[time-nuts] Advise on building a DIY GPSDO?

Bob Camp kb8tq at n1k.org
Mon Apr 4 21:23:03 EDT 2016


Hi

…. and this fulfills the requirement I mentioned:

“I just want to build one to say I’ve done it” 

There is *absolutely* nothing at all wrong with that. If this is your goal, you have
accomplished it. You likely have learned somethings along the way. 

If you have a performance goal that is anywhere close to what the $50 to $150
surplus devices will do, this sort of design will not do the job.

Figuring out what you want to do *does* matter a lot. 

Bob

> On Apr 4, 2016, at 8:48 PM, dlewis6767 <dlewis6767 at austin.rr.com> wrote:
> 
> Lots' of help herein; ...but,  also lots' of nay-sayers, too.
> 
> Don't let the nay-sayers scare you.  
> 
> A VERY accurate, newbie-based, GPSDO can be built with minimal
> investment or cost.
> 
> It's not hard at all.  Just Do-It.  Mistakes allowed.
> 
> I have built two GPSDO's from scratch.  Both worked very well against
> each other measured with an HP 5370B; against my rubidium; as well as
> my cesium.
> 
> Just look at it at the 'building-block' level. (no real need for an
> embedded computer unless you like code more so than dips.  :-)
> 
> 
> 1.  Get a good, used, GPS receiver with a 10Khz output.
> 2.  Get a good, used, 10MHz OCXO with a voltage control.
> 3.  Design a simple divide-by-thousand divider.
> 4.  Exclusive-or these two using a 4046 PLL (comparator 1)
> 5.  Design a voltage tracking / filter to match the OCXO control
> requirements.
> 6.  And, ...ta-dah;  
> 7.  You have a 10MHz, bench frequency standard that will rival all
> others; and the best part....you designed and built it!
> 8.  NOTE:  Take the unused, SR flip-flop output of the 4046 PLL and
> connect a small, analog, milliampmeter.  It will swing back and forth
> trackin the XOR function until your GPSDO 'locks'; then become
> stationary.
> 
> Basic? Yes!  Over-simplified?  Probably.  
> 
> But it will work and you will feel like you accomplished your goal of
> 'doing-it-yourself'.
> 
> -Don
> ======================================================
> 
> 
> 
> 
> 
>> 
> 
> -- 
> dlewis6767 <dlewis6767 at austin.rr.com>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



More information about the time-nuts mailing list