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

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

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