FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator

[Gandalf_Sr]

If the 74HC245DW runs on 3.3 volts then there is a drop in replacement in the LVC version which is about twice as fast. See the chart below which is taken from Ti's CMOS logic guide.  AUP would be faster but it's not available in the same package (as far as my limited search went).

[DaveR]

I installed the THS3095 opamps in mine today and re-ran the high range tests as per the attached file.  The results are self evident, and the improvements above 10MHz are very clearly seen.  What isn't seen is that, having viewed the improved waveforms, I was definitely more critical as regards distortion etc this time around, so the real improvement isn't just in the output levels but in the overall quality of the outputs as well.  I also noted that throughout the tests the factory heatsink on the opamps barely got warm, so it's probably grossly oversized already or not needed at all.

I ran the tests this time at +/- 13.5v (I don't want to push any dodgy 16v caps too hard), but at Insatman's request I also checked the 40 - 60MhHz results at +/- 12.0v and there was little or no difference in the results, so it appears that the 3095s are quite happy at the original PS voltages, and I rather doubt there'd be any changes if I upped the supply voltage to 15v.  If you need the higher outputs, then changing the opamps appears to be a "just DO it" mod.

Next task (for fun) is the TCXO change to see how much it stabilises the 40 - 60MHz outputs.

[spec123]

Re: THS3095

Please help me out.. Digi-Key shows two versions of THS3095, namely the THS3095D and THS3095DDA. The latter one has a power pad but otherwise looks similar. Can the power pad be a problem here? Which one would be best? Which one are you using?

[cybermaus]

I wonder if these are genuine?
https://www.ebay.com/itm/292350281588

Oh well, I'll find out soon enough, as I ordered some.
I figure they are not re-used, as they are in the reel cutoffs still.

Please help me out.. Digi-Key shows two versions of THS3095, namely the THS3095D and THS3095DDA. The latter one has a power pad but otherwise looks similar. Can the power pad be a problem here? Which one would be best? Which one are you using?

I had the same doubt. I guess it could be a problem if the powerpad is shorting out traces below, but I figure that can be solved with a strategically placed piece of kapton tape.
But yes, people already using 3095, please say which one.

[DaveR]

I bought the plain version without the power pad.  The power pad version is for specially designed boards which have thermal conductivity built in directly under the chip, so that they don't need a passive cooler on the top.  It may or may not work without a problem on the FY6600, but there's no point in buying it to find out that it doesn't

[DaveR]

I wonder if these are genuine?

At that price I'd say they will be genuine Chinese imitations of the real thing!

[spec123]

Re: THS3095

Rough calculation indicates that THS3095 may dissipate up to 0.5W or more when operating with 50 ohm load. IMHO this requires good heat sink.  Looking at Vals post #167 and photos, it appears that three chips will now need to connect to the heat sink. Are all three chips at the same height?  Yes, heat sink compound must be used, but don't want big gap between devices and heat sink.  Does anyone see a problem here? Use individual heat sinks?

Related question: Was a low power soldering iron used or is hot air tool required to install the devices?

[DaveR]

Well, the calcs are one thing, but my finger tip says there's no heat output worth worrying about - and I was running them under a 50 ohm load for several hours last night.  However, all three chips now under the heatsink make good contact with it and there's no rocking at all, so there's little need for any compound to be used (there wasn't any on mine to start with).  If you're still concerned about heat dissipation, I'd use some pieces of adhesive thermal pad rather than paste, which will just make a big mess as you put the heat sink back on.  The pads will also take up any height discrepancies which may exist when you've finished.  Individual heat sinks will need to be very small themselves to fit next to each other, and they'll probably be less efficient than what's already there.  (I only mentioned the heatsink because I recall some recent post talking about putting an even bigger cooler on them - something which is definitely not necessary.)

I used a hot air gun to remove the THS3002 and a very fine cranked tip on my soldering iron at 260degC to install the 3095s.  The pads on the board are already tinned so you should be able to use a hot air tool to fix them - if you can hold them down in the right places while you wave the gun around over them.  I just prefer to use the soldering iron so that I can see exactly what's happening on each pin and know that the joint is good.  You'll need a good magnifier or loupe for the job as well, unless you've got the eyes of a hawk.

[DaveR]

Another observation after the 3095s mod is that you can now get half decent output up to at least 100MHz using the two or three cycle sine wave trick.  However, attenuation of the output continues to increase with frequency - you don't get higher output amplitudes despite starting from a lower base frequency in the control software.

[norms]

Ok, new to this forum. I have a few questions about this 60Mhz Generator which I was not able to find on the net. I would be grateful if someone can answer these queries before I buy one.

