[time-nuts] Re: Bob warned me......

[Jorge Gomez]

 Is the applied Vtune voltage  clean?
tin order o do a "sanity" test I would just apply a 1.5v battery

On Tue, May 24, 2022 at 11:55 AM Erik Kaashoek via time-nuts <
time-nuts at lists.febo.com> wrote:

> Yes, Bob did warn me but I decided to try anyway.
> I measured the ADEV of a cheap VC-TCXO in the past starting starting
> with a tau of 1 second and the ADEV nicely started around 1e-10, well
> within the required spec. But there was a hint there where some
> stability issues depending on the Vtune so I measured the ADEV starting
> at much smaller tau (starting at 50ms) and the relation with the Vtune.
> The results where remarkable, to say the least and, can be seen using
> this link: http://athome.kaashoek.com/time-nuts/TCXO%20Vtune.png
> Ignore the rise of the ADEV with larger tau as the very large capacitors
> used to get rid of any ripple or noise where still (dis)charging
> As long as the Vtune was below 0.5 Volt the ADEV at tau=50 ms measured
> about 1.5e-10 (yes, I confirmed using a very stable OCXO that the used
> frequency meter can measure the ADEV with this resolution and short tau)
> But as soon as the Vtune got above 0.5 Volt the ADEV at 50 ms started to
> rise and at Vtune of 1.5 Volt the ADEV was 3e-9
> Looking at the frequency deviation there clearly is some repetitive
> active switching in the TCXO, no clue what.
> Now I need to find a cheap TCXO that behaves a bit better, although, the
> ADEV at tau of 1 s was still well within my target spec but one can hope
> to find something better
>
>
>
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