[Hallicrafters] Antenna Lightning Protection

[Bob Macklin]

In the 80's I was the chief engineer on a NASA telescope on a 10K ft
mountain near Tucson. This place is a lightening magnet.

I received a grant from NASA for a lightning protection study.

We ended up with a LARGE knife switch that would break all lines between the
internal wiring and the power into the building including the ground. All
the incoming lines had gas discharge clamps and semiconductor (Transorbs) on
them.

There is a CONE OF PROTECTION. We put a ham radio crankup tower in the
corner near the building and ran it up during thunderstorms. This protected
the telescope building from a direct hit.

This facility also had a NASA tracking station used for the Space Shuttle
program.

Bob Macklin
K5MYJ
Kent (Seattle), Wa,
"Real Radios Glow in the Dark"

----- Original Message ----- 
From: "Glen Zook" <gzook at yahoo.com>
To: <hallicrafters at mailman.qth.net>; "Waldo Magnuson" <magnuson at mac.com>
Sent: Tuesday, January 06, 2009 8:14 AM
Subject: Re: [Hallicrafters] Antenna Lightning Protection


> I do regular presentations on lightning protection and r.f. grounding.
You can find synopsis of my presentations (in Word format) and some
rudimentary diagrams at
>
> http://k9sth.com/Page_2.html
>
> Scroll down to the heading "Grounding Articles" and the first 4 links are
appropriate.  There are definitely several ways to accomplish a good
grounding system and what I recommend is just one of those.  However, my
recommendations are among the cheapest, if not "the" cheapest, ways to
achieve a good grounding system because you can fabricate most of the
devices yourself for a fraction of what they cost from commercial sources.
Now the websites for the commercial manufacturers often do offer some very
good information on grounding.  Of course the methods described "just
happen" to use the devices manufactured by that company.
>
> I do recommend installing dissipation devices in addition to a proper
grounding system.  There are instructions as how to build your own devices
at a cost under $10 each rather than purchasing such devices from commercial
sources that generally cost several hundred dollars each.  The ones that you
make yourself will probably not be as "pretty" as the commercial sources but
they do work.
>
> Now there is nothing now known to man that can prevent a lightning strike.
However, dissipation devices do reduce those chances considerably.  There
are those who say that such devices are "snake oil" and there are those who
swear by them.  I am among the latter.  Those companies who manufacture the
dissipation devices often will "guarantee" that you will "never" take a
strike.  But, if you do take a strike then they usually say that you did not
install the devices correctly.  As I said before, there is nothing that can
prevent a strike from possibly happening.  However, you can greatly reduce
that chance.
>
> I live 1/2 block from the highest point in the City of Richardson, Texas,
and although no where near as bad as Florida, we definitely get our share of
lightning.  The top antenna on my main tower is 67 feet above ground (see
http://k9sth.com/uploads/newantenna.JPG for photos) and in over 36 years of
the tower being installed I have never taken a lightning strike.  The "pole
pig" (electric company distribution transformer) that is about 40 feet from
the tower and about 40 feet lower than the tower has been struck.  Also, my
across the street neighbor has lost 3 trees and a chimney to lightning but
none of my antennas have ever been struck.  Now that is not to say that I
will never take a strike for, again, there is nothing now known that will
prevent a strike absolutely.  But I am a firm believer in dissipation
devices.
>
> In the past, when I was not retired, I oversaw the installation of
dissipation devices on over 200 two-way radio and microwave radio towers
ranging from around 100 feet to over 500 feet tall here in the State of
Texas.  Some of those towers recorded several lightning hits per year and
after the devices were installed none of the towers were hit, at least
during around 10 years that I kept track of them.  But, again, there is
nothing that will prevent a strike absolutely.
>
> You do have to install a proper ground system, there is no question as to
that.  Then adding dissipation devices is an added protection.  The ground
system comes first and then add dissipation devices.
>
> As I pointed out before, there are several ways to get a good ground
system.  The system that I recommend has been adopted by a couple of
television transmitter manufacturers and by at least one agency of the U.S.
government.  Of course the systems recommended by most of the manufacturers
of grounding equipment work well, they are just relatively expensive to
employ.
>
> Remember that commercial radio installations have to operate 24/7/365 and
they do not have the ability to disconnect the antennas during storms.  The
vast majority of those installations do not suffer damage from lightning
because of proper grounding systems and amateur radio operators need to take
note.
>
> Glen, K9STH
>
> Website:  http://k9sth.com
>
>
> --- On Mon, 1/5/09, Waldo Magnuson <magnuson at mac.com> wrote:
>
> From: Waldo Magnuson <magnuson at mac.com>
>
> I just read an article on gas discharge tubes (GDTs) and again thought I
should have some kind of lightning protection for my radios other than (when
I remember) disconnecting my antenna when I'm not using it.  What do others
have for lightning protection (if any)?  Any recommendations?  GDTs sound
good.
>
>
>
> ______________________________________________________________
>