I am in the process of completely upgrading both the power supply and
tube(s) of two Henry 2K-4's. The custom designed step start, Hipersil
4KV+ small footprint supply will drive an 8877 in the first effort. A
pair of 8877's is planned for the second project. Both OEM meters are
1ma full scale. The dedicated plate current meter scale reads 0-1 amp.
This plate meter offers no wiring problem since I plan to fabricate a
nichrome shunt across the meter terminals and place the it series
installed in the normally open (close on transmit) relay return line
from the cathode/filament and through the zeners to the B- on the
rectifier board.
However, here's where I need some guidance! The multimeter
is also an identical 1ma full scale movement with a scale of 0-400. It
reads forward/reverse output power, HV, and grid current. NO problem in
the first three switch selectable positions since the meter acts as a
voltmeter and samples those power levels via the Henry circuitry. What
I'm not certain about is how to accurately read the grid current from
the new circuitry currently in place. Since the second meter is also
1ma full scale, I imagine there will have to be some type of resistor
sensing package wired someplace in the circuit so that in the grid
position I can monitor the tube's performance. Any circuit design
assistance getting that aspect of the grid circuit to function would be
greatly appreciated. Thanks, Ron W2CQM/3
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