPS you can't change the voltage by much or could become unstable . Even if it's 12K as the autor say it works , because of various tolerances is not certain that in every case  will work

 The analogue psu can be an effective solution but the downside is that you'll introduce greater thermal stress than the original (typically 70 to 80% efficient) smpsu board on the unit if you neglect to add a cooling fan to prevent an already hot running generator from overheating. Preferably a fan that offers a further reduction in temperature to extend the life of the components, most notably that of the 105deg C rated caps.

 Indeed, a few of the homebrewed analogue PSU projects have suffered regulator failures for lack of heatsinking, in some cases to the detriment of component failure on the main board (a brand new THS3091 burning out forcing the owner to revert back to the original THS3002i chip for lack of a spare 3091 being one notable event).

 If you're going to build a custom analogue psu, you need to be very mindful of this thermal issue. A fan is a must have item, even before you add the additional heat from an analogue psu, imho. IOW, make adding a cooling fan you first priority before doing anything else (after allowing a period of grace to allow any faults to show up before voiding the Chinese warranty, of course :-DD).

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: MikeLud on August 04, 2019, 02:35:17 am
JBG,

Thanks for your advice, I will be adding a cooling fan. Once I finish the PS upgrade I will be upgrading to a D75J and THS3091.

Thanks,

Mike

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on August 04, 2019, 06:27:18 am
I don't think that power supply is worth upgrating , just replaced with a linear one .
Anyway you should measure your pot resistance and see if  it works ok with the old value 10k , in a such SMPS you can't change the voltage by much or could become unstable . Even if it's 12K as the autor say it works , because of various tolerances is not certain that in every case  will work

 The analogue psu can be an effective solution but the downside is that you'll introduce greater thermal stress than the original (typically 70 to 80% efficient) smpsu board on the unit if you neglect to add a cooling fan to prevent an already hot running generator from overheating. Preferably a fan that offers a further reduction in temperature to extend the life of the components, most notably that of the 105deg C rated caps.

 Indeed, a few of the homebrewed analogue PSU projects have suffered regulator failures for lack of heatsinking, in some cases to the detriment of component failure on the main board (a brand new THS3091 burning out forcing the owner to revert back to the original THS3002i chip for lack of a spare 3091 being one notable event).

 If you're going to build a custom analogue psu, you need to be very mindful of this thermal issue. A fan is a must have item, even before you add the additional heat from an analogue psu, imho. IOW, make adding a cooling fan you first priority before doing anything else (after allowing a period of grace to allow any faults to show up before voiding the Chinese warranty, of course :-DD).

JBG

Yes , I know , or you could build the supply in an external box . Could be easier this way , you don't have to find the right size transformer .
Mine is inside and gets hot , for stand-by I found a signal from the microcontroller in the front display board that's switching a relay so +15V and -15V are disconnected. If not , in stand-by the analog part will still consume a lot of current ... no shut down feature was implemented in the original design .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on August 04, 2019, 10:54:31 pm
JBG,

Thanks for your advice, I will be adding a cooling fan. Once I finish the PS upgrade I will be upgrading to a D75J and THS3091.

Thanks,

Mike

 You might want to rethink the D75J option when you consider the fact that where the original crappy smd XO lives may well be running at 45 to 50 deg C as a consequence of all the heat being put into the board by the three LDO regulators located just one centimetre away. Those LDO regulators won't cool themselves you know, something has to handle the heat and that something is the PCB, including that smd XO. I'd measured 50 deg C on the XO with my IR thermometer with a 70 deg reading coming from the LDOs nearby.

 Mind you, this was whilst I still had the wick turned up by 10% on the 5 volt rail and fortunately before I extracted the 50MHz TCXO oscillator can from the "50MHz TCXO Power Board" I'd ordered as a cheap way to get hold of an oscillator to directly swap out with the smd XO (albeit by having to resort to the 'mount on stilts' bodge).

 In fact, I was still waiting for the oscillator board to be delivered when I made this discovery so was able to formulate a better use for the whole oscillator module to act as a deflector plate above the small 50mm square cooling fan I'd decided to fit into the base between the PS board and the back panel, adjacent to the main board where it could be held to within 2 or 3 degrees of room temperature rather suffer the 30 deg C temperature cycling of the original XO's location.

 As I mentioned, these temperature readings had been obtained during my "5.49 volt period", so would likely have been a few degrees hotter than the standard (4.96 volts) setting and by few, I mean less than 5 degrees.

 A couple of things that had put me off going the D75J route, aside from the delivered cost, was the absence of a calibration trimmer and the rather lacklustre +/-1ppm accuracy and stability. My motto being, "If a job's worth doing, it's worth doing well or not at all.", I felt the 20 fold improvement in frequency accuracy and stability being offered wasn't sufficient to justify the time and effort when, for pretty well the same money and just a modicum of extra effort, I could do ten times better on the stability front and somewhat better again on the calibration accuracy front, courtesy of the trimmer option gained by the purchase of that "oscillator power board".

 The JYEC DIP oscillator on that oscillator power board boasts a stability of +/- 0.1ppm over a a 0 to 25 deg C range and +/-0.2ppm over the -10 to +50 or 60 deg C range and, of necessity for this sort of accuracy and stability, boasts a trimmer to allow calibration against a reference frequency source such as a GPSDO.

 I've attached a photo of the oscillator board - it's now going spare, perhaps I can flog it as a CD player upgrade to some audiophool ;)

 The only thing going for the D75J option was that it was a simple drop in replacement (assuming smd reworking holds no terrors). The 50MHz +/-0.1ppm oscillator board, otoh, did offer the opportunity to avoid 30degC temperature cycling, allow calibration against an NPL standard, and a 200 fold improvement in stability and accuracy over the original XO versus the marginal 20 fold improvement offered by the D75J. The choice really was a no brainer, imho. ::)

 I was eventually able to calibrate that TCXO to within 30ppb before I gave up trying to improve my best efforts once I realised that it was destined to vary by around the same amount during each day's use. The only thing better than a TCXO being an OCXO but, at the time when I first read Arthur Dent's posts on his own OCXO upgrade project, my initial thought had been that he had gone just a little OTT in this upgrade exercise, especially considering the need to find an extra 3 or 4 hundred milliamps at 12 volts to power the OCXO's oven, necessitating either a PSU upgrade or else the addition of another 12v  half amp or better psu board inside the box[1].

 Strange to say, that's now where I'm at with my own pet FY6600 project having decided that such an OCXO upgrade wasn't so OTT after all!  :) It's amazing the things you can observe with a function generator that boasts a frequency accuracy better than 100ppt with a day to day stability of 20 to 30ppt. :)

 That's now more than sufficient to show the limitations of a basic PLL GPSDO based on a "cheap 'n' cheerful" navigation only GPS receiver module whose positional accuracy (and therefore timing data) is at the mercy of the vagaries of the ionosphere. I'm talking about the minute to minute nanosecond phase shifts rather than the long term precision which is not in any doubt.

 Anyway, enough about the issue of exposing a D75J to such temperature extremes as are to be found inside these Feeltech function generators. When I was suggesting there was no need to bump the 10μF 450v smoothing cap up to a 68μF 400v one, nor indeed any need even when powered off a 117v 60Hz mains supply, suggesting there was little point in such an "Upgrade" if you were powering it from 220 or 240 volt 50Hz mains supplies, I'd overlooked the Stars and Stripes flag signifying your location as being somewhere in the US. I had fleetingly thought of suggesting that a more modest increase of capacity to 12 or 15 or even 22μF (even 33μF if that's what you happened to have in your parts bin) could be applied for perhaps some marginal benefit to those on 117v mains power where the main benefit would be more a matter of riding through brief drop outs rather than improved smoothing.

 I'm not suggesting that you need to remove that 33μF cap: that's obviously fine in view of the fact that quite a few modders must have already proved that the 68μF has only harmed their bank balance with no ill effect to the PSU board itself. Of course, if you want to save that 33μF cap for 'better things', you might want to swap the original back in or select a 12 or 15μF cap instead. Choices, choices, choices! >:D

[NOTES]

[1]  I had to add a 12v 500mA smpsu board I'd removed from a small Linksys psu I'd had going surplus to requirements to power the OCXO board since I'm still running with the original (though modified) smpsu board. That actually gives me an advantage over Arthur Dent's version where, afaicr, he relied upon an upgraded PSU to power the OCXO. The advantage being I can now shut the whole signal generator down on the rear panel switch without interrupting power to the OCXO since I wired its dedicated psu directly to the mains socket so that for as long as it's plugged into a live mains outlet, it can maintain the crystal oven temperature indefinitely.

 The OCXO draws 5 watts from the mains when first powered up from cold but once up to temperature (after a 2 or 3 minute warmup time), this drops to a mere 1.3 watts (about half a watt lost in the psu with the OCXO taking some 700 to 800mW from the 12v supply). Putting the signal generator into standby using the front panel  on/off button, only saves a watt at most with a typical standby consumption of around 5 watts so this is a very worthwhile economy and life extending feature in an item of test gear you'd otherwise tend to keep powered up 24/7 in the interests of maintaining frequency stability.

 There is a tiny penalty in shutting it down overnight in that there seems to be a 30 to 60ppt 'warm up drift' (it's hard to quantify exactly with my current GPSDO lashup). For most practical purposes this is insignificant and later on, after I've installed an external reference input socket to feed it from a GPSDO, that isn't going to matter any more for any tests involving the need for such accuracy.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 07, 2019, 04:02:42 pm
The analogue psu can be an effective solution but the downside is that you'll introduce greater thermal stress than the original (typically 70 to 80% efficient) smpsu board on the unit if you neglect to add a cooling fan to prevent an already hot running generator from overheating.

 If you're going to build a custom analogue psu, you need to be very mindful of this thermal issue.

Use an R-core transformer instead of a standard EI one.  They run very cool and heat from them isn't an issue.  No fans necessary.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aliaj00 on August 07, 2019, 07:08:36 pm
Guys i just bought the FY6800.

As i am new i could find is the specs the max current this one can provide and the single channel.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ArthurDent on August 07, 2019, 11:44:12 pm
It’s been a while since I posted an update because basically I haven’t made any changes to my FY6600 for about one year. Here is a recap of what I did.

As you can see from the photos I’m still using the same FY6600 I bought originally with V3.1 firmware. I’m also using the same output amps that came with the unit. The high quality SMPS I settled on as a replacement for the crappy one is about 25W, is quiet, runs cool so no fan is required, and is quite small.

The timebase modification I made using the 5X PLL chip and the 10Mhz OCXO is working well and if I don’t mind waiting about ½ hour for it to warm up and stabilize, I don’t have to use the external GPSDO 10Mhz at all. This 15 year old OCXO is very stable and is good to about the first 10 digits. Keep in mind that this OCXO is far more accurate than the original and warms up fast so I could use it within minutes of powering it up but I prefer to wait until the drift rate is almost nil. When I do check it I use my scope with the time/division set to 2ns/div. The DDS circuit they use is damn good to another few digits as well if fed from the GPSDO or Rb standards.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on August 08, 2019, 03:29:03 am
 Thanks for posting those pictures, Arthur.

 When I first read your exploits with the OCXO, my first thought had been that such a modification was a little OTT but that was before I'd bagged myself a bunch of CQE OCXOs for experimenting with building GPSDOs after realising that a decent OCXO was the starting point rather than just an inconvenient add on to deal with the jitter from a u-blox M8N GPS receiver module's programmed 10MHz output. :-[

 I've long since come to properly appreciate the value of such an upgrade so my thanks to you for the inspirational use of a 3N502 clock multiplier chip. The initial choice I made in using a TCXO instead of the full fat solution of a TCXO, was driven by the fact that I wouldn't have to replace the existing PSU with a more powerful one for the sake of keeping an OCXO's oven up to temperature. In the end, I still avoided replacing the original psu by the expedient of adding a separate 12v 500mA smpsu board to power one those 12v CQE OCXOs I'd decided to put to good use as the generator's frequency reference.

 I'm planning on adding an external 10MHz reference input socket and use the injection locking technique to avoid the risk of glitching the front panel micro controller from switching between the local and external references - it had become a little twitchy in that regard after I'd installed the 50MHz TCXO board. It seems to have lost that twitchiness since upgrading to the OCXO but I'm still mindful of the potential problem such mechanical switching of oscillator sources might cause. Also, of course, it's a neat way to avoid the need for an actual switch to be fitted on the back panel. :)

 As for both yours and DaveR's view that there's no need to fit a cooling fan if either a more efficient smpsu is fitted or else an R type transformer is used for an analogue PSU replacement, I feel I must point out that you're overlooking the fact that both the FY6600 and Fy6800 models were already running uncomfortably hot before any additional heat sources were introduced into the box.

 The 25W rated smpsu might be cooler running from its point of view but the fact remains that its efficiency at a relatively low loading may be no better than the crappy original and quite likely adding a little more heat into the box. R type transformers in an analogue PSU aren't the problem, it's the waste heat from the analogue regulators that poses the real threat. R transformers are a good way to go but I'm not so sure about the analogue aspect unless it's being used to eliminate the high frequency ripple of a switching psu with consideration to the penalty of additional waste heat this introduces.

 At the time when such psu mods were a popular pastime, it seemed to be largely driven by the need to eliminate the half live mains 'leakage' esd risk inherent to all small class II smpsus through the mandated Y cap EMC bodge to reduce common mode conducted interference.

 Unfortunately, without ready access to the safety earth, even a conventional mains transformer analogue supply will still represent some esd risk to a poor defenceless DUT. That being the case, the pragmatic solution to that particular problem is simply to replace the non polarised two pin mains lead connector with a three pin type to give access to the safety earth by which to short out the unwanted leakage with a 1 to 10k 'drain resistor'. You could hard wire the BNC grounds if you like but this introduces a whole new can of worms to the FY6600 in the form of an unwanted mains wiring routed grounding loop (along with undesired galvanic and thermocouple induced dc offsets when working with millivolt level signal voltages).

 The main problem with the original PSU board after replacing the rectifier diodes with ones more suited to the task and doubling the 12v rail cap values to 16v 470μF types (the voltage rating isn't an issue here) and adding a single turn winding to buck the 5v secondary to get a better balance of power distribution to the 12v rails without making the three stooges (LDO regulators) get unnecessarily all hot and bothered, is the high level of HF ripple being both conducted and radiated to pollute the signal processing circuitry with noise. There's no doubt a much quieter PSU would improve the quality of the signals being generated whether it be an analogue or a switching psu.

 Most all modern T&M gear these days relies on SMPSU technology so it's obviously possible to design and manufacture low noise smpsus - I've just been too frightened to ask the price of such specialised ultra low noise switching psus and dc-dc converter regulator modules so I've put the question of improving the PSU on the back burner for now.

 I suspect it may be a lot easier to tame the problem of switching noise in DC-DC regulator converter modules than it is to deal with the high voltage switching noise in a conventional smpsu so a better approach might be to use an R transformer with conventional rectifier and smoothing to power switching DC-DC converter modules in the place of your typical 7805, 7812 and 7912 regulators.

 As it happens, I've just ordered a couple of small DC-DC converters from BangGood (along with a KSGER V2.1S T12 Digital Temperature Controller Soldering Station and other bits 'n' pieces) to try out with my current GPSDO project as an alternative to using a 7805 bolted onto the aluminium case to handle the 9 or 12 volt wallwart voltage conversion to the single internal 5 volt rail supply (I'm using the original 5v 13MHz CQE OCXO I'd fortuitously spotted and purchased for just 4 quid at the Blackpool amateur radio rally last April) so I'll be able to check the <30mV ripple claim made for the fixed 5v output module (the other module does 3.3, 5, 6, 9 and 12 volt but is silent on the subject of output ripple).

 A small efficient mains transformer using low noise switching converters may provide a more efficient solution to the problem of power supply ripple noise with the present PSU board. I don't really want to speed the fan up to compensate for an extra 5 to 10 watts heating load from an analogue PSU solution if I can help it.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: svetlov on August 08, 2019, 12:09:32 pm
Hello ! Comrades  :) - but there is a photo of the insides of the generator model 6900
it’s mostly interesting to see the main board of the generator - and in particular its output part
Thanks friends
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 08, 2019, 02:17:33 pm
As for both yours and DaveR's view that there's no need to fit a cooling fan if either a more efficient smpsu is fitted or else an R type transformer is used for an analogue PSU replacement, I feel I must point out that you're overlooking the fact that both the FY6600 and Fy6800 models were already running uncomfortably hot before any additional heat sources were introduced into the box.

 The 25W rated smpsu might be cooler running from its point of view but the fact remains that its efficiency at a relatively low loading may be no better than the crappy original and quite likely adding a little more heat into the box. R type transformers in an analogue PSU aren't the problem, it's the waste heat from the analogue regulators that poses the real threat. R transformers are a good way to go but I'm not so sure about the analogue aspect unless it's being used to eliminate the high frequency ripple of a switching psu with consideration to the penalty of additional waste heat this introduces.

I have to admit being rather puzzled by your statements about "running uncomfortably hot" initially, Johnny, as neither my 6600 nor my 6800 has ever run anywhere near a temperature I'd describe as hot.  "Moderately warm" is how I'd describe it, but perhaps it's a subjective assessment?  The biggest source of heat, by far, after I did the PS mods in the 6600 was from the 7805 regulator, which got to around 75C and created a local hot spot on the top of the case, but I cured this by swapping it for an OKI 78SR regulator, which runs as cool as the rest of the PS.  Any heat inside the case now comes from the Cyclone chip and the 3095 op amps, but even then I need to run them very hard for a couple of hours (something I've only done once, as a test) to get them to an elevated temperature.  (In real world usage I rarely use more than about 1Vp-p output, so everything stays very much cooler.)  In the same test the D75J TCXO had no problem in coping, with only a 0.1Hz drift at 10MHz after the first 10 minutes of warm up, and no drift after the next 15 minutes - pretty much in line with what you'd expect from an OCXO, depending on the level of sub-Hz accuracy you want.

I still haven't bothered to modify the 6800's PS or op amps even though I've had all the parts to do it since I bought the generator about a year ago - the D75J is the only change I've made, as the awful drift caused by the original XO just had to go.  The distortion produced by the original op amps is minimal at the levels I use, so I can live with them, and they run cooler than the the 3095 upgrades so heat produced in the case is even less than that in the 6600.  Looking back, the 6600 mods were done more for the challenge than out of necessity, but the 6800 works well enough as it now stands, so I'll probably wait until they do become a necessity before I do anything else to it.

Finally, it's nice to see you back Arthur, and thanks for the update on your mods!

Regards,
Dave

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on August 08, 2019, 02:23:32 pm
Hello ! Comrades  :) - but there is a photo of the insides of the generator model 6900
it’s mostly interesting to see the main board of the generator - and in particular its output part
Thanks friends

Is there a link to the photo, Svetlov?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 18, 2019, 08:37:39 pm
I just got one of these generators. One of the limitations I found (it may have already been discussed here before), is that the number of time points is 8192 even for a sine wave. As a result the "14 bit" resolution is not really realized. There are very visible steps in the sine waveform every 1/8192 of the period and the voltage steps correspond to about 11 bits of vertical resolution. To do it properly the number of time steps should be 2*Pi*(#vertical steps).

I am not sure anything can be done about it, just something to be aware of. Other function generators typically use more time steps.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 18, 2019, 10:42:25 pm
FYI  I just sent service@feelelec.com an email asking that they replace the front panels for the 4 people I was able to identify who are forum members with borked V 3.0 units.  I was able to furnish shipping information for 3 of them.  I never heard from @canyon.

As before I held out my carrot of a detailed comparison against a Keysight 33622A using my HP 8560A spectrum analyzer.  I attached some screen shots at under 5 V output levels which are close enough that I don't think you can tell them apart.

So we shall see if there has been a change in attitude or if it is just more BS.

Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: evgen.05 on August 19, 2019, 06:20:37 am
Video. PCB - is blue now.

https://www.youtube.com/watch?v=FaNvHQW_CsQ (https://www.youtube.com/watch?v=FaNvHQW_CsQ)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on August 19, 2019, 07:22:11 am
The jitter problem wasn't checked ... in the video  5MHz for the square wave is a frequency where the jitter is not present .
Same crappy power supply .
Same interface .
24Vpp = exactly 2x12V power supply rails  ;D ,
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 19, 2019, 12:50:58 pm
The JYEC DIP oscillator on that oscillator power board boasts a stability of +/- 0.1ppm over a a 0 to 25 deg C range and +/-0.2ppm over the -10 to +50 or 60 deg C range and, of necessity for this sort of accuracy and stability, boasts a trimmer to allow calibration against a reference frequency source such as a GPSDO.

 I've attached a photo of the oscillator board - it's now going spare, perhaps I can flog it as a CD player upgrade to some audiophool ;)

these Chinese TCXO has terrible jitter due to phase noise, because they are actually build on synthesizer. So this is not suitable for audiophiles at all :)

I tested one from aliexpress: https://www.aliexpress.com/item/32794136550.html (https://www.aliexpress.com/item/32794136550.html)

And I can clearly see synthesizer steps of frequency even with RTLSDR. That's a total shit with spurs each 2 MHz  :horse:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jleg on August 21, 2019, 10:18:17 am
FYI  I just sent service@feelelec.com an email asking that they replace the front panels for the 4 people I was able to identify who are forum members with borked V 3.0 units.  I was able to furnish shipping information for 3 of them.  I never heard from @canyon.

ah, so you did it again!  ;) - I was a bit baffled, when a few days ago somebody from "FeelElec" sent an email with "We know your FY6600 have some problems" - 18 month after i contacted them with the complaint! They also used an email address i never used with them, which was also a bit strange for me.
They wanted to have some photos (which i did already send 18 months ago), and now they want to send me "a chip which solves the problem". I will believe this when it arrived...  ::)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 21, 2019, 12:46:09 pm
It's a bit strange that I happened to read the thread and see the post from the new person at FeelElec.  I've generally not followed it much except to occasionally read Johnny B Goode's  posts.  When I saw it, I resent my old email to the new address.

I'll believe it when everyone tells me they  got the part and the unit is working, but maybe it will happen.  I hope they send an entire panel and not just the chip.  However, the new presence might simply be an EE at the company able to get some chips, but not able to get front panels approved by management.

I've been rather baffled by their behavior as there is clearly a good market for them if they simply improve customer relations.  And plenty of very fine engineering talent on offer for free.

Look at where Rigol is today relative to 10 years ago.  Their top line gear is definitely not hobby priced.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on August 21, 2019, 01:04:07 pm
I received the microcontroller with firmware V3.1 from Feeltech , as they said that will send for free if you ask . Thx .
I will change the IC these days .

(https://i.ibb.co/DR1GMny/Microcontroller-v3-31.jpg) (https://ibb.co/DR1GMny)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 21, 2019, 02:00:45 pm
that's the price for Chinese no name things... If you want guarantee and service, then buy known brands :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 21, 2019, 02:16:03 pm
I received the microcontroller with firmware V3.31 from Feeltech , as they said that will send for free if you ask . Thx .
I will change the IC these days .

(https://i.ibb.co/DR1GMny/Microcontroller-v3-31.jpg) (https://ibb.co/DR1GMny)

I was sent a complete front panel, but with V3.1 FW which was already out of date by the time I got it and which has a known issue.  The 6600 sits on the spares shelf with my Rigol DS1102E and similar gear.

I guess it's time for me to look at FY6900 reviews and see how thoroughly it's been tested.  I *think* I can measure every relevant parameter now.  And if not, I'll get what I need.  I'm suffering from a *very* bad case of TEA syndrome.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on August 21, 2019, 02:28:35 pm
To be clear , my unit is working fine with V3.0 , I didn't ask this for a repair .
I don't think FY6900 is better if you already got FY6600 . Just minor improvements for front panel butons .
What is the isue with V3.1 ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 21, 2019, 03:36:24 pm
The V 3.0 FW will corrupt itself completely borking the unit.   It can happen at any time.

https://www.eevblog.com/forum/repair/reflashing-or-resetting-a-feeltech-fy6600-signal-generator/msg1350260/#msg1350260 (https://www.eevblog.com/forum/repair/reflashing-or-resetting-a-feeltech-fy6600-signal-generator/msg1350260/#msg1350260)

It happened to mine just after I finished adding a 3 wire connector and grounding the BNCs.  I ran it for several hours, turned it off and went to bed.  The next morning it looked like the photos in the link above.

It happened to another person right after they had replaced the PSU, XO, and output amps.

IIRC, the V 3.1 will corrupt the sine wave, but that is recoverable.  You'd have to go back through to pages 15-20 in the thread for details.

I just watched the FY6900 video linked above.   It's pretty basic.  If FeelElec comes through with taking care of users with corrupted FW I'll have some very interesting posts as I have an 8560A, 8566B, 8648C, 5386A, GPSDO, 438A, 33622A and an Owon XDS2102A 12 bit DSO which will collect a 20 Mpt trace at 1 GSa/s.  The Owon will let me make some *very* sophisticated analyses using Octave.  I spent 30 years doing DSP in the oil industry.
Title: Re: FeelTech Service
Post by: kahe40 on August 21, 2019, 06:31:25 pm
FeelTech has created a service-thread not long ago,
maybe it is not known to all members here in this thread.


https://www.eevblog.com/forum/testgear/re-feelelec-fy6600-series-signal-generator-after-sales-services/ (https://www.eevblog.com/forum/testgear/re-feelelec-fy6600-series-signal-generator-after-sales-services/)


 :-+


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on August 21, 2019, 06:59:47 pm
The jitter problem wasn't checked ... in the video  5MHz for the square wave is a frequency where the jitter is not present .
Same crappy power supply .
Same interface .
24Vpp = exactly 2x12V power supply rails  ;D ,

 Actually, since you need a jitter free reference, using 5MHz for the triggered channel whilst applying a small mHz frequency offset on the other channel, was exactly the right way to perform this test.  :)

 However, it's quite obvious that he hasn't been reading this forum thread otherwise he wouldn't be (rightly, however) obsessing over the glass fuse and the abuse of a ribbon cable wire stolen from the connection between the PS and main boards (you could actually see where the grounding wire had been chopped from the main board end of this ribbon cable connector) to link the ground to the safety earth connection on the C14 socket to the detriment of the common rail connection's increased inductance and the needless introduction of a low impedance grounding loop via the mains earth wiring.

 In view of the 24Vpp claim in the 0 to 5MHz frequency range, it's very surprising to see the continued use of a nominally +/-12v supply. At an absolute minimum, considering the 1.2v maximum 'headroom' figure for a THS3491 (I'd expect similar headroom figures for the THS3002i and THS3095 opamps), you'll need a minimum of +/-13.2v to achieve a 24Vpp capability, with preferably +/-13.5 to 14 volt rails to provide a small tolerance margin. I had expected to see the use of a PSU board with a nominal +/-15v output to satisfy the 24Vpp specification.

 Surprisingly, Feeltech have simply repeated the same grounding sins perpetrated in the FY6800 rather than properly address the issue of mains leakage and grounding loops with a 1 to 10KR "drain resistor" connection to the safety earth in the C14 connector. This does beg the question as to whether they've also wasted the opportunity to replace the 86R attenuator pad with a proper 50R pad. In view of this earthing bodge, I suspect this ridiculous "Skoolboy Howler" still remains unaddressed.

 Apropos of which, I still haven't gotten round to having another go at addressing this issue with my now venerable FY6600-60M generator. I'm still "In Recovery" from my last brain bursting attempt to come up with a new BOM for a 50R attenuator pad which currently sports an impedance of ~45 ohms since my last attempt to correct this particular annoyance - a little closer but still no cigar. >:(

 I see BangGood are now selling the 60MHz version for just £81.08 which is little more than I paid for my FY6600-60M just over nine months ago. Whilst it offers very little more than its predecessor models, it's a bargain for any cash strapped hobbyists looking to buy a cost effective signal generator with the bonus that virtually all of the modifications and upgrades that apply to the FY6600 and the FY6800 models still apply.

 Even the half mains live leakage suppression with a 10KR 'earth drain resistor' mod that so neatly solved this issue in the FY6600 without introducing the spectre of tens of millivolts of DC offsets and other assorted earth loop induced interference whereby, as with the FY6800, all the brute force and ignorance approach of swapping the C8 connector for a C6 or C14 mains socket has already been applied, leaving just the addition of a 10KR and some remedial work on the PS to Main board ribbon cable connector to be implemented, would be worth doing.

 One other thing I did noticed in that video was that the rear panel cooling fan location had not been populated with an actual fan. Presumably this will be an optional after-market add on. I suppose there's some consolation in that at least such an end user improvement won't be requiring the use of a hole saw and drill to modify the case in order to upgrade the cooling provision from almost none to barely adequate.  :)

 Feeltech do seem to have kept the home hobbyist who revels in such home improvement projects in mind with this "toy signal generator", leaving as they do, so many loose ends for the enthusiast to tidy up post purchase. Considering its price point, is that really such a bad thing?  >:D

JBG

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on August 21, 2019, 10:18:54 pm
As for both yours and DaveR's view that there's no need to fit a cooling fan if either a more efficient smpsu is fitted or else an R type transformer is used for an analogue PSU replacement, I feel I must point out that you're overlooking the fact that both the FY6600 and Fy6800 models were already running uncomfortably hot before any additional heat sources were introduced into the box.

 The 25W rated smpsu might be cooler running from its point of view but the fact remains that its efficiency at a relatively low loading may be no better than the crappy original and quite likely adding a little more heat into the box. R type transformers in an analogue PSU aren't the problem, it's the waste heat from the analogue regulators that poses the real threat. R transformers are a good way to go but I'm not so sure about the analogue aspect unless it's being used to eliminate the high frequency ripple of a switching psu with consideration to the penalty of additional waste heat this introduces.

I have to admit being rather puzzled by your statements about "running uncomfortably hot" initially, Johnny, as neither my 6600 nor my 6800 has ever run anywhere near a temperature I'd describe as hot.  "Moderately warm" is how I'd describe it, but perhaps it's a subjective assessment?  The biggest source of heat, by far, after I did the PS mods in the 6600 was from the 7805 regulator, which got to around 75C and created a local hot spot on the top of the case, but I cured this by swapping it for an OKI 78SR regulator, which runs as cool as the rest of the PS.  Any heat inside the case now comes from the Cyclone chip and the 3095 op amps, but even then I need to run them very hard for a couple of hours (something I've only done once, as a test) to get them to an elevated temperature.  (In real world usage I rarely use more than about 1Vp-p output, so everything stays very much cooler.)  In the same test the D75J TCXO had no problem in coping, with only a 0.1Hz drift at 10MHz after the first 10 minutes of warm up, and no drift after the next 15 minutes - pretty much in line with what you'd expect from an OCXO, depending on the level of sub-Hz accuracy you want.

I still haven't bothered to modify the 6800's PS or op amps even though I've had all the parts to do it since I bought the generator about a year ago - the D75J is the only change I've made, as the awful drift caused by the original XO just had to go.  The distortion produced by the original op amps is minimal at the levels I use, so I can live with them, and they run cooler than the the 3095 upgrades so heat produced in the case is even less than that in the 6600.  Looking back, the 6600 mods were done more for the challenge than out of necessity, but the 6800 works well enough as it now stands, so I'll probably wait until they do become a necessity before I do anything else to it.

Finally, it's nice to see you back Arthur, and thanks for the update on your mods!

Regards,
Dave

 Hi Dave,

 Apologies for the delayed response but that was the day me and the XYL started a ten day cruiseship holiday and it's taken me two and a half days to catch up with my TV recording schedule (downloading and converting the iPlayer downloads for future viewing rather than actually watching them!) and sorting out ebay problems with a couple of sellers (including hgfurniture2018's failure to successfully ship that bargain FY6600-60M I'd paid £40.41 for two months ago in spite of a second attempt (allegedly) to ship me another one).

 The problem with the FY6600 is that the ventilation slots do very little as far as passive cooling is concerned, even to the extent that tilting it up on its bail makes the situation a little worse. In essence, most of the heat escapes via conduction through the plastic case rather than a more desirable exchange of interior air with that of the cooler ambient air.

 This means that the interior air has to absorb the heat dissipated by the components to raise its temperature sufficiently to warm the plastic casing to set up a flow of heat to the outside surfaces in order for the ambient air to conduct the heat away. All these additional thermal gradients between the actual semiconductor junctions generating the heat and the outside thermal environment result in much higher component temperatures than would result from a modest flow of cooling air produced by even a small (50mm square 10mm deep) 12v cooling fan running off the 5v rail.

 A simple solution to improving the passive cooling would be to upend the generator to stand it upon its right hand side where the case orientation would provide a chimney effect to speed up the thermo-siphon induced flow of the interior air to improve this transfer of heat to the outside surface of the case (with perhaps some small boost of exchange of air between the interior and exterior of the case). However, the improvement would still be rather marginal for the inconvenience involved, making the addition of a cooling fan the clear winner.

 When I remembered that I actually possessed an IR thermometer and used it to check component temperatures, I found that the smd XO ic was running at 50deg C and the three nearby LDO voltage regulators running at 70deg C. The FPGA showed 50deg C as did the base of the heatsink. Since, out of necessity, I had to take these readings with the lid removed, I've no doubt these temperatures would have been a lot higher again in normal use (possibly another 10 to 20 degrees higher but I still don't possess a suitable thermal probe to measure with the lid in place).

 I've no doubt that my initial attempt to raise the 12v rails above the 11.7v mark by boosting the 4.97v to 5.49v was adding to the heat stress via the LDO regulators (probably by another 5 deg C) exacerbating this issue a little but even so, a slight 5 degree drop in temperature would still leave the innards on the wrong side of the 50 degree mark with regard to component service life (notably the electrolytic caps which are short enough lived to begin with).

 A cooling fan seemed to me an essential necessity, especially when considering that, in the interests of frequency stability, it would likely be spending more time powered up than powered down (good from the point of view of reducing thermal cycling stress induced fatigue but bad for the service life of the caps).

 When I do finally get hold of a suitable temperature probe, I won't be in the least surprised to see something like a 15 to 25 degree drop in internal air temperature between fan running and fan stopped test conditions.

 In the interim, I have the fact that before fitting the fan, I could detect three notable hot spots, two on the top of the case (PSU and heatsink locations) and one on the underside (heatsink location) the top two of which have now disappeared with the underside one now downgraded to a warmish spot to indicate the effectiveness of my fan cooling upgrade.

 I have been rather mindful of the need for quiet efficient effective cooling since before the turn of the century when building desktop PCs. It's all too easy to overlook the fact that temperature gradients can accumulate alarmingly high temperatures at the heat sources (typically semiconductor junctions with limits no higher than 125 deg C in most cases) if care isn't taken to minimise the intermediate thermal gradients.

 I marvel at how unventilated smpsu wallwarts manage to cope using conduction via internal air to pass heat to a plastic thermal conductor to the outside surface actually exposed to the cooling room air which is why I have so much confidence in their longevity when I salvage their innards for use inside of a ventilated case as an auxilliary psu such as the half amp 12v smpsu board I'm using to power the OCXO in my FY6600 generator (a grand total addition of another 1.3W to the heating load within the box).

 It's all too easy to overlook the importance of effective cooling, especially when adding such items as replacement analogue PSUs with their own critical cooling requirements to an existing box full of electronic components regardless of all the empty unused space within just crying out to be filled with all that analogue psu goodness.

