If you purchase ferrite components from most manufacturers, you’ll find that they all look pretty much alike: dark grey beads and toroids and rods without markings or other identification. This can cause problems at a later date when you don’t know what part you really have! A good solution is to put each type of part in a plastic bag and write the part number or type of mix directly on the ferrite with a permanent marker.
If you do place multiple cores in a bag or box, wrap each in a tissue or bit of plastic foam—ferrite is brittle and chips easily with very sharp edges as a result. If the component is broken through the magnetic path, the component is likely ruined due to the small air gap that will remain, even if glued tightly.
DX Engineering goes a step further by adding a colored paint stripe to their ferrite components. The table below cross-references the mix and the most common frequency range for which the parts are used. And label them anyway…
