your echoUAT ADSB install
Piper J3 (Jim) - that's a very professional installation, well done.
I installed the echoUAT and external antenna in/on the right wing inspection panel of my RV7A . Installed the SKYFYX GPS on top of the upper brace between the seatbacks per a recommendation from uAvionix. I'm not a builder but the only significant challenge I encountered was snaking the echoUAT wires through the existing wire tunnels from the wing inspection panel back into the fuselage. I didn't see other posts where folks were challenged with doing this, but I was. The existing wire tunnels (rather, holes) in my plane through the wing spars were only a dime's width diameter-wise and they were already full with autopilot servo wiring so to say it was a tight fit for threading additional wires through would be an understatement. And since you can't get your arm up in there, you have to be creative with a copper wire snake. The rest of the installation was straightforward.