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

[Bob kb8tq]

Hi

The temperature of the crystal is driven by the oven design. AT / SC / BT / IT
or whatever …. it is going to be over 80C. It’s not a function of the crystal. It
is what the physics of the oven force you to do. Inner oven *must* be hotter 
than outer oven. Outer oven *must* be hotter than the maximum ambient of 
50C. 

Bob

> On Feb 16, 2021, at 6:17 PM, paul swed <paulswedb at gmail.com> 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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