| 摘要 |
657,793. Crystal detectors. GENERAL ELECTRIC CO., Ltd., JAMES, E. G., and LINDELL, A. O. E. Jan. 27, 1949, No. 2343. [Class 40 (v)] A crystal contact device of the type adapted for connection to a coaxial line is suitably dimensioned to match the characteristic impedance of the line. As shown, the device is housed in a metal cylinder 1 in which are secured coaxial with the cylinder two discs 2 of insulating material which support the crystal 3 and contact wire 4 respectively. The discs are spaced by a metal collar 5, which is an easy fit in the cylinder, and are secured to the collar by synthetic resin plastic which hermetically seals the device. Each disc is provided with a central conductor 6 passing through a hole 7, the projecting portions 8 co-operating with the inner conductors of the coaxial lines, and having dimensions relative to the internal diameter of the cylinder 1 so that this portion has a characteristic impedance substantially matched to that of the lines. Similarly the diameter of the studs passing through the hole 7 in the discs is chosen having regard to the dielectric constant of the material of the discs, to match this portion to the adjoining portions of the device, and the internal diameter of collar 5 co-operating with the contact wire 4 is also arranged to provide the required characteristic impedance. In an alternative arrangement, Fig. 2 (not shown), the contact wire 4 is mounted on a metal rod passing through a hole in the stud 6 so that it may be adjusted before securing by solder. The device may be modified by making one of the discs of conducting material, the projection of the stud from this disc no longer being necessary, and connecting the coaxial line only to the other end of the cylinder. The collar may be integral with the cylinder or may be of insulating material, at least the inner surface having a metallic coating connected to the cylinder. Specification 635,690 is referred to. |
