| 摘要 |
PURPOSE:To effectively validate an AGC to a strong input by providing a low impedance converting circuit for converting the output impedance of a wire band filter to a low value, an electronic tuning circuit for adjusting a tuning frequency by the use of a variable capacitor and the AGC circuit. CONSTITUTION:The transistor TR1 of an emitter follower converts the output impedance of the wide band filter F to the low value. The electronic tuning circuit T adjusts the tuning frequency by the use of the bur cap B to the output signal of the transistor TR1. Between the wide band filter F and the base of the transistor TR1 or the gate of an FET, the impedance is high. Namely, since the impedance at a point to which the AGC is applied is high, the AGC is effectively validated. At the time of the strong input, it is difficult to generate an intermodulation. Further, by providing the variable capacitor in an RF input means, the matching of an antenna and a receiver main body is effective to reduce a loss in a transmission.
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