[450] the wound! (i mean wind)

[George Andrews]

Dave,

Give thought to what happened. I know 42 inches probably probably means a lot to you and I can understand that. You have determined the weak point in the system. If your mast was steel, continued flexing softens the metal at the flex point. Aluminum becomes brittle with flexing (work hardens). If you leave it where it is, you may not have to worry about wind. Model the antennae to see what the decreased gain is. Maybe you don't want to go back to the full 42 inch difference. There is a gain to be achieved in never having to worry about wind and ice load and wind. My antennae are not as high as they could be, but ice and windload or wind have never been a worry. My three element 6 M beam is set up with a very crude slipping clutch so that all the mast and rotor rotate if the wind really gets a hold of it. This way a component of the energy that might bend the mast or damage the antenna gets translated to a rotational component. I have to rezero rotor every so often, but that is trivial. Over the years, I have heard some strange creaking and groaning, but have not lost an antenna or had damage since I have been licensed. On the flip side, my stuff is not as effective as if I pushed the envelope. But physics and gravity will always win!

George
N1YAE
  ----- Original Message ----- 
  From: David McKenzie 
  To: 144.450 Mailing List 
  Sent: Wednesday, November 24, 2010 12:23 PM
  Subject: [450] the wound! (i mean wind)


  The mast on the HF tower bent just above the thrust bearing in last night's wind. I dropped it down and cut the mast just above the bend. The HF beam and loops are now 42 inches lower until I can replace it.

  The bend was very slight but was more than enough to bring the top about 30 degrees off vertical.

  No other damage here.



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