[time-nuts] The VE2ZAZ GPSDO
SAIDJACK at aol.com
SAIDJACK at aol.com
Sat Oct 21 02:29:35 EDT 2006
Hello Bruce,
I agree. The DAC reference is an LM7805CT regulator with 0.8mV/C (typ.)
temperature coefficient. Considering that typical Oscillators (MTI units for
example) have about +-20Hz deviation per 5V - this alone - excluding the Opamps
tempco, would lead to a temperature drift of 0.32Hz over a 50 Deg C temp
range. That's about 3.2E-08, quite a bit worse than a good surplus oscillator.
And the 7805 does not have a maximum tempco rating, so it could be 10x worse
than that...
bye,
Said
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