The AM Forum

Having decided to bite the bullet, I've been looking for various ways to 'do up' ladderline.

This is an interesting method and material....

http://www.youtube.com/watch?v=D--K4Uc5p0I


Coat hanger and pull-ties. I'll probably go with this method; everything at wallmart or in the tool box.

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

Anyone with somecheep spacers?

Any comments??

klc

You really can't get much cheaper than 1/2" pvc pipe, chopped up into 4 - 6" or whatever lengths.
Could drill holes in each end, or use the wire-tie method.
All of course mentioned in other threads.


I have some ceramic 4" spacers... but heavy, and not comparably "cheep".

I have had excellent results with 1/4 inch polyethylene tubing. It's the stuff used for refrigerator ice maker plumbing and costs a few bucks for a 25 foot spool at Home Depot. It is rigid enough to support 4 inch spacing, but probably no more. I just cut it up into 4 inch lengths, slot the ends and snap the wire into the ends. When they are all in position, I walk along with a hot glue gun and seal up the ends. It's very sturdy, weather resistant, and works equally well for fan dipole assemblies. It took me about 3 hours to make 130 feet of feedline.

Nice job with the poly tubing! much easier than my solution.

I grabbed a few of the 1/4 inch fiber glass "driveway markers" and cut them into 4in lengths. Drilled holes at each end.  Sturdy, probably last forever for me, a little heavier than the poly tube. though

Be sure to use something that can withstand UV.  Sunlight is the big killer of most substances.  I have seen window line completely deterioriate in less than 5 years in New Mexico.  You don't want to be redoing it in a short period of time. 

3/8" white PVC pipe also works good. Light, cheap, and available at home dumpo. I use it for my antenna spreaders, and it has been up close to 10 years now.

When I was doing my vent stack I asked the building inspector about PVC and he told me all the new PVC pipe is ok in the sun

That guy on YouTube is making 600 ohm worthless transmission line. And using stranded color coded wire.........geeesh! What happened to #8 solid??

Pulling chains here.......................laughing sounds please.

Phred

I also used 1/2" PVC pipe/tubing.  Works fine for me.  What's wrong with 600 ohm line Fred?  I used 6" spacing and #12 THHN insulated wire, just 'cause that's what was available and it works FB OM for a 600 ohm line!  Those old buzzard porcelain spacers are cool, but very heavy and fragile.  I had a bunch of them, but learned the hard way that they are not very durable and become quite heavy with a long length of line.

You can use plastic hangers. ladies' plastic curlers, driveway marker fiberglass rods, ball point pen barrels, even pieces cut out of old plastic milk jugs for spacers.  It all works and it all provides a cheap, but effective low loss transmission line.

73,  Jack, W9GT

Gud ideas gents.....  I was leaning towards the coat hangers as the black won't stand out as much. Trying to keep the Xyl somewhat happy. The feedline will exit on the garage side, so she'll see it when she comes up the driveway (The last 120 feet is at a 10 deg rise).....


klc

Be careful with the black coat hangers. They could contain lampblack (carbon black pigment) which may have conductivity at RF. This was pointed out to me on the board back a few months ago. I did not test the pile of black (Walmart) hangars I picked up, but it seems like something to check out before you invest a lot of time and effort!

Not a thing Jack........just pulling chains. I had a thread elsewhere about my ammeters not reading after I changed my system out from 450 ohm window line to the real 600 ohm ladder. I'm very happy with my new setup.

Fred

A few seconds in the microwave will tell the story! Looks pretty cool though.

Kevin ,

I have ceramic 6" spreaders that you are welcome to . I think I have about a dozen.

You want to use a few as necessary. The more spreaders the more capacitance you are adding to the system. I had a 200 ft run that ran horizontal and it had only 4 spreaders and then it went 60 ' vertical with 4 more.

The system worked well until I went with my current system the directional array which I used coax. I miss the open line because it allowed using many frequencies but the array can out "hear" the other system.

G

Gary I could use them if you don't give them away. I have 13 and need some more for a lazy H I want to build. I'd pay for them even.

If your using insulated wire, I doubt the pigment of the black plastic would hurt too much. 

A LOT of plastics that don't contain carbon melt easily in the microwave....

How would you tell if the material is conductive at RF frequencies, just by putting it in the radar-range?

