Abstract: Automatic frequency control (AFC) circuitry compensating for the nonlinear tuning voltage sensitivity characteristics of voltage-controlled tuners is shown. The circuit uses a nonlinear device, such as a zener diode, to develop an amount of error correction voltage that increases with increasing tuning voltage. In addition, through the use of a VHF Bandswitch voltage, the circuit controls an impedance in a network that combines the tuning voltage with the voltage developed by the AFC system in response to tuning errors. As a result, a greater amount of AFC error correction voltage is developed on Low Band VHF channels than on High Band channels. In this manner, substantially constant AFC pull-in range is maintained both within and among High and Low Band VHF and UHF channels.

Abstract: Circuitry compensating for inherent nonlinearities in the tuning voltage sensitivity of varactor tuners, thereby providing relatively constant AFC pull-in range throughout the band of operating frequencies, is shown. In both the VHF and UHF bands, the AFC system develops an error correction voltage in proportion to the tuning voltage. With respect to reception of VHF channels, a gain switching circuit operates to reduce the proportion of AFC error correction voltage developed on a High Band VHF channel, thereby compensating for increased tuning voltage sensitivity on High Band VHF. With respect to reception of UHF channels, a tuning voltage sensing circuit operates to effect an error correction voltage that is a greater proportion of the tuning voltage when the tuning voltage is above a pre-determined value corresponding to approximately channel 60.

Abstract: A temperature sensor holding device for electronic apparatus includes a plate member having an aperture for receiving a heat generating semi-conductor and formed for attachment to a heat sink, a spacer member fastened to the plate member and formed to telescope over the heat generating semi-conductor, and a cover member formed for attachment to the spacer and plate members and having a cut out portion on the inner surface thereof for receiving a temperature sensor device.

Abstract: A DC controlled amplifier is used to control the chrominance gain, and hence the color saturation, of a television receiver. The voltage on the wiper of a Color Control variable resistor and the output of an Automatic Color Level (ACL) detector are combined in a summing network to provide a DC voltage to the controlled amplifier. The ACL detector develops an output voltage that tends to maintain the peak-to-peak chrominance signal, and therefore the color saturation, at or below a threshold level. A control tracking circuit varies the threshold level in accordance with the voltage on the wiper of the color control variable resistor, thereby maintaining the dynamic range of the Automatic Color Level Control System relatively independent of the setting of the Color Control.

Abstract: A receiver incorporating a phase-locked loop to demodulate a signal comprising a plurality of distinct baseband components is disclosed. The loop filter circuit includes an adjustable resistive element for varying the loop damping factor, thereby providing optimum separation of the baseband components. In addition, the loop filter circuit provides a bandpass high-frequency noise output to a noise-activated muting circuit.