Kit wrote:
From my (past) CATV experience, ferrite-based devices don't introduce "noise" as such but they can certainly pick up noise (or transmit) unless they are toroidal or otherwise well screened.
Ferrites do create noise. The permeability of ferrites is a complex quantity, so it has a real part. This real part, like any resistance, generates thermal noise. It is sometimes referred to as "secondary permeability" (as opposed to the "initial permeability"), and typically rises rapidly above some frequency (the initial permeability often falls off starting at about this frequency, as well). That transition is where the ferrite turns from a good transformer core to a good RF suppression core.
A separate phenomenon, magnetic hysteresis, also causes losses in ferrites that produce noise when the magnetic field changes.
Best regards, Charles _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
