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[RFI] toroid core color coding

To: <rfi@contesting.com>
Subject: [RFI] toroid core color coding
From: aa6dx at pacbell.net (Mark)
Date: Mon Mar 10 17:51:47 2003
I found this in a 5/02 message... 73, Mark  AA6DX
There is no standard color code for toroids. Each manufacturer does it his
way. The color codes for iron powder cores shown in the ARRL handbook are
for cores made by Micrometals. These are readily available to hams through
Amidon and Palomar. The ferrite core numbers listed are for cores made by
Fair-Rite Corp, also sold by Amidon & Palomar. All Fair-Rite cores are
plain black, no coding. The numbers refer to the ferrite material. 73 has
been discontinued and replaced by 77. Over the years they improve some of
the materials and give the improved version a new number. This info does
not always get to writers of construction articles so you see call-outs of
obsolete materials. The new materials  work as exact substitutes. -- Jack,
K6NY, Palomar Engineers

================================================----- Original Message -----
From: "Pete Smith" <n4zr@contesting.com>
To: <rfi@contesting.com>
Sent: Monday, March 10, 2003 1:04 PM
Subject: [RFI] toroid core color coding

> I just pulled 4 toroid cores out of a defunct surplus computer power
> (110v in, 5 and 12 volts out).  The cores are 1" to 1.375" OD, and a
> under .5 inches high.  One is solid yellow, two are green on the outside
> and yellow on the sides, while one is yellow on the outside and white on
> the sides.  Is there an industry standard anywhere on these color codes
> that anyone can point me to?  I think I saw an e-mail on this a few years
> ago but can't find it now.
> Otherwise, can someone who knows more about such supplies opine as to what
> frequency range they are likely good for?  One was bifilar wound with
> ~#24-26 twisted pair, while the others are single windings of 1-2 layers
> enameled wire.  The latter are the ones that are green with yellow sides,
> while the bifilar winding was all-yellow.
> 73, Pete N4ZR
> The World HF Contest Station Database was updated 23 Feb 03.

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