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#1
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Thanks Doug
So it would work well as an antenna for marine SSB? If so I'm a bit surprised more people don't use this instead of trying to achieve that elusive ground plane in the hull. Sounds like you could just run the feed wire inside the mast if you don't need standoffs and the whole installation would be pretty slick. "Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message ... That's a slightly different animal. It is acts essentually like a dipole which is a balanced antenna. Balanced antennas do not need a ground plane. Standoffs are not needed because the mast is part of the ground side of the antenna which is what the shield on the coax is. I experimentd with a real dipole by stretching it between the masthead and the radar arch. It was fed in the middle with a balun. Worked well, but keeping the feedline out of harms way proved to be a problem. If the antenna in question was fed with coax, a balun would be desirable. Doug, k3qt s/v Callista "Gordon Wedman" wrote in message news:6wAEd.61994$nN6.13173@edtnps84... Over the holidays I killed some time looking through a few back issues of Cruising World. In the April 1986 issue a boat-based ham operator said he used a top-fed backstay antenna with excellent results AND he had no in-hull ground plane. He said he connected the shield from his feed wire to the mast-side of the backstay and this allowed the mast and all the standing rigging to act as a ground plane. He didn't say anything about using stand-offs between the feed wire and the mast. I would think you would get a lot of signal loss over that much length if you didn't use stand-offs? If a person could put up with the appearance and make sure the whole set-up didn't get torn down by sails/running rigging, would this really give good performance? I don't recall reading about this type of set-up so I guess its not too common on recreational boats but maybe it could be worth considering in some situations? |
#2
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Well, the tuners that come with marine sidebands (AT-140 etc) are
designed for end-fed long wires. Also, dipole lengths are specific to the band one is working. Multiband operation would require some sort of traps in both the backstay (sort of easy) and also matching traps in the mast (really hard!). So in short, you can eliminate the ground plane, but you also inherit less flexability. You also need to get an antenna tuner that can tune a dipole. There has been some discussion about tuning the entire rig (W4CCC) but I have no experience in that area. Larry (W4CCC) also seems to have vanished from this forum. I hope it was not a result of RF burns or that someone pointed out there is no record of his ham licence in the FCC database ![]() The elusive groundplane in the hull is a myth. Run foil from the tuner and radio to a thruhull and you are done. Make sure the thruhull is not part of a bonding system, it must be isolated. I wrapped the foil around a cockpit scupper seacock and secured it with a hose clamp. I get excellent signal reports and had no problems doing email from The Bahamas to dozens of land station inside the US and Canada. Let me know if you want to arrange for a QSO to check out my signal. Doug, k3qt s/v Callista "Gordon Wedman" wrote in message news:xhDEd.91279$KO5.69231@clgrps13... Thanks Doug So it would work well as an antenna for marine SSB? If so I'm a bit surprised more people don't use this instead of trying to achieve that elusive ground plane in the hull. Sounds like you could just run the feed wire inside the mast if you don't need standoffs and the whole installation would be pretty slick. "Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message ... That's a slightly different animal. It is acts essentually like a dipole which is a balanced antenna. Balanced antennas do not need a ground plane. Standoffs are not needed because the mast is part of the ground side of the antenna which is what the shield on the coax is. I experimentd with a real dipole by stretching it between the masthead and the radar arch. It was fed in the middle with a balun. Worked well, but keeping the feedline out of harms way proved to be a problem. If the antenna in question was fed with coax, a balun would be desirable. Doug, k3qt s/v Callista "Gordon Wedman" wrote in message news:6wAEd.61994$nN6.13173@edtnps84... Over the holidays I killed some time looking through a few back issues of Cruising World. In the April 1986 issue a boat-based ham operator said he used a top-fed backstay antenna with excellent results AND he had no in-hull ground plane. He said he connected the shield from his feed wire to the mast-side of the backstay and this allowed the mast and all the standing rigging to act as a ground plane. He didn't say anything about using stand-offs between the feed wire and the mast. I would think you would get a lot of signal loss over that much length if you didn't use stand-offs? If a person could put up with the appearance and make sure the whole set-up didn't get torn down by sails/running rigging, would this really give good performance? I don't recall reading about this type of set-up so I guess its not too common on recreational boats but maybe it could be worth considering in some situations? |
#3
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Oh, and I forgot. I don't use an insulated backstay. I have a 23' whip
mounted on the transome. Doug, k3qt s/v Callista "Gordon Wedman" wrote in message news:xhDEd.91279$KO5.69231@clgrps13... Thanks Doug So it would work well as an antenna for marine SSB? If so I'm a bit surprised more people don't use this instead of trying to achieve that elusive ground plane in the hull. Sounds like you could just run the feed wire inside the mast if you don't need standoffs and the whole installation would be pretty slick. "Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message ... That's a slightly different animal. It is acts essentually like a dipole which is a balanced antenna. Balanced antennas do not need a ground plane. Standoffs are not needed because the mast is part of the ground side of the antenna which is what the shield on the coax is. I experimentd with a real dipole by stretching it between the masthead and the radar arch. It was fed in the middle with a balun. Worked well, but keeping the feedline out of harms way proved to be a problem. If the antenna in question was fed with coax, a balun would be desirable. Doug, k3qt s/v Callista "Gordon Wedman" wrote in message news:6wAEd.61994$nN6.13173@edtnps84... Over the holidays I killed some time looking through a few back issues of Cruising World. In the April 1986 issue a boat-based ham operator said he used a top-fed backstay antenna with excellent results AND he had no in-hull ground plane. He said he connected the shield from his feed wire to the mast-side of the backstay and this allowed the mast and all the standing rigging to act as a ground plane. He didn't say anything about using stand-offs between the feed wire and the mast. I would think you would get a lot of signal loss over that much length if you didn't use stand-offs? If a person could put up with the appearance and make sure the whole set-up didn't get torn down by sails/running rigging, would this really give good performance? I don't recall reading about this type of set-up so I guess its not too common on recreational boats but maybe it could be worth considering in some situations? |
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