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@mindspring.com> wrote:
> From: Mark Robinson <markrob@mindspring.com>
> Subject: [TowerTalk] Protecting a Tower Relay Box
> To: TowerTalk@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¤tURL=/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
>
> _______________________________________________
>
>
>
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