Is there a particular type or size of ferrite bead or ring that should be used for cutting down RF interferance?,

                     regards, Terry

Hi Terry

I use them for long runs but don't know what spec they are so I use these and assume the guys at Robot birds know what they are doing.

Also found these from the forum sponsor.

Andy

These are actually the best, and you can have it free for the price of postage in a regular envelope, as I am completely 2.4Ghz. cant remember where I got them from now...probably RS components.

Not sure if they do these wide ones though ?

 having now googled .... it Appears they do ! 

I might be way off beam here, but.....

Ferrites are made from essentally iron filings, and the size of the filings determine the frequencies that they react to - the smaller the filing the higher the frequency.

So do we have to be select ferrites of a particulr spec?

Andy

Actually the two main types of ferrite material are manganese/zinc or nickel/zinc although there are many types. Both ferrite and iron powder toroids can be effective in suppression of breakthrough.

As Timbo implied earlier the deeper the ring the better (inductance proportional to length), thin ones can be stacked to improve effectiveness. Also several turns are necessary, around 12 being the optimum at 35mhz (if you have the room).