ladder line construction methods?
 

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

--
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Larry Gagnon wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Spacing is not critical. How about a 4" spacer made out of irrigation
plastic tubing?
--
73, Cecil, W5DXP



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Larry,
Boy, are you gonna have fun! As Cecil said, spacing isn't
all that critical. Use whatever you can find enough of, to make
the 'spreaders', as long as it's not conductive it should work.
The simplest way to feed ladder line through a window is to
make a 'spacer' board to fit in the window. Drill a couple of
holes in the board, the correct distance apart, feed the line
through the holes, 'hot glue' in place (or however you can get
it to stay put. Have to remove the screen...
'Doc

PS - The real 'trick' is to keep the line from 'swarming' on
you when you finish.

Impedance is about 120*ln(2*D/d) ohms, where ln is the natural
logarithm, and D is the wire spacing, center to center, and d is the
wire diameter. Assumes round wires, and air dielectric. You can
rearrange that: if you want x ohms and have d diameter, D =
d*exp(x/120)/2, where exp(x/120) is "e to the x/120 power". If you
don't have a calculator that handles that sort of math, this table
will probably get you close enough:

D/d impedance, ohms
1.9 150
2.8 200
6.2 300
22 450
75 600

Construction depends a bit on how much you're making and what you have
available for materials and tools. People used to use wooden spacers,
boiled in parafin wax. Someone gave me a bunch of PETE
tensile-strength test strips that are a good size. You can make
spacers from PVC pipe. You can thread wires through holes (generally
not so efficient), or fit wires into notches and secure by with a
plastic or wire wrap, or by melting the wire into an undersized notch,
or with various glues. Undoubtedly lots of other ideas, both
tried-and-true and just waiting to be tried for the first time.

You can drill holes through the glass and install feedthroughs (but
probably not if it's double-pane!), or drill a couple over-size holes
through the wall or possibly through a wooden window frame member, or
install a wood or plastic piece in a partially-open window. You can
also possibly inductively or capacitively couple through the window.
If you decide to go through wood or wall materials, plan to make
oversized holes, lined with decent electrical/RF insulation. What
strikes your fancy?

Cheers,
Tom


Larry Gagnon wrote in message ...
Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

One of many ways is to use plastic coathangers for spacers. These are
readily available, and have the added advantage that you can choose your color.
Just chop them up to whatever spacing you desire.
If you are planning on just a single band antenna, I would feed it with coax.
However, if you are going multi-band with a tuner, use the open wire line.
The Impedance is not critical. Use 2" to 6" spacing.
73 Gary N4AST

On Tue, 30 Mar 2004 19:52:50 -0000, Larry Gagnon
wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

As an alternative, you can try the website for w7fg. He makes and
sells open ladder line, as well as dipoles with the ladder line
attached.

bob
k5qwg

I have a G5RV made by W7FG. The construction is great and makes structural
sense. I can recommend his version highly.

Its easy to put up and you dont have to worry about the center connection
coming loose..*there is no center connection*

He uses one continuous wire from feeder to end of the dipole on each
side..smart...

Mitch KD4HTW


"Bob Miller" wrote:
As an alternative, you can try the website for w7fg. He makes and
sells open ladder line, as well as dipoles with the ladder line
attached.

bob
k5qwg

I made some ladder line last year. It works well, but was very time
consuming. I now buy it.

I purchased wire "staples" These are plastic bridges with holes for nails.
You pull out the nails and install your feed line.

There is a photo of a 1/2 inch section at this URL.

http://user.mc.net/~jdewey/Ham_radio...ding_relay.jpg

I used larger staples for my main feed line.

http://user.mc.net/~jdewey/Ham_radio/doublet.jpg

John
KA9CAR



"Bob Miller" wrote in message
...
On Tue, 30 Mar 2004 19:52:50 -0000, Larry Gagnon
wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

As an alternative, you can try the website for w7fg. He makes and
sells open ladder line, as well as dipoles with the ladder line
attached.

bob
k5qwg

The simplest way to feed ladder line through a window is to
make a 'spacer' board to fit in the window. Drill a couple of
holes in the board, the correct distance apart, feed the line
through the holes, 'hot glue' in place (or however you can get
it to stay put. Have to remove the screen...
'Doc
The above sounds very practical and do-able but make sure you put "drip loops"
on the incomming lines.
de wa2eaw...Bob

'Doc wrote:

PS - The real 'trick' is to keep the line from 'swarming' on

you when you finish.

