[time-nuts] My HP 5370B reads 6 nS out!

Magnus Danielson magnus at rubidium.dyndns.org
Sun Jun 14 18:01:42 EDT 2015


Peter,

On 06/13/2015 06:48 PM, Peter Reilley wrote:
> I just got a new (to me) HP 5370B and I wanted to try it out on the 1 PPS
> output
> from a Trimble Resolution T.   Using 10K samples averaging it is always
> about
> 6 or 7 nS to high.   Shouldn't this average toward zero?   If I use no
> averaging
> it bounces around within the expected range.
>
> I have done this test using the internal oscillator and an external rubidium
> frequency
> standard.   I get the about the same results in both cases.
>
> I did calibrate the OCXO in the 5370B using the rubidium standard and got it
> so
> that there is less than one cycle difference between the two over a period
> of a few
> hours.
>
> I have tried a number of GPS units with the same result.
>
> Could my rubidium oscillator be that far out?   It is a FEI model FE5680A.
>
> Am I missing something?

It is not entirely clear to me what you measure, PPS and later 10 MHz 
period time?

There can be a time-offset between the start and the stop channels.
Just adjusting the OCXO does not help for that.

Dig up the service manual and check there.

Cheers,
Magnus



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