Crystal oscillator with a 6A6 (T437E)

We found this circuit with the 6A6 double triode in a 1938 Radio Handbook. The power source is not provided.

TTL Oscillator (CB6150E)
This oscillator can generate 2 to 10 MHz signals and was found in an American 1980s documentation. The...
Testing Diodes with the Oscilloscope (CB1488E )
The figure shows how to use an oscilloscope for diode test. The circuit presents the...
Balanced Modulator (CB4191E)
This circuit is intended for SSB transmission by generating two sideband signals with the carrier...