He’s building his own linear amplifiers on what looks like sheets ... Good question, but it appears that there’s more than enough power to drive a long-range transmitter.

Perhaps understandably with such an old device, after cleaning away the dust of ages he replaced the power supply circuitry with new parts and PCBs. A linear amplifier is surprisingly simple ...

Guerrilla RF’s GRF5509 high-performance power amplifier paired with Impinj ... The GRF5509 delivers up to 2 watts of linear power while meeting the stringent spectral mask requirements required ...