GB723198A - Disc holding and frequency measuring fixture - Google Patents

Abstract

723,198. Electric tests. COLLINS RADIO CO. Dec. 29, 1952 [April 24, 1952], No. 32874/52. Class 37. The resonant frequency of a disc for an electromechanical filter, is measured by means of a jig which holds the disc in an arm which is rocked to a position where the disc is released to rest on a pair of parallel magneto-strictive wires. One of these is energized by a signal generator the frequency of which is adjusted to the resonant frequency of the disc when the energy imparted through the disc to the second rod is a maximum and indicated on a meter. As shown, Fig. 1, with the arm 34 in the " open " position, a knob 45 is pressed to move a shaft 42 axially inwards so that a pin 43 fixed to the shaft cams outwardly the bifurcated legs 39, 41 of a spring 37 screwed at 38 to the arm 34. A disc 41 is then inserted in a hemispherical slot 36, Fig. 2, in the arm 34 and the knob 45 pulled outwards to release the spring legs 39, 41 which grip the disc. The arm 34 is now swung over to the closed position shown in Fig. 2, and the knob 45 pressed inwards to release the disc which now drops slightly between fixed guides 21, 22 on to magneto-strictive wires 16, 19. The wire 16 is energized from a signal generator 11 through a magneto-strictive driving unit 14 secured to a support 13, and passes loosely through a support 18 and the guides 21, 22 to a further support 23 to which it is fixed. The wire 19 is fixed to the support 18 and passes loosely through the guides 21, 22 and supports 23, 24 to a magento-strictive output means 26 mounted on support 24. The energy passed from wire 16 to the wire 19 by the disc is indicated on a meter 28 connected to the output 26. The signal generator frequency is adjusted by a knob 12 to resonance, which is indicated by a maximum reading on the meter. The disc is then removed and ground until its resonance frequency has risen to the required value. The arm 34 is locked in the inward position of the knob 45, Fig. 2, by a detent 46 engaging a sleeve 44. Specification 722,664, [Group XL (b)], is referred to.