I still have TVI problems too. I have an AC power strip, but am unsure of its
quality.
Who knows a particular brand/model that implements the features discussed here?
----- Original Message -----
From: "John Rader" <k5xtx@hotmail.com>
To: rfi@contesting.com
Subject: [RFI] TVI solved
Date: Sun, 07 Nov 2004 19:52:04 -0600
>
> My new tower is located against the back wall of our house, and is just a
> few feet form the TV. My TV, a 52" Mitsubishi projection TV in a wooden
> cabinet, was experiencing fundamental overload. The prior install had no
> TVI, but this time I knew the feedline and TV antenna were too close
> together and would require some serious attention to eliminate overloa. But
> how?
>
> After posting this issue to the RFI reflector I recieved a number of
> excellent suggestions. Fortunately the first one I tried stopped the TVI,
> which occured with as little as 20 watts. After following Tom, N5EGs
> suggestion on TV grounding, I am now able to run 1,000 watts without audio
> or picture interference.
>
> Tom's suggestion:
> >From an RFI perspective at the TV receiver, there is a dipole
> antenna the two halves of which are:
>
> the braid of the TV feedline, and
> the AC power wiring (hot+neutral in parallel).
>
> The TV set sits in the middle of this dipole, and
> detects strong RF fields, sometimes causing fundamental overload.
> Since you moved your transmission feedline closer to the TV
> feedline, you increased the coupling to this dipole.
>
> You want to short out this dipole so that no RFI voltage
> exists between the TV set and it's ground. It would be easy,
> except... most TV sets do not have a ground connection in
> the power cord (they use a 2-wire cord).
>
> So here are the steps to take:
>
> 1. Purchase a AC power strip that has F-type connectors
> in it. Get one that connects the F-connector shell to AC-power
> ground. The TV antenna cable connects to one F-connector on
> the power strip. You will need to make a short jumper (a
> couple feet) to go from the other AC power strip F-connector
> to the TV receiver.
>
> 2. You also want the type of AC power strip that uses
> capacitors to bypass the hot and neutral wires to ground. This
> puts the RF potential of the hot, neutral, and ground wires all
> at the same value. These capacitors usually have about 1.6kv to
> 2kv rating so that voltage transients on the power line don't
> cause them to fail (which could present a hazard). Of course
> if the TV receiver had a three wire cord, this would become a
> non-problem.
>
>
> This setup shorts the braid of the feedline to the AC power
> ground, and makes sure the TV set frame is AC grounded to the same
> point. In essence you have shorted out the spurious dipole around
> the TV set.
>
> Make sure you shop around - there's some outrageously
> priced AC power strips. You should be able to find one that's not
> so pricey if you know what you are looking for and shop carefully.
>
> -- Tom, N5EG
>
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