are supplied supplies a gate power at a predetermined output voltage to the rf circuit 421 the second discharge circuit 509 constitutes a part of the third power supply control means described in u201c summary of the invention u201d and has a function for short circuiting the drain power line for rf and gnd terminal at the time of the on operation and discharging the drain power line for rf the second discharge circuit 509 is controlled in the on off operation by the control signal from the rf drain power source control circuit 511 of the power supply control amp monitoring circuit 422 namely the second discharge circuit 509 is operated so as to turn off when a signal for turning on the gate power supply 508 for rf is outputted from the drain power source control circuit 501 for rf and operated so as to turn on when a signal for turning off the gate power supply 508 for rf is outputted the second discharge circuit 509 prevents the gate power supply from shutting off when some charge remains in the drain circuit the power source control amp monitoring circuit 422 has the first timer circuit 510 a second timer circuit 512 an analog 5v monitoring circuit 513 an analog u2212 5v monitoring circuit 514 a vin monitoring circuit 515 a 3 3v.