Improvements in electric rectifiers

摘要

572,511. Detectors. GENERAL ELECTRIC CO., Ltd., BRITTAIN, F. H., and RANSLEY, C. E. Nov. 5, 1941, No. 14267. [Class 40 (v)] [Also in Group II] A crystal detector is assembled by the following method. A crystal is fixed in one end cap of an insulating tube, a second cap carrying the contact device being then attached to the other end of the tube. The contact is adjusted and then fixed in position, and the assembly sealed. The ends 6 of the insulating tube 5, Figs. 4, 6, are coated internally with metal, and it is then attached with fusible alloy to the brass cap 7 standing on the hotplate 12, Fig. 4. The crystal 1 is attached with adhesive 4 to the end of a rod 2, and its exposed surfaces coated with a metallic layer; it is then introduced on the rod 2 into the molten alloy 11 contained in a depression 10 in the cap 7. The hot-plate 12-is rapidly cooled, and when the alloy 11 has set, the rod 2 is detached and removed. The face of the crystal thus exposed is polished. This assembly is now attached to a second cap 13, Fig. 6, which supports a movable rod 16 carrying the whisker contact 17 welded to its upper end. The cap 13 stands on a hot-plate 19, and the open end of the tube 5 fits into a groove 15 containing fusible alloy. The assembly is connected into an electrical testing circuit, the rod 16 adjusted for satisfactory performance, and the hot-plate 19 then rapidly cooled. The rod 16 is held in position by alloy 20 which has overflowed from the groove 15. Finally, the assembly may be filled with wax, through a hole 21 in the tube 5, using a vacuum process. A modification is described using a crystal with plane faces, in which case it may be attached directly to the top of the cap 7 before the tube 5 is attached. The process for coating the crystal 1 with copper is described, and consists in dipping it in a solution of cuprous oxide in hydrofluoric acid. Coating of the insulating tube is performed either by using a proprietory solution, or by reduction of deposited cuprous oxide in hydrogen, or by placing an annulus of copper within the tube and heating.