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Author Topic: bare copper ladder line  (Read 601 times)
WA5UHK
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Posts: 131




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« on: August 20, 2008, 01:51:27 PM »

Anyone know of a source for bare copper ladder line with a nominal impedance of 450 ohms; the older style that uses white polystyrene insulator/spacers?



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WB2WIK
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Posts: 20611




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« Reply #1 on: August 20, 2008, 05:56:37 PM »

Yep. Try here:

http://www.w7fg.net/

Real, bare copper ladder line.  He says it's "600 Ohms" but I suspect it might be more like 500.  Not that it makes much of a difference!

WB2WIK/6
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WA5UHK
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Posts: 131




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« Reply #2 on: August 20, 2008, 06:38:28 PM »

Thanks for the help.

I've seen this.  Its quite large. The spacers are probably 6 inches.  The review is great; I just don't have the need for it.

I'm looking for the classic 450 ohm ladder line that was available for many years.  I still have about 20 feet of it on a 100 foot spool; wish I'd have taken the antenna & feed down from my old QTH.  

I'm almost sure I saw some for sale at a hamfest a couple of years ago but now I can't find a source.

I am trying to lower the visual profile of the  feed line as it goes down the side of my home from the second floor eve of the roof where my inverted v is fed and disappears into the attic of my above garage shack.  

Right now I'm using the 450 ohm "window" line that is dark brown or black and looks obvious.  I'll leave the section of it in my attic because it is insulated along the length.  But I want to replace the section outside.  I think the bare copper would patina after a while and look better and a bit more hidden.
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PHILA
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Posts: 28




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« Reply #3 on: August 20, 2008, 09:52:21 PM »

Do a google search on White Wire Loom.

That would be your best bet on covering the ladder line to match your house.
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N3QE
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Posts: 2285




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« Reply #4 on: August 22, 2008, 03:58:42 AM »

If you're asking for ladder line, but don't want ladder line, maybe what you want is 450-ohm "window line". This has about a 1-inch spacing, insulated conductors, and the insulation forms a plastic web with gaps.

I get mine at the RF Connection, http://www.therfc.com/ , because it's up the road from me, but there's other places too.

Tim.
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N3QE
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« Reply #5 on: August 22, 2008, 08:40:11 AM »

AFAIK the lowest-visual-impact ladder line can not be bought already made but you have to make it yourself.

Use, say, 14 gauge bare solid wire (preferably hard-drawn) and put 4" polycarbonate spacers every foot or so with tie wires. www.cebik.com has some details in the "Home brew parallel transmission lines" section.

I used 1/8" thick polycarbonate sheet and cut a bunch of 4" x 3/8" strips. Then I notched the strips at each end to fit 14 gauge bare solid wire (my table saw's blade happened to be just the right width) and drilled holes near each notch to put tie wires. I soldered my tie wires to the 14 gauge copper, but in retrospect just wrapping them would have been good enough.

Making it is a bit of a chore, I did 100 feet in my backyard taking up most of a Saturday morning, but it's beautiful after it's up in the sky, and yes it is a lot less ugly than brown window line.

Tim.
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WA5UHK
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« Reply #6 on: August 22, 2008, 09:02:12 AM »

Thanks Tim.

That's a good idea.  I make all my standoffs for ladderline with nylon rods.  I've got several sticks of various sizes.  I think I'll give that a try.  Since I control the run of the line I can put the spacers where I want.

Thanks again for the idea.
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N3QE
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« Reply #7 on: August 22, 2008, 10:56:13 AM »

I settled on transparent polycarbonate for the spacers based on Cebik's recommendation.

Nylon has some water absorption which may be undesirable in feed line. Look at all the old ARRL handbooks and how they boiled their spacers in paraffin wax :-).

Polycarbonate has good UV properities for exposure to the weather.

Polycarbonate tubes or rods would, I think, be preferable in terms of strength vs surface area, but polycarbonate in tube or rod form is a lot more expensive than polycarbonate in sheet form.

I used 26 gauge copper for the tie wires, but a couple of ties near the bottom end broke within a few months of installation. I replaced them with 22 gauge, wrapped not soldered, and they've held up since. The way the ladder line comes down at the bottom and is stood off from my house eaves took some trial and error, in the end the way that causes the least stress seems to be screw eyes on the standoffs with the feedline conductors in big loops through the screw eyes. This allows the ladder line to blow in the wind without any flexing at the standoffs.
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