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Re: [TowerTalk] Lightnig Arrestors at tower base or house entrance?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Lightnig Arrestors at tower base or house entrance?
From: K4SAV <RadioIR@charter.net>
Date: Tue, 26 Feb 2008 12:58:23 -0600
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
...."Is it because of some overvoltage issue on the shield? Maybe 
letting the coax be the sacrificial fuse (i.e. let it arc
through the jacket) might be a good approach?".....

That is exactly what you are trying to avoid by grounding the coax to 
the tower.  Replacing all the coax on a tower after a lightning strike 
is a difficult way to implement a fuse.  Pin holes in the coax jacket 
means death of the coax shortly after due to water entrance.

Jerry, K4SAV

Jim Lux wrote:

>Larry DiGioia N8KU wrote:
>  
>
>>Could someone please explain how you can ground a coax shield, on a 
>>continuous run down a tower, without letting moisture and humidity get 
>>into it? Thanks!
>>
>>Larry N8KU
>>    
>>
>
>Waterproof N connectors, Female/Female Barrel/bulkhead feedthrough 
>that's grounded?
>
>or
>
>Strip outer insulating jacket off, wrap clamp around, solder, cover 
>thoroughly or pot it?
>
>
>However, I don't know of a way to do it without cutting something.
>
>Something else to think about...
>
>What's the goal here?  Is it to provide a path from top to bottom of 
>tower for lightning? I would think the tower is a better path.  Is it to 
>  bleed off static type charges?  The shield ground back at the shack 
>will do that.  Is it to provide a path for induced current on the shield 
>from a nearby strike to get back to ground, without propagating to the 
>shack?  Given the fast rise time, maybe just wrapping the coax in a 
>grounded sheath is sufficient, and capacitive coupling through the 
>jacket will do the rest?  Is it because of some overvoltage issue on the 
>shield? Maybe letting the coax be the sacrificial fuse (i.e. let it arc 
>through the jacket) might be a good approach?
>
>Just some things to think about...
>
>
>Jim, W6RMK
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