| 摘要 |
PURPOSE:To surely receive the reception wave before power supply stop over a wide frequency range by supplying a voltage for AFC loop locking operation to a varactor diode of a local oscillation circuit at application of power in a radio receiver provided with an AFC loop. CONSTITUTION:At the time of application of power, a voltage rising from OV to a maximum voltage VDC is fed to an output line L1 via a leading time constant circuit 33. As a result, the voltage of the output line L1 rises from a lower limit voltage VL2 of the reception width BD up to the upper limit voltage VH2. Thus, with the AFC loop locking the reception wave of the frequency included in the reception width BD into the tuning state, if the power is lost and applied again, the AFC operation is applied so that the AFC loop locks the reception wave while the voltage of the output line L1 rises from OV to the upper limit voltage VDC via the leading time constant 33. As a result, the received high frequency S1 before power failure is locked surely and received at the time of reapplication of power.
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