Hello, A friend gave me an Isotemp OCXO 134-10 and the usual datasheet is available online at several sites. For example: https://blog.mayer.tv/images/isotemp_ocxo_134-10.pdf However this datasheet does not satisfies a true self proclaimed time nuts! I do not wish to disassemble it as the enclosure is entirely soldered and the unit is in very good condition. Does anyone know more hot stuff about this oscillator? in particular: -what kind of crystal is in there ? SC or AT? The design is old, so maybe AT, but my unit has datecode 0046, so maybe they upgraded the design? -is the oven a single or double oven? By comparison of the stability specs with other devices, I would tend to be conservative and not too hopeful, so I imagine an AT crystal in a single oven, but maybe it's better than that? Thanks for any detail Sebastien

  Let it cool down for a day or more. 

  Turn it on and start monitoring the frequency.

  An AT will be lower in frequency (by many 10’s of ppm) once it warms up.

  An SC will be higher in frequency (again by 10’s of ppm) once it warms up.

Hi It’s certainly a single oven. The ADEV (as per the spec) is pretty poor. That would suggest it likely is an AT cut. Best guess is that they kept making pretty much the same design for 10 years. They might have swapped out an IC or transistor that went out of production. If it started as an AT, it is highly unlikely they would have gone from a cheap (in 1992) AT to an expensive SC crystal. Quick and simply way to see what it is: Let it cool down for a day or more. Turn it on and start monitoring the frequency. An AT will be lower in frequency (by many 10’s of ppm) once it warms up. An SC will be higher in frequency (again by 10’s of ppm) once it warms up. Yes, there are a variety of other cuts it could be. More info here (and in a number of other places): https://xoprof.com/2023/09/unleashing-the-mystery-of-crystal-cuts/ That’s just the first thing Google turned up. Bob > On Sep 2, 2025, at 12:17 PM, Sebastien F4GRX via time-nuts <time-nuts@lists.febo.com> wrote: > > Hello, > > A friend gave me an Isotemp OCXO 134-10 and the usual datasheet is available online at several sites. > > For example: https://blog.mayer.tv/images/isotemp_ocxo_134-10.pdf > > However this datasheet does not satisfies a true self proclaimed time nuts! > > I do not wish to disassemble it as the enclosure is entirely soldered and the unit is in very good condition. > > Does anyone know more hot stuff about this oscillator? in particular: > > -what kind of crystal is in there ? SC or AT? The design is old, so maybe AT, but my unit has datecode 0046, so maybe they upgraded the design? > > -is the oven a single or double oven? > > By comparison of the stability specs with other devices, I would tend to be conservative and not too hopeful, so I imagine an AT crystal in a single oven, but maybe it's better than that? > > Thanks for any detail > > Sebastien > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com