[time-nuts] HP 5061Cs reference question

[Magnus Danielson]

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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