Hi, Bob End feeding that 160m 1/4 wave as an 80m 1/2 wave should work great! For several years I ran a vertical 40m 1/2 wave that I fed at the bottom through a 1/4 wave of 450 ohm ladder line. Perfect match (almost 1:1) on the CW end of 40m with NO TUNER! I could run it to full power with a FT-757 GX that I had at the time with nop antenna tuner. It had good BW and runnng it all across 40m was no problem, although I've always been mostly a CW DXer. I workd everywhere on the planet with that antenna! I later added a reflector and director for Bouvet and worked 'e first call in a BIG east coast pile when they came up. (Jacky, F2CW at the key). Late It was a reall killer on the evening 150 degree LP into SE Asia, and when ZS8MI came up, I almost missed him because he was S9+20db on the FT-757!
No, you don't need any radial field under a vertical 1/2 wave. You'll be driving a few thousand ohms, so a a few ohms or even 50-100 ohms of ground resistance won't add any significant loss. A simple ground rod will do fine. You can start and drive it with "slam-pipe" if you know what that is. (You ight be able to borrow one from an electrical utility guy. And, as you say, the high-current maximum will be up 1/4 wavelength so you'll have an excellent low take-off angle! Enjoy! BTW, when I did the 1/4 wave matching section, I did take care to feed the antenna with the side of the 450 ohm line that was connected to the center conductor of the coax, Of course, you could also feed it with an 80m parallel-tuned circuit, that you would tap down to find the 50 ohm point. Have fun!! I Think you'll be pleased! 73, Charlie, K4OTV -----Original Message----- From: Topband [mailto:[email protected]] On Behalf Of Bob K6ZZ Sent: Monday, January 06, 2014 10:19 PM To: [email protected] Subject: Topband: Feeding 160M Vertical on 80M Folks, I have a 60' tall top loaded vertical for 160M and would like to know how best to feed it to use it on 80M as well. On 80M there will be some pretty high voltages at the feedpoint. Other than dealing with high voltages, is doing this a bad idea (or good idea) for any partcular reason(s)? The high current point would be higher above ground which seems beneficial at the very least. What would be the best method for matching it on 80M? Do 1/2 wavelength ground mounted verticals require the same quality ground radial system that 1/4 wavelength verticals require? Thanks and HNY to all! 73, Bob K6ZZ _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
