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Got a couple of ferrite items from Palomar Engineers.  They included a useful tip sheet on combatting RFI.  It may be useful if you have an RFI problem to beat.  Scanned copy attached. 
73
Dave, VE3WI
That pdf is very helpful, thanks Dave. Maybe I should buy from Palomar in future because all the snap on ferrites I have bought in the past do not identify the mix being used.
Well, none of the toroids, beads or snap-ons from Palomar, Amidon, MFJ, Mouser ....  etc etc, that I have bought are marked on the ferrite itself, just on the packaging.  The commonly-available ones are all made by Fair Rite I believe, who does not mark them for identification.  I got a silver permanent Sharpie at Staples (they didn't have white, but they do have gold if you prefer) to mark them with.  Ferrites are also made by Magnetics & are colour coded, but they aren't sold by the major ham vendors.

Commonly-available powdered iron toroids are made by Micrometals & are colour coded (mix 2: red, mix 6: yellow, etc).

If you have some unknown ferrites, a procedure posted on QRZ is to:
- wind some turns (e.g. 10) of magnet wire on it
- measure the inductance (helps if you have an LC meter!)
- calculate AL (mH/1000 turns): either download Mini Ring Core Calculator http://www.electronicecircuits.com/elect...or-program, or do the math by hand
- compare with AL values for various mixes (Palomar & Amidon websites) to find a match

73
Dave, VE3WI
(2021-04-16, 10:43:21)VE3WI Dave Wrote: [ -> ]Well, none of the toroids, beads or snap-ons from Palomar, Amidon, MFJ, Mouser ....  etc etc, that I have bought are marked on the ferrite itself, just on the packaging.  The commonly-available ones are all made by Fair Rite I believe, who does not mark them for identification.  I got a silver permanent Sharpie at Staples (they didn't have white, but they do have gold if you prefer) to mark them with.  Ferrites are also made by Magnetics & are colour coded, but they aren't sold by the major ham vendors.

Commonly-available powdered iron toroids are made by Micrometals & are colour coded (mix 2: red, mix 6: yellow, etc).

If you have some unknown ferrites, a procedure posted on QRZ is to:
- wind some turns (e.g. 10) of magnet wire on it
- measure the inductance (helps if you have an LC meter!)
- calculate AL (mH/1000 turns): either download Mini Ring Core Calculator http://www.electronicecircuits.com/elect...or-program, or do the math by hand
- compare with AL values for various mixes (Palomar & Amidon websites) to find a match

73
Dave, VE3WI
I do the same with my torroids to know which mix each of them are.  I do not have too many in use here, but I do have them installed on my USB cables to between my laptop and my radios as a precaution to eliminate any RFI potential. I have several of the snap ons, but have read that they do not work as well as the larger torroid rings with the proper mix.