EEVblog Electronics Community Forum

Products => Test Equipment => Topic started by: feeltech on July 23, 2019, 06:39:42 am

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 23, 2019, 06:39:42 am
Dear Customers,
Thank you very much for your support for FeelElec Products.
Our company has launched a new signal generator FY6900 in 2019.

The following is a detailed introduction of the new product.



Product Description:
    FY6900 series dual-channel function/arbitrary waveform generator is a high-performance, cost-effective and multi-functional signal generator which integrates functions of function signal generator, arbitrary waveform generator, pulse signal generator, noise generator, VCO, counter and frequency meter. The instrument uses large-scale FPGA integrated circuit and high-speed MCU microprocessor. The internal circuit uses high-precision active crystal oscillator as the reference, and the signal stability is high. Surface mounting technology greatly improves the anti-interference and service life of the instrument. The instrument has completely independent dual DDS signal and four TTL level output. It can generate 36 preset waveform signals such as sine wave, square wave, rectangular wave, triangular wave, sawtooth wave, pulse wave, white noise and 64 user-defined waveforms. This instrument achieves the perfect combination of easy-to-use, excellent technical indicators and many functional characteristics in signal generation, waveform scanning, parameter measurement and use. It can help users accomplish their tasks faster. It is an ideal test and measurement equipment for electronic engineers, electronic laboratories, production lines, teaching and scientific research.

    FY6900 series dual-channel function/arbitrary waveform generator has humanized keyboard layout and instructions, providing users with an intuitive operation interface. The display interface uses a 2.4 inch TFT color LCD screen with 320*240 high resolution. It can display all the parameters of the two channels at the same time and prompt the current button function. The shortcut key greatly simplifies the complex operation process and greatly enhances the operability of the instrument. Users can use the instrument skillfully without spending a lot of time to learn and familiarize themselves with the operation of the instrument.

Appearance:
(https://www.eevblog.com/forum/contests/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=792333;image)
(https://www.eevblog.com/forum/contests/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=792339;image)
(https://www.eevblog.com/forum/contests/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=792345;image)
(https://www.eevblog.com/forum/contests/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=792351;image)
(https://www.eevblog.com/forum/contests/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=792357;image)

Technical Parameter:
(https://www.eevblog.com/forum/buysellwanted/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=794970;image)


Purchase Link: https://www.aliexpress.com/store/group/FY6900-Series/5040093_516012542.html?spm=2114.12010615.pcShopHead_85220635.1_3 (https://www.aliexpress.com/store/group/FY6900-Series/5040093_516012542.html?spm=2114.12010615.pcShopHead_85220635.1_3)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BravoV on July 23, 2019, 06:47:51 am
What ? No contest for free AWG ? Especially for the new released ones ?  C'mon ... :-//

Considering this forum alone has contributed alot to your business, imo.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: beanflying on July 23, 2019, 08:17:22 am
I wasn't going to but take this as critique on your on going poor behaviour to your current user base!

Your complete lack of support for the 6600 for those with failed units due to no fault of their own is PATHETIC!

Your abandonment of the 6800 after only months since release and likely non support going forward is Questionable at best!

Your renaming from company A to B is pointless as the shit from the already mentioned models has never been explained of supported by YOU and YOUR Company in any satisfactory manner.

LET THE POTENTIAL BUYERS BEWARE This company SUX until proven otherwise over time moving forward! :rant:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: beanflying on July 23, 2019, 09:34:41 am
It is not ME you owe a PM to it is the others long ignored by your company. Unlike some mine has worked well for the price paid and I have no real complaints about my 6600 apart from the much talked about terrible power supply and other niggles.

What I do have a major problem with is the complete lack of morals you show asking the members of this forum to support you when you have not supported those who asked and were not!

[attachimg=1]
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 23, 2019, 10:25:45 am
I wasn't going to but take this as critique on your on going poor behaviour to your current user base!

Your complete lack of support for the 6600 for those with failed units due to no fault of their own is PATHETIC!

Your abandonment of the 6800 after only months since release and likely non support going forward is Questionable at best!

Your renaming from company A to B is pointless as the shit from the already mentioned models has never been explained of supported by YOU and YOUR Company in any satisfactory manner.

LET THE POTENTIAL BUYERS BEWARE This company SUX until proven otherwise over time moving forward! :rant:


Thank you for your support and attention to our products! Our replies and commitments to your questions are as follows:

1. The company's previous sales and after-sales are the responsibility of the agents, which causes some customers' problems not to be feedback to us and thus not solved in time. As a manufacturer, we first apologize to you, so this situation will not exist after we open the official store of Aliexpress and eevblog account. Customer products can be directly fed back to us whenever they are purchased from any channel. Our company will actively solve the problem.
2. FY6900 is a new series of products, and its performance index is better than FY6800. FY6800 and FY6600 have no shutdown plans. We will continue to provide technical support and after-sales service to our customers.
3. About brand, FeelTech and FeelElec belong to our company, which can be reflected in the product boot screen.

If customers have Questions or suggestions about the product can be feedback to us, I believe that through our communication, we can make products and services better! Thank you again for your support for our products!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: beanflying on July 23, 2019, 10:52:43 am
Your first attempt at interacting with this Forum is this Thread started by a mystery Member spruiking for you! You didn't even have the decency to start your own thread.

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/)

Start at the beginning and read the content and try and repair why we should think kindly of you and not think you are PATHETIC in your companies behaviour!

You are the MANUFACTURER of the product and the failures start and end with you with your reseller being in the middle with generally zero technical skills or knowledge. Then to blame them for your poor product is worse than pathetic! Using them as sacrificial pawns is beyond pathetic.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 24, 2019, 01:39:29 am
Your first attempt at interacting with this Forum is this Thread started by a mystery Member spruiking for you! You didn't even have the decency to start your own thread.

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/)

Start at the beginning and read the content and try and repair why we should think kindly of you and not think you are PATHETIC in your companies behaviour!

You are the MANUFACTURER of the product and the failures start and end with you with your reseller being in the middle with generally zero technical skills or knowledge. Then to blame them for your poor product is worse than pathetic! Using them as sacrificial pawns is beyond pathetic.


1. We hope you can give us detailed questions about the inferior quality of the products, and we can help you solve them. We would like to thank you very much for your suggestion. FeelElec wants to bring customers a better product experience.
2. FeelElec have never attributed the responsibility to the agent, the agent feedback to our company's problems, we will respond within 24 hours, and actively assist the agent to help customers solve problems.
3. From now on, there will be someone in charge of the forum account. We are willing to receive more feedback from customers and suggestions. We also have the ability to solve any problems in our products, provide better services for users, and develop more products that users like. Better help distributors sell our products!
4. Any questions about product quality or special functional requirements you may encounter before or after can contact us directly in eevblog.

After-Sale Email Address: service@feelelec.com

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Electro Fan on July 24, 2019, 02:19:51 am
Hello feeltech,

You will likely get a lot of questions and suggestions here.  The feedback from EEVblog forum members might seem challenging but if you can respond well it will help you sell more of your products and also develop new features, functions, and improved performance.

Your 6900 model looks promising but many of your best customers and best advocates and friends could be your 6600 and 6800 customers.  Your 6600 and 6800 customers took the risk to try your products and how you support them will influence the thinking of potential new customers.  This might be the most important thing.

Having said the above, I have two suggestions for you.

1. You should consider selling your products directly from you (and/or your distributors) with feeltech factory support on eBay for customers who prefer to buy on eBay.

2. You should consider adding a 10 MHz reference input to your products so that customers can improve clock performance with external GPSDOs.

Good luck.

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: bdunham7 on July 24, 2019, 02:59:10 am


1. We hope you can give us detailed questions about the inferior quality of the products, and we can help you solve them. We would like to thank you very much for your suggestion. FeelElec wants to bring customers a better product experience.
2. FeelElec have never attributed the responsibility to the agent, the agent feedback to our company's problems, we will respond within 24 hours, and actively assist the agent to help customers solve problems.
3. From now on, there will be someone in charge of the forum account. We are willing to receive more feedback from customers and suggestions. We also have the ability to solve any problems in our products, provide better services for users, and develop more products that users like. Better help distributors sell our products!
4. Any questions about product quality or special functional requirements you may encounter before or after can contact us directly in eevblog.

After-Sale Email Address: service@feelelec.com


So I have a few questions and ideas for you:

1.  Can you provide a reliable, navigable, usable english-language (and perhaps others since these are sold globally) web site that has downloads for the PC software that is included on the CD that comes with the unit?  A significant number of these CDs have been reported unreadable or even missing entirely.  If this already exists and I missed it, thanks and I apologize in advance.  If the software is different for the FY6600, FY6800 and FY6900, they each should have their own page.  And improving the software would be welcome too.

2.  Can you tell us what changes have been made in the FY6900 other than the case?  Specifically, some resellers are advertising a feature called "Magic Pulse", which supposedly eliminates jitter in certain square waves.  Is this a real thing?

3.  Are these things actually manufactured, boxed and shipping yet?

4.  Choose your resellers more carefully if they aren't representing you well.  Selling and supporting them yourself on Aliexpress, eBay and perhaps Amazon would be a good thing.   
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 24, 2019, 05:53:15 am
Hello feeltech,

You will likely get a lot of questions and suggestions here.  The feedback from EEVblog forum members might seem challenging but if you can respond well it will help you sell more of your products and also develop new features, functions, and improved performance.

Your 6900 model looks promising but many of your best customers and best advocates and friends could be your 6600 and 6800 customers.  Your 6600 and 6800 customers took the risk to try your products and how you support them will influence the thinking of potential new customers.  This might be the most important thing.

Having said the above, I have two suggestions for you.

1. You should consider selling your products directly from you (and/or your distributors) with feeltech factory support on eBay for customers who prefer to buy on eBay.

2. You should consider adding a 10 MHz reference input to your products so that customers can improve clock performance with external GPSDOs.

Good luck.


FY6900 is an upgraded product of FY6600 and FY6800. Customers can enjoy the technical support and after-sales service provided by our company at any time.

Thank you very much for your suggestion. The reply is as follows:
1. There are distributors selling our products on Ebay, and customers can buy them on Ebay. After-sales problems can be directly contacted with us, or feedback to us through distributors, we will solve after-sales problems for you.
2. FeelElec technicians will accept your suggestion and upgrade the product according to your suggestion.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 24, 2019, 08:18:00 am



So I have a few questions and ideas for you:

1.  Can you provide a reliable, navigable, usable english-language (and perhaps others since these are sold globally) web site that has downloads for the PC software that is included on the CD that comes with the unit?  A significant number of these CDs have been reported unreadable or even missing entirely.  If this already exists and I missed it, thanks and I apologize in advance.  If the software is different for the FY6600, FY6800 and FY6900, they each should have their own page.  And improving the software would be welcome too.

2.  Can you tell us what changes have been made in the FY6900 other than the case?  Specifically, some resellers are advertising a feature called "Magic Pulse", which supposedly eliminates jitter in certain square waves.  Is this a real thing?

3.  Are these things actually manufactured, boxed and shipping yet?

4.  Choose your resellers more carefully if they aren't representing you well.  Selling and supporting them yourself on Aliexpress, eBay and perhaps Amazon would be a good thing.   


Thank you very much for your feedback and suggestions. The replies are as follows:

1. This is our PC software download link: http://en.feeltech.net/index.php?case=archive&act=list&catid=6&page=1 (http://en.feeltech.net/index.php?case=archive&act=list&catid=6&page=1)   

2. The functional performance upgrade that distributors publicize really exists. Following are details of FY6900 upgrade:
- MagicPulse Technology,Low Jitter(RMS)<200ps
- More Than 100 Waveforms: 8192 points * 14bits
- 0~24Vpp Amplitude Range,Min Resolution 1mV
We will record and upload relevant test videos as soon as possible.

3. Perhaps we can’t understand the third article clearly. Would it be convenient for you to describe it in more detail?

4. Thank you for your suggestion. We will carefully screen distributors in the future.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: beanflying on July 24, 2019, 09:22:09 am
Your first attempt at interacting with this Forum is this Thread started by a mystery Member spruiking for you! You didn't even have the decency to start your own thread.

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/)

Start at the beginning and read the content and try and repair why we should think kindly of you and not think you are PATHETIC in your companies behaviour!

You are the MANUFACTURER of the product and the failures start and end with you with your reseller being in the middle with generally zero technical skills or knowledge. Then to blame them for your poor product is worse than pathetic! Using them as sacrificial pawns is beyond pathetic.


1. We hope you can give us detailed questions about the inferior quality of the products, and we can help you solve them. We would like to thank you very much for your suggestion. FeelElec wants to bring customers a better product experience.
2. FeelElec have never attributed the responsibility to the agent, the agent feedback to our company's problems, we will respond within 24 hours, and actively assist the agent to help customers solve problems.
3. From now on, there will be someone in charge of the forum account. We are willing to receive more feedback from customers and suggestions. We also have the ability to solve any problems in our products, provide better services for users, and develop more products that users like. Better help distributors sell our products!
4. Any questions about product quality or special functional requirements you may encounter before or after can contact us directly in eevblog.

After-Sale Email Address: service@feelelec.com



Save your platitudes for someone gullible enough to believe them  :palm:

After 4+ YEARS YOU were still producing units with sub par power supplies and were no doubt very aware of that fact! 90V of floating supply is  :bullshit: So many other threads but I won't bother adding them all here.
https://www.eevblog.com/forum/testgear/feeltech-fy3200-psu-upgrade/msg965575/#msg965575 (https://www.eevblog.com/forum/testgear/feeltech-fy3200-psu-upgrade/msg965575/#msg965575)

Completely inadequate and PATHETIC response to some of YOUR CUSTOMERS directly and or via resellers not being able to come together to resolve major failures of FY6600 units. 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/) In a similar manner I won't bother to list all examples but trust me they are MANY! Members of this Forum were left with non functioning  units. True some were resolved but most went unsolved!

And in the main FY6600 thread so many partial failures of displays or certain waveforms and yet no upgrade or remedy path to repair them!

Clearly you only want to waffle platitudes and Feelgood  :bullshit: about moving forward and have us whitewash you very grey past.

Until you face up to your past you don't deserve a free pass to your future.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 24, 2019, 11:07:22 am
Your first attempt at interacting with this Forum is this Thread started by a mystery Member spruiking for you! You didn't even have the decency to start your own thread.

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/ (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/)

Start at the beginning and read the content and try and repair why we should think kindly of you and not think you are PATHETIC in your companies behaviour!

You are the MANUFACTURER of the product and the failures start and end with you with your reseller being in the middle with generally zero technical skills or knowledge. Then to blame them for your poor product is worse than pathetic! Using them as sacrificial pawns is beyond pathetic.


1. We hope you can give us detailed questions about the inferior quality of the products, and we can help you solve them. We would like to thank you very much for your suggestion. FeelElec wants to bring customers a better product experience.
2. FeelElec have never attributed the responsibility to the agent, the agent feedback to our company's problems, we will respond within 24 hours, and actively assist the agent to help customers solve problems.
3. From now on, there will be someone in charge of the forum account. We are willing to receive more feedback from customers and suggestions. We also have the ability to solve any problems in our products, provide better services for users, and develop more products that users like. Better help distributors sell our products!
4. Any questions about product quality or special functional requirements you may encounter before or after can contact us directly in eevblog.

After-Sale Email Address: service@feelelec.com



Save your platitudes for someone gullible enough to believe them  :palm:

After 4+ YEARS YOU were still producing units with sub par power supplies and were no doubt very aware of that fact! 90V of floating supply is  :bullshit: So many other threads but I won't bother adding them all here.
https://www.eevblog.com/forum/testgear/feeltech-fy3200-psu-upgrade/msg965575/#msg965575 (https://www.eevblog.com/forum/testgear/feeltech-fy3200-psu-upgrade/msg965575/#msg965575)

Completely inadequate and PATHETIC response to some of YOUR CUSTOMERS directly and or via resellers not being able to come together to resolve major failures of FY6600 units. 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/) In a similar manner I won't bother to list all examples but trust me they are MANY! Members of this Forum were left with non functioning  units. True some were resolved but most went unsolved!

And in the main FY6600 thread so many partial failures of displays or certain waveforms and yet no upgrade or remedy path to repair them!

Clearly you only want to waffle platitudes and Feelgood  :bullshit: about moving forward and have us whitewash you very grey past.

Until you face up to your past you don't deserve a free pass to your future.


We dono’t want to cover up the problems existing in the previous products, just want to be able to better serve customers and solve customers'problems.
As for the FY6600 malfunction encountered by our customers, now contact us, we will still actively solve the problem for our customers.
service@feelelec.com
Regarding the power supply, the answers are as follows:
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 ceramic Cap" will be between the "LG / NG" (Safety Ceramic Cap 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
And we responded in 2017 as well,
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1297231/#msg1297231 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1297231/#msg1297231)

The following figure is the official shooting of Apple Power Supply. You can see that the suspension voltage is 55V, which does not mean that the quality is problematic.
[attach=1]
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: bdunham7 on July 24, 2019, 05:13:18 pm


3. Perhaps we can’t understand the third article clearly. Would it be convenient for you to describe it in more detail?


Thank you for the link to the software.  Unfortunately, the link didn't work when I tried it just now.  Could you check on this?

As for question #3, I'm asking if the FY6900 has actually been delivered to your distributors yet.  Nobody seems to actually have any, although a lot of them claim to.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: chickenHeadKnob on July 24, 2019, 11:00:26 pm

As for question #3, I'm asking if the FY6900 has actually been delivered to your distributors yet.  Nobody seems to actually have any, although a lot of them claim to.

Yes they have been shipping, I got  mine from Banggood --> Kanadia about 10 day's ago. I verified it makes sine waves! and other stuff. I am so backed up with other problems right now I diddn't want to announce this as I know you guys are so hot and horny for inside pics and tests.
I was hoping someone else would take that burden. (embarrass icon here)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 25, 2019, 12:57:56 am
Thank you for the link to the software.  Unfortunately, the link didn't work when I tried it just now.  Could you check on this?

As for question #3, I'm asking if the FY6900 has actually been delivered to your distributors yet.  Nobody seems to actually have any, although a lot of them claim to.

1. We are very apologized to our website may have some problems. You can download files from Google Drive first. This is download link: https://drive.google.com/open?id=0B3N_NW8vylrmWU93b0EwRjhrQlE (https://drive.google.com/open?id=0B3N_NW8vylrmWU93b0EwRjhrQlE) . We will update the website later and send you a link.
2. FY6900 has already started to sell. You can buy it from an agent or our Aliexpress store.

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: beanflying on July 25, 2019, 01:33:55 am

We dono’t want to cover up the problems existing in the previous products, just want to be able to better serve customers and solve customers'problems.
As for the FY6600 malfunction encountered by our customers, now contact us, we will still actively solve the problem for our customers.
service@feelelec.com
MAJOR BS
Regarding the power supply, the answers are as follows:
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 ceramic Cap" will be between the "LG / NG" (Safety Ceramic Cap 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
And we responded in 2017 as well,
https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1297231/#msg1297231 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1297231/#msg1297231)

The following figure is the official shooting of Apple Power Supply. You can see that the suspension voltage is 55V, which does not mean that the quality is problematic.
[attach=1]

Compared with users like fremen67 that definitely deserves a free unit, not to mention many others, I did almost nothing except starting the the avalanche a bit.
I still think I deserve my 3.1 firmware unit replaced, along with all the other 3.0/3.1 firmware units.
You have only one threat practically to look into it, but  I have a feeling that will be probably the only Feeltech post, or one of the very few, same like this "Amy" person that started the other thread.
And yes, would have been nice to actually answer my emails, sent long ago.

 Good luck to the winners, personally I will not give my private information for 100EUR, but some others maybe will do it.

 DC1MC

FeelTech, here's a link to fremen67 (https://www.eevblog.com/forum/profile/?u=94067)'s profile, for convenience. You can PM him (https://www.eevblog.com/forum/pm/?sa=send;u=94067) a message. ;)

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/)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 25, 2019, 03:57:00 am
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: FeelElec New Arrival FY-6900 Signal Generator
Post by: wasyoungonce on July 25, 2019, 06:18:32 am
Given all this ( yes I read the whole fy6600 thread) guess I’ll keep saving for something that has product support.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 25, 2019, 06:27:14 am
Given all this ( yes I read the whole fy6600 thread) guess I’ll keep saving for something that has product support.

Thanks for your reply and hope you can still support our product. And if you have any suggestions or questions, please contact us any time. ;)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 26, 2019, 01:11:05 am
Thank you for the link to the software.  Unfortunately, the link didn't work when I tried it just now.  Could you check on this?

Have a nice day, our website have already to works well. This is the link http://en.feelelec.com/index.php?case=archive&act=list&catid=6. (http://en.feelelec.com/index.php?case=archive&act=list&catid=6.)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Jacon on July 26, 2019, 06:15:30 am
Thank you for the link to the software.  Unfortunately, the link didn't work when I tried it just now.  Could you check on this?
Have a nice day, our website have already to works well. This is the link http://en.feelelec.com/index.php?case=archive&act=list&catid=6. (http://en.feelelec.com/index.php?case=archive&act=list&catid=6.)
Really ?!?
This is all what I get there:
模板不存在:/www/wwwroot/en.feeltech.net/template/default_html5/message/error.html  :palm:

My advice:  Flowing us with streams of words is counterproductive, believe me.
So, less writing, more reading, thinking. & checking...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 26, 2019, 06:54:31 am
Really ?!?
This is all what I get there:
模板不存在:/www/wwwroot/en.feeltech.net/template/default_html5/message/error.html  :palm:

My advice:  Flowing us with streams of words is counterproductive, believe me.
So, less writing, more reading, thinking. & checking...

We are very sorry about it. It's amazing that we can open the link.
Can you help us one thing? Please check the http://en.feelelec.com/ (http://en.feelelec.com/) or search en.feelelec.com can be opened?

Thanks for your suggestion.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: PA0PBZ on July 26, 2019, 07:00:38 am
Remove the dot (.) after the 6 and it works: http://en.feelelec.com/index.php?case=archive&act=list&catid=6 (http://en.feelelec.com/index.php?case=archive&act=list&catid=6)
However, I do not see software.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 26, 2019, 07:04:33 am
Really ?!?
This is all what I get there:
模板不存在:/www/wwwroot/en.feeltech.net/template/default_html5/message/error.html  :palm:

My advice:  Flowing us with streams of words is counterproductive, believe me.
So, less writing, more reading, thinking. & checking...

Dear Customers,
I'm very apologized to I added an extra point after the link. 
This is my fault, sorry again.

From a mistaken employee。 |O
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: coromonadalix on July 26, 2019, 07:10:09 am
http://en.feelelec.com/ (http://en.feelelec.com/)    tons of chineeses  images links


This following description needs to be reworked, its incomplete and not professional at all

"FEELTECH is a professional industrial grade color LCD module and signal generator industrial product development, production, sales and technical services in one high-tech enterprises.Since its incept… "

incept  what ??

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

"14bitx8192"  ??           "High cost"  tag image  ??   

Seriously    do a proper job in your adds, you dont understand the meaning of your writings  ....  your generators are not industrial grade at all.   They are hobbyist grade.  If they were, the schematics would at least be available under an non disclosure agreement, and parts should be orderable.


I see things like this ......       i'll never buy from you ???


The "see more" links  doesnt work

http://en.feeltech.net/html/Signal%20generator/show_16.html (http://en.feeltech.net/html/Signal%20generator/show_16.html)              404 error
http://en.feeltech.net/html/Signal%20generator/show_17.html (http://en.feeltech.net/html/Signal%20generator/show_17.html)              404 error


Dont want to be rude,  take your web site offline an redo your work, you're trying to be correct and your doing more harm to your "image (company name)"
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: PA0PBZ on July 26, 2019, 07:16:10 am
I'm very apologized to I added an extra point after the link. 

ALWAYS click the preview button and check if you post a link!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 26, 2019, 07:20:45 am
Remove the dot (.) after the 6 and it works: http://en.feelelec.com/index.php?case=archive&act=list&catid=6 (http://en.feelelec.com/index.php?case=archive&act=list&catid=6)
However, I do not see software.

Thank you, dear customers.
When you open the link, such as the 6800, you need to click the download the FY6800 User Guide. This user guide include the PC software.

If you also can't seen it, please feel free to contact us.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 26, 2019, 07:40:21 am
ALWAYS click the preview button and check if you post a link!

Ok, I will always click the preview button and check it after I reply customers.
Thank you very much.

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 26, 2019, 07:56:00 am
http://en.feelelec.com/ (http://en.feelelec.com/)    tons of chineeses  images links


This following description needs to be reworked, its incomplete and not professional at all

"FEELTECH is a professional industrial grade color LCD module and signal generator industrial product development, production, sales and technical services in one high-tech enterprises.Since its incept… "

incept  what ??

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

"14bitx8192"  ??           "High cost"  tag image  ??   

Seriously    do a proper job in your adds, you dont understand the meaning of your writings  ....  your generators are not industrial grade at all.   They are hobbyist grade.  If they were, the schematics would at least be available under an non disclosure agreement, and parts should be orderable.


I see things like this ......       i'll never buy from you ???


The "see more" links  doesnt work

http://en.feeltech.net/html/Signal%20generator/show_16.html (http://en.feeltech.net/html/Signal%20generator/show_16.html)              404 error
http://en.feeltech.net/html/Signal%20generator/show_17.html (http://en.feeltech.net/html/Signal%20generator/show_17.html)              404 error


Dont want to be rude,  take your web site offline an redo your work, you're trying to be correct and your doing more harm to your "image (company name)"

Thanks for your suggestion, we will redo our English website.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: coromonadalix on July 26, 2019, 08:41:28 am
I'm native French  i could help with translation ??

When i go on Aliexpress, Bangood and others, i see tons of badly translated English or pseudo French descriptions, very annoying,   horribly used technical terms ...

I'm not perfect myself  loll  since i dont always catch English terms lol.


Like your description, it need a little re-doing

You see the "enter" tags after the texts ...  you need an good looking descrition sheet,  looks are important, we rely a lot on theses specs ...

keep the models infos/models width the same among all models ...

The display size  2.42.4   is wrong, i think you meant 2,4  inch  wide ??

Interface is not 115200, its serial, usb, lan (network), gpib, wi-fi, bluetooth  ...

Baud rate in serial port is : 115200   thats an huge difference

We have to decode what you mean ... with all the errors in the description


All small details are important, it define  how much you want to show your product, and describe it correctly,

Future buyers want to know or have the user manuals properly translated, software if any included or a link to download it ... acessories if any included ...  if you use some serial (scpi) protocols, have them properly defined and show examples how to do it .....  firmwares updates  if any and how to do it  ....
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 26, 2019, 10:34:21 am
I'm native French  i could help with translation ??

When i go on Aliexpress, Bangood and others, i see tons of badly translated English or pseudo French descriptions, very annoying,   horribly used technical terms ...

I'm not perfect myself  loll  since i dont always catch English terms lol.


Like your description, it need a little re-doing

You see the "enter" tags after the texts ...  you need an good looking descrition sheet,  looks are important, we rely a lot on theses specs ...

keep the models infos/models width the same among all models ...

The display size  2.42.4   is wrong, i think you meant 2,4  inch  wide ??

Interface is not 115200, its serial, usb, lan (network), gpib, wi-fi, bluetooth  ...

Baud rate in serial port is : 115200   thats an huge difference

We have to decode what you mean ... with all the errors in the description


All small details are important, it define  how much you want to show your product, and describe it correctly,

Future buyers want to know or have the user manuals properly translated, software if any included or a link to download it ... acessories if any included ...  if you use some serial (scpi) protocols, have them properly defined and show examples how to do it .....  firmwares updates  if any and how to do it  ....

Thanks for your suggestion, we have already post the new specification chart according to your request.We could provide more accurate descriptions in English in the future.
Hope you can still give us suggestions about the chart or another aspect.
We will record the operation video so that customers can see how the product works more intuitively. Then we plan build an independent English website to better serve global customers.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Brumby on July 26, 2019, 01:59:52 pm
Feeltech - it seems you are genuinely trying to address a number of issues.  This is a good thing.

The road ahead will be difficult.  I wish you well.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 26, 2019, 07:48:17 pm

As for question #3, I'm asking if the FY6900 has actually been delivered to your distributors yet.  Nobody seems to actually have any, although a lot of them claim to.

Yes they have been shipping, I got  mine from Banggood --> Kanadia about 10 day's ago. I verified it makes sine waves! and other stuff. I am so backed up with other problems right now I diddn't want to announce this as I know you guys are so hot and horny for inside pics and tests.
I was hoping someone else would take that burden. (embarrass icon here)

 Hi, chickenHeadKnob

 If you can find a few minutes of spare time, you might want to run the simple tests I described here:-

https://www.eevblog.com/forum/testgear/fy6800-vs-fy6900/msg2556021/#msg2556021 (https://www.eevblog.com/forum/testgear/fy6800-vs-fy6900/msg2556021/#msg2556021)

 Basically, it's a matter of choosing a "Golden Frequency" as far as producing a (4ns DAC clock period) jitter free square wave output is concerned (5MHz will do nicely - no need to use the frequencies I dialled in to demonstrate the limitations of the "Sync" function on frequency resolution >:D ).

 I attached two low res movie files (320x240) to show my results. Don't bother downloading them; I posted higher res versions (640x480) a few posts further on if you want to compare results. This should confirm whether  the "MagicPulse Technology,Low Jitter(RMS)<200ps" feature to reduce or eliminate the 4ns DAC clock period jitter on square waves, listed for the FY6900 by FeelElec, is a real or imagined one.

 The point being that the FY6900's manual makes no mention of it in the features list, nor in the specifications list as far as I was able to discern. It's only in the sellers' web sites sales blurb pages that this feature gets any mention.

 Since this is such a radical improvement over the preceding models, it seems a very strange omission from the user guide/manual. Mind you, these manuals for the preceding models have said more than they should in claiming a non-existent 10Vpp limitation for sine and square waves in the 10 to 20MHz region so anything is possible, including this error being repeated in the FY6900 manual.

 There is no 10Vpp limit for sine and square waves in the previous two models, only a 20Vpp limit from 1 microHertz to 20MHz inclusive with a jump straight to the 5Vpp limit thereafter. Certain other waveforms are curtailed by a 10Vpp limit but definitely not the sine and square waveforms in the case of the FY6600 and FY6800 models (and quite possibly the same applies to this new model despite what it says in its user guide/manual). The 20Vpp frequency range limit on sine and square waves at least, would also be worth making a quick test of if you still have a little more time to spare.  >:D

 BTW, this the "embarrassed" icon you were searching for  :-[  I've had to use it a (mercifully) few times already since I joined the forum membership some eight months ago now.  ::)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: windsmurf on July 27, 2019, 06:39:53 am
I get 404 errors when I try to download the FY6800 user guide, on both the Google Drive as well as Local download links.... :--

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: PA0PBZ on July 27, 2019, 06:55:33 am
I get 404 errors when I try to download the FY6800 user guide, on both the Google Drive as well as Local download links.... :--

Confirmed, another fail  :palm:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 27, 2019, 06:57:31 am
Feeltech - it seems you are genuinely trying to address a number of issues.  This is a good thing.

The road ahead will be difficult.  I wish you well.

Thanks for your reply. In the future, we will refer to customers' suggestions and help them solve after-sales problems.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 27, 2019, 07:04:03 am
I get 404 errors when I try to download the FY6800 user guide, on both the Google Drive as well as Local download links.... :--

We are very sorry about it. Our staff will redo the website. Please use this Google Drive download documents. 
https://drive.google.com/open?id=0B3N_NW8vylrmWU93b0EwRjhrQlE
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: DC1MC on July 27, 2019, 07:06:50 am
Hi Feeltech

The link to the documentation and software works from Germany:

 http://en.feelelec.com/index.php?case=archive&act=list&catid=6 (http://en.feelelec.com/index.php?case=archive&act=list&catid=6)

In the page there one can found some links to things like:   FY6900 User Guide

The links point to a rar archive that contains FY6900 User Guide AND Software

So the quickest and cheapest way is to modify the page to page to say the right thing:  FY6900 User Guide and Software.


Also, for the forum members, do not try to be fluent in English, it is clear that whoever manages the Feeltech account now, it understands a bit of English but not exceedingly much. So try to keep the your sentences shot and to the point. I may know that I'm not the biggest fan of Chine technology but at least there seem to be a sliver of goodwill and things moving in the right direction and this should be encouraged.

 Cheers,
 DC1MC
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 27, 2019, 07:08:09 am
Confirmed, another fail  :palm:

Sorry, dear customers. Please use the Google Drive download the documents. We will send the website link after we finish the website.
https://drive.google.com/open?id=0B3N_NW8vylrmWU93b0EwRjhrQlE

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: PA0PBZ on July 27, 2019, 07:10:09 am
Confirmed, another fail  :palm:

Sorry, dear customers. Please use the Google Drive download the documents. We will send the website link after we finish the website.
https://drive.google.com/open?id=0B3N_NW8vylrmWU93b0EwRjhrQlE

FeelElec

The FY8600 folder in there is EMPTY!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 27, 2019, 08:29:15 am
The FY6800 folder in there is EMPTY!

Please check it once again, we upgrade the documents.
https://drive.google.com/drive/folders/0B3N_NW8vylrmWU93b0EwRjhrQlE

If also can't open it, please contact me in time.
My sincerest apologies。

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: feeltech on July 27, 2019, 08:41:17 am
Hi Feeltech

The link to the documentation and software works from Germany:

 http://en.feelelec.com/index.php?case=archive&act=list&catid=6 (http://en.feelelec.com/index.php?case=archive&act=list&catid=6)

In the page there one can found some links to things like:   FY6900 User Guide

The links point to a rar archive that contains FY6900 User Guide AND Software

So the quickest and cheapest way is to modify the page to page to say the right thing:  FY6900 User Guide and Software.


Also, for the forum members, do not try to be fluent in English, it is clear that whoever manages the Feeltech account now, it understands a bit of English but not exceedingly much. So try to keep the your sentences shot and to the point. I may know that I'm not the biggest fan of Chine technology but at least there seem to be a sliver of goodwill and things moving in the right direction and this should be encouraged.

 Cheers,
 DC1MC

Thanks for your suggestions, we will accept your suggestion when building the website.

FeelElec  :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 30, 2019, 08:54:05 am
2.  Can you tell us what changes have been made in the FY6900 other than the case?  Specifically, some resellers are advertising a feature called "Magic Pulse", which supposedly eliminates jitter in certain square waves.  Is this a real thing?

Dear Customers,
This video shows the magic pulse function:
https://www.youtube.com/watch?v=1addM9svUOI&t=18s (https://www.youtube.com/watch?v=1addM9svUOI&t=18s)

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on July 30, 2019, 10:57:16 am
"Magic Pulse" function works only for the rectangular waveform?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on July 30, 2019, 11:37:11 am
What's the video supposed to be showing. :-//
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 30, 2019, 06:57:53 pm
"Magic Pulse" function works only for the rectangular waveform?

 Essentially, it only has to deal with sharp edged transients such as the square wave and its close cousins which contain an "instantaneous transition" between voltage levels (sawtooth and ramps etc). Sinusoidal waveforms are free of the 4ns DAC clock jitter that afflicted the square wave and its cousins in the previous FY6xxx models.

 For anyone not fully acquainted with this issue in their FY6600 and FY6800 function generators, there's a simple test which neatly demonstrates the issue in slow motion (you need an oscilloscope of any type with at least a 15MHz bandwidth - single channel with an external trigger port will suffice at a minimum[1] if you don't have the more usual dual or quad channel DSO to hand).

 Configure your function generator for 5MHz on both channels. Pick a convenient voltage level such as 5Vpp (2.5Vpp into 50 ohm load) and initially set both waveforms to square. Nominate one channel as your 'scope's trigger source and apply a 30mHz frequency offset[2] to the other channel and observe how it changes its phase displacement with respect to the triggering waveform (or slips past the triggering point if using a single channel 'scope triggered from an external trigger input signal set to precisely 5MHz).

 Now go through each waveform type in turn on the channel with the 30mHz offset and observe its side slipping behaviour. You might want to create a table of your observations against each waveform type but that's optional. It shouldn't take too long to determine which waveform types slide smoothly past the trigger point and which slip past it in 4ns increments.

BTW, this was the test I'd rather hoped chickenheadknob would be able to try out with his newly acquired FY6900. I guess he really mustn't have any spare time after all. It's a pity because it would have proved a lot more enlightening than that rather cryptic youtube video demo just posted by FeelElec, supposedly demonstrating their "MagicPulse" technology.

Hopefully, you should find two zipped mkv movies attached to this post. I say hopefully since the posting of attachments interface seems to be rather flakey since they updated it just recently.

[EDIT] The bug persists! I'll send the missing attachment in my next post...


[1] You can even use an old boat anchor 'scope with as low a BW as 5MHz provided you use a frequency setting of 1.25MHz instead of the "Magic" 5MHz initially chosen for this test. Remember, you need a bandwidth of at least three times that of a square wave's fundamental frequency in order for the 'scope to display a reasonable facsimile of said square wave.

[2] The 30mHz offset was chosen to provide a strobing effect at a convenient rate of one jump every few seconds. A larger offset value will speed up the strobing effect - select a value that suits your taste. For sinusoidal waves, it will simply alter the speed at which these waveforms glide smoothly along the X axis.

JBG
 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 30, 2019, 07:10:41 pm
What's the video supposed to be showing. :-//

 That's an interesting question. As is the usual with such 'promotional' videos, a complete lack of information on what frequency of square waves they are actually using for this demo. An audio commentary could have helped make up for the abysmal resolution chosen for this video.

 Haven't these daft buggers at least heard of 720x576 if not the more appropriate 1280x720 and 1920x1080 resolutions to make up for the absence of a commentary track? You'd almost think they didn't want to give anything away in this video. >:(

 Anyway, further to my previous posting, please find attached the second of my zipped mkv movie files that the kakamaimee eevblog posting UI managed to drop on the floor.

[EDIT] I see what they did! They (eevblog's ui) dropped my first attachment.  >:(  >:(  >:(

 Ho hum, let's try sending the one they dropped...again!!!  >:(  >:(  >:(  >:(  >:(  >:(

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 30, 2019, 07:15:13 pm
The lost attachment!

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 30, 2019, 07:32:42 pm
Ok everyone!

 It looks like both attachments finally made it into this topic thread for all to enjoy (and perhaps be inspired by). >:D

 For those of you wondering just what use the ability to set a ten point something MHz frequency to a precision of μHz could possibly be, wonder no longer for I believe I've just demonstrated one effective use. :)

 Admittedly at a three orders of magnitude less precision but I'm sure those with the patience to wait it out could test the μHz offset option to equal effect (take a snapshot to finally compare with 'the money shot' lest you forget what it started out as). >:D

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on July 30, 2019, 07:34:01 pm
It looks like both attachments finally made it into this topic thread for all to enjoy (and perhaps be inspired by). >:D

I could see them as soon as you posted them, 2 X Square is reference-Sine is 30mHz off.zip (2151.72 kB and 1X Sine is reference-Square is 30mHz off.zip (2135.43 kB

I know a bit about DDS and the 4ns problem, I surprised feelelec didn't make any attempt to show it, or lack of it, - well not surprised really. :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: exe on July 30, 2019, 07:47:26 pm
How does "magic pulse" work? (what a horrible name btw)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on July 30, 2019, 08:24:21 pm
How does "magic pulse" work? (what a horrible name btw)

I think that for rectangular and triangular waves it chooses just the frequency steps that align with the 4ns intervals, so no jitter but much less frequency resolution, but that's just guesswork based on no info. :)

I can't play JBG's vids in VLC as .mkv or .avi, but that might just be my PC(s).
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 30, 2019, 11:37:02 pm
How does "magic pulse" work? (what a horrible name btw)

I think that for rectangular and triangular waves it chooses just the frequency steps that align with the 4ns intervals, so no jitter but much less frequency resolution, but that's just guesswork based on no info. :)

I can't play JBG's vids in VLC as .mkv or .avi, but that might just be my PC(s).

 Triangle waves (as opposed to sawtooth), like the sine wave, aren't afflicted by this 4ns jitter issue. As for the attached files, you'll need to extract each mkv file from within each zip file before you can play them.  I suppose I could have simply cheated my way past eevblog's file type restriction by simply renaming the mkv file extension to zip. I'll try that now with one of those files...

 I tried the new fangled "Drag 'n' Drop" option - it seems to have attached something although the uploading went rather swifter than I was expecting so I'm not sure whether it actually worked .

[EDIT #2]  It worked! I downloaded them and used "open with" VLC media player to play them. I'll keep that renaming to zip trick in mind for any future movie file uploads. :)

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: chickenHeadKnob on July 31, 2019, 12:16:51 am

 
 Configure your function generator for 5MHz on both channels. Pick a convenient voltage level such as 5Vpp (2.5Vpp into 50 ohm load) and initially set both waveforms to square. Nominate one channel as your 'scope's trigger source and apply a 30mHz frequency offset[2] to the other channel and observe how it changes its phase displacement with respect to the triggering waveform (or slips past the triggering point if using a single channel 'scope triggered from an external trigger input signal set to precisely 5MHz).

 Now go through each waveform type in turn on the channel with the 30mHz offset and observe its side slipping behaviour. You might want to create a table of your observations against each waveform type but that's optional. It shouldn't take too long to determine which waveform types slide smoothly past the trigger point and which slip past it in 4ns increments.

BTW, this was the test I'd rather hoped chickenheadknob would be able to try out with his newly acquired FY6900. I guess he really mustn't have any spare time after all. It's a pity because it would have proved a lot more enlightening than that rather cryptic youtube video demo just posted by FeelElec, supposedly demonstrating their "MagicPulse" technology.

OK, I did your tests JBG. I figured you would not let go of this once learning I have a 6900 unit (sigh).  My problems at chez c-knob involve a lab in boxes and home renovation, but just for you I hauled out my o'scope and made a hole on my cramped and cluttered computer desk.

 I could not duplicate with sine,square,rectangle or triangle waves; ramps pos,neg, trapezoid, and CMOS and exponentials did however exhibit stepping. I don't want to spend any more time on further investigation right now as this "feature"  holds no obsession for me. I experimented with both sine and square wave as the source (edge) trigger channel. It did not change the cohort of wave shapes which exhibited stepping.

One probably irrelevant issue is that my cabling setup was haphazard and not properly terminated so there was a small amount of ringing with square waves.   The CMOS and trapezoid shapes were free of obvious ringing and they were stepping.

Testing at 5MHz with variable 30-70 mHz offsets
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on July 31, 2019, 12:18:47 am
"I'll keep that renaming to zip trick in mind for any future movie file uploads."

Just adding something to the end usually works and leaves the real .ext visible   ....30mHz off.mkv.txt  or even
...30mHz off.mkv.remove

I can play them after downloading a new version of VLC. :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 31, 2019, 01:10:40 am
"I'll keep that renaming to zip trick in mind for any future movie file uploads."

Just adding something to the end usually works and leaves the real .ext visible   ....30mHz off.mkv.txt  or even
...30mHz off.mkv.remove

I can play them after downloading a new version of VLC. :)

 Ok StillTrying,

 Thanks for the feedback. TBH, it did cross my mind to simply tack a .zip onto the end... after renaming them. ::)

 Anyway, although it's nowhere near being past my normal bed time (it's only 2am), I'm off for an "early night". ;)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on July 31, 2019, 07:35:53 am
Dear Customers,
We updated a video with subtitles about FY6900 "Magic Pulse" function in youtube.
https://www.youtube.com/watch?v=wxi_vpUhJwY&feature (https://www.youtube.com/watch?v=wxi_vpUhJwY&feature)


FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on July 31, 2019, 09:06:04 am
"We updated a video with subtitles"

I think that's actually worse, it confirms that you're not showing any of the unique properties of "Magic Plus", just some 2.71MHz square/pulses.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: beanflying on July 31, 2019, 09:18:44 am
"We updated a video with subtitles"

I think that's actually worse, it confirms that you're not showing any of the properties of "Magic Plus".

Not to mention 'Magic' and Professional are just synonymous with kwality Test Gear  ::)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on July 31, 2019, 10:55:14 am
Men, enlighten me: it is jitter? Or what is it?
Shaking line is about 200ps ..
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 31, 2019, 11:02:27 am
"We updated a video with subtitles"

I think that's actually worse, it confirms that you're not showing any of the properties of "Magic Plus".

 To be fair, it looks like they're trying to demonstrate their version of Siglent's "EasyPulse" technology... and failing badly for want of screen resolution in their demo video. 360p just doesn't cut it in this case. If they'd used 720p or (better yet) 1080p, it would have allowed their audience to see the actual 'scope settings they were using (and very likely the generator settings as well) which would have saved any need for sub-titles in the first place. ::)

 If you're not familiar with Siglent's "EasyPulse" technology, here's a link to the manual for the SDG1062X Signal Generator which boasts this feature (along with, interestingly enough, a mention of 150Msps 14 bit sampling >:D).

http://www.labtronix.co.uk/drupal/sites/default/files/sdg1000x/SDG1000X_DataSheet_DS0201X_E01A.pdf (http://www.labtronix.co.uk/drupal/sites/default/files/sdg1000x/SDG1000X_DataSheet_DS0201X_E01A.pdf)

The relevant DSO trace screen captures are on the fourth page of that document where it looks like they've sacrificed a potential rise and fall time speed of circa 6ns with a 6.67ns jitter for an 18.2ns Tr and Tf with a residual noise jitter of just 200ps rms or so.

 My initial calculated potential improvement before I saw the actual figures had suggested 12ns Tr and Tf figures - the detail reveals they'd made an even greater sacrifice than just one extra clock cycle, it looks more like two extra clock cycles are being sacrificed on the altar of low jitteryness with their slower 150Msps sampling rate - Tr and Tf times as enduring as 18.2ns!  ::)

  I wonder whether the technique inherently demands an extra two cycles to be sacrificed rather than just the one cycle it seems FeelTech had opted for in their own initial attempt to solve this issue on square waves (7.2ns versus the 3.8ns if they hadn't bothered at all - the other waveforms which contain such 'instant' transitions do so with rise and fall times of just 3.8ns). ::)

 I noted this apposite factoid taken from the "Key Features" list on the 2nd page of that pdf

"Special circuit for Square wave function, can generate Square waves up to 60 MHz with jitter less than 300 ps+0.05 ppm of period"

 which I think answers the question "Only Square Waves?"  ;) I mean, if it's good enough for Siglent (on a dual channel 60MHz AWG costing over five times the price of FeelElec's latest effort), then it ought to be just fine for Feeltech's customers too - just my attempt to keep things in perspective.  :-DD

[EDIT]
====================================================================================
 My bad! On taking another look at that "Key Features" list, it seems they're referring to an entirely separate feature aimed at only the square wave function (quite possibly just a squaring circuit driven from the sine wave output with it's own level adjustment circuit - the sort of add on device one could attach to any sine wave generator to achieve low jitter square waves - in this case, integrated into the SDG1062X Signal Generator itself).

 However, since it's a technique which strongly resembles Siglent's (and no doubt every other brand's) solution to edge jitter on pulse waveforms, it probably applies to more than just the square wave example that FeelElec chose for their demo. No doubt, when FeelElec redo their demo video, they'll think to include another pulse waveform.
===================================================================================

 To Feeltech/FeelElec, may I suggest you redo that video in a high enough resolution to allow your potential customers to actually see the 'scope and generator settings? After all, it'll save you having to bother with an audio or subtitled commentary - "A picture (in this case a movie clip) can save a thousand words"... but only if it has sufficient resolution. ::)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 31, 2019, 11:07:44 am
Men, enlighten me: it is jitter? Or what is it?
Shaking line is about 200ps ..

 Prey, do tell. How did you manage to discern that from such an ultra low res video?  :)

 JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on July 31, 2019, 11:10:41 am
PrtScr  ;)

Can be even bigger, if you like..

It is HD 1080p actually as you can see in the bottom right..


So, is it that jitter Magic Pulse technology is about?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on July 31, 2019, 11:43:54 am
Men, enlighten me: it is jitter? Or what is it?
Shaking line is about 200ps ..

I'm quite sure it's the scope's sinx distortion and nothing at all to do with the SG or jitter.

To be fair, it looks like they're trying to demonstrate their version of Siglent's "EasyPulse" technology... and failing badly for want of screen resolution in their demo video.

A complete fail on showing what Magic pulse does wouldn't matter, everybody makes mistakes, etc., but I'm including the other fails such as turning up after 18 months ? and saying sorry we didn't have the staff, were the staff numbers less than 1 ? :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: exe on July 31, 2019, 01:14:38 pm
afaik when new video is uploaded, it first only available in 360p. Only after a while higher resolutions are available (bc I've seen similar complains on last the signal path video).
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 31, 2019, 04:44:26 pm
PrtScr  ;)

Can be even bigger, if you like..

It is HD 1080p actually as you can see in the bottom right..


So, is it that jitter Magic Pulse technology is about?

 Well, for some reason when I go to youtube to watch that video in a higher resolution, I still can't select any higher res than  the 360p initially offered. The missing options suggestions are no help and searching for a hi-res version fails to find any. I've just spent the past few hours watching 1080p youtube vids, mostly high tech electric aircraft vids, to verify that the problem isn't an Opera issue. Do you have a direct link to that 1080p version you found that you can post?

 As for the type of jitter, it can only be the 4ns clock jitter rather than the typical 200ps rms jitter that afflicts all waveforms regardless.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on July 31, 2019, 05:07:05 pm
I can turn the quality up to 1080p on the latest video, the quality goes up but there's not much extra info to see!
I can't see a way to link directly to the 1080p version.

Code: [Select]
www.vdyoutube.com/watch?v=wxi_vpUhJwY
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 31, 2019, 08:13:58 pm
I can turn the quality up to 1080p on the latest video, the quality goes up but there's not much extra info to see!
I can't see a way to link directly to the 1080p version.

Code: [Select]
www.vdyoutube.com/watch?v=wxi_vpUhJwY

 Thanks for that YT d/l link, StillTrying.

 The best quality I could d/l was a 1280x720 version but that was sufficient to show what I needed to know. A 2.71MHz square wave on a 100ns per div X-axis scale isn't the most revealing of settings. Still, at least it wasn't a 2.5 or 5MHz setting to hide the 4ns jitter from view. The 4ns jitter is quite visible at 2.71MHz on an FY6600, modified or not.

 However, I did notice they'd taken care not to include the Tr and Tf figures in the statistics display. I guess we're just going to have to wait for a proper, independent review to materialise before we get to see just how much of a benefit this "Magic Pulse" business will prove to be.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 02, 2019, 06:38:44 am

 
 Configure your function generator for 5MHz on both channels. Pick a convenient voltage level such as 5Vpp (2.5Vpp into 50 ohm load) and initially set both waveforms to square. Nominate one channel as your 'scope's trigger source and apply a 30mHz frequency offset[2] to the other channel and observe how it changes its phase displacement with respect to the triggering waveform (or slips past the triggering point if using a single channel 'scope triggered from an external trigger input signal set to precisely 5MHz).

 Now go through each waveform type in turn on the channel with the 30mHz offset and observe its side slipping behaviour. You might want to create a table of your observations against each waveform type but that's optional. It shouldn't take too long to determine which waveform types slide smoothly past the trigger point and which slip past it in 4ns increments.

BTW, this was the test I'd rather hoped chickenheadknob would be able to try out with his newly acquired FY6900. I guess he really mustn't have any spare time after all. It's a pity because it would have proved a lot more enlightening than that rather cryptic youtube video demo just posted by FeelElec, supposedly demonstrating their "MagicPulse" technology.

OK, I did your tests JBG. I figured you would not let go of this once learning I have a 6900 unit (sigh).  My problems at chez c-knob involve a lab in boxes and home renovation, but just for you I hauled out my o'scope and made a hole on my cramped and cluttered computer desk.

 I could not duplicate with sine,square,rectangle or triangle waves; ramps pos,neg, trapezoid, and CMOS and exponentials did however exhibit stepping. I don't want to spend any more time on further investigation right now as this "feature"  holds no obsession for me. I experimented with both sine and square wave as the source (edge) trigger channel. It did not change the cohort of wave shapes which exhibited stepping.

One probably irrelevant issue is that my cabling setup was haphazard and not properly terminated so there was a small amount of ringing with square waves.   The CMOS and trapezoid shapes were free of obvious ringing and they were stepping.

Testing at 5MHz with variable 30-70 mHz offsets

Ok, I did your test JBG, too.
There's really something m a g i c about this FY6900  8)
See attachments, blue trace sine is trigger, yellow trace square is sliding fluently, just little bit twisting and curling  :o - don't know why!
From time to time there is skip like jitter but not very often.
Short videos show this curling/twisting of the yellow trace.  :P

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 02, 2019, 06:41:35 am
and another movie  :scared:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 02, 2019, 06:42:44 am
and last one  :-//
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 03, 2019, 03:48:18 am
and last one  :-//

 Ok, evava, and thanks for those interesting one second clips.  :)

 I had to set VLC to playback at 0.03 real time to see what was going on. I noticed a single brief 4ns ghost jitter in amongst the more continuous movements made up of tiny sub nanosecond 'jumps' in the first two videos but no sign of such a ghost jitter in the third.

 The 5MHz and 20MHz examples showed a curious 'double vision' effect whilst the 30MHz sample was showing a 'triple vision' effect. Most curious indeed! Just how do they do that!?

 As for the 'wiggly' effect, some of that might be the higher frequency components interacting with the sampling rate of the generator's DAC as they approach the HF end of the anti-aliasing filter's cut off frequency, supposedly somewhere between 75 and 100MHz.

 I've seen similar wrigglyness (but without any double and triple vision effects) on the amplitude and the flanks of the Sinc Pulse waveform at 10MHz as it slides past my homebrewed GPSDO's 10MHz square wave trace (the triggering signal in this case).

 At these frequencies, there may also be some cross-talk effect between the two channels so I wouldn't get too distracted by such wrigglyness. However, what can't be ignored is the double and triple vision effect which must be a side effect of whatever this "Magic Pulse" process is doing. I've not see such an effect on my more humble FY6600. That appears to be a new feature of the FY6900.

 Otherwise, when you're not using this 30mHz offset trick to reveal these signal generators' shortcomings, how does it perform with more normal settings? Can you still observe such effects on the square wave without resorting to the use of a 30mHz offset from a "Magic Frequency"?

 It does beg the question as to whether you'd see a similar effect if you run this 30mHz offset trick on a Siglent SDG1062X at its 'magic frequency' (based on a 150MHz sampling rate of course - 3MHz in this case). :-//

 I think I may have a new motto: "You make 'em, I break 'em.".  >:D

 Incidentally, just out of curiosity, I processed those clips with Handbrake to compress them into mkv container files and converted the 1st two 3MiB clips into 1.2MiB mkvs and the 3rd 4MiB clip into a 1.5MiB mkv. If you'd supported the camera on a tripod to steady the footage, I'd have probably been able to get a bit more compression.

 I reckon you'd have been able to offer 5 second or longer clips within the 4MB limit if you'd chosen a lower resolution such as 1280x720 of footage shot from a locked off tripod supported camera and compressed them with Handbrake or a similar video compression tool. Even 720x576 would likely have shown sufficient detail and allowed you to offer even longer clips within the 5MB limit, just a suggestion to get the most out your movie files if you want to avoid hosting them on youtube just so you can post youtube links instead of 4 and 5 MB attachments.

 At the time I did my own low res movie clips, I'd had a 2MB limit in mind. Knowing now that I can post 4MB clips, I'll try using 720x576 to create 20 to 30 second clips next time. You don't always need full HD to show short movie clips of unusual 'scope traces.  ;)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 03, 2019, 04:27:55 am

 
 Configure your function generator for 5MHz on both channels. Pick a convenient voltage level such as 5Vpp (2.5Vpp into 50 ohm load) and initially set both waveforms to square. Nominate one channel as your 'scope's trigger source and apply a 30mHz frequency offset[2] to the other channel and observe how it changes its phase displacement with respect to the triggering waveform (or slips past the triggering point if using a single channel 'scope triggered from an external trigger input signal set to precisely 5MHz).

 Now go through each waveform type in turn on the channel with the 30mHz offset and observe its side slipping behaviour. You might want to create a table of your observations against each waveform type but that's optional. It shouldn't take too long to determine which waveform types slide smoothly past the trigger point and which slip past it in 4ns increments.

BTW, this was the test I'd rather hoped chickenheadknob would be able to try out with his newly acquired FY6900. I guess he really mustn't have any spare time after all. It's a pity because it would have proved a lot more enlightening than that rather cryptic youtube video demo just posted by FeelElec, supposedly demonstrating their "MagicPulse" technology.

OK, I did your tests JBG. I figured you would not let go of this once learning I have a 6900 unit (sigh).  My problems at chez c-knob involve a lab in boxes and home renovation, but just for you I hauled out my o'scope and made a hole on my cramped and cluttered computer desk.

 I could not duplicate with sine,square,rectangle or triangle waves; ramps pos,neg, trapezoid, and CMOS and exponentials did however exhibit stepping. I don't want to spend any more time on further investigation right now as this "feature"  holds no obsession for me. I experimented with both sine and square wave as the source (edge) trigger channel. It did not change the cohort of wave shapes which exhibited stepping.

One probably irrelevant issue is that my cabling setup was haphazard and not properly terminated so there was a small amount of ringing with square waves.   The CMOS and trapezoid shapes were free of obvious ringing and they were stepping.

Testing at 5MHz with variable 30-70 mHz offsets

 Apologies for the tardy response.  :-[

 I'd gotten a little distracted by the low res youtube video issue I'd been experiencing so your reply got pushed so far onto the back burner, it took evava's reply to remind me about it and the fact that I hadn't actually made a reply.

 Anyway, thanks for taking the time to run those tests which seem to indicate that this Magic Pulse is only being applied to square waves. Sine and triangle waves didn't suffer from this 4ns clock jitter effect anyway, just square waves and any other waves with an instant transition between voltage levels such as ramps and sawtooth waveforms.

 It rather looks like they've moved the square wave out of the jittered waveform category and into the jitterless category which includes sine and triangle waveforms. I'll have to test the trapezoidal wave since I'd have expected it to be free of this jitter just like the triangle wave which I'd swear was a (surprisingly) jitterless example when I first checked it out.

 Anyway, that's more food for thought. I'll have another look at what is and what isn't free of this 4ns jitter on my FY6600 when I get some free time. I'm currently trying to complete a GPSDO project I've just started transferring from a prototyping breadboard lashup onto a piece of veroboard that I've prepped up to slide into a small extruded aluminium project enclosure, so I'm a little preoccupied right now - I do appreciate were you're coming from  :)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 03, 2019, 09:25:23 am
Thank you JBG for your answer.
Indeed it must have been some crosstalk or crossmodulation between channels or external modulation  of a special kind.
If I set both channels to square wawe this triple curling appears in both channels!

(you can set your player to continuously replaying this short clip, so you can better see what is going on)

If I push Single on scope, there are always just thin lines (yellow and blue ones), but always they have another shape.
Photos in next post.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 03, 2019, 09:31:35 am
pictures:

Go figure!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on August 03, 2019, 10:14:36 am
"If I set both channels to square wave this triple curling appears in both channels!"

Are the curly edges still there with both channels set to frequencies that align exactly with the 4ns sampling times, 1Mhz and 2MHz would do.

15Mhz, yellow trigger, both square, both trippled.jpg
If the scope's 1GSa/s there's only 2.5 samples per division, most of those curls will be the scope's Sinx doing the best it can with so few samples on the edge.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 03, 2019, 10:51:05 am
"If I set both channels to square wave this triple curling appears in both channels!"

Are the curly edges still there with both channels set to frequencies that align exactly with the 4ns sampling times, 1Mhz and 2MHz would do.

Blue: 2Mhz, not curling
Yellow: trigger, 30mHz next to, curling.
No jitter.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 03, 2019, 10:56:49 am
And trigger vice versa:

Blue: trigger, 2Mhz, not curling
Yellow: 30mHz next to, curling.
Again, no jitter.

Instead of jitter there seems to be curling?  :-//
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 03, 2019, 12:40:42 pm
And 100kHz:

- time base 5ns per division, you see leading edges
- yellow trace 100kHz,
- blue trace trigger, 300uHz next to, curling
yellow slips slowly, then skip (jitter?), and again slips slowly, while blue trace is constantly curling!

They are trying so desperately to suppress the jitter..or?

I wonder, how Siglent or Rigol cope with that?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 03, 2019, 03:45:55 pm
Thank you JBG for your answer.
Indeed it must have been some crosstalk or crossmodulation between channels or external modulation  of a special kind.
If I set both channels to square wawe this triple curling appears in both channels!

(you can set your player to continuously replaying this short clip, so you can better see what is going on)

If I push Single on scope, there are always just thin lines (yellow and blue ones), but always they have another shape.
Photos in next post.

 That was a more informative video clip. I tried setting VLC to play those 1 second clips on a continuous loop but the best I could do was to get it to play two passes at a time. I had more luck with this 3 second video and the trick appears to be to set the B point a few frames short of the bitter end to achieve continuous loop play. I guess the brevity of those 1 second clips was the reason for my limited success with loop play.

 It's surprising what a difference reducing the resolution from full HD down to a 1280x720 clip does for the playing time you can get out of a 4.5MB clip. I'd expect just mounting the camera onto a tripod, locked off to eliminate any camera wobbles would let you get more time for a given file size.

 All the common video formats use lossy compression to minimise storage requirements (and reduce writing speed to the media), so the less changes, frame to frame, that have to be recorded, the less the amount of picture data that has to be sent in each group of pictures (GoP), typically half to one second's worth of frames between a total refresh of each key frame during which only frame to frame differences are recorded.

 "Wobbly-cam" recordings aren't much of an issue when you're hosting your home movies on Youtube but when it comes to trying to cram a few second's worth of video into a 4 or 5 MB attachment limit, this sort of care in the camera work becomes rather more critical. If you don't have a tripod, you can arrange some sort of stable support to rest the camera upon (a stack of hardback books for height adjustment on a chair or small table for example).

 Anyway, having noted those points regarding video technique, I can comment on the effect of this "Magic Pulse" you'd managed to capture. The "Magic" has obviously eliminated the gross 4ns jumps you'd otherwise be seeing with a 6600 or 6800 function generator, lending the movement a more liquid, if ripply, appearance.

 It looks like the 'jumps' in phase are now around the 1.5ns mark. The tripling up looks like it could be the effect of the 'scope using some sort of persistence (a one second persistence setting perhaps?), otherwise I'd expect this tripling up effect to produce a blurred image rather than the crystal sharp images of seemingly three horizontal scans worth overlaid on top of each other.

 It's quite obvious that you're terminating the 'scope end of those BNC cables with 50 ohms (5Vpp settings with the scope showing circa 2.5Vpp values) so we can't blame badly matched cables for any of these effects. It would be interesting to see whether others in your priviledged position of FY6900 ownership would see the same effect using a different make and/or model of DSO like a Siglent SDS1202X-E for example  ;)

 Anyway, that's something to ponder on and I thank you for your contribution, both for this longer clip :) and for reminding me about the forgotten loop playback option in VLC. :palm:

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 04, 2019, 09:36:11 am
Hi JBG,
thank you for your kind words and new information in every your post.
And thank you for pointing me to Persistence setting on the scope, I have never thought it has much use. (I was wrong, obviously).
And support for camera is now ready  :)

Quote
It's quite obvious that you're terminating the 'scope end of those BNC cables with 50 ohms (5Vpp settings with the scope showing circa 2.5Vpp values) so we can't blame badly matched cables for any of these effects
Yes, I use "Banggood Special" ones, 50(?!) Ohm feed-through terminators. They work just ok.

Quote
The tripling up looks like it could be the effect of the 'scope using some sort of persistence (a one second persistence setting perhaps?), otherwise I'd expect this tripling up effect to produce a blurred image rather than the crystal sharp images of seemingly three horizontal scans worth overlaid on top of each other.

In all previous pictures and videos I had scope persistence set to "Min".

For better clarification I am now attaching pictures a videos with persistence set to "Min" and then to "Infinite", to maybe allow you to discern what is the feature of my Rigol and what not.

P.S. I like your polite English very much :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 04, 2019, 09:38:20 am
15MHz, persistence to "Min" - like in all previous videos.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 04, 2019, 09:39:31 am
15MHz, persistence set to "Infinite".

It seems to me that "Infinite" setting behaves rather like "Min" setting should behave...  :-//

Other settings (except Min and Infinite) behave like expected.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on August 04, 2019, 11:43:26 am
The "Magic" has obviously eliminated the gross 4ns jumps you'd otherwise be seeing with a 6600 or 6800 function generator, lending the movement a more liquid, if ripply, appearance.

Don't forget that the sine waves will still have the up to +/- 2ns sample timing jitter, it's just that the sine's amplitude can be corrected to fit the +/- 2ns off position. So there'll still be some timing wobble depending on the analogue BW between the DAC and squarer.

"It looks like the 'jumps' in phase are now around the 1.5ns mark."

I think at the mid level of the square waves it's better than that. I still don't know what their video was supposed to be showing. :)
Going by the threads on here it seem that many don't trust the Rigol even in dot mode when it gets down to only 2 samples on a fast edge.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on August 04, 2019, 12:20:10 pm
Both traces square, both 150Hz , persistence Infinite:

And - jitter 4ns, finally!

Is this FY6900 better than FY6600/6800, can someone compare?
Is it upgrade or downgrade?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on August 05, 2019, 03:24:20 pm
"Both traces square, both 150Hz , persistence Infinite:
And - jitter 4ns, finally!"


If they're squaring up a sine wave I'd expect some jitter to still be there at 150 kHz if it's a none 4ns frequency, when you get up to MHz the analogue BW will smooth the gaps in the sine's samples, the same as sinx draws between samples.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 06, 2019, 03:59:24 am
Hi JBG,
thank you for your kind words and new information in every your post.
And thank you for pointing me to Persistence setting on the scope, I have never thought it has much use. (I was wrong, obviously).
And support for camera is now ready  :)

Quote
It's quite obvious that you're terminating the 'scope end of those BNC cables with 50 ohms (5Vpp settings with the scope showing circa 2.5Vpp values) so we can't blame badly matched cables for any of these effects
Yes, I use "Banggood Special" ones, 50(?!) Ohm feed-through terminators. They work just ok.

Quote
The tripling up looks like it could be the effect of the 'scope using some sort of persistence (a one second persistence setting perhaps?), otherwise I'd expect this tripling up effect to produce a blurred image rather than the crystal sharp images of seemingly three horizontal scans worth overlaid on top of each other.

In all previous pictures and videos I had scope persistence set to "Min".

For better clarification I am now attaching pictures a videos with persistence set to "Min" and then to "Infinite", to maybe allow you to discern what is the feature of my Rigol and what not.

P.S. I like your polite English very much :)

 Regarding the double and triple vision effect, I've just had a thought that it might simply be an artefact of the camera due to the shutter speed allowing two or three screen refreshes to be captured. On second thought, after having another look at the latest 30MHz clip, perhaps not.

 Persistence is usually used to emulate a CRO's averaging effect through the long persistence phosphors used in the CRT which provided an indication of where the trace would be painted most often and where it would paint infrequently when using a high horizontal scan frequency, giving a better visual impression of the jitter noise and just plain noise on the waveforms being displayed.

 Early DSOs didn't include such CRT persistence effects which were missed by users who had upgraded from a CRO to a DSO and had been relying on this extra 'information' they'd been able to glean from this 'defect of persistence' that had been eliminated in the earlier DSO models. Suffice to say, FeelElec's 'scope settings must be making use of persistence to demonstrate the reduction of the 4ns jitter on square waves in exactly the same way that Siglent have seemingly done in their own 'scope trace captures shown in the data sheet for their own generators blessed with their own "Easy Pulse"(tm) feature.

 Multiple traces like the ones in your own screenshots and movie clips, ime, tend to be down to the DSO's trigger processing becoming confused by a level of randomness in the triggering signal, typically seen when trying to examine the HF ripple on the output rails of an SMPSU.

 I suspect the technique being used is a close relative to the concept of adding 'dither noise' to a music CD recording to convert the more objectional quantisisation noise to a less objection 'tape hiss' like background noise. In this case, it would appear that the 4ns jitter has been traded in for a 1ns randomised jitter in this case, judging as best as I can from those traces. I can't blame Siglent for using persistance in their own trace captures. Without such persistance, the crystal clarity is actually masking the true random nature of the phase dither noise that's now replacing the gross 4 and 6.7ns clock jitter that would otherwise show up without the Magic Pulse and Easy Pulse processing in each respective case.

