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Author Topic: Ladder line using popsicle sticks  (Read 3061 times)
AE7TE
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Posts: 57




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« on: November 23, 2017, 08:58:17 PM »

I'm about to try something absolutely crazy.

I just cut 25 popsicle sticks up into pieces 2 inches (50mm) long. I'm going to make holes in them which will friction-fit onto insulated wire. I'm not sure what wire I want to use yet, but it will likely be wire with soft, pliable insulation like speaker wire.

Once that happens, I'm going to dunk them all into a bath of melted wax so they are sealed. I can melt a big pot of wax and dunk them all at once. Then, I'll string them onto wire to make a 25 foot run of ladder line. The result will be a roll that will be easily usable in the field, with a QRP radio. The feed line is going to be extremely low-loss and work with a doublet to force as much of a 5w signal into the air.

I'm also sure these won't last forever. The wood is not excellent quality (for the price of a bag of popsicle sticks, I'm not expecting much). This is an experiment to see how long they work, as well as how well the twin-lead performs.

Ed AE7TE
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WB6BYU
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Posts: 17195




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« Reply #1 on: November 23, 2017, 10:28:11 PM »

One issue will be threading the wire through that many spreaders with a snug fit in each hole.

A better way is to use a short length of wire (or small cable tie, etc.) to pass through a hold in the end
of the stick and around the feedline wire - that saves a lot of construction work.

Sometimes a thin bare wire is passed through holes in the spreader and wrapped around (possibly
soldered) to the main wire on each side.  This could also be insulated wire if it isn't going to be soldered.
You should be able to wrap it tightly enough to hold the spreaders in place.  Basically, the main feedline
wire passes beside the spreader and a short piece of wire holds them in place.


In the end, I don't know that this approach will actually deliver significantly more RF to the antenna than
using TV twinlead, or some of the other options.  The ARRL has only recently admitted that their "standard"
formulas and charts for the loss of open wire line have been in error for many years.  (It looks llike someone
only included the resistance of one of the two wires in the calculation.)  As a result, open wire lines, while
having low losses, really aren't as low loss as some articles have made them out to be.   300 ohm twinlead
may be a worthwhile trade-off by saving the time of making your own, and by the time you include the
potential losses in a balanced tuner, you might not gain that much over just using coax, which is simpler.
(The losses in 25' of feedline is pretty low, especially on the lower bands.  I use 25' of RG-174 for my
backpack dipole kit, and the worst case loss on 10m is just over 1 dB, and less on the lower frequencies.
By eliminating the antenna tuner I can make up part of this loss, so open wire line really doesn't make
much of an improvement.


But if you want to try it, one of the antennas I made used a combination spreader / center insulator along
with a pair of 65' wires:  by moving the spreader / center insulator along the pair of wires, I can very the
length of the doublet vs. the feedline length.  The spacing at the center is about 6", and I use a second spreader
at the feed end.  In use, I adjust to the dipole length I want to use, tie off the wires on the spreader/insulator,
and use the rest of the wires for the feedline.  By putting some tension on the wire I can (hopefully) keep the
wires spread sufficiently without needing extra spreaders.  Actually the antenna has been sitting in my box
of antennas to try for perhaps 15 years now - I just haven't had an opportunity that called for it.  One of these days...
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KF4ZGZ
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Posts: 40


WWW

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« Reply #2 on: November 24, 2017, 02:52:35 AM »

I would cut notches or slots in the ends just big enough for a snug slip fit ...... add a touch of hot glue or even dollar store superglue.
Pulling the wire through a friction fit hole won't be fun.
As for wire .... I would use 14ga. stranded house wire.
And if it was me, I would have went with 6", but you should be ok.


Matt
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LA9XNA
Member

Posts: 189




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« Reply #3 on: November 24, 2017, 03:04:22 AM »

Use hotglue to fix the wire to the spreader.
A smal dot on each side of the spreader and your good.
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W6EM
Member

Posts: 1668




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« Reply #4 on: November 24, 2017, 10:39:16 AM »

While popsicle sticks are cheap, there are some materials that can be used that may not be quite as cheap, but fare far better outside.

For one thing, parrafin wax begins to melt at 99F, which on a hot summer day willmelt it off/out of the wood.  And, wood will wick up moisture from humid air and rain.  Commercial VHF collinear antenna manufacturers use beeswax to hold the elements vertically, inside fiberglass tubing as beeswax melts at a much higher temperature. 

