VTR tuner assembly with rejection of modulator harmonics in tuner channel

摘要

Low pass filters 18 and 19 are inserted before the mixers 12,15 in the UHF and VHF receiver channels in a video tape recorder tuner. The filters reject harmonics emanating from the modulation carrier signal generator 9, which is enclosed in the same metal housing as the receiver circuits. The filters are added because the harmonics from the modulation carrier signal generator 9 can mix with local oscillator 13,16 harmonics to produce interfering modulation products in the desired signal frequency band.The filters may be of m-derived type or may be constant-k T,L or Pi sections.