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Re: [TowerTalk] Radiating Lightning Rod

To: <>
Subject: Re: [TowerTalk] Radiating Lightning Rod
From: Rick Stealey <>
Date: Tue, 2 Jun 2009 13:20:07 +0000
List-post: <">>
 Jim says:
> I run each coax to the bottom of the tower
> and have a 6-8 turn Coax coil on each line before it goes into the equipment
> box at the base of the tower. from there all the antenna coax and control
> cables go underground in PVC pipe and come up in the wall behind my
> operating desk.

If there is lightning induced current coming down the coax lines (in parallel 
with current coming down the tower legs themselves) the inductance of the coil 
causes a large voltage to appear across the coil.  This can flash to the tower 
easily and likely destroy the coax.  
I believe the proper thing to do is to install the coax so it gets grounded 
right at the tower base.  In other words, assume the lighting current is going 
to flow on the coax and we want that current to get into the earth by a path 
that we determine.
Assuming in your equipment box (you didn't say) you are bonding your coax lines 
to a good ground, then it is likely that the majority of the strike current is 
dissipating at the tower location and only a small portion will find its way to 
your house.  But to protect the equipment in the house you really should be 
grounding and providing lightning arrestors outside, at the point where the 
conductors enter the house.  

Rick  K2XT

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