You may find the coax cables are joined by bnc connectors under the panel
near the pilot's left knee. This may be an easy(er) place to swap com
antennas before trying to access the back of the radio trays to swap the
coax. The hardest swap is laying on your back in the tail cone checking the
connectors at the base of the antennas.

I have heard that com antennas come with a special coating to suppress
static buildup. Static charges can interfere with the radios. This coating
will eventually deteriorate and could also degrade radio performance. I
suspect such a buildup probably produces 'static' or popping in the
receiver.

--
Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

"Kevin Clarke" wrote in message
nk.net...
Hi,

I'm looking for folks that might have a similar experience. Recently
upgraded the panel to include a GNS 430 and replace one of those old NARCO
all in one VOR instruments plus an old NARCO radio.

Anyway great upgrade. The GPS function works wonderfully. Filing /g is the
best. The NAV function works great. Dual glide slope indicators(the other
is slaved to a KX-155) really makes IFR manageable.

The problem is the COM function of the GNS 430. We're only getting about
40 miles of range on the receive side of the COM. I'll call for flight
following on COM1(the GNS) and never get an RX indication. When I flip
over to COM2 (the KX-155) it works just fine. The KX has a range of at
least 80 miles. The GNS seems uneven. We can xmit and be heard over
distances but the receive side is really only useful in and about the
terminal area. This is less than optimal.

When we did the upgrade we kept the original antennas that were on the
plane(PA28-180).

Our avionics guy is baffled, maybe useless at this point. He swapped out
the GNS plus ran a myriad of other tests. He says everything is checking
out just fine. But that is surely not our experiences. So I turn it over
to the collective wisdom of the net. Has anyone else ever experienced
anything similar?

Thanks.