An electron discharge device has a hermetic pinch seal formed by an indium type pressure seal. A method and apparatus for the manufacture thereof are also described. The apparatus comprises a demountable vacuum system having a removable top with ports therein, in one of which is mounted the envelope of the device being manufactured and in the others of which are mounted other envelopes. A rotatable and reciprocable platform in the vacuum chamber carries an evaporator for forming a photoelectric layer in the envelope and an electron gun on a pinch for sealing into the envelope. The platform also carries a test electron gun the beam from which is scanned over the photoelectric layer to test it, and an oven for baking the lower part of the envelope of the device. The various devices mounted on the platform are raised so that they enter respective envelopes for the purpose of degassing them.