Hal, An ocxo has two effects that cause a frequency change after power on: heater stabilization and crystal retrace.
Heaters usually stabilize quickly (1 - 2 minutes for DIP-14 ocxo, 7 to 10 minutes for typical eurocan docxo's) and then a. ~30 minutes soak until the ocxo starts following ambient temperature. After the initial warmup the crystal goes into an exponential retrace as it out-gasses etc and it can take many hours or even days or weeks for that to subside. Then what is left is typically linear aging. Bye, Said Sent From iPhone > On Sep 28, 2014, at 3:16, Hal Murray <[email protected]> wrote: > > > [email protected] 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. > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
