In , Lancer
wrote:

On Sun, 15 Feb 2004 15:04:05 -0800, Frank Gilliland
wrote:

In , Lancer
wrote:

On Sun, 15 Feb 2004 15:58:03 -0500, w_tom wrote:

A person who so poorly protected his own home as to suffer
completely unnecessary computer and TV damage will now teach
me? One who even posted the classic urban myth about concrete
damage to prove Ufer grounding does not work? You just
realized something: someone on the other side does have a few
decades of experience and engineering degrees. If you had
one, then the concept of resistance and impedance would have
been correctly posted. However someone even did read 'tower
talk' - and posted citations from 'tower talk' in direct
contradiction to your posted myths. Well at least you are not
posting personal attacks this time. The world can get better.

In the meantime this is a discussion about the OPs antenna
mast; not a forum for personal attacks. The OP must earth
his antenna mast both for lightning protection AND as required
by the National Electrical Code. That answers his question.
Please feel free to address the purpose of this thread - the
Original Poster's original request for information -
Zeeeeeeee3 originally posted:

It has several times, which you have chosen to ignore. Use proper
grounds and disconnect his equipment from the antenna and mains.
Your answer is use proper grounds, but don't disconnect any equipment.
Now which one makes more sense? Which one would better protect his
equipment? Which one offers more protection?


Hey Lancer, don't make it too simple. It's all about "impedance", don'cha know?


Couldn't I get a correct impedance match with a 1/4 wave of bus bar?
Now what did he say the frequency of lightning was?


I don't think he did, but if you post an arbitrary value I'm sure he will
provide you with the correct information. I -do- know that lightning is
monitored by listening to the Schumann (sp?) resonance, which is a constantly
changing frequency down around 8 Hz. So let's see, we would need a ground strap
that is resonant over a frequency range of, say, around 1 to 20 Hz..... so how
much money are you willing to spend on this little project? Because the only way
I see of doing this is with a megawatt negative impedance converter!







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Frank Gilliland wrote:
In , Lancer
wrote:

On Sun, 15 Feb 2004 15:04:05 -0800, Frank Gilliland
wrote:

In , Lancer
wrote:

On Sun, 15 Feb 2004 15:58:03 -0500, w_tom wrote:

A person who so poorly protected his own home as to suffer
completely unnecessary computer and TV damage will now teach
me? One who even posted the classic urban myth about concrete
damage to prove Ufer grounding does not work? You just
realized something: someone on the other side does have a few
decades of experience and engineering degrees. If you had
one, then the concept of resistance and impedance would have
been correctly posted. However someone even did read 'tower
talk' - and posted citations from 'tower talk' in direct
contradiction to your posted myths. Well at least you are not
posting personal attacks this time. The world can get better.

In the meantime this is a discussion about the OPs antenna
mast; not a forum for personal attacks. The OP must earth
his antenna mast both for lightning protection AND as required
by the National Electrical Code. That answers his question.
Please feel free to address the purpose of this thread - the
Original Poster's original request for information -
Zeeeeeeee3 originally posted:

It has several times, which you have chosen to ignore. Use proper
grounds and disconnect his equipment from the antenna and mains.
Your answer is use proper grounds, but don't disconnect any equipment.
Now which one makes more sense? Which one would better protect his
equipment? Which one offers more protection?


Hey Lancer, don't make it too simple. It's all about "impedance",
don'cha know?


Couldn't I get a correct impedance match with a 1/4 wave of bus bar?
Now what did he say the frequency of lightning was?

I don't think he did, but if you post an arbitrary value I'm sure he will
provide you with the correct information. I -do- know that lightning is
monitored by listening to the Schumann (sp?) resonance, which is a
constantly changing frequency down around 8 Hz. So let's see, we would
need a ground strap that is resonant over a frequency range of, say,
around 1 to 20 Hz..... so how much money are you willing to spend on this
little project? Because the only way I see of doing this is with a
megawatt negative impedance converter!

You guys are all over this topic and it's really blowing my hair
back.

Can you guy's condense it to your opinion of the best/cheapest
way to ground lets say..an omni on a roof-top or tower? Best
being a relative term.

I'm sure the advice will save at least one person from getting
blasted, and make people aware that you can't just put a hunk
of metal in the air without considering lightning.

Thx.

--
Go 40 42 12

In ,
wrote:

snip
You guys are all over this topic and it's really blowing my hair
back.

Can you guy's condense it to your opinion of the best/cheapest
way to ground lets say..an omni on a roof-top or tower? Best
being a relative term.

I'm sure the advice will save at least one person from getting
blasted, and make people aware that you can't just put a hunk
of metal in the air without considering lightning.

Thx.


Ok......

