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
