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Author Topic: Grounding for an RV "shack" with a short  (Read 419 times)
KD7PML
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Posts: 5




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« on: July 01, 2002, 05:22:40 PM »

G'day. New ham here. I have just purchased an Hustler 2M antenna so that I can make my RV-Trailer a shack of sorts. I have put up a short tower so that I can clear the local flora and am in the process of running the coax. My question: since I'm running off of a battery bank and ( as yet ) nothing is grounded - what is the best ( and or most expedient ) solution? I believe that I need a ground, but the mobile ham radio that I'm using  dosen't have a ground per se. So.. what's a lightning fearing, signal wanting fellow to do?
Thanks in advance
Al
KD7PML
Oregon
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WB2WIK
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Posts: 20543




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« Reply #1 on: July 01, 2002, 06:13:06 PM »

A station ground doesn't do much for lightning protection, but if having one makes you feel better, you're in a far better situation for "earthing" than most, since your station must be located fairly close to real ground.

I'd just slam a standard copperclad 8' ground rod (available at all electrical supply houses) into the earth in some convenient place beneath or near the trailer and find the shortest possible path to run a heavy cable or strap from the antenna supporting mast or tower to that rod.  The rig itself doesn't need any kind of ground.

WB2WIK/6
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K9KJM
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Posts: 2416




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« Reply #2 on: July 05, 2002, 01:42:48 AM »

"A station ground doesn't do much for lightning protection?"  WORST advice I have heard all year!  
Usually WB2WIK has decent tips. Ignore this one!  You want the BEST ground possible to avoid any lightning damage. You don't say if the RV is going to be mobil or not. If not, check the information in the "tech notes" at the POLYPHASER website for GOOD lightning protection info. If you are going mobil, Just do the best you can. A few short rods is many times better than nothing!  Lightning bolts come in all sizes, from really small that most any ground will take care of, To the really BIG BOLT that can vaporize number 6 copper wire!  This is where lots of the "old wives" tales start, Just because so and so got a direct hit and had such and such a ground system, that is the REAL answer. With lightning protection, there is no such thing as 100 %, But with a good installation, it gets really close.   Good Luck!
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WB2WIK
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Posts: 20543




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« Reply #3 on: July 08, 2002, 06:55:19 PM »

K9KJM: I've done a lot of research on this (lightning protection and hazards), and consulted with some of the leading experts in the industry, including K9STH, and I stand by my statement, "a station ground doesn't do much for lightning protection."

A station ground doesn't.

In fact, having a station ground has been proven a leading cause of lightning related damage to electronic equipment.

Problem is: A station ground has nothing to do with a lightning ground.  Lightning will take the lowest impedance path to earth; if that path happens to be through your equipment, because you've grounded it very well, then -- oh well!  

Far better to have excellent _antenna system_ grounds, far away from the station equipment, and leave the equipment floating.  This is much more recommended than any other approach, unless a truly effective, low-impedance SPG can be employed.  That is a costly exercise, and not worth the investment for most amateurs.  

A great article on this very subject is in this month's (July 2002) QST magazine.  If you read it carefully, what I have stated does follow the theory in the text.

WB2WIK/6
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