| 摘要 |
PURPOSE:To eliminate deviation of tracking by devising the titled circuit such that an input signal flowing to an input coil and a suppressing coil of an AGC circuit of a tuning circuit employing a varactor diode are varied relatively so as to eliminate the deviation of a tuning point at a strong electric field. CONSTITUTION:The input coil L1 and the suppression coil L3 of a magnetic circuit 1 of a closed magnetic path are connected in common to an external antenna 2. Then a channel voltage V is impressed to the varactor diode 5 connected to the tuning coil L2. When an input radio wave is weak, the input signal from the antenna 2 flows to the coil L1 only and given to the coil L2 without being attenuated. When an input radio wave becomes strong, the input signal flowing to the coil L1 is decreased, while the input signal flowing to the coil L3 is increased alike a seesaw. Since the coils L1 and L3 have the same phase relation, the magnetic flux by the input signal flowing to the coil L1 attended with the input signal increased is suppressed by the input signal flowing to the coil L3 and the delivered energy is attenuated.
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