[TowerTalk] VHF/UHF Common Mode Choke

David Gilbert xdavid at cis-broadband.com
Fri Jun 28 14:50:19 EDT 2019

I've never been much interested in VHF/UHF, but with the current level 
of solar flux and the summer static I'm thinking of giving it a try 
using homebrew antennas based upon DK7ZB designs.  For 6m I'll probably 
use a coaxial sleeve as a common mode choke (unless somebody can suggest 
something better/simpler), but for 2m/70cm I'm planning to build a dual 
band yagi with a common feedline and I'm not sure a sleeve would work.  
I guess it might, since 1/4 wave and 3/4 wave (432/144 = 3.00) 
accomplish pretty much the same thing, but I'd like some input from 
VHF/UHF hams who would know better than I.

And if a sleeve balun is indeed the way to go, what is the best way to 
fabricate one at UHF?  As W8JI points out, coax jackets aren't 
necessarily a low loss dielectric at UHF.

Thanks much for any suggestions.

Dave   AB7E

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