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BELL SYSTEM TECHNICAL JOURNAL 



ments made on a group of —18.5° X-cut crystals on which the coating 

 has been divided carefully with an electric stylus, the increase in the induc- 

 tance of the plates ranged from 1.4% to 2.6%. Any twinning resulting 

 from the dividing operation will also change the resonant frequency of the 

 plates. 



14.33 Soldering of Wires to Plates 



The next process, that of soldering the supporting wires to the crystal 

 plate may have considerable effect on the performance of the unit. The 

 deviations which may be introduced depend on the amount of solder used, 

 the location of the solder button with respect to the nodal line of the plate, 



30 

 20 



-10 

 -20 

 -30 

 -40 

 -50 



-20' 20° 40° 60° 80° 100" 120° 1- 



TEMPERATURE IN DECREES F 



Fig. 14.9. — Change of resonant frequency with temperature of -f 5° X-cut quartz 

 crystal plates. The curves show that when the volume of solder used for joining the 

 plates to the supporting wires is appreciable compared to the volume of the plates, the 

 frequency-temperature coefl&cient characteristic is affected by the volume of solder. 



the shape of the solder button, and the possible twinning of the plate during 

 the soldering operation. 



The amount of solder used in forming the joint of the wire to the plate 

 becomes extremely important when the plate is small. For example, Fig. 

 14.9 illustrates the changes in the frequency-temperature characteristic 

 resulting from the use of varying amounts of solder for a particular size of 

 plate. The units on which these measurements were made used X-cut 

 -1-5° plates of 16 mm x 6 mm x 0.5 mm. The types of wire referred to in 

 the figure, that is, hooked, straight and headed, were described in Chapter 

 XIIP". The frequency-temperature characteristic expected on the basis 

 of measurements made on crystal units using larger plates is approximated 



" Log. cit. 



