Bob, You didn't mention the model or manufacturer of your tower. The best installation involves a genuine tapered bottom section of the type made to accommodate a ceramic base insulator. Usually when you find one, you also get the mounting hardware and ball gap that accompanies it. You have to construct a concrete pier so the insulator is elevated. This keeps it up above water, snow, blowing debris etc. You have to have four copper straps coming down from the bottom of the insulator to the ground system so that the concrete does not have voltage across it--only the insulator should. The tapered or cylindrical insulator and tapered bottom section should seat into a pin hole on the bottom hardware mount allowing the tower to rotate so there is no twisting of the tower. Obviously you need to guy the tower as it is not free standing and the guys must either be RF transparent or be broken up with johnny ball insulators so they do not distort the pattern.
If you want to employ a free standing tower, or if you cannot find a bottom section or insulator or both, you can construct a tower and skirt feed it. You line the tower with 3 or 4 hot wires on insulators running up the sides with horizontal rings connecting them to each other every 20 feet or so and a ring at the top and bottom. If the tower is guyed you'll still need to break up the guys so they don't distort the pattern. Either way a quarter wave vertical with 100+ quarter wave radials will be a great flame thrower. There's no need to reinvent the wheel. You can find a lot of photos on-line of broadcast tower bases. This page should give you some ideas: http://www.amgroundsystems.com/projects_2013.html 73 Rob K5UJ _________________ Topband Reflector Archives - http://www.contesting.com/_topband
