Not sure if this was the thread where the amp had a meter called "Cathode Current". Whenever you see an older home brew amp with a meter labeled cathode current that is because the meter is reading cathode current and NOT plate current. Here is the rub on this. If you are home brewing a grounded grid amp and I do mean solidly grounding the grids not floating them on resistors. Many old timers who built home brew amps wanted to solidly ground the grids but if they did NOT raise the B- off chassis ground you could not meter grid current. You either have to float the grids on resistors or raise the B- above ground. I'd assume this amp had the B- grounded to the chassis.