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 <mag...@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 <
mag...@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 <
mag...@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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