198 



BELL SYSTEM TECHNICAL JOURNAL 



changing the angle of cut and the ratio of axes simultaneously. To go from 

 — 25°C. to +75°C. with a mid-range at 25°C., a crystal cut at 51°-7.5' 



O .85 



.80 



.70 





90 



30 O 30 



ANGLE OF CUT IN DEGREES 



90 



Fig. 1.16. — Relation between angle of cut and ratio of width to length for zero tem- 

 perature coefficient for G type crystals 



-80^ 



10 



20 30. 40 50 60 70 



TEMPERATURE IN DEGREES CENTIGRADE 



Fig. 1.17 — Temperature frequency relations for various angles for G type crystals 



with a ratio of axes of 0.859 is required. The GT crystal has been used 

 quite extensively in frequency and time standards and in filters meeting 

 rigid phase requirements. 



