Mark,
Try reducing the power output of the Omni VI until the problem is minimized.
Before you do, check for RF on the ground line. My station is on the 2nd
floor and my grounds are about the same length as yours. Both TenTec and
MFJ manufacture a tunable device to 'bring-the-ground-up-to-your-rig'... I
think that the MFJ is a model 931, but you ought to confirm this. Using the
931 or the TenTec equivalent, will allow tuning the ground for maximum RF
current. Since using one of these units, my RF-in-the-shack problems have
gone away... and I'm using a TenTec Jupiter driving a Kenwood TL-922A
linear, running about 1200 watts.
73, Larry - W1GOR
----- Original Message -----
From: "Mark Erbaugh" <mark@microenh.com>
To: "Tentec (E-mail)" <tentec@contesting.com>
Sent: Monday, May 19, 2003 23:34
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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