Here's a link that will allow you to calculate the characteristic impedance of what you construct, and has a really good suggestion for cheap ladder insulators.  Black polyethylene irrigation tubing.  It is sold in coils at most hardware/landscape suppliers.  Using black zip ties to hold the wire against the short pieces of cut tubing also is a good way to anchor the wires to the short pieces.

If you still want to use the wood, soak and coat them thoroughly with black epoxy marine paint.  Much better in humid environs.

73.

Lee

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W6EM
Member

Posts: 1668




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« Reply #5 on: November 24, 2017, 03:49:46 PM »

Oops, I left out the link......

http://hamwaves.com/zc.circular/en/index.html

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K8AXW
Member

Posts: 6399




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« Reply #6 on: November 24, 2017, 06:47:42 PM »

If I was going to go to all of that  trouble I'd follow the previous hints, (Pick one) but I would also soak the sticks in melted (some have said boiling - be careful of burns and it lighting off!)  paraffin to make it weatherproof. 

This is what many old times did for their 600 ohm ladder line.
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N7EKU
Member

Posts: 723




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« Reply #7 on: November 24, 2017, 07:30:28 PM »

Hi Ed,

Since the wire will have the same insulation whether it is zipped together as it comes, or separated by the sticks, the loss won't be any different I think.  Just the impedance of the line will change.  Zipped it will probably be something like 100 ohms and with 1" sticks maybe 300 ohms.  Of course the loss would change if the line was wet though as the wet lines together would cause changes in impedance and increased losses.
 Probably RG-174 would give the same or less loss if running a halfwave dipole antenna.

I would just choose this sticks method if you specifically needed a certain higher line impedance or if you were considering to operate with wet lines.  I think the wax would make the sticks last as long as the wire would since you are just operating portable.  Sure hot sun may melt the wax, but it wouldn't suddenly cause it to separate itself from the wood.  The fibers and pores of the wood would tend to hold the wax well I think.  Of course you could use candle wax or beeswax too.  Tung oil or linseed oil would probably work well too.

Good luck and have fun :-)


Mark.


I'm about to try something absolutely crazy.

I just cut 25 popsicle sticks up into pieces 2 inches (50mm) long. I'm going to make holes in them which will friction-fit onto insulated wire. I'm not sure what wire I want to use yet, but it will likely be wire with soft, pliable insulation like speaker wire.

Once that happens, I'm going to dunk them all into a bath of melted wax so they are sealed. I can melt a big pot of wax and dunk them all at once. Then, I'll string them onto wire to make a 25 foot run of ladder line. The result will be a roll that will be easily usable in the field, with a QRP radio. The feed line is going to be extremely low-loss and work with a doublet to force as much of a 5w signal into the air.

I'm also sure these won't last forever. The wood is not excellent quality (for the price of a bag of popsicle sticks, I'm not expecting much). This is an experiment to see how long they work, as well as how well the twin-lead performs.

Ed AE7TE

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Mark -- N7EKU/VE3
ZENKI
Member

Posts: 1438




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« Reply #8 on: November 24, 2017, 08:24:56 PM »

Find an electronics manufacturer or PCB maker near your location.

When people get PCB boards made they come in panels that are broken apart after parts placement. These are fiberglass or G10 epoxy boards with an excellent mask coating.

These remains are like popsicle sticks but will  see you into the grave. Another good thing about them is that they are light, UV and waterproof. I have not found a better spreader yet.

I'm about to try something absolutely crazy.

I just cut 25 popsicle sticks up into pieces 2 inches (50mm) long. I'm going to make holes in them which will friction-fit onto insulated wire. I'm not sure what wire I want to use yet, but it will likely be wire with soft, pliable insulation like speaker wire.

Once that happens, I'm going to dunk them all into a bath of melted wax so they are sealed. I can melt a big pot of wax and dunk them all at once. Then, I'll string them onto wire to make a 25 foot run of ladder line. The result will be a roll that will be easily usable in the field, with a QRP radio. The feed line is going to be extremely low-loss and work with a doublet to force as much of a 5w signal into the air.

I'm also sure these won't last forever. The wood is not excellent quality (for the price of a bag of popsicle sticks, I'm not expecting much). This is an experiment to see how long they work, as well as how well the twin-lead performs.

Ed AE7TE
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AE7TE
Member

Posts: 57




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« Reply #9 on: November 25, 2017, 12:03:38 AM »

I tried painting them all with rustoleum oil based paint. Because the paint is old and takes days for full drying, I said to hell with it and dumped all of the separators in the garbage.

