PURPOSE: To lower the oscillation frequency of the local oscillation circuit without lowering the frequency of the 1st IF signal by applying the local oscillation signal obtained by mixing up the oscillation signals of the 1st and 2nd local oscillation circuits to the 1st mixer circuit.
CONSTITUTION: At the VHF reception time, the oscillation signal of 2nd local oscillation circuit 37 is applied to 3rd mixer circuit 34, and the local oscillation signal obtained through the frequency piling between the oscillation signals of circuit 37 and 1st local oscillation circuit 33 is applied to 1st mixer circuit 28 to generate the 1st IF signal. This IF signal is applied to 2nd mixer circuit 30 to obtain the 2nd IF signal through the subtraction between the 1st IF signal and the local oscillation signal obtained by giving the double frequency via doubler circuit 39 to the oscillation signal of circuit 37. At the UHF reception time, the 1st IF signal is obtained in the form of the sum of the oscillation signal of circuit 33 and the local oscillation signal obtained through the difference of the frequency between the signals sent from circuit 39.
FUJIMOTO ISAO