OK, time to cast my lot in here. I'm attempting to go through the calibration process. Last night I was having a hard time getting readings consistently, so I figured it was cold solder joints somewhere. Touched that up, and now during the Q-bias setting process, I'm getting a little more output than expected (1.97 vAC/8.11 dbU). I'm also getting a quiet but audible hum when no test tone is applied, and I wonder whether that raised noise floor is contributing to my readings. These are my first three test point readings:
TP1: 6mV (nominal)
TP2: 121mV (a hair high)
TP3: 984mV (also a bit high)
Also, my TP9 is bang on at -10V, and I have the expected +/-15V on A3. I tested that 0252 in another module and it sounds fine there.
Is this device particularly sensitive to flux residue? I've cleaned it, but I don't feel like the flux remover I have is great. Tends to leave things kinda sticky. If not that, any other ideas where a hum might be coming from?
Also, for the benefit of posterity: I made a big mistake initially in this build, which was that I didn't notice that RV1 and RV2 aren't interchangeable, despite the fact that they have the same value. I flipped them, so neither trimmer was accessible. With difficulty, I managed to extract them and swap them. By turning RV1 as far clockwise as it will go, I can stop the meter lights from being illuminated, which I'll take as a sign that the part still works (I also measured them both before putting them back in, seemed fine). Anyway...don't be like me and do that if you're looking to build one of these.