| 摘要 |
PURPOSE:To prevent the suppression of the titled AGC circuit due to a press signal by turning on a transistor (TR) connected in parallel with an output capacitor of a rectifier circuit of a transmission voice amplifier by means of a pulse being a differentiated press signal so as to short-circuit the capacitor. CONSTITUTION:An amplifier A1 of a voice band amplifies the input from a microphone or the like to a required level. A resistor (R) 1 and a FETQ1 constitute a variable attenuator and the attenuation of the signal is changed by a bias voltage. A TR Q2, capacitors (C)5-C8, diodes (CR)1-CR4 and resistors R5-R10 constitute a full wave rectifier circuit. The TR Q3, R12, C11 short- circuit the C8 to grown by using a pulse being a differentiated press signal at the start of press operation. Thus, the suppression of the AGC circuit is prevented due to the press signal.
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