Re: [TowerTalk] Need install a BRAKE to protect antenna and rotator

["Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>]

Pinning the mast to the rotator is not usually recommended as it's a 
good way to destroy a small rotator.  Small rotators depend on the mast 
slipping to protect the rotator.  Pin the mast only if the rotator is 
capable of handling the torque.  You can pin it if you have a good break 
installed.
With an antenna that size, you need either a heavier duty rotator, or an 
external brake as has been discussed.  I'm assuming the bigger rotator 
is not an option, so I'd opt for one of the many schemes for installing 
a break.
There is nothing wrong with using a light duty (TV) rotator, if the mast 
can be held by the external break and only rotated with no more than 
light winds.
As I mentioned in an earlier post, I've had several rotators torn up 
because I tried to turn a large array on a windy day.  The fault was 
mine, not the rotators.
I also lost 5 28 ft long LMR-400UF pigtails. Replacing the pigtails 
required lowering the mast to the point where I could reach the top 
connections and that was not an easy task.
I'll spare the details, but this is the array which many have seen 
before.  http://www.rogerhalstead.com/ham_files/Tower29.htm  None of the 
antennas, or mast are pinned.
Yes, that is me up there about 15 years younger and 20 pounds lighter<:-)

I can no longer climb, so I have to hire any tower work.

I should have worked a few more years before retiring.<sigh>

73 and good Luck!

Roger (K8RI)



On 4/4/2016 Monday 10:19 PM, Douglas Ruz / CO8DM wrote:
> Yes, you are right...The U bolt failure caused the slippage.
>
> It is an small TV antenna rotator. Yes the antenna is balanced. The antennas
> is big spiderbeam...a big cross 46 ft by 46 ft.
>
> Pin the mast to the rotator is a good idea but I am worry about the U bolt
> that join the Center hub with the mast...if that U bolt fail then will get
> problem with the coax again.
>
> I will try installing a telescopic tube in the tower leg...with a pulley can
> move up or down the tube if I want rotate the antenna...that tube is a
> protection if the U bolts fail...If the U bolts fail, the tube will stop the
> rotation of the center hub.
>
> 73,
>
> Doug, CO8DM
>
> -----Mensaje original-----
> De: TowerTalk [mailto:towertalk-bounces@contesting.com] En nombre de Earl
> Morse
> Enviado el: lunes, 04 de abril de 2016 16:18
> Para: towertalk@contesting.com
> Asunto: Re: [TowerTalk] Need install a BRAKE to protect antenna and rotator
>
>
> Thought maybe you had a rotator with no brake installed but then saw that it
> was a U-Bolt failure that caused the slippage.
>
> You can pin the mast to the rotator if slippage is a problem but you should
> have a rotator with a brake so that the rotator doesn't slip.
>
> What kind of rotator?  Is the antenna balanced about the mast?
>
> Earl
> N8SS
>
> ------------------------------
>
> Message: 2
> Date: Sat, 2 Apr 2016 20:49:33 -0700
> From: "John V" <vjohnv@cox.net>
> To: <towertalk@contesting.com>
> Subject: [TowerTalk] Fwd: Need install a BRAKE to protect antenna and
>         rotator...
> Message-ID: <009501d18d5b$d5ceb850$816c28f0$@net>
> Content-Type: text/plain;       charset="iso-8859-1"
>
> "Hi,
>
>   
>
> I installed a modify spiderbeam few days ago. Spreaders are 7m long because
> I added 2 elem (shortened) on 40m.
>
>   
>
> Few days ago, during a windy day, both U bolts with saddle clamps in the
> rotator fail...the antenna mast (aluminum tube) rotate inside the saddle and
> broke both coax cables.
>
>   
>
> I quickly tie a pipe between the center hub and one leg of to tower until I
> find a solution.
>
>   
>
> Maybe I need a Brake mechanism to protect the rotator. Some kind of
> mechanism to operate with a rope from the bottom of tower.
>
>   
>
> It is very interesting...the center hub is connected with an U bolt with
> saddle clamp to the alum mast...I think strong winds will turn the center
> hub, so, I need protect the center hub too.
>
>   
>
> Any idea ?
>
>   
>
> Thanks,
>
>   
>
> Doug, CO8DM"
>
>   
>
> Doug,"
>
>   
>
>   
>
>   
>
>   
>
> Doug, great that you are getting up some good antennas!
>
>   
>
>   
>
>   
>
> One option would be to use some brake parts from a smaller car. You would
> need to find a brake drum setup and attach the backing plate to the tower
> and the drum to the mast. The brake pads could be actuated with a master
> cylinder near the ground. If you used a rear brake drum there is a chance
> that it could have an emergency brake cable that you could extend to the
> ground and not need any hydraulics.
>
>   
>
>   
>
> Una opci?n ser?a utilizar algunas partes de freno de un coche m?s peque?o.
> Necesita encontrar una configuraci?n de tambor de freno y coloque la placa
> de soporte a la torre y el tambor en el m?stil. Las pastillas del freno
> podr?a accionarse con un cilindro maestro cerca de la tierra. Si usted
> utiliza un tambor de freno trasero hay una posibilidad de que podr?a tener
> un cable de freno de emergencia que podr?a extender en el suelo y no es
> necesario ning?n sistema hidr?ulico.
>
>   
>
> Regards, John NA6L
>
>   
>
>
> ------------------------------
>
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--

73

Roger (K8RI)


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