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Hantek HDG2002B AWG: 5Mhz or 100MHz? Let's see!

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alex.forencich:

--- Quote from: IanJ on November 03, 2014, 09:09:27 pm ---Question about calibration..........

Am I right in saying you just hook up a volt meter to it's output and enter in all the voltages that appear at the output. It seems to throw a few voltages to me to start with but then did a whole load the same, even negative voltages till it completed.
When I then tested......my amplitude is all over the place at various frequencies.

Am I missing something with the procedure?

Ian.

--- End quote ---

Use a scope.  The unit needs calibration points at various frequencies to compensate for front end frequency dependence. 

fremen67:

--- Quote from: Howardlong on November 03, 2014, 08:04:55 pm ---OK I answered my own a) and b) questions by looking at thr behaviour of the device at the already calibrated low frequencies. And, it wasn't that well calibrated!

Firstly I did not use a 50 ohm termination because that wasn't the way the device was already cal'd. I also realised very quickly that it's not a very accurate 50 ohm impedance either, even at DC.

For the first ten or so DC measurements I used a DVM, so far so simple.

For the gazillions of other measurements I used an Agilent 54831d scope with a calibrated 10x probe coaxially fitted _directly_ into the AWG's output to avoid any standing waves problems due to non-termination at higher frequencies. I used the mean Vpp measurement on 10 averaged waveforms, and the measurement was reset each time, with the time base and vertical set appropriately as necessary.

It took a long time, probably an hour or so just for one channel, but the results are excellent compared to how it was.

However I've now realised there's a hardware filter tweak I possibly ought to have done first.

By the way, make sure the AWG was set to sine wave on the channel in question before calibrating. Trying to calibrate on a square wave is no fun due to the overshoot when not terminated, and the cal procedure did not seem to reset this on my unit.

--- End quote ---
You did not let me enough time to reply  :)
I can't add a lot more as I did the same way:
- sinus wave
- no 50 ohm termination
- a DVM for the 9 first values
- My MSO5062D for the 3 sets of 27 values from 500kHz to 95Mhz, using average value on 16 samples
- directly fitted in the HDG output
- also took an hour for the first channel
- gave up for the moment for channel 2
The results are now very accurate for DC values after calibration.
For AC it is better as I can now go up to 100Mhz but I can see the impact on a change of output range on the HDG. There are small steps on the output after each change of range. I just run a self calibration on the MSO before calibration but my probe must not be very accurate.

Regarding Wave generator, it was not working at all with FW 1.00.1 so I gave up and just used the software on the PC for that. I did not test it since I upgraded to FW 1.00.2

fremen67:

--- Quote from: IanJ on November 03, 2014, 09:09:27 pm ---Question about calibration..........

Am I right in saying you just hook up a volt meter to it's output and enter in all the voltages that appear at the output. It seems to throw a few voltages to me to start with but then did a whole load the same, even negative voltages till it completed.
When I then tested......my amplitude is all over the place at various frequencies.

Am I missing something with the procedure?

Ian.

--- End quote ---

From what I remember, only the 9 first values are DC. You need a scope for the others ( 3 sets of 27 values I think)

I recommand that you write down all the values you measured at the same time you enter them... just in case you have to start again from the beginning

IanJ:

--- Quote from: fremen67 on November 03, 2014, 09:18:50 pm ---
--- Quote from: IanJ on November 03, 2014, 09:09:27 pm ---Question about calibration..........

Am I right in saying you just hook up a volt meter to it's output and enter in all the voltages that appear at the output. It seems to throw a few voltages to me to start with but then did a whole load the same, even negative voltages till it completed.
When I then tested......my amplitude is all over the place at various frequencies.

Am I missing something with the procedure?

Ian.

--- End quote ---

From what I remember, only the 9 first values are DC. You need a scope for the others ( 3 sets of 27 values I think)

I recommand that you write down all the values you measured at the same time you enter them... just in case you have to start again from the beginning

--- End quote ---

Yep, managed to suss it out........great stuff!......and now I have a reasonably even amplitude for all freq up to 100MHz.....rather than tailing off severely not much above 20MHz.

I'll go over it again more accurately now I know how it's done.

Ian.

andrija:
I can confirm telnet over LAN works fine once you add the necessary parts and configure the (static) IP address. So you don't have to get a FTDI if you don't have already and can "upgrade" to 100MHz by editing the file via LAN. Just enter "root" as username (there's no password).

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