[TowerTalk] 160/80 dual inverted ell design
jimjarvis at optonline.net
Wed Jul 2 16:15:37 EDT 2008
Not sure where this thread started, but I put one up which worked
quite well, in
an afternoon. First qso was Campbell island on topband, from Vermont.
No trap required.
67' (62.5'?)of 450 ohm ladder line, with 67' of #12 wire attached
Hoisted over a 120' tall tree, such that the feedpoint was 10' in the
3 radials for each band, cut at 105% of quarter wave. All 6
radials were strung
through low branches of a pine forest.
Tuning: Progressively fold back topband radials until vswr center is
where you want it. Then tune 80m to desired frequency.
I neglected to take vf into account when calculating the 80m quarter
wound up trimming down the 80m side of the OWL to about 62-63',
before I could
pull resonance by folding the radials back equally. Looks a bit
funky, but it's easily
Whole process took maybe two hours, including shooting the arrow over
the tree, to get the hoist, and tuning the thing.
Next time, I think I'd go with 63' on the OWL, and 71' on the #12,
but site variables
can easily dominate the tuning of any antenna that close to ground,
and having it
long enough is always a virtue.
Jim Jarvis, President
The Morse Group, LLC
Achieving Results in a Changing World
coach at themorsegroup.biz
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