The modulator stage in a radio transmitter is normally

Question

The modulator stage in a radio transmitter is normally

1. A. Class-C Amplifier (Correct answer)
2. B. Class-B push-pull Amplifier
3. C. Class-A Amplifier
4. D. Class-D Amplifier

Correct Answer

Option A — Class-C Amplifier

Detailed Solution & Explanation

The correct answer is Class-C Amplifier.

Key Points

• The official JKSSB answer key marks Option A, Class-C Amplifier.
• In a classical AM transmitter the final RF stage is modulated, and that stage is operated in Class-C because it delivers the highest efficiency — typically 70-80% — for the amplification of a single carrier frequency.
• Class-C conducts for less than half of the input cycle, which distorts the waveform badly but is acceptable at RF because a tuned tank circuit restores the sinusoid.

Additional Information

• Many textbooks reserve the word *modulator* for the audio power amplifier that supplies the modulating signal, and that stage is normally Class-B push-pull (Option B) for low distortion with good efficiency. Candidates should be aware of both readings.
• Amplifier classes by conduction angle: Class-A 360° (most linear, least efficient), Class-B 180°, Class-AB between the two, Class-C under 180°.