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Re: [TenTec] If you ground it - it will come!

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>,<geraldj@storm.weather.net>
Subject: Re: [TenTec] If you ground it - it will come!
From: "Stuart Rohre" <rohre@arlut.utexas.edu>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 5 May 2006 14:57:05 -0500
List-post: <mailto:tentec@contesting.com>
Lynn makes a good point.  Our club station helper grounded every rig 
negative and every chassis to earth bus.  Of course there was coax to the 
VHF/UHF rig.  The lightning surge came down the shield of the coax from the 
tower, into the radio on coax connector and back to AC ground thru the DC 
negative copper of the circuit board, (until that vaporized).  We had 
created a ground loop.  In this particular hit, the AC ground looked lower 
impedance than the bronze strap bus,and its connection to cold water pipe 
just outside the wall.  (2 foot of braid to it).

How you treat grounds can be a damaging situation.

Total disconnection of the coaxes at entry to building when not in use would 
have make a bigger spark gap for the current to cross than the circuit board 
did.

We had survived a direct hit on the power pole 100 feet across the parking 
lot some years before.  The 65 foot tower usually discharges the 
surroundings to its earth rods.

Stuart
K5KVH 


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