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Hantek 2000 series - 2C42/2C72/2D42/2D72

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gf:

--- Quote ---I did some measurements in single channel mode (with -70...)
--- End quote ---

Was the "70" patched in the firmware? Or in other words, which model was it natively?

Thanks,
gf

JimBeam:
My device is a native 2C42 with the -70 patched in flash.

I used a R&S SMIQ03B Generator for the DSO tests set at 0dBm output and a 50 Ohm feedthrough termination on the DSO inputs.
The AWG output was observed on a RIGOL DS1104Z with the same cable setup reversed.

I will repeat the AWG measurements more exactly when time permits, maybe using a DSA702 to record the spectrum,
but I'm not expecting miracles anyway as the 2000 series are devices in the low price segment.
HANTEK even replaced the intended inductors on the board by 0 Ohm resistor to cut prices...
Yet they were so nice to retain a lot of the parts in the AWG that would not have been necessary to keep.  :-+

The presence of the AWG section is simply detected by R65  8) This is the DAC enable signal from the FPGA forwarded to the MCU via R65.
The chosen value of 560 Ohms is just my educated guess, some russian guy in a YouTube video used 50 Ohms.
Maybe someone with a genuine 2Dx2 could confirm the real world value of R65? The pictures in this thread are too blurry to read the marking.


--- Quote ---In my 2D72, the negative rail of the EL5166 measures rather about -3.3V
--- End quote ---
The mentioned -4V for the -5V rail were just from memory, I did not note the exact value.  :-//
When I saw the clipping I looked for a cause, found the -5V not being 5V, checked the feedback divider resistor values in the supply  - and modified them without any hesitation.

Btw.: Being at it, I retrofitted the SD card holder - to no avail. I guess there is no support in the SW.

JimBeam:
I just did some calculations around the DAC:

With an Rset of 2,2k we get a fullscale output current of around 18mA, which results in a voltage drop of about 0,9V across the 50 Ohm output load (This disregards the input impedance of the OpAmp input dividers, but as I used 51 Ohm resistors anyway, the difference should be neglectible.)
As the gain of the output driver is 3,733 (560/150 Ohm) the fullscale output voltage at the BNC (without load) is 0,9V * 3,733 = +/- 3,36V.

So the DAC range isn't fully used - or is there a mistake in my calculation?

gf:

--- Quote from: JimBeam on March 05, 2019, 06:41:20 am ---The presence of the AWG section is simply detected by R65  8) This is the DAC enable signal from the FPGA forwarded to the MCU via R65.
The chosen value of 560 Ohms is just my educated guess, some russian guy in a YouTube video used 50 Ohms.
Maybe someone with a genuine 2Dx2 could confirm the real world value of R65? The pictures in this thread are too blurry to read the marking.
--- End quote ---

I have a genuine 2D72. I have attached a photo of the (non-existing) R65 :-//

gf

JimBeam:
Ooops, that's the wrong R65 ...
I mean the one marked in the attached picture. (I hope Microcheap forgives me "borrowing" his picture from reply #38)


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