Do-it-Yourself - Professionally
Before getting down to the nitty-gritty on doing it yourself,
let's first compare Ladder-Line with commercial Window-Line.
WINDOW-LINE vs. LADDER-LINE:
Window-line from THE WIREMAN is great for portable operations but for permanent use, I prefer to use Ladder-line instead of Window-line.
Many people believe that Window-line is lossy when it gets wet. This is a myth and has been proven in two seperate, extensive tests:
- In the ARRL Lab, then described in QST in an article by Joel Hallas, W1ZR.
- By Steve Hunt, G3TXQ: http://www.karinya.net/g3txq/wet_ll/
The test by N7WS originally reporting excessive line loss with Window-line was flawed. In his test, Wes used a wetting agent to wet the feedline. This is not representative of real-life conditions, which makes the results unrealistic.
However N7WS's tests did serve a purpose. They produced results which significantly deviated (i.e. were worse) from those produced by W1ZR.
G3TXQ replicated the test, with and without the wetting agent and found the wetting agent to be the cause of the problem.
Steve also found that the velocity factor of the wire changed when wet. This created the need to re-tune the antenna matchbox. After you retune the matchbox, the Window-line's loss was similar to when dry. HOWEVER... if you do not retune the matchbox, then your antenna system will exhibit more loss because it is no longer properly matched. THIS is what has (mis)led people to believe wet window-line has additional loss.
LADDER-LINE DOES NOT HAVE THIS PROBLEM!
Normally there is no need to retune the matchbox when using Ladder-Line. It has very little material for watter to cling to, so its velocity factor is hardly affected when the line gets wet.
For tht reason, I prefer Ladder-Line over Window-Line.
But commercial Ladder-Line is almost unavailable.
Therefore you will need to do-it-yourself.
LUCKILLY there is a company in Germany producing several components which enable us to easily make very professional Ladder-Line. It is not cheap, but not expensive either. It is a fair price for the quality of the feedline you can build with it. THIS IS MY FAVORITE SUCH PRODUCT!
WIRE: I prefer to use (exclusively) WIREMAN CQ-532 (AWG18) or CQ-531 (AWG16).
This is insulated, stranded, Copperweld wire with excellent strength and it does not stretch.
I build all of my antennas with this wire, except my "Ultra-Light" antennas, which use CQ-534, a similar wire but only AWG26.
WIRE SIZE: The Clamp Fork has 3mm spacing, which means it will accept wires up to about 2.5mm which means AWG12, perhaps even AWG10.
by Arno, DL6SX (SK)
All products are built of high-quality UV-resistant material, made of Bayer Bayblend T65 (ABS/PC) plastic, meeting UL-94 (USA) standards.
The material is feather-light, tough as a tank, and definitely UV-Resistant. I have used this stuff for about 15 years now.
Spreaders are available in 4 different lengths, with SP-120 being the most popular amongst hams. But if you wish, you can even build your Ladder-Line wider.
The number in the component name indicates its overall length in mm. Wire spacing is shown in blue to the left of each spreader. The wire spacing is 10mm less than the overall length.
The spreaders use a unique but simple “clamp fork” to enable rapid insertion or removable in the ladderline. Use wider spacing for long runs and closer spacing for going around corners.
When a bend is necessary, simply insert a couple more spreaders andmake the bend, avoiding twisting or skewing of the feedline impedance.
Spacing for SP-120:
• Bends: as needed
I have not measured the impedance of the various possible solutions but they will be approximately 400 Ohms for SP-50 and approximately 600 Ohms for SP-120. Of course it also depends on the thickness of the wire used in the transmission line.
THE BEAUTY of using this system is, it enables you to construct each half-leg of the antenna and transmission line with one single piece of wire. There is no need to solder the transmission line to the antenna.
I have built a sample of the SP-120 solution using RED WIRE and WHITE WIRE-TIES.
These colors were chosen in order to show good contrast.
In real life you may use any color of wire you like but the wire-ties should be BLACK UV-Resistant.
I have absolutely no business relationship at all with the company making and selling these ladder-line spreader products. However the company that I work for (Spiderbeam) is a reseller of the three wire types I mention in the text.
- DX-Wire (Reseller)
Note: Shipping cost for a package of 40 spreaders (SP-120) to the United States is about $6.50 .
Products available in USA
The product below has been recommended by several of my friends in USA.
I am not familiar with it and therefore cannot recommend it because I only recommend products that I have personally used and approved. However this stuff looks good.
Ladder-Snap (Made in USA) spreaders allow you to make ladder-line using 14 AWG THHN wire (solid or stranded) sold at home improvement stores. Quickly you can Snap together your ladder line in lengths you need. Indestructible UV Stabilized Delrin Material.
LOOKS GOOD TO ME, BUT DO YOUR OWN DUE DILLIGANCE! - DJ0IP