Zenith Electronics Corporation

Zenith Radio Corporation

Peter Strammello, Jr

Peter C Skerlos

Mark J Lachiw

A varactor diode tuner includes a tunable image frequency trap in its input circuit. The trap is part of a tunable bandpass filter and forms a tapped capacitance matching network for UHF television signal carrier frequencies and a low impedance shunt at image frequencies. The trap is formed of discrete capacitors, an inductor and a tunable varactor diode.

Image trap filter circuit

An all-channel television tuner includes a single 75 ohm input for receiving airborne signals and CATV signals. A single band high frequency section tunes frequencies from 370 to 806 MHz and a three band low frequency section tunes frequencies from 54 MHz through 370 MHz. Both sections are coupled to the 75 ohm input through signal diverting means. A channel selector provides tuning voltages and band switching voltages to the sections and to the signal diverting means as a function of the channel selected.

All-channel television tuning system

The VHF and UHF tuners of a television receiver are coupled by a switchable diplexing circuit to a single antenna input terminal. The diplexing circuit includes a first electronic switching means responsive to a U/V bandswitch control signal connected between the UHF tuner and the antenna input terminal. A switchable low-pass filter is connected between the VHF tuner and the antenna input terminal, the switchable low-pass filter including a second electronic switching means responsive to the U/V bandswitch control signal for causing the low-pass filter to exhibit a first low-pass frequency response having a cut-off frequency fc in the VHF mode and a second low-pass frequency responsive having a cut-off frequency less then fc in the UHF mode.

Switching diplexer for single antenna input television receivers

A signal splitter-balun assembly for coupling a UHF antenna and a VHF antenna to a single input terminal of a television receiver is disclosed. RF isolation is provided by means of appropriate filtering, 60 Hz isolation is provided by means by a pair of capristors, and the required impedance transformation is provided by means of a conventional balun transformer in a low cost unit utilizing a minimum number of components.

UHF/VHF Splitter-balun assembly

An extended range tunable resonant circuit for use in a VHF television receiver tuning system comprises a bandswitchable inductive network connected to a low series resistance gallium arsenide varactor diode. The resonant circuit, when operated in response to appropriate bandswitching signals and tuning voltages, is effective for establishing a plurality of tuning bands collectively defining an extended sub-UHF tuning range from about 54 MHz to at least 408 MHz.

Extended range tunable resonant circuit for a VHF television receiver

Apparatus for simultaneously controlling the operating modes of a plurality of coupled video signal processing devices is disclosed. Manually operated pushbutton selectors provide D.C. control voltages to a plurality of electronic RF switches to permit the simultaneous viewing and recording of signals from various sources such as cable TV (CATV), subscription TV decoder (STV), video record (or disc) player, etc., in any desired combination. Video signal losses due to signal splitting are avoided when viewing and recording the same input signal by means of unique cooperation between view and record manually operable selectors. Electronic diode switching circuitry controlled by a minimum number of user selectable inputs allows for a reduced number of controller components and simplified design while facilitating user operation.

Multi-component video system controller

A conventional varactor tuned VHF/UHF television tuner with additional inductors placed in parallel in each VHF tuned circuit by means of diode switching provides an additional tuning capability over the CATV Superband. Selective tuning to any broadcast channel within the VHF, UHF and CATV bands is achieved by voltage-controlled tunable circuitry such as the type employing varactor diodes responsive to an adjustable DC tuning voltage having unique levels assigned to the various desired channels. By providing an additional bandswitching input voltage to a conventional tuner, Superband coils are diode-switched in parallel with VHF tuned circuits permitting an expanded tuning frequency range. This parallel coil approach in achieving Superband coverage permits the utilization of spring-wound VHF-band and Superband coils to facilitate tuning circuit alignment and to eliminate the need for a discrete Superband tuner or a CATV converter.

Growing community of inventors

Arlington Heights, IL, United States of America

Peter Strammello, Jr