Precise comparator for checking of group inductance standard

A comparator for the intercomparison of a group inductance standards is described. It enables the independent measurement of inductance- and serial-resistance-differences of two inductance standards. Measurement ranges are /spl plusmn/10 /spl mu/H and /spl plusmn/200 m/spl Omega/ with resolutions of /spl plusmn/1 nH resp. /spl plusmn/20 /spl mu//spl Omega/. The comparator enables an intercomparison of GR 1482-H inductance standards at f=1 kHz. The uncertainties of the measured differences are smaller than /spl plusmn/10 nH and /spl plusmn/0.2 m/spl Omega/. The uncertainties are approximately 30 times smaller than the observed one-year drift of the inductances in the group.