 Many have fallen foul of the 7805/7812/7912 regulator's thermal requirements but I see, now that I've googled "OKI 78SR", that you've discovered  a rather neat solution (90.5% efficiency!).  :)

 JOOI, have you measured the ripple noise output of this dc-dc converter substitute for the classic 7805 yet? I've got a similar dc-dc converter module on order from BangGood which claims less than 30mVpp ripple which I'm hoping to use in my very first basic GPSDO. It was part of an order totalling well below the 25 quid point at which you get free expedited delivery so is on a slow boat from China meaning it may be a few weeks before I get the chance to test its ripple noise performance. I've also got a step variable voltage dc-dc module in that order which made no mention of ripple noise performance which I'd also like to test.

 I rather suspect that despite some level of ripple noise in these dc-dc modules, they'd be a good compromise between the high ripple noise of an efficient mains voltage smpsu and the lower noise of an analogue R type mains transformer psu based on these converters in place of the classic 7805 type regulator.

 At the very least, such a solution should eliminate the direct radiation from the high voltage switching in a conventional cheap mains voltage smpsu from polluting the analogue circuitry of the signal generator either directly or via common mode conduction to the main board's low level voltage connections. The ripple noise of a dc-dc converter module should be easier to filter out than any common mode noise injected by a high voltage switching chip. However, whether any of this has any basis in fact remains to be seen but I do have high hopes that this turns out to be case.

 As for the need to modify any of these signal generators, it does, as you point out, rather depend on the use you plan to put them to. For audio use, they'll be fine as they are, especially if you invest in a decent external 50 ohm 20dB attenuator with perhaps a further selection of attenuation steps allowing you to avoid the internal 86 ohm attenuator pad for voltages below the 500mVpp mark, eliminating the risk of noise from the psu leaking past this built in attenuator onto the BNC outputs.

 Although audio signals are typically carried on notionally 600 ohm circuits (balanced or unbalanced) or simply passed from a low impedance source into a high impedance sink, it's still desirable to stick with a 50 ohm attenuator pad, if only for the sake of consistency. If impedance matching is important, a simple resistive matching pad can take care of that at the volt level since there's plenty of surplus voltage swing available to compensate the additional loss of such a matching pad.

 As I see it, all of these signal generators will benefit from the addition of a cooling fan and the suppression of the half live mains voltage leakage with a 1 to 10K "static drain" resistor connection to the protective earth on a three pole mains socket, neatly avoiding the ground loop issue. If nothing else is required, these two modifications are, imo, essential prerequisites for a long service life and protection from the ESD risk posed to any devices under test.

 A virgin FY6600 requires the most effort to complete these two mods, the FY6800 is already blessed with the required three pole mains socket for the leakage suppression mod leaving just the cutting out of a hole to accommodate a cooling fan whilst the FY6900 needs no such gross mechanical modifications, blessed as it is with both a C14 mains socket and an unpopulated fan aperture on its rear panel which I guess was just an incidental feature of the case Feeltech had bought in (I rather doubt they specifically asked for it).

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 22, 2019, 12:07:27 am
Here is a picture of a zoom-in on a 1 kHz 20Vpp sine wave. The scope scale is 10 mV/100nsec per division. One can see steps of 7.5 mV every 120 nsec, as expected for a 8192 points sine wave. So the vertical resolution ends up being 2666 levels or about 11-12 bits.
[attach=1]
I am not sure if this is a limit of the FPGA or if one could make a longer waveform with firmware changes.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 06:47:53 am
One can see steps of 7.5 mV every 120 nsec, as expected for a 8192 points sine wave. So the vertical resolution ends up being 2666 levels or about 11-12 bits.

Did you used 50 Ohm pass through dummy load on the oscilloscope input? Without it you will see random amplitudes. If it properly terminated, then full scale is 10 Vpp, not 20 Vpp, because FY6600 uses invalid "HiZ" units.

So, if this picture taken with properly terminated 50 Ohm, then:

10 Vpp / 7.5 mV = 1333

It means that there is just 11 bits DAC.

Such thing may occurs because some Chinese manufacturer used DAC902 instead of DAC904. It has the same pin-out, but it is more cheap and has 12 bits resolution instead of 14 bits.

It may be because manufacturer trying to get more money by selling cheap things, or it may be because DAC chip supplier provided fake chips (for example remarked DAC902 instead ofDAC904)...

You must be very careful and check all the details when you buy something on the Chinese market.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 07:16:13 am
Here is a picture of a zoom-in on a 1 kHz 20Vpp sine wave. The scope scale is 10 mV/100nsec per division.
FY6800 on a sine wave is about the same result 12bit
On the ramp signal, the resolution is 14bit
In the first case, the sine pitch is 4mV, in the case of 1mV ramp
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 07:26:27 am
That's very interesting. It looks like FY6800 uses 12 bit NCO to generate sine wave.

Can you check it on different sine wave frequencies (with different rise time), for example 100 Hz and 100 kHz?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 07:34:57 am
That's very interesting. It looks like FY6800 uses 12 bit NCO to generate sine wave.
Can you check it on different sine wave frequencies (with different rise time), for example 100 Hz and 100 kHz?

think the DAC is 14 bits, but the bit depth limits software.
Yes, I measured the value of the step at different frequencies of the generated sine 10 kHz, 1 kHz, 100 Hz, it does not change

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 07:46:51 am
So the real resolution for sine wave is just 12 bit :)

14 bit NCO requires more FPGA resources, and probably doesn't fit into EP4CE6, so they decided to limit resolution with 12 bit instead of use more expensive EP4CE10 or EP4CE22
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 07:57:04 am
So the real resolution for sine wave is just 12 bit :)
The Chinese are cunning, it’s good that they didn’t slip 10 bits. :horse:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 22, 2019, 08:34:37 am
It's a good idea to test an up-ramp. For 8192 horizontal points one gets 8192 vertical points. So the vertical resolution should be 13 bits in this case. Here is the picture for an up ramp on FY6600. The scope resolution here is 5 mV/100 nsec per division. The steps are indeed about 2.4 mV=20V/8192. So the DAC is not at fault. It is the number of points in the waveform that is creating the steps.
[attach=1]
This is not purely FeelTech limitation. Rigol and Keysight are also limited to some (although lesser) extend by the waveform length. https://www.eevblog.com/forum/testgear/new-rigol-16-bit-function-generators-dg800900-series/msg2452248/#msg2452248 (https://www.eevblog.com/forum/testgear/new-rigol-16-bit-function-generators-dg800900-series/msg2452248/#msg2452248)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 08:55:00 am
The steps are indeed about 2.4 mV=20V/8192. So the DAC is not at fault.

10 V / 2.4 mV = 4166, it's very close to 4096. So, it seems like 12 bits. With 12 bit you will have 2.441 mV step.

Do you measure it with 50 Ohm terminator on the oscilloscope connector? That's very important.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 08:58:28 am
It's a good idea to test an up-ramp. For 8192 horizontal points one gets 8192 vertical points. So the vertical resolution should be 13 bits in this case.
Yes, I was mistaken when I switched the waveform to ramp, the amplitude became 10V instead of 20V. Thus, it is not 14, but 13 bits, which are limited by the amount of memory.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 22, 2019, 08:59:45 am
No, there is no 50 Ohm terminator and it is not needed. It would simply attenuate both the signal and the steps by a factor of 2. The scope is calibrated for Hi Z load, so 20V pp is indeed 20 Vpp without terminator.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 09:02:26 am
No, there is no 50 Ohm terminator and it is not needed. It would simply attenuate both the signal and the steps by a factor of 2. The scope is calibrated for Hi Z load, so 20V pp is indeed 20 Vpp without terminator.

such measurement is incorrect. With Hi-Z your oscilloscope will show you random amplitude, you cannot believe it.

100 ns step uses about 10 MHz bandwidth, at >10 MHz you can get very high amplitude mistake on 1 meter cable with HiZ input.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 09:07:50 am
With Hi-Z your oscilloscope will show you random amplitude, you cannot believe it.
Do not invent, everything is correct, it shows without a terminator.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 09:15:55 am
With Hi-Z your oscilloscope Do not invent, everything is correct, it shows without a terminator.

No. With no terminator, there is 1M +15pF impedance on the cable end.

It means that your cable works as impedance transformer with random transformation ratio. In simple words, your 1 meter cable works as step-up or step-down transformer with random and unknown transformation ratio.

Since we-re talking about 100 ns steps, you're needs to take into account 10 MHz bandwidth. But since each step has square waveform, actual signal bandwidth is much more higher than 10 MHz. It's about 100-1000 MHz.

So, you can assume unterminated measurement just as random value... You cannot believe amplitude measurement at the end of transmission line with no proper termination.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 09:22:20 am
No. With no terminator, there is 1M +15pF impedance on the cable end.
Since we-re talking about 100 ns steps, you're needs to use 10 MHz frequency.
I can set a time step longer if I use a low frequency and it will not change anything.
In addition, the inclusion of a 20 MHz bandwidth limit also does not spoil the signal, just steps with a longer front, but they can also be seen with the same vertical step.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 09:27:28 am
pantelei4, since there is no proper impedance match, this is measurement at the output of transformer with random transformation ratio and random frequency response. It's transformation ratio will depends on many factors, include cable length and frequency.

All what you know, is that all amplitudes on your oscilloscope will be scaled with random factor which also depends on the frequency. So, there is no way to measure amplitude in correct way with no proper termination at the end of transmission line.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 09:36:53 am
since there is no proper impedance match, this is measurement at the output of transformer with random transformation ratio and random frequency response. It's transformation ratio will depends on many factors, include cable length and frequency.
The level of quantization will not change.
Can show you the vertical step of a linearly increasing signal with a frequency of 1 Hz? |O
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 09:44:20 am
Can show you the vertical step of a linearly increasing signal with a frequency of 1 Hz? |O

I suggest to avoid 50-60 Hz and 0...100 Hz range, because some oscilloscopes have amplitude distortion at such frequency.

I think 1000 Hz will be good enough. So, the time interval between steps should be about 1 millisecond.

But anyway, proper 50 Ohm termination is a better and much easier way to get proper amplitude measurement. :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 09:46:51 am
I suggest to avoid 50-60 Hz and 0...100 Hz range, because some oscilloscopes have amplitude distortion at such frequency.
I have a Rigol and it works correctly, and not like your Siglent.  :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 09:50:54 am
I have a Rigol and it works correctly, and not like your Siglent.  :-DD

yeah, but who knows, may be Rigol has another issue...  :D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 09:55:55 am
may be Rigol has another issue...  :D
Of course there is nothing perfect.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 10:22:50 am
I added some pictures on how to connect signal generator to measure amplitude properly.

This is strongly required if you want to know real amplitude value instead of random. Don't confuse, this is not just a decrease in amplitude by half. This is the only way to know real amplitude with no random scale factor.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 10:29:31 am
I added some pictures on how to connect signal generator to measure amplitude properly.
For whom?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 10:43:26 am
For whom?

you already know that. But many peoples trying to use direct connection of signal generator to the oscilloscope with no impedance match and have measurement issues because of that. And they don't know how to connect signal generator for proper amplitude measurements So I think it will be useful information for these peoples :)

Even people who knows that, often forgot it and make measurement mistake :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 12:35:47 pm
Thus, the JDS6600 with a memory length of 2048 points has only 10 bits of resolution on the sine and 11 maximum on the ramp. Unfortunately, I can’t verify this, because I broke it against the wall. :horse:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on August 22, 2019, 12:38:47 pm
For whom?

you already know that. But many peoples trying to use direct connection of signal generator to the oscilloscope with no impedance match and have measurement issues because of that. And they don't know how to connect signal generator for proper amplitude measurements So I think it will be useful information for these peoples :)

Even people who knows that, often forgot it and make measurement mistake :)

This is not impedance "mach" , just loading the signal at the scope input with 50ohm or whatever lowish ohm value will eliminate some of the the probes impedance effect . But of course you can't use 10x attenuation , the signal is too low .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 01:38:58 pm
scope input with 50ohm or whatever lowish ohm value will eliminate

No, the only way to get correct amplitude is to use exactly the same input impedance as your cable impedance. If you use 50 Ohm coax cable, you're needs to use 50 Ohm terminator. With any other value, for example 30 Ohm or 70 Ohm, amplitude will depends on frequency and cable length, so you cannot believe it. :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 22, 2019, 01:39:19 pm
A 50 ohm source connected to a 50 ohm cable connected to a 1 meg ohm input is going to have a reflection coefficient of 0.9999.  With most of the output reflected back into  the source, it will be severely distorted.

A 50 ohm terminator on a tee will work OK up into the middle HF region, but as you go higher the reflection from the stub going into the scope will become an issue.  To avoid that, buy some 50 ohm thru terminations.  The Chinese BNC ones I bought are actually quite decent and good to over 1 GHz.

If my 20 GHz SD-24 sampling head arrives today and works properly I'll add some scope traces to this post later.  I'll be setting up to test SMA-F to N-F adapters, so little effort to substitute a BNC tee & terminator and a thru.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 22, 2019, 03:07:05 pm
All of this transmission-line considerations of cable impedance and load impedance matching apply only if the cable is long enough to be a transmission line, which means its length is comparable to the wavelength of the wave. With light speed on the order of 1 ft/nsec one doesn't need to worry about impedance matching for a 3-ft cable and 100 nsec pulses.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 04:18:44 pm
Here is difference with different cable length, source is 10 dBm:

Blue - through 0.15 m cable
Yellow - through 1 m cable

[attachimg=1]


The same cables, the same signal, but with 50 Ohm input:

[attachimg=2]

Here is direct connection through BNC-BNC adapter (cable length 0.01 m):

[attachimg=3]
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 22, 2019, 05:02:51 pm
Thanks. Try the same for a sine with f=10 MHz, the difference will be smaller. Also would be interesting to look at square pulses. There will be some ringing on the transitions, but the flat regions will not be affected.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 06:03:36 pm
Thanks. Try the same for a sine with f=10 MHz, the difference will be smaller. Also would be interesting to look at square pulses. There will be some ringing on the transitions, but the flat regions will not be affected.

Here we are, the same cables, square wave, rise time 1 ns.

Blue - 0.15 meters
Yellow - 1 meter

[attachimg=1]

the same with 50 Ohm input:

[attachimg=2]

And through BNC-BNC adapter (0.01 m):

[attachimg=3]

As you can see, the difference between 0.15 meters and 1 meter cable is 7.96 ns delay. It is pretty clear visible.

Also, as you can see, even with 50 Ohm input there is some small impedance mismatch. This is because this square wave has too wide bandwidth (more than 1 GHz or something like that) and my oscilloscope input has some impedance mismatch at about 1 GHz and above... (I'm using oscilloscope with 100 MHz bandwidth).

Square wave is too hard for my scope  :horse:



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 06:31:19 pm
Also, as you can see, even with 50 Ohm input there is some small impedance mismatch.
This is not related to the number and level of steps. The level of quantization remains the same, and if it can be seen, this is enough.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 06:45:28 pm
This is not related to the number and level of steps. The level of quantization remains the same, and if it can be seen, this is enough.

DAC works at 250 MHz, so there is about 1-2 ns rise time transition between two levels. Are you sure that you can measure voltage difference on this transition with no proper termination at the end of cable?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 06:52:42 pm
DAC works at 250 MHz, so there is about 1-2 ns rise time transition between two levels. Are you sure that you can measure voltage difference on this transition with no proper termination at the end of cable?
In order to see, a low frequency is selected, for example 1 kHz or even lower.
The quantization level is a constant voltage signal, the RF bandwidth does not matter.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 07:06:04 pm
pantelei4, but these quantization levels are changed with rise time about 1-2 ns. It doesn't depends what frequency you selected, because DAC sample rate is fixed at 250 MHz. With any output frequency, transition between two quantization levels will occurs with fixed interval 4 ns and with fast rise time.

With low frequency you will get longer interval between changes. But how you know if this interval is one step 100 ns or 4 steps 25 ns? Since your cable doesn't have proper termination, short intervals may be overlapped with ringing in the cable and you will not be able to recognize short steps.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 07:15:18 pm
Since your cable doesn't have proper termination, short intervals may be overlapped with ringing in the cable and you will not be able to recognize short steps.
The steps will be long.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 22, 2019, 07:47:45 pm
pantelei4, just reviewed your screenshot, ok. I can agree, it looks like this is not the case when short pulse is hidden due to cable ringing. But who knows... Measurement with impedance match is more reliable  :)

So, FY6600 has 12 bit sine wave?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on August 22, 2019, 07:57:57 pm
So, FY6600 has 12 bit sine wave?
Yes.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 22, 2019, 08:44:12 pm
All of this transmission-line considerations of cable impedance and load impedance matching apply only if the cable is long enough to be a transmission line, which means its length is comparable to the wavelength of the wave. With light speed on the order of 1 ft/nsec one doesn't need to worry about impedance matching for a 3-ft cable and 100 nsec pulses.

The above is completely wrong.

Here is a 36 ps rise time, 10 MHz square wave displayed on a 200 MHz Instek MSO-2204EA with a 50 ohm source feeding a 1 M ohm input.  This is one of the excellent units sold by Leo Bodnar.  There is *no* cable, just a BNC male connector mounted on the board.

Aside from the appearance of the square wave I call your attention to the measured rise time shown in the lower left corner.  Nominally BW = 0.35 divided by rise time.

[attachimg=1] 

The second  image is the same source and same scope settings except that the source is now connected using a 50 ohm thru termination 1.5" long and the gain adjusted.  Again, note the measured rise time in the lower left.

[attachimg=2] 


Just for good measure here is the same setup but using a 100 ps pulse instead.  The scope is in dot mode with infinite persistence.  The narrower impulse is with the terminator, the wider is without.  I'd like to point out that the pulse is only 1/10th the I GSa/s sample rate of the DSO for the benefit of those who claim that you can miss a short pulse if your sample rate is not fast enough.

[attachimg=3]

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 23, 2019, 03:01:11 pm
rhb, in all your work in the oil business, have you ever worked out solutions to Maxwell's equations in a cylindrical waveguide with a center conductor?

What you are showing is not really relevant, you are looking at rise times of very fast pulses with a bandwidth way beyond that of the equipment used. So, the rise time and wiggles is just a function of the oscilloscope input stage ringing. It can depend on gain setting, quality of BNC connector, even how it is rotated. Plus, one shouldn't always trust automatic scope measurements, the difference in those rise times is not a factor of 2. And to compare pulse width, they should be made the same height.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 23, 2019, 03:18:46 pm
I suggest you find a good primer on the use of oscilloscopes and read it.  In particular the section on input impedance and bandwidth.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 23, 2019, 04:40:05 pm
rhb, in all your work in the oil business, have you ever worked out solutions to Maxwell's equations in a cylindrical waveguide with a center conductor?


Just for the record, the last time I solved that was 40 years ago when I went back to school to get an MS in geology after taking a BA in English lit.

The class average on the Physics II (EM) final was 45.  I had the highest score, 89.  I derived the solution to a complex capacitor problem from first principles during the exam.

That's the only grade I ever got I truly cared about.  And that was because some twit sitting next to me in class, after hearing I had a BA in English lit,  remarked I'd never pass because  "This is where they weed out the engineers."   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 23, 2019, 05:26:38 pm
I suggest you find a good primer on the use of oscilloscopes and read it.  In particular the section on input impedance and bandwidth.
Good for you. But people who have PhD like to understand things at a deeper level than an instruction manual.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 23, 2019, 08:23:25 pm
I suggest you find a good primer on the use of oscilloscopes and read it.  In particular the section on input impedance and bandwidth.
Good for you. But people who have PhD like to understand things at a deeper level than an instruction manual.

ROFL!!!!  I was merely suggesting you learn to crawl before you try to walk.

I was paid to sit as judge and jury on Stanford professors and their students for several years.  I worked as a contract consultant and my client paid around $35K/yr for consortium membership.  I was sent to the annual meetings to make sure the work they did was worth the money.  There were others, but you probably have not heard of Mines or the others.

Clearly not a world you're familiar with.   I know you have a BS, but it's obviously not a Bachelor of Science degree, even allowing for the horrible degradation of academic standards.

Attached are photos taken of the same 36 ps rise time pulser on a Tek 485.  It needs a full cal run, but it's still very good, especially compared to the horrible step responses of DSOs such as the Keysight MSOX3104T I returned  or the R&S RTM3104 I had on demo. It just isn't up to my (or Tek's) rather stiff demands for a proper scope step response.  A full cal on one of these is a full day's work which is why it's not in full cal.  Adjusting the front end attenuators takes a couple of hours.

For the benefit of the youngsters, the 485 was *the* premier portable analog scope for many years and has a 350 MHz BW.  It also has both 50 and 1 M ohm input selectable by switch.  The sweep is set at 2 ns/div for both photos.

Rather than spoil the fun, I shall allow our "PhD" friend here to explain which is 50 ohm and which is 1 M ohm and why the 36 ps rise time square wave looks so different.  In this case, aside from gain adjustments, the only change is the input impedance setting.  My apologies to the old guys who realize I botched the gain settings relative to the 0% & 100% lines.

BTW  For the benefit of the more intelligent readers of this farce, Leo Bodnar supplies with each of his pulsers a plot from a CSA803A with either an SD-30 or SD-32 head.  The SD-30 is a 40 GHz,  8.75 ps rise time head.  The SD-32 is a 50 GHz, 7 ps rise time head.  I'm not sure which he used for my plot.  Leo only claims < 40 ps in his listings to allow for individual unit variations.  The laser driver he uses has a 21-23 ps rise time IIRC, so he also offers 3.5 mm and 2.48 mm versions with faster rise times, albeit at higher cost as the connectors are *much* more expensive.  A 1 MHz square wave version of his BNC pulser will give exceptional TDR capability for very low cost with whatever scope you have.  Leo very graciously will provide that instead of 10 MHz if you ask. I have 1 MHz & 10 MHz square wave units and a 100 ps impulse unit.  They are fantastic!

[attachimg=1]

[attachimg=2]
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: BU508A on August 23, 2019, 08:29:11 pm
I suggest you find a good primer on the use of oscilloscopes and read it.  In particular the section on input impedance and bandwidth.
Good for you. But people who have PhD like to understand things at a deeper level than an instruction manual.

Arrogance will not help you understanding why proper termination is necessary.
But maybe if you will have a look at this, then perhaps you will understand.
And if you want to discuss this topic with someone on your level, I can recommend Shariar from The Signal Path.
He is a RF expert and has a PhD.

First: introducing s-parameters, the basics:
https://www.edn.com/design/test-and-measurement/4437010/S-parameters-basics (https://www.edn.com/design/test-and-measurement/4437010/S-parameters-basics)

A paper from CERN:
https://cds.cern.ch/record/1415639/files/p67.pdf (https://cds.cern.ch/record/1415639/files/p67.pdf)

a more general article from Wikipedia:
https://en.wikipedia.org/wiki/Transmission_line (https://en.wikipedia.org/wiki/Transmission_line)

a nice usecase of not correctly terminated transmission lines, example by Rohde & Schwarz
https://www.rohde-schwarz.com/de/file/Distance-to-Fault_Measurements.pdf (https://www.rohde-schwarz.com/de/file/Distance-to-Fault_Measurements.pdf)

And here is the link to The Signal Path if you want to discuss this topic with a PhD and not some mediocre EEs.
http://thesignalpath.com/blogs (http://thesignalpath.com/blogs)

And just a last remark:
Every, really every transmission line MUST have a proper termination, otherwise it will fail.
This is more true, the higher the frequencies are. High frequencies means: fast square signals.
All the high frequencies are in the edges covered. The related topic is "Fourier-Analysis", explained here:
https://en.wikipedia.org/wiki/Fourier_analysis (https://en.wikipedia.org/wiki/Fourier_analysis)

HTH,

BU508A



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 23, 2019, 09:13:03 pm
No one argues that a transmission line needs termination. The question is what constitutes a transmission line. The general rule is that the length of the line needs to be comparable to the wavelength of the signal transmitted. That is why impedance matching only becomes an issue at higher frequencies (shorter wavelength).

I perfectly stand by the original statement:
All of this transmission-line considerations of cable impedance and load impedance matching apply only if the cable is long enough to be a transmission line, which means its length is comparable to the wavelength of the wave. With light speed on the order of 1 ft/nsec one doesn't need to worry about impedance matching for a 3-ft cable and 100 nsec pulses.
It has already been shown by radiolistener that changing impedance matching only affects the ringing on pulse transitions (which necessarily have much higher frequencies or shorter wavelengths), it does not affect the DC value of 100 nsec -long steps (apart from trivial factor of 2 attenuation). So if one only cares about those 100 nsec flat steps, there is no need for termination. 

Now as for rhb tests, it doesn't even involve a cable, just a direct signal connection as far as I understand. As was discussed on another thread (https://www.eevblog.com/forum/testgear/oscilloscope-input-noise-comparison/ (https://www.eevblog.com/forum/testgear/oscilloscope-input-noise-comparison/)), oscilloscopes often have different input circuits for 1 MΩ and 50 Ω signal paths, so the rise time difference is not surprising at all. I don't know about the details of Tek 485 input, only that the bandwidth is quoted as 350 MHz (50 Ω) / 250 MHz (1 MΩ) at http://w140.com/tekwiki/wiki/485. (http://w140.com/tekwiki/wiki/485.)

I am sorry for tweaking rhb, he just likes to brag about his credentials so much that I couldn't resist.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tinhead on August 23, 2019, 09:39:02 pm
I couldn't resist.

https://en.wikipedia.org/wiki/Idiocracy
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: BU508A on August 23, 2019, 09:45:33 pm
No one argues that a transmission line needs termination. The question is what constitutes a transmission line. The general rule is that the length of the line needs to be comparable to the wavelength of the signal transmitted. That is why impedance matching only becomes an issue at higher frequencies (shorter wavelength).


Nope. The general rule is, what the source "sees" when it is going to leave a signal. If you put a wire into thin air,
then it will see the impedance of free space, around 377Ohm. If the Impedance of the source is different from that,
which is mostly the case, then it will come to distortions caused by reflections. If you put a piece of cable with the
impedance of 50 Ohm to the source, no matter how long it is, then the source will "see" these 50 Ohms at first.
If the impedance of the source differs from these 50 Ohms, you'll have reflections, distortions etc.
That is why the impedance of the source should match the impedance of the transmission line, which is seen
by the source at first.
Assuming the transmission line is homogen all over and it hits the end, then the same will happen as at
the beginning.
Therefore: no matter, how your transmission line is looking, if you want to avoid reflection and distortion, then
you have to follow the rule:
impedance of the source = impedance of the transmission line = impedance of the target.
This is independet of the length.

For this reason we have antennas. They adapt the impedance of the source to the impedance of the target.
In ideal cases you have a SWR of 1:1 which means that nearly all of the energy coming from the source will
reach the target. No reflection. No distortion.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 23, 2019, 09:53:05 pm
This should really go to a different thread. But two questions come to mind. a) What is the impedance of your audio headphones "transmission line"? and b) If you design an RF circuit (below 1 GHz), does every node on it sees 50 Ohm?
   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 23, 2019, 10:07:13 pm
It has already been shown by radiolistener that changing impedance matching only affects the ringing on pulse transitions

my example is not the worst case for impedance mismatch. It's just random mismatch. So it cannot be used as example that the difference is not so significant.

For clarification here is impedance measurement of my oscilloscope 1M input:
- at 10 MHz = 57 - j884 Ohms
- at 100 MHz = 43.9 - j96.5 Ohms

As you can see, my oscilloscope input impedance at 10 MHz is not 1 MOhm, but 57-j884 Ohm. So, you're needs to take this into account.

And don't expect that your oscilloscope will give you the same impedance mismatch, because your oscilloscope may have different input impedance at 1 MOhm mode.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: BU508A on August 23, 2019, 10:15:30 pm
The rule is the same, but in this frequency range the distortion is very low. The main reason for this is,
that the source has usually a very low impedance and the target in respect a high impedance. If some energy is
reflected, it will be absorbed by the source.
Most of the audio equipement which uses unbalanced connections have a source and target impedance of 47kOhm.
But as I said, in this frequency range the "wrong" impedance of the cable doesn't really matter.

Regarding the RF circuit: no one said, that it must have an impedance of 50 Ohm. The only condition is:
source Z = transmission line Z = target Z. If the signal leaves the circuit one have to make sure,
that the impedances are adapted, for example by using a Pi-network.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 23, 2019, 10:15:53 pm

For clarification here is impedance measurement of my oscilloscope 1M input:
- at 10 MHz = 57 - j884 Ohms
- at 100 MHz = 43.9 - j96.5 Ohms
As you can see, my oscilloscope input impedance at 10 MHz is not 1 MOhm, but 57-j884 Ohm. So, you're needs to take this into account.
Hmm, interesting, how did you measure it? It seems a bit surprising. If it has ~50 Ohm real impedance wouldn't it attenuate signals by about a factor of 2? What happens if you go to even lower frequencies.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 23, 2019, 10:20:05 pm
Hmm, interesting, how did you measure it? It seems a bit surprising. If it has ~50 Ohm real impedance wouldn't it attenuate signals by about a factor of 2? What happens if you go to even lower frequencies.

I measured it with vector analyzer. As you can see it has 1 M at DC but with AC things going to be much more complicated, and this is not ~50 Ohm, note it has reactive component (about 18 pF). So, the things are much more complicated, because input impedance depends on frequency and mismatch effect also depends on cable length and cable impedance (because it is also not exact 50 Ohm)...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: BU508A on August 23, 2019, 10:22:09 pm
Hmm, interesting, how did you measure it? It seems a bit surprising. If it has ~50 Ohm real impedance wouldn't it attenuate signals by about a factor of 2? What happens if you go to even lower frequencies.

I measured it with vector analyzer. As you can see, this is not ~50 Ohm, it has reactive component (about 18 pF). So, the things are much more complicated, because input impedance depends on frequency and mismatch effect also depends on cable length and cable impedance (because it is also not exact 50 Ohm)...

Maybe a Smith-chart would help?  ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 23, 2019, 10:23:36 pm

But as I said, in this frequency range the "wrong" impedance of the cable doesn't really matter.
Yes, because the wavelength of the signals is so much longer than typical cable length.

If the signal leaves the circuit one have to make sure, that the impedances are adapted, for example by using a Pi-network.
Yes, "signal leaves the circuit" means it has to propagate some distance. But within a circuit where the distances are very small, one does not need to match impedance. That is why as one goes to higher (GHz) frequencies, the circuit building blocks become smaller and there are more strip lines connecting then. Whereas for 1-10 MHz frequencies, one typically only does impedance matching at the input and output.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 23, 2019, 10:24:45 pm
May be...  ;D But when you use proper impedance match, things will be much more easier :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 23, 2019, 10:58:47 pm
because the wavelength of the signals is so much longer than typical cable length.

you're also needs to take into account that usual coax cable has velocity factor about 0.6, it means that wavelength is almost twice smaller in the cable in comparison to the vacuum.

In the vacuum 1 meter wavelength is 299.8 MHz. But in the cable 1 meter wavelength is about 197.8 MHz.

Also you're needs to take into account double cable length, because reflected wave needs to move forth and back. By take this into account, 10 MHz = 29.98 m * 0.66 = 19.79 meters wavelength in the cable / 2 = 9.8 meters.

For 10 MHz, 9.8 meters is longer than 1 meter cable, but not so much...

For 50 MHz difference will be even smaller: 50 MHz = 5.99 meters * 0.66 = 3.95 meters in the cable / 2 = 1.98 meters. As you can see 1 meter cable is pretty close to 1.98 meters. So we cannot treat it as "much longer" at all... :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 23, 2019, 11:05:46 pm
Yes, I agree with this. 10 MHz is kind of borderline above which one has to start thinking about impedance matching and termination.

There was a discussion on some other thread if 10 MHz clock distribution requires proper 50 Ohm termination on each end. In principle, yes, especially since the cables involved are often fairly long. In practice, not always. Some instruments have 50 Ohm impedance for external 10 MHz reference input, others have higher impedance.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 23, 2019, 11:29:25 pm
From my experience with these BNC to alligator clip cables:
https://www.aliexpress.com/item/32822207220.html (https://www.aliexpress.com/item/32822207220.html)

the critical frequency is about 2-4 MHz, above that I can notice significant error. I tested it with low bandwidth sine wave. It doesn't means that there is complete fail, no. You can still see the signal, but above 2-4 MHz you can notice difference with properly matched cable.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on August 23, 2019, 11:51:49 pm
Some instruments have 50 Ohm impedance for external 10 MHz reference input, others have higher impedance.

I think it depends on how device using it. Some device may ignore distortions and even may be tolerant to jitter. But some devices may be very sensitive to external 10 MHz purity.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 24, 2019, 12:49:04 am
@ maxwell3e10

BTW What's the "3e10" supposed to mean? 

You seem very busy avoiding identifying and explaining my 485 photos.

Generally this thread has degenerated into a "3 Stooges" skit with an occasional straight man walk on.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 24, 2019, 12:54:54 am
@rhb, see reply #1994

3e10 is something relevant to this discussion.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 24, 2019, 03:50:45 am
Sorry, kid, but that's more trouble than you are worth.  I'm not going to play "hunt the wumpus" for a message number.  In the future, post a link and make sure it works.

The real question is the difference in the response of a 485 at 50 and 1 Meg ohm input impedance to a 50 ohm source impedance, 36 ps rise time, 10 MHz square wave.

Which is which and why?

Also sitting next to me are a 1.5 GHz LeCroy DSO with switchable input impedance and a Tek 11801 with four 20 GHz sampling heads.  I have in total 5x 20 GHz sampling heads and 2x 12 GHz sampling heads.  Those are *all* 50 ohms input only.  If you  read the datasheets for serious scopes you will find that above about 500 MHz, the input *must* be 50 ohms.  You think maybe there is a reason?

There are a *lot* of PhDs on this forum.  I've not observed any that put Dr, Wizard or anything similar in their user name.  The normal pattern is initials, name or some combination.  Real PhDs don't need to see  initials before or after a  name to recognize one.  The hallmark of a PhD is the tag line from Clint Eastwood's "Magnum Force". "a man's got to know his limitations".

The real ones do, the failures and frauds don't.  Knowledge is infinite.  Humans are finite.  Getting a PhD is about coming to terms with that. And understanding what to do when you don't know.

At least one friend of mine (Stanford SEP 1982) and I agree that it's an expensive luxury, but if you can afford it, a lot of fun.  I suspect that I could find quite a few more friends who agree.

As for you, I'm not too sure you could do a decent job of sweeping floors at NIST;  so much ego and so little to justify it.

Have Fun (somewhere else)!
Reg

And yeah, I'm not a *nice* guy.  I have this unplesaant habit of telling the truth whether people like it or not.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tomato on August 24, 2019, 04:10:40 am
You seem very busy avoiding identifying and explaining my 485 photos.

@rhb, see reply #1994

Sorry, kid, but that's more trouble than you are worth.  I'm not going to play "hunt the wumpus" for a message number.

His reply to your question is in post #1994. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: svetlov on August 24, 2019, 09:38:30 am
dear DaveR :) ! detailed photos could not find-probably one of the participants of the forum will want to do photos - so far there's only this video
https://www.youtube.com/watch?time_continue=763&v=FaNvHQW_CsQ (https://www.youtube.com/watch?time_continue=763&v=FaNvHQW_CsQ)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 24, 2019, 03:30:44 pm
Here is a photo showing, starting at the bottom, the reflection response for an 50 ohm BNC terminator , 50 ohm thru BNC terminator  and the 50 ohm terminator on a tee.  Display is 50 mV/div and 500 ps/div.

The scope BW is 20 GHz with an SMA-M to BNC-F cable.  What you see in the first horizontal division is the reflection from the BNC-F connector.

