[Boatanchors] Open feed line insight needed

[mikea]

On Wed, Feb 01, 2006 at 09:35:13AM -0800, J.D. Mac Aulay, WQ8U wrote:
> My "plain text only" challenged friend need help from
> the group with replacing an open feedline.  
> Thanks & 73
> Mac
> WQ8U
> --------------- 
> Y'all,
>  
> I need some advice on the best type of open wire
> feedline to acquire.  I have an open span of about 200
> feet from my "tower" to the peak of my roof, and the
> feedline will have to withstand some pretty gusty
> winds here in New Mexico.  I'd appreciate any
> recommendations for feedline that would best hold up
> under these conditions.  
>  
> Thanks,
>  
> Jim Hanlon, W8KGI

It depends a bunch on the impedance you want the feedline to have, Jim. 
Open wire comes in various impedances, and you get to choose the one you 
want. I might well go for the 90-ohm open line that's a bit wider-spaced
than 300-ohm, and has "windows" between the two conductors, rather than 
the solid center of 300-ohm line. But really it depends on your antenna 
feedpoint impedance and your matching network in the shack.

I think that if I had a 200-foot run, then whatever type open line I was 
using, I'd want to have some supports every 30 feet or so -- just a post
with a crossbar at or near the top, and a couple of insulators to secure 
the feedline to. 

I live in central Oklahoma, and we get to see a lot of New Mexico and 
Texas when the wind's right. Winds here get up to 60 mph in storms, 
and I've had 95 mph downbursts send my board fence panels all over the
place, so I understand very well what you're dealing with.

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin