Also another answer that I get offlist
You don't need to spend the bucks or the time required with the Archer antennas. I made some really simple antennas for my nav installation. One female bulkhead BNC, one male BNC and a scrap of wire for each antenna. Mount the female BNC to the outboard rib and just lay the wire antenna inside the tip. Very easy and costs almost nothing. Since it's for nav and will be receive only, frequency-tuned length is not critical and power dissipation is not an issue. And inside the wingtips, it requires minimal mechanical strength.
Look here:
www.appaero.com/wings.htm near the bottom of the page. For the guide tubes, I cut a chunk of 14-2 NMB off of a roll and coaxed the insulation off the wire. I have pictures of the guide-tubes glassed inside the tips, but haven't gotten around to posting them to the web site yet. I used a scrap of tefzel for the pictures, but used a piece of fine music wire for the real antenna. Any wire about 20-inches long will do for nav, glideslope and marker beacon. You might be able to use the same antenna for all three, depending on the radios and splitters you use. If you have to pull a separate line for marker, the antenna should be about 39-inches.
Then I'll ask a few details more:
Q: If I understand you right, I mount an BNC Bulkhead Connector to the last rib (the connector is NOT isolated, so the shield makes contact with the rib),
A: That is correct - the BNC serves as both a light-weight mount for the antenna and to ground the coax shield to the airframe
Q: I put on an plug with only an musicwire connected to the inner pin.
A: Be sure to insulate the wire from the body of the male BNC connector. A few layers of heat-shrink tubing, tape, or fill the hole with epoxy with the wire centered in the shell.
Q: The musicwire will be bent in the Wingtip and the straight part of it should be 20".
A: 20-inches total length of exposed wire - any kind of wire and the length is not critical. I used music wire because it is small, reasonably stiff and slick - makes threading it inside the guide tube easy. The bend is not important except that it allows the wire to fit inside the fiberglass tip. I dig up the pictures of the insides of my tips.
Hope this is usefull for others also!
Dominik
