DC coupled 71A amp. I would really appreciate it if someone would verify my calculations. My B+ is ~360 volts and there is ~130 volts on the plate of the driver tube. This of course shows up on the grid of the 71A. The 71A runs at 20 ma and 180 volts on the plate and 40 volts bias. I lose ~10 volts through the winding of the OT so I have 350 volts less the 40 volts bias and 130 volts that comes from the plate of the driver tube for 180 plate volts. Therefore I believe that I need a cathode resistor of 8.5Kohm ( 130 volts plus 40 volts/20 ma ). I need reassurance as frankly I find this whole concept of DC coupling a trifle difficult to get my head around
Robert Lees
