This is one for Jim Weir I guess...

I had one of the Icom antenna switchboxes in my airplane
until this week when I needed the panel space to let my
handheld use the external antenna. I never really cared for
that set-up, it appears it just uses a 1/8 inch phone jack
with the switch in it to disconnect the aircraft radio when
you plug in the handheld. The thought of the handheld's RF
passing within a few mm of the unshielded antenna lead for
the panel mount always bugged me. Anyway, I'd still like to
have the ability to use an external antenna with the
handheld. So far, it looks like the options a
1) The Icom or similar switch box
2) An extra antenna that is dedicated to the handheld
3) A set up where the antenna cable comes out the panel or
near it so that you can disconnect the antenna and connect
it to the handheld.

The switch box takes up more panel than I'd like, and I have
the reservations already stated. The dedicated antenna
might be a problem because it is only used when your other
radios are already down, and since it is not used regularly
you may not know it is broken until you need it and have no
other backups (other than the rubber ducky antenna on the
handheld).

The antenna cable coming out of the panel and going back in
seems a bit hokey and prone to failure because of the tight
radius bend needed. It also looks like hell.

SO what other options are there?

Ideally, I'd like to have some sort of set up where there is
a dedicated connector on the panel and a select switch that
lets me select either the handheld or the panel mount. It
would also be nice to have the plane's ptt come out to an
adjacent jack so that once the switch is thrown you can
communicate normally (after also plugging into the headphone
adapter on the radio). As I recall, the PTT is a switch
closure to ground, but I'm not sure if I can just connect to
the ship's PTT without first disconnecting it from the
ship's radio (Jim?). What is an appropriate antenna switch
that provides enough isolation to protect both radios from
damaging overload due to the other one transmitting? How
about impedance matches, seems that Icom box does little to
make sure the impedances are properly matched.

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
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