UP AND DOWN CONVERTER FOR CABLE TELEVISION

PURPOSE:To prevent beat disturbance between the 1st and the 2nd oscillation frequency signals by providing partitioned chambers for an input filter circuit and a mixer between a partitioned chamber for an amplifier for the 1st local oscillation frequency signal and partitioned chambers for the 1st and the 2nd tuning circuits. CONSTITUTION:The 2nd-stage partitioned chamber 30f for the amplifier 14, partitioned chambers 30i and 30j for the 1st multiple-tuned circuit 21, and partitioned chambers 30l and 30m for the 2nd multiple-tuned circuit 23 are isolated from one another by partitioned chambers 30c and 30g, and the amplifier 14 and the 1st multiple-tuned circuit 23 are at mutually diagonal positions. Therefore, the local oscillation frequency signal of the 1st local oscillator 13 is supplied from the amplifier 14 to the 1st mixer 12, and even if it leaks from the 1st mixer 12 to the 1st multiple-tuned circuit 21, this local oscillation frequency signal is attenuated by the 1st multiple-tuned circuit 21 and the 2nd multiple-tuned circuit 23 so that almost no signal flows in the 2nd mixing circuit 24 and the 2nd local oscillator 25. Consequently, the local oscillation frequency signals of the 1st local oscillator 13 and 2nd local oscillator 25 never cause beat disturbance.