Abstract
An on-site comparison of the quantum Hall effect (QHE) resistance standards of the National Institute of Standards and Technology (NIST) and of the Bureau International des Poids et Mesures (BIPM) was made in April 1999. Measurements of a 100 Ω standard in terms of the conventional value of the von Klitzing constant, RK-90, agreed to 12 parts in 1010 with a relative combined standard uncertainty uc = 20 × 10-10. Measurements of 10 000 Ω/100 Ω and 100 Ω/1 Ω ratios agreed to 59 parts in 1010 with uc = 55 × 10-10 and to 38 parts in 1010 with uc = 31 × 10-10, respectively.