Points:

The thru shows a capacitive reflection as does the tee & terminator.  I don't have a 1 M ohm BNC termination, so the thru trace is not entirely accurate

The tee & terminator has a lot of ringing in the stub which is not terminated.  The spikes on the trailing edge are multiple bounces.   The tall ones are the open end of the tee.  The short ones are the terminator end of the tee.  The geometry doesn't exactly match the way a tee and terminator are used on a scope input, but it's pretty close.  To match the geometry better I'd have to use a different cable and that would change the BNC-F to a BNC-M  and change the time relationships as well.

From this one may conclude that the BNC terminator has a BW of about 1.5 GHz, the thru about 1 GHz and the tee and terminator about 650 MHz.  These are Chinese, but have been tested and bad ones discarded.

[attachimg=1]
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bitseeker on August 24, 2019, 04:31:11 pm
I've heard about the differences in terminators due to geometry, but it's neat to see it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on August 24, 2019, 09:05:12 pm
It would be good to start a thread on passive RF hardware: cables, attenuators, terminators, etc. At work I have a pile of cheap BNC cables and a pile of double-shielded Pasternack cables. For a critical signal its amazing how much difference a good BNC cable can make.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on August 24, 2019, 10:30:33 pm
I've been playing with my new toy some more.  It is beginning to appear that there is more variation in the Chinese stuff I'm using than in  the preceding thru vs tee & terminator comparison.  I can radically deform the trace by mashing on the male part of the connectors.

It's amazingly difficult to figure out how to get valid comparisons.  To really do it right I'd need a pair of BNC-F  1 M ohm input active probes with  50 ohm SMA-M outputs which went to 20 GHz.  That would let me look at what the scope would see.  My LeCroy DDS-125 goes to 1.5 GHz, but it's got 20% overshoot on a step which makes tests like this impossible.


https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/msg2640531/#msg2640531 (https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/msg2640531/#msg2640531)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Dbldutch on September 01, 2019, 11:04:14 am
A while ago I decided to upgrade and tune my rather old (30MHz Version 2.9) because I wanted to have a higher precision counter function.
After reading this enormous number of postings, with some very good information (thank you guys), I decided on three items.
The power supply, the oscillator and the driver opamps for the waveforms.
The latter two are easy and have been described various times.

The power supply has been talked about many times, with several options, but there are only a few examples for a replacement.
I decided to design a completely new supply, that would let me adjust the +/- 12V outputs to +/-15V as well.
Going through my parts collection, I picked a 24VA block transformer that I could mount on a protoboard. The transformer is a little heavy with 2 seperate windings of 12VA each, and an output of 15VAC. Both secondary windings are fused with 0.8AT PTC fuses. The primary has two seperate 115V windings. 

I decided to use simple LM317 and LM337 voltage regulators for both analog supplies. The only specialty is the circuit around the trimmers, because they are China quality, and therefore cannot really be relied upon. The worst case is when the runner looses contact, creating a much higher output voltage then you intended, and this could potentially blow up the FY6600.
For the digital voltages, I selected a simple DC-DC Buck convertor because doing that with normal regulators would create too much heat. I specifically did not want a fan, with all it's generated noise inside the box. I also used some parts from the old supply, specifically the line filter and the 5V choke.

My unit is intentionally still floating. This can be fixed easily with a BNC/USB connection to another instrument.

To reduce some heat hot-spots from the three on-board regulators, I added some sticky heat-sinks to them.

More information can be found on my blog: http://www.paulvdiyblogs.net/2019/09/upgrading-tuning-my-fy6600-waveform.html (http://www.paulvdiyblogs.net/2019/09/upgrading-tuning-my-fy6600-waveform.html)

Enjoy!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: StillTrying on September 01, 2019, 01:22:30 pm
The transformer is a little heavy with 2 seperate windings of 12VA each, and an output of 15VAC.

Why did you use 2 bridge rectifiers, with 2 matched secondaries I'd have made a center tap using just one BR.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 01, 2019, 05:05:05 pm
A while ago I decided to upgrade and tune my rather old (30MHz Version 2.9) because I wanted to have a higher precision counter function.
After reading this enormous number of postings, with some very good information (thank you guys), I decided on three items.
The power supply, the oscillator and the driver opamps for the waveforms.
The latter two are easy and have been described various times.

The power supply has been talked about many times, with several options, but there are only a few examples for a replacement.
I decided to design a completely new supply, that would let me adjust the +/- 12V outputs to +/-15V as well.
Going through my parts collection, I picked a 24VA block transformer that I could mount on a protoboard. The transformer is a little heavy with 2 seperate windings of 12VA each, and an output of 15VAC. Both secondary windings are fused with 0.8AT PTC fuses. The primary has two seperate 115V windings.

 The secondary winding voltages are specified for full load at the minimum mains voltage input limit so tend to be a little bit higher than you might expect when running on a light load at normal mains voltage. That "15v rms" may be more like 17v rms no load in practice which, after allowing for a generous 2 volt drop in the bridge rectifier and the 1.4 crest factor of an rms voltage for sine waves, would see the smoothing capacitor(s) storing a peak voltage close to the 22 volt mark which will likely drop to an average voltage around the 20 volt mark with an average current loading of 150mA when driving 50 ohm loads with a square wave peak to peak voltage swing of 24 with a 30mA 'vampire load' allowance.

 When the regulators are set for 15 volts under this condition, they'll have to dissipate 750mW each. At a 12v setting this increases to 1200mW each which is a significant amount of heat energy to dissipate via the unsinked tab of a TO220 device (free air dissipation for most TO220 packaged devices is typically 1.5 to 2 watts maximum @25 deg C ambient).

 That heatsinking you're going to use will be vital in (literally!) this case on account the ambient temperature within the case will be considerably higher than a mere 25 deg C (more like 50 deg but I still don't have a suitable temperature sensor to actually check this - that's just an 'educated' guess right now. It could be even higher in the absence of any active cooling - I have a small 50mm sq by 10mm deep 5 volted 12v fan fitted into mine which has made the two original hot spots on the top of the case disappear without trace.

 These dissipation estimates are rather conservative based on the information you gave and the actual, measured, values are unlikely to be less without the effects of drop out from supply ripple making its presence known (at least as far as the 15 volt option goes).

 It makes sense to use a switching type drop in substitute for the 7805 regulator (better than 90% efficient units with <30mV ripple at 1MHz or higher being cheaply available). As far as I can see, none of the logic ICs are powered from this 5 volt rail directly which is only used to feed the three on board LDO ICs (3.3, 2.5 and 1.8 volt rails iirc) so any switching ripple here is of no consequence. The other 5 volt rails (both plus and minus) are derived from LDO regulators fed from the +/-12 rails (via 8 volt LDO regulators istr) so are also immune to the ripple on this 5 volt psu rail.

 Given a modest airflow around the regulator heatsink (best to use a single large heatsink for both 12/15 volt regulators), this analogue PSU design should be reliable enough. Without the addition of a cooling fan, reliability becomes somewhat questionable (it was already questionable to start with without any modifications being applied).


I decided to use simple LM318 and LM338 voltage regulators for both analog supplies. The only specialty is the circuit around the trimmers, because they are China quality, and therefore cannot really be relied upon. The worst case is when the runner looses contact, creating a much higher output voltage then you intended, and this could potentially blow up the FY6600.
For the digital voltages, I selected a simple DC-DC Buck convertor because doing that with normal regulators would create too much heat. I specifically did not want a fan, with all it's generated noise inside the box. I also used some parts from the old supply, specifically the line filter and the 5V choke.

 As I've already hinted (and also in previous postings), I think it's a mistake to discount the cooling fan option. Although removal of the original PSU along with its own 2 watts contribution to the heat loading will compensate for the additional heat produced by a replacement analogue supply, you'll still see a net increase of waste heat raising the temperature within the box which not only isn't good news for the original components it's also counterproductive to keeping those analogue regulators at a safe working temperature even when well heatsinked.

 Unless everything else on your bench is passively cooled and totally silent to protect unusually sensitive hearing, I doubt you would find any objection to the barely perceptible whisper quiet noise of a small 5 volted 12v cooling fan which has proved in my case to be more than sufficient to drop the internal temperatures by a good 20 deg C. For all the cooling effect of those vent slots, particularly when propped up on its bail stand, you might as well seal them all up to prevent dust ingress and make it proof against liquid spillage accidents.
 

My unit is intentionally still floating. This can be fixed easily with a BNC/USB connection to another instrument.

 Which begs the question, "Why not fit a low impedance (1K to 10K resistor rather than the conventional 1 or 2M) "Static Drain resistor" between signal ground and the PE tag of a C14 socket?". You can buy filtered, switched and fused C14 connectors which will fit the back panel (along with some strengthening in that area of the flimsy fibreglass board used for the back panel) to replace the original C8 two pole connector (this is an FY6600, right?) which will save you recycling parts from the original psu (keeping it intact for use as a spare or to allow reversion to the generator's original state).

 This, for example:-

https://www.ebay.co.uk/itm/Male-C14-IEC-RFI-Filter-Flange-Mount-5-x-20mm-faston-Rated-At-2-4A-250V-ac/223637128377?epid=1905379730&hash=item3411cfc4b9:g:aeAAAOSwE5Vc6tiR (https://www.ebay.co.uk/itm/Male-C14-IEC-RFI-Filter-Flange-Mount-5-x-20mm-faston-Rated-At-2-4A-250V-ac/223637128377?epid=1905379730&hash=item3411cfc4b9:g:aeAAAOSwE5Vc6tiR)
 

To reduce some heat hot-spots from the three on-board regulators, I added some sticky heat-sinks to them.

Enjoy!

 I'm not quite sure what "sticky heat-sinks" are. Hopefully, if they're relying solely on a 'sticky glue' to secure them, the glue used won't be failing at temperatures less than 150 deg C. Also, three regulator heatsinks? The 5v dc-dc converter surely won't be in need of a heatsink (not at half an amp or less) and, in view of the possibility of outputting a 24Vpp square wave at mHz frequencies into a 50 ohm load, it would be better, as I've already mentioned, to mount both 12 or 15 volt regulators on a common larger heatsink to keep each individual regulator cool during the resulting protracted periods (seconds to tens or hundreds of seconds) that they could end up handling each half of such waveforms in turn.

 Incidentally, the circuit you've attached seems overly complicated to me, at least compared to a more pragmatic dc-dc converter alternative to the analogue regulator solution you're proposing. I rather think you're "making a rod for your back" with this upgrade project. Assuming it provides the hoped for benefit of eliminated switching noise (with the lid off, of course!), you may yet be forced to change your mind over the wisdom of keeping it "fanless".

 In view of the fact that only 5% or less of the input energy appears as useful signal power on the BNC outputs, it's worth taking a note of the mains input energy consumption (wattage) beforehand so as to compare this wattage figure to the new figure after completing your PSU upgrade exercise. The difference will represent the additional heat being dissipated within the box, giving you some indication of the magnitude of the thermal issues this upgrade will present you with.

 Most other contributors to this thread who've upgraded to an analogue PSU of their own design have recognised the need for a cooling fan but some have underestimated the cooling requirements, usually recognising just in time the need to fit a fan with one or two seeing the consequences where they've had to replace damaged parts when a regulator IC has failed, input to output short circuit, causing a massive overvolting event. You need to be very mindful of the potential thermal problems with such analogue supply upgrades so do take care.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 01, 2019, 06:33:24 pm
The transformer is a little heavy with 2 seperate windings of 12VA each, and an output of 15VAC.

Why did you use 2 bridge rectifiers, with 2 matched secondaries I'd have made a center tap using just one BR.

 Well spotted! ;) I missed that particular faux pas.  :-[ Not only would it have reduced the bridge rectifier count, it would also have avoided  a diode's worth of volt drop to boot. ::)

 The only time you'd see the use of two separate diode bridges like this is when you don't have a 79xx to complement a 78xx where the isolation of the two separately rectified and smoothed supplies allows you to use a 78xx for the negative rail (output pin to ground, common pin as the negative rail connection). I think the same trick can be used with the dc-dc regulators as well which can prove handy in view of affordable negative output and inverting output dc-dc converters seemingly being as rare as rocking horse shit on Ebay and Banggood.

 The most pragmatic solution to upgrading the Feeltech psu board to something less noisy would appear to be an analogue/switching regulator chimera. At a maximum power demand of just ten watts one could choose a 24VA 240v 50Hz mains transformer with a pair of 32v secondaries to drive buck converters capable of withstanding an input voltage of at least 48 volts to ensure you don't have to forego the 90 to 265vac universal mains voltage feature of the original.

 If you can get hold of a suitable "R" type, you can keep the losses down to that of the original switching supply or better meaning you don't have to squander any of the cooling fan benefit on preventing a conventional analogue PSU from burning itself out or cooking the main board and front panel components into premature failure.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Dbldutch on September 02, 2019, 03:46:14 am
Good question, I probably should have elaborated on that.

I used the two seperate windings of the transformer to my advantage and make it easier to create a single “star” groundpoint by creating two separate supplies. With center-tapped transformers it’s easier to create grounding issues when using perf or protoboard and not a real pcb. Initially, I was 't sure how I was going to create the negative supply. Using a positive (dc-dc) regulator would need a separate bridge. Another reason was that I could use full bridges and therefor smaller buffer electrolytes. Diodes are cheaper than good buffer caps.

The only connection of the two supplies is at the connector to the main board.

Thirdly, I wanted to isolate the high frequency noise that inevitabilly comes from the 5V DC-DC convertor away from at least the negative supply as much as possible.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Dbldutch on September 02, 2019, 04:07:46 am
Dear Johnnie,

In my humble opinion, you have been polluting this thread since about page 70 with your endless and repeating ramblings and rants.  :palm: I suggest you stop that. It’s not your personal thread and you are not nearly as good or skilled as you think you are to critique the work or ideas of other contributors and give us your lectures. As a minimum you should assume other people know what they are talking about. Be a bit more humble, and please, please be more brief!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 02, 2019, 07:43:48 am
Good question, I probably should have elaborated on that.

I used the two seperate windings of the transformer to my advantage and make it easier to create a single “star” groundpoint by creating two separate supplies. With center-tapped transformers it’s easier to create grounding issues when using perf or protoboard and not a real pcb. Another reason was that I could use full bridges and therefor smaller buffer electrolytes. Diodes are cheaper than good buffer caps.

The only connection of the two supplies is at the connector to the main board.

Thirdly, I wanted to isolate the high frequency noise that inevitabilly comes from the 5V DC-DC convertor away from at least the negative supply as much as possible.

Please take note that central tapp rectification with 1 bridge is full wave so you don't need bigger caps . You just used 1 more diode bridge unnecessary . The star ground and "isolation" from 5V buck converter could be made just as easily ...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 02, 2019, 03:59:40 pm
Good question, I probably should have elaborated on that.

I used the two seperate windings of the transformer to my advantage and make it easier to create a single “star” groundpoint by creating two separate supplies. With center-tapped transformers it’s easier to create grounding issues when using perf or protoboard and not a real pcb. Another reason was that I could use full bridges and therefor smaller buffer electrolytes. Diodes are cheaper than good buffer caps.

The only connection of the two supplies is at the connector to the main board.

Thirdly, I wanted to isolate the high frequency noise that inevitabilly comes from the 5V DC-DC convertor away from at least the negative supply as much as possible.

 Thanks for that enlightenment (and for your critique of my writing style). I must admit that whenever I dare to review my own scribblings, some of the more effusive of my postings do make me cringe a little - I think you may have a point. :-[

 Anyway, aside from the fact that a centre tapped bridge rectified transformer winding is effectively a full wave bi-phase supply to each of the positive and negative supply smoothing capacitors. you make a valid point in regard of minimising noise injection into the common ground reference point.

 It was just that, on the face of it, the use of separate windings and bridge rectifiers seemed a little unnecessary for a bi-polar dc supply. Obviously, there can be good reasons for such duplication. In your case, the issue of noise injection through a common grounding link between the ground point of a centre tapped transformer to a relatively remote grounding point on the regulator board, and in my case, contemplating a means to float a positive dc-dc converter regulator so as to connect it in reverse to the common ground point on the PCB carrying the other two conventionally wired +5 and +12 dc-dc converters.

 I guess when we're dealing with eliminating noise from a nice and quiet replacement PSU, your reason for the separate secondaries and rectifiers trumps 'convention' every time.  :)

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 02, 2019, 08:18:55 pm
If you are very worried about the 5V converter noise than you would choose a transformer with a separate winding for that ...

But , I use a linear regulator for the 5V rail + a dropping resistor and the power dissipation is not that big , it is doable . So , you are not bound to use a switching regulator .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 03, 2019, 10:47:06 pm
If you are very worried about the 5V converter noise than you would choose a transformer with a separate winding for that ...

But , I use a linear regulator for the 5V rail + a dropping resistor and the power dissipation is not that big , it is doable . So , you are not bound to use a switching regulator .

 That's a neat way to shed some of the heat dissipation burden off the regulator. Ideally you need to determine the maximum, worst case current loading on the regulator so you calculate the exact resistance value required to still leave a safety margin over and above the regulator's dropout voltage.

 Unless you're trying to design for a "Universal Mains voltage PSU" with a 240v 50Hz stepdown transformer that will still provide sufficient secondary voltage(s) at 110 volt input without manually switching a split primary between series and parallel, you might want to test at the lower mains voltage limit (216vac) and check the 100Hz ripple to ensure you still have a small (half volt or so) margin over and above the regulator drop out voltage. You can then calculate the resistance required, picking the nearest preferred value that's just less than this and select a resistor with a wattage rating to suit.

 Obviously, you can just make an educated guess, erring on the low side to be safe or, alternatively, just use a dc-dc switching converter to provide a fixed voltage to the regulator some 2.5 to 3 volts higher than its output voltage. If this trick is good enough for high grade commercial test gear, it should be good enough for these cheap signal generators. :)

 Having said all that, I don't think there's really any need to eschew the use of a switching regulator on the 5v supply since the only components which make direct use of this PSU voltage are the relays. From what I can see in the reverse engineered circuit diagram for the main board, the rest of the digital supply voltages all come from the three LDO regulators supplying 3.3, 2.5 and 1.2 volts. All the critical analogue supply voltages come from the +/-12v rails which only directly drive the high level THS 3xxx opamps, another 3.3v LDO regulator feeding the analogue Vdd pins of the DACs and the +/-5v LDO regulators feeding the OPA686Ns.

 If you're going to use a dc-dc converter for the 5v supply and ground return noise is a concern, you might want to rejig that 6 pin ribbon cable connector to route the 12v analogue supply grounds to the main board end of the connector independently of the 5v ground return (put the join as close to the main board connector as practicable).

 This ideal can only be fully realised when all three rails are fed from three separate transformer secondaries, each with their own independent bridge rectifiers and smoothing caps. If the +12v and +5v regulators are fed from a common rectified and smoothed supply, the best you can do here to is keep the common ground wire as short and as heavy gauge as possible.

 There was very good reason for doubling up on those ground wires in that overly long ribbon cable which Feeltech undid when they swiped one as a convenient way to provide a hard earthing connection to the C14's PE tag in the 6800 and 6900 models.  :rant:  >:D

 If you're going to go to as much trouble as building an analogue PSU to replace the smpsu board used in these signal generators, then you might as well do the best job possible or not at all imo. This means specifiying a high quality mains transformer with a 16VA minimum rating with a couple of 18v ac 300mA minimum rated secondaries and a single 8v 500mA secondary.

 If you're contemplating an OCXO upgrade you'll also need to make allowance for the additional 100 to 300mA at 12v loading typical of a warmed up OXCO which might best be served by a separate analogue PSU which will allow you switch the generator off completely but allow the directly connected OCXO supply to carry on drawing power whilst it remains plugged into a wall outlet.

 It will be difficult enough to find a mains transformer with all the required secondary windings let alone one with two 18v secondaries and a centre tapped 16v secondary that can be used to power 5 and 12 volt analogue regulators. Alternatively, you could choose a higher VA rated transformer with 500 or 600mA rated 18v windings and just hang another 12v regulator off the rectified and smoothed +20v output to power the OCXO[1]

 Using the front panel on/off button to put these generators into standby only saves a couple of watts at most, leaving it to consume some 5 to 6 watts in this state so there's good reason to keep that OCXO module powered up independently of the signal generator if possible since it's not only the matter of the three minutes or so warm up delay but also that of "retrace" that's at issue here. Of course, if you're going to add a socket for an external 10MHz reference, the issues of warm up and retrace pretty much go away.

[1] If, when you've managed to succeed in finding a suitable transformer from which to power everything, the thought of having an additional 5 or 6 watts going to waste in Feeltech's version of 'Standby' when the OCXO can keep itself nicely warmed up and on frequency without this 'help' is any cause for concern, you can always fit powerFET switches into the DC rails feeding the regulators and either repurpose the mains switch to control them or add another separate 'standby' switch to turn everything except the OCXO off (assuming the several hours long 60ppt 'warm up drift' after an overnight shutdown escapes your OCD attention - if it doesn't, I suspect you might prefer to forego such standby economy in your quest to achieve the best possible frequency stability out your OCXO investment  ;) ).

 TBH, the only reason I have such a facility at all is simply because I hadn't upgraded the psu to one capable of handling the extra load from my OXCO modification so had no choice but to add a small half amp rated 12v smpsu board which gave me the opportunity to wire it directly to the mains connections on the C6 mains socket, bypassing the on/off switch.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Dbldutch on September 06, 2019, 11:30:06 am
While playing with the Lars DIY GPSDO, I came across a funny problem that I have not found reported about the FY6600 yet.
https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/ (https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/)

I wanted to use the FY6600 to mimic the signals for the gps 1pps clock and the 10Mhz oscillator. I used ch1 set at 1 second pulses, and ch2 for 10Mhz pulses. The Lars circuit uses a HC390 counter to create 5 and 1MHz pulses. The 1Mhz pulse and the 1 pulse per second go the the inputs of a HC4046. the 4046 resolves the phase difference and shows that as a pulse relative the the phase difference on the output. I'm elaborating here, because I initially though that I could use the phase setting of the FY6600 to create a difference in the edges and observe the working of the circuit.

What I found was a continuous stepped phase shift between the channels.

After some diggin' around, I attached the FY6600 outputs directly to my scope and observed the same thing. This phase shift is a function of the FY6600.
My version is pretty old, V2.9 software and V1.41 for the main circuit board. I did modify the power supply, see an above post, and I upgraded the main clock to a D75J-050.0 part, which is a 1ppm precision part. However, both mods are unrelated to the problem I see.

Anyway, as long as both channels are within one decade of each other, the edges are aligned. However, when one channel is more than one decade apart from the other, there is a continues and stepped phase difference.

This can be easily reproduced on my unit:
Set ch1 to a 1 Mhz pulse, and set ch2 to a 10KHz pulse. Connect both channels to a scope with the same length BNC cables and trigger on ch2.

Set the scope timebase to 10ns and closely examine the phase of the two signals, they are perfectly aligned (if you used the same length cables  ::)).
As a test, use the phase adjustment (but also notice the funny behavior on 4, 7, 10 degrees, etc - also a bug?) Apart from the jumps, all is in order it seems. Set the phase back to 0.

Now set ch2 to 1KHz (or lower). Note the stepped drift of about 2 ns between the channels about every 5 seconds.
Set the scope timebase to 200ns and observe that the trace of ch1 seems to "walk" to the left of the screen continuously.
Next, set ch2 to 100Hz. Note the much faster stepping with larger jumps and at a rate of 1 second.

This effect is probably due to the way the FPGA is programmed.
Needles to say, this makes the FY6600 pretty much useless for these kind of measurements.

Can somebody with newer hardware and/or software confirm this behavior or point me to a post that already described/reported this?

Tks!

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pantelei4 on September 06, 2019, 01:56:59 pm
Can somebody with newer hardware and/or software confirm this behavior or point me to a post that already described/reported this?
FY6800
Yes, the generator cannot synchronize for multiple frequencies. Phase steps 4ns.
It cannot synthesize the frequency exactly, the jitter is also 4ns. He cannot divide the frequency by an integer and maintain synchronization. :horse:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 06, 2019, 02:28:08 pm
I see 4nS jitter for pulse wave at 2-3 sec . That's the code inside the FPGA , like the square wave jitter .
This "details" need a lot of coding work , that a small chinese company is unwilling/unable to do ...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 07, 2019, 12:31:21 am
I see 4nS jitter for pulse wave at 2-3 sec . That's the code inside the FPGA , like the square wave jitter .
This "details" need a lot of coding work , that a small chinese company is unwilling/unable to do ...

 This does raise the question as to whether investing in a more "Up Market" DDS based arbitrary wave generator would resolve this issue. Perhaps someone following this thread who happens to own such a more up market generator could oblige by repeating this test and report their results?

 JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 07, 2019, 01:00:56 am
Is a Keysight 33622A "up market" enough?

Give me the settings and I'll put the 33622A outputs and a GPSDO output on a 4 channel scope.  I know I can trigger my 200 MHz Instek and 1.5 GHz LeCroy, but I'm not sure about the Tek 11801 w/ a 20 GHz SD-26 sampling head.  It's a bit exotic and I'm still earning how to operate it.  Keysight claims less than 1 ps jitter for the 33622A  And I actually believe that claim.  Though the 11801 has too much jitter (4 ps) to actually test it.

I should note that if the clock chip in the F***Tech is not a fractional N device, it will have settings with much more jitter than others.  And even with fractional N devices there are still issues at certain settings. TANSTAFL.

Have Fun!
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 07, 2019, 04:24:04 am
"Up Market" for me  would be Siglent , Rigol ...  an expensive Keysight I'm sure doesn't have this issues .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: TurboTom on September 07, 2019, 10:31:38 am
...did some testing with the AWGs that I've got access to.
Settings:

Ch1 10MHz Square
Ch2 1Hz Square
"Phase Mode Coupled" if applicable

If the phase wasn't stable, I increased the frequency of Ch2 in decimal logarithmic steps until no phase walk-through was observable anymore.

Siglent SDG6000: Phase stable at initial settings
Rigol DG800/900: Phase stable at frequency ratios <= 1000:1 (i.e. Ch2 10kHz)
Rigol DG4000: Phase stable at frequency ratios <= 10e6:1 (i.e. Ch2 10Hz)
Hantek HDG2000B (crappiest thing I've got...): Phase stable at frequency ratios <= 10e4:1 (i.e. Ch2 1kHz)
Rigol MSO2000A-S, internal generator (surprise, surprise...): Phase stable at initial settings

Hope this information might help to enlighten the situation.

Cheers,
Thomas




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 21, 2019, 10:31:41 pm
Here is revision 0.7 of the bluepill software with the corresponding modified PC Software.
- The Modulation functions are now working
- The SPI write times are improved (bypassing the STM libraries and new specific 32bit write)
- The FPGA write protocol has been improved (The FPGA protocol allows not to resend the Control Register number when the last used was the same)
- The sweep functions are faster, because of the 2 previous points (now 6µs potential update time instead of 10µs)
- The calibration bug found by DaveR has been fixed

Enjoy and thank you for your feedback!

Edit: Should it be usefull, Modulation functions and Sweep functions can work together ...

Hi there!
Sorry for the long break but the last year has been quite hard … That's just life…

Here is revision 0.8 of the bluepill software with the corresponding modified PC Software.
This works with a FY6600 with  version 3.2 but this should also work with version <3.2, not with v3.3

All the existing functions of a FY6600 v3.2 are now integrated in this revision plus:
- Sweep on CH2
- Over voltage protection
- Variable load adjustment
- Manual output range selection
- Last config on startup available
- Factory reset function
- Amplitude, Offset + VCO-IN Calibration
- CH1 modulation, CH1 & CH2 sweep and measure are independant functions and can be activated simultaneously.
Thank you for your feedback!

If someone is also interrested in testing , the same version is also available for the front panel with keyboard and lcd function but all the views are not finished (Channels,  sweep, modulation and measure views are finished, system and configuration are still to be done).
All the functions are anyway available through the PC Software.

Although you don't need it, the bluepill version also works with a LCD, a keypad and an encoder but it is not 100% wired like the FY6600 so the binaries are not the same. If you have the hardware, you could also try the Bluepill with it (I would have to give you the modified wiring).

I have a FY6800 and a FY6900 waiting to be connected to the logic analyzer ;-)
The idea is to have at the end the front panel  software working with the FY6600, FY6800 and FY6900, idealy with the same FPGA version if possible...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 22, 2019, 07:50:56 am
This looks very impresive , you changed that shitty screen layout with many leading zeroes , better fonts  and so on .
 I have v3.1 , the firmware will work ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 22, 2019, 12:13:40 pm
I have v3.1 , the firmware will work ?
Yes it will. I tested it with flash eeproms v3.1 and V3.2.
It doesn't work with a V3.3 eeprom but as I don't have a V3.3 front panel, I can't see what changed in the FP-FPGA protocol for v3.3.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 22, 2019, 05:04:09 pm
Is this a cure for corrupted V 3.0 front panels?  It looks *very* nice. 

F***Tech sent me a V 3.1 front panel.  They are *supposedly* sending replacement '103 chips to other forum members  with corrupted units though I've not gotten confirmation yet they have arrived.. 

I've got an ST-Link V 2.0 and am about to jump into working on the nanoVNA FW.  If it is possible to load your front panel FW into a V 3.0 panel, I'll install jumper pins and try it out.  Adding the SWD pins would be much less work than swapping out the chip.

It would be really nice to see FOSS code that would allow other Chinese OEMs to clone the F***Techs and improve them.  It could not happen to a more deserving company.

Have Fun!
Reg

BTW if you use one of these as an RF source, checkout the nanoVNA.  But be warned, the groups.io list is like trying to drink from a firehose.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 22, 2019, 07:48:17 pm

Hi there!
Sorry for the long break but the last year has been quite hard … That's just life…


A big welcome back, fremen67 - it's been a long time since we last heard from you, and we've certainly missed your input!!

I'll need to get my brain into FY6600 mode again and dig out the STM programmer, but I'll certainly do what I can to help with the testing.  The new FP display looks to be a massive improvement in legibility!

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 22, 2019, 07:56:24 pm
Is this a cure for corrupted V 3.0 front panels?  It looks *very* nice. 

Yes it is but not only. The new firmware has been design to be fast from the beginning and all the functions handled by the front panel are supposed to work ...

If it is possible to load your front panel FW into a V 3.0 panel, I'll install jumper pins and try it out.  Adding the SWD pins would be much less work than swapping out the chip.

The version I posted is for the Bluepill board (connected in place of the front panel). The Bluepill version is interesting as it allows testing without flashing the front panel, plus it's easy to plug back the front panel to compare official/new firmware behaviour.
The version for the frontpanel is different as the wiring for the bluepill is not exactly the same (the bluepill has an onboard led for example). If you are interrested in testing the front panel version, I can post it. In the current version there is no buzzer, no soft power off and some views are still to be finished (configuration and system). Except from the GUI, the behaviour is the same as the bluepill version.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 22, 2019, 08:26:04 pm
A big welcome back, fremen67 - it's been a long time since we last heard from you, and we've certainly missed your input!!
Thank you for the kind words, that encouraging!

I'll need to get my brain into FY6600 mode again and dig out the STM programmer, but I'll certainly do what I can to help with the testing.
You are more than welcome. The first step would be to test the bluepill version to track bugs and compare behaviour with the stock firmware but if you want to go directly for the front end test, that's even better for me. I would be very interrested in having feedback on the GUI but I won't force you to reflash your front panel. Unless you swap the chips before, it's a one way trip.

The new FP display looks to be a massive improvement in legibility!
Thank you but that's only the visible part of the iceberg. I hope you will also like what is under the water  :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on September 22, 2019, 08:55:02 pm
Holly rotating potentiometers ;), @femen67 is back  :clap:, welcome back, I was really worried about you, some other forum members as well, is'g good that you're back and hopefully the hard times will stay away from you !!!

Also the new software looks really awesome, thanks for your hard work and sharing with the community    ^-^ !!!

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 22, 2019, 09:35:29 pm

The version for the frontpanel is different as the wiring for the bluepill is not exactly the same (the bluepill has an onboard led for example). If you are interested in testing the front panel version, I can post it. In the current version there is no buzzer, no soft power off and some views are still to be finished (configuration and system). Except from the GUI, the behavior is the same as the bluepill version.

I've got a V 3.0 front panel just sitting in a box and an ST-Link V 2.0 SWD programmer which I need to learn how to use.   So I'd be very happy to test your FW  on the old front panel.  I've also got a bluepill or two on hand.

My primary interest is in trying to improve low cost T&M gear so people don't have to wait until they are old to design and build radios as  hobby.  I'm not an EE so I never had access to T&M gear at work.  All I could ever do was *very* limited.  And mostly failed for lack of the needed gear.

If the F***Tech will sweep the HF ham bands and trigger a scope, then that, a $20 LCR-transistor tester, $10 DMM and a scope makes lots of QRP projects possible.  Throw in an RTL-SDR and a nanoVNA and it is radio geek heaven.

Have Fun!
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 22, 2019, 10:25:38 pm
I've got a V 3.0 front panel just sitting in a box and an ST-Link V 2.0 SWD programmer which I need to learn how to use.   So I'd be very happy to test your FW  on the old front panel.  I've also got a bluepill or two on hand.
Perfect! Here is the front panel firmware, also working with PC Software V0.8.
Have fun!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 22, 2019, 11:09:00 pm
fremen67,

Thanks, downloaded.  I'll try to test tomorrow if I find the panel without too long a game of hunt the wumpus.  And I figure out how to do it ;-)

I just installed the Atollic 9.3.0 dev suite on Debian 9.3.  I'm also going to install the Gnu tool chain and STM32Cube (or whatever it is called now).

I have been unwilling to post my comparisons of the FY6600 to the 33622A because F***Tech were such jerks.  I did not want to do anything to help their sales.  But the fact is, for many the FY6x00 is the best  option.  Now that we have alternative FW for the front panel, I'm not as reluctant.   The superb engineering work in this thread has made it an attractive target for cloning.  It's unlikely that the price can be lowered, but the quality and customer service can be improved.

At low signal levels such as what you have before the PA in a transceiver, my FY6600 and 33622A spectra are almost impossible to distinguish on an HP 8560A, a 50 Hz to 2.9 GHz spectrum analyzer.  And for the sake of being *really* rude, I have an 8566B which goes to 22 GHz,  high enough to challenge the 33622A ;-)

Welcome back from your travails.  May they never return.

Have Fun!
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 23, 2019, 01:37:54 am
It took me a while to track down my blue pill to FY6600 wiring loom, but now I've got everything together and v0.8 loaded, so I'll start testing the software tomorrow.  I don't really fancy swapping the STM32 chip on the FP for fun, so I'll leave the flashing of that until it absolutely needs to be done  ^-^.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 23, 2019, 02:24:54 am
Why does the chip on the front panel need to be swapped to flash it?  My understanding is that all that's needed is to connect to the SWD interface with an ST-Link programmer.

IIRC It's configured so that attempts to read it via the SWD interface will wipe the flash, but my understanding has always been that you could *load* new FW.  You just couldn't read what was there.  But unless you set that restriction when you loaded new FW, the new FW could be read back.

The major obstacle has been the lack of new FW to install.  And trashing a good front panel to test new FW made no sense.  At this stage I certainly would not reflash anything newer than V 3.0.  No sense breaking something that works until you know the replacement works.

If I've got this wrong, please point me in the right direction.  At this point I've read so much documentation for so many MCUs that I don't believe *anything* I *think* I *might* know.

Logically, I can't imagine that setting the STM read protection would make reprogramming impossible.  That would impose much too large a financial risk to an OEM for them to be able to use the feature.  If a bug were discovered midway through a production run, there would be no way to salvage the HW if it could not be reprogrammed via the SDW interface.

Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 23, 2019, 05:37:11 am
I think the code is protected , can't be copied , so if you have a working unit you would want to use another microcontroller to play with ... just in case you need to revert to the "original" firmware . Otherwise it would have been easy for people with bricked units to repair their firmware .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 23, 2019, 11:08:06 am
I think the code is protected , can't be copied , so if you have a working unit you would want to use another microcontroller to play with ... just in case you need to revert to the "original" firmware . Otherwise it would have been easy for people with bricked units to repair their firmware .
Exactly. If you flash the original front panel microcontroller, you can't go back.

Why does the chip on the front panel need to be swapped to flash it?  My understanding is that all that's needed is to connect to the SWD interface with an ST-Link programmer.

IIRC It's configured so that attempts to read it via the SWD interface will wipe the flash, but my understanding has always been that you could *load* new FW.  You just couldn't read what was there.  But unless you set that restriction when you loaded new FW, the new FW could be read back.
You are right, you are not obliged to swap the chip before flashing the front panel but we do not have the binary file from feeltech to flash back the front panel to the original firmware... if ever needed ;-)

And trashing a good front panel to test new FW made no sense.
When you have a complete spare front panel then this should not be a problem to test with the bricked one.

And trashing a good front panel to test new FW made no sense.  At this stage I certainly would not reflash anything newer than V 3.0.  No sense breaking something that works until you know the replacement works.
There is not possibility to upgrade a FY6600 stock firmware <= 3.2 with a newer one from Feeltech. These units are not upgradable unless you have the binary file from Feeltech and use an external programmer.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 23, 2019, 12:04:28 pm

 No sense breaking something that works until you know the replacement works.


Exactly.  As you seem to be the only one with the luxury of having a spare front panel to play with, Reg, we'll be counting on you for firmware testing.  There are a few more of us to debug the control software and blue pill board, without risk of uncovering a new "3.0" type glitch and ending up with a brick which needs delicate chip replacement surgery :).

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 23, 2019, 06:39:23 pm
Hi fremen67:

I tried to start the software testing today, but there appears to be a problem with the 0.8 blue pill hex file - it loads ok, but when the blue pill board is plugged into a USB port the PC throws up a "Device not recognised - a device ..... has malfunctioned)" message.  I can reload 0.6 and 0.7 hex files on the same board and they'll work fine, but 0.8 causes the error message again.  I tried four different boards and it's the same with each.  It wouldn't have anything to do with 0.8 being 3x the size of 0.7 would it (it does seem to be a very large jump in size compared with previous versions)?

Regards,
Dave

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 23, 2019, 09:06:56 pm
Hi fremen67:

I tried to start the software testing today, but there appears to be a problem with the 0.8 blue pill hex file - it loads ok, but when the blue pill board is plugged into a USB port the PC throws up a "Device not recognised - a device ..... has malfunctioned)" message.  I can reload 0.6 and 0.7 hex files on the same board and they'll work fine, but 0.8 causes the error message again.  I tried four different boards and it's the same with each.  It wouldn't have anything to do with 0.8 being 3x the size of 0.7 would it (it does seem to be a very large jump in size compared with previous versions)?

Regards,
Dave
This is completely normal. The code of the bluepill is exactly the same as the front panel version, the difference is that some I/Os of the front panel can't be used on the bluepill and are remapped for it. But if you connect them, it will handle the LCD, the keyboard and the encoder.
Almost all the I/Os of the bluepill are used now, including PA11 which is USB- signal, now used as an output to switch on the LCD.
For the test, you don't need to connect anything on the USB port of the bluepill.
Just connect the bluepill the way it was with v0.7 and it should work like this. Did you try?

Edit: just a picture to show what you could do with the current bluepill  firmware...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 24, 2019, 12:06:37 am
Just connect the bluepill the way it was with v0.7 and it should work like this. Did you try?

Yes, I did - I even reprogrammed the blue pill without disconnecting it from the FY6600 to make sure everything was the same for each BP level, but the v0.8 control software would do little or nothing.  However, I've now tried it again after rebooting the PC, and without the myriad of SDR radio programs and other stuff running in the background, and everything is working properly this time - so it's all systems go! (And now I know why it was throwing up the error, as the BP is effectively no longer a USB device with the latest firmware loaded.)

I've just given the Counter function a workout, and it's fine with AC coupling - within the limits of my FY6600, anyway.  The manual claims that the counter can measure up to 100MHz, but I remember from when I last tried it several months ago that mine wouldn't go anywhere near that.  Having tried it just now, it will only go up to 38.1MHz with a sine wave input, and 42.5MHz with a square wave, so I don't know whether this is just a problem with my unit or with the counter in general.  (That's actually a lot better than when running with FP control, when it falls over above 29.7MHz with any input.)  Has DC coupling via the Trig IN port been enabled yet?  I can't get any response after I select it, although it's hard to say whether it works under FP control anyway - it never shows a frequency, and the values it does show for Cycle, Width and Duty only rarely coincide with actual values.

A lot more to be done tomorrow, starting with the Calibration routines ....

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 24, 2019, 05:57:57 pm
Tremendous work Fremen,

In the case where the front panel is reprogrammed with your software will the internal usb provide the software functionality also , or is the bluepill controller still required ?

The new simplified gui looks clearer and  easier to read ,as well as giving  controls well beyond the standard FP setup ,
From purely a visual perspective I felt a little more curve at the edges of the boxes and soft key tabs on the screen might be more pleasing on the eye , thats all only icing on the cake in the end,

I have two working units , so I'm strongly weighing the options and considering rebranding my modded  fy6600 'Frementec'.
Does anyone know where the idiots guide to the programmer hook up is located at ?





Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 24, 2019, 08:11:36 pm
Has DC coupling via the Trig IN port been enabled yet?  I can't get any response after I select it, although it's hard to say whether it works under FP control anyway - it never shows a frequency, and the values it does show for Cycle, Width and Duty only rarely coincide with actual values.

A lot more to be done tomorrow, starting with the Calibration routines ....

Regards,
Dave
Yes the Trig IN counter works as well. I reached up to 104Mhz in the front input and 120 Mhz in the Trig IN input with a sine signal.

For measurement, the main work is done by the FPGA. The FP tells the FPGA what input to use and then checks on a time base when a value is available for reading.
The FP then gets Frequency or Counter depending on mode, gets also +/-WIDE from the FPGA and then do the maths for Period and Duty values.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 24, 2019, 10:59:06 pm
In the case where the front panel is reprogrammed with your software will the internal usb provide the software functionality also , or is the bluepill controller still required ?
You don't need the Bluepill when you reflash the front panel. And yes the USB connection on the rear of the FY6600 will work when connected to a PC with the PC Software.

The new simplified gui looks clearer and  easier to read ,as well as giving  controls well beyond the standard FP setup ,
From purely a visual perspective I felt a little more curve at the edges of the boxes and soft key tabs on the screen might be more pleasing on the eye , thats all only icing on the cake in the end,
I also like the curve at the edge of the boxes but I wanted the UI to be as fast as possible and drawing horizontal and vertical lines goes faster then drawing arcs… I will keep that for the end  :)

I have two working units , so I'm strongly weighing the options and considering rebranding my modded  fy6600 'Frementec'.
Does anyone know where the idiots guide to the programmer hook up is located at ?
That would be very nice! What versions do you have?

As for flashing the front panel, it is a matter of soldering a 4 pins header to JK1 (just under the 8 wires ribbon) and wiring  GND, JTCK and JMS to a ST-Link V2 programmer.
JTCK to SWCLK, JMS to SWDIO and GND … to GND. Keep the 2 ribbons connected as the power supply will come from them.
In short you switch on the FY6600 , launch the STM32-utility, click Target/Program&Verify,  select the .hex file and start!
You will find the software for the ST-Link here: https://my.st.com/content/my_st_com/en/products/development-tools/software-development-tools/stm32-software-development-tools/stm32-utilities/stsw-link009.html (https://my.st.com/content/my_st_com/en/products/development-tools/software-development-tools/stm32-software-development-tools/stm32-utilities/stsw-link009.html)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 24, 2019, 11:59:38 pm

Yes the Trig IN counter works as well. I reached up to 104Mhz in the front input and 120 Mhz in the Trig IN input with a sine signal.


I've worked out what the problem is now: the counter is not very sensitive and needs a fairly high input voltage, so if you feed the counter from one of the output channels the voltage will drop off as the frequency is turned up, and soon falls below the counter's threshold level.  The display and the Manual both warn about not exceeding 5V at the counter inputs, but what they don't state is that the level shouldn't fall too far below that, either, so the FY6600 effectively can't measure itself above about 30MHz.

It's been a bad day for testing, I'm afraid, as endless "events" stopped me from even getting started.  With luck I'll be able to stay clear of distractions tomorrow and get some good time in.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 25, 2019, 01:57:09 am
I have a version 3.2 15mhz ,

I have the St-32 programmer and software to hand  , I just need to solder in header pins and I can try running it up on the new UI  later today .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 25, 2019, 04:35:25 am
That flashed  fine for me , its up and running on 0.8 ,
PC Software clicked in nicely too ,
Only unexpected thing I found was pressing the encoder button defaulted  frequency to 10000hz and no longer changed  hz/khz/mhz .
I only gave it a quick visual check over so far ,I'll have another closer look in the afternoon .


 

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 25, 2019, 03:51:38 pm
I discovered the way the left right arrow buttons work while in wave select mode , to change bank from preset to arb thats a handy feature.

Everything just feels more snappy now with the new code , its not like the original s/w where the machine seems to have a little yawn before doing what its told , same can be said for the new pc front end software , when you change something on the pc screen theres no decernable delay in whats taking place in the unit itself.

One thing I've never liked much about the F'tec was the need to  press the channel button twice  in order to mute or switch on the output channels , if channel select(to top of screen)  and on or off could happen in a single key stroke it would be much handier for cueing and mixing the outputs for test signals or even if the unit was used in a musical context . 

So apart from the frequency select mode issue on the encoder push button  and the extra zero's that appear in front of the selected field which I thought were unessesary ,I cant fault one single other thing in the new UI , it has a definate edge in terms of intuitiveness of usage compared to Ftec 3.2 , I also like the way the parameters visible and available to modify changed depending on the waveform in use , it helped me focus better on the job at hand .

The new measure ,mod and sweep pages are a revelation compared to 3.2 , and full independent mod/sw  features on both channels  not to mention  my formerly 15mhz machine now goes up to 62.5mhz   :palm:
you have truly spoiled us sir !

The firmware  upgrade was easy , Id had the St32 programmer software on my pc before so once I got the header implanted,3 wires  and the driver clicked  in  ,once Id ok'd overwrite warnings , took about 30 seconds ,the machine rebooted itself , and it runs off the new UI without a glitch since. 




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: MikeLud on September 25, 2019, 04:23:30 pm
Fremen67,

Do you have an estimate when you will have a version that will work with a FY6800. I have a 60mhz FY6800 board version 1.7 FW V1.7.1. If you need help testing let me know. Also what LCD are you using with the bluepill.

Thanks
Mike
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jleg on September 25, 2019, 05:55:31 pm
As for flashing the front panel, it is a matter of soldering a 4 pins header to JK1 (just under the 8 wires ribbon) and wiring  GND, JTCK and JMS to a ST-Link V2 programmer.
JTCK to SWCLK, JMS to SWDIO and GND … to GND. Keep the 2 ribbons connected as the power supply will come from them.
In short you switch on the FY6600 , launch the STM32-utility, click Target/Program&Verify,  select the .hex file and start!
You will find the software for the ST-Link here: https://my.st.com/content/my_st_com/en/products/development-tools/software-development-tools/stm32-software-development-tools/stm32-utilities/stsw-link009.html (https://my.st.com/content/my_st_com/en/products/development-tools/software-development-tools/stm32-software-development-tools/stm32-utilities/stsw-link009.html)

I just flashed my bricked V3.0 - worked like a charm! Thank you very much for these efforts!
Still didn't get anything from Feeltech - i owe you a beer at least  ;)

Here's what i had before your cure, and what i have now:

[attachimg=1]



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 25, 2019, 07:49:00 pm
I discovered the way the left right arrow buttons work while in wave select mode , to change bank from preset to arb thats a handy feature.
I completely forgot to describe the new UI funtionnalities but it seems that you discovered them all by yourself...
For the others who do no have it in front of them:

Waves:
- First click on Wave button change to edit mode but does not change the current selection (big pain with the original firmare ...)
- Encoder +: change current wave to the next one
- Encoder -: idem for previous one
- Right Arrow: go to Arb1 wave
- Left Arrow: go to Sine vave
- Encoder click: end edit mode

Numerical parameters (frequency, ampl, ...):
- First click on corresponding function key change to edit mode
- Right, left arrows: select next or previous digit
- Encoder +/-: inc/dec selected digit
- Encoder click: select default parameter value (0V for Offset, 50% for Duty, 0° for phase, etc ...)
- Second click on corresponding function key end edit mode

Text parameters (sweep source, source direction, etc ....):
- First click on corresponding function key change to edit mode
- Right, left arrows, Encoder +/- : select next or previous choice
- Second click on corresponding function key: show possible choices for parameter on function keys for direct selection
- Encoder click: end edit mode

One thing I've never liked much about the F'tec was the need to  press the channel button twice  in order to mute or switch on the output channels , if channel select(to top of screen)  and on or off could happen in a single key stroke it would be much handier for cueing and mixing the outputs for test signals or even if the unit was used in a musical context . 
OK I will do it!

So apart from the frequency select mode issue on the encoder push button  and the extra zero's that appear in front of the selected field which I thought were unessesary ,I cant fault one single other thing in the new UI , it has a definate edge in terms of intuitiveness of usage compared to Ftec 3.2 .
I will change the behaviour of the encoder click when on frequency (revert to defaut value at the moment). It's in my todo list, before the rounded corners but after the system menu  ;)
As for the leading zeros appearing on edit mode, it has been done on purpose to ease digit selection but other solutions could be used later on (like adding zeros only to the right of the cursor).

The new measure ,mod and sweep pages are a revelation compared to 3.2 , and full independent mod/sw  features on both channels  not to mention  my formerly 15mhz machine now goes up to 62.5mhz   :palm:
you have truly spoiled us sir !
Thanks a lot for the compliments  :) (Sweep on both channels but modulation on channel 1 only as it is done by the FPGA...)

Some days ago I was on the idea to release only the bluepill version to test the functionnalities and now the front panel version is already installed on some units... I even did not finished to test all the programmed GUI functions. :scared:
You are the Indiana Jones of the FY6600 ! No fear!

I found and corrected yesterday 2 bugs in the version you have. The counter reset function did not work anymore and the encoder driver had some issues when activating a sweep function.
I will give you another version in some days.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 25, 2019, 08:09:07 pm
Fremen67,

Do you have an estimate when you will have a version that will work with a FY6800. I have a 60mhz FY6800 board version 1.7 FW V1.7.1. If you need help testing let me know. Also what LCD are you using with the bluepill.

Thanks
Mike

Hi Mike,
I have to focus on finishing the remaining menus (at least system menus) before switching to FY6800. The first step will be to analyze the protocol between the front panel and the FPGA to see the differences with the FY6600. I suppose that it will not impact a lot the new firmware (this plus some different keys on the 6800 front panel) but I can't be sure now. I will say one or two months... I will anyway do the modifications for the 6800 and the 6900 in parallel to same time.

The new firmware will be a big improvement for the sweep function of the FY6800 as they ruined it. Try this:
connect an oscilloscope and sweep a 0V DC wave from -1V to +1V at 0.01s or even at 0.1s sweep time. The ramp obtained is a disaster on my 6800 which is V1.6. May be different on the V1.7 but I have doubts.

In the meantime if you have a way to backup the flash eeprom on the main board that would be interesting for me.
The LCD that would work for the bluepill is a ILI9341 with SPI.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 25, 2019, 08:13:57 pm

I just flashed my bricked V3.0 - worked like a charm! Thank you very much for these efforts!
Still didn't get anything from Feeltech - i owe you a beer at least  ;)

Thank a lot for the feedback!
It is still in development but what about beeing involved in testing the firmware?  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fisafisa on September 25, 2019, 08:48:39 pm
Hi
Very good job!
Been reading for a long time until you disappeared.
Now I am very happy to see the project back online.

Any chance of releasing the source code?
I was mulling about porting it over to either a F7 discovery board I have with touch screen
or directly to a Raspbeery pi with a large screen.

In any case
Thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 25, 2019, 10:45:32 pm
I spotted some other slightly odd behaviour relating to the gate setting  and displayed frequency in measure mode , this also seemed to be having some effect on the pc softwares  stability. I also couldnt seem to get anything from the trig input on dc mode .

Please dont feel any need to rush an update on my behalf , all in its own good time will be fine ,
I have a second machine so Im quite happy to play guinea pig with the other .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on September 26, 2019, 02:26:42 am
It doesn't work with a V3.3 eeprom but as I don't have a V3.3 front panel, I can't see what changed in the FP-FPGA protocol for v3.3.

Hi Fremen67 and welcome back! I surely hope that you were just busy and nothing tragic happened.

How may I help to figure out V3.3 and what do I need? My FY6600 is V3.3. I don't have a logic analyzer but I do have a Rigol DS1054Z. Probably not enough, eh?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 26, 2019, 08:40:19 pm
I spotted some other slightly odd behaviour relating to the gate setting  and displayed frequency in measure mode , this also seemed to be having some effect on the pc softwares  stability. I also couldnt seem to get anything from the trig input on dc mode .

Hi soundtec - it's getting to be just like the good old days again, isn't it?

Try this and see if you can get your Trig IN working:  use your new FremTech 6600 box to send a 20MHz sine wave to the Trig IN of your 6800, and set the amplitude to just under 5v.  It should be measured ok on the 6800 counter with DC coupling.  Now increase the frequency to 40MHz, and the 6800 counter will probably not measure it.  Increase the amplitude until the relays activate and the 6800 will measure the signal again.  Go to 50MHz and the amplitude will need to be set to about 9.1v, and at 54MHz it will need to be about 18.7V.  Mine tops out at just below 56MHz, when the 20v amplitude limit is reached (although the RMS output level is still less than 5v, so still within the stated safe input limit on the 6800).  If you've changed the op amps on your 6800 you should be able to control it with fremen's software and test the Trig IN port on the FremTech (I can't because I still haven't changed the op amps in the 6800, so can't get anywhere near enough amplitude on the signal to activate the counter at anything over about 10MHz).

If you use the front input on the 6800 you should be able to send a two-cycle sine wave from the FremTech and check the counter up to >90MHz.  I've just done this on mine, and went up to 93MHz with 17.15v amplitude set (only 6.2v pp out, 2.1v RMS), so I could probably have got another 3 or 4 MHZ out of it before I hit the 20v limit.  Fremen must have a signal generator which can produce high RMS outputs to push the counter as far as he did.

What irregularities did you spot with the gate and software stability?  I'll see if I can replicate the problem here if you give me some settings to enter.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 26, 2019, 11:02:32 pm
Hi Dave ,

With a 1khz 5v square wave output to
dc/trig or ac  input to measure on the Frementec
Frequency display changes depending on which gate setting I use ,on 1S reads good ,10S reads 10khz  ,on 100S mode reads as 100khz. Also at power up gate reads 'Mode' not 1S 10S or 100S.  I just did the same test on Fy6800 and it properly displays 1khz on all gate settings .

My earlier issue with the Trig input was down to the patch cable .

While making adjustments to the measure panel on the pc I did get a couple of crashes where the program just closes after an error message .


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 27, 2019, 12:33:37 am
Were you seeing the wrong values on the front panel or the PC?  I haven't flashed my FP yet, but the PC software shows 1.000kHz, 1.0000kHz and 1.00000kHz, which is as you'd expect.

I've only managed to find one glitch so far, and that's on the Calibration Panel, when it does the same error behaviour.  It's looking pretty resilient and stable otherwise.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 27, 2019, 02:10:37 pm
Theres a few small changes required for the FP software to be working right , I believe the bluepill software is a little ahead in that respect . Fp adds the extra 0 like you see Dave ,but looks like it forgets the decimal point ,so the number looks wrong .

 I have an idea which might be a nice feature to add,

The abillity to arrange and automate a sequence of tones or arb waveforms  , that would be incredibly usefull for test purposes .
Rs232 is available ,would another usb to serial link connected to backpanel tx rx and gnd be the best way to go that way its entirely seperate from the internal usb used for the pc software . 

https://www.partsnotincluded.com/midi/how-to-send-receive-messages-over-serial/ (https://www.partsnotincluded.com/midi/how-to-send-receive-messages-over-serial/)
that might do it




Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jleg on September 27, 2019, 02:24:19 pm

I just flashed my bricked V3.0 - worked like a charm! Thank you very much for these efforts!
Still didn't get anything from Feeltech - i owe you a beer at least  ;)

Thank a lot for the feedback!
It is still in development but what about beeing involved in testing the firmware?  ;)

sure, hopefully this weekend i'll get to this, and try to dig a bit into testing...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on September 28, 2019, 04:38:06 pm
I loaded up the fy6600 serial protocall in open office calc ,seems to display nice ,but I havent a clue how it works ,

I saw the link to the guy who made WSPR the transmitter from the fy6600 ,
It seems like a way to automate the output of the generator would be really usefull for radio
http://www.arrl.org/files/file/QEX_Next_Issue/May-June2019/Steber.pdf (http://www.arrl.org/files/file/QEX_Next_Issue/May-June2019/Steber.pdf)
In this case a way to transcribe a text message into a waveform which is then uploaded to an empty slot in the Feeltech and schedualed for transmission at the next time interval,  all automatically ,

I did have some limited success with the with the serial to midi  I mentioned in my last post  ,
I was able  recieve a signal after power  on from the Feeltech via midi in my daw , but I dont know how to send a meaningfull control signal the other direction .  The idea of being able to use the feeltech in conjunction with midi and a sequencer seems to appeal to others as well .
For audio testing the excellent 'Room Eq Wizard' by John Mulcahy has a midi and serial connections tab , if it had the abillity to control a  generators output via serial  that would be nice .

I get the impression everything in the above wish lists is easily possible , all the hardware is there , the control protocall is there in black and white , its more like just hooking up the numbers in software .

https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/550/ (https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/550/)

He seems to have made his pwn dedicated remote

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aimc on September 28, 2019, 06:35:23 pm
This is all well known, but did you notice that (with proper termination of course) the generator's output declines from 10-60 MHz by about half (-6dBv)? I am talking about the FY6800 actually and want to use it as VCO expecting a flat response. I didn't go inside yet to measure directly at the DAC but I suspect there is something fishy going on at the amplifiers. Has this topic been discussed here or anywhere? Is there a "hack" available to fix this?

Thanks in advance
Lutz
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 28, 2019, 07:01:17 pm
I can't talk about FY6800 but an FY6600 is flat from 0 to 60Mhz ... maybe you did a simple mistake in your setup , it wouldn't be the first time in this thread  :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 28, 2019, 08:53:15 pm
This is all well known, but did you notice that (with proper termination of course) the generator's output declines from 10-60 MHz by about half (-6dBv)? I am talking about the FY6800 actually and want to use it as VCO expecting a flat response. I didn't go inside yet to measure directly at the DAC but I suspect there is something fishy going on at the amplifiers. Has this topic been discussed here or anywhere? Is there a "hack" available to fix this?

Thanks in advance
Lutz

What was the output voltage?  Check it at 1 Vpp.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aimc on September 28, 2019, 10:51:37 pm
Thank you for the reply. I did measure it again just now (see attachment) and yeah - well it has some ripple reaching around 2.5dBv (~0.75) at 60MHz (my former statement was a bit higher due to a mistake, sorry). Not sure if a 0.75 drop is acceptable for a function generator, but then again its a cheap product.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 29, 2019, 04:40:08 am
I don't understand what you're showing.

Is the sweep synchronized with the scope trigger?

Also please take a look at the PCB.  Is there any flux residue visible?  Flux absorbs moisture out of the air.  This results in an environmentally dependent parasitic capacitance.  It would not take much capacitance to  cause the drop in output you're seeing.

If you see any flux, clean it off with isopropyl alcohol and an old toothbrush and retest.  I've done quite a few repairs, including an HP 34401A which had been repaired previously that consisted of nothing but cleaning flux residue off the board.  The 34401A was completely non-functional until I cleaned it.  But after cleaning meets the factory spec.  It's the more accurate of my two 34401As.  The other one was a closet queen and saw very little use.

Have Fun!
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aimc on September 29, 2019, 04:31:43 pm
I don't understand what you're showing.

Is the sweep synchronized with the scope trigger?

Also please take a look at the PCB.  Is there any flux residue visible?  Flux absorbs moisture out of the air.  This results in an environmentally dependent parasitic capacitance.  It would not take much capacitance to  cause the drop in output you're seeing.

If you see any flux, clean it off with isopropyl alcohol and an old toothbrush and retest.  I've done quite a few repairs, including an HP 34401A which had been repaired previously that consisted of nothing but cleaning flux residue off the board.  The 34401A was completely non-functional until I cleaned it.  But after cleaning meets the factory spec.  It's the more accurate of my two 34401As.  The other one was a closet queen and saw very little use.

Have Fun!
Reg

Sorry, I did not describe the attachment. Well, essentially both images show a periodic ~0.5s sweep from 0.1-60MHz (left to right), one in the time and the other in the frequency domain. An yeah I triggered on the edge where 60Mhz jumps back to the higher amplitude 100KHz to keep the presentation stable (although I stopped it anyways later). The interesting part is in the envelope, which gets kind of jaggy, likely due to the sampling lag between the much finer FY6800 sweep increments compared to the scope acquisition speed. I can show that along the time axis the amplitude decline becomes visibly discretized into stair steps when you crank up the scope's front end amplification (not sure, but this also may saturate the amp, that's why I didn't show it).
The other screen shot shows the FFT of the FY6800 waveform during the same frequency sweep at much faster time base. Time base has to accommodate sufficient sampling to provide a decent time resolved FFT window, small enough to approximate it as a single tone at each time base sweep. Then, as the tone frequency slowly sweeps from acquisition to acquisition, with the FFT set up to keep only the maximum of the peaks you see a decent magnitude over frequency representation. This will take some time and acquisition sweeps until all maxima form a solid line. With the cursors set to the math output, you can quantify the roll of. When you compare both screen shots you see the expected similarity only different by the different log scale from the FFT (which I chose to show dBv units). The two representations also compare quantitatively pretty good within a reasonable margin of error.
Hope this explains my measurement steps.

I will have a look inside the AWG and look at the solder connections. Thanks for this advise :)

Regards
Lutz
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 29, 2019, 04:59:06 pm
I supose you have another generator that is linear as you want , otherwise you don't know where the problem is .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 29, 2019, 06:05:43 pm
I'll post a quick comparison of a Keysight 33622A and an F***Tech FY6600 with V 3.1 FW once I clean up a bit.

The 34401A is the most spectacular  example of the evils of flux residue. When it arrived, it just displayed random digits on all functions and ranges.  I opened it up and saw a 1 cm brown spot around where an LF357 had been replaced.  I sprayed it with 91% isopropyl alcohol and scrubbed it with an old tooth brush, checking with a magnifying glass to make sure I got everything off.  I then dried the board with a hairdryer.

When I powered it up it worked flawlessly and still meets factory spec on the 10 Vdc range checked against two very high quality LTZ1000 voltage references.

I've "repaired" several TV remotes, a CD player, DVD/VCR player and other things this way.  In the case of the CD player, I didn't get all of the residue off the first time.  About 6 months later it started acting up again ("NO DISC").  I cleaned it again using lots of alcohol.  Haven't had a problem with it again in several years.  I think the flux I missed was underneath the MCU chip.  The only residue on the board had been a small spot near one corner of the MCU.

The 91% IPA from the supermarket is not very pure, so blotting excess off with a towel is important.  Otherwise you will have s white film of something left behind.  You can see minute amounts of flux with a 5-7x magnifier by looking at the smoothness of a reflection from the board.  It's not uncommon for me to find that after an initial cleaning and drying.  If I see it, I do it over.

Have Fun!
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aimc on September 29, 2019, 06:26:49 pm
I supose you have another generator that is linear as you want , otherwise you don't know where the problem is .

No, not really - only a cheapo AD VCO development board that goes from 35M-4.4GHz. I do know the response of the scope (with and without probe) though and hope to find the problem with the scope only. Frequency range is rather low, so will try to tap in before the amp of the FY6800 if I find a good location to do so.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 30, 2019, 12:49:06 am
Here are a couple of screen shots.  The FY6600 V 3.1 sync output when sweeping it being swept :-(  Makes it  useless.  As a result, the only way to trigger on the sweep is the drop in output.

Sweep is 10 kHz to 60 MHz for the FY6600 and 1 kHz to 60 MHz for the 33622A.  Scope is an Instek MSO2204EA with 50 ohm thru terminators.  Signal amplitude is 200 mVpp.

First the 33622A.  Note that it has some signal drop as the frequency goes up.  Not sure what the culprit is.  I'll investigate.

[attach=1]

Then the FY6600 which has much more drop.

[attach=2]

I think the biggest FAIL is the sync signal not being the start of a sweep.  I spent some time trying to get proper synchronization on the F***Tech, but could not find a way to do it.  So I set a rising edge trigger on the signal at the 10 kHz end above the level at the 60 MHz level.

I bought the 33622A used from Keysight on ebay for 30x what the F***Tech cost. Older HPAK AWGs were so expensive on ebay that they didn't seem to make sense.  The 33622A goes to 120 MHz and is  quite amazing.  I bought it because my F***Tech was dead. F***Tech made promises but did not deliver.  My choices were more Chinese which did not fill me with great confidence or a 15 MHz HP for $500.  So I went with the 33622A.  I'm glad I did.  And glad I could afford it.

I've got an HP 8560A and a 438A, so I have other test options.  I'll see if I can use some of the other F***Tech rear panel inputs to synchronize the two AWGs and overlay the sweeps.

Have  Fun!
Reg

After I posted this, I noticed that the sample rates imply aliasing, so I'll need to examine that.  I suspect that sweeping over such a wide range into a DSO is not a good test.  So I'll try repeating with my Tek 485.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aimc on September 30, 2019, 03:25:38 am
That's interesting! Yeah the trig out of the FY does not make much sense for any sweep or VCO operation which kind of sucks. Otherwise it looks like you are getting similar results for the F...T brand while the Keysight seems much better. Your Keysight manual boasts with +-0.2dB amplitude flatness, so it better be. Looks like your time base and VCO sweep was faster than I did because your jaggies are bigger and you can't see that the response has a slight s-shape. A bit concerning as you say is the sampling rate in both our cases @60MHz. You used 5MSa/s and I used 20MSa/s which is grossly under sampled. However, it should not impact in the amplitude per say. If you have enough periods and non-integer multiple sampling points (you don't because you sweep) the lower frequency alias amplitude will at least be as high as the signal. This is covered by sampling theory. To demonstrate I repeated the experiment with 100MSa/s (I know its not >120MSa/s as it should be but close enough when using sinc interpolation, see aliasing in attachment "..no_SINC")  and found the drop being almost the same as with my former under-sampled post. For this reason alone I think the FFT method is likely better as you are using well oversampled small sweep-time pieces for each FFT. But there you have imprecisions with the windowing. So nothing seems better than the good old simple peak detector (or any new-fangled detector you can buy from Analog Devices).

If you don't trust me, you can try a higher sampling rate - but I think at the end of the day you measure the same drop...

Thanks and cheers
Lutz
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 30, 2019, 05:35:54 am
I have v3.1 , the firmware will work ?
Yes it will. I tested it with flash eeproms v3.1 and V3.2.
It doesn't work with a V3.3 eeprom but as I don't have a V3.3 front panel, I can't see what changed in the FP-FPGA protocol for v3.3.

Hello , I flashed a spare microcontroller with your firmware ... quick bug , in sinewave the output is badly distorted if I go up in frequency up to 197KHz . If I go back down from here is OK untill 1KHz or something when the distortion appears again . Something in comunication with the FPGA is not quite right .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 30, 2019, 06:29:19 am
I have v3.1 , the firmware will work ?
Yes it will. I tested it with flash eeproms v3.1 and V3.2.
It doesn't work with a V3.3 eeprom but as I don't have a V3.3 front panel, I can't see what changed in the FP-FPGA protocol for v3.3.

Hello , I flashed a spare microcontroller with your firmware ... quick bug , in sinewave the output is badly distorted if I go up in frequency up to 197KHz . If I go back down from here is OK untill 1KHz or something when the distortion appears again . Something in comunication with the FPGA is not quite right .

Hello, did you swap the microcontrollers?
I tested with my 2 FY6600s. One has a swapped MCU, the other has a bluepill… Sorry but I can't reproduce your problem  :-//
The sines are normal till 62.5 Mhz…
The MCU is not supposed to have an impact on sine output or shape. It just send the parameters to the FPGA when you change them but then no communication anymore with the FPGA.
Could you also test with an ARB sine (ARB1 if you did not change it otherwise you can create one and send it with PC Software).

Do others have the same problem? DaveR, Soundtec, jleg??

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on September 30, 2019, 06:36:24 am
Hi Fremen67 and welcome back! I surely hope that you were just busy and nothing tragic happened.
Thank you! Well... death is part of life… time eases things...

How may I help to figure out V3.3 and what do I need? My FY6600 is V3.3. I don't have a logic analyzer but I do have a Rigol DS1054Z. Probably not enough, eh?
You can do things with a DS1054Z but I am afraid the only reasonable way is the logic analyzer.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on September 30, 2019, 12:43:26 pm
OK , sorry about what I said , no bug , I forgot to connect a wire and the analog part wasn't properly powered . My FY6600 power supply is modified and uses a PWM signal from the microcontroller .
Yes , the original microcontroller is swapped with another one .

Just a sugestion , the frequency displayed is still hard to follow with just one decimal point when it is in MHz range for example ... I have to count allways how many digits are before the dot  ;D . Would be nice to display MHz , KHz and to move the point accordingly .

The sub-hertz many many digits ;D I think shouldn't be displayed when are not used ( set to 0 ) .

If you go to the max with the tens of MHz digit ( by error or not ) , the rest of the display goes to max also  and you lose what you have set , maybe you want 59.123456MHz . I think would be better not to let you go beyond 5 if 6 and the rest of the digits would be an invalid frequency .
When you go down in frequency the same thing happens if you reach 0 and turn the encoder one more time , the rest of the digits are erased to zero , I don't think this is desirable . Zeroing the display could be usefull , but with a long press on the encoder or another combination when you are in frequency adjustment .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on October 01, 2019, 01:08:59 am
I discovered that by generating a 2 kHz ramp on CH2 and feeding that to the VCO input on the back I can get a quasi-stable sweep by triggering off the ramp.  However, there is a *lot* of jitter in the FY6600 sweep relative to the ramp.

Here are the ramps produced by the 33622A and the FY6600.

[attach=1]

Next the sweep using the ramp input to the VCO input on the back of the FY6600.  The 33622A is the down ramp.

[attach=2]

Same thing but using the ramp from the 33622A

[attach=3]

The jaggies and banding are aliasing effects.

