The lowest I can bias is (a very high number). Whats wrong?
The vast majority of people who experience this have really conductive power tubes. I’d return them and ask for a pair that doesn’t conduct as well. If not I would check the screen resistors. Measure the voltage drop across the resistors, then calculate screen current. If the screen resistors seem fine and other tubes still conduct too well (100+mV read at the bias test point), then I would increase the negative voltage applied to the power tube’s control grids by raising R77 in increments. This will solve the problem if the previous two do not.
