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Author Topic: Bent 6M Element  (Read 781 times)
WB4LCN
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« on: May 06, 2012, 08:47:56 AM »

I finally finished refurbishing an old tower. I hired a tower expert to mount the antennas, yet while he was mounting my 5 element 6M log periodic, he bent one of the elements. At the time, I didn't notice what had happened. When he bent the element, he attempted to straighten it, but he was afraid to bend it back as it should be. As a result the element is still bent significantly. I only noticed it after he had mounted the rotatable dipole below and was climbing down.

The ground crew was a friend of mine and myself. We hoisted the antenna correctly as he requested. However, I did notice that the antenna was backward from the way it was needed to go easily on the mast. I suggested that the antenna be lowered and reconfigured, but the tower guy said since the antenna was small, he could flip it and from where he was on the tower. He did and that was apparently the moment when the element was bent. Again, myself and my friend on the ground did not notice that had happened.

After the tower guy climbed down, I expressed to him that I was concerned that the antenna might not radiate as it supposed to questioned him about how the SWR would be effected. He assured me that neither of those concerns were anything to worry about and the antenna was OK to use.

Am I correct for being concerned, or is that just one of those things that happens? Will the antenna now be compromised?

Thanks for you feedback.

dave Smiley
« Last Edit: May 06, 2012, 10:22:06 AM by WB4LCN » Logged

First, make it work, then make it pretty.
Yaesu Rigs: Kenwood TS-480HX, FT-8900R, FTM-350AR (Bluetooth motorcycle mobile), VX-8DR, SB-102 boat anchor (built one as a kid)

Moderate Spock: "Live for a reasonable amount of time and scrape by."
WB6BYU
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« Reply #1 on: May 06, 2012, 09:20:32 AM »

How bent is it?   Enough that it touches an adjacent element?

More important, how well does the antenna work when you try it out?

Many antennas can tolerate a fair amount of bending and still work well enough - certainly
visual aesthetics are much more critical than RF performance.

Tune in a 6m beacon and rotate the antenna to check the pattern.  If it looks good, then
the antenna should work as expected.  It's only worth changing if something like the SWR
or pattern is obviously wrong.
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WB4LCN
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« Reply #2 on: May 06, 2012, 09:55:49 AM »

How bent is it?   Enough that it touches an adjacent element?

Well, the element is bent at the boom and the tip of the bent element is about half the distance to the element in front of it. From the ground, it definitely doesn't have a good look. lol

dave Smiley
Logged

First, make it work, then make it pretty.
Yaesu Rigs: Kenwood TS-480HX, FT-8900R, FTM-350AR (Bluetooth motorcycle mobile), VX-8DR, SB-102 boat anchor (built one as a kid)

Moderate Spock: "Live for a reasonable amount of time and scrape by."
WB2WIK
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Posts: 20611




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« Reply #3 on: May 07, 2012, 08:06:31 AM »

Difficult to predict the impact of that electrically, but if the element is that bent it's likely also weaker at the bend point and more likely to fail right there.

I did antenna installations (for pay) for years and years and if something like that happened ("stuff" happens) the cost to fix it and re-install it would be on me.  I couldn't possibly charge a customer for that.
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W0FM
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« Reply #4 on: May 07, 2012, 11:15:42 AM »

What Steve said!  Plus:

Did you pay this "tower expert"?  Was there some disclaimer that any damage would not be covered by him because he let you and your friend be the "ground crew" rather than his own guys to save costs?  If you hired him, he should have taken the antenna down, fixed it properly and put it back up.

73,

Terry, WØFM
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