>This is the one problem I have found with the FT-990. It does seem to be
>vunerable to RF feedback thru external plug-in's, particularly, the external
>speaker. I would, as I know others would, be curious about other experiences
>and, hopefully, some solutions.
I'm a proud new owner of an "MP", and havn't
experienced any trouble like that so far,
so I've no direct experience with your trouble. However,
I've had simular trouble with other ham projects,
such as with a repeater controller
co-located with a ch2 TV broadcaster.
I found some snap on ferrit chokes at
Radio Shack that did wonders. They have
2 sizes, the big square one being the
one that I used, which leaves room for a wrap or
two of the wire. The other snaps onto typical
mic. or headphone size cables.
Another situation I've seen is in a commercial
2-way mobile installation, with
it's antenna mounted on the trunk lid, right over the
radio. RF would get into the PTT or the uP somehow,
causing strange behavior during keydown. This
was also cleaned up with the snap on from RS,
clipped on the control cable right at the radio.
Perhaps these are not as effective at HF as at VHF,
but might be worth a try.
Good luck, 73
wd4egf
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