[Antennas] Vibrating hollow elements

Wed Sep 21 07:34:05 EDT 2005

An old trick I have used with fairly good success for many years, is to 
 fill tubing elements to about 3/4 full with sand and cork the ends. 
The sand serves as an excellent "damper". Do not completely fill the 
tubing space. The sand needs a little room to move slightly in order to 
more effectively absorb the vibrations.
73,
Ray, W4BYG
Naples, FL
David Robbins wrote:
> The cc 4 element 10m has the same problem. It is probably related to how
> easily the relatively short and stiff elements vibrate. Telrex antennas
> (the later models with the lighter and stiffer elements) also had this
> problem. 2m antennas probably don't see it because they often have solid
> rod elements, and even if done in tubing they would probably not vibrate
> much because they would be so short that there wouldn't be much surface area
> to set up the vortices that excite the vibration. The 'fix' is to
> mechanically detune the elements and provide a way to dissipate the
> vibrational energy by adding a floppy heavy weight inside the elements. In
> larger elements a heavy rope works well, in the small tubing of the 6m
> elements I am trying pieces of aircraft cable. It seems to be working, at
> least I am not noticing the vibration as often as I did in the past here.
>> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>>>>>-----Original Message-----
>>From: antennas-bounces at mailman.qth.net [mailto:antennas-
>>bounces at mailman.qth.net] On Behalf Of W0DXZ at aol.com
>>Sent: Wednesday, September 21, 2005 00:30
>>To: antennas at mailman.qth.net
>>Subject: [Antennas] Vibrating hollow elements
>>>>OK I agree, that the Cushcraft maybe a cheaply made, though well
>>performing,
>> antenna. Now that mine has fallen apart (second one to do this) I may
>>replace it with another brand, unless CCraft comes up with a free
>>replacement.
>>Fat chance.
>>So,,, quality antennas, well made, solid elements... anyone make a solid
>>element antenna? I couldnt find any.
>>What is the best quality antenna, in the 6 meter 5-6 element range? Does
>>anyone make one that wont vibrate apart? I never had this with a 2M or
>>10M
>>antenna, why 6M?And why the CCraft, just cause there are so many of them?
>>I never
>>had this problem with my 3 ele CCraft 6M beam.
>>Suggestions?
>>>>Bob W0DXZ
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