Abstract: A combination UHF-VHF tuner has a switching diode placed in series with a VHF high-range peaking coil so that the coil forms a parallel resonance peaking circuit when high-range VHF signals are received and the coil acts as a series impedance matching element when a UHF IF signal is coupled from a UHF mixer stage.

Abstract: In a VHF tuner, feedback capacitance between the emitter of a local oscillating transistor and the ground in a local oscillator is changed at the low band receiving state and high band receiving state by controlling a switching diode connected in series to a capacitor for feedback capacitance and, a mixer is installed to mix the output of the local oscillator and high frequency input. For an improved mixer biasing circuit, the switching diode in series connection to the capacitor for feedback capacitance is connected to one terminal of a mixing FET in the mixer, and changing of the feedback capacitance in the local oscillator is accompanied by changing of working current of the mixing FET in the local oscillator.

Abstract: A high-frequency input circuit for two inputs has a pair of first and second pi variable attenuation circuits each composed of three P-I-N diodes, some of which are shared by both of the circuits. The P-I-N diodes serve as attenuator elements in the attenuation circuits and also as switching elements for switching between the first and second attenuation circuits.

Abstract: A printed circuit board lamination consisting of upper and lower printed circuit boards is provided with an area consisting of the sole lower printed circuit board, and a varactor diode and a resonance rod portion parallel to the lamination are arranged in this area. Thus, the length of lead of the varactor diode is reduced in effect, and also the effects of variation of the dielectric constant of the printed circuit board due to changes of the temperature thereof and relative humidity are reduced.