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#1
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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
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On Tue, 10 Jan 2006 16:56:56 -0500, Jon Gauthier
wrote: 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? The AT-134/140 is not designed to drive a balanced feed line, only unbalanced. You could probably drive a balun coil in reverse however, and run co-ax up the mast to a dipole. |
#3
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On Tue, 10 Jan 2006 20:08:05 -0500, Wayne.B
wrote: The AT-134/140 is not designed to drive a balanced feed line, only unbalanced. You could probably drive a balun coil in reverse however, and run co-ax up the mast to a dipole. ====================================== Upon reflection, that didn't come out right. What I meant was that you could probably drive the unbalanced side of a balun with the tuner if you wanted to run twin lead or ladder line to the antenna. |
#4
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Wayne.B wrote in
: You could probably drive a balun coil in reverse however, and run co-ax up the mast to a dipole. 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; |
#5
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Larry wrote:
Wayne.B wrote in : You could probably drive a balun coil in reverse however, and run co-ax up the mast to a dipole. 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; Larry, that's what you keep a balloon and tank of helium for. Or a kite for those of us on the cheap! |
#6
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![]() "Jon Gauthier" wrote in message ... 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 have an AH-4 tuner mounted on the stbd qrtr pushpit. My antenna is a 28 ft wire hauled up with the main and mizzen peak flag hoists. It is somewhat in an inverted-L configuration. I am sure that any wire can be hauled up in the air by a halyard or flag hoist to give him a reasonable length of wire in the air. I have seen people hang inverted Vees from the spreaders, but they have to switched over when changing tacks. On a Pacific crossing attempt, the boat that I was on, had a trapped vertical mounted the tubing for the vane. We had to guy it, but it worked reasonably well and had a great ground plane. Leanne s/v Fundy |
#7
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Jon Gauthier wrote in
: Larry, that's what you keep a balloon and tank of helium for. Or a kite for those of us on the cheap! 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... |
#8
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On Fri, 13 Jan 2006 20:08:42 -0500, Larry wrote:
around 120A at 13VDC from two T-16H deep cycles and a cheap charger. Careful Larry, we don't want any melting or exploding lead around here. |
#9
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Wayne.B wrote in
: On Fri, 13 Jan 2006 20:08:42 -0500, Larry wrote: around 120A at 13VDC from two T-16H deep cycles and a cheap charger. Careful Larry, we don't want any melting or exploding lead around here. 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. |
#10
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"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 |
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