[time-nuts] What sort of oscillator is this?

David McGaw n1hac at dartmouth.edu
Sun Sep 28 10:52:53 EDT 2014

The temperature stability and warm-up time imply an OCXO.  0.05ppm over 
0-55C is at the limit of what can be achieved with a TCXO but they do 
not have a long warm-up time.  It would be expensive and only would be 
used if warm-up time was critical.  The HP high-stability options are 
(almost?) always OCXOs.


On 9/28/14 6:16 AM, Hal Murray wrote:
> drkirkby at kirkbymicrowave.co.uk said:
>> Two people responded - one says a OCXO and the other an TCXO!!
>> The warmup time is I think an hour, but clearly that is not the time for an
>> oven to warm up.
> An hour seems like a reasonable OCXO warm-up time to me.  You might get
> faster warm-up times, but you will probably pay for it someplace else.  Here
> is a graph:
>    http://www.megapathdsl.net/~hmurray/time-nuts/Drift-ocxo3mhz-a.gif
> Also, it probably depends upon how long it has been powered off.
> See how much power the system draws when plugged in but turned off.  Most
> gear using OCXOs keep them powered up when the front panel switch says "off".
>   So 0 is a strong indication that you have a TCXO.  You can also unplug it
> for a couple of hours, then watch the power after you plug it in.  I'd expect
> a step decrease in power after the core is mostly warm.
>> I find it odd that an instrument that probably cost $50,000 when new did not
>> have a TCXO as standard,  and perhaps an oven as an option.
> Maybe most customers have a good lab source of 10 MHz and use an external
> clock.

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