| 摘要 |
To provide a picture intermediate frequency circuit capable of preventing the occurrence of intermodulation beats in a strong electrical field, without affecting in any way the original picture signal. A picture intermediate frequency signal output from the tuner 2 is supplied to a pre-amplifier 5 via an adjacent sound trap circuit 3, and a picture trap circuit 11 and 12, both of which are connected in series. Trap circuits 11 and 12 each have an attenuation point in the upper and lower frequency components equivalent to the frequency difference of the adjacent picture signal frequency with respect to the picture intermediate frequency signal, and trap the ~ 6MHz frequency components of the picture intermediate frequency signal. This allows the trap circuits 11 and 12 to previously remove unnecessary adjacent picture signals before they reach the pre-amplifier 5. As a result, the high frequency component generated in the non-linear region of the pre-amplifier 5 in a strong electrical field is prevented from interfering with the high frequency component of the unnecessary adjacent picture signals to produce cross-modulation signals, thus eliminating the occurrence of cross-modulation beats.
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