[TowerTalk] Protecting a Tower Relay Box

[Roger (K8RI)]

On 8/17/2010 8:10 PM, john at kk9a.com wrote:
> The best thing you could do is shorten your control wire and mount the relay
> at the tower base.
>
Or within reach of a tall step ladder.

73

Roger (K8RI)
> John KK9A
>
>
>
> To:<TowerTalk at contesting.com>
> Subject: [TowerTalk] Protecting a Tower Relay Box
> From: "Mark Robinson"<markrob at mindspring.com>
> Date: Tue, 17 Aug 2010 19:40:13 -0400
>
> 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
>
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