This crystal Hartley oscillator to be used as a calibrator is from a Radio Craft from November 1947. The circuit is mains powered with a transformerless source. The frequency of 100 kHz is given by the crystal.

This crystal Hartley oscillator to be used as a calibrator is from a Radio Craft from November 1947. The circuit is mains powered with a transformerless source. The frequency of 100 kHz is given by the crystal.