[time-nuts] Brand new OCXO/TCXO reccomenations

[Mark Goldberg]

Those look pretty good compared to some I got. See attached.

I'm purchasing a small, custom frequency run and it is cheaper for me to
super select than for the manufacturer to do so. In fact, they won't set up
that kind of testing for such a low volume. I'm lucky to get them at all.
About 70-80% looked like your examples, but there were a number of
outliers. I would expect that if you buy a common frequency they would have
the process optimized.

Regards,

Mark
W7MLG

On Fri, Sep 25, 2020, 11:51 AM jimlux <jimlux at earthlink.net> wrote:

> On 9/25/20 8:55 AM, Mark Goldberg wrote:
> > Note that many (maybe all) TCXOs exhibit a hysteresis effect when the
> > temperature cycles. The stability reported on the datasheets is only
> > tested with a temperature change in one direction. Cycling temperature
> > up and down will result in more variation.  I've seen two or three
> > times the datasheet variation when cycling some TCXOs between 0 and 50
> > C and have had to super select for this. I've also seen non monotonic
> > jumps. Aging is also very significant in the first few months after
> > soldering.
> >
>
> I've attached a couple plots showing the hysteresis of two different
> TCXOs (fairly good ones) - so you can get an idea of the amount of
> variation.
>
> 10 ppm easy, 1 ppm hard.
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