I have a big spool of TV 300 ohm line I got from a second hand store. I think I'll use that instead. I normally prefer to roll my own but this time it was a bit ridiculous. The only reason to even attempt what I was doing was because popsicle sticks are so ridiculously cheap.

I have made my own twin lead before, by cutting up coat hangers and using the plastic. It's very time consuming and I can't comment on how worthwhile it is.

Ed
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G3RZP
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Posts: 8153




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« Reply #10 on: November 25, 2017, 02:35:01 AM »

I tried all sorts of plastic spreaders, and they all eventually succumbed to UV even in the relatively low UV environment in the UK. $30 in the Dayton fleamarket got me a box of about 2 inch long 3/8 inch diameter ceramic insulators as used on USN aircraft in WW2 - I saw exactly the same insulators on an aircraft in the USAF museum. With 16SWG (14 AWG) hard drawn copper wires and about 60 feet long, the open wire line has lasted over 20 years.
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KU3X
Member

Posts: 435




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« Reply #11 on: November 25, 2017, 04:24:54 AM »

Very creative. Sounds like a fun project.
I needed to use 540 ohm parallel feeders to feed a double extended zepp, for a matching section. 450 ohms was too low and 600 ohms was too high, so I built my own. I used one half inch PVC. I drilled holes and fed the wire through the holes. The hole size was just a tad bigger than the OD of the wire. To keep the spreaders in place, I used a pair of needle nose plyers, stuck the plyers in each end of the PVC and gave the wire a tiny twist. Just a few degrees is all that is needed. No way could you move the PVC once the wires had the twist in it.
That antenna is still in service today.

Barry
www.ku3x.net
                  
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WB6BYU
Member

Posts: 17195




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« Reply #12 on: November 25, 2017, 07:17:20 AM »

Quote from: N7EKU

Since the wire will have the same insulation whether it is zipped together as it comes, or separated by the sticks, the loss won't be any different I think...



Actually it does make a difference:  that is one reason they put windows in
windowed twinlead.



The loss depends on how much of the field passes through the lossy PVC dialectic.
An air gap greatly reduces the losses.  Think of the dielectric as a resistor:
adding a larger resistor (air) in series with the resistances of the insulation
layers reduces the total leakage currents.  That's a simplification, but it
explains why the air gap is significant.

The PVC used in most wire insulation is much lossier than the polyethylene used
in transmission lines.  While dielectric losses are usually insignificant in a feedline
designed for such a purpose, that often is the limiting factor for zip cord, speaker
cable, and other 2-conductor wires we often try to use for feedline at HF.
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W6EM
Member

Posts: 1668




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« Reply #13 on: November 25, 2017, 02:30:33 PM »

Quote from: N7EKU

Since the wire will have the same insulation whether it is zipped together as it comes, or separated by the sticks, the loss won't be any different I think...



Actually it does make a difference:  that is one reason they put windows in
windowed twinlead.



The loss depends on how much of the field passes through the lossy PVC dialectic.
An air gap greatly reduces the losses.  Think of the dielectric as a resistor:
adding a larger resistor (air) in series with the resistances of the insulation
layers reduces the total leakage currents.  That's a simplification, but it
explains why the air gap is significant.

The PVC used in most wire insulation is much lossier than the polyethylene used
in transmission lines.  While dielectric losses are usually insignificant in a feedline
designed for such a purpose, that often is the limiting factor for zip cord, speaker
cable, and other 2-conductor wires we often try to use for feedline at HF.
From my old days playing with HV wire insulations in my employment many years ago, PVC is loaded with all sorts of clay fillers.  And, it tends to break down rather quickly from UV exposure in sunlight.  Carbon black is added to try to combat the UV damage, but it still is inferior to polyethylene as far as UV resistance is concerned.  PE normally doesn't have many additives other than some carbon black.  PVC isn't a very good insulation at higher voltages.....above 600V.  Sometimes, composites of PE and PVC are used.  PE is considered the insulation, PVC as jacket material......just like coax.  Off hand, I can't recall the dissipation/power factors of the two, but suspect that PVC is much higher than PE.  That's why its only a jacket at higher electric field strengths.

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KD8IIC
Member

Posts: 673




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« Reply #14 on: November 25, 2017, 09:57:54 PM »

  And after all is said and done, there is a U.S. made product known as True Ladder Line which is a durable
  alternative to this labor intensive drill.  Smiley
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