Fabrication of a standard two-stage autotransformer at LNE

The comparison of electrical quantities expressed in units of the international system of units and the same quantities generated from quantum effects is a direct way of determining physical constants. The determination of the quantum of resistance R
K
from a calculable capacitor is part of this process. In such an experiment, various impedance bridges are used whose main part is a two-stage transformer. We describe in this paper a new two-stage autotransformer currently built and characterized at LNE.