Hi Jim, Thanks much for the update. I can see how this was a pain to track down.
For those that don't remember the issue, the archive starts here: https://www.febo.com/pipermail/time-nuts/2015-December/094904.html And note that 1 / 0.704 ns = 1420 MHz, the frequency of a H-maser. So it's either electrical or magnetic or seismic, yes? Does it happen every time the HVAC turns on/off? Can you run a high-resolution phase comparator during the event to find the time constant of the phase jump / cycle slip? 1 kHz sample rate should be more than enough. That may help narrow down which circuit is at fault. /tvb ----- Original Message ----- From: "Jim Palfreyman" <[email protected]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Saturday, May 21, 2016 6:58 PM Subject: [time-nuts] Maser 0.7 nsec jumps solved > Hi all, > > Awhile back I posted about some mysterious 0.7 ns jumps in three different > masers (of the same brand) at three different locations around Australia. > > Well we think we've found the problem. All three locations also have > in-room air conditioners of the same brand. These are used for cooling > only. When these units turn on, we think they induce a magnetic field from > the inrush current that briefly disrupts the maser. We don't think it's > electrical because moving to another phase did not change things. > > These air conditioners are all quite close to the masers. Typically a metre > or 2 away. > > Much was done to discover this, but the clincher was that when the weather > cooled enough at the southern most location (Hobart), we turned off the air > con (only heating was needed) and the problem vanished. > > So there's a lesson here for all maser owners. The jump of 0.7 nsec is not > much, but it's huge for VLBI and for time-nuts. > > > Jim Palfreyman > _______________________________________________ > 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.
