[TowerTalk] Ferrites 31 vs. 77 material

[Jim Brown]

On 10/30/2019 6:43 AM, Roger Parsons via TowerTalk wrote:
> K9YC wrote:
> 
> "Yes, but virtually all of the recommendations for #43 and #52 material are WRONG!"
> 
> Steve is sadly no longer with us and unable to defend himself. However, he had previously rigorously defended his methodology. He was very technically able in both theoretical and practical matters, and I personally trust his results.

There is nothing wrong with his methodology nor his measurements. The 
thing he missed, and that I also missed until recently, is the effect of 
component tolerances. About a year ago, I bought 40 of the #52 Fair-Rite 
cores, split into four orders over about a month from four Fair-Rite 
distributors measured the characteristics of each, and put the data in a 
spreadsheet. I then selected cores at the limits of Rs and Xs and wound 
chokes following Steve's guidelines. None of those chokes were even 
close to his published data.

My methodology is discussed in detail in
http://k9yc.com/2018Cookbook.pdf

73, Jim K9YC