[time-nuts] Man with too many clocks.

EB4APL eb4apl at gmail.com
Sat Nov 5 09:25:01 EDT 2016

I agree that FE-5680 is a whole family of products with very different 
features and these can not deducted from the labels.

In my case I own a FE-5680A which outputs 1 PPS and a fixed (but 
slightly tunable) 10 MHz and needs 2 power supply voltages, +5 V and + 15 V.

I am sending directly to you the information of the breakout board that 
I use and it includes the pinout of this unit.  A caution here, some of 
the FE-5680 variations have different pinouts.


Ignacio EB4APL

El 05/11/2016 a las 2:01, Peter Reilley escribió:
> It is a FE-5680B.   It is my understanding that these were made in 
> many variations
> 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.
> Pete.
> 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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