> I know I must use some form of balanced open wire feedline
but the question
> is, can 3000' work and if so, what spacing, wire size etc.
should I be
> using? Just HF, and mainly 160 - 40M. I have miles of #6
aluminum wire,
Paul,
I had an open wire line about half that length made from #6
bare solid copper wire spaced 2-3/4 inches or less. Just the
right spacing to make it 450 ohms.
It was only 2-4 percent loss on 4MHz, I forgot exactly how
much loss now but with 100 watts applied it was over 95
watts at the far end I'm sure, including transformer losses.
I made the line "float" through insulators, and tensioned
the far end with a pulley arrangement to multiply the pull
from a counterweight. I floated the line with Teflon sleeves
inside the hole in screw-in ceramic post insulators and laid
over the side notch of ceramic electric fence insulators
that were mounted horizontally.
A few points:
If the wire rubs ceramic it will eventually eat through the
insulator glazing and wire.
You have to transpose the wires at fractional wavelength
intervals to minimize radiation.
You can get away with spacers every five or ten feet if you
tension the wires tightly and equally. I used UV resistant
lexan.
I was initially going to put a 300ft tower in a back
pasture, and run 240V through the leads for tower lighting
and RF.
Hope this is useful. I hope you are sure the hill will help
you on HF, because it's a lot of work installing the
feedline.
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See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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