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Author Topic: Homemade Ladder Line  (Read 3385 times)
KE0Q
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Posts: 19




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« on: April 02, 2008, 09:22:02 PM »

I'm thinking about putting up a horizontal loop antenna and want to fabricate my own ladder line.  I live overseas and I just do not have access to commercial ladder line.  I can get PVC pipe (various diameters) and good copper wire is available.  What dimensions do I need?  Any suggestions? I will be using a ICOM AH-4 Tuner.
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N3BIF
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Posts: 1190




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« Reply #1 on: April 02, 2008, 09:34:30 PM »

http://64.233.169.104/search?q=cache:j9JubSD6X6IJ:www.athensarc.org/ladder.asp+%22make+your+own+open+wire&hl=en&ct=clnk&cd=1&gl=us
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N3QE
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Posts: 2289




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« Reply #2 on: April 03, 2008, 03:37:00 AM »

What you need:

The feedline wire. Stranded or solid, anything from 12AWG to as skinny as 18AWG. If you can get copperweld, do it. Otherwise hard-drawn copper. Otherwise just copper. And anything will work in the end - stranded or solid, insulated or noninsulated, etc.

A bunch of spacers - you've already identified PVC pipe. If you can, get UV-rated PVC (here in the US, the grey kind for electrical conduit stands up better to sunlight.) But my preferred insulator is some 1/8" thick polycarbonate sheet, cut into strips 4" long by 3/8" wide. But lots of things will work fine.

Nominal dimensions: 4" spacing, and a spacer every 12". The reasons for these numbers are not necessarily electrical - it's because if you go smaller than 4" spacing, then you need more spacers, and if you are making 100 foot of this stuff, it gets pretty boring after the first dozen spacers!

You take two identical lengths of the feedline wire and stretch them out straight. Preferably with matching tensions etc. I use pulleys and counterweights to do my tensioning with hard-draw copper; with copperweld you'll need much more tension to get it to lay straight; with stranded soft-drawn copper wire you won'
t need much tension at all.

Start installing spacers every foot. My preferred way: cut narrow slots into the end of each spacer. Then drill a hole through the spacer. The feedline wire goes in the slots. And a "tie-wire" (could be same as feedline wire but often a little skinnier) of length a few inches goes through the hole and wraps around the feedline wire on both ends. If your feedline wire is bare/noninsulated then you can solder the tie wire to the feedline wire pretty easy. Otherwise just do a few wraps and use glue or tar or paraffin or whatever you have locally to glob it on. The glob is in part to stop the tie wire from untwisting, but just as important is to stop the spacer from sliding up and down.

Repeat the installation of all your spacers. You're done!
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KE0Q
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« Reply #3 on: April 03, 2008, 04:56:22 AM »

Thanks for the information!  Great website!

73's & Mabuhay from Mindanao, Philippines,

Tim - DU9/KE0Q
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WW5AA
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Posts: 2086




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« Reply #4 on: April 03, 2008, 08:01:25 AM »

I use venetian blind rods made out of plexi-glass. I cut sections to the correct length, drill a hole on each end and start stringing them onto the wires. Once all is in place I use a small torch and melt the holes. I like to paint the whole line with Krylon plastic spray paint. Have fun!

73 de Lindy
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WB2WIK
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Posts: 20612




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« Reply #5 on: April 03, 2008, 08:43:05 AM »

Tim, you can have American-made ladder line in 2-3 weeks shipped from the States...I send Balikbayan boxes to P.I. all the time.  Very cheap, pretty fast, guaranteed.

If I'd have known you needed some I'd have stuffed some into my last carton, which left my house on Saturday.  It will be in Cebu on April 20th and from there it can be transported locally to you...

Making open wire line may be fun for some, but for me it's a terrible, time consuming chore.  

WB2WIK/6
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WB6BYU
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Posts: 13341




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« Reply #6 on: April 03, 2008, 09:24:50 PM »

Certainly don't bother threading the spacers on the wires - that gets old
in a hurry.  Cut slits in the ends and slip the wires into them, then secure
the spacers with tie wires (or by melting the ends closed.)  At some
point in the past I remember coming up with clever ways to punch holes
in strips of plastic from a milk carton so the wires would snap in place,
but I'd have to re-invent it since I never actually tried it.

If you are going to use a flat line - for example, 600 ohm line for a
three-wire folded dipole, then you have to use the right combination
of spacing and wire diameter to get the desired impedance.  But this
isn't the way most hams use ladder line - generally it is used with some
unknown impedance at the antenna, in which case the exact impedance
of the line itself doesn't really matter.  It then becomes more of a
mechanical issue, how much spacing and tension you need to keep the
wires spaced adequately apart.  I've strung up 75' of line with no
spreaders at all by tying the ends of the wires to nails in a fence and
pulling up enough tension on the wires.  With roughly 8" spacing there
was no way the wires were going to twist together (and using insulated
wire meant that there was no damage if they accidentally touched
temporarily.)

The shorter the spacers the more of them you need for the same amount
of wire tension to keep the wires from twisting together.  Longer
spacers require stiffer material.  If you are going to use PVC pipe I'd
use the thinnest stuff you can find and cut it into long strips rather
than using lengths of whole pipe.  Similarly, the stiffer the wire the
fewer spreaders you need.  You can use any sort of wire that is handy,
from 3mm solid copper to 0.5mm stranded hookup wire.
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N3QE
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Posts: 2289




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« Reply #7 on: April 04, 2008, 10:56:24 AM »

With regards to installing spacers "getting old in a hurry", my two cents:

I built about 100 foot of ladder line, with polycarbonate spacers cut from 1/8" sheet, slotted ends with tie wires. Spacing was 4", and a spacer every foot. Wire was 14 gauge hard-drawn.

Making the 100 spacers took about two hours.

Stretching and tensioning the wire in my backyard was about a half-hour.

Installing 100 spacers with tie wires was about two hours.

Going back with a blow torch and putting a blob of solder on every joint was about an hour. The blob of solder is not so important for holding the tie wires, it is mostly there to stop the spacer from sliding up and down.

Attaching the wire to the antenna and re-hoisting the antenna up 100 feet, without the spacers catching on the corner of the house or on tree/bush branches, was about another hour.

In all, it was most of a day. I'm very very happy with the results - the feedline pretty much vanishes into the sky unless you look for it, as the polycarbonate spacers are transparent and the wires aren't all that thick, and it's completely unaffected by wet weather, and it isn't much wind load even in 40-50MPH winds, all good points over the brown window line it replaced. But it was a good amount of work. OTOH buying 100 feet of brown window line and hauling it up is just minutes in comparison.
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KE4ZHN
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Posts: 139




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« Reply #8 on: April 05, 2008, 08:57:28 AM »

http://www.w7fg.net/
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K3ANG
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Posts: 179




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« Reply #9 on: April 05, 2008, 11:44:46 PM »

I've never built it.
YMMV
Usual caveats.

http://www.kr1st.com/hfcoath.htm
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