snap on ferrite K18 (ID 18,8mm)
inside diameter: 18,8mm
outer diameter: 31,5mm
Impedance Z at 5Mhc ( 1/2 winding): 58 Ohm
Impedance Z at 25Mhz ( 1/2 winding): 150 Ohm
Split Ferrites for radio interference suppression
After many customer requests, we have now also these split ferrite cores in our programm. Most ferrite clip cores available on the market have a permeability of around 700 , which limits the performance below 25 Mhc . We therefore use ferrites with a permeability of 1500 , to achieve a better low frequency performance. Nevertheless, these ferrites (except the KLF) are also over 100 Mhz still very effective. The impedances are measured with a "half" turn. Already with three turns , the values are 10 x higher.
When you use these split cores , the motto is " ONE IS NONE." If you want to gain effective suppression, you should try get three or more windings into the core. Otherwise you should use around 10 cores, when only one winding is possible. For applications where the cable can not be removed and wound , you could also use about 10 pieces of very "lean" K10 cores.
With thin cables, you should make as many windings in the core as possible. Nevertheless, the windings should be still " loose" in the core. If the pressure on the two ferrite halves is too large, they do not close correct. The magnetic flux is interrupted and the supression of the core drops down rapidly.