First, sink a ground rod at the point where the coax will enter the house. If
you have a basement next to the ground rod, sink a couple more rods so they are
separated by ten feet or more and in the path of the coax. Some people like to
prep the ground by soaking with sal****er, but in my experience that makes the
rod corrode before its time, then the salt leeches away into the ground water,
leaving a very poor ground in a very short time. I use galvanized pipe as
opposed to copper rods because they have a larger diameter (more rod-to-ground
contact = lower resistance), and they last longer. You can also thread the pipe
for a super-neat installation of a waterproof box......

Next is the coax installation. Run the coax down the mast or side of the house
to the ground rod. Don't run the coax near any wiring inside the house. You can
detect house wiring with a cheap metal detector. Avoid sharp turns as much as
possible. At the ground rod it helps to have a waterproof box because you need
to cut the coax, ground the shield, and shunt the center conductor to ground
with a choke (as per the diagram I made yesterday).

About the choke: This serves two purposes. First, it shunts static electricity
from the antenna to ground. Second, it provides a path for lightning if it
should strike. Since the lightning will arc across every loop in the choke, the
inductance value isn't critical just as long as it is high enough to block your
RF (about 1 mH or larger for HF and above), and the wire size is large enough to
handle some current (#14 or larger should be fine). One of those heavy-duty hash
chokes for ignition noise is ok, or you can wind your own -- use a large iron
bolt for a core and wind about 50 turns of #10 or #12 house wire. If you aren't
running much power, you can slit the insulation along the length of the coil so
it will arc at a lower voltage.

Then run the coax up into the house along side the grounding strap. Tie them
together with cable-ties if you want. Again, it's important that you run these
so they don't come close to any house wiring, and they should enter at a
location that is clear of easily combustible stuff. Terminate the ground strap
with a really big alligator clip, jumper cable clamp, or whatever you have that
makes a really good connection and can be easily disconnected. The ground clamp
from an arc welder is almost ideal.

Above the point where the coax and grounding strap enter the house, make a hook
or post where you can hang both when not being used. Remember that if lightning
hits, it's very possible that these will jump straight out from the wall and
dance around like a water hose, so make sure they are held securely in place.

Inside the house, make yourself a grounding bus bar of copper or aluminum. Put
this on the back of your bench and use it to ground all your equipment. To this
you clamp on your grounding strap. When not using your bench, unhook the
grounding strap along with the coax and stow it away. Also, to protect the coax,
use an appropriate socket and short it out before you stow it.

When should you unhook your antenna? There is a thing called the 30-30 rule: If
you hear thunder less than 30 seconds after you see the lightning, unplug. Don't
plug in again until 30 minutes after the last thunder. That's pretty safe. You
can even improve on that by building a lightning detector, many of which will
indicate lightning even before you can hear the thunder.


How's that?

Oh, I almost forgot..... coax length!!!!! The low impedance of the ground will
be reflected at the radio when the length of the coax & ground strap, from the
ground rod to the radio, are 1/2 wavelength. This means 1/2 wavelength -without-
consideration of velocity factor because we want a low impedance -ground-. And
this means -- you guessed it -- 18 feet of coax!







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Frank Gilliland wrote:
First, sink a ground rod at the point where the coax will enter the
house. If you have a basement next to the ground rod, sink a couple more
rods so they are separated by ten feet or more and in the path of the
coax. Some people like to prep the ground by soaking with sal****er, but
in my experience that makes the rod corrode before its time, then the
salt leeches away into the ground water, leaving a very poor ground in a
very short time. I use galvanized pipe as opposed to copper rods because
they have a larger diameter (more rod-to-ground contact = lower
resistance), and they last longer. You can also thread the pipe for a
super-neat installation of a waterproof box......

Next is the coax installation. Run the coax down the mast or side of the
house to the ground rod. Don't run the coax near any wiring inside the
house. You can detect house wiring with a cheap metal detector. Avoid
sharp turns as much as possible. At the ground rod it helps to have a
waterproof box because you need to cut the coax, ground the shield, and
shunt the center conductor to ground with a choke (as per the diagram I
made yesterday).

About the choke: This serves two purposes. First, it shunts static
electricity from the antenna to ground. Second, it provides a path for
lightning if it should strike. Since the lightning will arc across every
loop in the choke, the inductance value isn't critical just as long as it
is high enough to block your RF (about 1 mH or larger for HF and above),
and the wire size is large enough to handle some current (#14 or larger
should be fine). One of those heavy-duty hash chokes for ignition noise
is ok, or you can wind your own -- use a large iron bolt for a core and
wind about 50 turns of #10 or #12 house wire. If you aren't running much
power, you can slit the insulation along the length of the coil so it
will arc at a lower voltage.

Then run the coax up into the house along side the grounding strap. Tie
them together with cable-ties if you want. Again, it's important that you
run these so they don't come close to any house wiring, and they should
enter at a location that is clear of easily combustible stuff. Terminate
the ground strap with a really big alligator clip, jumper cable clamp, or
whatever you have that makes a really good connection and can be easily
disconnected. The ground clamp from an arc welder is almost ideal.

