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

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

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

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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Cecil Moore wrote:

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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That's interesting, so you find wire whose OD is just right for the ID of the
tubing and that makes a good enough connection and is adjustable. How much
adjustment were you after, inches or feet?

-Bill

On Mon, 19 Apr 2004 00:10:50 GMT, zeno wrote:

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?

Zeno, all of your suggestions would increase the weight of the
feedline, and possibly stretch the antenna. FYI, a 500-ft. spool of
#14 or #12 insulated, stranded copper wire from Lowe's Home
Improvement (or Home Depot) runs about $15.00

Bob
k5qwg



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

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