 Of course, I could be completely off the mark but that's my best guess as to what's happening here. You probably only need a 1 second's worth of persistence to give a more accurate impression of the effectiveness of FeelElec's "Magic Pulse" processing. The only troubling thing about FeelElec's version of Siglent's Easy Pulse technique being the evidence of the occasional rogue 4ns jitter transient.

 I suspect that a frame by frame search of a minute or more's worth of movie footage without the use of persistence, using a Siglent generator in this test at its "Golden Frequency" of 3MHz, would reveal a similar result but without any rogue transient 6.6667ns ghost jitter events (or not - who's to say Siglent have done any better a job of this? - as far as anyone knows, such a test has never been done before).

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on August 06, 2019, 06:54:20 am
JBG you're describing 'waveform averaging' rather than persistence. I still think they're squaring up a DDS sine wave, but I won't be buying one just to do some tests. :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 06, 2019, 12:43:19 pm
JBG you're describing 'waveform averaging' rather than persistence. I still think they're squaring up a DDS sine wave, but I won't be buying one just to do some tests. :)

 You and me, both! :)

 TBH, I can't imagine that many owners of the FY6600 and 6800 models would be tempted to go for such a modest "upgrade" as represented by the improvements offered in the FY6900. That's not to say that when it comes to a hobbyist's choice of first time AWG, the FY6900 would be the one to go for despite the modest price premium over the now cheaper offerings of the older models.

 The PSU must surely be an "improved" +/-15 volt design simply to allow it to meet its DC to 5MHz 24Vpp specification alone. A 20% boost over the "Industry Standard" P2P limit is more marketing gimmick than any genuine asked for improvement. The traditional solution to obtaining higher voltage test signals has always been provided by the simple expedient of inserting a linear amplifier into the signal chain to serve this less common requirement. What self respecting EE doesn't keep a suitable linear amp to hand in their test lab for just such unusual testing scenarios? ;)

 I'm looking forward to seeing the first comprehensive review and tear down youtube video, even if it's simply to satisfy prurient curiosity.  :popcorn:

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on August 06, 2019, 02:01:14 pm
I am waiting for my KKMOOM 6900 60 MHz ;D
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on August 06, 2019, 02:50:17 pm
Why do they market these things with names like KABOOM and JUNKTEK.

It doesn't matter how magical and mysterious the pulses are, I wouldn't buy one while they show 8kHz as 00'008,000.000'000'000'000  >:D
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: excitedbox on August 11, 2019, 05:05:16 pm
My biggest problem is the website. As a web designer I don´t understand how any business can neglect their store and image. Your website is essentially a store location like a brick and mortar store at 1% of the cost but 1000x the value. If you walked into a pizza place with outdated or missing menus, broken tables and chairs that didn´t give you what you ordered (broken links), you would never go back.

A website is also a representation of your company and it´s values. A neglected website whether broken, or outdated, reflects the service you can expect from that company. Yet maintaining a clean and professional website is a one time investment of a couple hundred for most businesses compared to the monthly rent and huge construction costs of a brick and mortar business.

It is crazy to me that many companies that spend 10s of thousands on store fixtures and thousands a month on rent are not willing to spend $500-2000 once to build an entire second store.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on August 12, 2019, 11:17:26 am
My biggest problem is the website. As a web designer I don´t understand how any business can neglect their store and image.

I keep thinking that FT's website, marketing and technical support are just a student project for stuff they buy in.
http://feelelec.com (http://feelelec.com)
http://en.feeltech.net (http://en.feeltech.net)

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: excitedbox on August 12, 2019, 05:20:32 pm
They are not the only ones though. So many businesses just don´t get it. They literally pay as much a month for 1 employee as an entire website costs and is as if you opened up a store in every town around the world.

I offered someone a website out of pity last week. Website with SEO for 250 EUROS literally 10% of my normal rate since I just wanted some extra cash and haven´t heard from them since.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: dunkemhigh on August 12, 2019, 07:59:32 pm
What's the website for? No-one is going to buy from it. Also, it may be a (relatively) trivial cost to set up, but it has to be maintained by someone, so that's an ongoing cost.

Quote
As a web designer I don´t understand how any business can neglect their store and image

MRDA :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: excitedbox on August 13, 2019, 09:03:43 am
Most websites don´t need to be maintained besides answering emails or maybe updating a few words of text every few months which takes literally minutes. Ongoing costs for a basic website are under 50 a year in hosting fees and domain name registration fees.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Heszu on August 14, 2019, 02:02:42 pm
Hi, there..
Is FY6900 equipped with Fan in the back panel ??
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on August 14, 2019, 03:43:00 pm
Hi, there..
Is FY6900 equipped with Fan in the back panel ??

No, it is only the hole so that if you want you put one. |O |O
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Jon.C on August 15, 2019, 06:39:06 pm
https://www.youtube.com/watch?v=FaNvHQW_CsQ (https://www.youtube.com/watch?v=FaNvHQW_CsQ)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: bdunham7 on August 15, 2019, 08:42:47 pm
So I got my FY6900 today.  There's actually not much to tell and the video above shows enough. I'll just mention the issues that are probably of greatest concern to most.

It's the same guts in a slightly nicer case.  However, the parts of the case that stick out don't protect the BNC jacks nor do they allow you to stand the unit on its back with a right angle power cord.  It has a 3-prong power inlet, but it appears very cheap and my cords slide on and off very easily. The whole thing is comically light.

Amplitude and frequency controls oddly allow me to select up to 60MHz on any waveform, and the amplitude available is up to 24.0V at 20MHz and below.  Scope shows that it indeed is putting out at least that, if not a bit more, into a 1M scope input.  Above 20MHz it drops to 5.00 volts, which fades away a bit at 60MHz.  It's worth noting that a square wave at 10 MHz looks much worse (rounded, distorted) at amplitudes above 5.00V.  The op amps that kick in above 5.00V obviously are struggling.

The outputs are all connected and grounded to the IEC connector ground, but the measured resistance between the front BNC shell and the power cord ground is 2 ohms or so.

The DDS-inherent 4ns issue has been altered by interpolation--just look at the square wave inching its way across the screen at the end of the above video.  A quick check shows that the issue of a 10MHz square wave having a 48ns upper and 52ns lower section has been replaced by a 10MHz square wave that has equal periods measured at the zero-crossover point, but now has a 5ns rise and 8ns fall.  It seems pretty clear that they are using an interpolation method where instead of 12 high (+) samples followed by 13 low ones (-), they use 12 high, a zero and then 12 low.  Cleverly simple, but now a 10.000001MHz square wave shows three different rise times--so that the jitter is only low if you are using the zero crossover as your trigger point--and even then, there seems to be an occasional 4ns stray waveform.  My guess is that "Magic Pulse" is a half-baked simple linear interpolation method and that it will create as many issues as it solves.  We'll see.

[attach=1]

Anyway, for a cheap-ish signal generator for hobby use, it's probably worth the US$ 86 that I paid.  There's a bit more room to build a linear PS if you want, the grounding can be undone to make it floating again fairly easily (even with the stock PS) and there's a place to install an optional fan if you like.  That's right--what looks like a fan on the back panel is actually just a place where one could be installed by you.  And while you are at it, trim the excess plastic flash out of the fake vents along the sides at the bottom....
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on August 15, 2019, 10:56:44 pm
So the only slight problem with Magic Pulse is that it doesn't work?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: SteveyG on August 16, 2019, 09:25:59 am
Here's my quick overview. Let me know if anyone needs anything specific covering in more detail

https://www.youtube.com/watch?v=FaNvHQW_CsQ (https://www.youtube.com/watch?v=FaNvHQW_CsQ)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: SteveyG on August 16, 2019, 09:26:47 am
Hi, there..
Is FY6900 equipped with Fan in the back panel ??

No, it could possibly use one though - it gets quite warm when driving 50R loads.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 22, 2019, 07:14:50 pm
Here's my quick overview. Let me know if anyone needs anything specific covering in more detail

https://www.youtube.com/watch?v=FaNvHQW_CsQ (https://www.youtube.com/watch?v=FaNvHQW_CsQ)

 Hi Steve and thanks for that revealing  teardown video. :)

 It didn't quite hit the spot (at least as far us seasoned FY66/68 hundred users and fettlers are concerned ;) ). However, it did reveal the same earthing trick used on the FY6800, namely the stolen ribbon cable wire in the PS to Main board DC rails link, one of the two ground wires snipped off at the main board end and dragged over to the earth pin on the C14 connector - you can actually see the cut end in your video.

 You were rightly concerned over the issue of the glass fuse and the inadequate insulation of the stolen ribbon cable wire in the face of its trailing over bare conductors carrying full mains voltage but you missed the fact that this 'hard' connection to the safety earth isn't actually required with a class II smpsu and should have been replaced with a 1 to 10 KR 'static drain' resistor to effectively suppress the half live mains leakage without introducing the troublesome earthing loop issues you so eloquently described.

 Who knew, given the presence of a C14 mains socket to provide access to the protective earth (a feature lacking in the FY6600 and its predecessors), that the answer to this half live mains leakage issue was as simple as a 1 to 10k 'drain' resistor to link the main board ground to the protective earth? :)

 The absence of an actual fan in the rear panel fan housing location is but a minor impediment to all of us hardy "Fixers of things broken by design", at least all the hard work has already been done for us (no need for gross mechanical modding involving the use of drills or hole saws in this case  >:D).

 One burning question remains in my mind at least and that is whether Feeltech have finally gotten round to fixing their "Skoolboy Howler" in the BOM selection for the attenuator pad that gets switched in at output voltage levels of 500mVpp and below. The BOM used for this attenuator in the FY6600 and FY6800 models is still resolutely creating a 20dBish attenuator with a nominal impedance not of 50 ohms but one that's curiously of 86ohm impedance. Therefore, I'm wondering if you can test whether this remains the case with this model?

[EDIT 2020-03-30 :- Answer: They didn't! I just spotted the evidence in this YT review video

 https://youtu.be/kA6uxUDg55M?t=368 (https://youtu.be/kA6uxUDg55M?t=368)

 which is paused just a second or two before the evidence hoves into view. You may have to jump on the pause button straight away or else back up if you fail to pause it before it cuts to the psu board. You'll be looking at the half dozen resistors which make up the two pads right alongside of their switching relays. These are numbered RS1 to RS6. Perversely, the odd numbered trio does CH2, the even numbered trio CH1. These make up Pi attenuators with 100 ohm shunt elements and a 510 ohm series element exactly as they've used with the 66 and 68 hundred models.

[END of EDIT]
==========================================================================================

 It's fairly straightforward to check. Set the output to 500mVpp at a convenient frequency and change to a 1mV amplitude step size. Having set it up this way, check the magnitude of the signal with a 'scope or LMS as you adjust between 500 and 501mV settings (or possibly it's between 499 and 500mV - around the point at which the relay kicks in and out at any rate).

 What I, and others, had discovered was that without a terminating impedance load, the change in level was as expected but when terminated with a 50 ohm load, the change in level was much greater than the expected circa 1mV (tens of mV in fact). You can either calculate the impedance by measuring the voltage drop between no load and 50 ohm load at a fixed 499mV setting in the time honoured way or else cheat by turning the amplitude down to zero or just a millivolt or two at say a frequency of 100 to 10000 Hz and literally do a resistance measurement with a DMM (after fine tuning out any DC offset, of course!).

 Being familiar with Feeltech's track record in missing every golden opportunity to put right their various "Skoolboy Howlers" to date, I'd be very much surprised if you don't see the exact same behaviour we 66/68 owners have come to see and loathe.

 Even the error in the specifications section of all the manuals concerning the PP voltage level limits versus frequency ranges has been preserved (the only difference in this case being the 24Vpp for sine and square waves being maintained right up to 20MHz as per the previous 20Vpp limit of the 66/68 models).

 One curious anomaly appears to be the ability of this new generator to output 24Vpp sine waves out of a +/-12 supply when, quite clearly in the face of the 1.2 volt worst case "headroom" figure for the THS3495 (it'll be thereabouts for the original THS3002i dual opamp used and the THS3091/3095 opamps that have been used to upgrade the 20Vpp performance at the 20MHz limit in the 66/68 models), it should be clipping at around the 22Vpp mark.

 This begs the question as to how they've achieved such a magical result. Perhaps the PSU board has been upgraded to a nominal +/-15v unit with the silk screen printing unaltered to reflect this, or else perhaps, they've incorporated a couple of boost converters on the main board to feed the THS opamp rails. Measuring the actual voltages on the rails marked as +/-12v should answer this question.

 I've no doubt there'll be other test requests from others but those are the ones that stand out in my mind. Anything else I might think up will merely be icing on the cake and I think these will be enough to burden you with for now. :)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 22, 2019, 07:48:02 pm
Hi, there..
Is FY6900 equipped with Fan in the back panel ??

No, it could possibly use one though - it gets quite warm when driving 50R loads.

 Thanks for saying that, Steve. I've had my own observation on the surprisingly high temperatures inside of these signal generators (gently) questioned by some of the contributors to the FY6600 thread (which now includes discussion of this and the FY6800 since they're essentially identical machines with just minor variations - mostly cosmetic).

 To my mind, fitting a cooling fan, whatever the model, should be one of the very first modifications to be contemplated before anything else (along with the 1 to 10K "static drain" earthing resistor which in the case of the FY6600 involves an upgrade from the C8 two pole mains connector to a three pole C6 or C14 before this can be completed - it's a trivial mod in the case of the FY6800 and this 6900 model).

 For reference, I was measuring temperatures with an IR thermometer (therefore of necessity with the lid off) of 70 deg C from the three LDO regulators with a 50 deg reading from the SMD XO only 10mm away and ditto for the FPGA and the base of the heatsink.

 Mind you, this was whilst I had modded the PSU to increase its "5V" rail from 4.96 to 5.49 volts in order to raise the 11.7v on the "+/-12v" to a less marginal 12.7v so those LDO ics were probably running some 5 degrees or so hotter than standard. Even so, I'd expect the innards to possibly be running another 15 to 20 degree warmer with the lid in place.

Plastic isn't a particularly good thermal conductor so the two hot spots on top of the case are a pale reflection of the true temperature level inside. I don't as yet possess a thermal probe to test with the lid fitted but if and when I get hold of such a probe, I'll run a fan disabled fan enabled test to confirm the efficacy of such cooling. In the meantime, the fact that the two hotspots have disappeared without trace is enough confirmation of my fan cooling upgrade's efficacy. ;)

 My main concern isn't over the effect on the 'Silicon' but rather that of the life shortening effect on all those electrolytic caps inside. I'd rather not have to do a recapping exercise after a mere two to three years of hard use (nor for that matter, risk BGA failure) so for me, "Cool" is good, "Hot" is  (literally!) bad in this case - I'd much rather have "Cool" than "Hot".  >:D

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: ed512 on August 23, 2019, 09:11:28 pm
I have received my FY6900 but am unable to get the supplied software to work.  I installed the software on a Win7 machine and it opens OK but does not seem to connect the the FY6900.  I am also looking for instructions on how to use the software and specifically how to create custom arbitrary waveforms.  Of course connecting to the FY6900 is the most important thing.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TD-er on August 29, 2019, 02:35:34 pm
I also received my FY6900, but apart from typical coil whining from the power supply, it does not work at all. If you switch off the power switch on the back, you hear the pitch change and after switch this switch again you don't hear anything.
Only after a few minutes the (annoying) coil whine is back when switching this switch on again.

I am waiting for a reply from either Banggood or Feelelec, but so far it is not the best first impression here.

Not sure what issues the older versions had with their power supply.
I wish I read this thread before buying it. :(
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 29, 2019, 04:24:47 pm
I also received my FY6900, but apart from typical coil whining from the power supply, it does not work at all. If you switch off the power switch on the back, you hear the pitch change and after switch this switch again you don't hear anything.
Only after a few minutes the (annoying) coil whine is back when switching this switch on again.

I am waiting for a reply from either Banggood or Feelelec, but so far it is not the best first impression here.

Not sure what issues the older versions had with their power supply.
I wish I read this thread before buying it. :(

 Sounds like it might be a loose connector. You've seen the video so go take a look! :) You never know, the 'cure' might be something as simple as reseating a connector.  :)

 Regarding your wishing to have read this thread before buying it, that's exactly what I did some nine months ago with the FY6600 thread when it was only 69 pages long. It took me almost three days to thoroughly read every post, followed by another day skimming through them again before ordering an FY6600-60M from a UK based seller.

 The time spent reading the thread was time well spent since I was fully prepared to deal with whatever faults it may have suffered from bad assembly through to shipping damage (as well as all those "Faulty by Design" problems I was planning on putting right).

 By the time I received mine, just over a week later, I was more than thoroughly prepared for what I expected it to be, a fun filled DIY "Fixer Upper" project. :)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: excitedbox on August 30, 2019, 05:40:39 am
Mine is sitting at customs in Frankfurt right now (since the 27th) waiting to be released. It spend 10 days sitting at the Airport in China waiting on it´s flight. But with any luck it will be here on Monday.

I hate always having to wait so long for shipping. I get so impatient  |O :scared:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TD-er on August 30, 2019, 10:29:01 am
I did wait with opening until I got a reply via the mail.
They asked me to look inside and indeed it was a loose connector.
The connector between mainboard and power supply.

I also looked at the 'ground cable' and apart from the mentioned lack of insulation level, it is also dangling on a single thread of the internal strings.
So that's going to be replaced like in the video and I will also add some shrink tube on the other mains joints just to be sure.

This ground wire is really a safety issue, since it can come loose quite ease during transport and touch one of the mains points.

The manufacturer also wrote this about the power supply:
Quote
Our power supply is + & - 13.5V and 5V, the current is 200mA.
I assume it is for all voltages.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Howardlong on August 30, 2019, 09:37:32 pm
Pro tip: a coat of clear Plasti Dip rubber coating on the knob works wonders.

I masked off the back with tape before dunking it into the tin (it might work with a spray too, I just have a small 250ml tin of it). After removing it a few second later, I left it for about three hours to dry, removed the mask and popped it back on. Like night and day.

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 30, 2019, 10:03:36 pm
Mine is sitting at customs in Frankfurt right now (since the 27th) waiting to be released. It spend 10 days sitting at the Airport in China waiting on it´s flight. But with any luck it will be here on Monday.

I hate always having to wait so long for shipping. I get so impatient  |O :scared:

 I presume that you meant the 27th of this month. That's hardly any delay at all!  :-DD  How about a 99p tracked order for ten 74hc14s that's been sitting in Hong Kong customs since the 1st of June (just two days after being shipped out of China by the seller) and is, afaik but no longer care about, still stuck in that black hole. ::)

 I'd finally had enough of all the waiting so got Ebay to 'resolve the issue' and the seller has reimbursed my 99 pence. I'd ordered half a dozen of these ICs from a UK based Chinaman at the exorbitant price of almost three quid about three weeks ago and they'd arrived just 8 or 9 days later.

 I'd have insisted on the seller making another delivery attempt (at just 9.9 pence each, one can never have too many 74HC14s in the parts bin) except for the fact that Ebay have a peculiar definition of the phrase "21 business days lack of activity" in determining when to arbitrarily close a case I'd opened in regard of a cheap (£40.41) FY6600-60M I'd ordered from a Hong Kong seller who had unsuccessfully tried to send me a second unit when the first had become overdue by a month.

 Luckily for me, the seller in this case did actually refund my account via the paypal system, no thanks to ebay's flawed disputes handling system. The strange thing in this second case was that the seller had chosen the cheapest possible shipping option which lacked any tracking options.. both times! A 99p order gets the tracked treatment yet a 40 quid one doesn't - go figure! :wtf:

[EDIT 20191017-1]
 That pack of ten 74HC14s finally popped through my letterbox on the 14th, only 4 1/2 months after submitting the order!!! I told the seller and reimbursed him the payment he'd refunded. At a mere 99 pence, it was well worth such a tiny cost to salve my conscience with such 'honesty' in this case. :)

 Although it seems highly improbable that the FY6600-60M I'd ordered around the same time will ever turn up, I'm not so sure I'll be quite so honest when it comes to a matter of £40.41 on an untracked parcel. >:D [END_EDIT]

 Both purchase attempts had become disappointing failures but at least I got my money back.  :)  :( :-\  I'm now looking to Banggood as my main supplier now, ever since having had my attention drawn to the absolutely fabulous KSGER T12 oled soldering station they sell which is designed to drive the Hakko T12/T15 70 watt rated direct drive (with thermocouple) soldering iron tips far far more accurately than the original Hakko soldering stations ever could.

 However, as is usual with Chinese made mains powered kit, the 24v smpsu has potentially lethal issues requiring some gross mechanical remedial work on the diode heatsink (which bridges the nice isolation slots milled into the PCB) to improve on the use of solder resist mask as the sole method of insulation against a 170 to 340 vdc carrying circuit trace. :wtf: Not a serious problem for anyone who understands this lackadaisical attitude to mains voltage safety by the Chinese and regards such safety checking and basic remedial work as SOP with such Chinese product. >:D

 This is one soldering station I can't recommend as a first soldering iron for a newbie to purchase even though it's an excellent choice for the seasoned hobbyist upgrading from years of frustration with classic mains powered soldering irons such as the Antex 15, 18 and 25 watt models (or worse[1]) whom one can reasonably assume would know how to recognise Chinese death traps when they see them and, importantly, know just how to remove them. >:D

 It was Banggood simply because they were the only seller who were offering the right combination of soldering iron handle (the under-rated, even unjustly disparaged, T12-9501) and a T12-K 'starter tip' to go with the oled mains powered and extruded aluminium cased station[2] at a sensible price (Ebay sellers were only offering rubbish combos at inflated prices and my recent "Ebay Experience" had rather put me off dealing with any more Ebay sellers anyway).

 The soldering station had cost me just £39.05 but by the time I'd added a soldering iron stand, a wire wool tip cleaner, a set of assorted T12 tips and a Daniu FG-100 calibration thermometer, the whole order just topped the 76 quid mark. The order arrived on my doorstep just 8 days later from their Chinese warehouse (cheapest price option) and I have to say that it was money well spent, in spite of having to fettle not only the soldering station controller box itself but also that of the wiring in the 9501 handle :)

[EDIT 20191017-2]
 That 8 days delivery was either a lucky fluke or else the result of special 'Grooming' treatment to lull 1st time buyers into a false sense of optimism. Delivery times for BG typically range from a fortnight (if you're very lucky) through to 6 weeks or more (via express air delivery (in a cargo glider towed from the stern rail of a container ship???)). [END_EDIT]

 For anyone here who has ever hankered after an original Hakko T12/T15 soldering station but couldn't justify blowing some 250 to 300 dollars (nor even the 150 dollars of a 'cheap clone'), these KSGER units (all faults aside) represent a superior alternative at just a fraction the cost (around the 40 quid/60 dollar mark). I'd recommend a look at the recent youtube review and teardown videos that have been made over the past year on the KSGER T12 soldering station models if this has re-awakened anyone's interest in upgrading from a classic soldering iron setup.

[1] Worse in this case being those Weller soldering station units with a totally unprotected mains transformer inside - no user serviceable fuse of any sort, not even a thermal fuse embedded within the windings!  :wtf: As dangerous as the KSGER unit had been (mine is perfectly safe now!), that has not only one but two fuses!  >:D

[2] KSGER have made a bewildering array of variants of their T12 soldering station including ones with just a three digit seven segment display both in external psu/battery pack powered 'mini' versions along with different hardware/firmware versions of same, hence the distinction I made.

 Also, these can be bought in the form of self build kits at varying levels of complexity falling just short of requiring the DIY enthusiast to populate the controller board with smd parts and solder them up - they, afaik, are always supplied as a completed module ready to be wired up to the PSU and  five pin din soldering iron handle socket on the front panel. Incidentally, the version 3 firmware/hardware seems to be the hallmark of these kit versions rather than a later upgrade. The latest versions for the ready built units is currently at HW ver 2.1S and SW ver 2.10 as of this posting.

 Surprisingly, most of these kits are often sold at a higher price than the ready built units  :-// Even when they happen to be a little cheaper than a ready built unit, the tiny cost saving just isn't worth the hassle. You'll have enough DIY reassembly work making the PSU safe and rectifying the shoddy workmanship in the handle and plug with a ready built unit in any case but once you've put in that work, you'll have a soldering station to be proud of. >:D

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 30, 2019, 11:11:29 pm
I did wait with opening until I got a reply via the mail.
They asked me to look inside and indeed it was a loose connector.
The connector between mainboard and power supply.

I also looked at the 'ground cable' and apart from the mentioned lack of insulation level, it is also dangling on a single thread of the internal strings.
So that's going to be replaced like in the video and I will also add some shrink tube on the other mains joints just to be sure.

This ground wire is really a safety issue, since it can come loose quite ease during transport and touch one of the mains points.

The manufacturer also wrote this about the power supply:
Quote
Our power supply is + & - 13.5V and 5V, the current is 200mA.
I assume it is for all voltages.

 It did sound like a loose psu connector. I'm glad you were able to fix it at the behest of Feeltech support (presumably, no warranty voiding issues in this case).

 As far as the earth wire goes, that had been stolen out of the psu to main board ribbon cable by Feeltech's kludgery in the first place. If it were me, I'd be be reinstating it and looking to solder a 4K7R onto a convenient ground point on the main board and wiring the other end to the PE contact in the C14 socket in place of the bodged earth connection. This will drop the 90vac earth leakage on a 230v supply down to 250mV ac and attenuate the effect of the mains earth loop by some 40 to 50dB as well as suppress the HF switching noise that Feeltech's bodge had introduced onto the mains earth.

 The PSU is still a Class II smpsu which doesn't actually require such a safety earth connection anyway. However, unless Feeltech's customer support agree to such modification work being done, you might want to hold off to avoid immediately voiding your warranty with them in case it stops functioning due to a manufacturing defect outside of all the defects it already has. Give it time to  get beyond the "Infant Mortality" phase of the reliability curve before doing anything that will void the warranty (for what such Chinese Warranties are worth).

 Regarding that statement (from Feeltech themselves?) that the plus and minus twelve volt rails are now actually +/-13.5 volt rails, that rather suggests they've modified the transformer, possibly by reducing the turns count on the five volt secondary winding by one turn, to raise the 12 volt rails by another volt, neglecting to alter the silk screen printing by the connector to reflect this change. The extra volt or so would just about suffice to allow the THS3002i opamp to output a 24Vpp signal. It would neatly explain how they've managed to get an opamp with at least a 1.2v headroom specification to output a full 24Vpp out of a "+/-12 volt" supply.

 The original, unmodified psu in the FY6600 (and almost certainly that of the FY6800) were only managing 11.5 to 11.7 volts on the +/-12v rails. A common psu mod was to replace the cheap diodes on the 12v rails with proper high speed switching, low forward volt drop Shottky types and bump the 5v up by 5 to 10 percent for good measure  to raise the 11.5v to something like 12.7 volts (makes the LDO's on the main board run a little hotter though). In this case, it looks like Feeltech have done most, if not all of the work already.

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TD-er on August 31, 2019, 08:10:38 am
Well, I did already replace the ground wire, since I'm not letting a flatcable wire hang on 1 thread of copper (??) next to mains power solder joints.
Warranty is maybe worth something, but not that much.
Also added shrink tube around the mains solder joints, just to be sure.

I did test the unit a bit last night and it does seem to work fine.
There is however a strange signal added to the output wave form, which can be seen best at the "DC waveform".
It does seem to be at the begin/end of the memory-cycle of the wave form.

Also there is quite a distinct noise pattern on top of the wave form, which does seem to come from the power supply itself.
Maybe later I will make a board using a traditional transformer and just the old fashioned diode bridge, capacitor and 78xx and 79xx.
Just like I did when I was 13 (30 years ago...)
Or could I add a 3D-printed cap over the power supply to support some aluminium foil to isolate the power supply (or the main board) ?
The noise is just strong enough to let my scope's edge trigger to swap the wave form every now and then (at 1V pp output)

Just have to clean up the desk a bit and attach ethernet to the scope to get some screen grabs.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on August 31, 2019, 08:25:39 am
I have received my FY6900 but am unable to get the supplied software to work.  I installed the software on a Win7 machine and it opens OK but does not seem to connect the the FY6900.  I am also looking for instructions on how to use the software and specifically how to create custom arbitrary waveforms.  Of course connecting to the FY6900 is the most important thing.

Dear Customer,
Can you connect to the software now? If it is still not possible, please check if the CH340 driver installation is normal.

Best regards,
FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 31, 2019, 02:24:55 pm
Well, I did already replace the ground wire, since I'm not letting a flatcable wire hang on 1 thread of copper (??) next to mains power solder joints.
Warranty is maybe worth something, but not that much.
Also added shrink tube around the mains solder joints, just to be sure.

 I know exactly where you're coming from - "Discretion (in this case) being the better part of valour." and all that.  ;)
 

I did test the unit a bit last night and it does seem to work fine.
There is however a strange signal added to the output wave form, which can be seen best at the "DC waveform".
It does seem to be at the begin/end of the memory-cycle of the wave form.


 A good candidate for which seems, imo, to be the result of the earth loop introduced by that direct connection to the protective earth.


Also there is quite a distinct noise pattern on top of the wave form, which does seem to come from the power supply itself.

 The high voltage switching noise in such smpsu boards can be very hard to keep out of the rest of the circuit boards being powered.
 

Maybe later I will make a board using a traditional transformer and just the old fashioned diode bridge, capacitor and 78xx and 79xx.
Just like I did when I was 13 (30 years ago...)


 You and me both. ;) Mind you, I was never a great fan of this idea once I started building my own IBM desktop PCs in the mid 80s and could handle the very lightweight 200W PSU boxes with an ease impossible with an Old Skool analogue unit weighing some 15 Kg or more (mostly due to the required 300VA mains transformer).
 

Or could I add a 3D-printed cap over the power supply to support some aluminium foil to isolate the power supply (or the main board) ?
The noise is just strong enough to let my scope's edge trigger to swap the wave form every now and then (at 1V pp output)

 At best, that would only screen against the electric field component. It wouldn't do much, if anything at all, for the magnetic field component which will couple interference currents into any wiring or circuit traces. Containing such electromagnetic energy within the confines of a shielding box around such smpsu boards is a lot harder than it looks.  :(
 

Just have to clean up the desk a bit and attach ethernet to the scope to get some screen grabs.

 Those will be interesting to see and a handy "Before" reference for when you grab another bunch of "After" screen shots after trying out my suggestion of inserting a "Drain Resistor" between the main board ground rail and the PE connection in the C14 mains socket. >:D

 Regarding the "Analogue" psu idea, the major downside is the need to warm up all those 78/79 regulators and deal with the extra heat load in the box. If you use a good quality "R" transformer to all but eliminate the significant contribution you'd otherwise see with a cheap 'n' cheerful Chinese transformer, you're left with (essentially) just the rectifier losses and the regulator losses. The rectifier losses are trivial in this case (an amp's worth accounting for around 1.5W in a bridge rectifier at 50/60Hz).

 It's all those pesky 78/79 regulators that are the main problem in this case. However, thanks to the wonder of modern switching converter technology, these can be replaced with DC-DC converter based drop-in replacements which typically offer conversion efficiencies ranging from a (very) low 70% to a more reasonable 90 to 95 percent, even as high as 97 to 98 percent with the very best DC-DC converter modules.

 You still have some reduced level of switching noise to deal with (typically 30mV ripple at a fixed 1.2MHz on a 5vdc output dc-dc converter module) but almost totally absent the troublesome common mode switching noise of the classic mains voltage smpsu.

 Ripple on the supply rail at a fixed 1.2MHz (or even higher frequency) is a lot easier to filter out, especially when you don't have any significant levels of common mode noise to deal with as well. That's the theory at any rate but substituting all the Old Skool 78/79 regulators with dc-dc converter modules looks a very promising way to go (almost all of the benefits of an analogue PSU but without the worst excesses of waste heat such supply technology is infamous for).

 I've got a couple of these mini dc-dc converter modules on a ten quid Banggod order that's due to finally arrive in just over a week's time (it didn't qualify for the more expedited £76- order I'd put in for the KSGER T12 soldering station and friends which arrived just over a fortnight ago).

 I'm planning on using the 5v only output one (with a <30mV ripple specification) in my basic GPSDO that I'm currently very slowly assembling into a neat little aluminium extruded enclosure. I have high hopes that this will not only avoid the need to clamp the heatsink tab of a 7805 regulator to said enclosure but also allow me to power it off not just 9v wallwarts but also 6 to 24 volt wallwarts with complete impunity.

 Also, of course, I will be testing out how easy (or hard) it will be to attenuate the residual <30mV ripple to a vanishingly small <10mV or even lower with simple LPF filtering using tiny Ls and Cs (and some Rs - unwanted energy has to go somewhere - better it's dissipated by a resistor in the filter itself in a conversion to low temperature, thermal energy rather than escape "into the wild" unaltered  :-DD). I rather think this will be the optimum solution to a source of "clean" (if not green) energy to power all these FY66/68/6900 signal generators .  ;)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TD-er on August 31, 2019, 08:45:15 pm
Not entirely sure yet what may make the difference here.
Last night I tested with the included cables and had not connected the FY6900 to the computer via USB.

Now I did use some proper (well, less flimsy/cheap) coax cables and the FY6900 is connected via USB.
The noise does seem a lot less apparent.
For the screenshots I did enable "persistent colors" to color the noise.

Please note that I could not set the probe as being 1x, so you have to divide the voltages yourself by 10.   (edit: I did need to have a better look, the 1x was off screen and I just had to take a better look and some coffee)
The screenshots are with 1 MHz frequency set on the FY6900 and 0.5V Ampl.
There is no offset or phase set. The pattern for the square wave apparently does not start at the same position as the sine.
At 1 MHz the phase shift is 9 degree (18 degree at 2 MHz, 27 deg at 3 MHz), so there is some strange (fixed delay) offset.

I also added a screengrab of the strange spikes when showing "DC waveform"
This does look like some 50'ish kHz signal, so it may very well be from the power supply.


By the way, I also used the FY6900 PC Software.
Apart from the most horrible GUI design ever and really bad choice of fonts, is it quite useful.
See the screenshots and a hand drawn waveform.

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on September 01, 2019, 12:59:46 am
Not entirely sure yet what may make the difference here.
Last night I tested with the included cables and had not connected the FY6900 to the computer via USB.

Now I did use some proper (well, less flimsy/cheap) coax cables and the FY6900 is connected via USB.
The noise does seem a lot less apparent.

BNC connectors can be notoriously unreliable with regard to their ground contact resistance. The amount of common mode interference being injected into the signal generator's ground which appears on the centre pin connection can vary dramatically as you manipulate the poorer quality connectors.

 The usb ground connection, whilst still relying on an earth loop between the PC and the 'scope, may well be providing a more consistent, if still a little polluted with ground loop induced noise, connection of lower impedance to shunt the bnc ground return impedance which may be helping to reduce the noise in this case.
 

For the screenshots I did enable "persistent colors" to color the noise.

Please note that I could not set the probe as being 1x, so you have to divide the voltages yourself by 10.   (edit: I did need to have a better look, the 1x was off screen and I just had to take a better look and some coffee)
The screenshots are with 1 MHz frequency set on the FY6900 and 0.5V Ampl.


 A 0.5V amplitude setting isn't the best choice with this signal generator since I'm pretty certain this is the threshold voltage level where the attenuator is switched in. In the 66 and 68 models, this is an 86 ohm rather than the 50 ohm impedance attenuator it's supposed to be. Whether this same Skoolboy Howler has been perpetrated in the 69 model, no one has as yet completed the test to determine this.

 If you're testing without the 50 ohm cable terminating resistor (which, from your description appears to be the case), it won't make much difference with a short half metre cable at 1MHz since Feeltech's "fix" was simply to compensate for this in the firmware (but only for the Hi Z case - it can't possibly compensate the error in both cases).

 You need to select an amplitude greater than 0.5V if you wish to avoid having this questionable attenuator switched into circuit -  the 5.01V setting is sufficient to ensure this happy state.

[EDIT 20200815]

 I meant to write 501mV or 0.501v, not 5.01v which invokes the THS opamps for frequencies no greater than 20MHz

 Also, I attributed a cleverness to FeelTech in modifying the firmware to compensate for the "cheap" mismatched attenuator under Hi-Z loadings - there was never any such cleverness other than to create a "20dB drop" for the Hi-Z case only using the cheapest possible resistor combination to satisfy the insane insistence by their Bean counter in chief to "Cut costs at any price, even if this results in a big FU to the more serious users expecting to see a consistent 50 ohm output impedance at all voltage output levels.

 The fix for this issue is to simply replace those resistors with a set calculated for a 20dB at 50 ohm impedance attenuator network - no second guessing required :phew:

 

There is no offset or phase set. The pattern for the square wave apparently does not start at the same position as the sine.
At 1 MHz the phase shift is 9 degree (18 degree at 2 MHz, 27 deg at 3 MHz), so there is some strange (fixed delay) offset.

I also added a screengrab of the strange spikes when showing "DC waveform"
This does look like some 50'ish kHz signal, so it may very well be from the power supply.

  Such switching spikes are difficult to observe on a 'scope on account of the drifting frequency due to variations in the load on such smpsus. You normally need to capture it in a single manually triggered sweep (a feature at which modern DSOs excel). If you're examining such artefacts on a DC output rail, this is also where the 'scope's AC coupling feature comes to the fore.


By the way, I also used the FY6900 PC Software.
Apart from the most horrible GUI design ever and really bad choice of fonts, is it quite useful.
See the screenshots and a hand drawn waveform.

 I haven't got my 'scope set up on the bench due to lack of working space at the moment otherwise I'd have tried the same tests to compare. However, istr seeing similar levels of smpsu switching interference at sub 1 volt settings some time back so I think what you're seeing is typical of Feeltech's "Finest".  ::)

 As for the freehand waveforms, I've never tried using the included software in the past nine months since I purchased mine from a UK based seller last November. I haven't bothered largely because it can be a bit of a faff setting up the USB pass-through on my winXP VM for something that's been a low priority so far.

 As well as some unfinished business with that 86 ohm attenuator (now a 45 ohm one since my last attempt to put it right) I've still got one remaining feature to add to my 6600 before I'm ready to experiment with the software and the usb interface (I'm going to add a socket for an external 10MHz reference to be supplied by an as yet unbuilt GPSDO).

 Also, I may replace the existing PSU board with an "Analogue PSU" based on dc-dc converters in place of the classic 78/79 regulator ICs to hopefully eliminate that troublesome common mode switching noise injected by the high voltage switching transients on the primary of the transformer into the low voltage secondary windings.

 The residual ripple on the dc-dc converter modules' outputs should be a lot easier to suppress with a bunch of small LPFs than the inescapable high voltage transients inside of a typical smpsu which not only conduct common mode interference into the main board via the wired connections but also directly irradiate it  as well.  >:(

 However, all that is for a future project. I really, really should have bought those cheap 6v carbon zinc lantern batteries that I spotted in Wilkinsons for just a couple of quid each yesterday to make up the negative 12v rail to complement the 12AH SLA I'll be using to power the positive 12v rail and a 7805 regulator by which to test the generator sans that pesky smpsu board before I start ordering parts for my analogue/switching chimera of a power supply. It's something I've had a mind to do for at least the past six months but, like many things I have plans for, it's been on a rather crowded 'back burner' since like almost  'forever'. :-[

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: excitedbox on September 01, 2019, 04:37:14 pm
Mine is sitting at customs in Frankfurt right now (since the 27th) waiting to be released. It spend 10 days sitting at the Airport in China waiting on it´s flight. But with any luck it will be here on Monday.

I hate always having to wait so long for shipping. I get so impatient  |O :scared:

 I presume that you meant the 27th of this month. That's hardly any delay at all!  :-DD  How about a 99p tracked order for ten 74hc14s that's been sitting in Hong Kong customs since the 1st of June (just two days after being shipped out of China by the seller) and is, afaik but no longer care about, still stuck in that black hole. ::)

 I'd finally had enough of all the waiting so got Ebay to 'resolve the issue' and the seller has reimbursed my 99 pence. I'd ordered half a dozen of these ICs from a UK based Chinaman at the exorbitant price of almost three quid about three weeks ago and they'd arrived just 8 or 9 days later.

JBG

Yes I am still waiting on a 4 Euro order from the beginning of June. Just a couple of i2c and spi expanders and an h11 load cell pcb. and it stopped updating tracking after reaching the shipping center in china.

I don´t recommend using Banggood after all the problems I have had with them. Only good thing is that if you complain they refund the money and let you keep the item in most cases. I got a Aneng Q1 multimeter with a cracked screen for free that way (27 Euros saved). But A usb microscope I paid 29 Euros for was a really cheap model with the wrong specs in the description. I ended up not complaining because at some point the time spent is worth more than the refund.

Banggood also has listings for colorful plant seeds (neon blue strawberries etc.) that are obviously fake and photo shopped and even after being reported they don´t remove them.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TD-er on September 01, 2019, 06:01:30 pm
[...]
 A 0.5V amplitude setting isn't the best choice with this signal generator since I'm pretty certain this is the threshold voltage level where the attenuator is switched in. In the 66 and 68 models, this is an 86 ohm rather than the 50 ohm impedance attenuator it's supposed to be. Whether this same Skoolboy Howler has been perpetrated in the 69 model, no one has as yet completed the test to determine this.
I did set it to a low value on purpose to see if the board could pick up the noise I saw before.

When switching from 0.5V to a higher amplitude, you hear a relais clicking, so it is very well possible an extra attenuator is switched in/on.
Noise levels are not better noticable when set at an amplitude of 1V.
Quote
If you're testing without the 50 ohm cable terminating resistor (which, from your description appears to be the case), it won't make much difference with a short half metre cable at 1MHz since Feeltech's "fix" was simply to compensate for this in the firmware (but only for the Hi Z case - it can't possibly compensate the error in both cases).
The first test I did was both with the included BNC-BNC cable and with the included BNC->crocodile to my normal probe.
Both showed significant noise.

Quote
You need to select an amplitude greater than 0.5V if you wish to avoid having this questionable attenuator switched into circuit -  the 5.01V setting is sufficient to ensure this happy state.
I can test again with higher voltages.

Quote


There is no offset or phase set. The pattern for the square wave apparently does not start at the same position as the sine.
At 1 MHz the phase shift is 9 degree (18 degree at 2 MHz, 27 deg at 3 MHz), so there is some strange (fixed delay) offset.

I also added a screengrab of the strange spikes when showing "DC waveform"
This does look like some 50'ish kHz signal, so it may very well be from the power supply.
Such switching spikes are difficult to observe on a 'scope on account of the drifting frequency due to variations in the load on such smpsus. You normally need to capture it in a single manually triggered sweep (a feature at which modern DSOs excel). If you're examining such artefacts on a DC output rail, this is also where the 'scope's AC coupling feature comes to the fore.
Will do, grab a single run.


Quote
As for the freehand waveforms, I've never tried using the included software in the past nine months since I purchased mine from a UK based seller last November. I haven't bothered largely because it can be a bit of a faff setting up the USB pass-through on my winXP VM for something that's been a low priority so far.
I thought that maybe such a user definable pattern can be useful in making some error state reproducible.
You can define up-to 32 of those patterns (8k per pattern)
So for that it is quite useful to have the software.
Only nasty thing is, as long as the USB cable is plugged in, my ESP flash tool keeps trying to flash to that port (and fails). So I have to remove the cable when flashing to ESP nodes.

Quote
Also, I may replace the existing PSU board with an "Analogue PSU" based on dc-dc converters in place of the classic 78/79 regulator ICs to hopefully eliminate that troublesome common mode switching noise injected by the high voltage switching transients on the primary of the transformer into the low voltage secondary windings.

 The residual ripple on the dc-dc converter modules' outputs should be a lot easier to suppress with a bunch of small LPFs than the inescapable high voltage transients inside of a typical smpsu which not only conduct common mode interference into the main board via the wired connections but also directly irradiate it  as well.  >:(
The reason I mentioned those linear ones was because of the effect of a switching DC/DC converter which I thought of replacing.
But I guess the spikes from a switching power supply from mains to DC may be more present indeed than those generated on little DC/DC units.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Andreas on September 01, 2019, 07:13:04 pm
Here's my quick overview. Let me know if anyone needs anything specific covering in more detail

For me it would be interesting if 2 annoying "features" regarding AM-Modulation from FY6800 are still there on the FY6900.

- When AM-Modulation is switched on and the carrier frequency (main channel) is changed by USB-Interface (with delivered software or by terminal program) then on the FY6800 the AM modulation is switched off on each frequency step.

- AM modulation % is done wrongly on the FY6800:
  For 80% AM I would expect 20% minimum amplitude and 180% maximum amplitude compared to AM switched off = 100% amplitude.
  The FY6800 outputs 100% and 20% amplitude when 80% AM is dialed which is in fact only 66% AM =(100%-20%)/(100%+20%)
  instead of (180%-20%)/(180% + 20%) = 80%

see also here:
https://www.eevblog.com/forum/testgear/fy6800-dds-signal-generator-questions/msg2502990/#msg2502990 (https://www.eevblog.com/forum/testgear/fy6800-dds-signal-generator-questions/msg2502990/#msg2502990)

with best regards

Andreas
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: bdunham7 on September 01, 2019, 08:35:59 pm
Here's my quick overview. Let me know if anyone needs anything specific covering in more detail

For me it would be interesting if 2 annoying "features" regarding AM-Modulation from FY6800 are still there on the FY6900.

- When AM-Modulation is switched on and the carrier frequency (main channel) is changed by USB-Interface (with delivered software or by terminal program) then on the FY6800 the AM modulation is switched off on each frequency step.

- AM modulation % is done wrongly on the FY6800:
  For 80% AM I would expect 20% minimum amplitude and 180% maximum amplitude compared to AM switched off = 100% amplitude.
  The FY6800 outputs 100% and 20% amplitude when 80% AM is dialed which is in fact only 66% AM =(100%-20%)/(100%+20%)
  instead of (180%-20%)/(180% + 20%) = 80%

see also here:
https://www.eevblog.com/forum/testgear/fy6800-dds-signal-generator-questions/msg2502990/#msg2502990 (https://www.eevblog.com/forum/testgear/fy6800-dds-signal-generator-questions/msg2502990/#msg2502990)

with best regards

Andreas

I didn't check the first issue, but I can verify that the second is unchanged.  Modulation leaves the high level unchanged and the lower level is (100% - mod%).  Easy enough to understand, but not in accordance with convention. 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on October 11, 2019, 01:55:22 pm
I just got my fy6900 in the mail. After skimming forum posts on previous fy6600 and fy6800 models, am I right to assume they use a 50 MHz clock for their FPGA? This one uses a 10 MHz oscillator, which would make a tcxo/ocxo upgrade or external reference input much easier to add!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on October 12, 2019, 11:07:50 pm
I just got my fy6900 in the mail. After skimming forum posts on previous fy6600 and fy6800 models, am I right to assume they use a 50 MHz clock for their FPGA? This one uses a 10 MHz oscillator, which would make a tcxo/ocxo upgrade or external reference input much easier to add!

 That's an interesting twist to the tale. ::)

 I wonder if they're using an NB3N502 14MHz to 190MHz PLL Clock Multiplier chip with a 10MHz xtal resonator or another cheap smd XO chip? The 3N502 can be driven from an external clock source ranging from as low as 2MHz to as high as 50MHz or else generate its own clock with XTAL resonators from 5 to 27MHz which in both cases can be multiplied up by factors of 2, 2.5, 3, 3.333, 4 and 5 to provide an ultra low jitter clock output so it's certainly a contender as a 50MHz clock source which I believe is a fairly common FPGA clock frequency.

 However they've made the change from a 50MHz smd XO clock to a 10MHz XO, it should simplify an OCXO or TCXO upgrade. No need to add a 3N502 in place of the shitty little 50MHz smd XO chip as we've had to do with the preceding models in this case. ;)

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on October 13, 2019, 12:26:07 pm
It looked like a regular smd XO, with 10 MHz going straight into the fpga, but I could be mistaken. I only opened it up to have a quick glance at the internals before daring to plug it in. This turned out to be a good idea, because the cover screw had inconveniently drilled itself straight through the SMPS ribbon cable, pretty much shorting together the +-13.5v rails!

Other things I noticed were the NEC relays, with date codes ranging from 1997-2004. Three of the four had what looked like some kind of conformal coating on them, so I suspect these werent even NOS relays :D

Regardless, still a bargain, but quite hilarious. I'll have a closer look at the main board next time I have it open... when I replace the power supply.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on October 14, 2019, 06:18:10 pm
It looked like a regular smd XO, with 10 MHz going straight into the fpga, but I could be mistaken. I only opened it up to have a quick glance at the internals before daring to plug it in. This turned out to be a good idea, because the cover screw had inconveniently drilled itself straight through the SMPS ribbon cable, pretty much shorting together the +-13.5v rails!

Other things I noticed were the NEC relays, with date codes ranging from 1997-2004. Three of the four had what looked like some kind of conformal coating on them, so I suspect these werent even NOS relays :D

Regardless, still a bargain, but quite hilarious. I'll have a closer look at the main board next time I have it open... when I replace the power supply.

 Just when you thought they couldn't get any cheaper! Their buyer (buying department) must be expert(s) at sniffing out bargains in the component supply chain. Perhaps they'd located a dirt cheap source of 10MHz XO and clock multiplier chips (not necessarily those NB3N502 ICs I mentioned) or perhaps an FPGA version that can be clocked with 10MHz rather than the more typical 50MHz - who knows how the inscrutable Chinese mind works?. :-\

 Incidentally, are those +/-13.5v rails marked as such, or was it just what voltages you were seeing whilst the unit was delivering 20Vpp into 50 ohm dummy loads? Also, did you take the opportunity to repair the vandalism Feeltech had perpetrated in stealing one of the two ground return wires out of the ribbon cable in order to provide a hard connection to the PE terminal on that BFO C14 mains connector?

 This latter act of vandalism really ought to be remedied, preferably by tripling up the one remaining ground return wire and patching out the missing wire similarly and, for good measure, remove the resulting ground loop issue by inserting a 3K3R or 10KR in series with the PE connection. The class II smpsu board used doesn't actually require a hard protective earth connection and even a 10KR "static drain" resistor is sufficient to knock the 90vac half mains live voltage ESD hazard of a 240v mains supply down to just half a volt ac or less.

 At least one member who'd bought an FY6800 was saved the trouble and embarrassment of returning it with a "DC Offset fault" after heeding advice to break the earth loop (in his case, he'd chosen to disconnect the 'scope ground) and retest. The FY6600 hadn't suffered this ground loop issue but the half mains live 'touch voltage' presented an ESD hazard if you forgot to connect the BNC ground before connecting to the test point of your DUT (and disconnected it after disconnecting from the test point).

 It turned out that the solution was simply to upgrade the 2 pole C8 connector to a 3 pole C6 or C14 connector to wire the PE to the main board ground via a 10KR 'drain resistor' to suppress this half mains live 'touch voltage' and neatly sidestep this ground loop issue.

 It's quite clear that Feeltech's decision to upgrade from the C8 to a C14 mains connector on the FY6800 model must have been a response to all the moaning about the ESD hazard in the FY6600 EEVBlog thread. Unfortunately, they chose to do the absolute minimum possible to implement a solution to address this complaint about the presence of this ESD hazard by totally ignoring all and every "unintended consequence" of hard earthing the BNC ground points and reduction of ground return wires in the smpsu board to main board ribbon cable connector from a barely adequate count of two to a woefully inadequate count of one.

 That ribbon connector could have done with an upgrade from a 6 pole single row to a 12 pole dual row connector to add another 6 ground wires to the circuit to reduce PSU noise and ripple getting onto the main board supply rails. Reducing the ground return wire count would have been the last thing any sane manufacturer would have even considered, let alone implement. :palm:

 Feeltech (FeelElec) aren't the only Chinese manufacturer of bargain priced test, measurement and electronic tools who show such blatant disregard for any modicum of quality in their products. KSGER who make all those otherwise excellent T12/T15 tip based soldering stations are just as bad (and even worse if you rate the electrocution risk higher than the ESD risk).

 I bought one of these cheap alternatives to Hakko's rather flawed FX-951 soldering station two months ago and, as with the FY6600, it rather benefited from some basic fettling and general remedial work. It is now as safe as any normal electrical appliance made by The West (excepting for some models of Weller soldering stations  ::)) can be expected to be and no longer at risk of its controller succumbing to soldering iron handle wiring faults, typical of "Chinese Quality Control".

 It's considered SOP to take such mains powered Chinese Marvels of Technology apart as you did, in order to check for and (almost inevitably) make safe for "Human Consumption" and 'fitter for purpose'. :)

 I was only expressing an idle curiosity in the matter seeing as how Feeltech appear to have been taking note of the various moans and groans and modifications that had been discussed in the earlier FY6600 thread (a "Standing on the shoulders of giants" effect) where the use of the 3N502 had been suggested by one of the members to Arthur Dent who had been proposing to fit a 10MHz OCXO to his FY6600 at the time (and has long since done so) and from which I eventually[1] took inspiration to do likewise after having already replaced the shitty little 50MHz smd XO chip with a 50MHz 0.1ppm rated TCXO driver board I'd mounted well clear of the 50 deg C environment of the original on-board XO chip.

 Having employed the 3N502 to allow me the use of a CQE branded 12v 10MHz OCXO in my own FY6600 project and using another one in my current DIY GPSDO project to make use of a 5v 13MHz CQE branded OCXO (74HC86 clock doubler to 26MHz into a 74193 (original old skool TTL!) divide by 13 to drive the 3N502 with the lowest allowable 2MHz input frequency clock) to generate an ultra low jitter 10Mz square wave, that 3N502 was rather on my mind when I saw your post. :)

 As I've already admitted, it was just idle curiosity on my part so there's no hurry in answering that question. That's not to say I wouldn't be interested in what you do eventually discover as I'm sure others would likewise be interested in what you may care to divulge about Feeltech's (FeelElec) latest and greatest toy signal generator.

[1] I rather naively thought at the time, that this OCXO mod was just a tad OTT but eventually realised the value of such accuracy and stability once I discovered that I was never likely to improve on the +/-30ppb I was getting out of the 50MHz TCXO board. As good an improvement as it was over the original smd XO chip's best +/-20ppm effort at (in)stability, I had developed a new found desire for sub ppb accuracy which nothing less than an OCXO could satisfy. ::)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: wadim207 on October 17, 2019, 11:30:29 am
When testing the functions of the generator FY6900, it was found impossible to connect to the computer. When connected to different computers, the device is not detected by windows 7, new devices do not appear in the device lists. When you connect another device with USB-SERIAL CH340 on these computers, it is recognized and connected. Installing the ch340/CH341 driver of different versions did not help. Help solve the problem or fix it.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on October 19, 2019, 08:47:43 am
When testing the functions of the generator FY6900, it was found impossible to connect to the computer. When connected to different computers, the device is not detected by windows 7, new devices do not appear in the device lists. When you connect another device with USB-SERIAL CH340 on these computers, it is recognized and connected. Installing the ch340/CH341 driver of different versions did not help. Help solve the problem or fix it.

Dear Customer,
Our technicians are helping you solve the problem on AliExpress.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: ToKreTu on October 25, 2019, 10:41:07 am
Hello I’m new in this forum as a contributor.
I’ve just received my FY6900 and I’m very happy with it so far - everything is working as expected.  After thorough investigations on the internet I came to the conclusion that at the moment there is no better signal generator on the market for that price.

@feelelec
Only one point is confusing me and I need clarification.  It’s about the input signal level for the Counter.  There are three different instructions concerning the Counter Input: 

1.   When entering the counter menu by pressing the COUNTER button the Display shows the Message “Warning: Maximum Safe Input Voltage: 5V AC+DC” (picture 1). What does that mean and what does “Safe Input” exactly mean? Does it mean that the device can get damaged when the Input Voltage is higher? Or does it only mean that the measurement result can get inaccurate?
2.   In the User Guide on page 28, picture 2-1 the max. safe input voltage is given as “20V AC+DC” and in the box at the bottom of this page it is only 5V but now it speaks about Trig. IN instead of Counter IN (picture 2). This is very confusing! Again: What means “safe”?
3.   On the other hand the Technical Specifications in the User Guide allow an “Input Voltage Range” of 1Vpp~20Vpp (page 43, External Measurement; see my picture 3 below).  And that is what I am actually expecting of a frequency counter!

Please confirm my expectation or, if you cannot, please explain why the input voltage for the Counter is limited to only 5V.
One point is for sure: The User Guide and the real device (firmware V1.2) do not correspond.

Thank you, Thomas
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Kleinstein on October 25, 2019, 11:24:40 am
The maximum safe voltage normally is the level one can be sure not to cause a damage. The actual level where damage starts may be considerably higher. Another point is that there may be a higher level for short time.

The different voltage levels are indeed confusing. Part of this could be due to translation.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on October 26, 2019, 02:40:40 am

1.   When entering the counter menu by pressing the COUNTER button the Display shows the Message “Warning: Maximum Safe Input Voltage: 5V AC+DC” (picture 1). What does that mean and what does “Safe Input” exactly mean? Does it mean that the device can get damaged when the Input Voltage is higher? Or does it only mean that the measurement result can get inaccurate?
2.   In the User Guide on page 28, picture 2-1 the max. safe input voltage is given as “20V AC+DC” and in the box at the bottom of this page it is only 5V but now it speaks about Trig. IN instead of Counter IN (picture 2). This is very confusing! Again: What means “safe”?
3.   On the other hand the Technical Specifications in the User Guide allow an “Input Voltage Range” of 1Vpp~20Vpp (page 43, External Measurement; see my picture 3 below).  And that is what I am actually expecting of a frequency counter!


Dear Customer,
Thank you very much for your discovery.
The safe input voltage "20V AC+DC" on the instruction manual is correct.
The display on the machine is wrong and our engineers will amend it.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: WaveyDipole on October 30, 2019, 05:02:10 pm
Is there any difference between the FeelElec and KKmoon branded versions except for the price (KKmoon is around 10GPB cheaper)? They appear to be the same re-branded unit? Quality? Earlier firmware?

Regarding the firmware, can it be upgraded?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on October 31, 2019, 03:25:38 am
Is there any difference between the FeelElec and KKmoon branded versions except for the price (KKmoon is around 10GPB cheaper)? They appear to be the same re-branded unit? Quality? Earlier firmware?

Regarding the firmware, can it be upgraded?

Dear Customer,
KKmoon is our agent, you can purchase from our store or KKmoon store.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: WaveyDipole on November 04, 2019, 06:50:25 pm
My KKmoon branded unit arrived today and seems to be in good working order. I haven't looked inside yet, but there was no appreciable voltage or current on the BNC connectors. A quick test of functions and waveforms shows all is well. I did note in earlier posts th problem regarding the amplitude voltage display and the observation regarding the control knob. My unit does have the amplitude voltage display problem and I agree that the control knob is indeed a little fiddly, but does work and is only to be expected for the price. I will probably replace it tjough. I can't comment on the power supply yet, but this has been well covered already.

I was able to perform a quick test of the software on Windows 7 Pro and I had no problem getting this to work. The CH340 drivers were already installed so I didn’t have to go through that step. I have only looked at it only from a remote control perspective. I also managed to get the software to work in Linux under Wine. A little configuration in Wine was required in order to connect with the serial port, but otherwise the software seemed to connect and work. There was one error during installation (unregistered et40.dll) which I need to investigate further.

The FY6900 software lists 16 ports under 'Port Connect', so a port needed to be selected from this range. However, in Linux a USB serial port is mapped to something like /dev/ttyUSB0. On my machine, Wine, in turn, maps this to com33 by creating a symbolic link in ~/.wine/dosdevices.

In order to get around this, one option is to manually create the symbolic link for the required port. The downside is that Wine automatically refreshes the links back to their default state when an application is launched. This means that the symbolic link had to be created every time and after the FY6900 software was launched, otherwise Wine would just reset it and the software would try to connect to an inactive port. Fortunately there is a better way.

It is possible to override the serial ports mappings that are created automatically by Wine. This is quite simple and can be done simply by a registry entry per port. Full details can be found here:

https://wiki.winehq.org/Wine_User%27s_Guide#Serial_and_Parallel_Ports

This method has the advantage that the chosen port is mapped automatically each time Wine is started and no manual work is required. Since I am using more than one USB serial device, I created three entries to re-map com7, com8, and com9 to /dev/ttyUSB0, /dev/ttyUSB1 and /dev/ttyUSB2. Of course, if you have only one serial device, then it is sufficient to map just the one port, and any port from the FY6900 software list can be chosen. All I need to know is which /dev/ttyUSBx port the FY6900 device is mapped to in Linux and then select the corresponding com port (7-9) in Wine. If the FY6900 remains plugged in to the USB port, then the last used serial port will automatically be used when the software is re-started.

If I can work out the protocols it uses to send commands and data, then it should be possible to create scripts
to set up the FY6900 and run tests, or even write a native Linux program. At some point I will have a proper look at the inside, but from my brief look, the unit does work, is the 60MHz version (PY6900-60M, version 1.3) and seems more than adequate for hobbyist use. I would like to know, incidentally, whether version 1.3 is a current version of the firmware? Does anyone have any information on firmware versions?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on November 06, 2019, 05:04:38 am
If I can work out the protocols it uses to send commands and data, then it should be possible to create scripts
to set up the FY6900 and run tests, or even write a native Linux program. At some point I will have a proper look at the inside, but from my brief look, the unit does work, is the 60MHz version (PY6900-60M, version 1.3) and seems more than adequate for hobbyist use. I would like to know, incidentally, whether version 1.3 is a current version of the firmware? Does anyone have any information on firmware versions?

Dear customer,
Our latest version of the firmware is 1.3.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on November 06, 2019, 03:47:17 pm
Dear FeelElec,

I understand your effort to come closer to the community and that was one the key reasons why I decided to take the risk and to order one. I understand there might be some technical flaws but I assume it's due to imposed restrictions when trying to positioning such a product in the under 100$ price tag.

As a hobbyist, it's hard to find the a use case where I would spend more than that on a signal generator, my purpose is really to learn about electronics and this kind of equipment helps me grasp and visualize some key theoretical concepts.

I find it also quite interesting when the community of REAL electronics engineers or serious hobbyist hack into it and find ways to improve them, this is in fact another way to learn as doing it so, forces you to understand some other concepts of what are you really improving (and eventually a way for you to sell a few more).

So if you allow me to provide some feedback:

1 - Always keep a positive and constructive attitude towards the community, I'm am sure that others like me will use it as an argument to select your brand VS others.

2 - Keep your website neat and up to date regarding your products. I'm sure there are a ton of potential customers that aren't aware of this forum, let alone this topic, so your site is the only window between both. And nowadays there's no reason why you couldn't have a gorgeous website for a very very small amount of money.

Example, you just stated that rev. 1.3 of the firmware was released, how can I update my own ? (it has version 1.2), your website shall have a support area for each one of your products with product documentation, latest firmware updates with respective release notes (doesn't have to be very extensive).

3 - Allow feedback for new features or bugs for coming firmware updates, having the community telling you exactly what they expect from your products, even on this segment, its a very inexpensive and powerful tool (I'm on the product business myself, although in software) and can make your product sales cycle last for years....

Example, I would really like to have a way to send a single pulse while I'm playing with logical circuits.

Thank you,
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: WaveyDipole on November 09, 2019, 08:03:21 pm
Further to being able to run fy6900.exe under wine, it seems that one some Linux/wine installations the application might show the form labels with small squares instead of characters. The main menu and text fields will be OK. It seems the problem may be related to a missing TrueType font called DroidSansFallBack.ttf. The file can be downloaded here:

https://android.googlesource.com/platform/frameworks/base/+/master/data/fonts/DroidSansFallback.ttf

It should be placed in ~/.wine/drive_c/windows/Fonts, or the corresponding path for your wine prefix. It can also be placed in /usr/share/fonts/truetype/Droid. The former is probably preferable, but either seems to work.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on November 13, 2019, 10:02:19 pm
Dear FeelElec,

Mind addressing the firmware upgrade procedure instructions and release notes ?

thank you in advance,
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on November 14, 2019, 09:02:40 am
Example, I would really like to have a way to send a single pulse while I'm playing with logical circuits.

Dear Customer,
Thank you for your suggestions. As for your requirements, the instrument supports the output of single or multiple pulses under the trigger function.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on November 14, 2019, 09:30:19 am
Awesome... I've likely missed something on the manual, need to RFTM once again :)

Could you point me in the right direction for the upgrade procedure ?

Thank you in advance,
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on November 21, 2019, 06:19:53 am
Awesome... I've likely missed something on the manual, need to RFTM once again :)

Could you point me in the right direction for the upgrade procedure ?

Thank you in advance,

Dear Customer,
Is your firmware 1.3 version about this instrument?

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on November 21, 2019, 08:58:47 am
Dear FeeElec,

No, I'm running an older version of the firmware (1.2) ... early adopters tend to suffer with more frequent updates, but I am OK with that.

Do you have the binaries and respective release notes published anywhere?

Thank you,
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on November 21, 2019, 02:21:36 pm
Yes, I too would very much like to know how to install the latest firmware.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on November 23, 2019, 05:32:23 am
Dear FeeElec,

No, I'm running an older version of the firmware (1.2) ... early adopters tend to suffer with more frequent updates, but I am OK with that.

Do you have the binaries and respective release notes published anywhere?

Thank you,

Dear Customer,
We didn't publish the files about upgrade V1.3.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 23, 2019, 12:19:52 pm
Hi , I bought The FY6800 from Banggood .
The signal output on all the wave forms looked like there was an earth quake shimmering and Jitter
The Power supply caps failed after an hour.  even after replacing with low esr it still was unstable and poor quality.
I did send and email with Photo's to your support and never got any reply . Banggood did give me a small refund to cover some cost of repair $10 . I spent over $60 to get working So SO.

I had to completely replace power supply . The Xtal was really bad quality replaced it with new TCXO 50MHz 0.01ppm.  The output ops I had to replaced as the smp had damaged it . +_ 16.73V  = too high for the op amps.
Your spec sheet said the square wave up to 25Mhz  but did not mention that the Jitter over 5MHz was Bad.
The square wave is only stable @ clock multiples . every thing else is touch and Go.
Also the voltage amplitude is not accurate ie 5.000 volt is 5.4* volt 
Also added a laminar air flow for cooling. and cleared the fake air slots so they let air though.
Over all if it was not for this forum it would be only good for a Door stop.
Even after all the repairs It still is no were close to your spec sheet.  :bullshit:

So sorry to say there is no way I would buy the New FY6900 . The Case looks really nice .
But does it have the same Poor SMP!!  and Jitter due to bugs etc.
Or is it just now a nicer Door stopper.

The one thing good about the FY6800 is that it is ease to use..  Just place by open door.  :-DD
How about a Firmware update to solve phase shift on the square wave and others the ramp & stair are horrible
ramp has bad over shoot.

Enlighten me whats under the hood ..  :-DD



Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on November 23, 2019, 05:57:52 pm
I had a FY6600, it stopped working, they never answered me an email, then I bought a FY6900 60Mhz, and I was lucky to be able to sell it, for more money than I paid, and I bought a FY 6900 20 Mhz, I believe which is a signal generator and ideal for a hobbyist like me, who only occupy it 5 or 6 times a month, it is not worth investing in a 60Mhz, for that it would go for a rigol or siglent.

-It is not upgradeable, although it has the button combination for update.
- bad source.
- It has no cooler.
- Altera chip does not have a heatsink.
- scarce vents.
and for other small things, having paid $ 66 with bonuses included from aliexpress seems like enough investment.

in spanish
yo tuve un FY6600, dejo de funcionar, nunca me contestaron un mail, luego compre un FY6900 60Mhz, y yo tuve la suerte de poder venderlo, por mas dinero de lo que lo yo pague, y compre un FY 6900 20 Mhz, yo creo que es un generador de señales y ideal para hobbista como yo, que solo lo ocupo 5 o 6 veces por mes,  no vale la pena invertir en un 60Mhz, para eso iria por un rigol o siglent.

-No es actualizable, a pesar que tiene la combinacion de boton para update.
-mala fuente.
- no posee cooler.
- el chip altera no posee disipador.
- rejas de ventilacion escasas.
y por otras pequeñas cosas, el haber pagado u$s 66 con bonos incluidos de aliexpress me parece suficiente inversion.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: enut11 on November 23, 2019, 10:58:57 pm
Question for @FeelElec
I am looking to buy an FY6900 60M, but only if it has a predictable and stable amplitude setting up to about 20MHz.
Can you publish amplitude vs frequency specs for the 6900? Specifically, I am looking for better than +-0.2dB at 1kHz vs 10MHz and beyond.
enut11
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on November 24, 2019, 11:15:22 am
Dear FeelElec,

Are you stating that I bought a brick ? Is its working fine so far but we're basically in 2020, there's no such thing as "closed" products anymore nowadays.... for sure there will be needed fixes in the coming revisions... for example, whats new in the rev 1.3 ??

