Just bought the last copy of this book that Amazon had in stock for 17.95 + 3.99 in shipping. Looks like it will be a very nice reference to have on the shelf...
Thanks! ~Brett (N7MG) On Fri, Jul 23, 2010 at 5:21 AM, WILLIS COOKE <wrco...@yahoo.com> wrote: > Brett, I would recommend the Book "Understanding, Building and Using Baluns > and Ununs by the late Jerry Sevick, avaliable from CQ > http://store.cq-amateur-radio.com/Categories.bok?category=Books%3AAntennas&searchpath=1547318&start=10&total=17 > With this book, a BS in Physics, 54 years as a ham and 30 years as an EE I > finally understood enough to make a balun or an unun. I don't understand > them well enough to answer your questions correctly. I read all the stuff I > could find on the internet and 50 years of ham magazines before I bought the > book and was still too confused to pick a core and build the unun that I > needed. If you just want a 4:1 balun and don't want a study course, I would > recommend that you buy one. If you really need one that works 160 to 10 buy > an expensive one from a good source, the ones that I tested did not have the > advertised bandwidth. I did not test the Elecraft balun, but what I have > seen of Elecraft engineering would give me confidence to try one. > > Willis 'Cookie' Cooke > K5EWJ > > ________________________________ > From: Brett Howard <br...@livecomputers.com> > To: elecraft <elecraft@mailman.qth.net> > Sent: Fri, July 23, 2010 3:53:42 AM > Subject: [Elecraft] Balun Questions > > I'll preface this by explaining that I'm a digital guy and I've lately > decided I want to get a little better understanding of magnetics and > RF... Thus why I'm taking on making my own W3NQN band pass filters and > I've also been interested in building a Balun... > > So I've looked at a few sites describing how to make a 4:1 balun... One > such solution is to take 2 100 ohm 1:1 baluns and connect them in > parallel on the input side and in series on the output side... > > I looked at the Elecraft BL1 manual but I didn't see what material the > core was... However in another article I saw someone post the recommend > getting a FT140-61 and winding 7 to 8 turns on each side to make the two > 100 ohm feedlines. > > So I ran the numbers and 8 turns on a FT140-61 gives you about 100 ohms > on 160 meters. Thus two 100 ohm points in parallel gives you 50 ohms in > and 200 ohms out. 4:1... Great. > > However at say 40 meters... Each feedline is 430 ohms. Thus you've got > a 215ohm input and a 860 ohm output. This just seems like it would make > a mess. Why does it still work? > > Finally I'll explain my final goal... I've looked at several ways to > make a 4:1 which involves using two 1:1's. Then there are methods to > take 2 4:1's to make a 6:1 (the feedlines are 125ohm windings to pull > this off). My final goal is to try to make a 6:1 and use it to use > ladder line once I get through the wall with coax. I always just > figured that a 6:1 would be better as it would have a 50 ohm in and a > true 300 ohm out. > > However once you get away from the design frequency the feed impedances > go to pot... So is there really much difference in the 6:1 and the 4:1? > I've read of many people doing what I'm talking about with a 4:1 and > just figured that a 6:1 should provide a better match... Am I thinking > right or is the match so terrible anyway that it doesn't so much > matter? > > Is it just that the thing balances the currents on the outputs and I'm > just over thinking the matching ability? > > Appreciated gentlemen. > > ~Brett (N7MG) > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
