Ham Radio General Class Practice Test

For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal?

1. SSB

2. CW

3. AM

4. All of these choices are correct

The correct answer is: CW

A Class C power stage is particularly well-suited for amplifying signals where the amplitude of the signal is not continuously varying, such as with Continuous Wave (CW) signals. In this mode, the transmitted signal is essentially a carrier wave that is turned on and off, typically representing Morse code. The high efficiency of Class C amplifiers comes from their operation; they conduct for less than half of the input cycle, which is advantageous for signals like CW where the gap between keying can be significant, allowing for heat dissipation without excessive loss. While it is true that Class C amplifiers can also be used in some Single Sideband (SSB) and Amplitude Modulation (AM) applications, they generally require additional considerations, such as using linear amplification or additional stages for distortion control, which makes them less ideal for fully modulated signals compared to their suitability for CW. Therefore, CW stands out as the best-suited mode for Class C amplification.