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

[Bryan _]

Clint, where are you seeing a 10Mhz output from the XC9752. That may be the easier approach if 10Mhz is the desired frequency. just send it to a buffer/ amplifier. Likely most users will want to do that anyways to add additional outputs.

-=Bryan=-

> Date: Sat, 26 Sep 2015 07:36:30 +0100
> From: cjaysharp at gmail.com
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] FE-5680B Rubidium and DDS
> 
> Bryan, I also found a stable 30MHz which I think is used to clock the
> optional DDS board so I intend to experiment adding an AD9851 board with 6x
> multiplier enabled but first I want to try and understand why the unit
> locks and only outputs 10MHz from the XC9572, something in the firmware
> appears to turn off the output, I may get around to experimenting a little
> more soon and will of course share my findings if they're of interest. .
> 
> Bob, there are files which claim to be a dump of the firmware and also the
> XC9572 along with a partial schematic but they're from a 5680A which, from
> the pictures on the net, is a slightly different hardware version although
> the major components appear identical so it may be possible to modify the B
> version Bryan and I have.
> 
> On 26 September 2015 at 02:45, Bryan _ <bpl521 at outlook.com> wrote:
> 
> > There is information on this thread on how you can tap into the unit at
> > various points to get 20 and 60Mhz. Other owners have used a divider to
> > bring it to the 10Mhz frequency desired. I have one of these units and
> > haven't gone around to dividing it down. I purchased mine from Ebay and the
> > seller notes that this particular version will output 10Mhz for a second or
> > two and then disappear. I suspect you have the same version, maybe even the
> > same seller, so the operation of these particular units appears to be
> > normal. Mine will lock so I know it's working.
> >
> > http://www.eevblog.com/forum/testgear/fe-5680b-1pps-to-10mhz/msg556800/#msg556800
> > I as well wish there was a quick way of converting it back to 10Mhz. I am
> > sure it can be done, just not sure how or where to look <g>
> >
> > -=Bryan=-
> >
> > > From: kb8tq at n1k.org
> > > Date: Fri, 25 Sep 2015 17:45:08 -0400
> > > To: time-nuts at febo.com
> > > Subject: Re: [time-nuts] FE-5680B Rubidium and DDS
> > >
> > > 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
> > > > of electrons were greatly inconvenienced.*
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> 
> 
> 
> -- 
> Clint.
> 
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
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