INTRODUCTION AND SCOPE

This document has been compiled in response to a generally expressed desire on the part of both users and manufacturers for a guide to the use of quartz crystal units for frequency control so that they may be used to their best advantage. The most common error has been the assumption on the part of some users that the crystal unit is an absolute frequency-determining device. This idea has persisted, probably due to the fact that the frequency tolerances in earlier equipment were sufficiently wide that frequency variation imposed by the associated circuit conditions were small enough to be ignored.

It is not the function of this brief document to explain theory nor to attempt to cover all the eventualities which may arise in practical circumstances. It does draw attention to some of the more fundamental questions which should be considered by the user of quartz crystal units for new applications. Such a procedure will reduce considerably the user's risk of unsatisfactory performance.