What does this mean? I am unfamiliar with the term.

Zeno

What is a good type of wire to use? Stranded ok? Insuluated ok? what is best?

Zeno

KA9CAR wrote:

I made some ladder line last year. It works well, but was very time
consuming. I now buy it.

I purchased wire "staples" These are plastic bridges with holes for nails.
You pull out the nails and install your feed line.

There is a photo of a 1/2 inch section at this URL.

http://user.mc.net/~jdewey/Ham_radio...ding_relay.jpg

I used larger staples for my main feed line.

http://user.mc.net/~jdewey/Ham_radio/doublet.jpg

John
KA9CAR

"Bob Miller" wrote in message
...
On Tue, 30 Mar 2004 19:52:50 -0000, Larry Gagnon
wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

As an alternative, you can try the website for w7fg. He makes and
sells open ladder line, as well as dipoles with the ladder line
attached.

bob
k5qwg

Any reason not to feed each wire through the wall using those old
time ceramic insulators with the hole down the middle, you know,
those 4 or 5" long while tubes that were used in the knob&tube era
of electrical wiring. Since I would be making my own feed line
here, I could rejoing the pair on the other side of the wall and
continue with my spacers until I reached the ceiling, and then to
the process again, eg. putting each wire thru its own tube and then
continuing with the spacers on the other side.

It is either this or using that idea of double coax feed with the
coax grounds connected to each other at one end and grounded to the
tuner (?), anyone have sucess with this method of coming into the
shack via balanced lines?

Zeno

'Doc wrote:

Larry,
Boy, are you gonna have fun! As Cecil said, spacing isn't
all that critical. Use whatever you can find enough of, to make
the 'spreaders', as long as it's not conductive it should work.
The simplest way to feed ladder line through a window is to
make a 'spacer' board to fit in the window. Drill a couple of
holes in the board, the correct distance apart, feed the line
through the holes, 'hot glue' in place (or however you can get
it to stay put. Have to remove the screen...
'Doc

PS - The real 'trick' is to keep the line from 'swarming' on
you when you finish.

If one is constructing ladder line, is the point to design the ladder line
so its impedance matches the characteristic impedance of the antenna
itself at its feed point?

The theoretical feed point impedance for a full wave loop antenna is
approximately 100 ohms, (but this does change, and is dependent upon
antenna height above ground, near-by structures, and ground conductivity.)
Should I try to make my ladder line to get as close as possible to this
100 ohm? In other words, does it make any difference reallly if my (12
guage insulated) ladder line uses 4" spacers (550 ohm) or 2" spacers (468
ohm) or 1" spacers (385 ohm) in the final analysis? Should I just go with
the 4" spacing because it looks cool?

Anyone think that maybe non-insulated would be a better way to go?

Zeno


Larry Gagnon wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

--
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zeno wrote:
What is a good type of wire to use? Stranded ok? Insuluated ok? what is best?

I made mine cheap out of #16 stranded insulated house wire available at
Home Depot.
--
73, Cecil, http://www.qsl.net/w5dxp



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zeno wrote:
If one is constructing ladder line, is the point to design the ladder line
so its impedance matches the characteristic impedance of the antenna
itself at its feed point?

The point of using ladder-line is so the antenna impedance doesn't
matter (within reason). SWRs on the ladder-line range up to 30+:1
with small ill effects. A 30:1 SWR on ordinary coax is a signal
killer.

Consider that the feedpoint impedance of an all-HF-band antenna
might range from 60 ohms to 3000+/-j3000 to 6000 ohms. The SWR on
Z0=600 ohm line would be around 10:1. The SWR on Z0=50 ohms would
range up to 100+:1.

The theoretical feed point impedance for a full wave loop antenna is
approximately 100 ohms, (but this does change, and is dependent upon
antenna height above ground, near-by structures, and ground conductivity.)
Should I try to make my ladder line to get as close as possible to this
100 ohm?

Nope, go for simplicity. There's not much practical difference between
Z0=400 ohms and Z0=600 ohms. And you may be able to use the impedance
transforming properties (on a line with reflections) to your advantage.

Anyone think that maybe non-insulated would be a better way to go?

Non-insulated wire allows one to hang parallel stubs up and down the
line, useful for matching purposes. It also allows one to measure
actual feedline voltages.
--
73, Cecil, http://www.qsl.net/w5dxp



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On Wed, 14 Apr 2004 06:43:35 GMT, zeno wrote:
Should I just go with the 4" spacing because it looks cool?

