[time-nuts] Crystal Ageing

[Jeffrey Pawlan]

It was Rick who wrote about crystal aging. It is not predictable whether the
crystal will go higher or go lower in frequency and there is no guarantee that
it will age at a linear rate. The worst-case is when a crystal erratically
jumps.

I had attended a conference of the Frequency Control Symposium of the IEEE in
which the causes were discussed. There was disagreement among the experts. Some
thought it was owing to the physical stress or surface imperfections caused by
grinding and lapping. Others thought it may be partially a result of the
etching. Others thought it was caused by microscopic impurities in the quartz.
Others talked about the effects of plating. Rick wrote about the
microcrystalline structural defects. Perhaps all of these contribute and it is
unpredictable how they will add together.

73,

Jeffrey Pawlan  WA6KBL