High Voltage Supply - Command Technologies COMMANDER HF-2500 Manual

OUTPUT FILTER CIRCUIT
The PI variable network filter transforms the plate load impedance from
approximately 2,500 ohms down to 200 ohms, Two air variable
capacitors, and an associated inductor, accomplish this transformation.
A heavy duty band switch selects the proper inductance from two high
"Q" inductors. Each inductor contains taps for the desired band. A
design "Q" of 14 allows for good harmonic attenuation on all bands.
The utilization of a special reactance tuned ferrite 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
provides further harmonic attenuation of the output, in the same
manor, as an "L" coil in a Pi - L network.

HIGH VOLTAGE SUPPLY

The high voltage supply operates from 200/234 Vac. 20 ampere line.
The primary of the high voltage transformer is switched on/off with
solid state relays, that only conduct when the phase angle of the AC
power line is at zero degree crossover. 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 applied to a full wave
voltage doubler rectifier circuit. (On the HF-2500 MAGNUM, 2400 volts
AC is applied to a full wave bridge). This supplies approx. 2600 volts
DC to the 3CPX800-A7 anode. Metering of the tube anode and grid
current is accomplished by shunt resistors located in the negative
return of the 3CPX800-A7 cathode. Plate voltage metering is
accomplished by a resistor multiplier network in the B+ line of the high
voltage circuit.