Abstract: The power supply for an airborne pulse radar includes an unfiltered source of 400 cycle AC power connected to a full wave rectifying circuit including two diodes associated with each phase of the three phase input circuit. In addition, three SCR's are employed for controlling the operation of the rectifiers. During normal operation of the pulse magnetron power supply, the control electrodes of the SCR's are biased to the conducting or enabled state by a small floating DC voltage which is obtained from a small DC power source which includes a rectifier circuit connected to the floating secondary of a low voltage transformer. When a fault is sensed in the magnetron pulse circuitry as indicated by the drawing of excessive current, a switching circuit is activated which removes the enabling voltage across the SCR's, so that the input rectifier circuitry is disabled, thus preventing burn-out of components included in the pulse generation circuitry.