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--------- Forwarded message ---------- From: wa4dou@juno.com To: calav@flash.net Date: Mon, 15 Jan 2001 17:16:42 -0500 Subject: Re: [Force 12 Talk] C-31XR Balun ... Message-ID: <20010115.171646.-951555.15.wa4dou@juno.com> Ken These arguements appeal to my technically intellectual mind. But they do nothing for the pragmatist in me that says, all other arguements notwithstanding, if there is not significant real world results then all you're doing is contemplating your navel. As regards the 2 element yagi, even LB W4RNL says he has heard reports of that nature but just doesn't know what to make of them in light of present knowledge and understanding. That antenna was 30 ft. off the ground in Jacksonville Beach, Fl. and no more than 75 yds off the beach. Its pattern was very sharp on the nose of it, leaving no doubt that the pattern was symetrical and there was a deep null to the side and rear that was also symetrical. It was the same phenomonon on all azimuths. Fact is Ken, there are things at work here that still remain unknown. And one of them is that if "feedline" radiation really is a reality 100% of the time, then pattern skewing and null fill still can only occur if feedline radiation occurs at angles that produce worthwhile radiation. Regardless, i stand by my statements and i've long been aware of the nature of baluns and the supposed theory behind them. Still, they aren't always needed and their absence doesn't always lead to detrimental results, measurable, psychological or otherwise. 73 Roy WA4DOU ------------------------------------------------------------------------- ------------------------------------------------------------------------- ----------------------------------------------------------------------- On Mon, 15 Jan 2001 14:49:30 -0700 Ken Hirschberg <calav@flash.net> writes: > Roy - > The distortion of the pattern that I'm referering to is mainly due > to > unbalanced current in a driven element. Feeding a balanced, > symetrical > element with an unbalanced feedline, except in certain special > cases, will > create unbalanced current. If the currents are unbalanced, the > pattern will > be disrupted; always, not sometimes. Whether the feedline radiates > energy > into space or couples it into a tower leg, does not matter as far as > the > current imbalance is concerned. > > Please see Weeks, W.L. , Antenna Engineering, McGraw-Hill, 1968, for > an > excellent dicussion of the balun issue. > > If you got 20-30 dB of front to rear out of a 2 element parasitic, > congratulations are in order; you are the new world record holder! > 73, Ken > > wa4dou@juno.com wrote: > > > Ken and Natan > > I'm sorry but i believe you're propagating a "can sometimes > happen" > > into a virtual certainty. I once built a 2 element yagi that had > 20-30 db > > of front to side and f/b ratio in all directions. It used no balun > and > > was a killer antenna to Europe and Africa and South America. Lots > of > > signals totally disappeared when to the side or rear of that > antenna. > > Your computer modeling programs today say thats not possible. They > also > > claim that feedline radiation is always a problem, it just isn't > always > > so. If feedline radiation had been a problem with that antenna and > with > > my present one, then it would manifest itself as skewed patterns > and f/b > > f/s degradation. It doesn't. I'm still going to try my EB-1 on my > C3SS. > > I stand by all i wrote and ,once again, i encourage others to > > experiment with both possibilities and decide for themselves and > report > > their findings in appropriate amateur forums. > > 73 Roy WA4DOU > > > ------------------------------------------------------------------------- > > > ------------------------------------------------------------------------- > > > ----------------------------------------------------------------------- > > On Mon, 15 Jan 2001 12:36:51 -0700 Ken Hirschberg > <calav@flash.net> > > writes: > > > Hello, Roy - > > > Suggest you measure the feed line over a length of half a > wavelength > > > to determine what currents are flowing on the outside. Then > install > > > the balun and repeat the measurement. If you find currents > flowing > > > on the outside of the feed line, then rest assured the pattern > will > > > be > > > skewed. > > > 73, Ken > > > > > > > > > wa4dou@juno.com wrote: > > > > > > > Hello Frank and the gang, > > > > While considerable debate still attaches itself to the whole > > > subject of > > > > baluns, i'd like to remind folks, especially those who run > > > considerable > > > > power and have one or more failures associated with their use, > > > that it > > > > has hardly been demonstrated that baluns are necessary in many > > > instances, > > > > despite the fact that the "benefit" of the use thereof is > > > conducive to > > > > near perfect theoretical performance in the mind of the user. > > > > I have a F12 C3SS on a 53 ft. tower and have used it for > nearly > > > a year > > > > without any balun whatsoever. During most of that time, i've > had a > > > Cal-Av > > > > EB-1 balun which i intend to install in the Spring. Then i'll > have > > > a > > > > "baseline" with which to judge the performance and necessity > of > > > using a > > > > balun in my particular installation. So far, my impression of > my > > > antennas > > > > f/s and f/b performance is consistent with the performance > > > expectations > > > > of a typical 2 element yagi. > > > > I have had other yagis and quads with which i've sometimes > used > > > baluns > > > > and sometimes not. I've even experienced 2 element yagi > > > performance > > > > (without benefit of a balun) that far exceeded theory on both > f/b > > > and f/s > > > > in all directions. And i've definitely seen occasions where > baluns > > > were > > > > desirable and did effect positive results. > > > > That said, i'd like to encourage users and potential users > to > > > suspend > > > > judgement and to evaluate their antennas, with and without and > > > report > > > > their findings in various appropriate forums. Efficiency > dictates > > > that > > > > the simplest installation that achieves the desired result is > > > always to > > > > be desired. As a radio communications technician and ham of > 39+ > > > years, i > > > > believe i'm capable of making accurate scientific observations > in > > > this > > > > case. > > > > 73 de Roy Lincoln WA4DOU > > > > > > > > > > ------------------------------------------------------------------------- > > > > > > > > > > ------------------------------------------------------------------------- > > > > > > > > ----------------------------------------------------------------------- > > > > > > > > > ________________________________________________________________ > > > > GET INTERNET ACCESS FROM JUNO! > > > > Juno offers FREE or PREMIUM Internet access for less! > > > > Join Juno today! For your FREE software, visit: > > > > http://dl.www.juno.com/get/tagj. > > > > > > > > > > > > > > > > > > -------------------------------------------- > > > Force12Talk mailing list provided as a service by Force 12 > Antennas, > > > Inc. > > > Force 12 Web site: http://www.qth.com/force12 > > > > > > Submissions: send to Force12Talk@qth.com > > > To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com > > > Force12Talk Message Archive: > http://www.qth.com/force12/list/force12talk > > > For problems with the list, contact n4zr@qth.com > > > > > > > > > > ________________________________________________________________ > > GET INTERNET ACCESS FROM JUNO! > > Juno offers FREE or PREMIUM Internet access for less! > > Join Juno today! For your FREE software, visit: > > http://dl.www.juno.com/get/tagj. > > > ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! 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