Explanation: Class C amplifiers are specifically designed for maximum plate efficiency, conducting current for significantly less than 180 degrees of the input signal cycle. This short conduction angle minimizes the time the active device spends dissipating power, leading to very high efficiencies, often exceeding 70-85%. While this operation is highly nonlinear, it is suitable for amplifying constant-amplitude signals like CW (Morse code) or FM, where the output can be filtered to reconstruct the desired waveform without significant distortion of the information. Class A amplifiers conduct for the full 360 degrees, offering the best linearity but the lowest efficiency (20-30%). Class B amplifiers conduct for 180 degrees, providing better efficiency (50-60%) and linearity suitable for modes like SSB and AM when used in push-pull configurations. Filtered Class D amplifiers are switching amplifiers known for even higher efficiency (often 90% or more), but "plate efficiency" typically refers to the traditional analog amplifier classes (A, B, C) in the context of RF final amplifiers.