Hi Thermal shifts from tip are a very real issue when you flip around OCXO's. The acceleration is an instantaneous change. The thermal will have a time constant out beyond 30 seconds. It's pretty easy to separate the two if you have something that functions like a strip chart recorder. Stable 32 does the job very nicely...
There is a second thermal issue related to just plain blowing a bunch of air over the OCXO, compared to still air. That may or may not be significant depending on just how well the 10811 is shielded in your pendulum. Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom Van Baak Sent: Monday, March 29, 2010 4:58 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Making a HP 10811 better > Now if you really want some fun connect your OCXO to a > one meter cable and let it swing like a pendulum clock. You > should see some very nice sinusoidal FM as it goes back > and forth. Devise some sort of mechanical, compressed air, > or magnetic impulse system to keep it running like that all day. > > /tvb It works! http://www.leapsecond.com/pages/10811-g/ Bob, it would seem the frequency shifts in this swinging 10811 oscillator are all acceleration related and not due to internal temperature variations, right? I could imagine there are (longer time constant) thermal effects for a full 2g turn-over, but not with this short ~1 Hz period. In fact you can see a slight, probably temperature gradient related, frequency drift after a full 2g turn (I waited about 5 minutes after each turn): http://www.leapsecond.com/pages/ocxo-2g/TBolt-2g-6axis.gif /tvb _______________________________________________ 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.
