After many frustrating experiences with unwelcome interaction between various 160 antennas and towers, I am thinking about going back to basics by removing all the other 160 wires, and shunt feeding the 110 foot tower (which has a number of yagis on it). All else being equal (such as ground system), are there reasons why a shunt-fed tower would work differently than a vertical of the same height, on an insulated base ? 73, Steve, N2IC _______________________________________________ Topband reflector - topband@contesting.com
Hi Steve and All, I was writing about my tests a few years ago but maybe it will be useful for some... I was using a Half Sloper on 20m high tower with TH6DXX on the top. I was very satisfied with this antenna and it "gave" me 280 DXCC that time. Anyway I decided to check how shunt fed tower will behave...I had relays on wires of sloper so I was able to make tests during QSOs in a real time. After more than 30 QSOs with stations of a distance above 5000 km I decided to stay with shunt fed system..95 % correspondents gave me 1 to 2 S better report when using the tower. I have to add the tower is only 4m from my house ( 9m high). Regarding detuning... I have K9AY about 30m from a tower and I was not very satisfied with it so I suspected the tower affects it. I made detuning described by John ON4UN (LB DXing fourth edition page7-94 fig.7-135) . I did it for both 80 and 160m so I'm able to switch it on TB on and off ( switching to 80m).. the difference is huge , the null at the back can be worse even 2 S when the antenna is not detuned. 73 GL Rys SP5EWY _______________________________________________ Topband reflector - topband@contesting.com