Is There a Best Method to Suppress RFI from Small Engine Ignition?

Increased demand for reduced electromagnetic radiation from small engine operation has necessitated an evaluation of the effectiveness of various suppression methods available to the engine manufacturer or end-user. This investigation studied the effectiveness of different suppressors in spark plugs, spark plug boots, shielded connectors, and ignition leads. Suppression from resistance, inductive resistance, and shielding were evaluated. This work was undertaken on “breadboarded” ignition systems of the battery coil inductive, magneto, and capacitor discharge types. Results from these were then compared to actual spark ignited engines mounted in lawnmowers, snowmobiles, chain saws, and a motorcycle.