Originally Posted by TrekLawler
if you have a good, in working order transponder L band antenna, it will do just fine with no need for a replacement.
That sounds like a common sense approach. The manual (section 4.4) arguably eliminates a common sense approach saying....
"The GDL 82 requires the existing L-Band Ultra-High Frequency (UHF) antenna(s) meet the following specifications: Standard 50 ohm vertically polarized antenna with a VSWR < 1.7:1 at 978 MHz and < 1.5:1 at 1090 MHz..."
I have a common transponder antenna, a CI-101 and VSWR at 978 is not listed. The Ted monopole for ADS-B doesn't publish for 1090. IMO, if one is a stickler, there is going to be some more work to measure the VSWR, or dollars spent on an already tested antenna.
My test flight went fine. Because I have an antenna intended for 1030 and 1090, I will be curious to see how good 978 out is, compared to other UAT installs.