[time-nuts] FE-5680B Rubidium and DDS

[Bob Camp]

Hi

There is no dump of the firmware. The problem you are most likely 
having is not firmware related.

If the VCXO i the unit drifts to far it needs to be re-tuned. Until this is done
the device simply sits in a “search for lock” loop forever and ever.

Simple way to do it:

Monitor the VCXO and bump the trimmer until the frequency goes above the intended
target (10 x N MHz depending on your monitor point) by at least 0.15 ppm. The sweep is
slow enough that a counter running at a 0.1 second gate will easily show you what’s going on.

Of course it can be other things. All of them are a bit more involved to fix.  

Bob

> On Sep 25, 2015, at 11:34 AM, Clint Jay <cjaysharp at gmail.com> wrote:
> 
> I've recently purchased one of the PPS Only FE Rubidium standards from eBay
> and, like many others I suspect, haven't been able to get a stable output
> frequency that lasts longer than a few seconds from the module.
> 
> It appears that the 10MHz source vanishes after a few seconds but this is
> controlled by firmware.
> 
> Which leads to my question, there is a dump of the firmware from the
> FE-5680, has anyone tried to reprogram one?
> -- 
> Clint.
> 
> *No trees were harmed in the sending of this mail. However, a large number
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