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Re: [RFI] Single-point grounding

To: Tom Thompson <tlthompson@qwest.net>
Subject: Re: [RFI] Single-point grounding
From: Pete Smith N4ZR <n4zr@contesting.com>
Date: Sun, 01 Jul 2012 13:42:15 -0400
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Sorry, I guess I should have made this clear - the lightning events in 
question have been nearby, not direct hits. I disconnect everything at 
the entry panel, an approach that has weathered one direct hit 
(everything on the tower was fried, but there was minimal damage in the 
house).

73, Pete N4ZR
The World Contest Station Database, at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at 
reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000 and
arcluster.reversebeacon.net, port 7000

On 7/1/2012 12:44 PM, Tom Thompson wrote:
> There is a 3 part series on the ARRL web site about lightening 
> protection.
>
> http://www.arrl.org/lightning-protection
>
> Tom   W0IVJ
>
>
>
> On 7/1/2012 8:28 AM, Pete Smith N4ZR wrote:
>> I'm not sure exactly where I should post this, but suspect that this
>> group probably has more relevant expertise than most, so please bear
>> with me.
>>
>> In the last year, I have had two expensive episodes.  In both cases, my
>> transceiver's RS-232 transceiver was fried during a lightning storm, and
>> several knowledgeable people suggested a difference in chassis potential
>> between computer and transceiver as the reason.  Their prescription for
>> avoiding a repetition was simple - connect the chassis of all of the
>> units to a single-point ground.
>>
>> My solution - which I'm asking people to critique - was to fabricate an
>> L-shaped, roughly 3x5 foot ground bus made from 3/4" copper tubing,
>> which I mounted on the back of my L-shaped operating desk. All joints
>> are silver-soldered. I then connected each of the affected units to the
>> bus with very short and heavy stranded wire, and connected the end of
>> the bus to my grounded shack entry panel (in a double-hung window).
>>
>> The DC resistance of the ground bus is very low, but the length
>> approximates a quarter wave on 10 meters, and with the units connected
>> near the ends of the bus, I wonder if I'm feeling a false sense of
>> security about the likely behavior of the bus during a nearby lightning
>> event.  Would I be better off (or no better) running heavy conductors
>> from each unit to the entry panel, even if they would have to be
>> similarly long? Or should I just give up and plan on disconnecting the
>> RS-232 connection whenever weather approaches?
>>
>> 73, Pete N4ZR
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
>>
>
>
>


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