Fer Sure, Dude!

The choice is simply one of maximizing copper to minimize loss. If
you expect a wide variation of Z through using the radiator across a
larger variation of frequency, it is hard to choose one single
determiner of line Z outside of this consideration. You could use the
same logic to select 50 Ohm line (there is absolutely nothing magical
about the value); however, cost becomes prohibitive due to a larger
conductor for the inside lead driving the size of everything else to
obtain the same loss figure as the cheaper, simple twin lead
construction.

So, there you have it, cool and cheap (true to only the frugal
Amateurs's perception of reality).

As for another question about coming in through the wall. You idea
would work suitably. The only problem is in having it penetrate house
insulation that is foil-backed (without you being aware of that being
so). Some would offer the penetration presents no problem as it is
for a very small interval. In the large scheme of things, quite true;
and yet as a site dislocality (humorously called a bump in Z) this is
where additional SWR will be present with a corresponding
magnification of V and the possibility of breakdown. This is
unlikely, but this would be where it happens if "likely" occurs. As
things go, it is all a probabilistic issue - the insurers have tables
for this.

73's
Richard Clark, KB7QHC

Cecil Moore wrote:

Larry Gagnon wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?




1/4" / 6 mm PTFE rod. From Radiospares in the U.K.
but there must be suppliers in the States. Cut into
suitable lengths with a hobby knife - I used 125 mm
but not critical. Drill holes 5 mm from each end,
making sure they are parallel. Holes should be about
1/2 mm smaller than the wire you are going to use. I
used 19/0.2 silver plated copper with a PTFE jacket.

PTFE is fairly soft and easy to work with hand tools.
The stuff available here is white and surprisingly
very unobtrusive visually, certainly a lot better
than black windowed 450 ohm twin.

Slit from the holes to the ends of the rod with a
hobby knife. Ease open with finger and push the wire
in. I used an aluminium ruler to push with. It will
'click' into place. You can adjust the spacer positions
easily but the grip is enough, even with PTFE, to keep
the spacers in place. Space the rods 12" to 18".
This will also work FB with bare copper conductors.

Apart from its excellent electrical characteristics
the PTFE is very good at shedding rainwater, which
can be a problem if you use other plastics, especially
tubes.

You now have some very posh mil-spec ladder line. I
can easily make 30' an hour with hand tools.

vy 73

Andy, M1EBV

Tnx to both Richard and Cecil et al, I think I am good to go. I will most
likely use the uninsulated wire for the diy ladder line. Although I do
not quite understand the thing about stubs and am not sure how I would be
able to measure anything along the ladder line since it is actually high
up in the air for the most part (I might be able to measure something at
its ends tho....what exactly does one need to be measuring up there?).
Sorry to be so Elmer-needy....

I just happen to have a bunch of that black poly 1/2" irrigation tubing,
which cuts up easily, and is apparently a good choice for diy ladder line
because of its UV tolerance.

There is no foil-backed insulation to worry about coming into the house
peak or ceiling. I have a bucket of those old porcelin knob&tube feed
thru dealies out in the barn.

I am making some masts out of whatever I can recycle, mostly old metal tv
telescoping masts. I will have to guy them if I get them up as high as I
possibly can for the four corners of the loop. I was thinking of using
pulleys and dacron for the guys, pulleys so I can redo the guys after
years...and they look like they are about to fall apart etc. without
having to take down the poles.....or should I use wire for guys? The
masts are metal anyway, maybe wire guys are ok, what do you think?

-Zeno (although I probably will be "Bill" when I finally get on the air
again)

They just gave me KG6UHM, but I think I either want my old expired call
back or concoct something new....with good cw rhythm....and "phonetics"
which reads like a novel......



Richard Clark wrote:

On Wed, 14 Apr 2004 06:43:35 GMT, zeno wrote:
Should I just go with the 4" spacing because it looks cool?

Fer Sure, Dude!

The choice is simply one of maximizing copper to minimize loss. If
you expect a wide variation of Z through using the radiator across a
larger variation of frequency, it is hard to choose one single
determiner of line Z outside of this consideration. You could use the
same logic to select 50 Ohm line (there is absolutely nothing magical
about the value); however, cost becomes prohibitive due to a larger
conductor for the inside lead driving the size of everything else to
obtain the same loss figure as the cheaper, simple twin lead
construction.

