Open Wire Line Spreaders ??

[ke7trp]

I guess we are lucky with this little 16 gauge wire!

C

[W2VW]

Full strap from the GPT-750 into my 75 meter dipole on 160M, the edgewound coil in teh tuna gets slightly warm and I get talkback from the vacuum cap, but the 16 ga W7FG is stone cold to the touch.  The feedline is such that it's at a high impedance point for 75, which would put it at a low point for 160 (hence the ant taps on the coil being only a couple turns from the center).

That's as severe a test as you'll find with uh, "reasonable" power... sometimes better is the enemy of "good enough"- extra weight, wind loading, ice collection, etc.

Model the feed point impedance on 160. Next, calculate the R.F. current at the feed point given reasonable power

[AC4R]

www.youtube.com/watch?v=qzFKGB6qkXs


The easy way to make true open line. If the link doesnt work go to you tube and search N4LQ.  He makes open line using ink pen barrells as spreaders. If you use the Bic stik pens you dont even have to cut them, simply pull out the ink cartridge and remove the plug from the other end . You secure the spreader to the wire using 1 cable tie for each spreader. No more drilling and cutting pvc spreaders and then threading them thru the line. This is the best plan yet for true balanced line.

AC4R

[ke7trp]

Thats really pretty neat.  It wont last very long.  1 year in az heat those zip ties break. I have tried to use them on all sorts of outside uses. They turn brittle and crack with almost no force. 

That is a really neat idea.. Gotta hand it to the guy

C

[w3jn]

Model the feed point impedance on 160. Next, calculate the R.F. current at the feed point given reasonable power

THat sounds too much like work 

I did, however, do a sweep of the ant with the HP3577A VNA and an external HP return loss bridge.  While the results aren't valid because I just hooked the feedline directly to the 50 ohm bridge (this wasn't an attempt at a serious modeling, just messing around), around 2 MHz it was way on the right side of the center of the Smithy chart.

[KA1ZGC]

Thats really pretty neat.  It wont last very long.  1 year in az heat those zip ties break. I have tried to use them on all sorts of outside uses. They turn brittle and crack with almost no force.

Not to nit-pick, but that's the result of UV exposure, not heat.

There are zip ties that are made for outdoor use from plastics that aren't as UV-sensitive.

Personally, I prefer to use fiberglass garden rods. Cut to length, drill through the ends, thread the wires, tie some retainer wires in place, and you're done.

[ke7trp]

The UV and the heat comes from the same source. The sun.  This is the valley of the sun.  Not to nit pick..

We have UV protected Zip ties here also.  The last 6months to a year. Then they are so brittle they crack with your fingers..

C

[flintstone mop]

W7FG has an ad in QST each month advertising open wire line.

I've been using it here for several years since I built a link-coupled balanced tuner.  Seems to hold up FB.

He uses lightweight, black, thinwall tubing.  I think it's the kind used for underground sprinklers.  Each spreader has a slot cut/ground into each end.  The wire is squeezed into that slot.

He uses insulated wire.  I don't think that bare wire would work for that method.

73, Barrie, W7ALW

I'll have to echo Barrie. I also have the W7FG ladder line/antenna. It wasn't stressed with extreme high winds and ice, but it DID make it through our Western Pa Winter without any problems.

FRED

[ke7trp]

Its SILV O line tubing.  I think its grean dot from memory

C

[ka3zlr]

Howdy,

That is a great Video.....neat idea.

73
Jack

[KA1ZGC]

The UV and the heat comes from the same source. The sun.  This is the valley of the sun.  Not to nit pick..

...just to be a smart-ass, then?

[ke7trp]

You started it..

C

[Ed/KB1HYS]

I have two of these ceramic tubes, about 3/8th inch in diameter and 4 inches long.  No idea where they came from.   Very thin wall (~1/16th?) but they are tough. Not sure what they are made of, too bad I don't have about 50 or so, I could use this guys technique and some RTV to seal the ends/protect the ties and have the Cat's Meow of wire line...

[k4kyv]

Personally, I prefer to use fiberglass garden rods. Cut to length, drill through the ends, thread the wires, tie some retainer wires in place, and you're done.

What are garden rods?

How long are they and what diameter? Where do you buy them?

Wonder if they are about the same thing as the fibreglass electric fence posts I mentioned.

