Raab, F.H. JACoW Geneva, Switzerland 978-3-95450-180-9 10.18429/JACoW-NAPAC2016-MOPOB51 English 174-176 MOPOB51 ion operation klystron ISOL proton Contribution to a conference proceedings 2017 2017-01 http://dx.doi.org/10.18429/JACoW-NAPAC2016-MOPOB51 https://jacow.org/napac2016/papers/mopob51.pdf GMRR has developed solid-state RF-power modules that deliver up to 650 W at frequencies from 325 to 704 MHz. The nominal output of 500 W is delivered with an overall efficiency from 79% at 704 MHz to 83% percent at 325 MHz. In contrast to conventional solid-state power amplifiers, high efficiency is maintained over a wide range of output powers; e.g., 70 percent or better for outputs of 30 W or higher. Each 500-W module contains five 120-W RF power amplifiers (PAs) and a Gysel* splitter and combiner. The class-F** PAs employ GaN FETs and produce over 120 W with efficiencies from 82-86%. A class-S modulator maintains high efficiency over nearly the entire range of amplitudes. Supporting hardware includes a control computer, DSP, low-level RF amplifiers, and drivers. The 500-W modules are intended to be building blocks of a multi-kW RF power source. A system based these modules will consume 1/3 to 1/2 of the prime power required by a system based upon klystrons or conventional solid-state amplifiers and will have significantly lower cooling requirements.