Yeah, I know I lent you my 2 cents in your original thread but I was wrong. I think only a circuit problem like the above referenced resistor could explain your Fluke reading.
ARC ref 110 tube bias prob
All is going well but the last two tubes (master and slave) are showing weird readings.
The master shows no reading and reading 16.76 volts DC (not 0.65mVDC!) on my Fluke. The slave is showing a negative rating (-20mVDC).
The tubes are all good (swapped them over) but any tubes in that position do the same.
Anyone know what’s going on?