Abstract: During the manufacture of an electron tube having a radiation-sensitive layer, several components of the tube are subjected to a treatment in auxiliary evacuated containers which are sealed hermetically temporarily by means of interchangeable closing members. The auxiliary containers are accommodated in a common container which comprises means which can be controlled from outside to open and close the auxiliary containers accommodated therein. After evacuating the common container the auxiliary containers are opened and the tube is assembled and sealed finally by means of one of the closing members while using a seal consisting of a gallium-containing material in the liquid state. Finally the vacuum in the common container is broken and the finished tube is removed.