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Re: [TowerTalk] Mounting Polyphaser to SPG

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Mounting Polyphaser to SPG
From: K4SAV <RadioIR@charter.net>
Date: Sat, 13 Jun 2009 10:38:25 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
W5KI wrote: As I build back the station, I intend to bring antennas and 
control lines to a SPG plate 15 feet from the house, with the surge 
protection units (polyphasers). ....

also: "Should the ground wire connecting the station/house system to the 
antenna SPG also be disconnected during storms (like the coax and other 
lines)?"

Unless you have a good ground system out away from the house to dump all 
that lightning current then you are a sitting duck either way.  If you 
have a good ground system at a remote tie point, then removing the 
ground between that point and the house along with all the cables is an 
option.  However I would not consider 15 feet to be a remote tie point.  
In that case I would leave the ground connected.  Lightning often has 
fingers that branch away from the main stroke channel.  At 15 feet 
separation this isn't a big jump. 

I never know what people mean when they say SPG.  If you have a tower 
and an associated ground system you should also have a tie point for all 
your cables at the base of the tower.  If you want to add surge 
suppressors at that point, that is an option.  You should also have a 
common tie point where the cables enter the house, and surge suppressors 
there are also an option.

If you have only wire antennas then you need to do some extra work if 
you are worried about lightning hits.  As you just found out you can't 
control lightning currents with a coax cable.   You will have to add 
masts and ground rods to carry the lightning currents and use crossed 
fingers for extra help especially when the dipoles are close to the house.

Jerry, K4SAV


Steve Norris wrote:
> Appreciate all these continued comments and opinions.  I am reading all with 
> much greater interest than last month.  I took a massive lightning hit here 
> in early May and I don't even have a tower up.  On the side of mountain 
> (hill) though and have a 18-inch diameter oak with the top half blown away to 
> remember it by.  Suffice it to say the low 160m dipole near that tree, and 
> the first 100 feet of coax connecting it to the antenna switch were 
> essentially vaporized (or blown to the next county.)  Past that point, not so 
> pretty either.  Lost just about all electronics in the house.
> All the ideas and discussion are priceless, whether good, bad, or 
> "agree-to-disagree" points.
>
> As I build back the station, I intend to bring antennas and control lines to 
> a SPG plate 15 feet from the house, with the surge protection units 
> (polyphasers).  This will be the disconnect point for all coax and control 
> lines during storms.  Over on the house side of this 15 foot separation, the 
> station ground system and electrical ground will be tied together.  At the 
> corner of the house closest to the antenna SPG, I plan to extend/retract 
> coaxes and control lines from the house to that antenna SPG.  So my QUESTION: 
>  Should the ground wire connecting the station/house system to the antenna 
> SPG also be disconnected during storms (like the coax and other lines)? 
>
> While researching, found this goverment PDF.  While not directed at RF 
> (rather power circuits), it has a lot of info on copper/aluminum/etc.,  
> issues of bonding dissimilar metals together, and touches on some points your 
> guys are making.  Found it while looking up info on Pentrox.  
> http://www.usbr.gov/power/data/fist/fist3_3/vol3-3.pdf
>
> Steve, W5KI
> _______________________________________________
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>   


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