How come you don't publish the binaries ?

How can I upgrade my firmware and or fix any bug in the near future ?


Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on November 24, 2019, 01:35:18 pm
Dear FeelElec,

Are you stating that I bought a brick ? Is its working fine so far but we're basically in 2020, there's no such thing as "closed" products anymore nowadays.... for sure there will be needed fixes in the coming revisions... for example, whats new in the rev 1.3 ??

How come you don't publish the binaries ?

How can I upgrade my firmware and or fix any bug in the near future ?

Right friend, if you buy the v1.3 update, it comes with a gift FY6900. :-DD :-DD
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Howardlong on November 25, 2019, 02:16:28 pm
Is its working fine so far but we're basically in 2020, there's no such thing as "closed" products anymore nowadays....

Your evidence for this is what? Maybe your glasses are little too rose tinted!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Old Printer on November 25, 2019, 04:09:50 pm
Is its working fine so far but we're basically in 2020, there's no such thing as "closed" products anymore nowadays....

Your evidence for this is what? Maybe your glasses are little too rose tinted!

Anyone who does not believe that obviously doesn't own any Apple products.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on November 25, 2019, 04:32:43 pm

I didn't meant "close product" in the sense that FeelElec shall provide open interfaces or opensource they software... but why shouldn't I be able to update my product to the latest revision ?

This is a brand new product, knowing from decades of experience that there's no such thing as perfect software (or firmware if you want), why the hell shouldn't they provide their latest versions ?

Event my toy oscilloscope (DSO150) offers firmware updates, is that too much of an ask ?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: dunkemhigh on November 25, 2019, 06:07:34 pm
That's a valid point. With mechanical stuff we can't upgrade (unless we buy a new one) but then we don't need to - the kit usually works as it should because if it doesn't then it's not fit for purpose and we can get our money back. With software, however, it is rare that it is bug-free like hardware is, so it is generally sold incomplete. It's like buying, say, a food mixer with paddles made out of styrofoam. We assume that these bugs will be fixed (because they can be - it is only software) because if they couldn't then we would return it as faulty.

The other point to note is that firmware  updates happen a LOT faster than hardware updates. Why would I buy one this week when I know that next month a newer and far better one will be on the market at the same price (or, as is often the case, cheaper)?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on November 27, 2019, 12:28:27 am

I did send and email with Photo's to your support and never got any reply . Banggood did give me a small refund to cover some cost of repair $10 . I spent over $60 to get working So SO.


Dear Customer,
I'm very sorry perhaps I didn't receive your email. Can you tell me your email address?

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on November 27, 2019, 12:32:54 am
I am looking to buy an FY6900 60M, but only if it has a predictable and stable amplitude setting up to about 20MHz.
Can you publish amplitude vs frequency specs for the 6900? Specifically, I am looking for better than +-0.2dB at 1kHz vs 10MHz and beyond.
enut11

Dear Customer,
Our FY6900 is can be do it. Can you tell me your email? I could send you the user manual by email.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on November 27, 2019, 12:41:03 am
Dear FeelElec,

Are you stating that I bought a brick ? Is its working fine so far but we're basically in 2020, there's no such thing as "closed" products anymore nowadays.... for sure there will be needed fixes in the coming revisions... for example, whats new in the rev 1.3 ??

How come you don't publish the binaries ?

How can I upgrade my firmware and or fix any bug in the near future ?

Dear Customer,
Our latest version is 1.3, and 1.3 supports online upgrade. Now that you have the latest version, you do not need to upgrade. If you want to upgrade version 1.2, we need to mail you the chip. If the latest version is released and needs to be upgraded online, we will send the upgrade package to the customer, and will not release binaries.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on November 27, 2019, 12:42:38 am

I didn't meant "close product" in the sense that FeelElec shall provide open interfaces or opensource they software... but why shouldn't I be able to update my product to the latest revision ?

This is a brand new product, knowing from decades of experience that there's no such thing as perfect software (or firmware if you want), why the hell shouldn't they provide their latest versions ?

Event my toy oscilloscope (DSO150) offers firmware updates, is that too much of an ask ?

Dear Customer,
Our product can be upgrade latest version.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on November 27, 2019, 05:41:55 pm

I didn't meant "close product" in the sense that FeelElec shall provide open interfaces or opensource they software... but why shouldn't I be able to update my product to the latest revision ?

This is a brand new product, knowing from decades of experience that there's no such thing as perfect software (or firmware if you want), why the hell shouldn't they provide their latest versions ?

Event my toy oscilloscope (DSO150) offers firmware updates, is that too much of an ask ?

Dear Customer,
Our product can be upgrade latest version.

FeelElec

Great to hear! Can you please tell us by which process we can update our firmware to the latest version?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: ishergin on November 29, 2019, 06:11:42 pm
Hello!

I've received FY6900 PC Software v 6.5 from my seller. Application offers to update firmware my FY6900 from v1.3 up to v1.4. Could I see changelog?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Clarmrrsn on November 30, 2019, 11:04:04 am
Does anyone know if there are any EU stockists of the FY-6900?

A few ebay listings say they are in London, but I suspect that is a crock.

Looking for my first signal gen and this looks like a good candidate.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Howardlong on November 30, 2019, 11:35:22 am
Does anyone know if there are any EU stockists of the FY-6900?

A few ebay listings say they are in London, but I suspect that is a crock.

Looking for my first signal gen and this looks like a good candidate.

I doubt the product is in London too, however I did two orders for the FY-6900 with seller ”industproduct”, one took 5 days elapsed, the other 7. I’d guess he product is in Hong Kong or China, and they bulk ship a number of products on a single consignment, and redistribute items once in the UK.

The example attached was ordered on 22nd August and arrived on 27th.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Clarmrrsn on November 30, 2019, 01:43:28 pm
Thank you

None in stock from that seller just now, but I suspect this is the same seller, that old trick of more than one ebay account that they all seem to pull.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F123968464157 (https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F123968464157)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on December 03, 2019, 02:20:43 am
Hello!

I've received FY6900 PC Software v 6.5 from my seller. Application offers to update firmware my FY6900 from v1.3 up to v1.4. Could I see changelog?

Dear customer,
At present, the latest version of our device is 1.3, and we do not have 1.4. I've confirmed with our technicians that it's just a tip.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on December 03, 2019, 12:58:53 pm
Hello!

I've received FY6900 PC Software v 6.5 from my seller. Application offers to update firmware my FY6900 from v1.3 up to v1.4. Could I see changelog?

Dear customer,
At present, the latest version of our device is 1.3, and we do not have 1.4. I've confirmed with our technicians that it's just a tip.

FeelElec



Could you please tell us where to download this version 6.5 of the PC software, so we can update our signal generators to the latest firmware? Your website still only offers version 6.3 of the software.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: ishergin on December 03, 2019, 01:06:25 pm
I opened dispute on Aliexpress with problem's desctiption (about invalid amplitude value with 50 Ohm load and jitter), after that seller sent me PC software with firmware. I haven't tried update firmware yet  :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Clarmrrsn on December 06, 2019, 10:27:02 am
Be careful if buying FY6900 on Ebay (As Always)

As I suspected the seller I ordered from as above is full of it, dispatched on monday and tracking still has not updated.  Says "In transit to Yodel". Yet seller insists it is shipped from uk!!!   (Maybe they are walking it from London to Falkirk)

Can get no information from the seller, I would be better speaking to the next door neighbours dog and asking him where my parcel is.

Typical Chinese Ebay seller.

Unfortunately though it looked the best option at the time.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on December 06, 2019, 11:56:35 am
Just ensure you know the revision number before purchasing it, 1.2 and before can't have software upgrades, that "feature" :palm:  was only released in 1.3 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on December 07, 2019, 05:40:20 pm
Just ensure you know the revision number before purchasing it, 1.2 and before can't have software upgrades, that "feature" :palm:  was only released in 1.3

Where did you hear this? If true, that's just really really shitty.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: enut11 on December 08, 2019, 07:15:10 am

"I am looking to buy an FY6900 60M, but only if it has a predictable and stable amplitude up to about 20MHz.
Can you publish amplitude vs frequency specs for the 6900? Specifically, I am looking for better than +-0.2dB at 1kHz vs 10MHz and beyond.
enut11"


Dear Customer,
Our FY6900 is can be do it. Can you tell me your email? I could send you the user manual by email.

FeelElec

Hi @FeelElec
I have sent you a Personal Message with my email address.
enut11
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: beanflying on December 08, 2019, 11:01:20 am
It's more like you are expecting a Leopard to change it's spots expecting actual and credible customer service from Feeltech/Feelelec

All I see here is attempts at platitudes and more of the same 'support' as in the past.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on December 08, 2019, 11:05:32 am
Just ensure you know the revision number before purchasing it, 1.2 and before can't have software upgrades, that "feature" :palm:  was only released in 1.3

Where did you hear this? If true, that's just really really shitty.

Look a few post above... It was confirmed directly by sales support as well... I ended up selling mine, otherwise I would be stucked to a brick
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Clarmrrsn on December 08, 2019, 12:07:43 pm
Be careful if buying FY6900 on Ebay (As Always)

As I suspected the seller I ordered from as above is full of it, dispatched on monday and tracking still has not updated.  Says "In transit to Yodel". Yet seller insists it is shipped from uk!!!   (Maybe they are walking it from London to Falkirk)

Can get no information from the seller, I would be better speaking to the next door neighbours dog and asking him where my parcel is.

Typical Chinese Ebay seller.

Unfortunately though it looked the best option at the time.

Well ill be a monkeys uncle.

It has turned up at Yodel Livingston depot at 7am this morning (On a Sunday.......really??)

I suspect they did indeed get some poor soul to walk from London to Livingston, they must have walked non stop for 6 days and have blisters the size of golf balls.  :-DD
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on December 09, 2019, 07:53:05 pm

Look a few post above... It was confirmed directly by sales support as well... I ended up selling mine, otherwise I would be stucked to a brick

Thanks, apparently I just read over that. What a crock, honestly. Feelelec shoud ship microcontrollers with updated firmware to everyone who bought a unit with version 1.2 and below, because this is just no way to treat your customers.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: v0ltair3 on December 09, 2019, 09:45:41 pm
If you contact them, they will...

You need to pay for the shipping and resolder it yourself. As I don't have the proper tools for doing it, I would have to pay for the shipping plus finding someone that would offer that service and pay for it anyway... So I sold it ...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 10, 2019, 10:11:21 pm
Hi. Changing the firmware (chips) is a quick and short way. Although not for everyone. :/ And not too expensive. Greetings
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: nctnico on December 10, 2019, 10:19:46 pm
These kind of replacement jobs are much easier when you don't clean the pads (remove solder). Add flux, heat gently with hot air, remove the old chip, put the new chip in place, add flux again and reheat until the joints are nice. Usually there is enough solder on the pads so you don't need to add any solder. If there isn't enough solder on some pads then a big tip (about 3 or 4 pins wide) and flux are all you need to fix it. Just add a little bit of solder to the tip and put flux on the pins. You'll see the flux gets rid of all the bridges. Using a small tip just makes things much harder and messy.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 11, 2019, 07:41:03 am
Hi. It will be easier the next time. I will use your trick. This time when soldering I had too much adrenaline in my blood.  :o Success pleases.   :-+ Greetings.
PS. After replacing the chips and updating FY6900 PC Software to v. 6.5, I updated the firmware to version 1.4. :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on December 11, 2019, 10:08:00 pm
Hi. It will be easier the next time. I will use your trick. This time when soldering I had too much adrenaline in my blood.  :o Success pleases.   :-+ Greetings.
PS. After replacing the chips and updating FY6900 PC Software to v. 6.5, I updated the firmware to version 1.4. :)

Hi, where did you download firmware 1.4 and software 6.5, I can't find it. :-//
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 12, 2019, 07:32:27 am
Simplest way is:  connect to PC and power on generator,, run FY6900 PC Software with admin privileges. Without - its failed. Update software from 6.3 to 6.5. Check firmware version. And update (or not).
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on December 12, 2019, 01:12:47 pm
Thanks for the info, you know what are the firmware improvements from 1.3 to 1.4?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 12, 2019, 02:01:12 pm
It's too new. I didn't have enough time to look around. Because of that ... I have no idea  :-[
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on December 12, 2019, 11:49:16 pm
Hi janusz, there update software to version 6.5, and firmware to version 1.4, the fy6900 start screen still shows v1.3, but the pc software tells me that it has installed 1.4, so I don't know who believe him  :-//


in spanish

Hola janusz, ahi actualize software a la version 6.5, y el firmware a la version 1.4, la pantalla de inicio del fy6900 sigue mostrando v1.3, pero el software de pc me indica que tiene instalado la 1.4, asi que no se a quien creerle :-//
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 13, 2019, 08:48:44 am
The same here. Some time ago a representative of the producer on this blog indicated that the latest version is 1.3. Maybe it's some beta version.  ???  Interestingly, the "Random Noise" signal disappeared. It's like a shifted DC  :-\
---
 Reply #156 on: November 27, 2019, 12:41:03 am: "...Our latest version is 1.3, and 1.3 supports online upgrade. Now that you have the latest version, you do not need to upgrade...."
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on December 13, 2019, 01:35:45 pm
Ive contacted Feelelec via email for a replacement controller with the newer firmware, but have not heard a peep back from them. @Feelelec, could you please advise us on the best way to go about getting this IC?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 13, 2019, 03:21:12 pm
I sent the inquiry and the order to: sales@feelelec.com (available on their website). I think it's a sales department. I got the answer very quickly. Next day. After paying (chips + porto) I received the parcel after about 15 days.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: wz5q on December 13, 2019, 04:40:13 pm
I sent a request to service@feelelec.com for the latest version of the PC Software (ver6.5) as their website only had ver6.3. I received an answer with the requested ver6.5 software attached to it the next day.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on December 13, 2019, 05:04:15 pm
The same here. Some time ago a representative of the producer on this blog indicated that the latest version is 1.3. Maybe it's some beta version.  ???  Interestingly, the "Random Noise" signal disappeared. It's like a shifted DC  :-\
---
 Reply #156 on: November 27, 2019, 12:41:03 am: "...Our latest version is 1.3, and 1.3 supports online upgrade. Now that you have the latest version, you do not need to upgrade...."
[/quote

https://www.youtube.com/watch?v=4cJGHDeAL04 (https://www.youtube.com/watch?v=4cJGHDeAL04)
I comment, watching this video, mine has not changed anything, the noise randon is still, but the software detects it as 1.4 to the installed firmware, it can be a minor adjustment, because the input level follows in 5v the poster, when I should say 20v

in spanish
te comento, observando este video, el mio no ha cambiado nada, el noise randon sigue estando, pero el software me lo detecta como 1.4 al firmware instalado, puede ser un ajuste minino, porque el nivel de entrada sigue en 5v el cartel, cuando deberi decir 20v
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 14, 2019, 09:31:34 am
Interesting video. What interests me the most is: how to use the sweep function effectively?  :-\ And this is how my generator looks (after replacing the PSU) :D
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: thomastheo on December 16, 2019, 04:27:03 am
Well, you guys were right, they responded to my email, and offered to send the replacement chip for a very fair price. It shouldn't have been necessary, but all things considered I am unaccustomed to getting this kind of after-sales care from a manufacturer, so I have to give them props for it. They do stand by their product and even offer parts, which is pretty amazing these days.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on December 16, 2019, 09:36:51 am
Dear customer,
Now, we are releasing version is 1.3. V1.4 is still being tested and is not recommended for upgrade.

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: us0ta on December 16, 2019, 10:26:16 am
Dear, FeelElec! I bought FY-6900-60 on AliExpress, but it does not work properly. The main problem is that the device does not generate a signal at all. When you turn on the device should be a sinusoid, but it is not. When choosing the type of waves, it is also empty at the output. I tested both channels. Cable tested too. When you connect the oscilloscope also indicates the lack of waves. What could be wrong? And how to fix it?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 16, 2019, 11:10:49 pm
(I am not a producer and I do not know if it will work, but) if the cables inside the device did not disconnect and you have not done it yet: I was fix my generator (with firmware version 1.2) Good luck ...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: us0ta on December 17, 2019, 11:29:35 am

  • 1. connect the generator to the PC (via USB) and turn it on,
  • 2 run - with admin privileges - the FY6900 PC Software application (v.6.5),
  • 3 check if the software has correctly detected the generator (lower right corner of the application window: generator type (FY6900-60M) and connection port, (eg COM3), sometimes you need to disconnect and connect the cable USB by OS again detected the generator,
  • 4 on the upper bar go to the "Help" option and run the "Repair_Sine" option.
I was fix my generator (with firmware version 1.2) Good luck ...

Janusz, thank you for reply!
Installing the driver and connecting to the PC passed without problems. I did "Repair_Sine"  several times, but there is no result
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Janusz on December 17, 2019, 01:57:30 pm
...Installing the driver and connecting to the PC...but there is no result
It's a pity! I believe that the help from the manufacturer will be more effective.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on December 20, 2019, 06:51:41 am
Dear, FeelElec! I bought FY-6900-60 on AliExpress, but it does not work properly. The main problem is that the device does not generate a signal at all. When you turn on the device should be a sinusoid, but it is not. When choosing the type of waves, it is also empty at the output. I tested both channels. Cable tested too. When you connect the oscilloscope also indicates the lack of waves. What could be wrong? And how to fix it?

Dear customer,
We are very sorry about this trouble.
This condition may be caused by the internal cable falling off or loose.
Please send one message to my email: sales@feelelec.com. I could send you the files about FY6900 dismantling method.

FeelEelc
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: us0ta on December 20, 2019, 09:32:53 am
Dear, FeelElec! I bought FY-6900-60 on AliExpress, but it does not work properly. The main problem is that the device does not generate a signal at all. When you turn on the device should be a sinusoid, but it is not. When choosing the type of waves, it is also empty at the output. I tested both channels. Cable tested too. When you connect the oscilloscope also indicates the lack of waves. What could be wrong? And how to fix it?

Dear customer,
We are very sorry about this trouble.
This condition may be caused by the internal cable falling off or loose.
Please send one message to my email: sales@feelelec.com. I could send you the files about FY6900 dismantling method.

FeelEelc

I've received dismantling method pdf, but how it can help me?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: FeelElec on December 25, 2019, 09:32:50 am
Dear customer,
Is the cable inside the instrument normal?

FeelElec
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: us0ta on December 26, 2019, 05:51:57 pm
Dear customer,
Is the cable inside the instrument normal?

FeelElec

Everything is ok inside, but device doesn't work properly (
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: yo3fhm on December 30, 2019, 01:51:49 pm
Hi everybody!

I would like to ask if there is anyone who tried to upload arbitrary waveforms to FY-6900 (files created, for example, through Matlab).
There are only some brief references in the user guide, nothing step-by-step :
Quote
- Can output up to 97 groups of functions / arbitrary waveform, contains 33 groups
of preset waveforms and 64 groups of user-defined waveforms.
- Non-Volatile Storage Can store 64 user-defined arbitrary waveforms, (8K 14bits) * 64
- Users can download arbitrary waveform to this instrument after edit through PC program which is included in user CD.
- Note: Arbitrary waveforms can be edited and downloaded from PC software provided by FeelElec

In the hope of your answers, please allow me to wish you a Happy New Year and best wishes !

Regards,
Cezar YO3FHM


Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: yo3fhm on January 02, 2020, 11:54:41 am
OK, while nobody posted any reply to my answer, I found the following information on a review from the FeelElec Store on AliExpress .
It is from a customer from USA (as the flag say there). Hope to be useful for other people :

Quote
The last 2 days I have been testing the functions of my FY6900 generator with a 12 bits oscilloscope. The instrument has lots of controls, and built-in functions, so serious testing took some time. I am very happy with the results. The specifications are fulfilled within the given limits. The generator came with software to control it through an USB connection. The computer control works fine. The software also allows you to draw your own waves, and to store them as arbitrary wave which works also well; another plus for the FY6900. The manual was a good help, not to long, but clear; that is the next plus. I am most satisfied with this instrument, its software and documentation, and its very reasonable price. Thank you FEELELEC for your balanced equipment, and documentation. I expect it to be highly useful for the next years in my workshop. 28 Sep 2019 14:17

Also, I mention that I contacted FeelElec and the response from their sales (on the E-mail) also included the serial communication protocol (Host Computer Communication Protocol Specification Rev 1.8 ), which contains the commands *and* all the necessary examples for programming !
I think this is a big plus for those who want to automate various measurements.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: wz5q on January 09, 2020, 02:00:59 pm
I have a FY6900-60M (Serial Number 191169001053) Firmware rev 1.3.

It is working just fine and I am impressed with the device.
It works amazingly well for the cost.

The only bad thing I have found is an aggravating anomaly with the "SWEEP" function.

The following is an example:

The unit is set for running a Sine Wave, Linear Frequency Sweep from 1Hz to 100KHz at a time period of 500.00 seconds and the direction set to Forth. When the Sweep is engaged, it starts at 1Hz and starts to increase in frequency normally until it reaches 100KHz. This is normal function.

This is the anomaly:
If you stop the Sweep and then restart it, it does not start at the set beginning frequency.

For example, the Sweep is running from 1Hz to 100KHZ and you stop the sweep at 10KHz. If you start the sweep again it starts at 10KHz and continues to 100KHz. The sweep does not start again at 1Hz, it remembers where it stopped and starts at that point to continue. There is no option I can find to make it start again at 1Hz where the unit is set to begin, it will always remember where it stopped and starts at that point.

This anomaly also occurs when the direction is set for Forth, Back, and Forth to Back.

I sent Feeltech an email at service@feelelec.com explaining this, we shall see what they say.
Hopefully they can fix this in a future firmware upgrade.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: AlMuz on January 09, 2020, 09:39:47 pm
Hi Everyone,

I've finally got my device and have a few questions to a group of experienced users.
 
But first few words about my experience trying to get it from China:
I was trying to get this device since September 2019. 
To be added - I am not trying to say that AliExpress better than Banggood. It is just hit or miss with these Chinese re-sellers. Had similar issues at AliExpress ordering T12 soldering iron from KSGER (however going to another seller helped).


So, back to device:

I am not an expert, but would recommend to everyone do tear-down immediately to check everything.
Say in my scenario I had a ground wire barely holding to solder joint on power connector. It fell of when I finished removing plastic panels.
Totally sure it would fell off by itself just from ambient vibrations in the room, with a risk of shorting device ground to power line.

I've got a Kkmoon 60Mhz version. Which looks have got slightly updated main board from what posted here previously (silckscreen says v.1.9 instead of v.1.8)
Major difference I see (from what I could figure out just by looking on videos and pictures posted by others) is that the newer board got a FAN connector under the power-lines plug.
Which is in fact complete nonsense -  it is simply a  JST connector footprint that is directly hooked to 5V power rail. You will not get any speed control. But 5V probably might be enough to spin 12V 40mm FAN at a lower RPM still getting away some heat without producing too much noise.

Also - the ground wire in my version goes directly to the main board, instead of power supply broad. This is probably better, avoiding the resistance of few additional wire-plug contact points on the way to BNC connectors. The wire still just cut-off from original 6 pin connector. Anyway, as a simplest safety improvement I would replace thin ground wire from JST plug with a proper thick and insulated ground wire that goes directly from GND TH-pad of the FAN plug (or any other massive GND pad at the bottom ground plane of the board).

Anyway, I did not go for FAN installation to this JST pad or ground wire fix just because I plan full replacement of power supply. I've noticed some spikes in output signal likely from swithing supply, so plan to rework it into decent full-linear regulator.

Just ordered nice fitting (D=3" x H=1") toroid transformer.  There are plenty of these available on eBay or AliExpress for $35 shipped. Designed for audio amplifiers some of them posses output windings of multiple voltage levels (+/-9 and +/-15).

In my case I've got a very good deal ($23) for 20VA toroid with just two 13V AC positive and negative windings.  Should be just right to power 12V (or actually 13.5V) DC rails. For that I plan to use widely available AC-DC supply module based on LM317, LM337 and LF353 (not sure what the last OpAmp serves, looking to schematic - likely for better output stabilization).

5V supply for digital circuitry will drop on positive winding (should have common ground with analog op-amp supply rails anyway).
And to somewhat even the load between positive and negative windings - will drop a separate full bridge rectifier with BUCK converter to power-up a temperature-regulated FAN speed controller. Total of all the parts I've already ordered (with some additional components) is under $60.

The question:
I've also noticed that main board has two new empty SMD pads for inductors, they were not there before in FY6800 version (to the right of power rails JST connector). Likely for additional filtering of +/- 12V rails. There is a narrow trace connecting two square pads on each inductor footprint (shorting them togather). Did anyone cut those and installed some chokes? What were the choke parameters (inductance and series resistance)? Did you notice any improvement in signal output (with original power supply or upgraded one)?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: excitedbox on January 13, 2020, 12:29:22 am
I also had problems getting mine. I ordered on Ebay but it disappeard in Customs. The seller sent it again and same thing happened. Then I ordered from AliExpress from a seller that claimed to ship from Spain but really shipped from China and repackaged in Spain. This caused a long delay and the seller didn´t answer any emails until the last day of my dispute on AliExpress. It seems the repacking company doesn´t update the tracking number so the tracking shows it as delivered even though it only got to their warehouse in spain. After that it still took another 3 weeks until it arrived. I was pretty angry because the shipping guarantee was for less than 2 weeks total and it took over a month and a half. Plus no communication was just unacceptable. In addition to claiming to ship from inside of the EU. I would not have ordered there if I had known that. I even paid 12 Euros extra for shipping which I would have saved buying directly from China.


In the end it all worked though and I ordered an Amplifier board for ~26 Euros so I can output up to 32V 5A waveforms.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rhb on January 14, 2020, 03:38:17 am

In the end it all worked though and I ordered an Amplifier board for ~26 Euros so I can output up to 32V 5A waveforms.

32 V into a 50 ohm load is 0.64 A.  5 A through 50 ohms requires 250 V.

I think there is something wrong with this picture.

Reg
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: nctnico on January 14, 2020, 08:22:29 am
Those amplifier boards don't have 50 Ohm outputs; usually the output impedance is close to 0 Ohm.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: teecelly2020 on January 14, 2020, 02:15:30 pm
Replaced the power supply in the FY6900 with this handy module from Jameco.  Meanwell PT-65B +5v, +12v, -12v switching supply.  https://www.jameco.com/Jameco/Products/ProdDS/216726.pdf (https://www.jameco.com/Jameco/Products/ProdDS/216726.pdf)

Fits perfectly.  has isolated ground, and lower noise than original unit.  Lowers noise floor and THD dramatically...especially below 4 volts.  (I use it for audio testing)  Also, higher current capability means it doesnt sag under load.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rhb on January 14, 2020, 03:43:20 pm
Those amplifier boards don't have 50 Ohm outputs; usually the output impedance is close to 0 Ohm.

6.4 ohms based on the numbers given.  Actually not a bad compromise if one wants to drive 4 & 8 ohm speakers for testing.  But really bad if one is trying to drive an RF power amplifier.  I just wanted to emphasize that you need to also state the load impedance not just voltage and current.

Have fun!
Reg
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: einfachprima on January 14, 2020, 06:05:36 pm
I received my FY6900-60 last week (KKmoon, firmware 1.3). Based on the infos in this thread and on the website of Janusz (thanks a lot!) I was able to do the following modifications:
The software is useless for me, there is also a major bug, if you enter a frequency the unit gets the wrong frequency (e.g. entering 60 MHz results in 6 MHz).

There is one thing I don't understand: Some of you replace the power supply with a better one. And  this is a lot of work. What's wrong with the Feeltech power supply? How can I measure the problems of this power supply?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on January 15, 2020, 12:51:21 am
I received my FY6900-60 last week (KKmoon, firmware 1.3). Based on the infos in this thread and on the website of Janusz (thanks a lot!) I was able to do the following modifications:
  • I replaced the rotary knob with a more finger friendly knob
  • I added four small rubber feet to avoid moving the unit on my table
  • I calibrated the frequency so it fits to the frequency counter of my oscilloscope
  • I replaced the tiny cable to mains ground with a solid one
  • I installed software 6.3, updated to 6.5 and installed firmware 1.4
The software is useless for me, there is also a major bug, if you enter a frequency the unit gets the wrong frequency (e.g. entering 60 MHz results in 6 MHz).

There is one thing I don't understand: Some of you replace the power supply with a better one. And  this is a lot of work. What's wrong with the Feeltech power supply? How can I measure the problems of this power supply?

 As far as I'm aware, the FY6900's smpsu board is a slightly modified version of those used in the previous two models (6600 and 6800) and its main failing in this context is that of all cheap smpsus, high levels of conducted and directly radiated switching noise from the mains voltage HT switching module, not forgetting the related switching ripple noise riding on top of each voltage bus (+5, +12 and -12 volt rails - or, in this case the +5, +13.5 and -13.5 volt rails).

 The only good things about the psu board used in these signal/function generators are that they are class II psus which don't require a safety earth connection (and therefore neatly avoids the ground loop issues introduced by FeelTech's abuse of the LVDC 6 wire ribbon cable in the 6800 and 6900 models) and the design of this smpsu whereby the secondary 12 or 13.5 volt rails are inherently symmetric in output current rating to create a perfectly balanced bi-polar opamp supply which is something I've yet to see in any similarly rated 3 rail smpsu.

 Searching for a better quality smpsu to replace the existing unit with one that also offers identical current output ratings on the +/-12 or 15 volt rails has, so far, been on a par with searching for Unicorn droppings or Hens' teeth. Every single contender had this curious imbalance between the +/-12 or 15 volt rails, typically a 1A positive rail versus 330 to 500mA on the negative rail (a 3:1 to, at best, a 2:1 current rating ratio).

 Considering that the blindingly obvious, no-brainer use of +/-12 and 15 volt psus is to power opamps requiring balanced bi-polar supply rails, this lack of balanced output smpsus is quite contrary to all expectations where one might consider the 2:1 and 3:1 current rated psus to be speciality 'curios' manufactured for obscure off the wall applications rather than the almost ubiquitous pests of the smpsu world they appear to be. IOW, just WTF is going on!

 The only downside to the FY6600's floating ground rail was the troublesome half mains live 'touch voltage' courtesy of the EMC mandated use of the class Y capacitor bodge which creates an ESD hazard to the DUT. Many owners of the FY6600 replaced the C8 mains socket with a C14 in order to provide a ground connection to shunt this half live mains touch voltage directly to ground to suppress this ESD hazard. Some recognised the earth loop issues in using a hard connection so used a 100nF cap in series which eliminated any unwanted DC offsets from the mains earth wiring but did nothing for high frequency noise both being picked up by and sent out from the signal generator.

 In the end, after several weeks of looking for a solution that would allow me to retain the original C8 mains connection (an exercise in futility as I eventually proved), it turned out that the optimal solution was to upgrade the C8 to either a C6 or a C14 socket and simply use the protective earth terminal as a connection for a "static drain" resistor of sufficiently low value to reduce the 115vac 'touch voltage' down to just half a volt. In this case, a sufficiently low value of 'static drain' resistance turned out to be 10KR. Low enough to eliminate the ESD hazard but high enough to provide some 60 to 80 db attenuation to interference between the signal generator and the mains earth wiring.

 Some FY6600 owners tried upgrading the psu to a better quality smpsu and others chose to design and build an analogue psu based on a conventional mains transformer using 7805, 7812 and 7912 voltage regulators.

 Unless you can track down an ultra quiet smpsu designed for use in sensitive test gear, a seemingly better quality smpsu probably won't provide much, if any, improvement over the original in terms of noise reduction, Hence the decision by many to go the "analogue psu" route with a DIY design of their own.

 Many of these were successful but others fell foul of the additional heat produced by the voltage regulator ICs which, despite the manufacturers' claims for overheat protection, burnt themselves out anyway, taking out an opamp in at least one such case.

 I've been considering a psu upgrade for some time now and I've reached the conclusion that the best cost effective solution would be to use an R type mains transformer (24 to 30VA with two separate 16 to 18 v secondaries) and use dc-dc buck converters with ldo voltage regulators to get the best of both worlds (switching and analogue).

 However, before I even start such an upgrade, I have yet to test the potential improvement using battery power (a 12v SLA for the +12v and +5v rails (7805) with a couple of 6v lantern batteries to provide the -12v rail) to completely eliminate the smpsu switching noise which currently pollutes the generator's output. Once I've seen the effect of eliminating such switching noise for myself, I'm sure I'll have all the motivation I'll need to design and build my own replacement psu. At the moment though, my 'Basic GPSDO' project has priority and such battery testing remains on the back burner for the time being.

 As for "measuring the problems of the psu", the best way to quantify the 'problem' is to substitute it with 'battery power" as I described above and check the generator's output using an HF radio to tune into and around the carrier frequencies chosen for this test. You can, of course, use a spectrum analyser if you are so blessed but an HF radio can be just as effective a way to discern any improvement.

 Trying to quantify noise and ripple of any power supply using an oscilloscope is fraught with many problems as explained in the following YT video https://youtu.be/Edel3eduRj4 (I just put "measuring psu noise and ripple" into YT's search box and this, unsurprisingly, was the first hit).

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: einfachprima on January 15, 2020, 09:40:09 pm
Thanks for your detailed answer!

I had mixed up some information for 6600/6800/6900 in the past. Let me summarize what I now understand. Basically there are two independent problems:

Ground connection / ground loop / ESD hazard

FY6600 has a C8 mains connector without PE. That's ok because it's a class II power supply. And it has an advantage: no ground loops etc. Disadvantage: A voltage between PE and BNC ground can be measured (ESD hazard).
Possible solutions:
FY6900 has a C14 mains connector, PE is connected to PCB ground (with an inappropriate wire ...).
If I want to separate PE and BNC ground I have three possibilities (similar to FY6600):
Do you suggest to use option 3 (drain resistor)? Or is it better to use an isolation transformer?

Signal noise introduced by smps ripple/noise

It's a good idea to do a short test with a battery powered FY6900. If the signal is significantly better a new power supply (linear regulator, ...) is an option (this probably solves the ground problem as well). Currently I doubt that justifies the effort. At least for me and my oscilloscope. The ripple/noise of the function generator output is currently no problem for me (between 5 mVpp and 20 mVpp with a visible 60 kHz signal).


Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on January 16, 2020, 05:33:17 am
Thanks for your detailed answer!

I had mixed up some information for 6600/6800/6900 in the past. Let me summarize what I now understand. Basically there are two independent problems:

Ground connection / ground loop / ESD hazard

FY6600 has a C8 mains connector without PE. That's ok because it's a class II power supply. And it has an advantage: no ground loops etc. Disadvantage: A voltage between PE and BNC ground can be measured (ESD hazard).
Possible solutions:
  • Replace C8 with C14, connect PE to BNC/PCB ground
  • To avoid ground loop a 100nF capacitor can be used (in serial)
  • To avoid ground loop a 10k drain resistor can be used (in serial)
FY6900 has a C14 mains connector, PE is connected to PCB ground (with an inappropriate wire ...).
If I want to separate PE and BNC ground I have three possibilities (similar to FY6600):
  • Remove wire between PE and PCB ground
  • Add a 100nF capacitor (in serial)
  • Add a 10k drain resistor (in serial)
Do you suggest to use option 3 (drain resistor)? Or is it better to use an isolation transformer?

Signal noise introduced by smps ripple/noise

It's a good idea to do a short test with a battery powered FY6900. If the signal is significantly better a new power supply (linear regulator, ...) is an option (this probably solves the ground problem as well). Currently I doubt that justifies the effort. At least for me and my oscilloscope. The ripple/noise of the function generator output is currently no problem for me (between 5 mVpp and 20 mVpp with a visible 60 kHz signal).

 I'm not surprised you were mixing up the information between those three topic threads. The FY6600 one has been going for some two and a half years and is now 86 pages long with a total of 2149 replies as of the 2nd of this month!

 If that 5 to 20 mV ripple with a visible 60KHz signal you mentioned is a reference to the 60KHz switching noise, you might see some reduction if you try it with a 10KR in series with the earth connection.

 My own concern over the noise and ripple stems from my experience when generating a 30MHz carrier using a Kenwood TS140S HF transceiver to monitor it where there did seem to be some ripple and noise modulation on what should in theory have been a perfectly quiet carrier wave. Other than that, such ripple noise hasn't proved to be a major problem so far but then I am still working on modifications to enhance its frequency accuracy and stability so haven't been using it very much other than for testing those modifications and researching the workings of a DIY GPSDO I've been working on for almost a year along with discoveries of the GPS system's own deficiencies (nanosecond phase shift modulation due to ionospheric propagation conditions being the major problem for a basic pll driven GPSDO such as the one I'm trying to rebuild into a screened metal enclosure onto veroboard).

 The FY6600 has been a project in its own right for just over a year now and was what had spawned the basic GPSDO project I'm trying to box up as a workable frequency reference. These two 'projects' feed off each other so I'm dividing my time between the two. What doesn't help is my reliance on Banggood and Ebay to supply the components needed for these and other ancillary projects which have created additional delays to these long drawn out projects. I might eventually get around to fitting the four long screws that secure the FY6600's case halves together and have my GPSDO up and running in maybe as little as 6 months time with a bit of luck.

 When I was looking at the half mains live touch voltage issue with my own FY6600, I was a little reluctant to convert from the C8 connector and the very flexible 2 wire 6A mains cord to a C14 connector with its much stiffer 3 wire 10A rated mains cord in order to avoid the "Tail Wags Dog" effect with such a lightweight piece of test gear (only 700 grammes with no grippy rubber feet to stop it sliding all around the bench, especially true when propped up on its bail stand which left the rear hard rubber faced feet dangling in mid air as the rear edge grounded onto the bench top).

 I tried all sorts of inventive schemes to eliminate the touch voltage including mostly ways to cleverly null it out, overlooking the fact that you had to at least detect which way round the neutral and live wires of the non-polarised cord were plugged into the C8 socket so as to connect your nulling out circuit's reference to the neutral.

 Several doomed experiments with 1:1 mains transformers to create my anti-phase mains voltage source finally convinced me that, whilst in principle such a scheme could be made to work given a clever enough polarity detection system to control an automatic mains reversing switch, my "clever cure" was far more trouble than it was worth and still contained a risk of doubling the touch voltage if it went faulty for any reason.

 Since I've already suffered way too much at the hands of the Lord Murphy (of "Murphy's Law" fame), I decided that discretion in this case was most definitely the better part of valour and gave up the whole idea of nulling out the problem and looked to the more prosaic solution of using a polarised 3 pin mains socket to provide a convenient earthing point for attaching a 10KR drain resistor to kill off the touch voltage without introducing a low impedance earthing loop into the circuit.

 By way of a compromise in regard of the "Tail Wags Dog" effect, I chose a C6 (trefoil - clover leaf) mains inlet socket instead of the big butch C14 sockets other FY6600 owners (and Feeltech in the case of their 6800 and 6900 models) had elected to use. I'd noticed that a few of my C6 mains cables had been made up using thinner lightweight mains flex than typically used with C14 cords which would mitigate the "Tail Wags Dog" effect (as indeed this proved to be case).

 It might be argued by some that by not directly connecting the protective earth to the zero volt rail (BNC grounding point), I have compromised the generator's electrical safety. However, since it uses a class II smpsu board which does not require the use of a safety earth anyway, I don't see this as an issue of safety in this (plastic) case. The mains socket upgrade is merely to provide a reliable earthing point to automatically shunt the Y cap's half mains leakage touch voltage safely to ground via a 10KR resistor.

 It seems that Feeltech had been reading the FY6600 topic thread and taken note of the stream of complaints over this half mains live voltage issue and in a half assed ill thought out bout of unthinking pragmatic knee jerk response, decided to "upgrade" to a C14 mains socket, vandalising the 6 wire psu to mainboard ribbon cable to divert one of the only two ground return wires directly to the protective earth tag. Not only had they introduced an unwanted low impedance earth loop issue, they'd also aggravated the psu noise and ripple by stealing one of the ground return wires linking the psu to the mainboard into the bargain.

 Judging by the fact that the ill fated FY6900 was also given the very same (identical in fact) treatment, it looks as though Feeltech must have given up monitoring the FY6600 thread once they'd sprung their "Improved FY6800" upon an unsuspecting world otherwise they'd have used a more elegant solution for the FY6900.

 Basically, when it comes to fixing the earthing sins of the FY6800 and 6900 models, the optimum solution of using a 10KR (or even a 3k3R if you prefer) to link the ground rail to the protective earth as described for the FY6600 remains the same since these later models still use a cheap and cheerful class II smpsu board inside of their plastic cases which don't require a low resistance earth connection to meet electrical safety requirements.

 However, for those of a nervous disposition over the use of unearthed test equipment, there are ways to provide a low impedance path for fault currents to flow to the protective earth which under normal, non-fault conditions, can still provide a high resistance drain path for the unwanted half mains touch voltage. Basically it amounts to shunting the 10KR (or 3k3R) drain resistor with a couple of high current silicon diodes in series in anti-parallel with a second such pair (four diodes in total). In this case, you can get away with just a single pair of anti-parallel high current rated silicon diodes by using a 3k3R resistor (the ground loop noise margin will only drop 10dB in this case).

 This is a method I'd used some forty years ago to eliminate mains earth loop induced hum on a turntable with built in RIAA amplifier which blessed it with line out level signals that already gave it considerable immunity to such mains earth loop induced hum. In this case, since it was essentially only the 50Hz and the first few harmonics I was concerned with, I recall putting a 100nF cap across the two back to back diodes to guard against the possibility of high frequency harmonics should the diodes start to conduct and generate any distortion products (I can't remember whether or not I'd included a 1 or 10 k resistor across the diodes). I think the diodes I'd used had an Irr rating of 6A.

 In this case, I wouldn't add any capacitance across the diodes, just a 10 or 3.3 k resistor. If you're only guarding against the risk of a mains fault internal to the generator itself, I should think 6A rated diodes would suffice. If you're more concerned over an attached DUT injecting mains voltage, you'll probably want to fit 20 to 50 amp rated diodes (in which case you're likely to see the mains flex burst into flames with that level of fault current). For such current ratings, it's probably best to parallel up several 6 or 10 amp rated diodes to improve the chances that at least one will fail short circuit in the event of any such catastrophic fault current events.

 That, of course is a very simple solution and I'm sure there are better alternatives based on a pair of heavy duty thyristors (or triacs for some redundancy) where you can trigger them from a higher volt drop such as 10 to 30 volts to avoid any false triggering. Of course, triacs and thyristors have minimum sustaining current specs which will need to be considered in such a paranoid protection scheme. The one thing I wouldn't rely solely upon in such protection is any form of electromechanical relay to switch the high resistance drain circuit into its low resistance safety earthing state.

 TBH, after proof reading this, it does seem a rather over the top solution to a problem that may never ever arise but If I'd seen the need forty odd years ago to provide a safety earth connection that would avoid the hum loop issue, there may well be purpose designed devices available for just such protection by now but it hasn't occurred to me to go searching for any. A quick internet search failed to reveal any such ground loop isolating devices. My perception of the quality of human ingenuity has just gone down yet another notch or two. :(

  After having another go at tracking down a diode based 'hum eliminator' I came across this Youtube video https://youtu.be/qNQX8jyxRrs where the guy mentioned a 70 dollar hum eliminator, the "Ebtech Hum X Ground Loop Hum Exterminator" which he'd suspected was also based on the two anti-parallel diodes device he was building. I had already come across this item which I'd also had the same sneaking suspicion that it was quite likely based on the same principle (possibly utilising triacs rather than diodes).

 The youtuber mentioned that he'd seen the circuit he was building in other internet sources but failed to mention where. It would have been nice to track down other mentions of a circuit I'd invented for my own use over forty years ago. It seems I'm not the only person on the planet to have come up with the blindingly obvious solution to safely overcome the issue of hum loops in domestic audio systems where the short runs of screened interconnects are able to short out the modest voltage drops involved to keep the diodes in the high impedance state as in the case of the Feeltech signal generator's connections to the DUT and any other test gear located on the test bench.

 Two final observations I have in regard of that youtube video and the "Ebtech Hum X Ground Loop Hum Exterminator", is that I think the safety concerns that were expressed in the comments are entirely valid. The only safe place for such a circuit is inside the device rather than as an external add on adapter. Also, the need for 500v PIV rated diodes is a spurious one where the anti-parallel connection of the two diode (strings) means they'll never have to face more than one or two diode forward volt drops worth of reverse bias anyway.

 If one of the diode strings fails open circuit under a fault event, the 500v PIV rating won't help the situation and it would be far better to give a 50v PIV diode every opportunity to fail short circuit in such a circumstance. Indeed the lower the PIV rating, the better the chance of it failing short circuit rather than being blown to smithereens like a glass fuse by a high energy 300+ volts avalanche breakdown transient.

 If a semiconductor manufacturer could be persuaded to integrate this diode or triac based ground loop hum eliminator into a dedicated device, it could be optimised to reliably fail safe and meet electrical safety standards so I'm a little disappointed that there seems to be no such device commercially available. Presumably there isn't sufficient demand to justify the required investment.

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: einfachprima on January 16, 2020, 11:42:30 pm
Today I compared the noise of the FY6900 (DC 1.0 V & DC 1.1 V because the amplifier changes above 1 V) with the different PE options (disconnected, connected, 100nF, 10KR). I found no or only minor differences, so this has no real influence.

I will keep the 10KR (or the cap) to suppress the half mains leaking voltage between BNC GND and PE and to avoid ground loops. I'm fine with that solution.
Further (paranoid) protection with several diodes or triacs is an interesting thought experiment, but I don't think I need it.

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on January 17, 2020, 07:08:51 pm
Today I compared the noise of the FY6900 (DC 1.0 V & DC 1.1 V because the amplifier changes above 1 V) with the different PE options (disconnected, connected, 100nF, 10KR). I found no or only minor differences, so this has no real influence.

I will keep the 10KR (or the cap) to suppress the half mains leaking voltage between BNC GND and PE and to avoid ground loops. I'm fine with that solution.
Further (paranoid) protection with several diodes or triacs is an interesting thought experiment, but I don't think I need it.

 Your results with the varied earthing arrangements suggest that the common mode choke in the mains input filter on the psu board is doing a pretty effective job in attenuating switching transient noise leaking into the mains supply.

 Like yourself, I don't think there's any real need in this case (class II appliance) for the anti-parallel diode measure I'd offered for the benefit of anyone worried that inserting a 10k or 3k3 ohm resistor in series with the grounding wire would compromise the electrical safety of the signal generator in any way.

 The Thorens record deck however, being a class I appliance, was earthed for electrical safety so I wanted to avoid the risk of lifting the earth connection to rely solely upon the phono interconnect leads to the grounded inputs of the attached amplifier as was common practice in the audiophile community, hence my thinking laterally about the problem and the anti-parallel diode solution I'd concocted to fix both safety and ground loop issues at a single stroke.

 In this case, should the BNC grounds go fully live for any reason, I suspect the worst that would happen would be the operator receiving a "nasty jolt" through a fingertip rather than suffer electrocution (assuming said operator fails to notice a stronger than usual mains voltage tingle and take the hint that further careful investigation with a test meter should  be instigated to pinpoint and remedy such a potentially fatal fault condition).

 The risk of electrocution in this case seems such a vanishingly small one that I personally feel comfortable enough to live with (and I'll stake my life on that! :)).

 However, in the light of the above statements, it has just occurred to me that a better way to detect whenever a dangerous mains potential from whatever source is present on the BNC ground circuit of the signal generator (aside from the emission of magic smoke from a half watt 10k resistor) is to wire up a pair of blue leds (chosen for best luminous efficiency and brightness) in anti-parallel (for redundancy) in series with a 150k half watt or higher rated resistor across the 10k resistor (effectively a modern solid state version of the classic neon mains indicator lamp).

 This can be added to the front panel as a "Dangerous Earth Potential!" warning lamp to remove reliance on the operator managing to safely notice the resulting mains tingle touch voltage by pure dumb good luck alone. This offers the benefit of not only indicating a live to earth fault in the signal generator itself but also that of similar faults within any other connected test kit.

 Of course, one would need some means to verify that this warning lamp is in good working order. At the very least, it would need to be tested after its initial installation and at regular intervals thereafter (perhaps monthly or annually). In the case of 220/240v mains voltage, assuming a half watt rated 10k "drain" resistor has been installed, a 2W rated 27k resistor probe connected to mains live could be used to probe the BNC grounds whilst the generator is isolated from any other grounded kit ( in 120v regions, an 8k2 ohm 1W resistor could be used for this test). This should result in some 60 to 70 volts rms across the drain resistor, sufficient to light up the warning LEDs without risk of it burning out.

 Even better would be to incorporate this test resistor into the circuit with a test button that could be located out of the way on the rear panel. In this case, one might elect to use a 27k resistor regardless of the mains voltage standard. This will result in a 0.3mA lamp current on a 120v supply which is still more than sufficient to light up a blue LED quite nicely.

 Adding a  "Dangerous Earth Potential" warning lamp to the signal generator makes a lot more sense as a safety measure than my original anti-parallel diode idea which introduced the risk of overloading its mains flex earth conductor with fault current (quite possibly a hundred amps or more) from any other connected equipment that happens to suffer a live to earth contact fault. It's a feature that certainly merits further consideration but for now, I'll park that idea on the back burner until I've completed my current and more pressing list of planned upgrades.

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BeeJee on January 19, 2020, 12:11:14 am
did you see the high quality solution by SDG Electronics on Youtube for the better psu in his FY6900 ? his video's # 029, 077, 080 & 081
 are very elaborate & usefull about that..
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rhb on January 19, 2020, 02:31:31 am
Johhny,

Your are, as always, a bit over the top in detail.  But a huge pleasure to read.  Someone once remarked about me that if you asked me the time, I'd tell you how to build a watch.  You go a step farther and explain how to build the machines to make the watch parts. :-)

Have Fun!
Reg
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: stcoso on January 19, 2020, 02:40:34 pm
Hi, I've got this func gen and I'm looking for a way to control it from PC without using the software from feeltech. Is the communication protocol known?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: nctnico on January 19, 2020, 06:39:33 pm
did you see the high quality solution by SDG Electronics on Youtube for the better psu in his FY6900 ? his video's # 029, 077, 080 & 081
 are very elaborate & usefull about that..
I've seen those too but I have doubts about the clearances (a 3.5mm screw terminal doesn't have the clearance for 230V mains) and the design seems to be over complicated without getting to really low supply voltage noise levels.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on January 20, 2020, 10:28:32 pm
did you see the high quality solution by SDG Electronics on Youtube for the better psu in his FY6900 ? his video's # 029, 077, 080 & 081
 are very elaborate & usefull about that..

 I found #077 and just 6 1/2 minutes in I see he's elected to choose a 1.5A -13.5v dc-dc converter which is 3 times the actual half amp requirement worst case loading with a -12vDC on both channels feeding 50 ohm loads  :wtf:

[EDIT] see the edit below - it's more like a factor of 6!

 I haven't watched the rest of the video just yet but I thought I'd post a quick response to his initial miscalculated requirements for the +/- 13.5 volt rails before viewing the rest to see how he's going to keep HF switching noise from leaking onto the output rails of the LDOs he was considering - I've done some more research into this subject since my last posting and am fully aware of the pitfalls in just slapping LDOs onto the output of buck/boost converters to get noise free DC rail voltages.

[EDIT]

 I finished watching that video and managed to track down the rest (I think!) from his home page which actually took ages to show up. I noticed he'd taken additional measures to keep the switching noise out of the LDO regulators and made provision to deal with the effect of the Y cap in his 24v mains smpsu module. I have to say I disagree with the use of a 10 ohm resistor to suppress the half live mains touch voltage issue since even a 10K ohm resistor is a low enough shunt impedance to hold this leakage voltage down to a mere half volt (at least in the case of the original smpsu board - it might need the use of a 4k7R for this higher power replacement) more than low enough to keep even the most delicate of ancient mosfets safe from harm.

 As for the 8mV of noise on the outputs of the generator being residual random noise in the opamps themselves, I'm not entirely convinced that that is the case, especially as he'd set the output to zero with no dc offset. That final test didn't seem thorough enough to my mind - ok as an initial check to confirm his psu wasn't radiating/conducting switching noise into the main board circuitry perhaps.

 A more thorough test would involve selecting the DC "waveform" set to 10 or 12v into 50 ohm loads on both channels. This the worst case psu loading of circa half an amp when both channels are generating +12 or -12 volt dc outputs simultaneously into short circuits - actually, it's a mere quarter of an amp when driving 50 ohm loads - even I was out on my initial psu amperage estimate! :palm: A CMOS waveform at 99% duty cycle would come a close second worst case as far as the positive 13.5 rail is concerned.

 I'm wondering if he actually did any similar noise checks with the original smpsu board in place before embarking on this psu upgrade. It's quite possible that most of the improvement might have arisen simply from the use of a well shielded mains voltage to 24VDC smpsu module replacing the original RFI radiating smpsu board.

 Putting the original psu board into a metal enclosure of similar volume to his replacement PSU assembly might possibly have proved just as effective a solution. We'd be looking at a large and airy enough full metal jacket to keep things cool and shielded whilst also providing containment of any possible fire hazard posed by the original board - it's just a thought.  ;)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: nctnico on January 21, 2020, 02:14:49 pm
Try to set the PSU on fire. I'm quite sure it won't burn at all. It is a typical standard consumer PSU which has likely been sold to power millions of pieces of household electronics.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: beanflying on January 21, 2020, 11:45:28 pm
Other than the floating Neutral/Earth issues the power supply is no more or less horrid than the average to poor cheap ones sold in a bunch of items. Going to massive efforts to replace it with a relatively costly solution in this cheap box makes little to no sense. By the time you weigh up the cost of bits and even a bit for the time spent you are pushing toward some of the 'better' other Chinese made alternates.

That is not to say don't complain about it but it should be made clear AGAIN to the manufacturer that it is sub par and poorly engineered from the factory and unacceptable.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: AlMuz on February 24, 2020, 10:20:59 pm
And this is how my generator looks (after replacing the PSU) :D

hi Janusz
I see you have chokes soldered at L6 and  L7, near the +12V and -12V (or +/-13.5V actually) input lines.
Did you solder them in or you already had them in place?
If you did - what are their parameters? how did you pick?

Mine FY6900 60MHz came with nothing soldered there, just empty pads and "L" (I see that the pads are shorted with traces).
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: flannp on March 03, 2020, 12:11:53 am
I just picked up a FY6900 60Mhz. V1.3.1

Does anyone know if it's possible to calibrate the timer on the sweep function?
I'm seeing a timing issue on my box, for example if I try a 2 second sweep I see a 1.8 second sweep on my keysight DSOX1102A scope.
The timing issue seems to multiple as I do longer sweeps, so for example a 10 second sweep will output a 11.8 second sweep and so on.

All modes seem to have the issue
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: metrologist on March 03, 2020, 12:32:13 am
In one case the sweep is fast and another it is slow.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on March 03, 2020, 03:15:33 pm
Hi flannp, how did you set up the fy6900, because if you set it as the second image, it doesn't reproduce the scan of the first image.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: flannp on March 03, 2020, 07:43:50 pm
I was using a high pass filter.

I just did it again with a 10k resistor and 100nf RC low pass filter.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: flannp on March 04, 2020, 02:24:28 am
In one case the sweep is fast and another it is slow.

That is just the end of the previous sweep that wasn't fully captured. It was at the same speed
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Mouse69 on March 13, 2020, 04:54:33 pm
Hi Guys,

Well I'm going to start modding my fy6900, first was the earth mod, but what follows here trying to keep it cool.

[attach=1]
This is the spray painted black (stove paint) heat sink, I'll be adding a very small scrape of thermal compound under it

Next the lower grills in each side, I used a Stanley knife, gently pushed with my thumb (sharpe bit on the grill, safe back of knife against my thumb) to cut them away, to allow a little more air in

Then marked out some 5mm spaced holes in the top casing and drilled (note to self, next time idiot put your glasses on)

And added a fan at the back

Fan not connected yet, I'm doing the SDG PSU swap out, it will get wired in at this point to suck the air out the back (I used an MTB bike tube to make a gasket and yes I can see it's not perfect at the top, I will try and address that - to keep the vibration and thus noise down).  I'll get the thermal camera on it and see what it looks like once it's done
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on March 14, 2020, 08:59:45 am
I've received mine... seem a decent improvement over the previous. Space for a fan, iec connector, ground attached to the gnd of the output at the psu.
The psu is missing ycap and primary side of psu totally floating. Edit: there is an ycap between negative after the rectifier bridge and ground. On the input there is a little isolation transformer.
The output is above +/-15.5v, with 16v rated caps. Seem ideal to place an LDO.
The XO is 10mhz, and is easy to find a TCXO with lower 1ppm.
As usual space for better opamps instead of the 3002 parts.
There is also the space and hole for putting a cooler above the LDO.
I think that with 2 LDO at the output the smps ripple can be totally eliminated. Remain the emi created by the smps.
In any case not seem as bad as the other psu that i have of the fy3200
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: AlMuz on March 19, 2020, 05:58:48 pm
Here is my mod of FY6900 with linear power supply having total TDP around 4W.

In terms of TDP to design fully linear power supply for this device (without any DC-to-DC switching converters, like done by SDG Electronics) it is hard to go with a single transformer that has single output.

The requirements for analog output circuitry is bipolar +/- 13.5V producing solid 250mA (that is if you connect outputs to a normal 50 Ohm terminated load).
If you want short-circuit both outputs - you need at least 0.5A. Both outputs have 50 Ohm in series, so in worst-case scenario when you short-circuit them to the ground at peak +/-12V output voltage the either of supply rails will be looking into the load of two parallel 50 Ohm resistors (so that is 25 Ohm). This results in 480 mA max current consumption (disregarding other losses in output circuitry of FY6900 to power OpAmps, LDOs etc).

So bipolar supply with max 0.5A on each rail is more than enough for normal use.
On eBay I found a perfectly fitting toroid transformer for $25 shipped, producing 26V RMS with center tap at 0.76A (20VA).
That means at max load will feed 13VAC RMS at 0.76A to power each rail.

[attachimg=10]

In normal use of FY6900 (meaning both outputs conected to 50 Ohm terminated loads, so 250mA total) the output RMS of this transformer is around 18V (between center-tap wire and either of two "power rail" wires).

The LM317/LM337 module from eBay ($10 assembled and shipped) produces almost no-heat (radiators barely warm).

[attachimg=12]

Most heat (around 0.5W) is dissipated by 1V drop on each diode in rectifying bridge, so that leaves 17V of DC with some ripple after capacitor to LM317/LM337.
The output voltage of LDOs should be configured at 13.5V, so that is perfect 2.5V voltage drop close to the spec of LM317/LM337.
So total TDP of LM317/LM337 module is at most 2W spread on three componnents (full-bridge rectifier and 2 LDOs with radiators).

I was hoping that the remaining power of this transformer will be enough to get additional +5V rail to power digital circuitry of FY6900.
Connecting another LDO to +13.5V rail produced a lot of heat. That is because digital part (FPGA + LCD) consumes around half an amp (530mA in my case).
(13.5V - 5V)x0.5A = 4.25W TDP reuquires an LDO module with larger radiator which barely fits inside remaining space of FY6900.

But the worst part was that digital side sucking 0.5A brings positive "rail" of transformer output down to its nominal voltage (of 13VAC RMS).
That brought the voltage at the input of LM317 to be too low (no overhead room for required drop to provide regulation).
So the positive output rail of 13.5V started sagging (at 50 Ohm load on both outputs) passing through some ripple left after full-bridge rectifier and smoothing capacitor.
The FY6900 could not output perfect sine wave with 24V peak-to-peak swing, positive half-wave was distorted. To be said - even at 16V peak-to-peak output the sine wave was distorted.

I've tried to replace an 5V LDO with a decent switching DC-to-DC module, hoping that instead of heat produced by LDO that voltage-drop energy will be converted into more current for 5V rail. The situation improved a lot, got perfect sine at 20V peak-to-peak, but 24V was still distorted.

Started thing about should I go and look for another transformer, more powerful one. Or the one that maybe has two outputs - one with center-tap to create bipolar +/-13.5V and another set of output wires to create for +5V rail. Another option was find one more tiny transformer for 5V specifically.

It was easier to find one more small transformer to power +5V rail specifically.
6VAC RMS 1A for $16 from eBay:

[attachimg=13]

Also got EMI filter for $10. Did not do any comparison tests on how it improves the situation, but "if it fits - let it sits":

[attachimg=1]

A cheap $2 LM317 module from eBay did not fit well with this smaller transformer:

[attachimg=2]

For peace of mind I've put a requirement of 1A output on +5V rail (600mA for digital components of FY6900 and some 200...400mA leftover for cooling fan).

LM317  by its spec requires 3V drop to provide regulation. At 1A of load the transformer output RMS gets down to 6V, voltage drop after full bridge rectifier leaves almost nothing for a linear regulator to deal with:

[attachimg=3]


At 0.5A of load  (so nothing left for cooling fan) this module still produced considerable ripple on its output:

[attachimg=4]

So, decided to make my-own LDO module:

The situation became much better (at 1A load):

[attachimg=5]

Both transformers with EMI-filter left no space to fit LDO modules. So LDO boards were mounted to the top surface (upside-down), hanging on top of main FY6900 board.
Also painted plastic case with MG Chemicals Nickel infused conductive coating to reduce EMI from outside.

[attachimg=6]
[attachimg=7]
[attachimg=8]

Here is output before (square wave at 0.0000V amplitude, sorry did not make this one as a normal screenshot from the scope):
[attachimg=11]

And after:
[attachimg=9]
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on March 19, 2020, 11:54:10 pm
Doh! Logic part consumes that much? I'm using a 2x15vac 20va transformer, and almost done a 317+337 + small 5v buck. So i'm out of luck and i need also a bigger transformer (or a second transformer) like you.
Sorry, but what is the purpose of the opamp in the 317/337 board?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on March 20, 2020, 06:01:52 am
@AIMuz, if those last two 'scope images are referencing a before you replaced the original SMPSU board with an after you'd installed your replacement analogue PSU, there seems to be very little improvement. However, when you turn the level down to less than 501mV p-p (plus or minus 250mV on the "DC Waveform" setting), you need to keep in mind that the output from the generator's first stage opamp is routed via a 20dBish attenuator (possibly still with a Z0 of 85 ohms as per the 6600 and 6800 models) which will reduce any PSU noise and ripple to a tenth of the voltage you'd otherwise see for voltage settings greater than 5.001V p-p.

[EDIT 2020-03-31 Definitely the same 85 ohm attenuator! See https://youtu.be/kA6uxUDg55M?t=366 for proof!]

 You should be testing using the "DC Waveform" setting at voltage levels in excess of +/-250mV to prevent the attenuator being switched into the circuit (and above the +/- 2.500v setting if you want to examine the effect of the TH3002i +12db boost amplifier on the psu noise level). That avoids any 'leak-through' of whatever waveform you've set it to output (in this case, it appears to be a 1KHz squarewave) making it easier to identify the psu originated noise components that are polluting the signal generator's outputs.

 I presume you're using good quality RG58CU patch cables to link the output to the 'scope's input and have them properly terminated. One thing to watch out for when testing with the "DC Waveform" at the higher voltage levels is to avoid overheating the terminating resistors (6Vdc - half of the 12v is lost in the 50 ohm output resistors in this case -  represents some 720mW of dissipation in the termination resistance load which just might be more than what they're rated to handle for any extended period).

 Apropos of this, you miscalculated a little on the worst possible case scenario loading on the +/- 13.5v rails which comes not only from the need to supply an extra 25% to the 1st stage opamps which drive the final stage opamps along with some additional 'vampire loading' allowance (somewhere in the region of another 50mA on each rail at a best guestimate) but also the fact that when you set both channels to output the maximum 12v amplitude of the "DC Waveform" at the same polarity (either both -12 or +12 volts simultaneously into 50 ohm loads), one or the other 13.5 volt rail will then need to supply some 350mA or so (the 50 ohm loading reduces the output voltage to 6 volts - it's only 12v for hi-Z loads (I have to keep reminding myself every time I'm trying to calculate the worst case abuse of the +/- 12v rails - this bites me almost every time I try to calculate this  >:( )).

 If you really want to drive into short circuits indefinitely, you'll need to supply an additional 240mA making the total, absolute worst case demand some 590mA, say 600mA to be on the safe side (though not so safe for that beleaguered THS3002i (or a pair of THS3491 / 3095 / 3091 opamps if that upgrade mod has been applied)).

 It's only when you're outputting repetitive waveforms that the 13.5 rails get to share the loading at an average of half of this worst case demand. Even so, each rail may suffer transient overloads with very low frequency waveforms (say 120Hz or lower). Maximum voltage square waves being the most stressful on the PSU at any frequency up to the 20MHz limit before the  limit is reduced to a mere 5V p-p thereafter (the 24V p-p limit is reduced to the 20V p-p limit at the 5MHz threshold ISTR).

 Can you retest using the "DC Waveform" option at above the 250mV threshold to switch the attenuator out of the circuit? I'm sure you'll get a different picture. I certainly did when I ran those tests on my FY6600 and it wasn't a pretty sight when I upped the voltage above that 250mV limit. :( I'm still using the original, if modified, smpsu board so the 80 to 95MHz 3mV ripple on top of the other psu noise wasn't entirely unexpected - just a disappointment to see it breaking through onto the outputs like this.

 I suspect that at this frequency, this is most likely to be directly radiated RFI leaking into the main PCB rather than ripple on the 12v rails getting through all the filtering and LDOs onto the internal voltage rails (not that any of the LDOs will be able to block such ripple passing straight through them to any meaningful extent at these high frequencies).

 I have my own thoughts on upgrading to a less noisesome psu. Essentially a similar setup to yours but without the analogue voltage regulators. I'll be using a 15 to 20VA R transformer with two separate 15v secondaries (I'll have to float a second 13v output positive buck converter so I can use it for the negative rail (inverting output buck converters are not only expensive (and less efficient) but as rare as unicorn droppings on Ebay and the like).

 The switching noise of a small buck converter or three is a lot easier to deal with than that which blasts out of an unshielded mains voltage smpsu as I discovered when I chose to use a 7805 sized 1.3A 24 to 5v (with higher output voltage settings available) dc-dc buck converter in my my homebrewed GPSDO rather than an actual 7805 to drop the incoming 9 or 12 v wallwart supply down to the required 5 volts.

 However, before I test the depth of the psu modification waters with both feet, I'm going to try the effect of using battery power (a 12v SLA for the +12v rail with a 7805 off of that for the +5v rail with a pair of 6v lantern batteries for the negative rail). That'll dispose of the psu noise source and verify that a quiet psu replacement will actually rid the generator of this presumed source of noise and give me a benchmark to compare against whatever design of PSU I ultimately cook up (I hate 'flying blind' with this sort of project).

 I've had the lantern batteries for several months now - I just haven't got a round tuit since I've kept myself occupied with other projects (that GPSDO for one, and the addition of a 10MHz reference input socket with frequency injection locking module to the FY6600 for the other).

 Since those projects have now finally been completed, I may actually pull my finger out and run that battery power test in the next few days, assuming I don't manage to find yet another project to keep me from this laudable task. The main obstacle is the lack of a suitable 6 pin connector to reduce the risk of damage from operator error. The alternative would be to solder flylead wires onto the psu's output pins (the rectifier diodes conveniently eliminate the back-feed risk) which I can connect to a switching control circuit to connect/disconnect the battery power to all three rails simultaneously (something that's required to play it safe regardless of how it's connected anyway - or maybe not; see my 'train of thought' comments below).

 Testing with battery power might, on the face of it, seem a simple enough task but it could prove a little more complicated than just connecting the batteries one by one, assuming the sequence is of no importance when it might well be critical. In this case, discretion is the better part of valour - I'd rather be safe than sorry, especially after all the hard work I've put into turning this sow's ear into something resembling, if not a silk purse, then at least a rayon facsimile of such.

 I'd like to replace the psu board with something a lot less noisy before I finally restore the case fixing screws to their rightful place - they've been kept aside in a safe place for just over a year now. ::) I'd just  like to confirm in my mind that the existing psu board is not masking out another source of noise that simply can't be eliminated before embarking on what could land up being a folly of a project if that proves to be the case.

 You can't get any quieter than battery power (and a 7805 for the 5 volt rail) so it's the ideal way to test for any other hidden noise sources that may yet defeat the whole purpose of such a project. I'd prefer to know exactly where this will end up rather than proceed on blind faith alone.

 As regards the business of applying battery power to all three rails simultaneously, it's just occurred to me that I could run it up on the mains psu, connect the 12v batteries in parallel to the psu rails via the soldered on flyleads and connect the 5v regulator via a Schottky rectifier diode and then shut off off the mains power to make a smooth transition to battery power for the few minutes required to test the noise levels on the output before reversing this procedure to go back to mains power before safely shutting it down.

