[time-nuts] GPS antenna selection - lightning

Glenn Little WB4UIV glennmaillist at bellsouth.net
Sat Aug 6 09:46:08 EDT 2016

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.


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

Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

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