Yamamoto, Y. Matsumoto, T. Michizono, S. JACoW Publishing Geneva, Switzerland 2673-5504 978-3-95450-234-9 10.18429/JACoW-SRF2023-WEPWB098 English 820-822 vacuum SRF GUI cryomodule cavity Contribution to a conference proceedings 2023 2023-09 https://doi.org/10.18429/JACoW-SRF2023-WEPWB098 https://jacow.org/srf2023/papers/wepwb098.pdf At KEK, cost reduction study for STF-type input power coupler used in the STF-2 accelerator has been attempted since FY2015. In FY2019, one coupler was fabricated by some cost-effective and non-conventional methods including different alumina-ceramic material, copper plating and TiN coating. In high power RF test at room temperature, this coupler achieved 1 MW at 900 µsec/5Hz, and 935 kW @1.65 msec/5Hz. After that, this coupler experienced 10 thermal cycle tests from room temperature to liquid nitrogen temperature without vacuum leakage. In this report, the detailed results will be presented.