[TowerTalk] New tool - toroidal ferrite core inductor calculator

[Jim Brown]

On 6/16/2021 2:39 PM, Dan Maguire wrote:
> I never found an actual datasheet for Amidon type 31.  A link to a
> page showing the u'/u'' plots, not just physical dimensions, would be
> much appreciated.  Amidon has not responded to email requests.

Amidon is not a manufacturer, they are a distributor/reseller, and 
they've been selling stuff at VERY high markups (like $15 for a part 
that costs them less than $3) for years, having invented part numbers 
like 240-xx. The manufacturer of the parts identified with Fair-Rite mix 
numbers is Fair-Rite, an old line US company. Many manufacturers make 
mixes similar to their #43 and their #61. The chemical recipes for some 
of these materials is a closely guarded secret. The properties of #31 is 
quite special compared to other MnZn materials.

Many years ago there was a ham named Amidon. Long SK. Fair-Rite was 
owned by a husband and wife team, and I met them in 2004-5 at an IEEE 
EMC conference where I was presenting a paper. She was the EE, he was 
the ChemE. They retired a few years later, but last I heard, the company 
is still owned by the family. Don't know if they're still alive.

73, Jim K9YC