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Re: [RFI] Eliminating TVI

To: "RFI List" <rfi@contesting.com>
Subject: Re: [RFI] Eliminating TVI
From: "Jim Brown" <jimbrown.enteract@rcn.com>
Reply-to: Jim Brown <jimbrown.enteract@rcn.com>
Date: Tue, 23 Dec 2003 12:03:39 -0600
List-post: <mailto:rfi@contesting.com>
On Tue, 23 Dec 2003 09:45:11 -0800 (PST), N6KJ wrote:

>The color goes away (screen switches to black/white) whenever I transmit
>on 80 or 40 meters.  No problems with 20 meters and higher.  TVI present with
>as little as 10 watts output into a dipole about 30 feet from the TV.

Sounds like a really severe case!

I suspect either power line or antenna line coupling, and I suspect the
filters you are using are ineffective below 20 meters. The 43 material
is primarily a VHF material. I would try toroids optimized for HF, and
wrap as many turns as possible around them on all the wirng entering
the TV. And I would disconnect any extra wiring so that I was looking
at only one connection at a time (for example, power and antenna
connected, VCR disconnected). 

Along the same line: What happens with rabbit ears or equivalent on the
TV and nothing else connected but power?  If you still have the
problem, this suggests either a shielding problem or a power line

And is the color going away because RF is getting into the color
circuitry, or because the RF signal is dropping in level in the
presence of RF? 

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