Kostas,
The work you are reading is somewhat out of date, in that Fair-Rite's
#31 material did not exist when Jerry was working, and initial
permeability is not a useful parameter when understanding common mode
chokes that are useful at HF. What matters, for CHOKES, is their
resonance and a high value of resistance at resonance.
I suggest that you STUDY my work at k9yc.com/publish.htm. The Ham's
Guide is a tutorial on RFI and how chokes work, and the applications
note on Transmitting Chokes for160-1M are what you need to study.
73, Jim K9YC
On 6/14/2021 10:39 AM, Kostas SV1DPI wrote:
I am reading the book "Understanding, Building, and Using Baluns and Ununs"
In the page 37 refers to 1:1 baluns. So it recommends that the core of a
Reisert balun (current balun) should have a permeability of 250 (160m)
or 125 (80 to 10m) or 40 (20-10m) for maximum efficiency. I have seen in
several articles that some guys make their baluns using mix 31 ferrites
(2631803802 has 1500) or ft240-43 (permeability=800). As I can
understand a higher permeability means a better chock or not? According
the book I gain efficiency with lower permeability but what I loose?
Have something changed after the book is written or not? Comments please...
73 Kostas SV1DPI
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