Hi Indeed, there will always be some EMF into the EFC from some field. You can never really get rid of a loop with some cross section in the EFC circuit. Most of us don't get to worry about 1x10^-16 at 1,000 seconds on our OCXO's….
Bob On Dec 30, 2012, at 11:16 PM, Jim Lux <jim...@earthlink.net> wrote: > On 12/30/12 8:03 PM, Bob Camp wrote: >> Hi >> >> They are using some pretty major fields in that paper. As they point out, >> high level tests likely do not extrapolate well to low level performance. >> Their data shows the impact diminishing quickly as the field drops. >> >> If you accept their 1x10^-11 per gauss number as correct, your OCXO might >> see a 5x10^-12 change as you rotated it 90 degrees. Unless you have a very >> good OCXO, that's not a big impact. >> >> In the case of a fan that's likely generating mili gauss of field (you don't >> get that much off of 50 ma at 12v), you could see 1x10^-13 level changes. >> Your OCXO's AVAR is likely well above that at any tau that the fan messing >> with. >> >> Yes, I'm making the assumption that the fan motor is not in contact with the >> OCXO case. In any rational setup there will be at least a few inches between >> the fan and the OCXO. Not exactly far field at 20 Hz, but the field does >> drop off pretty fast. >> >> > > A bigger concern might be if you're locking something you care about to that > oscillator. The PLL might be more sensitive (particularly things like the op > amp circuitry driving the VCO... there's probably some sort of physical loop > in the wiring between the inverting and noninverting inputs of the op amp. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
