Self-oscillating mixer circuit

DETAILED DESCRIPTION What is claimed is: 1.
A self:oscillating mixer circuit comprising: a first input terminal; a first switching diode connected to said first input terminal at one end thereof; a self-oscillating mixing transistor connected at its emitter to the other end of said first switching diode and grounded at its base; a feedback circuit for oscillation connected between the collector of said transistor and said one end of the first switching diode; an intermediate frequency damping circuit connected between said input terminal and ground; a second input terminal connected to said other end of the first switching diode; a first bias voltage source connected to said one end of the first switching diode, for rendering said first switching diode conductive and nonconductive; means for rendering said first switching diode conductive by applying a voltage of said first bias voltage source to said first switching diode so as to allow said transistor to effect a self-oscillating mixing operation; and means for rendering said first switching diode nonconductive by changing the voltage of said first bias voltage source applied to said first switching diode, and disconnecting said oscillation feedback circuit and said intermediate frequency damping circuit from the emitter of said transistor so as to allow said transistor to effect an intermediate frequency amplifier operation.
2.
A self-oscillating mixer circuit according to claim 1, wherein the voltage of said first bias voltage source is applied to the base of said transistor through a resistor when said switching diode is in a conductive state, and the base voltage of said transistor operating as a self-oscillating mixer is changed in the intermediate frequency amplifier operation thereof.
3.
A self-oscillating mixer circuit according to claim 1, wherein said circuit further comprises a bias voltage source for changing over a frequency band, a second switching diode, a swtiching circuit with a series-connected resistor, and means for connecting said bias voltage source and the base of said transistor to said swtiching circuit, whereby the bias voltage applied to said transistor is changed from a first voltage level for high band reception to a second voltage level for low band reception so as to provide an optimim and stable oscillating mixing operation for said high and low band reception