[Amps] Reverse grid current on standby

[Michael Schwab]

I would ask for possible input on a (to me) puzzling issue:
I am using a gg 3cx1500 amplifier. On stand-by I see a very low amount of reverse grid current (5-10mA) indicated. When I key up the amp and transmit it swings into the positive.

Metering circuit consists of a 10 Ohm resistor between B- and ground and a 5k variable resistor to the + side of the meter, the other leg of the meter grounded.

What am I missing?

Mike, OE6MBG