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antenna leads broken by wind




 
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Patrick J. / KD5OEI
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« on: April 30, 2017, 08:43:29 PM »

Today I found a bunch of window line on the ground. The dipole is still up but the transmission line is no longer attached.
The wind of the recent weather no doubt. The transmission line is attached fairly free to float in the breeze. I guess the constant twisting of it snapped it off up there.
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« Reply #1 on: April 30, 2017, 09:23:13 PM »

Today I found a bunch of window line on the ground. The dipole is still up but the transmission line is no longer attached.
The wind of the recent weather no doubt. The transmission line is attached fairly free to float in the breeze. I guess the constant twisting of it snapped it off up there.

Yup! Wonder if this is a common failure mode
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W6TOM
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« Reply #2 on: May 01, 2017, 07:59:44 AM »

 I'm about to change my antenna system, at present I have a 80/40 meter coax fed fan dipole, using a 60 foot redwood tree along my back property line as the center support. Years ago I paid a tree climber to put a pulley way up in the tree. This antenna has worked out well, the only issues has been clearing branches that fall onto it, Redwood trees shed a lot. I've had to take one end loose and shake those off a few times, the 40 meter section which is supported by plastic standoffs under the 80 meter section has been blown around the 80 meter section in a wind storm, same cure take that end loose and shake.

  This antenna has been in the air now for 6 or 7 years and served me well but had limited bandwidth and band coverage.

  Now I have a window line fed dipole I plan to replace this with, I'm using the WA1FFL center support. I need to have another tree climber come in and clear some branches up high that have grown in the way of my lowering the old antenna. I have to run about 60 feet back to the garage which is where my shack is. The plan is to put up some 2 X4's and run some Dacron rope as a messenger cable for the window line.

  I am concerned about the window line breaking over the years of flexing, no snow or ice issues here in the Bay Area but we can get some good wind/rain storms in the Winter.

  Any advice from those who have done this previously would be appreciated.


* Balanced Line Dipole.JPG (143.87 KB, 904x768 - viewed 62 times.)

* Tree-2.JPG (368.86 KB, 768x1024 - viewed 65 times.)
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« Reply #3 on: May 01, 2017, 08:35:19 AM »

I have a doublet fed with window line and the ladder lock center insulator.  I has a cinder block-pulley tensioner.  It as been up now for twenty years.  Unfortunately the one tree is about dead and the rope is grown into the tree, so it looks like a new antenna after getting some trees removed.
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« Reply #4 on: May 01, 2017, 08:37:47 AM »

I am using heavy duty window line with 14 gauge copper clad steel conductors.
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« Reply #5 on: May 01, 2017, 10:08:51 AM »

....snip ....  Now I have a window line fed dipole I plan to replace this with, I'm using the WA1FFL center support. I need to have another tree climber come in and clear some branches up high that have grown in the way of my lowering the old antenna. I have to run about 60 feet back to the garage which is where my shack is. The plan is to put up some 2 X4's and run some Dacron rope as a messenger cable for the window line.

  I am concerned about the window line breaking over the years of flexing, no snow or ice issues here in the Bay Area but we can get some good wind/rain storms in the Winter.

  Any advice from those who have done this previously would be appreciated.

I got me one of those.  Never used it as I'm using a coax fed system plus tuner

a
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« Reply #6 on: May 02, 2017, 12:32:59 AM »

Previously I used a piece of copperweld ladder line with stand offs and one of the leads broke. The tower had to be climbed.

This time was window line 450 Ohms type, solid conductor, hanging off the center insulator with plenty of slack. The free hanging line means the center insulator which is supported by a pulley can be lowered to where it can be got at with a step ladder. Just need to wait for my friend to assist holding the ladder and hopefully this can be fixed more easily.

It may be the center insulator moving around,  plus this time the freely slack window line may have contributed.

Would some kind of flexible ends on the window line help? or maybe just be one more thing to break. Trying to understand /learn about what happened and take steps to reduce the weakness.

