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3. 发明专利

JPS5870617A UHF ELECTRONIC TUNER 失效
公开(公告)号：JPS5870617A
公开(公告)日：1983-04-27
申请号：JP16866981
申请日：1981-10-23
申请人： HITACHI LTD
发明人： ASABA YOUJI , KANAI FUMIO , SHINAGAWA MITSUHISA
IPC分类号： H03J3/22 , H03J3/28 , H03J3/30
摘要： PURPOSE:To obtain an excellent tracking, by using a 1/2lambda resonance circuit for a local oscillation circuit of a UHF tuner using a varactor diode, and using a two-point tuning circuit for a high frequency tuning circuit, and providing a parallel resonance coil for a tuning diode. CONSTITUTION:A 1/2lambda resonance circuit is used as a local oscillation circuit, and a two-point tuning circuit is employed for a high frequency tuning circuit. The frequency adjustment in the 13 CH of the high frequency tuning circuit is done with a resonance coil 9 and that in the 62 CH is performed with a resonance coil 23. The parallel resonance frequency satisfies Formula, where L1 is the inductance of the coil 9, Cs is a series additional capacitor 8, Cp is the parallel added capacitor 24 and L2 is the inductance of the coil 23. The amount of change in frequencies when the capacitor cs is changed is larger at lower frequencies and smaller at higher frequencies the same as the 1/2 resonance circuit and in actual adjustment, the capacitor Cp1 is changed by changing the inductance of the coil L2.

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