Jim correctly said " Rope can wear and even break if it allowed to rub over
a tree branch,
and even in some pulleys. Absent that problem though, yes, it's the weak
spots in the antenna that break."
My experience is that it certainly can. The Synthetic Textile brand is the
worst offender, as its
woven outer sheath doesn't last long.
My cure is two-fold. Thanks to expert advice from Eric Scace, K3NA, I use
halyards with sailing blocks (aka pulleys) which are designed to work under
poor environmental conditions. My favorite brands are Harken (US) and
Ronstan (VK), both available from West Marine and Annapolis Performance
Sailing. There are many variations to chose from, so read the catalogs and
spec sheets carefully. In addition, for the wires that are terminated on
one end (inverted L's) I use snatch blocks made by Holt (UK) and available
from both West Marine and APS. Snatch blocks make replacing or repairing
long wires quite easy.
To reduce the rubbing effect of the rope going over a branch and/or having
the branch grow over the rope if it hasn't been moved in a while, I use
Leather Cambium Friction Savers from Sherrill Tree (who also makes the BIG
Shot slingshot on steroids) . They're a bit tricky to install from the
ground (especially with pine that have a lot of branches from 6 feet on
up!), but well worth the effort, especially if you have climbers installing
them!
Note -- these items are not inexpensive, but you *do* get what you pay for,
I've never had a failure of any sort in the over 15+ years I've used them.
Finally, I disagree with Jim's cokment that by using halyards "you give up
a bit of height." In my case, I can raise the antenna to the height of the
cross (support) branch by raising the halyard as far as it can go -- the
point where the block reaches and is stopped by the the cambium saver.
GL!
73, Eric W3DQ
Washington, DC
-----------------------------
Date: Mon, 26 May 2014 17:06:29 -0700
From: Jim Brown <jim@audiosystemsgroup.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Wire antennas
On 5/26/2014 11:07 AM, K7LXC--- via TowerTalk wrote:
> The other thing you can do for wire antennas (tnx to Jim for all his
> insights) is to use a continuous halyard. That is, the halyard should be
one
> length tied in a loop. Tie an overhand knot in it somewhere and that will
> give you a loop with which to hook one end of the wire antenna.
Thank K2RD for the halyard idea. That's a good way to get a pulley up
high without hiring tree climbers (expensive), but you give up a bit of
height.
> I've found that in almost all cases, it's the wire antenna that breaks
> - not the halyard. Since you've got a continuous and functioning halyard,
> just hook the wire back to it and you're good to go. It's such a PITA to
> replace a halyard with one end at the top of the tree that this should
save
> you some potential future misery.
Rope can wear and even break if it allowed to rub over a tree branch,
and even in some pulleys. Absent that problem though, yes, it's the weak
spots in the antenna that break.
And a big thank you to Steve, K7LXC, who visited me 4-5 years ago and
advised me that Rohn 25 would work for me if I installed it properly and
didn't put too much on it.
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|