On Mon, Feb 14, 2011 at 7:47 PM, Shawn Tayler <[email protected]> wrote: > > My question is what is the process in the aging if the crystals that causes > this drop in frequency? I understand it may be mechanical but the level if > vibration the radios are exposed to varies greatly and there does not seem to > be a correlation with the frequency shift we are seeing.
All crystals change frequency as they age. Some of this is that the crystal absorbs mass as gas is defused into the structure or looses mass by outgassing or the mounting metal defuses into the outer layer or the metal oxidized. All these are chemical changes I've also read about microscopic cracks or defects in the crystal can grow over time In a radio the oscillator also has other components like caps and resistor that can age. Most crystal oscillators that you buy come with a spec for aging and also an adjustment and I find the engineers have build maybe only a 20 year worst case life into the adjustment range -- ===== Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
