Description:
The NTE1174 is a monolithic TV Automatic Fine Tuning (AFT) circuit in a 14−Lead Staggered DIP type package that provides an AFT voltage and an amplified 4.5MHz intercarrier sound signal. When connected to an output of an IF amplifier the NTE1174 provides the signal processing (amplification and detection) necessary to generate the AFT correction signals required by the TV tuner. It also mixes the video and sound IF carriers and amplifiers the resultant 4.5MHz intercarrier sound signal. The sound output may then be connected to an FM detector such as the NTE1175 “TV Sound IF and Audio Output Subsystem,” or the NTE712 “FM Detector and Audio Driver.”
The AFT portion of the NTE1174 is similar the NTE 780 AFT circuit with the following exceptions: (a) the AFT filter capacitors are external and user selectable, allowing the detector to operate as a peak detector and resulting in a higher effective gain for the TV signal; (b) the detector bias resistor is external and user selectable, allowing the gain of the AFT and intercarrier signals to be adjusted; (c) the dynamic resistance of the shunt regulator has been decreased.