[TenTec] Window line

[Rob Atkinson, K5UJ]

that's real interesting data on window line.    I never fooled around with 
it because i had heard of the problems, like wind resistance, one or both 
sides snapping due to metal fatique, and the Z changing when it rains.   I 
went with ladder line and bought mine from W7FG.   no doubt i could have 
homebrewed it and come up with a higher impedence and better conductors but 
i was lazy and in a hurry (typical 21st century).   i ordered 200 ft. of the 
stuff and when i pulled it out of the box my first thought was, No way is 
this gg to work.   but I looped one end on a fence, untangled it and 
stretched it out and adjusted the spacers and it was fine.    you have to 
have a way to support it across the ground that doesn't upset the balance 
(no metal).  I used PVC poles and they have worked fine for the past 2 years 
or so.   if you go to www.w7fg.com you can find out more about his product.  
also, if you go to www.cebik.com there is a table on one of his pages that 
gives characteristic Z for different gauge of wire and distances apart and 
there is other information about it.

speaking of surprising losses, i was using TLW earlier this year to work on 
making a L network for matching an ant. feedpoint to a line and in the 
process happened to discover that good old RG213 has a surprisingly high 
loss, even on 160 m., even when both ends are 50 ohms.  If you use it for a 
run of 200 or more feet, you start getting into what were for me, 
unacceptably high % of power lost in the line.   i may have done something 
wrong with the software, but i remember finding that if the run was 300', 
and i put 1 kw into the  line, at the feedpoint end, I'd be delivering 
around 700 or 800 watts to the ant.  i know a lot of you will say no one 
will notice that loss, but if i am gg to tx 1 kw, i'd like to get closer to 
that much to the feedpoint so  the ant. can loose it in the ground, hi.   
Something to think about for anyone with large low band coax chokes made 
with this stuff.   I used to wonder why broadcasters running only 250, 500 
w. or 1 kw used such robust feedline like 2 inch heliax.   Now I know.  
They'd rather pay a lot one time for feedline, but have a lower light bill 
in order to achieve their required field strength.

rob/k5uj

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