Final answer:
The output of an AM/CW/SSB radio receiver can be manually adjusted or automatically controlled by an AGC circuit, which maintains constant volume despite signal strength variations.
Step-by-step explanation:
The overall output of an AM/CW/SSB receiver can be adjusted by several manual controls on the receiver or by a circuit known as the AGC circuit. AGC stands for Automatic Gain Control, which helps to keep the output volume constant even when the signal strength varies. This is different from the IF amplifier, which amplifies the signal at the intermediate frequency stage, the VFO (Variable Frequency Oscillator), which is used to tune the receiver to different frequencies, and the Audio gain control, which is a manual control for adjusting the volume of the audio output.