Zeeman frequency oddness
Since I recently got an HP Cs degausser (thanks, Stijn!), I though I'd
go through the whole setup routine for my 5061B/004 and see how close
the C-field-via-Zeeman setting would bring me to GPS-derived frequency.
It turned out to be an interesting and puzzling exercise.
This 5061 seems to be in perfect working order -- quick lock, good meter
readings, and measurements indicate frequency within parts in e12. I
don't have any reason to believe that it's not tuned or working
properly, except for the Zeeman-setting results.
The problem is that when I tune the audio source around 53.53 kHz, per
both the manual and the sticker on the door, I don't see any change in
Beam I at all. Nor do I see anything at the alternate frequency of
42.82 kHz.
Instead, I see the expected three peaks -- primary with a smaller
secondary on either side -- at about 48.21 kHz, which doesn't show up
anywhere in the literature I've found.
Below, I've cut and pasted a years-old message from TVB and Corby that
explains the Zeeman frequencies. I've measured the synthesizer output
and it's nominally 12.6317725 MHz, which per that message should
correspond to a 53.53 Zeeman. Where 48.21 kHz comes from, I have no idea.
I'm using a Rigol arbitrary function generator locked to an external
reference as the audio source, in sine wave mode. I know that's not the
cleanest device in the world, but the wave doesn't look too bad on my
scope and a counter indicates the frequency is what the dial says. As I
adjust the audio amplitude, the beam current responds, and I see a peak
at around 500mV, which the 5061B manual says is correct.
Any ideas why I might be seeing this very off-the-wall result? Could
distortion in the audio source cause something like this? I'm more
inclined to blame technique or gremlins than the 5061B -- again,
external measurements indicate that the thing is tuned correctly and
operating properly, just having this goofy Zeeman response.
Thanks!
John
[time-nuts] Zeeman frequency and cesium tube interchange
Tom Van Baak
Fri Apr 22 13:32:35 EDT 2005
Hi Brian,
The SI second is defined for mean sea level and no
external fields.
If there were no magnetic field, in theory, a cesium
tube would show a resonance when its synthesizer
generated exactly 9192.631770 MHz; the definition
of the second.
But in practice, a weak uniform magnetic field is
necessary for the beam apparatus to operate; to
isolate the center peak from the other peaks. This
DC field also has the side-effect of slightly shifting
the frequency of the center line.
Fortunately the frequency shift is a calculatable
amount (a function of magnetic field strength) so
the trick is that the synthesizer must be designed
to generate a slightly higher frequency to exactly
compensate for the shift that will be induced by
the field.
Thus the synthesizer for a 5061A does not actually
generate 9192 631 770 Hz as one might expect,
but because of the nominal 61 milligauss C-field,
the synthesizer must generate 9192 631 771.6 Hz
in order to lock onto the Cs peak precisely. The
Zeeman frequency for 61 mG is 42.82 kHz (info
from an old 5061A manual).
Other 5061A/B use a 76 mG field, corresponding
to a 53.53 kHz Zeeman frequency, and require the
synthesizer to generate 9192 631 772.5 Hz (info
from a new 5061B manual).
The short HP 5062C runs at 9192 631 774.3 Hz
with a Zeeman of 70.40 kHz.
Below is a great reply from Corby Dawson about
the problems this can cause when mixing FTS
4050, 4060, HP 5060A, 5061A, 5061B parts.
/tvb
----- Original Message -----
Tom,
The zeeman frequency required depends on two things, the magnitude of the
C-field current and the synthesizer frequency.
HP 5061A and B units that have a synthesizer freq. of 12.6317725 Mhz are
configured for a lower value of C-field current by selecting a higher
value series resistor on the A15 board. In this case any tube installed
(5061A/B 5060 4050 4060) will operate at the 53.53Khz zeeman frequency.
HP 5061A and B units and 5060A units that have a synthesizer frequency of
12.6317716 Mhz are configured for a higher C-field current due to a lower
value series resistor in the C-field circuit. In this case any installed
tube will operate with a 42.82Khz zeeman frequency.
Problems arise when synthesizer and or A15 modules are swapped around
indiscriminantly leaving a unit with modules that do not match!
Since the HP and FTS tubes C-field windings are designed to provide the
same field for a given input they are interchangeable. You can operate
any of these tubes at a 42.82 or 53.53Khz zeeman. I usually just stick
with how the mainframe came configured.
