Open Wire Line Completed

[k4kyv]

The cross-arms will be made from 1 1/4" X 1 1/4" solid aluminium stock ordered from McMaster Carr, and mounted on the poles using angle brackets and U-bolts.

 Great finding Don! I hope you will post the end result.

http://amfone.net/Amforum/index.php?topic=28037.msg214722#new

Here are some snapshots

The spreaders are made of plexiglass rods.  I first made them when I was in Houston in 1977 for the end-fed zepp; they were 6" long.  I still had a few that I had kept for all these years in the antenna insulator collection, so I cut them to 2 3/4" in length and made additional slots and holes, enough to make the 24 insulators used in this line. A good example of why I never throw anything away.

[k4kyv]

At the shack end

The loop at one of the insulators is to maintain exactly equal lengths for both feeders, with the transmission line coming to the wall at an angle. The spacing of the feed-throughs is greater than the line spacing, to maintain proper spacing of the line despite the angle of termination.

[k4kyv]

Line towards tower

[Todd, KA1KAQ]

Nice job, Don. Looks like a commercial installation. The reason I never ran balanced feeders before was always due to the twists, turns, and proximity to metal roofs and so on. Your approach addresses all of those problems with its supports to keep it straight and out of contact with anything. Something to shoot for!

[K1JJ]

Wow, very strapping installation, Don!  Should last a lifetime.


BTW, maybe by adding a pole at the house -  would let you tighten up the OWL and control cables run at that point to keep the strain off the junctions.

What are that pair of poles in the background supporting - looks like a 10M lazy H or something?

T

[k4kyv]

Wow, very strapping installation, Don!  Should last a lifetime.


BTW, maybe by adding a pole at the house -  would let you tighten up the OWL and control cables run at that point to keep the strain off the junctions.

That's exactly what I did.  That pole is the one shown with the pair of turnbuckles and the overhead loop to keep lateral tension off the stand-off insulators, and it is securely guyed, just like the pole at the tower end.  The stretch of line from that pole to the shack wall is only about 14' and the line is allowed to sag, not pulled to a lot of tension. I set the pole far enough away from the shack to easily get the riding lawn mower in between the guy wire and the building.

What are that pair of poles in the background supporting - looks like a 10M lazy H or something?

That's my K6STI 160m low-noise receiving loop, built per a couple of articles in Sept 1995 QST. It never worked worth a crap, but it's less trouble just to leave it standing than than to take it down.  And I may try to see if I can make it perform better, one of these days. Actually, that antenna did serve a useful purpose; when I finally decided it was worthless for its intended purpose, that motivated me to built the beverage, which has given excellent results on several bands.

BTW Tom, I have a question for you. Remember a few years ago you sent me a link to an outfit that sold full-body climbing harnesses. I developed a hip problem shortly thereafter and couldn't climb for a while, so I didn't jump right in and purchase the harness. I eventually had corrective surgery and now my hip is fine and I can climb just as well as ever. A few months ago I clicked on that link, but though the company still sells tower stuff, evidently they no longer carry climbing gear.  Wonder if you could tell  me the make and model of that harness you recommended.  I recall it cost about $115 and was the mid-line product.  I believe you said you used one. I need to  search and see if I can find some other vendor who sells that same product. I found a few others listed on some web sites, but the harnesses I found do not seem to have all the features of the one you recommended.

[K1JJ]

Yo Don -

Here's the old thread, but alas, I see the link to that harness is bad.

http://amfone.net/Amforum/index.php?topic=26962.0

I looked at my harness here and there are no ID tags except OSHA jargon.

Here's a pic below, so maybe you can match it up to something out there. Someone suggested that Grainger carries harnesses too. The back view uses an "X" pair of belts with a steel loop joining the two belts.  I don't use the rear loop for anything - rather tie the lanyards to the chest loop. A fall will keep me from smashing my face into the tower with the chest connected instead.

Be sure to get a short gorilla hook that goes from the center belt buckle to a direct connection to the tower. This optional hook saves much time when climbing and belting off. Using the straps are a lot of work, though I still use them as backup once positioned.


