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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>
> _______________________________________________
>
>
>
> _______________________________________________
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--
73
Roger (K8RI)
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