Matsushita Electric Industrial Co., Ltd.

Tsutomu Shishido

Makoto Hasegawa

Sadahiko Yamashita

Motoi Ohba

Koh Kikuchi

Yasumasa Watanabe

Disclosed is a double converter tuner having an input circuit for performing first band control with respect to an input signal, amplifying a band-controlled input signal after automatic gain control is performed, and further performing second band control of a gain-controlled signal, a first IF (intermediate frequency) converter for converting an output generated from the input circuit to a first IF signal having a higher bandwidth than the reception bandwidth of the input signal, a first IF circuit for amplifying an output from the first IF converter, performing third band control and performing a further amplification, a second IF converter for converting an output generated from the first IF circuit to a second IF signal, and a second IF circuit for amplifying an output from the second IF converter, performing fourth band control, and performing another amplification. The first and second IF converters are arranged on different circuit boards to prevent frequency interference therebetween.

Double converter tuner

A compact or miniaturized well-shielded double superheterodyne tuner is provided, wherein an input circuit portion, a first mixing portion, a first intermediate frequency bandpass filter, a second mixing portion and an output circuit portion are mounted in separated casings. The first mixing portion and the second mixing portion are provided on printed boards and each mounted on a bottom plate of the casing. The casings containing the first and second mixing portion are arranged in a manner such that grounded surfaces of the printed boards contained in the casings are arranged face to face. The casing containing the bandpass filter is contacted adjacently to a common face of the face to face casings. Each of the casings containing the input and output circuit portions is located adjacently to each of faces common to the face to face casings and the filter containing casing. Some structual improvements are also provided for simplifying the manufacture and adjustment of the tuner.

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Yokohama, Japan

Tsutomu Shishido