| 摘要 |
PURPOSE:To eliminate the fluctuation of a receiving level, by connecting an output side of a broad band filter and a narrow band filter connected in cascade to a common output terminal via a transistor(TR) circuit for selecting respectively broad and narrow bands. CONSTITUTION:A broad band pass filter 12 and a narrow band pass filter 14 are connected in cascade to an output side of an intermediate frequency transformer 10. Further, a broad band selecting TR circuit comprising a capacitor C1, resistors R6-R9 and R12, is provided between an output terminal of the broad band pass filter 12 and the common output terminal OUT. Further, a narrow band selecting TR circuit comprising a capacitor C2, resistors R10-R14, and the TRs19, 20 is provided between and output terminal of the narrow band pass filter 14 and the common output OUT. Moreover, the broad or narrow band selecting TR circuit is switched with a control voltage VC. |