 The only extra complication in my case being the OCXO's independent 12v mains smpsu which has an unswitched connection to the C6 mains socket. Fortunately, for this test, the regulation of this 12 volt supply won't be critical so I can just use a couple of 1N400x diodes in series from the 12v SLA battery to avoid any backfeed issues whilst getting it all set up (I'll just have to unplug the whole generator from the wall outlet to cut the mains power rather than just using the rear panel switch in order to transition it to battery power). I may have a result sooner rather than later, in which case, I'll post a report to both this and the FY6600 topic threads.

 This "train of thought" portion also includes some "train of action" involving recording screen captures by way of a "Before" record to eventually compare against my franken PSU (a chimera that will be made up of a conventional analogue mains transformer with rectifiers and BFO capacitor smoothing, feeding a bunch of dc-dc converters).

 I've attached all 20 screen captures, including the very first test one made after being forced to power cycle reboot the 'scope (a Siglent SDS1202X-E, btw - yours appears to be either the 1204 or the 1104 model going by the image you apologized for - no need for any apology).

 This was the first time ever in over a year that I've managed to crash the 'scope so thoroughly that only a power cycle reset could fix it. I'd plugged my usb thumb drive in about an hour earlier (I'd had to nip out on an errand) and it was only when I pressed the 'Print' button that everything froze up. The next four images led to my experiencing a minor epiphany which, if you care to take a look right now before reading any further, will put the observant 'way ahead' of me in regard of the cause of this event...

====SPOILER SPACE====






=====================

 I was expanding the X axis out in search of the 40 to 70 KHz switching ripple artefacts before it occurred to me that the 10MHz was an improbable switching artefact (not that such fixed and stable frequencies, even up to 20MHz, aren't uncommon in custom high grade switching regulators/dc-dc converters for use in high grade T&M kit) before the penny dropped.

 I'd been putting a half volt p-p 10MHz Sinc pulse out on CH1 before I'd set up the 0.3v DC test signal on CH2 and forgot to turn it off to avoid unwanted crosstalk. Once I'd belatedly turned CH1 off, the picture became a lot clearer as you can see from the following sequence of screen captures.

 Using scope traces to analyse switching noise in mains voltage smpsus (particularly the universal voltage kind) is a far from ideal method but if you don't happen to have a spectrum analyser to hand, then at least it offers a way to get some insight into the nature of the problem (it does rather better when looking at dc-dc converters that run at a fixed switching frequency once loaded up sufficiently to exit their voltage maintaining 'hiccup mode' - hint: don't waste time examining this type for noise and ripple when they're in hiccup mode through insufficient loading).

 You'll have noticed my switching between the 20MHz and full BW options to demonstrate the huge difference in results. The 20MHz 'standard' for noise measurement 'scope traces originated back in the days of analogue PSUs and the rarity of lab grade 'scopes that actually had wider bandwidths. These days, with high frequency kit powered from an smpsu, that 20MHz standard has become somewhat obsoleted. You really aught to be doing these tests on the full bandwidth setting if you don't want the true nature of smpsu switching noise hidden by an artificially imposed 'modesty filter'.

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on March 20, 2020, 03:17:48 pm
I have a 20Mhz fy6900, just put a fan in your space, and a heatsink in the fgpa, if I made all the modifications that other users make, it would be convenient to buy a siglent or rigol, here in Argentina it is too expensive to assemble a good source. Also for my hobby is (for now) excellent.

in spnish
yo poseo un fy6900 20Mhz, solo le coloque un ventilador un su espacio, y un disipador en el fgpa, si le hiciera todas las modificaciones que le hacen otros usuarios, me convendria comprar un siglent o rigol, aca en Argentina es demasiado caro armar una buena fuente. Ademas para mi hobby anda (por ahora) excelente.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: AlMuz on March 21, 2020, 07:55:24 am
Sorry, but what is the purpose of the opamp in the 317/337 board?

Had the same question when I've got this module in mail.
The double opamp sits in a feedback of adjustment pins for LM317/337.
Looks like some improvement over basic LDO schematic with resistor divider, but not sure what exactly (better ripple rejection?):
[attachimg=1]
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: AlMuz on March 21, 2020, 09:04:38 am
@JBG


I am not sure if your 2-channel scope supports this feature, but I have mine connected to home Ethernet and really enjoy its embedded web-browser interface (scope hosts a web-server): https://youtu.be/Cxh_Liay09E?t=161 (https://youtu.be/Cxh_Liay09E?t=161)
No hassle with USB sticks.


Thank you for the notes on FY6900 output scaling. That indeed expected and it is my fault I did not think of that during my initial tests.

Assessing noise characteristics by signal oscillogramms is a bit tricky and unrewarding, but what else can we do without having an access to a decent spectrum analyzer?  I know there is an FFT option inside our scopes, but its precision is not right where I wish it to be.

Looking onto noise oscillograms at nanosecond scale can be deceiving. Oscilloscope trigger might be hitting tiny sub-section of signal that has noise components of much lower frequencies but much higher amplitude. And you wont see that unless you zoom out timescale. So I decided to stick with millisecond scale to cover broader spectrum when making these screen shots.

But first - establish the baseline!

Here is the scope output with no probes connected at predefined settings (2ms time scale, 1mV resolution):
[attachimg=12]

Here if I attach the regular 300MHz probes and shield their tips (but not short to the ground):
[attachimg=13]

Coaxial cables are not ideal, and some of them more susceptible to EMI than others.
Here is with setup of regular BNC-coax on one input and RF-coax RG316 on another, both 50Ohm terminated at the scope inputs.
Having other ends wrapped in foil they still catch a lot of EMI (my scope SDS1104X-E was fully hacked, so bandwidth goes into 300MHz, RG316 is upper signal and regular BNC-coax which comes with FY6900 is lower):
[attachimg=8]
[attachimg=9]

Here is what I get if I connect other ends of two coaxes to the inputs of FY6900:
[attachimg=10]
[attachimg=11]

Coax type makes a lot of difference!

RG316 looks cleaner, but that might be not because of it is of higher quality or better shielding.
But rather higher capacitance due to its smaller diameter, so that works like low-pass filter.


So, to mitigate effect of the cable characteristics and its EMI susceptibility (if any) I've decided to switch the scope into 20MHz bandwidth:
[attachimg=14]
[attachimg=15]

Now they become more or less equal. So that we can now focus on FY6900 output than on test setup.
RG316 was replaced with another RG58/59 BNC-coax similar to one which came in a box of FY6900.
First check with DC 0V, as expected, nothing new. Basically the same I've posted earlier.
[attachimg=1]

And here is at 1V (somewhere after first relay click):
[attachimg=2]

Beyond second relay click, 5V:
[attachimg=3]

And at 10V, big OH SH!T, I see 120Hz mains coming through:
[attachimg=5]

My PSU calculations apparently were way too optimistic.
20VA feeding two channels of two 50Ohm-terminated loads leaves no more headroom for voltage regulators.

Here is more prominent at 11V:
[attachimg=6]

Negative reail is even worse, problems start at -9V with some strange curves:
[attachimg=4]

Very terrible -12V:
[attachimg=7]

It is unlikely I will ever need such DC offsets in my real projects, so I guess I will leave it as is.
I really wanna see similar picture of 5V DC with original supply, but not willing to disassemble my FY6900 just to "check it out"

@Johny B Good or anyone:
Can you please measure and post the same screenshot of coax connected and 50 Ohm-terminated scope with 2ms/div horizontal and 10mV/div vertical resolution setting?

Thanks,
Alex
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on March 21, 2020, 01:18:14 pm

Had the same question when I've got this module in mail.
The double opamp sits in a feedback of adjustment pins for LM317/337.
Looks like some improvement over basic LDO schematic with resistor divider, but not sure what exactly (better ripple rejection?):
Seem configured as active lowpass filter. Maybe for have a more stable reference at adjust pin?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on March 22, 2020, 09:01:16 pm
@AIMuz,

 Thanks for the speedy response considering the mass of screenshots you'd probably had to peruse in some detail. In hindsight, I realise it would have been better for all concerned if I had actually been a little more selective over which screenshots to attach to my reply. Usually, the limiting factor is in the total file size but, in this case, the whole collection was less than a MB's worth which wasn't the best criteria in choosing what to send. Apologies for the screenshot overload.  :-[

 The output scaling is easy to overlook, especially if you're unfamiliar with the basic circuit layout as I had been prior to downloading DerKammi's reverse engineered circuits, some 12 months ago now, for the FY6600 which he'd posted to github for the benefit of the members contributing to the FY6600 topic thread.

 Sadly for me, the 1202X-E doesn't have that web server facility built in. A later firmware update might add this feature (I think I've applied two updates so far and I don't think there has been another one since).

 Your comments regarding trying to assess noise characteristics are ever so true.  :( The built in FFT SA feature is limited by the use of an 8 bit ADC but using the ENOB option might improve the limited dynamic range (I haven't tested whether this is actually compatible with the FFT function yet).

 I started using it just after I posted all those 'scope traces and with some experimentation with the settings and winding the  timebase down to 20μs per division, along with an averaging factor of 16, I eventually got a decent looking spectrum covering the 0 to 100MHz range. I'll attach a couple of screenshots (the first with the generator switched off, leaving only the OCXO powered up, with the second showing the noise spectrum when turned on at a 0.3v DC output setting). You can be the judge of the usefulness of my FFT settings, which to me, seem to be the best I've ever managed to to set it up to so far.

 Even after getting the FFT settings optimised, I was still seeing inexplicable spectra which led me, belatedly, to look for a baseline.  :-[  In the process, I discovered that one of my BNC dummy loads (the first one I happened to pick out of the tray) was acting like an antenna - it actually raised the baseline noise spectrum above that from an empty BNC socket contrary to my expectation of seeing a slight reduction from the 50 ohm input loading.

 The rest of my dummy loads however, were free of this 'antenna effect' so it seems to have been just a weirdly faulty dummy load (testing the resistance with a DMM shows the expected 50 ohm resistance value (51 actually but all the others showed readings in the range of 50.4 to 50.8 ohms so, allowing for the test lead resistance, within a 1% tolerance range). I've put that weirdly broken dummy load to one side for a later more detailed examination.

 Apropos of the quality of BNC patch cables, I've also discovered some serious problems. The half metre BNC to BNC cable supplied with the FY6600 is no shining example and, what's worse, the BNC plugs on my collection of 3 metre 'Cheapernet(tm)' patch cables are out of spec on the outer barrel dimensions, making them a little on the iffy side in regard of getting a good contact with the ground return on most sockets I plug them into. However, with a bit of adjustment on 'The Angle of Dangle', they're still an improvement over that supplied patch cable.

 The actual cable quality might be ok (I'll have to chop the plugs off one to check - no great loss in this case). I've got a small collection of good quality BNC plugs I can use as replacements if the quality of the cable proves good. I guess even just over 20 years ago, the quality of Chinese manufactured patch cables was even worse than it is today.  ::)

 Not being sure about how much noise the little 12v half amp smpsu board that powers the OCXO module might be contributing, I landed up pulling the plug to completely isolate it from the mains supply. When I was still seeing interference artefacts in the FFT display, I landed up disconnecting the 9999 counts DMM I use to monitor the OCXO's tuning voltage from my homebrewed GPSDO along with the BNC patch cable plugged into the 10MHz output socket.

 This merely reduced the level of 10MHz spaced spurs rather than totally eliminate them so I pulled the plug on that as well which only gave a slight further reduction. In the end, I unplugged the mains cable from the C6 socket on the signal generator, leaving the connection to the 'scope as the generator's one and only connection to the outside world. Even in this state, I was still seeing noise that only reduced by unplugging it off the end of the scope connecting cable which then only completely disappeared once I'd unplugged that from the 'scope's CH1 input socket.

 It seems that the plastic case of the FY6600 makes a very lousy shield, leaving the circuitry inside exposed to external interference. I plan on taking it and the 'scope (plugged into a long mains extension cable) outside, weather permitting, to repeat this test outside of what I suspect is a very polluted electromagnetic environment. It could turn out that a "Noisy PSU" may prove the least of this signal generator's woes although I rather doubt that eliminating this noise source won't at least offer a significant improvement.

 If this proposed "Outdoors Test" demonstrates a significant (unpowered state) noise reduction, I'll have to run my battery power tests outdoors too if I want to collect any meaningful test data. It might seem to involve some effort just to get a baseline but I'd rather know the score before upgrading the PSU in the blind hope that I'll get a tangible improvement rather than discover that I've actually made things worse (or at least no better) for all my trouble.

 Regarding what you said about setting too fast a timebase to see the slower yet higher amplitude mains frequency related ripple component is ever so true. It's a problem I became all too painfully aware of about a year ago when I first started trying to diagnose PSU noise and ripple from waveform traces alone. This sort of investigation is where the services of a half decent spectrum analyser comes into its own. If the use of ENOB is compatible with the FFT SA function on these DSOs, it might just provide a poor man's version of a half decent SA. I'll do some testing later today (it's now 04:27 UTC this Sunday morning right now).

 Picking up on the points you raised over the BNC patch cables, your hypothesis in regard of the RG316 having a higher capacitance per metre due to it being thinner than RG58 doesn't apply. Being 50 ohm cables they will both show close to 100pF per metre (if you have an LC meter, you can test this quite easily). Although the conductor diameter does have some effect on its per unit length inductance, at this scale of physical dimensions seen with typical co-axial cables, it's an order or three less in magnitude (I wasn't able to find any figures in the literature on this aspect of co-axial cable properties - it's just a gut feeling) compared to the changes in capacitance per unit length that result from altering the diameters ratio and dielectric permitivity.

 Since the impedance of co-axial cable depends on the ratio of L (which only changes slightly) and C which can be radically altered by the conductor diameter ratio, the measured capacitance for any diameter of 50 ohm cable remains very close to the 100pF per metre I've measured with various sizes of cable. Obviously, the capacitance value is lower for 75 and lower still for 93 ohm cables. I don't know the figures off the top of my head but comparing the capacitance (using an LC meter or DMM with a capacitance measuring feature) against length offers a convenient way to quickly ascertain an unknown (dirt cheap) cable's nominal impedance.

 In this case when using a dummy load matched to the cable's impedance, you're using it as a transmission line and the LPF effect simply doesn't exist (other than for the unfortunate effect of the 15 to 20pF loading on the scope's input in the 100MHz and beyond range when it has no built in 50 ohm termination option and you're obliged to use an external in-line terminator). The lower noise level using the RG316 cable will simply be on account of its much better quality in regard of screening over that of the cheap cable that was used in the manufacture of that half metre BNC patch cable supplied with the signal generator.

 All this discussion of patch cable quality (lack of in my case) has made me realise that I urgently need to upgrade my collection of test cables one way or another. I'll probably land up assembling my own set of patch cables unless I can track down a source of reasonably priced ready made patch cables of acceptable build quality which, these days, is easier said than done.  :(

 The following attached screenshots include the requested traces (but on the 500μV per division setting needed to raise a usable trace in my case) as well as the FFT plots I mentioned above.

 The first two traces after the FFT images were captured with nothing plugged in and then with only a dummy load (I can't recall which way round they were captured - since there's no perceptible difference, the distinction seems rather academic). The fifth shows the Cheapernet(tm) 3 metre patch lead unterminated with the far end not plugged into anything whilst the sixth is terminated at the scope end. In both cases, the cable is simply coiled up on the test bench. The triggering source was CH1.

 For the last four captures displaying the results of using the supplied half metre patch cable, I decided to use the AC line triggering option (hence the hardware frequency counter readings of 49Hz in the top right corner - obviously limited to truncating to the nearest whole Hz). In this case, this short cable was simply laid out on the bench in a straight line.

 The first of this final sequence depicts an unterminated cable and I was obliged to reduce the Y axis sensitivity to 1mV per division for this capture. Grabbing the middle of the cable increased the amplitude by some 2 to 3 dB, confirming the abysmal quality of the cable itself. Holding onto the BNC plug at the far end reduced the level. The source of the external interference - the induced 50Hz voltage that my body was picking up - was being shunted to ground via this contact so no great surprise here.

 The second image shows the result of connecting a 50 ohm terminator at the scope end of the cable, the third image shows the result of transferring the terminating load to the far end (scope end unterminated) and the fourth image shows the result when both ends are terminated. As before, I was once more obliged to switch back to the 500μV per division sensitivity setting for these last three screen grabs.

 There was no discernible difference between the final three screen captures, confirming that the ingress of the 50Hz interference was due to incomplete coverage by the screening braid, allowing the E field component to leak through and induce a voltage onto the Hi Z input (1M ohm with circa 18pF shunt capacitance) when unterminated. Connecting a single 50 ohm terminator at either end was more than sufficient to attenuate it well below the 'scope's input noise level. Terminating both ends would be just "Gilding the Lilly" as far as this source of interference is concerned.

 It's clear from these results that my Cheapernet patch cables could prove to be worthy of a connector upgrade. I've got enough BNC plugs to upgrade three patch cables at a pinch, two of which are of the screw onto the cable type (one with spring type centre pin socket making it solderless, the other needing the centre pin contact to be soldered for best reliability of this connection), the other four being the more conventional braid clamp and soldered centre pin "Burndept" style.

 I've just replaced the bad plug on the cheapernet(tm) patch cable I'd been using with the solderless screw on plug and it seems to be quite acceptable (the outer screen proved to be mylar foil overlaid with a tinned copper braid with the centre wire being stranded tinned copper). I'll check out the other five patch cables. They might not all be as bad as the one I've just repaired and some, if not all, of the bad ones might only require replacement of a single plug to effect a repair. My patch lead situation may not be quite so dire as it first seemed. I guess you could include verifying your cables as a vital part of establishing your "baseline". The refurbished patch cable hasn't altered the original spectra I'd previously collected so I guess I must have got the "Angle of Dangle" just right on the earlier runs.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on March 23, 2020, 04:32:24 am
Hello all,

 I've been experimenting with my SDS1202X-E's FFT function beyond those noise spectra plots I'd taken of my FY6600's DC waveform at 0.3V output setting. This time, I've used the FFT function to examine a 10MHz sine wave at 1V rms (a p-p voltage setting of 5.9V to get the peak of the 10MHz lined up to the 0dBV mark in the FFT graph.

 Rather gratifyingly, the resulting plot looks just like the classic response you typically see for a single tone carrier wave, complete with sideband noise pedestal. It seems the FFT function, if you have the patience to wait for it to average 16 scans at a timebase speed of 10μs per division or slower, is a half decent "Poor Man's SA" after all. It might even be possible to improve the quality further if the 'scope allows for the use of the ENOB feature with the FFT function. I haven't tested this yet (I have a sneaking suspicion that the FFT function will preclude the use of the ENOB feature).

 My first attempts at setting the correct levels to produce a zero dBV had resulted in a carrier wave at -6dBV in the FFT plot and it was only after turning the "Measure" feature on that I realised I'd overlooked the need to account for the voltage halving effect when driving 50 ohm loads when calculating the p-p voltage setting required to translate the 1.414 peak amplitude of a 1 volt rms sine wave up to 2.828 volts. I'd already applied a twofold increase, forgetting the need to double up yet again when driving the 50 ohm loading at the 'scope end of the cable. :palm:

 Anyway, I've attached two FFT plots so you can judge for yourself the efficacy of the Siglent 1000 series' built in FFT function's ability to produce meaningful spectral data. The response curve for the 10MHz sine wave disappears off the top of the plot by 20dB on account of my having to set the reference to -20dBV to bring the noise floor into view.

 I could go into further detail but I think this truly is a case where "A picture is worth a thousand words." so I'll leave it at that and let the pictures speak for themselves.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on March 26, 2020, 02:15:20 am
 Following on from reply (#236) where I mentioned patch cable issues, the discovery of my unpowered FY6600 generating noise and the need to test outside of a noisy environment, favourable weather permitting, well, the long overdue 'favourable weather' finally materialised here in the UK this Tuesday the very next day!

 The afternoon temperatures rose to the giddy heights of 17 to 18 deg C for the first time in over 5 months, motivating a foray into our garage to dig out the patio and garden furniture which proved rather handy as far as my 'outdoors testing endeavour' was concerned. As a result, I managed to gather ample data, proving my hypothesis that my FY6600 was as rainproof as a colander in a rainstorm as far as keeping out the EM interference that my hobby room seems to be awash with.

 I've descriptively renamed the screen captures to keep the verbiage toned down to a minimum. The first seven images are from the outdoors test, the next four attempt to demonstrate the effect of loading the +12 rail with some 250 to 400mA or so of loading on the smpsu ripple voltage artefacts in the FFT scans, the next two are baseline noise floor scans of the DSO to determine the origin of the -75dBV at the extreme LHS every FFT plot (it seems to be just a plotting display artefact - you can just detect the 50Hz peak which disappears completely when the input is terminated).

 The last 14 images (blast EEVBlog's 25 attachment limit! - it's just 12, the last two will be attached to a second post) show the effect on the noise floor of the FY6600's use of the 12dB boost amp and the attenuator as you select each of three output voltage ranges with examples of the effect this has on a 10MHz sine wave over a range of level settings from a low of just 5mV p-p right up to the maximum of 20V p-p (unloaded Hi-Z voltages - the voltage is halved when driving 50 ohm loads).

 The problem with my patch cables seems to be a combination of dimensional tolerances stretched to the extreme opposite limits between the BNC connectors on the patch cables and the slightly just too undersized barrel diameters of the sockets used by Feeltech. More than likely, the main culprit is Feeltech rather than those patch cables. I might be able to bodge a work around by squeezing the sockets into a slightly oval shape. The only worry is that I might damage them or just make things worse. Has anybody tried this bodge with any success?

 For anyone thinking of following along, keep in mind that I've modified the 85 ohm attenuator pad used in the 6600 and 6800 models (and possibly in the latest 6900 one as well, I can't recall whether this question was ever answered let alone what the answer may have been).

 I'd been attempting to convert it to a 50 ohm pad matching the actual Hi-Z voltage attenuation Feeltech had corrected for in the firmware but the best I could manage was a 45 ohm pad matching the required attenuation. It had been such a brain bursting exercise trying to calculate the actual voltage attenuation of this whacky oddball 85 ohm attenuator pad that I gave up trying to fine tune it any further until I'd managed to recover from all the effort I'd expended in getting it this good (45 ohm is, at least, some improvement over the 85 ohm monstrosity Feeltech had created so taking some rest on my laurels seemed justified).

 I can always have another go at cracking this problem any time I feel I'm up for yet another round of busting my brain. Anyhow, the point is that you'll get slightly different results from mine at settings below the 500mV p-p threshold (or the equivalent DC voltage settings within the range of +/-250mV)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on March 26, 2020, 02:17:36 am
 Here are the last two image files EEVBlog prevented me from including on account of their 25 file attachment limit.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on March 31, 2020, 04:26:29 am
 In my previous post, regarding the effect of choosing dc voltage levels to avoid switching the attenuator into the output circuit, I pondered as to whether this attenuator network had been corrected from the 85 ohm pad used in the previous two models or not. Well, I came across incontrovertible evidence that this "Skoolboy Howler" remains uncorrected in the FY6900 when I chanced upon the following YT review video https://youtu.be/kA6uxUDg55M?t=366.

 That link takes you to the point in the video just before it pans to reveal the resistors identified as RS1 through to RS6 in between the relays just behind the output sockets which can be seen to be the same 100 and 510 ohm values used by its predecessors.

 It looks very like the original design brief had been to switch a 20dB (50 ohm) attenuator pad into the output for p-p voltage settings below the 500mV threshold and compensate in the firmware with a 20dB boost so as to improve the S/N ratio at the bottom end of the range. Somehow or other (with the FY6600 model at least - possibly an inheritance from an even earlier model), they'd cocked up the BoM for this attenuator network and used a firmware bodge as a quick 'n' dirty fix to save having to re-work the boards. They've obviously chosen to correct for the unterminated Hi-Z case (such a quick 'n' dirty fix won't work for both cases) and hope no one would get wise to their kludge.

===========================================================================================
[EDIT 2020-08-15]

 In hindsight, there was never any "Clever firmware kludge". F***tech had simply picked the cheapest resistor values to make up a divide by 10 (20dB) voltage attenuator that would stand in for the original 50 ohm 20dB  with Hi-Z loadings and let those working with 50 ohm transmission lines and loads go to Hell. You just need to replace the 510R with 249R and the 100Rs with 61.2Rs to restore the intended by design 50 ohm 20dB attenuator pad. The choice of those resistor values had never ever been a "Skoolboy Howler", just one made to satisfy the insanely stupid cost cutting demands at any price by their Bean Counter in Chief. I wonder what the savings would have been using half a dozen 125mW rated E192 0.5% resistors over the cheaper E24 types they actually used?

 For such a cheap function generator, this could be excused as a temporary solution until the next generation, the FY6800 in this case, could provide a golden opportunity to correct this mistake. However, since they were aware of this issue (they had to be in order to apply a firmware fix), ignoring this opportunity becomes completely inexcusable and since they also carried on perpetrating this error into their next 'golden opportunity' with the FY6900 to put things right, one has to assume the design/production "team" at FeelTech are just a bunch of retards going all out to destroy what little credibility that may remain of their employer's reputation.
===========================================================================================

 Of course, since this is so obviously targeting the cash strapped hobbyist market demographic, it's not inconceivable that the designers may have deliberately planted all these errors and omissions not only to save costs but also to provide "Easter Egg" like challenges to their target demographic for them to test their expanding electronics knowledge upon.

 I've offered this theory before in the FY6600 thread which was regarded then as being a rather too fanciful explanation for all of these readily avoided defects. Now however, with the earth loop fiasco and attenuator nonsense (and other deficiencies) still being carried through to the FY6900, this theory (which originally started out as a "Joke") starts looking ever less fanciful.

 TBH, I suspect the truth of the matter is somewhere in between. The designer(s) probably reported the E&Os to production who went, cap in hand, to management who probably then said something along the lines of, "Sorry, at the price we're selling these things, we simply can't afford the expense - besides which, we're pretty sure our target demographic will be more inclined to have a go at fixing these minor issues in view of its low price point and the cost of shipping it back, thereby ensuring voided warranties. Leave it be and see how it goes before we splash the cash remedying what may prove to be a non-existent problem.".

 I know it might be hard to believe but I think the EEVBlog membership forms only a tiny fraction of Feeltech's customer base so that imagined scenario might not be quite so far from the truth as you might think. The apparent influence the FY6600 topic thread had on Feeltech's rethinking the use of the more expensive C14 socket over the original 'cheap as chips' C8 mains socket and 2 wire mains cord was probably more to do with highlighting the litigation risk for consequential ESD damage to DUTs due to this negligence.

 That mains socket upgrade was about as brutally pragmatic a solution as it could possibly have been with absolutely no thought for the consequences of introducing the deleterious effects of ground loop noise and mystery dc offset voltages. They couldn't have done less work in replacing the C8 with a C14 socket if they'd tried. The C14 and matching mains lead costs were unavoidable (and likely cheaper than the C6 based alternative). This knee jerk reaction to all the complaints about the ESD risk in the FY6600 thread speaks volumes about Feeltech's attitude to their customers.

 Mind you, having said all that, if I was in the market for my very first cheap function generator and wasn't already in possession of a FY6600, I'd certainly buy the FY6900-60M as a 'starter' generator. My FY6600 has been as much a project as a T&M tool so I don't regret any of the time and effort I've invested over the past 12 months or so in improving it beyond its original 'stock' condition.

 The one remaining question I'd like to answer however, is whether the smpsu board is as detrimental to this function generator's performance as almost everyone seems to imagine. I have my doubts but the only way to determine just how big of a problem this is, is simply to run it off battery power with only a 5v analogue regulator in the mix to power the logic rail.

 If the battery power test shows a tangible reduction of spurious noise and ripple, I'll  build a test PSU based on a conventional step down mains transformer to power dc-dc buck converters for comparison against analogue voltage regulators.

 I have a strong feeling that the noise and ripple from three small dc-dc converters will be far more manageable than that of the original smpsu board, hopefully to the point where the noise and ripple performance of analogue regulators will become so marginalised as to make them (and their heatsinks) totally redundant appendages.

 Whatever the outcome of this final psu testing project, my next function generator is going to be a model from a more upmarket manufacturer such as Siglent or one of their competitors. As much as I've enjoyed tinkering with and modifying the hell out of this toy function generator, there eventually comes a time to move onto bigger and better things.

 Once I've dealt with the psu issue one way or another, I'll have pretty well exhausted all of the possible enhancement opportunities so generously offered by FeelTech's FY6600, leaving me free to consider a possible more upmarket replacement at my leisure. I may well be able to manage quite nicely with the FY6600 for a little while longer yet before the need for something better forces me to fork out another wad of cash for a bigger and better function generator.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 01, 2020, 07:00:42 am
Someone can explain me, please, what is this problem of the 85 ohm pad? As i've not well understood it. Thanks!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 01, 2020, 09:06:48 pm
Someone can explain me, please, what is this problem of the 85 ohm pad? As i've not well understood it. Thanks!

 The short explanation is that it changes the output impedance of the function generator from the specified 50 ohm standard to a non-standard 85 ohm impedance at amplitude settings of 500mV p-p or less. The function generator otherwise behaves like all normal function generators at amplitude settings above this 500mV p-p threshold.

 This technique of switching an attenuator into the output of the primary amplifier stage to keep noise levels at bay for sub 50mV p-p settings is universally applied by all makes and brands of signal/function generators from the cheapest to the most expensive.

 The difference between Feeltech (God bless 'em) and every other make, is that every other make employs 50 ohm pads (typically 20dB or thereabouts) in order to maintain a consistent 50 ohm output impedance specification.

 BTW, if you're only using this to generate test signals at audio frequencies, this anomaly is usually of very little significance. It only becomes an issue when dealing with MHz frequencies where you have to start treating your interconnecting cables as the transmission lines that they are.

 Pondering the almost zero cost of using the correct resistor values to create a 20dB (or thereabouts) 50 ohm pad, I plugged the slightly misremembered values for this resistor network into the Pi attenuator calculator and was startled to see a 26dB 50 ohm pad result pop up! This led me to have another look at that YT video to check and was relieved to see the 100 and 510 ohm markings instead of the 56 and 510 values I'd plugged into the calculator. I guess the 56, rather than the actual 100 ohm value must have been a memory of previous 'test' values I'd used over six months ago when trying to calculate a solution to Feeltech's error.

 The best I had been able to manage back then had resulted in a 45 ohm pad with the appropriate unloaded attenuation to match Feeltech's firmware bodge solution. Even then, I had been relying on test values of the series pass element to trim the unloaded attenuation to exactly match the existing attenuator.

 Somehow or other, my initial calculations had been so far out, that this had resulted in a Zo of 45 ohms which no two recalculation attempts of the many I tried were ever able to resolve. In the end, I just gave up busting my brain against the problem and simply accepted that whilst a 45 ohm pad wasn't perfect, it was at least far better than the 85 ohm one it now replaces. I think that, six months on, I'm now sufficiently recovered to risk another go at solving this puzzle once and for all (fingers crossed).

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: bdunham7 on April 02, 2020, 08:20:39 pm
This isn't a criticism of anyone, especially all the Feeltech modifiers out there, but it does occur to me that the FY6600/6800/6900 are the most highly polished turds in history.  :-DD

Keep up the good work, guys!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 04, 2020, 12:06:29 am
Thanks Johnny B Good.... i still miss what is a "50ohm pad" but i've roughly understood the problem, that if i've well understood was fixed in the 6900.

Another thing, someone know what calibrate every trimmer onboard? In the fy2300 was easy as the circuit was much simpler. I see 3 of them per channel. On the 3200 there was the offset, zero adj and gain, i suspect that on the 6900 are the same...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 05, 2020, 10:37:53 am
 So, regarding this argument, i've discovered something.
If i set the waveform to dc, it uses the offeset circuit to output the signal.
So, setting the signal to square wave and dc 99.999%:

I know that 50ohm, must be the impedance and i'm measuring pure resistance, but it's normal?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 05, 2020, 11:05:52 am
Taking this schematic of the fy6600 as good also for the 6900:
[attach=1]
The output relays can do a lot of combinations, but i can hear them clicking only in the 3 ranges that i've listed. I suppose that the ths amplification takes place only with Vout > 5v, between 0.5 and 5 i have direct output from the opa, and under 0.5v enter the attenuation. But why in the > 5v range i not have the 50ohm output resistance?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: nctnico on April 05, 2020, 12:25:18 pm
So, regarding this argument, i've discovered something.
If i set the waveform to dc, it uses the offeset circuit to output the signal.
So, setting the signal to square wave and dc 99.999%:
  • If amplitude is > 5v / with 6v signal i get +3vdc without load. With 50ohm load i get only 1v instead of 1.5v expected
  • If amplitude is > 0.5 and <= 0.5 / with 5v signal i get +2.5vdc without load. With 50ohm load i get  1.25v as expected
  • If amplitude is < 0.5 / with 0.5v signal i get +0.275vdc without load. With 50ohm load i get  0.102v

I know that 50ohm, must be the impedance and i'm measuring pure resistance, but it's normal?
What is the current limit of the opamp? And what is the open loop output impedance of the opamp? If you dig deeper into the specifications then you'll see that a surprisingly large number of opamps can't drive a lot of current.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 05, 2020, 12:48:03 pm
One opamp is the upgraded ths3491. But seem that in some ranges it uses an opa686n.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 05, 2020, 01:02:14 pm
Errata corrige. On 6600 is the opa, on 6900 there is an ad 8009 that can supply enough current for a 50ohm load at 5v
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 05, 2020, 02:57:07 pm
Sorry, but who upgrade the opamps on this units, remove the original ths part or put the 3091/3491 in parallel to the pre existing part? Because my unit had the 2 100ohm output resistors per channel not put in parallel, but every resistor was directed to one output of an opamp, giving a 100ohm at the output  if only one of them is installed (like out of the box...) . Now i have put them in parallel (shorting pins 1 and 7 of the removed u9 and u5) for have a 50ohm impedance also when using the range above 5v. And i have also removed the 2 resistor per channel of the old opamps. I suspect an error in the pcb...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 05, 2020, 08:54:54 pm
Thanks Johnny B Good.... i still miss what is a "50ohm pad" but i've roughly understood the problem, that if i've well understood was fixed in the 6900.

Another thing, someone know what calibrate every trimmer onboard? In the fy2300 was easy as the circuit was much simpler. I see 3 of them per channel. On the 3200 there was the offset, zero adj and gain, i suspect that on the 6900 are the same...

 Your " i still miss what is a "50ohm pad" " is a slightly different question to the original. The 'padding out' attenuators used to trim the signal levels going into or leaving a fixed gain amplifier block are typically  spoken of simply as being an XdB pad in the telecoms industry (where X is the number of dBs of attenuation). The 'system impedance' (in our case, 50 ohms) is normally only  mentioned if there's any chance of confusion.

 In this case (Feeltech's confusion) I could only guess at the intended 20dB or so of attenuation, so mentioned only the 50 ohm 'system impedance' value versus the actual impedance value of 85 ohms of this misbegotten attenuator network formed by the two triplets of resistors marked as RS1 through to RS6 on the FY6900 mainboard which so clearly showed the 4 x 100 ohm (marked 101) shunt resistors and the 2 x 510 ohm (marked 511) series resistors exactly matching the resistor values used in the 6600 and 6800 models.

 I've never dared to mess with any of these trimmers since the dc offset and gain calibration settings were pretty well spot on to begin with and I wanted them to stay that way. There did appear to be some confusion as to the effect of a supposed DC offset trimpot on the gain. Looking at Der Kammi's reverse engineered circuit diagram, I think I can understand why.

 The W16 and W26 trimpots have nothing to do with DC offset adjustment as might be implied by DerKammi's labeling and everything to do with trimming out common mode gain (or balancing the gain between the inverting and non-inverting inputs to maximise the CMRR. Thinking about it, having just now solved the puzzle of those trimpots' function, I guess a better way to have labelled them would have been to have named them as "OPA_CH1_CMR_ADJ" rather than "DC AMPL_CH1_OFFSET" (easy to be wise in hindsight, of course ::) ). All opamps are, by definition, DC amplifiers so the need to mention "DC" as a part of the description wasn't really required in this case anyway.

 I don't believe DerKammi thought the W16 / W26 trimpots had anything to do with calibrating dc offsets, it was just bad luck that his choice of DC and OFFSET in the label could, upon cursory inspection, imply such a function. I can now see that it requires two trimpots in order to adjust the gain by equal amounts on each leg of a balanced input amplifier, hence the W26 and W5 trimmer combination to maintain a high CMRR performance on CH1 (ditto W16 and W3 for CH2).

 The only trimpots involved in calibrating the DC offsets on each channel are those marked W1 and W2. It is only when you understand this and the interactive nature of the W5/W26 and W3/W16 gain adjustment trimpots, that you have any hope of improving the gain and DC calibration before those trimpots fall to bits from excessive trial and error attempts to get back to where you'd started from. :-BROKE ::)

 Whilst I'd normally disregard that age old adage, "If it isn't broken, don't fix it!" as advice for wimps, in this case I rather think discretion is most definitely the better part of valour. If the calibration seems to be seriously out of wack and you're feeling brave/lucky and heroic enough, then by all means have a go (but take heed of the following advice lest you find yourself chasing phantoms).

 And, please note that allowing an earth loop to exist will create mystery DC offsets so leave it disconnected from anything else connected to ground if you haven't already fixed the earth loop issue created by Feeltech's half assed attempt to eliminate the half mains voltage ESD hazard to any DUT being connected up that had existed with the FY6600 and its predecessors.

 The above comments weren't intended as a criticism of DerKammi's very fine work in producing this reverse engineered circuit diagram which had been intended to serve the needs of a group who'd spent weeks discussing exactly what had gone into and what had been left out of this diminutive box of tricks.

 As for the FY6900, you can be pretty certain that there'll be few (if any at all) departures from what DerKammi had revealed of the FY6600 circuitry. There are only a limited number of ways to build a signal generator of this quality at such a low price point. From what I've seen of the FY6900's innards, it seems Feeltech have stuck with a basic tried and tested circuit layout, even to the extent of retaining that cockamamie 85 ohm attenuator pad  :wtf:  ::)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 05, 2020, 09:51:23 pm
So, regarding this argument, i've discovered something.
If i set the waveform to dc, it uses the offeset circuit to output the signal.
So, setting the signal to square wave and dc 99.999%:
  • If amplitude is > 5v / with 6v signal i get +3vdc without load. With 50ohm load i get only 1v instead of 1.5v expected
  • If amplitude is > 0.5 and <= 0.5 / with 5v signal i get +2.5vdc without load. With 50ohm load i get  1.25v as expected
  • If amplitude is < 0.5 / with 0.5v signal i get +0.275vdc without load. With 50ohm load i get  0.102v

I know that 50ohm, must be the impedance and i'm measuring pure resistance, but it's normal?

 Please keep in mind that the P-P thresholds of 500mV and 5v correspond to the DC voltage levels of plus or minus 250mV and 2.5V respectively.

 It looks like the 99.999% must be the duty cycle value so you can use a DMM to measure DC voltage. The readings you obtained are correct for the first two cases but the final case should have given an open cct reading of 250mV rather than the 275mV you saw. A quick calculation shows that the 102mV reading matches expectations when an 85ohm attenuator has been inserted into the signal path.

 It could be the DMM reacting badly to the transient dip when switched to its 2Vdc range. repeat the test on the DC waveform setting using the plus or minus 250mV and plus or minus 2.5V relay switching thresholds and report back.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 05, 2020, 10:29:55 pm
Dc waveform is generated by the offset circuit, and not pass in the attenuation circuit (no relay clicking varying the range). So it's not good for this measurement.
I was using rectangle with duty so high to be compared to a dc (but this time we are going in the attenuation network) for have a good measirement of the voltage drp across the load resistor. As i've posted after that comment the reading at the >5v range was off, and actually i had a 100ohm resistor to the output of the ths opamp instead of 50 (that's why i had only 1v with amplitude of 6vpp, with duty 100% is +3v). With 50ohm load and a 100ohm output impedance 1v is correct, but it's not correct the 100 ohm output impedance. With 50 ohm output impedance and 50ohm load i must have half volts (so 1.5v).
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 06, 2020, 12:31:15 pm
Sorry, but who upgrade the opamps on this units, remove the original ths part or put the 3091/3491 in parallel to the pre existing part? Because my unit had the 2 100ohm output resistors per channel not put in parallel, but every resistor was directed to one output of an opamp, giving a 100ohm at the output  if only one of them is installed (like out of the box...) . Now i have put them in parallel (shorting pins 1 and 7 of the removed u9 and u5) for have a 50ohm impedance also when using the range above 5v. And i have also removed the 2 resistor per channel of the old opamps. I suspect an error in the pcb...

 Correct me if I have misunderstood the above but, as best as I can interpret it, you've already tried upgrading the single THS3002i dual opamp (shown as U5A and U5B in DerKammi's reverse engineered circuit diagram) to a pair of THS3491 (or THS3091 or THS3095) single opamps (depicted in the diagram as U21 and U22 (THS3001)). Unfortunately, this attempt to include the circuitry around the empty U21 and U22 IC locations implies that the original THS3002i stays in place when upgrading to a pair of higher grade 3001, 3091, 3095, 3491 or 3495 opamps. This not the case. The original THS3002i must be removed when populating the empty U21, U22 IC locations (keep in mind that this was aimed at a group who were as much aware of this requirement as DerKammi had been when he'd originally traced out the circuit layout for his own needs).

 When I did my own opamp upgrade just over a year ago, it was simply just a matter of extracting the old THS3002i opamp from the board without damaging any circuit traces and soldering the replacements into the U21 and U22 locations. There had been no need to solder additional wire straps or re-arrange resistor placements. All the required circuit traces on the FY6600's main PCB were present to make this an either/or choice. You must remove U5 when you install single opamp ICs in the U21/22 locations.

 However, in the specific case of the THS3491 opamps I'd chosen to use, I ran a wire strap between pins 1 and 4 in order to take the ref pin (1) to the negative rail (pin 4) as per the the exhortation in the datasheet notes to connect this to a more negative potential than the intended switching threshold of the /PD pin. The purpose of this ref pin is to simplify interfacing between the control logic and the THS3491 when it is powered from dual rail +/-5 to +/-15v  supplies which share the control logic's ground return rail.

 The older THS3095 also has these extra pins but the datasheet was last revised December 2015 and neglects to mention the need to tie the ref pin to a negative potential (the 3491datasheet was revised more recently in July 2018) so those who'd used the 3095 had simply left these pins floating, seemingly without the ill effects implied by the THS3491 datasheet instruction not to allow the ref pin to float. Being aware of the implied risk of allowing any ref pin to just float, I played it safe and tied it to the -12v rail on pin 4. The /PD pin has an internal pullup which means it will float high, enabling the opamp by default in this case, so can safely be left open circuit.

 The circuit layout on the FY6600 main PCB to allow a simple swap between a single dual opamp and a pair of single opamps does introduce additional parasitic inductance and capacitance into the circuitry. It's just possible that Feeltech have made changes to reduce these effects which do now require re-positioning of the resistors when making such an opamp upgrade. It's impossible to tell from the photograph.

 The once relatively straightforward opamp upgrade modification with the FY6600 (and AFAIAA, the FY6800) boards may now be a little more complicated in the case of the 6900 boards. Since I don't own an FY6900, I've not felt any pressing need to track down any information in this regard so this is just speculation on my part. If you've been basing your upgrade on the FY6600 mods, you may have simply been caught out by some small but radical changes to the PCB layout on the FY6900 main board.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 08, 2020, 05:40:40 pm
As now i've done nothing to the ref pin. Simply removed the 3001 opamp, removed his set of feedback resistors, and shorted the two 100 ohm output resistors for have a 50ohm output impedance.
Need to check on fy6900 where the ref pin goes, but by now all seem works as it should.

I was also checking the attenuation pad for finding the correct values. Following this link:
https://www.electronics-tutorials.ws/attenuators/pi-pad-attenuator.html (https://www.electronics-tutorials.ws/attenuators/pi-pad-attenuator.html)
It suggest that's a pi-pad, with 50 ohm input (the 49.9 ohm resistance at the output of the ad8009). Following the formulas, for a 20db attenuation (from 2.5v to 250mv) i need the 2 resistors to ground at 61.1ohm and the resistor in series at 247.5ohm, for have a Zi=Zo= 50ohm.
This calculation seem correct? This evening i'll try this combination. For sure the opamp ad8009 can source the required current (rated at 150ma).
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 08, 2020, 10:30:16 pm
Those values works perfectly. Attenuation perfect. I've used for the 247.5ohm a series of 0805 220+27 ohm, and the 61.1 is a series of 56+4.7. Why they have not used this values?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 09, 2020, 12:19:42 am
Attach a photo of the attenuation pad mod and a photo of the inside of the device, crumbled with heat sinks (everything got it heatsink, fpga, ldo, also glued something on the 2 ad8009, and for sure one big on the ths), 2 trasformers (one for +/-12 and one for 5v all linear). The unit got also a 0.9ppm 10mhz tcxo, ths3491, attn pad mod and the 50ohm mod for the ths output. Also added 2 multiturn pot for set the gain of the opamp that do the offset as was quite off. Original resistor is 3k, used 5k pot. Also used an ntc sensor + tc648 pwm fan controller + 40mm silent fan.
As hardware i hope that's all. I've noticed a lot of sw bugs. Sometime the sync not works,  in dc mode if the frequency is  set high i can't go over +/-2.5v (but it's dc....), somerimes does random weired thing on the settings. Next i try to do a fw upgrade (now i have 1.3.1).
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 09, 2020, 02:57:26 am
As now i've done nothing to the ref pin. Simply removed the 3001 opamp, removed his set of feedback resistors, and shorted the two 100 ohm output resistors for have a 50ohm output impedance.
Need to check on fy6900 where the ref pin goes, but by now all seem works as it should.

I was also checking the attenuation pad for finding the correct values. Following this link:
https://www.electronics-tutorials.ws/attenuators/pi-pad-attenuator.html (https://www.electronics-tutorials.ws/attenuators/pi-pad-attenuator.html)
It suggest that's a pi-pad, with 50 ohm input (the 49.9 ohm resistance at the output of the ad8009). Following the formulas, for a 20db attenuation (from 2.5v to 250mv) i need the 2 resistors to ground at 61.1ohm and the resistor in series at 247.5ohm, for have a Zi=Zo= 50ohm.
This calculation seem correct? This evening i'll try this combination. For sure the opamp ad8009 can source the required current (rated at 150ma).

 Prompted by your efforts at cracking this conundrum (converting from an 85 ohm pad to a 50 ohm one which matches the high impedance on the output condition that Feeltech corrected for in the firmware), I've girded my loins and faced this beast of a problem once more.

 This time, I think I've got the correct solution. Remarkably, it turns out that the attenuation required is very close to the 20dB figure you arrived at. It turns out to be 19.69dB (50 ohm pad). This was an "intermediate" figure which I'd confused myself into thinking required a 6.02dB correction factor (up or down - I was undecided initially but went for the extra attenuation which then required me to trim the series resistance down so low that I ended up with a 45 ohm pad).

 I think I'd overlooked the fact that the output voltage under open circuit (no loading on the output) in the range >0.5v <5 volt P-P when the OPA686 is directly driving the output via its pair of 100 ohm resistors which set the output impedance to 50 ohm, the voltage is that at the OPA686's output pin (theoretically, no volt drop in the 50 ohm resistor).

 Obviously, when the pad is switched into circuit at the transition 501mV to 500mV p-p whilst the output remains unloaded, the 85.9 ohms loading from the pad causes a volt drop in that 50 ohm resistor reducing the voltage going into the pad to 63.22% of the OPA686's output voltage which is reduced by another 16.39344% in the pad itself to give a total reduction factor of 0.10364 which corresponds to an attenuation of 19.69dB.

 When I'd reached this point in my earlier calculation attempts, I'd erroneously assumed I'd need to add (or subtract) another 6.02dB to account for the terminated output state on account these calculations had been based on voltage ratios in the unterminated state. Since I figured I'd not properly accounted for the actual parameters of this conundrum, I decided to run the volt drop calculations again with the 19.69dB resistor network values as a sanity check (it had just seemed too easy a solution to be true).

 The new resistor values I came up with are 62 ohms for the shunt elements with a 240 ohm series element which gives you a 19.68dB 50.34 ohm pad. If you can afford (or else select on test) the 61.9 ohm resistors, this gives you a 19.69dB 50.27 ohm pad with a 240 ohm series element. I used the following attenuator calculator:

https://chemandy.com/calculators/pi-attenuator-calculator.htm (https://chemandy.com/calculators/pi-attenuator-calculator.htm)

along with this on-line dB ratio calculator: http://www.sengpielaudio.com/calculator-db.htm (http://www.sengpielaudio.com/calculator-db.htm)

 You might wonder why I'm chasing attenuation values to within 0.01dB and impedance values within half an ohm of the nominal 50 ohm system impedance. It's critical to exactly match the attenuation given by the 85 ohm in the unterminated state if you don't want to see the output jump up by 3 mV from the expected 500mV after dropping down from the 501mV mark using the 62 and 240 ohm values in place of the perfect resistor values of 61.562 and 238.636 ohms produced by the calculator (assuming 0.5% tolerance 49.9 (or 100//100) resistors on the opamp outputs).

 If Feeltech had used an actual 20dB 50 ohm pad, then the OPA686 output voltage would have been boosted from 500mV to 5v when switched from a 501mV setting to the 500mV level. However, to correct for the error introduced by this 85 ohm pad, they had to reduce the boost in voltage at this transition point to 4.8244v p-p which is what complicates the replacement of the 85 ohm pad with a 50 ohm pad that will minimise this voltage jump (which will now be correct for both unterminated and terminated cases - currently only correct for the unterminated case more commonly associated with audio frequency testing), hence the resulting 19.69dB pad.

 I'm hoping you can run through the calculations to check my own best effort. After getting it so wrong on my first and second attempts over 6 months ago, I don't fully trust my calculations and would prefer an independent check by others that aren't me! ::)

 When I last asked if anyone else subscribed to the FY6600 topic thread could have a crack at this problem, I was met with resounding silence. The real issue with this "Skoolboy Howler" of Feeltech's is that for terminated conditions, this leaves a gaping hole in the range of output voltage levels just below the 500mV p-p settings range (250mV p-p terminated) that can only be filled by using an external 50 ohm 20dB attenuator.

 Thinking about this issue of gaping holes in the voltage level adjustment range, a modest 'backward jump' of a few mV at this 500mV transition point is rather more tolerable than the huge gap that currently exists since you can compensate by dialling the voltage level down a few more mV. If you substitute with a 20dB 50 ohm pad, you'll create a small hole in the voltage settings range whereas a 19.5dB pad will just give you a small overlap which whilst still a little irksome, at least doesn't prevent you adjusting to an exact voltage setting (within 1mV) required to execute a test.

 Anyway, that 20dB pad you're thinking of creating is only 0.31dB adrift from my own calculations so you might want to try the 62 and 240 ohm resistor values I came up with for a 19.68dB 50.34 ohm pad (a little overlap in voltage settings is better than a little gap imo ;) ). This, of course, assumes you don't see a problem with any of my calculations.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 09, 2020, 09:18:05 am
With rectangle wave set to 99.999% dc, passing from 0.5000vpp setting without load (0.250v at the output) to 0.5001 the measured voltage it's the same to the mv scale. A setting change of 0.0001v is under the DAC resolution. With 50 ohm load obviously the same.
Sorry, but why you speak that we need less than 20db of attenuation? With output voltage of 0.250vpp (0.500vpp setting with dc 99.999) i've measured exaclty 2.500v at the output of the opamp. A drop of ten times it's a perfect 20db attenuation. And actually with the 56+4.7 and 220+27 resistors all seem absolutely perfect.
The only imperfection that now have the device is when switch from the 5v range to the 5.0001, so when the ths kicks in. If i have a measured 1.2478v output voltage, when ths are inserted, increasing from 5.0000 to 5.0001 switch to 1.2635v. Around 16mv error, in any case not too bad. It's different from ch1 to ch2. About this, it's too difficult to fix. Need to made adjustable the gain of the ths, but a trimmer here means introducing some problems. Maybe it's sufficient to replace the feedback resistors with fancy precision units.
I not think that worth.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 09, 2020, 09:33:30 am
Some measurements of my device now, with 50ohm load, 10khz, duty 99.999% (can be assumed dc).
Setting 0.0000v, measured 0.0002 (lost a lot of time with trimmers for have this!)
Setting 0.5000v, measured 0.1243v
Setting 0.5001v, measured 0.1247v
Setting 5.0000v, measured 1.2480v
Setting 5.0001v, measured 1.2648v
Setting 24.0000v, measured 6.036v

Same test, but without load:
Setting 0.0000v, measured 0.0004v
Setting 0.5000v, measured 0.2475v
Setting 0.5001v, measured 0.2497v (2mv error, quite normal without the matched output impedance, but enough precise for me)
Setting 5.0000v, measured 2.4964v
Setting 5.0001v, measured 2.5346v
Setting 24.0000v, measured 12.096v

Ch2 is a lot better as the ths resistor probably are a bit mor in tollerance.

By now, i'm quite satisfied. I hope to not open it for at least some time
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 09, 2020, 04:41:19 pm
With rectangle wave set to 99.999% dc, passing from 0.5000vpp setting without load (0.250v at the output) to 0.5001 the measured voltage it's the same to the mv scale. A setting change of 0.0001v is under the DAC resolution. With 50 ohm load obviously the same.
Sorry, but why you speak that we need less than 20db of attenuation? With output voltage of 0.250vpp (0.500vpp setting with dc 99.999) i've measured exaclty 2.500v at the output of the opamp. A drop of ten times it's a perfect 20db attenuation. And actually with the 56+4.7 and 220+27 resistors all seem absolutely perfect.
The only imperfection that now have the device is when switch from the 5v range to the 5.0001, so when the ths kicks in. If i have a measured 1.2478v output voltage, when ths are inserted, increasing from 5.0000 to 5.0001 switch to 1.2635v. Around 16mv error, in any case not too bad. It's different from ch1 to ch2. About this, it's too difficult to fix. Need to made adjustable the gain of the ths, but a trimmer here means introducing some problems. Maybe it's sufficient to replace the feedback resistors with fancy precision units.
I not think that worth.

 Many thanks to you for those test results. They more or less confirm my own recent findings (although I've yet to test the actual voltage change on the opamp output pins when the attenuator is switched in and out of circuit).

 The reason for the smaller (19.69dB) attenuation value was simply to match that of the 100/510/100 85 ohm pad's effect when the output is unloaded since Feeltech had seemingly corrected for this departure in the firmware from the 20dB they must have originally intended. My original tests had shown less than 1mV error in making adjustments around the 500mV relay switching threshold in the unloaded test case but a massive 64mV drop in the terminated test case when going from 501 to 500mV p-p settings.

 Both channels exhibited the same pattern to within a mV or two of each other so I assumed from this that Feeltech had applied a firmware patch to correct the error introduced by using an 85 ohm pad in place of a 50 ohm pad. This correction method can only apply to either the unterminated or terminated case not both and it seems Feeltech had elected to correct for the high impedance case typical of audio frequency kit.

 In hindsight, I suppose the 5% resistors they'd selected from the E24 range could have fortuitously created a 20dB pad on both channels in my case rather than the theoretical 19.69dB of a Pi attenuator network comprised of 100 ohm shunt arms with a 510 ohm series element.

 If I had been more thorough in my testing, I could have used the "DC Wave" option and test settings of 250 and 251 millivolts whilst probing the output pins of the OPA686 opamps with a DMM which would have provided definite proof as to whether Feeltech had actually noticed the problem and applied a firmware fix to compensate for the high impedance case or whether it had simply been the effect of wide tolerances in the components they'd used just happening to minimise the error by "dumb luck" alone with my particular example.

 Of course, it's never too late to run this check to properly verify what is actually going on. I may have been giving Feeltech far too much credit for their technical 'expertise' in kludging a firmware bodge to hide this error from the Audiophool community.

 If my (rather belated) testing shows the same voltage jump at the output of those OPA686 opamps of 10 to 1 and 1 to 10 as the attenuator is switched out and in respectively as you've discovered with the FY6900 (the FY6600 could have been different), all the complexity of calculating a resistor network for a 19.69dB pad vanishes at a stroke and I'm left with the much simpler task of calculating for a bog standard 20dB pad.

 Mind you, I'd still have to find four 61.2 and two 246 ohm resistors to make up 19.95dB 50.01 ohm pads out of the E192 0.5% range or else select on test combinations that will create a 20dB pad within 0.5 ohm of 'nominal impedance'. In this case, I think it's preferable to insert slightly too little than slightly too much attenuation since the resulting overlap can be worked around if you need to produce a specific level to within a mV or so.

 The similar issue when the 12dB boost amplifier is switched into circuit for the 5 to 20 volt p-p range is less of a problem since the 16mV error you mentioned with the output terminated corresponds to an equivalent of 1.6mV at the 500mV transition point and, unlike the 500mV case, represents the same dB change whether the output is terminated or not when adjusting the level around the 5v p-p point.

 Like you, I don't think this small error is worth chasing down. Very likely signal/function generators in the "Semi-professional Budget Class" costing ten times the price of the Feeltech will also exhibit a similar issue whenever their 12dB boost amplifier stages are switched in and out.

 In view of your findings regarding the tenfold increased voltage when the 85 ohm attenuator is switched into circuit in the case of your FY6900, the presence of an 85 ohm attenuator across three generations of function generator models defies all reasonable explanation. Its very existence appears simply to to be an oversight of utter technical incompetence of shamefully monumental proportions on Feeltech's part and nothing more (no clever firmware bodge to hide its consequences from the audiophool community after all!  :palm:)

 It seems highly probable that the 6600 and 6800 models also applied a 10 fold boost in output voltage to compensate for switching a 20dB attenuator into the circuit so as to sustain the signal to noise performance at output levels below the 50mV p-p mark.

 Of course, this might not be true for the FY6600 but I'll be testing this effect in my own function generator just to confirm the exact truth of the matter before attempting to re-work those "20dB" attenuator networks formed by resistors RS1 through to RS6. TBH, I'll be extremely surprised If my results, which I'll be reporting back to this topic thread (and the FY6600 thread even though they don't deserve to know >:( ), fail to match yours.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 09, 2020, 05:45:42 pm
When attenuation kicks in, it switch from the 0.500vpp (0.5001 setting) to 5.000vpp (0.5000vpp setting). So the attenuator need to output 500mvpp.
I've neither calculated the attenuation factor of the original pad (but i've confirmed the 84.something Zout). I knew Zin, Zout, attenuation factor and done calculations based on this. I not know why feeltech chosen those values.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BlackICE on April 10, 2020, 01:37:18 am
I have fy6900 also and it indeed has the 83 or ohm  resistor problem at switch over point of 0.5v. Also I find it annoying setting the voltage offset to zero you never really get a 0 offset. When trimming the offset to a true zero and changing the amplitude the offset drift off again.

I understand the recommendation to connect the ground lead through a 1k to 10K resistor to PE instead of direct connection. What are the resistor modifications to correct for the 83 ohm problem?

I created an esp32 circuit board to interface with a Silgent oscilloscope to do Bode plots. I initially used the 5 volts coming off the rear connector. But soon discovered that that didn't work too well it created huge amounts of amplitude and timing Jitter of the generated waveforms. I suspect the current available from the 5-volt output isn't nearly adequate for esp32 to that times can draw an excess of 200 milliamps when the Wi-Fi is active and up to 800 milliamps of you turn Wi-Fi and Bluetooth on at the same time. I also added some decoupling capacitors and that didn't seem to help at all. Does anybody have any idea about the true current capacity of the 5 volt output and Lead.

Bty this changing output impedance led me to falsely believe after doing Bode plots that my audio amplifier was changing gain based on the input amplitude.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 10, 2020, 03:51:30 am
When attenuation kicks in, it switch from the 0.500vpp (0.5001 setting) to 5.000vpp (0.5000vpp setting). So the attenuator need to output 500mvpp.
I've neither calculated the attenuation factor of the original pad (but i've confirmed the 84.something Zout). I knew Zin, Zout, attenuation factor and done calculations based on this. I not know why feeltech chosen those values.

 We'll never know for sure why they chose to approximate the required 20dB for the unterminated case using 100 ohm shunt resistors with a 510 ohm series resistor. We can speculate that it could have arisen from an act of bean counteritus (cost savings) and an overstock of 100 and 510 ohm resistors which just happened to fit the bill (give our audiophool customers the required unterminated attenuation and let the Devil take the hindmost (those needing to drive 50 ohm loads to get valid test results),

 An alternative speculation is that their computers and/or access to the on-line attenuator calculators were down that day and the "designer" had looked at the most likely and abundant resistors they had in stock (favouring the massively overstocked components) and trialled some test calculations that would at least serve the high impedance case and earn him a "Pat on the head" from the boss or chief bean counter for his ingenious cost cutting solution.  :-//

 Yet another possibility is that an error in calculating the resistor values (the "Skoolboy Howler" hypothesis) had simply gone unnoticed for lack of proper qualification testing  :-DD before committing the design to production.

 And one for the more cynically minded is that it was a deliberate error, planted as an "Easter Egg" challenge to their largely cash strapped home hobbyist market demographic to solve as yet another warranty  :-DD voiding temptation to keep customer support costs as close to zero as they possibly could.

 That's four possible reasons for those chosen values (all pure speculation for my amusement off the top of my head) you can choose from. If you can think of any others to add to that list, then pray, do please tell. ;)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 10, 2020, 05:28:17 am
I have fy6900 also and it indeed has the 83 or ohm  resistor problem at switch over point of 0.5v. Also I find it annoying setting the voltage offset to zero you never really get a 0 offset. When trimming the offset to a true zero and changing the amplitude the offset drift off again.

I understand the recommendation to connect the ground lead through a 1k to 10K resistor to PE instead of direct connection. What are the resistor modifications to correct for the 83 ohm problem?

I created an esp32 circuit board to interface with a Silgent oscilloscope to do Bode plots. I initially used the 5 volts coming off the rear connector. But soon discovered that that didn't work too well it created huge amounts of amplitude and timing Jitter of the generated waveforms. I suspect the current available from the 5-volt output isn't nearly adequate for esp32 to that times can draw an excess of 200 milliamps when the Wi-Fi is active and up to 800 milliamps of you turn Wi-Fi and Bluetooth on at the same time. I also added some decoupling capacitors and that didn't seem to help at all. Does anybody have any idea about the true current capacity of the 5 volt output and Lead.

Bty this changing output impedance led me to falsely believe after doing Bode plots that my audio amplifier was changing gain based on the input amplitude.

 Go to https://chemandy.com/calculators/pi-attenuator-calculator.htm and plug in the values 20dB and 50 ohm. This will give you the perfect values but you can also specify 'preferred' resistor values from the E12, E24, E48, E96 and E192 tables here: https://chemandy.com/technical-articles/single-pages/preferred-resistor-values.htm.

 You can also try different value combinations in the "Preferred" values entry boxes from the less exotic resistor tables or do what masterx81 did and make up the required values with pairs of resistors in series (or alternatively use parallel resistor combinations).

 The use of a 20dB attenuator for voltages of 0.5v p-p or less (and likewise, the use of a 12dB boost amplifier for the voltage range 5 to 24v p-p (5 to 20v p-p in the 6600 and 6800 models)) provides a 'gearbox' function for the 14 bit DAC 'engine' to maintain a better match to the available s/n performance (notably the issue of quantization error noise that becomes increasingly intrusive as lower voltage outputs are selected).

 This use of relay switched attenuators (and boost amplifiers for signal generators specified to deliver more than the 5v p-p limit of lesser specified devices) will often introduce a discontinuity of level as they're adjusted through the switching thresholds due to slight mismatches between the attenuator and tenfold boost of signal voltage intended to precisely match the additional 20dB attenuation when going from the 501mV setting to the 500mV setting (and vice versa for the opposite direction). This calls for a very tightly specified 20dB attenuator to hold such discontinuities to an acceptable level (and assumes a very precise tenfold increase or decrease of the output voltage from the opamp feeding this switched attenuator).

 masterx81 has already done the necessary testing to prove that the required attenuation is the classic 20dB with an associated order of magnitude step change in level  from the opamp's output applied at the switching points in the amplitude settings range so you can proceed with some confidence that replacing resistors RS1 to RS6 with values obtained using the attenuator calculator will resolve the problems you've been experiencing.

 As for the power issues you've been suffering with the esp32 module, all I can advise is that you stop abusing the poor old FY6900's PSU board and use a separate 5v psu to power your esp32. There was room for some doubt as to whether you were abusing the 'scope's or the signal generator's 5 volt PSU rail - the signal generator seemed the most likely candidate for this abuse. However, whichever it was, stop doing it! Use a dedicated 5v supply (and link the common zero volt rails as required).

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BlackICE on April 10, 2020, 05:39:39 am
Johnny thanks for the tips. I was only abusing the function generator which is cheap and disposable. The oscilloscope connects to the esp32 through Wi-Fi and have no physical connection whatsoever. It's too bad that the function generator cannot output enough 5 volts to run the ESP32. Otherwise it would be nice slick solution to just add a small board plugged into the back and have full support for Bode Plots. Are there any easy adjustments for the DC offset? It seems to be all over the place and amplitude dependent.

The thread below talks about how do Bode plot using a FY series function generator. The first solution was to have a PC act as a function generator simulating a Siglent function generator then translating those commands to an FY function generator through a serial port. The second version used a precursor to the ESP 32 the ESP8266 to act as a Siglent function generator on a LAN using Wi-Fi. I took the Wi-Fi code and modified it to use esp32 and added support for using DB units.

https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-and-sds1204x-e-bode-plot-with-non-siglent-awg/ (https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-and-sds1204x-e-bode-plot-with-non-siglent-awg/)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 10, 2020, 06:53:06 am
The psu of the fy6900 is the same as the fy3200... not so nice. And for sure can't keep much more load on 5v line than the 500ma required by the logic of the  unit.

Question: it's safe to connect the ground through an 1k resistor? By now i have a linear psu with ground tied to earth. Would be nice to put a switch, but for now i not need it.
Higher end unit how handle the grounding problem?


For setting the offset and amplification i've used a long procedure.
For first, go in dc waveform, set volts to 0, and turn the w1 or w2 (depending on channel) for have 0v on the output. Then set rectangle waveform, 5.000v setting, and turn w16 or w26 until with duty set at 99.999 and duty set to 0.001 you not have a perfect specular value (for example 2.550 and -2.550). After this, set dc at 99.999,  move the gain (w3 or w5) for have a value half the error (as the previous example, 2.525). Then set the duty back to 0.001 and fix the offset as before until with dc at 0.001 and 99.999 the measure isn't the same. Then recheck with waveform in dc if the 0v is remained at 0 (very unlikely) and restart the "loop". I've lost a lot of time for a good result.
Moving the dc "wave" offset moves a bit also the rectangle wave offset.
Do it after at least 30min the device is powered on and at operating temperature. Adding heat sink to everything and a temperature controlled fan lowered the change with temperature, but something changhe

For attenuation pad i suggest a series of 56+4.7ohm instead of 100ohm, and a series of 220+27ohm  instead the 510ohm. Both 0.5ohm under the perfect match but for me are enough, are a bit a pain to be soldered. If you find a way with parallel resistor would be easier, and let us know
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BlackICE on April 11, 2020, 07:09:53 am
Thanks, masterx81

How close do you get your voltage offset to be for all that work?

I haven't opened the box yet so it would be helpful if you can tell me the correct size of the resistors to fit the pads. I don't think voiding the warranty is a big deal since I appears there isn't one! I asked my seller and email feelelec about my sin wave got corrupted. No answer from feelelec the seller said they will look into it and get back to me. Haven't heard anything since. Later when I manage to update the PC software (need to run in admin mode so that China can spy on my PC?) I found a menu item that as labeled "repair_sine" that fixed it. (for how long?)

Johnny was giving a number of reason of why the wrong resistor values may have been used. Given that they are using super old NEC relays, I would say what they can get cheap, or had plenty stock of, who cares no one will find out and if they do ha ha no warranty.

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 11, 2020, 07:58:50 am
Some measurements of my device now, with 50ohm load, 10khz, duty 99.999% (can be assumed dc).
Setting 0.0000v, measured 0.0002 (lost a lot of time with trimmers for have this!)
Setting 0.5000v, measured 0.1243v
Setting 0.5001v, measured 0.1247v
Setting 5.0000v, measured 1.2480v
Setting 5.0001v, measured 1.2648v
Setting 24.0000v, measured 6.036v

Same test, but without load:
Setting 0.0000v, measured 0.0004v
Setting 0.5000v, measured 0.2475v
Setting 0.5001v, measured 0.2497v (2mv error, quite normal without the matched output impedance, but enough precise for me)
Setting 5.0000v, measured 2.4964v
Setting 5.0001v, measured 2.5346v
Setting 24.0000v, measured 12.096v

Ch2 is a lot better as the ths resistor probably are a bit mor in tollerance.

