[TowerTalk] Copper Wire

[Bill Coleman]

On Aug 25, 2005, at 9:32 PM, ersmar at comcast.net wrote:

> You might have heard/read that thick shunt wires provide better  
> match/greater bandwidth/increased stamina, etc.  Just hang two or  
> more of the thinner wires off some kind of insulating support (PVC  
> or wood come to mind) off the tower and tie the top and bottom ends  
> together to form a shunt wire with a larger effective diameter.

You don't need an insulator for this.

I have a 44 foot tower, and I used a 3 foot piece of 1" angle  
aluminum with a couple of U-bolts around the tower legs. This places  
the end a good foot and a half off the tower. A 1 foot piece of 3/4"  
angle aluminum spreads the two wires. There's no insulation at the  
top. At the bottom, I have a 5" NEMA box. The wires join to another  
piece of 3/4" angle aluminum, which are held with a single #10  
stainless bolt through the NEMA box. The box contains the matching  
networks for 80m and 160m.

The wires hang free, side by side over about 42 feet. Works well. I  
tried the shunt originally with one wire just six inches off the  
tower - very much harder to match.

>      OOT (one other thing):  Keep your shunt wire(s) an appreciable  
> distance away from the tower face.  My wires (I use two in  
> parallel) are two feet off the Trylon tower face; I've seen others  
> as much as five feet away.  I'm sure modeling will tell you why  
> this is preferred; I just followed others' examples.

I think the big reason is that it is easier to match a skeletal  
ribbon a couple of feet off the tower.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901