[TowerTalk] Choice of Antenna Wire for Multi-Element 80 Meter Yagi on a Catenary

[Jim Brown]

On 6/27/2020 8:53 AM, Máximo EA1DDO_HK1H wrote:
> For wire antennas best is the wire called "Copperweld" or "DX Wire".
> It is a hard steel core surrounded by thick copper, then insulation.
> It gets the mechanical strength from steel, no stretching, and the copper conductivity.

I really dislike Copperweld. I find it miserable to work with, and any 
kinks can cause it to break. W6GJB hung an 80M dipole using it high in 
redwoods from pulleys he had paid tree climbers >$1k to install. It 
broke a few days later, and he got to pay the climbers again to restring 
the ropes.

My favorite antenna wire for strength is #8 bare copper that I've 
stretched to approximate hard drawn #9. Very strong, doesn't stretch.

On 6/27/2020 8:49 AM, Richard Smith wrote:
 > Are there any concerns about the use of HD copper wire, such as 
tendency for kinks, or other mechanical concerns?

I first did the stretching describe above around 2004 at the suggestion 
of WA6NMF. More recently, W6GJB and I have built a half dozen or so 
antennas with this stretched wire. We've had no failures, and have 
observed no problems unique to it. As with any wire that will see 
vibration and moisture, soldering is a bad idea. I've used nothing but 
copper split-bolt connectors, two per side spaced several inches (the 
second is for mechanical strength). At ends we use egg insulators, with 
the wire making a single loop through the insulator with 6-12 inches 
looped back onto itself and clamped with two U-clamps. As with any 
rigging of wire that will move, connections between the feedline and the 
dipole are made with relatively loose loops that place no stress on the 
connections or the looped wires.

Note that we're rigging for dipoles rigged at 100-130 ft in redwoods, 
fed with RG11, with a 100# weight on one end support rope and the other 
end tied down. The primary stresses in your installation are probably 
wind on the wires themselves.

We use 7/16" rope from Synthetic Textiles, not for its strength, but to 
give our hands something to grab when pulling tension on it. I switched 
to this rope from 5/16-in, which suffered wear where it went through 
badly rigged pulleys. It's also plenty strong enough for our 
installations in tall trees. For your installation, 1/8-in or 3/16-in is 
probably just fine.

There was a German vendor at Visalia last year who was selling what 
looked like extremely rugged antenna rope. If I hadn't just bought 2,000 
ft of the 7/16-in stuff, I would have thought seriously about using it 
instead.

Another thought about your rigging. I suggest that both of your support 
ropes be rigged with weights to reduce stress on the rope and the wires 
in storms.

73, Jim K9YC