It may be that I can make some useful measurements of the F***Tech output using the nanoVNA.  I've never tried to measure the output impedance of an amplifier, so significant research needed.  But it certainly appears as if there is a shunt capacitance across the output.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: aimc on October 01, 2019, 03:08:11 am
Hmmm interesting, but now the drop is even deeper from the looks of it...??? Maybe the VCO mode has a different can of worms. Also 2KHz seems a bit fast for a sweep. Maybe the VCO can't handle it and/or it can but then the waveforms gets distorted within a single sine period depending on frequency? Haven't done the math on that... I know if you do it slower, the scope's sampling rate drops and you get aliasing, but as I said before the peak values of the aliases remain the same.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on October 01, 2019, 05:27:16 am
I suggest checking Feeltech linearity manually in 100KHz increments or how do you want , only with the generator connected to the scope .
For 0-60MHz linearity , the probe proper compensation is very important , not just that basic visual 1KHz sqarewave no overshoot , undershoot procedure . Unfortunatly a scope and probe is not that linear as we would want , it is not a RF voltmeter . A judgement could be made only if you have another generator you are certain that is linear .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 01, 2019, 12:19:31 pm
I noticed I needed a version of the original Feeltech software installed on the machine before Fremens would run  ,I had been trying out the latest FY6900 version pc software ,maybe this caused the issues I am seeing , I wonder is there a particular version of the Feeltech pc  software I should be using for maximum compatibillity to Fremen's FP code ,

I also saw the software Yves created for his Fy3224s ,theres several features  that looks very usefull , both to the radio enthusiast which its designed for ,but also would be very helpful for programming test tones or sweeps for audio or any other test purpose that comes to mind . The programable buttons to trigger arb waveforms from memory could almost turn the unit into the equivalent of a sampler ,might be of use to those who are looking to incorporate an arb gen in a musical context .

I tried a trial version of Ni labview to display the .VI file included with some of the Feeltech software packages , seems to make an attempt to copy the controls of the unit on screen but the  labels are garbled charachters ,there appears to be a control element missing from the Feeltech VI file as well.

I did also see RHB's post about the Fy6600 WSPR transmitter , the author of the article did create a basic VB code for control of the FY6600, so thats another thing Id like to try out.

I did have another think about the double button press being required  to select channel and mute/unmute  , maybe a nice idea would be when you initially depress the channel 1 or 2 button  have it select that channel to top if its not there already ,then let the unlatching of the button send the command to mute or unmute as required , now only a single press (and release) covers both functions , it  only logical  captain  Fremen >:D   


Many thanks for all the efforts .


 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on October 01, 2019, 07:30:43 pm
Can anybody post a csv file that is accepted by FT software, or fremen's software? I can't figure out the format. I'm trying to do a simple ASK modulation on CH1 from CH2 and anything I try will just return an error message and shut down the program.

Thanks,
Miti
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on October 01, 2019, 08:41:52 pm
It would be really nice to see FOSS code that would allow other Chinese OEMs to clone the F***Techs and improve them.  It could not happen to a more deserving company.

yeah, it will be great. If it will be released I will buy some FY6600 clone :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 01, 2019, 09:00:09 pm
I used Wavemanager plus to create a few compatible wave forms ,

 version 4.13 of the  program is included in the download for the 3224s here

https://drive.google.com/drive/folders/1hqqHqvfk1FKhzYSjJ-S6_SUTr_zx0fhp?usp=sharing

Ive been using version 5.8 of the Feeltech software , and so far find Fremens 0.8 is unusable with a 'run time error 380'
invalid property value, V 0.7 is usable but just for the basic channel functions .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 01, 2019, 11:14:08 pm
Can anybody post a csv file that is accepted by FT software, or fremen's software? I can't figure out the format. I'm trying to do a simple ASK modulation on CH1 from CH2 and anything I try will just return an error message and shut down the program.

Thanks,
Miti
Find attached a sine wave created with the modified PC Software 0.8.
This is the original FT format.
You can download it to a standard FY6600 or a modified FY6600 with PC Software 0.8.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 01, 2019, 11:34:10 pm
Just a sugestion , the frequency displayed is still hard to follow with just one decimal point when it is in MHz range for example ... I have to count allways how many digits are before the dot  ;D . Would be nice to display MHz , KHz and to move the point accordingly .
Thank you for the feedback.
Yes, as already written to sountec, this is planned. I will also add a thousands separator to ease the reading. This just a matter of prority.

The sub-hertz many many digits ;D I think shouldn't be displayed when are not used ( set to 0 ) .
Not sure this will look nice but why not...

If you go to the max with the tens of MHz digit ( by error or not ) , the rest of the display goes to max also  and you lose what you have set , maybe you want 59.123456MHz . I think would be better not to let you go beyond 5 if 6 and the rest of the digits would be an invalid frequency .
When you go down in frequency the same thing happens if you reach 0 and turn the encoder one more time , the rest of the digits are erased to zero , I don't think this is desirable . Zeroing the display could be usefull , but with a long press on the encoder or another combination when you are in frequency adjustment .
The behaviour your are describing is what I have on my RIGOL DP832 but there are much less digits on it… and I already find it painfull...
In your example, with 59.123456MHz, this would be a pain to set 60.000000MHz...
The behaviour I programmed is the one that was existing on the FY6600. It is also the behaviour of my RK8511 electronic load and my SIGLENT SDG2042X for the max limit.
I don't know if there is a standard on that matter …
What do others think?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 01, 2019, 11:57:27 pm
I noticed I needed a version of the original Feeltech software installed on the machine before Fremens would run  ,I had been trying out the latest FY6900 version pc software ,maybe this caused the issues I am seeing , I wonder is there a particular version of the Feeltech pc  software I should be using for maximum compatibillity to Fremen's FP code ,
I tried to stay compatible at the beginning with a standard FY6600 but I had to modify the original protocol for the new functionnalities. I don't know if Feeltech changed the protocol for the FY6800 or FY6900 but logically the FY6600 version should be the most compatible with the new FP. Not sure why you would want to use it with the new FP anyway...

I did have another think about the double button press being required  to select channel and mute/unmute  , maybe a nice idea would be when you initially depress the channel 1 or 2 button  have it select that channel to top if its not there already ,then let the unlatching of the button send the command to mute or unmute as required , now only a single press (and release) covers both functions , it  only logical  captain  Fremen >:D   
If I get you right, this would than be impossible to show CH1 for example if not displayed without changing CH1 output state …. the same for CH2.
The problem is that there are few buttons so we have to compromise … The problem is exactly the same with measure, sweep and modulation functions. One push on the button will show the view if not already displayed, another push will activate the function.
This is also now the standard way on oscilloscopes with common buttons for several channels: one push to select the channel or deactivate it if already selected. I don't say this is easy at the beginning but you get used to it :-//
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 02, 2019, 12:23:33 am
Ive been using version 5.8 of the Feeltech software , and so far find Fremens 0.8 is unusable with a 'run time error 380'
invalid property value, V 0.7 is usable but just for the basic channel functions .
That is strange, I have no problems sending waveforms to the FY6600 with the software …
The waveform file reading and editing  is a part that I did not change in the PC Software at the moment. This is still the orignal code and it might not be stable. I may have a look at it if needed.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 02, 2019, 01:27:48 am
The logic in the logic controls is an interesting question , seeing how its done in other popular equipment is definately a good way forward ,

Theres a question that came up before about the software catching up to changes via  the front panel , V0.7 had the update button , would it be possible for the FP to be programmed to send an equivalent update signal to the pc everytime  a value had been altered locally , it would  make sure two remotely located  opperators are reading the same true values from the instrument at all times .

0.8 Im not sure why its unstable . I'll look again tommorrow 


 



Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on October 02, 2019, 09:17:03 am
Hi fremen67 , the stand-by button is not working and the red led is allways on . I don't think I have shorts , the voltage on the microcontroller pin go to GND when the I press the button so it seems fine .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 02, 2019, 11:50:23 am
Hi fremen67 , the stand-by button is not working and the red led is allways on . I don't think I have shorts , the voltage on the microcontroller pin go to GND when the I press the button so it seems fine .

If you are interrested in testing the front panel version, I can post it. In the current version there is no buzzer, no soft power off and some views are still to be finished (configuration and system). Except from the GUI, the behaviour is the same as the bluepill version.

Correct, no buzzer neither at the moment.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 02, 2019, 12:13:52 pm
Fremen did warn us  both those functions remained missing from the firmware in an earlier post Cdaniel,

One thing Ive noticed on the unit with the flashed Fp code was what seems to be the sine displays corrupted both on the FP display and in software ,I'll have a closer look this afternoon .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 02, 2019, 12:36:28 pm
Theres a question that came up before about the software catching up to changes via  the front panel , V0.7 had the update button , would it be possible for the FP to be programmed to send an equivalent update signal to the pc everytime  a value had been altered locally , it would  make sure two remotely located  opperators are reading the same true values from the instrument at all times .
The refresh button is always there but moved to the configuration tab.
Synchronization is indeed an interresting subject.
The communication protocol is defined in a way that the FP only answers to external requests. This simplifies the protocol handling as from the PC side, your are only listening to the COM port after having sent a request. If you receive unsolicited data when waiting for a specific answer this would lead to false com errors, unless adding complexity to the protocol.

But yes the FP could have a flag available that the PC would read indicating that something that is interresting for the PC has changed.
Something that changes in the FP is not necessarily interesting for the PC (depending on the tab you are viewing, some changes may be relevant, others not), so that means extra coding in the FP. That also means extra load on the communication, extra load on the FP CPU.
The effort might not be worth the result. That is why I ended with the refresh button.
You are talkink about "two remotely located  opperators" but in the real life I guess this would be you and yourself  ;)
Before releasing the 0.8 PC software I was about to remove definitely the refresh button and replace it with a refresh on tab change. It is already the case for the calibration parameters or the configuration parameters that are read when you open the corresponding tab. If you want to force a refresh, you would change tab and come back. I think this is what I will finally do in the next release.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 02, 2019, 12:46:47 pm
One thing Ive noticed on the unit with the flashed Fp code was what seems to be the sine displays corrupted both on the FP display and in software ,I'll have a closer look this afternoon .

The corrupted sine bug is always present in the FY6600. I had it also with the new front panel so I think it might be in the FPGA code.
This is the sine wave itself in the flash eeprom that looses some points for whatever reason. It happened to me once and I just reflashed the eeprom. If your sine wave is really broken and if you don't have a way to flash the eeprom, I will add a function to the PC Software to refresh it.
The best way to know is to connect your FY6600 to a scope.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on October 03, 2019, 01:09:23 am
Find attached a sine wave created with the modified PC Software 0.8.
This is the original FT format.
You can download it to a standard FY6600 or a modified FY6600 with PC Software 0.8.

Thanks fremen67! So the secret was to rename it to .FY.
Just for fun, I made a DCF77 out of the FY6600. I have a radio controlled wall clock from when I was an European citizen.
Sure it doesn't sync in Canada so I wanted to play a bit.
I prepared an arbitrary waveform according to the DCF77 specs and I modulate a 77.5 carrier on CH1 with the arbitrary wave from CH2.
It works like a charm. I haven't seen that solid antenna sign in a looooong time. It tries to sync every ten minutes before the hour and then it gives up.
I'm thinking of making a transmitter that has a GPS receiver as a precision clock.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 04, 2019, 07:48:44 pm
Hi Miti - would you mind posting that Ch2 waveform you made?  I've got a weather station that hasn't been able to get a time fix from DCF77 for years, and it should help me do a quick diagnosis as to whether it's a receiver fault or just an antenna problem.  It will save me having to do a manual time correction every three months if I can fix it :).

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on October 05, 2019, 01:24:29 am
Hi Miti - would you mind posting that Ch2 waveform you made?  I've got a weather station that hasn't been able to get a time fix from DCF77 for years, and it should help me do a quick diagnosis as to whether it's a receiver fault or just an antenna problem.  It will save me having to do a manual time correction every three months if I can fix it :).

Regards,
Dave

I should have done it two days ago. I've attached it in the original post.
CH1 77.5KHz, 10V, CH2 3.66mHz (yes, mili Hz), 1V, MOD AM, Source CH2 with the arbitrary waveform, Mod-Rate 180%. You can try ASK as well.

Edit: ASK doesn't work, you may need different levels.
Edit1: It starts with 20:50 CEST Wed 02 Oct 2019 and it goes up to 20:53. It starts 20:54 but doesn't finish it.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 05, 2019, 03:16:10 am
Well, I've given Fremen's control software a good thrashing over the last two weeks and, functionally, it has stood up very well.  Bugs were very few:

1. Run-time error 384 followed by crash if you try to minimise the window to the taskbar.

2. Run-time error 380 when trying to start software when FY6600 is already running (not every time, but persistent when it happens).  Program starts, but fails to open COM port and shows extreme values in parameter boxes.  Only cure is to close both program and FY600, then restart program followed by startup of FY6600 and manual instigation of comms.  *** SEE BELOW ***

3. Run-time error 6 in Calibration, if out of range number is entered into "Ch1 L:0.5 Min" box (eg accidentally enter a +ve number).  The value is saved, but the program shuts down when the message box is closed.

Every feature was tested for operation and works as it should (as far as I can tell, anyway);  the only shortcut I took was to only partially test Ch2 with some random settings.  Sweeps using VCO input were tested using an FY6800 feeding the VCO of the FY6600 (and kept me amused for hours watching the results on the scope).

The main improvements needed are now to the usability of the control software, some cosmetic, and some to the data entry method.

1.  After seeing that popup box appear a thousand times when entering a new parameter, I would just love to see direct entry into the value boxes enabled!  If the popup has to stay, then a bigger, bolder font is required to ease eyestrain.

2.  Can a shortcut method of number entry be implemented, eg 50m instead of 50000000, 10.7m instead of 10700000, and 455k instead of 455000?  Besides being difficult to read and decipher long strings of zeros, I think I'm getting RSI from bashing the zero key!

3.  Remove all Chinglish from labels and popups, such as "Forth&Back" in the Sweep - Direction label (which strangely changes to the more usual Back&Forth once the Source has been changed to VCO and back to Time).  As Forth, Back, and Back&Forth are not really descriptive of what happens in most of the sweep modes, "Increasing", "Decreasing" and "Alternating" may be better general terms.  (Or Rising, Falling, Alternating ?)  In the Waveform Window, the "Reset Waveform" button doesn't really describe what it does, ie "Clear Waveform" or "Erase Waveform", and the popup it opens is a good example of Chinglish gobbledegook, when it really means "Are you sure?  Unsaved data will be lost."

4.  Calibration window - it would be preferable if the first data entry popup opens as soon as the item buttons are pressed, as it's too easy to look away from the screen after clicking on a button and enter the first value from the DVM, only to then find that the popup window hasn't been open...   Again, direct entry would be preferable to the popup.

5.  Move the Waveform and Text windows to the RHS, so that the most used windows (Control and Configuration) are in their "natural" positions at the left?

6.  Provision for naming uploaded waveform slots something other than "RandomXX" would be very good to have.  How do you know what you put in Slot 51 a couple of weeks after the upload, let alone six months later?

*** This actually happened again while I was writing this tome, but this time it wasn't recoverable after an hour of trying different things.  The only way back this time was a full bluepill erase and reprogram.  The full error message showed "Invalid parameter value", and was there even after a simple reprogramming without erasure, so the problem appears to be corruption of the data storage area in the STM32 chip.  The first time it happened was after I'd closed the software and turned off the boxes, although they were still connected to the PC which was left running overnight doing other things; the problem occurred the next day, for no apparent reason, when I turned the boxes and software back on again for another session but, as stated earlier, I managed to get everything up again pretty quickly and worked for several more hours without a hitch.  This time I'd pressed "Send Data" in the Waveform Window when there was only a blank waveform on screen; wondering if I'd accidentally overwritten the factory sine wave in Slot 1, I went back to the Control Window to check, and error 380 appeared again.  (Which reminds me - that "Send Data" button needs a confirmation popup along the lines of "Ensure selected Loading Area is correct.  Send / Cancel" to stop accidental overwriting of uploaded waveforms.)

I think soundtec said he'd been struck by the same, or similar, error just a few days ago, but I don't know if he's overcome it yet.  I'll keep playing with the software to see if I can find any clues as to what might be happening.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 05, 2019, 03:23:25 am

I should have done it two days ago. I've attached it in the original post.


Cheers, Miti!

Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 05, 2019, 01:35:03 pm
Thanks for that Dave ,
Yeah its very similar to the issue Ive had , like you I found it best to run up the software before the machines connected ,then manually select the com after . I did get a couple of lock ups on both software and the Generator ,but a power down and back up of FY and restart of the software cleared the problem  .
Without any software connected I find the FY to work fairly well , its putting out the waves or functions its supposed to do.

One thing I found a bit superfluous was the menu within menu , so for instance say you have a choice of two variables , Trig or counter input , instead of source button toggling trig/counter  you have to go down  another menu level to select between two variables ,
I think multiple presses to cycle through the options is better and easier than another layer of submenu  ,

I must reflash my on-board Stm32 , I'll be more carefull this time , Ive a feeling there could have been a grounding issue between the computer and the FY6600 last time ,a ground loop and hum I think could upset the flashing of memory , I'll run the laptop off batteries only this time when I run the update . 
Maybe screening both the ST link  and the FY6600 in a biscuit tin for the duration of the update might be a plan too .
 
 



 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on October 05, 2019, 01:52:10 pm
No issues flashing the microcontroller ... you should do it with the face off , so the power is only from programmer .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 05, 2019, 02:35:12 pm
Hi soundtec - it's possible that Run-time error 380 is covering two different types of problem: the minor one which we've both had and found a workaround for, and the major one I had last night.  Although recovery from that isn't that big a deal once you know what's happened, it's not something you'd want to happen regularly, as you lose all your saved setups and calibration details each time.  It would be prudent to take a screenshot of your calibration figures so that they can be quickly re-entered without needing the DVM every time.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 05, 2019, 04:33:14 pm
Well, I've given Fremen's control software a good thrashing over the last two weeks and, functionally, it has stood up very well.  Bugs were very few:

1. Run-time error 384 followed by crash if you try to minimise the window to the taskbar.

2. Run-time error 380 when trying to start software when FY6600 is already running (not every time, but persistent when it happens).  Program starts, but fails to open COM port and shows extreme values in parameter boxes.  Only cure is to close both program and FY600, then restart program followed by startup of FY6600 and manual instigation of comms.  *** SEE BELOW ***

3. Run-time error 6 in Calibration, if out of range number is entered into "Ch1 L:0.5 Min" box (eg accidentally enter a +ve number).  The value is saved, but the program shuts down when the message box is closed.

Every feature was tested for operation and works as it should (as far as I can tell, anyway);  the only shortcut I took was to only partially test Ch2 with some random settings.  Sweeps using VCO input were tested using an FY6800 feeding the VCO of the FY6600 (and kept me amused for hours watching the results on the scope).

The main improvements needed are now to the usability of the control software, some cosmetic, and some to the data entry method.

1.  After seeing that popup box appear a thousand times when entering a new parameter, I would just love to see direct entry into the value boxes enabled!  If the popup has to stay, then a bigger, bolder font is required to ease eyestrain.

2.  Can a shortcut method of number entry be implemented, eg 50m instead of 50000000, 10.7m instead of 10700000, and 455k instead of 455000?  Besides being difficult to read and decipher long strings of zeros, I think I'm getting RSI from bashing the zero key!

3.  Remove all Chinglish from labels and popups, such as "Forth&Back" in the Sweep - Direction label (which strangely changes to the more usual Back&Forth once the Source has been changed to VCO and back to Time).  As Forth, Back, and Back&Forth are not really descriptive of what happens in most of the sweep modes, "Increasing", "Decreasing" and "Alternating" may be better general terms.  (Or Rising, Falling, Alternating ?)  In the Waveform Window, the "Reset Waveform" button doesn't really describe what it does, ie "Clear Waveform" or "Erase Waveform", and the popup it opens is a good example of Chinglish gobbledegook, when it really means "Are you sure?  Unsaved data will be lost."

4.  Calibration window - it would be preferable if the first data entry popup opens as soon as the item buttons are pressed, as it's too easy to look away from the screen after clicking on a button and enter the first value from the DVM, only to then find that the popup window hasn't been open...   Again, direct entry would be preferable to the popup.

5.  Move the Waveform and Text windows to the RHS, so that the most used windows (Control and Configuration) are in their "natural" positions at the left?

6.  Provision for naming uploaded waveform slots something other than "RandomXX" would be very good to have.  How do you know what you put in Slot 51 a couple of weeks after the upload, let alone six months later?

*** This actually happened again while I was writing this tome, but this time it wasn't recoverable after an hour of trying different things.  The only way back this time was a full bluepill erase and reprogram.  The full error message showed "Invalid parameter value", and was there even after a simple reprogramming without erasure, so the problem appears to be corruption of the data storage area in the STM32 chip.  The first time it happened was after I'd closed the software and turned off the boxes, although they were still connected to the PC which was left running overnight doing other things; the problem occurred the next day, for no apparent reason, when I turned the boxes and software back on again for another session but, as stated earlier, I managed to get everything up again pretty quickly and worked for several more hours without a hitch.  This time I'd pressed "Send Data" in the Waveform Window when there was only a blank waveform on screen; wondering if I'd accidentally overwritten the factory sine wave in Slot 1, I went back to the Control Window to check, and error 380 appeared again.  (Which reminds me - that "Send Data" button needs a confirmation popup along the lines of "Ensure selected Loading Area is correct.  Send / Cancel" to stop accidental overwriting of uploaded waveforms.)

I think soundtec said he'd been struck by the same, or similar, error just a few days ago, but I don't know if he's overcome it yet.  I'll keep playing with the software to see if I can find any clues as to what might be happening.

Regards,
Dave

Thank you Dave for the feedback.

As you may have guessed, there are 2 projects in development: the front end or  bluepill project and the PC Software modification project. The first one was the main goal, the second one was of course induced by the first one. When I started the front end project (without LCD display), I had to find a way to send commands to the MCU, hence the use of the Feeltech PC software for which they published sources and the protocol. I did not realized that this second project will consume so much time. In fact module after module, I rewrote about 80% of the original code.
The code that has yet to be improved/rewrite is the code behind the 2 left tabs (wave management, in which I just added a new protocol for wave transfer with new FP) and the code related to the COM port handling (which I started to simplify before releasing v0.8 but which is still in progress).
The main problem I see with this PC Software is that it is written in VB6, which is obsolete for years now. It won't run on linux platforms and regarding GUI possibilities, the less that can be said is that it looks quite old and limited now).
So at some point, a new PC interface will have to be written with another tool. That should not be a problem with the current project as a starting point plus the extended protocol description. So my goal with this modified PC Software is to have a tool that works with all the new FP functionalities, which won't crach, but I won't have time to improve a lot the GUI.

I will investigate the 3 crash problems you reported.
The only problem related to the bluepill firmware seems to be linked to the data storage in the STM32 MCU. In fact there are no real eeprom in the MCU and the data that needs to be stored is stored in code pages. This happens when you save a specific configuration but also in case of a power off to save the current configuration. When the voltage drops under a limit, an interrupt is triggered which calls a backup procedure.
Did you activated the last startup configuration option before it happens? Should you reproduced the problem, could you back up the whole MCU before erasing it? It should allow me to detect which parameter caused the problem. I suppose that the MCU crashed at started when loading the last configuration parameters. I will also add extra checks to detect potential problems.

All the improvements you are listing on the PC Software would be indeed worth having. I wil try to improve the GUI for the next release. It is just a matter of time ;-)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 05, 2019, 04:55:44 pm
Thanks for that Dave ,
Yeah its very similar to the issue Ive had , like you I found it best to run up the software before the machines connected ,then manually select the com after . I did get a couple of lock ups on both software and the Generator ,but a power down and back up of FY and restart of the software cleared the problem  .
Without any software connected I find the FY to work fairly well , its putting out the waves or functions its supposed to do.

Thank you Soundtec for the feedback. I will spend some time to improve the robustness of the PC Software.

One thing I found a bit superfluous was the menu within menu , so for instance say you have a choice of two variables , Trig or counter input , instead of source button toggling trig/counter  you have to go down  another menu level to select between two variables ,
I think multiple presses to cycle through the options is better and easier than another layer of submenu  ,
You don't have to go into submenus to modify the list values. It is only usefull when you have a lot of choices in the list as it allows you do directly select the one you want.
The intended way of choosing a list value when you are in edit mode is either to use Right or Left Arrow or Encoder + or -. It will show the next or previous possible choice.
With encoder you can go very fast.
Do you also don't like this way too?

I must reflash my on-board Stm32 , I'll be more carefull this time , Ive a feeling there could have been a grounding issue between the computer and the FY6600 last time ,a ground loop and hum I think could upset the flashing of memory , I'll run the laptop off batteries only this time when I run the update . 
Maybe screening both the ST link  and the FY6600 in a biscuit tin for the duration of the update might be a plan too .

Should you have the problem where the FP don't start, before re-flashing the MCU, could you make a full backup? And also tell me what is shown on the LCD?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 05, 2019, 06:19:21 pm
3.  Remove all Chinglish from labels and popups, such as "Forth&Back" in the Sweep - Direction label (which strangely changes to the more usual Back&Forth once the Source has been changed to VCO and back to Time).  As Forth, Back, and Back&Forth are not really descriptive of what happens in most of the sweep modes, "Increasing", "Decreasing" and "Alternating" may be better general terms.  (Or Rising, Falling, Alternating ?)  In the Waveform Window, the "Reset Waveform" button doesn't really describe what it does, ie "Clear Waveform" or "Erase Waveform", and the popup it opens is a good example of Chinglish gobbledegook, when it really means "Are you sure?  Unsaved data will be lost."

This should be an easy and quick modification. But what should I use?
There are 3 modes for sweeping:
Mode 1: goes from start value to end value,
Mode 2: goes from end value to start value,
Mode 3: goes from start value to end value then come back from end value to start value

If your start value is lower than your end value, than "increasing" or "Rising" might be confusing for Mode 1 as it will in fact decrease the value…
Other ideas for the 3 modes?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 05, 2019, 07:16:52 pm
Did you activated the last startup configuration option before it happens? Should you reproduced the problem, could you back up the whole MCU before erasing it? It should allow me to detect which parameter caused the problem. I suppose that the MCU crashed at started when loading the last configuration parameters. I will also add extra checks to detect potential problems.

Hi Fremen.  I'm pretty sure I was running with M1 enabled, and I certainly had another saved config in M2.  The problem when error 380 strikes is that the parameters mostly go back to their defaults (or some improbable value such as -1 sec sweep time) or are blank.  Although you can change tabs, the screens themselves are completely frozen, so any chance you might have had of correcting an obviously incorrect parameter is gone - one of my first thoughts was to load one of the saved configurations, but there was no way to do it.  The Startup configuration on the Config page had also changed back to "Default" and likewise couldn't be changed again.  I wish I'd thought to take some screenshots, as they might have been of use to you.  After deciding that the nuclear option was the only way left, I unzipped a fresh copy of the 0.8.hex file and did a memory comparison against it before I erased the MCU, and the ST-LINK Utility found no differences, so it was obvious that the program code itself hadn't been damaged.  I can't see any option to make a full chip backup, but presumably I could download the pages used for data storage if I knew their start address and size (if ST-Link will allow it)?  If you let me know where to look I'll see if I can save the contents next time it happens.  (I could have used another bluepill last night and retained all the evidence, as it happens, but it was after 3am and my brain was slowing down!)

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 05, 2019, 07:30:54 pm
This should be an easy and quick modification. But what should I use?
There are 3 modes for sweeping:
Mode 1: goes from start value to end value,
Mode 2: goes from end value to start value,
Mode 3: goes from start value to end value then come back from end value to start value

If your start value is lower than your end value, than "increasing" or "Rising" might be confusing for Mode 1 as it will in fact decrease the value…
Other ideas for the 3 modes?

Yes, that is a conundrum!  Perhaps if the Start and End value boxes were also relabelled "Start (Low) Value" and "End (High) Value", or just "Low Value" and "High Value" that would dissuade perverse-minded users from doing things in an unnatural way?  ^-^

Regards,
Dave

Edit:  How about "Low Limit" and High Limit" for the value boxes?  That should make the intent pretty well foolproof, I'd have thought.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 05, 2019, 08:49:05 pm
Did you activated the last startup configuration option before it happens? Should you reproduced the problem, could you back up the whole MCU before erasing it? It should allow me to detect which parameter caused the problem. I suppose that the MCU crashed at started when loading the last configuration parameters. I will also add extra checks to detect potential problems.

Hi Fremen.  I'm pretty sure I was running with M1 enabled, and I certainly had another saved config in M2.  The problem when error 380 strikes is that the parameters mostly go back to their defaults (or some improbable value such as -1 sec sweep time) or are blank.  Although you can change tabs, the screens themselves are completely frozen, so any chance you might have had of correcting an obviously incorrect parameter is gone - one of my first thoughts was to load one of the saved configurations, but there was no way to do it.  The Startup configuration on the Config page had also changed back to "Default" and likewise couldn't be changed again.  I wish I'd thought to take some screenshots, as they might have been of use to you.  After deciding that the nuclear option was the only way left, I unzipped a fresh copy of the 0.8.hex file and did a memory comparison against it before I erased the MCU, and the ST-LINK Utility found no differences, so it was obvious that the program code itself hadn't been damaged.  I can't see any option to make a full chip backup, but presumably I could download the pages used for data storage if I knew their start address and size (if ST-Link will allow it)?  If you let me know where to look I'll see if I can save the contents next time it happens.  (I could have used another bluepill last night and retained all the evidence, as it happens, but it was after 3am and my brain was slowing down!)

Regards,
Dave
The easiest is to save the full content of the MCU.
You enter a size of 0x20000, right click on Device Memory tab and "save to file" as .hex file
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 05, 2019, 09:10:35 pm
Did you activated the last startup configuration option before it happens? Should you reproduced the problem, could you back up the whole MCU before erasing it? It should allow me to detect which parameter caused the problem. I suppose that the MCU crashed at started when loading the last configuration parameters. I will also add extra checks to detect potential problems.

I just tried to create Error 380, and managed it first time!  The procedure is as follows:

Start with working software and FY6600, change some values and save the configuration (I started with defaults and set Ch1 to 10MHz sine wave at 3.5v ampl., and Ch2 to 20MHz sine wave at 5v, then saved the config to M2).  Ensure "Last" is checked in Config window.

Go to the Waveform window and press "Reset Waveform" then "Send Data".  The program will try to send something somewhere, then put up a message saying "No answer from generator".
At this point the software will now be completely unresponsive and may have to be forcibly closed using Task Manager.

Restart the software and Error 380 will pop up.  The Control and Config windows should look something like the attached (as you can see, the Control window is nothing like it should be).  Tonight the Control window is frozen solid, but the buttons in the Config window can still be "pressed", even though they don't do anything.

I've also got a bluepill which will probably contain some corrupted data (if I can get to it), although the ST-Link utility again shows nothing wrong with the program in memory. (But you can now easily create some corruption of own.)

Regards,
Dave

** Edit:  Hex Dump added. **
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 05, 2019, 09:24:19 pm
The easiest is to save the full content of the MCU.
You enter a size of 0x20000, right click on Device Memory tab and "save to file" as .hex file

Added to attachments in previous message!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 05, 2019, 11:58:05 pm
Did you activated the last startup configuration option before it happens? Should you reproduced the problem, could you back up the whole MCU before erasing it? It should allow me to detect which parameter caused the problem. I suppose that the MCU crashed at started when loading the last configuration parameters. I will also add extra checks to detect potential problems.

I just tried to create Error 380, and managed it first time!  The procedure is as follows:

Start with working software and FY6600, change some values and save the configuration (I started with defaults and set Ch1 to 10MHz sine wave at 3.5v ampl., and Ch2 to 20MHz sine wave at 5v, then saved the config to M2).  Ensure "Last" is checked in Config window.

Go to the Waveform window and press "Reset Waveform" then "Send Data".  The program will try to send something somewhere, then put up a message saying "No answer from generator".
At this point the software will now be completely unresponsive and may have to be forcibly closed using Task Manager.

Restart the software and Error 380 will pop up.  The Control and Config windows should look something like the attached (as you can see, the Control window is nothing like it should be).  Tonight the Control window is frozen solid, but the buttons in the Config window can still be "pressed", even though they don't do anything.

I've also got a bluepill which will probably contain some corrupted data (if I can get to it), although the ST-Link utility again shows nothing wrong with the program in memory. (But you can now easily create some corruption of own.)

Regards,
Dave

** Edit:  Hex Dump added. **
Thank you Dave for the backup  :-+

My development machine for the PC Software is a Virtual Machine running Windows XP as I need VB6 studio which does not run under Windows 10. With this machine I can't reproduce your problem.
When I run PC Software 0.8 directly from my host machine which is Windows 10, I get the error message "No answer from generator" when downloading any waveform, then I have to kill the program with the task manager and restart the function generator but it does not corrupt the flash memory from the MCU... I will see tomorrow with my Logic Analyser what is going on with Win10.

I loaded my bluepill with your backup and also got the error 380. Some data in the flash is corrupted in M1 (sweep data on CH1 and CH2). I don't know yet if it is related to the wave transfer which failed or if it happened when you saved the config to M2. As you had to restart the bluepill after that, it loaded corrupted data from M1 to current parameters …. and PC Software obviously did not liked it. As you have no keyboard nor LCD connected to your bluepill, you can't correct the values directly in the bluepill and your only solution is to reflash the bluepill.
The good news is that I can easily modify PC Software to deal with incorrect values, I can also modify the firmware to check the values coming from the flash at startup.
The question remaining is how did the flash get corrupted ?
Could you try again the exact same procedure after having reflashed the bluepill?
Also could you check the voltage on your bluepill power supply input?

Thank you again!

Edit: In M1 I can see CH1 with 10Mhz and 3.5V, CH2 with 20Mhz but amplitude is not 5V but 2.5V … if you are sure for the 5V, that is an interesting information.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 06, 2019, 01:29:21 am
Hi Fremen - new hex dump as requested, and BP input voltage (from FY6600) is 4.945v, rock steady.  This time the software didn't freeze as it did before, and I could close it down normally, but it still gave Error 380 when it was restarted, and the Control window was corrupted.  This time, though, it allowed me to enter new values for the frequencies of the two channels - but no matter what I put in the popup, the number shown in the value boxes was always 20000000 on both channels!  Subsequent restarts of the software, however, show the attached Control window, in which drop-downs can be changed but all values are frozen.   It looks as if the effects of the corruption may vary randomly, even if the cause is the same.

The 2.5v shown for Ch2 in M1 is probably correct, thinking about it - I set it to 5v initially and saved the setup to M2, then changed it to 2.5v so that the config saved in M1 would be different.  At least, that's definitely what I did this time, and almost certainly what I did previously (so probably not as good a lead as you first thought?).

I'm running 64bit Win7, by the way, just to add another variable into the equation.

If you want any more tests doing, it won't be a problem, but they'll have to wait until tomorrow, as I'm off to try and catch up on some sleep :)

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 06, 2019, 01:54:13 pm
Hi Fremen - I think the problem stems from trying to upload a waveform into Loading Area 1.  I've just been testing with a reflashed bluepill and the Startup Config set to Default and, although the "No answer from generator" - freeze - force shutdown - Error 380 sequence is the same, the program looks uncorrupted when it restarts but won't communicate with the FY6600 until the box has been restarted, then everything appears to be normal again (this is the "minor corruption event" that both soundtec and myself have mentioned).

