Frequency-modulated broadcast transmitter for 88-108 megacycles

A description of a crystal controlled, reactor-valve modulated f.m. transmitter of conventional design. The unit can provide r.f. output powers of 1, 3, 10, 20 or 50 kW in the range 88-108 Mc/s. Particular attention is paid to the "Frequematic" modulator unit by means of which the subdivided frequencies from a master crystal oscillator and from the modulated oscillator are fed into a phase detector. In the case of frequency drift of the free oscillator, this develops an out-of-phase voltage which is applied to the reactor valve to correct the frequency drift. Suitable arrangement is made to prevent the device's cancelling out the frequency modulation.