"Mohd Nazry Bin Mustapa":
Anyone know how to make a simple lightning arrester
(Homebrew) that really work in case of lightning.

"David Robbins":
the most basic one is a spark gap. these have been
used since the first days of long telegraph lines.
just position two sharp pointed metal pieces a small
distance apart, connect one side to the cable and the
other to a good ground. you want the distance as small
as possible, but wide enough so your normal transmission
power doesn't create an arc.

The usual practice for radio antennas is to place
a series capacitor downstream (towards the radio
set) from the spark gap to dispense with the DC
and low-frequency components of the lightning strike.

In crude, fixed-pitch ASCII art, it would look like
this:
| |
Antenna ---------+--------| |----------- To Radio
| | |
SPARK V Blocking
GAP ^ Capacitor
|
Ground ---------+----------------------

The size of the capacitor is a compromise between not
disrupting the RF circuitry and coupling the low-frequecy
energy from the strike into the radio. Making the
capacitor reactance in the order of a few ohms at the
lowest operating frequency generally should work for
50-ohm coax.

Jim, K7JEB, Glendale, AZ

| |
Antenna ---------+--------| |----------- To Radio
| | |
SPARK V Blocking
GAP ^ Capacitor
|
Ground ---------+----------------------

PS: The breakdown voltage of the capacitor should be
10 times that of the spark gap. For a 1KV spark gap,
that would give 10 KV.

JEB

K7JEB wrote:

| |
Antenna ---------+--------| |----------- To Radio
| | |
SPARK V Blocking
GAP ^ Capacitor
|
Ground ---------+----------------------

PS: The breakdown voltage of the capacitor should be
10 times that of the spark gap. For a 1KV spark gap,
that would give 10 KV.

JEB

2uF at 10kV, quite a capacitor. That would be 6 ohms or so on
topband. 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.
The best we can hope for is to dissipate charge build up on the
aerial 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. A spark gap that can conduct a lightening strike would
be the size of a small truck.

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

vy 73

Andy, M1EBV

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.

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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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

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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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

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

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