On 4/24/2013 10:05 AM, Joel Hallas wrote:
FWIW, my experience indicates that solid wire is more likely to break from
metal fatigue than stranded. Stranded also seems less likely to kink during
installation -- death to wire under stress.
Yes and no. In my experience, with antennas under considerable stress
(see previous post in this thread), the key is to make every single
termination (end insulators, center insulators) in such a manner that
the movement at any point is minimized. I've had failures of both solid
and stranded copper of comparable size, and the cause was HOW I rigged
those connections, not the choice of stranded or solid.
As an example, I loop the ends of a dipole through egg insulators, and
secure the ends in place by placing multiple clamps on the wire where it
has doubled back on itself. I use either split-bolt connectors or
U-clamps for this. I do something similar at the center insulator,
bringing the wire through either another egg insulator and down to the
feedline connector, or through a thimble to the mechanical element of
the center insulator, and then loop it down to make the electrical
connection. Whatever the method, I try to rig that loop to minimize any
movement when the antenna or feedline move in the wind.
Another important point -- solder degrades the mechanical strength of a
joint, and will often CAUSE failure. I've learned that split-bolt
connectors are a far better way to make both mechanical and electrical
connections, and I often use several of them at the feedpoint -- at
least two for the mechanical connection, and usually two for the
electrical connection.
In my experience, both copperweld and Flexweave are LOUSY for antennas
because their mechanical properties are poor. They may be OK for low,
short antennas with little stress, but they do NOT hold up with flexing
nor with pulling stress. I bought several spools of Flexweave and built
some antennas with it. All were on the ground within a year or two. My
ham friends in Chicago have had similar experiences under much less
stressful conditions. My neighbor, W6GJB, a very smart aeronautical
engineer who works in the space program, built an 80/40 fan dipole
using stranded copperweld and very good construction techniques (I
helped him do it). It lasted two days when we strung it between a couple
of his redwoods. We rebuilt it using the hard drawn copper I described
in an earlier post.
73, Jim K9YC
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