Been long-time lurker here (previously as N0OCT), but can certainly speak
to the balloon supported vertical.
FD '93 we did one with our club, and as I was young, energetic and a
chemist, I was charged with getting this thing going. Ok, it was my idea,
too. Full-sized 1/4 wave vertical for 80m complete with 4 radials angled
down at 45 degrees.
We sourced a military surplus weather balloon (latex) from the local
mil-surplus store. I acquired a full-sized cylinder of helium (about $60
in those days). It played very well, as it was a mostly still night that
night.
Some pro tips:
- find a person who is experienced in handling gases (I am), and consider
hydrogen. Both cheaper and greater lifting power. We were all set to use
hydrogen until some old guy yelled "Hindenburg!" at one of the meetings.
It can be done safely by someone trained in it. Oh well.
- Make sure you transport and move your gas cylinder with the protective
valve cap in place at all times. Also, make sure you can secure it safely
where you plan to use it.
- Consider how you might bring this thing down if it gets tangled in a
tree. Ours did, and no pulling on the driven element would unlodge it.
Someone went home and got a pellet gun. It took about 367 shots before it
had enough holes to actually deflate.
- Consider how you will secure the balloon to the driven element. Someone
had used duct tape around the latex "stem" exiting the balloon to secure it
while we hooked the wire up to it. When the duct tape was removed, it
created tiny holes, and while up in the air, the balloon parted ways with
our antenna. This occurred *below* the check valve in the stem. Imagine
the entire FD crew watching their support balloon rocket straight up into
the sky. Imagine the consternation over what the FAA might do to us, or if
it got sucked into a jet engine intake and caused loss of life. Imagine
the FD crew going back to the mil-surplus place and getting another one. .
..
As I said, ultimately it worked, and worked well. I'd never do it again,
but I'd gladly watch.
73, Jim KK0U
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