AGC voltage is applied to the:

The AGC voltage is fed back to the radio frequency (RF) and intermediate frequency (IF) amplifier stages of a receiver. By reducing the gain of these early stages when a strong signal is present, the receiver prevents overload and distortion in the detector and subsequent audio stages. Applying AGC to the audio frequency (AF) amplifiers is incorrect because the primary goal of AGC is to control the signal level before it gets demodulated. If strong signals were allowed to reach the detector unattenuated, the signal would distort regardless of any AF adjustments.