By now, i'm quite satisfied. I hope to not open it for at least some time
The 0v is under the mv range.
My calibration procedure was also a bit harder than normal because i've added 2 trim pots for regulating the gain of the dc offset opamp (for have an almost perfect offset).
Resistors are 0805. If you see my previous post did you see how i've soldered them for have a series. All can be done also in parallel (that's better) but you have to do a lot of calculation do find the right values.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BlackICE on April 11, 2020, 08:34:40 am
How about this combo.

250 plus 60.4 ohms

https://www.digikey.com/products/en/resistors/chip-resistor-surface-mount/52?k=805+resistor&k=&pkeyword=805+resistor&sv=0&pv2085=u250+MOhms&sf=0&FV=3%7C1131%2C3%7C1684%2C3%7C2106%2C3%7C2503%2C3%7C848%2C3%7C976%2C7%7C2%2C7%7C3%2C1291%7C39328%2C-8%7C52&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25 (https://www.digikey.com/products/en/resistors/chip-resistor-surface-mount/52?k=805+resistor&k=&pkeyword=805+resistor&sv=0&pv2085=u250+MOhms&sf=0&FV=3%7C1131%2C3%7C1684%2C3%7C2106%2C3%7C2503%2C3%7C848%2C3%7C976%2C7%7C2%2C7%7C3%2C1291%7C39328%2C-8%7C52&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25)

https://www.digikey.com/product-detail/en/panasonic-electronic-components/ERJ-PB6D6042V/P21222CT-ND/6215477 (https://www.digikey.com/product-detail/en/panasonic-electronic-components/ERJ-PB6D6042V/P21222CT-ND/6215477)

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 11, 2020, 08:44:06 am
Would be ok but both aren't on common values (and i not have them in house). If you need to do an order in any case, as you haven't nothing in 0805 format, order them

Be aware! Those links are wrong! 250megaohm! 60.5kohm!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BlackICE on April 11, 2020, 09:38:54 am
I clicked too soon without reading carefully. The 250 is pricey but only need 2 of those.

I don't have any SMD devices. Never soldered any SMD parts! To remove the old ones I planning to use 2 soldering irons to lift the old part off like using chopsticks. I haven't really done much electronics for decades and have avoided SMD better they seem to be a PITA compared to through hole. However I noticed that places like JLCPCB solders common SMD parts for you at very low cost that makes SMD more attractive.

https://www.digikey.com/product-detail/en/koa-speer-electronics-inc/RK73H2ATTD60R4F/2019-RK73H2ATTD60R4FCT-ND/10234995 (https://www.digikey.com/product-detail/en/koa-speer-electronics-inc/RK73H2ATTD60R4F/2019-RK73H2ATTD60R4FCT-ND/10234995)
https://www.digikey.com/product-detail/en/stackpole-electronics-inc/RNCF0805TKY250R/RNCF0805TKY250RCT-ND/4928401 (https://www.digikey.com/product-detail/en/stackpole-electronics-inc/RNCF0805TKY250R/RNCF0805TKY250RCT-ND/4928401)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 11, 2020, 10:27:57 am
Here in italy you can buy a sample set of 25 resistors 1% 0805 composed of 170values (scale 1.0 1.2 1.5 1.8 2.2 2.7  3.3 3.9 4.7 5.6 6.8 8.2 and multiple) for around 35e shipped. In usa i suspect a lot cheaper.
If you plan to use them only for this work order only what you need.
If you plan to do some smd repairing a set i handy to have.
I use only one soldering iron, but need a bit of practice
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 12, 2020, 12:31:09 am
Thanks to the calculator in this software
http://lygte-info.dk/project/TestControllerIntro%20UK.html#Notes_&_Download (http://lygte-info.dk/project/TestControllerIntro%20UK.html#Notes_&_Download)
I've found some better values. For 61.1 ohm 39+22=61 (instead of 56+4.7=60.7) and for 247.5 a parallel of 390 and 680=247.85 (instead of 220+27=247), all in common E12 values. I not think that change that much, but it's a bit better
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BlackICE on April 12, 2020, 05:40:26 am
Does that software control oscilloscopes and function generators too and log and display the results?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 12, 2020, 07:05:37 am
No... i was playing with it for dc load, multimeter and power supply and i've noticed the calculator that does the iterations for find the best resistor match between serial/parallel
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 12, 2020, 05:11:44 pm
I've reopened it for use the new resistor values for attenuation network (but only opened i've discovered that i've ended the 390ohm resistors :( ).
Now with 22+39 (instead of 56+4.7) and 220+27 the network is less balanced than before. With 50ohm switching from 0.5v duty 99.999 to 0.5001 it goes from 0.1247v to 0.1240v (previously 1.243 to 1.247). And putting the 390//680 resistors for sure it made it worse (as increase the attenuation). I think that i go back to the previous solution as was giving a better result.
And i was also investigating why the >5v range was off, and i've maybe discovered something.
If with no load and the usual dc 99.999 i set 1v, at the output of the opamp i have 0.5000v as expected.
But if i set the amplitude to 5.0001v (for turning on the ths amplifier stage) it jumps to 0.5160v. I need to calculate the gain of the ths stage, but i think that they have done something in software for trying to fix a non perfect gain of the ths stage.

Some measurement ant the exit of the opamp:
Duty 99.999
Set 1v got 499mv
Set 5v got 2498.6mv
Set 5.0001v got 514.9mv
Set 10v got 1029.5mv
Set 20v got 2020mv

Need to do some math
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 12, 2020, 10:53:48 pm
The dc waveform does weired things...
If you are in square, amplitude 5v, and after go in dc, you hear a relay clicking going from 1.000 to 1.001
If you are in square 5.0001v, in dc you not hear any relay clicking in the whole range
If you are in square 0.5000 , in dc you hear 2 times the relay clicking. 1.000/1.001 and 2.500/2.501
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 14, 2020, 04:19:36 am
The dc waveform does weired things...
If you are in square, amplitude 5v, and after go in dc, you hear a relay clicking going from 1.000 to 1.001
If you are in square 5.0001v, in dc you not hear any relay clicking in the whole range
If you are in square 0.5000 , in dc you hear 2 times the relay clicking. 1.000/1.001 and 2.500/2.501

 I've been following the discussion whilst I was getting around to doing more tests with my FY6600, notably confirming your own findings that the voltage is switched by a factor of ten when switching the attenuator pad in and out of the circuit.

 After testing with 99.999% and 0.001% duty cycle square waves and DC voltages (and some sine wave testing at 1KHz thrown in for good measure), I've come to the conclusion that the 85 ohm pad should simply be replaced with a 20dB 50 ohm pad with no further questions asked.

 The results weren't entirely consistent but, putting aside the crappy iterative adjustment requirements of the W3 /16 and W5 /W26 trimpots to set both gain and the DC balance simultaneously, I think that this is the only way to proceed for now before meddling with those damned presets once more.

 It had occurred to me that any dc offsets would skew the 99.999 and 0.001 % duty cycle square wave tests so had tweaked W1 and W2 to zero the 2mV offset each channel had. Unfortunately, I then accidentally tweaked W26 (CH1's gain balance) whilst checking CH2's dc offset so landed up having to go through a more truncated version of your round of adjustments, discovering in this process the excellent reason for my not wanting to meddle with any of these trimmers in the first place!  >:(

 Now, Like you, I discovered some very peculiar behaviour when testing the DC voltage attenuator relay switching thresholds. CH2 uses the pad but now switches at the 100 and 101mV thresholds. CH1 is even more peculiar in that it has decided to not make any use of the attenuator pad!  :wtf:

 Now this may have been the result of my crashing the function generator due to connecting to my GPSDO which is powered off of a 9v wallwart which has half mains live voltage on its DC output lead (basically, the FY6600's half live voltage issue the other way round). This was never an issue until now because previous connections had all been made whilst the GPSDO or the FY6600 was grounded via the DSO.

 I'm pretty certain that the attenuator was being switched in and out around the 250mV mark (500mV in terms of P-P repetitive wave forms) prior to my discovering this old resurrected issue with Feeltech's poorly written firmware not properly recovering from the confusion of an ESD triggered lockup when rebooted.

 The strange thing is that you might expect to see rather wild voltage outputs at the points where it's supposed to switch the attenuator in and boost the voltage tenfold (and vice versa) but it just behaves as if it has forgotten the need to do any of these actions as you work through the voltage settings.

 I haven't tried to do a full system reset to clear out the corrupted settings and take it back to normal just yet. Mine, fortunately is running the later V3.3 firmware which, as far as I know , is free of the 'bricking issues' of the earlier V3.0 and V3.1 versions. However, I will do a restore to defaults after retesting this peculiar behaviour to make sure I hadn't imagined it all.

 It seems the FY6900 isn't all that different to the FY6600 after all, at least as far as the shite firmware quality is concerned at any rate. :( >:( :palm:

 I've just verified the above behaviour but the truth of the matter is that if you've quit the "DC waveform" without resetting the voltage to zero (press the dial or hit the "OK" button when the voltage is selected), you can land up with a dc offset which forms a component of the switching threshold voltage. If this is high enough it can even leave the final amplifier stage permanently switched in and you won't be able to hear any relay clicking at any level  :wtf: >:(

 This isn't the first time I've been hit by this peculiar behaviour but it's so easy to overlook the need to zero out DC offsets inherited from any "DC waveform" testing activity. :palm:

 The problem is basically just down to the shite quality of Feeltech's firmware. It's not fatal, just pretty damned annoying! >:(

 Incidentally, I've noticed some really bogus circuitry between the twin (balanced line) 5 element filter and the inputs to the primary opamp (the OPA686 in the case of the FY6600). The loading on the filter's outputs looks far from balanced and nothing like the normal arrangement for a balanced to unbalanced buffer amplifier setup.

 I suspect the real reason for this horrible interaction between the gain trimmers is to provide a means to compensate for any imbalance between the DAC904's constant current outputs (IOUT and /IOUT) which feed the 49.9 ohm resistors which turn the signal into a 50 ohm voltage source driving each half of the anti-aliasing filter which drives a 100 ohm load on the inverting output and a 100 ohm plus the variable resistance of a trimmer in series on the non-inverting output. I'd have expected the terminating impedance for this filter to match the 50 ohm feed impedance.

 One other oddity is the choice of connecting the DC offset amplifier output via a 240 ohm resistor into the filter output connection rather than use the virtual ground summing point of the opamp's inverting input pin to the same effect sans the loading it currently adds to the filter.

 I suppose this could simply be errors in transcribing the actual circuit layout to a reverse engineered diagram on DerKammi's part. Although it's been a year since I downloaded the diagrams, there's not been any amendments for the past two years and, after downloading it all yet again, the diagrams remain unmodified. It looks Like I'll have to double check the diagram against the reality of the actual hardware to verify DerKammi's very fine work.

 Assuming no errors on DerKammi's part (which I'm inclined towards) then it looks like Feeltech have made some very odd design choices that go against established wisdom. If nothing else, it's as well to understand exactly how those W5/26 and W3/16 trimmers are supposed to work before going on a quest that's likely to drive you to despair (or even clean round the bend). ::)

 That's a problem I'm not going to try sorting out until after I've fixed the attenuator issue. I've decided to use 249 and 61.2 ohm resistors from the E192 range. With a 0.5% tolerance,the resulting attenuators can range from a low of 19.96dB @ 50.28 ohms to a high of 20.1dB @ 49.94 ohms, a narrow enough tolerance range to stop worrying about hand picking components to obtain the best possible match.

 If you want tighter control you can always pick by selecting on test from a larger collection, in which case you'd probably be better off going for the cheaper E48 range and buy a bagful or two of each value (249 and 61.9 ohm resistors - or 62 ohms from the E24 range) from which to assemble 'perfect attenuator pads'.

 At these frequencies (60MHz max), the additional stray Ls and Cs from series or parallel combinations won't be any problem. When I've needed to source the odd smd resistor over the past year or two, I've looked through my collection of scrapped Desktop PC MoBos armed with a jeweller's loupe and a bright desklamp. Despite the values I'm normally searching for not being commonly found on PC MoBos, I've nevertheless usually succeeded in tracking down suitable resistors (even when Murphy has intervened and teleported my prize into a parallel universe, forcing me to resume my search of PC MoBos once more for more of the same).

 Although I don't expect to find suitable E48 examples of 62 and 249 ohm resistors amongst my PC MoBo collection, I'll still have a look before I resort to shelling out hard cash to be certain I haven't overlooked a 'gold mine' of suitable resistors 'hiding right under my nose'. There's nothing worse than spending good money on stuff you didn't need to buy.

 Ideally, I'd like to acquire a usefully sized stock of smd resistors covering a wide range of sizes and values. When I tried  tracking down such supplies recently, they all seem to be a little overpriced to my mind. I get the feeling that the suppliers are targeting hobbyists with rather more money than sense rather than people like me with more sense than money. I suspect I hadn't been looking in the right places (or searching hard enough). I guess I'm just going to have to try harder next time.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 14, 2020, 04:21:39 am
 Another three images!

 The black button underneath the 10MHz extl reference socket in the 3rd image is the "thru/term" switch which allows me to daisychain the 10MHz feed onto other kit if required. It's otherwise latched in to connect a 51 ohm terminating resistor across the BNC socket as shown in this image.

 I plan on eventually adding a 4 or 8 way distribution amp but if I get another item of test gear that can benefit from an extl 10MHz reference feed before then, I'll be able to simply daisychain the feed by using a BNC T adapter and switching the FY6600's extl 10MHz into 'thru' mode and terminate the far end of the cable to avoid standing wave issues.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 14, 2020, 06:58:31 am
Yes, the offset is  set simply by attenuating the negative input of the opamp.
And i've also noticed that if you not set to 0 the dc value going back to the square wave it maintain some offset. Software a lot to be improved. And i'm running the latest 1.3 (the autoupdate software not find anything new).
For fix a bit the amplification stage i've tried to put some selected resistor values (as you also have suggested). Now instead of near 12.10 v at 24v setting dc 99.999 i have 11.93v... impossible to set well this thing.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: evava on April 15, 2020, 12:25:47 pm
It is crap!

Out of sudden during the work I noticed that (on my FY-6900 generator) SINE trace has other shape (is damaged) on both -
generator and scope! And on both channels together!

It made me really angry and I started immediatelly to google - and I found out that in software in menu Help there is item "Repair Sine" - LOL!

I connected generator to computer, ran Repair sine and nothing happened!
I tried many times and still nothing happend. Then I switched generator off and on, and Sine shape reappeared in all beauty  :)

How happy I am again! - Just, how long this time? What about other shapes? Why only just Sine?   :palm:

So, thank you all who contribute in this forum, for now I have replaced output resistors with 240ohms and 62ohms, that is necessary change IMHO.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 15, 2020, 08:54:26 pm
Johnny B Good, what is the "injection locking module"?


Evava.. you are the second that i hear that the sine got corrupted. And if my memory is good, was corrupted in your same shape. Really strange. Who know what cause it. Maybe a software bug, and it's easier to allow for rebuild the waveform than find the bug
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 16, 2020, 04:57:37 am
 There are, apparently, multiturn trimpots available that fit the same footprint which could help ease the calibration process.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 16, 2020, 05:32:26 am
It is crap!

Out of sudden during the work I noticed that (on my FY-6900 generator) SINE trace has other shape (is damaged) on both -
generator and scope! And on both channels together!

It made me really angry and I started immediatelly to google - and I found out that in software in menu Help there is item "Repair Sine" - LOL!

I connected generator to computer, ran Repair sine and nothing happened!
I tried many times and still nothing happend. Then I switched generator off and on, and Sine shape reappeared in all beauty  :)

How happy I am again! - Just, how long this time? What about other shapes? Why only just Sine?   :palm:

So, thank you all who contribute in this forum, for now I have replaced output resistors with 240ohms and 62ohms, that is necessary change IMHO.

 Regarding the need to replace the 85 ohm attenuator pad resistors with the originally intended 20dB 50 ohm pad resistor values, I wholeheartedly agree.

 I've been browsing the earlier postings to the FY6600 thread to discover when I first mentioned the need to fix this "Skoolboy Howler" which ultimately turns out to be purely an act of malice by Feeltech's chief bean counter in forcing the designer to rethink the use of the more expensive 61.1 and 249 ohm resistors chosen from the E192 0.5% range to create the necessary attenuation and find the cheapest way to satisfy the '20dB' correction for the Hi-Z case only.

 Those resistor values were no accident. They'd been chosen specifically as the cheapest way to correct the 20dB boost built into the firmware for the Hi-Z case (matching the P-P "amplitude" settings which only apply in the high Z case anyway). I'm afraid I'd over-thought the problem, giving Feeltech way too much credit for thinking up a firmware fudge to get around a BoM error that was no error at all but a specific choice at the behest of the evil beancounter in chief.  :palm:

 It seems I first mentioned it way back on April 25th of last year. Despite my thinly disguised plea for assistance in calculating a replacement resistor network, I saw absolutely no response or apparent interest in my findings. I've edited some of those early postings with my new findings simply to set the record straight purely for my own satisfaction and for any latecomers trawling these older postings but I won't be posting any updates to that undeserving lot - they'll jolly well have to trawl through the thread if they want to see these new nuggets of information or else pick up the info from this topic thread.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 16, 2020, 06:14:26 am
Johnny B Good, what is the "injection locking module"?

====snip====


 It's an alternative to the switching method (mechanical or electronic) of change over from an internal (10MHz in this case) to an external reference frequency source such as a GPSDO reference (typically 10MHz).

 Instead of using a changeover switch to go between the internal 10MHz OCXO reference clock and a 10MHz GPSDO clock plugged into an EXTL ref socket as per Arthur Dent's OCXO modification posted to the FY6600 thread about 18 months or so back, the external reference is buffered and level matched to avoid disruption to the internal reference oscillator it is injecting into in order to gently nudge it into synchronization without creating an abrupt transient that could corrupt any digital processes which rely upon this as a clock source.

 The simple act of plugging the external reference into the extl ref socket is enough to have the the function generator's internal reference lock to the external reference without further operation of an intl/extl change-over switch. Simply unplugging the external reference will release the internal reference from its locked state and allow it to free run again without further ado.

 If you're interested in further details you can check out my latest posting into my topic thread here:-

https://www.eevblog.com/forum/chat/injection-locking-the-10mhz-ocxo-to-external-reference-(upgrading-a-fy6600)/msg2956918/#msg2956918 (https://www.eevblog.com/forum/chat/injection-locking-the-10mhz-ocxo-to-external-reference-(upgrading-a-fy6600)/msg2956918/#msg2956918)

 Although there are only 3 posts into this topic thread, be warned, they are all mine and each one is longer than its predecessor ::).

I've linked to the third and final (and longest!) posting which includes the "Money Shot" image of my hand drawn circuit diagram of the injection locking module.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 16, 2020, 09:45:16 am
There are, apparently, multiturn trimpots available that fit the same footprint which could help ease the calibration process.

JBG
Interesting! I've not searched for something similar, what's the footprint name?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BlackICE on April 16, 2020, 10:40:44 am
I would also like to know what footprint for a 10 turn pot that fits.
I'm one of the "lucky" owners that had the same sine wave corruption. What BS to have a menu item to "fix" it instead of a real lasting fix.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on April 16, 2020, 08:35:44 pm
I would also like to know what footprint for a 10 turn pot that fits.
I'm one of the "lucky" owners that had the same sine wave corruption. What BS to have a menu item to "fix" it instead of a real lasting fix.

 Regarding "surface mount multiturn trimpots", I too wanted to know (where to get hold of 'drop in' replacements) so I googled the phrase "surface mount multiturn trimpots" and found the Bourns web site and countless links to pdfs

https://www.bourns.com/products/trimpot-trimming-potentiometers/trimpot-trimming-potentiometers-multiturn (https://www.bourns.com/products/trimpot-trimming-potentiometers/trimpot-trimming-potentiometers-multiturn)

https://www.vishay.com/docs/51010/ts6.pdf (https://www.vishay.com/docs/51010/ts6.pdf)

 I saw a reference to drop in multiturn trimpot replacements in the FY6600 thread a year or more back. I did have a look for the relevant posting but gave up and tried my luck with duckduckgo instead.

 I've attached a couple of pdfs

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: BlackICE on April 17, 2020, 05:22:58 am
Am I going to need a hot air gun and solder paste to replace the pots?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 17, 2020, 06:45:17 am
No it's not necessary. Put a lot of solder on the 2 legs to mantain high the temperature, then move fast to the single pin and the old pot goes away. Soldering back the new one is easy.

In any case i not know why they not put calibrations in software. Cost less to them and it's more precise. But maybe it's asking too much for who put a "repair sine" function instead of fixing a bug...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on April 17, 2020, 10:05:32 am
Someone have the device open for check what trimmer values we are searching? The original pots are in the 3x3 format, distance between 2 legs around 2mm. Maximum ext dimensions (leads included) 6x6mm.
I am thinking to glue some cilinders from the top cover to the pots and do some holes for allow adjustment while the device is closed. I've found some differences when calibrated open and when it's closed. I've used a temperature controlled pwm fan so inside the device the temp must be quite stable over the seasons
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on May 07, 2020, 12:51:29 pm
Quote

 The reason for the smaller (19.69dB) attenuation value was simply to match that of the 100/510/100 85 ohm pad's effect when the output is unloaded since Feeltech had seemingly corrected for this departure in the firmware from the 20dB they must have originally intended.  My original tests had shown less than 1mV error in making adjustments around the 500mV relay switching threshold in the unloaded test case but a massive 64mV drop in the terminated test case when going from 501 to 500mV p-p settings.

 Both channels exhibited the same pattern to within a mV or two of each other so I assumed from this that Feeltech had applied a firmware patch to correct the error introduced by using an 85 ohm pad in place of a 50 ohm pad. This correction method can only apply to either the unterminated or terminated case not both and it seems Feeltech had elected to correct for the high impedance case typical of audio frequency kit.

   INPUT DATA
 
System impedance:      Ohms 84.75                New 50 ohm impedance
Required attenuation:      dB     21.67
     IDEAL VALUES
 
Ideal series resistor:      Ohms  510.083           to keep the same db  300.932 ohm
Ideal shunt resistor:      Ohms  99.993             to keep the same db  58.993   ohm
                                                                              50ohm   @ db 21.67 


Thanks just wondered about one of your comments  the original resistor 510 100 100 Pi layout showed 21.67 db
 and you said 19.69dB. I used that calculator you used .  just add 510 & 100 in the preferred section give the ordinal data.
I have the FY6800 which also has the exact panel layout as the 6600 . I also did a lot of mods
I also noticed this error that you have been working hard to solve .. I was just adjusting the setting voltage up or down . with a bench meter 8 digit to compensate .

I congratulate you on all you work . and hours of effort .. I will try this mod for sure .
I also used laminar cooling as it gives a better air flow . used a flat fan from an old laptop and fixed it to the vertical grills at the back.
 
Please keep up the good work.
 



Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on May 08, 2020, 10:56:39 pm
Quote

 The reason for the smaller (19.69dB) attenuation value was simply to match that of the 100/510/100 85 ohm pad's effect when the output is unloaded since Feeltech had seemingly corrected for this departure in the firmware from the 20dB they must have originally intended.  My original tests had shown less than 1mV error in making adjustments around the 500mV relay switching threshold in the unloaded test case but a massive 64mV drop in the terminated test case when going from 501 to 500mV p-p settings.

 Both channels exhibited the same pattern to within a mV or two of each other so I assumed from this that Feeltech had applied a firmware patch to correct the error introduced by using an 85 ohm pad in place of a 50 ohm pad. This correction method can only apply to either the unterminated or terminated case not both and it seems Feeltech had elected to correct for the high impedance case typical of audio frequency kit.

   INPUT DATA
 
System impedance:      Ohms 84.75                New 50 ohm impedance
Required attenuation:      dB     21.67
     IDEAL VALUES
 
Ideal series resistor:      Ohms  510.083           to keep the same db  300.932 ohm
Ideal shunt resistor:      Ohms  99.993             to keep the same db  58.993   ohm
                                                                              50ohm   @ db 21.67 


Thanks just wondered about one of your comments  the original resistor 510 100 100 Pi layout showed 21.67 db
 and you said 19.69dB. I used that calculator you used .  just add 510 & 100 in the preferred section give the ordinal data.
I have the FY6800 which also has the exact panel layout as the 6600 . I also did a lot of mods
I also noticed this error that you have been working hard to solve .. I was just adjusting the setting voltage up or down . with a bench meter 8 digit to compensate .

I congratulate you on all you work . and hours of effort .. I will try this mod for sure .
I also used laminar cooling as it gives a better air flow . used a flat fan from an old laptop and fixed it to the vertical grills at the back.
 
Please keep up the good work.

 That quote is rather out of date. Take a look at my more recent posting  Reply #285 on: April 16, 2020, 05:32:26 am to discover why the solution happens to be as simple as replacing those resistors with a set calculated for a 50 ohm 20dB pad.  :palm:

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on May 11, 2020, 12:01:54 pm
Hi All,
After reading pages upon pages of so many upgrades and Ideas on how to improve the FY6600 & fy6800.
I have the FY6800 which has a few differences but is the same animal that Feeltech made a few minor changes. :palm:  and much thanks to Johnny B.Good for all his inspirations . Gave me some idea's how to improve my FY6800. and a lot of research. .. |O
 I found a small mod that may have been over looked.  :-/O
So armed with my Niger solder iron , Coffee, & roll up.  :popcorn:
I Dived in .
The first issue was the cross talk on the filter stage adding noise to the op amp AD8009 1Ghz . the FY66 uses OPA686N 250Mhz .
the circuity is the same but the pins on the AD8009 are reversed so the PCB has a small difference as to swoop over the connections . So I lifted one of the 100ohm and fixed to the neg rail junction c42 & L31 and a sort wire to pin 2 of the AD8009 this removed the interference of the track under the 100ohm going to pin 3.
I also noticed on the AD8009 manufacturers data sheet recommend a small Pf cap on pin 1 (output) which
goes to 49.9ohm resistor (FY6600 has 2 * 100ohm) and then to the relay. The relay has an odd point capacitance .
 So , I used the test point just before the first relay And the ground pad adjacent and fitted a 22pf ceramic cap
so to balance the error on this line .
The out come was I now have a Square wave that Looks .. Ok you guested .. Yes Square all the way up to 25Mhz.
Before there was a lot of top over shoot and Bottom so then it started looking like a sinish square over 12Mhz.
Now with a better shape . and less noise .
Now I have figured out the noise issue I can put some thought into the jitter . which is also less . Not gone.
But with all my spare time .
     Retirement .. LockDown  ..
         I'm going to solve this Bug ..
              With or without a Vaccine ..  >:D 
 I hope this might help some one else ..   :-+ .

The Yellow  Ch1  Without mod  ..  Blue Ch2 is With Mod  ..   @ 20Mhz  3v
in the other 2 photo's the other cap was a 10pf  but was removed  later as it was too big needs to be 2pf . aint got 1 ..
Update  change 22pf to a 10pf and added another 10pf on out of op amp pin1 . Improved quality.

Conclusion it at its Max performance but it is what it is . I have come to the state  :horse:  is a good time waster
  I think i will look for a good second hand Rigol  , HP , owen , anything thats not Feeltech .

[attach=1]
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: kmajjo on May 14, 2020, 04:41:34 pm
Hello,
I bought an an FY6900 - 60M some weeks ago. At the beginning no problem then the sine wave became strange (see attached picture).
As you can see on the joined picture , when i select sine wave form i obtain a mixte of sine  and square wave form.
I sent some emails to FeelElec complaints service without having an answer from them.
Could you help me ?
(http://)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on May 14, 2020, 09:21:45 pm
No problem. in the PC software in top menu there is a help setting Tag . Click
  Repair sine . 
this solves it .
There is a post further up with pictures . From another person   
  evava    #282 on: April 15, 2020, 12:25:47 pm   :-+

It happen to every one I also had it .

Its also nice to know That FeelTech didn't do much on the upgrades ..
 
 What's the Jitter like on the 6900 ?

 :popcorn:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: kmajjo on May 14, 2020, 09:31:38 pm

Quote
Repair sine .this solves it .

Sorry,
I don't understand your answer
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: kmajjo on May 14, 2020, 09:35:00 pm
Sorry,
Ok post #282
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on May 14, 2020, 09:39:55 pm
In the software .
Look at the other post . pictures
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: bobyeltsin on May 15, 2020, 10:10:10 pm
Here's my two cents about this unit. Yes, it is value for money. The specs are there, the community is there, but holy shit is this a tinker toys implementation of a function generator. The housing is crap. The power supply is crap. It uses salvaged parts from the gray market. I've had to fix the PSU, correcting some serious safety flaws. Just replaced a faulty rotary encoder within one month of (lightly) using it, and the construction looks like an underground student project. But still, it works, and it does the job, but it is a high high maintenance product. buyer be aware.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Ronnyvs on May 24, 2020, 11:08:01 pm
First of all,
Hello everybody!!!

i also got my 6900 last week(25 may 2020) ... after one day i also had an interrupted sine... before buying i read many threats, so i thought lets do the sine repair in the help function....
too bad!!!
After clicking "repair sine" the damaged sine did an inversion of 180 deg. (upside down) hmm... i clicked for the 2nd time "repair sine" but nothing happened except now the device acts very very very slow.... and no signal at all at the outputs.
turning device out and in (several times) didn't help...

so i enjoined my device literally a few hours.
Of course i sent an mail to the UK-seller of banggood and i sent a few mails to Feeltech.
Most of the forum readers do know the answer already.... NO ANSWERS!!!

According to the irritation i bought an Siglent generator last Friday (of course better device ,other money)

But for the FY6900...
Hopefully Feeltech or the seller will respond my mail and come with a solution
it would be a pity to throw it at the junk yard after a few hours of fun for a few bucks...
but i would like to get it working again...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on May 27, 2020, 02:17:55 pm
Hope you get a Get a refund ..
BTW which Siglent  did you get .. Just curios ..

I guess that the 6900 did not get any upgrades except better magic smoke . >:D

Return it . to the seller its still $$
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Ronnyvs on May 28, 2020, 09:43:04 am
Hi Labrat,

I don't want my money back, because i still believe in the product.
If it's doing what they tell what it's capable of, then it's still worth the money.
a lot off features for a little price...

so I'm not not arguing the product but the problem off how he seller and reseller deals with some products or complaints...

therefore i'll hope i get a new one, or the they give me a solution how i'm able to repair or re flash the firmware....

about you curiosity ...

I bought the Siglent SDG830.... (only one channel) but for now it's good for what i have to do with it...
software and hardware looks solid and reliable and when you take it in your hand ,then it also feels like a real device...

regards,

Ronny
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on May 28, 2020, 12:37:49 pm
I would recommend you read some of the previous threads
search FY6600  its the same as what you have basically different box and a few pore updates
Look at Johnny B Good , Myself , Arthur Dent, and many more. about 3 years of blogs covering most of the problem.
Feeltech is also at the top of this blog . but there are many more .
I have the 6800 @ 60mhz also had a few problems ie the power supply went up in smoke after an hour. :wtf:
So you are not alone . but I would read the others sections . Not in this blog .
Good luck there is a lot to read
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Ronnyvs on May 29, 2020, 09:46:51 am
Hi,

As you can read in my other thread, i did read all the threads in some forums. depending the hardware problems i can resolve several things... so that was for me the reason that i wanted to buy such an 6900....
some small software issues arne no problem either... i did consider the price according to what you get... and i still think that good... so depending on that i would buy an 6900 again...

Hopefully banggood and feeltech would also cooperate to a good solution with the broken generator...

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on May 29, 2020, 02:22:39 pm
Because feelelec knows of the problem of the sine wave that is corrupted and they added an option in the menu, that the only thing it does is to invert it, if it is run again the equipment is damaged, they do not release a firmware update and problems end. Also they do not participate here in the forum providing solutions, I have a 20Mhz fy6900 for now, everything is fine, but it is scary to use it, I already lost a fy6600 that they never solved the problem for me, being in guarantee. |O

in spanish
Porque se feelelec sabe del problema de la onda senoidal que se corrompe y agregaron una opcion en el menu, que lo unico que hace es invertir la misma, si se le ejecuta de nuevo se daña el equipo, no liberan una actualizacion de firmware y se terminan los problemas. Ademas ni participan aca en el foro  aportando soluciones, yo poseo un fy6900 20Mhz por ahora todo bien, pero da miedo usarlo, ya perdi un fy6600 que ellos nunca me solucionaron el problema estando este en garantia. |O
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Quarlo Klobrigney on May 29, 2020, 03:47:44 pm
Still waiting on mine. it'll be a month tomorrow with non-specific tracking from Feeltech China to the US. How long would it take normally? Does anybody know? Hopefully after this arrives it won't be a dog's breakfast.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Ronnyvs on May 29, 2020, 08:54:06 pm
A company can only exist if it is treating his customers at the right way...
if your product is not working well, that's not a problem. if you try to solve the problem that's nice and good...
But a company can't exist without any customers... so,
one way or another feelelec wil respond , or they will lose sooner or later their company because the way their behavior...

I always believe in people and i still do. That's why i also think that Feelelec would make the right choice to help their customers.

customers do have a thousand company's where they can sell, but Feelelec is just one of them... 

Feelelec, you started this forum thread, help your customers and end this thread in a proper manner...

hopefully , in the future, we could talk about your products the way it should be. Nicely with the comments positive and sometimes a little less, but always at a worthy way!


 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: nctnico on May 29, 2020, 09:50:42 pm
A company can only exist if it is treating his customers at the right way...
if your product is not working well, that's not a problem. if you try to solve the problem that's nice and good...
But a company can't exist without any customers... so,
one way or another feelelec wil respond , or they will lose sooner or later their company because the way their behavior...
There is a sucker born every minute...

Still if your device doesn't work then file a complaint for a refund. I don't know how you bought it but you shouldn't let the opportunity to file a complaint to get a refund pass. Do not fall into the trap of being strung along long enough for the period to file a complaint pass. That is the number 1 rule when buying stuff from China.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Ronnyvs on May 30, 2020, 09:14:39 am
Nctnico,

It looks like you don't understand the message i wrote....
I'm not complaining about any refund or anything else. I got an arrangement with Banggood  and they offert me almost immediately an propose of a new device or money refund.

so according to that, nothing to complain!

it was a message which will affect on every company, and in this forum especially to Feelelec.

And about buying stuff in china....
Not everything goes well, but actually i do a lot of business directly with China  for almost 15 years.
And my experience is quite good... mostly good and fast reply of messages, price-arrangements are reliable, even so the delivering as well.






Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: nctnico on May 30, 2020, 04:42:37 pm
it was a message which will affect on every company, and in this forum especially to Feelelec.
Well, that part is only partly true. Most people look at the price only and keep buying mediocre stuff. So in the end the largest market share will not be held by the company offering the best quality or service but by the company which delivers products which are OK-ish for the price. You see that with many Chinese equipment manufacturers; they dial in quality & service to the point of biggest profit.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: kjpye on May 31, 2020, 03:45:04 am

 You see that with many Chinese equipment manufacturers; they dial in quality & service to the point of biggest profit.
[/quote]
Every (successful) manufacturer does the same thing. You find a market niche not being filled by somebody else.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TechieTX on May 31, 2020, 09:57:14 pm
One thing I'm curious about: 2 pages back in post #257 masterx81 said he'd bought a new 6900 and it had firmware 1.3.1.

Anyone tried updating?  Does it actually update?

I've been periodically checking this thread since January.  Call me crazy, but I don't trust their response of "Our latest version is 1.3, and 1.3 supports online upgrade." based on design flaws and history.  Until I see something from a real user along the lines of "yes, it updated and didn't brick my sig gen" then I'm holding off buying one.  That 'repair sine' feature doesn't give me a warm fuzzy about their coding competence.   :-\

Additionally, someone had mentioned elsewhere 15WV electrolytics on the 13.5V supplies in the stock PSU.  Whichever bargain bin engineer specified them apparently has little understanding of MTBF.  Sounds like the PSU is designed to last for about a month of continuous operation.  Google:"load life rating" and the first hit will give you a hint why that's a Bad Idea.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 10, 2020, 10:54:10 am
I'm a owner of this FY6900 (labeled KKMoon but we learned that this is all the same)
After some month of use I'm happy with regards to price and function.
I read all the forum posts regarding this device and learned a lot with special thanks to JBG.
I decided to keep the PSU but I replaced the weak cabling (see photos attached)
and replaced the terrible ground connection by a better 5.6k resistor connection (in the black heat shrinking).
I also build in a 40mm vent (12 V) and connected it to the new fan connector (5 V). I used hot glue for the mounting - no screws and let it blow the
air into the device. It's performing very well without any noise.

And with the hint from the forum I upgraded this incredible piece of sh... software (running as Admin)

At this time I discovered how worth the 10 MHz time base is. The (TC??)XO is a surface mounted 3.3V module.

Because I do not own one of the fancy HP counters I checked it against the 1pps of a UBLOX Neo 6m and calculated
a difference of 18,1 ppm. So I looked at EBay and found a appropriate 3.3. V OCXO for 16€ (incl. delivery).

But how to check this OXCO? I measured it's frequ with the FY6900 and recalculated it against the measured failure and got
a failure of 0,238 ppm. That's not far from the failure of a locked Neo 6m.

So far so good. But I was curious to measure it the direct way. The counter function of the FY6900 is ok, it runs till 999.999.999.999.
But you have to start, stop and clear it manually. I looked around but found no information in the manual and my tests with the trigger input
didn'd find any results. Has anybody checked this and found an undisclosured functionality of the FY6900 for gating the counter?

So I decided to breadboard a poor man's gating. With the help of an 74S74 and an 74S37 I triggered the flipflop with the 1pps and gated
always the 74S37 for the OCXO 10 MHz to the counters input.

So you can stop it after (2x) 1s, 10s, 100s ... to get the readings.

With this small setup I got the OCX= frequency by 9.999.998,54 Hz (after warming up for 1 hour). This fits to my recalculated value not too bad!

The OCXO takes about 500 mA at 3.3 V. I do not think that the integrated PSU can provide this additional power but I'll check it.

Some photos attached fyi.



Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on June 10, 2020, 09:08:37 pm
 A very nice post, Bad_Driver :) and my thanks to you for providing details of your modifications and your proposed replacement of the original 10MHz smd XO ic with an OCXO (at least you don't have to mess about with a 3N502 clock multiplier chip as owners of the 66 and 68 models had been obliged to do with their 10MHz OCXO upgrades).

I'm a owner of this FY6900 (labeled KKMoon but we learned that this is all the same)
After some month of use I'm happy with regards to price and function.
I read all the forum posts regarding this device and learned a lot with special thanks to JBG.
I decided to keep the PSU but I replaced the weak cabling (see photos attached)
and replaced the terrible ground connection by a better 5.6k resistor connection (in the black heat shrinking).
I also build in a 40mm vent (12 V) and connected it to the new fan connector (5 V). I used hot glue for the mounting - no screws and let it blow the
air into the device. It's performing very well without any noise.

 Aw, shucks! You're embarrassing me now :D

 Although that tiny smpsu board has received much criticism, I still have some doubts as to whether the criticism is sufficiently justified to warrant its replacement with a "Better Kwality" cased smpsu or a DIY'd analogue solution so I'm holding fire on such a "PSU upgrade" until I finally get around to running those tests using battery power that I've been meaning to do these past 12 months or so.

 I've had the 12AH SLA (and a 7805) several years prior to even discovering the very existence of the FY6600 and have since purchased a couple of 6v lantern batteries for the negative supply rail some six months ago now. The problem is that I've had more pressing needs to attend to (such as DIY GPSDOs and their little side projects) to deflect me from performing the battery power testing needed to both prove the need to upgrade the smpsu board but also to provide a baseline against which to test the performance of replacement PSU solutions. I don't want to just rush into a psu upgrade project based on (possibly unwarranted) assumptions alone.

 That little 5 volted 12v cooling fan makes a considerable difference to the internal temperature despite its modestly quiet airflow performance. It doesn't need much airflow when the case venting arrangements more or less completely cancels out what little thermosiphon cooling effect may exist, especially when tilted up on its bail stand. For anyone even so much as considering a replacement DIY analogue psu, a cooling fan is an absolute prerequisite (cooling fan first then, maybe a psu upgrade later).

And with the hint from the forum I upgraded this incredible piece of sh... software (running as Admin)

 That bit of news should reassure TechieTX then.  ;)
 
At this time I discovered how worth the 10 MHz time base is. The (TC??)XO is a surface mounted 3.3V module.

Because I do not own one of the fancy HP counters I checked it against the 1pps of a UBLOX Neo 6m and calculated
a difference of 18,1 ppm. So I looked at EBay and found a appropriate 3.3. V OCXO for 16€ (incl. delivery).

But how to check this OXCO? I measured it's frequ with the FY6900 and recalculated it against the measured failure and got
a failure of 0,238 ppm. That's not far from the failure of a locked Neo 6m.

 That 18.1ppm error comes as no surprise (btw, I think where you've used the word "failure", you actually mean "error" ;) ).
It's just an XO btw. A TCXO would normally have a trimmer to adjust it to within the typically claimed +/-0.1ppm margin of error.

 That OCXO looks just like my 10MHz CQE 12v OCXOs. It should have a VFC pin to allow it to be electrically tuned (typically over a range of 1 to 4ppm). Looking at the images you attached, I couldn't see any connection to this VFC pin which I'm guessing is likely floating around the mid Vcc point (~1.6v) since it has settled so close to its marked frequency.

 You can put a trimming pot across the supply rail and connect the slider to the VFC pin and trim it to within a few hundred ppt of 10Mz (a three orders of magnitude improvement on its current calibration). Even with a 25 turn trimpot, you'll likely need to pad it out at one or both ends to concentrate the adjustment range closer to its 10MHz frequency (and this relies on having a very stable 3.3v supply feeding the trimpot). For now at this experimental testing stage, you could use any handy 5 to 50K potentiometer to improve on no trimpot at all.

 The fifth pin (there's usually a fifth pin whether or not it has any function) may be a voltage reference (possibly 1.8 or 2.5 volts from the built in LDO supplying the oscillator circuit itself, or maybe just a 2.5 or 3.0 volt source from a tightly temperature controlled precision bandgap voltage reference for use elsewhere by whatever other circuitry it is attached to.

 The only type of high precision bandgap voltage reference that performs better than a temperature compensated one is a temperature controlled high precision bandgap voltage reference which your typical OCXO has in spades. As long as you don't try to use it directly as a stabilised supply to power even low power logic, it's likely to outdo any other alternative high precision voltage source you might otherwise employ.

So far so good. But I was curious to measure it the direct way. The counter function of the FY6900 is ok, it runs till 999.999.999.999.
But you have to start, stop and clear it manually. I looked around but found no information in the manual and my tests with the trigger input
didn'd find any results. Has anybody checked this and found an undisclosured functionality of the FY6900 for gating the counter?

So I decided to breadboard a poor man's gating. With the help of an 74S74 and an 74S37 I triggered the flipflop with the 1pps and gated
always the 74S37 for the OCXO 10 MHz to the counters input.

So you can stop it after (2x) 1s, 10s, 100s ... to get the readings.

With this small setup I got the OCX= frequency by 9.999.998,54 Hz (after warming up for 1 hour). This fits to my recalculated value not too bad!

The OCXO takes about 500 mA at 3.3 V. I do not think that the integrated PSU can provide this additional power but I'll check it.

Some photos attached fyi.

 I'm not aware of any hidden counter functionality in any of this series of function generators (FY66. 68 and 69) but your frequency counter lashup (gating the counter from the 1PPS on a 100 seconds measuring interval) should give you pretty fair accuracy considering the NEO-6M's 21ns jitter and the random peak phase drift of up to 30ns imposed by ionospheric effects on the SV signals over a 100 seconds gating time.

 You made a wise choice by using the 74S series (110MHz typical clocking speed for the 74S74 versus 33MHz for the 74 and 25MHz for the 74LS with sub 10ns switching speeds). A lot of the propagation delay should cancel out, leaving most of the uncertainty in the GPS domain.

 All that's missing from your test setup is a calibration trimpot to tune the OCXO to within 30ppt or so of its specified 10MHz frequency with something to insulate it from random draughts of air (and also reduce its "at temperature heating demand" which is likely to be around the 180 to 200mA mark).

 Most of the 3.3v OCXOs I've checked out, seem to demand around 1 to 1.2A heat up current which gets them to operating temperature in around 3 minutes or just under. That 500mA initial warmup demand, whilst kinder to your 3.3v supply, means it's likely to take a good (or bad iyswim) 5 to 6 minutes to get to temperature.

 Your biggest hurdle to using this OCXO in your FY6900 is going to be finding the extra 1.4W (possibly as much as 3.6W if that 500mA is due to a current limit in the 3.3v supply), let alone the at temperature demand of 600 to 800mW. Others doing this upgrade with the older 12v OCXOs took advantage of the horrible imbalance in maximum current ratings between the negative and positive 12v rails of their replacement smpsu upgrades putting the doubled or tripled rating of the plus 12v rail compared to the puny rating of the negative rail to good use, powering their add-on OCXO.

 Since I didn't want to be rushed into upgrading the PSU to one of these overspecified smpsus just for the sake of finding the additional 280mA at 12v for my OCXO, I simply gutted the innards of a small Linksys 12v 500mA wallwart and mounted its tiny smpsu board inside my function generator, wiring its mains input directly to the C6 mains socket I'd used to replace the cheap 'n' nasty 2 pole C8 socket. This not only neatly solved the power issue, it also allowed me to leave the OCXO powered up regardless of the mains on off switch state all the time it remained plugged into a wall outlet.

 The only fly in this ointment being that, despite the foam rubber 'overcoat' on an ovenised XO, the overnight drop in temperature was still enough to result in a 200ppt drift in frequency which takes a couple of hours to settle down. It's only a minor irritation (a mere 0.2ppb error) since there's no warm up delay on subsequent power up as there would otherwise be if everything had been powered down overnight (plus, it's never a good idea to subject an OCXO to needless temperature cycling anyway).

 I could use the front panel standby 'on/off' button to minimise this effect but since it only reduces consumption from circa 7W down to around 5W (instead of the 1.3W taken by the OCXO and its smpsu board alone), I prefer to just switch off at the back when I've lost interest in maintaining the frequency to within +/-30ppt to monitor the deficiencies of a basic GPSDO relying on a cheap u-Blox  navigation module, prey to the timing errors imposed by the varying ionospheric conditions.

 I'd love to replace the M8N with an M8T or even a 6 or 7 T model but all bar the ancient 5T carry a hefty price premium (around a £100 extra for one of those PixHawk units still blessed with a 6T rather than the more up to date (and better suited to the navigation demands of a drone) M8N. Long gone are the days (back in 2016) when the 6T PixHawk kit could be had for just a modest 30 quid :'(

 I've attached a couple of photographs of my much modded FY6600 - It's starting to get just a little crowded in there. ::)

 Top left hand corner shows the plastic ex-wallwart case half (chosen simply because was the right size and could take a couple of self tapping screws to hold it down to the base of the case) into which I hot glued the PCB of another wallwart (that half amp 12 volt Linksys one I mentioned). This is wired to power the OCXO (bottom LHS of the picture). The OCXO's output feeds the injection locking module located in the extreme top RHS which allows an external 10MHz reference to gently lock the OCXO to its frequency, which signal is then passed onto the 3N502 sitting right where the original 50MHz XO chip used to reside.

 A preliminary search for suitable 30VA R-Core transformers to make up a replacement PSU based on buck converters rather than those miniature space heaters commonly known as 7805, 7812 and 7912 voltage regulators (or modern day equivalents) suggests it may be possible to shoehorn one into the space now occupied by the PSU board (sandwiched between the fan and OCXO).

 Since this psu upgrade will also be able to power the OCXO, a dedicated OCXO psu board will no longer be required, freeing up a little more space for components of the new psu (assuming my planned battery tests indicated any merit in such an upgrade). IOW, whilst it does seem rather overcrowded in there, it does look like I should be able perform a PSU upgrade without imposing too much disruption on the existing layout. However, that's a low priority right now - I've got enough side projects to keep me busy for a while yet before I revisit this particular "Can of Worms".

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 11, 2020, 07:30:32 am
Thanks Johnny for your long reply!

I read all you postings regarding the Feeltech FY series and the idea for my accomplished and planned modifications came from your
postings! And sorry for my failure/error/mistake. I'm not a native speaker and I have to help myself with my east german school english!
(and by the way: cool nick name with respect to a great song - I especially like it in the version of Jimi H.)

Unfortunately  the bought OXCO has no Ref.Volt.Out and no adjustment (the pins are still there) - see attached data sheet of
the vectron OC-160-DAB-308BF. I wasn't aware of that but for my first tries it works out for me. Later I can go ahead with a better one.
But I'm impressed how carefully you watched my pictures.

To be honest: For my needs the FG works fine, I'm a hobbyist but I like good tools. So I bought some weeks ago the new Siglent SDS 2000X Plus
and with the "improvements" from the dedicated forum I own now a 500 MHz oscilloscope  :-DD And with it's measurement function I discovered first
the freq-error of the FY. And there is a german saying: "Der Weg ist das Ziel" - which means that it's all about the way and not about the final result

I'm coming as hobbyist from Audio electronics, renewal of old HiFi equipment as  a REVOX Tape Recorder, amplifiers and such stuff. During my University time I
worked with digital electronics and Zilog Z80 in the 80s. Then I were for 20 y out of E-business and restarted as hobby some years ago
.
2 years ago I started with Arduino and played around with GPS. I have a lot respect of everything > 1 MHz and I try here to improve my knowledge.

Regarding the PSU I'm with you. It makes no sense to follow all the suggested improvements without any idea what can be achieved.
In my head is a very simple approach. On my shelfs are dozens of old Laptop PSUs with enough power for everything but unfortunately only one voltage.
So I looked around and found TPS5430 based ready to use solutions at EBay (see attached photo)

What do you think about this: using an external 19V Laptop PSU (no problems with grounding and security anymore), inside a TPS5430-based PSU
adopted to 2x13,5 V and another cheap Step-down-converter for 5V?? It's the cheapest way to (hopefully) improve the PSU of the FY. If there is enough
place and need for further "cleaning" you can bring another analog regulation behind the switching one. And I get enough power for any OCXO as well.
I played around with such a solution for a headphone amplifier which needs +/+16 volts and it works very well.  :bullshit:

But my main restriction is time. I'm still working (more than full time and with a lot of travelling) and have family. So I have to look for some hours to come forward with my projects.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on June 11, 2020, 08:52:45 pm
I'm a owner of this FY6900 (labeled KKMoon but we learned that this is all the same)
After some month of use I'm happy with regards to price and function.
I read all the forum posts regarding this device and learned a lot with special thanks to JBG.
I decided to keep the PSU but I replaced the weak cabling (see photos attached)
and replaced the terrible ground connection by a better 5.6k resistor connection (in the black heat shrinking).
I also build in a 40mm vent (12 V) and connected it to the new fan connector (5 V). I used hot glue for the mounting - no screws and let it blow the
air into the device. It's performing very well without any noise.
Its same as the FY6600/ 6800  just the case

 MY one is the FY6800 @ 60Mhz
Hi You would be better reversing the fan to suck the air though and out . All electrical equipment use this method
as it give better uniformed cooling .
Plus I have also done a mother load of upgrades
I  followed JBG ideas and ArthurDent  with a few extras mods of my own .
 I upgrade the power supply to to be 80% efficient  to run the 20Mhz OCXO  0.02PPb  .
apodoses to the 10MHZ
Mounted in a thermal case . also added 333 ohm resistor to the trigger BNC so I could use the internal counter on the
coupled mode set at DC. . to check stability
Added 2,  10nf caps on the buffer op amps to compensate for the relay contact noise on the square wave.

 I have one more mode still on the drawing board .
at the moment its working almost dam close to perfect . ^-^

 It also passes ArthurDents test as well  123456789Mhz   :-+

 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on June 12, 2020, 12:30:18 am
Thanks Johnny for your long reply!

I read all you postings regarding the Feeltech FY series and the idea for my accomplished and planned modifications came from your
postings!

 Some might consider you a 'glutton for punishment' for admitting that.  :)

And sorry for my failure/error/mistake. I'm not a native speaker and I have to help myself with my east german school english!

 No need to apologise! Your written English is far better than my written Spanish (Español) and I managed to obtain a CSE (Certificate of Secondary Education) grade 1 pass (regarded as the equivalent of a grade 4 pass in the higher GCE (General Certificate of Education) exam standard of the late '60s here in the UK).

 I sometimes spot similar errors when I proof read these missives of mine (and I'm a native English speaker!!! :-[ ). I wasn't being critical, just contributing a bit of feedback to help you perfect your written English skills.

(and by the way: cool nick name with respect to a great song - I especially like it in the version of Jimi H.)

 It's a pseudonym I came up with when I started posting to usenet news groups. Not my first (ill considered) choices of pseudonym but my 2nd or 3rd by which time I'd decided to use one that at least would be pronounceable when read out loud (and more easily remembered) with a loose connection to my actual name (John).

 Many of the pseudonyms seen in EEVBlog postings seem to be based on electronic components without much regard as to how awkward and clumsy they might be for their respondents to use as a means of address in any replies. I know a name, real or pseudonym, is just a label which can be any unique combination of letters and digits. Since we're human rather than machines relying upon simplistic labelling algorithms where any jumble of letters and digits will suffice to uniquely specify a label, I'm left wondering at this predilection for machine friendly labels instead of the more easy for humans to remember labels such as Johnny, Frederic, Alfred, Alphonsus Liguori, Cuthbert and suchlike?  >:D

Unfortunately  the bought OXCO has no Ref.Volt.Out and no adjustment (the pins are still there) - see attached data sheet of
the vectron OC-160-DAB-308BF. I wasn't aware of that but for my first tries it works out for me. Later I can go ahead with a better one.
But I'm impressed how carefully you watched my pictures.

 You've fallen into the trap that OCXO always means VCOCXO when the reality is that it only typically means VCOCXO and can, as you've just discovered, sometimes just mean literally "What it says on the tin.".

 Strictly speaking, what you had been shopping for, was a VCOCXO but when you try using that as a search term, you end up missing most of the VCOCXOs on offer simply through them being mislabelled as OCXOs for the sake of descriptive brevity under the quite reasonable assumption that an "OCXO" without such a VFC pin is about as much use as an armless Handyman (i.e. Pointless!).

 TBH, on a package that size which includes the most expensive part of the VFC circuit, the pin itself, the startling omission of the varactor diode and smd resistor network is, imo, sheer criminal negligence, no doubt perpetrated at the behest of the manufacturers' bean counters looking to shave a cent off the cost off a 50 dollar part. :palm:

 It's rather unfortunate that such ambiguity from the common use of the label OCXO to describe both OCXO and VCOCXO types can lead to such purchasing errors when the buyer fails to check this very point. When purchasing from major electronic component suppliers such as Farnell and Digikey which list OCXOs by the thousand, it's easy enough to check whether you're looking at a fixed or tunable type (once you've found the appropriate data column in a page and half wide table!).

 If you're looking at an Ebay offering and it doesn't explicitly state which type it is, you'll need to message the seller and ask them to clarify this point. That way, you have it in writing should the part supplied not be as they described, allowing you to extract a refund either directly or via Ebay's money back guarantee.

 As for the non-functioning Vref pin, whilst a bit of a disappointment, it's far less of an issue. My very first ever VCOCXO which I bought last year at the Blackpool Mobile Radioham rally for the princely sum of 4 quid had a Vref and a VCF pin. It was a 13MHz CQE unit rather than the 10MHz VCOCXO I'd actually wanted to purchase. I bought it anyway since it had been the only OCXO of any sort I'd seen anywhere on sale at that event and any OCXO was better than nothing, especially at such a low price. It would at least give me a VCOCXO to experiment with whilst I tried to track down a more suitable one at a less than exorbitant price on Ebay and I had a strong hunch that I could use it to generate a 10MHz reference locked to its 13MHz output with just the right mix of TTL magic if needs be (in this case, I wasn't wrong - the proof sits atop of my component drawers stack on my workbench).

 I mention this DIY GPSDO project related trivia simply because I couldn't track down a data sheet to identify its pin outs nor its operating voltage (5 or 12 volts???) other than for a 12v 13MHz Vectron which helped for the pin outs but left me in the dark over its required operating voltage. However, this search for a datasheet did lead me to a UK based Ebay trader selling the 12v 10MHz version of this 13MHz CQE OCXO for just 99 pence more than I'd paid for that radioham rally bargain. I chanced 19 quid on three (£14.97 plus £4 P&P) which all tested good when they arrived just a few days later.

 I then immediately placed an order for four more. At a fiver each, one can never have too many, plus bulk ordering saved a little on the P&P costs -2 quid for the first one and a quid postage for each additional unit - in this case, a total order cost of £24.95. These also tested good and I now have my "Lifetime's Supply" of CQE 12v 10MHz VCOCXOs. :)

 Meanwhile, I had already lashed up a divide by 13 test circuit on a solderless breadboard sandwiched between times two and times 5 clock multiplier stages to prove I could actually generate a precise 10MHz from the original 13MHz OCXO which I had decided to treat as a 5 volt part rather than risk literally blowing my 4 quid investment with a dose of 12 volts.

 I only had a relatively crude means of applying test voltages above the 5 volt mark to test with at that time, plus it was my one and only working OCXO and since it seemed to function ok on a 5 volt supply anyway, even if it was taking around 8 minutes to warm up, I decided to play safe and assume it was actually a 5 volt part after all rather than risk going beyond the 7.6 volts I'd already taken a chance with.

 The way the square wave voltage had been increasing with supply voltage, some 2v p-p shy of the supply rail voltage, implying a never seen by me in any OCXO datasheets of a p-p voltage of 10v on a 12 volt supply, did strongly suggest that this 13MHz unit was in reality a 5 rather than a 12 volt part best not subjected to any further voltage abuse. I have, and still do, treat it as a 5 volt part to this day.

 However, I'm working on a MK II GPSDO based on one of the 10MHz units and a simplified construction on copper clad board using 'squashed bug' style IC mounting to replace the current setup built onto veroboard (strip board) using the 13MHz OCXO with its associated collection of power rail polluting TTL to generate a rather jittery 10MHz reference which had required the addition of a 10MHz XTAL between the LPF and the output socket to tone down the jitter to a more acceptable level. This MK II version should be a vast improvement over its predecessor in spite of it being essentially the same basic analogue filtered hardware PLLed design.

 Once I have this later version up and running, I'll be pulling that 13MHz OCXO out once I've collected enough test data comparing the old and the new units to run more supply voltage tests (to destruction if needs be) now that I have a suitable variable voltage bench supply to test with. I've had a growing suspicion these past few months that my "5 Volt" OCXO may actually be a cunningly disguised "12 Volt" part after all. Now that I have a 12v 10MHz OCXO, along with half a dozen working spares, I can now well afford the risk of blowing my 4 quid investment away in a 12 volt testing 'accident'. >:D

To be honest: For my needs the FG works fine, I'm a hobbyist but I like good tools. So I bought some weeks ago the new Siglent SDS 2000X Plus
and with the "improvements" from the dedicated forum I own now a 500 MHz oscilloscope  :-DD And with it's measurement function I discovered first
the freq-error of the FY. And there is a german saying: "Der Weg ist das Ziel" - which means that it's all about the way and not about the final result

 Well, you don't exactly need to spend  £2,736.00 on a SDS2000X Plus 350MHz 4CH DSO to measure that sort of frequency error  :) You could have made do with a £360.00 SDS 1202X-E (I paid a fiver more just over 18 months ago for mine) and a €20.00 u-blox NEO M8N to provide a cheap yet ever so precise (if a little jittery) 10MHz reference to compare against the FG's output (just tune the FG for 'zero beat' around a 180mH away from the 10MHz setting in your case).

 The English expression is: "It's morel about the journey than the destination." That's ever so true of Life's journey with its unchanging itinerary: "You're born, you live, you die.". It would seem you're travelling First class whilst I'm happily making do with 'Economy Class'. :)

 The frequency counter display, top right hand corner on these SDS models, is a hardware frequency counter display (6 digit for the SDS1202X-E and 7 digit for the SDS2000X Plus series) which is more accurate than the software based measurements display. When I first got my M8N to finally get a usable lock (the built in patch antenna had been demoted to an ornamental badge courtesy of all the circuit traces underneath its ground plane grossly overloading the tiny LNA with self inflicted RFI, effectively blocking all SV signal reception.

 It was only when I tried a 3/4 wavelength wire antenna shoved into the SMA socket that I finally started seeing SV signals several days after I had taken delivery and several days prior to a separately ordered Active mag mount patch antenna with 5 metre cable being posted through our letterbox.

 Once I was able to get the M8N module to lock onto satellites and allow me to program the PPS line to a 10MHz 50% duty cycle, I could finally check the accuracy of that SDS1202X-E DSO's hardware frequency counter for the very first time, discovering that it was some 300Hz high (10,0003MHz). This error reduced very slowly over the next 6 to 9 months, reaching the point where it now continues to give readings of 10,0000MHz on a 10MHz reference frequency.

 I very much doubt that Siglent calibrated it with precisely the pre-aging offset required to let it settle "exactly on frequency" after 9 months to a year of service. They may possibly have given it some deliberate offset to allow for an average amount of ageing drift but the fact that mine, within the limits of the display resolution (6 digits' worth), is now 'spot on frequency' must surely just simply be a matter of pure dumb luck.

 I would be a little leary of relying on a brand new Siglent DSO's hardware frequency counter to provide accurate frequency readouts even within its own modest 6 or 7 digit resolution limit. It's useful for showing 'ball park' readings by way of a quick sanity check but if you need better accuracy you'd do better to use the frequency counter function of an FY6600 with calibrated to better than 1ppb OCXO reference on a 100 second gate time.  >:D

 I've got mine measuring the GPSDO's 10MHz +11.5dBm sine wave output (not connected to the external reference socket - the FG's OCXO is running free) on a 100s gating time and the final digit is alternating between 1 and 0. On average, it's over-reading by 5mHz but that might be something to do with it claiming to be detecting a 56% duty cycle.

 This may or may not be true of the actual sine wave output from my GPSDO. The 10MHz square wave output coming from three of the 74HC14 hex Schmidt trigger inverters via 150 ohm resistors connected to the LPF filter via a 100nF capacitor to remove the DC component further filtered by a 10MHz crystal tuned to its series resonance in series with the output from the LPF I'd have thought should have well and truly removed any such duty cycle imbalance but I'm open to learning new and startling facts in regard of converting square waves into pure sine waves.

 I may have missed a trick or possibly it's merely a defect in the FG's frequency counter input circuitry. It'll be interesting to repeat this test with the MK II GPSDO as my source of pure 10MHz sine wave test signal.

I'm coming as hobbyist from Audio electronics, renewal of old HiFi equipment as  a REVOX Tape Recorder, amplifiers and such stuff. During my University time I
worked with digital electronics and Zilog Z80 in the 80s. Then I were for 20 y out of E-business and restarted as hobby some years ago
.
2 years ago I started with Arduino and played around with GPS. I have a lot respect of everything > 1 MHz and I try here to improve my knowledge.

 Well, it's a similar story here. For a change, I won't bore you with the gory details suffice to say that FeelTech's bean counter led cheapskate cost cutting measures are like an old old friend. Even Akai have managed to perpetrate some staggeringly stupid bean counter induced tricks on their flagship tape decks (the cost cutting clipping distortion inducing trick used to save pennies on the dolby record and playback boards in a 500 quid GX630DB and the idiocy of using a rubber drive belt between the rubber faced tape counter idler to drive a separately mounted optical tape counter sensor rather than mount the sensor directly onto the idler wheel shaft saving both costs and improving accuracy (the very opposite of the usual bean counter trick :wtf:) feeding an electronic counter which could be set to show footage or hours minutes and second's worth of tape used or remaining on their even more flagship GX747 bi-directional record and playback 4 track stereo deck both of which had sideband scrape noise and wow and flutter figures well below the likes of Revox and their ilk.

 I still have those tapedecks. The later GX747 (originally bought to replace my much modded but stolen GX630dB) got packed away into its original box barely used (no Dolby noise reduction) nearly forty years ago when I was reunited with my beloved (I'd invested a lot of energy in various modifications) GX630DB hardly the worse for its year or so spent in the hands of a "Fence". This is still sitting on top of one of my speakers gathering dust waiting for me to get round to resuming my 30 year old tape digitisation project. I may well get back to it one of these days but don't ask me when.  :(

Regarding the PSU I'm with you. It makes no sense to follow all the suggested improvements without any idea what can be achieved.
In my head is a very simple approach. On my shelfs are dozens of old Laptop PSUs with enough power for everything but unfortunately only one voltage.
So I looked around and found TPS5430 based ready to use solutions at EBay (see attached photo)

 The thing that puts me off using such laptop charging bricks is the possibility that they may introduce switching noise which could see any analogue or buck converter regulators as an easy open pathway onto the 12v rails. They might not be as big a problem as I fear but be prepared to test for any such possible 'surprises'.

 The main issue with mains voltage smpsus is this business of switching a 170 to 340vdc HT supply to use a ferrite transformer to step down the voltage and galvanically isolate the low voltage output from the incoming mains supply. Unless this transformer has had an extra penny or two spent on adding a screening foil between the mains side windings and the low voltage output winding(s), a lot of high frequency switching energy will be coupled via the interwinding capacitance from the high voltage pulses onto the low voltage secondary windings producing a significant amount of common mode interference on the LVDC output wiring.

 This is certainly the main issue with the psu board used by FeelTech in their function generators (that troublesome Y cap is intended to divert these common mode currents straight back to the source where they belong. Unfortunately for us humans and any sensitive DUT, this source is a high voltage DC modulated with the mains voltage waveform. The cap filters the DC component but this leaves us with a very high impedance (1.6M ohm for a 1nF Ycap) half mains 'touch' voltage. An irritating annoyance for us humans but an ESD risk to any sensitive DUT not already cross bonded to the BNC ground prior to connecting to its test point. That 5.6K grounding resistor neatly shunts this touch voltage to less than half a volt whilst neatly avoiding the creation of a low impedance mains earthing loop.

 I checked out the TI datasheet on the TPS5430 you mentioned. It's actually (primarily) a buck regulator chip. Obviously the circuitry around the negative rail chip has been rearranged to provide an inverted boost output topology, sacrificing some efficiency and output capability and the inevitable increase in ripple voltage on its output. Provided it can still supply the demand from the load, the increased ripple can be mitigated with an additional LPF.

 The problem with almost all boost inverters is that they have a harder task to perform than its buck converter counterpart. It's a problem that's made worse in the case of inverting boost converters which can't cheat by using the incoming supply as a base voltage upon which to series output a lower voltage to effect the required voltage boost. In the case of an inverting boost converter which supplies a negative rail from a positive supply, all of the output energy has to come from the energy storage element, typically an inductor.

 The main reason for my considering the slightly less efficient R_Core transformer compared to its toroidal transformer counterpart is due to the lack of any toroids with more than two isolated secondary windings compared to the typical maximum of four typically found on R-Core transformers. The need to choose an efficient compact 25 to 30VA rated mains transformer is driven by the lack of cheap negative rail buck converter modules. Having at least three isolated secondary windings available will allow me to use cheap high efficiency positive rail buck converters for all three supply rails (using one 'connected backwards' for the -13.5 volt rail).

 However, the 1.2MHz switching buck converters I'm favouring for this job only have a maximum input voltage limit of 24vdc which makes secondary voltage selection very tight when you don't know the exact basis for their 15 or 18 volt specification (on load? off load? at maximum or minimum mains voltage? What???). I'd be much happier with a version that is rated for a 40vdc input since it would ease my choice of transformer considerably. The only buck converters I have with a 42vdc input rating are the slightly less efficient switching/LDO combination type where the buck converter supplies 6.5vdc to a 5v LDO. They're supposed to be a compromise between the efficiency of switching technology and the low noise feature of an analogue regulator - Yeah, right! I'll believe that when I start testing them and see this with my own eyes ::)

What do you think about this: using an external 19V Laptop PSU (no problems with grounding and security anymore), inside a TPS5430-based PSU
adopted to 2x13,5 V and another cheap Step-down-converter for 5V?? It's the cheapest way to (hopefully) improve the PSU of the FY. If there is enough
place and need for further "cleaning" you can bring another analog regulation behind the switching one. And I get enough power for any OCXO as well.
I played around with such a solution for a headphone amplifier which needs +/+16 volts and it works very well.  :bullshit:

 If you're going to be using DC charging brick limited to an output voltage of 19 to 23 volt, those cheap mini 360 1.3A variable output voltage buck converters sold by Banggood will be just the ticket for the positive rails, leaving you to track down just one positive input, negative output boost converter for the negative rail (otherwise just use that TPS5430 module for the +/-13.5 volt rails and a single mini 360 buck converter for the 5v rail.

