[time-nuts] EFC divider resistors

[Bob Stewart]

Any idea what the usual temperature coefficient is for the VRef output of  the OCXO?  I looked under the Trimble label of my spare and found: DOC2127 and 44/1416.  The one I have installed is probably the same.




>________________________________
> From: Bob Camp <lists at rtty.us>
>To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>Sent: Friday, January 31, 2014 6:17 PM
>Subject: Re: [time-nuts] EFC divider resistors
> 
>
>Hi
>
>A 7805 has a *rated* temperature coefficient of 2 mv / C. Most parts do way better than this. The problem is knowing if you have a good part or not. On a 5V part, your reference could be running 400 ppm/C. Since the divider has no impact on this number, it over-rides what ever you do with the divider resistors. A good voltage reference will set you back about $50 or so. 
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