Perhaps you could link a handheld up to your antenna to check it. Problem is
a bad antenna can cook the output stage of an icom A3/22 for example.
Have you tried an SWR meter on the antenna?
I can't remember the antenna input on the 200. Does it take a standard BNC?
Jerry
LTS@avnet.co.uk
http://www.avnet.co.uk/touchdown
----- Original Message -----
From: Fred Fillinger <fillinger@ameritech.net>
Subject: Re: Date: Sat, 12 May 2001 21:53:25 +0100
> Bob, it starting to sound like it really is an antenna problem, being
> unable to receive beyond few miles. You've said that people can hear
> you OK, but an antenna working at 25% efficiency will still put out
> about 2 watts from your A200 (theoretically good to several hundred
> miles). Modern panel-mount receivers or base stations with
> audio-leveling circuitry reading you loud and clear means nothing.
> But 75% loss of received signal is going to give all the symptoms
> you've been reporting.
>
> I've not seen an internal adj. on any comm that that requires
> in-flight tweaking. The improved reception could be due to differing
> daily atmospherics, or merely reconnecting a poor coax connector.
>
> Any field strength meter you can borrow can compare your xmit output
> to someone's else's of similar pwr and at same distance from the
> antenna. Does anybody's base station have a built-in signal strength
> meter? Many do.
>
> Re grounding, just about anything's possible with avionics, but DC
> grounding and RF ground are two different things entirely. There's no
> shorts or opens in the antenna coax I hope....
>
> Regards,
> Fred F., A063
>
> "Bob.Harrison" wrote:
> >
> > Hi! To all those who tendered advice re my ICOM AC 200 Transcom.
> > Well today came and went. We went to Wolverhampton to see the "oracle"
> > there,
> > having disconnected one end of the Mag switches shielding grounds for
which
> > there was no improvement.
> > He ....... could only bench test the damn thing, in spite of saying
bring
> > the
> > 'plane. He told me what I already knew.... that the set was set up as
the
> > maintenance manual recommends( which I already knew!)
> > Under pressure he decided to put his screw driver in the squelch adjust
hole
> > tried a slight adjustment (NOT having noted where it bloody was before
he
> > started!) and we re-installed it in the a/c. We were getting
Wolverhampton
> > Radio (who have an Icom Base!) fives at 10 miles and very faintly at 15
> > miles. So we though we had improved the thing.
> > Got back to Wickenby regularly calling them but only got reception in
the
> > circuit!
> > Just tell me ,Chaps, why isn't it possible to make a slave harness and
plug
> > it into the a/c with co-ax extension piece to the a/c antenae to enable
the
> > set to be put on the engineers knee whilst in flight to ajust the damn
thing
> > as the transmissions
> > are recieved or NOT as the case may be?
> > Perhaps a mechanical engineers' solution for some reason doesn't apply
to
> > radios?!
> > He also has suggested that all equipment or any structural ground tails
> > should be taken direct to the battery.?
> > Regards
> > Bob Harrison
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