G,
Thank you very much...The ceramicspreaders  sounds like an easierway to go. A PM follows.

"the array can out "hear" the other system"

 Maybe i'll try a beverage or two in the spring. I've got about 1300' east-west to play with."

"How would you tell if the material is conductive at RF frequencies, just by putting it in the radar-range"

Bruce, that'll tell u that it absorbs energy at that particular frequency. Whether that helps??, don't know.  I'd guess that running some ladder line made with the material in question into a dummy load at a particular frequency may give a better data point.  Or just wire up and test it that way.

Again, to all youse that made comments, thank you.

klc

(Buddley, joan crawford will thank you)

Not sure I understand what makes it worthless nor what makes #8 solid any better that stranded?

Frankly, I think aluminum fence wire is about the best all around antenna wire there is at our humble power levels.

What I found most interesting was his squeezing the wire to get a press fit.  If you did this right, you might not even need the hot glue.  Very clever.

js

I commend the old guy for making his own.   Probably got the time.  Why not?   

I picked up a bigg stack of brand new Ceramic insulators at a ham fest. Look like 6 inch.  The thing about using them is they are so heavy.

Anyone have ANY idea about the power capability of 18, 14 or 12 or 10 AWG ladder line?   

C

ke7trp,

I've used the 1/4 inch "driveway markers" and #14 solid copper. Cut the fiberglass rod to about 5-1/4 inches in length, notch the ends for the #14, and then drilled a hole a little farther inside to loop a 1 inch piece of #14 around the parallel line to hole everything together. Spacing is about 5 inches for somewhere near 600 ohm line.

The Junkston Desk KW can run full strap on this line feeding a 40 meter dipole.

On 75 meters, I feed the ends of a full wave loop to a Junkston KW matchbox. The loop is made of #14 THHN. The Desk and a "500" are quite happy and haven't started any fires in the neighborhood yet.

wd8kdg
craig,

Ok.. I have 16 gauge stranded.  I hope I dont light it on fire.. LOL


C

It depends greatly on the mismatch of the system.  If there is a huge swr, then you will have current maximas that are so large it will heat up certain diameter wires. For example, I once fed a W8JK that had an input of about 5 ohms. I used very heavy open wire line, like #5 wire spaced 6".  Running a KW, the openwire actually arced across from the voltage maximas.  The current maximas had to be huge too, but the large diameter wire handled them without obvious heat.

There are cases of guys melting that brown plastic openwire when feeding say, a 40M dipole on 75M. The mismatch was high.

So, generally, if you run 1500w pep on AM, use at least #14 or #12 wire for normal use when the flat top is at least 1/2 wavelength long on the lowest freq. If you want to feed a dipole that is only 1/4 wave long then you will need much heavier openwire diameter and a strapping tuner of large diameter coiling and hardware. But bear in mind that on the higher bands you will have some spots that have large mismatches, so try to use larger diameter wire, like #10 if you can for multi-band 10M-160M use.

But the easiest way to check is to load up the antenna on various bands, drop a BIG carrier for a few minutes (on a clear freq) then unkey and feel the openwire for at least 1/4 wave up and down its length looking for hot spots.

T

Ok..  Thanks for the info.  Its a KW AM.  The antenna is resonant a 3900.  Open wire, flat top. Going to use it in the ghetto. I think I should be ok.  Time will tell :)

C

Good to know numbers.

Now the questions are:

a. Do these apply to the flat top portion also?
b. Does the surface area of stranded vs solid offer an advantage?

and a sort of unrelated question:

I am going to take down my 80 meter steel fence wire dipole and replace it with aluminum fence wire.

As long as I have to cut new wire and I can make it any length I want,  I am having a hard time finding anyone to suggest a best length for the flat top.

The present setup is very usable on 80 through 20 using a tuner and 450 ladder line (the brown plastic stuff).  I only run legal limit on 80 and about half that on the other bands (different transmitter).

I run a net every day on 3870 so I want max performance there and elsewhere can be a compromise.

If I ever stumble into a big tuner that covers 160, I guess I cold eliminate the 80 meter dipole completely and put the 160 where it is.

I assume that a 160 open wire fed with a tuner would work as well as the 80 on 80?

So, I guess the question is, is there an optimum flat top length for 3870 that will still allow 40 and 20 operation?

js

Read the open wire line thread by KC6MCW.  There is a ton of info on that thread.   ALOT of BS also. So you have to weed through it.   

