On Oct 24, 8:23*pm, Tom Horne wrote:
I have read that the presently available 300 ohm ladder line is
unsuitable to use at some amateur radio frequencies because of it's
construction and the losses caused by skin effect in the copper coated
steel construction. *I have been using a Terminated Folded Dipole in a
flat top configuration as my HF antenna at home. *Having recently
acquired an Icom AH-4 Antenna Coupler I am considering converting it
to a simple folded dipole, *feeding it with 300 ohm ladder line to
match it's nominal impedance from the coupler. *I know your sure that
there is a question in here someplace so is there better quality 300
ohm window line available that is entirely stranded copper in it's
construction?
--
Tom Horne, W3TDH

Tom, what length of feed line are considering? How do you intend to
install it and support it from your shack to the antenna?

I have tried both 300 ohm TV type twin lead and ladder line. Both are
quickly affected by rain and snow. But more importantly is the wind
whipping the feed line and breaking it somewhere. About once per 6
month period I had to pull the whole antenna down and either replace
the feed line or find the break and repair it.

If you are able to secure the feed line with insulators every 10 feet
or so, the wind damage should be minimal.

A couple of years ago I made my own 600 ohm open wire feed line and
the wind is no longer a problem. The wind resistance is very low and
weather is only a problem when ice collects on the feed line.

IF you are interested, the 600 ohm feed line is #14 copper with
plastic rod insulators every 10 feet. The length from shack to antenna
is about 125 feet. Two poles support the feed line on its way and the
shack end is attached to a rope and pulley so I can adjust the
tension, or let the end down for maintenance.

Just some thoughts for you. Good luck, and don't be afraid to try
different schemes.

Paul, KD7HB
Central Oregon desert

On 10/25/10 12:50 PM, KD7HB wrote:

Just some thoughts for you. Good luck, and don't be afraid to try
different schemes.


300 ohm line is probably not the best choice if you want to use
non-coaxial feedline. Much better is real ladder line or window line.

And there are some serious misconceptions about window line too, so you
hav eto be careful of what you read.


Wes Stewart, N7WS wrote what is commonly cited as ladder line's fatal flaw:

http://users.triconet.org/wesandlinda/ladder_line.pdf

I suggest that you read it.


But the study in itself suffers from a fatal flaw. And it is actually
demonstrated in the article.

Stewart had difficulties in getting his ladder line completely wet. In
fact, the water created antibubbles on the surface of the line, and ran off.

Well now, how do we fix this? We apply wetting agent to the line, this
will cause the water to wet the entire surface, then measure the loss.

Anyone see the problem here? Last time I checked, there is no wetting
agent in rain. This is testing of artificially wetted window line,
nothing more, nothing less.

I have ladder line that has been up for 10 years now, and water still
beads up on it like it did when it was new. I'll not even add that it is
vertical, so there won't be as much water hitting it as when it comes
form a spray bottle - oh wait, I did mention it.....

The characteristics of polyethelene which is used to cover window line
in fact make it very difficult to be wetted. One might be able to
enforce wetting by sandblasting the line to roughen the surface, or oh
yeah, apply wetting agent.

That however makes the results of the experiment of equal value to
modifying coax in a detrimental way, then measuring some aspect, and
saying "all coax is like this". And why would ya do it anyway?

There are reasons to use ladder or window line, and there are reasons to
use coax. For example, at our club mountaintop station, we use
copperweld for the dipoles, properly hung on towers. There is a shrt run
of normal premium coax, just enough to lower the antennas for maintence
if needed, but the coax is switched to hardline coax for most of the run
into the shack. This is a good setup if you have lots of space, a goodly
number of towers, and monoband (or at least fan) antennas.

Now for the home QTH, I have some limited space, around a 100 feet. yet
I still want multi-band operation. So I'm looking at more limited choices.

Monoband dipoles are pretty much out of the question. Loaded multiband
dipoles? For all the ham bands? Maybe not so good. Fan dipoles? a pain,
and I'd have to start supporting the antenna on a messenger line.

So that ladder line or window line fed doublet is looking pretty darn
good about now. Rain or shine.

- 73 de Mike N3LI -

On Mon, 25 Oct 2010 14:44:20 -0400, Mike Coslo wrote:

Stewart had difficulties in getting his ladder line completely wet. In
fact, the water created antibubbles on the surface of the line, and ran off.

"Antibubbles?"

Well now, how do we fix this?

That the line was resistant to becoming "completely wet" would seem to
be a boon, not a problem, for its application.

We apply wetting agent to the line, this
will cause the water to wet the entire surface, then measure the loss.

Anyone see the problem here?

Most wetting agents are detergents (in fact the whole point of using a
detergent is for complete wetting).

Sources are obscured through other applications, but glimmers of
evidence suggest that adding a wetting agent will quadruple the
conductivity of water.

