[time-nuts] Linear voltage regulator hints...

Bob Camp kb8tq at n1k.org
Tue Dec 9 19:14:18 EST 2014


Hi

> On Dec 9, 2014, at 6:57 PM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
> 
> 
> 
> On 12/9/2014 3:02 PM, Bob Camp wrote:
> Here's an overnight ADEV plot against the new Cs of where we are in the project.  Red is ADEV.  Green is the TIC.  Blue is the output of the GPSDO to Channel A and the Cs to Channel B of my 5335A measuring TI, using the 1PPS from my GPSDO to trigger the external gate.  I see that the Cs phase has drifted down slightly vs my GPSDOe.  I wonder if this is an indication of a calibration problem with the Cs or some subtle issue on my board?
>> 
>> Looks perfectly normal to me. Your Cs is sensitive to magnetic field. Have you “zeroed” it out? No of course not, nobody does. (almost nobody …).
>> 
>> Bob
> 
> This reminds me of the great CBT demagnetizer debate at HP.
> Even Len Cutler didn't think this was necessary, at least
> in the 5071, and possibly the 5061.  When Len says something
> is overkill, you can be sure of it.  Anyway, we still had
> to support a CBT demagnetizer for customers who wanted it.
> The customer (with money to spend) is always right.  The
> 5071 measures the C-field with a Zeeman line measurement
> and adjusts it if necessary.

… and it seems to do *something* roughly every 24 hours …. That might include “react to the heating turning off in the building ..”.

Bob

> 
> Rick Karlquist N6RK
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