[time-nuts] FE-5680A

Peter Bell bell.peter at gmail.com
Thu Nov 10 22:57:18 UTC 2011


It's fairly clean - there is a bit of harmonic distortion since its being
generated from a 10MHz square wave via a simple LC filter but it seems
otherwuse quite nice. The RF architecture of these new units is quite
different from the old ones and the VCXO now runs at 60MHz this is divided
down in a Xilimx PLD and the output comes from that - the RF for the snap
diode drive is generated  by mixing the 60MHz with the output of a DDS chip
and it seems that the  FM needed to interrogate the Rb cell is applied in
this loop rather than directly to the VCXO.

Overall, I think the output is quite a bit nicer than the old units.

On Nov 11, 2011 6:32 AM, "WB6BNQ" <wb6bnq at cox.net> wrote:
>
> Peter,
>
> Is the 10 MHz output a clean sinewave or does it look kind of trashy ?
>
> thanks,
>
> Bill....WB6BNQ
>
>
> Peter Bell wrote:
>
> > Assuming it's the same as the units I have (two labels, with "FEI P/N
> > 217400-30352-1" on the upper label and two barcodes on the lower
> > label) then the +5V supply runs all the logic in the unit. There are
> > no special power sequencing requirements, but you need both supplies
> > for the unit to operate. The current drain on the 5V line is fairly
> > low - about 90mA - the 15V will pull about 2A when the unit is cold
> > and then drops to 500-600mA once everything is warmed up.  Pin 3 is
> > the lock indicator - driven low when locked.  The output (10MHz sine)
> > is present on pin 6, and appears immediately after power up - although
> > the frequency is not accurate until the lock pin is asserted.
> >
> > The 4 digit prefix on the lower barcode is a date code - so "S/N
> > 0416-77234" would indicate a unit made in week 16 of 2004.
> >
> > Regards,
> >
> > Pete Bell
> >
> > On Fri, Nov 11, 2011 at 12:30 AM,  <EWKehren at aol.com> wrote:
> > > I did purchase one of the "New"  FE-5680A Rb's. Looking at packaging
 and
> > > the housing it does look new. I have not powered it up because of +5
 Volt on
> > > pin 4. Does any one know its purpose and is there a power up
 sequence. Any
> > > help will be appreciated.
> > > Bert Kehren  Miami
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