On Wed, Mar 13, 2019 at 9:02 AM jimlux <[email protected]> wrote: > If I go out and buy 100 TCXOs with a spec of, say, 50 ppm, what does the > distribution of the initial frequencies (and, I suppose, the frequencies > after aging) look like. > > If you are buying 1000, you probably will get the manufacturer to test to meet your specs. At 100, you will likely get what you get from them. I am buying VCTCXOs 50 at a time and they have quite a variation. Basically they meet spec for temperature variation, but many just barely meet spec. They typically are 1-2 ppm off before adjusting them on frequency and drift 1-2 ppm in the weeks after soldering too. After that, maybe 1 ppm per year. This is only one example of one manufacturer in a custom frequency for me. If you buy a standard frequency, you will likely get the benefit of better manufacturing control they can afford for high volume parts. I am buying parts specified at +/- .28 ppm over 0 to 70 degrees and they just meet that, but the frequency is anywhere at any temperature. It is often not a linear function.
I've also seen hysteresis, frequency jumps, etc, with only about 80% of the parts acceptable to me. Those effects are not considered or tested by the manufacturer at this low volume, so I have to do the temperature testing and cull the unacceptable ones. You will probably have to do the same, age and test yourself to get acceptable results. Regards, Mark _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
