Where most of the gain comes from in a superheterodyne receiver In a well-designed AM superheterodyne set, which stage typically provides the majority of the amplification of the received signal?

Introduction / Context:
Superheterodyne receivers translate incoming RF to a fixed intermediate frequency (IF), where stable, high-gain, and selective amplification is easier to implement. Understanding where most gain is applied helps with noise figure, stability, and selectivity trade-offs in practical designs.

Given Data / Assumptions:

• Single-conversion AM superhet with IF around a few hundred kHz (e.g., 455 kHz).
• Moderate RF preselection, fixed IF filtering.
• Standard audio chain after detection.

Concept / Approach:

At a fixed IF, narrowband high-Q filters and multiple cascaded IF amplifier stages can be stabilized and aligned for both gain and selectivity. RF stages usually offer lower gain to avoid oscillation and radiation from the antenna. Audio power stages amplify only after detection, acting on baseband, not on the weak RF/IF signal.

Step-by-Step Solution:

Verification / Alternative check:

Alignment procedures emphasize IF peak gain and bandwidth; data sheets for IF ICs show most overall gain contribution in the IF chain.

Why Other Options Are Wrong:

RF stage gain is limited to maintain stability and prevent LO radiation; audio power stage does not amplify the RF/IF signal; “none of the above” and LO buffer are distractors.

Common Pitfalls:

Assuming more RF gain always improves sensitivity; it can worsen strong-signal handling and stability compared to placing gain at IF.

Final Answer:

IF stage