Device for frequency stabilization of microwave oscillators

A device for precision frequency setting and frequency stabilization of microwave oscillators is described, which, essentially, provides phase-look frequency control by means of a frequency meter, a frequency converter, and a synchronizer. The frequency meter consists of a high-stability 5 MHz oscillator and 10:1 or 20:1 frequency multiplier. The multiplier output signal is converted by a harmonic generator with a tunable output filter. The filtered signal from the harmonic generator and the output signal from the microwave oscillator to be stabilized combine in a mixer which puts out an intermediate-frequency signal. The latter is amplified and then fed back to the microwave oscillator through a synchronizer consisting of a phase detector and a d.c. amplifier. Two stabilitrons and a 3 kohm resistor protect the d.c. amplifier against high-voltage pulses during switching of the 50 MHz oscillator and the harmonic generator from one mode of operation to another.