In Parts 1 and 2 of this series, we discussed many things: the standby power supply, main power supply, horizontal and vertical deflection circuits, degaussing, and tuners. In Part 3 of this series, we will discuss the IF (Intermediate Frequency), AGC (Automatic Gain Control), sound IF, sound amplification, and the remote control circuits of the basic television set. IF (Intermediate Frequency) Circuits The most important feature of the IF amplifier is selectivity. Selectivity is the process of allowing only the desired frequencies to pass, while rejecting all others. There will be about three or four separate amplifier stages in a color TV IF circuit. By amplifying the signal in stages, the amounts of distortion in the IF signal waveform are reduced. The IF stages of a color TV set are fixed-tuned to a single IF frequency. Both the video and audio IF signals travel together through the IF amplifiers. The IF amplifiers need to have a bandwidth of at least 4.5 MHz, if amplification stages range from 41 MHz to 46 MHz. Traps through the circuits are used to attenuate transmission of the video carrier of the next higher channel, sound carrier of the current channel, and the sound carrier...