Pronitchev, O.V. Kazakov, S. Design of Main Coupler for 650 MHz SC Cavities of PIP-II Project JACoW Geneva, Switzerland 978-3-95450-180-9 10.18429/JACoW-NAPAC2016-MOPOB24 English 121-123 MOPOB24 ion cavity vacuum cryomodule proton Contribution to a conference proceedings 2017 2017-01 http://dx.doi.org/10.18429/JACoW-NAPAC2016-MOPOB24 https://jacow.org/napac2016/papers/mopob24.pdf Proton Improvement Plan-II at Fermilab has designed an 800MeV superconducting pulsed linac which is also capable of running in CW mode. The high energy section from 185MeV to 800MeV will be using cryomodules with two types of 650MHz elliptical cavities. Both types of cryomodules will include six 5-cell elliptical cavities. Each cavity will have one coupler. Updated design of the 650 MHz main coupler is reported.