Has anybody used the Av-DEC Polyurethane Conductive gaskets under the base of their antennae?
If so what is the experience. I gather they are not cheap.
I, like most, throw out any rubber gaskets that come with an aircraft antenna. Most manufacturers have stopped including them in the box as well.
I put a whole set of the Av-DEC gaskets on a Piper Comanche project. They are basically metal screen imbedded in the seal material. They were neat but are priced more for government contracts than EAB home builders. I think I ordered them direct from the manufacturer in Fort Worth and they wanted to know the exact antenna part number for each to make sure they cut out the proper shape. They seem to work okay but might be a cure looking for a problem. Also keep in mind the screen mesh isn't going to do you a whole lot of good unless the mounting skin is bare to allow the screen mesh to properly bond to the skin. If you will be mounting to a painted skin there isn't really any advantage.
Since then I have changed over to mounting the bare antenna base to the airframe and then using Permatex Right Stuff gasket maker as a perimeter sealant. On receive-only antennas like GPS, ADS-B "in" and Nav I remove the paint around the mounting holes on the inside of the skin with a piloted bonding brush in a drill motor and put star lock washers under the nuts to get good bonding. If corrosion is a concern I will coat the nuts and circular bonding area with more Permatex Right Stuff gasket maker. On comm transmit and transponder and/or ADS-B "out" antennas (i.e. any transmit type antenna) I remove the paint on the outside of the skin under the complete footprint of the antenna and then alodine the clean surface. Then after installing the bare-bottomed antenna I again use Permatex Right Stuff gasket maker as a perimeter seal. Transmit antennas need the best ground plane bonding they can possibly get. Lots of antennas get installed without the rigor of baring the exterior metal and alodining but I don't do this for a living so the extra time involved is fine by me.
