Becker Transponder E10 error message

On Saturday, May 12, 2018 at 3:02:09 PM UTC-4, Steve Cameron wrote:
On Friday, May 11, 2018 at 5:10:14 PM UTC-4, Steve Cameron wrote:
I've recently bought a glider that has an older Becker transponder(mode c), and every time I turn it on it invariably displays the E10 error code. In reading past reports of this issue(2006/2008) on the net this seemed to be a fairly common occurence, with no real solution. Becker says its a transmission fault involving the antenna and or ground plane. My local avionics shop tested it for the two-year cert, everything checked out OK, than at the end of the check the E10 pops up. We've tried adding a short piece of coax at the antenna end, as well as insuring the ground plane is truly grounded. So far nothing seems to rid the error message. My avionic tech here seems to think it was a design flaw in the unit, and I'm very tempted to just scrap it and move on. Is there anyone out there who has successfully dealt with this issued?
Thanks
SC

Darrel, your comment about making sure the BNC connector made good contact with the aluminum foil ground plane seemed to do the trick. I doubled up some heavy duty tin foil and placed it over the top of the antenna stub that the bnc connects to, than attached the bnc connector for a tight fit. I turned the transponder on and ran for @ 30 minutes, with no E10 message. Hopefully this will be the last of that problem!

Thanks again!
SC

Steve,

my 4401 has a threaded BNC connector in the back. I bought a new threaded-to-bayonet adapter to make sure I have a good and rattle-free connection.
As for the ground plane, I have some 'real estate' behind the seats and installed a ground plane about 1.5ft x 1.5ft. The guy who did my transponder check and sign-off liked it.

Uli
'AS'