Thierry wrote:

SNIPPED

HI,

Good to read : http://www.astrosurf.org/lombry/qsl-...protection.htm

Personnaly, in my humble opinion, under thundery weather there is no better
solution than unpluging all electronic devices...

Thierry, ON4SKY

Agree! But, I still lost an ICOM 756 Pro II when disconnected from
antenna,
and had the power supply unplugged. A ground loop in the external ground on
the 756 and the power supply, where 12 volt return is tied to chassis,
caused
damage to the power connector on the 756 and fried the 756 internal
cabling and
circuit boards were carbonized.

I'm still waiting for my insurance settlement.

MORAL: Lightning does what lightning does!

"Ham op" wrote in message
...
Thierry wrote:

SNIPPED

HI,

Good to read :
http://www.astrosurf.org/lombry/qsl-...protection.htm

Personnaly, in my humble opinion, under thundery weather there is no
better
solution than unpluging all electronic devices...

Thierry, ON4SKY

Agree! But, I still lost an ICOM 756 Pro II when disconnected from
antenna,
and had the power supply unplugged. A ground loop in the external ground
on
the 756 and the power supply, where 12 volt return is tied to chassis,
caused
damage to the power connector on the 756 and fried the 756 internal
cabling and
circuit boards were carbonized.

I'm still waiting for my insurance settlement.

MORAL: Lightning does what lightning does!


For sure, as soon as there is a sink, a path of lower resistance, the
lightning will find it and will follow it to your most expensive accessory..
This canal can be the coaxial, the house cabling system, even yourself if by
mistake you touch a metallic device during the thunder. Even the ground as
state in my article can be an excellent way for the lightning to strike your
installation. Hence it is better to entrust this installation to experts.

So I when I say to unplug all devices, this is *all* cabling system,
including grouding.

Usually the insurance do an excellent job and you should be able to rebuy
all your defective devices.

Good luck.
73
Thierry, ON4SKY

Jerry wrote:
"I know about some articles on the ARRL site, but was wondering if
anyone else had some ideas or pointers on how to pratically do this?"

Coax helps protect your radio from lightning. It rejects common-mode
currents inside which might otherwise damage the radio.

Thunderstorms often produce lightning from clouds charged to 100 million
volts with respect to the earth. Current may oscilate up to 200 thousand
amps in a lightning discharge. Temperature inside the stroke may reach
30 thousand degrees C (5x the temperature of the sun`s surface).

A stroke starts and stops abruptly, so it contains r-f in addition to
d-c. The discharge may take up to 150 milliseconds and consist of
several flashes in both directions. It may include a path
miles long, so it has a pretty good ionization trail for an antenna.

If your antenna is struck by lightning, it is best to bypass the energy
aroundb people and equipment.

Medium wave stations have arc-gaps around the tower base insulators,
Faraday screens between primary and secondary of tower r-f coupling
transformers, and tower lighting chokes which keep both r-f and
lightning out of the power mains.

High frequency stations often use balanced wire lines, and these have an
arc-gap from each wire to the earth at a point outside the station.

VHF, UHF, and microwave stations use grounded antennas and coax. Towers
which support the antenna generally have each tower leg separately
grounded by a heavy cable to its own ground rod near the tower base. R-F
cables and waveguide are grounded at the antenna and at least at the
base of the tower. Coax nay be coiled with several turns between the
tower base and the shack to discourage lightning on the outside of the
coax from entry to the shack. Waveguide is solidly bonded to the tower
but not usually coiled to make a lightning choke.

The solid-state VHF, UHF, or microwave station often needs additional
surge protection because of the difference in potential between electric
service and antenna system grounds
This takes the form of husky r-f chokes in each power wire to the r-f
equipment. Each choke is shunted at each end to ground with a capacitor
and with a voltage limiting device or devices, often MOV`s. There are
ready-made brute force coil and capacitor low-pass pi-filters which need
only addition of MOV`s to make them effective lightning suppressors. I
made mine in an earlier time using Miller Coil Company tower lighting
chokes and they worked well. You could wind 2 or 3 dozen turns of #12 or
#14 insulated wire in an 8-in. dia. circle to make your own 0.1
millihenry chokes. The standard choke used to be 2.5 millihenry, but it
is not critical.

The same wiring techniques required for noise reduction apply to the
biggest noise of all, lightning.

Best regards, Richard Harrison, KB5WZI

"Richard Harrison" wrote in message
...
Jerry wrote:
"I know about some articles on the ARRL site, but was wondering if
anyone else had some ideas or pointers on how to pratically do
this?"

Coax helps protect your radio from lightning. It rejects common-mode
currents inside which might otherwise damage the radio.

Thunderstorms often produce lightning from clouds charged to 100
million
volts with respect to the earth. Current may oscilate up to 200
thousand
amps in a lightning discharge. Temperature inside the stroke may
reach
30 thousand degrees C (5x the temperature of the sun`s surface).

A stroke starts and stops abruptly, so it contains r-f in addition
to
d-c. The discharge may take up to 150 milliseconds and consist of
several flashes in both directions. It may include a path
miles long, so it has a pretty good ionization trail for an
antenna.

If your antenna is struck by lightning, it is best to bypass the
energy
aroundb people and equipment.

Medium wave stations have arc-gaps around the tower base insulators,
Faraday screens between primary and secondary of tower r-f coupling
transformers, and tower lighting chokes which keep both r-f and
lightning out of the power mains.

High frequency stations often use balanced wire lines, and these
have an
arc-gap from each wire to the earth at a point outside the station.

