[TowerTalk] Protecting a Tower Relay Box

[GALE STEWARD]

I'll add my comments which agree with the others advising you NOT to mount the relay box 80ft up the tower. I had to climb my tower once at dusk during the CQWW CW contest to swap out a failed relay box. At least I had a spare. By the following weekend, I had it mounted down at 5ft! It takes a few more coax runs but it's well worth it. Even in bad WX, you can repair something if it's at ground level.

GL with the project!

73, Stew K3ND




--- On Tue, 8/17/10, Mark Robinson <markrob at mindspring.com> wrote:

> From: Mark Robinson <markrob at mindspring.com>
> Subject: [TowerTalk] Protecting a Tower Relay Box
> To: TowerTalk at contesting.com
> Date: Tuesday, August 17, 2010, 7:40 PM
> 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
> 
> 
> 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?productId=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
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>