right on Gene, scrap their idea of a coil, and consider using a top wire, as
high as it can be, to load the thing. .
You'll lose the multi band performance that way though, unless you fix it so
that you can detach the topwire and stow it along the length of the tower
when using this ingenious antenna on the other bands. Feed it inverted "L"
style, and use a 500-800 pF series cap (transmit rated). Use a BCB variable
to find the value needed (do not TX, only MFJ analyzer). Then measure value
and
replace with a doorknob sandwich. A tapped shunt inductor can be used also.
Here are some ideas on how to make your own:
http://homepages.dstream.net/K0FF/HomebrewTips/LoadingCoil
see: http://homepages.dstream.net/K0FF/5-8Fourty for mechanical ideas.
Second option is a linear loading tube, which is a trombone of aluminum
tubing (maybe 20 feet tall and 1 foot wide) instead of a "coil". Not quite
as good, but can be easily detached from ground level when using the
antenna on the other bands. Easily made from 1", 3/4" and 1/2" aluminum
conduit. Slide a short along parallel tubes to find resonance. The 51 foot
height (only) of the HyTower makes it a poor candidate for this approach
though.
4 Radials under it will work OK, and even tho "more is better", unless you
can go to a LOT more, basically don't waste your time. Also, the fewer you
have, the shorter they can be. Seems backwards.18HT has a neat design
concept, except on 160, you just can't fool Mother Nature.
Geo>K0FF
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