Hi Rick, A monoband current forcing balun doesn't require as much coax as you might think. The 1/4 wavelength of coax would probably be needed anyway, so the only "extra" length is the 3/4 wavelength coax and thats only 35 feet of RG-213 on 20 meters.
http://www.qsl.net/i0jx/balun.pdf For the price of 35 feet of coax you're 100% certain that the antenna feed is balanced. Admittedly this doesn't scale very well to 80 and 160 meters, but its a great performer on the higher bands including 6 meters. 73 Frank W3LPL ---- Original message ---- >Date: Sat, 14 Jul 2012 15:15:47 -0700 >From: "Richard (Rick) Karlquist" <[email protected]> >Subject: Re: Topband: Chokes, et. al. - what is the attenuation ? >To: [email protected] >Cc: [email protected] > > > >On 7/14/2012 1:19 PM, [email protected] wrote: >> I'm liking my current forcing, 1/4 wavelength and 3/4 wavelength coaxial >> baluns more and more! >> >> 73 >> Frank >> W3LPL >> >> > >On low bands, the Q of resonant stubs is fairly low. >Therefore, the effective common mode impedance of these >baluns will not be extremely high. If you want a >single band choke, you could get a higher impedance >more easily by using a low loss ferrite like 61 or 67 >to make a conventional common mode choke and then >resonate the choke with a shunt capacitor. It also >requires a heck of a lot less coax than a wavelength. > >Rick N6RK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