Above the point where the coax and grounding strap enter the house, make
a hook or post where you can hang both when not being used. Remember that
if lightning hits, it's very possible that these will jump straight out
from the wall and dance around like a water hose, so make sure they are
held securely in place.

Inside the house, make yourself a grounding bus bar of copper or
aluminum. Put this on the back of your bench and use it to ground all
your equipment. To this you clamp on your grounding strap. When not using
your bench, unhook the grounding strap along with the coax and stow it
away. Also, to protect the coax, use an appropriate socket and short it
out before you stow it.

When should you unhook your antenna? There is a thing called the 30-30
rule: If you hear thunder less than 30 seconds after you see the
lightning, unplug. Don't plug in again until 30 minutes after the last
thunder. That's pretty safe. You can even improve on that by building a
lightning detector, many of which will indicate lightning even before you
can hear the thunder.

How's that?

Oh, I almost forgot..... coax length!!!!! The low impedance of the ground
will be reflected at the radio when the length of the coax & ground
strap, from the ground rod to the radio, are 1/2 wavelength. This means
1/2 wavelength -without- consideration of velocity factor because we want
a low impedance -ground-. And this means -- you guessed it -- 18 feet of
coax!

Very informative Frank, make sure we can reference that.

Dunno if average joe will completely comply, but he can't say you
didn't worn him! We pushed poles in the ground with the bobcat and
post hole digger, mostly for lightning. Out here where I live, by
the time the fire dept gets here with the tanker (no hydrants)you're
toast.

Ground is good. (like you said)

--
Go 40 42 12

In ,
wrote:

..... We pushed poles in the ground with the bobcat and
post hole digger, mostly for lightning. Out here where I live, by
the time the fire dept gets here with the tanker (no hydrants)you're
toast.


Here's a little trick if you use a pipe for a ground rod: Thread both ends of
the pipe. On the top put a fitting that will accept a garden hose. On the bottom
put a reduction fitting (to be used as a nozzle). Hold the pipe vertical, turn
on the water full blast, then let the water drill the hole. When you are done
just unscrew the top fitting, and PRESTO!!! A great ground rod without a lot of
fuss.

BTW, this doesn't work very well in areas where there are a lot of large rocks
in the ground.....






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Frank Gilliland wrote:
In ,
wrote:

..... We pushed poles in the ground with the bobcat and
post hole digger, mostly for lightning. Out here where I live, by
the time the fire dept gets here with the tanker (no hydrants)you're
toast.

Here's a little trick if you use a pipe for a ground rod: Thread both
ends of the pipe. On the top put a fitting that will accept a garden
hose. On the bottom put a reduction fitting (to be used as a nozzle).
Hold the pipe vertical, turn on the water full blast, then let the water
drill the hole. When you are done just unscrew the top fitting, and
PRESTO!!! A great ground rod without a lot of fuss.

BTW, this doesn't work very well in areas where there are a lot of large
rocks in the ground.....

That's a slick idea, we're sandy loam and clay around here. Next
time I sink a ground rod I'll remember the water.

--
Go 40 42 12

If in sandy loom, then a single ground rod may not be
sufficient. Neighborhood history will apply. Previous
lightning damage in the last ten years? If so, then the
single point ground may be expanded with more rods; spaced as
Frank suggests and to comply with NEC. Other alternatives
include looping the house with a buried bare copper wire. But
again, this is typically only required for high 'strike
frequency' locations - more a function of neighborhood
geology.

A problem with the water idea is a loose ground rod. A
ground rod must be firm in ground when installed. A loose
ground rod is not earthed. Ground rod is further compromised
if using threaded joints. Ground rod should be monolithic
until well below frost line.

If antenna is not located near to service entrance and
single point ground, then antenna may require its own earth
ground. This in addition to the coax ground. IOW either the
antenna is part of your structure and earthed at the service
entrance ground; or antenna is earthed as if a lightning
rod. If the antenna connection to earth ground is
significantly shorter than connection to service entrance,
then antenna must also have its own earth ground rod located
as directly under the antenna as possible. This so that
lightning takes a short path to earth; does not seek
alternative paths via other items such as chimney or interior
wire.

If installing for commercial broadcaster reliability, then
the inductor from center core is additional protection. But
most industry professionals say the center conductor will leak
sufficiently to the outer shield making no center conductor
connection necessary. IOW that ground block sold in Home
Depot or Radio Shack (to earth only outer shield to single
point earth ground) is more than sufficient protection for
most residences. Again, neighborhood history will apply.
Inductor adds only minor improvement; a function of local
history and other considerations.

