On Sunday, December 31, 2017 at 12:58:25 PM UTC-6, Darryl Ramm wrote:
On Sunday, December 31, 2017 at 10:03:37 AM UTC-8, Scott Williams wrote:
On Sunday, December 31, 2017 at 7:33:39 AM UTC-6, wrote:
AC 43.13B 308d says you need a backing ground plane.
But I didn't see any special details for CF versus other composites?

Following the instructions from the glider manufacturer seems smart.

My std Cirrus has a schempp-Hirth TN that clearly spells out the installation
of the blade antenna. but it allows either aluminum or copper for a ground plane.
I chose a copper plate 0f .043 thick.
Trigg 22 has good output, but the 'sensitivity' was right on the low tolerance.
Any thoughts or insights?
thanks,
Scott

What did the technician doing the test recommend? If there was a doubt why did they not direct connect test the transponder?

These measurements are not highly precise. If its within tolerance then go fly. If not then get a different avionics technician to repeat the test if possible and if its bad then direct connect test the transponder to see it is likely the transponder or cable/antenna..

in short,
New trig tt22, new only 14 inch antenna coax, new antenna, copper ground plane, trig authorized shop doing test, fresh battery with good voltage.
Tech reports using two different 'test rigs' , also report "sensitivity is on the low tolerance, but I'll pass it" with no other suggestions.
I followed up with Trig factory tech line, maybe have to send it in for a factory check. Factory rep had on suggestions.
I have no idea just what 'sensitivity is. factory was helpful, but I think maybe "sensitivity" may be outside of the influence of installation variables.
I was hoping for someone to have an insight.

Thanks,
Scott