Yves,
?
In the meantime did some additional checking. I figured the biggest difference seemed to be in the TP1 temperature voltage.
I did a simulation of the circuitry but both our tp1 voltages seem to be reasonable. The main influence on the voltage level is the IVT potentiometer, R88. This one is glued to R33 on my board with some grey gunk. So I can't check if the value is reasonable compared to the pot setting. I didn't see any glue on your board, wondering if that was done in the factory.
Does look somebody has been fiddling with the potmeters in the past:
?
After checking TP5 I figured the next interesting point might be J1 which has the output signal of the log amplifier board
The output ratio seems to be slightly off from TP5, being 17dB.?
?
During these measurements I found something which surprised me. To measure the signal I removed the cable from the Log amp to the Opt 130 and connected the TinySa to J1 of the Log amp, as expected the signal on the 8591E disappeared. When I reduced the RBW to below 1khz, the signal reappeared on the 8591e. Note, the jumper wasn't placed on the LogAmp.?
I was expecting the signal always to come from the logamp to opt130 but on futher check of the schematics it seems the AUX IF is used to feed the signal to the opt130. There is no schematic of the 130 in the CLIP sadly.
?
I also spent some time whipping up a python script together with ChatGPT to render the rs232 HPGL output, getting there, just some issues remaining with the select indicators under the labels in the right side menu. If there is any interest for this script in the group i'll gladly share it
?
Marco
?
