Rca Licensing Corporation

William D Anderson

Max Ward Muterspaugh

A balanced mixer and output filter for television receivers and the like is presented. The mixer is followed by a fairly selective bandpass filter to protect the IF amplifiers from first and second adjacent channel signals.

Single balanced mixer with output filter

The present invention concerns apparatus for changing the effective tuning inductance with a change of frequency of a multi-band oscillator, said frequency being controlled in response to the magnitude of a tuning voltage for tuned signal amplifiers so that three point tuning can be achieved in the lowest frequency band between the signal amplifiers and the oscillator. In accord with the present invention, a reactance network is connected in series with the tuning inductor of the lowest band for tailoring the tracking of the oscillator frequency with change of tuning voltage.

Television tuner oscillator with three point tracking

In a tunable filter including first and second inductors, a varactor diode, and a bandswitching diode connected intermediate the inductors to select the inductor configuration for first and second tuning bands, a capacitor is connected in parallel with the bandswitching diode. When the bandswitching diode is in the high impedance 'non-conducting' state, the capacitor is functionally connected with other elements of the tunable filter for purposes such as trapping or tracking. When the bandswitching diode is in the low impedance 'non-conducting' state, the capacitance is functionally disconnected from the tunable circuit.

Growing community of inventors

Fox River Grove, IL, United States of America

William D Anderson