1. I need a fm signal at 10mhz with a 1khz modulation, would this unit be able to do that. The manual mentions a vco max of 1khz, but then says vco frequency should be below 500hz.   

2. what is the maximum frequency that can be used for the carrier frequency.

3. The firmware version 3.2 is mentioned as the best one to get, I see screen shots show version 2.6. Was 2.6 an earlier sold version or is this references some other version and not the firmware

[canyon]

Gang,

It's been quite some time since I checked in here. I have a FY6600 v3.0 that got scrambled the third time I used it. Is there any remedy, reflash or fix available. Or, is it just a plastic case for a new project?

ken
wa4mnt@gmail.com

[DaveR]

Hi norms,

In answer to your questions, the FY6600 can do a 60Mhz carrier modulated internally at up to 100kHz (tested) and externally at up to 2kHz (according to the latest manual).  Firmware version 3.2 or 3.2.1 is the one which should be supplied if you buy one now, and it appears to be stable.  Earlier versions 3.0 and 3.1 had serious problems, but those should be well out of circulation by now.  I think any version prior to 3.0 probably refers to an earlier model or one of the cheaper, lower maximum frequency versions which can be bought.

[DaveR]

It's been quite some time since I checked in here. I have a FY6600 v3.0 that got scrambled the third time I used it. Is there any remedy, reflash or fix available. Or, is it just a plastic case for a new project?

Hi Ken,

At the moment it's still just a plastic case, but work is well under way on a project which may yet see it able to be revived in one form or another.  Have a read of the last few pages to get a feel for what's going on, and keep your fingers crossed

[DaveR]

I installed the D75J TCXO chip last night, and my frequency error went down from -4.65ppm to 0.45ppm, and after warm up and calibration it was down to 0.02ppm and rock steady - a pretty good result, although it was almost "a mod too far".

For anyone else contemplating replacing the existing clock chip with the D75J, please take my advice NOT to try to solder it directly to the board after the old chip has been removed, as the pads on the new chip are tiny, completely hidden from view, and only just coincide with the edges of the existing solder pads, so getting the chip positioned exactly right is a matter of pure chance.  I think luck must have been with Insatman when he did it, but I wasted over two hours struggling to get the connections made before giving up.  Instead, just cut three pieces of fine wire about 8mm long (34 gauge worked very well) and solder them to pads 4,5, and 8+9 on the chip, then bend them into legs and feet so as to give about 3mm clearance from the board.  Soldering the feet to the board then becomes a simple matter because you can now see precisely what you are doing.  After the abuse it took I'm surprised the chip still worked in the end, but if it packs up now I know I can replace it without fuss in a matter of minutes!

I think that's all the hardware modding done now, except for painting the box red and putting go-faster stripes down the sides, but that can wait

[soundtec]

Thats a pretty good result Dave ,a ten fold reduction in drift or more.

I have the 3095's here too but I havent soldered them in yet ,is there something about lifting one leg for the powerdown feature ?
Are there already low value output mixing resistors so the two halves of these op amps run correctly?
Are there any other adjustments needed to fix the gain of the stage ?
Might solder in these op amps in the next few days.
I wonder if theres much improvement in THD% with the new op amps in place ,the original spec on the Fy6600 is 0dbm and .8%THD, be nice if that figure comes down a bit .

[DaveR]

Hi soundtec,

Yes, I'm very pleased with the final result - 60Mhz sine waves with no more than a little amplitude modulation now, otherwise a perfect waveform.

For the 3095s, just solder them in as they are: they'll work fine.  No need for anything else except to remove the existing 3002.  It looks as if Feeltech may have been planning for a future higher spec version and made provision for dual amps on the board - which is very fortuitous for us as they make a big difference.  I would imagine the THD does come down, but I've got no means of verifying or quantifying it. 

Happy modding!

[Candid]

For anyone else contemplating replacing the existing clock chip with the D75J, please take my advice NOT to try to solder it directly to the board ..

Can you please make some pictures of your work. I would really appreciate this!

And do you have pictures of the replacement of the THS3095 too (before / after)?
Replacing them is just removing the old ones and replacing with the THS3095 at the same location?

I think I saw already a picture here but cannot find it and slowly I am getting nearer and nearer to make both of this modifcations too  after I already made the most important linear psu thing. So I need to complete my local information.

