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## Re: [TowerTalk] dipole length adjustment

 To: Re: [TowerTalk] dipole length adjustment "David Robbins K1TTT" k1ttt@arrl.net Sat, 20 Jan 2007 13:35:07 -0000
 ```I prefer the 'close enough' adjustment method. This works for any units and any band. The formula is just length*change/frequency As long as the units of 'change' (how much you want to move the resonance) and frequency are the same it will give you how much to cut or add in whatever units you use for length. Note that length can be the current length, the desired length, or just the guestimated length for the band. And frequency can be the current frequency, the desired frequency, or just the center of the band. As long as you don't try to use it to retune a 30m dipole to 40m or something like that it will be 'close enough'. Don't believe me... consider this case, a 40m dipole that is resonant at 6900khz and you want it at 7100khz. Change =200khz Assume current length is 32' 32*200/7100=.9' (10.8" or lets say 11") but if you were a bit off and its really 33' 33+200/7100=.92' (11.04".. close enough) but what if you used 7000khz or even worse 6900khz 32*200/6900=.92' oh, prefer meters... assume current length is 10m 10*200/7100=.28m really 10.3m? 10.3*200/7100=.29m (does 1mm really matter??) or you used 6900khz? 10*200/6900=.29m so don't worry about all the spreadsheets, fancy formulas, and other stuff... just cut it long, find that first resonance, and snip away. Oh, and remember this... how close is 'close enough' is proportional to how hard the adjustment is to make. That is, the harder it is to make the adjustment (climbing a roof, or tower is harder than snipping from the ground) the wider the limit is on 'close enough'. Remember "Too low an SWR can kill you!". David Robbins K1TTT e-mail: mailto:k1ttt@arrl.net web: http://www.k1ttt.net AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread [TowerTalk] dipole length adjustment, Robert Chudek - K0RC Re: [TowerTalk] dipole length adjustment, David Robbins K1TTT <= Re: [TowerTalk] dipole length adjustment, Cecil Moore Re: [TowerTalk] dipole length adjustment, k6xyz Re: [TowerTalk] dipole length adjustment, Cecil Moore