I don't remember what I ended up with as far as the zeeman freq. was
concerned when I installed a Frequency Electronics tube into a 5061A, but
do remember the line width was quite broad in keeping with the reduced
accuracy spec. of the FE tubes. (Same spec. as the 5062C tube)
I have installed FTS tubes into the 5062C giving it the +-7Z10-12th
accuracy spec. and did have to modify the synthesizer for 42.82Khz and
set the C-field accordingly.
Hope this helps!
Corby_
John
Going from what you have here and the information below it would seem to me
that there is some form of residual magnetism effecting the tube. I don't
believe the waveform of the signal has a huge effect as long as its not a
square wave. I think it can have distortion.
Its been a while but since you have an accurate reference, I believe you
can adjust the system to align to that and see what pip on the zeeman you
end up on. Perhaps you are aligning to the wrong pip. Go to either of the
lower ones and see if it works better or lines up. If it does then the math
holds and refines the question.
There was an old HP doc that evidently it was very easy to align to the
wrong pip. It was quite a problem actually.
Regards
Paul
WB8TSL
On Sat, Oct 27, 2012 at 3:16 PM, John Ackermann N8UR jra@febo.com wrote:
Since I recently got an HP Cs degausser (thanks, Stijn!), I though I'd go
through the whole setup routine for my 5061B/004 and see how close the
C-field-via-Zeeman setting would bring me to GPS-derived frequency. It
turned out to be an interesting and puzzling exercise.
This 5061 seems to be in perfect working order -- quick lock, good meter
readings, and measurements indicate frequency within parts in e12. I don't
have any reason to believe that it's not tuned or working properly, except
for the Zeeman-setting results.
The problem is that when I tune the audio source around 53.53 kHz, per
both the manual and the sticker on the door, I don't see any change in Beam
I at all. Nor do I see anything at the alternate frequency of 42.82 kHz.
Instead, I see the expected three peaks -- primary with a smaller
secondary on either side -- at about 48.21 kHz, which doesn't show up
anywhere in the literature I've found.
Below, I've cut and pasted a years-old message from TVB and Corby that
explains the Zeeman frequencies. I've measured the synthesizer output and
it's nominally 12.6317725 MHz, which per that message should correspond to
a 53.53 Zeeman. Where 48.21 kHz comes from, I have no idea.
I'm using a Rigol arbitrary function generator locked to an external
reference as the audio source, in sine wave mode. I know that's not the
cleanest device in the world, but the wave doesn't look too bad on my scope
and a counter indicates the frequency is what the dial says. As I adjust
the audio amplitude, the beam current responds, and I see a peak at around
500mV, which the 5061B manual says is correct.
Any ideas why I might be seeing this very off-the-wall result? Could
distortion in the audio source cause something like this? I'm more
inclined to blame technique or gremlins than the 5061B -- again, external
measurements indicate that the thing is tuned correctly and operating
properly, just having this goofy Zeeman response.
Thanks!
John
[time-nuts] Zeeman frequency and cesium tube interchange
Tom Van Baak
Fri Apr 22 13:32:35 EDT 2005
Hi Brian,
The SI second is defined for mean sea level and no
external fields.
If there were no magnetic field, in theory, a cesium
tube would show a resonance when its synthesizer
generated exactly 9192.631770 MHz; the definition
of the second.
But in practice, a weak uniform magnetic field is
necessary for the beam apparatus to operate; to
isolate the center peak from the other peaks. This
DC field also has the side-effect of slightly shifting
the frequency of the center line.
Fortunately the frequency shift is a calculatable
amount (a function of magnetic field strength) so
the trick is that the synthesizer must be designed
to generate a slightly higher frequency to exactly
compensate for the shift that will be induced by
the field.
Thus the synthesizer for a 5061A does not actually
generate 9192 631 770 Hz as one might expect,
but because of the nominal 61 milligauss C-field,
the synthesizer must generate 9192 631 771.6 Hz
in order to lock onto the Cs peak precisely. The
Zeeman frequency for 61 mG is 42.82 kHz (info
from an old 5061A manual).
Other 5061A/B use a 76 mG field, corresponding
to a 53.53 kHz Zeeman frequency, and require the
synthesizer to generate 9192 631 772.5 Hz (info
from a new 5061B manual).
The short HP 5062C runs at 9192 631 774.3 Hz
with a Zeeman of 70.40 kHz.
Below is a great reply from Corby Dawson about
the problems this can cause when mixing FTS
4050, 4060, HP 5060A, 5061A, 5061B parts.
/tvb
----- Original Message -----
Tom,
The zeeman frequency required depends on two things, the magnitude of the
C-field current and the synthesizer frequency.
