Hi,
I also have/had this problem and it wasn't RF feedback. In my case it
was a ground loop problem.
Disconnect anything you have plugged into the RS-232 port, Mark/Space,
Audio In, Audio Out, and Serial Port jacks on the back of your radio.
Transmit and see if your problem is gone. If it is call the service
department and have them send you a fax of the fix for the TX Audio
Board ground loop. They will send you a picture of the board which will
show you two places to cut the ground foil, you then have to add a new
ground to two places as well.
This was not a complete fix for me, I still need to wrap my RS 232
cable through a toroid and cannot use the serial port and RS 232
simultaneously (I made a Y-cable to split the data signal so the
computer and antenna controller can both read the frequency data).
I still cannot plug the computer into the audio jacks (without getting
transmit distortion) so I cannot use the computer for voice keying.
I can operate my Omni VI Opt 3 with my Titan amp at 1500 watts with
clear transmit audio (I'm on the second floor, right under the beam) on
10, 12, 15, 17, and 20 meters SSB or CW. I don't have an antenna up for
40-160 right now but I will be trying it out in late fall when I put up
a contest-season wire antenna.
73 & Good luck de George / KF9YR
-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com] On Behalf Of Mark Erbaugh
Sent: Monday, May 19, 2003 10:35 PM
To: Tentec (E-mail)
Subject: [TenTec] RF Feedback on Omni VI (opt 3)
My Omni VI option 3 upgrade has developed symptoms of RF feedback. I got
a
report of RF in my transmitted audio. I'm also hearing muffled audio in
the
speaker or headphones when transmitting. I get this problem even when
transmitting into a dummy load. The muffled audio in the speaker seems
pretty much the same whether I'm on 75m or 10m.
My Pegasus is sitting next to the Omni VI. I moved all the cabling from
the
Omni VI to the Pegasus. The Pegasus doesn't appear to have the RF
feedback
problem.
My ground isn't ideal. I have about 15 feet of RG8 coax braid going to
the
copper ground wire that runs from the electrical panel to grounding rods
(2). There is about 8 feet from where the braid joins the ground wire to
the
ground rod. So I guess my total length to ground is about 23 feet.
I do plan on shortening the path to ground and using heavier wire, but
that's going to require drilling through the poured walls of my
basement.
The two ground rods for the electrical system are just outside the wall
of
my shack (about 6 feet apart). By drilling through the basement wall, I
should be able to get the total length to the first ground rod down to
six
feet or so. Is it likely that a third ground rod for the shack (but
connected to the other two) would help?
Any ideas?
Thanks,
Mark
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