Investigation of Atmospheric-Pressure Dependence of Compact Detachable Zener Module

The influence of atmospheric pressure on the DC voltage output of a prototype Zener voltage standard system has been investigated. The system is composed of a compact temperature-controlled Zener module, detachable from an expansion unit with additional battery packs. It can be used not only as a secondary standard but also as a voltage reference for more general purposes. In this study, we placed the compact Zener module in a vacuum chamber and measured its output voltage by changing the air pressure. The results indicate a pressure coefficient of $\pmb{(0.5\pm 1.2)\mathrm{nV}/\mathrm{hPa}}$ for the nominal 10 V output.