George,
The very first thing I'd recommend is to move that beam off the roof and
onto a mast/tower as far from your shack as you can go. If you do the math,
your RF exposure is way above the safe levels... You're just too close to
the beam and your RF level is quite high due to the 1500 watt amplifier.
You may have kept RF out of the RF equipment, but the computer is probably
being saturated...
73, Larry - W1GOR
----- Original Message -----
From: "George Skoubis" <george.skoubis@verizon.net>
To: <tentec@contesting.com>
Sent: Tuesday, May 20, 2003 13:48
Subject: RE: [TenTec] RF Feedback on Omni VI (opt 3)
> 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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