Last time I checked, there is no wetting
agent in rain. This is testing of artificially wetted window line,
nothing more, nothing less.

If adding a wetting agent is called for - in spite of its absence in
rain (for now until the new political alignment ****cans EPA) - it
will undoubtedly render the line as less than useful as would be
expected in either a wet or dry environment.

How did we get here?

73's
Richard Clark, KB7QHC

On Oct 25, 1:44*pm, Mike Coslo wrote:
On 10/25/10 12:50 PM, KD7HB wrote:

Just some thoughts for you. Good luck, and don't be afraid to try
different schemes.

300 ohm line is probably not the best choice if you want to use
non-coaxial feedline. Much better is real ladder line or window line.

And there are some serious misconceptions about window line too, so you
hav eto be careful of what you read.

Wes Stewart, N7WS wrote what is commonly cited as ladder line's fatal flaw:

http://users.triconet.org/wesandlinda/ladder_line.pdf

I suggest that you read it.

But the study in itself suffers from a fatal flaw. And it is actually
demonstrated in the article.

Stewart had difficulties in getting his ladder line completely wet. In
fact, the water created antibubbles on the surface of the line, and ran off.

Well now, how do we fix this? We apply wetting agent to the line, this
will cause the water to wet the entire surface, then measure the loss.

Anyone see the problem here? Last time I checked, there is no wetting
agent in rain. This is testing of artificially wetted window line,
nothing more, nothing less.

I have ladder line that has been up for 10 years now, and water still
beads up on it like it did when it was new. I'll not even add that it is
vertical, so there won't be as much water hitting it as when it comes
form a spray bottle - oh wait, I did mention it.....

The characteristics of polyethelene which is used to cover window line
in fact make it very difficult to be wetted. One might be able to
enforce wetting by sandblasting the line to roughen the surface, or oh
yeah, apply wetting agent.

That however makes the results of the experiment of equal value to
modifying coax in a detrimental way, then measuring some aspect, *and
saying "all coax is like this". And why would ya do it anyway?

There are reasons to use ladder or window line, and there are reasons to
use coax. For example, at our club mountaintop station, we use
copperweld for the dipoles, properly hung on towers. There is a shrt run
of normal premium coax, just enough to lower the antennas for maintence
if needed, but the coax is switched to hardline coax for most of the run
into the shack. This is a good setup if you have lots of space, a goodly
number of towers, and monoband (or at least fan) antennas.

Now for the home QTH, I have some limited space, around a 100 feet. yet
I still want multi-band operation. So I'm looking at *more limited choices.

Monoband dipoles are pretty much out of the question. Loaded multiband
dipoles? For all the ham bands? Maybe not so good. Fan dipoles? a pain,
and I'd have to start supporting the antenna on a messenger line.

So that ladder line or window line fed doublet is looking pretty darn
good about now. Rain or shine.

* * * * - 73 de Mike N3LI -

An observation about wetting agents. As I have stated before
diamagnetic materials are tightly bound in a skin of resting
particles. Water is diamagnetic and all are aware that insects can
walk on this skin and at the same time these particles are tightly
bound to each other that they can form droplets of water into a tight
sphere for equilibrium. One can also have a shallow vessel of water
where, when a magnet is placed on the underside, the particles will be
attracted to the skin creating deflection. Anyway
the point is that a wetting agent removes the diamagnetic features of
water and other radiative materials where the cohesivness of the
particles is destroyed. Bearing in mind that these static particles at
rest are the root of radiation it certainly does not make sense in
destroying their adhesion to a radiating surface. I imagine that any
"windows" added between the lines would affect the displacement
current as well as the enclosed capacitive field within when the
environment changes when compared to pvc spacers. I do believe that
wetting agents are applied to space vessels to ensure the surfaces are
cleared of these same static particles prior to take off.

For years I used the cheapest 300 ohm twin-lead I could find, at times
splicing pieces
together. I have fed T2FDs, Inverted Vee's, Verticals, once I actually
loaded
a piece of wet noodle, and almost anything you could
imagine. In wind, rain, and snow I had years of good DX and other fun but
never noticed
any differences which might have occured in theory -- they never revealed
themselves in
practical use.

Irv VE6BP
Hamming since '58

"Tom Horne" wrote in message
...
I have read that the presently available 300 ohm ladder line is
unsuitable to use at some amateur radio frequencies because of it's
construction and the losses caused by skin effect in the copper coated
steel construction. I have been using a Terminated Folded Dipole in a
flat top configuration as my HF antenna at home. Having recently
acquired an Icom AH-4 Antenna Coupler I am considering converting it
to a simple folded dipole, feeding it with 300 ohm ladder line to
match it's nominal impedance from the coupler. I know your sure that
there is a question in here someplace so is there better quality 300
ohm window line available that is entirely stranded copper in it's
construction?
--
Tom Horne, W3TDH