So, there you have it, cool and cheap (true to only the frugal
Amateurs's perception of reality).

As for another question about coming in through the wall. You idea
would work suitably. The only problem is in having it penetrate house
insulation that is foil-backed (without you being aware of that being
so). Some would offer the penetration presents no problem as it is
for a very small interval. In the large scheme of things, quite true;
and yet as a site dislocality (humorously called a bump in Z) this is
where additional SWR will be present with a corresponding
magnification of V and the possibility of breakdown. This is
unlikely, but this would be where it happens if "likely" occurs. As
things go, it is all a probabilistic issue - the insurers have tables
for this.

73's
Richard Clark, KB7QHC

On Wed, 14 Apr 2004 17:33:42 GMT, zeno wrote:
I just happen to have a bunch of that black poly 1/2" irrigation tubing,
which cuts up easily, and is apparently a good choice for diy ladder line
because of its UV tolerance.

Hi Bill,

Black is usually indicative of carbon content; but I wouldn't let that
stop me the first time around if it was handy (pop it into the
microwave and nuke it to see if it gets hot - this is not about
microwave frequencies, merely tendency to conduct and to dissipate).

There is no foil-backed insulation to worry about coming into the house
peak or ceiling. I have a bucket of those old porcelin knob&tube feed
thru dealies out in the barn.

Sounds like a done deal.

I am making some masts out of whatever I can recycle, mostly old metal tv
telescoping masts. I will have to guy them if I get them up as high as I
possibly can for the four corners of the loop. I was thinking of using
pulleys and dacron for the guys, pulleys so I can redo the guys after
years...and they look like they are about to fall apart etc. without
having to take down the poles.....or should I use wire for guys? The
masts are metal anyway, maybe wire guys are ok, what do you think?

Dacron, I think, is the more long-lived, goferit. Use wire, don't use
wire; it won't matter much.

As for measuring stubs. Not sure how that appeared as a concern, but
as to measuring in general, attach a known mismatch at the far end and
measure the SWR across frequency. If the readings look better than
you would have reckoned, then you have something wrong along the way
(loss tends to sweeten the appearance of problems). The known
mismatch could be as simple as a direct short at even multiple of
quarterwaves away (or open on odds - whichever). Make sure to account
for velocity factor, or simply compare the physical length to the
measured electrical length of the short/open. This, too, will give
you an indication of line health. You can go farther and calculate
the actual line Z, but who cares? Only guys like me (and that hardly
counts for much).

73's
Richard Clark, KB7QHC

Zeno,
"Swarming" means that because of the 'memory' of the wire
used to make the 'twin lead', when it's turned loose from
whatever you fixed it to to build it, it tries to assume it's
former shape. Usually results in a 'rat's nest' of wire in
a not so compact ball, LOL! Not really something to waste a
lot of worry on, just be aware that it can happen.
'Doc

Zeno,
No reason why it wouldn't work, just use the normal care
in selecting a 'spot' in the wall that doesn't hold any
other wiring, etc. Using feed-throughs like that is sort of
'permanent', can't remove it without repairing the holes.
The board in the window thingy isn't 'permanent', just take
it out of the window and replace the screen (if any). The
choice is your's and your 'significant other's (probably more
her's, than your's, right?)...
'Doc

'Doc wrote:
"Swarming" means that because of the 'memory' of the wire
used to make the 'twin lead', when it's turned loose from
whatever you fixed it to to build it, it tries to assume it's
former shape. Usually results in a 'rat's nest' of wire in
a not so compact ball, LOL! Not really something to waste a
lot of worry on, just be aware that it can happen.

Tying the ladder-line to the trailer hitch of my GMC pickup and
stretching it a bit solved all those problems.
--
73, Cecil http://www.qsl.net/w5dxp



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'Doc wrote:

Zeno,
"Swarming" means that because of the 'memory' of the wire
used to make the 'twin lead', when it's turned loose from
whatever you fixed it to to build it, it tries to assume it's
former shape. Usually results in a 'rat's nest' of wire in
a not so compact ball, LOL! Not really something to waste a
lot of worry on, just be aware that it can happen.
'Doc

Perhaps the term 'Sproinging' might be better. You take it out in a
neat roll, let go, it goes 'Sproing!' and you have a rats nest. When
you get ready to put it up, call a couple of chums over for an
antenna raising party and let them loose the coil -- then let them clean
up the ball of wire! :-)

Irv VE6BP


--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/
Visit my very special website at http://members.shaw.ca/finkirv4/
Visit my CFSRS/CFIOG ONLINE OLDTIMERS website at http://members.shaw.ca/finkirv5/
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

So "Swarming" is really the term for that? I could use that.
Sometimes that phenomenon is real comedy material. I can just
see Laurel and Hardy putting up a short wave antenna......

