GB656645A - Electron discharge device construction - Google Patents

Abstract

656,645. Thermionic valves. STANDARD TELEPHONES & CABLES, Ltd. March 19, 1948, No. 8228. Convention date, March 20, 1947. [Class 39 (i)] An electron discharge device comprises a vitreous bulb 2 having an anode retainer sleeve 15 sealed to one end, a tubular anode 1 telescoped into and sealed to the sleeve, a grid 3 and cathode 4 in the anode and coaxial with it, a flattened metal ring 13 sealed in the wall of the bulb, means for attaching the grid to' the ring, and lead-in conductors 6 sealed in the other end of the bulb and extending through the ring to the cathode. The grid is preferably flared at one end and may have a collar attached which may be joined to a flange on a sheet-metal cone 12 which may be integral with the ring 13. The ring 13 may have one or more annular bosses 14 to stiffen the support and yet allow radial expansion to relieve strains on the glass. The anode preferably extends beyond the seal between the retaining sleeve 15 and the bulb to protect it from electron bombardment. In manufacture the assembly except for the electrodes themselves may be mounted on a jig, Fig. 2 (not shown), whilst the two bulb portions and the ring 13 are being sealed together. The cathode is then attached to its lead wires, the grid to the cone 12, and the anode is put inside its retaining sleeve; the brazing rings 16 are heated to seal the anode to the sleeve. The same assembly may thus be used for electrodes of different sizes.