Question 6A361

Linear amplifiers are crucial for signals where amplitude carries information, such as Amplitude Modulation (AM) or Single Sideband (SSB). Class B amplifiers conduct for approximately half of the input signal cycle (180 degrees). When properly designed, often in a push-pull configuration, they achieve good linearity, faithfully reproducing the signal's amplitude variations without significant distortion. They also offer significantly higher efficiency than Class A amplifiers, making them suitable for power amplification. Class A amplifiers are also linear, conducting for the entire 360-degree cycle, but their efficiency is very low, making them less practical for high-power linear RF applications. Class C amplifiers are highly non-linear, conducting for much less than 180 degrees. They cannot preserve amplitude modulation and are only used for amplifying constant amplitude signals, such as CW (Morse code) or FM (Frequency Modulation), where efficiency is prioritized and amplitude information is either absent or regenerated by a tuned output circuit.