Abstract: A microwave oven includes an inverter inducing a high frequency oscillating current at a primary winding of a transformer via a switching element turned on and off, a magnetron to which a high voltage is applied by the transformer, a temperature sensor sensing the temperature of heat generated by the switching element to thereby generate a temperature signal, and a microcomputer compensating "on" and "off" periods of the switching element in response to the temperature signal from the temperature sensor so that an increase in an amount of an anode current in the magnetron is restrained with an increase of the temperature sensed by the temperature sensor. The microcomputer also functions to deenergize the switching element when the temperature of the switching element sensed by the temperature sensor exceeds a predetermined value.

Abstract: A high frequency heating apparatus includes a high frequency heating source for outputting a predetermined maximum rated high frequency output. An inverter circuit receives an AC input and supplies a predetermined high frequency drive power to the high frequency heating source. A switch manually changes and outputs a plurality of rated consumption power change signals including at least two levels corresponding to the maximum rated high frequency output of the high frequency heating source and at least one high frequency output lower than the maximum rated high frequency output, associated with a rated consumption power of the apparatus. A controller controls the high frequency drive power from the inverter circuit in accordance with the rated consumption change signal from the switch. The high frequency output from the high frequency heating source and the rated consumption power of the apparatus are linearly, variably set in accordance with the rated consumption power change signal.

Abstract: A microwave oven having a magnetron whose output level may be varied from 100% down to 0% of full magnetron power by a control section including an inverter circuit. The control section controls the output of the magnetron by varying the duration of first output pulses coupled to the inverter circuit in a first "regular" output range of the magnetron from 100% down to a predetermined % of full magnetron power and also controls magnetron output by intermittently supplying second output pulses to the inverter circuit in a second "low" output range from the predetermined power % down to substantially 0% of full power.