MANUFACTURE OF QUARTZ CRYSTAL FILTERS 



529 



Fig. 12 — Filter testing area. The standard-lrequeiicy uuileib art- st-fii 

 above the test sets. 



of each filter section is brought to a peak at a specified frequency. The 

 filter is placed in a test shield simulating its final container. Voltage 

 from a precision oscillator is applied to the input terminals of the 

 section and the voltage at the output terminals is measured with a 

 sensitive detector preceded by a variable attenuator. The condensers 

 designated Ctl in Fig. 13 are adjusted with a non-metallic tool until 

 the loss reaches a peak of 50 to 70 db. Each section contributes two 

 such peaks. 



Ctl 



Ctl 



onM^ 



ckOQO/ 



Ctl Ctl 



Fig. 13 — Schematic of crystal channel filter. 



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nM^ 



