| 摘要 |
PURPOSE:To make the tracking error frequency zero over the entire reception band by controlling the voltage of a varactor diode of an RF amplifier circuit and a local oscillation circuit so as to maximize the output of a signal meter by a microcomputer. CONSTITUTION:The signal inputted to an antenna 1 is fed to a tuning coil via an amplification transistor (TR) and an AGC TR 4. A control voltage is applied to the varactor diodes 6, 9 of the secondary side of the tuning coil 2 from the microcomputer 31. A signal from an RF amplifier circuit 13 is inputted to a mixing circuit 22 via a tuning coil 23 and a capacitor 24. A signal meter 32 outputs an output in response to the electric field of a reception signal to the microcomputer 31, which varies the control voltage of the varactor diodes 6, 9, 17 of the RF amplifier circuit 21 and the local oscillator circuit 21 so as to maximize the output of the signal meter 32.
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