[TowerTalk] New tool - toroidal ferrite core inductor calculator

[Lux, Jim]

On 6/16/21 8:33 AM, jim.thom jim.thom at telus.net wrote:
> On a  side note, N3RR,  Bill Hider, a few yrs ago, bought  700  (seven
> hundred) of the type  31,  2.4 inch OD cores...from I think,  Fair
> rite..... and the tolerance between all of em  was strewn all  over the
> map,  like  +  or  -  20+ %.   Bill came up with a simple  1  turn test to
> evaluate,and then grade them into various groups.  Some time in the past,
> apparently  Fair rite  moved their production facilities to  CHINA, and
> after that, the  +/- tolerances went all to hell.


20% tolerance has been standard on magnetics for decades. And fairly 
large temperature coefficients too, like any magnetic material.

I don't know that their Chinese facility (2013) actually had much effect 
on their quality and consistency.