Hi If it was made before 1981 it pretty much certainly is *not* an SC. That’s not to say it is an AT. A lot of crystal cuts got used in OCXO’s over the years.
My guess, it broke, somebody took it apart and threw away the defective crystal. It was replaced with a random unit from the junk box and the ovens were (effectively) turned off. Bob > On Feb 16, 2021, at 8:18 PM, paul swed <[email protected]> wrote: > > After a bit of research I am wondering if this odd unit was actually an > attempt at a AT cut crystal reference. The temperatures seem to line up. > Its certainly an alpha or less product. > It was stable at 43 F. > Was thinking about disconnecting the oven and bringing the leads out to > manually control the temp. With a quality external temp meter. Then see as > the temperature is adjusted, does it follow an AT cut curve. > As someone on the thread said "it maybe working as intended". > Regards > Paul > WB8TSL > > On Tue, Feb 16, 2021 at 6:17 PM paul swed <[email protected]> wrote: > >> Hello to the group still working and decoding the AN/URQ-13 reference >> oscillator. Bob had mentioned that the crystal should be at 85 C and thats >> right for a SC cut crystal. Would there be any reason that this oscillator >> is perhaps a AT cut crystal thats in the 30 C range. Just odd that the >> front meter reads in the normal temperature range and the real >> measurement is 40C. Makes no sense but they build AT cut crystals for some >> reason. >> Ehat about the smaller ovens like Piezo's. Pretty sure I can find many >> details on the Morion oscillators like the MV200. >> >> Other bits of details. >> There are 2 discreet regulators that simply produce most likely a low >> noise +/-8.5V. The Oven heaters seem to run on +15V and the divider analog >> circuits need 13V min to work. But not 15V. That seems to cause some >> distortion. >> The other circuit on the board attached to the oscillator is a buffer amp. >> It does have several meter resistors on it also. >> >> Regards >> Paul >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