However, looking in LA 1 to see what was there, I found a partial waveform: it was 75% of the sine wave which I'd made two or three attempts to send there, so I resent the sine wave again and the transfer completed ok.  Then I tried sending an AM waveform to LA 50: no problem; sent it LA 51: no problem; sent it to LA 1: error sequence starts.  Looking in LA 1 after everything was running again, there was 25% of the AM wave and the remainder of the previous sine wave; sent the AM wave again: error sequence - restart everything - check in LA 1, there was 50% of the AM wave and the remaining 50% of the old sine wave (see attached).  Sent the AM wave again: error sequence etc., and LA 1 now has 75% of the AM wave and 25% of the sine wave (see attached).  Tried twice more to send the rest of the AM wave, but LA 1 is stuck with 75% AM and 25% Sine wave.  Tried sending an FM wave to LA 1: error sequence etc., and now there's 50% FM + 25% AM + 25% Sine in there (see attached).  Are we looking at a bug in the new wave transfer protocol, which only appears to affect LA 1 (and maybe others, but not 50, 51 and 55, according to my testing)?

I suspected that during the these tests corrupted data would have been lurking in M1, so I then tried to expose it, but loading M1 just returned Ch2 back from Random51 to SINE (reversing the last previous change), and restarting the program with M1 enabled was also normal.  Then I tried sending a sine wave to LA 1 with Startup set to use M1, fully expecting everything to break completely, as per last night's tests, but after going through the error - restart sequence again I looked in LA 1 and found a 100% sine wave!  So this time the transfer had worked ok, immediately before comms were lost, and the program restarted ok afterwards.  Next, I sent an AM wave to LA1 again: it completed ok, no error sequence, no restarts necessary.  Then the same thing with an FM wave: perfect.  Then a Sawtooth: perfect again, so now it appears that the comms / transfer protocol has settled down and become stable.  Restarted the program and the FY6600, and sent two more waveforms to LA 1 without a problem, but the next one, an AM wave, failed after two blocks (now watching the status bar at the bottom of the window - no need to restart everything now, as I know there will be 50% of an AM wave and 50% of a sine wave sitting in LA 1 :) ).

Now I was wondering why it wasn't doing last night's catastophic crashes any more, so I restarted everything again, turned on M1, and sent a blank wave to LA 1, which failed after 3 blocks.  After restarting, LA 1 contains just the remaining 25% of the earlier sine wave, but everything else is still working and Error 380 seems to have gone missing.  Time to give up!

Perhaps once the transfer problem has been sorted out, the M1 corruption problem will disappear with it.  After a cup of tea, I'll try last night's procedure again with a clean reflash, just to make sure it still happens as it did.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 06, 2019, 03:52:09 pm
More testing:

Tried a new bluepill, freshly flashed, did same procedure as last night, got same result.  Reflashed, tried again without saving any config data to M2, but still same result.  Both transfers to LA 1 failed after two blocks, and both produced Error 380.

Decided to go back to the previous BP, which was apparently working ok when it was disconnected, in order to check LA 1 contents, and got an immediate Error 380 from it!  So it was actually corrupted but still working earlier?

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 06, 2019, 04:30:56 pm
More testing:

Tried a new bluepill, freshly flashed, did same procedure as last night, got same result.  Reflashed, tried again without saving any config data to M2, but still same result.  Both transfers to LA 1 failed after two blocks, and both produced Error 380.

Regards,
Dave
Thank a lot Dave for your time.

There was definitely a bug in the PC Software regarding the new wave transfer protocol coding. The bug was invisible on my test system as it is quite "slow" (Virtual machine). When running PC Software directly on the host system I could trace it with my logic analyzer  :phew:
There was a de-synchronization between the PC and the MCU which led to the MCU waiting for a wave block (1/4 of a wave) while the PC was still asking the authorization to send it.
When it that waiting state, the MCU does not reply to other commands.
This synchronization problem could happen randomly on any block, hence the partial waves.

The corrupted data in M1 is still a mystery for me as I was not able to reproduce it.
I attached a modified version of PC software (just the wave transfer for now, not yet the error 380 handling).
Let see if you are able to reproduce the flash corruption with this version now…
I will also modify the FP firmware so that it will return to a normal waiting state alone if the block wave is not coming.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 06, 2019, 07:11:46 pm
That seemed to have got it sorted, Fremen.  I did lots of transfers without a problem, saved four different config sets and swapped from one to another several times, and everything was fine.  Then I restarted the box and the program and immediately got error 380 again.  The hex file attached is taken from the MCU while still attached to the FY6600 and powered up, so you should be seeing the contents exactly as the software saw them.  M1 was enabled, so I'll try again with M1 off to see if that's where the problem is coming from.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 06, 2019, 08:19:24 pm
Here's something to think about, Fremen: I didn't reflash the bluepill, but on a whim I started up the Feeltech software v6.0, and it worked perfectly, with all the saved config sets loading ok.  Then I closed it and restarted v0.81 and 0.81 was happy again!  No error 380, and everything working.  Closed and restarted 0.81 four times, no problem.  Closed the software and shutdown the FY6600, restarted the software and turned on the FY6600, error 380.  Started v6.0, works fine.  Closed 6.0 and started 0.81, working again.  Closed the software and shutdown the FY6600, restarted the FY6600 then the software, working fine.  Closed the software and shutdown the FY6600, restarted the software and turned on the FY6600, error 380.

I don't think you'll find any corrupted data, because it's probably something else that's causing the error, still linked to the transfer protocol.  I didn't have any problems with v0.8 until last night, when I tried waveform transfers with it for the first time.  It seems that the software is very stable until you do an upload, then something untoward happens causing error 380.  It may be significant that the error occurs when the software is running before the FY6600 is turned on, as the error pops up when the COM port is selected - and you did say that COM port handling was still a work in progress, so perhaps it will sort itself out as work progresses?

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 06, 2019, 10:23:26 pm
Here's something to think about, Fremen: I didn't reflash the bluepill, but on a whim I started up the Feeltech software v6.0, and it worked perfectly, with all the saved config sets loading ok.  Then I closed it and restarted v0.81 and 0.81 was happy again!  No error 380, and everything working.  Closed and restarted 0.81 four times, no problem.  Closed the software and shutdown the FY6600, restarted the software and turned on the FY6600, error 380.  Started v6.0, works fine.  Closed 6.0 and started 0.81, working again.  Closed the software and shutdown the FY6600, restarted the FY6600 then the software, working fine.  Closed the software and shutdown the FY6600, restarted the software and turned on the FY6600, error 380.

I don't think you'll find any corrupted data, because it's probably something else that's causing the error, still linked to the transfer protocol.  I didn't have any problems with v0.8 until last night, when I tried waveform transfers with it for the first time.  It seems that the software is very stable until you do an upload, then something untoward happens causing error 380.  It may be significant that the error occurs when the software is running before the FY6600 is turned on, as the error pops up when the COM port is selected - and you did say that COM port handling was still a work in progress, so perhaps it will sort itself out as work progresses?

Regards,
Dave

Thank you Dave for the feedback.

I think I found the link between the wave transfers and the corrupted flash values. The wave transfer bug in the PC software was one,  but it also triggered another one in the new firmware. :palm:

I some conditions the receive buffer of the FY6600 was able to overflow which led to overwrite some variables in memory (sweep parameters, …). When switching off the FY6600, the parameters are saved to flash memory (when option is enabled)... with inconsistent values for some of them. So the corruption occured before writing to the flash, not in the flash.

Error 380 occurs in the PC Software because some list values read from the FY6600 are inconsistent with min and max values it has. For example sweep direction is supposed to be 0, 1 or 2. If greater, it won't find a corresponding label and will fire the error 380. This is not supposed to happen in normal situation and this can easily be handled by program.

The original feeltech pc software is not able to read all the values from the FY6600, especially the sweep parameters that can only be written. When using v6.0, you where able to overwrite sweep parameters that had inconsistent values with consistent ones. That explain why it solved the error 380 on v0.81.

I will modify the firmware to fix the buffer problem and the PC software to check list values consistency (and also some labels).

Let's move forward  ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 06, 2019, 10:51:44 pm
Let's move forward  ;)

Yes indeed!  I'll be waiting for the next release to put it through the wringer again ...

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 11, 2019, 11:18:41 pm
Let's move forward  ;)

Yes indeed!  I'll be waiting for the next release to put it through the wringer again ...

Regards,
Dave

Here we go!
PC Software: Wave transfer should be OK, original COM port handling re-written
Bluepill & FP: Wave transfer buffer handling bug fixed, display data on LCD with thousand separator
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 12, 2019, 01:12:27 am
Thanks, Fremen.  I'll get onto it over the weekend, I hope.

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 12, 2019, 10:13:43 am
Thanks for the new software Fremen, I'll let you know how it goes later on today.
I did reflash my unit with V0.81  ,just to double check there wasnt an issue related to the process of updating itself , and it wasnt ,
I didnt try any waveform uploads , but many of the issues Dave mentioned I saw too , like jumbled waveforms etc .

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 12, 2019, 02:44:40 pm
Yeah thats working a lot better for me , I see the ok/encoder push now defaults each variable to a preset value  thats great in  offset , phase ,duty and rise /fall  , my question is would it be simpler to make  the default values  the same as power on values?


One thing I like about your BP version is the addition of the numeric keypad , I think when you look and compare the FY series to the better makes of stuff thats the big difference , the Rigols and the Owons have a slightly bigger box to encorporate the numberpad .

I did notice that the data from the counter was only displayed when triggered from software , engageing counter from front panel the software wasnt able to hook in , also software reported back 10khz or ten times the value displayed on the unit itself .

I still see some waveform corruption in the display for the sine wave ,as loaded on slot one ,it sorta has a tail on it ,visable on the unit itself and also on the software ,now in 0.82 pc  Im seeing two cycles of each wave displayed in the thumbnail view in control window .

Just as a test I applied factory square wave (slot2) to measurment input , 1khz 5 volts ,all other parameters default , I get back a reading of 49.9 duty and differing +/- peak widths ,  499,992 /500,008 and its a bit jumpy ,
I went ahead and created my own square wave  in the software ,uploaded it to a blank arb memory slot , comes out perfectly 50% duty and right on 500,000nS  and 1khz ,rocksolid 
Ill repeat the same test with the unmodified FY6800 next and compare the result . Could it be possible that even the original memory slots data are corrupted to some small degree and that discrepency somehow got worse ,maybe  . Another thing about the measure page was gate mode isnt initially set,  maybe just default to 1 second mode like the original software here might be best  as I think it causes the pc software to hang up a bit as it expects to see a signal .
 
So I repeated my test with the standard FY6800 ,  around  499,994 vs 500,006 was the best I could get , regardless of uploaded/internal waveform , ac or dc coupled input . I did generally see an improvement across both AC and DC measurements with the new waveform , maybe someone else can try the same test .
 
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 13, 2019, 01:43:15 am
I decided to conduct a few more tests , I made a new sine wave in software , both in Fremens and in Wavemanager plus , I uploaded them both to  free slots on the FY6600 .  I then used a low distortion audio interface in conjunction with REW to measure the various harmonics produced at various levels , the new sine waves I made showed markedly less THD than the standard slot 1 sine , typically around 10-15 db less on several peaks across the frequency range .Ill try a similar set of tests tomorrow with the unmodified FY6800,same set of upload waves vs sine and square from mem slots 1 and 2 .

I ran the spectrum analysis at 96khz and factory slots clearly showed several spikes of distortion extending well above the audible range , so either the basic memory waveforms built into the FY6600 were sub optimal to begin with ,or somehow they became corrupted . I should be able to post screen caps of the various spectra tomorrow ,modified and unmodified machines , internal vs newly made waveforms .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 13, 2019, 10:14:54 am
Thank you sountec for the feedback!

Yeah thats working a lot better for me , I see the ok/encoder push now defaults each variable to a preset value  thats great in  offset , phase ,duty and rise /fall  , my question is would it be simpler to make  the default values  the same as power on values?
This was already existing in the previous versions. As you noticed, this was meant to reset parameters to preset values like  offset (0V), phase(0°), duty(50%) and rise/fall(4ns) . For frequency and amplitude that might be less usefull as frequency = 10kHz and amplitude = 2.5 V. These are the default power on values when the "last power on values" option is not checked. It is of course possible to take last power on values when pushing OK but then you have to remember what the values were, plus if you don't use the option, M1 memory, which is used to store the values when powering off, could be empty or could contains values that you don't even remember…
So you might be in a situation where you are not sure of what will happen when pushing a button...

One thing I like about your BP version is the addition of the numeric keypad , I think when you look and compare the FY series to the better makes of stuff thats the big difference , the Rigols and the Owons have a slightly bigger box to encorporate the numberpad .
The photo of the bluepill setup I posted might be confusing. I use a numeric keypad on the bluepill just because I needed a 4x4 matrix keypad to replicate the front panel keyboard hardware. Each key of the numerical keypad corresponds to an existing FP key (F1 = 1, F2 = 4, …). It is not used  for numerical data input.

I did notice that the data from the counter was only displayed when triggered from software , engageing counter from front panel the software wasnt able to hook in , also software reported back 10khz or ten times the value displayed on the unit itself .
The PC software is not reading continuously values and configuration from the FP. This of course possible but it consumes CPU times of the FP to get messages and to reply to them. This could lead to create artefacts when the FP is sweeping waveforms, which is done 100% by the FP software (FPGA genarates the wave and the FP sweeps it).
The only exception is when you trigger the measure function from the PC Software as it has obviously to read the measure values from the FP.
If you mix data input (on the FP directly and on the PC Software) you could then have inconsistent values displayed on the PC software.
For example if you change the gate time directly on the FP and have the PC Software reading measures, the frequency will not be displayed correctly unless you force a refresh of all the values (changing to another tab and coming back now forces a values refresh in the 0.82).
If you need to modify values on both the FP and the PC Software, then you have to think of forcing a refresh manually on the PC Software at some point.

I still see some waveform corruption in the display for the sine wave ,as loaded on slot one ,it sorta has a tail on it ,visable on the unit itself and also on the software
As I explained previously, this comes from a corruption of your sine directly in the main board eeprom. This is a known bug of the FY6600 caused by the FPGA. The only cure is to write the sine definition again in the eeprom. Either with an external programmer or using the FP to do it, which is what feeltech did (this function not developped yet in the FP).
The workaround for now is to use an arb slot with a sine wave that you send from the PC Software.

now in 0.82 pc  Im seeing two cycles of each wave displayed in the thumbnail view in control window .
Yes it was already like this in the previous versions. This might not be a good idea but I found it easier to read for some waves, like ramps for example. As for the FP LCD, it only displays on cycle.

Just as a test I applied factory square wave (slot2) to measurment input , 1khz 5 volts ,all other parameters default , I get back a reading of 49.9 duty and differing +/- peak widths ,  499,992 /500,008 and its a bit jumpy ,
I went ahead and created my own square wave  in the software ,uploaded it to a blank arb memory slot , comes out perfectly 50% duty and right on 500,000nS  and 1khz ,rocksolid 
Ill repeat the same test with the unmodified FY6800 next and compare the result . Could it be possible that even the original memory slots data are corrupted to some small degree and that discrepency somehow got worse ,maybe  .
The square wave, but also CMOS and Adj-Pulse waves are not stored in memory slots. They are dynamically created by the FPGA. It would otherwise be impossible for it to adjust on the fly the duty cycle for them (or pulse length).
When using a square wave that you created in a memory slot, the FPGA just send it to the output. This is a different process, hence the different results you got.
Unfortunately even a new FP firmware can't change this.

Another thing about the measure page was gate mode isnt initially set,  maybe just default to 1 second mode like the original software here might be best  as I think it causes the pc software to hang up a bit as it expects to see a signal .
I guess you still have inconsistent values in M1 from 0.81 and still have "last power on option " checked. This should be fixed after you corrected those values and switch off the FY6600.
You could otherwide perform a factory reset (which I recommand), but it will reset calibration data if you changed them, or you could simply check all the values and save your configuration to M1.

So I repeated my test with the standard FY6800 ,  around  499,994 vs 500,006 was the best I could get , regardless of uploaded/internal waveform , ac or dc coupled input . I did generally see an improvement across both AC and DC measurements with the new waveform , maybe someone else can try the same test .
I guess you saw 499,996 and 500,004 ns as they are multiples of 4ns.
4ns is the minimal resolution of the FY6600 and FY6800 as they sample at 250 000 Msa/s. So that seems quite logical results...

Sorry for the long post but I though this might also have some kind of interrest for others…

EDIT: 49.9 % is an incorrect rounding of the duty cycle. It should display 50.0 % as the result with a cycle of 1,000,000 ns and a wide+ of 499,992 ns is 49.9992 %. I will correct it in the next version.
And by the way 499,992 ns instead of 500,000 ns represents an error of 0.0016 % … I don't think the FY6600 oscillator is that precise...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Jacon on October 13, 2019, 10:38:38 am
Fremen, considering this:
.....
The PC software is not reading continuously values and configuration from the FP. This of course possible but it consumes CPU times of the FP to get messages and to reply to them. This could lead to create artefacts when the FP is sweeping waveforms, which is done 100% by the FP software (FPGA genarates the wave and the FP sweeps it).
...
how about moving to this new board:
https://www.banggood.com/STM32F401-Development-Board-STM32F401CCU6-STM32F4-Learning-Board-for-Arduino-p-1568897.html (https://www.banggood.com/STM32F401-Development-Board-STM32F401CCU6-STM32F4-Learning-Board-for-Arduino-p-1568897.html) ?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fremen67 on October 13, 2019, 11:33:02 am
Fremen, considering this:
.....
The PC software is not reading continuously values and configuration from the FP. This of course possible but it consumes CPU times of the FP to get messages and to reply to them. This could lead to create artefacts when the FP is sweeping waveforms, which is done 100% by the FP software (FPGA genarates the wave and the FP sweeps it).
...
how about moving to this new board:
https://www.banggood.com/STM32F401-Development-Board-STM32F401CCU6-STM32F4-Learning-Board-for-Arduino-p-1568897.html (https://www.banggood.com/STM32F401-Development-Board-STM32F401CCU6-STM32F4-Learning-Board-for-Arduino-p-1568897.html) ?
The new firmware is written for the existing front panel MCU. This is a STM32F103CBT6 that you also find in the bluepill. Hence the use of the bluepill as a transition.
Changing the Front panel MCU is not something that a lot of people are willing or able to do. Plus you would have to find a CPU with a LQFP48 package that should also be 100% pin compatible.

The fact that the Front Panel has to deal with LCD, communication and sweep handling at the same time is not an ideal design.
Without removing the existing front panel CPU, a solution would be to use a second board dedicated to FPGA communication. This would be easier for anyone to do. In that case the second board could of course have a more powerfull CPU.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: soundtec on October 13, 2019, 02:18:32 pm
Many thanks for the detailed reply Fremen,

I do wonder though are all the internal factory stored waveforms subject to this degradation over time , it was only my abillity to measure very small amounts of distortion was I able to detect it . The great thing for me is that my FY6600 is now capable of even lower distortion on sine waves than before ,and by a good margin , I was in 0.05 % territory now with the new sine  its more like 0.002% or less 2nd harmonic , as well as upper harmonics barely above noise floor .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on October 15, 2019, 09:21:25 pm
Hi Fremen,

The software checking is still in progress, but I've been through quite a bit so far and only come up with one crash and a couple of small items:

Calibration:  Ch2 Offset M:2.5 - this gives a Runtime error 6 if you try to enter a value less than 2.5, so the allowable range needs to be checked.  The program closes when the error dialog is cleared, but the entered value is still saved.  Once, after restarting the program after this crash, the boxes in the Control Window were full of improbable and impossible values, so data corruption had obviously taken place again; the same incorrect values reappeared each time the program was restarted, whether set to Defaults or M1,  but at least the program still ran ok and sensible values could be entered in the value boxes.  I couldn't recreate this situation again, so hopefully it was just a one-off.

Control Window - Sweep - Square Wave - Duty:  Ch1 range is 0.001% - 99.999%, but Ch2 range is only 0.1% - 99.9%.

Control Window - Ch1 Mod - FSK - HOP Frequency has redundant decimal point after value if whole number entered.

All the previous problems have been cleared, and waveform uploading now works very well indeed.  I need another session or two just to recheck the sweep and counter functions, but it's looking pretty good at the moment!

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: fisafisa on November 27, 2019, 04:55:34 pm
Hi
No more news?


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Prehistoricman on December 09, 2019, 05:33:00 am
Did you guys ever extract the built-in firmware?

I found this paper that extracted firmware from an STM32F1 series MCU 'easily':
https://tches.iacr.org/index.php/TCHES/article/download/7390/6562/
Page 9/10 (207/208)

Sounds like a fun project.

Edit:
And by an interesting coincidence, this paper specifies a FeelTech unit for generating their attack glitches.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: wpmcnamara on December 21, 2019, 04:24:37 am

I used it to align some AM radios but now I wanted to align the 10.7MHz IF sections.

So I recently purchased an FY6800.  After verifying it worked I ordered an assortment of upgrade parts.  I installed a linear 15vdc supply, installed new op amps and replaced the encoder so I could have a larger knob.  Next was to figure out how to get a repeatable setup for FM IF sweeps and contribute to the thread.


I also want to repair/restore/adjust/align/fiddle with some FM receivers.  I'd be interested how you make out.  Is it necessary to have such high outputs that new power supplies, op-amps, etc are needed? 
Also, I'm trying to synthesize a usable FM multiplex stereo test signal.  I have an RF signal generator with an FM function, but the multiplex signal is complex and I'm still trying to figure out the best way to do it.  Any ideas?

I recently picked up a FY6800 cheap and the first serious thing I did was use it in troubleshooting an AM/FM receiver.  You can generate a basic, but very usable stereo FM IF signal with the 6800, straight out of the box, no mods necessary.  I loaded a stereo multiplex signal in one of the arbitrary slots and used it, on channel 2, to modulate a 10.7 MHz sine wave on channel one, which I fed into the IF section.

The stereo MPX isn't as complicated as it sounds.  I put together an Excel spreadsheet that would generate the waveform for me.  8192 data points is plenty.  I generated a cosine signal on the left channel and a sine signal on the right.  The spreadsheet lets me adjust the L and R levels, as well as the relative modulation levels.

This is the MPX signal for a 1kHz sine and cosine at equal levels.
[attachimg=2]

This is what the decode output looks like.  This was taken from the audio outputs on the receiver sitting on my bench.
[attachimg=1]

Similarly, this is the MPX for a 1kHz sine and cosign with one signal at 50% of the other.
[attachimg=4]

And the decoded output...
[attachimg=3]

Now, you do see some channel separation problems if you set on channel to 100% and the other to 0%.  Channel separation is only about 20dB in that case.  However I don't know if that is a problem with the spreadsheet math, the limited sample size of the waveform, or this particular receiver.

*edit*  attached spreadsheet I used for the MPX waveform generation.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on December 26, 2019, 01:16:26 am
Did you guys ever extract the built-in firmware?

I found this paper that extracted firmware from an STM32F1 series MCU 'easily':
https://tches.iacr.org/index.php/TCHES/article/download/7390/6562/
Page 9/10 (207/208)

Sounds like a fun project.

Edit:
And by an interesting coincidence, this paper specifies a FeelTech unit for generating their attack glitches.

That attack was tried and did not work on this device.   You can find the details back around pp 15-20 of this thread.

I'm a bit surprised that predistortion of the waveform never came up in this thread that I recall.  Though I have *not* read all of it.

  I recently bought a text on the use of predistorted waveforms for generating RF which is very important to cellular operations.

Have Fun!
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Prehistoricman on December 28, 2019, 10:18:49 pm
That attack was tried and did not work on this device.   You can find the details back around pp 15-20 of this thread.

Really? I took a look at those pages and didn't see anything about it. I saw references to the Fraunhofer attack (which doesn't work on this STM32F1) but not the one I found.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: JohnCompter on December 29, 2019, 10:16:31 am
The 60 Mhz is valid for a sine wave, but the other wave forms tend to have a sine wave form also at 60 Mhz.
The output is very sensitive for grounding currents. I lost a number of steps is the output attenuator by grounding currents.
The interface to a PC works well, but one has to climb a steep hill before the communication between PC and waveform generator operates well.
I did not found a way to transfer a waveform, made in e.g. Mathematica, in a intelligent way to the FY6800. Copy-past was the only way.

Cheap is true, but that is what you notice when you buy it. The quality belonging to cheap you will notice for ever.
 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: CDaniel on December 29, 2019, 11:12:25 am
If you read the specs , the other waveforms are not specified up to 60MHz ... this is normal for every such generator , even expensive .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on January 02, 2020, 09:33:28 pm
That attack was tried and did not work on this device.   You can find the details back around pp 15-20 of this thread.

Really? I took a look at those pages and didn't see anything about it. I saw references to the Fraunhofer attack (which doesn't work on this STM32F1) but not the one I found.

Sorry.  I thought it was the same paper.  IIRC CyberMaus did all the work on that.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tzok on February 01, 2020, 07:16:17 pm
Will there be any updated versions of this firmware? Is is worth to flash it to a working panel (v3.2)? Chineese firmware is a little annoying, especially with changing a waveform each time WAVE button is pressed. And there is also something wrong with the amplitude of built-in half wave rectifier (but I believe firmware doesn't have anything to it).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: masterx81 on February 15, 2020, 12:03:30 pm
Hi! One simple question. Why i see most people goes to ths3095 instead 3091? 3091 seem a bit better...
Thanks!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on February 18, 2020, 01:51:40 pm
If you take the trouble to disassemble the device completely and replace the buffers I suggest you go all the way with THS3491. These are the best currently available and you can order directly from TI.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: masterx81 on February 18, 2020, 03:39:12 pm
Aren't they a bit an overkill for a device like this?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Jacon on February 18, 2020, 05:38:21 pm
..... I suggest you go all the way with THS3491....
And what do you plan to do with 3491's PowerPad on this PCB, which isn't prepared for it ?   :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on February 18, 2020, 07:09:22 pm
You don't need the powerpad.
I also used them. But now i have some overshoots  with square Signal...
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: masterx81 on February 18, 2020, 08:27:16 pm
One more reason to remain on classic 3091 😅
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: bdivi on February 19, 2020, 10:52:35 am
PowerPad thermal relieve is not required for the FY6600 output power. The original heat sink on top is more than enough.
The PCB is silkscreened bellow the ICs so no issues with shorting anything.

I have perfect square waves here - no overshoots whatsoever with sub 5ns rise and fall times.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on February 21, 2020, 01:27:08 am
Look what I found in the dumpster at work today... among other goodies. GPS modules, brand new 7" LCDs 800x480, RF cables, pressure sensors, small screws, etc.

Fully isolated +/- 15V and 5V power modules. The first thought was... replacement for my FY6600 power supply. With a Mean Well 24V/15W (or even a decent 24V wall adapter from a thrift store) and two of these power modules, plus double LC filtering, I think I can get a pretty decent and quiet power supply with a small footprint. What do you think?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 21, 2020, 11:39:53 pm
Look what I found in the dumpster at work today... among other goodies. GPS modules, brand new 7" LCDs 800x480, RF cables, pressure sensors, small screws, etc.

Fully isolated +/- 15V and 5V power modules. The first thought was... replacement for my FY6600 power supply. With a Mean Well 24V/15W (or even a decent 24V wall adapter from a thrift store) and two of these power modules, plus double LC filtering, I think I can get a pretty decent and quiet power supply with a small footprint. What do you think?

 You lucky B'stard you! :)

 I don't usually bother downloading these "Show 'n' Tell" photos but since I wanted to invert the 2nd one to check out those GPS modules, I made an exception. They, and the inverted copy, are now in a folder in the Feeltech signal generators folder in the test equipment folder which I named "Miti's dumpster find (2020-02-21)" for future reference.

 I'd suggest using one of those 'R' cored mains transformers rather than replace one smpsu (the original bare board unit) with another (that Meanwell one you mentioned) to supply the required nominal 20vdc input to those dc-dc converter modules.

 There's no guarantee that even a a metal cased mains smpsu will do much better in preventing the high voltage switching spikes from escaping onto its low voltage output rails than the existing smpsu board. Using a conventional high quality mains transformer with capacitor smoothed full wave rectification of its low voltage secondary(ies) to feed those modules guarantees elimination of such a troublesome switching noise source from your proposed psu solution.

 The biggest downside with the classic conventional analogue mains psu arises from the waste heat of analogue voltage regulators (intelligent resistive droppers being a better description of your classic 7805, 7812 and 7912 voltage regulator).

 Using switching regulators in place of analogue regulators deals rather nicely with this waste heat issue although they may suffer some low level of switching ripple and noise on their output rails (but only extremely low levels of directly radiated or conducted switching noise in the case of competently designed switching regulator modules).

 At least you won't have to suffer the issues of high voltage switching transients being coupled onto the output rails via the inter-winding capacitance of a cheap commodity unshielded high voltage isolating/step down transformer so commonly used in your typical smpsu whether nicely encased in a metal "screening box"  like that Meanwell or just a tiny circuit board mounted in a lump of plastic directly plugged into a wall outlet.

 When you see claims of "Low noise and ripple" for the better quality smpsu, it's worth reminding yourself that that's just a relative term for the switching class of psu - even the 'low noise' types can still negate the benefit of all those low noise dc-dc converter modules you've lucked out on.

 Judging from the photos you posted, those modules appear to be good quality items, well worthy of such a project. I think it would be a big mistake to power them off yet another mains voltage smpsu whilst there's ample room to include a 15 to 25 VA R type mains transformer and a bridge rectifier and smoothing cap (along with a cheap 10MHz OCXO driving an NB3N502 programmed as a 5 times multiplier sat where the crappy smd XO used to be). A 15VA transformer is sufficient if you're not planning on upgrading to an OCXO but you might want the extra margin of an additional 5 to 10 VA to cater for any possible future OCXO upgrade.

 It looks like the left hand column is displaying the 5v modules and the middle column the +/-15v modules. It also looks like they're all blessed with heavy duty LDO post dc-dc converter voltage regulators intended to attenuate residual ripple and switching noise - they need to be special LDO chips with a much higher frequency psrr performance (100s of KHz versus the typical 10KHz max of an LM1117 LDO regulator) in order to achieve this hoped for reduction in output ripple and noise.

 Are the output rails really fully isolated from their input connections? Also, did you manage to track down any datasheet information on them? It looks like you've managed to capture a few of the "Unicorn Parts" I've been searching for on ebay this past year or so, you lucky B'stard.  ;)

 One final question (idle curiosity really) in regard of those GPS boards. Do you have any information of the actual gps modules themselves? I suspect they're most likely timing modules rather than cheap commodity navigation modules - u-blox maybe?

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on February 22, 2020, 12:33:11 am
Well... these kind of switching modules can push quite a bit of HF noise between the input and output. I wouldn't want to use these in a piece of test equipment without a very careful board design and filtering. These modules are nice to provide a lot of power to digital circuitry.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on February 22, 2020, 01:36:35 am
Datasheets and link attached.

https://learn.adafruit.com/adafruit-ultimate-gps

Edit: Those are not LDOs, they are Schottky diodes. The question is, what's a PIC doing there? Probably just ON/OFF and supervision?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on February 22, 2020, 04:05:55 am
Datasheets and link attached.

https://learn.adafruit.com/adafruit-ultimate-gps (https://learn.adafruit.com/adafruit-ultimate-gps)

Edit: Those are not LDOs, they are Schottky diodes. The question is, what's a PIC doing there? Probably just ON/OFF and supervision?

 Thanks for the gps module link. So, it turns out to be not so useful a module as far as my GPSDO ambitions are concerned (my basic PLL GPSDO using a u-blox NEO-M8N is now completed and housed in a neat extruded aluminium case since my final reworking of the circuit just last night). I think the u-blox module is actually a better bet for this sort of  basic GPSDO project (based in part on Gyro's LEA-6T circuit he posted almost two years back here: https://www.eevblog.com/forum/projects/my-u-blox-lea-6t-based-gpsdo-(very-scruffy-initial-breadboard-stage)/msg1493431/#msg1493431 (https://www.eevblog.com/forum/projects/my-u-blox-lea-6t-based-gpsdo-(very-scruffy-initial-breadboard-stage)/msg1493431/#msg1493431) ).

 I managed to track down a datasheet for the 5v module here: https://www.alldatasheet.com/datasheet-pdf/pdf/606479/DELTA/S36SE05003NRFB.html (https://www.alldatasheet.com/datasheet-pdf/pdf/606479/DELTA/S36SE05003NRFB.html) The specifications don't look too bad but I'd be inclined to test them for noise and ripple before committing myself to using them in a replacement PSU. Those +/-15 volt modules appear to be versions of the Murata modules as per the following pdf: https://power.murata.com/datasheet?/data/power/bei15.pdf. (https://power.murata.com/datasheet?/data/power/bei15.pdf.) According to this page: https://power.murata.com/bei15-150-q12n-c.html (https://power.murata.com/bei15-150-q12n-c.html) they seem to have a 100mV ripple and noise rating (fairly typical for higher voltage output dc-dc converters).

 The important points of difference between the original smpsu board and a replacement mains voltage transformer based one using these modules is the elimination of the massive amounts of directly emitted RFI by the original mains smpsu and the amenability to additional low pass filtering of the noise and ripple of these modules (the opamps' own PSRR will largely take care of what noise and ripple remains on the voltage rails). The directly radiated switching hash from the original smpsu board which swamps everything can't be so conveniently disposed of by the on board opamps' PSRR.

 If you think you can easily solve the noise and ripple issue with cheap AM1117 LDO ICs, think again! For this trick to work, you'll need special LDOs designed to reject noise and ripple into the low MHz region - your standard off the shelf AM1117s just ain't going to cut the mustard for this job. :(

=============================================================================================
[EDIT 2020-02-22]
 I've just done an ebay search on those +/-15v modules and got this single hit https://www.ebay.co.uk/itm/1pcs-BEI15-150-Q12N-C-Murata-Murata-Power-Solutions-Isolated-DCDC/352744225236?hash=item522131b9d4:g:iGUAAOSwigxdR9Cb. (https://www.ebay.co.uk/itm/1pcs-BEI15-150-Q12N-C-Murata-Murata-Power-Solutions-Isolated-DCDC/352744225236?hash=item522131b9d4:g:iGUAAOSwigxdR9Cb.) By their deluded reckoning, you've got a tad more than 635 Australian dollars' worth in just those modules alone (around 325 quid's worth)  :wtf:

 The 5v modules are more reasonably priced at just $15.71 each by Octopart... Hmnn, I wonder if they do the 15v modules? Indeed they show a whole bunch of distributor prices at or around the $32 mark which makes X-On Electronic Services a bunch of (deluded - they seem to think they have a monopoly on these parts) piss taking wankers imho. More realistically, you seem to be in possession of around 270 dollars' (American) worth in dc-dc modules in total (assuming the photo represents your complete collection). Still a respectable return on your dumpster diving exploit.  ;)
=============================================================================================

JBG

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Miti on February 23, 2020, 01:18:13 am
[More realistically, you seem to be in possession of around 270 dollars' (American) worth in dc-dc modules in total (assuming the photo represents your complete collection). Still a respectable return on your dumpster diving exploit.  ;)
=============================================================================================

JBG

Add 2 GPS modules priced at $39.95 each, about 80 Li-Po batteries Zeus 2400 mAh, 4 brand new LCDs 800x480 LVDS, pressure sensors, mini vacuum pumps, and many more small things. Not too long ago I found some scrapped boards and I recovered 20+ genuine Ublox Neo M8T modules.
Now if only I could sell them...  :palm:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: nctnico on February 23, 2020, 03:11:39 pm
If you think you can easily solve the noise and ripple issue with cheap AM1117 LDO ICs, think again! For this trick to work, you'll need special LDOs designed to reject noise and ripple into the low MHz region - your standard off the shelf AM1117s just ain't going to cut the mustard for this job. :(
There is a very simple solution for that: use an RC filter in front of the LDO. The resistor will also help to dissipate some of the energy lost in the LDO.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on March 12, 2020, 08:54:46 pm
Borked again!!!!!!

