[time-nuts] AN/URQ13 reference AT cut crystal?

[paul swed]

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