Figure 22, circuit from the 1957 ARRL Radio Amateurs Handbook.
There are two terminals on the left indicating where an unregulated rectified and filtered power supply is to be connected. A legend indicates that the minimum input voltage is to be 325 volts DC. The negative input goes to common. The positive input terminal goes to the wiper of a 160 ohm pot. One end of the pot goes to one of the plates of a 6AS7/6080 twin triode tube. The other end of the pot goes to the other plate of the tube. The two cathodes are tied together and connect to the positive output terminal which is labeled 250 volts maximum output. The negative terminal of the output connects to common. We will return to the grids of the 6As7 later. The cathode of a 5651 voltage regulator tube connects to common. The anode connects through a 68 k ohm resistor to the plus 250 volt output. The anode of the 5651 also connects through a 1 meg ohm resistor to the right hand grid of a 6SL7. The right hand cathode connects through a 10 k ohm pot connected as a rheostat to common. The cathode also connects through a 12 k ohm resistor to plus 250 volts. The right hand plate connects through a 470 k ohm resistor to plus 250 volts. The right hand plate also connects to the left hand grid of the 6SL7. The left hand cathode connects through a 15 k ohm resistor to common. There is a 0.1 u f capacitor in parallel with the 15 k resistor. The left hand cathode also connects through a 12 k ohm resistor to plus 250 volts. The left hand plate connects through a 470 k ohm resistor to plus 250 volts. The left hand plate also connects to the two grids of the 6AS7 pass tube. This completes the verbal description.