Installed 2 Comant Bent whip comm antennas, Like several other builders I put them in the second inboard bay under the rear seats. I made some doublers and put a flange on them so that they could be riveted to one of the seat ribs. Match drilled the antennas and installed nutplates. Clecoed the doubler to the rib and then ran a #40 drill through the nutplates into and through the bottom skin. Also ran a hole through the center of the cable access. Removed the doubler. and used the step drill to enlarge the four screw holes and the cable hole in the bottom skin. Then riveted the Doubler to the rib using LP 4-3 pop rivets. I bought 20 ft of RG400 shielded coax when I bought the antennas, and 2 BNC connectors. Stripped the coax and installed the 2 BNC connectors. Because of where the fuse sits on the 'sawhorse/dolly' I'm ot going to screw in the antennas now. I'll wait til its on it's own gear. But I can run the coax, and leave a service loop out of the bottom and this will allow me to finish soundproofing the rear seats and closing out the baggage area.
Right Com Antenna test mounted to doubler
Mounting holes for right Com antenna drilled in bottom skin
Right Com antenna doubler riveted to 2nd inboard rib.