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What follows is based on experience in an environment where hurricanes etc do not occur (altho I have been visited by Cyclone Bola, reading about 140 km/h in a relatively sheltered weather station in Auckland City and would have been much stronger at my QTH. (Incidentally my C3-S and pipe mast that I was using came through it without any problem...) If we are talking about a small beam at 35-40 ft then the loadings are small and modest suppport structures will do a fine job. Consider yacht masts of around 35-40ft which have to sustain much higher loads than that gnerated by even a monster beam. Mention has already been made of roof mounts. For a mast: Out here 2in OD thick walled alumin or steel tube in 20ft (6m) lengths is used in quantity for scaffolding and temporary structures.. I assume there is similar practice in North America. The beauty of this stuff is that there is a ready supply of jointers, flanges and other fittings as stock items, not to mention more fittings available for 2in OD used for making supports for chain link fences, handrails and the like. Means that all manner of things can be done without welding. We are talking guyed structures here. The long and short of it is that if you put together two twenty foot lengths and put a light beam on top of it the whole caboodle can be wrestled into a vertical position by a few good keen men (or women), the guys tied off and you are in business. Can still be done if you put a light rotator on the top, but better to put the rotator on a length of strong rot proofed plank at ground level and lift the whole works into the rotator once the mast is vertical. Usually needs two sets of guys or top guys and a house bracket lower down. The mast can rotate if the guys are attached to a flange (you can even get flanges with four holes in the flat) supported by another flange which is secured to the mast. You do not need massive guys. Out here seven strand galvanised wire is commonly sold as clothes line wire and will do just fine. Even 16g high tensile fence wire will do well once you learn how to work with it. Electric fence insulators made from ABS plastic are light, cheap and strong. Need them to break up metallic guys. Of late I have become a bit paranoid about the potential of guys to distort beam patterns and would probably go synthetic rope for the upper guys.Probably just for peace of mind. Make sure the rope type used does not deteriorate from UV , tho. Loadings are relatively light. You can use synthetic rope lanyards instead of turnbuckles at the bottom of the guys. Cheaper, easier to use and more reliable than turnbuckles if you replace them every year or three. On verticals: unless you are at the seaside, ground mounted verticals are really pushing it up hill on the higher bands and strongly advise getting the vertical up above power wires, house wiring etc to make them play. ie roof mount the vertical. On the other hand once the vertical is roof mounted the top of it is at the height at which a simple all band inverted vee dipole would likely perform better.....and cheaper. My 02 c NZ worth (= 008c US) 73 Barry PS My take on this is that typical small amateur towers are seriously overdesigned and overweight. For the inevitable blathering about PE reports etc : If the mast and beam are made light, one would need to be dead unlucky if it did major damage even if it did fall over. end Barry Kirkwood PhD ZL1DD Signal Hill Homestay 66 Cory Road Palm Beach Waiheke Island 1240 NEW ZEALAND ph/fax 64-9-372-5161 www.waiheke.co.nz/signal.htm ----- Original Message ----- From: "Jason Hissong" <jhisson1@columbus.rr.com> To: <Force12Talk@qth.com> Sent: Monday, October 14, 2002 7:09 AM Subject: [Force 12 Talk] Was F12 Verticals > Thanks for the great replies guys, direct and to the list. Instead of > replying to everyone individually, I will reply to the list (as it may be > relevant to others out there). I also got some replies from the tower talk > list as well. > > It seems that going with a beam is worth it when you use a mast (to keep > costs down). I take it with a mast, the rotator is on top right? What type > of mounting on the ground do you need? As far as guying is concerned, if I > attach a mast to the back of my garage, can I guy the tower to parts of the > house? The Force12 Low Profile Towers seem like a good compromise. I would > probably go with the 41' version. I would want to mount it to the back of > the garage (if it is that small, I could probably mount it to the side of > the house where the garage and house meet.) I have an MQ1 already that I > bought cheap, but I like the idea of a 5 band antenna. > > With the military masts, could I attach it to the side of the house somehow? > Anything I can make retractable and safe, I can use. And I do not think the > city is actually going to come out and measure that the antenna is exactly > 35' high when extended :) > > Thanks! > > Jason Hissong > N8XE > > > > -------------------------------------------- > Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. > Force12 Web Site: http://www.force12inc.com > > To Submit Message to the List: Force12Talk@qth.com > To unsubscribe and view the Message Archive: see http://qth.com/force12/list > For problems with the list: contact n4zr@qth.com > > > -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact n4zr@qth.com |
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