[time-nuts] 9390 GPS RX

Ed Palmer ed_palmer at sasktel.net
Fri May 31 01:58:15 EDT 2013

On 5/30/2013 9:44 PM, Mark C. Stephens wrote:
> Oh No, it stayed locked, I sat there until 4:30am watching it..
> But it's still drifting +/- 2 Hz 8 hours later which annoys me so much!
> I will take a page from Ed's book and exercise patience, I guess.
> Not much else I can do without disturbing its natural course.

Well, since you've apparently given up on time-wasters like sleep, there 
are a few things that you can do while you wait.

1.  Check your power supplies for noise, ripple, and proper value. Not 
just the 28V, but there has to be 5V, maybe +-12V or +-15V, etc.  Don't 
forget that you've got capacitors in there that are over 20 years old so 
anything's possible.
2.  Check the EFC to the FRK for noise & ripple.
3.  Are there any software commands that have to be or should be used to 
set up the disciplining?  I glanced through a manual for a 9390 and it 
looks like there's a 'z' command to initiate disciplining.
4.  Do the status reports indicate that everything's good?  Number of 
satellites tracked?  Signal strength?  EFC value?  Anything else?

I'm looking at the picture of the unit on your website and I'm a bit 
confused.  I see the FRK in the back corner, but I can't see it's 
cabling.  I see what looks like an OCXO on the second board from the 
front with white cables coming off of it.  There's also what looks like 
the outline of an OCXO on the main board with white cables connected 
where the output and EFC would be.  What's connected to what?

By the way, in the back right corner of the main board next to the 
EPROM, I can see a big Dallas Semi chip.  Are you aware that there's a 
lithium battery in there that's probably stone dead?  I don't know what 
the effect of that would be, but it's something to check.


> -marki
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of J. L. Trantham
> Sent: Friday, 31 May 2013 12:32 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] 9390 GPS RX
> So, probably means that it is 'flashing', on and off. :^).
> Joe
> So, it's been sitting there for a couple of hours before the Lock LED came on.
> Interestingly enough, I woke up (its 3am here) and I thought, Hmm wonder if its locked.
> I walked down stairs to the workshop and looked at the front panel just as the Lock LED came on!

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