Today I drilled, deburred and primed four additional, dedicated mounting holes in the doubler plates, then riveted the doubler plates and platenuts to the top rib. Used squeezer for all rivets (which were AD470AN3-7s, cut down to the proper length). Installed the antenna puck. Attached six feet of RG-58 coax cable (with BNC connectors on each end). I sealed this connection with weatherproof rubber sealant “tape,” commonly used on outdoor coax connections. I've had excellent results with this stuff in many antenna connections over the years, so I think it will prevent corrosion in the connection for the next few years as I build the rest of the airplane. I began installing three Adel clamps along the front side of the spar web to hold the coax cable, and began enlarging a tooling hole in the bottom rib for the cable to pass though.