Hi all,
We have an Icom 710RT SSB on our catamaran (now in Guatamala), and
haave been having some strange behaviour from the Mic recently.

When I release the Tx button on the mic after transmitting, the radio
will sometimes (30%) downshift to the next lower programmed freq. No, I
am not hitting the channel key on the mic.This odd behaviour only
happens on the 8 meg freq. Naturally, that is the net freq for that
part of the Carib.

Makes me look like more of an idiot than I already am when I don't hear
or respond to a reply to my thoughtful comments on the net.

EMF or RF causes?? Bad mic? Any help with causes/cures? Leave to go
back to the boat in a month.
Bruce
SV Skyus, a 42' Loch Crowther SuperShockwave cat

"skyus" wrote in
oups.com:

EMF or RF causes??

As it only happens on one band, not others, I'd say "probably". RF may be
backing up the cable from a loose ground strap on the tuner. (It IS
properly grounded, right?) Clean all the grounding connections if it
didn't do this problem in the past. Corrosion is normal...it's a BOAT!

You can also try adding some more grounding paths at the transceiver than
you have now. This will change the resonant frequency of the wiring to the
radio and may solve the RF problem. Use a test lead with clips on the ends
and ground the chassis of the radio to various other grounded gadgets near
it and try it.

I tend to agree with Larry since the problem occurs on only one band.

Can we assume the radio worked properly until ?? months ago? Were any
changes made to the electrical/electronic system just prior to the
malfunctioning? Has the problem changed over time (e.g., used to happen
rarely but now occurs every time)?

Since the microphones are pretty common, you might borrow one from
another cruiser to confirm that the problem is not with your microphone.

Another possible cure may be to add some ferrites to the microphone
cable, although RF could be getting into the radio via other paths as
well. Do a web search to get some pointers on keeping RF out of your
equipment.

Of course, you are aware that single sideband will not work well on a
vessel with two hulls..................just kidding.

Good luck.

Chuck







skyus wrote:
Hi all,
We have an Icom 710RT SSB on our catamaran (now in Guatamala), and
haave been having some strange behaviour from the Mic recently.

When I release the Tx button on the mic after transmitting, the radio
will sometimes (30%) downshift to the next lower programmed freq. No, I
am not hitting the channel key on the mic.This odd behaviour only
happens on the 8 meg freq. Naturally, that is the net freq for that
part of the Carib.

Makes me look like more of an idiot than I already am when I don't hear
or respond to a reply to my thoughtful comments on the net.

EMF or RF causes?? Bad mic? Any help with causes/cures? Leave to go
back to the boat in a month.
Bruce
SV Skyus, a 42' Loch Crowther SuperShockwave cat

"chuck" wrote in message
k.net...
I tend to agree with Larry since the problem occurs on only one band.

Can we assume the radio worked properly until ?? months ago? Were any
changes made to the electrical/electronic system just prior to the
malfunctioning? Has the problem changed over time (e.g., used to happen
rarely but now occurs every time)?

Since the microphones are pretty common, you might borrow one from
another cruiser to confirm that the problem is not with your microphone.

Another possible cure may be to add some ferrites to the microphone
cable, although RF could be getting into the radio via other paths as
well. Do a web search to get some pointers on keeping RF out of your
equipment.

Of course, you are aware that single sideband will not work well on a
vessel with two hulls..................just kidding.

Good luck.

Chuck

I agree with Larry and Chuck...since it is only one band, it is probably RF.
Several different length ground tape paths might be the quick fix.
I am trying to convince my boss his trimaran will never work on HF SSB also,
but so far he has had not problems with three hulls. LOL

73
Doug K7ABX

Thanks for all your advice. Will work on ferrites and grounding when I
get back to Guatamala. Problem started suddenly, but then I had changes
locations and started using a new cruisers net on that freq. Still only
happens say 30% of time. Maybe it fixed itself when I was gone....
Right. So is SSB on a multihull double sideband?
Bruce

On 20 Aug 2005 14:16:00 -0700, "skyus" wrote:

=So is SSB on a multihull double sideband?

Absolutely! Port hull uses LSB and stbd hull uses USB. The result is
AM.

Cheers--
Terry--WB4FXD
Edenton, NC