On 15 Dec 2003 14:33:27 -0800, (Mark Keith) wrote:

Andy Cowley wrote in message
As I understand it, there is nothing that can work if a direct lightening strike occurs. We are talking megavolts and thousands of amps.
Way beyond anything an amateur could build.

Sure, but for only a short duration. There is plenty the average ham
can do to reduce damage.

The best we can hope for is to dissipate charge build up on the
aerial

Useless....Not much hope in that tactic.

and ensure that there is no more than a kilovolt or so at
the input to the rig caused by the (field) effects of a nearby
strike.

Actually, I think just a run of coax itself will reduce the potential
to a few hundred volts before it gets to the rig.

A spark gap that can conduct a lightening strike would
be the size of a small truck.

A 10 gauge wire can safely conduct a lightning strike to ground. But
you must have a good low resistance connection to ground. If not, the
wire will be burnt toast.

The only way to make sure you have a working station after a
lightening strike on your aerials is to take out good insurance.

Insurance won't do any good for the existing gear. Proper setup to
avoid damage, or disconnecting is a better idea. I take strikes around
here all the time. Two were direct strikes to my mast in the last 4
years. I had no damage at all to anything, and I was sitting 15 ft
from the base of the mast both times at this puter. Didn't flinch at

All my antenna systems ground to the tower. The tower is thouroughly
grounded into a network of ground rods and #2 bare copper.

The cables come into the house through underground conduit where they
are again grounded and run through PolyPhasers.
http://www.rogerhalstead.com/ham_files/cablebox.htm

I need to add some photos that show the grounding at the tower base.
Each leg is grounded through an 8' ground rod and the bare #2 radiates
out from there for a minimum of 80 feet with ground rods spaced about
8 to 16 feet, depending on what's in the way.

There are crossing cables that also bond the cables and one run that
parallels the conduit into the house with at least 5 ground rods along
its length. It also ties into the old ground system for the original
90 foot tower. All joints are Cad Welded except the tie to the tower
legs which use cable clamps to attach the cable to the leg. Then the
cable is gracefully bent at the base to curve out to the first ground
rod in the series.

It took a direct hit late this past summer with no harm to any
equipment. I say direct hit as my neighbor happened to be looking at
the tower when the strike hit. He was impressed. :-))
I just tell the neighbors it's the neighborhood lightening rod and
after that I think they believe me.

http://www.rogerhalstead.com/ham_files/tower.htm The view (third row
from the bottom) is from the back yard of the above neighbor near our
lot line.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com
Return address modified due to dumb virus checkers


all. MK