Patent GB-622995-A (GB)
Title: Improvements in or relating to electron discharge apparatus
IPC: H01J25/24
Filed: 1945-02-13
Abstract: 622,995. Velocity-modulated tubes. SPERRY GYROSCOPE CO., Inc. Feb. 13, 1945, Nos. 3631, 3632, 3633 and 3634. Convention dates, Jan. 22, 1944, Jan. 24, 1944, March 14, 1944 and March 14, 1944. [Class 39 (i)] [Also in Groups XL (b) and XL (c)] A cavity resonator, for example in a reflex klystron, is tuned by a pair of longitudinally-extensible thermal elements which are selectively energizable for relative movement of resonator wall portions to vary the resonator frequency in opposite directions in response to expansion of the elements. Rapid variations of tuning in both directions are obtainable without relying on the cooling of a heated element. In one form, two straight filaments are employed, one of which on expansion allows springs to move the resonator grids closer together, while the second on expansion allows stronger springs to raise a flexible platform carrying one end of the first filament, thus moving the grids further apart. The filaments may be replaced by rigid rods, the springs being then unnecessary. The wires may be differentially heated by a manuallyadjustable potentiometer circuit or by a pushpull valve circuit fed from the output of a frequency discriminator (see Group XL (c)). In another form, upper grid 127, Fig. 4, is movable by wires 148, 149, which rock flange 117 about fulcrum 131. Expansion of wire 149 allows spring 151 to pull the flange down against weaker spring 129, while expansion of wire 148 allows spring 129 to move the flange upwardly. The wires are insulated by a bead 146 and are held by a tube 134 carried by fixed flange 116. A lever 144 alters the position of wire 149 for initial setting and lock nut 137 allows the tension of spring 151 to be adjusted. In another form one V-shaped pair of wires or strips 342, Fig. 7, is connected at one end to movable platform 335 carrying the upper grid and at the other end to a spring-mounted bead 345; a second similar pair 353 is connected at one end to fixed platform 321 and at the other end to bead 345. Expansion of wires 342 causes platform 335 to move downwardly under the action of springs 393, while expansion of wires 353 allows spring 346 to move bead 345 upwardly and, through wires 342, to move platform 335 upwardly, overcoming springs 393. Spring 346 is anchored in a beam 385 carried by two pillars 322 which also support platform 321. Springs 393 may be replaced by spring levers acting on platform 335 from above. In a form which allows the initial setting of the elements to be adjusted from the outside, the wires 398, 401, Fig. 16, are carried by rods 399, 402 from an insulating bead 345<1> which can be moved by screw-head 408 acting through flexible wall portion 404. Wire 401 on expansion moves platform 391 downwardly under spring 393, while wire 398 on expansion moves the platform up through rod 397 and spring 395. In a form employing V-shaped wires a similar initial setting adjustment may act on the lower grid only, while the thermal adjustments act on the upper grid. In a further modification, two pairs of parallel wires act one upon the upper grid and one upon the lower grid, initial adjustment being upon the upper grid. Specifications 14591/41, as open to inspection under Sect. 91, and 535,767 are referred to.