[time-nuts] OCXO retrace, how long is reasonable?

[Bob kb8tq]

Hi

The gotcha with all this is the temperature coefficient. If they all have
roughly the same +100 ppm / C tempco (which they might), then the typical
lab temperature swing of 2 to 4 C will have them out in the 200 to 400 ppm 
range (and more or less tracking each other ….). 

1 LSB on a 16 bit part is 15 ppm. Again relative to the reference involved. On a
typical GPSDO, this *probably* is 5V (but maybe not …. ). We are chasing something 
in the 5 to 10 LSB range. Even if the two “full scales” line up, the reference in the
$5 meter is likey to get in the way. 

Better to spend $100  on a HP 3456 …..

Bob

> On Sep 5, 2020, at 3:33 PM, Perry Sandeen via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Learned members,
> Wrote: 
> Well, I could measure the EFC voltage every other day and if it'schanging, then it's the OCXO that’s drifting, if not (or not inaccordance to the DAC graph) it's the DAC itself.
> 
> One can buy 5 digit LED meters on ebay for $5 each +shipping.
> 
>  While I wouldn't necessarily trust their accuracy, at that price one could buy 3 or 4 and continuously measure  several variables.
> Regards,
> Perrier
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