HP 5061A and B units that have a synthesizer freq. of 12.6317725 Mhz are
configured for a lower value of C-field current by selecting a higher
value series resistor on the A15 board. In this case any tube installed
(5061A/B 5060 4050 4060) will operate at the 53.53Khz zeeman frequency.
HP 5061A and B units and 5060A units that have a synthesizer frequency of
12.6317716 Mhz are configured for a higher C-field current due to a lower
value series resistor in the C-field circuit. In this case any installed
tube will operate with a 42.82Khz zeeman frequency.
Problems arise when synthesizer and or A15 modules are swapped around
indiscriminantly leaving a unit with modules that do not match!
Since the HP and FTS tubes C-field windings are designed to provide the
same field for a given input they are interchangeable. You can operate
any of these tubes at a 42.82 or 53.53Khz zeeman. I usually just stick
with how the mainframe came configured.
I don't remember what I ended up with as far as the zeeman freq. was
concerned when I installed a Frequency Electronics tube into a 5061A, but
do remember the line width was quite broad in keeping with the reduced
accuracy spec. of the FE tubes. (Same spec. as the 5062C tube)
I have installed FTS tubes into the 5062C giving it the +-7Z10-12th
accuracy spec. and did have to modify the synthesizer for 42.82Khz and
set the C-field accordingly.
Hope this helps!
Corby_
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and follow the instructions there.
Hi John,
Don't know if I address your real issues, but I want to add some more
pieces to the puzzle.
On 10/27/2012 09:16 PM, John Ackermann N8UR wrote:
Since I recently got an HP Cs degausser (thanks, Stijn!), I though I'd
go through the whole setup routine for my 5061B/004 and see how close
the C-field-via-Zeeman setting would bring me to GPS-derived frequency.
It turned out to be an interesting and puzzling exercise.
This 5061 seems to be in perfect working order -- quick lock, good meter
readings, and measurements indicate frequency within parts in e12. I
don't have any reason to believe that it's not tuned or working
properly, except for the Zeeman-setting results.
The problem is that when I tune the audio source around 53.53 kHz, per
both the manual and the sticker on the door, I don't see any change in
Beam I at all. Nor do I see anything at the alternate frequency of 42.82
kHz.
Instead, I see the expected three peaks -- primary with a smaller
secondary on either side -- at about 48.21 kHz, which doesn't show up
anywhere in the literature I've found.
There are in total 7 peaks, you want the center peak of those.
Tom has made measurements:
http://leapsecond.com/images/cfield.gif
I have done the same to one of my tubes, but I don't recall where I have
that flimsy picture, so the above is a good start.
Below, I've cut and pasted a years-old message from TVB and Corby that
explains the Zeeman frequencies. I've measured the synthesizer output
and it's nominally 12.6317725 MHz, which per that message should
correspond to a 53.53 Zeeman. Where 48.21 kHz comes from, I have no idea.
The separation of the peaks depends on the C-field value you have.
For low C-field strength, the side-peaks separate my the square of the
C-field (B), and the cluster shifts gently linear with the C-field.
You want to spread the side-peaks out, such that they do not confuse
your measures. Also, looking at the above you have the 7 Rabi
distributions, and on top of those the Ramsay fringes, at which you want
to lock onto the center one. It may be interesting to learn that certain
systematics skews the shape of these, and thus causes a systematic
miss-tuning, so great care is taken to reduce that effect when
manufacturing the tube.
Look at the above C-field plot again and you see how the side features
move with different C-field settings.
Modern "digital" caesium clocks measure the side-features in order to
Servo the C-field into a stable value, and hence also stabilize C-field
drift out of the equation first degree.
I'm using a Rigol arbitrary function generator locked to an external
reference as the audio source, in sine wave mode. I know that's not the
cleanest device in the world, but the wave doesn't look too bad on my
scope and a counter indicates the frequency is what the dial says. As I
adjust the audio amplitude, the beam current responds, and I see a peak
at around 500mV, which the 5061B manual says is correct.
Any ideas why I might be seeing this very off-the-wall result? Could
distortion in the audio source cause something like this? I'm more
inclined to blame technique or gremlins than the 5061B -- again,
external measurements indicate that the thing is tuned correctly and
operating properly, just having this goofy Zeeman response.
You want a clean source, as spurs or distortion would cause you to look
at multiple points in the spectrum at the same time and you would get
the combined result of those features. Still, the distortion values
doesn't have to be stellar to get decent readings.
