This may be the wrong section (gas engines) for a question like this. You might get more response in the radio section.

I don't know of anyone using emi suppression ferrite beads. I have 6 gasoline engine powered airplanes and they are all flying on PPM (commonly known as FM) radios. I do not have the slightest hint of radio interference. This comes about by using well established techniques for preventing radio interference and good equipment. No chokes, noise traps, or opto isolators are used.

Sorry that I didn't answer your question. Maybe someone else can.

Ken