Interlaboratory comparison of Josephson voltage standards

An interlaboratory comparison of Josephson Voltage Standards (JVS) has been made among 16 national, industrial; and military standards laboratories in North America and one in Europe. The comparison was made at 10 V using a set of four traveling Zener reference standards. A pivot laboratory made measurements at the beginning, at the end, and at nine other times during the comparison. The measured differences and their uncertainties are reported and used to establish a table of equivalence between each participant and the pivot, and between each participant and the National Institute of Standards and Technology (NIST). All but two of the differences fall within two parts in 10/sup 8/.