Using 10 V Josephson voltage standards to estimate the uncertainty of Zener voltage references as traveling standards

In anticipation of a European comparison of 10 V Josephson array voltage standards (EUROMET project 429 led by the NMi VSL), the BIPM and the BNM-LCIE Josephson standards have been compared by means of Zener traveling references. A mean difference of 5 parts in 10/sup 9/ has been found with a standard uncertainty of 6 parts in 10/sup 9/. The results show that the performance of the Zener references could be the main cause of uncertainty in such a comparison.