On Nov 12, 12:46 pm, "JERD" wrote:
"Rick" wrote in message

...



I want to install a vertical, fed with an SGC230 at the bottom, but
concerned about minimising chance of a lightning strike on a bare
conductor.

Hi Nick,
There is virtually nothing you can do to prevent a strike hitting your
antenna.

Interesting topic!

I have a tall metal pole supporting one end of a long wire HF antenna. This
tall metal pole is set in 1 cu yard of concrete. Is this concrete suitable
for conduction into mother earth or should I run a large copper strap from
the pole to an earth rod?

JERD
VK5JE

Should be fairly good as is. Acts as sort of a "UFER" ground.
http://search.yahoo.com/search?p=ufe...p=mss&ei=UTF-8
I don't think adding another wire to ground would hurt anything,
but it's probably not needed to act as a decent lightning ground.
My mast is sitting directly into the earth. But I also run about
3 wires from the base of the mast to the ground system under
the mast, which is connected to all other grounds.
I've had two direct strikes that I know of, and they were non events.
The mast seemed to be fairly low resistance as the strikes were
very quiet. Or at least, thats one personal method I use to tell
if an object is a good lightning ground. A poor ground like a tree
will give a very loud crack as it strikes, and I'm not talking about
the sonic boom which occurs a very short time later. I'm
talking about the actual direct sound you hear from the strike,
which also gives a "click" to the auditory nerve if you are close
enough.
MK

On Nov 12, 8:33 am, "Nick" wrote:
Hi,
I want to install a vertical, fed with an SGC230 at the bottom, but
concerned about minimising chance of a lightning strike on a bare
conductor.

Would it give more protection / solve the problem, if I encased it
in a fibreglass yacht mast which I happen to have ?

I plan it to be approx 40' high with the top 25' being a fibreglass
yacht mast with the wire running up the inside. Top would be
insulated / sealed so no ions could spray out, attracting a strike
... am I going the right way ?

Thanks,
Nick

Like they say, a vertical taller than any other object is fair game
to lightning. Not really much you can do, except make sure
that the return to earth at the base of the mast is very well
grounded. You want it going to ground at the base of the antenna,
and not at some later point along the feedline. I would snub the
feedline to ground at the base, and run it along the ground the
rest of the way to the shack. Then at the shack, use the
usual "ground window" techniques with arresters, single
point grounding, etc..
The only thing I can think of that "might" slightly reduce the
chances of the antenna streaming would be to add a large
"ball" at the top of the whip. Along the same line as flag
poles.
And even thats no sure thing. ..
MK

Rick a écrit :
Is this concrete suitable for conduction into mother earth or should I run
a large copper strap from the pole to an earth rod?

Hi Jerd,
The latter, and you should have more than one if possible. The strap should
not have bends in it, should be low inductance (a copper strap is better
than a wire, etc.). Remember there are zillions of electrons coming down
that pole, and they all have to get into the earth, and all the ones in
front are being pushed by the ones in back, all screaming "Hurry up, or get
the hell outta the way, cause I gotta go...... real bad." And if they don't
get outta the way, the ones in back will jump around them like a New York
driver in a traffic jamb, to find a faster way to get where they are headed.
And you don't want that to happen because the other path may be through your
coax and into your house/equipment.



Now how does that portray the situation? That's the best I can do !

Awesome

--
Ker2x