The gain is 3.6 (11dB). The output filtering is a 5th order Butterworth filter with very high harmonic suppression. The efficiency is somewhat hard to calculate, but my best guess is 47%, which is actually not bad. It could be higher, but at these power levels, we can afford a little power waste. The downside is that the output filtering is designed for the whole FM spectrum, while the amp itself is tuned to 100MHz. The THD is 0.02% meaning that for the power of 1.43W the harmonic power is 30mW. The best guess for the power dissipation of the transistor is around 0.6W since it mostly works in class C
