| 摘要 |
PROBLEM TO BE SOLVED: To prevent the breakdown of a power amplifier by preventing the application of the voltage of a power supply on the power amplifier when a control terminal is not connected to a connecting electrode by the occurrence of defective solder connection and when the specified negative voltage is not applied on the control terminal of the power amplifier. SOLUTION: A first connecting electrode 2d1, which is connected to a voltage output terminal 3a of a rectifying circuit 3, and a second connecting electrode 2d2, which is connected to a control terminal 4c of a protecting circuit 4, are arranged on a printed board 2 in close proximity. One control terminal 1d of a power amplifier 1 is mounted on the first connecting electrode 2d1 and the second connecting electrode 2d2 and connected by soldering. The power amplifier 1 is attached on the printed board 2.
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