Hardness assurance in quartz crystal resonators

Methods are discussed for hardness assurance qualification screens for quartz crystal resonant devices. Verifying that the quartz bar has been properly swept and ensuring device traceability to that bar may be adequate for filter applications and some oscillators. For precision resonators, the radiation testing of each resonator is the only known way to be certain that a defective resonator was not obtained. Recommendations for particular tests are given.