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Author Topic: Open Wire Line Spreaders ??  (Read 61139 times)
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WBear2GCR
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« on: September 21, 2008, 10:49:48 AM »

Two questions on open wire line spreaders.

First, is there any sort of market today for open wire spreaders?
(thinking about making some...)

Secondly, it would be a useful archival and informational thing to discuss the pros and cons of different spreader designs, and to post jpegs of various different spreader designs!

Also, are all ceramic spreaders connected to the feedline by some sort of small gauge wire wrap/tie?? (never used 'em!)  Grin

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W2DU
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« Reply #1 on: September 21, 2008, 01:00:41 PM »

Hello Bear,

I haven't seen any spreaders available on the market, but I think there would be a great market for them if you were to make them.

As far as I know, the only feedline materials available for hams are coax, twin-lead,  and window line. We know the tremendous advantage window line gives us over coax for using a dipole over all bands, where coax is limited to fundamental and odd harmonics. But the loss due to line attenuation with window line is still much greater than open-wire line separated with spreaders spaced from two to four feet apart.

In the days prior to coax the usual spreader width was six inches, and with no. 12 wire the characteristic impedance Zo was around 600 ohms. However, there is no magic in 600 ohms when the line is being used with a tuner. Consequently, the spacing can be anywhere from two to six inches, with practically zero radiation at HF.

I'm sure that if spacers were available, do-it-yourself hams would prefer real open-wire lines to window lines to obtain the lower loss attendant with the high values of SWR that accompanies the mismatches that occur when using a random length dipole with open-wire line.

I'd like to see you start such an adventure, and I wish you luck if you do.

Walt, W2DU
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W2DU
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« Reply #2 on: September 21, 2008, 02:45:11 PM »

A further thought for you, Bear. I suggest that you discuss the marketability of feed line spreaders with my personal friend, Press Jones, N8UG, The Wireman. I'd bet the farm that he'd be as eager to sell your spreaders as he is my W2DU baluns. His business address is www.wireman.com, but his personal email address is n8ug@ss.rr.com.

Incidentally, I'm presently using a combination of 300-ohm twinlead and 45-0hm ladder line in both my MI and FL locations. But if you were to make spreaders I'd buy a bunch of them and go back to real open-wire for my feedlines.

Walt, W2DU
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KF1Z
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« Reply #3 on: September 21, 2008, 03:02:54 PM »

You sure that's not,  www.thewireman.com ?

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W2DU
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« Reply #4 on: September 21, 2008, 03:09:32 PM »

Yep, it's www.thewireman.com. Sorry, I goofed. Some call it old age dementia--I call it 'senior moment'. Thanks for the correction, Bruce.

Walt, W2DU
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KF1Z
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Are FETs supposed to glow like that?


« Reply #5 on: September 21, 2008, 03:22:14 PM »

If you dare to buy from them... there are these.....

http://www.surplussales.com/Antennas/Antennas-9.html


But, if you can make them cheaper Bear, I'm sure there's a market.

Plus, I don't see any there for 600 ohm line.....


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W2DU
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« Reply #6 on: September 21, 2008, 04:12:40 PM »

The Johnson CS2 spreader shown in the link listed above is made of ceramic, which is sorta heavy, and would pull the center of the dipole down unless it was supported at the center.

On one of my previous feed lines I made spreaders out of 1/8" fiberglass cut to 3/8" wide by 2 1/2" long, which were much lighter than ceramic. 

There are also clear plastics that could be used for making such spreaders. IMHO, I believe the more progressive ham community would go for open-wire feeders if light-weight, high-dielectric spreaders were available.

Walt, W2DU
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WBear2GCR
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« Reply #7 on: September 21, 2008, 04:30:33 PM »


If there is a problem with plastics it is in temperature.
Some plastics don't like cold at all - get seriously brittle.
Other plastics don't like heat - does the open wire ever get hot??
Oh, other plastics don't like UV.

And, I don't have a means to mold plastic... molds are beaucoup expensive for that stuff!

But, I repeat my earlier request for jpegs and drawings of classic spreaders.
And, how does the feeder wire get attached to the spreader??