 Although the 5v logic supply won't be bothered by supply ripple voltage it may still be of benefit to add an lpf at the psu end to reduce any ripple since it's the effect of the corresponding ripple current flowing through a common return shared with the analogue supply that you need to keep mindful of.

 If you can't separate the 5v logic supply's ground return from the analogue supply rails' ground return in the PSU, then aim to keep the ground connection between the PSU and the main board as short and as heavy gauge as is practical to minimise any such ripple current induced crosstalk between the logic and analogue supplies as possible. You can fit a ferrite ring or tube to suppress any common mode over the whole bundle of wires and even fit ferrite beads or tubes over the individual supply wires, just don't do the same for the common ground return. :)

But my main restriction is time. I'm still working (more than full time and with a lot of travelling) and have family. So I have to look for some hours to come forward with my projects.

 I know what you mean, I was planning on making a start on my MK II GPSDO today but got so involved in creating this "Masterpiece" of a response  :-DD :-DD :-DD... Sorry, oh yes. here I am putting the final touch to this missive, which is to say, it's only a quarter to one in the am, still early for this night owl so I may yet despoil that lovely blank sheet of copper clad board with the very first hole to locate my chosen OCXO's final resting place in this new GPSDO project of mine before retiring for the night. :phew:

 P.S. I may be slow in responding to any more postings from now on once I actually start building a new project as I'm hoping to do very shortly. Apologies in advance if I appear to be ignoring anyone but I'm not as good at this "Multi-tasking" malarky as I once had the arrogance to think I was. ::)

P.P.S. I've attached a couple of documents you might find of interest.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 12, 2020, 05:53:05 am
Thanks for reading and commenting my postings!

@Labrat101:
Great job with the modifications you have done! Thanks for the advice with the vent. But I'm not sure that it will have the same effect ecsp. with the PSU
when running reverse @ 5V. May be I have to increase the voltage a little bit but I want to avoid another kind of complexity (with fan regulation).
One of the things I learned during my business life is to follow KISS (keep it simple and short - if possible, and if not, than take the nearest non-complex solution)

I looked around in the forum for the mentioned "Arthur Dent test" but with his more than 1100 postings I couldn'd find it, can you give me advice?

This leads me to my next question for JBG and Labrat:

You both have done the OCXO-mod with your device. What is the result for the FG? Are 10.000.000 Hz on the output now really 10 MHz or are there other
influences and hurdles in the device design?

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 12, 2020, 06:58:40 am
Johnny I waked up unfortunately early at 6 and read your posting in bed.

You spend so much time for your long reply! Thanks!

To buy the OCXO without VCO was my mistake. The type was clearly stated at EBay but unfortunately I missed that point when I checked the data sheet.
But 16€ was ok for my first tests.

The decision for the new oscilloscope was not easy. I used for 10 y  and old, used, no-name 250 MSample/S chinese osci that I bought at EBay for my LF-work.
But for month now I had do deal with a defect rotary pulse switch for the channel 1 tray offset. And it seems not easy to find a fitting replacement because
it is unlabeled. If I find one I will repair it and sell it again but I'm not sure that the efforts are worth it.

For my Arduino projects it make sense to have a 4-channel device. For more than 1 year I've done research in the forums and at youtube.
And I was considering to buy a SDS-1104X-E.  To be honest, it would do the job.

Then I took the new RIGOL MSO5000 into account. Yes there is also a forum based "improvement" solution but the firmware seems to
be buggy. No we are in the 1k€ region  :=\
Around new year the new SDS2000X Plus showed up and I was impressed by the big screen, mouse control (really helpful on my bench) and the 10 bit mode (limited up to 100 MHz)
I belief that this will be great for my LF-work, I own a dozen high end tape recorders (btw: the REVOX is a reel-to-reel recorder, B77) and some of them
need care.
 
After family-internal negotiation I ordered a SDS-2104X+ for about 1300 € here in Germany. And it is a great old man's toy  :-+
And with all the addons (also integrated FG, several bus decodierers, Bode plotting...) and the incredible bandwith of now 500 MHz I'm happy for the next 10 years (I hope)

And my company tells me to fly economy as well  |O
But your assumption is right at the end of my working life I can spend some bucks more for my hobby beside all the care for my family and my 4 kids.

John you has spend a lot of efforts with the measurement of noise floor with FFT and you demonstrated the effect of electronic noise very well! I like your outside journey experiment!
This leads me to the following question:
You pointed out to me all the possible impacts of SPSU noise. And thanks for the attached article! I ordered immediately from bedside a set of ferrite beads  ;)
Yesterday I have done some first load tests with the dual voltage PSU with 1.25 A on both lines with resistor load. But I have to do further investigations, the chip on one
channel (the positive) run hot (around 100 degrees) the other kept cool. May be a wrong cabeling of me...

But you are right I have to consider the whole impact of external Laptop-PSU and internal switching regulators together with the additional C filtering on the FY-FG-board.
 
As discussed earlier it makes no sense to build the best noise (nearly) free PSU without thinking about the final result. (from my LF-investigations I learned
that also batteries have some chemical noise floor and that there are some better electronic regulations but this far away from our needs here)

And for this you have to do a defined and repeatable "before-after modification" test.
What do you think, how should be a setting for the measurement of the impact of an improved PSU with the FY-FG to get reliable and comparable results at the output?
 
Any helpful comment is appreceated!



Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on June 12, 2020, 08:55:30 am
Hi .
When I said run the fan in reverse I did not mean reverse the voltage .
Just rotate the whole fan 180 deg so it sucks the air though the case and blows out from the back.
This will give uniformed cooling over the entire surface . Also open the side vents that are probably closed by the plastic molding
processing. ( Just one of my many degs in cooling Air flow and thermal transfer ) it will also drop the current drawn by the fan motor itself .
....
I was very impressed in your proto lay out pictures . I never liked the solder less boards . I always got more loose connections than
good  and contact noise . Maybe just me. Every one else seems to use them ok.
and the screening around each block . I am impressed  that sort of work has to be A++   ^-^
....
About the Blog ArthurDent wrote just search by name I think it was on about the 3 or 4 page in the search results 2yrs + back.
...
On my OCXO I have not connected the vco up yet. It has the pins but CTS data sheet say leave NC .
  I am not good on the vcocxo not one of my subjects . but the vco out on my one is showing 1.66v when floating .
  Its a 3.3v CTS 119 series and its a Sample model  ''Cheep'' .
 I just have to figure out how to correctly connect it . The only thing I found was written  putting 5k 15turn pot between
 the VCO and  Ref pin centre to the 5k pot and to ground on last pin of the pot . (voltage divider to ground)

RNS

 :popcorn:

 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 12, 2020, 10:49:49 am
Thanks for your reply!

There is a misunderstanding. It's clear that I have to rotate the fan not the voltage! I'm only wondering about the impact on the PSU which is
now in the direct flow.

And the case of the 6900 seems to have better quality, the side vents are all open.

Because I used hot glue it should be not so hard to get the fan out. I had to buy 4 in a package at Amazon for 8€ .
So there are enough spare fans  :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on June 12, 2020, 11:00:16 am
if you have knowledge of the vc & ref  setup i would be interested in any info on this
as its not in my field . ^-^

it wont have any impact on your PSU other than it will be cooler hot air will be forced out .
and the cool air will flow over .
As you have it you are pushing the hot air from the PSU round the inside of the case heating other components
that were before cooler.
The air vents on the bottom sides should suck cool ambient air in  and the fan extracts hot air out which rises upwards .
the case will stay at ambient .
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 12, 2020, 03:02:19 pm
I have only little base knowledge of it. It's far better to read the last postings of Johnny B. Good.
Yes very long but very helpful. He describes the impact and usage of the VCO-calibration.

At the end it is simple, 5...10 k multiturn R between Voltage and ground and the variable output (I do not know the english words)
to VCO but Voltage must be precise. Ask JBG he has worked on it for a long time! And it takes time.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 23, 2020, 12:36:01 pm
I found under the heat sink this two non populated IC pads. Does someone has a clue what this could be for?
Different OPs with other footprint? Or another pair of THS3002 to increase load?
Has someone used it? I apologize when this was part of the ongoing disussions and I missed it.

Thanks in advance!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on June 23, 2020, 04:52:47 pm
I found under the heat sink this two non populated IC pads. Does someone has a clue what this could be for?
Different OPs with other footprint? Or another pair of THS3002 to increase load?
Has someone used it? I apologize when this was part of the ongoing disussions and I missed it.

Thanks in advance!

O yes these were discust in great detail .
They are for adding 2 singe op amps instead of the dual op amp . There is a circuit diagram I will have to dig it out
its also on github  don't have all the details on hand . I did this upgrade about a year ago .
I will try and find them .  JBG may have a better memory were all this was posted .. way back.
I'm a bit involved in rebuilding 3  HP 5385a Frequency counters got cheap as not working got 2 out of 3 working so far.  ^-^..
RNS
 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 23, 2020, 08:10:21 pm
Thanks for your reply! I found the schematics of the 6600 but I was not aware that there are spare pads
for other OPAs. I read all the stuff about changing the old THS3002 against the better single one but
I didn‘d find it in the FY6900 topic. Have you done it?
And btw nice counters! Hope you get all three running!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on June 24, 2020, 02:00:47 am
I found under the heat sink this two non populated IC pads. Does someone has a clue what this could be for?
Different OPs with other footprint? Or another pair of THS3002 to increase load?
Has someone used it? I apologize when this was part of the ongoing disussions and I missed it.

Thanks in advance!

 That's an interesting photo you just posted. It looks like someone will have to reverse engineer this main board on account it is radically different from the FY6600 and the FY6800 models as far as the final 12dB boost amp circuit goes.

 What's different in the case of the FY6900 is that they've used a pair of THS3002i dual opamps in place of the single dual opamp used in the earlier FGs. It was a little tricky to make out what that IC in the top left hand corner of the heatsink's keep out area was (I'd been able to positively identify its cousin in the bottom LH corner, a THS3002i). I was surprised to see a second THS3002i chip but the 100 ohm resistors and the FB and Gain resistors rather give the game away.

 The unpopulated U21 and U22 are for single higher spec opamps THS 3001/3491/3495 etc. If you have a go at this upgrade, you'll need a pair of the higher spec single opamps to fill the unpopulated spots and remove both THS3002i opamps and strap the 100 ohm resistors now separated by the removal of the 3002i opamps (each one of a pair used these resistors to combine their individual outputs so the load saw a 50ohm source but the outputs were in no danger of fighting each other due to slight gain mismatches - it's a common way to use more than one opamp in parallel to improve performance at higher frequencies).

 TBH, I'm rather surprised they'd bothered providing the unpopulated U21 U22 locations on the main board since with a 20MHz upper limit before the 24v pk-pk limit is dropped to 5v (and these opamps switched out of circuit), I'd have thought just doubling up on the 3002i opamps alone would have addressed the horrible distortion on sine wave output at 20v pk-pk at the 20MHz limit exhibited by its predecessors.

 Check the waveform at the same 20MHz limit for the 24v p-p option driving 50 ohm loads which should result in a 12v p-p waveform. If it looks more like the 2nd attached image SDS00227 (THS3491 upgrade) rather than the 1st image SDS00163 (the original THS3002i opamps), I wouldn't go to all the bother and the expense of another pair of THS3491 opamps just for a marginal, if any, improvement. There might not be any real need in this case to duplicate the opamp upgrade efforts of the FY6600 and 6800 community.  ::)

JBG

P.S. I'm still busy testing my MK II GPSDO (after an initially promising but, ultimately disastrous start - I somehow blew up a 74HC14 and two of my 5v RRO cmos opamps, culminating in the tiny 1.3A mini 360 5v buck converter starting to let out its magic smoke.

 I had modded the buck inverter to give me 5.340v (the cmos opamps are rated for 5.5v working but it was the first one that went short circuit and cooked the buck inverter's goose). I landed up trying out my one and only example low noise 5v buck converter with 5v LDO in place of the burnt out one simply on account it had the same pin out footprint and it seemed a convenient way to test the claimed "Best of both technologies" most of the efficiency benefit of a switching regulator with an LDO to get rid of the switch noise (yeah, like that's gonna happen :o ).

 I haven't gotten round to checking this low noise buck/LDO chimera's noise and ripple yet - I've been rather busy fettling my now functioning GPSDO board. The latest experiment involved a test with ten times the 500 seconds TC (replace the 100K and 1M resistors with 1M and 10M - I couldn't find another 5.6M in my collection but I had a few 10M resistors ::) ).

 As you could imagine, it took way longer to lock the OCXO - around 3 1/2 hours versus the 25 minutes with the 500 seconds TC !!! Fortunately, I have a simple circuit add on which should shave a couple or more hours off that startup time which I hope to put to the test later today.

[EDIT 2020-07-09]

 That "Low Noise best of both worlds buck/ldo" module exceeded my expectations of decrepitude, largely I suspect due to the use of an unshielded inductor. Also, my simple two diode (one for each of the 470 and 47uF TC caps) plus a 5K trimpot accelerator circuit did solve the slow startup issue, shaving some 3 hours off the original 3 1/2 hour lock up time.

 I also finally got round to matching up a set of 5 1K resistors to create a selection of 5 voltmeter offsets in 1v steps from zero up to 4 volts to let me use the mV range on a cheap (13 quid) Mestek 9999 counts DMM to monitor the VFC in tenths of a mV using the OCXO's 5.127v Vref to provide an extremely stable voltage source (far better than the TL431 I used to create a 3v meter offset in the MK I).

 The motivation to finally get off my backside and install this reference source came about as a result of my using a part used but well rested AA alkaline cell as an initial temporary measure to monitor the MK II's VFC in 100uV increments after the apparent VFC started bucking the trend of a rising voltage with age exhibited by the 13MHz OCXO used in the MK I which proved to be the AA cell starting to increase its voltage output about 1 mV per day :wtf:

 I hadn't taken note of the AA cell's initial voltage so wasn't able to work this out until after directly monitoring the 2.282v VFC for a couple of days to confirm it wasn't actually dropping at all (at least at nowhere near the rate implied by my AA cell voltage offset lash-up).

 Lithium coin cells are a much better bet on voltage stability for such a stunt provided the 3.16 or so volts gets you close enough to allow a cheap 3 1/2 digit DMM to use its mV range and show readings to tenths of a millivolt. Here, absolute accuracy whilst nice to have, is not essential - it's the weeks long stability of a CR2032's open circuit voltage that counts (worst case drain with a 10M DMM input is just 100nA, in my case it had been just 15nA or so with the MK I and a CR2032).
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on June 24, 2020, 08:17:52 am
Hi JBG
that looks good .
I managed to pick up 3 .HP 5385 frequency counters cheap . All had the same faults
On the power supply bad connections.
I did some tests on my 6800 . And they all say to the 11th digit . I am now at 10.000000001Mhz.
 :-+
And using  my oven 20mhz ocxo divided by 2 to give me my 10mhz reference signal .
Is well good to any standard.
..
About that photo of the 6900 unpopulated pads I think this is so it can be upgraded to us 2 ths 3491 in parallel as reccomend by Texas instruments.
Don't us the 3495 as they have the heat pad on the bottom.
From what I could see from the photo .
You will have to trace out the tracks on paper
As it dual 3495 will need a couple of smd resistors for load matching..
..
It not that much different from the fy6800
Putting two 3491s in parallel will allow for
Better load output .
This may cause a relay problem as it will amplifier any errors .
The relays are contact type and not Reed relays that don't have the same noise problems.
All the good equipment use Reed relays .
On high frequency.
That's why put the 10pf on the relays it not as good as a reed but it make a pore man's alternative.  :-+
..
Try to do a trace out of those spare pads.
Most of it should be pin to pin  ..
Have fun
RNS.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 24, 2020, 10:08:27 am
HI John,

good to hear from you! I done some tests with your advice, attached you find the screenshots. Up to 20 Vpp (what is 7.6 V measured)
sine stays sine as you can see. I recognize a little deformation at 24 Vpp but related to your picture the both OPAs in parallel doing a better job.
I also run some FFTs do get an idea of the THD. You find this with the steps from 24Vpp-20Vpp-15Vpp-5Vpp-0.5Vpp (to get the magic clicks of
the relays @ 5V and 0.5V).

I see no reason to change the OPAs now (may be later). I'm a bit careful with this. I started my "OPA-career" in the late 70s with the east german clone of the uA709 (named A109) and you may remember that this circuit was really sensitive to compensation. I learned during this time a lot about gain, bandwith (and the product of  both) but also about "swinging" of badly compensated OPAs.

I'm always shaking my head  |O when I read in audiophile forums from members, which
explain how good the change of an standard audio OPA against a fancy high performance RF model works and what they now
on new details from their sources can hear....  :-DD And this without any lab experience, without Osci-control. What they now hear are
the arte faktes of high frequency swinging.... but it makes no sense to discuss with this kind of people which spend 500 € for SPDIF optical cables.

 btw: I follow your advice to rethink the idea of using a laptop PSU and the little 2x15V converter. I have done some measurement and the
switching noise is hugh! So I went thru the whole FY6600 forum again and found in the beginning the first PSU-solution of Arthur Dent with
an industrial grade PSU (ARTESYN NFS40-7610J). It's expensive (around 50€) but I got a new one today from a UK based reseller for 15€.
This is a little OTT but with this I get enough power for my planned OCXO mod. I also read a lot (your advice as well) about SMPSU-filtering and ran
some tests with ferrite beads, rings and capacitors. I keep you informed!
Title: Re: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on June 24, 2020, 10:18:00 pm
 The first two thumbnails don't match the images that pop up when they're clicked to view them (the same result when downloading them).

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 25, 2020, 06:44:57 am
Fixed! Something went wrong.  :=\
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on June 25, 2020, 12:43:21 pm
Fixed! Something went wrong.  :=\

With the ops I would leave alone as well. to get 24vpp
 as the SMP is 12v plus/minus  (24vpp) the ops require about 2v head room .
So if your getting 24v this maybe why the sine is funny above 20v .
The max safe voltage supply of these output ops is 30v on a dual rail.

Noise off the SMPS 0.01pf Ceramic  & a  2 Large 470uf with a small choke between them and
and a ferrite bead works wonders. ( caps can be Larger upto about 2200uf )
  If you want all out quite go for 10uf Tautanim Caps that's what i used. A liitle more cost but well worth it . I had a whole box of them so I used what I had. :-+

Always Remember if it aint Broke don't fix it  :-+
It also depends on what you will be using it for .
  Myself  I am a very precision Nerdy pensioner and if not perfect it bugs me  :-DD   :popcorn:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 25, 2020, 02:09:29 pm
The 6900 runs with the „old“ PSU at 2x 13,5 Volts. So 23 Vpp can be possible.

I have done today the mechanical work to bring the new PSU into the box
and startet with the filter connection. (choke, tantalium and ceramic Cs, I also have a great choice by the hands)
As Arthur Dent suggested I have 2 diodes in serial with the +/- 15 volts rails to stay a little bit more away from the OPAs
limits.

The best thing is that the SG now is much heavier and doesn‘t much longer has this „toy weight“.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on June 25, 2020, 04:59:03 pm
I am now put my FY6800 to the full
Test .
The bottom scope is the oscillator sync
The 10Mhz out of fy6800 from the ocxo & the TCxo from Hp 5385 .
Top scope is 10mhz sine sinked to the 2 difference references .

BTW   ''Bad_Driver'' Try using your probes set @ x10  or your bandwidth will be out.
          also it will reduce the in circuit loading . :)

 My cables are M/Grade and are 50ohm inductance .So you won't see the termination.
 in the photos . but its there.. :)  The square ish is from a buffered JK Divider 0.01PPb
 10Mhz Reference signal.  un terminated .
 Update:: I forgot to add a resistor to my divider output .  :palm:  It only affected the scope wave not reading  :-+ 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on June 26, 2020, 06:59:15 am
To make the measurements comparable to the results of JBG I used H.Q. coax with 50 ohms termination.
Therefore Vpp is "only" around 8 volts. I tried internal and external termination, results were the same.
Since my FG is under reconstruction I cannot repeat the measurments without load.

After some strange experience I learned that the weak BNC connector of the FY FG and cheap coax cables doesn't fit together.
So I upgraded my cables and connectors withe much better one and couln'd find my old crimp tool what to a new one lead.
I'm sure the old one will show up the next days....
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on June 26, 2020, 07:39:14 am
Yup the connectors are not over good
I found by closing the small center pin on the BNC solved 99% of looseness.  Also if you look at the grounding on the connecting plug the are 4 very thin cuts an can be opened carefully to make the plugs fit snug .
The problem is that a lot of these cheap BNC
Don't seem to be standard sizes  :palm: .. check with a micrometer . :-+
There are different only a few thousand inch.
But enough for a noisy connection.
 :popcorn:
RNS.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 06, 2020, 12:05:34 pm
On Saturday I was sitting with my 2nd cup of coffee after breakfast and once again I was scrolling through offerings at EBay for my
FY "improvement" project. Last week I finished my PSU-upgrade and as expected the performance with high Vpp is a little bit better but
that was expected since I increased the lines up to 14.5V +/-. Noise floor is lowered by some dB but that can also be result of my new
PSU filtering stage.

With some items in my basket @ EBay I rethought the situation and all the little weaknesses of the Feeltec device:
- non linear amplitude-frequency response behind 1 MHz, I see a decline of 2.3 dB starting with 1 Mhz up to 60 MHz
- the non existing trigger function with sweeps
- the strange behavior of logarithmic sweeps - I expect a sweep of one decade per time interval as usual for Bode plots
- the strange attenuator stage behind the OPs (thanks to JBG to point this out)
- the  non existing firmware upgrade policy of Feeltec
- the cheap 10 MHz XO of the FY
- ...

I paid last year 89 € for the FY6900  and I learned a lot during the last month about PSU filtering (thanks to JBG), about the FFT functionality of my new SDG 2104X+ (improved to 2154  :-+) and about my needs on a FG.

I came to the conclusion that I would be able to improve the weak XO with a much better one OCXO (that was the only reason for my PSU change - to have the additional power available) but all the other weaknesses will stay a pain in my a... and will not be fixable by myself.
If the FY FG would be my eternal improvement project as hobbyist I would go further but it isn't.

The FG is as it is, not bad for the money I paid for and I will keep it. But I will stop my efforts to improve it. Maybe I rebuild the PSU to the old one
since I avoid any mechanical changes in the device (I used a selfmade alloy frame for the new industrial grade PSU that fits perfect to the
existing holes). Attached a photo of the FY with new PSU.

On saturday I ordered a Siglent SDG2042X @ Welectron here in Germany (also with the ability for SW-based-improvements - see the EEVBLOG).


Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 06, 2020, 09:27:49 pm
Bad_Driver    Looks Good . Those caps look interesting If it works its good  :-+
 
There is a trigger bnc input on the back . It did not work well on my FY6800 and I don't use it .
So that is now my 10Mhz reference out out to my HP 5385 frequency counter.
Which I now have 3 . Got a job lot of 3 non working unit . I was hoping to get at least one good one .
Fixed all 3  :-+   . Got two spares . One I will sell .
They are nice as they have reference in/out  & 11 digit display and being old school room for addons  :-+
& good from 10Hz to 1ghz

All the best have   :popcorn:
RNS
 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 07, 2020, 08:16:01 pm
Hi Labrat,

what price do you expect for your spare counter?
btw: the caps are NOS east german tantalium Cs. I have a bunch of them bye the hand and they seem still ok.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 07, 2020, 08:59:34 pm
Hi Labrat,

what price do you expect for your spare counter?
btw: the caps are NOS east german tantalium Cs. I have a bunch of them bye the hand and they seem still ok.
I will be putting it on ebay for around $250 as I had to do quite a lot of work on it .
 It still need a little work as the previous owner miss used it . :palm:
 I have tested it and it is all working as per the service manual  and it reads good to my 10Mhz OXCO which is 0.02 PPB which I reckon is good enough for most of us .
  I have no Idea what the shipping cost would be like and How long it would take .

It the one in the post a few up ..#336 on: June 25, 2020, 04:59:03 pm
 I used it to do the tests after calibration 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 08, 2020, 10:30:18 am
There was a bunch of HP5385 on EBay from Israel, each in working condition für around 100€ during the last weeks.
I hesitated because of the high shipping costs and the unclear Tax/import situation into EU.

I wish you good luck @ EBay. As we all know HP stuff sells for good money these days.
Let me know what money you get.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 08, 2020, 12:16:24 pm
There was a bunch of HP5385 on EBay from Israel, each in working condition für around 100€ during the last weeks.
I hesitated because of the high shipping costs and the unclear Tax/import situation into EU.

I wish you good luck @ EBay. As we all know HP stuff sells for good money these days.
Let me know what money you get.

Thanks I live in Israel there was a lot of X Army stuff the seller is good I get a lot of stuff from him most of it is just loose wires broken or missing knobs  . Its all Military grade so it has some better components in them . there are a few very good suppliers  (tsvi.parts)  :-+  Shipping sucks every were . :palm:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 09, 2020, 03:01:58 am
Hi Labrat,

what price do you expect for your spare counter?
btw: the caps are NOS east german tantalium Cs. I have a bunch of them bye the hand and they seem still ok.
I will be putting it on ebay for around $250 as I had to do quite a lot of work on it .
 It still need a little work as the previous owner miss used it . :palm:
 I have tested it and it is all working as per the service manual  and it reads good to my 10Mhz OXCO which is 0.02 PPB which I reckon is good enough for most of us .
  I have no Idea what the shipping cost would be like and How long it would take .

It the one in the post a few up ..#336 on: June 25, 2020, 04:59:03 pm
 I used it to do the tests after calibration 


 Hi Labrat101,

 I was just reviewing that post a couple of hours ago and puzzling over that photo you'd attached (I'd been a little too preoccupied the first time I'd seen it) so I downloaded it in order to rotate it 90 deg CW in GIMP to save craning my neck trying to work out what was what :)  I've saved the result which I'll attach to this reply to help make that setup you mentioned (which explains that opened up frequency counter  :D ) a little clearer to anyone interested in the counter.

 I was rather surprised to see that chimera of a DSO with a CRT display HP scope, along with a 100MHz 200MSa/s logo, no doubt the product of a marketing droid's fevered imagination (70MHz 200MSa/s perhaps with a 200MSa/s ADC for each channel - 100MHz 200MSa/s no way Jose! Not even with one ADC per channel  :palm:).

 That's quite possibly the only example of HP making the mistake of allowing a marketing droid have the final say in the styling of their product line. I doubt that makes it a rarity numbers-wise since there's probably a shed load of these things circulating around in the second hand marketing channel.

 This reminds me of ntcnico's tag line "There are small lies, big lies and then there is what is on the screen of your oscilloscope" only in this case, it's not the screen so much as the front panel markings. If you regard it as a 70MHz BW 'scope (assuming one ADC per channel), it should serve its purpose very nicely (it is an HP after all  ::) :) ).

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 09, 2020, 06:06:36 am
I got yesterday as mentioned before my new Siglent SDG 2042 which improved itself with a little service
of 5 minutes and the help of an USB-stick into a SDG 2122.
A small step for mankind but a giant step for me! What a great device in relation to the FY6900!  :-+
I will run some tests later with both but this weekend I start family holidays for 2 week and go to the coast.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 09, 2020, 10:52:06 am

 Hi Labrat101,

 I was just reviewing that post a couple of hours ago and puzzling over that photo you'd attached (I'd been a little too preoccupied the first time I'd seen it) so I downloaded it in order to rotate it 90 deg CW in GIMP to save craning my neck trying to work out what was what :)  I've saved the result which I'll attach to this reply to help make that setup you mentioned (which explains that opened up frequency counter  :D ) a little clearer to anyone interested in the counter.

 I was rather surprised to see that chimera of a DSO with a CRT display HP scope, along with a 100MHz 200MSa/s logo, no doubt the product of a marketing droid's fevered imagination (70MHz 200MSa/s perhaps with a 200MSa/s ADC for each channel - 100MHz 200MSa/s no way Jose! Not even with one ADC per channel  :palm:).

 That's quite possibly the only example of HP making the mistake of allowing a marketing droid have the final say in the styling of their product line. I doubt that makes it a rarity numbers-wise since there's probably a shed load of these things circulating around in the second hand marketing channel.

 This reminds me of ntcnico's tag line "There are small lies, big lies and then there is what is on the screen of your oscilloscope" only in this case, it's not the screen so much as the front panel markings. If you regard it as a 70MHz BW 'scope (assuming one ADC per channel), it should serve its purpose very nicely (it is an HP after all  ::) :) ).

JBG

       Some things are kept out of the eyes . Because their brain fills in the Blanks .. 99% wrong .

Hi JBG ..
This scope is marked up as 100Mhz @ 200mSa/s
Its also an X military and has been modded not by me  . It  will run and see signal of over 5Ghz .
It has some weird panels inside that are not in the manual .
So sorry to disappoint you the label is just a label . The front panel was replaced from another scope. :-+

The other PK scope was modded it is 150Mhz 1gs with a firmware from another section here.
And is just a cheap digi scope with bugs .
.
Quote
I was rather surprised to see that chimera
The funny square wave was my error as I wrote above. I forgot to put the loading resistor on the 10Mhz
Reference Divider circuit. The cranking of your neck must have knocked your class off  :-DD
..
Why all the sudden are you picking on my scope labels  its is Not 70 mhz per channel .
 This scope is really good maybe old but it has some very nice addon panels in side all with Mil Marks.
& no your not going to have a Peek .

PS   Did I knock your Scope  :-DD

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: timkoers on July 17, 2020, 11:02:55 am
Would somebody be kind enough to provide a list of fixes that you could easily do to the FY6900?

I started at the first page of this topic, but I quickly lost it due to various discussions.

The main thing that I am interested in is not to have AC (by any mains, pun intented) on my BNC's. Could an 1/2W 10k resistor be used in series between the mains connector's earthing cable and the power supply?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 17, 2020, 02:28:22 pm
Would somebody be kind enough to provide a list of fixes that you could easily do to the FY6900?

I started at the first page of this topic, but I quickly lost it due to various discussions.

The main thing that I am interested in is not to have AC (by any mains, pun intented) on my BNC's. Could an 1/2W 10k resistor be used in series between the mains connector's earthing cable and the power supply?

 That's almost exactly the same solution I used with my FY6600 (three one quarter watt 33K resistors in parallel to make up an 11K "Static Drain" resistance to ground). In the case of the FY6600, this modification also required an upgrade from the C8 mains socket to a three pin one (C6 as I chose or C14 as almost everyone else did - probably picked out from the "Scrapped desktop PC parts Box" ;D ).

 The psu boards remained the same class II type, with no safety earth requirement. All Feeltech had done was to upgrade the mains input sockets on the 6800 and 6900 models and "angrily bodge" an earth connection between the socket's PE tag and the nearest convenient point of contact with the zero volt rail with the absolute minimum amount of reworking of the wiring, hence that reprehensible hijacking of one of the ground returns in that 6 way PSU to Mainboard ribbon cable connector that we see in the 6600's immediate successor, the 6800 and, unbelievably, in the 6800's successor too, this nice shiny new 6900 model when one might well have expected them to review this bodge, hang their heads in shame and work out a proper solution.

 Apparently, they have absolutely no shame whatsoever which should come as no surprise to anyone who has ever had to remedy the glaring safety issues often seen with other cheap Chinese made electrical kit (eg, the metal cased version of the otherwise excellent KSGER T12 Soldering Station control unit for one  ::)).

 Getting rid of this unwanted earth wiring loop without reintroducing the ESD hazard of the 6600 model is as simple as (preferably) undoing the damage done to the psu to main board ribbon cable and wiring a 3.3 to 10K half watt resistor between the PE tag on the C14 socket and any convenient ground point connection to the main board.

 This is a modification well worth doing to the 6800 and 6900 models since, not only does it keep the half live touch voltage down to less than half a volt ac, it also eliminates the random DC offsets introduced by the low impedance connection to the noisy mains earth wiring which had fooled some users into thinking their brand new 6800 and 6900 AWGs had not had their DC offsets properly zeroed out at the factory, leading them on a wild goose chase in their misguided efforts to trim it out on the preset pots. :palm: ::)

 Long story short: Yeah, just put a 4K7 resistor in series with the wire going to the C14's earth tag. ::) ;D

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on July 17, 2020, 05:00:35 pm

Quote

 That's almost exactly the same solution I used with my FY6600 (three one quarter watt 33K resistors in parallel to make up an 11K "Static Drain" resistance to ground).

please one photo or diagram
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 18, 2020, 11:45:12 am
Go to my posting

https://www.eevblog.com/forum/buysellwanted/re-feelelec-new-arrival-fy-6900-signal-generator/msg3092712/#msg3092712 (https://www.eevblog.com/forum/buysellwanted/re-feelelec-new-arrival-fy-6900-signal-generator/msg3092712/#msg3092712) :scared:

There is a photo of my device before I changed the PSU at the end.

IMHO it makes only sense to
- improve the weak cabeling
- add a 12 Volt 40 mm Fan and connect it to the 5v fan connector
- connect mains earth with the ground with 4.9 kohms

The power supply is better than expected and for this device good enough.
There are other weaknesses you can not change.... :palm:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: timkoers on July 18, 2020, 02:47:53 pm

 Long story short: Yeah, just put a 4K7 resistor in series with the wire going to the C14's earth tag. ::) ;D

JBG

I put a 10k resistor in there, is that resistance too high?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 19, 2020, 04:54:56 am

 Long story short: Yeah, just put a 4K7 resistor in series with the wire going to the C14's earth tag. ::) ;D

JBG

I put a 10k resistor in there, is that resistance too high?

 That should be ok - I used an 11k resistor (three 33k in parallel). It's not critical, anywhere from 3.3k to 10k should be just fine - the 4k7 was just a suggestion bang in the middle (exponentially speaking :) ). Using a 10k reduces the "touch voltage" from half 240v mains (circa 90vac when measured with a 10M input DMM) to a mere half volt (quarter of a volt in the case of 120v mains supplies).

 You can measure the reduced half volt ac on the BNC grounds (assuming 230v mains) to confirm that the 10k resistor is doing its job. Assuming a worst case of 1 ohm resistance between the FG and the DUT's shield connections, a 10k resistor should provide 80dB of attenuation to any noise and unwanted DC offsets coming from the mains earth wiring.

 Reducing the resistor to 1k reduces this attenuation by 20dB to 60dB. Even if you use a 100 ohm resistor, you should still see a 40dB attenuation of mains earth wiring noise injection but since the main aim is to reduce the 90vac touch voltage down to less than a volt, the 3.3 to 10 k resistor values are more than sufficient to remove this ESD hazard to even the most delicate of DUTs.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: timkoers on July 19, 2020, 08:21:54 am

 You can measure the reduced half volt ac on the BNC grounds (assuming 230v mains) to confirm that the 10k resistor is doing its job. Assuming a worst case of 1 ohm resistance between the FG and the DUT's shield connections, a 10k resistor should provide 80dB of attenuation to any noise and unwanted DC offsets coming from the mains earth wiring.

 Reducing the resistor to 1k reduces this attenuation by 20dB to 60dB. Even if you use a 100 ohm resistor, you should still see a 40dB attenuation of mains earth wiring noise injection but since the main aim is to reduce the 90vac touch voltage down to less than a volt, the 3.3 to 10 k resistor values are more than sufficient to remove this ESD hazard to even the most delicate of DUTs.

JBG

I measured it between Live en the GND with my DMM (The EEVBlog's Brymen BM235), but is is showing 230V AC. I don't think I measure it correctly though.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 19, 2020, 12:36:19 pm
It‘s ok. You can ckeck it by measuring voltage between main earth and bnc ground. Should be lower than 1 V.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on July 19, 2020, 11:07:56 pm
Go to my posting

https://www.eevblog.com/forum/buysellwanted/re-feelelec-new-arrival-fy-6900-signal-generator/msg3092712/#msg3092712 (https://www.eevblog.com/forum/buysellwanted/re-feelelec-new-arrival-fy-6900-signal-generator/msg3092712/#msg3092712) :scared:

There is a photo of my device before I changed the PSU at the end.

IMHO it makes only sense to
- improve the weak cabeling
- add a 12 Volt 40 mm Fan and connect it to the 5v fan connector
- connect mains earth with the ground with 4.9 kohms

The power supply is better than expected and for this device good enough.
There are other weaknesses you can not change.... :palm:

connect mains earth with the ground with 4.9 kohms?????
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 20, 2020, 09:55:16 am
Yes, look at the attached foto. The drain resistor is inside the black skrinked part of the yellow-green wire.
The device needs no earth grounding on the hot side. It‘s class 2.
So you cut the thin wire between ground and the outlet.
But now you need the drain resistor to reduce the occuring
„touchable“ voltage induced by the PSU - this was the situation with
the older FY6600. You can measure it between mains earth and ground.
The drain resistors reduces this leakage voltage to nearly zero.
There is only a minimal current flowing thatswhy the size of resistor
is not so important.
After that you get a „floating“ device what means you can connect bnc-ground to
a point of you DUT that has a potential different to earth.

But if you unsure what you are doing it is better to avoid to play with the hot side of the PSU. :--

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 23, 2020, 09:15:11 pm
I finalized today my FY 6900 with my (non VC) OCXO I bought some weeks ago for
16 € @ EBay. The same I invested into the industrial grade PSU.
All the other stuff was from my shelf.
On the photos you can see the new PSU, the filtering board with the LDO 9V for the fan
and the OCXO board with the LDO 3.3 V for it. OCXO in the foam covering. OCXO, LDO, 74S04
on the backside of the strip board.
The OCXO 3.3 V output goes to the solder point were the cheap XO was located.
I use the former useless Trigger BNC as output for the 10 MHz reference signal.
It is driven by 3x 74S04 gates in parallel, each with a 150 ohm resistor at the output to get
a better signal with 50 ohms impedance.
The last picture shows the measure of a 2.000.000 Hz GPS signal from my Neo m8n.
After 2 hours the error is 250 ppb. Ok for this device and the end of my improvement efforts.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: g2 on July 25, 2020, 06:35:21 pm
I would like to buy a new function generator.
Which function generator should I choose: FY6600 or FY6800 or FY6900 or RD JDS6600. Or are there others in the same price range.
I have today Feeltech FY3200S 20MHz and am dissatisfied with:
1. lack of galvanic separation of the power supply.
2. missing galvanic separation of the USB port
3. Zero-pass glitch
4. On the FY3200 generator when you change the frequency or amplitude the output waveform glitches. No smooth adjustment.
5. In addition, Channel 1 20mV glitch has occurred for every 10.7uS.
When I read in EEVBLOG about the different function generators, it is difficult to figure out which one to choose, as there is a lack of an overall overview of advantages and disadvantages.
And some of the modification may not be important to everyone.
Do I get the same errors as with the Feeltech FY3200S?
Is there anyone who can explain some of the differences?
and what is absolutely necessary to change?
Thanks in advance Gert
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 25, 2020, 09:07:05 pm
Quote
I have today Feeltech FY3200S 20MHz and am dissatisfied with:

Hi I have FY6800 60Mhz  It has all the same bugs .. the internal PSU all have a problem.
 ie bad earth & pore quality ..
 The Jitter is the same .. only the box and some minor  software update.
 If you read though other posts . there are a lot of upgrades ie PSU etc.
 If you are unhappy with what you have the new faster version has some good features
 value for money  .. that's properly yes  >:D  Get what you pay for ..
.. It all depends on what you want to use it for . Just home hobby its ok .
 But if you are going to lash out I would go for maybe a good second hand profession one.
 I myself and many others in this forum have done many upgrades to make these FY's work well.

 Its a hard to recommend something that has known bugs .. You will have to do a lot of home work.

  personally when my FY6800 dies I would not get another one .

Have funny & good luck .
Make your self a Pros & cons list .  and read some of the earlier Posts this will guide You to a decision.

You should also read this link from JBG .

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2475843/#msg2475843 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2475843/#msg2475843)

 



Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 26, 2020, 10:05:31 am
It is a good device you get for 89€ (my 6900) The 6900 has some minor improvements over its predecessors.
The keys and the improved PSU p.a.
For this money it does the job and as mentioned above some little tweaks (improve cabling, fan, cutting
earth and ground and use drain resistor) it is a good hobbyist device.

And I‘m pretty sure that there is no other device out there with the same value-per-price. :-+

But If you see all the weaknesses it has by design  before owning it you should buy
a more professionell device as I have done at the end.  |O

 the time of good bargains at Ebay is over
and you pay for 30 years old HAgilsight devices in unknown condition a fortune now.  :horse:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 26, 2020, 10:09:11 am
While writing the last post I got a question mark in my mind because I lost track of the Feeltech devices
during the last weeks.

Have they published a new firmware or software?


Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 26, 2020, 12:01:24 pm

Have they published a new firmware or software?   :-DD

I look every so often .. No the Last one is long time ago .. 
 This was a joke .. Yes    :-DD

There new model has a different number .. But they don't seem to supply updates .. and the PC program did have an update by GitHub which solved a few bugs .
 Nothing new for the 66 / 68  ..
 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: timkoers on July 26, 2020, 12:26:43 pm
I noticed that the FY-6900 is getting rather hot during standby. Is this common?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 26, 2020, 01:33:01 pm
I noticed that the FY-6900 is getting rather hot during standby. Is this common?
The standby only turns the display off ... The PSU is still running on full load .. >:D
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 26, 2020, 04:25:43 pm
Quote
I have today Feeltech FY3200S 20MHz and am dissatisfied with:

Hi I have FY6800 60Mhz  It has all the same bugs .. the internal PSU all have a problem.
 ie bad earth & pore quality ..
 The Jitter is the same .. only the box and some minor  software update.
 If you read though other posts . there are a lot of upgrades ie PSU etc.
 If you are unhappy with what you have the new faster version has some good features
 value for money  .. that's properly yes  >:D  Get what you pay for ..
.. It all depends on what you want to use it for . Just home hobby its ok .
 But if you are going to lash out I would go for maybe a good second hand profession one.
 I myself and many others in this forum have done many upgrades to make these FY's work well.

 Its a hard to recommend something that has known bugs .. You will have to do a lot of home work.

  personally when my FY6800 dies I would not get another one .

Have funny & good luck .
Make your self a Pros & cons list .  and read some of the earlier Posts this will guide You to a decision.

You should also read this link from JBG .

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2475843/#msg2475843 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2475843/#msg2475843)

 

 You'd better take a look at a later posting I made on this subject here:-

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2477619/#msg2477619 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg2477619/#msg2477619)

 It turns out that the manuals for the 6600, the 6800 and the 6900 all perpetrate the same frequency versus p-p voltage limit error. All three can generate a full 20v p-p (High impedance loads) up to the 20MHz frequency limit for sine and square waves before plummeting to the 5v p-p limit.

 I've since come to the conclusion that, aside from that horrible earthing bodge that destroyed whatever ground return integrity there was in that 6 wire ribbon cable linking the PSU to the main board, the 6900 model is actually an improvement over its predecessors - they still use those ("We bought a million of these bastard THS3002i opamps and we won't be getting rid of them until every last one has been used up in our function generator product line") but now they've doubled them up to reduce distortion at the 20MHz 20v p-p limit. It's an improvement at the extreme limit but it still falls a little short of what could be achieved with just a single THS3491 per channel in the FY6600 and FY6800 upgrades.

 If I was still in the market for yet another cheap Chinese AWG, I'd be going for an FY6900 and a 4.7K half watt resistor ready to be inserted into a new grounding wire link from the C14's PE tag to the ground rail of the main board, plus a fan to fill the hole in the rear panel.

 As things stand, after running my never ending modification project, code named FY6600, for a little over 18 months, I'm now more than prepared to invest in an SDG1032X (hackable to a 1062X) for a mere 278 quid without discount. After all of my time spent in the purgatory of improving this toy AWG, I feel I'm long overdue some light relief.

 Back in November 2018 when I'd been looking for a signal generator to complement my recent 365 quid 'scope purchase (an SDS1202X-E), the original 360 quid asking price of the SDG1032X had seemed so out of proportion to what I'd just spent on the 'scope, that the sub 76 quid asking price of an FY6600-60M with double the frequency range looked a very good alternative... on paper at least. Of course, I've now developed a new sense of respect for the more subtle distinctions between these two products. ::)

===========================================================================================
[EDIT 2020-10-26]

 Now that I've had experience of both of the SDG1032X (returned as "Unfit for purpose" due to a horribly jittery internal clock oscillator fault) and the SDG2042X bought to replace it in the hope of being able to finally retire my much abused FY6600, I can tell you that I now have a new found respect for Feeltech's design efforts (but not the inexcusable bean counter led stupidity that did dollars worth of damage for the sake of a cent or two's worth of cost savings, nor for their non-existent "After sales customer support").

 It might come as a shock but the UI on these feeltech AWGs is miles better than the user hostile UI that Siglent have inflicted upon all of their AWG product line. The most user hostile effect I see with the FY6600 model are simply those horrible plastic dimples used to actuate the real, if variable quality, soldered on PCB mount switches - at least it's possible to replace any faulty or hard to operate switches.

 The most user hostile and counter-productive aspect of Siglent's UI is the frequency setting interface where the keypad entry is limited to a maximum of 11 digits, the last three of which then get stamped on by the chosen multiplier, causing the displayed reading to be rounded to the nearest 8 digit value even though the full 11 digit entry does get used to set the frequency.

 If you want to make a fine adjustment via the rotary encoder and digit select cursor as per the FY's only method, you're limited to just 8 digits and always have to shift the cursor to the desired digit, unlike the FY's "sticky digit select" which can be anyone of the full 14 digit's worth of resolution available to the FY series.

 The 1uHz resolution in the SDGs only applies to a maximum of 100KHz and that's when using the clunky keypad entry method. Unlike the FYs where you can fine tune a 1uHz offset over the full range DC to 100MHz, Siglent's 1uHz resolution is limited and reduces as you select MHz and then tens of MHz frequency settings. Despite the lack of a keypad (more likely because it lacks a keypad), Feeltech had managed to create a frequency setting interface that is a positive joy to use by comparison to that of the SDG models. :o ::)

 Then we come to the rest of the menu driven UI unfriendliness of Siglent's (not so) finest which I won't bore you with other than to say, "It's no Beauty Queen". This is one area that could definitely benefit from the expertise of an industrial designer of UIs rather than some software hack looking to the other equally horrible efforts of their perceived competition (Rigol and the A brand product lines).

 The staggeringly (in hindsight now) uncritical praise by reviewers such as Dave Jones and that guy that did the tear down of that famous 1,3 million dollar Keysight 113GHz BW 'scope must surely have been down to their limited experience with only A brand (and Rigol) kit to compare against the Siglent gear they've reviewed.

 Mind you, I thought Dave had reviewed at least one of the more recent FY66/6800 AWG models? Perhaps I'm thinking of a Defpom review (but even he failed to say "Phewey! This UI sure does stink!" when he reviewed the SDG1032X). Perhaps they were so hung up over the performance specifications, they neglected to pay any mind to what I now see with the benefit of my FY6600 experience as glaring deficiencies in the UIs of T&M kit in general (apparently, Siglent are better than most in the UI department ::) ::) ::) ).

 In the light of my experience with the FY6600, it would seem that all these highly regarded reviewers have (undoubtedly unwittingly) done a great disservice to their Youtube audience by not offering scathing criticism of the UI quality of this class of T&M kit (DSOs seem to have attracted the cream of the software talent available within each manufacturer's pool of such developer talent, leaving the function generator departments having to make do with the dregs).

 My remarks following this edit insert still apply despite Labrat101's findings with his own FY6800's fake/clone Cyclone FPGA IC. In his case, I think the problems he's discovered are more to do with having the bad luck to receive an FY6800 with a faulty clone FPGA rather than just the fact that it used a clone FPGA.

 I don't believe that Feeltech had decided out of the blue to start using cheap clone Cyclone chips with the introduction of the FY6800 (BICBW) when it seems more likely that this had all started with the very first FY6600 models. With the benefit of Labrat101's findings, it just means you now have some more tests to perform to make sure a new FY6800 or (on topic in this thread) FY6900 is free of these and previously discovered defects before risking all by modifying the (bean counter instigated) crap out of it and invalidating its nice shiny Chinese waranty.  :-DD :-DD :-DD :-DD

[END EDIT]
===========================================================================================

 For any cash strapped hobbyist, the FY6900 makes an excellent first AWG choice. It stands head and shoulders above its peers (other cheap Chinese toy signal generators). Indeed, this had also been the case for the 6600 and 6800 models which it supersedes.

 By "cash strapped hobbyist", I mean someone with at least the basic skills to wire a 4.7K resistor between the PE tag of the C14 socket and a convenient connection point on the ground rail of the main board, along with the ability to at least undo the vandalism to the ground return wire in the 6 wire ribbon cable between the PSU and main circuit board and fit a 40mm square 12v fan into the unpopulated fan aperture in the rear panel and connect it to the 5v rail to quietly reduce the internal temperature to less insanely high levels. >:D

 There, I've just pointed out the three cheapest and highest priority (most essential) modifications that any "cash strapped hobbyist" should do to protect their modest investment. ::) There's no need to thank me for this sage advice (a simple click on the "Say thanks" button will more than suffice if you insist). >:D

JBG

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 26, 2020, 04:41:40 pm
I noticed that the FY-6900 is getting rather hot during standby. Is this common?

 Too bloody right, it is! As was the same for its predecessors, the 6600 and the 6800 models. Luckily in this case (literally!) the simple cure of installing a small 40mm square 12v fan and powering it from the 5v rail to give quiet relief from these electrolytic capacitor frying temperatures is even easier on account of the existing 40mm square fan shaped aperture in the rear panel (you'd had to cut your own fan aperture into the 6600 and 6800 cases to start with).

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on July 26, 2020, 05:07:32 pm
John

don‘t jump to short. I‘m pretty happy with my new SDG2042 (now 2122) and would not hesitate
to invest the 500€ again.

Have look at Welectron in Germany as long as the EU has not left your island  :=\.
I think the 6 month or 12 month financing offering can shift the monthly burden into the ground floor noise
of your familiy budget  :popcorn: And Welectron delivers the calibration certificate  :-DD

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 26, 2020, 06:37:20 pm
Wow ...
Johnny I can feel your blood boil with just mentioning the name FY**** .
18 months of trying to get your moneys worth out of this P.O.C.C.
   Your Not alone .
The only reason I bought My 68 .  A year ago, was the Specs were so good I just could not believe it was Possible for $100 apx. ( Its Not  :wtf:)
I was going to buy the Siglent 2000 model .. Really sorry now . Next time I won't penny pinch .
 As we both know the time and effort spent upgrading  :horse: ..  We could have  invented a time machine ..
 OK, its been a Big learning curve and killed a lot of retirement boredom.
 But Keep your cool .
 Lets all buy a really good AWG and make a New Post .. .. OH " it just works Great out the Box ".. Bummer I'M bored .  :-DD
 
 :popcorn:
RNS
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 26, 2020, 06:51:09 pm
I noticed that the FY-6900 is getting rather hot during standby. Is this common?
The standby only turns the display off ... The PSU is still running on full load .. >:D

 Not quite full load, just very close to.  :)

 I reckoned in the FY6600's case it was no more than a 2 watt saving at most (a change of ~7 to ~5 watt). When testing to ascertain the lowest possible standby power state, I discovered that the relays made a contribution of 140mW each with no more than two of them possibly being operated at any one time, depending on whether either or both channels had been set to output in the 500mV to 4.99V range (the lowest possible standby power configuration). After taking account of the presumed effect of an 80% PSU efficiency, this translates very closely to as much as a third of a watt variation in the standby power consumption figures.

 Since applying my one turn buck winding modification to the PSU to efficiently increase the +/- 12v rails to +/- 12.7v (they had been a volt lower than this prior to any modifications), the current maximum possible consumption with square wave output on each channel driving 50 ohm loads at the 20v p-p setting (10v p-p loaded), including that of the 1.3 watts consumed by the OCXO's 12v 0.5A smpsu, I can see a peak consumption of 10W measured at the mains socket.

 Since this means a total combined output power of 1W into the 50 ohm dummy loads, that leaves all of the balance (some 9 watts in my case, otherwise 7.7W without the OCXO modification) being dissipated inside the confines of such a small effectively unventilated plastic box which results in rather high internal temperatures.

 Even with just 7,7 watt's worth of dissipation, the inside of that generator still runs far hotter than is good for the service life of its electrolytic capacitors which is why a small 40mm square 12v fan powered off the 5v supply rail can make such a dramatic difference and the reason why I'm such a fan of this fan modification.  >:D

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 26, 2020, 09:09:11 pm
John

don‘t jump to short. I‘m pretty happy with my new SDG2042 (now 2122) and would not hesitate
to invest the 500€ again.

Have look at Welectron in Germany as long as the EU has not left your island  :=\.
I think the 6 month or 12 month financing offering can shift the monthly burden into the ground floor noise
of your familiy budget  :popcorn: And Welectron delivers the calibration certificate  :-DD

 I appreciate the advice but being in the UK, I'd be looking at a UK based Siglent agent such as Labtronix or Telonic rather than one based in Germany (besides which, such financing has never appealed to me, especially as I now have some savings to burn up before the grim reaper comes to collect his prize - not that I'm all that much of prize in most anyone's view anyway).

 Other than the issue over Telonic routinely removing these certificates of calibration from the boxes, I've been very pleased with the service I've had plus they'd given me a nice discount on the price of the 'scope and timely delivery. That certificate isn't a proper calibration certificate anyway since it lacks any actual test measurement data results (that cryptic reference that Karen's email had made to explain why these certificates are removed from the box).

 As for that paper 'certificate', well, paper is just paper and 'ink', no matter the pretty patterns it creates, is just ink when all is said and done - the pdf copy is just as good despite my disappointment at not finding a paper copy packed into the shipping box.  :( ::)

 The main reason I'm considering the 210 quid cheaper SDG1032X over the SDG2042X is that the more expensive of those only goes to 25MHz square waves with rise and fall times of just 9ns in all variants whilst even the unhacked 1032 does low jitter square waves up to 30MHz and 60MHz when hacked to a 1062 both with respectable rise and fall times of 3.8ns at 2.5v p-p into 50 ohm loads. If the 2042 had included the special square and pulse wave feature of the 1000 series, my choice would have been to invest the extra 210 quid on a 2042 and hack it to a 2122.

 Obviously, the choice depends on what you think are the more important features to best meet your current and not too distant future needs. At this moment, I believe the square wave performance is likely to be of greater importance. I may live to regret not investing the extra 210 quid in a year or two's time but at least I won't be regretting having a better square wave generator feature for 210 quid less than I'd paid for the 2042.

 If in hindsight, I come to regret my decision to buy the cheaper model, well, that's easy enough to put right, and quite possibly for less than the current asking price of the 2042. If in doubt, choose the cheaper option since you may well have a much better choice a year or two down the line when you might be able to skip the 2000X series altogether. >:D

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 26, 2020, 10:27:05 pm
Wow ...
Johnny I can feel your blood boil with just mentioning the name FY**** .
18 months of trying to get your moneys worth out of this P.O.C.C.
   Your Not alone .
The only reason I bought My 68 .  A year ago, was the Specs were so good I just could not believe it was Possible for $100 apx. ( Its Not  :wtf:)
I was going to buy the Siglent 2000 model .. Really sorry now . Next time I won't penny pinch .
 As we both know the time and effort spent upgrading  :horse: ..  We could have  invented a time machine ..
 OK, its been a Big learning curve and killed a lot of retirement boredom.
 But Keep your cool .
 Lets all buy a really good AWG and make a New Post .. .. OH " it just works Great out the Box ".. Bummer I'M bored .  :-DD
 
 :popcorn:
RNS

 Well, my annoyance lies with the bean counter in chief whom FeelTech must have employed to best inspire the final production version's minor but annoying deficiencies to produce a cost effective half built AWG project kit aimed squarely at the cash starved hobbyist market demographic who would jump at the chance to make it their very own by modifying the hell out of it (and in so doing, invalidate the worthless Chinese warranty into the bargain - a win win for FeelTech).

 Most of the glaring deficiencies can be easily fixed by a keen and knowledgeable (or inventive) hobbyist for very little cost. A small cooling fan in all three models, a C14 socket replacement for the C8 in the 6600 model along with a half watt wire ended 3.3 to 10 K resistor and a rewire of the earth connection in the 6800 and 6900 models with a 3.3 to 10 K resistor to eliminate the earth loop issue and suppress the half mains live voltage ESD hazard of the 6600 model to address the two most serious and pressing issues for starters.

 The rest of the more ambitious modifications discussed in the FY6600 topic thread can be considered optional by most hobbyists, depending on their particular interest and needs. Considering the very cheap price, you do actually get quite lot for your money but at just circa 100 dollars US, there are limits, some of which can be extended relatively cheaply and others that are insurmountable, like the 4ns jitter issue on pulse and square waveforms (although the Sinc pulse waveform is surprisingly free of this 4ns jitter).

 Like your good self, I too was persuaded by the published specs which compared favourably to the SDG1032X in a swings and roundabouts sort of way at the time. So, on the basis that a 76 quid mistake was easier to swallow than a 360 quid mistake, I took a punt on the much discussed FY6600 and had myself a new obsession.  ::)

 As you so eloquently put it " its been a Big learning curve and killed a lot of retirement boredom", you hit the nail right on the head. :) And, the observation you made about starting a topic on a really good AWG has also hit the nail fair and square on its head. Let's face it, Novelty doesn't have much endurance, not even the novelty of perfection. Warty things tend to be of more enduring fascination (and let's face it, that FY6600, like its successors, had no shortage of warts for discussion >:D ).

 BTW, I have no regrets about buying that FY6600. As you mentioned, it gave me a lot of experience that will allow me to more fully appreciate whichever of the SDG models I finally choose to spend my hard earned on (the 1032 is the main contender at the moment). TBH, I doubt you really regret buying that 6800, I'm sure you must have learnt a lot from the experience, good or bad. If nothing else, you'll have a much better understanding of what you'll want out of your next AWG purchase. :popcorn:

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 27, 2020, 09:32:33 am
Quote
BTW, I have no regrets about buying that FY6600. As you mentioned, it gave me a lot of experience that will allow me to more fully appreciate whichever of the SDG models I finally choose to spend my hard earned on (the 1032 is the main contender at the moment). TBH, I doubt you really regret buying that 6800, I'm sure you must have learnt a lot from the experience, good or bad. If nothing else, you'll have a much better understanding of what you'll want out of your next AWG purchase. :popcorn:

Yup .. retirement Fixing things is a great pass time and fun.
 If only I could figure how to interface my Brain to a USB and get a new Updates would cut the learning curve  :-DD,
yup..your Right.. I guess if I had not bought the 68 . I would Not have had to read 15000 posts to catch up.  :-DD
  And been reading the News instead  ..   That really sucks ..  :palm:

My project with my fy68 has come to an end .. Run out of space in the box .. and unless some cleaver programmer can make a update to the firmware . and sort the final Jitter out on the software .
 which I don't think that will happen .
I did get the jitter down to 2ns but the firmware makes it side shift which is even more annoying
 so that is a dead end.   left as is.

Herr :-//.. what can we mode now .  Doc. Herr  :-//

 :popcorn:
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on July 27, 2020, 02:36:28 pm
Quote
BTW, I have no regrets about buying that FY6600. As you mentioned, it gave me a lot of experience that will allow me to more fully appreciate whichever of the SDG models I finally choose to spend my hard earned on (the 1032 is the main contender at the moment). TBH, I doubt you really regret buying that 6800, I'm sure you must have learnt a lot from the experience, good or bad. If nothing else, you'll have a much better understanding of what you'll want out of your next AWG purchase. :popcorn:

Yup .. retirement Fixing things is a great pass time and fun.
 If only I could figure how to interface my Brain to a USB and get a new Updates would cut the learning curve  :-DD,
yup..your Right.. I guess if I had not bought the 68 . I would Not have had to read 15000 posts to catch up.  :-DD
  And been reading the News instead  ..   That really sucks ..  :palm:

My project with my fy68 has come to an end .. Run out of space in the box .. and unless some cleaver programmer can make a update to the firmware . and sort the final Jitter out on the software .
 which I don't think that will happen .
I did get the jitter down to 2ns but the firmware makes it side shift which is even more annoying
 so that is a dead end.   left as is.

Herr :-//.. what can we mode now .  Doc. Herr  :-//

 :popcorn:

 I know what you mean but a direct USB interface won't help, our brains have been evolved to absorb high data rate information via our senses of smell, sight and sound (pretty much in that order over the past 500 million years or so) so we use the intermediaries of display screens and loudspeakers (smell is a low bandwidth low priority channel in humans) to translate such data streams via USB and other serial interfaces. That's about as direct a link as we can create out of our technology.

 The bottleneck on learning new things is beyond the reach of a direct USB connection, hence all the development put into data format translation devices such as monitor screens and loudspeakers since it avoids the half million years or so lag in human evolutionary development that would be required to adapt the brain to cope with such direct data transfer streams. It's far easier to use a format/protocol translator to convert the format into a form our brains have had some 500 million years worth of development to work efficiently with and eliminate this half million year delay - go with what you've already got, this is one wheel we definitely don't want to waste time reinventing.  :-DD

I'm fairly sure that 15,000 posts figure must be an exaggeration. However, let's check: You joined just last November but you could've been reading the EEVBlog posts for a year before then, so assuming a total reading period of, let's say, 750 days, that equates to some 20 posts a day on average... Ok, I take that back. It's quite possible that this figure is no exaggeration after all. :o

 I guess you're referring to the global news on TV and in the newspapers. I know what you mean. The news is rather too "Interesting" these days but not in an amusing way, more in the sense of the "We live in interesting times" Chinese Warlord quote. Since it's pretty much been like this since WW II and just gradually getting worse, it just gets more and more depressingly boring for anyone who's managed to survive into a gentle retirement.

 Life's short enough without over-contemplating humanity's propensity for its various civilisations throughout all of history to date, to sleepwalk its way into a terminal disaster. What makes this particular exercise in somnambulism particularly worrisome is the fact that the civilisation in question this time is a global one where, unlike all the previous civilisations restricted to relatively small geographic areas, there may well be no way of coming back from this disaster by way of other less despoiled habitable regions on our little dirt ball. So yeah, I know just what you mean (I think!). ::)

 I guess it's all about knowing when to stop. And, reaching the stage when you've got the box crammed to capacity with mods is a very good indicator to my mind. :-DD

 You could review what you've done and realise that a well laid out circuit board could contain everything you've done so far and still leave room to spare for additional mods. At which point, you step back and consider the worth of redoing this to a better more compact and efficient standard and realise you'd best leave it as it is and just go out and buy a new higher quality AWG from the Siglent line instead and have done with it. :-DD

 I like your final line. It looks like a "Bugs Bunny"ism - I enjoyed those Bugs Bunny cartoons as a kid and long into adulthood. :) Anyway, it seemed an appropriate way to sum up your new predicament.  :)

 Like you (and doubtless many others), I've reached the end of my tether on this particular project. I'm particularly proud of my OCXO with injection locking external reference interface modification but Life's much too short to waste, tinkering any further, with this piece of cheap kit.

 The one good thing to come out of all this modding activity is that I'll be a lot happier to splash the cash on one of those Siglent AWG models than I'd have been some 18 months back. It's certainly changed my mindset in that regard. :)

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 27, 2020, 07:48:48 pm
 
Quote
know what you mean but a direct USB interface won't help, our brains have been evolved to absorb high data rate information via our senses of smell, sight and sound (pretty much in that order over the past 500 million years or so) so we use the intermediaries of display screens and loudspeakers (smell is a low bandwidth low priority channel in humans) to translate such data streams via USB and other serial interfaces. That's about as direct a link as we can create out of our technology.

That's Not quite true there are Thousands of people who have never evolved ..
They are called politicians and run the governments of major country's ..   :palm: 
 And other No Good organisations.. no names but also have not evolved ..

 Thanks to say that most people in this forum are Human and are evolving for the better.

 Yea  Doc you have been eating too many carrots   ..
 I was reading this forum long before before i joined .. I read fairly fast and let my brain catch up later  :-DD

All the best . Have Fun Stay safe
 :popcorn: RNS
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: g2 on July 28, 2020, 09:04:16 am
First thanks to Labrat101, Bad_Driver and Johnny B Good for your really good answers.
I could possibly buy FY6900 and make "the three cheapest and highest priority (most essential) modifications that any" cash strapped hobbyist "should do to protect their modest investment." Quote from Johnny B Good.
When I read earlier Posts:
Reply # 302 had an interrupted sine ... lets do the sine repair in the help function .... turning device out and in (several times) did not help.
Reply # 305 I have the 6800 @ 60mhz also had a few problems ie the power supply went up in smoke after an hour.

I think it's okay for me to buy a device and make modifications, but after that I should be able to trust it and be happy with it.
A week ago I read about the RD JDS6600 and think it sounded OK.
But then I came to Johnny B Good comment: Shit, isn't it, compared to the FY6600 and FY6800 models?
(RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator  «Reply # 197).
The JDS6600 has far from as good data and feature as the Fy6900, but is it more stable, and you know what you get?
Are there any disadvantages to Siglent?
and are 2 channels useful?

Labrat101 comment:
and killed a lot of retirement boredom.
Yup .. retirement Fixing things is a great pass time and fun.
And been reading the News instead .. That really sucks ..
You're right, but I think it has nothing to do with retirement. It's a matter of keeping oneself engaged in something reasonably and still evolving. Electronics are good for that. I'm retired myself.
I think you write it yourself in Reply # 375.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on July 28, 2020, 10:23:32 am
I think it's okay for me to buy a device and make modifications, but after that I should be able to trust it and be happy with it.
A week ago I read about the RD JDS6600 and think it sounded OK.
Quote

First Thanks for the comments .. There is a "Say thanks" Button on the top of each post  :-+

 As for the JDS6600  the only difference is the JDS which is the same exact animal as the FY . the markings on the case different colours.
 Also if you watched the YouTube demo's they all keep the frequents setting well below 1Mhz ..  ie 100Khz the sine square etc are fine.
 But why buy a unit that has a capability of much more 25Mhz  and demo it at low Hz  .. because it would show the yucky faults .
 The Spec sheet could have been written on toilet paper . it would be at least useful one time use  :-DD .
 The 6600 models are the first versions and the software has not been really updated. .
  I would stay clear of the 6600 they may well be very old stock .. The 6900 does have a better firmware .
 The Power supplies do have a lot of harmonic noise as well as being NON iso standard ..  :palm:
 Its sort of the luck of the draw how long the PSU will last . and the earth thing as well .
  If you do buy go for a newer model as there are a few changes ..
    but before you turn it on Take Dave's advice TAKE it a part .. check it well as the wiring etc does not get checked
 Don't worry about the guarantee  its not worth much ether .
  Be prepared to spend about a 100 hours modding it  ... and also read all the modes ..  :-DD   

  JBG modes will give you Many happy hours of reading  :-+

 May the force ''Not'' be with you .. 240vac to earth Ce   :-+   

BTW the sine repair does work on the 6800 I have used it
 There is also A Calibration function Not mentioned in the manual ..
 Hold the power on & Ch1 in and hold while powering up by switch on back..   System / More .. Osci 
 
:popcorn:
RNs
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Fandorin on August 09, 2020, 12:36:59 pm
Hello everybody,

My first post here.
I have plans to buy a signal generator and I was leaning toward FY-6900 60 MHz. But today I was browsing Aliexpress and saw models I haven't seen before: FY-6900 80M and FY-6900-100M: https://www.aliexpress.com/item/4000082390571.html (https://www.aliexpress.com/item/4000082390571.html)
Are these new models? The specifications are suspiciously identical to the 60 MHz model and the only difference is sine wave max frequency. The prices are higher of course - 120 USD and 138 USD respectively.
Has anybody purchased any of these? I will appreciate your thoughts about these models.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on August 09, 2020, 05:00:11 pm
 Those higher frequency specifications for sine waves are realistically attainable with the 250MSa/s sample rate used by the DAC (Nyquist limit in this case being 125MHz). Presumably FeelTech have modified the AA filter to cut off just above 80 and 100MHz (probably just above 100MHz for both those models).

 If you're looking for a cheap AWG that can generate sine waves at frequencies beyond the 60MHz limit of the previous models, the price premium looks quite reasonable if you do have a need to generate sine waves in the 60 to 100 MHz range. I'm assuming that you're already well aware of the non-existent support from FeelTech and the various deficiencies these AWGs have compared to the more expensive mainstream brands.

