FCC Exam Question: 6A499

Feeding back into the control grids of the IF and RF amplifiers a negative DC bias which is proportionedto the average magnitude of the received carrier wave accomplished:

A. Rhymed effect
B. Automatic volume control
C. Neutralization
D. Refraction
Correct Answer: B

Explanation: This process describes **Automatic Volume Control (AVC)**, also known as Automatic Gain Control (AGC). Its purpose is to maintain a relatively constant audio output level despite significant variations in the strength of the incoming radio signal. When a strong carrier wave is received, the detector produces a larger average DC voltage, which is then fed back as a negative bias to the control grids of the RF and IF amplifier stages. This increased negative bias reduces the gain of these amplifiers, preventing them from saturating and keeping the output volume stable. Conversely, a weaker signal produces less negative bias, allowing higher amplifier gain. *Rhymed effect* is not a recognized term in radio theory. *Neutralization* is a technique used to prevent unwanted oscillations in RF amplifiers by feeding back a portion of the output signal out of phase to cancel internal feedback. *Refraction* refers to the bending of waves (like radio waves) as they pass from one medium to another, such as when they interact with the ionosphere. These are unrelated to the described volume control mechanism.

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Includes Elements 1, 3, 6, 7R, 8, and 9.