General > General Technical Chat
Review: Hantek DDS 3X25. Anyone own one?
alm:
The specs for that LA sounds close to the Intronix LogicPort, I wonder if it's a clone.
Note that software is critical for a PC-based LA, triggering, decoding and searching through signals are essential for operating an LA. I wouldn't buy a LA without first trying the software. I hated the Zeroplus software, for example.
saturation:
Nice discussion. I see it a little differently, what we want out of the 3x25 is a function generator with defined distortion and stability in its frequencies, how this is done is another thing.
If this can be done cheaply by a hodge podge approach yet still provides the primary functionality, then its really a good thing. I think we've seen its strengths and weaknesses as we continue to dissect it.
I've seen 'bad' analog designs by Horowitz and Hill's criteria such as in preamp stages that are in real products, but they work, so time has proven these to be cost effective. One example of those is the fan speed controller on the Atten 858D workstation, dissecting it to make it safe also made me laugh.
The Atten 858D workstation is well discussed on eevblog, it really provides stable output heat but not a true scaled measured flow rate, but it drops the cost of hot air workstations 10X against a true brand name, and its 1/3 cheaper than a even knock off Chinese hot air workstation ... its a design unique to Chinese gear as this Hantek is. All they did is take the controller circuit similar for the Hakko 936 soldering station, and used it to control the heating element of a hot air gun; then they put a variable wire wound pot in a 24VDC circuit to simply drop the supply voltage for the fan, for 'variable' control, how goofy is that? But it works! Excess power is dropped into the pot and is wasted, but the total power of this DC circuit is < 1 watt, and the pot never becomes hot to touch at the lowest speed setting, so it should be reliable if the transformer doesn't fail.
Of course, it has its unfixable problems. You have line voltage in the handle, which is not allowed in many industrial setting to avoid shock hazard, they prefer DC in hand tools. But then, hot air guns are allowed by industry for commercial paint stripping, in many powertools, and in consumer items as hair dryers, so why not in a hot air workstation in a non non-ISO certified setting?
Which brings us back to the 3x25. What more can be squeezed out of it to improve or extend its function generator capabilities? But if you need it to study true DDS technology I think you've shown its not.
marmad:
--- Quote ---If this can be done cheaply by a hodge podge approach yet still provides the primary functionality, then its really a good thing. I think we've seen its strengths and weaknesses as we continue to dissect it.
--- End quote ---
True. If I can just get it to output a stable sweep sequence, I will be fine with everything else. And it may end up working - I'm trying a few tricks today.
But it is important to point out that Hantek is saying they use DDS technology in the device - and they're not really doing so.
Mechatrommer:
--- Quote from: saturation on July 23, 2011, 01:19:17 pm ---But if you need it to study true DDS technology I think you've shown its not.
--- End quote ---
i think it is, from all my (limited) reading and latest links above. DDS only convert digital data into analog data (wave) what else does it do? the only thing lacking imho in 3x25 are:
1) adjustable frequency or gain whatever on hardware level (not in fpga)
2) filtering on the output analog signal to reduce noise.
3) good fw implementation in fpga (or pc? ie dll or usb comm) to mimick/simulate (whatever your definition) a DDS.
saturation:
I hope you succeed, we will all be merry! For the bolded items, I couldn't agree more, but we read so many untruths in advertising and worse the spec sheets, from many China branded items that its not worth your effort to take their specs seriously; we all ended up reconfirming performance to see its true capabilities, its a similar story with the Atten 858D workstation story I posted.
Before I bought mine, early in this thread, I scouted other users who did the initial testing for me. I think a Japanese radio restorer was using it to repair AM/FM radios, which at least told me it provided a usable output to the top of FM, ~ 100 MHz.
--- Quote from: marmad on July 23, 2011, 01:39:19 pm ---
--- Quote ---If this can be done cheaply by a hodge podge approach yet still provides the primary functionality, then its really a good thing. I think we've seen its strengths and weaknesses as we continue to dissect it.
--- End quote ---
True. If I can just get it to output a stable sweep sequence, I will be fine with everything else. And it may end up working - I'm trying a few tricks today.
But it is important to point out that Hantek is saying they use DDS technology in the device - and they're not really doing so.
--- End quote ---
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