FIG. 1 is a top, front and right side perspective view of a portion of a frequency changer showing my new design,

FIG. 2 is a front elevational view thereof,

FIG. 3 is a top plan view thereof,

FIG. 4 is a bottom plan view thereof,

FIG. 5 is a left side elevational view thereof,

FIG. 6 is a right side elevational view thereof; and,

FIG. 7 is a reference view showing the article in use thereof.

The broken line showing of the remainder of the frequency changer is for illustrative purposes only and forms no part of the claimed design. Also, the broken line showing of reference environment in FIG. 7 is for illustrative purposes only and forms no part of the claimed design.