"Larry" wrote in message
...
SHHHH!@ Don't be givin' away my Field Day secrets!....

Have you ever seen one of those blimp-shaped balloons with a car dealer
ad on the side of it over the dealership way up high...even in the wind?
Looks just like a little Goodyear blimp on a 3-point tether to a line to
the ground. Well, I wondered how one of those would do for a 160M and
75M vertical, 1/4 wave or half wave (end fed with a tuner..no ground
needed). So, When the dealer took the balloon down, I figured he'd store
it for another promo at some future time. I asked him if I could borrow
it the day after I noticed it was missing from his Chevy lot. "It's out
in the dumpster and you can have it if the dumpster hasn't been dumped,
yet." I rushed out back and did a little "dumpster diving" retrieving
this invaluable piece of aircraft, its tether, and enough line to fly it
at 2400 AGL! As the rented Helium tank had gone back to the ad company
it all came from, I stopped by WalMart and bought a disposable helium
balloon tank, actually 2 of them but I didn't need two.

I replaced the "downhaul" line with some 1/16" braided dipole cable that
I have on an old military portable dipole made for Army field HF
stations. The "hot side" (there's no balun) was flown up vertically by
the balloon. The shield side was laid out on the ground, 1/4 wavelength
on 3900 Khz.

We strung out the wire as the balloon lifted it all 64' up and clamped it
off on the portable dipole's contact, the center of the portable dipole
now tied to a big tent stake driven into the ground. No tuner was
necessary as the feedpoint impedance was measured to be around 38 ohms
with just one radial, not buried. Signal reports were amazing! The
full-length 1/4 wave vertical performed like a broadcast tower.
Bandwidth of such a thin wire was about 40Khz to the 1.5:1 SWR points but

as the dipole reels were laying in the lawn, adjusting them to a
different part of the band to get the SWR flat was real easy.

This blimp-like balloon is MADE to fly in the wind. The 3-point hitch
insures the balloon doesn't "tilt" as the wind pushes at it. When it
tilts with wind pressure, the airfoil of it lifts harder and the 4
tailfins point it to windward, providing lift to keep it on top of its
arc, not blown down to the ground. Works great!

On 160 meters, tuned around 1.870 Mhz, bandwidth is about 25 Khz with
120' or so of wire aloft. The blimp has no trouble maintaining altitude
of that much wire. There's plenty of lift that actually increases with
wind pressure! I worked Arizona on 1855 Khz at midnight, 10 over S9 with
650 watts into it from my solid state Tentec Hercules II modified linear
amp....around 120A at 13VDC from two T-16H deep cycles and a cheap
charger.

Makes top-banding possible on my small lot.

This would work at sea if the damned boat didn't go up and down and back
and forth...(c; It'd work great at anchor in a quiet harbor...

Larry,
MARS group Field Day, Goldsboro/Seymour Johnson NC about 1969.....
1970? we put up two or three hydrogen filled balloons hauling several linked
spools of the braided phosphor-bronze antenna wire, all of which were parts
of the old "Gibson Girl" emergency radios. (Hydrogen generators, emerged in
water provided the gas) It was awesome on 160M! Six or seven hundred feet
long we estimated. We used what was a conventional antenna tuner in those
days, working the wire against four or five ground rods.
Thunderstorm Sunday afternoon sent us scrambling to take things down. I
was tasked to retrieve the balloon antenna. Someone noticed that each nearby
lightning strike caused a foot long blue crackling thing to come from the
free end of the downlead, now lying in the grass.
After several attempts to find some volunteer to wind in the precious
braided bronze wire, we gave up. Cut the tether and sent a Marsgram to the
nearest FAA office notifying them of the "accident".
That's my story and I'm stickin' to it.
Old Chief Lynn