The results of an experimental study of the formation of powerful UHF pulses with the help of a standing wave waveguide resonator are presented. The switching process from the energy accumulation mode into the output mode was carried out with a high-speed gas discharge commutator with external triggering at a frequency of 50 and 100 Hz. Pulses were obtained with a duration of 15 ns and a power of 70 mw with a power amplification factor of 18 db in comparison with the power into to the generator. The efficiency in extracting the accumulated energy attained 80%