On Mon, 12 Nov 2007 14:33:10 GMT, "Nick" wrote:

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

Hi Nick,

No, it wouldn't.

Make the antenna shorter, and surround it with taller, nearby grounded
vertical conductors for the lightning to select in preference. For
more protection, connect the tops of the taller conductors over the
antenna.

Of course, this advice reduces to putting the antenna in a grounded
cage that takes the hit. Unfortunately it also renders the antenna
deaf.

Moral: Trying to stop the lightning from hitting your antenna also
stops RF.

[Hint: if you are going to stop it with a super glom of insulation,
like fiberglass, consider that this insulation is inferior to a
bajillion miles of air already there surrounding the antenna. That
doesn't slow down lightning much does it?]

73's
Richard Clark, KB7QHC

On Mon, 12 Nov 2007 14:33:10 GMT, "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

The popular solution seems to be the Alpha-Delta grounding antenna
switches. Unfortunately, There does not seem to be one that can be
operated remotely.

John Ferrell W8CCW
"Life is easier if you learn to
plow around the stumps"

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