I have flown through dry snow over the Great Lakes that completely
desensed the receivers in the airplane - and this was a plane equipped
with static discharge wicks... Rising noise to a roar, big discharge
POP, receiver back on line for about 3-5 seconds until the rising roar
blocks it up again- total cycle 15 to 20 seconds, only able to hear ATC
for 3 to 5 seconds out of that... Not fun at O'dark thirty, it is 10F
outside, you won't survive a ditching into the water, and your VOR
receiver can't tell you where Windsor is...

Yes, I believe in P-Static...

denny

Cecil Moore wrote:
Wes wrote:
I don't give a damn what they call it, here's a definition of
precipitation:

Cecil Moore wrote:
Jim Kelley wrote:

I simply meant that a folded dipole
is just as likely to produce precipitation static noise as a dipole
antenna.


Probably not true for a bare-wire dipole Vs a ladder-line folded
dipole. Insulation is one well accepted method of reducing
precipitation static on airplane antennas. In any case, the two
wires in the folded dipole make it different from the single wire
in the dipole.

Any antenna/receiver combination is likely to be sensitive to
p-static. Some more than others obviously. An indoor, heavily
insulated folded dipole connected to an differential input receiver
would probably not receive much - so I'll give you that one even
though I never claimed it would. Happier now?

I'm away from my computer for the moment but consider your capacitor
suggestion. Let's say we have a perfect ground plane and are testing
a dipole Vs a folded dipole. They are in inverted-V configurations so
we can discharge a capacitor between the end of the antenna and
ground. For the dipole, there is only one path to ground through the
receiver. For the folded dipole, there are two paths to ground, one
through the receiver and one to ground. Why won't the charge
applied to the folded dipole divide and take both paths?
--
73, Cecil, w5dxp.com

You seem like a guy who'd pick a fight with his own shadow sometimes,
Cecil.

73, ac6xg

I will use a pulley. The branches I want to use are very high. I cannot
throw or even use my slingshot thingy for this. I have a handyman who has
agreed to climb the trees in the spring. I will get everything ready this
winter.

I have some large trees on each corner of my lot. I can probably get 50 feet
up.

I was going to use nylon rope to attach to the trees but I read that
polyester rope last longer. It is even cheaper. I erroneously thought that
the more expensive nylon would last longer.


"Bob Miller" wrote in message
...
On Tue, 19 Dec 2006 18:11:27 GMT, "B29" wrote:

Thanks for the suggestion. I have decided to make my own. There are
suggestions on the web that radio shack makes some good twin lead.

www.thewireman.com is a good place to buy twinlead and stuff.

However,
I still would like to put up a balun. What would be the best balun for me?
I
intend to operate on 75 meters.

I admit to being a ham since 1956. However, I have not been very active
and
now that I am retired would like to get on low band. I am not very
knowledgeable on all the types of antennas. I do know how to make a random
wire work but do not want that type of antenna again.

Also, to keep the twin lead insulated, do I need to coat the ends where
they
are shorted?

I do appreciate the successful reports of using this type of antenna. What
might happen if I put an antenna tuner on the transmitter end and tried to
operate a folded dipole for 75 meters on 40 meters?

I cannot safely use my trees until they are thawed. I cannot climb them
myself and I would not pay someone to do this until it is safer.

You could attach a weight to a piece of rope or cord, throw it over a
limb, and then hoist the end of the antenna up. Beats climbing, ice or
not, and to adjust the antenna, you just loosen the rope, and let the
antenna down.

Bob
k5qwg



Michael

"Denny" wrote in message
groups.com...
Michael, please do not spend good money for something you can build
yourself for a fraction of the cost, and learn good things in the
process...
An 8X10 piece of plexiglass storm window from the hardware store will
supply strips for the end and center insulators... A chunk of 300 ohm
TV twin lead will supply the folded dipole material... A roll of coax,
some solder, and a pieces of small rope, and you are in business... A
hack saw will cut the plexi (so will a skill saw or table saw)...
Why not make one for 10 meters as a starter until spring comes... This
can be hung between two trees or whatever so it is at least head high
and will give you some fun when the band opens here and there..... You
can check the formula for length versus resonant frequency...

denny / k8do

On Thu, 21 Dec 2006 18:56:49 GMT, "B29" wrote:

I will use a pulley. The branches I want to use are very high. I cannot
throw or even use my slingshot thingy for this. I have a handyman who has
agreed to climb the trees in the spring. I will get everything ready this
winter.

