Hi Glenn, You should be very worried about voltage breakdown of your base insulator! Do you know how much RF voltage your base insulator can safely handle?
A fourth idea you might consider is to simply use your tower to support a 1/4 wave vertical wire for 80 meters, fed against the same radials you use on 160 meters. This may be your easiest and most effective solution. I'm sure other Topbanders use the same solution for 80 meters. While a 1/2 wave vertical theoretically has a small amount of gain compared to a 1/4 wavelength vertical, in actual practice useful gain cannot be achieved when its mounted very close to average soil. The situation would be different in a salt marsh. 73 Frank W3LPL -----Original Message----- From: Topband [mailto:[email protected]] On Behalf Of Glenn Biggerstaff Sent: Saturday, February 28, 2015 8:16 PM To: [email protected] Subject: Topband: 160 Tower on 80 Hi all, I have a 90 foot Rohn 25 tower with an insulated base and insulated guy wire sections for top loading ,base fed for 160 meters. It work great ,but I would like to use it on 80 meters as well. The 3 ideas I have considered are voltage feed at the base with a resonant LC network at the base, but I am a little worried about the voltages present at legal limit power. Second idea,disconnect the top loading and put a trap between the top loading and the tower to divorce the top loading on eighty then an L network at the base for 80. Third idea, run a wire as a sloper either a quarter wave fed against ground or a 1/2 wave dipole from the tower. Any thoughts or alternative ideas would be greatly appreciated. Glenn WW4B _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
