Hi Mark,
When I installed my GPS WAAS antenna, I taped a square of 320 sandpaper (grit side up) on the turtle deck and then used the flat base of the antenna for a pattern to cut a small piece of wood.
Pretty sure I used something similar to balsa because it is softer and easily shaped. I started with a barrel sander on my drill to shape it somewhat and then finished sanding to match the shape of the turtle deck curve by sanding the wood on the piece of sandpaper I taped directly on the turtle deck. After I got the fit the way I wanted it, I used the white paint that I had for my airplane to spray the edges really well and lightly sprayed the side that rests on the turtle deck. Not really necessary but I also had some thin white rubber that I use for my fuel filler neck area so I put that between my turtle deck and the wood but friends have done the same fix without a rubber gasket in between. I also used my antenna base holes for a pattern to drill through and I put the antenna just inside the back bulkhead of the turtle deck for easy access and then ran the coax down through a hallway drilled in the bottom of the back corner of the turtle deck floor area. Just make sure it is accessible from inside the rear bulkhead of the turtle deck compartment. It’s really a pretty easy fix for the issue of the curve of the turtle deck and as you can see in the photo it looks pretty nice. I’ve had several people copy it and it takes no time at all to make
No issues at all when flying. Sometimes when I’m inverted, my ADSB will temporarily show a fail on Flight Aware..., but have not received any letters at all from the feds...they seem to know when Aerobatic airplanes fly with ADSB it’s part of the deal when inverted. I’ve flown with it for a year now with no issues.
Lynn OJala N13LD
(612) 840-3863