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[TowerTalk] Mr Harpole's 2 Recent Posts

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Subject: [TowerTalk] Mr Harpole's 2 Recent Posts
Date: Thu, 22 May 97 09:38:22
     Post #1
     The rig will probably suffer damage. The power ground is just one 
     ground rod which is insufficient to get all that energy into the 
     earth. A radial system, as described in our catalog (Appendix A) 
     is really what's needed. Nevertheless, you fail to indicate how 
     you connected to that ground rod. Anything less than #2 is not 
     going to work too well; even #2 is the bare minimum, with 2/0 the 
     suggested minimum if wire must be used. 1.5"-wide copper strap is 
     better than even 2/0. While 4/0 would be best (wire-wise), it is 
     probably more difficult to work with that than strap. Again, the 
     size of the connection is all but academic if you don't have a 
     good lightning ground.
     You need to protect all your I/Os: RF, telco, ac, etc. You didn't 
     indicate if these other I/O's were protected. Again, if not, 
     you'll probably have damage to the rig from one of those sources.
     Post #2
     Yes, you can disconnect everything as per VUD, but that will NOT 
     protect you. Is a tree conductive or grounded? No. Yet lightning 
     will go through a tree if it needs to. Lightning is a constant 
     current source and will develop as much voltage as it needs to 
     achieve its goal, which is to equalize the potential gradient 
     between the cloud and its mirror image on the earth. I believe 
     the Hustler is a shunt-fed (dc-grounded) antenna. This usually 
     helps in a lightning situation. What probably happened is that 
     the surge energy found its low inductance path to achieve its 
     goal (which, again, is potential equalization) without "seeing" 
     your equipment. Next time, it may "see" your equipment as the 
     desired path because the mirror image just discussed is located 
     at a location where your coax line and equipment is the desired 
     Realize that VUD is NOT controlling the path the surge energy 
     will take. So far this person has been lucky. At some point, his 
     lucky streak (pun intended) will end. By properly protecting and 
     grounding YOU control where the energy will go. That is the crux 
     of the PolyPhaser Philosophy.
     Of course VUD can increase his chances by installing a #1 Iron 
     golf club at the top of his tower. As Lee Trevino once exclaimed, 
     "not even God can hit a #1 Iron." (This IS a joke for those who 
     may think otherwise.)
     Hope this helps!
     Sincerely and 73,
     Bob Wanderer AA0CY
     Senior Applications Engineer
     PolyPhaser Corp.

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