Abstract: A fault-tolerant control system facilitates the closed loop control of a magnetron. The control system includes a transformer assembly for applying peak current to a magnetron, a pulse-forming network that conditions a transmit pulse, and a control circuit for adjusting the peak current applied to the magnetron. The control circuit includes a sample and hold circuit for comparing a signal representative of a detected peak current to a desired peak current level. The sample and hold circuit is coupled to a digital up/down counter circuit, and the output of the counter circuit is utilized to adjust the charge voltage of the pulse-forming network.

Abstract: A novel bias circuit provides precise base emitter voltage(V.sub.BE) which tracks the temperature coefficient of an RF transistor using low cost devices. The bias circuit includes a precision current source which injects current through a P-N junction device to derive a temperature compensating reference voltage thereacross. The P-N junction device is isolated from current fluctuations using a current isolation circuit coupled between the P-N junction device and the base of the RF transistor. The diode is thereby isolated from and unaffected by changes in the base current of the RF transistor. Multiple RF transistors are biased from the single P-N junction device by replicating only a trimming potentiometer and the current isolation circuitry for each additional RF transistor to be biased.