[time-nuts] Re: Coupling between oscillators -- an example

[Joseph Gwinn]

On Sun, 27 Mar 2022 03:30:23 -0400, time-nuts-request at 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" <richard at karlquist.com>
> Subject: [time-nuts] Re: Coupling between oscillators -- an example
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at lists.febo.com>,        John Ackermann N8UR <jra at febo.com>
> Message-ID: <006da0b8-9dbc-ec19-9e41-10ac6540077f at 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