International comparison of low voltage (0.001 V) and high voltage (100 V) in coaxial line at 30 MHz

At a frequency of 30 MHz-a commonly used intermediate frequency-two micropotentiometers have been intercompared at a voltage level of 0.001 V and in a second exercise two thermal converters at a level of 100 V. Seven national laboratories of metrology from China, Finland, the former German Democratic Republic, Hungary, the United States (U.S.A.), India, and the Federal Republic of Germany with the PTB as pilot laboratory participated in the first comparison and three of them also in the second one. In this paper, the methods for determining the RF-dc transfer differences are described and the results of the intercomparison are presented. The results proved that uncertainties between 0.002 and 0.005 can be obtained for the transfer difference at 30 MHz with the stepping-up and stepping-down procedures used to perform accurate high and low voltage measurements referred to a national RF voltage standard at 1 V