Ferrite Toroids, Beads
Ferrites are made to different component formulas ( typically known as mix's ), to provide desired characteristics. There is no magic "one type fits all". Below is a table that provides a guide to some of the common mixes used in Ham Radio, and the use / frequency range over which they are most applicable. The 'mix' numbers are "Fair-Rite" brand - other manufacturers may use identical mix numbers but the product characteristics may differ.
| Mix # | EMI Suppression | Transformer | Comment |
| 31 | 1-300 MHz | 1:1 only, < 250 MHz | Ideal for antenna feedline chokes at lower HF Ham bands. OK for current baluns - not suitable for voltage baluns other than 1:1. |
| 43 | 25-300 MHz | 3-60 MHz | Generally more economic that mix 31, but suited to higher HF Ham bands when used as a common mode choke. |
| 61 | 200-2000 MHz | 1-300 MHz | Lower loss therefore useful for voltage transformers where power is transferred via magnetic flux |
| 73 | 0.1-10 MHz | < 10 MHz | Low frequency EMI suppression - good choice for SMPS noise reduction. |
| 75 | 0.15-10 MHz | 0.1-10 MHz | Good choking impedance at low frequencies - good choice for SMPS noise reduction. |
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Ferrite Core, Cylinder, Mix 75, 0.687" OD, 0.375" ID, 1.125" Length
Fair-Rite p/n 2675665702Offers high choking impedance at low frequencies.DimensionsODIDHeightmm17.49..
$2.80 Ex Tax: $2.43
Ferrite Core, Toroid, Mix 75, 1.22" OD, 0.748" ID, 0.591" H
Fair-Rite p/n 2675821502, Mix 75 toroid suitable for lower frequency EMI controlDimensionsODIDHeight..
$3.60 Ex Tax: $3.13