This rf power amplifier design for a 2.5 Watt power amplifier for the FM band. An input of 50 mW gives a final output power of 2.5 Watts with a 13 Volt supply. The best bit is that the amplifier requires no tuning once it's built - it gives roughly the same gain and output power right across the FM band from 88 to 108 MHz.
There's even some hefty output low pass filtering to make sure that harmonic output is small and no interference is caused to users (mostly military!) on multiples of the FM frequency being amplified. A nice design based on, believe it or not, a military one...!