[Peter]

I connect my DMM as advised to calibrate card1, success. :-)


When I start with ch2/card2 I can't trim T2 to match off/on VAC. It differs at the best around 1 VAC

As is I connect DMM to the back on my lunch box. Else, which TP's on card2 is preferred?

[JPK]

On channel 2, the input signal just after unbalancing is on TP6
and the output signal just before re-balancing is on TP7.
You can see this clearly on the schematic.