I always tell new Hams to ground everything they can.... but if they get a
direct hit then they will be too busy fighting fire to worry about the
antenna...

-Dave-
K5DRC Since 1969
BULL SHOALES LAKE
http://www.bullshoals.org/lake.htm
AR/MO STATE LINE

Some day someone will give a WAR and nobody will go

"Owen Duffy" wrote in message
...
On Fri, 16 Dec 2005 11:20:53 -0500, "Robert11"
wrote:

Hello:

Have been reading up on lightning a bit, and it certainly
is a confusing subject.

Let's say I have an Inverted-L or a Sloper in the yard (receiving only).

If a lightning storm is in the vicinity, obviously the best protection
possible is to just disconnect the radio from the antenna. No differences
of opinion here, I would imagine.

But, as a more or less theoretical question, to minimize the possibility
of
lightning hitting the antenna at all, or inducing large voltages in it, is
it better to just leave the now "floating" antenna alone, or is it better
to
ground one end of it ?

Why ?

You have to think carefully about what you are trying to protect.

It seems to me that in the event of a lightning stroke in the near
vicinity of your antenna, large voltages will be induced in the
antenna wrt "ground", whether or not your antenna or its support
structure features as a streamer, or takes the current from a leader.

That voltage may be sufficient for insulation breakdown, and charge
will flow to ground via some path, not necessarily of your choosing.
Substantial physical damage may occur where insulation breaks down,
the path of the side-flash current may result in further damage to
persons or equipment.

If you make a substantial connection from the feedline to some thing,
you have some degree of control over the path that the discharge
current flows. Properly chosen and implemented, that might be better
than doing nothing, but if poorly designed or implemented, it could be
worse than doing nothing. Side-flash can still occur where you have
provided a path to ground.

Very often, the target of effective lighting protection of radio
installations is minimisation of voltage drops or potential
differences internal to an installation as a result of lightning
discharge current rather than trying to minimise the voltage to
"ground" resulting from the current.

Owen
--

On Sat, 17 Dec 2005 01:48:24 -0600, " hillbilly3302"
wrote:

I always tell new Hams to ground everything they can.... but if they get a
direct hit then they will be too busy fighting fire to worry about the
antenna...

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This summer my 80 foot tower took a direct hit, the first in my 48
years of hamming. The tower was grounded and there was no fire, but it
tripped a circuit breaker in my house and damaged a radio connected to
it. My point is that fire is not an automatic consequence.

Incidentally, the sound of thunder from a hit that close is remarkably
different from a hit some distance away. First, you hear the clap from
the nearest part of the bolt and then from parts successively farther
away, a long, rolling sound that continues much longer than one at a
distance. If I don't ever hear it again, that will be ok by me. :-)

73, Bill W6WRT

Bill Turner wrote:

On Sat, 17 Dec 2005 01:48:24 -0600, " hillbilly3302"
wrote:


I always tell new Hams to ground everything they can.... but if they get a
direct hit then they will be too busy fighting fire to worry about the
antenna...


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This summer my 80 foot tower took a direct hit, the first in my 48
years of hamming. The tower was grounded and there was no fire, but it
tripped a circuit breaker in my house and damaged a radio connected to
it. My point is that fire is not an automatic consequence.

Incidentally, the sound of thunder from a hit that close is remarkably
different from a hit some distance away. First, you hear the clap from
the nearest part of the bolt and then from parts successively farther
away, a long, rolling sound that continues much longer than one at a
distance. If I don't ever hear it again, that will be ok by me. :-)

73, Bill W6WRT


Bill;

Ain't been there, Ain't done that, Don't want no stinkin t-shirt. ;^)

Seriously though glad that nothing really serious happened. When I was
in retain sales I sold many electronic items to people that suffered
both direct and indirect hits. Lots of damage no injuries everyone was
lucky.

Dave WD9BDZ

"Bill Turner" wrote in message
...
On Sat, 17 Dec 2005 01:48:24 -0600, " hillbilly3302"
wrote:
This summer my 80 foot tower took a direct hit, the first in my 48
years of hamming. The tower was grounded and there was no fire, but it
tripped a circuit breaker in my house and damaged a radio connected to
it. My point is that fire is not an automatic consequence.

