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Sail Magazine article on ham antenna?

Discussion in 'Boat Electronics' started by Jon Gauthier, Jan 10, 2006.

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  1. Jon Gauthier

    Jon Gauthier Guest

    A friend of mine who's cruising the Eastern Caribbean asked me to
    investigate a ham antenna that someone told him about, which they saw in
    "Sail". My subscription ran out months ago, and I also can't find it on
    their website.

    Anyone here recall the article - it was about a HF antenna you could
    hoist up the mast. Probably a take on an inverted V, but I can't make
    any recommenations to him unless I can see exactly what he's referencing.

    He currently has a fiberglass whip tuned with an Icom tuner (AT-140 or
    an older AT-130?). His boat is a 41' catamaran. He's having trouble with
    his setup - can only reach up to 100 miles or so with 40-10 meters. It
    almost sounds like he's using only ground-wave propogation, or his
    vertical is radiating vertically vis-a-vis NVIS...

    I know I can have my AH-4 tuner drive a length of ladder line, so could
    he use his AT-140/130 to do the same, and feed the center of a dipole
    60' up his mast, with each end insulated at the bow and stern?
     
  2. Larry

    Larry Guest

    Cool idea! 40 meter shrouds, 75 meter backstay/furler. 20 meter traps in
    the 40 meter shrouds should do it.

    If we connect the triattic to the mizzen's boom lift, we should have enough
    length for 160 meters...(c;
     
  3. Jon Gauthier

    Jon Gauthier Guest

    Larry, that's what you keep a balloon and tank of helium for. Or a kite
    for those of us on the cheap!
     
  4. Larry

    Larry Guest

    [email protected] 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...
     
  5. Larry

    Larry Guest

    Not a problem. It only draws that kind of PEAK current on SSB RF peaks.
    Average current drain is around 30A only when transmitting, which is quite
    safe.
     
  6. Lynn Coffelt

    Lynn Coffelt Guest

    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
     
  7. Larry

    Larry Guest

    Old Chief Lynn
    Back before Hurricane Hugo blew it all away, the USCG's old 1.9Mhz Loran
    "A" station on the North end of Folly Beach still had its original 1/4
    wave tower on the beach, the building was there but the equipment was
    gone. It took me about 8 levels of CG bureaucrats, but I finally got
    permission to go over to the station, with the key, and operate ham radio
    from this fine example of a 160 meter vertical antenna on the Atlantic
    Oceanfront for a weekend. We took a bunch of dedicated crew and operated
    all weekend, logging hundreds of 160M DX from Europe, Africa, Middle
    East, Japan....stations I didn't think possible on such a low frequency
    band running so little power as we were limited to.


    The old antenna served us well but we never got to go back because Hugo
    came and blew the top of the antenna away. The stub that's left on its
    solid old mount is a weather station for NOAA, now:

    http://www.ndbc.noaa.gov/images/Stations/fbis1.jpg

    Under that base is about 36 radials under those salt-water dunes, the
    perfect ground plane. It was a great weekend of hammin'...(c;

    73 DE W4CSC
     
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