[Elecraft] FW: Question about suspending a delta loop...
Ron D'Eau Claire
ron at cobi.biz
Sun Sep 16 17:06:06 EDT 2012
I don't have a big loop, but I have not had any trouble with using a
counterweight on my inverted L with one end supported at about the 40 foot
level in a 60 tree. I use a compound pulley arrangement that halves the
distance the counterweight must travel. About 30 lbs of counterweight
supports my 100 foot antenna with about 15 lbs tension on the antenna wire.
It has survived winds in the 60 to 100 mph range on dozens of occasions
since I put it up in 2007. On one occasion the winds were strong enough to
cause the counterweight to move about 10 feet, meaning the tree trunk was
moving 20 feet about 2/3 of the way to the top.
While "shock loading" resulting from sudden movement is a concern, my
reasoning is that the wind must set many tons of tree in motion to start
moving the counterweight, so the tree is a very robust "shock absorber" that
prevents very sudden movements. The 5/16" Dacrom ropes I use have also
survived nicely for 5 years without issue.
As others have noted, the challenge when using a counterweight system is to
keep the antenna from "walking" the counterweights to one limit. I opted to
avoid hanging both ends of my inverted L in trees for just that reason.
73, Ron AC7AC
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