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Re: [RFI] Eliminating TVI

Subject: Re: [RFI] Eliminating TVI
From: Jason Buchanan <jsb@digistar.com>
Date: Tue, 23 Dec 2003 19:06:44 -0500
List-post: <mailto:rfi@contesting.com>
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.

Based on your email it doesn't sound like you have much chance to fix this problem. but........ try the suggestions below:

If the TV has a setup screen that you can display with NOTHING connected to it but the power cable plugged into the wall, go to that menu and try keying the radio. The idea is you want to display a solid background with no signal input, generated by something inside the TV, and not coming from a signal jack.

If you still experience the problem with NOTHING plugged in but the power cord in the wall you probably will have no way to fix the problem. Something inside the TV is not shielded and until you open the plastic case and find it you're out of luck (see needle in haystack).

The only thing you could try is running the power cord through some beads (77 mix probably) to see if you can eliminate RF from the power cord (try alternating putting the beads at both ends of the cord).

My preamplifier for my stereo is real real real bad on 40 meters. The RF comes in through the RCA jacks (the other stereo in another room sucks RF in through the speaker wire). 15 watts out will produce a hum, 800 watts causes it to leap off the shelf and dance around so I have to make sure it is off when I'm on 40 meters. However, one leg of my 40 meter dipole runs parallel to the roofline of the house (it's tied off to the chimney on the other side of the house) so I think there is a lot of RF coming through the romex for the attic lights.

My 160 dipole causes my ground fault circuit to trip causing hair dryer anxiety for my wife the morning after a 160m rally.

Portions of the band where SWR is LOW greatly reduces interference - any SWR is bad because it goes into the shack, your house, your neighbors' house, etc.

Anyway, best of luck.

73 Jason N1SU

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