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Hantek HDG2002B AWG: 5Mhz or 100MHz? Let's see!
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50ohm:
Does anyone know what type of signal is suitable as external reference clock? It looks that Hantek HDG2032 does not lock properly to standard sinewave reference from rubidium master clock. If the output signal is measured with oscilloscope, it looks just fine. The frequency and phase are both locked to external reference just fine - according to oscilloscope...

But... when measuring the signal with spectrum analyzer there's huge difference between internal and external reference clocks. With exterenal clock there's wideband noise covering all over the band!

It looks that the standard 10 MHz reference signal is not enough for Hantek. It has output of +10 dBm. I was able to amplify this to about +20 dBm, which gave much better results with Hantek. At most of time the Hantek output was stable, but still there was moments with noisy output. So it might be that +20 dBm is just on the edge of working reference level.

But: +20 dB is very high level for reference signal! Really; it means 100 mW transmitter power, same as in WLAN! It's really very HUGE signal as clock reference. Too much. Something must be wrong with Hantek's reference input circuit.

The internal reference seems to be off about -200 Hz, when the unit is warmed up more than 30 minutes (normal warming period for all lab instruments). This was verified with 10 MHz output setting and from reference output jack at the backside. Both shows exactly same result with 10 MHz setting - like they should do.

With external reference we can have stable and correct frequency at the output - for the short moments when it's working without noise. At most of the time threre's wideband noise but even when it occurs the fundamental output frequency was correct according to specrtum analyzer's counter.

Here's my tests with 10 MHz/1V output setting. I also did some wideband noise/spurious measurements with 15 MHz setting. It seems that the output blocks are not properly shielded because the 10 MHz reference leakage is clearly visible at generator output. Also some other spurious frequencies and raising noise level around fundamental was detected. The 10 MHz leakage is clearly visible and verified with spectrum analyzer's counter and it's same as Hantek's erratic reference frequency. Also it's harmonic was visible on 20 MHz.

As for comparison I took a same measurement from Marconi 2022C RF generator ouput with 15 MHz / 0 dB settings with external reference. This Marconi is not even very high quality RF generator yet - but like we can see the Hantek's output is not very clean.

So there's some modification work to be done to get the external reference working and to shield the output blocks so that there's not so much spurious.
markone:
I'm not following this precious 3ad for several months, now i'm the hurry to make some RF work and i have a straight question in order to decide what to do with this instrument (ie sell it for a siglent/rigol one) :

is the fault of uncalinbrated amplitude frequency sweep function solved by the last FW update and/or FW hack ?

Right now i'm away from home and i'm not able to test it with the last firmware revision.

Several months ago i put it straight in the box as soon as i discovered that freq. sweep function does not (did not, at least) take in account calibration data, ie if you sweep from 1 to 50 Mhz, the amplitude of the signal will decrease A LOT with frequency rising.

Any help will be appreciated !
50ohm:

--- Quote ---I'm not following this precious 3ad for several months, now i'm the hurry to make some RF work and i have a straight question in order to decide what to do with this instrument (ie sell it for a siglent/rigol one)
--- End quote ---

Here's 100 kHz...30 MHz frequency response plots from unmodified Hantek 2032B with 1V output setting. Firmware version is 1.00.3.03.05 (150807.0). Calibration data is also untouched, original data from factory.

Results are measured with spectrum analyzer using trace max hold function.

First attached image includes three traces:

Green one is what you asked about: it's frequency response of automatic sweep from 100 kHz to 30 MHz from 2032B.

In the blue trace there's manual sweep with 50 kHz steps from 2032B. If we compare these two traces, we can notice that calibration data is not applied with automatic frequency sweep. Total amplitude error between 1 MHz and 30 MHz with frequency sweep was measured with delta marker and it was 2,09 dB.

Please note the notch at 24,6 MHz on manual sweep trace. At this point, relay clicked inside Hantek. Maybe some kind of output filter was disabled and/or the output impedance was changed because the level increased about 0,3 dB there. This relay is not clicking in automatic frequency sweep mode, even with very slow sweeps like 120 seconds.

In the red trace there's output from Marconi 2022C RF generator with -1 dBm setting and manual frequency sweep with 50 kHz steps. Those little 0,1...0,2 dB notches in this (and other) traces are spectrum analyzer calibration errors (this graph has 1 dB vertical scale while it's normally 10 dB so the spectum analyzer's frequency vs. level calibration table errors become also visible in this measurement setup).

If you plan to do any RF work, please consider to buy RF generator instead of any function generator. At least with Hantek, possibly with other ones also you will face some serious issues if you try to do RF work with it:

- General spectral purity problems and huge reference/spurious frequency leakage (please see my previous post)

- Insufficient frequency area for any kind of modern RF tuning. Suitable only for IF blocks testing.

- There's no dBm setting for the output - and the voltage setting does not correspond to any real world dBm in the "50 ohm. world" anyway! It shows correct voltage levels only against oscilloscope's 1 megaohm input, when spectrum analyzer and all other RF instruments have 50 ohm. impedance.

- You cannot generate any faint signals. With minimun setting the output is 2 mV. This is shown as -56 dBm at spectrum analyzer. This is too loud signal for any kind of receiver tuning etc. You will need external step attenuator to generate needed levels. With RF generator, you can go beyoud -100...-130 dBm depending on model. For example, most receiver tuning/testing tasks require usually less than -100 dBm signals.

- There's huge leakage from generator output also when the output is turned off! Output relay does not cut RF signals. Please see the second measurement, it's time domain level analysis when the 30 MHz output is first on with 1V level, then output turned off. The output relay has only ~56 dB attenuation at 30 MHz, so in the RF world it doesn't cut the signal at all... :) If you want the generator to be silent you will also need to set the amplitude to the minimun value or turn of the whole generator. This leakage is frequency related; with 1 MHz the relay had 82 dB attenuation.

- Output connectors are BNC type, when all RF instruments have N type. If you use it with different kind of RF stuff you will need adapters.

I hope this helps.
markone:

--- Quote from: 50ohm on January 12, 2016, 04:50:21 pm ----snip
I hope this helps.

--- End quote ---

Sure it helps, many thanks for your post.

I agree with all your statements, for serious purpose we should start from something like Rigol DSG815.

For HF receivers sensitivity test i built a 60dB fixed attenuator to put in line with other fixed attenuators, nothing critical, just to get some rough estimations.

During this day i flashed the hantek with last FW (150807) and i get the very same result of the past, that is identical with yours.

I addition, now AM modulation function with internal mod. source is no more working properly, see the attached image  :palm:

The funny thing is that when i enable the function it works properly for a couple of seconds, then starts with the strange amplitude envelope that you can see in the scope screen shot.

I fear that i have to reset / re-flash the instrument, maybe losing cal data.

Current instrument SW / HW info :

SW 1.00.3.03.05 (150807.0)
Kernel : 3.2.35
FPGA 21
KEYBOARD 3

PCB 1004

Any help will be appreciated.
Berni:
Yeah the firmware is horrible. Most modulation features will do something weird if you set them to just the right values, sometimes the waveform preview on the main screen glitches and shows markers that cut in to the text above it or just plain shows something that's not right. Even the output enable button does not work properly. I had a case where i somehow got the unit to have the output enable button lit up signaling the output is enabled but there was no output, pressing the enable button again the button stayed on but there was waveform output after that. Some settings also crash the unit and make it reboot, if you have selected to remeber the last setting it will reload them and get stuck in an infinite reboot loop until you factory reset it. It just goes on and on.

Its a real shame since the hardware in there is pretty nice but the software ruins it.
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