CW wrote:
Effective lightning protection can be done in the amatuer station for a
reasonable cost. Most though, don't do so.

My costs have always been reasonable - I unplug the antenna
when not in use. I don't use it during thunderstorms. I have
lived in extreme lightning areas with zero problems.
--
73, Cecil http://www.qsl.net/w5dxp



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CW wrote:

Effective lightning protection can be done in the amatuer station for a
reasonable cost. Most though, don't do so.
"Andy Cowley" wrote in message
...

As I understand it, there is nothing that can work if
a direct lightening strike occurs.

How? How do you deal with thousands of amps? It's for certain sure that
a simple spark gap will be blown to kingdom come in the first millisecond,
so what happens in the next millisecond? and the one after...........

I think your method must be untried, untested and 'whistling in the dark'.

Andy, M1EBV

Cecil Moore wrote:

CW wrote:
Effective lightning protection can be done in the amatuer station for a
reasonable cost. Most though, don't do so.

My costs have always been reasonable - I unplug the antenna
when not in use. I don't use it during thunderstorms. I have
lived in extreme lightning areas with zero problems.


All good stuff, Cecil, but I'd say that was lightening avoidance
not protection. I still don't believe there is an effective method
of lightening protection for an amateur station that will accept a
direct strike and survive. Even your method would probably result
in a fried antenna ;-) Hope you never find out!

vy 73

Andy, M1EBV

If it weren't possible, millions of dollars of radio equipment would go up
in smoke every year. There are places that, if you have a tower, you WILL
get hit on a regular basis. If you would like to know something about it, do
a search on this group for Gary Coughman. Also, take a look at the
Polyphaser web site. Before you start accusing someone of not knowing what
they are talking about, you would be well advised to ensure that it is not
you that is ignorant.


"Andy Cowley" wrote in message
...
CW wrote:

Effective lightning protection can be done in the amatuer station for a
reasonable cost. Most though, don't do so.
"Andy Cowley" wrote in message
...

As I understand it, there is nothing that can work if
a direct lightening strike occurs.

How? How do you deal with thousands of amps? It's for certain sure that
a simple spark gap will be blown to kingdom come in the first millisecond,
so what happens in the next millisecond? and the one after...........

I think your method must be untried, untested and 'whistling in the dark'.

Andy, M1EBV

Andy Cowley wrote:
All good stuff, Cecil, but I'd say that was lightening avoidance
not protection. I still don't believe there is an effective method
of lightening protection for an amateur station that will accept a
direct strike and survive. Even your method would probably result
in a fried antenna ;-) Hope you never find out!

I've been back in Texas for about 5 years now and the only thing
that has gotten fried was a five-foot-tall live oak tree, the
shortest thing around. Go figure. It's still struggling to stay
alive with half its branches dead and a burn mark down the trunk.
--
73, Cecil http://www.qsl.net/w5dxp



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http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

"Andy Cowley" wrote in message
...
CW wrote:

Effective lightning protection can be done in the amatuer station for a
reasonable cost. Most though, don't do so.
"Andy Cowley" wrote in message
...

As I understand it, there is nothing that can work if
a direct lightening strike occurs.

How? How do you deal with thousands of amps? It's for certain sure that
a simple spark gap will be blown to kingdom come in the first millisecond,
so what happens in the next millisecond? and the one after...........

I think your method must be untried, untested and 'whistling in the dark'.

Andy, M1EBV

lightning doesn't go on for milliseconds, 50 micro-seconds is a relatively
long stroke. 30kA can go through a 12ga copper wire with no damage for
10-20 microseconds. in most cases there will actually be very little
voltage between wires of a coax or twin lead just because their insulation
will break down or the feedpoint of the antenna will arc over... both are
naturally occuring spark gaps that actually work very well to protect
equipment from direct strikes. assuming of course the tower and feedline
have good grounds. where people have problems is they don't ground the
shield of the coax to a single point ground along with the power lines, so
they get differential voltages between grounds that has no place to go but
through the equipment. properly grounded installations with relatively
small arresters to limit voltage on the center conductor of the coax
relative to the shield are very effective. for tube type receivers a simple
spark gap is adequate, for transistorized stuff you may need lower voltage
protection and should probably get something commercially made for the job.

