[time-nuts] FEI 5680A

Jeff Mock jeff at mock.com
Wed Mar 5 21:38:59 UTC 2008


I think that I might purchase a GPS disciplined oscillator instead of 
rubidium standard for a cal lab.  There's no physics package in danger 
of wearing out and no worries about local settings changing accuracy. 
They are also low power and something like the Trimble unit is very compact.

jeff


Rex wrote:
> Jean-Christophe Deschamps wrote:
>> Dear group,
>>
>> I'm a newbie here, so please bear with me.
>>
>> I'm about to buy a FEI 5680A Rubidium frequency standard off 
>> ebay.  From what I've gathered, these units were used in the telco 
>> industry for about 10 years, but are still useable for my needs.  I 
>> wish to have a reasonably good frequency standard for calibrating test 
>> equipment (scope calibrators, function generators, etc), say every 6 
>> months or once a year.  For such use I really don't need extreme 
>> stability/accuracy.  Only hope is that the physics part isn't 
>> completely dead.
>>
>> These units typically only produce a 1pps signal, but have the capacity 
>> to produce the classical 10 MHz sine wave.
>>
>> I've found a number of documents explaining how to have the 10 MHz 
>> produced by these versions.  Two of them give consistent informations 
>> and seem to be sufficiently documented to be of real value.
>>
>> Drop me a mail at jcd at q-e-d.org if you feel posting the files could 
>> help someone.  I don't know how to post files so that readers of this 
>> list can access them. Anyway, I'll postpone distributing the files at 
>> large until I check by myself their contents is useful.
>>
>> Feedback welcome!
>>
>>   
> It seems there were many versions of the 5680A that look about the same 
> but are very different. Some run on just +15 V and some need that and 
> +5V. I suspect there are other voltage options too. Some are adjustable 
> in frequency with software commands or a C-field screw.
> 
> I bought one in early 2005. I figured out by reverse engineering that it 
> needed both +15 and +5 V. It provides both 10 MHz and 1pps outputs on 
> the D-connector. I never found a way to get it to respond to any serial 
> commands, although it has rs-232 interface chips and the signals were 
> propagating inside. I never found any way to adjust the frequency on 
> this one.
> 
> Other people clearly have units that run on just +15V and do respond to 
> serial commands to set the frequency. One person reported they were able 
> to adjust the frequency on theirs with a screw setting.
> 
> So it is hard to say what you may get. You may want to search the 
> time-nuts archives, particularly in 2005.
> 
> 
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