The white T-shaped contraption shown in the photo there might be an idea to limit movement of the soldered area and expand any flexing to a larger 'radius' along the window line.
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« Reply #7 on: May 02, 2017, 12:59:22 AM »

I use open wire line, stressed between supports.

But, I had problems with the OWL and the antenna leads coming disconnected.

I found if I bound the feedline to the center insulator and left about 4 inches of the OWL flying, my problem ended.

My center insulator is a piece of 1 inch pvc.  I ran the OWL perpendicular to the insulator and used a pair of zip ties (uv sterile, good ones) crossed over each lead, total of 4 zip ties.

I'd offer pics, but it's 40 feet up. Lol

--Shane
KD6VXI

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« Reply #8 on: May 03, 2017, 10:24:38 PM »

Previously I used a piece of copperweld ladder line with stand offs and one of the leads broke. The tower had to be climbed.

This time was window line 450 Ohms type, solid conductor, hanging off the center insulator with plenty of slack. The free hanging line means the center insulator which is supported by a pulley can be lowered to where it can be got at with a step ladder. Just need to wait for my friend to assist holding the ladder and hopefully this can be fixed more easily.

It may be the center insulator moving around,  plus this time the freely slack window line may have contributed.

Would some kind of flexible ends on the window line help? or maybe just be one more thing to break. Trying to understand /learn about what happened and take steps to reduce the weakness.

The white T-shaped contraption shown in the photo there might be an idea to limit movement of the soldered area and expand any flexing to a larger 'radius' along the window line.

I use a similar method to raise my antenna. I use cable ties to secure the ladder line spacers to the rope as I pull it up. The rope is tied off a few feet away from the tower to keep the feed line away from it. Depending on your situation you may not be able to go down too far but I think every inch would help. I'm not sure how that would work with window line vs 600 ohm ladder line, especially on a rainy day.
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« Reply #9 on: May 04, 2017, 08:39:01 PM »

Quote
This time was window line 450 Ohms type, solid conductor

Wow, Too bad that happen. I use window line but it is the stranded 13 gauge copper clad stuff. I don't think it would break in 100 years unless I lived in tornado country?

I have up 250 feet of the stuff and this summer I am going to drop it down and somehow cut out the windows out and use 3 inch electric fence spacers. I wish I know where to find a propane hot knife to cut those sections out? Maybe a good pair of industrial scissors would do it?  Here in the NE there are times when you're actually transmitting, the swr becomes so whacked out when snow and ice gets on it that it becomes impossible to keep the transmitter happy. Maybe if I had a loop up, I could hook a filament transformer up to it and melt the ice that forms on it?
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« Reply #10 on: May 06, 2017, 12:14:37 PM »

...
  Any advice from those who have done this previously would be appreciated.
Tom, I had good luck with 300 ohm window line and a lightweight end insulator not intended as a center insulator. Sorry I don't have a picture. I cut out a couple of the steps, looped the still-insulated wire over the ears of the insulator, one on each side, closed each loop with a wire tie, stripped the wire and soldered to the antenna wire secured to the holes in  the insulator.  This ham-special center insulator was supported just above the canopy of an oak by a light-duty telescoping fiberglass pole, un-guyed, just woven through the branches. The whole set-up bent and swayed with the wind but stayed up, didn't break, and lasted until I took it down, a decade later.

The 300 ohm stuff didn't get caught in the branches as easily as the 450 ohm line and is lighter.

I've been leery of putting antennas right in trees but am considering it now. I know the high voltage ends can cause fires but the center should be low voltage and safe for a dipole. Is this what you've done, put the center among the branches?


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« Reply #11 on: May 06, 2017, 06:28:56 PM »

Quote
This time was window line 450 Ohms type, solid conductor

Wow, Too bad that happen. I use window line but it is the stranded 13 gauge copper clad stuff.

where can this be bought?
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« Reply #12 on: May 06, 2017, 08:27:13 PM »

Google The Wireman.

https://www.thewireman.com/
[url=http://]]]

https://www.thewireman.com/
http://
https://www.thewireman.com/antennap.html#balanced Item 554

 It may be a lot less money to make your own out of their item # 531.

