A Simple Crystal Discriminator for FM Oscillator Stabilization

A crystal discriminator employing only one quartz crystal and very simple in adjustment is described in detail. The stability of center frequency determination in the presence of frequency modulation and variation of component values is calculated in terms of the circuit parameters, and is shown to be adequate for the requirements of broadcast transmitters. Experimental measurements confirm the results of the theoretical analysis. The discriminator was designed for use in a television aural transmitter, and a brief description is given of the complete FM exciter unit.