[TowerTalk] material permeability of a BalUn core

[Jim Brown]

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The work you are reading is somewhat out of date, in that Fair-Rite's 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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