I have some large trees on each corner of my lot. I can probably get 50 feet
up.

I was going to use nylon rope to attach to the trees but I read that
polyester rope last longer. It is even cheaper. I erroneously thought that
the more expensive nylon would last longer.

As I understand, black Dacron Polyester is the good stuff. They have
it at AES, the Wireman, RadioWorks, etcetera... I've been using some
surplus olive drab Dacron I got from RadioWorks that is really long
lasting and blends in nicely... Radioworks, by the way, has good
marine-type pullys if that's the direction you're going.

bob
k5qwg



"Bob Miller" wrote in message
.. .
On Tue, 19 Dec 2006 18:11:27 GMT, "B29" wrote:

Thanks for the suggestion. I have decided to make my own. There are
suggestions on the web that radio shack makes some good twin lead.

www.thewireman.com is a good place to buy twinlead and stuff.

However,
I still would like to put up a balun. What would be the best balun for me?
I
intend to operate on 75 meters.

I admit to being a ham since 1956. However, I have not been very active
and
now that I am retired would like to get on low band. I am not very
knowledgeable on all the types of antennas. I do know how to make a random
wire work but do not want that type of antenna again.

Also, to keep the twin lead insulated, do I need to coat the ends where
they
are shorted?

I do appreciate the successful reports of using this type of antenna. What
might happen if I put an antenna tuner on the transmitter end and tried to
operate a folded dipole for 75 meters on 40 meters?

I cannot safely use my trees until they are thawed. I cannot climb them
myself and I would not pay someone to do this until it is safer.

You could attach a weight to a piece of rope or cord, throw it over a
limb, and then hoist the end of the antenna up. Beats climbing, ice or
not, and to adjust the antenna, you just loosen the rope, and let the
antenna down.

Bob
k5qwg



Michael

"Denny" wrote in message
egroups.com...
Michael, please do not spend good money for something you can build
yourself for a fraction of the cost, and learn good things in the
process...
An 8X10 piece of plexiglass storm window from the hardware store will
supply strips for the end and center insulators... A chunk of 300 ohm
TV twin lead will supply the folded dipole material... A roll of coax,
some solder, and a pieces of small rope, and you are in business... A
hack saw will cut the plexi (so will a skill saw or table saw)...
Why not make one for 10 meters as a starter until spring comes... This
can be hung between two trees or whatever so it is at least head high
and will give you some fun when the band opens here and there..... You
can check the formula for length versus resonant frequency...

denny / k8do

Thanks Bob,

I did not even think to get pulleys and rope from amateur radio supply
places. I will do some shopping there very soon.

What do you think about feeding the dipole with some sort of balun?

Michael W0EZI


"Bob Miller" wrote in message
...
On Thu, 21 Dec 2006 18:56:49 GMT, "B29" wrote:

I will use a pulley. The branches I want to use are very high. I cannot
throw or even use my slingshot thingy for this. I have a handyman who has
agreed to climb the trees in the spring. I will get everything ready this
winter.

I have some large trees on each corner of my lot. I can probably get 50
feet
up.

I was going to use nylon rope to attach to the trees but I read that
polyester rope last longer. It is even cheaper. I erroneously thought that
the more expensive nylon would last longer.

As I understand, black Dacron Polyester is the good stuff. They have
it at AES, the Wireman, RadioWorks, etcetera... I've been using some
surplus olive drab Dacron I got from RadioWorks that is really long
lasting and blends in nicely... Radioworks, by the way, has good
marine-type pullys if that's the direction you're going.

bob
k5qwg

"B29" wrote in
t:

Thanks Bob,

I did not even think to get pulleys and rope from amateur radio supply
places. I will do some shopping there very soon.

What do you think about feeding the dipole with some sort of balun?

