Automatic Frequency Control of Microwave Oscillators

A method for the automatic frequency control of any type of tunable microwave oscillator is described. In this method a servomechanism is used which includes a wave-guide discriminator circuit, a mercury-contact relay, a 60-cycle amplifier, and a small two-phase induction motor. Tests made on a preliminary model of a circuit of this type used with a 4000-megacycle oscillator showed that a stability of 1 part in 50,000 was obtainable. The manner in which such a control system may be used in a microwave repeater is described.