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MGL Avionics

EMI Interference Suppressor

Warning: Beware of ferrite suppressors sold in many electronic shops or mail order catalogs. Nearly all of them are made from Manganese-zinc or Iron powder and have zero effect at VHF frequencies (100Mhz or higher).

We only sell high quality German made Nickel-zinc (NiZn) ferrites made and optimized for operation at VHF frequencies and effective to over 1Ghz.

Ferrite beads are used to block energy at radio frequency from traveling on wires. They can be extremely effective if used correctly and are used in the following situations:


MGL Avionics has selected two particular effective ferrites. The first type shown in the above two pictures is very effective and suitable for preventative first time installation (new installations). This type is relatively low cost (around $5).

The second type is shown below and is suitable for installation onto existing wiring harnesses. This ferrite is effective despite not being molded in a single piece due to a clever "defined airgap" machined at extreme precision. This ferrite type is also suitable for experimentation as it is easily removed and placed in different locations. Cost is relatively high for this ferrite type (around $10).

Please download the document below for hints and tips related to installing ferrite beads.

EMI Ferrite bead suppressor document




Performance of the closed ferrite bead.  Dotted line is with two wire turn and solid line is with one turn. Performance of the clamp type ferrite bead.  Thick line is with one wire turn and thin line is with two turns. EFIS Accessories: Ferrites