Testing experience on 325 MHZ, 7 kW RF power amplifier for accelerator applications

The design of power amplifier (PA) modules and power dividers and combiners (PDCs) is at the heart of high power amplifier based on solid-state RF power devices. The design of PA module and its testing are very challenging part in the development of high power amplifiers. Therefore, amplifier test procedure have been planned carefully to know amplifier capability. Some of the amplifier parameters are measured using low power VNA tests under cold and hot conditions of the PA module and tuned it as initial design validation for input return loss and gain characteristics etc. However, efficiency and other parameters are measured under high power operation. Pulse testing of amplifier has been the first step in our high power test plan. We have measured amplifier parameters like efficiency (> 68%), response timing, gain (> 21 dB), harmonics, spurious noise etc. at low duty factor which do not have much thermal impact on them. Maximum temperature on the board of PA module in CW mode is less than 110 °C at full power operation. In this paper, authors would like to take an opportunity to share their experience and discuss various aspects of high power amplifier tests performed on 1 kW PA modules and 7 kW amplifier. (author)