The classification as a linear amp has nothing to do with its power. It's the configuration of the amplifier generating the RF that determines whether it's linear or not. Class A and class B push-pull amps are linear, Class C is nonlinear.100 mW is hardly what I would call a linear power amplifier. A kilowatt is more like it. A 100 mW signal on 1 MHz is smack in the middle of the AM broadcast band and would be of questionable legality.