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Re: [TowerTalk] Lightning suppression through coax loops

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Lightning suppression through coax loops
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Date: Fri, 28 May 2010 00:17:24 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

On 5/27/2010 9:27 PM, Gary Schafer wrote:
> Actually, Polyphaser recommended against putting loops in the coax line. The
> thought was that a loop would greatly increase the field and act as an
> antenna that would  increase the chances of induced current into other
> conductors.
>    
  The problem with loops, or I should say the potential problem with 
loops is lightning does not like to travel in circles.Give it a corner 
or curve and it's likely to get off the conductor and go some where else.
   I seriously doubt the explanation of the field and antenna theory. It 
sounds great and loops close to each other do couple, but the coax 
itself forms a much larger antenna to radiate, or be coupled to than 
does a one or two turn loop at the bottom.
> It is also recommended not to parallel any lines from one side of the
> protector/ground point with lines on the other side such as lines going into
> the house from the protection/ground panel.
>
>    
Parallel lines do couple as well, but how would some one get the lines 
on one side of their SPG/bulkhead to parallel lines on the other side?  
Well with a poor installation I can see lines running up one side and 
then back down the other side and end up parallel for a short distance 
defeating the SPG to some extent.

The main idea though is to ground the shield at the top and bottom of 
the tower. Then runs the cables to the bulkhead and SPG at the house 
entrance.  Coiling the coax before it's grounded is a good way to make 
lightning more unpredictable than it's normally unpredictable self.

73

Roger (K8RI)
> 73
> Gary  K4FMX
>
>    
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com [mailto:towertalk-
>> bounces@contesting.com] On Behalf Of Wes Attaway (N5WA)
>> Sent: Thursday, May 27, 2010 9:58 AM
>> To: n4zr@contesting.com; TowerTalk@contesting.com
>> Subject: Re: [TowerTalk] Lightning suppression through coax loops
>>
>> I believe I remember that the old Polyphaser manual had some info about
>> coax
>> loops and bends.  The idea is simple, and makes sense, because the
>> grounding
>> at the tower and at the entrance to your house, etc., is creating a
>> voltage/current divider that will, ideally, shunt most of the energy to
>> ground before it gets to your house.
>>
>> The Polyphaser manual explained that loops and bends in coax runs toward
>> the
>> point of entrance add inductance to that path and cause it to be
>> incrementally less attractive for the lightning energy.
>>
>> I see no reason to doubt this because it is simply a practical application
>> of Ohm's Law.
>>
>>
>> ------------------ Wes Attaway (N5WA) ------------------
>> 1138 Waters Edge Circle - Shreveport, LA 71106
>>      318-797-4972 (office) - 318-393-3289 (cell)
>>          Computer Consulting and Forensics
>> -------------- EnCase Certified Examiner ---------------
>>
>>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Pete Smith
>> Sent: Thursday, May 27, 2010 7:10 AM
>> To: TowerTalk@contesting.com
>> Subject: [TowerTalk] Lightning suppression through coax loops
>>
>>
>>
>> 73, Pete N4ZR
>>
>> The World Contest Station Database, updated daily at
>> www.conteststations.com
>> The Reverse Beacon Network at http://reversebeacon.net, blog at
>> reversebeacon.blogspot.com
>> I bought an Ameritron RCS-10 antenna switch at Dayton, and in reading
>> the manual (please, no giggling) I note that it calls for a two-turn
>> loop in each antenna coax line just before entering the relay box.
>> These are described as "drip and lightning retarding loops." The manual
>> is quite prescriptive (for example, "keep coils spaced from each other
>> by vertical or horizontal separation of 2" minimum"), and I get the
>> "drip" part, but I wonder what the real, practical effect of these loops
>> would be.  Is there enough inductance to offer any practical blocking
>> effect for induced voltages resulting from a nearby strike?
>> _______________________________________________
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