Try this one for the toroid Mike

http://www.electronics-tutorials.com...ansformers.htm

Cheers Bob VK2YQA


Funny - I am doing almost the same thing. Mine is based on the cebik data
(http://www.cebik.com/wbfd.html) on T2FD's that covers 80-10M. (You may
have heard that Oz limited call amateurs get HF on Jan 1...)

His calls for an 800r termination and hence a 800r feedpoint with a 16:1
balun. I have just purchased the toroid (F25 material from Neosid - about
35mm OD, 17mm thick) and am working out the winding details. Someone told
me that you work on the primary side XL being 10x the source Z (ie 500r -
about 8 turns) but I havent been able to clarify which end or whether the
middle freq was being talked about. I actually intend working through a
document on it this weekend (lack of good weather permiting)



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