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Topband: Gamma matching crank-up tower

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Subject: Topband: Gamma matching crank-up tower
From: (Tom Rauch)
Date: Thu, 24 Oct 2002 19:54:43 -0400
> Why does it screw things up ??
> I am curious, since running the cables inside my tower is not an
> option since the tower is kept down when I'm not will go up
> and down many times a week.

When cables are passed down through the tower center, the tower forms 
a less-than-perfect Faraday cage and the cables are not excited 
nearly as much as when hanging on the outside. Bad luck also might 
bring unwanted resonances in the hanging cable system, and that could 
be avoided with the cables inside the tower.

Problems would vary with every installation, just like when using a 
Sloper antenna fed against a tower. I have no idea how often it would 
be a real problem, but I certainly see how it could go either way. I 
would guess that RF into rotor cables and such would be the most 
common problem when cables are dropped outside the tower away from 
the face.

Myself, I have shunt fed many many towers with cables taped to the 
outside of the legs without any problems at all. I have never hung 
cables several inches from the tower, that would be much worse!73, 
Tom W8JI 

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