Topband: Toroidal common mode choke

["Bill Conwell \(home\)" <bill@conwellpdx.com>]

I've got an FT-240-43 core on which I'd like to wind RG58 to make a choke
for the feedpoint of my inverted-L.

 

I've seen articles that studied the optimum number of turns for air-core
chokes, but don't recall seeing any for toroidal chokes.  Can anyone offer a
pointer (or empirical data) that might guide me.  (20 turns?)

 

(I sometimes also use the antenna for 80m - disconnecting part of the
horizontal leg.)

 

Tnx,

 

/Bill, K2PO

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