BTW, with that back-guyed post near the house, the XYL could use it as a clothesline. (until you key up)

T

[WA1GFZ]

Don,
Make sure the threaded rod going through the wall has plenty of insulation.
I set the house on firs once showing off the big rig. A friend went outside to watch the power meter spin and reported smoke coming out of the wall.
Looks very nice W6AM quality

[W3GMS]

Don,
Great job!  It looks like you could string 33KV lines for the utility company.  Very neat work. Some 30 years ago I made my spacers just like you did.  I went overboard and put them every 12".  Never a failure with the line and it looks as good as I put it up years ago.  I used 3/8 lexan solid rod stock as spacers.
Joe, W3GMS

[K5UJ]

Don, way to go--very buzzardly and strapping--looks like there has been an upside to poor band condx although I hope it wasn't hot as hell when you were setting up the feedline.  That solid aluminum stock must have cost a fortune.  How did you make the recesses in it for the porcelain?  You may have said and I missed it.  I am interested in all things machining--a retired machinist has lent me a shop textbook he uses for his apprenticeship training.  Anyway the whole thing looks like it could handle a few KW no problem--I'll be interested in hearing how it plays with RF.  

I was a little surprised at first to see the dipole feed straddling one of the tower legs and braces and wondered if there would be any noticeable difference in tower coupling on 75 m. if it went between two legs but I guess since the leg is perpendicular to the feed it isn't an issue?

Tom you have a sharp eye, I also noticed that folded dipole looking thing between the two poles in the shackend.jpg photo and wondered what was up with it.

rob

[Mike/W8BAC]

Nobody has mentioned it directly yet Don but I'm sure the copper wire wrapping of the feed lines to anchor the OWL to the insulators took some practice. I don't see any distortion if the OWL at all due to twisting the heavy copper wire restraints. Nice job from soup to nuts. Looking forward to hearing you this fall.

Mike

[Opcom]

That is a fine job!

[k4kyv]

Don, way to go--very buzzardly and strapping--looks like there has been an upside to poor band condx although I hope it wasn't hot as hell when you were setting up the feedline.  That solid aluminum stock must have cost a fortune.  How did you make the recesses in it for the porcelain?  

I bought the 1¼ X 1¼ inch stock from McMaster-Carr. It cost about $13.50 per one-ft. length. I used two pieces to make five 4" cross-arms.  I ruined one by breaking off a pilot-hole drill bit inside the metal, so I ended up with just exactly enough.

The stock was cut into 4" lengths using a hacksaw, carefully marking the stock on all 4 sides using a square and extra-fine permanent marker, chucking the stock in a vice, and cutting it very carefully with the hacksaw so that the cuts came out square.  The insulators are 3/4" diameter. I purchased a 13/16" drill bit for the job, and drilled the holes 1" deep using a drill press. The insulators are set in the holes using J-B Weld, and a bead of roofing tar seals the base of each insulator to keep water and UV away from the epoxy.

I was a little surprised at first to see the dipole feed straddling one of the tower legs and braces and wondered if there would be any noticeable difference in tower coupling on 75 m. if it went between two legs but I guess since the leg is perpendicular to the feed it isn't an issue?

It took a sharp eye to see that! I can't even see it in the photo myself. That feed line, #10  copperweld spaced 2" apart, goes up through the interior of the tower, spaced at the geometric mid point of the triangle with a strip of plexiglass at 10 feet intervals.  The wire is fed up through holes drilled in the plexiglass, which is attached to the tower, wired to pairs of horizontal braces. The direction the feed line runs away from the tower to the dawg-house requires straddling the tower leg.  I wanted to keep the line straight and symmetrical, and the tower legs are set the wrong way for the line to come out in between. The wires are carefully bent so they are each spaced equally from the tower leg, with enough clearance not to arc over to the tower.  The ceramic knife switch shorts the feeders to the tower for additional lightning protection.

The surge impedance of the OWL up the tower calculates to 438 ohms (close enough to 450Ω). To maintain the same impedance with the run from the shack to the tower using #8, the spacing is increased to 2 17/32 inch spacing. One switch option at the tuner configuration feeds the OWL directly through to the line running up to the dipole, so I can experiment with locating a balanced tuner in the shack, to directly feed the dipole using the OWL all the way through as tuned feeders.

[K5UJ]

<<It took a sharp eye to see that! I can't even see it in the photo myself. >>

Don any photo you put up of ur rigs/antenna farm is going to be gone over as if we're CIA photo analysts 

Terry looks like you used one of those big brown Johnson cylindrical insulators for your feedpoint.

[W2PFY]

Terry looks like you used one of those big brown Johnson cylindrical insulators for your feedpoint.

Me?

[K5UJ]

Terry looks like you used one of those big brown Johnson cylindrical insulators for your feedpoint.

Me?

thought this was yours; must have been someone else:

http://amfone.net/Amforum/index.php?action=dlattach;topic=28303.0;attach=27400;image

[W2PFY]

Ok, That is mine but it is not round but works just as good as a round one