[TowerTalk] Antenna element vibration damping - How

[Bill]

I have noticed that most everyone uses rope in the elements to dampen
element vibration, but it is not a cureall. I have used this idea as well,
but have had mixed results. Both my 5 element Hygains (15 and 10) had
serious element vibration, even with the rope. The tips of the elements
would vibrate off within a few months. Never had the problem with my old
TH6DXX.

This isn't just a Hygain problem though, my 6 element KLM 10 meter
monobander had the same problem. My 6 element 15 was just fine. I have had
two Force 12 antennas and have not had a problem even without the rope
trick.

I can still remember the broken element ends on the 5 element Hygain with
the rope hanging out.

Bill, W5VX

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of David Robbins
K1TTT
Sent: Friday, August 08, 2003 1:49 PM
To: va3pl at cuic.ca; towertalk at contesting.com
Subject: RE: [TowerTalk] Antenna element vibration damping - How


Contrary to what others have said... get the heaviest, thickest rope you
can slide into the element and still have room for it to flop around.  I
like a tight nylon braid or old hemp/sisal because its heavy, I would
guess you could also use a flexible wire rope also but have never seen
it done.  The dampening action is achieved by the rope moving around
inside the element to absorb the vibration energy.  A rope about 1/2 of
the ID of the tubing is generally good.  One other thing interesting
about it is that it is generally most important to have rope in the
middle of each side of the element... that is, generally the vibration
is worst about 1/2 way out from the center to the tip of the elements.
So if you have a choice (like the element is made of 3 pieces on each
side) put rope in the middle section and maybe the outer one, rope near
the boom end does much less for vibration.

Depending on the element construction you can hold it in the element
with either the end cap or the bolts that go through the element to
either hold it to the boom or to hold sections of it together.


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: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of VeeAthreePL
> Sent: Friday, August 08, 2003 17:41
> To: towertalk at contesting.com
> Subject: [TowerTalk] Antenna element vibration damping - How
>
> I have had read somewhere on this reflector that in order to damp
element
> vibration in the wind you have to insert rope inside the elements.
> I am just about to install my Mosley TA36 with 40M kit and would like
to
> install such a modification. How it is done exactly?
> Thanks
> 73 de Andy - VA3PL
>
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers",
"Wireless
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041
with
> any questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk


_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.

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