My FY6600 which came with V 3.0 which as is well known borks itself.  I received a replacement front panel with V 3.1 (long after V 3.2 was out and probably V 3.3).

Another member of the forum asked if he should buy an FY6600  for a project which  needs 2 Vpp into 50 ohms.  So I hooked my FY6600 up to a DSO, checked the output level, put a 24 dB attenuator on the input to my HP 8560A spectrum analyzer.  But I didn't get a signal.  Reconnected to scope, no signal.  Connected my Keysight 33622A to DSO.  DSO is fine.

I no longer get a sine drawn on the display.  But none of the other waveforms work either even though the display shows them.  I've done all the usual power cycle, reconnect cable stuff.  No joy!

At this point I have spent 100x more time fixing FY6600 issues (original 2 wire mains and V 3.0 FW) than I have using it.

So if anyone from F***Tech is reading this, do you think I should recommend  someone buy your product?  If so why?  I'd be more inclined to recommend it to a bitter enemy, but there is no one I hate that much except F***Tech.

Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on March 12, 2020, 09:26:05 pm
If you think you can easily solve the noise and ripple issue with cheap AM1117 LDO ICs, think again! For this trick to work, you'll need special LDOs designed to reject noise and ripple into the low MHz region - your standard off the shelf AM1117s just ain't going to cut the mustard for this job. :(
There is a very simple solution for that: use an RC filter in front of the LDO. The resistor will also help to dissipate some of the energy lost in the LDO.

 Hi nctnico,

Apologies for the delay in responding but that recently completed basic DIY GPSDO I mentioned had been holding up a frequency injection locking add on project for my already very much modified FY6600 since May of last year and I had resumed this project to the exclusion of almost all else once I finally, and at long last, had a working GPSDO to play with.

 For anyone interested in locking their already upgraded to an OCXO FY6600 or 6800 generator to an external 10MHz reference, you can check out my Topic thread: Injection locking the 10Mhz OCXO to external reference (upgrading a FY6600) posting here: https://www.eevblog.com/forum/chat/injection-locking-the-10mhz-ocxo-to-external-reference-(upgrading-a-fy6600)/msg2418711/#msg2418711 (https://www.eevblog.com/forum/chat/injection-locking-the-10mhz-ocxo-to-external-reference-(upgrading-a-fy6600)/msg2418711/#msg2418711)

Returning to the matter in hand, using an RC filter is not a bad idea, especially when dealing with critical low current demand areas of a system that need to be kept isolated from the switching noise of a bulk power supply. A major plus point for the use of a resistor in place of an inductor is the avoidance of self resonance in a filter that's expected to deal with switching noise components that could extend to 100MHz or more.

 When I was deciding how to power my little GPSDO, I looked into the pros and cons of using LDOs with a buck converter powered from cheap commodity smpsu wallwarts in the 9 to 19 volts dc range and ultimately decided to forego the (in my case dubious[1]) benefit such an arrangement might bring.

 Since everything runs off a 5vdc supply (actually 5.16v), including the 13MHz OCXO, I'd initially considered using a 7805 (or modern day equivalent) to handle the voltage conversion from a 9 or 12 volt wallwart, but swiftly decided against this on the grounds that it would complicate the mechanical construction with the need to bolt its heatsink tab to the aluminium case as well as nearly double up the energy consumed with a 9v wallwart and more than double it in the case of a 12v supply.

 All of this energy input needs to be dissipated within the confines of a small 50 by 100 by 112mm extruded aluminium box that I'd prefer not  to compromise its RF screening properties any more than was absolutely necessary by riddling it with ventilation slots.

 Also, I was concerned about the indifferent voltage regulation of the AMS1117-5 used on the solderless breadboard psu board (YwRobot MB102) compared to the boost converter used in the Poundland 1200mA powerbanks with which I'd been testing the CQE 13MHz OCXO to determine whether it was a 12 or 5 volt unit I'd acquired for cheap (I couldn't track down a datasheet for this particular model but the search had lead me to a cheap supply of 12v 10MHz CQE OCXOs :D)

 I decided in the end to use the buck converter on its own to directly create the 5 volt supply and do away with any further complication. A bit of LC filtering reduced the 25mv p-p noise and ripple to less than 10mv with additional filtering for the OCXO and the GPS module making the need for any LDOs redundant in this case. Since the modestly insulated OCXO only consumes around 850mW[2] or so once warmed up, the total input power in the 7 to 20 volt range remains within 20mW or so of 1.8W (just under 3W mains voltage input to the 9 or 12 volt wallwarts I've used to power it up). Power supply noise and ripple doesn't appear to be an issue in this case so I'm quite pleased with the result.

[NOTES]

[1] I figured the extra heat penalty of allowing another 1.5 volts margin for a pair of LDOs (one for the OCXO and GPS module - 180mA warmed up, the other to serve the logic gates involved in converting the 13MHz to 10MHz and phase locking at 100KHz, also another 170 to 180mA) just wasn't worth the trouble, especially when there was every chance of poorer voltage regulation with load and temperature compared to that of the buck converter I'd chosen.

 I might have been able to reduce the load on the logic supply by some 30 to 50mA but the 74HC193 ICs just just don't seem to have the cojones of the old skool 74193 I was obliged to use to divide the 26MHz (clock doubled 13MHz OCXO output) to get the minimum frequency needed by the 2nd 3N502 clock multiplier I used to multiply the resulting 2MHz back up to the 10MHz sine wave reference I needed. Relying on additional LC filtering just seemed the better solution in this case.

[2] This 13MHz square wave output OCXO draws a warm up current, limited to 280mA which ultimately settles down to 190mA @4.82v after some seven minutes of warm up time which is reduced to a less agonising 5 minutes delay on a 5.16v supply. Wrapping it in a sponge rubber 'overcoat' knocks some 20 to 30mA off the at temperature operating demand.

 What had made me decide that it was a 5 volt version was the fact that for each volt increase on the Vcc pin up to a maximum test limit of 7.5v, results in an extra volt on the p-p output voltage, a trend that if continued to a 12v supply would result in (the never specified for any OCXO I'd ever seen datasheets for) of 11v p-p output.

 All the signs were that the oscillator was being powered directly off the incoming Vcc rather than via an LDO of any sort and although cmos can allow logic levels of 10 volts or more, this seemed a rather unlikely scenario so I decided not to push my luck any further than I already had and assume it to be a 5 volt unit (at 5 volts, it had proved stable enough without my taking any further risk in burning it out on a full 12 volt supply).

 However, the 12 volt 10MHz examples I have are, rather curiously, also limited to a maximum heater current of 280mA which of course drops to a lower (uninsulated, at temperature) current of circa 90mA which leads me to reconsider my decision to treat the 13MHz example as a 5 volt unit (especially since I'd been able to get the 12v units to output from a 5v supply, albeit with an even longer delay to start actually generating a recognisable sine wave output than the 13MHz unit had taken on a 4.82v supply). I may experiment further at a later date if I ever find any evidence that any OCXOs with 10v p-p cmos logic level outputs were even manufactured but, for now, I think I'll leave this sleeping dog to lay undisturbed lest it bite me in the backside for my trouble.

[EDIT 2020-08-12]

 Just to update the record, today, after finally commissioning my MK II GPSDO using a 12v 10MHz CQE OCXO powered from a 97% efficient 5v to 12v boost converter fed from the 5.34v output of a 3A rated mini 360 buck converter (allowing me to retain the option of 6.8 to 24 volt DC power sources of its MK I predecessor), I opened the MK I up to isolate my "Five Volt" CQE 13MHz OCXO to run some voltage tests which I hadn't dared to run for fear of smoking it with a 12 volt 'over-volting' event.

 It turns out that this is also a "Twelve Volt" part that just happened to be sufficiently obliging to produce a stable output (after a protracted 7 or 8 minute warm up delay) from as little as 4.82 volts (I was actually using a 5.17v supply rail in the MK I).

 I'd been harbouring a sneaking suspicion for the past few months that my "5V" OCXO was actually a "12V" one in disguise - the same 280mA peak heater current limit during warm up and the 'unregulated two thirds of the input voltage' on its Vref pin (which finally stabilised at 5.114v once the input supply rail started going north of the 10.8v mark). Just for good measure, I ran the supply rail up to 14 volts using a 0 to 32v 10A bench supply I hadn't possessed at the time I'd purchased my 'precious' one and only 13MHz OCXO for which I hadn't been able to find any voltage data for.

 The only good thing about strip board construction with a 13MHz OCXO generating a 10MHz reference is that the noise from even a noisy switching buck converter pales into insignificance, drowned out as it is under a storm of TTL rail supply noise generated by the times two - divide by 13 - times five stages required to arrive at 10MHz using 3N503 clock multiplier chips with a 2MHz minimum input frequency requirement.

 The MK II is essentially the same design but sans any 13 to 10 MHz TTL jiggery pokery since it conventionally uses a 10MHz OCXO and is built onto a single sided copper clad board to keep ground noise to a minimum. In spite of the use of an extra dc-dc converter to generate the 12v rail from the 5.34v rail, the MK II actually consumes some 400mW less power (1.4W versus the 1.8W of the MK I) as a result of eliminating all of the 13 to 10MHz TTL conversion circuitry.

 I was going to restore the MK I but having to undo most of the connections to the 13MHz OCXO to keep the rest of the circuit isolated from the 12v test voltages, I'm now going to strip it down for the not so cheap and cheerful ICs I'd had to use in this design (3N503 clock multipliers ain't cheap!  >:( ) and the 13MHz OCXO will be kept as a "Keepsake" memento of my very first experiences with OCXOs and diy GPSDOs.

 After the experience gained in proving that a 13MHz OCXO could be used in a 10MHz GPSDO, I don't see any further use for it. By the time I'd come to the actual construction of my MK I, I had already gotten hold of seven of the 10MHz 12v CQE OCXOs but having developed a working circuit to use that "Five Volt 13MHz" OCXO, I'd decided to go ahead as planned and see it through to the bitter end, especially as I'd had it in the back of my mind that it would save the (in hindsight over-rated) "complication" of safely mixing 5 and 12 volt supply rails on the one PCB.

 I'm now awaiting delivery of an EFRATOM LPRO-101 and any future DIY GPSDO projects will be microcontroller based designs such as the Lars one or something along those lines, hence my stripping the MK I down for spares. It had served its purpose well as a test bed to reveal the limitations of a single frequency navigation class of GPS receiver module driving a hardware PLL controlled OCXO - the MK II is using a u-blox M8T which is better but still far from perfect, hence the LPRO-101 purchase to see just how far from perfect my MK II actually is.

 And, to think that all of this was sparked off by my desire to improve the frequency stability and accuracy of my FY6600-60M AWG. :)
 

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: playit on March 16, 2020, 11:20:44 am
hi i have dg41cn intel mobo, changed ram speed in bios ,then it never got up ,no matter what i did, my bios chip is W25Q16BVAIG 1023 ,can i erase and flash it to solve this ,can i do that with eeprom ch34 1a  programmer,thanks
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: engrguy42 on March 23, 2020, 12:10:25 pm
Apologies for being the new guy, waltzing in here and asking newbie questions, but...

I was wondering if some kind soul could give a brief summary of what are the big issues with this signal generator (and presumably the handful of re-branded equivalents) that have resulted in 87 pages of discussion over the last 3 years? It sounds like there are some major issues with firmware and/or grounding or something, requiring some to lash out at the vendor to get off their butts and fix it?

I ask because I have one of the re-branded versions and it seems to work fine. Surprisingly capable, IMO, for a $80 device, including some very surprising PC software that seems to do a nice job.

And while I'm the last guy to ever fall into the TL;DR camp, in this particular case I can't really justify reading 87 pages of stuff for an $80 device.  :D 

Thanks much to any kind soul who can assist.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: alexm58 on March 23, 2020, 11:14:35 pm
Apologies for being the new guy, waltzing in here and asking newbie questions, but...

I was wondering if some kind soul could give a brief summary of what are the big issues with this signal generator (and presumably the handful of re-branded equivalents) that have resulted in 87 pages of discussion over the last 3 years? It sounds like there are some major issues with firmware and/or grounding or something, requiring some to lash out at the vendor to get off their butts and fix it?

I ask because I have one of the re-branded versions and it seems to work fine. Surprisingly capable, IMO, for a $80 device, including some very surprising PC software that seems to do a nice job.

And while I'm the last guy to ever fall into the TL;DR camp, in this particular case I can't really justify reading 87 pages of stuff for an $80 device.  :D 

Thanks much to any kind soul who can assist.

I'm rather a new guy here, but I have followed this thread for a year or so, and read all the earlier posts.

TL;DR summary:

There were some major issues with the early versions, which were eventually (mostly) fixed by the manufacturer.

There are also a number of mods which can be made to significantly improve the performance of the unit for relatively little cost.

There are a few rants at the manufacturer, but mostly it's about fixing the problems of the early units, and improving performance.

HTH :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: engrguy42 on March 23, 2020, 11:22:21 pm
Thanks much. I sure appreciate it.

I've got the Koolertron version (pretty much identical to the Feeltech and others), and I've been quite impressed at what you get for 80-90 bucks. Even the USB/PC software was VERY surprising, allowing you to build waveforms and stuff. It actually works.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on March 29, 2020, 09:08:10 pm
Thanks much. I sure appreciate it.

I've got the Koolertron version (pretty much identical to the Feeltech and others), and I've been quite impressed at what you get for 80-90 bucks. Even the USB/PC software was VERY surprising, allowing you to build waveforms and stuff. It actually works.

 From what I've been able to glean off the interweb, this Koolertron branded Junctec GH-CJDS66 is a totally different beast to the Feeltech FY6600 that's been the subject of many many different modification projects in this topic thread. If this is still the case, as it appears to be (for all I know, it's just possible that Koolertron may have recently decided to abandon the Junctec version and sell the FY6600 as an alternative rebranded offering instead), then virtually everything that has been discussed in this thread simply won't apply.

 The most obvious distinction between the FY6600 (and its successors) and the Koolertron GH-CJDS66 is the use of an external 5V 2A rated wallwart to power it via the customary co-axial DC jack, eliminating not only the regulatory need to get the various safety certifications for an appliance powered by an internal Class II smpsu but also the expense (as cheap as the unit used in the Feeltech products was) of a 3 rail smpsu board.

 The other most striking difference between the Koolertron version and the Feeltech units is the Koolertron's use of a 10 digit frequency display versus the 14 digits of the more cramped Feeltech's display. If yours matches the descriptions above, then you'll most likely only be able to get general help and advice from this topic thread.

 JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: ThaZ on April 01, 2020, 06:12:44 pm
I've version V3.3 as firmware in the FY6600-60Mhz  ::)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: darkspr1te on April 04, 2020, 12:06:13 pm
Hi All,
 I'am asking if someone could give the tl;dr on the current status of firmware dump, I was asked by another forum user to look into this as I recently was able to dump a locked stm32f103r8 device and can confirm it works on on 105/107 devices too, How ever it's not perfect and requires certain things to hand tool wise to achieve.
I would be will to assist with these methods if we still have nothing on the unit.


darkspr1te

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DC1MC on April 04, 2020, 04:44:51 pm
Well, as I am the "culprit" for asking ;), I will give you a status update:

1) There is no public unencrypted firmware dump of the original firmware.

2) There are a couple of encrypted upgrade firmwares, but because the upgrade function was not available on the early models (the ones with actually bad firmware bugs) the buyers had to either pocket the loss or insist, and, in some cases, being given a replacement front panel or a replacement programmed chip.

3) A number of community members, the shining star being fremen67, have devised alternative firmware to be used with some Arduino compatible boards (aka "Blue Pill").

4) A full firmware dump and the extraction of the encryption key to decode the updated firmwares will allow the people that still have older, non-upgradable units to update to the current version of the firmware.

5) Also, the possibility to save and restore the factory firmware will open the unit for experimentation and improvement.

6) I have such a unit and happily do any soldering and experiments that you require to extract the fw if possible an help time passind during the quarantine.

 Cheers,
 DC1MC
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: up8051 on April 04, 2020, 06:52:14 pm
Here are information how to dump STM32F1:
https://blog.zapb.de/stm32f1-exceptional-failure/
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Prehistoricman on April 05, 2020, 12:06:30 pm
Here are information how to dump STM32F1:
https://blog.zapb.de/stm32f1-exceptional-failure/
Nice article but the author is very bold about this being the first non-invasive attack. The paper I linked found success in using power glitching to bypass the bootloader check. Power glitching is non-invasive, right?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: up8051 on April 05, 2020, 01:08:30 pm
The paper I linked found success in using power glitching to bypass the bootloader check. Power glitching is non-invasive, right?

Could you please provide the link?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: masterx81 on April 05, 2020, 06:38:16 pm
Hi!
Someone have found a way to fix the attenuation network impedance for low ranges (less than 500mv)?
I see that during attenuation there is active the 49.9ohm resistor after the opa, then the network of 100-510-100 resistors, giving 2 voltage dividers, one 49.9/100 and the other one 510/100. I have an fy6900 and have the same problem (plus a pcb design error so that the 2 100ohm output resistors after the ths are not in parallel, but this is another story :palm:)
Thanks!
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Prehistoricman on April 06, 2020, 04:45:50 pm
Did you guys ever extract the built-in firmware?

I found this paper that extracted firmware from an STM32F1 series MCU 'easily':
https://tches.iacr.org/index.php/TCHES/article/download/7390/6562/
Page 9/10 (207/208)

Sounds like a fun project.

Edit:
And by an interesting coincidence, this paper specifies a FeelTech unit for generating their attack glitches.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Nikolay_1984 on April 20, 2020, 05:21:53 pm
hello help repair the FY 6600 after a failed firmware. If enabled, only two green LEDs on the generator channels light up and nothing else is lit and the power button does not respond in Windows 10. The device is defined as a USB CH340
 com port is not active in the port management program, tell me how to repair this device.
I understood the firmware in altera
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Noy on April 21, 2020, 08:36:04 pm
Hi,
which kind (size, Material) and value of resistor should i use to connect GND and PE?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jchw4 on April 22, 2020, 03:02:41 pm
Another PS mod. Original one just died, so I had to invent something quick and dirty.

I had old laptop power adapter and a few cheap dc-dc buck modules ($0.7 delivered), so you can see the result. One is connected according to http://www.ti.com/lit/slyt516 (http://www.ti.com/lit/slyt516) to get negative voltage.
The output now is much more stable, so it's an upgrade for about $2 ;)

If somebody is going to follow me, note that I disassembled the original adapter. Don't do it! I wanted to save cables, which turned out to be a bad idea. Disassembly is messy, everything is glued inside and it's very easy to damage something. Just cut the two cables.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: FeelElec on April 26, 2020, 03:42:07 am
hello help repair the FY 6600 after a failed firmware. If enabled, only two green LEDs on the generator channels light up and nothing else is lit and the power button does not respond in Windows 10. The device is defined as a USB CH340
 com port is not active in the port management program, tell me how to repair this device.
I understood the firmware in altera

Dear customer, please describe your problem in detail. You can send an email to sales@feelelec.com, and we will actively solve the problem for you.

FeelElec
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on April 26, 2020, 09:28:02 pm
Hi,
which kind (size, Material) and value of resistor should i use to connect GND and PE?

 Hi Noy,

 Apology for the late reply but this looks like a question intended for the original author of the "Lo-Z static drain resistive connection between the PE and the BNC ground" modification, which would be my good self.  ;)

 The "Lo-Z static drain" resistance value being, in this case, a matter of 3K3 to 10K rather than the typical anti-static drain value of one or two megohms. A quarter or half watt rated carbon or carbon film or metal film (take your pick - it's not critical) 4K7 resistor will suffice and allow DC offsets of up to 32 and 48 volts respectively between PE and BNC ground.

 I recently converted three UK wallwarts with a similar half mains touch voltage suppression mod using 4K7 ohm resistors so had a reason to calculate the maximum DC offset voltage that could be applied between the 0v connection and mains earth.

 In two of these mods, I'd simply used gutted wallwarts which happened to have proper (but unused) earth pins to rehouse the innards of a 12v wallwart and a 20v wallwart that had come supplied with an Aldi 4 watt LED desk lamp not so blessed with earth pins. I'd already gutted these older wallwarts and kept their housings for just such jobs as this.  >:D

 For those of us living in regions where the use of an earthed wall socket is mandatory such as here in the UK, the next time you're going through your box of ancient wallwarts, keep hold of any with a real earth pin since they've now become as precious as gold dust in the quest to eliminate the rather cheap 'n' nasty half mains voltage tingle of the later and current models that rely on a plastic earth pin merely to act as a safety shutter opener on such sockets.

 The other low standby power 12v 1A rated wallwart was already blessed with a real earth pin (unused) so only required to be cracked open in order to fit a quarter watt 4K7 metal film resistor between the accessible and solder-able earth pin contact[1] and the 0v rail of its 12v DC output.

 The reason for this sudden spurt of wallwart modification activity was my experiencing the ESD induced lockups of my FY6600 as a result of grounding it to an already grounded DUT or DSO prior to my solving this half mains voltage on the BNC grounds issue. Now I was seeing the same effect but this time as a result of the half live mains voltage of the 12v wallwart powering my GPSDO.

 Although it's a simple enough matter to arrange a separate GPSDO earth connection, independent of its 7 to 24 volt dc supply connection, I'd decided that I'd had more than enough of this nonsense of wallwarts cursed with this half live mains voltage issue and it was high time that I actually did something about it.

 The desk lamp wallwart had been an annoyance for some considerable time (LV current carrying telescopic arms making the use of such wallwarts unacceptable in this case) so, quite naturally, it  had gotten included in my 'de-tingling' of the primary and spare 12v  GPSDO wallwarts project.

[1] Solderable they might be but you do need to take precaution against softening the plastic whilst applying some 70 watts' worth of heat for the 20 to 30 seconds typically required to form a reliable solder joint using lead/tin solder. I used a broken digitally programmable on/off timer switch held by its earth pin in a vice into which I plugged the wallwart to act both as a heatsink and as a stabilising jig to prevent the earth pin canting out of alignment (I knew I'd eventually get some use out of that crappy timer switch if I held onto it long enough  :) ).

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: xzswq21 on May 09, 2020, 12:19:21 pm
is there any upgraded FY6600 Function generator? I want to buy one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Trader on May 16, 2020, 07:07:04 am
is there any upgraded FY6600 Function generator? I want to buy one.

Check the FY6900
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on May 17, 2020, 01:43:38 am
I had one of the NEC output relays fail in my generator which I had for only a year and haven't used much. Seems a bit surprising, unless NEC is not really NEC.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on May 17, 2020, 02:25:12 pm
is there any upgraded FY6600 Function generator? I want to buy one.

Check the FY6900

 That took long enough! ;D

 BTW, I second that suggestion.

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on May 17, 2020, 02:37:15 pm
I had one of the NEC output relays fail in my generator which I had for only a year and haven't used much. Seems a bit surprising, unless NEC is not really NEC.

 Well, to quote (or at least paraphrase) Forest Gump, "Shit happens."

 Even the the most expensive of high quality components can fail (just ask NASA) and relays being 'relays', this doesn't necessarily indicate the use of a fake or counterfeit part. NEC relays can fail, just not so frequently as the more cheaply made versions is all. Just be thankful that it lasted a whole year before failing.  >:D

JBG
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on May 17, 2020, 04:37:41 pm

 Even the the most expensive of high quality components can fail (just ask NASA) and relays being 'relays', this doesn't necessarily indicate the use of a fake or counterfeit part. NEC relays can fail, just not so frequently as the more cheaply made versions is all. Just be thankful that it lasted a whole year before failing.  >:D

JBG

BTW Johnny my Last mod with the 2 x 10pf Caps on the op amp worked wonders with signal Quality . . NEC relay that's a blow out news.

Well I do hope NASA is Not using Feeltech / FeelElec Equipment other wise we are going to have all sorts of Stuff falling out of Orbit  :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on May 17, 2020, 10:16:13 pm
I  was messing with my FY6800 mumbling to myself .
The wife was standing behind me .
  She reached over and unplugged it and said " I can fix it.. I know what's wrong.  :-*
 I thought what the heck .. Don't mess with a woman .
   Five minuets later she returns with a grin ..  "I told you I could fix it !! "
 OK. Show Me .  :-\
 Pointing to the back Door .. See I have fix the Jitter .. the door is now quiet  . "No more noise from the Wind"
  O Thank you G-D for creating  Woman  >:D

  Great Now I have an excuse to buy a Aglient   :-+ :popcorn:  ..

  I said I would find a solution. But this One, completely slipped my mind .


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on June 13, 2020, 05:09:11 am
Once I started playing with my FY6600 to replace the NEC relay, I thought would be nice to replace the switching power supply as well. There has been a lot of discussion of various power supply options here, but I noticed this triple +5V, +/- 12-15V low-leakage linear power supply is available inexpensively:
https://www.ebay.com/itm/SL-Power-Electronics-Linear-Power-Supply-MTLL-5W-A-5V-5A-12-12V-NEW/172432850496 (https://www.ebay.com/itm/SL-Power-Electronics-Linear-Power-Supply-MTLL-5W-A-5V-5A-12-12V-NEW/172432850496)
[attach=1]
It's a bit underpowered, rated only for 0.1A for +/- 12V, but fits nicely in the box. I measured the current limit is actually about 130 mA, which is sufficient for most cases. Reducing the current sense resistors from 3 Ohm to 1.5-1.8 Ohm increases the current to 250 mA without introducing any ripple.

Here is the spectrum of the 10 MHz sine output (taken with Owon XDS3062A scope), showing that linear supply gets rid of some spikes in the spectrum. The box runs a little hot, so probably putting a small fan in there would be a good idea.
[attach=2]
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: pizzigri on June 20, 2020, 06:30:20 pm
Another PS mod. Original one just died, so I had to invent something quick and dirty.

I had old laptop power adapter and a few cheap dc-dc buck modules ($0.7 delivered), so you can see the result. One is connected according to http://www.ti.com/lit/slyt516 (http://www.ti.com/lit/slyt516) to get negative voltage.
The output now is much more stable, so it's an upgrade for about $2 ;)

If somebody is going to follow me, note that I disassembled the original adapter. Don't do it! I wanted to save cables, which turned out to be a bad idea. Disassembly is messy, everything is glued inside and it's very easy to damage something. Just cut the two cables.

Hi! I’m really sorry, however in the TI document linked, after the phrase “ where s is the complex Laplace variable and He(s) repre- sents the higher-frequency...” and a host of equations, I got quite lost. I’m a hobbyst and trying to learn, but not to the point of learning at 50+ this level of math.... could you please post a wiring diagram, as obtaining a neg rail from standard buck converters would be incredibly helpful not only in this application but generally as well? I would really appreciate it.
By the way, I want to publicly thank both JBG and Masterx81 for their help and incredible patience in helping me in the PSU mods and TXCO replacement sourcing.
I sincerely felt that the level of questions I asked both of you guys was really too low for the very high level of competence and skill this forum is known for, and that is why I sent you guys PM’s.
To contribute in some way to the thread, here’s the thermal images of the main board and the psu board. On the PSU there is a frankly unsettling resistor (R3) that is running really hot, about 93 celsius.
On the board, the three voltage regulators near the usb connector, are in dire need of a heatsink. The small and inexpensive ones built for the Raspberry are perfect for this.
The rest of the board is running around 40or so celsius, and I think can go as is - see the other two images, one with the Cyclone, and the other of the components near the opamps under the big existing heatsink.
 Boy, I’m learning sooo much just by following this one thread....

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on June 20, 2020, 08:02:02 pm
Once I started playing with my FY6600 to replace the NEC relay, I thought would be nice to replace the switching power supply as well. There has been a lot of discussion of various power supply options here, but I noticed this triple +5V, +/- 12-15V low-leakage linear power supply is available inexpensively:

It's a bit underpowered, rated only for 0.1A for +/- 12V, but fits nicely in the box. I measured the current limit is actually about 130 mA, which is sufficient for most cases. Reducing the current sense resistors from 3 Ohm to 1.5-1.8 Ohm increases the current to 250 mA without introducing any ripple.

Hi if your interested I totally rebuilt my power supply on the 5volt side I use the 2x  CVCC buck converters they are a $ more but they run perfectly well and very little noise .Plus I set the CC side to 500 ma & 1200ma on the OCXO. I did put 0.1pf ceramic and 470uf ripple class cap . (red) not viable on the pictures.
Also I put a shield cover that fits over the OCXO board to thermal isolate it.
the whole thing with the OCXO draws 8 Watts .
  On the mains side 8 watts is about 0.04 Ma @ 240vac .
   Ripple was just readable on 10mv on my scope.
Also found using 20Mhz OCXO x2.5 reduced the the jitter to 2ns .
 Opposed to 10Mhz x5 as the PLL also multiplies the jitter as well.
 Its Now reads 0.02 PPb   :)
RNS
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Bad_Driver on June 22, 2020, 08:17:39 am
Thanks for sharing this result of your PSU-Modification.

Once I started playing with my FY6600 to replace the NEC relay, I thought would be nice to replace the switching power supply as well. There has been a lot of discussion of various power supply options here, but I noticed this triple +5V, +/- 12-15V low-leakage linear power supply is available inexpensively:
https://www.ebay.com/itm/SL-Power-Electronics-Linear-Power-Supply-MTLL-5W-A-5V-5A-12-12V-NEW/172432850496 (https://www.ebay.com/itm/SL-Power-Electronics-Linear-Power-Supply-MTLL-5W-A-5V-5A-12-12V-NEW/172432850496)
(Attachment Link)
It's a bit underpowered, rated only for 0.1A for +/- 12V, but fits nicely in the box. I measured the current limit is actually about 130 mA, which is sufficient for most cases. Reducing the current sense resistors from 3 Ohm to 1.5-1.8 Ohm increases the current to 250 mA without introducing any ripple.

Here is the spectrum of the 10 MHz sine output (taken with Owon XDS3063A scope), showing that linear supply gets rid of some spikes in the spectrum. The box runs a little hot, so probably putting a small fan in there would be a good idea.
(Attachment Link)

After reading for weeks now all the postings of  FY66/68/69 I think it is one of the few (or the only one?)
with a before/after comparison. There are many ideas and projects on PSU-improvement here but I believe
that this makes only sense when you can measure the results!
I'm improving these days my PSU to get the additional power for
an OCXO-Mod (with my FY6900) and think about a before/after-measurement setting.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on June 22, 2020, 03:25:32 pm
Hi We all spent many hours of research.
Like I chose the 20MHZ OCXO opposed to the 10Mhz .
2 reason 1st they are cheaper for high PPb  and I reconnected if you multiple anything you also multiply any errors as well  . And I found that dividing my 20Mhz 0.02 PPB OCXO by 2 from the PLL pin 4 buffered out . I get
10Mhz reference signal for calibration which is 0.01 PPB which has to be good enough for any Nerd standard.
and times 2.5 of the 20Mhz give me only a 2ns jitter apposed to 4ns of the original . Which at 25mhz square wave
is pretty good plus I can push it to 28MHz before it fails to be a square wave. Sine is ok all the way to 60Mhz.  :-+
Also put a few tautanium 10uf caps on all the power lines & ferrite rings over the ocxo supply.
The Relay have a contact noise place a 100pf ceramic or smaller on the relay inputs from the op amp line.
the cap can be between 10 - 100pf depending on the relay . only the color is the same the contact resistance
varies from relay to relay. This will give a cleaner Square wave & also the sine .

The Power supply as with most was a small challenge I used the transformer from an old dual tape deck from a
PA system that was binned . so it had the metal screening plus a copper screen raped round the winding.
If you are going to buy I would go for a torridial transform that have a really good performance.
There is good stuff that can be pulled from old audio devices .  :-+
The Link to that power supply looks good as well but it is only 5W  .
 IF you are going to add more mods My FY6800 actually uses near 8W .After all mods ..
 
.. I don't have a before Pictures as my SMP failed within 2 hours of use.  The power supply totally crispy .. :scared:
 These are after all mods @ 40Mhz sine .
 Mains ripple is about 40 uv . but that maybe lead or connection noise.

Have Fun  :popcorn:
RNS

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Bad_Driver on June 23, 2020, 09:56:01 am
Hi Maxwell

I tried to repeat your measurement with my Oscilloscope (Siglent SDS 2000X+ 500 MHz) with my FY6900 before my scheduled
PSU-improvement. As far as possible I used your settings (50 Ohms termination)

You find all settings in the screenshot (Windowing is Blackmann). The O is "only" 10 bits. What FFT-Windowing have you used?
It looks different from youre findings. The FY6900 (with 5.6 k drain resistor between outlet earth and grounding as only modification)
has a different PSU than FY6600, may be this can be the reason as well.

I learned a lot during the last weeks about O-FFT with the help of https://www.edn.com/ffts-and-oscilloscopes-a-practical-guide/ (https://www.edn.com/ffts-and-oscilloscopes-a-practical-guide/)
and that the combination of  the weak BNC-connectors of the FY and cheap Coax-Cables result in nonsens   :bullshit:

I repeated the measurement of Ebel0410 (post #281 in this topic) which he has done with a R+S SA with my O's FFT and the results
matched surprisingly good. If someone is interested I can provide my measurements. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: maxwell3e10 on June 23, 2020, 11:41:56 am
For FFT measurements I use the scope to acquire the maximum number of points at maximum sample rate (40M points at 500 MS/sec with 12 bit for Owon XDS3062A) and then transfer to computer for analysis with Matlab. I used Kaiser window and scaled the FFT to give PSD relative to fundamental in 1 Hz width. You can see some other measurements here https://www.eevblog.com/forum/testgear/signal-quality-of-budget-waveform-generators/msg3047624/#msg3047624 (https://www.eevblog.com/forum/testgear/signal-quality-of-budget-waveform-generators/msg3047624/#msg3047624)
In particular, the broad peak near 25 MHz is due to the scope. But the white noise background level is pretty good.

My Fy6600 was initially completely not modified, so no grounding connection. One could see in the time domain some spikes from SMPS for low-level signals. With linear power supply there is still no ground connection and no spikes.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jchw4 on July 13, 2020, 04:47:19 pm
Another PS mod. Original one just died, so I had to invent something quick and dirty.

I had old laptop power adapter and a few cheap dc-dc buck modules ($0.7 delivered), so you can see the result. One is connected according to http://www.ti.com/lit/slyt516 (http://www.ti.com/lit/slyt516) to get negative voltage.
The output now is much more stable, so it's an upgrade for about $2 ;)

If somebody is going to follow me, note that I disassembled the original adapter. Don't do it! I wanted to save cables, which turned out to be a bad idea. Disassembly is messy, everything is glued inside and it's very easy to damage something. Just cut the two cables.

Hi! I’m really sorry, however in the TI document linked, after the phrase “ where s is the complex Laplace variable and He(s) repre- sents the higher-frequency...” and a host of equations, I got quite lost. I’m a hobbyst and trying to learn, but not to the point of learning at 50+ this level of math.... could you please post a wiring diagram, as obtaining a neg rail from standard buck converters would be incredibly helpful not only in this application but generally as well? I would really appreciate it.

You don't need math. Just look at the front of the Ti paper. Take your module and align it with the fist picture.

The module will have (V+,V-) In, (V+, V-) Out. You need to check with DMM that (V- In) (V- Out) are connected, so it's "GND" net on the first picture.
Then you have (V+ Out) (V- Out) and they are both marked on the illustration.

Now you need to align what you got from the previous step with the second picture.  Basically you rotate the result 180 degrees and label nets according with the new image. This will give you negative pole.

I.e common GND goes to module (V_out+), input(+) goes to module (V_in+) and you take -12V from module (GND).

