[AReU] Common-mode chokes

[Ron Youvan]

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


   This website discusses es demonstrates how the wrong CM choke can hurt instead of helping you. 
It fails to emphasize the main reason to use a CM choke at the feed point of an antenna, which is to 
minimize the feedline radiation (so your signal is not circularly polarized) es to minimize the 
un-balancing the effects of unseen metal objects in the "near field" of the antenna, such as metal 
ducts in your attic. (or a great nearness to a tree on only one end, which will increase your 
feedline radiation)

   It also demonstrates how many turns of coax you need to make an air core coaxial balun on the 
lower frequencies bands.  (I found it surprising.)

CM = common mode
-- 
    Ron  KA4INM - Every HAM should have at least one desk MIC,
                  it's the perfect place to hang the cans when
                  CW is "arm chair copy."