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Re: [TowerTalk] New tool - toroidal ferrite core inductor calculator

To: towertalk@contesting.com
Subject: Re: [TowerTalk] New tool - toroidal ferrite core inductor calculator
From: Wes <wes_n7ws@triconet.org>
Date: Thu, 17 Jun 2021 09:41:52 -0700
List-post: <mailto:towertalk@contesting.com>
In 1980 I was traveling a week at a time from Tucson to Conoga Park on business.

Working on some personal project I needed some toroids and I actually visited Amidon's garage while I was in the neighborhood, so to speak. He for sure was marking up prices, but as Jim Lux says, he was doing a service, selling small quantities that manufactures weren't about to sell.
Wes  N7WS


On 6/16/2021 6:23 PM, Lux, Jim wrote:
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.
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