EDIT:
Found the infos for the OP-Amps https://github.com/DerKammi/FY6600-15-30-50-60M

[DaveR]

Sorry,  Candid, I didn't take any photos, but you can see Vytautas' before and after pics of his THS3095 changeover here:  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/

As for the D75J, just read my description in conjunction with what you see when the old clock chip is removed - it will be obvious what needs to be done when you look at the four solder pads on the board and compare them with those on the chip (using the datasheet to identify them).  Basically you are just adding three short table legs to the chip to make it ten times easier to fit onto the board.  You won't be connecting anything to the solder pad next to C1 on the board, and the legs are connected to the other three pads matching each corner of the chip.  For the correct orientation of the chip, see Insatman's photo here:  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/800/

Regards,
Dave

[cybermaus]

Sorry,  Candid, I didn't take any photos, but you can see Vytautas' before and after pics of his THS3095 changeover here:  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/150/

As for the D75J, just read my description in conjunction with what you see when the old clock chip is removed - it will be obvious what needs to be done when you look at the four solder pads on the board and compare them with those on the chip (using the datasheet to identify them).  Basically you are just adding three short table legs to the chip to make it ten times easier to fit onto the board.  You won't be connecting anything to the solder pad next to C1 on the board, and the legs are connected to the other three pads matching each corner of the chip.  For the correct orientation of the chip, see Insatman's photo here:  https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/800/

You know, it is actually possible to link to specific message inside a page rather the the top of the page.
That is a little easier for people to know which one you meant.

Like these:

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1348087/#msg1348087

https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1434962/#msg1434962

Just rightclick on the specific message and do "copy link address"

[Candid]

Thank you for your help. I ordered from digikey because no chance to get the TCXO in germany directly. Even the german distributor does not have in stock and cannot name any supplier in germany. So in the end I paid 52 EUR for the TCXO and the THs including tax and postage. But I started with the linear psu and cannot stop on half the way now with the FeelTech experiment

[Insatman]

I installed the D75J TCXO chip last night, and my frequency error went down from -4.65ppm to 0.45ppm, and after warm up and calibration it was down to 0.02ppm and rock steady - a pretty good result, although it was almost "a mod too far".

For anyone else contemplating replacing the existing clock chip with the D75J, please take my advice NOT to try to solder it directly to the board after the old chip has been removed, as the pads on the new chip are tiny, completely hidden from view, and only just coincide with the edges of the existing solder pads, so getting the chip positioned exactly right is a matter of pure chance.  I think luck must have been with Insatman when he did it, but I wasted over two hours struggling to get the connections made before giving up.  Instead, just cut three pieces of fine wire about 8mm long (34 gauge worked very well) and solder them to pads 4,5, and 8+9 on the chip, then bend them into legs and feet so as to give about 3mm clearance from the board.  Soldering the feet to the board then becomes a simple matter because you can now see precisely what you are doing.  After the abuse it took I'm surprised the chip still worked in the end, but if it packs up now I know I can replace it without fuss in a matter of minutes!

I think that's all the hardware modding done now, except for painting the box red and putting go-faster stripes down the sides, but that can wait

I did have a bit of trouble soldering the D75J, but not as much as you did I guess.   After my first attempt the ground lead was open so I simply heated up the corner of the PCB pad and shoved more solder in.  That worked the trick as Aussie Dave would say.   The D75J ended up a bit crooked in my eariler posted pic but I was not about to unsolder it to fix that.   I probably should have said a bit more about installation in my earlier posts.  I think your method is probably better.   I got similar results on the frequency stability/accuracy.   Now to install those THS3095 ICs that arrived yesterday.

[rhb]

Umm...

You guys do realize that what you're doing is quite insane don't you?    I think it's pretty cool, but on an objective level it's more than a little daft.  It's like building  a 200 HP air cooled VW.  You *can* do it, but it really doesn't make sense.

I just want mine to work!

Proud owner of a V 3.1,
Reg

[DaveR]

Umm...

I think it's pretty cool, but on an objective level it's more than a little daft.

Since when has objectivity taken precedence over having fun??  We mod because we can!

[DaveR]

Just rightclick on the specific message and do "copy link address"

Thanks for the pointer, cybermaus - I've done it correctly before, but when the wife's dressed up ready to go shopping and standing behind you, sighing impatiently, it's hard to remember the simple things!

It's actually right-click on the message title and select "copy link location" in my version of Firefox, but I think it's now burned into the memory banks!

[DaveR]

After my first attempt the ground lead was open so I simply heated up the corner of the PCB pad and shoved more solder in. 

It was probably your chip being crooked that helped, and you accidentally found the only position where it would work!  I tried shoving more solder in on all three corners but, being the perverse stuff that molten solder is, it just refused to find one of the pads on the chip, even though I'd tinned them first.  The chip was rigid, so I knew I had two corners fixed, but I couldn't tell which two they were.  Still, the end result was well worth the trouble!!

You'll have no problems with the 3095s .