[TowerTalk] Re:TowerTalk Twin lead feedline

[w8ji.tom]

Hi Press,
----------
> From: n8ug@juno.com
> To: towertalk@contesting.com
> Subject: [TowerTalk] Re:TowerTalk Twin lead feedline
> Date: Friday, July 10, 1998 5:19 PM

> The  few designers and builders who required critical value had only to
> alter length to suit, and a purist could still "roll his own"
> Keeping the cost down has made the resurge of balanced line use a real
> exciting phenomenon, and the growth still escalates. Problems due to the
> big stretch of the "nominal" expression on the 14 gauge model have been
> rare. 

I wouldn't apologize for making the line better!

1.) Larger conductors generally have less loss for a given spacing and
dielectric.

2.) Lower impedance generally means less weather effects for a given
spacing 

3.) Lower impedance line often means less impedance extremes at the far end
in many applications.

4.) Larger conductors mean more power handling.

5.) Larger conductors mean less breakage.

This type of line is very poor at VHF, at least the samples I've measured.
I'm sure you've seen the effects of periodically repeating "bumps" on VHF
or UHF performance.

IMO, the problem is misapplication of what amounts to a good line for HF
(except for weather and routing problems) to VHF "matched" applications.
Dean Straw seems to feel the new ARRL Chart is correct, and the old one
wasn't that far off. My measurements disagree with that. 

When we sort that out off-line, I'll post a correction or clarification.

Have you ever measured VHF performance Press, and do you recommend this
line over hardline? Since you sell the stuff, you see more than Dean or I
do.

73 Tom

--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm