[time-nuts] Caring for the elderly (OCXO)

Bob Stewart bob at evoria.net
Sat Aug 31 14:16:41 EDT 2013


Hi Said,

Thanks for the input!  I thought I had remembered someone's post about crystal jump, but I wasn't sure.

Bob





>________________________________
> From: Said Jackson <saidjack at aol.com>
>To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>Cc: Time Nuts <time-nuts at febo.com> 
>Sent: Saturday, August 31, 2013 1:12 PM
>Subject: Re: [time-nuts] Caring for the elderly (OCXO)
> 
>
>Bob,
>
>Pretty standard behavior for some crystals. I recently had such a jump after 150 hours. Some ocxo vendors are way more affected than others.
>
>Nothing to worry unless it gets worse or happens more often over time.
>
>Bye,
>Said
>
>Sent From iPhone
>
>On Aug 31, 2013, at 10:48, Bob Stewart <bob at evoria.net> wrote:
>
>> My OCXO is a Trimble 34310-T that I bought from a China recycler a month or so ago.  It has been very stable until this morning.  At about 10:30AM my PLL showed a large blip during one segment  count (1PPS) and the DAC started tracking upward to stabilize.  Then, 745 seconds later it glitched in two successive segments and the PLL has tracked the DAC downward well below the old stable number.  For an independent reference, I have my 8640B self-locked inputting on Channel A of my 5335A with a large enough gate for 8 decimal points of display.  My GPSDO is serving as the time reference for the 5335A.  Give or take the stability of the 8640B, the counter seems to agree with what my GPSDO is doing.
>> 
>> This is for hobby and learning, so no big deal, but I'm wondering if this is how OCXOs start misbehaving in their dotage (so to speak).  On the one hand, it gives me another insight into error handling for my PLL logic, which is good.  But, on the other: I'm wondering if I should just give it a proper burial and put in my spare?  Maybe I'll leave it in to see if any other error modes develop, and then toss it when I finally have code I'm willing to share.  Anyway, is this oscillator on its last legs?  I'm more worried about letting out the magic smoke and damaging other components than I am about accuracy at this point.  
>> 
>> Bob - AE6RV
>> _______________________________________________
>> 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