Disclosed is an electron beam evaporator for installation in a vacuum apparatus which provides for variable positioning during or between applications of a coating. The apparatus has a carrier plate which is a flat hollow body, the top cover plate of which supports the evaporator. The hollow body is disposed over the bore in the tank such that it can be turned about the main axis of the bore. The component assemblies of the electron beam evaporator are vacuum-tight on the cover plate and the connecting lines are carried through the interior of the hollow body to the component assemblies.