These toroids were developed as "cable shields". The rounded edges make them very
suitable for use in preventing TVI/BCI/LFD in all sorts of equipment. This particular
ferrite mix consists of a nickel-zinc material with a permeability of 850. The internal
diameter of 19mm allows for a large amount of wire to be wound onto the core.
These cores are particularly suited for making chokes to be used with transmitting
apparatus and computers (power supplies, accessories, modems, computer peripheral
cables &c) to prevent interference. They are also very suitable for use in immunising
TVs, video recorders, stereo sets and telephone equipment. It is easy to wind six turns
of 5mm diameter 75 Ohm TV coax on one of these cores without removing the
moulded-on plug. These cores are also excellent for use in immunising telephone
systems. Because of their low profile they can be hidden away inside most telephone
Important: ALWAYS use as many turns as possible. A doubling of the number of
turns results in a quadrupling of the blocking impedance.
Outer diameter 29mm
Inside diameter: 19mm