| 摘要 |
PURPOSE:To set an output level in a range sufficiently wider than the operation level range of a detector and to make a detector input level constant to reduce the temperature fluctuation, by providing a variable attenuator between a coupling circuit and the detector to change the attenuation quantity in accordance with the output set level. CONSTITUTION:A part of the output of an amplifier 3 is taken out by a coupling circuit 5 and is inputted to a detector 6 through a variable attenuator 11. The output of the detector is compared with a reference voltage and is amplified in 7 and is applied to a variable attenuator 2. By this constitution, since the input level of the detector 6 is held in a narrow range when the attenuation quantity of the variable attenuator 11 is changed in accordance with the output set level of a terminal 9, the output level is set in a range wider than operation level range of the detector 6. By making the detector input level constant, temperature fluctuation is made slight. |
