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Terra Comm/Nav/Trans
Aircraft Radios

I installed Terra radios in my RV-8.  But it doesn't matter which aircraft radios you install, or in which airplane you install them.  These tips and ideas are applicable and may help you out.

Mechanical Installation

Front of comm traysThe COMM and NAV aircraft radio trays were already connected, but I riveted the TRANS tray to them.  I used a couple of AN426AD3 rivets.  The front ones were easy to squeeze with the pneumatic squeezer.  The tray itself got in the way to squeeze the rear ones, so I squeezed them with a small C-clamp.  I located the rivets using the preexisting holes if I could, since they were countersunk and would keep the rivet head out of the way.

Front of comm traysI cut the square hole in the instrument panel, and set the aircraft radios and trays so they protruded the amount I wanted.  Then I marked the trays where the back of the instrument panel hit them.  I used three pieces of angle iron to hold the front of the trays to the panel.  Two rivets through the panel and two into the tray.  By doing the ones on the panel first, I could use the squeezer on the rivets that show.

Radio mountI mounted the back of the trays to the F-802NPP L.G. Box Upper Brace with a screw.  I thought I had located it where it would be easy to install and remove, but it was harder than I thought.   See What I would do different for this discussion.


I did almost all of the wiring at the bench.  I wired the d-sub connectors before I installed them in the trays, but I suppose you could do it the other way around (see Helpful Hints for Soldering Terminals). 

Antenna cable diplexer mounting I made the antenna cables on the back of the COMM and TRANS about 12 inches long, and put a BNC connector on them.  This lets me disconnect the cables easily if I want to pull the panel.  I have only one antenna for nav and glide slope, so needed the Diplexer (VOR/GS/LOC), Vans Part Number = AV CI-507.  I mounted it on the backside of the F-866APP Baggage Compartment.  I ran the antenna cables from the back of the aircraft radios to the diplexer without splices or connectors.

The TRANS cable runs down the left gearbox, aft under the floor to the antenna.  The COMM and NAV cables run down the right gearbox, aft under the floor to the COMM antenna, and out to the right wingtip to the NAV antenna.

Installing the Antennas

I used a doubler on the inside of the fuselage for the TRANS and COMM antennas.  The TRANS doubler was just a large aluminum washer.  I made the COMM doubler out of scrap aluminum that I cut to the same size as the base of the antenna.  After drilling the center hole, I placed the antenna against the fuselage, marked and drilled the holes.  After repeating this for the doubler, I then fastened nutplates to the inside (top) of the doubler.  Then I screwed everything into place.

Inside view of transmission antenna
Inside trans antenna
Inside view of communications antenna
Inside comm antenna

Wingtip Antenna

Wingtip antennaThe Van’s “AV ANTENNA W’TIP” amounted to a strip of metal foil, some coax, and the connectors.  I ran the cable through the wing and terminated on the last rib.  Then for the antenna, I cut the strip to length, soldered on the coax, and glued it inside the wingtip.

Really, the only difficulty was that the fiberglass resin caused the sticky side of the metal strip to come undone, so it wanted to curl up instead of laying flat.  I used a few strips of masking tape to hold the strip down until the resin set.  I added another strip of cloth across the top of the coax so that the soldered joint didn’t take any abuse.  I figured that this way, the fiberglass strip would take all the stress of the coax moving and flopping as I did loops to music.

Checking things Out

Make sure you use a good, clean power supply here.  Either a real power supply, or a battery.  Don’t use a trickle charger.  I made sure the COMM all worked with the intercom and checked that the NAV locked onto the local VOR.  I’ll have to wait on the TRANS until the first flight.  I don’t think ATC will be able to receive my signal on the ground.

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