[TowerTalk] Weight on ends of a OCF diploe

[Grant Saviers]

My experience is that the tree grows around the rope over the limb 
(pines, firs, cedars, not redwoods) and thus becomes immovable.  So I 
put a good $14 marine/ss pulley on the top end so it becomes a fixed 
support.  If the rope moves back and forth before it is grown around 
then it frays and breaks, but there is little motion with a fixed rope.  
The force needed to pull up antennas is also significantly reduced, 
particularly if I spring for ball bearing pulleys.

Then the antenna hoist line thru the fixed pulley is a full loop so if 
the antenna breaks I can't lose the antenna end.  Or a 1/8" messenger 
line on the end of a not looped (or looped) hoist line which can be 
handy for tugging antenna wire thru/around branches.  A full loop can 
get surprisingly long since the antenna attach point can be a ways from 
the tree base when the antenna is on the ground. Good pulleys are cost 
effective vs line cost.

With very low wear, the 3/16 or 1/4 dacron line lasts, I'm reusing it 
from 1986. Now and then some goes into a mesh bag in the washer and they 
clean up nicely.  I've done this with all sorts of gunked up lines since 
my sailing days, but use a front loader which can't wrap them in an 
agitator top loader mechanism (don't ask).  But better not get caught by 
the YL, and run a dummy load afterwards to clean the washer.

Bigger is better for pulley diameters but then they get very pricey if 
marine quality.  8 to 10x rope diameter vs pulley (called a sheave) 
diameter is the rule of thumb for modern fiber line running brigging on 
a sailboat.  16:1 for wire rope to get 90% of break strength.

The "bungee in pvc pipe" is a great idea for tensioning, no big mass on 
a spring effect with a bucket of rocks.

Grant KZ1W

On 8/11/2016 23:37 PM, Jim Brown wrote:
> On Thu,8/11/2016 10:02 PM, Roger (K8RI) on TT wrote:
>> 5/16ths is over 1700# strength, but a bit more expensive. 
>
> FWIW, I use the 5/16-in rope because it's easier to grab hold of to 
> pull tension on my very high dipoles. 3/16-in (and even 1/8-in) is 
> plenty strong enough for most antennas that aren't very high.
>
> Wes, N7WS, described a system similar to one I rigged here soon after 
> I moved here, with help from Ira, K2RD, and others. I replaced it with 
> the system of pulleys that I now use because it allowed me to get the 
> antennas higher, and it also allowed me to rig a 20/15/10 fan in line 
> with the 80/40 fan that had loading coils for 160.
>
> The system that Ira showed me how to rig had a continuous loop of 
> 5/16-in that he launched over a limb with his pneumatic tennis ball 
> launcher (he cleared the tallest redwood on my property  -- about 175 
> ft -- by at least 10 ft on the first shot). To that loop he attached a 
> pulley, then pulled the support wire through the pulley, then pulled 
> the pulley it all the way to the top.
>
> That system survived at least one winter without a weight, because 
> there was enough "give" in the way the pulley was rigged to allow for 
> sway, but I'm not confident that the loop rope would have survived 
> over that limb for 10 years. :)  Wes's experience suggests otherwise.
>
> 73, Jim K9YC
>
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