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## Re: [TenTec] NEC, ground, grounds, and radials

 To: geraldj@weather.net, Discussion of Ten-Tec Equipment Re: [TenTec] NEC, ground, grounds, and radials Steve Hunt Discussion of Ten-Tec Equipment Sat, 08 Jan 2011 12:54:21 +0000 mailto:tentec@contesting.com>
 ```Correct! I believe it was Jerry who pointed me to the accurate formula a couple of years ago on this very List. I was considering how to build low impedance balanced line with a Zo in the range 50 Ohms to 70 Ohms for a Hexbeam application. One look at the published curves told me it couldn't be done; but Jerry put me right! Steve G3TXQ On 08/01/2011 02:05, Dr. Gerald N. Johnson wrote: > Like my curves its center to center. The upper trace is using the 276 > log formula and the lower one is the 120 inv hyperbolic cosine function. > Mine has the spacings on a log scale his is a liner scale. The upper > trace formula is increasingly inaccurate below 300 ohms impedance with > 87,000 percent error at a spacing just a hair wider than the conductors > touching. The wrong formula says you can't get a Z0 less than 87 ohms > (as published in QST last summer again), but the correct formula gets > down to practically zero Z0 just before the conductors make contact. > http://www.geraldj.networkiowa.com/papers/CSVHF2010/lztl1.JPG/ > http://www.geraldj.networkiowa.com/papers/CSVHF2010/lztl2.JPG/ > > 73, Jerry, K0CQ > > On 1/7/2011 7:46 PM, Jack Mandelman wrote: >> Steve, >> In your plot how are you defining S, the spacing between conductors? Is it >> center to center? Is it consistent for both the approximated and actual >> curves? It appears that only the actual curve uses the center to center >> definition; in the limit as S-->d the inner edge to inner edge spacing goes >> to zero, and Zo also goes to zero. >> >> Jack K1VT >> >>> Jerry, >>> A picture paints a thousand words: >>> http://www.karinya.net/g3txq/temp/ladderline_zo.png >>> 73, >>> Steve G3TXQ >>> On 07/01/2011 22:44, Dr. Gerald N. Johnson wrote: >>>> / I've published the same article twice now, once in The VHF'er in 1966/ >>>> / and last year in the proceedings of the 2010 Central States VHF >>>> Conference./ >>>> >>>> / So I have it available on line but not in a format that will be found >>>> by/ >>>> / search engines:/ >>>> / http://www.geraldj.networkiowa.com/papers/CSVHF2010/lztl1.JPG/ >>>> / http://www.geraldj.networkiowa.com/papers/CSVHF2010/lztl2.JPG/ >>>> / I suppose I should work up an html page that could be found by a search/ >>>> / engine and expand it with the history as I have found it./ >> _______________________________________________ >> TenTec mailing list >> TenTec@contesting.com >> http://lists.contesting.com/mailman/listinfo/tentec >> > _______________________________________________ > TenTec mailing list > TenTec@contesting.com > http://lists.contesting.com/mailman/listinfo/tentec > > _______________________________________________ TenTec mailing list TenTec@contesting.com http://lists.contesting.com/mailman/listinfo/tentec ```
 Current Thread Re: [TenTec] NEC, ground, grounds, and radials, Jack Mandelman Re: [TenTec] NEC, ground, grounds, and radials, Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials, Steve Hunt <= Re: [TenTec] NEC, ground, grounds, and radials, Jack Mandelman Re: [TenTec] NEC, ground, grounds, and radials, Steve Hunt Re: [TenTec] NEC, ground, grounds, and radials, Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials, Jack Mandelman Re: [TenTec] NEC, ground, grounds, and radials, Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials, Jim WA9YSD