[time-nuts] Thermal impact on OCXO

David davidwhess at gmail.com
Fri Nov 18 04:30:23 EST 2016

I have only heard of and never observed the problem of manufacturers
cutting the middle out of a gaussian distribution for tighter
tolerance parts.

Robert Pease of National Semiconductor had an even better story:

I recollect the story of one of the pioneering transistor companies,
back in the '60s.  They had agreed to ship to their customers
transistors with an AQL (Acceptable Quality Level) of 2%, which was
pretty good for those days.  So the tester would test 98 good parts
and put them in the box.  Then, following her instructions, she would
add 2 bad transistors to finish off the box, thus bringing the quality
to the exact level desired.  This went on for some time, until one of
the customers got suspicious, because the two bad transistors were
always in the same corner of the box! Then things were changed ...

On Thu, 17 Nov 2016 10:34:06 -0500, you wrote:

>I once herd a story from once upon a time that, if you bought a 10%
>resistor, what you ended up with is something like this in the figure
>Of course 1% percent resistors (EIA96) are manufactured in high yield
>today, but I would guess some of this still applies to OCXOs, you
>aren't likely to find a gem in the D grade parts. After pre-aging for
>a couple of weeks they are either binned, labeled D, or the ones that
>show promise are left to age some more before being tested to C grade,
>etc, etc.

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