In a message dated 11/25/2010 12:56:12 A.M. Eastern Standard Time,
Gary@isect.com writes:
Any idea what fault would cause my old and previously faithful Amp Supply
Co
LK550 sometimes to register ~400mA of plate current and negative grid
current, even with no PTT and no drive?
A bad tube with an intermittent grid to filament short. Usually when the
grid current goes negative but the amp works OK then your grid shunt
resistor is open. In your case I suspect a bad tube. If you had said you got
plate current in idle no drive, I would say it is oscillating. But you got a
questionable tube I think.
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