Cheers,
Magnus
Two things come to mind:
- is this the high performance tube? Perhaps it has a different
Zeeman frequency than the standard tube? - a non HP replacement tube? FTS Cs beam tubes are way different
Zeeman frequencies than HP.
-Chuck Harris
John Ackermann N8UR wrote:
Since I recently got an HP Cs degausser (thanks, Stijn!), I though I'd go through the
whole setup routine for my 5061B/004 and see how close the C-field-via-Zeeman setting
would bring me to GPS-derived frequency. It turned out to be an interesting and
puzzling exercise.
This 5061 seems to be in perfect working order -- quick lock, good meter readings,
and measurements indicate frequency within parts in e12. I don't have any reason to
believe that it's not tuned or working properly, except for the Zeeman-setting results.
The problem is that when I tune the audio source around 53.53 kHz, per both the
manual and the sticker on the door, I don't see any change in Beam I at all. Nor do
I see anything at the alternate frequency of 42.82 kHz.
Instead, I see the expected three peaks -- primary with a smaller secondary on either
side -- at about 48.21 kHz, which doesn't show up anywhere in the literature I've found.
Below, I've cut and pasted a years-old message from TVB and Corby that explains the
Zeeman frequencies. I've measured the synthesizer output and it's nominally
12.6317725 MHz, which per that message should correspond to a 53.53 Zeeman. Where
48.21 kHz comes from, I have no idea.
I'm using a Rigol arbitrary function generator locked to an external reference as the
audio source, in sine wave mode. I know that's not the cleanest device in the world,
but the wave doesn't look too bad on my scope and a counter indicates the frequency
is what the dial says. As I adjust the audio amplitude, the beam current responds,
and I see a peak at around 500mV, which the 5061B manual says is correct.
Any ideas why I might be seeing this very off-the-wall result? Could distortion in
the audio source cause something like this? I'm more inclined to blame technique or
gremlins than the 5061B -- again, external measurements indicate that the thing is
tuned correctly and operating properly, just having this goofy Zeeman response.
Thanks!
John
[time-nuts] Zeeman frequency and cesium tube interchange
Tom Van Baak
Fri Apr 22 13:32:35 EDT 2005
Hi Brian,
The SI second is defined for mean sea level and no
external fields.
If there were no magnetic field, in theory, a cesium
tube would show a resonance when its synthesizer
generated exactly 9192.631770 MHz; the definition
of the second.
But in practice, a weak uniform magnetic field is
necessary for the beam apparatus to operate; to
isolate the center peak from the other peaks. This
DC field also has the side-effect of slightly shifting
the frequency of the center line.
Fortunately the frequency shift is a calculatable
amount (a function of magnetic field strength) so
the trick is that the synthesizer must be designed
to generate a slightly higher frequency to exactly
compensate for the shift that will be induced by
the field.
Thus the synthesizer for a 5061A does not actually
generate 9192 631 770 Hz as one might expect,
but because of the nominal 61 milligauss C-field,
the synthesizer must generate 9192 631 771.6 Hz
in order to lock onto the Cs peak precisely. The
Zeeman frequency for 61 mG is 42.82 kHz (info
from an old 5061A manual).
Other 5061A/B use a 76 mG field, corresponding
to a 53.53 kHz Zeeman frequency, and require the
synthesizer to generate 9192 631 772.5 Hz (info
from a new 5061B manual).
The short HP 5062C runs at 9192 631 774.3 Hz
with a Zeeman of 70.40 kHz.
Below is a great reply from Corby Dawson about
the problems this can cause when mixing FTS
4050, 4060, HP 5060A, 5061A, 5061B parts.
/tvb
----- Original Message -----
Tom,
The zeeman frequency required depends on two things, the magnitude of the
C-field current and the synthesizer frequency.
HP 5061A and B units that have a synthesizer freq. of 12.6317725 Mhz are
configured for a lower value of C-field current by selecting a higher
value series resistor on the A15 board. In this case any tube installed
(5061A/B 5060 4050 4060) will operate at the 53.53Khz zeeman frequency.
HP 5061A and B units and 5060A units that have a synthesizer frequency of
12.6317716 Mhz are configured for a higher C-field current due to a lower
value series resistor in the C-field circuit. In this case any installed
tube will operate with a 42.82Khz zeeman frequency.
Problems arise when synthesizer and or A15 modules are swapped around
indiscriminantly leaving a unit with modules that do not match!
