Anyone know how to make a simple lightning arrester (Homebrew) that really
work in case of lightning.

Hang up "STOP" sign.

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Anyone know how to make a simple lightning arrester (Homebrew) that really
work in case of lightning.

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


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.

NOTE: a lightning arrester WILL NOT WORK if you don't have a good ground.
IT IS NOT A REPLACEMENT FOR A GOOD GROUND SYSTEM! All a lightning arrester
does is limit the voltage difference between signal carrying wires and the
nearby ground it is connected to, you must properly connect all grounds
together to get any benefit from any kind of lightning arrester.

David Robbins wrote:
SNIP

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.
SNIP

Remember, there is still a significant voltage across the spark gap
before it ignites and during conduction. A 1/16 inch, or a 1.5 mm, gap
will sustain ~1000 volts before igniting and support several hundreds of
volts during conduction.

The best solution, disconnect all antennas when not in use.

DD, W1MCE

"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.

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
...
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

Nonsense. Every insulated AM broadcast station antenna has an arc
gap at the base. How many stations get struck by lightning each year
and keep on operating?

Pete