On 28/08/2012 19:29, Eddy Swynar wrote: > I am thinking of incorporating a homebrewed 4:1 balun as part of a transmatch > that I have here, which was designed to feed coaxial cable-fed antennas > only... > > Is there really & truly such a thing as an air core 4:1 balun that will cover > the entire spectrum from 1.8- to 29.7-MHz...? I've looked & I've repeatedly > searched on the internet, but can not quite come up with such an animal. > Maybe the frequency range of such a beast is far too great for any practical > design... > > Anyone have any leads in this regard...?
I've not come across anything that would cover that much spectrum in one unit that didn't have ferrite in it. I needed something very similar to match a doublet. I ended up with a pair of coax baluns (in series - don't tell me!) and I get 1:1 indicated on the input to the transmatch on all bands 80 to 10. The doublet is too short for 160m, so is fed as a T on that band, and loaded quite differently. The main balun is 14 turns of good quality RG213 on a 4 inch plastic drainpipe former. The smaller one is 6 turns. 73 Keith G3OIT _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