Incidentally, the sound of thunder from a hit that close is remarkably
different from a hit some distance away. First, you hear the clap from
the nearest part of the bolt and then from parts successively farther
away, a long, rolling sound that continues much longer than one at a
distance. If I don't ever hear it again, that will be ok by me. :-)

73, Bill W6WRT

Long years ago, 50 yearsor so before I reached Ham status, a thunderstorm
awakened me in the wee hours and proceeded to dance around in the shallow
hill pasture near the house. Stroke after stroke occurred and all so near I
could hear a loud click as the strike occurred and then the diminishing
rumble. I still haven't figured out the initial click sound, it came from
outside so wasn't a house internal electric phenomenon.

Harold
KD5SAK

kd5sak wrote:

Long years ago, 50 yearsor so before I reached Ham status, a thunderstorm
awakened me in the wee hours and proceeded to dance around in the shallow
hill pasture near the house. Stroke after stroke occurred and all so near I
could hear a loud click as the strike occurred and then the diminishing
rumble. I still haven't figured out the initial click sound, it came from
outside so wasn't a house internal electric phenomenon.

I've read that this click is due to the ear's reaction to the strong
electromagnetic pulse. If that's what you heard, it comes from the ear
itself, not from outside.

Roy Lewallen, W7EL

"Roy Lewallen" wrote in message
...
kd5sak wrote:

Long years ago, 50 yearsor so before I reached Ham status, a
thunderstorm
awakened me in the wee hours and proceeded to dance around in the
shallow
hill pasture near the house. Stroke after stroke occurred and all so
near I
could hear a loud click as the strike occurred and then the diminishing
rumble. I still haven't figured out the initial click sound, it came
from
outside so wasn't a house internal electric phenomenon.

I've read that this click is due to the ear's reaction to the strong
electromagnetic pulse. If that's what you heard, it comes from the ear
itself, not from outside.

Roy Lewallen, W7EL

This is the first time I have seen it mentioned the ear reacting to the
electromagnetic pulse. Most of the time it is described as the same way
the old WW2 depth charges sounded in the submarines. YOu get the click and
then the boom. I forgot the term used but it is something like an impulse
or pressure shock wave traveling faster than the speed of sound and then the
actual sound wave.

Ralph Mowery wrote:

This is the first time I have seen it mentioned the ear reacting to the
electromagnetic pulse. Most of the time it is described as the same way
the old WW2 depth charges sounded in the submarines. YOu get the click and
then the boom. I forgot the term used but it is something like an impulse
or pressure shock wave traveling faster than the speed of sound and then the
actual sound wave.

I do believe that any mechanical wave, such as a pressure or shock wave,
travels at the speed of sound, no more and no less. To travel faster, it
would have to be an electromagnetic wave.

Roy Lewallen, W7EL

I do believe that any mechanical wave, such as a pressure or shock
wave,
travels at the speed of sound, no more and no less. To travel faster,
it
would have to be an electromagnetic wave.

Also, the deaf person wouldn't hear the mechanical wave. Well,
unless they had "some" hearing still available. If it was proven that
a totally deaf person could hear it, that would pretty much nail it
down as
electromagnetic. If that came out to be true, then Coffmans theory
about the auditory nerve picking it up would probably be true unless
some other nerve was actually involved.
MK

I've read that this click is due to the ear's reaction to the strong
electromagnetic pulse. If that's what you heard, it comes from the ear
itself, not from outside................................

According to old Gary Coffman posts, he says it's picked up by the
auditory nerve. Also, deaf people can hear that click.
I've had two strikes to my mast with me sitting 15 ft away from the
base of the mast. I could hear that click, but I also could hear
the arc sound of the strike going to ground outside. Sounded
like a light bulb being thrown to the ground outside my window.
Not that loud really. I'm fairly convinced the quality of the ground
connection effects the loudness of the strike. The strikes that hit
my well grounded mast are fairly quiet, not counting the overhead
sonic boom. The strikes to the trees in the yard are super loud
in comparison. A loud crack, instead of the quieter arc sound.
MK

wrote in message
oups.com...
I've read that this click is due to the ear's reaction to the strong
electromagnetic pulse. If that's what you heard, it comes from the ear
itself, not from outside................................

According to old Gary Coffman posts, he says it's picked up by the
auditory nerve. Also, deaf people can hear that click.


Thanks OM, I've wondered for nearly 50 years what the "click"
mechanism was. I've told the story several times, but never to anyone
I thought it would be useful to ask for an explanation of the "click".

Harold
KD5SAK