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KB2WIG
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« Reply #8 on: September 21, 2008, 04:45:15 PM »

 Don't know da price...


http://www.daburnonline.com/search.aspx?find=antenna


klc
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KF1Z
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Are FETs supposed to glow like that?


« Reply #9 on: September 21, 2008, 05:06:03 PM »


But, I repeat my earlier request for jpegs and drawings of classic spreaders.
And, how does the feeder wire get attached to the spreader??

         
\

Did you look at the link to Surplussales?
Or do you want pictures posted here instead?


Could be wrong, but I believe you use short pcs of wire to hold them in place.... like a "twist-tie".



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Barrie
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« Reply #10 on: September 21, 2008, 05:13:41 PM »

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
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W8EJO
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« Reply #11 on: September 21, 2008, 05:15:12 PM »

W7FG sells 600 ohm ladder line. Here are the pics & prices:

http://www.w7fg.net/
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WA1GFZ
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« Reply #12 on: September 21, 2008, 06:28:37 PM »

I've used Johnson 4 inch ceramic spreaders since about 1968. They will handle up to #10 feed line with #14 tie wire. My present antenna has been up since 1983. I remember Hatry in Hartford sold them .55 each. I space them 30 inches apart. 6 inch spreaders are heavy. I have some but never used them. I guess thay would be good for a lazy H. gfz
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WBear2GCR
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« Reply #13 on: September 21, 2008, 08:06:52 PM »



Posting images here would be good.
Good archival reference too...

I'm just trying to determine which style is most bestest, and of course if it makes any sense at all to look into what would be required to produce a run of them... them being ceramic, unless a better idea comes along.

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KF1Z
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Are FETs supposed to glow like that?


« Reply #14 on: September 21, 2008, 08:21:18 PM »

..


* untitled.jpg (6.63 KB, 173x97 - viewed 921 times.)

* untitled2.jpg (8.7 KB, 183x81 - viewed 879 times.)

* untitled3.jpg (7.24 KB, 161x103 - viewed 930 times.)
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KF1Z
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Are FETs supposed to glow like that?


« Reply #15 on: September 21, 2008, 08:38:18 PM »

And then there's these...
wb3huz has listed for sale here, in the for-sale section.....



* spreader.jpg (29.77 KB, 600x268 - viewed 1177 times.)
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WA1GFZ
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« Reply #16 on: September 21, 2008, 10:03:56 PM »

4 inch Johnson spreaders are about 1/2 by 3/8 inch with 2 holes and 2 end slots. They are unglazed. The longer 6 inch Johnson are glazed. There has to be a lot of wet ice on the feedline to take me off the air. I bet  a little voltage on the feedline would take care of that but don't remember the last time I could have needed to. 
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k4kyv
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Don
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« Reply #17 on: September 21, 2008, 10:13:14 PM »

And then there's these...
wb3huz has listed for sale here, in the for-sale section.....

I use those.  Over the years I have accumulated a good size collection.

In the past I have used the classic EF Johnson 6" ceramic spreaders, but one problem is that if the antenna is allowed to whip around in the wind, the 6" spreaders tend to break.  I recall one windstorm when I had my dipole strung between two trees; the next day I noticed that every other spreader in the entire line was broken.

I have noticed that some of my Johnson spreaders are glazed and others not, in all lengths.  Maybe one had a choice, with the unglazed versions costing less.  I'll have to look up in some of the old ads to see.

I have made my own 6" spreaders using 1/2" diameter plexiglas (acrylic plastic) rod.  I actually drilled the holes and used a power tool to form the end groove to make them similar to the Johnson spreaders, but next time I may try heating the wire and see if it will simply embed itself in the plastic.  Plexiglas is lighter in weight, less brittle and less prone to breakage than ceramic, and stands up for many years under the UV from the sun.

My present feedline that runs up through the middle of the tower is spaced with plexiglas spacers cut out of 1/4" thick sheet stock, and I have one every 10 feet.  The feeders are tensioned with small turnbuckles to hold them in place between spacers.  I drilled two holes in the spacer and threaded the wires through, and used a soldering iron to melt grooves at the ends of each spacer to fit directly over the tops of the Z-rungs of my tower, and tied down the ends with galvanised steel electric fence wire.  They have stayed in place for over 25 years now, with never a failure.  The only problem I have had is that over time they collect bird shit, since birds like to perch on the tower and antenna,  but it hasn't seemed to affect the performance of the antenna.

