Abstract: A termination/attenuation network applies to an input of a set-top box a MOCA channel signal having a narrow band of frequencies and included in RF signals having a wide band of frequencies received via a cable from a satellite antenna. The network includes a pair of series resistors and a parallel resistor coupled to a junction terminal between the pair of series resistors in a T-shaped configuration. A series-pass band-pass filter (L1, C2) bypasses the pair of series resistors and a parallel band stop filter (L2, C1) decouples the parallel resistor at the frequency band of the MOCA channel signal for selectively reducing attenuation at the frequency band of the MOCA channel signal.

Abstract: A termination/attenuation network applies to an input of a set-top box a MOCA channel signal having a narrow band of frequencies and included in RF signals having a wide band of frequencies received via a cable from a satellite antenna. The network includes a pair of series resistors and a parallel resistor coupled to a junction terminal between the pair of series resistors in a T-shaped configuration. A series-pass band-pass filter (L1, C2) bypasses the pair of series resistors and a parallel band stop filter (L2, C1) decouples the parallel resistor at the frequency band of the MOCA channel signal for selectively reducing attenuation at the frequency band of the MOCA channel signal.

Abstract: An F connector coupled to a transmission line applies a radio frequency (RF) signal to an RF input of a filter of a set-top box via an impedance matching network that includes a first inductor and a second inductor that are coupled in series. A capacitor and a third inductor are coupled in parallel between a discharge tube and a junction terminal that is interposed between the series coupled inductors for protecting electronic components such as the filter from a voltage surge developed in the transmission line.

Abstract: An F connector coupled to a transmission line applies a radio frequency (RF) signal to an RF input of a filter of a set-top box via an impedance matching network that includes a first inductor and a second inductor that are coupled in series. A capacitor and a third inductor are coupled in parallel between a discharge tube and a junction terminal that is interposed between the series coupled inductors for protecting electronic components such as the filter from a voltage surge developed in the transmission line.

Abstract: A voltage regulator is switchable between a lower regulated DC output voltage and a higher regulated DC output voltage. Foldback current limiting is actuated in response to the current drawn by the load when a current limiting threshold is exceeded. The current limiting threshold is determined by the voltage relationship at respective taps of a pair of voltage dividers, with said relationship being effected by the voltage appearing across a current sensing resistor coupled in series with the load. The current limiting threshold is adjusted to be approximately the same for both the lower and the higher regulated DC output voltages. This adjustment is accomplished with a non-linear voltage dependent device, which is coupled to one of the voltage dividers, and is actuated in the higher output voltage mode.

Abstract: The present invention concerns a voltage regulator wherein the series pass transistor and an amplification transistor are of complementary types. Supply current flows from the DC supply source through the emitter-collector path of the series pass transistor to the load. The amount of this current is controlled by a negative feedback control signal coupled from the regulated output voltage to the base electrode of the amplification transistor, which in turn drives the base of the series pass transistor. The emitter electrode of the amplification transistor is coupled to a voltage which is less than the regulated DC output voltage so that drive requirements for the pair of transistors is reduced.

Abstract: 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.

Abstract: An RF signal input circuit for a UHF tuner of a television receiver comprises a series-tuned circuit including a varactor diode and an inductance element connected in series, in the order named, between signal ground and a gate electrode of a field-effect transistor RF amplifier. The series-tuned circuit has a relatively uniform bandwidth throughout the UHF range. A capacitor connected in shunt with the gate electrode completes a "split-capacitor" configuration in which the varactor diode and the shunt capacitor form a variable impedance transformation network for making the relationship between the effective impedances of the series-tuned circuit and FET amplifier relatively uniform throughout the UHF range. The order of the varactor diode and inductance element allows a low cost adjustable capacitor comprising a grounded shield wall as one plate and a movable tab as a second plate to be connected directly across the varactor diode.

Abstract: A unitary tuning structure of a UHF tuner includes an inductance loop, an inductance adjustment element attached to a top portion of the inductance loop so as to be foldable with respect to the inductance loop about an axis parallel to the printed circuit board to which the inductance loop is attached and a capacitance adjustment tab attached to a side portion of the inductance loop so as to be foldable with respect to the inductance loop about an axis perpendicular to the printed circuit board. In another form of the unitary tuning structure, a second inductance loop can be attached within the first loop.

Abstract: A mixer for mixing first and second signals for providing a difference signal comprises a mixing transistor. The first and second signals are applied between the base and emitter electrodes of the transistor. A non-linear impedance is coupled in series with the emitter electrode. Spurious signal components are reduced in amplitude compared with the difference signal.

