Precision inductors: calibration and maintenance

This paper presents three different techniques for calibrating and maintainingprecision standard inductors at metrological laboratories which employ such items of equipment that allow the precise comparison of two impedances, usually a standard and an unknown. General radio standard inductors of 100 pH, 1 mH and 10 mH were calibrated as a demonstration. As reported by the manufacturer of the selected inductors, the stability requirement, of within 0.01% per year, was achieved using these techniques.