High Voltage Supply - Command Technologies COMMANDER VHF-2000 Manual

OUTPUT FILTER CIRCUIT
The PI variable network filter transforms the plate load impedance from
approximately 1600 ohms down to 200 ohms, Two air variable capacitors
and an associated inductor accomplish this transformation. A design "Q"
of 14 allows for good harmonic attenuation all across the band. The
utilization of a special reactance tuned powdered iron core 4 to 1
Transmission line transformer transforms the nominal 50 ohm antenna
impedance up to the 200 ohm output of the PI circuit. This also achieves
further harmonic attenuation of the output in the same manor as an "L" coil
in a Pi - L network. Additional harmonic attenuation is accomplished with a
bandpass filter on the output.

HIGH VOLTAGE SUPPLY

The high voltage supply operates from 117/200/234 Vac 20\30 ampere
line. The primary of the high voltage transformer is switched on/off with
solid state relays that during power up, only conduct when the phase
angle of the AC power line is at the 0 to +30 degree crossover point. This
minimizes line surge and inrush current while the high voltage filter
capacitors charge. The front panel on/off switch activates the solid state
relays with 2ma AC to turn the unit on. Approximately 900 volts AC is fed
to a full wave voltage doubler rectifier circuit. This supplies approx. 2600
volts DC to the 3CPX800A7 s anodes. Metering of the tubes anode and
grid current is accomplished by shunt resistors located in the negative
return of the 3CPX800A7 s cathodes. Plate voltage metering is
accomplished by a resistor multiplier network in the B+ line of the high
voltage circuit.