Abstract: The RF stage and local oscillator stage of a tuner both include respective cascode connected dual gate field effect transistors as the amplifying device and similarly configured tuned circuits coupled to the first gate electrodes of the field effect transistors. The tracking characteristics of the tuner are enhanced due to the similar amplifier and tuned circuit configurations.

Abstract: A local oscillator is arranged in a Colpitts type configuration in which an amplifying device such as a bipolar transistor or field effect transistor having a control electrode (base or gate electrode) is coupled to a first electrode (emitter or source electrode) defining the end of a conduction channel through an oscillation conditioning network conditioning the device to oscillate in a given range and also to a frequency determining network including a first varactor diode responsive to the tuning voltage and an inductance element coupled in series between the control electrode and signal ground, and in which the output is taken at a second electrode (collector or drain) defining the other end of the conduction channel. A range extending circuit including a second varactor diode responsive to the tuning voltage is coupled between the control electrode and signal ground for ensuring that the oscillator operates reliably at both ends of the tuning range.

Abstract: A dual gate field effect transistor (FET) is configured as a self-buffering local oscillator of a tuner by arranging the FET in a cascode configuration in which the first gate electrode is coupled to the source electrode through an oscillation conditioning network and also to a frequency determining network, the second gate electrode is coupled to signal ground through a negligible impedance and the drain electrode is utilized as the output of the oscillator.

Abstract: A companding system for a television audio apparatus includes a compressor and an expander for stereo difference or second audio program signals. The compressor provides variable preemphasis of high frequency signal components and the expander provides complementary variable deemphasis. Due to noise, the amount of deemphasis the expander can provide is limited. To ensure complementary operation of the compressor and expander a clamp means is used in the compressor to set the maximum amount of preemphasis. Similarly, in the expander, a clamp is used to set the maximum deemphasis of the compressor.

Abstract: A multiplier for multiplying the modulated sound and picture carriers to produce an intercarrier sound signal in a quasi-parallel sound channel of an IF section has a pair of anti-parallel connected diodes in a limiter for generating an amplitude limited version of the picture carrier. It has been discovered that the varying capacitance of the diodes with picture amplitude can cause phase shifts and hence phase modulation interference in the intercarrier signal. The latter is especially troublesome for stereo sound reproduction. To reduce such interference, a low value resistor is shunt coupled to the diodes to inhibit the capacitance variations of the diodes and resulting undesired phase modulation in the intercarrier sound signal.

Abstract: A television tuner has a tuned circuit at the input of an RF amplifier. The tuned circuit has a varactor tuned parallel circuit and an output series coil for good high frequency attenuation and constant bandwidth with changes in frequency. For good low frequency attenuation, an input series capacitance is provided comprising a pair of varactors. The varactor pair is oppositely poled to reduce frequency doubling of low frequency signals.

Abstract: A television receiver has provisions for a second audio program (SAP) and an indication for signifying when the SAP is present and a muting circuit for muting the SAP, both in response to the output signal of a SAP detector. A filter capacitor is coupled to the detector output to prevent flicker of the indicator due to noise. To prevent the filter capacitor from incorrectly maintaining an indication of the presence of a SAP, thereby preventing proper SAP muting, when a new channel is selected, channel change signal causes a semiconductor switch to discharge the filter capacitor.

Abstract: A plurality of common emitter transistor amplifiers have the output of a single operational amplifier applying an AGC signal to their bases. An input of the operational amplifier is connected to the collectors through respective diodes to isolate and to selectively form a feedback loop for the on amplifier from the off amplifier. Another input of the operational amplifier receives the AGC voltage so that the operational amplifier varies the base current and hence the gain of the common emitter transistor which is on.

Abstract: In a double conversion tuner intended to tune UHF broadcast channels as well as VHF broadcast and cable channels, the frequency range of the first intermediate signal produced by the first mixer is selected to correspond to that of UHF channel 37. The frequency range of UHF channel 37 is reserved for radio astronomy and is, therefore, not used for the broadcast of television information. The tuner includes provisions for inhibiting interference from the RF signals corresponding to channels 36 and 38 which are adjacent to channel 37 and which are used for the broadcast of television information.

Abstract: A tuning system for a receiver includes an RF filter for selecting the RF signal corresponding to a selected channel of a plurality of channels in response to a filter tuning control signal, a local oscillator for developing an oscillator signal, the frequency of which is controlled by an oscillator tuning control signal developed in response to a binary coded representation of the channel number of the selected selection, and a mixer for heterodyning the selected RF signal with the local oscillator signal to produce an IF signal. A circuit including a memory is provided for storing binary signals for controlling the modification of the oscillator tuning control signal to derive the filter tuning control signal.