You'll want a 4:1 balun if you'll be using coax.


- 73 de Mike KB3EIA -

Jim Kelley wrote:
Jim Kelley wrote:
I simply meant that a folded dipole
is just as likely to produce precipitation static noise as a dipole
antenna.

... so I'll give you that one even though I never claimed it would. Happier now?

Sorry, I thought you were claiming equal magnitudes of noise for two
dissimilar antennas.

You seem like a guy who'd pick a fight with his own shadow sometimes,

Sorry, I seem to have inferred something you didn't mean to imply.
I believe I can prove the difference in the two antennas using EZNEC
but not until I get back to my home computer.
--
73, Cecil, w5dxp.com

Buying pulleys at radio supply places is as bad as buying at a marina. Get
the stainless stuff at your local hrdware for about half the cost.

"B29" wrote in message
t...
Thanks Bob,

I did not even think to get pulleys and rope from amateur radio supply
places. I will do some shopping there very soon.

What do you think about feeding the dipole with some sort of balun?

Michael W0EZI


"Bob Miller" wrote in message
...
On Thu, 21 Dec 2006 18:56:49 GMT, "B29" wrote:

I will use a pulley. The branches I want to use are very high. I cannot
throw or even use my slingshot thingy for this. I have a handyman who has
agreed to climb the trees in the spring. I will get everything ready this
winter.

I have some large trees on each corner of my lot. I can probably get 50
feet
up.

I was going to use nylon rope to attach to the trees but I read that
polyester rope last longer. It is even cheaper. I erroneously thought
that
the more expensive nylon would last longer.

As I understand, black Dacron Polyester is the good stuff. They have
it at AES, the Wireman, RadioWorks, etcetera... I've been using some
surplus olive drab Dacron I got from RadioWorks that is really long
lasting and blends in nicely... Radioworks, by the way, has good
marine-type pullys if that's the direction you're going.

bob
k5qwg

Jim Kelley wrote:
chuck wrote:
Hi Jim,

Can you elaborate further on your understanding of just how an
ungrounded antenna wire that receives an increment of charge causes a
response in the receiver as the charge is being acquired?

Hi Chuck - given a large enough increment of charge it's pretty
straightforward. Best example I can think of is a capacitor. Take a
high gain amplifier with an input coupling capacitor and start daubing
clumps of charge onto the unconnected input lead. When the amount of
charge is big enough, you'll hear the pop that results from the
instantaneous change in charge. Thousands of those per second and
pretty soon we're talking some real noise. ;-)

If dust particles are charged as raindrops are (mixed polarity and
magnitude) a typical incremental charge is on the order of 8
picocoulomb. Do we have an understanding of how much power would be
transmitted to the 50 ohm input impedance of the receiver by such an
incremental charge and the mechanism by which that transmission takes
place? Based on anecdotal info, it is not unusual for these impulses
to appear at an average level of several S-units.

Thanks for any insights you can share.

Chuck, NT3G

I've never worked these numbers before, but given your typical charge
per particle of 8 picocoulombs, and a 16uV signal from a 50 ohm antenna
(converted to uamps), I get about 4x10^4 of those particles per second.
Given the density of air, that's a pretty low number I think. If I'm
wrong, please don't blast me. The back of my envelope here is pretty
messy and hard to read. :-)

Hi Jim,

Seems I misunderstood your original post as suggesting that each
incremental charge produced a pop.

I see that the typical current density of rain in a storm is on the
order of 0.1 - 1 uA/square meter. Taking the usual obscene liberties
with priors, that's on the order of 60 - 240 pA for a 40 meter long wire
with a diameter of 2 mm.

The average voltage developed at the receiver front end (50 ohms)would
then be on the order of 12 nanovolts (240 pA x 50 ohms). This is
obviously many orders of magnitude less than reported p-static signal
levels.

Using your capacitor-coupled amplifier example, a continuous, average
current of 240 pA would be more like DC than what we seem to hear. I am
persuaded that there may be some kind of relaxation process going on in
which the charges build to some breakdown level and appear as a pulse
(significantly greater than 12 nV) at the receiver input. But what
breaks down? Diodes? Presumably we are not talking about arcing here.
Does anyone recall this phenomenon in the vacuum tube receiver era?

