Hello,

I understand single wire antenna wires should be grounded. I have also
heard it is a good idea to put a lightening arrestor on them. Can someone
tell me a good type of lightening arrestor to get and how they are
connected, please ?

Wayne

On Sat, 31 Jan 2009 00:10:26 -0500, Wayne wrote:

Hello,

I understand single wire antenna wires should be grounded. I have also
heard it is a good idea to put a lightening arrestor on them. Can someone
tell me a good type of lightening arrestor to get and how they are
connected, please ?

Wayne


Here is an example of how they are made and used.

http://www.geocities.com/n2uhc/lightningarrestors.html

Gnack

Hello,

I understand single wire antenna wires should be grounded. I have also
heard it is a good idea to put a lightening arrestor on them. Can
someone
tell me a good type of lightening arrestor to get and how they are
connected, please ?

Wayne


Here is an example of how they are made and used.

http://www.geocities.com/n2uhc/lightningarrestors.html

Gnack


Thank You Gnack,

Now I have a better idea what they are all about.

"Wayne" wrote in message
...
Hello,

I understand single wire antenna wires should be grounded. I have also
heard it is a good idea to put a lightening arrestor on them. Can someone
tell me a good type of lightening arrestor to get and how they are
connected, please ?

Wayne

Hey Wayne,

When I built a homebrew RF amplifier to help pick up weak SW signals, I put
something together that I have actually seen work when lightening struck
somewhere nearby. It consisted of a neon indicator light going from the
wire carrying the incoming signal to grount, and in parrallel with this I
put a 10K resistor (to bleed off static electricity at voltages below that
which would activate the neon indicator) and two 1N4001 diodes, configured
so that if one did not conduct the other would (picture two arrows sitting
next to each other and pointing in opposite directions.) Again, all of
these were in parrallel going from signal to ground, and then I put a .1uF
1000V ceramic disk capacitor going from the signal side of all this to the
input of my amplifier (or to the input to the radio, in your case.)

The theory is that the incoming signal will pass by all of this and go
through the .1uF capacitor to your radio, but a high-voltage pulse, such as
static electricity from someone touching the antenna wire or a nearby
lightening strike, will be stopped by the .1uF 1000V capacitor (make sure it
is a ceramic disk) and will be discharged by the neon indicator and one or
the other of the diodes, with tiny remnants of the pulse being blead off by
the 10K resistor. Now, please understand , I am no expert (which someone
will no doubt point out) but I actually saw this work one time when I was
listening to a SW station while a storm approached. I did not disconnect my
equipment before the storm got too close, and finally lightening struck
nearby and the neon indicator lit up for an instant. That convinced me it
was time! And I say that this whole thing worked because even though my
antenna picked up the pulse, it was discharged and my equipment did not
suffer any negative consequences. I saw the neon indicator light up
briefly, and when putting this thing together that was something I never
actually expected to see.

In my opinion, the only thing one has to worry about with this setup is
losing some signal through the diodes, the PN junctions of which act as
small capacitors connecting the signal line to ground. But I have not come
up with an answer to that yet. Nothing is perfect...

If this interests you, write to me and I will email the schematic for it.

Hope this helps. Take it easy...

Dave

wrote in message
...
On Sat, 31 Jan 2009 04:07:10 -0600, Gnack Nol
wrote:

On Sat, 31 Jan 2009 00:10:26 -0500, Wayne wrote:

Hello,

I understand single wire antenna wires should be grounded. I have also
heard it is a good idea to put a lightening arrestor on them. Can
someone
tell me a good type of lightening arrestor to get and how they are
connected, please ?

Wayne


Here is an example of how they are made and used.

http://www.geocities.com/n2uhc/lightningarrestors.html

Gnack

So the arrestor is grounded, not the antenna itself. I was puzzled
about that too, because if the antenna itself was grounded, all the
signals would go to ground. Now I do know that many years ago, when I
was still a teenager, I had an old tube radio, and it had an antenna
and a ground screw on the back. I recall that all too well, because
that thing had a hot chassis, and I grounded it to the water pipe in
the basement using speaker wire. When I turned on the switch there
was a bright flash and the speaker wire went up in smoke, which left a
nasty burn across my fingers as the glowing wire fell in my hand as I
reached to unplug it. I had molten plastic embedded in my skin, as
well as my father hollaring about all the smoke in the house. I
didn't use that old radio for a few years, but after I leaned more
about electronics, I discovered that the chassis was supposed to be
isolated from the metal case with rubber grommets, except they had
worn thru. Therefore the whole radio was hot. Kind of scarey how
they made things back then. From what I recall, it was an old
Halicrafters.

I did replace the grommets, and put a polarized plug on the end, as
well as put a capacitor to that ground screw.

These days they make this stuff safe, but dont provide an antenna
terminal, which means they dont perform as well. Ya just cant win!

LM

Just a note: in the absence of an antenna terminal, one could take a couple
feet of insulated wire and attach it to the incoming signal line, then wrap
a few inches around the whip antenna, effectively coupling the incoming
signal to the whip inductively. This is what I usually do, as it makes use
of the preamp between the whip antenna and the rest of the radio, giving you
better reception and audio.

Dave

wrote in message
...
On Sat, 31 Jan 2009 04:07:10 -0600, Gnack Nol
wrote:

On Sat, 31 Jan 2009 00:10:26 -0500, Wayne wrote:

Hello,

I understand single wire antenna wires should be grounded. I have also
heard it is a good idea to put a lightening arrestor on them. Can
someone
tell me a good type of lightening arrestor to get and how they are
connected, please ?

