[time-nuts] GPSDO Alternatives

WB6BNQ wb6bnq at cox.net
Thu Dec 6 09:21:40 UTC 2012


If you want to understand how to approach the issue, you need to study the Shera
controller system.  It does exactly what you and others are discussing doing.  It
is relatively simple, straight forward and the HEX file is available to program
the CPU with.  The circuit board is all ready made and available.

The only hard part is the D/A which may be a bit of a problem with respect to the
original part.  However, even that may be available from another vender.  If not
there are some similar replacements, but that may require making new boards to
account for the parts being surface mount types.

Do yourself a favor and look at the following URL and download the reprint of the
QST article.



Chris Albertson wrote:

> Now you can see the problem with designs that require both a PCB and a
> programmed uP.   Most people can't do either of these and those who can
> typically are good at only one.   Then you find someone and after he looses
> interest the project is dead and un-suportable.
> So I was thinking of how to build a GPSDO that does not need a programmed
> uP and would be so simple that a PCB would not be needed.  It shoud be
> simple enough that after getting the parts could be built quickly by anyone.
> The Arduino has a USB interface and both ADC and DAC and digital IO.  I
> read about the concern about using USB power.  The Arduino can also be
> powered by a 9V battery so it will continue to run if the USB power goes
> away.  Or you can use a power cube (aka "wall wort")  Anyone can program an
> Arduino even if you know nothing about uP.  It is VERY easy and the
> software runs on Mac OS X, Linux and even Windows.
> I would use a separate power supply for the OCXO as they take more power
> and this needs to be cleaner than I'd expect USB power to be.
> The question I have again is about a simple phase detector.
> On Wed, Dec 5, 2012 at 3:28 AM, <EWKehren at aol.com> wrote:
> > Chris
> > There is a low cost solution and I have the input circuit perfect for GPS
> > on a $1 gate array I have boards and am presently using Shera original
> > version.  Would like to buy his version 402NE but have not been able to
> > get a
> > response from him. Have repeatedly asked for help on this list for some
> > one to
> >  step forward to write the uproc. program. No one. The total material cost
> > would  be less than $ 25 PCB included  GPS receiver OCXO or RB would be
> > extra. If  the FE 5680A with RS232 would be used cost is less than $ 15.
> > There
> > are now  PIC's out there that can also do the timing function reducing cost
> > even more but  that will take more smarts.
> > Bert Kehren
> >
> >
> Chris Albertson
> Redondo Beach, California
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