| 摘要 |
PURPOSE:To improve the cross modulation characteristics at multichannel signal reception, by providing a plurality of tuning selection circuits at the pre-stage of the 1st mixer and a plurality of amplifiers amplifying the frequency bands. CONSTITUTION:When a channel in a low band VHF band is received, a control circuit 21 applies a tuning voltage to a tuning selection circuit 14 and a control voltage to a voltage controlled oscillator 5 with a signal from an external signal supplying terminals 23. The tuning selection circuit 14 tunes and selects a desired reception frequency signal from a TV signal in VHF band inputted to an input terminal 12. The reception frequency signal tuned and selected is set to a suitable level with a signal from an automatic gain control terminal 22 at a low band VHF amplifier 17 and is applied to the 1st mixer 4 through a switching circuit 20. The signal of the voltage controlled oscillator 5 has a specific frequency inherent to the tuned and selected channel, and it is mixed with the signal from the switcher 20 at the 1st mixer 4 to convert the reception frequency to the 1st intermediate frequency. The others are the same as conventional constitution. |
