Uhf electronic tuning receiver


PURPOSE:To improve the image suppressing ratio over the entire receiving range, by providing an image trap where the frequency is shifted together with a tuning frequency to an interstage coupling circuit. CONSTITUTION:A UHF electric tuner is constituted with a high-frequency amplifier circuit 3, the interstage coupling circuit 5 and a mixing circuit 7. The interstage coupling circuit 5 is provided with a resonance circuit comprising a capacitor 53, a coaxial resonance line 5 and a resonance frequency varying varactor diode 59. A coupling loop 57 leads a signal of the resonance circuit to the mixing circuit 7. The image frequency is synthesized at an opposite phase by coupling a coupling loop 7 and an input section of the resonance line 55 with a capacitor 50 in the electronic tuner constituted like this. Since the trap frequency through the constitution changes in follow-up to the change in the tuning frequency, the image frequency is improved over the entire receiving band of UHF.




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    JP-H07307680-ANovember 21, 1995Sumida Denki Kk, スミダ電機株式会社イメージ信号抑圧回路