Gonin, I.V. Khabiboulline, T.N. Lunin, A. Solyak, N. JACoW Geneva, Switzerland 978-3-95450-178-6 10.18429/JACoW-SRF2015-THPB005 English 1066-1069 THPB005 cavity simulation linac operation cryomodule Contribution to a conference proceedings 2015 2015-12 http://dx.doi.org/10.18429/JACoW-SRF2015-THPB005 http://srf2015.vrws.de/papers/thpb005.pdf LCLS-II linac is based on XFEL/ILC superconducting technology. TTF-III fundamental power coupler for the 3.9 GHz 9-cell cavities has been modifies to satisfy requirements of LCLS-II, operating in CW regime. In this paper we discuss the results of COMSOL analysis of the possible modification of couplers, working at various operating regimes. We present also the results of mechanical study.