Wayne


Here is an example of how they are made and used.

http://www.geocities.com/n2uhc/lightningarrestors.html

Gnack

So the arrestor is grounded, not the antenna itself. I was puzzled
about that too, because if the antenna itself was grounded, all the
signals would go to ground.

snip

LM

Be careful how you're looking at that for your understanding, though.
Something that appears to be a DC ground, need not be an AC (RF) ground. So
if you had a long wire antenna, and wrapped some turns around the telescopic
or whatever, and then grounded the hanging end, you have not grounded the
signals, because the turns around the telescopic form an inductance, which
serves to couple the signals into the radio, by induction. There are
caveats, of course, such as how many turns in your 'coil', the diameter of
the winding, the diameter of the wire, and the frequencies of interest. If
you look at the schematics for typical RF input stages, particularly with
higher frequency receivers, you will often see a coil of just a couple of
turns of quite thick wire connected directly to the antenna socket, which
you may initially think represents a 'short' to the antenna. If you take it
a stage further and start getting up into UHF and low SHF, you will often
find a straight piece of wire or even print connected directly across the
antenna input. At these frequencies however, that apparent 'short' is
actually an inductance, and may well have a reactance of several tens or
hundreds of ohms at the frequency of interest.

I have a home-brewed interdigital filter for 1.2GHz ATV lookback notching,
and the input and output coupling 'coils' are a single half-turn loop of 1mm
wire. The actual 'L' elements are straight pieces of 6mm ally rod.

Arfa

wrote:
On Sat, 31 Jan 2009 04:07:10 -0600, Gnack Nol
wrote:

On Sat, 31 Jan 2009 00:10:26 -0500, Wayne wrote:

Hello,

I understand single wire antenna wires should be grounded. I have also
heard it is a good idea to put a lightening arrestor on them. Can someone
tell me a good type of lightening arrestor to get and how they are
connected, please ?

Wayne

Here is an example of how they are made and used.

http://www.geocities.com/n2uhc/lightningarrestors.html

Gnack

So the arrestor is grounded, not the antenna itself. I was puzzled
about that too, because if the antenna itself was grounded, all the
signals would go to ground. Now I do know that many years ago, when I
was still a teenager, I had an old tube radio, and it had an antenna
and a ground screw on the back. I recall that all too well, because
that thing had a hot chassis, and I grounded it to the water pipe in
the basement using speaker wire. When I turned on the switch there
was a bright flash and the speaker wire went up in smoke, which left a
nasty burn across my fingers as the glowing wire fell in my hand as I
reached to unplug it. I had molten plastic embedded in my skin, as
well as my father hollaring about all the smoke in the house. I
didn't use that old radio for a few years, but after I leaned more
about electronics, I discovered that the chassis was supposed to be
isolated from the metal case with rubber grommets, except they had
worn thru. Therefore the whole radio was hot. Kind of scarey how
they made things back then. From what I recall, it was an old
Halicrafters.

I did replace the grommets, and put a polarized plug on the end, as
well as put a capacitor to that ground screw.

These days they make this stuff safe, but dont provide an antenna
terminal, which means they dont perform as well. Ya just cant win!

LM


If ya really want to get some good info go to your public libray & look
for The ARRL handbook & there is also an ARRL antenna book. or you could
buy them also if want.
http://www.arrl.org/catalog/index.ph...nd+Propagation

"Dave" wrote in
netamerica:


wrote in message
...
On Sat, 31 Jan 2009 04:07:10 -0600, Gnack Nol
wrote:

On Sat, 31 Jan 2009 00:10:26 -0500, Wayne wrote:

Hello,

I understand single wire antenna wires should be grounded. I have
also heard it is a good idea to put a lightening arrestor on them.
Can someone
tell me a good type of lightening arrestor to get and how they are
connected, please ?

Wayne


Here is an example of how they are made and used.

http://www.geocities.com/n2uhc/lightningarrestors.html

Gnack

So the arrestor is grounded, not the antenna itself. I was puzzled
.....
worn thru. Therefore the whole radio was hot. Kind of scarey how
they made things back then. From what I recall, it was an old
Halicrafters.

I did replace the grommets, and put a polarized plug on the end, as
well as put a capacitor to that ground screw.

These days they make this stuff safe, but dont provide an antenna
terminal, which means they dont perform as well. Ya just cant win!

LM

Just a note: in the absence of an antenna terminal, one could take a
couple feet of insulated wire and attach it to the incoming signal line,
then wrap a few inches around the whip antenna, effectively coupling the
incoming signal to the whip inductively.

Unless both ends of that wire are connected, one to the antenna and the
other to ground, making this one winding of a transformer, you are
actually using _capacitive_ coupling. The wire is one plate of the
capacitor, the whip is the other plate and the insulation is the
dielectric. The body of the radio forms the plate of another capacitor
and the earth forms the second plate of that capacitor.

However, the name of the coupling mode is secondary to the fact that it
will provide stronger signals. However, connecting the antenna directly to
the whip will also work, and unless you take special precautions to
protect against lighting, direct or capacitive coupling are both almost
equally hazardous.

This is what I usually do, as
it makes use of the preamp between the whip antenna and the rest of the
radio, giving you better reception and audio.

Dave
7w-110V light bulb
antenna -----|------UUU-------|-|------------antenna terminal of rx
neon NE2 ^ v diodes opposite pollarity.
ground ------|----------------|-|------------ground terminal of rx

Something like the above diagram should work.

I had a nearby lightning strike that vaporized the antenna wire, burned
out the lightbulb and scattered pieces of the diodes around. The receiver
(a tube type) showed no damages.





--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

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