Wayne,

I would suggest you put a ground plane behind the antenna, and tie it in with the airplane ground.  Had this problem once on a Mooney with an STC'ed one piece fiberglass belly pan.  Ground plane doesn't need to be big, 12 - 14 inches in diameter should do.  I used some copper mesh that I had handy, but a thin sheet of aluminum should also do.

Micah Froese
Lancair Legacy
300 hours
down for paint

Subject:
Small Tail Incidence Data & Transponder Problems
From:
Wayne Bailey <waynnno@yahoo.com>
Date:
Wed, 08 Oct 2008 18:46:39 -0400

To:
lml@lancaironline.net



Also,  having intermittent transponder problem.  Seems to always have problems with SOCAL in LA basin,  but other radar environments sometimes have a problem sometimes not.  Go figure.  I have reply light flashing but they can't see me - other times no reply light.  Tried cycling etc.

Current transponder is a King KT76C.  Internal antenna.  Don't know about required matching transformer yet. Going into the shop this morning for trxpd checks.  Plan to check frequency and power and check for matching transformer.  But my mechanic says that he has had very limited / no success with "internal" antenna on other composites.

Any list experience with internal antenna? Any suggestions on where internal antenna might be located?

Thanks a lot.  Really appreciate help from the list.

Purchased AC last spring,  but haven't flown it much due to taking it out of CA to avoid the sales tax (9.5%  !!!).  Plan to start flying a lot more and resolving these issues.

Wayne Bailey
310-567-6877

N10RD
LNC2
360