[TenTec] OT: THHN Wire in Germany

[Jim Brown]

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