[en] A new cylindrical mirror electrostatic spectrometer for measuring the internal conversiop electrons, emitted by radioactive sources in the 0.1-20 keV energy range with energy resolution of 0.1-1% when sources with up to 1.5 cm² area are used, is described. Tests were conducted with ⁵⁷Co and ¹⁶⁹Yb radioactive soUrces prepared by vacuum sputtering and mass separation. The spectrometer operates automatically in the oilless vacuum of 4x10^-6 Pa. Electron spectra are scanned in a cyclic way. The device background noise is of the order of 1.5 imp/min