C

Hi Jack,

Yes, large diameter wire also applies to the flat top cuz the flat top will see basically the same current maximas and minimas as the feedline, depending on its length and the length of feedline for a particular freq. But just assume this to be so.  You want a strong flat top anyway. We always start at a voltage maxima at the end insulators of the dipole flat top and work our way back with a current maxima 1/4 wavelength from the end insulator and so forth down the feedline.

The only advantage I can see for solid wire on HF is it is less prone to deterioration when exposed. I've seen a solid single strand of #8 last for 30 years. But the thin stranded stuff will break down quicker, simply cuz of its diameter. If a single large solid strand gets corroded 1mm, it's no big deal. If a tiny strand gets 1mm, then its a problem when all the bundle gets it, strengthwise.  But for HF, I can't see any diff in skin effect. I use stranded #10 for all my wire antennnas for years. I use the inexpensive stuff from Home Despot on 500' rolls with insulation.

As for optimum length for 80-20M... it is all about antenna pattern. The best pattern to maintain is a figure eight on all three bands - that would be about 90'.   But if you put up a standard 130' long dipole, it would have a standard figure 8 on 75M, a sharp figure eight on 40M with 2db gain, but on 20M a cloverleaf with a sharp null broadside. The 20M is the problem.

I would put up a 180' flat top and use it for 160-40M as a great figure 8 antenna. Then stick up a small coax fed dipole for 20M for a nice figure 8. That wud be a good solution. An alternative would be an open wire fed 22' long flattop that wud make a figure 8 on 10M-20M.

T

Do you have an ex wife in the copper wire business?

Funny but I just completed some extensive tests comparing steel, stranded copper and aluminum on a 160 meter dipole, both using MMAMA modeling and real antennae.

I concluded that any advantage copper has is more than offset by the lighter weight of the aluminum.

This applies to an end supported dipole.  If it can be supported in the middle at the same height as the ends, then copper has nominal advantages.



js

I will be interested in hearing how aluminum holds up.  I have always heard it doesn't do well as antenna wire -- wind movement introduces metal fatigue and breakage and/or it snaps under icing.  I know big stranded aluminum is used for service drops from pole pigs but those are usually not long spans or are large gauge.  The other prob. is the hassle of making the metal transition from Al to Cu and soldering.  You can crimp maybe but you have to work out an aluminum brass copper transition somewhere I would think.

The antenna v2.0 I made with hard drawn copper is about half the weight of the one I had up using insulated THHN. both #14. That insulation adds a lot of weight. I'll stick with HD copper, the copperweld stuff is too hard for me to work with. I dont believe in aluminum for antenna wires - for tubing it works quite nicely.  :)

damn pulleys still not here yet.  >:( I cant proceed until they get here.

FWIW I had 124' centerfed #8 THHN supported only at the ends for 3 years in a very windy location using wimpy trees.

It took a hell of a beating.

I tried to inverted V it, but it's just no good. too many snags. I'm hoping that by riding on pulleys the antenna will stay up for good. Wife wants me to get a tower and quit farting with trees. Come spring I'll be happy to make that happen.

No radio operating = s&%# quality of life.  :( 

tomorrow and tuesday looks good to putting it back up.

Now that's a good point...

Is it the added CAPACITANCE that the ice or water adds that makes openwire change characteristic impedance or will the DC short of ice/water make a difference with bare wire?  The reason I axe is I thought water (aside from acid rain) did not conduct well - it was the minerals in the water that made it conductive.  Maybe the stray minerals sitting on the spreaders and bare wire make a big difference when they mix.

I guess my question is, how much is the effect from capacitance (which would affect insulated wire too) vs: the effect from actual contact with the bare wires?

I remember having a dipole on Nantucket and had to spray it down every few days due to the shorting action of the salt spray. It was that bare openwire stuff with the little white insulators. Salt is an extreme case of course. I wonder how it wud have been if the wire was insulated?

T

Somebody PLEASE correct me.....But I do bvelieve that Timtron is using open ladderline 6inches spacing(?) MORE??? and transmitting 50kw, WBCQ transmitters, through it. And it works every day with no snags. PLS click on link.
Tim would not do anything that would compromise reliability.

Phred



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