Christer,

 

I have the tail-mounted internal antenna as recommended by Lancair, and a whip antenna like the one in your picture mounted on the belly just in front of the main landing gear doors. This belly mounted antenna has an aluminum plate ground plane installed inside the carbon skin. The belly-mounted antenna is hooked to a Garmin SL-30 and the tail antenna is connected to a Garmin SL-40. Both radios/antennae work very well out to at least 100 miles when airborne; probably much farther.

The only difference that I could tell between our installations is that I used RG-400 cable, rather than RG-58, but I’d be surprised that the RG-58 would make that much difference. Is there any chance that your antennae cable has been crimped, mashed, or bent too sharply around a corner? Any of these could cause the problems you describe, but I think you’ve likely checked this already? You might also check to see that the shield conductor is firmly grounded and not “floating.” If these work OK, try a piece of RG-400 to connect your “spy plane” antenna to the radio.

 

Build up of static electricity will cause the problems you describe. We used to have a very difficult problem with the F-111 because the static wicks installed by the maker would vibrate off during high speed flight, rendering the radios useless. The solution was to slow down to allow the static charge to dissipate naturally. I have installed static wick mountings for my airplane, but have not actually installed them. The radios have worked very well without them through 130 hours of flying this summer. I suspect that the coming colder/drier winter weather may affect this more. I will be watching for this, and advise. I think it unlikely the radios themselves are bad. My recommendation is that you focus on the cable first—it’s easiest to check; and then the static buildup…

 

Good Luck!

 

Bob