| 摘要 |
PROBLEM TO BE SOLVED: To stabilize with a simple configuration the receiving performance of a VHF/UHF electronic tuner the receiving performance of which has been unstable depending upon the band of input signals, because the amplifying amounts of the input signals vary depending upon the low VHF band, high VHF band, and UHF band. SOLUTION: In order to correct the amplifying amount of an electronic tuner composed of a VHF tuner circuit 1 and a UHF tuner circuit 2 in each of the low VHF band, high VHF band, and UHF band, a parallel circuit of an amplifier circuit 21 and a switching diode Di is added to the preceding stage of the electronic tuner. The diode Di is on/off-controlled by utilizing band selecting voltages BL, BH, or BU, RF-AGC voltage, or IF-AGC voltage, and when the diode Di is controlled, the amplifier circuit 21 is controlled. The circuit 21 can be added between the electronic tuner and a video intermediate frequency amplifier/detection circuit 13.
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