"swarming" hmmmmm, like you disturbed a hornets nest eh?

Now that I think of it, the actual physics behind "swarming"
would be pretty darn sophisticated stuff.....


Bill (aka Zeno, aka, etc...)


'Doc wrote:

Zeno,
"Swarming" means that because of the 'memory' of the wire
used to make the 'twin lead', when it's turned loose from
whatever you fixed it to to build it, it tries to assume it's
former shape. Usually results in a 'rat's nest' of wire in
a not so compact ball, LOL! Not really something to waste a
lot of worry on, just be aware that it can happen.
'Doc

What is need is some kind of "brain washing" technique for wire....

Either that or they should sell wire in straight lengths.....
One of my favorite (and boring) routines at the Home Depot, while awkwardly tooling
around with 20 Foot pipes in the shopping cart nearly causing bodily harm when
negotiating a turn down an isle, is to ask one of the managers, "where do you keep
the 1000 footers?"

Getting home with a 500 foot straight length of wire would require a few red flags
in back.....


-Zeno

Irv Finkleman wrote:

'Doc wrote:

Zeno,
"Swarming" means that because of the 'memory' of the wire
used to make the 'twin lead', when it's turned loose from
whatever you fixed it to to build it, it tries to assume it's
former shape. Usually results in a 'rat's nest' of wire in
a not so compact ball, LOL! Not really something to waste a
lot of worry on, just be aware that it can happen.
'Doc

Perhaps the term 'Sproinging' might be better. You take it out in a
neat roll, let go, it goes 'Sproing!' and you have a rats nest. When
you get ready to put it up, call a couple of chums over for an
antenna raising party and let them loose the coil -- then let them clean
up the ball of wire! :-)

Irv VE6BP

--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/
Visit my very special website at http://members.shaw.ca/finkirv4/
Visit my CFSRS/CFIOG ONLINE OLDTIMERS website at http://members.shaw.ca/finkirv5/
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

Doc,

Would this be a good reason to use solid core copper wire?

After tying one end of my ladder line to a short (PVC) pole at
the house roof peak (this is to keep it high and away from some
other lines), I need to carefully arch (arc) it around and into
the side of the house (or into a modified "window" that
ventillates the attic space up there. I might use a "stick" or
something to make sure the ladder line stays where I want it
here. The ladder line at this point has to go through a space
between a cable tv and a telephone line. If the ladder line is
kept in place, it will be 2-3 feet away from the other lines
which are perpendicular (and thus only in proximity at a one
point).


It is because of these other lines that I perhaps might have to
consider other alternatives, but I thought I would first try the
idea of running the ladder line all the way into the station in
the house. If there is a problem with interference, then I might
have to consider the system, I have seen mentioned, where you
run double coax lines into the house for the last section with
the shields tied together (anyone actually tried that, does that
work well, any problems, etc.?)



My point being that solid core wire is easier to "mold" into
shape. My only concern is that sometimes solid core could break
if there is a repetitive friction type bending stress along the
way (wind, or who knows).

Zeno



'Doc wrote:

Zeno,
"Swarming" means that because of the 'memory' of the wire
used to make the 'twin lead', when it's turned loose from
whatever you fixed it to to build it, it tries to assume it's
former shape. Usually results in a 'rat's nest' of wire in
a not so compact ball, LOL! Not really something to waste a
lot of worry on, just be aware that it can happen.
'Doc

Richard Clark wrote:


Black is usually indicative of carbon content; but I wouldn't let that
stop me the first time around if it was handy (pop it into the
microwave and nuke it to see if it gets hot - this is not about
microwave frequencies, merely tendency to conduct and to dissipate).

Wouldn't sticking my multi/ohmeter into the material at a couple of points
tell me if it dielectric or not? I did that and it would seem that this black
poly pipe is totally non-conductive. If it contained carbon it would be like
a composition resistor and register something (no?).

