[time-nuts] GPS antenna selection - lightning

Clay Autery cautery at montac.com
Sat Aug 6 11:00:22 EDT 2016


Is the 1987 version the latest issue available for free?

______________________
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 8/6/2016 8:46 AM, Glenn Little WB4UIV wrote:
> Cone of protection is addressed.
> Volume 1 is theory, volume 2 is application.
> The military requires 1/0 cable exterior to the building, commercial
> practice is #2AWG.
> Ground rod spacing is address.
>
> Overall a very good reference based on practical experience and backed
> with theory.
>
> 73
> Glenn
> WB4UIV
>
>
> On 8/6/2016 1:19 AM, Bill Hawkins wrote:
>> Hi Glenn,
>>
>> Your advice is excellent.
>>
>> Seems like every time we have a lightning discussion there is no
>> distinction between an EMP and a direct hit.
>>
>> I started work in 1960 at a blasting cap plant in upstate New York. The
>> powder magazines were protected by tall masts according to the "cone of
>> protection" theory. The angle of the cone varied between 45 and 60
>> degrees. The earth ground resistance of the mast was measured by a
>> hand-cranked device that looked like a megger but read earth resistance
>> to less than a tenth of an ohm. Had the lightning but never lost a
>> magazine.
>>
>> You say MIL-HDBK-419 covers EMP. Does it also cover cone of protection
>> for direct hits?
>>
>> I was fascinated by the idea that a simple capacitor discharge into an
>> inductor could be greatly enhanced by reducing the diameter of the
>> inductor with a conventional explosive, described in one of Stephen
>> Coonts' books, if my failing memory recalls correctly. And so I learned
>> what I could about EMP. Never built anything, just interesting behavior.
>>
>> Best regards,
>> Bill Hawkins
>>
>>
>> -----Original Message-----
>> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Glenn
>> Little WB4UIV
>> Sent: Friday, August 05, 2016 9:47 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts]GPS antenna selection - lightning
>>
>> A very good reference for EMP protection is MIL-HDBK-419.
>> This is downloadable for a number of web sources.
>> It is about 600 pages and is in two volumes.
>> This discusses a number of different sources of EMP such as nuclear and
>> lightning.
>> A lot is for protection of military industrial complexes, but, there is
>> a lot that pertains to us.
>>
>> I worked for a military complex that assembled nuclear missiles.
>> The site was built to this handbook specs.
>> We had no EMP related damage at the site.
>>
>> Number one rule, bond all grounds together. If something on your
>> property takes a hit, you want everything on your property to elevate to
>> the same level and the same rate.
>> If you have multiple, non bonded grounds, there is a different reference
>> for each ground. This is a major source for disaster.
>>
>> I spent seven years in lightning mitigation. I was told by professionals
>> that I was wrong. The third time that their tower was struck, destroying
>> all of the lights and attached equipment, they followed my
>> recommendations. That was ten years ago. The three hits were within four
>> months of each other. The site has been free of destructive hits since
>> then.
>>
>> 73
>> Glenn
>> WB4UIV
>>
>>
>>
>>
>




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