Hi Jim. Good hearing from you on this as I knew you had some long wires
way up in the air. Funny you should mention pre-stretching as I was just
considering that. I have never done so on purpose however.
In my mind I envisioned if I had a 300' length of say #12 and tried a
pre-stretch that it would break near one of the ends and no where near
the middle. Has that been your experience? I am thinking the middle of a
long run is not as vulnerable to breaking. 73
Gedas, W8BYA
Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 3/10/2019 3:23 PM, Jim Brown wrote:
I have a strong dislike for copperweld -- I find it miserable to work
with, and neighbor W6GJB had a #12 copperweld 80M dipole break a few
days after paying climbers almost $1K to rig it in his tall redwoods.
My wire antennas are at 140 ft between redwoods, and fed with RG11,
rigged with pulleys, tied down at on end and a 90# jug of dry sand on
the other. I used to use THHN, #10 on permanent antennas, #14 for
portable ones, but the #10 THHN stretches over time if under tension,
and must be circumcised every few years.
If insulation is not needed, a far better approach is to buy a spool
of #8 bare copper from the big box store and stretch it to approximate
#9 hard drawn copper. WA6NMF introduced me to this idea around 2004,
and neighbor W6GJB and I have done it several times since. We tie one
end of about 200 ft of wire to an immovable object, like a tree or
telephone pole, the other end to the trailer hitch of his pickup, and
Glen drives very slowly until it breaks, while I observe at a
distance. The stretch is typically 15-20%.
73, Jim K9YC
On 3/10/2019 8:25 AM, Gedas wrote:
I am planning to put up a long inverted v antenna with it's feedpoint
at 85' using 600' total wire (300' on each leg). The ends will be
near the ground, only 20-25 feet high.
My question is given that each leg of this antenna will be 300' long
am I better off going with a lighter weight #14 THHN insulated
stranded wire or some heavier #12 THHN stranded? I am not going to
purchase a different wire that would be better suited like
copper-weld etc since I have plenty of these other two and want to
try something today.
I realize there is going to be a _lot_ of sag in either case but I am
not sure of the breaking strengths of either #12 or #14 and in the
end which will help keep the wire up higher with less sag. Any ideas?
Gedas, W8BYA
Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
ilman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|