VHF, UHF, and microwave stations use grounded antennas and coax.
Towers
which support the antenna generally have each tower leg separately
grounded by a heavy cable to its own ground rod near the tower base.
R-F
cables and waveguide are grounded at the antenna and at least at the
base of the tower. Coax nay be coiled with several turns between the
tower base and the shack to discourage lightning on the outside of
the
coax from entry to the shack. Waveguide is solidly bonded to the
tower
but not usually coiled to make a lightning choke.

The solid-state VHF, UHF, or microwave station often needs
additional
surge protection because of the difference in potential between
electric
service and antenna system grounds
This takes the form of husky r-f chokes in each power wire to the
r-f
equipment. Each choke is shunted at each end to ground with a
capacitor
and with a voltage limiting device or devices, often MOV`s. There
are
ready-made brute force coil and capacitor low-pass pi-filters which
need
only addition of MOV`s to make them effective lightning suppressors.
I
made mine in an earlier time using Miller Coil Company tower
lighting
chokes and they worked well. You could wind 2 or 3 dozen turns of
#12 or
#14 insulated wire in an 8-in. dia. circle to make your own 0.1
millihenry chokes. The standard choke used to be 2.5 millihenry, but
it
is not critical.

The same wiring techniques required for noise reduction apply to the
biggest noise of all, lightning.

Best regards, Richard Harrison, KB5WZI


An interesting fact that many don't know is that lightning actually
strkes upwards as the clouds are negatively charged.


--
Woody

harrogate2 at ntlworld dot com

Does anyone know of cases where houses have fried as a consequence of
ham wire antennas, "protected" or otherwise?

We all know of cases where electronics gets zapped but Jerry is
concerned about his house.

Be interesting to hear of actual cases, wouldn't it? Statistics would be
even better, but I won't hold my breath.

Chuck

Jerseyj wrote:
Hi all,
For years I lived in an apartment and just had antenna's in the attic ,
but now having moved to a house in a few months I'll be putting up a
10-160 wire type antenna in my trees. Given the recent spate of serious
thunderstorms, and the accompanying lightning, I'm a bit concerned about
properly grouding the antenna so that I don't fry the house *smile*. I
know about some articles on the ARRL site, but was wondering if anyone
else had some ideas or pointers on how to practically do this ?

Jerry

Chuck wrote:
"We all know of cases where electronics gets zapped but Jerry is
concerned about his house."

Ben Franklin promoted lightning rods to protect people and houses before
electronics was. These rods would not have sold had they not seemed to
work. Tell me a drowning man will grasp at straws!

Best regards, Richard Harrison, KB5WZI

On Mon, 18 Jul 2005 10:59:41 -0500, (Richard
Harrison) wrote:

Chuck wrote:
"We all know of cases where electronics gets zapped but Jerry is
concerned about his house."

Ben Franklin promoted lightning rods to protect people and houses before
electronics was. These rods would not have sold had they not seemed to
work. Tell me a drowning man will grasp at straws!

Best regards, Richard Harrison, KB5WZI


Franklin, defying the gods, performed his kite flying experiment in
June of 1752, and by late June or July, the first "lightning rods"
were installed on structures in Philadelphia. Ol' Ben kinda made up
his own "nec code".

bob
k5qwg

Chuck wrote:
"We all know of cases where electronics gets zapped but Jerry is
concerned about his house."

I`ve worked in many protected structures struck repeatedly by lightning
to their air terminals, rods, and towersm resulting in not one scintilla
of damage to occupants or equipment.

Transportation vehicles are struck by lightning every day and seldom
experience anything inside. An open convertible is not safe in a
lightning strike however.

Best regards, Richard Harrison, KB5WZI

Richard, we both know that a transportation vehicle makes a pretty good
Faraday[sp?] Cage.

Lightning attaching to a wire will instantly vaporize the wire.

Physical damage is generally caused by direct strike. The energy in the
action intergral [I^2*R*dt] generates local heat. The thermal shock
causes the damage. [And fire].

Richard Harrison wrote:
Chuck wrote:
"We all know of cases where electronics gets zapped but Jerry is
concerned about his house."

I`ve worked in many protected structures struck repeatedly by lightning
to their air terminals, rods, and towersm resulting in not one scintilla
of damage to occupants or equipment.

Transportation vehicles are struck by lightning every day and seldom
experience anything inside. An open convertible is not safe in a
lightning strike however.

Best regards, Richard Harrison, KB5WZI

Ham Op wrote:
"Physical damage is generally caused by direct strikes."

Lightning can produce awsome distruction from its millions of volts and
thousands of amps. Stories about it are informative, amusing, and
abundant.

Damage is mostly avoidable. High towers are nearly certain to be struck
repeatedly in passing thunderstotms. I`ve worked in medium wave
broadcasting, Short wave broadcasting, land-mobile radio, aircraft
radio, and microwave relay systems aplenty. I worked decades with a
worldwide corporation that had towers across the U.S.A. and several
other countries in the world. That corporation had its many towers
fitted with inverted Copperweld ground rods at the top to serve as
lightning rods to take most of the hits the towers received. At their
bottoms, the towers` lightning energy was shunted off to the earth
through ground rods driven into the soil around the towers. It worked.
There was no vaporized coax, tower lighting wires, or anything else.

We had to operate perpetually. We couldn`t pull the switch and throw the
coax out the window, even if someone were on hand to do so.

Evidence of lightnong strikes were the small pits it made in the
lightning rods.

Best regards, Richard Harrison, KB5WZI