Disconnecting to protect equipment is unreliable because
humans are not reliable. Humans are only available only 1 in
three hours - and that assumes humans are home often.
Protection must be installed virtually 24 hours every day and
must be fully sufficient even when using the equipment.
Disconnecting is just convenient extra protection made
unnecessary by properly earthing.

Again, you have soil that typically makes poor earth
grounds. This will be especially a problem if more conductive
earth lies beneath - such as limestone. Ground rod would need
be deeper to make contact with that limestone. If geology
changes beneath building, then that too can create earthing
problems. Point being the best earth ground must be the
single point earth ground.

If using multiple rods, then those rods need be connected by
buried bare copper wire. Some do this by digging a hole, then
driving ground rod into bottom of that hole. A four or six
inch plastic pipe lines the hole. Buried bare copper wire
clamps to earth ground rod AND can be inspected through that
covered plastic pipe. Integrity of that wire to rod clamp is
important.

Forget about salting the earth. Some have lined 'buried
copper wire' trench with better material such as trailings
from a steel mill. This tends to improve the transition from
buried copper wire to earth while not destroying the copper.
Tailings are a superior idea to salt since salt will leach
away before the year is gone. But most don't bother. They
simply bury the wire.

Notice the concept. The most critical and essential feature
of any protection 'system' is defined by that single point
earth ground. The quality of that earth ground and how
connections are made to that central earth ground determines
system effectiveness. Single point grounding is the most
critical component in a protection system.

wrote:
That's a slick idea, we're sandy loam and clay around here. Next
time I sink a ground rod I'll remember the water.

--
Go 40 42 12

A benchmark in this technology is Polyphaser. These
application note applies to your questions:
http://www.polyphaser.com/ppc_PEN1002.asp
http://www.polyphaser.com/ppc_PEN1024.asp
http://www.polyphaser.com/ppc_PEN1026.asp
http://www.polyphaser.com/ppc_PEN1025.asp
http://www.polyphaser.com/ppc_PEN1003.asp

wrote:
That's a slick idea, we're sandy loam and clay around here. Next
time I sink a ground rod I'll remember the water.

From: (Frank=A0Gilliland)
In ,
wrote:
..... We pushed poles in the ground with the bobcat and post hole
digger, mostly for lightning. Out here where I live, by the time the
fire dept gets here with the tanker (no hydrants)you're toast.
_
Here's a little trick if you use a pipe for a ground rod: Thread both
ends of the pipe. On the top put a fitting that will accept a garden
hose. On the bottom put a reduction fitting (to be used as a nozzle).
Hold the pipe vertical, turn on the water full blast, then let the water
drill the hole. When you are done just unscrew the top fitting, and
PRESTO!!! A great ground rod without a lot of fuss.
BTW, this doesn't work very well in areas where there are a lot of large
rocks in the ground.....

_
The hose in the pipe method works very well. It is standard procedure
down here to do what you suggested when installing
pvc sprinkler systems that must pass under walkways, driveways, etc.
You mentioned sal****er...folks have been known to pour bagged salt
around their tower, as well, although down here you really don't need
it, as the water table is easily accessible at 3 to 5 feet. It's
practically impossible to have a rod here that ISN'T in the water
table....but I prefer dragging the copper line in the Gulf behind the
boat,,,,.remember,,,, N3CVJ said if you're gonna break the law, (dxing
is technically against the law on cb) 'tis better to do it from a
portable station than from your home.

In ,
(Twistedhed) wrote:

From: (Frank*Gilliland)
In ,
wrote:
.... We pushed poles in the ground with the bobcat and post hole
digger, mostly for lightning. Out here where I live, by the time the
fire dept gets here with the tanker (no hydrants)you're toast.
_
Here's a little trick if you use a pipe for a ground rod: Thread both
ends of the pipe. On the top put a fitting that will accept a garden
hose. On the bottom put a reduction fitting (to be used as a nozzle).
Hold the pipe vertical, turn on the water full blast, then let the water
drill the hole. When you are done just unscrew the top fitting, and
PRESTO!!! A great ground rod without a lot of fuss.
BTW, this doesn't work very well in areas where there are a lot of large
rocks in the ground.....

_
The hose in the pipe method works very well. It is standard procedure
down here to do what you suggested when installing
pvc sprinkler systems that must pass under walkways, driveways, etc.
You mentioned sal****er...folks have been known to pour bagged salt
around their tower, as well, although down here you really don't need
it, as the water table is easily accessible at 3 to 5 feet. It's
practically impossible to have a rod here that ISN'T in the water
table..


Now isn't that just special..... as if anyone cares about your mud.


..but I prefer dragging the copper line in the Gulf behind the
boat,,,,.remember,,,, N3CVJ said if you're gonna break the law, (dxing
is technically against the law on cb) 'tis better to do it from a
portable station than from your home.


And, of course, there is no reason to doubt his word on the subject.







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