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

[Magnus Danielson]

Hi Paul,

As we have discussed a small eternity ago, the heat-up of the oscillator
gives a pretty good clue of what sits there. This is just from the fact
that the cold room temperature oscillator will shift very differently
from it's heated temperature by the oven and just observing which range
you can figure out what cut you most likely have.

I have a habbit to look at that heat-up and noted they where different.
Looking at charts for AT, BT, IT and SC cuts we could estimate frequency
offset for room temperature and those spoke to confirm. Naturally, this
was ovenized. TCXOs do not do the same thing as they are compensated,
and most generally AT cut as far as I know.

Cheers,
Magnus

On 2021-02-17 00:17, paul swed 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
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