JBG
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Fandorin on August 09, 2020, 06:16:58 pm
Thanks for the reply.
I decided that the price for the 100 and 80 MHz models is too much for me and will get the 60 MHz. This should be enough for me.
Anyway, it will be interesting if someone buy one of these and post some test results in the forum.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: vutt on August 13, 2020, 06:16:17 pm
I pulled the trigger on KKMoon FY6900 and it's on my way atm.

It looks like one of the most recommended upgrade is ground wire/resistor mod.
I have plenty of Schuko Power Cord donors laying around for nice wire, but what's the recommended wattage rating for resistor? I have bunch of 1/8 watts ones but they feel so tiny for handling potentially mains level current.
I'm fine with little shopping for proper one, resistors are cheap.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on August 19, 2020, 09:37:13 am
Keep it simple. I used a 5.6K 1/4 W resitsor from my shelf.
Take two 10k in parallel - than you are on the safe side.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on September 17, 2020, 03:22:38 pm
OK, so I have a question however I cannot seem to find an answer using the search engine....
So, I made a whole host of mods to the FY6900, but essentially apart from the PSU upgrade, ground, fan etc etc all described in this thread, the most important one was upgrading the reference crystal - I replaced it with a VC-TCXO IQD LFTVXO009900BULK with a 0.9ppm accuracy, and indeed the DDS works like a charm, as there’s no more drift. However, I noticed that there’s an offset, that at 10 MHz is about +170 hz, is there any way to calibrate the FY6900 and remove it? It is vary stable and does not drift (too much).
However, I do not yet have a GPSDO, that’s next on my list, so I am relying on the fact that both my counter (a Fluke PM6666) and my DSO 1202x-e roughly agree on this offset.

Eta pictures
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on September 17, 2020, 11:20:15 pm
OK, so I have a question however I cannot seem to find an answer using the search engine....
So, I made a whole host of mods to the FY6900, but essentially apart from the PSU upgrade, ground, fan etc etc all described in this thread, the most important one was upgrading the reference crystal - I replaced it with a VC-TCXO IQD LFTVXO009900BULK with a 0.9ppm accuracy, and indeed the DDS works like a charm, as there’s no more drift. However, I noticed that there’s an offset, that at 10 MHz is about +170 hz, is there any way to calibrate the FY6900 and remove it? It is vary stable and does not drift (too much).
However, I do not yet have a GPSDO, that’s next on my list, so I am relying on the fact that both my counter (a Fluke PM6666) and my DSO 1202x-e roughly agree on this offset.

Eta pictures

 The short answer is "Yes, there is!" (or rather, there certainly is for the FY6600). However, if you use that hidden menu option, your 'magic'  (free of the 4ns jitter) frequencies at 50, 25, 12.5 MHz and so on, will no longer be jitter free. The best way to address this is to calibrate your VCTCXO to a reference traceable to an atomic standard - a GPSDO (or a RFS that's been recently calibrated within the past year or so :) against a traceable frequency standard (eg a GPSDO  >:D).

 I checked out that VCTCXO's datasheet which suggests there's every chance that your Fluke counter is overdue its next re-calibration (don't place too much trust in your DSO's frequency read out) since the tuning range is specified as being a minimum of +/-5ppm over a 2v tuning range centred on 1.85v (+/-50Hz for a 10MHz centre frequency). The actual tuning range could be as much as double that quoted minimum figure but more likely to be around the +/-7ppm mark.

 Assuming the EFC pin is at the 1.85V mark either by design or from a connection to an external trimpot across the 3.3v Vcc rail and ground, preset to its mid point for the time being until you can gain access to a trustworthy frequency reference by which to calibrate your VCTCXO as exactly as you can get it tuned to its specified 10MHz, it may already be within +/-1ppm of 10MHz to start with.

 IOW, there's every chance that it's closer to 10MHz than your DSO and frequency counter are implying. Wait until you have access to a GPSDO or RFS before attempting to recalibrate it, whether you use the software option or do it the right way with a trimpot wired to the EFC pin of that VCTCXO.  :)

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on September 18, 2020, 06:26:56 am
John, thank you.....
Do you think a small breakout board wired to the pads on the main pcb of the fy6900 with the TCXO and trimpot on it be feasible? If I keep the distance below a couple cm I can avoid using coax cabling. I’m thinking this could also allow for a jumper or switch to route the reference signal to a bnc for the GPSDO to control the DDS.... I imagine there should be a few decoupling caps.
What trimpot do you suggest?

I am shopping for a bg7tbl GPSDO, however I am a bit lost between the various sellers, any opinion on rf-experts on ebay?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on September 18, 2020, 11:26:44 pm

I am shopping for a bg7tbl GPSDO, however I am a bit lost between the various sellers, any opinion on rf-experts on ebay?

I would recommend the Leo Bodnar GPSDO  it works great a little costly but has 2 outputs
and work out the box and accurate 10-12

There is a good chance that your 69 has the same Fake cyclone chip as the 68 and in that
case putting a better tcxo with a faster rise time the cyclone internal correction will fail
 and will produce a ghosting over the waves .
It will give better accuracy if you can live with a badly formed waves . Arb will show over shoot on things like the ramp , Staircase is some thing special more like an escalator .
 
I spent many months trying to solve these problem and have done ever upgrade plus a few of my own . Also the mother board its self has a really bad track error layout problems which means cutting and reconfiguring the tracking solve a few errors but it has too many .
 JBG has the 66 model that has a slightly different layout and is properly better in the Mods

 Have Fun
 :popcorn:

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on September 19, 2020, 06:24:28 pm
Demoralizing :palm: .....
However I did not see the ghosting, can you give me a setting to check on the DSO, where it is obvious?
As for the LB unit I looked it up, they have two, one that is quite affordable at 99£ and the 150£ one....
Thank you for your insight I really appreciate it!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on September 19, 2020, 07:00:43 pm
Demoralizing :palm: .....
However I did not see the ghosting, can you give me a setting to check on the DSO, where it is obvious?
As for the LB unit I looked it up, they have two, one that is quite affordable at 99£ and the 150£ one....
Thank you for your insight I really appreciate it!

Try 11Mhz square wave . Do you get a shadow on both sides of the wave . depending on
your scope speed . the wave will shake as is . appear to wobble from left to right .
on a digital scope it will look like what I call a jelly wobble .
on an analogue it will show a distortion on the rise and fall .

Sorry if I have upset you .

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on September 19, 2020, 07:12:17 pm
Update while its set for 11Mhz set the display to DOTs  & persistence to 1 sec
it will enable you to see the ghost overlay .. its not jitter because its a complete wave
duplication about 15 deg offset

If you have a clean square wave . congratulation yours is working well .
 don't tell any one because you may have the only good one  that slipped by.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on September 20, 2020, 07:18:37 pm
Ok, so now that I see it i realize that I did notice it in the past.
There’s ghosting at basically every MHz step above 1 MHz. But, wasn’t that there before? I did this upgrading the TXCO????
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on September 20, 2020, 09:01:26 pm
Ok, so now that I see it i realize that I did notice it in the past.
There’s ghosting at basically every MHz step above 1 MHz. But, wasn’t that there before? I did this upgrading the TXCO????
The 69 had added what they called Magic jitter or something like it.
 which by using software they tried to fix what the internal clock phase circuit that is hardwired into the cyclone developed by its original manufacture Intel .
Which very cleverly counts the xtal pulse and compares it to the last if there is an error it ignores bad pulses it then carries on . So it removes jitter . So any drift of frequency is corrected.  From what I understood from the documentation from the Intel doc's .
its PLL 's &  DAC array  . Also the cyclone was designed to have an internal clock speeds upto
100Mhz .  I checked my cyclone in my 68 and those pins are not operational nor are the ref points operational which are hardwired and not software controlled .
 I worked in Intel for nearly 10yrs and I know that no substandard chip ever left the FAB without being destroyed .

 Actually your square wave is not that bad  >:D.
  I have got a 4ns on both sides but I put an OCXO in and has a very fast rise.
 This is when I realized that there was a bigger problem that I should have guessed right at the begin .
 As I mentioned it an early post . How can any one produce a item like this for around
 $80 and the cyclone cost on its own nearly $35 - 40 . maybe buy a million and get 30% off.
 The DAC s are also properly  not original that's why they scratched the numbers off .
 The PCB has cross talk as well . .
 The error  can also be seen in the FFT  If your scope has a good range

 So if you do upgrades be careful not to change the voltages etc that there software is monitoring  also the High Z resistors are 82ohm. aprox .
  I did not change mine as I gave up trying to make  a round peg fit into a square ..
 
    OK 20KG hammer would solve the Peg problem  :-DD

   Sorry No Bad feelings .
 
  There is another panel not shown in Photo of the 10mhz board Ref Frequency,
 which uses the bottom 2 BNC connectors
 Note is hard to see the name on the Cyclone .  it sort of rubs off
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on September 20, 2020, 10:56:48 pm
What hard feelings? Nahhh at least I know now to simply stop... I got nowhere near your level of tinkering inside my 6900, basically PSU mods, ground improvement, additional 7V PS to power a 12V fan, placed Raspberry Pi heatsinks on everything my thermal camera said it needed, improved heatsink for the opamps and the TXCO replacement. I got second thoughts on making an adjustment board for the TXCO....

 Maybe I will improve the PAD on the output like masterx81 did on his copy of the thing - I'm having difficulties getting the resistors to do it.



 So if you do upgrades be careful not to change the voltages etc that there software is monitoring  also the High Z resistors are 82ohm. aprox .
  I did not change mine as I gave up trying to make  a round peg fit into a square ..
Uh that means I am not supposed to change the 82-85ohm pad to 50? Your suggestion is not clear
My scope is a Siglent SDS1202x-e.

Next step, learn as much as possible until I got enough dough to move on to a real DDS, even a "cheap" one like the Siglent SDG2042X, and maybe keep the 6900 as a backup. The specs remain impressive all the same, I have to move to the 2000x series to have basically as much stuff as it, for ten times the money. But, yeah, its a pile of crap.
Thank you for your kind help.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on September 21, 2020, 10:34:48 am
What hard feelings? Nahhh at least I know now to simply stop... I got nowhere near your level of tinkering inside my 6900, basically PSU mods, ground improvement, additional 7V PS to power a 12V fan, placed Raspberry Pi heatsinks on everything my thermal camera said it needed, improved heatsink for the opamps and the TXCO replacement. I got second thoughts on making an adjustment board for the TXCO....

 Maybe I will improve the PAD on the output like masterx81 did on his copy of the thing - I'm having difficulties getting the resistors to do it.



 So if you do upgrades be careful not to change the voltages etc that there software is monitoring  also the High Z resistors are 82ohm. aprox .
  I did not change mine as I gave up trying to make  a round peg fit into a square ..
Uh that means I am not supposed to change the 82-85ohm pad to 50? Your suggestion is not clear
My scope is a Siglent SDS1202x-e. 

Next step, learn as much as possible until I got enough dough to move on to a real DDS, even a "cheap" one like the Siglent SDG2042X, and maybe keep the 6900 as a backup. The specs remain impressive all the same, I have to move to the 2000x series to have basically as much stuff as it, for ten times the money. But, yeah, its a pile of crap.
Thank you for your kind help.
Siglent SDS1202x-e.   :-+ :-+

Hi I would leave the Pad alone as it won't help much . also I found that they choose those values were to try and correct the capacity of
the low grade relays. . On my photo you will see i put a 10pf cap on the opamp output after the filter .
This is to correct the contact capacity of the relay . which makes the square wave much sharper . but it does not cure the jitter/ghost .

The Only reason I bought this in the first place was that I could not Believe that the Specs could be that good for $80 .
 So I took the Gamble .. Naa next time I will but my money on the  :horse: at least I will know it will always be in last place.
 My FY68 failed after only 2hrs of operating the SMPS gave off Magic smoke and very nice toasty .
This is what started the whole long STORY   :-BROKE  .. They would not except a return and gave me 30% refund and said get
someone to fix it.  :palm:  . .
 So I came to the conclusion that FY roughly transliterated into English =  FuckYou .

 I had added a 20Mhz CTS OCXO  2PPB with a PLL @ x2.5 to give 50Mhz and a divide by 2 from the PLL ref pin to give me also
 10Mhz out reference and was adjust with the Leo Bodnar to a 10.000,000,001 Mhz .  :-+.
I now only use this !!68 for reference frequency .

I ordered a UTG962 from Uni-T direct a month ago and was sent via DHL who in there wisdom put the wrong Address code. :palm:
 what happened to Copy&Paste . Ok they have now resent it via Fedex and If the Gods are with me should arrive in the next few days.
 
 As for me this project is dead and the only further upgrades will be carried out with the delicate swing of a 20KG hammer.
 Of course I will remove my OCXO first ..
 

 Just out of interest can you take a close up Photo of your main PCB  I would like to see IF they made any changes to the panel layout.

BTW you mentioned  Raspberry Pi  what were you using this for?
  About the TCXO adjustment use JBG advise there
:popcorn:
  RNS
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on September 23, 2020, 02:38:36 pm
Hi Friends,

there is a new kid on the block:

https://www.eevblog.com/forum/testgear/juntek-psg9080-programmable-signal-generator-(80-mhz-300-msas-14-bit)/ (https://www.eevblog.com/forum/testgear/juntek-psg9080-programmable-signal-generator-(80-mhz-300-msas-14-bit)/)

Seems to be better than the Feeltec crap. Watch DefProms YT-tear down. Can be a chance for a new generation of enthusiastic hobbyist to spend weeks
in improvements  :-DD

I like Labrat's idea with the big 20 kg hammer. I noticed that I after having finished the OCXO and PSU update of my 69 and buying the Siglent SDG 2122 (2042 before improvement) never touched the FY  |O

So I think I will it rebuild into the state of origin. The PSU I used for improvement and the OCXOs demands is industrial grade and I think it will have a bright future with another project. The FY PSU can spend the rest of it's life in the plastic box.

cu B.D.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on September 23, 2020, 07:13:10 pm
Hi  All I finery  got my long awaited UTG962 ..

 So I had to run some quick test plugged it in all fired up .. in cheesiness   :wtf: armed with the Samsung phone translator
put it into English no big deal . 2mins .
  The first thing I did was set the limit from high Z to 50 ohms . and set the sine to 60Mhz .. OK not bad at all . not perfect but
 liveable .
Next the big test the SQUARE wave 1mhz  :-+ . 5Mhz  ok what's going on the display I noticed shows a trapezium and as
 I increase the Mhz it gets more and trapezium  :wtf:
 The GOOD news there is NO jitter or wobble or shacking .
So I tried the pulse . very nice has the same the Rise & Fall time can be set . But the minimum setting is 15ns .
 But the manual and the spec say it can go to 20Mhz Square . I sent them a message to quire this .
 Other than that the controls and the setting are really good and also a lot of presetting that are very nice .
over all it has some amazing features  . There are lots of menus  and it also has a sinc out .
The Screen is really nice and clear to read .
over all its far better than the FY68 with a lot of fine tuning available  .
The overall frequency accuracy is from a regulate TCXO  so the 10mhz is a little off maybe 2sec a day  (30ppm) :scared: (not for time nuts)
The over all foot print is very small 180 x 95 x 70  . I could drop it inside my Old Tektronix TDS 340 and take a week to find it.
 
The only down side is the slow Rise & Fall time being 15ns .

I will do some more test on it .. and I am not going to buy any more stuff for awhile ..

 Update I just checked the sinc out pulse and that is clean upto 20Mhz square @ 4ns  perfect square there is a hidden power
 it just need a small mode some where .. but as its still under warrantee I am Not opening it .

 :popcorn: :popcorn:
 PS.. Really Need a scope with 200Mhz+ bandwidth to see 20Mhz Square 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on October 09, 2020, 09:34:37 am
As explained I used a free hour to rebuilt the FY6900 into it's state of delivery before all my PSU improvements.

I kept only the wiring with the drain resistor and the fan.

Unfortunately I forgot that I killed the weak 10 MHz XO during desoldering since I don't own a SMD station.
So I was faced with the problem to find a new XO.

As mentioned above I used for my improvements a 3.3 V OCXO (Vectron) with the new PSU.
It takes during warm up about 1 A later 0.3 A.

I gave the origin PSU of the FY69 a chance and I was surprised!!
It has enough reserves to feed the additional 1 A  from the 5V line into my simple 3.3 V LDO-OCXO solution.

At the end I have a FY6900 with the original PSU, a fan, a earth-drain resistor-ground wiring and a 3.3 V OCXO that is feed from this PSU.
Now the FY can R.I.P. on the shelf. |O

btw: Is there a new firmware for the FY on the market?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Ernest1 on October 09, 2020, 01:33:28 pm
Oh wow, poor FeelTech lol.

Are these that bad? I mean the price seems reasonable or is there something better at a lower or same price?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on October 09, 2020, 07:27:57 pm
Oh wow, poor FeelTech lol.

Are these that bad? I mean the price seems reasonable or is there something better at a lower or same price?
Do you want the short answer . YES .. Total waste of money More Bugs than you have in the Garden.
If you want a Good AWG at  almost the same price that just works out the box.

 Go for the UNI-T UTG962  .  I have bought 1 and it just functions great .
 The link for the OEM supplier .
 https://www.aliexpress.com/item/4000373256414.html?spm=a2g0s.9042311.0.0.49434c4dAwQI7Y (https://www.aliexpress.com/item/4000373256414.html?spm=a2g0s.9042311.0.0.49434c4dAwQI7Y)

 The Manual Downloadable  from  www.uni-trend.com (http://www.uni-trend.com)
   :popcorn: 
           Be happy Don't go for a non functional AWG   ..
 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: precaud on October 10, 2020, 02:31:25 am
Are these that bad? I mean the price seems reasonable or is there something better at a lower or same price?

There's a lot of hyperbole flying around about how bad the FY6900 is. Sometimes I wonder if these folks actually use test equipment for anything, or whether they just test and opine on it. It takes very little effort to make this a very usable FG. Mine is replacing my HP 8116A while it gets cleaned, recapped, and a quieter fan in my spare time. I like the HP's user interface better. Very fast and easy. But the little FY is doing OK otherwise.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Bad_Driver on October 11, 2020, 08:25:58 am
I paid for mine about 80€, and it is worth the money. And while playing with it and with the help
of this forum I learned a lot about current arbitrary function generator technics. That is my benefit
from this little toy.

You can‘t expect HPAgiseight performance. As described you can simple fix the earth-ground wiring,
and put the fan into it‘s designated place. But it is a a very light plastic box, it slips on the desk with
every key pressed.

And it should be no problem for the vendor to improve the graphics and the fonts
and the shown digits on the display. There were enough advices in this board. But there is no improvement for a year or so.
At the end it‘s your decision, but I became during working with it the strong desire for a more professional
device, as mentioned I bought a Siglent SDG 2042 (which improved itself into a 2112 without soldering  :-+)
and I‘m happy with it (but that costs about 6 times more).

At the end my conclusion is this: it does the job in many cases but it is no pleasure to work with it.
It is a good beginners device but you get appetite for more. I tried to stay fair in relation to the price.

Any comments?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on October 11, 2020, 05:28:48 pm
Hi Bad-Driver
As you said is correct If one requires AWG that they spend more time fixing than using
its  ... OK .
  From my experience it was a good time waster . 
   Pros .. meet interesting friends on this forum .
   Con's  Yes  Too many to list.  at least 1200 blogs on this forum alone .
 But its the same as buying a clock That does not tell the correct time .
 It works, it chimes on the hour . But not on any particular Hour .   :palm:

Also it comes complete with all Fake chips ie the cyclone .. The Heart  :wtf:

 Live long and Prosper spend the extra  bucks
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on October 15, 2020, 03:42:19 am
 Incredibly, my modified FY6600-60M proved to be a considerable improvement in many ways over an SDG1032X that I'm now returning for a full refund on account of a rather strange and seemingly rare instability afflicting its internal clock reference (I suspect it's the same 25MHz +/-25ppm rated smd xo as used in the earlier SDG1025 model - the SDG2000X series use a 10MHz metal lidded +/-10ppm smd part for its internal clock reference).

 After discovering the work around solution of feeding its external 10MHz clock reference socket from a low phase noise GPSDO reference to eliminate this peculiar LF jitteryness in the internal clock (which, BTW, can be exported via this socket and show the exact same jitteryness), I discovered that the frequency control UI would only accept up to 8 digits worth of resolution when selecting each digit for adjustment via the rotary encoder.

 However, it is possible to enter a total of 11 digit's worth when using the keypad before pressing the multiplier key (MHz in my case) whereupon the placement of the MHz multiplier would stamp over the last three digits, causing the displayed frequency to be rounded to the nearest 8 digits even though it had actually accepted the full eleven digits that had been entered. Furthermore, the lack of the 'sticky digit cursor position of the FY6600's frequency selection UI adds even more pain to what is, quite frankly, an execrable UI experience (and there's even worse which I won't bore you with).

 Now you might be thinking, "But, Johnny, that's only the UI which can be fixed with a firmware upgrade - it's not fully set in stone, surely the rest of the specifications are considerably better than what Feeltech's "toy" has to offer?" Well... (a small) yes and (a large) no.

 The extra 200 quid didn't buy me any enhancements to the Feeltech's feature set (and this is for a modified FY6600 rather than the better FY6900!) that I couldn't live without. To achieve that state of AWG nirvana, you need to spend yet another 200 quid more on an SDG2042X before you can safely consign your FY6xxx to the spares cupboard. >:( :(

 For instance, most, if not all of the DDS ARB functions are limited to a maximum frequency of just 6MHz versus the 18MHz they can typically be pushed to with little ill effect in the case of the Feeltech "toys" (the trueArb option for instance, limits the Sinc pulse function to a maximum limit of, not the 1.8MHz I'd initially assumed was being shown in that hard to read when selected frequency display but, incredibly, just a mere 1.8KILOHERTZ!!  :wtf: :wtf: :wtf: :palm:

 These SDG1000X and 2000X series of AWGs do provide a nicely built fully shielded enclosure to prevent ingress of any EMI within the lab/workshop environment. However, that does introduce the issue of mains earth ground loops (solvable with a pair of heavy duty low voltage silicon diodes wired in anti-prallel with a 1K resistor across them placed in series with the protective earth connection to open circuit this king size magnetic loop antenna under normal operating conditions - the diodes short out any otherwise dangerous voltage in the event of a live contact with full mains voltage from any source, thus blowing the safety fuse involved or trip out any ELCB/GFCI circuit breakers at the CU). The low jitter full frequency square wave feature of the SDG1000X series, nice as it is, simply doesn't justify all the other performance shortfalls as a result of downgrading from an FY6xxx series AWG to this Siglent model range.

 For anyone looking to upgrade out the "cheap toy AWG" category, the best bang for your buck option appears to be Siglent's SDG2042X right now. Rigol stopped being any competition against Siglent some years back and it's the likes of Feeltech Siglent should be keeping their eye upon as of at least the past two years.

 Closer inspection of Feeltech's competitor products in the same 100 to 150 dollar price bracket just looks like a switch would be pretty much an exercise in swapping one frying pan of pain for another to my mind. If you've outgrown the limitations of an FY6xxx then it's time to stop wasting money on more of the same and contemplate, at a minimum, an SDG2000X series or one of the A brand offerings and spend some real money.  ::)

 Harking back to LF jitter issue with the SDG1032X I received just over a week ago, I do believe I'd witnessed a similar phenomena with my FY6600 before I'd upgraded its crappy ten cents 50MHz XO chip almost two years ago to an off-board 50MHz 0.1ppm TCXO. Back then, the only other signal sources I could play with had been a collection of salvaged DIP14 XOs with which I'd played a game of "Chase Will 'O' the Whisp" trying to match frequencies against the FY6600.

 Not only was I fighting the execrable stability of a ten cent XO being roasted alive at 55 to 60 deg C from the 65 to 70 deg heat off a trio of LDO regulators just 1 cm away as well as the slower thermal drift in my DIP14 oscillators, I do believe I was also having to contend with a similar LF jitter effect in the ten cent smd XOs Feeltech's bean counters had insisted upon using. ISTR that this game of "Chase Will 'O' the Whisp" seemed a whole lot easier after upgrading to the 0.1ppm 50MHz TCXO board.

 I've long since replaced that upgrade with a 10MHz OCXO and a 3n502 clock multiplier chip. In the light of recent events regarding an all too familiar looking clock reference instability in the SDG1032X, I decided to repeat this game of"Chase Will 'O' the Whisp" with 5 and 16 MHz DIP14 oscillators to refresh my memory. I had little difficulty in matching frequencies and, after covering the solderless breadboard I'd plugged the oscillators into with a cotton rag to shield them from random cooling air drafts, I could only discern a small amount of frequency drift, comparable to the 50MHz 0.1ppm oscillator board I've just shot a ten second movie clip of by way of comparison to the jittery sine wave output from the SDG1032X I'd recorded last week.

 The 50MHz is the green CH4 trace compared to the GPSDO stabilised 10MHz sine (yellow CH1) and Sinc pulse (blue CH3) outputs from the FY6600 with the RFS connected to CH2 (purple). I'm triggering from CH1.

 I've attached both movie clips and I'd be interested if any of these look familiar to anyone who has ever tried playing this particular game of "Chase Will 'O' the Whisp" with any of the FY6900's predecessors (I doubt the FY6900's 10MHz XO would be similarly afflicted but you never know). BTW, if you haven't already guessed, I'm displaying the SDG1032X's output on CH2 in this video.
 
 I've had to append the .zip extension to the attached files in order to bypass EEVBlog's waste of time filename restrictions. For any newbies, after downloading them, either remove the .zip extension or else use the "Open as" option and choose VLC media player (or whatever your poison of choice happens to be).

John

PS I almost forgot to mention that I'm expecting delivery later this morning of an SDG2042X from my favourite T&M kit supplier. :)

[EDIT] It did arrive this morning (11:45 UTC). Pretty snappy delivery considering they'd only confirmed that they'd received the payment less than 24 hours ago. :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on October 15, 2020, 06:36:34 pm
Hi Johnny
I tried to open your ZIPs both seem to be corrupted .  Could you re do them .
That was a very long story .
I have said all along that the FY6600 cyclone chip was original .
The Fake chips were in the FY6800 .. &up
But I have found a new use for my FY6800 I have Locked the frequency @ 40 Hz Cmos Square and added a power transistor
to the output .  And I am using it as a Gamma Strobe for my wife who suffers from Dementia .
I left the OXCO in place and calibrated with my new Leo Bodnar GPSDO .
 And it has been running for about a 2 week  . It has help a little but as she is in the really last stages .
 Today I off set the frequency by just 0.05 hz .. WOW wont do that again . The brain sinc has to be the
same locked frequency zero drift . So it's back to 40.Hz 10-9.  . This should have been done 8yrs ago.

 Sorry to hear that your Siglent AWG was not up to standard .
I have been very Happy with my New UTG 962 .
 I have not been able to reproduce any of the jitterery stuff that the FY6*** has ..
 The display as I call it is What u see is what you get on the scope exactly .
The oc is very good the spec says its 50ppm or less . my one is 30.4 ppm. Maybe later I might be temped to add an external
Reference  . mean time I just add the error in on the frequency setting and leave it .
I was very temped to go for the UTI ,s big version . which does have the ref in/out and it is far superior .
 But for my needs the UTG962 does every thing I want when I want  just peachy .
 The display input allows to add example 10.000,000,000,001 without any problem . but I have to add 30 ppm to the
value to make 100% perfect to my Leo  :-+
But on every day stuff the general hobbyist would never notice this small error .
For the faint hearted never check the OC in your PC . its Horrible.

Johnny I would like to see your video's if you could up them again  :-+

 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: DC1MC on October 15, 2020, 08:01:30 pm
Labrat101, regarding your 40Hz Gama Strobe, I have some very bright leftover LED bars used for LCD backlight and a couple of 10MHz TCXOs, what is the waveform for this generator, sine, rectangular or some special shape, I have an elderly relative that could benefit form it.
Also, is really the 40Hz frequency that critical, that +/- 0.5 produces adverse effects ? How do thse effects manifests and actually is there any visible, measurable improvement when is the right frequency ?

Many thanks,
DC1MC
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on October 15, 2020, 09:04:49 pm
Labrat101, regarding your 40Hz Gama Strobe, I have some very bright leftover LED bars used for LCD backlight and a couple of 10MHz TCXOs, what is the waveform for this generator, sine, rectangular or some special shape, I have an elderly relative that could benefit form it.
Also, is really the 40Hz frequency that critical, that +/- 0.5 produces adverse effects ? How do thse effects manifests and actually is there any visible, measurable improvement when is the right frequency ?

Many thanks,
DC1MC
BTW This should really be made into a new post ..

Don't use the leds that are too bright .. that is not the object .
 Be careful on the chose of leds they are not all equal and can cause eye damage.
as some have high uv output .
There are many documents on the subject from Professors & uni's
The wave form is cmos square and the pulse must be 50% on 50% off .
Don't use the leds from a TV they have a lenses 
i found the best were from the torch with about 40 flat plan leds are very good
 they should be as close as possible to day light.
 the frequency is critical if the person suffers from fits or other problems
 Do not try it.
You need to research it .. its not a try & see . Yes it does help
 If you read the other post I did mention the wave form also.
Yes the frequency can not be change after you start the treatment




Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on October 16, 2020, 12:42:49 am
@Labrat101

 I've had a similar complaint about these "zip" files being corrupted before. I did explain why I'd had to append a false extension onto the ends of these mkv H.264 movie clips and the need to rename them to delete the final ",zip" endings. or else use the "open as" option in the right click drop down menu to choose a suitable media player rather than let it default to whatever is the default application for dealing with actual .zip files which will get all confused and report that this .zip file must be corrupted because it fails to recognise the expected metadata.

 Just by way of a test, I downloaded the second file and tried to open it with the default application which in this Linux Mint system is "Ark", and it refused with a "corrupted archive" error message. If you're using windows, then I'd guess this is what you're seeing with whatever you use for opening such compressed archives (PKunzip? or similar).

 Microsoft has always been scammer/malware/virus friendly with its habit of hiding the vital clues revealed by the filename extensions by default (Aping Apple's "user friendly" reliance on metadata rather than filename extensions to decide how files are handled by default). I suspect the .mkv part of the .mkv.zip ending is being neatly suppressed, leaving you to suppose that removing the .zip extension will prevent the default mediaplayer application from opening these files.

 All of that microsoft nonsense is why I offered two ways to avoid the very trap you appear to have fallen into. Since it's now been 6 years or more since I last used the only good version of windows ever released by ms (win2K Sp5, aka NT5.0), I'm now a little unfamiliar with the list of filetypes windows doesn't hide from view (especially as I'd long since disabled all this nonsense with file names in their previous best version of windows, win95OSR2).

 The only reason, afaics, for this issue of "Korrupted Downloads"(tm) is due to the EEVBlog's filter on allowed file extensions necessitating the use of fake extensions and the nonsense that is windows habit of hiding the critical file name extension types like .com .exe .dll .bat .lnk .pif and so on (example: receiving an email attachment with the name of "naked lady.jpg.exe" which windows disguises by hiding the .exe extension yet, curiously, it still treats as an executable program file regardless of the consequences, leaving the hapless victim wondering where Hell his naked lady picture has disappeared to).

 If you follow my instruction on how to open these attached files (either remove the fake .zip extension from the filename (and don't worry about not seeing the mkv extension) before double clicking on them to let your default media file handler open them or else right click and select an appropriate mediaplayer - VLC is an excellent choice in this case), you will be able to watch these movie clips.

 BTW, if anyone else has any better suggestion on how best to get past EEVBlog's attachment filename filtering, feel free to chime in. :)

John

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on October 16, 2020, 10:44:34 am
   @ Johnny B Good

Ok . I removed the Zip part and they worked fine.
 If you had put TXT at the end it would have made it a little more obvious  :-+
I watched them OK compared to my FY68 with the fake chip I get a double sine one is stationery and the other slides over the top  :wtf: the square on my one is horrible over 5Mhz.
That square wave you have the sloping top & bottom is from the relay contacts put a very small cap 8pf or 10pf before the relay input will solve that .
 But I have locked it now for one purpose ONLY and @ 40hz cmos it is working fine . with only a small tweet.

 BTW Thanks . I also moved away from windows about 15 years ago .  Now on Mint 20  :-+ :-+
I have a laptop that I bought about 5 years ago that came with the shity 10 .
 which I only use for Multisim & Texas Tina-Ti.
and my wife's computer which is windows 7 as it has her game that she has played for nearly 8yrs  :palm:
 and with Dementia can't be changed . (still on level 1).

 Now with the Pulse strobe & VLF music  there is a slight improvement  :-+
 I have to keep an eye on the VLF pulse as it can make things move like Dr. Who's sonic screw driver.
  :popcorn:
  RNS

After an hour in the same room . So Relaxing  make U feel like your out of body
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on October 17, 2020, 12:13:42 am
   @ Johnny B Good

Ok . I removed the Zip part and they worked fine.
 If you had put TXT at the end it would have made it a little more obvious  :-+
I watched them OK compared to my FY68 with the fake chip I get a double sine one is stationery and the other slides over the top  :wtf: the square on my one is horrible over 5Mhz.
That square wave you have the sloping is from the relay contacts put a very small cap 8pf or 10pf before
the relay input will solve that .
 But I have locked it now for one purpose ONLY and @ 40hz cmos it is working fine . with only a small tweet.

 BTW Thanks . I also moved away from windows about 15 years ago .  Now on Mint 20  :-+ :-+
I have a laptop that I bought about 5 years ago that came with the shity 10 .
 which I only use for Multisim & Texas Tina-Ti.
and my wife's computer which is windows 7 as it has her game that she has played for nearly 8yrs  :palm:
 and with Dementia can't be changed . (still on level 1).

 Now with the Pulse strobe & VLF music  there is a slight improvement  :-+
 I have to keep an eye on the VLF pulse as it can make things move like Dr. Who's sonic screw driver.
  :popcorn:
  RNS

After an hour in the same room . So Relaxing  make U feel like your out of body

 I'm glad you solved the problem and that suggestion to use a fake .txt extension instead has been made before so, in view of the fact that it's a fake extension anyway, I'll take you up on that advice. I guess I was being just a little too conservative in sticking with the .zip idea out of the seeming logic that .zip files can contain any type of file or files - unfortunately, that's only valid when you actually take the trouble to encode them as real .zip container files. :palm: :palm: :palm:

 I've just been looking through my earlier attempts at attaching short video clips and I've just realised why I'd chosen to use .zip as a fake extension. My very first video clips had been actual zip files, requiring the recipient to unpack them into their original .mkv format. I then received a suggestion that I could simply append a fake extension to get past EEVBlog's file type filter, hence my sticking with the .zip as a fake extension, little realising that this would be more trouble than using something like .TXT :palm: From now on, it's .TXT all the way :)

 I don't envy your situation but no one can know what's ultimately in store for them and their loved ones. You just have to manage whatever comes along as best as you can since you have little choice in such matters. Whilst that AWG leaves a lot to be desired as a piece of test gear, it's good to see that you've managed to repurpose it rather than send it straight to landfill or clutter up cupboard space just gathering dust. BTW, it looks like you've found yourself a drugs free alternative to the narcotic experience. :)

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on October 17, 2020, 08:56:51 am
@ Johnny

All is good . I have been following an idea from a Nobel prize winner Pro.
 and I am working on the VLF - EMIC which was designed about 2 decade ago.
   Using 7.38Hz which was proven to work . The usage placement differs .
 I did think of opening a New post .. But I think that this field is outside the
 scope of this forum . & not for Novice .
 :popcorn:
 RNS  \$\Omega\$ 101
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: gameru on October 22, 2020, 01:38:40 pm
Good day
I want to buy a Function Arbitrary Waveform Signal Generator and i can't decide between FY 6900 and Fy 6200
Can someone tell me the diference between them?
Thank you
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 22, 2020, 01:54:40 pm
Hi when you set the internal osc frq offset for 10mhz in the secret system menu, how do I save it as the cal setting that I set is lost when I switch off then on
Thanks For any Help
Dave 2E0DMB
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on October 22, 2020, 01:59:20 pm
Hi when you set the internal osc frq offset for 10mhz in the secret system menu, how do I save it as the cal setting that I set is lost when I switch off then on
Thanks For any Help
Dave 2E0DMB
Long press on the OK button ..
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 22, 2020, 02:04:55 pm
Thanks for the fast reply,
Thanks Dave
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 22, 2020, 03:56:11 pm
Hi I have also done a mod to connect my gpsdo that is using a converted multi outlet 50ohm old video amp,
I cut the track going from the output of the tcxo and put a switch so I can select the gpsdo or the on board tcxo, the Problem I am having  is that when I am connected to my gpsdo and switch on off any of my mains test eqt the 6900 stops outputting a signal , I have tried adding caps and rf chokes / inductors, grounded  copper tape over the tcxo and the cpu, this did not help, changing input level to the 6900,
can anyone give me any other things to try ?
Thanks Dave 2E0DMB
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on October 22, 2020, 09:30:27 pm
Hi when you set the internal osc frq offset for 10mhz in the secret system menu, how do I save it as the cal setting that I set is lost when I switch off then on
Thanks For any Help
Dave 2E0DMB
Long press on the OK button ..

I am not familiar with this and after a little while trying to sort it out I could not find the "hidden service menu"... as I have a large offset from the FY6900 due to my upgrade of the stock crap XO with a 0.9 PPM TCXO, I'd like to zero the offset so that when I dial 10MHZ I do get it instead of 10.000235...
now I calibrated my counters to the GPSDO and it's quite obvious, it does not drift like it did before but  the offset is... off putting.
Labrat, could you elaborate more on it?
Cheers!
Franco
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 22, 2020, 09:45:39 pm
Hi you have to press the on button and the ch1 button at the same time when switching the power switch at the back , then once started press the system button then the more button
once you have adjusted it you use the ok button to save
yes the STD tcxo does drift a bit,
Let me know how yours goes, the STD one is of by 263hz at 10mhz,
Dave 2E0DMB
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on October 23, 2020, 01:03:51 pm
that is GREAT!
I now have my crappy FY6900 pulling out frequencies with an offset of 0.1 ppm, and with the upgraded TCXO i placed inside it doesn't even drift too much.... at least today, I'll leave it on for a couple days connected to my conter (with GPSDO external ref attached) and let's see how it fares.
But it's amazing how better that is, it always bugged me how the thing was always off by 230Hz!!!!

THANK YOU guys!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 23, 2020, 03:27:58 pm
that is GREAT!
I now have my crappy FY6900 pulling out frequencies with an offset of 0.1 ppm, and with the upgraded TCXO i placed inside it doesn't even drift too much.... at least today, I'll leave it on for a couple days connected to my conter (with GPSDO external ref attached) and let's see how it fares.
But it's amazing how better that is, it always bugged me how the thing was always off by 230Hz!!!!

THANK YOU guys!
Hi was the upgraded TCXO a swap in to the same place with no mods ?
Thanks Dave
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on October 23, 2020, 04:46:59 pm
Well I did a mot of mods actually, with the help of EEV members...

one was the drop-in replacement of the original crystal with a 0.9 PPM TCXO, this one:
VC-TCXO IQD LFTVXO009900BULK
suggested by MasterX81, it is somewhat expensive at about 14 Euro shipped, purchased thru ebay.
It can be replaced without any other mod, and it works, as I have basically no drift. However, as you imagine, I had a very noticeable offset...
also, if you read previous posts, it may "break" the Magic thingy that FY introduced to reduce jitter.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on October 23, 2020, 04:58:59 pm
So I actually am in search of a decent generator to replace the FY.
The  Siglent SDG 2042 is a prime candidate, however I do not have the money to purchase it new, and used are nowhere to be found, at least unless I find a good deal...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 23, 2020, 06:50:44 pm
Well I did a mot of mods actually, with the help of EEV members...

one was the drop-in replacement of the original crystal with a 0.9 PPM TCXO, this one:
VC-TCXO IQD LFTVXO009900BULK
suggested by MasterX81, it is somewhat expensive at about 14 Euro shipped, purchased thru ebay.
It can be replaced without any other mod, and it works, as I have basically no drift. However, as you imagine, I had a very noticeable offset...
also, if you read previous posts, it may "break" the Magic thingy that FY introduced to reduce jitter.
ok thanks for the info,
Dave
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 24, 2020, 11:38:17 am
Well I did a mot of mods actually, with the help of EEV members...

one was the drop-in replacement of the original crystal with a 0.9 PPM TCXO, this one:
VC-TCXO IQD LFTVXO009900BULK
suggested by MasterX81, it is somewhat expensive at about 14 Euro shipped, purchased thru ebay.
It can be replaced without any other mod, and it works, as I have basically no drift. However, as you imagine, I had a very noticeable offset...
also, if you read previous posts, it may "break" the Magic thingy that FY introduced to reduce jitter.
Hi pizzigri
How long does it take your 6900 to give a stable / no drift frq output with the new TCXO fitted ?
Thanks Dave
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on October 24, 2020, 07:38:11 pm
About half an hour or so. I added a fan to the housing and also used some Raspberry Pi heat sinks on the badly placed LDOs that are near the TCXO location.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on October 26, 2020, 08:28:43 pm
Hi I have also done a mod to connect my gpsdo that is using a converted multi outlet 50ohm old video amp,
I cut the track going from the output of the tcxo and put a switch so I can select the gpsdo or the on board tcxo, the Problem I am having  is that when I am connected to my gpsdo and switch on off any of my mains test eqt the 6900 stops outputting a signal , I have tried adding caps and rf chokes / inductors, grounded  copper tape over the tcxo and the cpu, this did not help, changing input level to the 6900,
can anyone give me any other things to try ?
Thanks Dave 2E0DMB

 That sounds just like the problem I used to have with my FY6600 over 18 months back whenever I connected it to any hard grounded DUT or my DSO. I cured it by upgrading the cheap 'n' nasty C8 figure of eight mains socket to a C6 cloverleaf (trefoil) socket as used with most laptop charging bricks - you can get the more flexible 6A mains leads for these. :) and wiring a 10KR between the PE tag and the BNC ground rail to kill off the 120Vac leakage from the Y cap which had been creating an ESD transient upon making contact to the DUT's grounded connection almost every time with sufficient energy to corrupt the FPGA's current processing task.

 Most times you could disable then enable the channel output or switch between menu items to get it to resume but sometimes you'd have switch off and back on again, thankful for the FY6600's mercifully brief 6 seconds boot up time.

 If you haven't already done so, try applying the 4k7R grounding mod (after making good Feeltech's gross vandalism on the ground return wire in the ribbon cable joining the psu to the main board). You'd think leaving Feeltech's grounding vandalism intact would prevent this but connecting to kit powered from a cheap wallwart such as a solderless breadboard could induce a similar ESD event as I found out when connecting to my not yet fully grounded GPSDO fed from an as not yet modified wallwart blessed with a real but unused brass earth pin. I could have simply run a ground wire to directly earth the GPSDO and any associated distribution cabling but you really want to avoid creating low impedance earth loops into any coax based distribution cabling scheme.

 In your case, it would seem what you've described is a crude but simple changeover switching arrangement between clock sources (the internal 10MHz TCXO and an external GPSDO reference) wired directly to this switch providing a direct injection path for any common mode interference to appear on the FPGA's clock input line via the GPSDO cable connection.

 If all your kit, including the GPSDO, has a hard connection to the mains protective earth, you've created an almost ideal demonstration of the problem, so familiar to Hi-Fi enthusiasts, of ground loops (or as they naively call them, "Hum Loops"). In our case there are far greater issues than mere mains hum and its harmonics to worry about as I believe you're only just now discovering.

 When I added an external 10MHz clock reference input socket to my FY6600, may main concern had been the several milliseconds break in clock supply to the FPGA during the switching action of a simple mechanical change over switch, hence my designing a complicated injection locking circuit that would automatically and gently lock the OCXO into phase with the external reference by simply plugging the external reference into the socket to avoid any such risk of disruption. Likewise, unplugging the external reference would gently release the OCXO back to its own devices, also without any disruption.

 I'd overlooked the bleedin' obvious of phase loop locking it via the EFC connection otherwise I would have implemented the changeover between internal and external clock sources using that method which would also have provided a similarly glitch free changeover characteristic but with a wider lock in range than the +/-10ppb I'd been aiming for. Either way, injection or phase locking to an external reference, provides considerable immunity to any interference from mains borne switching transients that might be induced into the lab's clock reference cabling.

 If you have used a simple mechanical changeover switch with no transient limiting protection between the raw external clock signal and the FPGA's delicate clock input, you run the real risk of permanent damage to the FPGA. This is one modification you have to be really careful of in its implementation even if it's just the use of a disposable 74HC14 with two or more of its inverters cascaded to act as a buffer between the GPSDO input socket and the changeover switch (not forgetting to use a resistor attenuator network between the 5 volt 74HC14's output and the 3.3v clock input pin of the FPGA).

HTH and HAND ;)

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 29, 2020, 10:36:56 pm
OK, so I have a question however I cannot seem to find an answer using the search engine....
So, I made a whole host of mods to the FY6900, but essentially apart from the PSU upgrade, ground, fan etc etc all described in this thread, the most important one was upgrading the reference crystal - I replaced it with a VC-TCXO IQD LFTVXO009900BULK with a 0.9ppm accuracy, and indeed the DDS works like a charm, as there’s no more drift. However, I noticed that there’s an offset, that at 10 MHz is about +170 hz, is there any way to calibrate the FY6900 and remove it? It is vary stable and does not drift (too much).
However, I do not yet have a GPSDO, that’s next on my list, so I am relying on the fact that both my counter (a Fluke PM6666) and my DSO 1202x-e roughly agree on this offset.

Eta pictures

 The short answer is "Yes, there is!" (or rather, there certainly is for the FY6600). However, if you use that hidden menu option, your 'magic'  (free of the 4ns jitter) frequencies at 50, 25, 12.5 MHz and so on, will no longer be jitter free. The best way to address this is to calibrate your VCTCXO to a reference traceable to an atomic standard - a GPSDO (or a RFS that's been recently calibrated within the past year or so :) against a traceable frequency standard (eg a GPSDO  >:D).

 I checked out that VCTCXO's datasheet which suggests there's every chance that your Fluke counter is overdue its next re-calibration (don't place too much trust in your DSO's frequency read out) since the tuning range is specified as being a minimum of +/-5ppm over a 2v tuning range centred on 1.85v (+/-50Hz for a 10MHz centre frequency). The actual tuning range could be as much as double that quoted minimum figure but more likely to be around the +/-7ppm mark.

 Assuming the EFC pin is at the 1.85V mark either by design or from a connection to an external trimpot across the 3.3v Vcc rail and ground, preset to its mid point for the time being until you can gain access to a trustworthy frequency reference by which to calibrate your VCTCXO as exactly as you can get it tuned to its specified 10MHz, it may already be within +/-1ppm of 10MHz to start with.

 IOW, there's every chance that it's closer to 10MHz than your DSO and frequency counter are implying. Wait until you have access to a GPSDO or RFS before attempting to recalibrate it, whether you use the software option or do it the right way with a trimpot wired to the EFC pin of that VCTCXO.  :)

John
Hi John
I am just changing my 10mhz ref for the VC-TCXO IQD LFTVXO009900,
what value pot would you suggest to use to do the adjustment,
 Thanks Dave 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 29, 2020, 11:03:28 pm
Hi I have just checked and the adjust track and the 3.3v are joined so that is why the frq is high using this tcxo I will have to cut the track ,
Thanks Dave
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on October 30, 2020, 10:19:24 am
Hi I have just checked and the adjust track and the 3.3v are joined so that is why the frq is high using this tcxo I will have to cut the track ,
Thanks Dave
Hi Dave
there is a 33 \$\Omega\$ from the out on the pcb near the the Fake cyclone . this maybe incorrect for your tcxo
 On one of my previous attempts to get this chip to respond correctly due bad track design I connected directly
to the cyclone pin direct . (Not recommended as the pins & tracks are pore. )
On my attempt I mounted a new resistor vertically and connected that to a short piece of RG3** then to a
TCXO . which was later scraped and used OCXO  20Mhz with a PLL & divider and then to the cyclone .
Due to the fact that the cyclone chip is NOT original the clock correction circuit malfunctions .
 

My FY6*** was scrapped as a AWG  and repurposed as a 40Hz med strobe .

You Might be wise to return the shity tcxo back as it does stay just within the scope rest of the
Bad design layout .   which they tried to correct with a software patch .. Magic Jitter  :-DD
Sorry . I hope I have not up set you .
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on October 30, 2020, 10:32:59 am
Yes. As a matter of fact, I have learned all I could from this thing. I spent now about 140 Euro, all included - FY6900 from Amazon, parts, TCXO, time. It works, even if in a crappy way. The FY did improve it a lot, thanks to all the EEVBlog members that helped me!
But, it's limitations are unavoidable, since the flawed Cyclone chip and convolved design.
That is the reason I just calibrated it via SW, and not built the breakout board I intended to... I dont want to spend any more time on it.

I can use it until I score a REAL AWG, but I am only a hobbyist.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 30, 2020, 09:36:40 pm
Hi Thanks for all of the info,
I have fitted the new TCXO and did cut the track between pins 1 and 4 ,and used a r/divider using a 47kohm coming from the 3.3v to a 500K ohm pot to the pin 1 voltage control pin of the tcxo, and now I can set it to 10.000000 and it is very stable without software frq offset adjustment (I just need to get a 10 turn pot)
Thanks Dave 2E0DMB
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 31, 2020, 02:20:42 am
OK, so I have a question however I cannot seem to find an answer using the search engine....
So, I made a whole host of mods to the FY6900, but essentially apart from the PSU upgrade, ground, fan etc etc all described in this thread, the most important one was upgrading the reference crystal - I replaced it with a VC-TCXO IQD LFTVXO009900BULK with a 0.9ppm accuracy, and indeed the DDS works like a charm, as there’s no more drift. However, I noticed that there’s an offset, that at 10 MHz is about +170 hz, is there any way to calibrate the FY6900 and remove it? It is vary stable and does not drift (too much).
However, I do not yet have a GPSDO, that’s next on my list, so I am relying on the fact that both my counter (a Fluke PM6666) and my DSO 1202x-e roughly agree on this offset.

Eta pictures

 The short answer is "Yes, there is!" (or rather, there certainly is for the FY6600). However, if you use that hidden menu option, your 'magic'  (free of the 4ns jitter) frequencies at 50, 25, 12.5 MHz and so on, will no longer be jitter free. The best way to address this is to calibrate your VCTCXO to a reference traceable to an atomic standard - a GPSDO (or a RFS that's been recently calibrated within the past year or so :) against a traceable frequency standard (eg a GPSDO  >:D).

 I checked out that VCTCXO's datasheet which suggests there's every chance that your Fluke counter is overdue its next re-calibration (don't place too much trust in your DSO's frequency read out) since the tuning range is specified as being a minimum of +/-5ppm over a 2v tuning range centred on 1.85v (+/-50Hz for a 10MHz centre frequency). The actual tuning range could be as much as double that quoted minimum figure but more likely to be around the +/-7ppm mark.

 Assuming the EFC pin is at the 1.85V mark either by design or from a connection to an external trimpot across the 3.3v Vcc rail and ground, preset to its mid point for the time being until you can gain access to a trustworthy frequency reference by which to calibrate your VCTCXO as exactly as you can get it tuned to its specified 10MHz, it may already be within +/-1ppm of 10MHz to start with.

 IOW, there's every chance that it's closer to 10MHz than your DSO and frequency counter are implying. Wait until you have access to a GPSDO or RFS before attempting to recalibrate it, whether you use the software option or do it the right way with a trimpot wired to the EFC pin of that VCTCXO.  :)

John
Hi The offset is due to the EFC/control pin 1 having 3.3v on it , you need to cut the track and supply with the correct voltage then it will set to the correct frq with no software offset
Dave
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on October 31, 2020, 02:38:12 am
Hi Thanks for all of the info,
I have fitted the new TCXO and did cut the track between pins 1 and 4 ,and used a r/divider using a 47kohm coming from the 3.3v to a 500ohm pot to the pin 1 voltage control pin of the tcxo, and now I can set it to 10.000000 and it is very stable without software frq offset adjustment (I just need to get a 10 turn pot)
Thanks Dave 2E0DMB

 IMHO, that's the only sensible method to calibrating the AWG. The secret software calibration option is for the "Rubes" who wouldn't know one end of a soldering iron from the other. >:D Not only will you know exactly how you stand with regard to those "Magical Frequencies" in these Feeltech AWG models, you've also left yourself a simple way to lock that TCXO to an external 10MHz frequency reference using a PLL circuit that allows a glitch free way to make an automatic changeover from internal to external clock sources and back again with no need for a gross mechanical switch alongside of the external reference input socket. >:D

 That circuit will work just fine in your case but most electrically tunable OC and TC XOs will typically arrange for the EFC to float at the mid voltage point with an input impedance somewhere between 68 and 100K which might require a control voltage lower than the mid point, hence the more usual potential divider arrangement of trimpot flanked with padding resistors at each end to limit the tuning range to a more useful 10 to 20% of the full EFC tuning range.

 A typical setup where the the EFC pin has to be pulled lower than its mid point might for example, consist of a 500 ohm multi-turn trimpot connected to gnd via a 2.2K with a 2.7K resistor connecting the other end to the Vcc rail with the wiper contact connected to the Hi-Z EFC pin which will normally be shunted to gnd with a 100 to 10000nF ceramic de-coupling cap to block any HF interference that might be floating around.

 The padding resistors ideally need to be selected so as to get the mid point setting of the trimpot as close to the currently required tuning voltage as possible to preset the XO to its designated frequency. A good idea would be to provide easy access to allow additional shunt resistors to be soldered across either of these padding resistors to allow compensation for ageing of the XO over the next few years of its operational life.

 A major issue with using trimpots as potentiometers in this way is that of variable resistance between the sliding contact and the track. The higher the impedance of the EFC pin, the lower this small but still significant voltage error you will see resulting from such contact resistance variation. The ultimate in Hi-Z 'zero' loading to reduce this effect to 'zero' is to use a suitable opamp as a simple voltage follower buffer (a cmos RRO opamp with low tempco DC offset being an obvious choice - the DC offset isn't a major issue as long as the tempco is nice and low) to drive the actual EFC pin.

 A 500 ohm trimpot flanked with 2.2ishK padding resistors will typically provide a low enough variation in slider contact resistance induced voltage error when connected to a 70 to 100K impedance EFC as to make the use of a Hi-Z input buffer amp of rather marginal benefit, especially in the case of a TCXO where the classic two resistor and a trimpot (with decoupling cap) arrangement is a more than ample solution.

 A potentiometer arrangement as above (with or without padding resistors) is the best choice of controlling or trimming a control voltage input when the input is a relatively high impedance since it minimises voltage variations induced by slider contact resistance variations, However, there are situations where using a trimpot simply as a variable resistor can be just as effective.

 I have a fine example of this situation in my MK II GPSDO where I've taken advantage of the ready made temperature controlled voltage reference built into the CQE 10MHz VCOCXO (as used in Symmetricom kit) that I'm using to create a stable set of DC offset voltages in 1 volt steps over the 0 to 4 volt range to allow me to monitor the EFC voltage in increments of 0.1mV using just a cheap Mestek "9999 counts" DMM that would otherwise only measure in 1mV steps when measuring the full 2.285V EFC directly.

 Currently, I'm measuring the difference between the 2v DC offset and the 2.2855v EFC voltage - I know the DC offset is a fixed unvarying two volts and the meter has auto-ranged to its 1000mV scale with a difference reading of 285.5mV which is all I really need to see. The accuracy of the two volt DC offset voltage is of secondary importance to that of its stability which is guaranteed in this case by a temperature stabilised voltage reference source second only to an expensive lab reference, courtesy of the one supplied by the OCXO's Vref pin.

 The Vref on these CQE OCXOs (I'd bagged myself a set of seven just over a year ago for just a fiver each) is a nominal 5v (typically around a 100mV or so higher) with an output impedance of just one ohm meaning that the string of five matched 1K resistors plus a 120 ohm padding resistor with its fixed 1mA drain causes a fixed 1mV drop on the original unloaded 5.128v Vref of my chosen OCXO example. This results by design in just over a +1mV error across each of the lowest three best matched resistors.

 I mention the phrase "by design" because I knew I'd have to have some way to trim this source of 1 volt DC offsets as close to exactly 1000mV each as I could achieve. With a 10Mohm input DMM measuring a voltage difference less than 1 volt, the worst case 1.2K impedance at each of these 1v taps on the fixed potentiometer could  only induce a vanishingly small error into my mV readings, leaving me only the small matter of how best to trim the the voltage at the top end of this potentiometer string to exactly 5,000mV (give or take a mV or two to trim out the slighlty less well matched 1K resistors at the top end of this string should a change of OCXO require a 3 or 4 volt DC offset).

 I'd chosen a 120 ohm padding resistor so that I'd only need to increase its ~120mV drop by just another 7mV using a variable resistor to draw the required additional 58uA or so. This corresponds to a shunt resistance value around the 86K mark across the 5K resistor string so I used a 50K pot with a 56 or 68 K resistor - the circuit was such a no-brainer, I didn't bother taking notes ::). In this case, the very low 58uA current through the wiper contact in what was virtually a constant current circuit seemed unlikely to cause any voltage stability issues (and subsequent voltage checks bear this out).

 I had suitable 5v cmos rro opamps to hand and a Vcc of 5.31v to allow the use of one to buffer a well padded out trimpot to completely eliminate the slider contact resistance issue but this seemed a rather unnecessary complication in this case where a 0.5% variation due to slider contact resistance would only result in a ~0.03% change in my DC offset voltages at worst (around a third of a millivolt per volt's worth of DC offset).

 Although the advice to use trimpots as lightly loaded potentiometers in preference to using them as variable resistors is generally sound, there are situations where using them this way can offer a simpler and more optimal solution with my own example above being a case in point.

 Your case, rather fortuitously, is not too far from the 'virtual constant current' situation of the above and, as ageing of the XO tends to reduce its resonant frequency, the EFC voltage adjustment trend with age is a rising one with virtually all EFC XOs, you can simply add a shunt resistor (typically half a M ohm or so in this case), if needed, across your chosen 47K padding resistor to compensate any ageing drift that might eventually take it beyond the trimpot's adjustment range over the next few years.

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: davebb on October 31, 2020, 04:36:58 am
Hi John
This is brilliant info Thanks
I have ordered a multi turn trim pot to replace the 40 year old carbon pot I bogged in for testing , this new tcxo is very stable with this old pot ,
I mainly use the awg on the sine wave setting,
Thanks Dave 2E0DMB
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Trader on October 31, 2020, 06:50:17 am
Price decreased USD $86.50

https://www.aliexpress.com/item/4000012709976.html (https://www.aliexpress.com/item/4000012709976.html)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on November 01, 2020, 10:51:13 pm
IMHO, that's the only sensible method to calibrating the AWG. The secret software calibration option is for the "Rubes" who wouldn't know one end of a soldering iron from the other. >:D

Ouch that hurt.... although I cannot deny being a "Rube" as you say since I am not a EE but just a newb hobbyist playing around. Audio, HAM Radio and electronics always fascinated me so if I have a little time to spare I study and try to learn. My specialization is product and industrial design, so I'm a bit more at home with SolidWorks than LTSPice - although my daytime job is in journalism.

However, the reason I'm demoralized is the fact that the FY6900 allegedly uses a counterfeit Cyclone IV chip. I believe you cant squeeze blood from a turnip, and there's a law of diminishing returns, over a certain point IMHO it makes little sense to try to improve the FY, the effort may not be worth it. This said, I also believe that I fu*ed up at the very beginning, after improving the PSU (thank you for your great help with that, BTW!), when I replaced the TXCO.... as has been said in this thread, that may have already broken the Magic Pulse s*it from FY and reintroduced the jitter. It did help immensely with the stability however.
So I'm not really sure if it makes sense forme to break open again the bugger and build all the described circuitry, unless there's a way to reinstate the sw patch for the 4ns jitter?
IE, "updating" the firmware from the PC software?
And, I got a used ooold HP33120A to play with, so I can compare and see how it goes. It was a decent deal on ebay, for much less that 200$ and I couldnt resist - if nothing else, to play with it.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 01, 2020, 11:42:04 pm
IMHO, that's the only sensible method to calibrating the AWG. The secret software calibration option is for the "Rubes" who wouldn't know one end of a soldering iron from the other. >:D

Ouch that hurt.... although I cannot deny being a "Rube" as you say since I am not a EE but just a newb hobbyist playing around. Audio, HAM Radio and electronics always fascinated me so if I have a little time to spare I study and try to learn. My specialization is product and industrial design, so I'm a bit more at home with SolidWorks than LTSPice - although my daytime job is in journalism.

However, the reason I'm demoralized is the fact that the FY6900 allegedly uses a counterfeit Cyclone IV chip. I believe you cant squeeze blood from a turnip, and there's a law of diminishing returns, over a certain point IMHO it makes little sense to try to improve the FY, the effort may not be worth it. This said, I also believe that I fu*ed up at the very beginning, after improving the PSU (thank you for your great help with that, BTW!), when I replaced the TXCO.... as has been said in this thread, that may have already broken the Magic Pulse s*it from FY and reintroduced the jitter. It did help immensely with the stability however.
So I'm not really sure if it makes sense forme to break open again the bugger and build all the described circuitry, unless there's a way to reinstate the sw patch for the 4ns jitter?
IE, "updating" the firmware from the PC software?
And, I got a used ooold HP33120A to play with, so I can compare and see how it goes. It was a decent deal on ebay, for much less that 200$ and I couldnt resist - if nothing else, to play with it.
just out of interest set the FY to 11Mhz square wave . with a 200mhz probe @ x10
 so you have about 3 cycles showing .
Set the persistent at 1ns do you get a double vertical on the rise and double fall .
 If yes zoom in and you will see its a complete over lay ie the first wave is lagging about 4ns
 behind the first ..   just curious .

HP33120A  Nice find
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: pizzigri on November 02, 2020, 08:13:36 am
This is what  I get....
did it this morning before goi g to work so I did not do any fancy stuff
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 02, 2020, 09:51:02 am
Ok Thanks ..
I just wanted to know if they had made any hardware changes ..
 They haven't . This is due to the Cyclone chip timing comparator . it should take
 if I remember correctly about  5 counts of clock cycles and ignore the errors.
  this was a hardwired in feature . To reduce jitter to less than 1ns .

  It seems that there early version ie Fy66  was made with better quality parts.
 and there profit markup was too low as the cyclone cost About $35 on its own .
 PCB & etc.etc screen panel ,Box . all for around $80 . is a close cut.

 Thanks it was just curiosity
 
 I move over to the UTG962 really very happy with it . I can not get it to reproduce a jitter
 or any other weird stuff that the FY6*** do .
 
 The Only mode required for the UTG962 is to dust it off once in awhile  :)
 
 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: battlecoder on November 02, 2020, 11:55:20 pm
I was actually playing with my FY-6600 yesterday and ran into the jitter issue.
So here's my 4 cents of jitter evidence:
[attachimg=1]

I really like all the features they managed to package in the device, especially considering its price. But it's exactly this kind of stuff what makes me want to get a better frequency generator. Inconsistencies and glitches can have you hunting problems that are not really in your circuit, but in your gear.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 03, 2020, 08:26:45 am
@ battlecoder

This might interest you this link.
Its a comparison of several AWG and the UTG962 & Tek & Rigol 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: FeelElec New Arrival FY-6900 Signal Generator
Post by: battlecoder on November 03, 2020, 04:28:10 pm
@ battlecoder

This might interest you this link.
Its a comparison of several AWG and the UTG962 & Tek & Rigol 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)
That's a pretty thorough comparison. Would have loved to see how the DG800 compared to the models tested, but this is already pretty good information to pick a device, thanks!
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on November 03, 2020, 05:36:01 pm
@battlecoder

 That 4ns jitter in the FY66/6800 AWGs is "by design". However, if you just need a fast pulse with low jitter for a stable triggering source, take a look at the Sinc pulse.

 Just like the sine waveform, it's free of this 4ns DAC clock jitter, leaving just the matter of some 300ps Pk-Pk of noise jitter (just over one third of what you see in the SDG1032X AWG ::)). This is good up to 12MHz (the Nyquist limit for this flavour of Sinc Pulse, 10 squiggles per cycle, being at 12.5MHz).

 You don't start seeing the 4ns clock jitter until you go beyond the Nyquist limit. At 20MHz, the 4ns jitter becomes very evident again but if you're after a low jitter pulse waveform around the 10MHz mark, this is your best choice. Not only do you get a low jitter pulse, you also get a very distinctive narrow pulse shape that distinguishes it from the more anonymous sine and square wave shapes making it easy to keep track of the direction of drift at mHz frequency offsets when you might only be glancing at the 'scope trace just once every few minutes. :)

 Of course, you'd only likely to be running such frequency comparisons after upgrading the internal clock reference to a 10MHz OCXO with a 3N502 clock multiplier to recreate the 50MHz clock feed to the FPGA chip. :) Incidentally, it's worth keeping in mind that this 4ns DAC clock jitter issue also afflicts massively more expensive DDS based AWGs - it's only the square and pulse waves that get the special low jitter treatment in Siglent's AWG models. Any awfms with a sharp transition suffer this DAC clock jitter effect (6.7ns in the case of the 150MHz clocked DAC in the SDG1000X series and 3.3ns in the case of the 300MHz clocked DAC used in the SDG2000X series to generate awfms),

 It came as rather a disappointment to discover that the SDG2000X's Sinc pulse with its 20 squiggles and 300MHz clock whilst looking perfect at its 10MHz 'magic frequency' (exactly 30 clock cycles' worth) turned to shit with just a tiny 1mHz offset. The Nyquist limit in this case being a mere 7.5MHz (and half that for the SDG1000X).

 This had only been of importance to me with the FY6600 due to it's excellent low jitter performance as a 10MHz reference signal for testing my DIY GPSDO projects against. It wasn't until rf-loop had given an excellent explanation for this apparent shortcoming of an AWG costing seven times what I'd paid for the FY6600 two years ago and the reliance on the Sinc pulse as an only source of low jitter timing pulse being rendered redundant now that I had a generator that could supply low jitter square and variable duty cycle pulse waveforms up to 25MHz for this task that stopped me from returning it as "Unfit for Purpose".

 Now you might think that's the end of the disappointments in the SDG versus the FY AWG comparisons but sadly no. It might surprise you to know that, aside from the crappy dimple operated front panel switches of the FY6600 model range, the FY series has a much more user friendly UI than that of the SDGs which can best be described as "User Hostile".

 I know, I know, who would have imagined that, aside from the obvious shortcomings of the FY AWGs, it had so many good features as to outclass the best efforts of Siglent (and naturally, Rigol) and much of the A brand offerings? Who knew? I didn't until I actually got my hands on first an SDG1032X, swiftly followed by the SDG2042X (now hacked to the 120MHz - sine wave only- specification) in my possession.

 Obviously, with the SDG2000X series, you get a 16 bit 1.2GSa/s generator (but only 300MSA/s for DDS generated awfms - not a lot better than the FY's 250MSa/s specification) along with a high quality all metal cased construction containing high quality components and a larger feature set (unfortunately cursed by what can only be described as a "Shit UI").

 You might wonder then, why I didn't reject this outright as "Unfit for Purpose" but the plain truth is that all of these shortcomings could be sorted by a 4 years long overdue (but quite do-able) firmware update to totally revamp the UI and fix all the other irritations such as polluting a perfectly good lab reference distribution with its rather lacklustre internal 10MHz clock reference whenever it's switched from the external clock back to the internal clock reference.

 Simply put, there's a missing user option to disable the "export the internal clock" part of this switching between internal and external clock references. The option to export its internal clock onto a distribution cable can still be useful when no existing lab reference is available to synchronise other test and measuring kit, hence my suggestion to allow the user to configure it to suit their circumstances rather than remove it completely from the clock source choice option.

 I had hoped I could retire my much modified FY6600 when I'd acquired the SDG2000X but this hasn't proved to be the case, admittedly largely due to all my modifications to improve its functionality. It still remains a very useful item of test gear in spite of the addition of the generally better Siglent AWG to my stock of T&M kit.

 The main annoyance I have with the FY6600's UI is that of the stiff front panel dimple operated pcb mounted switches of rather inconsistent quality making operation of some functions a rather hit and miss affair. I'd speculatively invested some £2.73 in a bag of 100 such switches from Bang Good almost a year ago in the hope I could use them to replace the existing switches and improve the situation but I still haven't gotten around to dismantling the front panel again to verify whether these switches can be used to replace the originals. Assuming the switches do prove to be suitable, there's still no guarantee of gaining a worthwhile improvement.

