Multi-channel wave receiver

Claim 2

A television signal receiving circuit comprising: a VHF tuner including a first resonant circuit, means for coupling an RF signal to said first resonant circuit, an RF amplifier circuit coupled to an output of said first resonant circuit, a second resonant circuit coupled to an output of said RF amplifier circuit, a mixer, an oscillator having a third resonant circuit, means for supplying the outputs of said oscillator and said second resonant circuit to said mixer, a UHF tuner having an IF output coupled to said mixer, each of said resonant circuits having a variable capacitance with means for coupling a tuning voltage thereto, means within each of said resonant circuits for switching between a low and a high frequency band, wherein said means for switching between a low and a high band comprises a switching diode, first and second portions of said resonant circuit being coupled and decoupled by said switching diode, and an impedance connected to the output of said UHF tuner, a diode in shunt with said impedance, and means for forward biasing said diode during VHF reception to isolate the UHF tuner from the VHF tuner.

Claim 3

In a television receiver, a mixer for converting an RF signal into an IF signal, a local oscillator, said local oscillator having a resonant circuit means, said oscillator having a variable capacitance and switching means for tuning said resonant circuit between a low and a high frequency band, means for coupling a first signal from said oscillator to said mixer independently of the state of said switching means, means for coupling a second signal from said oscillator to said mixer only when said switching means is in a predetermined state, a capacitor coupling said first signal to said mixer, said capacitor having a value to pass said oscillator signal at said low frequency band, a further capacitor provided to couple the second signal to the mixer and wherein said further capacitor is sufficiently small to provide a large impedance at the low band frequency and a small impedance at the high band frequency.

Claim 4

In a television receiver, a mixer for converting an RF signal into an IF signal, a local oscillator, said local oscillator having a resonant circuit means, said oscillator having a variable capacitance and switching means for tuning said resonant circuit between a low and a high frequency band, means for coupling a first signal from said oscillator to said mixer independently of the state of said switching means, means for coupling a second signal from said oscillator to said mixer only when said switching means is in a predetermined state, a capacitor coupling said first signal to said mixer, said capacitor having a value to pass said oscillator signal at said low frequency band, a further capacitor provided to couple the second signal to the mixer and wherein said further capacitor is sufficiently small to provide a large impedance at the low band frequency and a small impedance at the high band frequency.

Claim 5

A television receiving circuit for a VHF-UHF receiver comprising: a VHF filter circuit receiving the VHF signal, a tunable preselector having a tunable circuit receiving the output of said VHF filter circuit, a first voltage variable capacitor in said tunable circuit of said preselector, a first switching diode in said tunable preselector and forward biased at the high frequency band of VHF and at the UHF frequency band, a first inductor and first capacitor connected in circuit when said first switching diode is forward biased, an RF amplifier receiving the output of said tunable preselector, an RF signal tuning circuit receiving the output of said RF amplifier and including first and second resonant circuits coupled together, a second voltage variable capacitor in said signal tuning circuit, a second switching diode in said first resonant circuit and forward biased at the high end of the VHF band, a second capacitor and a first resistor connected in series and across said second switching diode, a third voltage variable capacitor in said second resonant circuit, a third switching diode in said signal tuning circuit and forward biased at the high end of the VHF band, a third capacitor and a second resistor connected in series and across said third switching diode, a UHF tuner supplying an input to said signal tuning circuit, a fourTh switching diode connected between ground and the input to said signal tuning circuit of said UHF tuner and forward biased during VHF operation, a mixer receiving the output of said signal tuning circuits, a local oscillator having a resonant circuit and supplying input to said mixer, a fourth voltage variable capacitor in said resonant circuit of said oscillator, a pair of output paths between said local oscillator and said mixer, and a fifth switching diode connected in one of said output paths of said local oscillator and forward biased at the high frequency end of the VHF band and at the UHF band.

Claim 6

A television receiving circuit for a VHF-UHF receiver comprising: a VHF filter circuit receiving the VHF signal, a tunable preselector having a tunable circuit receiving the output of said VHF filter circuit, a first voltage variable capacitor in said tunable circuit of said preselector, a first switching diode in said tunable preselector and forward biased at the high frequency band of VHF and at the UHF frequency band, a first inductor and first capacitor connected in circuit when said first switching diode is forward biased, an RF amplifier receiving the output of said tunable preselector, an RF signal tuning circuit receiving the output of said RF amplifier and including first and second resonant circuits coupled together, a second voltage variable capacitor in said signal tuning circuit, a second switching diode in said first resonant circuit and forward biased at the high end of the VHF band, a second capacitor and a first resistor connected in series and across said second switching diode, a third voltage variable capacitor in said second resonant circuit, a third switching diode in said signal tuning circuit and forward biased at the high end of the VHF band, a third capacitor and a second resistor connected in series and across said third switching diode, a UHF tuner supplying an input to said signal tuning circuit, a fourTh switching diode connected between ground and the input to said signal tuning circuit of said UHF tuner and forward biased during VHF operation, a mixer receiving the output of said signal tuning circuits, a local oscillator having a resonant circuit and supplying input to said mixer, a fourth voltage variable capacitor in said resonant circuit of said oscillator, a pair of output paths between said local oscillator and said mixer, and a fifth switching diode connected in one of said output paths of said local oscillator and forward biased at the high frequency end of the VHF band and at the UHF band.