General > General Technical Chat
Review: Hantek DDS 3X25. Anyone own one?
Mechatrommer:
--- Quote from: seattle on April 30, 2011, 06:07:52 am ---Hi, has anyone looked to see if the amplitude adjustment on the 3x25 is done via an analog gain stage, or if it's done via limiting steps in the output DAC?
--- End quote ---
i think someone who are familiar will be able to tell from my teardown pictures earlier (relinked below). from my limited knowledge, i think its not by analog gain stage, its all comes from the 12bit pins of DAC. and as no info on the DAC model, last time i search to no success. hint... 200MHz clock 12 bit DAC, the closest i can find is ISL5861 210MSPS DAC Chip but looking at the pictures, i dont think it is.
--- Quote from: seattle on April 30, 2011, 06:07:52 am ---Has anyone seen some USB flakiness? It can be fixed by unplugging and replugging. Just wondering if it's my machine or others have seen this.
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yes its with my machine too. it hanged from reporting any value to pc software. un/re-plugging solve the issue. but its with my homemade software (api calls) i dont know if its happened with the bundled software, never experience that. so it could be the machine, or it could be the software.
thanx for reviewing and joining in seattle. i believe you have more capable machine of testing the noise floor than me. the spectrum on SA 3.4vpp.JPG looks sexy, do u mind to tell what machine it is?
seattle:
--- Quote --- it hanged from reporting any value to pc software. un/re-plugging solve the issue. but its with my homemade software (api calls) i dont know if its happened with the bundled software, never experience that. so it could be the machine, or it could be the software.
--- End quote ---
Yes, it does happen a fair bit with the bundled SW on my machine. So your SW is likely at the mercy of their libs in terms of stability :)
--- Quote ---thanx for reviewing and joining in seattle. i believe you have more capable machine of testing the noise floor than me. the spectrum on SA 3.4vpp.JPG looks sexy, do u mind to tell what machine it is?
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It's a chinese USB scope called QA100, dual 100Msps 10-bit adc with 32 channel logic analyzer and super deep memory.
Mechatrommer:
it seems somebody got mixed up between RIGOL DG2041A and HANTEK DDS 3x25...
RIGOL DDS-3X25 video signal generator
torch:
--- Quote from: Mechatrommer on May 07, 2011, 09:28:11 pm ---it seems somebody got mixed up between RIGOL DG2041A and HANTEK DDS 3x25...
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I don't know much about these things, but neither of the two standalone units pictured made me think "cost-effective, USB function/arbitrary waveform signal generator (card) (virtual)." :o
torch:
So my DDS3x25 arrived today, and I fired it up to put it through it's paces.
First thing I found is that the manual is wrong -- at least for Vista 64. The drivers are buried in an archive on the CD and must be extracted manually -- the install program copies over the 32 bit drivers, not the 64 bit ones.
With that sorted, I fired up their program and made sure things were talking. Then I shut it down and fired up Mechatrommer's version. Might as well try out the auto configuration routine, right? So I dug out another bnc cable, two terminators and another USB cable, hooked it all up and let it go. (The little graphic was great -- makes the connections idiot proof -- I need things like that ;-) )
Once it was done, I started playing a bit. I noticed that the rise time on the trigger output was much quicker than the rise time on the square wave output when I cranked up the Rigol to 2ns. It also had a tiny ring that the output didn't have. That seemed odd, so I swapped terminators -- no difference. Then I swapped cables and the signal shapes swapped. On closer examination, the cable that came with the DDS3x25 was an RG58/U. The one I had in the drawer is an RG58/UA. I've never had either a signal generator before, nor a scope fast enough to see this level of detail, so maybe you all know about these differences already, but for any other newbies shopping for cables, the RG58/UA seems to be the better choice here.
Ok, I'm an idiot. It's not the cables, it's the function generator. :-[
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