Why does the power amplifier of the SSB transmitter need to be linear?

A single-sideband (SSB) signal consists of varying amplitudes and frequencies that directly represent the original voice audio envelope. To faithfully reproduce this complex waveform without introducing severe distortion, the power amplifier must be linear, meaning its output amplitude is exactly proportional to its input. If a non-linear amplifier (like a Class C amplifier used for CW or FM) is used on an SSB signal, it clips and distorts the waveform. This distortion creates unwanted splatter and makes the transmitted voice completely unintelligible at the receiving station.