I've got a 496 that works flawlessly in 2 airplanes but works intermittently in a third airplane. What I finally discovered after much angst and troubleshooting in the 3rd is that for some reason, when I have a certain nav frequency tuned in to either radio (Narcos)(109.7 -- my ILS freq at GMU), neither the GPS nor wx signal will activate.

Change the freq, and all is well within 5 minutes. Pete, you can explain this RFI (I assume)mystery to us common folk. It not only does this to my 496, but also does it to my Anywhere Map Wx PDA. So clearly, there's some sort of blocking of signals going on in the 3rd plane (TwinCo).

So, back to the original query, it may not be an antenna issue, but maybe a freq issue on a nav/com.

FWIW

Keven

P.S. Did I read somewhere that Larry sold his 337?
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Lovely Wendie