[TowerTalk] New tool - toroidal ferrite core inductor calculator

[Lux, Jim]

On 6/16/21 4:07 PM, Jim Brown wrote:
> 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.

Here's what I know...

Bill Amidon, in North Hollywood, literally in his garage (the Otsego st 
address is in a residential area), bought wholesale and repackaged for 
ham and entertainment industry use in little envelopes. He published a 
giant tissue paper datasheet that you unfolded like a map.  A fairly 
steep markup as I recall, but back then, the mfrs only sold substantial 
quantities (100s) - I think Palomar Electronics did the same sort of thing.

He sold out quite a while ago, I'm thinking the 80s - The company got 
into the magnetic recording head business (that may also have been part 
of Bill Amidon's business) and moved down into the South Bay (Torrance 
or somewhere like that) to be close to Ampex and similar suppliers. They 
grew, and then split into the "recording head" and the "ferrite 
components" businesses - the recording head business long ago collapsed 
(not just for them).  I honestly don't know why they even still sell in 
small retail quantities.  Amidon Associates was founded in 1990, and I 
think that's roughly the time of the split up.



> 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
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>