| 摘要 |
PURPOSE:To improve a control effect on the image interference, the leakage of an output from a station and the multiwave interference by providing a filter part having band pass characteristic consisting of a high pass filter, an amplifier, and a low pass filter. CONSTITUTION:The high pass filter 20 is provided in a front state of the first IF amplifier 12 and the low pass filter 21 is provided in a back stage thereof, which are respectively constituted by a concentrated constant. They constitute the filter part having the band pass characteristic as a whole. The respective filters 20, 21 have tunable forms in which a cut off frequency is changed accord ing to a receiving frequency. At the back part of the filter 21, the first IF amplifier 23 of the second stage is disposed, a fixed high pass filter 22 is dis posed at the front stage thereof, and a fixed low pass filter 24 is disposed at the rear stage, respectively. According to this constitution, the band pass characteristic becomes substantially a narrower band than a receiving band and a steep characteristic outside the band is obtained, and the control effect on the image interference, the leakage of the output from the station and the multiwave interference can be improved.
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