92 



BELL SYSTEM TECHNICAL JOURNAL 



55° 60° 65° 70° 75° 80° 85° 90° 95° 100° 105° 110° 115° 120° 125° 

 VALUE OF T IN DEGREES 



Fig. 13 — Contour map of zero temperature coefficient low-frequency 

 shear crystals with three rotations. 



30 



-, 20 



10 



■10 



-20 



-30 



-40 



-50 



,^ 



7 



/ 



/ 



/ /dou< 



z/ 



V 



^^ 



/doughnut 



^ 



^ 



LONG BAR, LENGTH 

 ~ ALONG X AXIS 

 ■I ST HARMONIC 

 / ^2 ND HARMONIC 



fif 



V 



\ 



^^^ 



/: 



^ 



■^ 



'% 



k 



x^-^^ 



vA. 



yM 



\ 



Ot\ 



^ 



V 



^ 



V 



^: 



-T 



V 



Ft 



10 20 30 40 50 60 70 80 90 100 110 



TEMPERATURE IN DEGREES CENTIGRADE 



Fig. 14 — Frequency temperature relations for zero temperature coefficient crystals 



