Hi Said: All kinds of things effect the crystal including gravity. Some time ago I wrote a Labview program to look at the control voltage then rotated the PRS10 resting it on each of four faces, see: http://www.prc68.com/I/Images/FC_ROT.jpg So, just as gravity effects pendulum clocks, it's also effecting crystal oscillators, just on a smaller scale.
There also was a LV screen for the physics package, see: http://www.prc68.com/I/Images/Phy.jpg The PRS10 is at: http://www.prc68.com/I/PRS10.shtml Have Fun, Brooke Clarke http://www.prc68.com/P/Prod.html Products I make and sell http://www.prc68.com/Alpha.shtml All my web pages listed based on html name http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam [EMAIL PROTECTED] wrote: > Hi Bob, > > they should and do, and if it jumps the Rb will pull-in the OCXO frequency > correcting for the error. This pull in time is determined by the loop time > (cut-off frequency) of the Rb PLL loop. I expect this loop time to be much > shorter than a GPSDO's loop time, so the effect is probably much less > visible. One > should still be able to see it as a distinct offset when plotting the EFC > control voltage of the OCXO. > > Considering that jumps often hit 1ppb offset, I am surprised how many folks > on this forum have discussed that their oscillators jump, and how little > research actually has gone into figuring out how to minimize these jumps. I > would > not be a big fan of contraptions that use two or three OCXO's to minimize > the impact since all three could potentially jump at the same time. I would > rather attack the problem at the source - most of the time its the crystal. > > There is probably something that can be done to minimize jumps, such as the > crystal cut, modifying the crystal operating temperature, modifying the > current through the crystal, comparing different mounting methods, changing > the > direction (orientation) the crystal is mounted in, etc etc. > > Here is a hint for experimentation: I once had an OCXO that jumped all the > time (many times per hour). Since this was a reject part (definitely a > factory > RMA), I took a large screwdriver and gave the OCXO a good bang. The jumping > was immediately mitigated down to a couple of times per day. That causality > was a real eye opener, whatever stresses were on the crystal were released > by > the shock. > > bye, > Said > > > In a message dated 10/23/2008 08:39:18 Pacific Daylight Time, > [EMAIL PROTECTED] writes: > > So why would they not show the same kind of jumps as plain OCXO's? Rick K. > mentioned atomic standards avoid jumps. > Bob Q. > > _______________________________________________ > 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.