Anyway I am working on another source of rigid 3/8" dia. UV/PVC which might
work out better.

bill

On Sat, 17 Apr 2004 20:28:35 GMT, zeno wrote:
Richard Clark wrote:

Black is usually indicative of carbon content; but I wouldn't let that
stop me the first time around if it was handy (pop it into the
microwave and nuke it to see if it gets hot - this is not about
microwave frequencies, merely tendency to conduct and to dissipate).

Wouldn't sticking my multi/ohmeter into the material at a couple of points
tell me if it dielectric or not? I did that and it would seem that this black
poly pipe is totally non-conductive. If it contained carbon it would be like
a composition resistor and register something (no?).

Anyway I am working on another source of rigid 3/8" dia. UV/PVC which might
work out better.

Hi Bill,

Being conductive and being lossy are not the same thing. You may have
both situations, or one, or the other; however "not being conductive"
does not necessarily mean "not lossy." The microwave test is hardly
conclusive unless you notice it heat up. Other testing is more
sophisticated.

73's
Richard Clark, KB7QHC

Being conductive and being lossy are not the same thing. You may have
both situations, or one, or the other; however "not being conductive"
does not necessarily mean "not lossy." The microwave test is hardly
conclusive unless you notice it heat up. Other testing is more
sophisticated.

73's
Richard Clark, KB7QHC

Ohhhhh! I get it now. Its like why some kitchenware is ok for the microwave and
some not. The RF might be heating my spacers and if the spacers are the wrong
stuff, we have a melt down! Darn....why did all those neat industries making cool
things out of glass and ceramic dry up and disappear.....

with the collectible price of simple glass antenna strain insulators you would
think some industry would fire it up again, and while they are at it they could
make some of them out of purple glass and the collectors would go nuts unleashing
all kinds of cash on them. How hard is it to make things out of glass?

ps. has anyone actually heard of a diy ladder line having a spacer melt down
while running power? no reason why it couldn't happen....

Now that I understand, I will at least put my prospective spacers through the
microwave test....

-bill

On Sat, 17 Apr 2004 23:38:29 GMT, zeno wrote:
ps. has anyone actually heard of a diy ladder line having a spacer melt down
while running power? no reason why it couldn't happen....

Hi Bill,

This has never been reported here. Instead, it is noted by the
characteristic Z of the line being lower than computed. Such
measurements (of the characteristic Z) can be performed through a few
simple but still time consuming tests.

73's
Richard Clark, KB7QHC

Anyone tested that gray UV resitant PVC pipe? What about that for ladder line
spacers?

-bill

Richard Clark wrote:

On Sat, 17 Apr 2004 23:38:29 GMT, zeno wrote:
ps. has anyone actually heard of a diy ladder line having a spacer melt down
while running power? no reason why it couldn't happen....

Hi Bill,

This has never been reported here. Instead, it is noted by the
characteristic Z of the line being lower than computed. Such
measurements (of the characteristic Z) can be performed through a few
simple but still time consuming tests.

73's
Richard Clark, KB7QHC

On Sun, 18 Apr 2004 02:36:42 GMT, zeno wrote:
Anyone tested that gray UV resitant PVC pipe? What about that for ladder line
spacers?

Hi Bill,

Each formulation seems to be distinct, but offhand I don't recall
which is which. To broaden your experience with this forum, visit:
http://groups.google.com/groups?oi=d...mateur.antenna
and checkout their advanced search page. Use "PVC" and "Loss" as
keywords in the search. The topic is not so novel as to be sparsely
represented in the archive.

73's
Richard Clark, KB7QHC

"zeno" wrote in message ...
Anyone tested that gray UV resitant PVC pipe? What about that for ladder
line
spacers?



I can't say that I tested it but I have an 8 element 220 mhz beam on a 10
foot piece of the grey electrical conduit that has been up over 15 years. I
think it is about 1 1/2 inches in diameter.

Hi Richard,

Thanks for the link to the archives, I will check it out.

I imagine there a few hams who want to make their own ladder line these days.
Other than finding some vintage ceramic spacers (rare) what are they using?

Apparently paraffin soaked dowels are not without some shortcomings. I think
there is at least one ham who has a cottage industry selling his homemade version
ladder-line which, from what I can gather, utilizes the black poly piping that I
mentioned earlier.

I think I came across at least one ham who has used the grey UV/PVC pipe which he
slices (saws) lengthwise and then drills holes and/or notches etc. This seems a
bit labor intensive if one wants to make any quantity, but maybe not as much as I
think.

