GB578840A - Improvements in or relating to means for tuning hollow resonators - Google Patents

Abstract

578,840. Coilless resonators. HOLMAN, H. E., and BARFORD, N. C. April 15, 1942, No. 5005. [Class 40 (iii)] An electrical resonator is tuned by differential screw mechanism which deforms the resonator. The invention is described with reference to a resonator employed in an electron discharge tube, but is applicable to other resonators. In the form shown in Fig. 1, the resonator comprises thin copper discs 3, 4 sealed into and extending outside the discharge tube 1, the external portions, which are clamped to a support 15, being formed with annular parts approaching each other to provide localised capacity which is changed by deformation of the upper disc 4. The annular part of the lower disc is reinforced by a ring 11. The annular part of the upper disc is engaged by ring 8 connected by links 9 to a disc 10 threaded to receive a screwed portion 18 of an adjusting spindle, the upper portion of the spindle being screw-threaded at 12 to engage a sleeve 13 which is also screw-threaded in the cap 14 of support 15. If sleeve 13 is held by disc 20 and knob 17 operated to turn the spindle, disc 10 is 'moved axially a distance of .0005" for one revolution of the spindle if the upper and lower threads on the spindle have pitches of .03125" and .03175" respectively. If the disc 20 is rotated through one revolution and the external pitch of the sleeve 13 is .025", disc 10 is moved .00625" if knob 17 is held or .00675" if spindle 12 turns with the sleeve. Knob 17 and disc 20 provide fine and relatively coarse adjustment, it being substantially immaterial whether knob 17 is held or not for the coarse adjustment. Back-lash is avoided by spring 19. In Fig. 2, employing the same type of resonator, the annular part of the upper disc carries an upstanding ring 30 secured to a further ring 31 connected by three lugs 32 to another ring 33 which is adjustably secured at diametrically opposite points by screws 34, for initial adjustment, to a plate 25 surrounding the tube 1. The plate 25 is carried at one side on pillars 26 and is reduced at 29 to provide pivotal action, whereas its other side is forked and engaged by lugs 23 on each side of a nut 22 carried on a screwed adjusting spindle 21 which also screws on to a fixed screw 36 of different pitch.