[time-nuts] getting a grip on 10811 drift (trying to read my instruments)

Charles P. Steinmetz charles_steinmetz at lavabit.com
Thu Nov 15 21:49:13 UTC 2012


Chris wrote:

>If I read this correctly, I'm looking at
>9,999,999.97  Hz ?

Correct -- the small digit to the right is the exponent.  As others 
have mentioned, by holding the UP arrow key in for about 3 seconds, 
the 1992 will switch to a 10-second gate and give you one more digit 
of resolution, but you don't need that for this job.  BTW, the manual 
for the 1992 is pretty widely available on the web.

>My EFC mapping looks like this (this was done before
>I adjusted the coarse control)
>
>-4.94 VDC         9,999,999.95
>      *     *     *
>  0 VDC      9,999,999.93
>      *     *     *
>+4.90 VDC           9,999,999.90

How and where are you measuring the EFC voltage?  Are you sure the 
voltage on the EFC pin of the 10811 (Pin 6) was the same as you 
measured?  Was the EFC return pin (Pin 5) connected to the oscillator 
supply return (Pin 4)?  If it is left floating, the EFC will not work properly.

Best regards,

Charles











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