Measurements of the temperature dependenceof the output voltages of someZener diode based voltage standards

The author describes a test facility and procedures for determining the temperature coefficients of the 1.018 V and 10 V outputs of Fluke 732B electronic voltage standards based on temperature-regulated Zener diodes. Of the fifteen instruments studied fourteen were found to have statistically significant temperature coefficients for the 1.018 V outputs with respect to ambient temperature; values range from –39 × 10-9/°C to 41 × 10-9/°C. For the 10 V outputs, ten of the fifteen have statistically significant temperature coefficients ranging from –15 × 10-9/°C to 16 × 10-9/°C. By applying small corrections for temperature dependence, based on coefficients describing the change in output voltage as a function of the resistance of the internal thermistor, errors in calibrating and comparing these standards can be reduced.