EUROMET Project 432: Frequency performance of 12 906 ? and 6453 ? reference resistors for ac quantum Hall effect experiments

The Czech Technical University (CTU), acting as pilot laboratory in an international comparison, has fabricated and provided as transfer standards four terminal-pair thermostatted travelling resistance standards with nominal values of 12906 Ω and 6453 Ω. Vishay S 102 K resistors form the resistive elements of these standards and 100 Ω platinum resistance thermometers make it possible to monitor their inner temperature. The laboratories participating in the comparison (five in Europe and one in Canada) were requested to measure the frequency dependences and time constants of the travelling standards by comparing them with resistors with calculable frequency performance. Calculable resistors of several different designs (monofilar, bifilar, quadrifilar and octofilar) were available. For both travelling standards, the ac-dc differences of the parallel equivalent resistance, as reported by the different laboratories, are within 13 parts in 108 at 500 Hz and 70 parts in 108 at 5000 Hz. The reported time constants differ by less than 3.9 ns and 4.8 ns, respectively.