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Jim noname wrote:
My first is about the classic ground plane built on a so239 connector. I went with #14 wire and soldered the center wire on no problem. My question is whats the sturdiest way to stick on the radials? I have a 100 watt iron and still can't get a solid connection for the radials. See the message in another thread, about using a hot-air gun to pre-heat the connector before applying the iron. That'll do it. #14 wire will tend to sag under its own weight, so it's better to use thicker copper wire like #12. Some designs show the radials attached with solder-tags, but in my experience they bend. It's better to crimp radials through each of the four holes in the socket, and then solder them on directly. Cut the radials to their final length *after* you have completed the crimping and soldering. There may be a problem with soldering to some kinds of plating, so choose a connector made from brass as the base material. Drill the surface plating out of the four holes, and also file it away around the corners so you're soldering to bare brass. Also pre-tin the four corners with solder before you crimp on the heavy wire radials. Then it will solder easily. If the SO239 doesn't have teflon insulation, screw on a PL259 to keep the center pin from moving when the insulation softens, and leave it to cool down before you remove the plug. Finally, be aware that the feedline needs to run straight down through the four sloping radials and some way beyond. If you notice any weird behavior, it's probably due to RF currents on the surface of the feedline - this type of antenna is quite prone to that problem. Two large ferrite beads clipped onto the feedline will probably fix it; use one right behind the PL259, and a second one about 19in down. Having said all that, any 2m antenna will work much better outside! If you're tied up in CC&Rs, take a look at the Ventenna concept for a well-disguised outside antenna. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
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