On Sun, 01 Feb 2004 01:19:22 GMT, Orval Fairbairn
wrote:

BTW, it DOES make a difference if you hook up the comm antenna to the
nav and vise-versa. One is horizontilly polarized while the other is
vertically polarized. Both receiver sensitivity and xmit capability cna
be severely compromised.

Yes, but: The Narco "Comm" antenna is the transmitter, and the "Nav"
antenna provides the signal for the receivers for BOTH the Nav and the Comm
channels. The Comm receiver is *supposed* to use horizontally-polarized
antenna. I know, it ain't right optimum. But that's the way Narco wants
it.

The original two antennas in the airplanes were coax dipoles with baluns.
Both horizontally oriented, both located UNDER the aluminum-covered
turtledeck. They were truly duplicates. And they worked quite well, for
almost 20 years.

One crapped out a few years back, and that's when I built the surface-mount
antenna described in my "Antenna Madness" posting about three years ago.

So I've got one horizontal, and one vertical. I try to hook the old dipole
(the horizontal one) to the receiver and the new vertical one to the
transmitter. I actually run the coaxes in two pieces, with the connector
right by the seat, so I can switch antennas easily if I detect a problem.
This is handy for troubleshooting...a couple of times, I've noticed that I
wasn't receiving signals very strong, or folks complained that they
couldn't hear me very well. I've been able to quickly swap antennas and
compare.

Ron Wanttaja