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« Reply #13 on: November 11, 2017, 07:51:19 PM »

Today some friends helped me fix the antenna.  The 4 legs of open ladder line made lowering it a real pain as it would catch on every guy wire and tree branch.

Once it was down, the ladder was removed and it is now a single dipole of #14. Back up it went.
I was counseled to have the wire as long as possible, so it is going to be a little longer than the 63-65FT per side it was before. I'm not sure I prefer that but he said the tuner will adjust for it just like before since I am using 450 Ohm window line from the center of the dipole to the transmitter.

First thing noticed going from the 4-legged 'dipole' made of ladder line to the single wire 2-legged dipole that is more conventional for ham use is that the tuning of the tuner is much sharper. I was told that this is because the wide ladder line on each leg, plus the thing having 4 such legs gave a broader bandwidth.

The 3KW MFJ-989  VersaTuner V (This is not the -b, -c or other, but the original) tuner was able to match it @10W with careful adjustment but only with the "transceiver" capacitor at one extreme "6" on the scale, which is minimum capacity.

Well as partially expected when the 350-400W carrier QRP setting of COL Tucker was unleashed, the tuner was greatly offended. All settings and parameters the same, but the antenna is now possibly fussier.

The tuner suffered pretty badly. The power meter is dead. There was some noise like arcing and the 1KC modulation test tone could be heard. The tone changed and became louder and the output waveform of the transmitter changed. At this point we decided to just let it go because then we could tell more easily what was damaged because of the burn marks. The 4-1000 started to get red in the face, more like toward orange, as this continued. We made much of this, as in - "listen to that, the arcing's at 1KHz" - and - "switch to two tone - what does that sound like?" - That's the beauty of COL Tucker. If he's in QRP mode, he does not care a whit if every watt just bounces right back.

But that tuner has been blown up before and will probably be blown up again. I didn't let it cook for no reason. Forensically I can see what happened, think about why it happened now and not before, and what should be beefed up. The metering circuit has always been simple to fix - usually a capacitor shorted.

The Murch UT-2000B tuner is better/never arced, except that its meter is calibrated in "relative reverse power" so I'll have to dig it out.

Tomorrow the antenna gets a sweep with the MFJ analyzer. I sincerely wish it could read above 650 Ohms. I'm exhausted.
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« Reply #14 on: November 21, 2017, 09:45:43 PM »

A check of the new antenna over a wide frequency range using a 1:1 current balun and MFJ-259 analyzer showed what the trouble was.

This antenna setup has a low resistance and low reactance. Using the existing 2:1 current balun, the "R" values seen by the tuner was reduced to 1/4 of the values shown, and some are already very low. (Where it says "1", it read "0" on the MFJ). The current must have been very high inside the tuner with the big transmitter on it.

So, these values are still pretty low but will probably be easier on the tuner. The tuner has not been removed and taken apart yet. If there is carnage or melting I'll post pictures. The length also needs to be trimmed a little.

It was possible with a 40W carrier in Dallas to talk with Darrel WA5VGO in Houston area.


* antenna sweep.png (57.02 KB, 1127x719 - viewed 26 times.)
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« Reply #15 on: Yesterday at 11:30:35 AM »

I Love my 75 meter dipole. It is one of the W7FG true ladder dipoles.http://trueladderline.com/ That coupled to my Johnson KW match box works great 10 thru 80. It don't care if it is covered in snow or rain. I have had so much snow and ice on it that  it was laying on the ground. I have my dipole end supported by a large maple tree. With a weighted pulley set up on other end. When I find my antenna on the ground. I just shake the snow and ice off it and it goes back up on it's own.

Happy Thanksgiving John N8QPC
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