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Re: [TowerTalk] Weight on ends of a OCF diploe

To: "'Roger \(K8RI\) on TT'" <K8RI-on-TowerTalk@tm.net>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] Weight on ends of a OCF diploe
From: "Wes Attaway \(N5WA\)" <wesattaway@bellsouth.net>
Date: Thu, 11 Aug 2016 22:34:57 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I feel compelled to offer an alternative view.

Jim Brown correctly pointed out that the question of pulleys and a
counterweight depends on how tall your trees are, how high your antennas are
in those trees, and how much the trees wiggle.

In my case I have Pines that are over 100' tall.  I put my OCF antennas at
the 60-70-ft level.  The wiggling is minimal at that height, although the
trees do move.  I leave a little slack in the antenna and I do not (and have
never) used counter weights.  I use 3/16" or 3/8" black Dacron line over the
tree limbs.

My method of attachment is that I get a line over an appropriate limb on the
center tree and I use it to haul up a pulley that has a black line in it.  I
hoist the antenna center with that line.  (There are two lines in the center
....one to hold the pulley up and one to haul the antenna center up).  I do
not use pulleys on the ends.  I just shoot a line over a limb and pull a
black line up through and over to the end insulator (on each end).   

I know all the stories about abrasion and all the other stuff but not one
antenna has ever broken in the 15+ years that I have been at this QTH (and
we have had some hurricanes come through) except once when a big limb broke
off of a tree and crashed through the antenna wire.

I am sure counterweights are appropriate for some situations but I don't
think you should just assume you need them.

   -------------------
Wes Attaway (N5WA)
(318) 393-3289 - Shreveport, LA
Computer/Cellphone Forensics
AttawayForensics.com
   -------------------
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Roger
(K8RI) on TT
Sent: Thursday, August 11, 2016 9:36 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Weight on ends of a OCF diploe

In a typical installation for an OCF antenna, I'd think a concrete block 
in a bucket should be more than adequate. Be careful not to exceed the 
ratings of the antenna or tower.   I agree with David on just using the 
weight at the tree, but here (central Lower Michigan), I'd use a lot 
more weight because of common spring ice storms

In my case I have a similar arrangement, but it's a center fed, sloping, 
half wave dipole with one end to the tower and the lower end to a 
"substantial" tree.  I use a relatively strong braided Dacron rope 
(available from Davis RF and other sources). I depend on the elasticity 
of the rope, but it's under "roughly" 200# of tension. To eliminate 
center sag from the coax and choke weight. At this tension there is only 
a slight visible sag, sighting along the length of the antenna from the 
lower end.  With SW antenna the rope runs through a half inch hose 
around the back side of the tree.  The hose is to protect the tree,  The 
NE antenna ties off to a forged lag bolt with an eye, in a very large 
tree.  At this size there is little danger of the mature tree growing 
around the lag bolt.  A younger tree might require moving the bolt every 
few years.

I use as much tension as desired within the strength capabilities of the 
antenna and supports.
As a personal preference I'd use at least 100#, with the tower back 
guyed ( if necessary)  With my 45G, the antennas serve as tension 
against each other.  OTOH.  My 100' tower's guying is strong enough that 
back guying would not be needed even at 200# tension in just one direction.

73

Roger (K8RI)

On 8/11/2016 Thursday 12:20 PM, David Robbins wrote:
> Enough weight to keep it reasonably tight.  Normally only one end needs to
> be able to move, I would do that on the tree end instead of the tower.
> typical weights I have seen are buckets filled with concrete or rocks or
> sand, 20-30 pounds at most... if it is very long then maybe more weight.
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
>
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Chuck
> Gooden
> Sent: Thursday, August 11, 2016 16:14
> To: towertalk@contesting.com
> Subject: [TowerTalk] Weight on ends of a OCF diploe
>
>
>
> Retired recently and am getting back into ham radion.
>
> I am planning on putting up a 80 to 10 meter OCF antenna.  The antenna
will
> be supported on a TV tower with the ends attached to some pine trees.  I
am
> planning on using a pulley and some weight on the ends to allow for wind
> effects on the pine trees.
>
> My question is how much weight will I need at the ends to allow for wind
> movement of the trees?
>
> Thanks,
>
>
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-- 

73

Roger (K8RI)


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