| 摘要 |
PURPOSE:To obtain a stable overload preventing circuit by interrupting a power supply circuit when a power value extracted by a progressive wave component extracting circuit and a reflected wave component extracting circuit and a high frequency power calculated by a supply power exceed a set value. CONSTITUTION:The high frequency power 2 applied from an exciting device of a pre-stage is amplified by a trnasistor (TR) 1 and reaches an output terminal 5 through a tuning circuit 4. The high frequency output of the progressive power extracting device 6 and the reflected wave power extracting device 7 is converted into a DC voltage at detectors 8, 9 and applied to an adder 12 via a coupling resistor 11. The DC voltage drop of a resistor 10 corresponding to the power supply input power is applied to the adder 12 via the coupler 11. A value adding the reflected wave power to the power supply input power and subtrated by the propressive wave power therefrom is outputted from the adder 12. This value is the power loss in the TR1, and when the loss exceeds the set value of a voltage adjuster 14, a relay 15 is operated and the power supply circuit is interrupted. |
