The following partial schematic describes all of the necessary power to operate only the cavity itself.
Even though the DC voltages are described in reference to the chassis, none of the connections go to the chassis here. That will happen later in the RF deck.
I used the transformers I had on hand; if you have something that has all of the necessary windings on one unit, so much the better. The full schematic .PDF file here lists all of the necessary power needed for the complete amplifier.
Note that the screen voltage is derived from the half-voltage point of the voltage doubler. I did this to eliminate the need for a separate screen supply.
The zener diode serves 2 purposes here: