Pilot frequency generator with frequency multiplier - produces constant amplitude signal, and has an oscillator oscillating at a pilot harmonic

The generator comprises a frequency multiplier which converts the oscillator to pilot frequency, and delivers the latter. A control signal circuit detects the pilot signal amplitude changes and maintains it constant by a signal delivered to the frequency multiplier. The frequency multiplier has a harmonics generating amplifier, whose working point and/or gain are changed by the above control signal. The amplifier is followed by a filter passing the pilot frequency. The amplifier has a transistor generating the harmonics, to whose base a d.c. control signal is applied in order to control its working point. The filter is a cavity resonator bandpass filter.