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Re: [RFI] Eliminating TVI

To: rfi@contesting.com
Subject: Re: [RFI] Eliminating TVI
From: "Ian White, G3SEK" <G3SEK@ifwtech.co.uk>
Reply-to: "Ian White, G3SEK" <g3sek@ifwtech.co.uk>
Date: Tue, 23 Dec 2003 23:39:46 +0000
List-post: <mailto:rfi@contesting.com>
N6KJ wrote:
I'm not a TV expert so I don't know the answer. What I can say is that if 10 watts of RF on 80/40 meters with a dipole 30 feet away is swamping the input then somebody did a pretty crappy shielding job on this tv. I used to run 100 watts into a dipole that was about 1 or 2 feet from our TV antenna when I lived with my parents with no problems.

It's time to find out what's really going on.

At present you have no idea of the nature or size of the RFI "challenge" to the TV. Is it really the RF field in which it's sitting, or is it due to RF currents being conducted into the TV, along the mains lead or along one (or more) of the connecting leads?

I hate to keep banging this drum, but... you could learn a lot by using a clip-on RF current meter on all the incoming leads, to see where the currents really are, and roughly how big they are. Details and examples of RF current meters are at the URL below.

You have already tried various methods to reduce RF currents on the TX feedline, and on the leads to the TV... but how much have they achieved? Which of your chokes are doing something useful? Which of them are a waste of time, because there wasn't much current there anyway?

Until you make some measurements, you're groping in the dark.

-- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) Editor, 'The VHF/UHF DX Book' http://www.ifwtech.co.uk/g3sek/clip-on/clip-on.htm _______________________________________________ RFI mailing list RFI@contesting.com http://lists.contesting.com/mailman/listinfo/rfi

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