[Amps] Henry 3K trouble

[Tom W8JI]

> The HV came back after replacing the resistor, however now 
> my grid
> current goes way high.  Even keying the amp with no audio 
> on SSB shows
> about 15 to 20 mils of grid current.
>
> When I applied some excitation (maybe 5-10 watts), it did 
> indicate
> output and plate current, however not knowing if the meter 
> was reading
> correct or not, I did not take much time to measure actual 
> output for
> fear of losing the grid.  With 20 to 40 watts of drive, 
> the grid
> reading nearly goes off scale with no effect turning the 
> load cap.
> SWR is 1:1, so no problem there.

Brian,

That is almost always a short from the negative rail of the 
HV to ground at the filter capacitor side of the metering 
circuit.
What that will do is place the grid meter in parallel with 
the plate current meter.

Look for a diode that goes from the chassis to the negative 
rail. It is normally a conventional rectifier diode, 
although it could be a low voltage zener.

73 Tom