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Review: Hantek DDS 3X25. Anyone own one?
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vehf277:
Hi everybody!

I am newbie in this thread.
I bought Hantek 3X25 a few days ago and found some strange/wrong in coming out signals.
I checked three wave types - sine, triangle and saw. All three signals are 500mV 1000Hz. The signals are looking as normal but a signal envelope looks like not a flat bar but a mixture(not a modulation) of signals, 1kHz and much lower frequency. You can see the screen captures made by OWON SDS7102.
The question is: is it normal for Hantek 3X25 or not, did anybody see this the same and if it's wrong how to fix it?

Thank everybody in advance for help!:)
saturation:
It looks like you cabling issues as your 'carrier' is modulated or mixed with what looks like line frequency, ~ 60 Hz.  The Hantek output is quite clean if properly hooked up.
vehf277:
Thank you!:)
TriodeTiger:
The thread spawned an interest in me to purchase one of these on a small eBay sale for $120 :) It's got its quirks, but suits me for anything I can possible think of on the lower frequency end.

With my new scope to be written about, I measured the sync phase offsets on a sine wave with the beautiful GolTek software (the original supplied software wouldn't let me write a DLL file to system32, even with admin privileges or manual copying of it beforehand :palm:)


--- Code: ---  100kHz: Sync Phase: -1 degrees / -20ns
  1MHz:   Sync phase: -9 degrees, -25ns, sync jitter: +/- 5ns or 3 degrees
  10MHz:  Sync phase: -70 degrees, -20ns, sync jitter: +/- 4ns or 10 degrees, (sine at this point)
  20MHz:  Sync phase: -160 degrees, -25ns, sync jitter: +/- 1 ns or 5 degrees
  20MHz+: (Mostly noise at this point.)
--- End code ---

That seems pretty useless for anything over 1MHz for sync.

Ah well, all for now.

EDIT: Odd, his phase correction turned off reduced the error by ~10x, 1 and 10MHz offset becomes ~2ns now. What's up with that? That's significant for 10MHz, since phase is now only +/- 5 degrees instead of 70.

A goodie shot, transfered through a 3.5'' medium of some kind, I remember those :wtf::
tymm:
Just as an update, I've done a bit more work on the DDS3x25 Python code and - while things are by no means complete - I think it's in not too bad shape for most general use... There are simple interfaces for generating sine & square waves of arbitrary frequencies, for setting/getting digital IO values, for using the counter, etc. 

Code can be found here:
https://github.com/tymmothy/dds3x25
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