Voltage dependence of the relative AC-DC transfer difference for HF voltage-transfer standards

The voltage dependence of the relative ac-dc difference for thermal converters and resistance mounts was examined. It is shown that the voltage dependence of the ac-dc difference for thermal converters which is not negligible above 30 MHz, can be reduced with special thermocouples. In resistance mounts the change of the input conductance is proportional to the square of the measuring voltage. A procedure to calculate the ac-dc difference variation from the dc conductance change is presented.