| 摘要 |
PURPOSE:To reduce spurious radiation and to improve stability by independently separating broad-band amplifier which covers frequency bands for UHF and VHF reception and then by arranging a high-frequency filter circuit at the input side of a preamplifier independently separately. CONSTITUTION:Local oscillation output part 41 of the tuner in UHF reception is connected to the 1st input terminal 51 of the 1st filter block 43 as a mixing part. This filter block 43 consists of high-frequency cutting filter part 43a for UHF frequencies and low-frequency cutting filter part 43b for VHF frequencies. Local oscillation output part 42 of the tuner in VHF reception is connected to the input terminal of the 2nd filter block 44 as an intermediate-frequency band low-frequency cutting filter, and output terminal 55 of this filter 44 is connected to the 2nd input terminal 52 to filter block 43. Its output is inputted from output terminal 53 to prescaler circuit 46 via broad-band amplifier 45. Thus, the need for adjustments of a coil, etc., can be liminated and the spurious radiation can be reduced. |