There are a few caveats. First, the DC-DC converter may not start in this configuration. But as I just had the modules I decided to give it a try.
The paper mentions that in this arrangement the converter will have to supply twice the output current (P_out/V_in in case of laptop 19V to -12V should be less than 2, but I just rounded it to 2). But module is 3A rated and I guess that we are not  going to pull more than 1A in the worst case so it should be OK.
But you should check the voltages and currents after the assembly. And I guess that this module may not be actually 3A (I did not test it), but it should be cheap to replace when it dies.

Quote
By the way, I want to publicly thank both JBG and Masterx81 for their help and incredible patience in helping me in the PSU mods and TXCO replacement sourcing.
I sincerely felt that the level of questions I asked both of you guys was really too low for the very high level of competence and skill this forum is known for, and that is why I sent you guys PM’s.
To contribute in some way to the thread, here’s the thermal images of the main board and the psu board. On the PSU there is a frankly unsettling resistor (R3) that is running really hot, about 93 celsius.
On the board, the three voltage regulators near the usb connector, are in dire need of a heatsink. The small and inexpensive ones built for the Raspberry are perfect for this.
The rest of the board is running around 40or so celsius, and I think can go as is - see the other two images, one with the Cyclone, and the other of the components near the opamps under the big existing heatsink.
 Boy, I’m learning sooo much just by following this one thread....
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: RainerB on July 23, 2020, 11:00:05 am
I build a linear PSU for my FY6800 with some addons:

-  opto isolated USB Interface (4 pol connector with 5V for front board) (CH340G)
- 10 MHz OCXO
- 10 MHz distributor with 2 isolated sine wave outputs  (AD8055)
- 50 MHz output for fpga  (NB3N502)
- 6 pol connector for external controller board (Blackpill) (with digital poti and reference voltage for OCXO)


Two ldo regulators LM2941/LM2991 with +/- 13V output support the main board. Both can be disabled for power saving (future option).
A DC/DC converter generates 6V for 3 5V LDOs (TLV76750) :
1. Front board and optional controller
2. Main board (can be disabled for power saving)
3. OCXO and 10 MHz distributor (can be disabled for power saving)

The external controller is able to count the 10 MHz pulses with the help of 1PPS pulses and generate a controling voltage for the OCXO.
Option :
In future the external controller should drowngrade the front controller to a display and keyboard unit and take over current control job of the front controller.

This version works but has some mechanical bugs and minor electronical issues.

Therefore I'm working on version 2.0 at the moment:

- Fixing mechanical bugs
- Move the voltage reference and the  I²C controled digital eeprom potentiometer from controler board to the PSU board.
(After intial calibration the external controller can be removed )
- use SMA connectors for 10 Mhz and 50 MHz signals.
- add expansion connectors ?

Any comments welcome.
Regards
Rainer


Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on July 24, 2020, 09:33:10 am
Quote
I build a linear PSU for my FY6800 with some addons:

Welcome.
This looks very nice .. you made the PCB as well as it looks made to perfection .
The layout looks nice well thought out ..
Do you Have the circuit diagram ?   :-+
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: supertrabuco on July 25, 2020, 04:36:00 am
I build a linear PSU for my FY6800 with some addons:

-  opto isolated USB Interface (4 pol connector with 5V for front board) (CH340G)
- 10 MHz OCXO
- 10 MHz distributor with 2 isolated sine wave outputs  (AD8055)
- 50 MHz output for fpga  (NB3N502)
- 6 pol connector for external controller board (Blackpill) (with digital poti and reference voltage for OCXO)


Two ldo regulators LM2941/LM2991 with +/- 13V output support the main board. Both can be disabled for power saving (future option).
A DC/DC converter generates 6V for 3 5V LDOs (TLV76750) :
1. Front board and optional controller
2. Main board (can be disabled for power saving)
3. OCXO and 10 MHz distributor (can be disabled for power saving)

The external controller is able to count the 10 MHz pulses with the help of 1PPS pulses and generate a controling voltage for the OCXO.
Option :
In future the external controller should drowngrade the front controller to a display and keyboard unit and take over current control job of the front controller.

This version works but has some mechanical bugs and minor electronical issues.

Therefore I'm working on version 2.0 at the moment:

- Fixing mechanical bugs
- Move the voltage reference and the  I²C controled digital eeprom potentiometer from controler board to the PSU board.
(After intial calibration the external controller can be removed )
- use SMA connectors for 10 Mhz and 50 MHz signals.
- add expansion connectors ?

Any comments welcome.
Regards
Rainer


Hola, es un proyecto muy interesante, sobretodo los conectores y el control externo.

En un FY6900 seria interesante un proyecto semejante? Y sobretodo cambiarle la mini-fuente pulsada por una linial 5V, 1,5A?
Saludos y gracias
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: RainerB on August 17, 2020, 06:39:20 am
@Labrat101
@Attached are the shematics of version 2.0. (Some resistor values will be modified during first tests)

An eeprom poti for the OCXO voltage and an I²C IO expander are added on the board
I replaced some regulators with THT version to save space on the board and use a heat sink.
I add some sma connctors for HF signals.
Mechanical problems are fixed. (hopefully)

ToDo:
I have to add a connector for controller driven fan.

@ supertrabuco
Yo no hablo español

Not sure what you want to say. Google translator doesn't really help.

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on August 17, 2020, 10:56:49 am
@Labrat101
@Attached are the shematics of version 2.0. (Some resistor values will be modified during first tests)

An eeprom poti for the OCXO voltage and an I²C IO expander are added on the board
I replaced some regulators with THT version to save space on the board and use a heat sink.
I add some sma connctors for HF signals.
Mechanical problems are fixed. (hopefully)

ToDo:
I have to add a connector for controller driven fan.

@ supertrabuco
Yo no hablo español


Very impressive  you have given  a lot of thought into this .
 I Have found another Bug in my FY6800 and its the Cyclone chip .. I still can't get the jitter to hold stable . so I ran some test on the Cyclone vi and its has some faults
ie .. Its ether a fake or a reject version . From reading the Cyclone manual it has a internal DAC control on the input were the xtal enters . there are 4 inputs and are hardware
enabled .
 I enabled the pin and added another xtal as an experiment . it fails the test . also all the Jitter and frequency control of the cyclone is out of sinc on my chip.
 Which means the chip is not original . I don't know if this is the case with all the FY68.. or just a few .
  The original Cyclone chips do not have this problem .. I should have checked this earlier and not chased the rabbit down the hole .
 I guess I should have realized this.  :palm: :palm: How can they produce this unit with high quality or original chips for $80 and make a profit   :palm:

So I am going to buy the UNI-T  UTG962  which is far superior and I have not found any one who can say anything bad .. Other than it Just works out the box 

 If your project corrects some of the problems your chip maybe be a better version.  :-+

 Have fun and keep up the good work .  :-+
 :popcorn:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: RainerB on November 02, 2020, 01:13:40 pm
Version 2 is now ready.  The LDO's deliver 14V DC ( AC Input >=  200 V ) .
The isolated USB interface worked.
Ajusting of the OCXO with an external Controller and 1PPS from GPS worked.
My FY6800 has no internal frequency offset.
An ajusted TR5212  showed 10.000.000,0 Hz for the readward isolated 10 Mhz Outputs and for Output 1/2 when set to 10 Mhz.
If anybody is interessed in an empty pcb please let me know. I have 4 more here and no use for them.

Now I will add a pcb with an STM32F411 Blackpill  for adding some features :
- Fan controll
- OCXO ajusting with GPS
- Some Ham Radio functions e.g.:https://hamprojects.wordpress.com/2018/10/21/fy-6800-generator-as-beacon/ (https://hamprojects.wordpress.com/2018/10/21/fy-6800-generator-as-beacon/)
...

(Of course my modifications didn't fix the 4ns bug) 
Regards
Rainer

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: RainerB on November 02, 2020, 01:16:56 pm
I created a new backside with Freecad. The code is attached.

Regards
Rainer
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on November 02, 2020, 07:01:25 pm
Wow very nice work.

I abandoned my FY68** . as a total waste of Time . So I Locked it at 40Hz & fitted transistor to the output
 So it is now a 40Hz Cmos pulse Med Strobe . For my wife who suffers from dementia .
 At this stupid low frequency the jitter does not affect the daylight LED strobe .
 
   I have now the UTG962 works without fault without any jitter . Just love it .

All the best and Good luck .
 :popcorn:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: battlecoder on November 02, 2020, 08:22:28 pm
@Labrat101
@Attached are the shematics of version 2.0. (Some resistor values will be modified during first tests)

An eeprom poti for the OCXO voltage and an I²C IO expander are added on the board
I replaced some regulators with THT version to save space on the board and use a heat sink.
I add some sma connctors for HF signals.
Mechanical problems are fixed. (hopefully)

ToDo:
I have to add a connector for controller driven fan.

@ supertrabuco
Yo no hablo español

Not sure what you want to say. Google translator doesn't really help.

Wonderful job. Looks like a killer replacement for the puny supply that comes inside and I would definitely love to upgrade my FY6600 with something like that.

Btw, what @supertrabuco said is "Pretty interesting project. Particularly all the connectors and external control". Then he asks if it would be possible to do the same for the FY6900, and replace the small switching supply for a linear 5V, 1.5A one.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on November 02, 2020, 10:17:28 pm
Quote
@ battlecoder

Wonderful job. Looks like a killer replacement for the puny supply that comes inside and I would definitely love to upgrade my FY6600 with something like that.

Btw, what @supertrabuco said is "Pretty interesting project. Particularly all the connectors and external control". Then he asks if it would be possible to do the same for the FY6900, and replace the small switching supply for a linear 5V, 1.5A one.
The FY66 is upgradable
The FY68 /9  the only 2* real upgrades that would be valid  would be .
A)  Replace the Cyclone chip .  or (B)
B)  Fill with cement paint it a cool colour. Makes a great Door stopper .
*optional use as is .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on November 03, 2020, 08:17:06 am
@ battlecoder

This might interest you this link.
Its a comparison of several AWG and the UTG962 & Rigol & Tek etc . Its Long and full.

https://www.element14.com/community/groups/roadtest/blog/2020/05/17/tektronix-afg31052-verification-tests (https://www.element14.com/community/groups/roadtest/blog/2020/05/17/tektronix-afg31052-verification-tests)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: de_light on November 05, 2020, 09:32:43 am
Received a FY6900 today. Opened it up to find a v1.9 board.
They seem to have replaced the Cyclone branding on the FPGA with a "FEELELEC PRO 1941" branding  :wtf:

Edit for a pic

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on November 05, 2020, 11:35:16 am
That Just confirms what I Previously have said . Thanks.
 Total conformation that the Cyclone Chip was a Fake ..
       Maybe Intel pressed charges against them for using there Brand name.  :-DD.

  How well does the Pro 1941 chip work ?
 (typo error correction  1.7.*  The number was blurred ) 
  Sorry No Bad Feeling .
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: de_light on November 05, 2020, 11:43:28 am
That Just confirms what I Previously have said . Thanks.
 Total conformation that the Cyclone Chip was a Fake ..
       Maybe Intel pressed charges against them for using there Brand name.  :-DD.

  How well does the Pro 1941 chip work ?
     BTW Also my Fy68 had also had v1.9v board .
  Sorry No Bad Feeling .

If you tell me an idiot's guide to testing it, I shall do my best! My demands for a function generator aren't strenuous - purely hobbyist usage for repairing radios, driving MOSFETs etc
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: de_light on November 07, 2020, 10:45:12 am
I have tried to capture some images for you. Please bear in mind I am a beginner and rather cack-handedly probed the BNC centre prin output from the FY6900 with a short ground wire/spring touching the outer shell. It is NOT terminated in a 50 ohm resistance (Rigol DS1054Z)

First image is an 11 MHz square wave output, 5VDC p-p. Second is with dots and 1s persistence.

Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on November 07, 2020, 02:10:14 pm
If you use the probe directly it is already matched to the scope 50 \$\Omega\$.
Not Bad I have seen a worse . Your scope bandwidth is 50Mhz unless you have done an upgrade .
11Mhz square is at the upper end of your scope's limitation .
 So you wont see the jitter but just that thicker line .
 Try @ 3Mhz or Less square should be more in the bandwidth and set the probe to X10 .
 But by the width of that rise is properly 4ns +-

Rule of thumb you need a scope at least 5 to 10 time the Bandwidth of the Frequency required to see.
 There are other people on this forum  better at explaining this reason .

 :popcorn:
 enjoy
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: mawyatt on November 07, 2020, 03:01:03 pm
The frequency of a squarewave has nothing to do with the edge rise and fall time, which is essentially independent of the waveform frequency. You need a scope rise time of better than 1/5 the measured rise time according to Tektronix, which using the usual 0.35/BW 1st order model for lower BW scopes would place the required scope BW of greater than  5*(.35/tr), or >175MHz for a 10ns rise time.

https://www.mouser.com/pdfdocs/Tektronix12_things_to_consider1.pdf (https://www.mouser.com/pdfdocs/Tektronix12_things_to_consider1.pdf)

The reason for this 1/5, or 5X better scope rise time mentioned by Tektronix is that the scope and DUT rise time are uncorrelated and thus follow the effective "system" rise time as the usual tr-system = sqrt[(tr-scope)^2 + (tr-DUT)^2], so a 5X better scope tr only causes a 2% measurement error if I did my math correctly.

Anyway, hope this helps.

Best,   
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: de_light on November 07, 2020, 07:08:11 pm
Scope is unlocked to 100MHz and probe set to 10x
Waveform at 3MHz

 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: radiolistener on November 07, 2020, 11:48:30 pm
First image is an 11 MHz square wave output, 5VDC p-p. Second is with dots and 1s persistence.

if someone interested, here is the same 11 MHz 5 Vpp square wave taken from PSG9080 generator through 1 meter RG58 cable.
1) 1 MOhm input mode
2) 50 Ohm input mode
3) fall edge of the first cycle after trigger and rise edge of the second cycle after trigger (delay 70 ns after trigger)
4) rise edge of the second cycle after trigger with max oscilloscope resolution (2 ns/div, delay 70 ns after trigger)

jitter is about 0.6 ns peak-to-peak

I think amplitude error is due to to oscilloscope response flatness, because I tested PSG9080 with logarithmic detector and it's response is pretty flat up to 50 MHz and my multimeter shows pretty precise amplitude at low frequency (at 1-100 kHz).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Labrat101 on November 08, 2020, 09:06:05 am
Hi .   @radiolistener
That's a Nice square wave with a low jitter.  :-+
 The PSG9080 is better built .
 All the FY series suffer from same old problems. 
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: RainerB on November 11, 2020, 08:16:26 am
I'm plaing with fremen67's Bluepill Code V0.82.
An ILI9341 Display and the serial PC connection worked.
The keypad doesn't really worked, not sure if this version support (all) keys.
The PB2 Pin is not available on the Bluepill. Can anybody give me some additional information about the bluepill version?
I send fremen67 a pm a few days ago, but didn't got any feedback yet.

Thanks and regards
Rainer
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: mnementh on November 26, 2020, 03:38:33 pm
Considering that the FY6x00 are all available right now within a few dollars of the UTG 9x2, at around US$100 (the days of the $40 FY6600 are long gone), and only aboot $75 less than the PSG8090 even with "Black Friday" sales, is the PSG8090 now the best bang/buck? 

I like the form factor of the UTG 9x2, as it would fit under my scope with the bail down (pretty sure that's why these were made this way); but it is pretty hard to make even a ballpark evaluation of these 3 families of "Chinesium Cheapies", except that the FY6900 seems to be pretty roundly disliked as a downgrade from previous versions.  :P

One thing that would make my decision easier... can the 9x2 be easily modded with an external +/-15V supply? I mean, without just munging the eff out of the board...?

mnem
 :popcorn:
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: mnementh on December 05, 2020, 04:41:29 pm
Pulled the trigger on a UTG 962 from bang-em-good; was able to burn a few affiliate points and saved a few dollars. Might be here before X-mas; we'll see how it fares then.

mnem
 ;D
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Falk on December 22, 2020, 10:26:38 am
To whom it may concern.

https://www.mikrocontroller.net/articles/FY6900 (https://www.mikrocontroller.net/articles/FY6900)

Sorry, only in german.

Njoy
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: cepsbow on March 31, 2021, 02:54:28 pm
I really appreciate the efforts here guys.  :-+ I got my FY6600 while they were on sale, and have been steadily modding it as I went. Before I went into the FP, wanted to know if there is access to the source for the mcu and whatnot? And can you flash this over the stock micros firmware? For information my FY6600 came with version 3.3 hardware and a FEELELEC PRO FPGA. I need to pour over the ICs and match them up to the models you guys posted. Has anyone heard from fremen lately?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: jdmoranii on August 16, 2022, 08:23:03 pm
Hi, Dave. Sorry to resurface a long-dead thread, but…

I recently discovered that my FY6600 was dead. The -12V DC supply was being loaded down. I connected a (-) dc supply to that rail, limited current to 1A and cranked up the voltage until 750mA flowed. C81 got toasty hot. So I removed it. Searching this thread for “C81” and “C82”, I found your comment that C81/C82 were 100nf. But they look physically too big, the smaller caps in parallel with them are 100nf. So I removed C82 and measured it. It was 10u. I replaced C81 with a 10u.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 02, 2022, 09:46:30 pm
By chance, I just happened to look in on this thread for the first time in several months!

I remember the C82 incident, and have to say that I had no idea what its value was at the time (it blew on 10 Aug 2018, according to my notes!), but 100nF has done the job for the last four years, so it can't be too critical.  Physical size is, of course, no indication of value, and C53, 54, 56 and 57, which are all supposed to be 10uF, are massive in comparison to the original C81 and C82 on my PCB (as per some photos I took when did the 3095 opamps upgrade).  However, looking again at the photos, it would appear that C81 and C82 were actually different beasts (at least in colour and shape - although you couldn't tell that from the frazzled remains of C82 I removed), so my original assumption that they were the same value may have been incorrect - although why the capacitors on the 4558 VCC+ and VCC- should be different, I have no idea.  Thanks for your message, though: if C82 ever blows again I'll consider replacing it with a 10uF (if I can find one with a small enough footprint to fit in its place on the board).

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 03, 2022, 04:57:46 am
 Hi Dave  :)

 If you don't want to clutter your web browser with a tabbed link to a moribund topic thread or have to check your bookmarks' folder every so often just to take look for fresh postings, why not click on the "Notify" button?  :)

==============================================================================================
[EDIT 2022-09-03]

 To add to the above advice, that the key benefit to clicking the "Notify" button is that you can delete the tab any time thereafter and de-clutter the web browser. I usually wait a day or three to see how many times the attached images have been viewed before doing that, even longer if I think I may have more to add. If the viewed count rate drops right off after a week or three and I'm still planning on adding another post, I really aught to add it to my bookmarks folder and close the tab but I'm not that organised so just tend to leave the tab open. ::)
==============================================================================================

 Another trick you can use when trying to resurrect a thread that hasn't seen a new post in several months (or even a year or three!) is to attach an image or three to your post. That way, you can gauge the level of passive interest from the number of views they get even if no one bothers to post a reply.

 Here's an example of the effectiveness of that trick where the latest post had been two and a half years prior to my own contribution. >:D Sadly, no actual replies but the view count against each attached image does at least reveal a level of interest (the initial 4 views in the space of only 5 minutes strongly hinting at the use of the notification button).

https://www.eevblog.com/forum/metrology/i-just-bought-an-efratom-100318/msg4176703/#msg4176703 (https://www.eevblog.com/forum/metrology/i-just-bought-an-efratom-100318/msg4176703/#msg4176703)

 By way of an on topic update, I'm pleased to able to report that my much modded FY6600-60M is still going strong. Indeed, its upgrade replacement, a Siglent SDG2042X (120MHz version ;)), has effectively been relegated to acting as a support plinth for the 6600, mainly it has to be said, for its inability to offer the advertised 1 microHertz tuning resolution 'feature' beyond 100KHz for an insufficiency of digits in the frequency display :o :( >:(

 I've attached an image which I think might be of some interest (after all, this is the latest round in my search for a better frequency reference than the 6600 had originally been cursed with). >:D

 BTW, the gps disciplining wobble accounts for some 6 or 7 ns of the band of persistence recorded in that screen grab. The remaining 29 ns comes from what appears to be a diurnal temperature influence on the ruby's frequency stability (along with a tiny calibration error and a smidgen of ageing drift).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 03, 2022, 03:57:25 pm
Hi John,

Nice to see you're still active!

Thanks for the tips, but, as someone who keeps the most cluttered browser in the universe (three of them, in fact, all multi-windowed and multi-tabbed), I don't intend to spend half of what's left of my life resorting tabs or converting them into bookmarks just to save a few seconds every six months or so :).  Some of them are several years old, but I know where they are and I can easily find them thanks to the ColorfulTabs addon.  A number are linked to topics on here that I've participated in over the years, and I keep them open because it's an amusing diversion to look in occasionally to see how many more times the wheel has been reinvented since I became a lapsed member of the thread.

The FY6600 was a nice project to be involved in, and it eventually evolved to a level of sophistication which more than met my user needs (and many others', it would appear), and your efforts to squeeze even more performance from it have taken it to another level again.  It's amazing what can done with a bit of cheap kit and some ingenuity, isn't it?

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 04, 2022, 01:13:27 am
 Hi Dave,

 I've just edited that post to clarify the benefit of clicking the notify button as per the following.

 To add to the above advice, that the key benefit to clicking the "Notify" button is that you can delete the tab any time thereafter and de-clutter the web browser. I usually wait a day or three to see how many times the attached images have been viewed before doing that, even longer if I think I may have more to add. If the viewed count rate drops right off after a week or three and I'm still planning on adding another post, I really aught to add it to my bookmarks folder and close the tab but I'm not that organised so just tend to leave the tab open. ::)

 As for the venerable FY6600, that proved to be a surprisingly excellent performer once you'd voided its warranty with several relatively trivial modifications to fix its seemingly beancounteritus inspired penny pinching induced shortcomings. Sure, the penny pinching did save a few cents on the dollar in production costs but I think the motivation to even risk such a ludicrously foolish penny pinching strategy was more to do with reducing their costs on handling warranty returns down to a nice fat zero by taunting their target market demographic into turning this Sow's Ear into a silken purse at the expense of a voided warranty.

 I think Feeltech knew their target demographic far better than it knew itself and were maximising the PRC's government subsidies on export shipping costs to make any warranty return attempts a high risk exercise if the AWG had been 'fiddled with' in any way since the return shipping charges would be an upfront cost to the customer, only refunded if Feeltech deemed the warranty hadn't been voided.

 When I'd offered this hypothesis to the group two or three years ago, it was discounted as just another "conspiracy theory" but the fact that their latest 6900 version has an unpopulated fan cooler aperture moulded into its back panel only lends further credence to this hypothesis imho.

 The original motivation for such nonsensical penny pinching may well have been simply that of reducing production costs which, after monitoring this topic thread, would have revealed the warranty voiding efforts of its target demographic soon enough that it seems they'd decided to pretend ignorance of the more egregious defects, electing to apply a cack handed half live mains leakage fix in the 6800 (and the 6900!) models and leave the remaining defects unaddressed to ensure a minimum of valid warranty returns where they would not only have had to deal with the expense of any repair (in reality more likely just take another unit from their stock of spares set aside for such warranty replacements) but also that of the customer's warranty return shipping costs.

 Looking at the way FeelTech have failed to respond to their customers' requests to fix blatant shortcomings, looks very much like a strategy to cut overheads by taking advantage of their customers' propensity to void their warranties (deemed worthless by most anyway) by having a go at fixing the issues for themselves, and thereby reduce the number of warranty returns they would otherwise be obliged to deal with.

 However, despite what I think of the situation, I'd still be inclined to replace the 6600 with a 6900 should it ever develop an irreparable fault. After all, for the money, it still represents an excellent bargain in AWG technology for what most of us would consider "chump change".

 It's certainly cheap enough to risk improving to a higher standard with an OCXO lockable to an external 10MHz reference and an upgrade of the 85 ohm attenuator to a real 50 ohm 20 dB resistor network plus replacing the earthing wire link to the PE pin of the C14 socket with a 4.7K resistor to eliminate random dc offsets and noise coming in from the mains earth wiring and, of course, fitting a fan into the case for a modicum of active cooling.

 Incidentally, the abysmal lack of passive convective cooling airflow proved inspirational in the ventilation arrangements I'd used in my rubidium frequency standard. I needed the cooling fan to be the sole arbiter over the LPRO's base plate temperature so any natural convective flow would have been counterproductive, so it's hats off to FeelTech for a real tour de force lesson on how to achieve virtually zero convective cooling.  >:D  :-DD :-DD
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 05, 2022, 12:21:36 am
Hi John,

I think the warranty thing is a bit of overthinking by you.  Like all Chinese companies at the lower end of the market, warranty doesn't enter their minds: they just know that they can build something for x dollars and sell it for y dollars, and if (y-x)*n sales is enough to set them on the road to riches then they are happy.  No need to follow international safety standards or awkward things like that, and they write the specs themselves and sometimes even manage to meet them: if they don't, so what?  Caveat emptor!  If they've done a bit of research, they'll know that there's absolutely no chance of getting a faulty item returned to them, because sending it back is likely to cost more than the item is worth, and if, by chance, something is sent back, they can just throw it in the skip and say they never received it!  It's all in the Chinese Business Manual.  That's not to say that they all follow the Manual to the letter, because I've dealt with some really good sellers in the past, who went way beyond expectations to provide a good service, but you just have to weigh the chances of buying a pig in a poke before you part with your money, and be prepared to write it off if the item turns out to be porcine.

As for the actual AWG itself, I knew what I was getting after the FY6600 and bought a 6800 because I saw a good deal from some seller, knowing I could easily upgrade it in a couple of hours - although I stopped after the earthing correction and the TCXO change because the newer firmware meant that I didn't see the need to do anything else to it - and even went on to buy a 6900 a couple of years ago just because curiosity got the better of me.  (I'm actually not that keen on the 6900 because the keypad buttons are too firm, and are a definite downgrade from the 6800.)  Having just looked at the 6900 case, I find that I did actually fit the "missing" fan (I can't remember doing it, but I'll have had one or two suitable ones lying around, no doubt), but that's probably all I've done to it, apart from the obligatory earthing fix.

Out of interest, do you actually NEED a rubidium standard, or is that just another obsession?  (Says I, with two Thunderbolts next to the PC keeping my feet warm, four more GPSDOs in various places, and half a dozen home-made 10MHz OCXOs sitting in a box upstairs!)  :)

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 05, 2022, 08:56:32 pm
Hi Dave.

 Very nicely put. :) That's a less contentious version than mine but the conclusions reached are the same. I knew I was buying a "Pig in a poke" (more accurately, a "Sow's Ear") when I bought mine from a UK based Ebay seller as I mentioned in my very first eevblog post way back mid November 2018 to which my first reply had come from your good self!  :)

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1973777/#msg1973777 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1973777/#msg1973777)

 I was interested to note your comments on the 6900's overly stiff buttons. Obviously stiff compared to the 6800 but surely an improvement over those bumps used on the 6600 front panel? These operate actual momentary push switches soldered onto the PCB. Those bumps are the one remaining annoyance only tempered by the fact that it's at least possible to replace any switches that may fail or start behaving erratically.

 Answering your question over my need of a rubidium standard, I have to offer an unqualified yes. I had been tempted to claim you'd answered your own question but although there is an element of want over need, in this case it's a vital tool in assessing other frequency standards (tcxo, ocxo, docxo, gpsdo and so on). In any case, I'll eventually be converting it into a GPSDRO to get rid of its ageing drift.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: DaveR on September 06, 2022, 12:05:05 am
Hi John,

The buttons on the 6900 are truly awful, at least on the model I bought, although they may have been changed again to something more acceptable on the latest 5v incarnations.  The buttons on mine are soft silicone rubber on a very stiff spring or switch; there is no tactile feedback, and it takes a lot of effort to compress the wobbly blobs enough to move the spring and activate the switches underneath - solid plastic buttons would have been far better.  The membrane buttons on the 6600 are a pleasure to use by comparison - at least you can feel the click when the switch operates.  The 6800 buttons are light touch, and feel just right: I couldn't believe how far backwards Feeltech had gone with the 6900, because you need two hands, or have it braced against something immovable, to use it!

Thanks for that link!  It's almost four years ago now, but reading a few pages from the thread brought it all back to me as if it were just last week.  I see I was stalling on the 6800 opamp upgrade even then, and never did carry it out :).

Regards,
Dave
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Johnny B Good on September 06, 2022, 04:41:34 pm
 Hi Dave,

 Thanks for giving me a "heads up" on the overly stiff buttons used by the (hopefully) early versions of the 6900. If they're so stiff as to make those used in the 6600 models a joy to use by comparison, they must be very stiff indeed (BTW "a joy to use" isn't a phrase that immediately springs to mind when using the 6600 buttons).

 If I ever need to replace the 6600 with another cheap AWG capable of 1uHz resolution from DC to 60 or 100MHz and lower sine wave jitter than that of an SDG2000X model, the latest 6900 models look (stiff button issues aside) to be an ideal replacement since most of the hard work, with the exception of replacing the resistors in the 85 ohm 20 dB attenuator, has already been done.

 They carried on using those cheap dual opamps but doubled them up to reduce sine wave distortion at the 20v pk-pk and 20MHz limits when driving 50 ohm loads. The improvement falls a little short of the opamp upgrade in the 6600 and 6800 models but still sufficient to make the expense of a pair of THS3091s or whatever, questionable so I'd be inclined not to bother.

 The current models using a single rail smpsu board makes for a simpler upgrade to a quieter 5v psu (it also simplifies the battery powered test setup somewhat to check whether such an upgrade is even worth the trouble of purchasing or making up a replacement psu).

 The change from a 50MHz XO to a 10MHz XO eliminates any need to add a 3N502 clock multiplier chip onto the OCXO upgrade's BOM list, saving both time and costs all of which make for a relatively easier DIY upgrade path. What's not to like (stiff buttons aside)? ;D

 With regard to unused component purchases (that still to be done opamp upgrade you mentioned), that's not so unusual with DIY projects. The simplified battery power test I mentioned was prompted by the fact that the two 6v lantern batteries I'd purchased almost three years ago now, are still gathering dust on a shelf. I never did get around to testing whether a psu upgrade would be worth the effort. :palm:  :)

 I think the reason for putting this "battery test" exercise off indefinitely was due to having an epiphany involving the use of an HF transceiver with a short wire aerial to monitor the quality of the AWG's output into a metre or so of wire plugged into its BNC socket and being left a little bit bemused by the apparent high levels of mains frequency sideband noise which would vary in strength depending on how I laid out the AWG's transmitting antenna.

 Suspecting that the mains wiring was re-radiating the 10MHz test signal and mains current was modulating this re-radiated signal via some non-linearity mechanism (the "rusty bolt" effect), I connected the transceiver directly to the AWG through a 2 metre BNC patch lead and an SO239(?) adaptor, having already enabled its built in 20dB front end attenuator (no pre-amp required for the HF bands - just a bandpass filter feeding the 1st mixer directly). Lo and behold! A nice clean carrier sans the mains frequency harmonics. It turns out that relying on an "over - the - air" link path with an HF receiver to monitor the signal quality is not really a good idea (it's a quick and (very) dirty test with the "quick" of that description being its only redeeming quality).

 After belatedly running a proper test, I realised that what I'd initially concluded to be a psu noise issue was in fact just the result of a badly organised test that had allowed a polluted version of the test signal to be re-radiated from the mains wiring. :palm: The "psu noise issue" had proved to be nowhere near as bad as I'd assumed and quite possibly not even an issue at all so my planned battery test lost all sense of urgency and was literally left to gather dust.

 I might eventually get round to running this battery test, most likely when I get round to adding more padding to the trimpot on the OCXO board to make it less 'touchy' to adjust. The main impediment to running the battery test had been the lack of a suitable 6 pin connector to plug into the main board power socket. However, since I'd now like to be able to switch between battery and mains power at the flick of a switch to run the comparison as a "Blink Test", I'll probably just (temporarily) solder the wires straight onto the cct board (psu or main). One additional 'complication' in my case being the need to include the OCXO's 12v rail in this scheme since it's powered independently from its own smpsu (another possible noise source) regardless of the rear panel on/off switch state.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: tzok on September 08, 2022, 08:29:10 pm
Any chance that the Front Panel firmware will be finished, or at least it will reach full functionality, like ability to turn the device off ;)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: adeuring on September 16, 2022, 01:33:46 am
Got recently a second hand FY6800. One channel worked fine, the other had a terrible positive offset that made is practically unusable. (Forgot unfortunately to make a DSO screenshot before repairing the thingy...)

I suspected that the opamp driven by the DAC, an AD8009, (IC1 in DerKammi's excellent schematics, https://github.com/DerKammi/FY6600-15-30-50-60M/blob/master/Hardware/FY6600_Main_A0.pdf ) was broken and replaced it; now both channels work fine. Attached is photo of the old AD8009 (left) and the replacement (right). Note that the removed chip does not have the Analog Devices logo...

[attachimg=1]

But before anybody concludes that Feeltech uses fake chips: (1) The device has an unknown history – I do not know who soldered the left opamp in the photo onto the board; (2) I am not familiar with the "pattern" used by Analog devices to label their chips – perhaps the left chip is genuine; (3) clones do not have to be worse the original…

Another oddity: The counterpart of the chip I replaced for the other channel (U10 in DerKammi's schematics) is an LMH6702MA, not another AD8009… But again: I do not know if the previous owner(s) of the device or Feeltech soldered this chip.

Thanks to DerKammi and everybody else who contributed to the schematic. Having it available made the repair really simple.

PS: I suspect that this thread and DerKammi's Github repo for the FY6600 can lead to a sort of addiction to the FX66xx. I bought it mainly for some audio measurements but after reading this thread I'm wondering if I shouldn't start too to tinker with this "sow's ear" ;).
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: rhb on September 16, 2022, 12:57:55 pm
Hi,guys.  I finally wandered back for a visit after a long hiatus and am happy to see my favorite energizer bunny, the F***tech thread is going strong :-)

Naturally, I had to get an eBay update on FY6900.  One seller in the US is offering a 2 year warranty and “100% satisfaction”.

Naturally, rather suspect.

Is there any hope yet of replacement FW to fix my twice self-borked 6600?

HaveFun!
Reg
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: kaldach79 on November 06, 2022, 07:42:17 pm
Hi,
Do you know what driver is used in the generator display?
My LCD is damaged - grey backround, or only backlight. After freeze works fine by short time.
The original display has an 18 pin, but i have problem identifying the driver ILI9341 or ST7789.
Thanks for the help! :)
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: kaldach79 on November 26, 2022, 02:28:30 pm
Am updating my post. Display containing ST7789 driver chip, not working properly.The image is inverted, and the blue and red color are reversed.
I will try display with driver ILI9341.
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: hlj.pycad on March 20, 2024, 02:07:47 pm
when I try to turn on the FY-6600 , it will show the brand icon "FeelTech" for a brief moment,  then the screen turn white. The keys seem still fuction. Any clue where I should look into?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: hlj.pycad on March 29, 2024, 01:39:44 pm
I fixed the last problem. It's PSU output caps' problem.

But some how my "sinewave" became 3/4 sine+1/4square.... it's there a fix for this?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: Atlan on March 29, 2024, 01:51:19 pm
Repair sine with program?
Title: Re: FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator
Post by: hlj.pycad on March 29, 2024, 02:07:17 pm
Yes. I just found that. Thank you.