Spring / Summer backyard tower project

[Rob_Walker]

Rob, it was I who posted the comment about where to place a common mode choke and how to wind it. It doesn't matter what diameter you wind the coil of coax; the key is to keep it neatly wound and use enough coax. I have attached a picture of mine (well, one of mine) so you can see how I did it.

John, VA3KOT

John,

I read a good article on common-mode chokes.  The author built all these different air and ferrite core chokes then measured their impedance across different frequencies with a VNA.  That's a nice toy to have.  I have a customer in Cambridge that purchased a VNA for $80k to test the jackfields they make for the broadcast industry.

http://www.karinya.net/g3txq/chokes/