Gotcha loud n clear. ThanksSorry to rain on your parade, but adjusting negative bias voltage is not proper way to adjust bias current.
New tubes are different than old stock and most likely that -35volts doesn't really follow requirement for bias current.
It might work but I would prefer to measure bias current.
Very cool....i was reading about this type of contraption recently: the author had used two or three hand held meters in unison to achieve the result until he built similar...I used to have a simple store bought version called a BiasKing ? once..not sure where it went🤪Years ago I built a plate current fixture to allow the monitoring of octal, pin 3 plates. I used an analog meter from a defunct VTVM and calibrated it for 100mA full scale deflection or FSD, through selection of the correct shunt resistor for 100mA FSD...custom made.
It has a switched, dual adapter interface that enables me to conveniently monitor a dual output configuration.
It is a low cost test fixture if you can scrounge up the parts.
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