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Re: [Amps] RF in the Audio

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Subject: Re: [Amps] RF in the Audio
From: "Paul Christensen" <>
Date: Mon, 26 Sep 2011 09:58:15 -0400
List-post: <">>
> If you want to know what is happening as you make changes you need to
> establish a set of benchmarks first. You and I have the test equipment to 
> do
> a lot of the measurements, most do not.

That's an important but often difficult step for most folks.  Myself, I've 
been tempted to proclaim the superior performance of my open line dipole 
with its symmetrically balanced remote ATU.  The truth is that I really 
don't know how it's actually performing -- only how *I think* it's 
performing   I have never established a baseline of performance, starting 
with a simple dipole, then adding a balun at the feedpoint, moving to 
various unbalanced tuners, then link-coupled tuners, and finally testing 
performance of my current antenna system.

One thing I do know is that I will always limit the use of open wire line to 
areas external to the home.  Unless the home does not have switch-mode 
electronic appliances, there's no way I would be satisfied with open or 
ladder line anywhere inside the home.  And today, who can live in a home 
without a lot of slick, noise-generating appliances?  I'm always on "RFI 
patrol "to eliminate or minimize these noise sources.

Even if the line is truly balanced, that balance would exist in 
transmission, but not necessarily in receive.  Why?  Noise sources arrive at 
different directions to the line.  Some noise is broadside to the line, 
other sources are perpendicular to the line.  The line will not be immune 
through perfect balance to all noise sources around a 360 degree arc. 
Twisting the line as suggested in the early literature may help but it 
doesn't take much imbalance to bring the noise out of a null.

Paul, W9AC

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