On Sun, 27 Mar 2022 03:30:23 -0400, time-nuts-requ...@lists.febo.com wrote: time-nuts Digest, Vol 215, Issue 35
> 3. Re: Coupling between oscillators -- an example > (Richard (Rick) Karlquist) > Date: Sat, 26 Mar 2022 15:37:17 -0700 > From: "Richard (Rick) Karlquist" <rich...@karlquist.com> > Subject: [time-nuts] Re: Coupling between oscillators -- an example > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com>, John Ackermann N8UR <j...@febo.com> > Message-ID: <006da0b8-9dbc-ec19-9e41-10ac65400...@karlquist.com> > Content-Type: text/plain; charset=UTF-8; format=flowed > > > > On 3/25/2022 12:41 PM, John Ackermann N8UR wrote: >> >> >> PS -- an interesting feature of these oscillators is that they are an >> "S12" variant that has a little accelerometer bolted on and hooked to >> the EFC circuit to compensate for G forces. These were ship-board Cs >> units, so I wonder if the accelerometers were intended to compensate for >> ordinary ship vibrations, or maybe the firing of the big guns. :-) >> > > During the initial debug of the early 5071 prototypes (circa 1990) > it somehow came to light that 5061's on ships had a phenomenon where > the frequency would be slightly, but noticeably affected by the > slow rolling motion of the ship. Len Cutler and our CBT genius > figured out that the problem was in the cesium beam tube. Therefore, > the 5071 would also exhibit this problem. The CBT was modified before > the 5071 release and the problem was eliminated. IIRC, the problem > had to do with the Cs atoms being ballistic objects that didn't hit > the bulls eye if the CBT was moving. I seem to recall that the > problem was a result of some other problem they tried to fix, but > the fix was too clever by half as they say. > > Possibly, this is related to the units you have. > > Regarding big guns: one of the specs the 5071 (and 5061) had to meet > was the "hammer blow test" which simulates the firing of big guns, > using a 400 pound hammer that strikes a frame in which the DUT > is mounted. It's OK if the DUT suffers structural damage ... > as long as the DUT keeps working. I think it is allowed to > momentarily go off frequency during the test. This 400# hammer test sounds a lot like MIL-S-901, which is hideous to behold, but is nonetheless realistic. The barge test is something else - think nearby mines and depth charges. Recall all those War at Sea movies about WW2, where clashing groups of battleships duked it out with 16" naval guns and 500# bombs. It would be very bad if one's battleships had glass jaws, collapsing after one hit. Thirty years ago, I worked on a naval system that was required to absorb and survive three cruise-missile strikes. .<https://en.wikipedia.org/wiki/MIL-S-901> Joe Gwinn _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.