[time-nuts] Efratom/Datum GPSDO GPS-FC

[paul swed]

Quite difficult to see. But it appears the gps antenna cable is just
hanging there not connected to what I presume would be a antenna.
Regards
Paul
WB8TSL

On Sun, May 31, 2015 at 4:47 PM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> If you look at the pictures you can see the oscillator they are using for
> the 10 MHz. At least as far as I can see
> it’s markings look like those of a VC TCXO. If you mount the device
> outdoors (as you must to get it to work) there
> will be a lot of temperature swings. In if the little oscillator *is* an
> OCXO, it’s not a fancy one. Between the
> simple oscillator and the outdoor location, you are unlikely to get very
> good performance out of the unit.
>
> The Oncore in this device has many of the same issues as ones we have
> discussed in other GPSDO’s. The
> design of the one in your gizmo is now approaching 20 years old. The
> interface strings are well documented
> and you should be able to tap into the module’s i/o stream to see what’s
> going on. I would recommend tacking
> a TTL to USB converter onto it and letting a terminal program show you
> what is happening.
>
> Bob
>
>
> > On May 31, 2015, at 11:58 AM, Vlad <time at patoka.org> wrote:
> >
> >
> >
> > Hello,
> >
> > Some time ago, I got Efratom/Datum GPS-FC item. The apparatus itself
> looks like good quality weather-proof aluminium case with embedded GPS
> antenna. It has only one connector. That connector is using to supply the
> power to the unit and as well to get 10Mhz signal from it.
> >
> > Here is the sticker inside of the devices:
> >
> > http://www.patoka.ca/OCXO/GPS-FC-LBL.JPG
> >
> > I tried to play with this device, however all my attempts to get 10 Mhz
> from it has failed.
> >
> > Here is how its looks inside:
> >
> > http://www.patoka.ca/OCXO/GPS-FC-PCB.JPG
> >
> >
> > AFAIK, there is Motorola Oncore GPS. I checked the 1PPS signal from that
> module and its looks good - I see the 1PPS on my scope.
> > Also I did check on TP4 on PCB. Looks like its an output from 10Mhz
> VTCXO. And I see the sine on the scope.
> >
> > I tried to contact Microesemi to obtain some service manual or even
> schematic for this unit, but unfortunately its not an option. Microsemi
> sent me only this manual:
> >
> > http://www.patoka.ca/OCXO/GPS-FC-Manual.pdf
> >
> >
> > Its appeared this units out of support for long period of time. So, I
> would ask if anybody knows anythings about it ? Especially I would be
> interested about what to measure/expect on control points on PCB. I still
> hope its repairable. Thanks in advance !
> >
> >
> >
> > --
> > WBW,
> >
> > V.P.
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