[KX5JT]

Max-Gain Systems has fiberglass rods....

http://www.mgs4u.com/fiberglass-tube-rod.htm

The following seems reasonable and I'm sure a few of them could be sawed to size and the zip-tie method from the video would work fine!  Has me thinking!

1/4"OD    (9/64" ID)    0.240    1/16"    8 ft. Black     RT-14-964-8    $4.50

$4.50 for 8 feet! 

[Steve - WB3HUZ]

They are often used for tomato stakes and the like. They are maybe 1/4" diameter. HTe Lowes and  Home Depots of the world sell them.

Personally, I prefer to use fiberglass garden rods. Cut to length, drill through the ends, thread the wires, tie some retainer wires in place, and you're done.

What are garden rods?

How long are they and what diameter? Where do you buy them?

Wonder if they are about the same thing as the fibreglass electric fence posts I mentioned.

[WBear2GCR]

Why do you need 12 ga wire in high impedance feeders?

Why does a Dragster need big tires?

C

to get the horsepower transmitted down to the ground!

              _-_-

[KA1ZGC]

They are often used for tomato stakes and the like. They are maybe 1/4" diameter. (The) Lowes and  Home Depots of the world sell them.

Yep, those are the ones. About 1/4" to 3/8" dia., green fiberglass. Picture a green arrow shaft about 5 feet high.

I just cut, drill holes in the ends (a vee-block on a drill press is all it takes), and thread them exactly like one would thread open-wire line with ceramic spacers.

Caveat emptor: this came up in a thread a few years back, and someone mentioned they'd picked some up from some home mega-store and discovered they were actually steel rods cast in fiberglass. The ones I got were solid fiberglass, but that was many years ago.

Just wanted to pass that on in case someone was thinking of buying some en masse only to hit that same snag. I would recommend buying one or two to see what they're made of. If they're no good as spacers, you can always find some good use for them.

[ka3zlr]

Why do Big Fat Babies Produce Big Fat Farts....lol.....just because...

73
Jack

It's still a Neat Idea......

[k4kyv]

They are often used for tomato stakes and the like. They are maybe 1/4" diameter. (The) Lowes and  Home Depots of the world sell them.

Yep, those are the ones. About 1/4" to 3/8" dia., green fiberglass. Picture a green arrow shaft about 5 feet high.

I just cut, drill holes in the ends (a vee-block on a drill press is all it takes), and thread them exactly like one would thread open-wire line with ceramic spacers.

Caveat emptor: this came up in a thread a few years back, and someone mentioned they'd picked some up from some home mega-store and discovered they were actually steel rods cast in fiberglass. The ones I got were solid fiberglass, but that was many years ago.

What I would question is the substance they mix in with the fibreglass to make it green. If there is no metal inside, I would still cut a piece and run it in a microwave oven for a couple of minutes (along with a small glass of water for safety reasons) and see if it warms up.

The electric fence posts are closer to 1/2" in diameter, and white.  I have never checked them out in the micro, but plan to use them this summer when I re-do my feedline that runs down to the tower.  I just hope they haven't "discontinued" them, per the usual case of commonly available items when I go to purchase them. I should check these for a wire core, too.

[KA1ZGC]

What I would question is the substance they mix in with the fibreglass to make it green. If there is no metal inside, I would still cut a piece and run it in a microwave oven for a couple of minutes (along with a small glass of water for safety reasons) and see if it warms up.

That is an excellent point. I never thought of that.

It's a fairly light green, paler than chlorophyll, actually you might call it a "pastel chlorophyll" (if you're a complete sally). Fairly close to the color of lime juice.

Not far from the color of the Statue of Liberty, which is why I'm surprised I didn't think of that.

I know copper is used to make green pyrotechnics, and it wouldn't surprise me if it were also used as a green pigment. If it's cost-effective to make white house paint using titanium for color (and it must be, because they do), it can't be much worse to use copper to make green fiberglass.

Never nuked it, but used it for spacers in feedline and an indoor antenna at Drake TR-4 power levels for several years. When I took it down, there was no discoloration or distortion, which I did check for. Tuning was normal as could be expected, given that the antenna design was unusual and likely very reactive to start with.

Either way, nuke-checking potential spacers is good practice. Since I may be replacing the feedline in Albion this summer, I'll make sure to do that with the next batch of spacer material I pick up (after ensuring they don't have metallic cores, of course).

[k4kyv]

Everything has to be green these days.

http://www.sourcewatch.org/index.php?title=Greenwashing