[time-nuts] HP 5061Cs reference question

Magnus Danielson magnus at rubidium.dyndns.org
Sat Dec 6 23:49:37 UTC 2014


C-field adjustment is what you should be doing then.

Cheers,
Magnuns

On 12/07/2014 12:24 AM, paul swed wrote:
> Slow by 44 ns in 27 minutes.
> -2.7 e-11
> Regards
> Paul
>
> On Sat, Dec 6, 2014 at 5:24 PM, Magnus Danielson <magnus at rubidium.dyndns.org
>> wrote:
>
>> Yes, but what's the offset?
>>
>> Cheers,
>> Magnus
>>
>>
>> On 12/06/2014 10:12 PM, paul swed wrote:
>>
>>> The system does consistently come to lock with a constant offset. So its
>>> finding something. Just the odd little offset thats bugging me.
>>>
>>> On Sat, Dec 6, 2014 at 2:48 PM, Magnus Danielson <
>>> magnus at rubidium.dyndns.org
>>>
>>>> wrote:
>>>>
>>>
>>>   It's a challenge indeed. IF you are running on fumes, it will be harder
>>>> for the automatic locking to find first and second modulations, and if it
>>>> does this, it is much more likely to be the central pedestal as the
>>>> others
>>>> will be even further down into the noise. The lack of the fundamental
>>>> tone
>>>> will cause that FLL may fail to lock, since the sweep signal can be too
>>>> strongs, and if it does lock, it will be weak as the loop gain will be
>>>> off
>>>> by the lack of signal and then naturally the S/N will be problematic.
>>>>
>>>> Not sure that it in itself will be the cause of systematically drifting
>>>> of
>>>> the mark, but rather varying a lot around that mark.
>>>>
>>>> Cheers,
>>>> Magnus
>>>>
>>>>
>>>> On 12/06/2014 08:16 PM, paul swed wrote:
>>>>
>>>>   All good answers with a good tube and enough current to read on the
>>>>> meter.
>>>>> But I am working at the very limit of the Cs fumes. There is current,
>>>>> about
>>>>> .5 to 1 tick mark on the meter of a 5061 using a 5060 tube.
>>>>> Thats the challenge on a very eol tube.
>>>>> Regards
>>>>> Paul.
>>>>>
>>>>> On Sat, Dec 6, 2014 at 1:56 PM, Magnus Danielson <
>>>>> magnus at rubidium.dyndns.org
>>>>>
>>>>>   wrote:
>>>>>>
>>>>>>
>>>>>    Tom,
>>>>>
>>>>>>
>>>>>> On 12/06/2014 06:04 PM, Tom Van Baak wrote:
>>>>>>
>>>>>>    Paul,
>>>>>>
>>>>>>>
>>>>>>> There are 7 peaks total, about 40 kHz apart (on my 5061A). If you're
>>>>>>> talking about just the central peak, there are two smaller peaks on
>>>>>>> either
>>>>>>> side, about 1 kHz apart. The exact value depends on internal magnetic
>>>>>>> field, which is specific to each beam tube design.
>>>>>>>
>>>>>>> For some measurements of all the peaks, have a look at:
>>>>>>> http://leapsecond.com/pages/cspeak/
>>>>>>>
>>>>>>>
>>>>>>>   These are the 7 Zeeman pedestals, and on top of them you have the
>>>>>> Ramsay
>>>>>> fringes. You can indeed lock onto the wrong Ramsey-fringe, but they too
>>>>>> have amplitude differences. For a normal tube, they are quite
>>>>>> significant,
>>>>>> but if you look at the Ramsay fringes on the NIST-F1, they are much
>>>>>> denser
>>>>>> and looses amplitude much slower, so you need to pay more details of
>>>>>> which
>>>>>> fringe you use. The density of the Ramsay fringes is due to the
>>>>>> observation
>>>>>> time, which has been one of the driving forces to develop hydrogen
>>>>>> masers
>>>>>> and cesium fountains, but for a simple cesium tube, it's a few dm of
>>>>>> distance and the average speed of the cesium steam.
>>>>>>
>>>>>>     You can play with the C-field in addition to playing with peaks:
>>>>>>
>>>>>>   http://leapsecond.com/images/cfield.gif  (578 x 4610 pixels)
>>>>>>>
>>>>>>>
>>>>>>>   Which is a good illustration. It would be good.
>>>>>>
>>>>>>     For more details search the archives for the word Zeeman. For
>>>>>> example:
>>>>>>
>>>>>>   https://www.febo.com/pipermail/time-nuts/2005-April/018171.html
>>>>>>>
>>>>>>> A nice description from hp how a cesium beam standard works:
>>>>>>> http://leapsecond.com/museum/hp5062c/theory.htm
>>>>>>>
>>>>>>>
>>>>>>>   Do check the FTS-4065C manual as I just uploaded. Good complementary
>>>>>> information.
>>>>>>
>>>>>> Cheers,
>>>>>> Magnus
>>>>>>
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