On Fri, 14 Nov 2008 15:45:07 +0700, Martin Sole wrote: >I plan to use RF chokes at the feed point of my quad elements and would >like some ideas on a few parameters. http://audiosystemsgroup.com/RFI-Ham.pdf See the Choke Cookbook and the tutorial material that precedes it. For your needs, #31 and #43 cores are equally good. 73, Jim Brown K9YC