"David Robbins" wrote in message
...

"Andy Cowley" wrote in message
...
CW wrote:

Effective lightning protection can be done in the amateur station for
a
reasonable cost. Most though, don't do so.
"Andy Cowley" wrote in message
...

As I understand it, there is nothing that can work if
a direct lightening strike occurs.

How? How do you deal with thousands of amps? It's for certain sure that
a simple spark gap will be blown to kingdom come in the first
millisecond,
so what happens in the next millisecond? and the one after...........

I think your method must be untried, untested and 'whistling in the
dark'.

Andy, M1EBV

lightning doesn't go on for milliseconds, 50 micro-seconds is a relatively
long stroke. 30kA can go through a 12ga copper wire with no damage for
10-20 microseconds. in most cases there will actually be very little
voltage between wires of a coax or twin lead just because their insulation
will break down or the feedpoint of the antenna will arc over... both are
naturally occurring spark gaps that actually work very well to protect
equipment from direct strikes. assuming of course the tower and feedline
have good grounds. where people have problems is they don't ground the
shield of the coax to a single point ground along with the power lines, so
they get differential voltages between grounds that has no place to go but
through the equipment. properly grounded installations with relatively
small arresters to limit voltage on the center conductor of the coax
relative to the shield are very effective. for tube type receivers a
simple
spark gap is adequate, for transistorized stuff you may need lower voltage
protection and should probably get something commercially made for the
job.

I've seen a common spark plug used to provide a spark gap for antennas.
Setting the gap to about .05 inches will conduct much of the current away
from the down stream circuitry. Some have suggested a few turns of the
Coax after the gap will provide enough inductance to deter conduction past
the gap, but I haven't pursued that to establish it as fact. There is also
the problem of causing an impedance mismatch with an inductance in the line.
The gap being smaller than the spacing of the coax would seem to be enough
to minimize damage.

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. MK

Andy Cowley wrote in message I still don't believe there is an effective method
of lightening protection for an amateur station that will accept a
direct strike and survive.

There is, but most hams don't do it. Costs money, and everything has
to be set up just right. It's done the same way all other 24 hour
radio/tv stations, etc do it. How many commercial radio stations have
you heard that go off the air when lightning strikes their tower? Not
many I bet. We would never have reliable broadcast TV in this town if
that were the case.. :/ MK

On Mon, 15 Dec 2003 13:51:49 -0600, Cecil Moore
wrote:

Andy Cowley wrote:
All good stuff, Cecil, but I'd say that was lightening avoidance
not protection. I still don't believe there is an effective method
of lightening protection for an amateur station that will accept a
direct strike and survive. Even your method would probably result
in a fried antenna ;-) Hope you never find out!

I've been back in Texas for about 5 years now and the only thing
that has gotten fried was a five-foot-tall live oak tree, the
shortest thing around. Go figure. It's still struggling to stay
alive with half its branches dead and a burn mark down the trunk.

My system gets hit about 3 times a year. So far I've only lost the
front end out of a 2-meter rig and some coax. Since installing the
new tower I've not lost any radio gear, but I did get one computer
fried.

http://www.rogerhalstead.com/ham_files/tower.htm
shows the tower and antennas, but not the ground system.

There are currently 30, 8' ground rods and over 600 feet of bare #2
copper tying the whole works together.

Unfortunately we had to have some septic work done. When digging out
the tank they hooked the ground system. Pulled out a section of the
basement wall and cracked a whole bunch of it. The wall is
temporarily repaired, but we are going to have to replace the entire
wall this coming season.


IF you have a fast connection the view from the top of the tower
http://www.rogerhalstead.com/ham_files/tower.htm panorama.
It's over 19 megs and would take forever on dial up.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com
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