An automatic output regulator for power oscillators

The paper describes a new system of automatic output regulation for induction heating oscillators. With the use of a power triode as part of the oscillator grid-resistor an oscillator is made to block whenever a negative voltage is applied to the triode grid. This grid voltage is applied for a controlled portion of each half-cycle by means of two small thyratrons whose firing angle is determined by the phase of an error signal. The error signal is derived from a tungsten lamp bridge in which the lamp is heated by part of the high-frequency output of the oscillator. This system enables an existing oscillator to be regulated without alteration of its power supply. An automatic regulator unit using the system is described. It is interchangeable between a number of oscillators of different designs installed in the exhaust section of a tube plant.