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

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@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 > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com >