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Re: [TowerTalk] CATV & Phone grounds

To: JC Smith <>,TowerTalk <>
Subject: Re: [TowerTalk] CATV & Phone grounds
From: Red <>
Date: Tue, 11 Jul 2006 11:02:21 -0500
List-post: <>
Hi, JC;

I had been pondering your earlier post regarding need for a perimeter 
ground or loop.  PolyPhaser made an argument in their earlier book, 
Grounds for Lightning Protection, for this and I observe that commercial 
installations use a perimeter ground.  I don't recall the reasoning.  
Perhaps someone on this list can enlighten me and others.

Meanwhile, it sounds to me like your system ties utility and station 
grounds  together.  A consideration is minimizing impedance between 
them.  Copper pipe should be better than wire.  I think the  soldered 
joints are probably ample in area and they are water cooled, and both 
the resistance at RF and the inductance are less than what smaller wire 
would present.  Is the routing of the  pipe reasonably straight?  Are 
the tower and station grounds composed of several ground rods or other 
contacts spread over an ample area?  Might you improve the utility 
ground by adding some rods, spaced at twice their depth?  You don't want 
one ground point to be poor with respect to another.

This lightning protection issue is always a probability game.  You can't 
reach 100% safety and you must trade-off cost of additional features vs 
their added protection.  Unfortunately, I can't quantify the added 
protection of some of those features.

73 de Red

JC Smith wrote:

>It makes sense that all grounds be tied together, but a question is how?  

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