| 摘要 |
PURPOSE:To prevent damage of amplifier by setting attenuators on the front stage of the amplifier to adjust the level of signals inputted by variation of impedance on the output side. CONSTITUTION:An amplifier 12 is connected on the output side of the high-frequency oscillator 10 through a circulator 13 and a continuously variable type attenuator 19, and a measuring transistor 18 and an output voltmeter 17 are connected to the output side of the amplifier 12 through a directional coupling 14. If input side of the TR18 is short-circuited, load impedance against the amplifier 12 becomes small and amplifier may be broken because the maximum output power exceeds the tolerance. In this case, attenuation is controlled by the attenuator 19 by using the negative feedback loop NF1 so that the maximum output power does not exceed the tolerance. Therefore, by this constitution, damage of amplifier can be prevented. |