Also unknown is the state of charge of the ungrounded antenna wire just
prior to the acquisition of an incremental charge. Is the antenna at
some high positive or negative potential just prior to impact, allowing
a small incremental charge to cause a breakdown?

What I think we do know is that there are sometimes charged particles
(dust, rain, snow, etc.) that impact an antenna and cause a
characteristic type of noise in the receiver. Exactly which particles,
with which charges, and under what conditions of pre-existing charge in
the antenna do we see such noise and at what signal levels?

I'm sort of at the analogous point of noting that crop growth is
correlated with some periodic level of rainfall, without a clue as to
the mechanism by which the raindrops and plant growth are related. ;-)

Appreciate your comments, Jim.

73,
Chuck




73, Jim, AC6XG







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"chuck" wrote in message
...
Jim Kelley wrote:
chuck wrote:
Hi Jim,

Can you elaborate further on your understanding of just how an
ungrounded antenna wire that receives an increment of charge causes a
response in the receiver as the charge is being acquired?

Hi Chuck - given a large enough increment of charge it's pretty
straightforward. Best example I can think of is a capacitor. Take a
high gain amplifier with an input coupling capacitor and start daubing
clumps of charge onto the unconnected input lead. When the amount of
charge is big enough, you'll hear the pop that results from the
instantaneous change in charge. Thousands of those per second and pretty
soon we're talking some real noise. ;-)

If dust particles are charged as raindrops are (mixed polarity and
magnitude) a typical incremental charge is on the order of 8
picocoulomb. Do we have an understanding of how much power would be
transmitted to the 50 ohm input impedance of the receiver by such an
incremental charge and the mechanism by which that transmission takes
place? Based on anecdotal info, it is not unusual for these impulses to
appear at an average level of several S-units.

Thanks for any insights you can share.

Chuck, NT3G

I've never worked these numbers before, but given your typical charge per
particle of 8 picocoulombs, and a 16uV signal from a 50 ohm antenna
(converted to uamps), I get about 4x10^4 of those particles per second.
Given the density of air, that's a pretty low number I think. If I'm
wrong, please don't blast me. The back of my envelope here is pretty
messy and hard to read. :-)

Hi Jim,

Seems I misunderstood your original post as suggesting that each
incremental charge produced a pop.

I see that the typical current density of rain in a storm is on the order
of 0.1 - 1 uA/square meter. Taking the usual obscene liberties with
priors, that's on the order of 60 - 240 pA for a 40 meter long wire with a
diameter of 2 mm.

The average voltage developed at the receiver front end (50 ohms)would
then be on the order of 12 nanovolts (240 pA x 50 ohms). This is obviously
many orders of magnitude less than reported p-static signal levels.

Using your capacitor-coupled amplifier example, a continuous, average
current of 240 pA would be more like DC than what we seem to hear. I am
persuaded that there may be some kind of relaxation process going on in
which the charges build to some breakdown level and appear as a pulse
(significantly greater than 12 nV) at the receiver input. But what breaks
down? Diodes? Presumably we are not talking about arcing here. Does anyone
recall this phenomenon in the vacuum tube receiver era?

Also unknown is the state of charge of the ungrounded antenna wire just
prior to the acquisition of an incremental charge. Is the antenna at
some high positive or negative potential just prior to impact, allowing a
small incremental charge to cause a breakdown?

What I think we do know is that there are sometimes charged particles
(dust, rain, snow, etc.) that impact an antenna and cause a characteristic
type of noise in the receiver. Exactly which particles, with which
charges, and under what conditions of pre-existing charge in the antenna
do we see such noise and at what signal levels?

I'm sort of at the analogous point of noting that crop growth is
correlated with some periodic level of rainfall, without a clue as to
the mechanism by which the raindrops and plant growth are related. ;-)


the noise is caused by corona on the antenna due to the electric field
between the ground and cloud. this field can be many thousands of kv per
meter which is enough to cause sharp points and tips of elements to generate
corona which makes the hiss and pop noises.