[time-nuts] Man with too many clocks.

Peter Reilley preilley_454 at comcast.net
Fri Nov 4 21:01:36 EDT 2016

It is a FE-5680B.   It is my understanding that these were made in many 
of features but that what features were present or absent could not be known
from the model numbers of other external identifying information. This one
has the 1 PPS apparently.


On 11/4/2016 1:07 PM, EB4APL wrote:
> A bit OT, but regarding your Rb, some units needs to be powered thru 2 
> pins, one is used only for the 10 MHz output buffer, if remember it 
> correctly. Which is your model number?
> Ignacio EB4APL
> El 04/11/2016 a las 16:35, Peter Reilley escribió:
>> I gave up on trying to use the GPS 1 PPS signal to calibrate the 10 
>> MHz OCXO's that
>> I have.   The reason that others have pointed out is that the 
>> uncorrected 1 PPS
>> signal from the GPS is has just a little too much a jitter to use it 
>> for calibration
>> with your eye using a scope.   If it were sawtooth corrected then it 
>> would be better
>> but you really need a GPS disciplined oscillator.
>> Not to be outdone, I brought out a rubidium oscillator that I had put 
>> away because
>> it did not appear to work properly.   It only put out a 1 PPS signal 
>> and nothing else.
>> I compared that with the GPS PPS and could get a good comparison on 
>> the scope.
>> The rubidium drifted about 40 nS over 12 hours.   So it seemed to be 
>> good.
>> With that I could adjust the OCXO's in my 5370's.   The spec for the 
>> HP 5370B with
>> a HP 10811 OCXO is better than 1 X 10^-10 RMS for 1 sec average. That 
>> is, it should
>> take more than 1,000 seconds for one 10 MHz wave to shift by 360 
>> degrees.   That
>> is very hard to do using the screw adjustment in the OCXO. Even the 
>> slightest
>> movement possible will cause a frequency change greater that is 
>> spec'ed.   How
>> do cal labs do it?
>> My HP 5370A has a 10544 OCXO which is spec'ed for short term 
>> stability of
>> better than 1 X 10^11 for 1 second.   Even better than the 5370B! The 
>> adjustment
>> screw is much coarser and it is not possible to get any better than a 
>> few seconds for
>> one cycle phase shift of the 10 MHz OCXO against the standard. It 
>> seems that I can't
>> get even close to the spec.
>> These have been running for a few days.   It that enough?
>> Pete.
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