[TowerTalk] Relay box location

[NPAlex at aol.com]

Mark,
 
I would strongly recommend not locating the relay at the 80ft level on your 
 tower unless you enjoy climbing, on a cold winter night, during a contest 
or  other inopportune time. Because that is when the relay will fail.  
Locate  it at ground level where it is easily accessible.  Been their and done  
that
 
Norm W4QN
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Message:  3
Date: Tue, 17 Aug 2010 19:40:13 -0400
From: "Mark Robinson" _markrob at mindspring.com_ 
(mailto:markrob at mindspring.com) 

I am  intending to fit this relay box at the 80 foot level on my tower

_http://www.arraysolutions.com/Products/dualfeed.htm#top%20of%20page_ 
(http://www.arraysolutions.com/Products/dualfeed.htm#top%20of%20page) 

I  planned on using wire like this to feed 12V to the  relay

http://www.lowes.com/pd_314364-20424-55269-S4-08_4294821905_4294937087?produ
ctId=3128549&pl=1&currentURL=/pl_Electrical%2BWire%2Band%2BCable_4294821905_
4294937087_?cm_cr=Electrical-_-Web%20Activity-_-Electrical_A1_Activity-_-SC_
Electrical_Area1-_-19604_1

since  it was readily available and cheap. I know that I don't need wire 
this  
thick but it is cheap. I plan on using a cheap Radio Shack 12V psu in the  
shack. I  don't want this cable tied into my expensive Astron 12V  supply 
which could be damaged by lightning and then feed the pulse into  any other 
equipment tied to the shack 12V DC bus.

I am planning on  protecting the 12V line with "MOV Metal Oxide Varistor 
24Z50 Harris 100J"  on each line to ground at the base of the tower and at 
my 
SPG box. Adding  some inductance just before the entry to the house might 
help too.  I  started thinking about this and was figuring that it might 
help 
to ground  the 12V return wire to the tower at the top and bottom of the 
tower and at  the SPG box. I wouldn't need MOV's on that return line then. 
I 
am not sure  if this will provide any benefit from lightning. Taking this 
thought a bit  furrther, maybe I could run the power down the tower using 
some old coax.  The center conductor would carry the 12V positive and the 
return would be  on the shield which would be grounded at the top and 
bottom 
of the tower  and at the SPG box. Will using coax in this way provide any 
benefit over  the wire from Lowes



thanks  Mark  N1UK