Some Improvements in Quartz Crystal Circuit Elements 



By F. R. LACK, G. W. WILLARD, and I. E. FAIR 



The characteristics of the F-cut quartz crystal plate are discussed. 

 It is shown that by rotating a plate about the X axis special orientations 

 are found for which the frequency spectrum is simplified, the temperature 

 coefficient of frequency is reduced practically to zero and the amount of 

 power that can be controlled without fracture of the crystal is increased. 

 These improvements are obtained without sacrificing the advantages of the 

 Y cut plate, i.e., activity and the possibility of rigid clamping in the holder. 



THERE are at the present time two types of crystal quartz plates 

 in general use as circuit elements for frequency stabilization at 

 radio frequencies, namely, the X-cut and F-cut. ^ This paper is 

 concerned with the improved characteristics of plates having radically 

 new orientations. 



In its usual form the F-cut plate is cut from the mother crystal, 

 as shown in Fig. 1. The electric field is applied along the F direction 



OPTIC AXIS 



MECHANICAL 

 AXIS 



Fig. 1 — Showing relation of Y-cut quartz crystal to the crystallographic axes. 



and for high frequencies an Xy shear vibration is utilized. 



The frequency of such a vibration is given by the expression: 



1 " Piezo-Electric Terminology," W. G. Cady, Proc. I. R. E., 1930, p. 2136. 



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