Fabricated a shelf for the two Garmin GPS antennas which will mount under the cowling. The shelf is 6″ wide and 6″ deep and the antennas are mounted as far forward on the shelf as possible so that reception loss by the top cowl hinge line is minimized. I could have purchased the RV-12 GPS antenna shelf but I just saved $12 by making it myself.
Antennas are installed with nutplates. Wherever possible items are installed with nutplates, allowing for one handed installation and removal. There is about a 1/4″ gap between antennas. I’ll mount the third puck style antenna under the showplanes fiberglass instrument panel cover.
Here’s roughly where it will go, held on with 6 #8 screws through the firewall with nutplates on the shelf. Planning for a 1/4″ gap between the antennas and the top cowl. The screws will be inserted from the baggage well side. I’m insisting that nothing protrude into the baggage area, keeping snags to a minimum when loading and unloading. Hence it’s better to have a round head screw in the baggage area rather than a nutplate and screw sticking out.