[TowerTalk] running cables up the towe

Donald Chester k4kyv at hotmail.com
Mon Aug 28 16:57:13 EDT 2006

I run my open wire tuned feeders up through the middle of the tower.  The 
tower doubles as a quarter-wave vertical on 160, so running the feedline 
inside the tower improves isolation of the feeders when in the vertical 
antenna mode.  Also, the tower provides some shielding to the feedline when 
using the feeders and dipole.  The tower is on a base insulator, and when 
using the dipole hung at 119', I can ground or unground the tower across the 
base insulator with virtually zero effect on the tuning of the dipole.  The 
dipole acts as top loading for the vertical, so it is really more like a 
vertical tee than a simple quarterwave vertical, with measured base 
impedance on the order of a couple hundred ohms (plus substantial 
j-component), rather than 36 ohms purely resistive.

I would expect some reduction in lightning problems running any kind of 
feedline cable inside the tower rather than on the outside, plus I believe 
it would be mechanically more secure.

I space my feeders using strips of plexiglas mounted every 10', supported by 
the horizontal rungs of the tower.  While climbing the tower, I loosen up 
the feeders at the bottom end using turnbuckles, to allow my feet to extend 
unhampered inside the tower.

Don k4kyv

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