What is the effect of excessive microphone gain on SSB transmissions?

Setting the microphone gain too high on a Single Sideband (SSB) transmitter will overdrive the radio's audio circuits. This inevitably leads to clipped, distorted transmitted audio that is difficult for receiving stations to understand. Besides sounding terrible, this distortion creates spurious emissions commonly known as "splatter." Splatter makes your signal excessively wide, causing irritating interference to other operators on adjacent frequencies. Excessive mic gain does not affect your antenna system's Standing Wave Ratio (SWR), as SWR is purely a physical property of the antenna and feedline match. It also has no impact on the radio's frequency stability or sideband inversion.