very largely compensated for by the virtually pressure independent inductance that is achieved after encapsulation or potting with plastic the inductance changes then amount to only 3 to 4 depending on the degree of purity of the raw materials the permeability values which can be achieved at room temperature are then approximately 3000 to 7000 upon making a comparison of the diagrams according to fig1 and 2 which respectively show the profile of the initial permeability u03bci as a function of the temperature t in u00b0 c it is apparent that in the case of mnzn ferrite having a secondary permeability maximum abbreviated as spm at a temperature lt 0 u00b0 c compared to such a ferrite having a secondary permeability maximum at a temperature gt 0 u00b0 c virtually unchanged inductance values are retained under the effect of mechanical pressure in a temperature range of interest in terms of applications from approximately room temperature to 130 u00b0 c under the effect of mechanical pressure due to potting or encapsulation with plastic in fig1 and 2 the profile of the initial permeability u03bci before and after encapsulation or potting is indicated by reference numerals 10 and 11 in fig1 and by reference numerals.