[time-nuts] getting a grip on 10811 drift (beginner-ish question)

Charles P. Steinmetz charles_steinmetz at lavabit.com
Fri Nov 9 23:43:27 UTC 2012


Chris wrote:

>My perpetually drifting 10811 pretty quickly made it to the negative 
>voltage rail on the control voltage.

Is this an oscillator you just powered up after it had been off for a 
long time?  The most common versions of the 0811 are specified for 
drift of less than 5 x 10e-10 per day after they have been on for a 
month.  IME, they usually meet that spec within a week of being 
turned on, even if they have been off for a long time.  Mine run from 
about 2 e-11 to 2 e-10 per day (note that they are on continuously).

>I put in a 1/4 watt 50 ohm resistor (like the parts list called 
>for).  My working hypothesis is that the small resistor was changing 
>impedance due to heat.

The 10811 output is specified as 0.6 Vrms max into 50 ohms, or 7.2 
mW.  I doubt that heating-induced resistance change was a significant 
problem.  But no harm changing it.

Best regards,

Charles







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