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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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WA1GFZ
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« Reply #18 on: September 21, 2008, 10:41:14 PM »

Don,
The only time I ever lost a spreader is if it banged against hard. I use #14 tie wire with 5 or 6 wraps on each side and I don't solder them.
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W7IXZ
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« Reply #19 on: September 22, 2008, 12:40:45 AM »

In the early 50's we would cut wooden dowel to 6 inch lengths, drill each end and cut a groove on the ends, and then boil them in parafin canning wax until they quit bubbling.  It boiled all of the moisture out of the wood and helped to seal the wood grain from future moisture.  They were pretty light weight and worked very well.  I used to run a pp 250TH rig with 810 modulators and a Johnson KW Match Box on all bands.  Back then I could not afford the commercial spreaders.  I never had a problem with them.  The method was used by a lot of us back then.  One just had to be careful with the boiling wax as it could burst into flames easily.  I did it outside on a hot plate and an old coffee can.  The old ARRL handbooks explain it and also have pictures.
Larry W7IXZ
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N5RLR
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« Reply #20 on: September 22, 2008, 01:45:17 AM »

eHam has an interesting article here [click]. Wink
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Michael

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k4kyv
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Don
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« Reply #21 on: September 22, 2008, 02:19:16 AM »

I seem to recall that parafin canning wax was mixed 50/50 with beeswax to make a wax solution to seal things  like i.f. transformer coils and rf chokes in early radio equipment.
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Don, K4KYV                                       AMI#5
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ve6pg
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« Reply #22 on: September 22, 2008, 05:31:01 AM »

...i made my spreaders out of  half-inch pvc pipe. light weight, and very durable...there is an article on the web, where the guy uses plastic coat hangers...cheap to buy at the dollar store..just set up a jig, start cutting, drill the holes, and you're done...do a google for homebrew ladder line....tim...sk..
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Steve - WB3HUZ
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« Reply #23 on: September 22, 2008, 08:47:23 AM »

This is the best way to go these days. The W7FG setup is easy and very light. Ceramic is heavy by comparison. But, if you want the old buzzard look and you use the spacer sparingly (every 5-10 feet), the weight becomes less of an issue. I made about 100 feet of line using those Birnbach spacers and used the setup for 6-8 years with no problems.


...i made my spreaders out of  half-inch pvc pipe. light weight, and very durable...there is an article on the web, where the guy uses plastic coat hangers...cheap to buy at the dollar store..just set up a jig, start cutting, drill the holes, and you're done...do a google for homebrew ladder line....tim...sk..
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W1UJR
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« Reply #24 on: September 22, 2008, 10:11:41 AM »

Steve's correct, W7FG stuff works great.
It is reasonable in price, easy to run, and also easy to repair.
I use it at my QTH on the coast, and its subject to some pretty nasty wind loads, works fine.

I'd be the last one to discourage any one from a business venture, but I'm not sure how much of a market you'll have for the spreaders, esp. when you calculate the cost to tool up and produce ceramic spreaders. I doubt you'll find it an economical venture, in fact, if you calculate your costs of materials, molds, labor, etc. might be cheaper for you to buy NOS spreaders from Surplus Sales of Nebraska! The ham market would pay perhaps $1-2 per spreader, maybe as much as $5, but as the price goes up, your target demographic shrinks. If you figure that each spreader might be good for 12" of line, and the average feed line is say 100 feet in length, that means $50 just in spreaders, not to factor in line costs for the wire.

A far as market size, well, I'd say small, most hams don't have the time nor inclination to put together individual spreaders on lines. I like old time radio gear, but most hams greet me with a blank look when I mention balanced feedline. When I explain the advantages, low loss, multi-band use, etc. they see only the difficulties running balanced line vs. coax. The folks who typlcially spend the big bucks on their stations are teh contesters, and most of them have deciated antenas for each band, so balanced line is of little intrest there. There has been somewhat of an awakening in the ham community about balanced line and balanced tuners, but it is a small segment that routinely use that on the air, I just don't see a very lucrative market there. .
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