[time-nuts] New to list and GPSDO questions

Bob Stewart bob at evoria.net
Thu Jun 13 15:17:53 EDT 2013

Hi Paul, and everyone.  Yeah, that's a good question: how much accuracy do I want?  I'm really just looking for a relatively easy project; one that will go to successful completion and give me a sense of accomplishment.  At this moment, I have the problem of the man with two clocks.  Better than 1 Hz @ 10MHz accuracy would be good.  But, realistically, if the 5334B and 8640B both tell me the same thing, then I'll probably be happy.  I could do that with the Trimble 34310-T, a pot and a flip-flop, but then I'd feel compelled to listen to WWV on occasion and tweak the pot!  LOL  I do have OCD, so I'm getting involved with timing with more than a little trepidation.

I want this to be as low budget as is reasonably possible, barring wastage, so I think a 1PPS source and Bert's FLL are the right choice.  Is there actually a PLL circuit that works with a 1PPS reference?  I only found a very few GPSDO projects during my search, and Bert's was the only one using the 1PPS signal.  And, I just like the way he did it, right down to giving the possibility of powering the output op-amp from the VREF output of the 34310-T.  I'm assuming that won't overload it, of course, so any comments on that would be appreciated.

Bob - AE6RV

----- Original Message -----
> From: paul swed <paulswedb at gmail.com>
> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
> Cc: 
> Sent: Thursday, June 13, 2013 1:47 PM
> Subject: Re: [time-nuts] New to list and GPSDO questions
> Absolutely agree with this comment. But understand thats a trade off for
> simplicity and for many radio operators its good enough as they say.
> Whats really not been mentioned in the thread is how accurate do you want
> to be or need.
> Be very careful with the answer. Time is the drug that keeps on giving.
> $$$$$
> Regards
> Paul
> On Thu, Jun 13, 2013 at 2:41 PM, Attila Kinali <attila at kinali.ch> wrote:
>>  On Wed, 12 Jun 2013 20:29:26 -0700 (PDT)
>>  Bob Stewart <bob at evoria.net> wrote:
>>  > Hello to the list.  I saw on K3PGP's site a mention that
>>  > the UT-41 GPS receiver had a 10KHz signal on-board so I decided, why 
> not
>>  > build a GPSDO for my "new" HP 5334B?  Unfortunately the one 
> I bought
>>  doesn't
>>  > have a 10KHz point, and the board doesn't even pull out the 1PPS 
> signal
>>  from
>>  > the chip.  So I've had to switch gears and will go with 
> VE2ZAZ's board.
>>  Please be aware that VE2ZAZ's design uses a frequency locked loop and 
> not
>>  a phase locked loop. Thus you end up with a slight frequency error
>>  (instead of a slight phase error).

More information about the time-nuts mailing list