I am using a first generation IC-7700 with a SignaLink USB on FT8/4 and other digital modes, including CW, and everything works just fine. Set your radio to USB for FT8, not Data, you don't need that setting, and assuming you are using the DIN socket on the rear and your SLUSB is jumped correctly, yours should work. If you want to know any specific menu setting, eMail me and I will reply with my settings. 73 de Jim K4LIX