The circuit we present below, obtained from an old publication of the 1960s, consists of a reference oscillator that generates a frequency of 100 kHz given by a crystal.
Two pentode tubes are used and should be supplied with a voltage of 250 V from an external source. This source should also supply the filament voltages to the valves.
The circuit generates a sinusoidal signal of excellent quality and there is a neon lamp indicating operation and also stabilizing for the circuit.
Pinning of the valves must be obtained from one of the manuals that are available for download in the tubes section. In it we also have suggestions of sources to power this circuit.
In figure 1 the complete diagram of the oscillator.