 Ideally, I'd upgrade to the rubber key operated panel switch arrangement as used on the later models but there's no cost effective way to achieve this, hence this rather more pragmatic approach to the problem. A significant factor could simply be due to the plastic dimples themselves which would limit the effectiveness of a switch upgrade. However, I'll be able to get a feel for this (literally!) once I've pulled the front panel apart. Basically, it's a journey into the unknown but, considering the potential payoff, it's a journey I think will be worth embarking upon... when I do eventually get a round tuit. :)

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: battlecoder on November 03, 2020, 07:03:37 pm
Of course, you'd only likely to be running such frequency comparisons after upgrading the internal clock reference to a 10MHz OCXO with a 3N502 clock multiplier to recreate the 50MHz clock feed to the FPGA chip. :) Incidentally, it's worth keeping in mind that this 4ns DAC clock jitter issue also afflicts massively more expensive DDS based AWGs - it's only the square and pulse waves that get the special low jitter treatment in Siglent's AWG models. Any awfms with a sharp transition suffer this DAC clock jitter effect (6.7ns in the case of the 150MHz clocked DAC in the SDG1000X series and 3.3ns in the case of the 300MHz clocked DAC used in the SDG2000X series to generate awfms),

Thanks for the detailed reply, John. As I'm a complete ignorant regarding the specifics of these devices, I have two questions for you, if you don't mind:
1.- In your opinion, s it worth upgrading from the FY-6600 to the FY-6900?
2.- If I were to replace the 50Mhz clock inside my FY-6600, what would work best: A 50Mhz OCXO? A 10Mhz OCXO with a clock multiplier? (Even more: Is it possible to use an external 10Mhz signal instead?)

Thanks
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on November 04, 2020, 02:22:51 pm
Of course, you'd only likely to be running such frequency comparisons after upgrading the internal clock reference to a 10MHz OCXO with a 3N502 clock multiplier to recreate the 50MHz clock feed to the FPGA chip. :) Incidentally, it's worth keeping in mind that this 4ns DAC clock jitter issue also afflicts massively more expensive DDS based AWGs - it's only the square and pulse waves that get the special low jitter treatment in Siglent's AWG models. Any awfms with a sharp transition suffer this DAC clock jitter effect (6.7ns in the case of the 150MHz clocked DAC in the SDG1000X series and 3.3ns in the case of the 300MHz clocked DAC used in the SDG2000X series to generate awfms),

Thanks for the detailed reply, John. As I'm a complete ignorant regarding the specifics of these devices, I have two questions for you, if you don't mind:
1.- In your opinion, s it worth upgrading from the FY-6600 to the FY-6900?
2.- If I were to replace the 50Mhz clock inside my FY-6600, what would work best: A 50Mhz OCXO? A 10Mhz OCXO with a clock multiplier? (Even more: Is it possible to use an external 10Mhz signal instead?)

Thanks

 Regarding question 1, I can't really say whether the FY6900 is a safe alternative in view of Labrat101's experience with the cheap FPGA clone in his FY6800 which may possibly have been more to do with his example simply suffering from a faulty clone chip rather than just that it was a cheap cloned FPGA.

 It occurs to me that Feeltech may well have been using cloned FPGAs from day one with the FY6600 rather than switching production over to a cheaper cloned chip option for the later FY68/6900 models. Until Labrat101 had discovered the use of a cloned FPGA in his FY6800, no one, as far as I know, had even questioned whether the FPGA was the real deal or not. Until someone examines the FPGA as closely as Labrat101 did in their FY6600 or FY6900 AWGs, we can only speculate over how far back the use of this 'cheap cloned FPGA' issue extends.

 Since nobody else has reported the issues Labrat101 had suffered and his discovery that the FY6800 had been cursed by the presence of a cloned FPGA (probably simply because nobody else had taken the trouble to "Look this particular Gift Horse so closely in its mouth"), it's quite possible that the FY6900 may prove to be no less reliable than its predecessors if Labrat101's findings had been simply the result of a faulty cloned FPGA.

 In other words, if we assume that Labrat101 had simply suffered the misfortune of getting a unit that happened to have a faulty cloned FPGA rather than the FPGA being a low quality clone, the FY6900 would seem to be the obvious choice to go for, since not only is it enhanced by the "Magic Pulse" feature to eliminate the 4ns clock jitter issue, it also provides an easy way to install a cooling fan and, like the 6800 models, improves on the front panel buttons used by the 6600.

 However, you're talking about upgrading from the 6600 to the 6900 rather than making a first time choice over which of these two models to purchase. Unless you're expecting to be able to sell your 6600 to partially finance the 6900 acquisition, you'd be doubling up your total expenditure for just a relatively modest upgrade.

 Since you already possess an FY6600, which I presume is working as good as its design limitations allow, it may be better to stick with it on the basis of "Better the Devil You Know" and put up with the stiff dimple operated front panel switches until you can afford to buy a significantly better AWG like an SDG1000X or SDG2000X for example.

 Regarding question 2, I think a 10MHz OCXO with multiplier chip would be a better alternative to a 50MHz OCXO unless you discover a really cheap source of 50MHz OCXOs on account of its non-standard frequency. The 10MHz OCXO is the safer bet despite the additional cost of a clock multiplier chip, since it has a much wider range of applications should the FY6600 let out all of its magic smoke, leaving you with a spare OCXO to add to your collection of salvaged components. Also of course, it can be used as a direct replacement for the 10MHz XO chip used in the FY6900 model.

 Regarding the addition of an external 10MHz reference socket, either frequency option (10 or 50MHz, including a 20MHz OCXO option) is amenable to being locked to such an external 10MHz clock source using a simple PLL circuit which will allow an automatic glitchless change-over between the internal and external reference clock options.

 Using a PLL (or in my case, injection locking) allows an automatic glitchless change-over between internal and external clock sources without any need for a separate mechanical change-over switch such as the one suggested by forum member "Arthur Dent" some two years ago in the FY6600 topic thread.

 When I designed my own injection locking circuit, I'd been so concerned about eliminating the risk of upsetting the FPGA from interruptions to its 50MHz clock feed via a simple change-over switch that I became rather fixated on the frequency injection locking technique, overlooking the more obvious PLL option (an OCXO with an EFC pin fed from a calibration trimpot that I'd forgotten could just as easily be driven by a PLL :palm:).

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 05, 2020, 07:07:51 pm
Hi Johnny . And All ..
Guess what someone just loaded up a photo of their new FY6900 .
 They Have renamed the cyclone to it's  Correct Name .
  Sorry if any one is  |O    But it looks like the Cat is out of the bag .
    The True colours just shine though .

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg3312048/#msg3312048 (https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg3312048/#msg3312048)

I just want to cut the lid off this puppy  ..
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on November 05, 2020, 10:20:48 pm
Labrat101, how to know when an FPGA is original or fake? :-//
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 06, 2020, 12:40:12 am
Labrat101, how to know when an FPGA is original or fake? :-//
Hi the first is the marking and the package. Looked good at first glance
The label should not wash off with a mixture of IPA  & Acetone. . ( use with care very strong solvent)
Some Clones have the wrong size pins . The Top Could have a flow over and lazer print
and only the texture is wrong . Example Intel has a small 'R' inside the O very small and hard to see .
 (Not on all versions change with year or batch.The newer versions has a different plate )
 
I work for Intel for 10yrs . The are a lot of documents on this chip. The main thing that this chip
has is a very low jitter of less than a ns . All intel chips are tested at die level before being enclosed.
 all bad or out of spec chips are destroyed . The cyclone 4 has a very good responses and also
 has , and can run @100Mhz as per the Spec sheet . It also has several inputs for different xtals .
 There are a few test pins that are not normally used . These when I tested were not connected.
 Also on my cyclone the label rubbed of with just plain 90% alcohol  :wtf:

There were other thing as well . FY68 did not respond to a better OCXO 2ppm . Made things worse
this when I realized that the fault was with the FPGA  was something else.
 And been chasing a rabbit down a hole. There is a mile of info that has been done on these units
 and yes we all missed the obvious .  |O .
  If you search the other 500 pages under several heading going back I believe nearly 3 yrs
I am sure some will correct me on that . Yes I have read every one .
 Some people seemed Happy with these Units so their must be a difference between
 the chip quality ( luck of the draw)
 
 In a nut shell it is very hard to spot some of the Fake chips now .
Some of the clones are very good and will work fine . At a lower spec or out of spec .
 
They assume the the average hobbyist won't notice . But when some one spends weeks building
 there new little project followed all the instructions starts running some test and all the scope
reading are nothing like  what they should be . They assume they wired it up wrong etc.
 Chances are it is Ok .  . Making a new Project for the Novice a heart breaker .
From all the feed back And what I have seen these units don't come close to CE standards.
 My AWG most of the ARB waves were so far off spec made them useless .
 ( FY   Now Replaced with a uni-t  99% within all Specs  @ $20 more)

  If it works and seems to be within your usage . Be Happy .
 But always double check if there is an error.
 you could be checking a good circuit and getting bad results .
Been there . spent 3 days looking for a fault that wasn't there .   |O |O |O

Edit update ..
If you want to know more about these FPGA . There is plenty of Info.
https://en.wikipedia.org/wiki/Field-programmable_gate_array
Also Just Google  FPGA
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Adrian_Arg. on November 06, 2020, 04:19:46 pm
Bad_Driver, the 5.6K resistor that you connected to the ground and that connects with the screw, is empty since the screw does not make ground with the plate, the screws are isolated from the ground of the plate and the source, what is its usefulness ??? I mean the green and yellow wire
(https://www.eevblog.com/forum/index.php?action=dlattach;topic=200307.0;attach=1001790;image)
in spanish
Bad_Driver, la resistencia de 5,6K que conectaste a la tierra y  que conecta con  en el tornillo, esta al vacio ya que el tornillo no hace masa con la placa, los tornillos estan aislado de la tierra de la placa y de la fuente, cual es su utilidad??? me refiero al cable verde y amarillo
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: battlecoder on November 08, 2020, 07:06:44 am
@John, again, thanks for your reply. I have a couple more comments/questions, if you don't mind.

Since you already possess an FY6600, which I presume is working as good as its design limitations allow, it may be better to stick with it on the basis of "Better the Devil You Know" and put up with the stiff dimple operated front panel switches until you can afford to buy a significantly better AWG like an SDG1000X or SDG2000X for example.
It's firmware 3.1 so considering all the people I've seen recommending to stay away from a v3.0 or 3.1 device...should I look into replacing the firmware?

Regarding question 2, I think a 10MHz OCXO with multiplier chip would be a better alternative to a 50MHz OCXO unless you discover a really cheap source of 50MHz OCXOs on account of its non-standard frequency. The 10MHz OCXO is the safer bet despite the additional cost of a clock multiplier chip, since it has a much wider range of applications should the FY6600 let out all of its magic smoke, leaving you with a spare OCXO to add to your collection of salvaged components. Also of course, it can be used as a direct replacement for the 10MHz XO chip used in the FY6900 model.

 Regarding the addition of an external 10MHz reference socket, either frequency option (10 or 50MHz, including a 20MHz OCXO option) is amenable to being locked to such an external 10MHz clock source using a simple PLL circuit which will allow an automatic glitchless change-over between the internal and external reference clock options.

I'm on the fence regarding the mods (because I actually intend to purchase a better instrument, so not sure if worth my time?), but considering I still think the FY6600 is NOT a bad frequency generator, and has a lot of really cool features and capabilities (I'm really impressed by the amount of modulation types that can actually accept an external signal), there's a chance I'll give the hacks a go. *IF* I do, I'll probably be using a 10Mhz OCXO plus the 5x multiplier as per your recommendation, with a PLL circuit to switch between internal and external source (Will need to do some research to design that, though. PLLs are unknown territory for me), and *maybe* a better supply (for some reason my supply doesn't measure the terrible leakage voltage ... or I've been measuring it wrong), but I feel inclined to increase the positive and negative 12V rails to something like 15V. I think I read somewhere that it helps with the awful distortion in 20V p-p sine waves. If that's not the case then I be damned, I would love to have better looking waves at those voltages.

Any other mod I should consider doing to it?

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 08, 2020, 11:50:36 am
@ battlecoder
I would not take the voltage up to 15+_ as the output ops are rated for 30v duel voltage MAX . Nom 28v.
 also take into account the working voltages of some of the caps .
I would not take the voltage above 12.5_+ . duel voltage 25v .
 I think JBG will agree . As we both have been to see Alice .  :)
 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: battlecoder on November 08, 2020, 05:28:59 pm
@ battlecoder
I would not take the voltage up to 15+_ as the output ops are rated for 30v duel voltage MAX . Nom 28v.
 also take into account the working voltages of some of the caps .
I would not take the voltage above 12.5_+ . duel voltage 25v .
 I think JBG will agree . As we both have been to see Alice .  :)

Thanks for the warning. Any way of reducing the sine wave distortion at the highest voltage setting then? Or that's completely unavoidable?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 08, 2020, 11:05:49 pm
@ battlecoder
I would not take the voltage up to 15+_ as the output ops are rated for 30v duel voltage MAX . Nom 28v.
 also take into account the working voltages of some of the caps .
I would not take the voltage above 12.5_+ . duel voltage 25v .
 I think JBG will agree . As we both have been to see Alice .  :)

Thanks for the warning. Any way of reducing the sine wave distortion at the highest voltage setting then? Or that's completely unavoidable?
I don't remember exactly what I did .
 The sine wave as I recall was ok ish upto 60Mhz . But I did change the ops and I put a
small ceramic cap 8pf on the input of the relay contact . as the relays on my one had a funny
contact impedance . which made the sine cleaner & the square look square.
 But the Jitter was like watching mountains during an earth quake .
The cap was on the op amp just after the dual filter there are 2 small pots ether side .
if you look there is a 49.9 \$\Omega\$ resistor that goes to the relay centre .
along that track is a ground plain just put a 10pf or smaller . between the track and ground.
 this might help you .
 I did load up some pictures on another section about 6 months ago . with some stuff
JBG was working on his injection locking . which did not work on my one . I did something
slightly different . but it did not solve the problem of the  :wtf: jitter .
 That's when I hit the bottom of the hole and had tea with Alice .
 And ordered the UTG 962 which just works great out the box .
 And wondering why I went as far as I did .
 It killed 9 months of Retirement boredom . Meet interesting folks on this forum .
 And Learned only one think how to waste time & money .
My  20Mhz 2ppb OCXO  + PLL was over $20 .
As I said earlier back I converted it to a Med Pulser 40hz cmos .
 I did use a proto type with a XR2206cp which actually goes to 1mhz and
No Jitter,   just 2 ceramic caps no xtal  it had a drift of about 0.02 hz an hr .
 & very clean cmos pulse . for a $1 chip. found in the scrap box .
 But for the med Pulse I needed more stable . now its ok..  40hz 10-7

UPDATE Circuit  Diag of the FY66
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: battlecoder on November 08, 2020, 11:50:40 pm
I don't remember exactly what I did .
 The sine wave as I recall was ok ish upto 60Mhz . But I did change the ops and I put a
small ceramic cap 8pf on the input of the relay contact . as the relays on my one had a funny
contact impedance . which made the sine cleaner & the square look square.
I have the 30Mhz version. Didn't feel like going higher than 30Mhz back then, but still, the biggest distortion the sine wave suffers is near max amplitude. Frequency doesn't change much of it from what I've seen.

The cap was on the op amp just after the dual filter there are 2 small pots ether side .
if you look there is a 49.9 \$\Omega\$ resistor that goes to the relay centre .
along that track is a ground plain just put a 10pf or smaller . between the track and ground.
 this might help you .
Will definitely try that, thanks.
And ordered the UTG 962 which just works great out the box .
I'm actually considering getting one. I just don't like the rather lacking options for modulation and external-supplied control signals.

And wondering why I went as far as I did .
 It killed 9 months of Retirement boredom . Meet interesting folks on this forum .
 And Learned only one think how to waste time & money .
Exactly my concern with the upgrades. That's why I want to keep the effort I put into modding it as low as possible. It already works reasonably well, so I'll probably just fix the frequency stability, and will probably add a fan (It already gets kinda warm. Putting an OCXO inside is only going to make it worse, so a fan is pretty much mandatory).
As I said earlier back I converted it to a Med Pulser 40hz cmos .
 I did use a proto type with a XR2206cp which actually goes to 1mhz and
No Jitter,   just 2 ceramic caps no xtal  it had a drift of about 0.02 hz an hr .
 & very clean cmos pulse . for a $1 chip. found in the scrap box .
 But for the med Pulse I needed more stable . now its ok..  40hz 10-7

UPDATE Circuit  Diag of the FY66
That's a pretty neat use for a frequency gen.
Also, thanks for the schematic! I'm sure it'll come in handy.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 10, 2020, 11:28:53 am
Hi!
What parameters did you use to check the jitter? Yesterday i've checked with my old owon 7102v, with 1mhz square, 50ohms termination on scope, enabled persistance, triggered some mv over negative part, i've moved the horizontal cursor for check the rising edge after the trigger rising edge and zoomed up to 2ns/div. I've measured less than 2ns of jitter. With lower frequency (khz region) got worst results, but i'm not sure if it's the scope or the measuring method.
Interesting the contact impedance of the relays, need to measure mine.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 10, 2020, 02:23:56 pm
Your Scope is just Fine .
 The only real important thing is to set your probe @ x10 .
 If set to x1 the probe is 6Mhz BW @ 1M \$\Omega\$.
This will be on the scope labels or enclosed docs that came with the probes .  also X10 will but less load on the DUT . 
 If you already knew this ignore the above .  :)
 Depending which AWG you are using and they added Magic jitter software which I have no idea if its meant to
stop jitter or just give an allusion or a BS gimmick .
But I guess 2ns is better than 4ns .  Less than 1ns good standards .
 
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 10, 2020, 02:36:14 pm
I'm using direct bnc to bnc rg58, with a T on the scope and 50ohm termination. The scope is set to 10x as i was too lazy to change the setting  :-DD
I not understand why at 1Mhz seem pretty stable, while at lower frequencies it goes almost everywhere. Maybe triggering at 50% of the edge will be better.
This evening i take few shots.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 10, 2020, 10:08:39 pm
RG316 50cm cable 50 \$\Omega\$ though termination.
Persistent set @ 1 Seconds both Channels
Display set to DOTs
Channel 1 yellow 11Mhz  Channel 2 Purple 19.23Mhz
Real time setting . Equal time would give a flatter top.
 jitter 200ps
PK scope (Siglent SGS1150 150Mhs)) 
Aglient 200Mhz (bottom Pic)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 10, 2020, 11:23:49 pm
In order:
1.000.000,000 hz
[attach=1]
1.000.000,001 hz
[attach=2]
10.000,000 hz
[attach=3]
10.000,001 hz
[attach=4]
100,000 hz
[attach=5]
100,001 hz
[attach=6]

Persistance is set to infinite, almost 30secs.
As this is a 200Msps device, any multiple of 5ns must be almost free of jitter. If i select 0.001hz more than the multiple, the fun begins.
But... why at 100hz i get a so bad result?
Note at 1.000.000,001 hz seem that what's changing is only the rise time. I not know how is possible.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 11, 2020, 08:30:27 am
@ masterx81
I ran those frequencies with the UTG962 with your setting could not replicate  .
 I think the problem is as I have said earlier .  Fake Cyclone and the software is
over compensating .
This is why I gave this unit up as a Dead duck in a cute Box.
 Its as good as a multimeter that can't measure volts .

edit my scope did not show frequency in image . 1.000,001hz
I can't figure out how your rise time is so slow ..
  its a 1 second pulse . on/off relay contact would show faster .
100hz is showing a double sinc . hardware error . FY fuzzy logic
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 11, 2020, 09:12:23 am
My tests are at the rising edge after the trigger point. You are showing the trigger point
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 11, 2020, 09:41:36 am
sorry . :palm:
I still could not replicate that .
I used your setting still could not replicate that @ 100hz
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 11, 2020, 10:40:43 am
The FY6900 have a 0.9ppm TCXO, maybe the clock source for the scope is higly unstable?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 11, 2020, 11:27:49 am
The FY6900 have a 0.9ppm TCXO, maybe the clock source for the scope is higly unstable?
I doubt that very much more like the cyclone is playing up .
Do a recal on the scope and reset but the scope is fine.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 11, 2020, 12:16:57 pm
Interesting that at 1Mhz is quite stable. I'll reset the scope, and try to scope the 50hz mains to see if it's more stable, and maybe the 1khz probe compensation output.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 11, 2020, 12:39:50 pm
Stop trying to finding things wrong with the scope .
 Its the FY69 that is faulty .. and it won't mater what you do . will not change that fact.
 All you will succeed in is messing up a perfectly good working scope .
 This was the same crap I was getting from my FY . Its full of Fake chips crap software .etc
 Its hard to except it .. sorry .. I had the same thing . same outputs ..
   This is why I don't use it any more. .
Sorry no hard feelings .
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on November 12, 2020, 03:18:17 am
 Try swapping the dots (periods/full stops) for commas and replace the comma with a decimal point (period/full stop). :)

 You've just fallen into the trap known as "Mathematic convention". Most, if not all, of Europe use a comma as the decimal point and the full stop (period) as the digit formatting separator.

 The first frequency shown is actually 1MHz. The key is in recognising the anomalies in the use of commas and full stops or periods. For Anglo-Americans the oddities are a comma followed by one or more full stops or periods or else a single comma preceded by one or more full stops or periods.

 Once you keep in mind the international nature of the EEVBlog membership and take a closer look at any numbers that don't look "quite right", it'll become obvious enough as to which convention has been applied.

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on November 12, 2020, 12:49:24 pm
Most, if not all, of Europe use a comma as the decimal point and the full stop (period) as the digit formatting separator.

Most of Europe is wrong then, :)  no wonder they all drive on the wrong side of the road as well. :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: nctnico on November 12, 2020, 01:47:05 pm
My tests are at the rising edge after the trigger point. You are showing the trigger point
Set the triggering to normal mode instead of auto. At low frequencies the auto trigger likely fires before the signal which results in drawing random traces.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: battlecoder on November 12, 2020, 02:50:45 pm
Most, if not all, of Europe use a comma as the decimal point and the full stop (period) as the digit formatting separator.

Most of Europe is wrong then, :)  no wonder they all drive on the wrong side of the road as well. :)
Not only Europe. We use comma as decimal in many countries here in South America. Definitely not a fan of that.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 12, 2020, 02:54:51 pm
Set the triggering to normal mode instead of auto. At low frequencies the auto trigger likely fires before the signal which results in drawing random traces.
I will try it, thanks!

And sorry for the decimal point thing, also here often cause problems...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: StillTrying on November 12, 2020, 11:41:02 pm
By my rough guestimate that X smudging is not too bad. The +Ve trigger point is 133,000  (133 thousand :)) screen widths away. Roughly +/- 1ppm of jitter shared between the FG's and scope's clocks.
- I think. :)

(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1106606;image)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TurboTom on November 13, 2020, 12:32:22 am
Just for comparison : This is what the same measurement looks like on a "liberated" DG811AWG.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 13, 2020, 06:03:28 am
Just for comparison : This is what the same measurement looks like on a "liberated" DG811AWG.

I am not sure now, so many images and bit poor explanations how they are exactly done.
But is it so that this previous Owon scope image about FY square, or was is pulse, is 100Hz, signal, period 10ms and in display next rising edge after trigger. So it is exactly what mean cycle to cycle jitter.

When do higher freq and then look over same time period 10ms situation is or is perhaps different depending... Now it least in some cases may affect lot of or nearly nonsense. It depends how square/rectangle  or pulse  is produced in system. Some times it can also see on data sheet where is jitter defined as just imagined example 100ps + 1% period.

So because it is somehow unknown how different generators produce sqr, rectangle and pulse, mu opinion is that it is best to use same square/rectangle period for compare.  Pulse is one special case when generator (most of) have separate pulse and rectangle mode.  Some simple generators may use even DDS arb procedure for produce pulses.
In history there was example one simply Siglent SDG1000 (no X)   where square/rectangle was internally produced using classic comparator method where square was derived from internal sine using fast comparator leading to quite good cycle to cycle jitter in high frequencies and then very extremely poor jitter in very low frequencies.  If example with this test over 10ms period using  tens of kHz or MHz range cycle cycle jitter is amazing low and if test with 100Hz it is nightmare and with 1Hz no need tell... yes it can read from data sheet, they did not lie. But how many understand it - well, I have seen some wondering after purchase when not even read or think what is told in data sheet.

Long to short... better to use same setup for compare.   Even if then can see difference is nonsense, but this can see only afterwards. ;)

FYI  one parcel is on the road...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 13, 2020, 08:56:26 am
As i've specified few posts before the screenshots, on the fy i've only selected square wave and changed frequency, default 5vpp and other settings.
The square is geerated  like every other waveform, through the DAC.
I'm pretty sure that the dac run always at the same 200Msps sampling frequency
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 13, 2020, 10:17:58 am
Just for comparison : This is what the same measurement looks like on a "liberated" DG811AWG.
Dictionary   lib·er·at·ed 
1) (of a person) showing freedom from social conventions or traditional ideas, especially with regard to sexual roles.
"the modern image of the independent, liberated woman"
2)(of a place or people) freed from imprisonment, slavery, or enemy occupation.
"liberated areas of the country"

All my tests were Done on a UTG962  . Un modded in any way.
 I don't think my UTG962 or my scope . come under this category . ( liberated )
  Mind you The UTG962 has a very slim Body and small foot print .   ;D
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TurboTom on November 13, 2020, 10:19:58 am
In case of the DG800, I checked all the available options: In both square and pulse mode, regardless of selected frequency, the slope observed after 10ms looks identical, as shown in the screenshot above. Since both references (AWG and Scope) were free-running (i.e. not locked to an external reference), I guess what's observed is rather the phase noise of the two internal references over 10ms vs. each other than the phase jitter of the generated waveform. The sampling clock aof 250MHz can be clearly observed when looking at arbitrary waveforms with steep edges.

Attached you see a "square" wave slope (1ns timebase) of slightly below 10MHz (to eliminate whole-number factor vs. sampling frequency effects), sampled over about one minute with infinite persitance. Trigger point is one period of the square wave to the left.

Once again, just for comparison...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 13, 2020, 02:57:23 pm
In case of the DG800, I checked all the available options: In both square and pulse mode, regardless of selected frequency, the slope observed after 10ms looks identical, as shown in the screenshot above. Since both references (AWG and Scope) were free-running (i.e. not locked to an external reference), I guess what's observed is rather the phase noise of the two internal references over 10ms vs. each other than the phase jitter of the generated waveform. The sampling clock aof 250MHz can be clearly observed when looking at arbitrary waveforms with steep edges.

Attached you see a "square" wave slope (1ns timebase) of slightly below 10MHz (to eliminate whole-number factor vs. sampling frequency effects), sampled over about one minute with infinite persitance. Trigger point is one period of the square wave to the left.

Once again, just for comparison...

In my previous msg I try carefully tell why it is better to use settings where things are so that we compare apples to apples.

This other user image (Owon scope) was 100Hz aka 10ms period, cycle to cycle jitter.

Now you show around 10MHz signal, previously around 1MHz. 

What I prevuiously told different frequencies different jitter.  Many times it is not not at all same to do it with 10MHz and after 10ms drelay or 100 Hz and there 10ms, and more better if avoid these golden frequencies and use some bit off like you just did with 10MHz.

Rigol DG900
Jitter (rms) 
Typical (1 Vpp)
≤5 MHz: 2 ppm of the period + 200 ps
>5 MHz: 200 ps

Same in Sig 1000X
Jitter (rms), Cycle to cycle
300 ps +
0.05 ppm of period


now 10ms period have 10 000 000 ns.

2ppm from it is 20ns.  This is why 100Hz can look extremely different.
And it is rms...  depending distribution peak value can not know without information about distribution. It is not always gaussian.

So how this 100Hz jitter looks like with DG800/900  compared to this @masterx81 test.

Arrgh...  I do not have scope now available...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TurboTom on November 13, 2020, 03:42:28 pm
@rf-loop --
of course, you are right. I attached a measurement with a square wave set to 99.999 280 Hz. The slope observed is one period after the triggering slope. I selected the amplitude to 12Vpp, high impedance but connected via a 50R BNC cable. The AWG input absorbs the reflected wave. If I set a higher amplitude on the AWG, rise time will be approximately doubled. It seems, the AWG firmware takes care of the finite slew rate of the output drivers in order to keep ringing and overshoot under control. No question, the FY6900 is capable of faster slopes and a (slightly) higher output amplitude (24Vpp vs. 20Vpp).

What's interesting to observe is that apparently the phase jitter of the output signal of the DG800 / 900 series only depends on the time delay between the trigger and the observed slope. It appears to perform way better than the spec, both the period-dependent figure as well as the absolute, "fast" figures.

Edit: As an additional observation, I added in the same screenshot a trace of the second channel, outputting a square wave of "arbitrary origin", i.e. without "controlled slope technology" (Rigol calls it "SiFi II"). The jitter originates from the 250MSa/s sampling frequency plus a little phase noise and what not. The rise time dropped from ~10ns to ~6ns, but overshoot and ringing are way worse. But even under these conditions, the jitter is still much better than spec.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: radiolistener on November 13, 2020, 11:22:06 pm
Just tried to test PSG9080 with 10 ms delay after trigger, but unfortunately my oscilloscope SDS1102X doesn't support trigger delay more than 10000 divs time, for 5 ns/div the maximum delay is 50 uS.

Here is my test for PSG9080, taken with 1 meter RG58 with 50 Ohm termination (to avoid cable dependency).
Screenshots taken with iinfinite persists and 1 minute accumulation.

1) Square wave 100 Hz with 10 ms trigger delay and 1 us/div (minimum time per div for 10 ms delay on my oscillsocope)

2) Square wave 9'999'280 Hz with 99.8 ns trigger delay and 2 ns/div

3) Square wave 10'000'000 Hz with 20 us trigger delay and 2 ns/div
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 14, 2020, 02:33:20 am
Just tried to test PSG9080 with 10 ms delay after trigger, but unfortunately my oscilloscope SDS1102X doesn't support trigger delay more than 10000 divs time, for 5 ns/div the maximum delay is 50 uS.

Here is my test for PSG9080, taken with 1 meter RG58 with 50 Ohm termination (to avoid cable dependency).
Screenshots taken with iinfinite persists and 1 minute accumulation.

1) Square wave 100 Hz with 10 ms trigger delay and 1 us/div (minimum time per div for 10 ms delay on my oscillsocope)

2) Square wave 9'999'280 Hz with 99.8 ns trigger delay and 2 ns/div

3) Square wave 10'000'000 Hz with 20 us trigger delay and 2 ns/div

Why you do not use 2nd time scale in 1st image. Or is it so that it do not work in this old X model.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 14, 2020, 03:19:51 am
@rf-loop --
of course, you are right. I attached a measurement with a square wave set to 99.999 280 Hz. The slope observed is one period after the triggering slope. I selected the amplitude to 12Vpp, high impedance but connected via a 50R BNC cable. The AWG input absorbs the reflected wave. If I set a higher amplitude on the AWG, rise time will be approximately doubled. It seems, the AWG firmware takes care of the finite slew rate of the output drivers in order to keep ringing and overshoot under control. No question, the FY6900 is capable of faster slopes and a (slightly) higher output amplitude (24Vpp vs. 20Vpp).

What's interesting to observe is that apparently the phase jitter of the output signal of the DG800 / 900 series only depends on the time delay between the trigger and the observed slope. It appears to perform way better than the spec, both the period-dependent figure as well as the absolute, "fast" figures.

Edit: As an additional observation, I added in the same screenshot a trace of the second channel, outputting a square wave of "arbitrary origin", i.e. without "controlled slope technology" (Rigol calls it "SiFi II"). The jitter originates from the 250MSa/s sampling frequency plus a little phase noise and what not. The rise time dropped from ~10ns to ~6ns, but overshoot and ringing are way worse. But even under these conditions, the jitter is still much better than spec.

Thanks. Perhaps this SiFi II  is something like Si have done long time ago... who knows.
So or so but in this single test looks like better than  data sheet worst case limits what perhaps are there but need find - if need.
I do not have here things for tests but here one old image about SDG1000X

Around in same ball park related to c-c jitter but in SQR  risetime small difference - naturally.

(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1108278;image)
Your image for compare
btw, how this freq is under 10MHz and delay is under 100ns and both are based to same clock
ETA: oh... and now I hit scope is also stopped...hmmh


(https://siglent.fi/data/SDG1000X/SDG1032X-square-cycle-cycle-jitter.png)
Old Si SDG1kX from some my old tests.

But then for every random readers. This is NOT for start any competition between these! Different things for different needs. All have some good and some bad things. What is best for one depends always hist personal needs and budget for hobby or work. Same for every piece of things. Kitchen machines, cars, test instruments and what ever, also clothes and food. There is not universal best and never come.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: radiolistener on November 14, 2020, 03:30:04 am
Why you do not use 2nd time scale in 1st image. Or is it so that it do not work in this old X model.

What is 2nd time scale? Do you mean sequence sampling?
I don't use it, because it works slower and it looks worse from my point of view and it's not clear for me how it's implemented :)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on November 14, 2020, 03:32:16 am
@radiolistener,

 You might have more luck with the 'scope's timebase zoom feature looking at this jitter. Just a thought.

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 14, 2020, 04:13:02 am
@radiolistener,

 You might have more luck with the 'scope's timebase zoom feature looking at this jitter. Just a thought.

John

Yes as I say previously, using second time scale and because there is not full screen runtime zoom it can use splitted window zoom where other window have different time scale (based to same timebase!)

Of course in first place I can use also timebase zoom but with some reason I did not (And I do not anymore remember also how this Old obsolete X model works exactly in this case) ... we need slowly learn thinking timescale instead of timebase. In analog scopes world we did timebase change and dual timebase zoom and dual time base dual trig and delayed zoom and what ever we like but mostly not in common digital scopes. These are different things.  Yes also I use still mostly term "timebase" but slowly I need learn away this thinking because it is not true. We do not even have delayed or trig after delay second timebase zoom... we have only second time scale display, splitted window or whole window "zoom" like old Owon did in history, dual time scale zoom in "feature" what was laughed by lot of peoples.
 ;D
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: radiolistener on November 14, 2020, 04:23:18 am
You might have more luck with the 'scope's timebase zoom feature looking at this jitter. Just a thought.

Hm... yes, you're right. In Zoom mode aka dual time scale SDS1102X allows to see 10 ms delay.
I never used Zoom feature before and thought it's complete useless. But in such case it helps :)

See picture in attachment for 10 ms delay.
PSG9080 generator, square wave 6 Vpp, 100 Hz.
The same 1 meter RG58 coax cable and 50 Ohm termination.
Infinite persist mode with 1 minute accumulation.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 14, 2020, 07:05:56 am
You might have more luck with the 'scope's timebase zoom feature looking at this jitter. Just a thought.

Hm... yes, you're right. In Zoom mode aka dual time scale SDS1102X allows to see 10 ms delay.
I never used Zoom feature before and thought it's complete useless. But in such case it helps :)

See picture in attachment for 10 ms delay.
PSG9080 generator, square wave 6 Vpp, 100 Hz.
The same 1 meter RG58 coax cable and 50 Ohm termination.
Infinite persist mode with 1 minute accumulation.

Excellent. Thanks.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TurboTom on November 14, 2020, 08:07:37 am
Hm... yes, you're right. In Zoom mode aka dual time scale SDS1102X allows to see 10 ms delay.
I never used Zoom feature before and thought it's complete useless. But in such case it helps :)

See picture in attachment for 10 ms delay.
PSG9080 generator, square wave 6 Vpp, 100 Hz.
The same 1 meter RG58 coax cable and 50 Ohm termination.
Infinite persist mode with 1 minute accumulation.

 :-+

One thing to keep in mind when when doing high-resolution (timing) measurements after long delays with non-synchronized timebases: You're always observing the correlation of all the phase noise / jitter of both timebases involved, the generator's and the scope's. In order to characterize a single instrument, you would need the "counterpart" to be known and proven at least an order of magnitude better than the one to be characterized. Which is rearely the case with these (mostly) entry level instruments, unfortunately...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: radiolistener on November 14, 2020, 09:35:58 am
for comparison, here is ROJON TCXO 96 MHz (https://www.aliexpress.com/item/32794136550.html) with the same trigger delay setting.

TCXO output pin connected directly to SMA connector with almost zero line length.
SMA connector is connected directly to oscilloscope through SMA-BNC adapter.
Power supply chain: KORAD KA3005D 5.00V => LM2931 3.3V (https://www.ti.com/lit/ds/symlink/lm2931-n.pdf) => tantal 100uF => ferrite bead => tantal 47uF => ceramic capacitors => TCXO


Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 14, 2020, 10:13:37 am
Hi Again ,
There seems that every one has put a lot of effort into this .
It would be more interesting if the results were taken from the actual output pins of the cyclone .
Ie the PSG9080 has a genuine cyclone chip . Were as the FY has a Clone Cyclone and on the new release
of the fy69 some one actually upload a photo of the chip . which has 'Feeltec Pro' stamped on it ..
 So there can't be any comparison between an Apple and a Lemon.
 If some one has Fy & another AWG with a genuine cyclone which to the spec's of the Cyclone does not have a Jitter problem
 due to it inbuilt patterned clock control circuit. The Clone version does not have this circuit .
 Also the Fy PCB has a layout mistakes that were not corrected and probably will never be done as the PCB would need a reprint.
which was corrected in many other models by other Makers . Of course this increased the cost .
 So All tests on other AWG's will never be able to duplicate this Error .
Therefore:. The 4ns Jitter will always be present on the clone version. over the full spectrum range .
 :popcorn:

   @ radiolistener
 That is a healthy drift that would be expected to be seen from a TCXO . shows the temp control is working
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: radiolistener on November 14, 2020, 11:03:57 am
Ie the PSG9080 has a genuine cyclone chip

PSG9080 uses Xilinx Spartan 6 XC6SLX9 instead of Altera Cyclone IV
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 14, 2020, 05:50:43 pm
Ie the PSG9080 has a genuine cyclone chip

PSG9080 uses Xilinx Spartan 6 XC6SLX9 instead of Altera Cyclone IV
:-+  Even Better   :-+  My Bad my error I meant to write genuine chip
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: battlecoder on November 14, 2020, 07:58:54 pm
Well you could all have done this fantastic analysis of the PSG9080 before 11.11.  >:(
What I'm going to do now with the Uni-T I purchased?  :-DD
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 14, 2020, 08:13:44 pm
Tried every trigger setting, but at 100hz and watching the rising edge 10ms after the trigger point the jitter is always the same. I've also doubt about the timebase of my scope, but by now i not have other ways to check it.
The psg9080 seem a quite promising device. I'm only a bit upset as i've spent a lot of time in this fy6900, and seem not so well spent 🤬
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on November 14, 2020, 08:25:47 pm
for comparison, here is ROJON TCXO 96 MHz (https://www.aliexpress.com/item/32794136550.html) with the same trigger delay setting.

TCXO output pin connected directly to SMA connector with almost zero line length.
SMA connector is connected directly to oscilloscope through SMA-BNC adapter.
Power supply chain: KORAD KA3005D 5.00V => LM2931 3.3V (https://www.ti.com/lit/ds/symlink/lm2931-n.pdf) => tantal 100uF => ferrite bead => tantal 47uF => ceramic capacitors => TCXO

 Since that TCXO looks exactly like the JYEC 50MHz unit fitted to a "Hi-Fi clock board" pictured here:-

https://www.aliexpress.com/item/32962398016.html?spm=a2g0o.detail.1000013.5.56363e63yTUr7u&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.169870.0&scm_id=1007.13339.169870.0&scm-url=1007.13339.169870.0&pvid=410d0e76-b02e-45aa-8020-b3a4f3048a97&_t=gps-id:pcDetailBottomMoreThisSeller,scm-url:1007.13339.169870.0,pvid:410d0e76-b02e-45aa-8020-b3a4f3048a97,tpp_buckets:668%230%23131923%2353_668%23808%234094%23330_668%23888%233325%234_668%234328%2319940%23905_668%232846%238112%23575_668%232717%237562%23480_668%231000022185%231000066059%230_668%233468%2315613%23482 (https://www.aliexpress.com/item/32962398016.html?spm=a2g0o.detail.1000013.5.56363e63yTUr7u&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.169870.0&scm_id=1007.13339.169870.0&scm-url=1007.13339.169870.0&pvid=410d0e76-b02e-45aa-8020-b3a4f3048a97&_t=gps-id:pcDetailBottomMoreThisSeller,scm-url:1007.13339.169870.0,pvid:410d0e76-b02e-45aa-8020-b3a4f3048a97,tpp_buckets:668%230%23131923%2353_668%23808%234094%23330_668%23888%233325%234_668%234328%2319940%23905_668%232846%238112%23575_668%232717%237562%23480_668%231000022185%231000066059%230_668%233468%2315613%23482)

 but purchased from an ebay seller two years ago for almost exactly the same price and being customisable to any end user's  frequency requirements and is at an even higher frequency of 96MHz, it's quite obviously a DDS type which is likely responsible for most of that jitter you can see. I suspect that if you select a less delayed zoomed segment to examine (say 1ms), the jitter will be reduced (possibly to just 10% of the 10ms delayed segment?).

 I'd bought the 50MHz TCXO clock module intending to salvage the JYEC oscillator to directly (using short wire stilts) replace the original 50MHz ten cent smd XO used on the FY6600's main board. Luckily, I discovered the blazing hot 55 to 60 degree C operating temperature of the smd XO in time to avoid taking the oscillator board apart and installed the whole module above the intake fan I'd installed into the base of the AWG to act as a deflector and stay within 2 deg of room temperature to avoid the rather wild temperature excursions it would have suffered If I'd gone ahead with my original plan. :phew:

 I recently tested that module (long since usurped by the current 10MHz OCXO upgrade with a 3N502 multiplier chip sat where the original smd XO chip had been) in order to quash the myth that the metal lidded smd 10MHz VCXO used in the SDG2000X series is a VCTCXO. It isn't - it's just a high quality VCXO allowing the user to re-calibrate it via the UI. The saving grace in this case being the presence of an external 10MHz reference socket. Unfortunately, that socket is bi-directional but I won't bore you with the details, suffice to say I hope Siglent will be interviewing job applicants for the position of chief UI developer sometime very soon. :rant:

 The biggest drawback with those TCXOs is the backlash in the trimmer adjustment. If that ROJON TXCO is anything like my JYEC one, it'll meet its 0.1ppm temperature stability spec with ease. :)  The backlash in the calibration trimmer makes achieving better than (a quite achievable) 25ppb accuracy a bit of a black art, involving as it does, skilful application of the trimming tool and a large dose of luck. It can be done, given enough patience and a stable calibration frequency reference source to adjust against but it's no easy task.

 I'm in the middle of quantifying the ionospheric induced timing errors in the GPSDO's output (some 4 to 6ns pk-pk phase modulations peaking around the 2 to 3mHz rate otherwise I would have set that 50MHz TCXO clock board up again to examine it using the zoomed timebase option (50ms or more delay) to see for myself (I'd only directly compared the exported internal 10MHz clock of the Siglent to my example of an actual TCXO so only saw  "jitter free" signals).

 I'll set that experiment up after I've finished my current test run with the GPSDO versus the sine wave output of the FY6600-60M locked to the RFS in order to let me dial in uHz offests to trim out the frequency drift between the GPSDO and the RFS, allowing me a more accurate view of these 4 to 6ns phase modulations imposed by the varying state of the ionosphere (the major source of timing errors with a single frequency GPS timing receiver such as the M8T I'm currently using - I can't really justify the 200 quid plus of a ZED9 right now :( ).

 Since the use of a cheap AWG is still on topic, I've attached a series of screenshots showing just how effective a tool these cheap AWGs (well my FY6600 at least) can be once the curse of the ten cent XO has been replaced by the blessing of an OCXO that can be locked to an external reference (the RFS in this case).

 The first five (note the date & time bottom RH) is a sequence started some 30 or 40 minutes after making a 40uHz adjustment to the FY6600 (representing the RFS, magenta trace). I'd noticed the frequency shift with the increase of room temperature from the central heating being turned on an hour earlier, corrected the offset and promptly forgot all about it. :palm: The last five were a similar sequence but I'd gotten distracted from making the initial screenshot some 42 minutes earlier by being called for tea. :palm:

 I'm triggering from CH2, the RFS since it's the GPSDO on CH1 that's doing the 4 to 6ns waltz. Also, it's worth bearing in mind the roughly half nanosecond's worth of jitter introduced by using the FY6600 as a frequency correction intermediary for the RFS (which will have some small amount of jitter of its own). I've been subtracting 0.5ns off the apparent pk-pk phase deviations to get a more accurate assessment.

 Incidentally, the SDG2000X series in spite of having an external clock reference socket, simply cannot be used for this type of measurement for lack of digits by which to set its output frequency (8 using the rotary encoder and digit cursor buttons or else 11 if using the keypad - 5 short of what you need for (the claimed) 1uHz resolution at or beyond 10MHz). :palm: :palm: :palm: Siglent have got a mountain to climb before they're even on a par with Feeltech's UI (which seems to have benefited from the absence of a keypad!). It seems, barring a catastrophic failure, that my much modded FY6600 has a lot more useful life left in it despite the acquisition of an SDG2042X ::)

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 15, 2020, 12:45:34 pm
FY6900-60

I have looked two individual units. Here better one. Other one initial freq off is well over 30ppm.
This one is "only" 22ppm after it have warmed up. Its xtal reference stability is quite poor.
In my position, at this time until I am back in my homeland, I  do not have nearly any test equipment.
Here is FY start up drift and after then some random drifting around in normal room without notable temp changes in test period.

Note that in image scale 100 is  10 000 000Hz  and measuring receiver freq accuracy is far better than 0.05ppm and drift/jitter performance for this purpose so good that I can say as rolls royce company... "enough".  So this is not even visible in this scale.

For my use these FY6900 toys are totally in class "utterly useless".  UI and design is "nightmare" like some just out from school kid engineer designed and made in some car garage floor.
Example just one single detail. AM modulation is something what looks that designers have not any idea for what they are in generator and then example modulation depth is totally out of order. Yes there is wrong math. And UI. How a hell they think it can use in practice for anything. Example if you adjust modulating freq, whole modulation need stop. Then you set new Mod freq (other channel is modulating) after then you start MOD function again.  If you do not use external modulation source ... well two channel generator can do just one channel AM out. So can not produce even two channel independent AM. And when try adjust MOD frequency whole mod drop off before it can adjust.
And then, when adjust modulation depth it change also carrier level. What a hell. If set 100% mod carrier drops 6dB related to 0% mod depth. (even this I can accept if it then stay fixed...but shit, it do not) and if set other mod% it also move carrier level.  Then if look example AM side bands levels... they are totally off. They did not know what are sideband levels related to carrier when modulation depth is x%. What they have done in school... if they have been there.
Right levels are

100% -6dB
50%   -12dB
10%   -20dB
2%    -40dB

And as can see in image they are off. And error is not small. I did not take under 2% mod levels because perhaps not so important and also used spectrum have not enough traces for one image.

Whole gen is total nightmare in UI and in HW for any serious purpose even if it have many dingle dongle "features".

(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1109818;image)
(FY6900-frequency-drift-after-start-and-out-of-specs-initial-offset-pub.png)

(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1109822;image)
(FY6900-random-frequency-drifting-in-normal-roughly-constant-room-temp-pub.png)

(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1109826;image)
(FY6900-AMmod-100-50-10-2-levels-pub.png)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: TurboTom on November 15, 2020, 04:20:22 pm
...
 
And then, when adjust modulation depth it change also carrier level. What a hell. If set 100% mod carrier drops 6dB related to 0% mod depth. (even this I can accept if it then stay fixed...but shit, it do not) and if set other mod% it also move carrier level.

...

This is something that you will find with (virtually) all AWGs. When applying AM, in the AWGs, the maximum Vpp level is kept constant, i.e.

Vout(t) = A * sin(w_carrier*t) * (1 + m/2 * (sin(w_mod*t) - 1)) -- assuming both sinusoidal carrier and modulation signals and modulation depth m =[0..1]

The maximum peak amplitude will be just A. And this approach makes good sense in case of an AWG. You simply don't want to "overdrive" the attached DUT and prevent it from possible damage by supplying a voltage level that's beyond your preset limit.

You simply cannot expect the characteristics of an RF signal generator from an AWG, it's a different instrument, made for different applications, though some AWGs are getting close ... both price-wise as well as frequency-wise.

With your other points, I completely agree.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on November 15, 2020, 04:35:25 pm
In my unit i have a 0.9ppm tcxo. So the jitter came elsewhere...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 15, 2020, 07:56:16 pm
Quote from: masterx81 on Today at 04:35:25 pm (https://www.eevblog.com/forum/index.php?topic=200307.msg3327174#msg3327174)
In my unit i have a 0.9ppm tcxo. So the jitter came elsewhere...

I guess you meant..  So the jitter comes from elsewhere...
Sorry But   Yes .
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 16, 2020, 08:31:32 am
...
 
And then, when adjust modulation depth it change also carrier level. What a hell. If set 100% mod carrier drops 6dB related to 0% mod depth. (even this I can accept if it then stay fixed...but shit, it do not) and if set other mod% it also move carrier level.

...

This is something that you will find with (virtually) all AWGs. When applying AM, in the AWGs, the maximum Vpp level is kept constant, i.e.

Vout(t) = A * sin(w_carrier*t) * (1 + m/2 * (sin(w_mod*t) - 1)) -- assuming both sinusoidal carrier and modulation signals and modulation depth m =[0..1]

The maximum peak amplitude will be just A. And this approach makes good sense in case of an AWG. You simply don't want to "overdrive" the attached DUT and prevent it from possible damage by supplying a voltage level that's beyond your preset limit.

You simply cannot expect the characteristics of an RF signal generator from an AWG, it's a different instrument, made for different applications, though some AWGs are getting close ... both price-wise as well as frequency-wise.

With your other points, I completely agree.

Yes for AWG I can accept also this principle that keep modulated total (sidebands and carrier sum) for peak level.
I know many AWG works like this.  Exept Siglent after they finally change it in some previous FW update.


But.

In FY6900 situation is total mess with this moving carrier level + same time wrong modulation %.
They move carrier when AM% change, it can see idea is perhaps just this "keep peak" principle. If it do ALONE this it can accept - just like example in Rigol DG800/900 or some  Siglent models. Not so nice but still acceptable and in some other kind of use just ok.

But then in FY6900 sidebands level related to true current carrier level is totally out of order. If user do not have things for measure modulation depth, using this % setting he get wrong true %.

When I look example DG800 sidebands level related to carrier (dBc) is - perfect.   Just tested DG using 0dBm out and AM from 100% down to  0.06%   sidebands -70dBc  and below this my measurement can not say sure due to noise (because I need use 50dB attenuator between generator and test system) but perhaps even under 0.06% still quite ok . With this DG800, it is easy to correct carrier level if it need keep in some specified level with higher modulation %. If need correct carrier level it is simple just correct level. And all adjustments can do without interrupting modulated signal (except some very tiny glitches)
It follow math just perfectly.

But with FY need some  table where can find what AM% give wanted AM%. If I need this... I feel it is better to throw it out from window before total burn out with it and do things with lot of better tool without even enormous price difference.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 18, 2020, 12:10:43 pm
FY6900-60

I have looked two individual units. Here better one. Other one initial freq off is well over 30ppm.
This one is "only" 22ppm after it have warmed up. Its xtal reference stability is quite poor.
In my position, at this time until I am back in my homeland, I  do not have nearly any test equipment.
Here is FY start up drift and after then some random drifting around in normal room without notable temp changes in test period.

Note that in image scale 100 is  10 000 000Hz  and measuring receiver freq accuracy is far better than 0.05ppm and drift/jitter performance for this purpose so good that I can say as rolls royce company... "enough".  So this is not even visible in this scale.

For my use these FY6900 toys are totally in class "utterly useless".  UI and design is "nightmare" like some just out from school kid engineer designed and made in some car garage floor.
Example just one single detail. AM modulation is something what looks that designers have not any idea for what they are in generator and then example modulation depth is totally out of order. Yes there is wrong math. And UI. How a hell they think it can use in practice for anything. Example if you adjust modulating freq, whole modulation need stop. Then you set new Mod freq (other channel is modulating) after then you start MOD function again.  If you do not use external modulation source ... well two channel generator can do just one channel AM out. So can not produce even two channel independent AM. And when try adjust MOD frequency whole mod drop off before it can adjust.
And then, when adjust modulation depth it change also carrier level. What a hell. If set 100% mod carrier drops 6dB related to 0% mod depth. (even this I can accept if it then stay fixed...but shit, it do not) and if set other mod% it also move carrier level.  Then if look example AM side bands levels... they are totally off. They did not know what are sideband levels related to carrier when modulation depth is x%. What they have done in school... if they have been there.
Right levels are

100% -6dB
50%   -12dB
10%   -20dB
2%    -40dB

And as can see in image they are off. And error is not small. I did not take under 2% mod levels because perhaps not so important and also used spectrum have not enough traces for one image.

Whole gen is total nightmare in UI and in HW for any serious purpose even if it have many dingle dongle "features".

(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1109818;image)
(FY6900-frequency-drift-after-start-and-out-of-specs-initial-offset-pub.png)

(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1109822;image)
(FY6900-random-frequency-drifting-in-normal-roughly-constant-room-temp-pub.png)

(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1109826;image)
(FY6900-AMmod-100-50-10-2-levels-pub.png)

After this FY6900 I look other generator. (DG800 "DG992")


I looked bit about its internal reference stability. Drift after startup and after it have roughly temperature equilibrium in room in its place. Place was also exactly same where FY6900 was when tested. Same stability in room temp etc.

DG is really and totally like from different universe.
Due to its reference much higher stability I use different scale. When small div was 0.1ppm in FY test, now in this test small div is 0.01ppm. (and test freq 100MHz) There is also other difference.The frequency offset scale is inverted so that trace go right it mean frequency move down and vice versa. Just opposite with FY test.

Then other thing. AM modulation.
As told I do not like when carrier levvel change depending AM modulation depth. Of course this problem is not meaningful with low modulation depths. But with higher modulation % it change more and need note. Finally with 100% modulation carrier drop of course 6dB. But in this generator sideband levels related to carrier true level are all ok. Need say - perfect. 
If you have 0dBm out and turn AM mod on and 100% just turn output level 6dB up then it is 0dBm. If use lower % look what is needed level correction if need keep carrier level. Mostly <10% do not need correction in practice.
Most important (least for me) is that AM modulation depth is correct and and also other modulations, here DG is very good and FY is just terrible.
Down to 0.02% AM mod what I can now here measure, it is  very accurate.
Internal reference is totally from different universe if compare to this FY6900.





(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1113666;image)

DG drift from startup. 1h20m follow up.
NOTE SCALE. It is 10x magnified related to FY6900 test image!!!



(https://www.eevblog.com/forum/testgear/re-feelelec-new-arrival-fy-6900-signal-generator/?action=dlattach;attach=1113670;image)

DG800/900  AM modulation % accuracy. Better than good, it is perfect.
ETA: Some explanation about image. Modulation depths 0.02% 0.2% and 2% (blue, yellow, orange) are all done with same carrier frequency 7.1MHz.
There carrier level change is so small amount that this spectrum display resolution is not enough for shoe difference.
20% mod, carrier tuned bit lower freq, red trace. As can see carrier is bit dropped for keep sum level same. Finally 100% mod again bit lower freq just for better visible carrier level.


Sidenote. If someone wonder this base noise level...
Signal level in generator output is 0dBm.
Between instrument is 50dB attenuator and then display have same 50dB level offset. .With this arrangement used "measuring" receiver level accuracy-linearity is better.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on November 18, 2020, 10:23:15 pm
Just out of curiosity could you run the same tests on the UNI-T UTG962 60Mhz . just a passing thought if you have the time .
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on November 19, 2020, 02:19:31 am
Just out of curiosity could you run the same tests on the UNI-T UTG962 60Mhz . just a passing thought if you have the time .

Of course. Just give one to me.
 :-DD
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on December 14, 2020, 10:33:56 pm
In order:
1.000.000,000 hz
[attach=1]
1.000.000,001 hz
[attach=2]
10.000,000 hz
[attach=3]
10.000,001 hz
[attach=4]
100,000 hz
[attach=5]
100,001 hz
[attach=6]

Persistance is set to infinite, almost 30secs.
As this is a 200Msps device, any multiple of 5ns must be almost free of jitter. If i select 0.001hz more than the multiple, the fun begins.
But... why at 100hz i get a so bad result?
Note at 1.000.000,001 hz seem that what's changing is only the rise time. I not know how is possible.
Little correction. I've bought a siglent 1104x-e, and with this the measurement at 100hz have around 7/8ns of jitter (infinite persistance over near 2 min). Well lower than the 30ns measured by the owon. Almost same jitter at 100.001hz, while with the owon was all over the places. Not optimal, but less worse than what the owon was showing.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: radiolistener on December 15, 2020, 01:55:09 pm
Little correction. I've bought a siglent 1104x-e, and with this the measurement at 100hz have around 7/8ns of jitter (infinite persistance over near 2 min). Well lower than the 30ns measured by the owon. Almost same jitter at 100.001hz, while with the owon was all over the places. Not optimal, but less worse than what the owon was showing.

could you please explain exact condition when you see the jitter.
Do you use 10 ms trigger delay? Can you see it with no trigger delay?

Oscilloscope oscillator also has a jitter, so if you use long trigger delay the source of jitter is unknown, because it may be related to oscilloscope jitter. Isn't it?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on December 16, 2020, 10:06:01 am

could you please explain exact condition when you see the jitter.
Do you use 10 ms trigger delay? Can you see it with no trigger delay?

Oscilloscope oscillator also has a jitter, so if you use long trigger delay the source of jitter is unknown, because it may be related to oscilloscope jitter. Isn't it?

I see the jitter using 100hz frequency, delay 10ms, trigger auto (but also normal), ac coupling, 5vpp signal, square wave dc 50%, trigger voltage 0v (played also with other trigger setting without doing any better). With the owon the jitter was really bad, obviously the time reference of that scope was not so good as the siglent one. I will try other 100hz signal sources for exclude that the jitter came from the scope (but now with a "decent one" i doubt it)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on December 16, 2020, 11:45:00 am

could you please explain exact condition when you see the jitter.
Do you use 10 ms trigger delay? Can you see it with no trigger delay?

Oscilloscope oscillator also has a jitter, so if you use long trigger delay the source of jitter is unknown, because it may be related to oscilloscope jitter. Isn't it?

I see the jitter using 100hz frequency, delay 10ms, trigger auto (but also normal), ac coupling, 5vpp signal, square wave dc 50%, trigger voltage 0v (played also with other trigger setting without doing any better). With the owon the jitter was really bad, obviously the time reference of that scope was not so good as the siglent one. I will try other 100hz signal sources for exclude that the jitter came from the scope (but now with a "decent one" i doubt it)

For this purpose (check oscilloscope own jitter) you do not need 100Hz signal. What ever signal what itself have very low jitter is ok for this purpose. Example good quality 10MHz high quality oscillator. Frequency itself is not at all important here. If you find good 1 - 50MHz OCXO it is well enough after it is stabilized. Of course for this purpose is better if it have rectangle output instead of sine so it eliminate bit more possible signal noise produced trig jitter. Trig jitter itself in SDS1kX-E is specified under 100ps. But time jitter over 10ms is not directly specified and I do not have here available my older tests where I have measured these models time jitter using highly more than enough stable signal. Of course oscilloscopes are also individuals. Every single reference oscillator is bit different.  Jitter is not big but better I do not say numbers because I can remember wrong.
Totally other thing is accuracy and long term ageing drift and these can read in specs as max limits and then temperature drift.

But one I can say. This thread topic generator FY6900 internal reference is totally crap shit. And yes, I KNOW it, I have two for teardown and look.  This kind of generator can use only for playing fun as it is also overall utterly useless piece of shit, but again, can use for playing fun. In this generator all is wrong except price... oh well also it is high if look its quality. One car garage floor assembled and soldered dirty PCB card and shit PSU in pastic box without any kind olf EMI rejection and what is like kids designed and if look safety rules it can not even legally import to EU area. All connectors also most crap shit what ever can find any place.
Example DS811 modded to DS992 price is bit over FY6900 but designed and manufactured professionally.

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: masterx81 on December 16, 2020, 11:54:54 am
Sorry, but i'm not sure that the frequency isn't important. On the owon the measured jitter at 1mhz was not observable, while at 100hz was really worse than what the 1104x-e is measuring. I suppose that if the scope run always at 1ghz sampling rate, at 100hz there are more probability to observe jitter as we are measuring a lot more samples than at higher frequencies.

Yes, it's quite crap... But the rigol (one that i was also considering) costs almost 1.5times this unit (100e vs 250e). Only for doing some waveforms without RF work, can be useful... Now i've attached it also to the blode plot of the siglent...
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: puterboy on December 30, 2020, 12:17:32 am
The first solution was to have a PC act as a function generator simulating a Siglent function generator then translating those commands to an FY function generator through a serial port. The second version used a precursor to the ESP 32 the ESP8266 to act as a Siglent function generator on a LAN using Wi-Fi. I took the Wi-Fi code and modified it to use esp32 and added support for using DB units.

https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-and-sds1204x-e-bode-plot-with-non-siglent-awg/ (https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-and-sds1204x-e-bode-plot-with-non-siglent-awg/)

I have read through the above thread several times but it was unclear to me what you need to do to get the ESP32 to work and loaded.
Can you point me to some more detailed "how-to" instructions?

Thanks
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: puterboy on December 30, 2020, 01:07:36 am

 By "cash strapped hobbyist", I mean someone with at least the basic skills to wire a 4.7K resistor between the PE tag of the C14 socket and a convenient connection point on the ground rail of the main board, along with the ability to at least undo the vandalism to the ground return wire in the 6 wire ribbon cable between the PSU and main circuit board and fit a 40mm square 12v fan into the unpopulated fan aperture in the rear panel and connect it to the 5v rail to quietly reduce the internal temperature to less insanely high levels. >:D

 There, I've just pointed out the three cheapest and highest priority (most essential) modifications that any "cash strapped hobbyist" should do to protect their modest investment. ::) There's no need to thank me for this sage advice (a simple click on the "Say thanks" button will more than suffice if you insist). >:D

JBG

Are there two separate "mods" to the grounding?
Several posts and videos I have seen, seem to suggest just a single (combined) mod of replacing the existing thin ribbon cable wire between C14 PE and the connector on the power supply board with a 1-10K resistor in series with a heavier gauge wire.

Are you instead suggesting two separate grounding wires to the C14 PE -- one new wire run with a series resistor going to the main board ground and the other a heavier gauge wire (without a resistor) replacing the old ribbon wire to the PS connector?
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: puterboy on December 30, 2020, 01:21:34 am
On my photo you will see i put a 10pf cap on the opamp output after the filter .
This is to correct the contact capacity of the relay . which makes the square wave much sharper . but it does not cure the jitter/ghost .


On my 6900, the square wave starts degrading into a distorted sinusoidal-like wave above about 12MHz.
Does just adding a simple 10pf cap solve much of the problem and preserve a good sine wave up until the claimed 25MHz per the specs?
Can I do just this change without any of the other more complicated mods that you and others have talked about?

If so, where do I put the cap?
Also, can I use a garden variety chinese ceramic or do I need a special/high quality one?

Thanks
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: puterboy on December 30, 2020, 01:33:12 am
Hi Thanks for all of the info,
I have fitted the new TCXO and did cut the track between pins 1 and 4 ,and used a r/divider using a 47kohm coming from the 3.3v to a 500ohm pot to the pin 1 voltage control pin of the tcxo, and now I can set it to 10.000000 and it is very stable without software frq offset adjustment (I just need to get a 10 turn pot)
Thanks Dave 2E0DMB

 IMHO, that's the only sensible method to calibrating the AWG. The secret software calibration option is for the "Rubes" who wouldn't know one end of a soldering iron from the other. >:D Not only will you know exactly how you stand with regard to those "Magical Frequencies" in these Feeltech AWG models, you've also left yourself a simple way to lock that TCXO to an external 10MHz frequency reference using a PLL circuit that allows a glitch free way to make an automatic changeover from internal to external clock sources and back again with no need for a gross mechanical switch alongside of the external reference input socket. >:D

So does using the "hidden service mode" permanently delete/break the "Magical Frequencies" patch or is it undoable?
I would like to play with the software calibration (even if it makes me a Rube) but not at the expense of permanently breaking the stock software.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: radiolistener on December 30, 2020, 01:34:44 am
On my 6900, the square wave starts degrading into a distorted sinusoidal-like wave above about 12MHz.

Most of all, this is not 6900 degrade, but your oscilloscope bandwidth limitation or inproper connection (you're needs to use 50 Ohm coax cable with terminator for square wave testing)
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: puterboy on December 30, 2020, 01:46:17 am
On my 6900, the square wave starts degrading into a distorted sinusoidal-like wave above about 12MHz.

Most of all, this is not 6900 degrade, but your oscilloscope bandwidth limitation or inproper connection (you're needs to use 50 Ohm coax cable with terminator for square wave testing)

I am using a Siglent 1104X-E modeed to 200MHz.
I am using the direct male-to-male coax connector supplied with the FY6900 to connect the signal generator to my scope. Do I need to use a different compensated cable instead? If so, what type of cable should I purchase?
Thanks
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: precaud on December 30, 2020, 02:43:44 am
He (radiolistener) is saying, the cable needs to be terminated in 50 Ohms at the scope.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: radiolistener on December 30, 2020, 03:00:31 am
I am using a Siglent 1104X-E modeed to 200MHz.

200 MHz is too small to see nice square wave above 10 MHz. If you want to see good 20-50 MHz square wave, you're needs at least 300-500 MHz bandwidth oscilloscope. You're reach limit of your scope bandwidth when you put square wave above 10 MHz, and this is why it turns into sine...

Do I need to use a different compensated cable instead?

you're needs to use 50 Ohm terminator at the scope input side in order to get proper cable match.
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: rf-loop on December 30, 2020, 06:31:02 am
I am using a Siglent 1104X-E modeed to 200MHz.

200 MHz is too small to see nice square wave above 10 MHz. If you want to see good 20-50 MHz square wave, you're needs at least 300-500 MHz bandwidth oscilloscope. You're reach limit of your scope bandwidth when you put square wave above 10 MHz, and this is why it turns into sine...



From FY6900 do not come out this nice square. SDS1204X-E is well enough for look and characterize FY6900 output square.

Define "nice" square what you are talking. Do you mean these square waves what exist only in students book images.
Square wave risetime is this key factor. If there is not more than 5ns risetime available SDS1204X-E is well enough even measure this risetime with medium accuracy. Group risetime can calculate SQR((trise1^2) + (trise2^2))  then you can compare it to original trise1. If original was 5ns it may give 6% error in risetime.

But if we think what really looks like square on screen and we are looking only whole one period on screen then example 10MHz square is well ok if we have 200MHz scope, 20 times 1st harmonic.

Now if we go with FY6900 to higher levels than up to 5Vpp displayed value what is 2,5V in 50 ohm line. With over 5Vpp in 50ohm line its risetime is roughly 12ns, because FY6900 end amplifier is in totally crap junk class. And with  10Vpp over 50ohm load even rest of "flat" tops disappear, what ever scope you take and look. Because this end stage just can not do it at all. User can adjust it up to 24Vpp... with 50ohm load  it means 12Vpp ... no need to tell but just "game over" totally.
ETA: Up to 5Vpp FY display value, 2,5Vpp to 50ohm load, situation is different and risetime is specified 7ns or less in data sheet. And in my tests this is less. Something like 5ns +/-<1ns. Even with this, SDS1204X-E is well enough.

It do not matter if you look this signal with 100MHz scope ot 1GHz scope. Even 50MHz scope do not lie so much when risetime is 12ns. Because its own risetime is nominally 7ns. 12ns+7ns group risetime is 13,9ns.  So if you look it with 50MHz scope you see 14ns risetime and if you look it with 1GHz scope you are very close 12ns now think how much it affect in visual image if you have whole period on screen and you change from 50MHz BW to 1GHz BW...
Just for simplest basics...

Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Johnny B Good on December 30, 2020, 04:24:34 pm
It just had to be stated. Thank you very much for stepping into the breach on this one, rf-loop.  :)

John
Title: Re: FeelElec New Arrival FY-6900 Signal Generator
Post by: Labrat101 on December 30, 2020, 05:44:11 pm
It just had to be stated. Thank you very much for stepping into the breach on this one, rf-loop.  :)

John
But will they listen! . And learn . some how I dough it . 
   Beautify said  rf-loop   :-+