[time-nuts] 5370A vs 5370B

[Bob Camp]

Hi

Ok, I got enough time to play a bit more with the 5370B today. Here's what I found (all running on the internal standard):

If I take the gate time out to 1 second, the frequency display reads as it should. 

If I look at the standard deviation on various samples of period I get some interesting data:

With the instrument cold,  I get some amazingly low (like 4 ps) standard deviations on 10K and 100K sample sets.

With it cold I get 15-30 ps on 100 and 1K sample sets. 

Once things heat up I get numbers in the 20-30 ps for all sample sets. 

I'm guessing that means that nothing's major broke, but I still might find regulator that needs replacement. 

Bob


On Mar 10, 2010, at 7:48 AM, Magnus Danielson wrote:

> Bob Camp wrote:
>> Hi
>> Yes indeed, the period was measured with the two channels in the com mode and the reference
>> into one of them. I hadn't considered the trigger offset issues and was expecting something
>> sub-100 ps rather than 500 ps. Obviously I need to spend some "quality time" with this beast.
>> Now I gotta figure out how to change the gate time :}......
> 
> If you do not fiddle with trigger levels, you _will_ loose accuracy. It is a systematic error.
> 
>> It sounds like my oscillator buffer board is going to get butchered pretty soon. 
> 
> I hope you mean modified. Applying a short at the right point improves the situation, but you don't need that to get started. It is a refinement that could wait for a little while.
> 
> Cheers,
> Magnus
> 
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