[Antennas] Antenna Vibration

Tue, 21 Jan 2003 11:46:31 -0500

george...  good point...  let us not forget the "tacoma narrows bridge"
paul w8jn
----- Original Message -----
From: "George, W5YR" <[email protected]>
To: <[email protected]>; "James E Boyd" <[email protected]>
Sent: Tuesday, January 21, 2003 11:38 AM
Subject: Re: [Antennas] Antenna Vibration


> Jim, it's been about 50+ years since I studied Structures in undergrad
> school, but I would recommend that you take steps to damp that
> vibration before damage results. It could stay like it is for the next
> ten years and do nothing but annoy you, but it could also be slowly
> weakening some part that will fail one of these days.
>
>  When the wind blows, most  towers with beams, etc. will
> intermittently vibrate "a little" as the unbalanced wind forces on the
> beam(s) causes them to exert unbalanced forces and torques on the
> tower itself.
>
> But, a continuous vibration without wind excitation suggests something
> else is going on. You might contact the manufacturer, describe your
> installation in detail and get an second opinion.
>
> As you describe it, there is a pronounced resonance in the structure
> that needs to be uncovered and removed.
>
> 73/72, George
> Amateur Radio W5YR -  the Yellow Rose of Texas
> In the 57th year and it just keeps getting better!
> Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> K2 #489  IC-765 #2349 IC-756 PRO  #2121 IC-756 PRO2 #3235
>
> ----- Original Message -----
> From: "James E Boyd" <[email protected]>
> To: <[email protected]>
> Sent: Monday, January 20, 2003 8:29 PM
> Subject: [Antennas] Antenna Vibration
>
>
> > Dear Group,
> >
> > Has anybody had this problem before??  This year I've really noticed
> my
> > tower vibrating during the wind blowing.  I'm not talking about wind
> > storms.  But just any breeze.  Its getting so bad that you can hear
> it in
> > the house.  I've tried turning the beams to see if that will stop
> it, but
> > only for awhile.  My tower is only 40 feet tall.  I only have 2
> small
> > beams on top of the one thats next to the house.  But I'm wondering
> if
> > the vibration could even go down into the concrete and crake it?
> When
> > you put your hand on the tower, this puppy is really dancing to a
> tune.
> > So the question being, can anything be done to slow the tone down.
> I
> > don't know what musical note my tower is playing, but it must be
> around
> > low "C".  Any help will be really appreciated.
> >
> > 73
> > Jim
> > kb9vtm
> >
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