| 摘要 |
PURPOSE:To attain ease of tuning at channel selection by opening a switch circuit to avoid the AFC operation when no tuning is taken. CONSTITUTION:When no tuning is taken, the switch circuit 12 is opened not to perform any AFC operation. In changing the frequency of a channel selection signal through the operation of a knob 8, a signal outputted from a mixing circuit 2 is changed sequentially. Then a tuning discrimination circuit 10 discriminates the tuning by observing an output of a demodulation circuit 4. When a prescribed time is elapsed with this state, the switch circuit 12 being in open state so far is close by the control of a timer circuit 13 and the AFC operation is attained.
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