I just want mine to work!
Assuming you don't fry your FY6600 making the modifications, you will have a FG/ARB SG that compares in many features to some of the higher priced ARB/SGs from Rigol, Hantek and Tek.
What I did though is I made a custom waveform, 0 to max, for VCO input to sweep, and a small -max pulse at the beginning to trigger the scope. And I fed that into the VCO in the back. So no need for a square wave.
If you are doing this at higher freuqencies, the pulse at the beginning may need to be more than just one sample, because we may have 8192 samples, but above 30KHz not all samples make it to the signal (250MHz sample rate / 8192 samples)
How to one-shot it though? not sure, I guess that would be a feature request to fremen67.
But why not simply repeat your bode plot?
Paulca, expanding on the suggestion of Cybermaus, you can get a triggered sweep for your scope by feeding a low frequency negative ramp from CH2 to the VCO terminal in back. Make sure your ramp goes from 5V to 0 V, using offset and amplitude adjustments. Set your start and stop frequencies, then use"Forth" in Sweep selection to get a forward frequency plot. Your scope can be triggered directly from the positive edge of the ramp using a second scope channel or ext trigger.
While this does work, it is cumbersome and fraught with possible errors. For more serious work with frequency response plots I suggest you get a low cost scalar network analyzer. There are plenty of low cost ones on eBay.
I just want mine to work!
A very valid goal.
And I think it is OK to inform new users by posting every so often that these mods are not strictly needed to have a nicely working $90 AWG signal generator with a good cost/benefit ratio out of the box. But that does not mean we cannot play.
And also, every so often some handy piece of information may fall out that even the more conservative owners can use.
But yes, adding a €45 TCXO on a $90 device also took my attention. Only do that if you enjoy doing that.
What's the status of just getting usable FW in my 3.1 unit? Are we there yet?
For what it's worth as another data point for discussion on this topic, I'll add my experiences with our shop purchasing the Koolertron version of this generator a couple of months ago.
The 60MHz unit arrived from the Ebay vendor's warehouse in Walton, KY quickly. Upon initial unboxing and examination of the unit, it was discovered that several waveforms were missing from the generator, right out of the box: Lorenz, Sinc (I assume they meant "Sync"?), Multi-Tone, Exp-Decay, Exp-Rise, and Noise. No waveforms were output, and the representative waveform on the display was missing; nothing but a flat-line. Immediately I filed a return. The vendor was quick to answer back with accusations that I didn't know how top operate the generator, that I should watch a video, and that obviously the generator was fine - the PEBKAG. They demanded me to post a video of the problem before they would do anything about it. I wasn't going to stand for that crap and having to jump through their hoops (I can't easily post a video for their amusement) and let them know exactly what was going to happen; send the defective device back for a full refund. First they stalled a few days. Then their shipping label that they uploaded to Ebay was irretrievable. Upon investigation, it was discovered that this is a frequent ploy that some less-than-honest sellers will do; upload an invalid .pdf file as a return shipping label, and in the process, shift all of the legwork of doing the return to the poor soul who bought the defective item in hopes that they'll eventually just give up, or perhaps stall things long enough that the return period will expire.
Long story short, I ended up having to drive tens of miles to get the thing shipped, using my own money. Their idea of "reimbursement" for the shipping fee was to short change me by exactly $1. They told me that since they accepted return on my device (yeah, after more than 2 weeks of back-and-forth ridiculousness!) they expected me to reverse the negative feedback given for the transaction (the first and ONLY time I've ever given such in 15 years of Ebaying). And their response to that negative feedback was that I didn't know how to operate the device. Uh... yeah. That's it... I knew how to get sine, square, triangle, and all kinds of other waveforms out of the device but for some reason I just didn't know how to operate the unit well enough to get those other waveforms out of it.
At least the ARB waveforms would work, and I left within the generator a nice little hand-drawn "hand with middle finger saluting them" waveform.
After all that fiasco, I bought the Feeltech model. The buttons aren't as nice, and I'll have to deal with the voltage on the ground lead, but other than this, so far so good... I just need to check what version of firmware.
And if anyone needs to know the vendor name, let me know.
Could someone who owns one of these FY6600 signal generators do a simple test - could you set the unit to output a pulse waveform at 10MHz with a ~40% duty cycle and see if it has any jitter as described in this thread:
https://www.eevblog.com/forum/testgear/rd-jds6600-signal-generator-jitter-on-pulse-output-when-duty-cycle-is-not-50/
If the Feeltech is clean I might return my unit, otherwise I suppose I might live with it *sigh*.
Thanks much.
I am assuming that the 5ns jitter comes from the 200MHz sample rate that the unit has. I don't really know how DDS signal generators work, but I am assuming this 5ns is an artifact of the 200MHz base clock.
My modified FY6600 has jitter on 50% duty cycle but not at 40%...go figure.
My modified FY6600 has jitter on 50% duty cycle but not at 40%...go figure.