| 摘要 |
PURPOSE: A UHF input circuit using an HPF(high pass filter) is provided to exclude the influence of VHF signals on an UHF input tuner to improve UHF/VHF rejection characteristics. CONSTITUTION: Input UHF/VHF band signals pass through an HPF(11) formed of capacitors(C1,C2) and an inductor(L3) and using 40MHz as cut-off frequency to filter frequency less than 40MHz. An IF trap circuit(12) is connected in parallel to an inductor(L1) and the capacitor(C1). A citizen band trap circuit(13) is connected in parallel to an inductor(L2) and capacitor(C2). Therefore, the UHF/VHF band signals passed through the HPF(11), IF trap circuit(12) and citizen band trap circuit(13) have IF trap characteristics and citizen band trap characteristics, and are respectively output to a UHF input tuner and a VHF input tuner.
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