If the UV/PVC pipe is a good solution, I might be able to track down a source of
3/8" UV/PVC pipe which I would not slice up, but just cut into 6" lengths and
then devise a fastening system on either end for the wire.

Bill

Richard Clark wrote:

On Sun, 18 Apr 2004 02:36:42 GMT, zeno wrote:
Anyone tested that gray UV resitant PVC pipe? What about that for ladder line
spacers?

Hi Bill,

Each formulation seems to be distinct, but offhand I don't recall
which is which. To broaden your experience with this forum, visit:
http://groups.google.com/groups?oi=d...mateur.antenna
and checkout their advanced search page. Use "PVC" and "Loss" as
keywords in the search. The topic is not so novel as to be sparsely
represented in the archive.

73's
Richard Clark, KB7QHC

On Sun, 18 Apr 2004 17:44:50 GMT, zeno wrote:

If the UV/PVC pipe is a good solution, I might be able to track down a source of
3/8" UV/PVC pipe which I would not slice up, but just cut into 6" lengths and
then devise a fastening system on either end for the wire.

Hi Bill,

The sellers and methods are as diverse as the stars. It is really
very simple with few gotchas. It really is more a matter of build
and test - the only real validation you can trust.

73's
Richard Clark, KB7QHC

I imagine there a few hams who want to make their own ladder line these days.
Other than finding some vintage ceramic spacers (rare) what are they using?

Hi Zeno, Read back thru this thread, there have been all sorts of suggestions.
You can use cut up plastic coathangers, plexiglass, PVC, cut-up vinyl chopping
boards ect., for spacers. The spacing can be 1"-6". The wire can be #14
insulated-#20 insulated or uninsulated. Saw a number of suggestions to get it
in the house.
My suggestion is to pick out a method and materials that you like, and try it
out. You will probably be pleased with the results. I like all my ladder
(open wire) line
73 Gary N4AST

I just found several hundered feet of used #10 solid copper, insulated
wire, it was pulled out of my well (submersible 240V pump) a few years
ago. Any reason, aside from weight, not to use this #10 wire for
constructing diy ladder-line? I understand the bigger the wire the less
the loss (what little there is with ladder-line), also I understand that
solid core copper will stay straighter and maintain the spacing better
than braided. The insulation is kind of thick and rubbery (it went down to
the well submersible), would it be better to cut off the insulation or
just leave it? If cut off do I need to clean it up further or just leave
the residue on the wire? Since this is three wires braded together I would
have to do some major straigtening first. Maybe this is just a bit too
heavy, now that I think of it, there is alot of copper there. Any
motivating advantages???

Bill

Larry Gagnon wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

--
********************************
to reply via email remove "fake"

zeno wrote:
I just found several hundered feet of used #10 solid copper, insulated
wire, it was pulled out of my well (submersible 240V pump) a few years
ago. Any reason, aside from weight, not to use this #10 wire for
constructing diy ladder-line?

Maybe you should patent the idea of a self-supporting transmission line?
--
73, Cecil http://www.qsl.net/w5dxp



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Anyone just use lengths of copper pipe or tubing? You might only need a
tiny spacer every 5 feet or so. Was that you or someone else who made the
ladder line out of tubing shaped like a sine wave.... hi hi

seriously, though, if one needed a section of ladder line to really stay
put (say a section which gets nervously close to other naughty metal things
or wire, why couldn't you fabricate just that section out of copper tubing
and then go the rest of the way with wire? Are there impedance issues when
changing the wire thickness along the way?

73

Bill

Cecil Moore wrote:

zeno wrote:
I just found several hundered feet of used #10 solid copper, insulated
wire, it was pulled out of my well (submersible 240V pump) a few years
ago. Any reason, aside from weight, not to use this #10 wire for
constructing diy ladder-line?

Maybe you should patent the idea of a self-supporting transmission line?
--
73, Cecil http://www.qsl.net/w5dxp

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zeno wrote:
seriously, though, if one needed a section of ladder line to really stay
put (say a section which gets nervously close to other naughty metal things
or wire, why couldn't you fabricate just that section out of copper tubing
and then go the rest of the way with wire? Are there impedance issues when
changing the wire thickness along the way?

I have used solid copper wire sliding inside copper tubing to achieve
an adjustable length transmission line for matching purposes.
--
73, Cecil http://www.qsl.net/w5dxp



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