Kazakov, S. Hanna, B.M. Pronitchev, O.V. JACoW Geneva, Switzerland 978-3-95450-178-6 10.18429/JACoW-SRF2015-THPB098 English 1376-1378 THPB098 cavity resonance multipactoring rf-amplifier monitoring Contribution to a conference proceedings 2015 2015-12 http://dx.doi.org/10.18429/JACoW-SRF2015-THPB098 http://srf2015.vrws.de/papers/thpb098.pdf The linear accelerator for the PIP-II program utilizes two types of 325 MHz Single Spoke resonator cavities: SSR-I and SSR-II. Operating power of SSR-II is about 17 kW and requires input couplers which can reliably work at power levels > 20 kW with full reflection at any reflected phase. Currently only one 10 kW RF amp is available for coupler testing. To increase testing power, a special resonance configuration were used. This configuration allows us to raise RF power approximately 3 times. The testing scheme and results are discussed in the paper.