Since the HP and FTS tubes C-field windings are designed to provide the
same field for a given input they are interchangeable. You can operate
any of these tubes at a 42.82 or 53.53Khz zeeman. I usually just stick
with how the mainframe came configured.
I don't remember what I ended up with as far as the zeeman freq. was
concerned when I installed a Frequency Electronics tube into a 5061A, but
do remember the line width was quite broad in keeping with the reduced
accuracy spec. of the FE tubes. (Same spec. as the 5062C tube)
I have installed FTS tubes into the 5062C giving it the +-7Z10-12th
accuracy spec. and did have to modify the synthesizer for 42.82Khz and
set the C-field accordingly.
Hope this helps!
Corby_
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
John,
Did you do the Zeeman frequency adjustment before doing the 'degauss'? In
other words, did you 'magnetize' rather than 'de-magnetize'?
Have you checked the A15 board to make sure it has the correct resistor and
current? I have a 5061B Service Manual if you need some sections or
schematics.
Good luck.
Joe
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of John Ackermann N8UR
Sent: Saturday, October 27, 2012 2:16 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Zeeman frequency oddness
Since I recently got an HP Cs degausser (thanks, Stijn!), I though I'd
go through the whole setup routine for my 5061B/004 and see how close
the C-field-via-Zeeman setting would bring me to GPS-derived frequency.
It turned out to be an interesting and puzzling exercise.
This 5061 seems to be in perfect working order -- quick lock, good meter
readings, and measurements indicate frequency within parts in e12. I
don't have any reason to believe that it's not tuned or working
properly, except for the Zeeman-setting results.
The problem is that when I tune the audio source around 53.53 kHz, per
both the manual and the sticker on the door, I don't see any change in
Beam I at all. Nor do I see anything at the alternate frequency of
42.82 kHz.
Instead, I see the expected three peaks -- primary with a smaller
secondary on either side -- at about 48.21 kHz, which doesn't show up
anywhere in the literature I've found.
Below, I've cut and pasted a years-old message from TVB and Corby that
explains the Zeeman frequencies. I've measured the synthesizer output
and it's nominally 12.6317725 MHz, which per that message should
correspond to a 53.53 Zeeman. Where 48.21 kHz comes from, I have no idea.
I'm using a Rigol arbitrary function generator locked to an external
reference as the audio source, in sine wave mode. I know that's not the
cleanest device in the world, but the wave doesn't look too bad on my
scope and a counter indicates the frequency is what the dial says. As I
adjust the audio amplitude, the beam current responds, and I see a peak
at around 500mV, which the 5061B manual says is correct.
Any ideas why I might be seeing this very off-the-wall result? Could
distortion in the audio source cause something like this? I'm more
inclined to blame technique or gremlins than the 5061B -- again,
external measurements indicate that the thing is tuned correctly and
operating properly, just having this goofy Zeeman response.
Thanks!
John
[time-nuts] Zeeman frequency and cesium tube interchange
Tom Van Baak
Fri Apr 22 13:32:35 EDT 2005
Hi Brian,
The SI second is defined for mean sea level and no
external fields.
If there were no magnetic field, in theory, a cesium
tube would show a resonance when its synthesizer
generated exactly 9192.631770 MHz; the definition
of the second.
But in practice, a weak uniform magnetic field is
necessary for the beam apparatus to operate; to
isolate the center peak from the other peaks. This
DC field also has the side-effect of slightly shifting
the frequency of the center line.
Fortunately the frequency shift is a calculatable
amount (a function of magnetic field strength) so
the trick is that the synthesizer must be designed
to generate a slightly higher frequency to exactly
compensate for the shift that will be induced by
the field.
Thus the synthesizer for a 5061A does not actually
generate 9192 631 770 Hz as one might expect,
but because of the nominal 61 milligauss C-field,
the synthesizer must generate 9192 631 771.6 Hz
in order to lock onto the Cs peak precisely. The
Zeeman frequency for 61 mG is 42.82 kHz (info
from an old 5061A manual).
Other 5061A/B use a 76 mG field, corresponding
to a 53.53 kHz Zeeman frequency, and require the
synthesizer to generate 9192 631 772.5 Hz (info
from a new 5061B manual).
The short HP 5062C runs at 9192 631 774.3 Hz
with a Zeeman of 70.40 kHz.
Below is a great reply from Corby Dawson about
the problems this can cause when mixing FTS
4050, 4060, HP 5060A, 5061A, 5061B parts.
/tvb
----- Original Message -----
Tom,
The zeeman frequency required depends on two things, the magnitude of the
C-field current and the synthesizer frequency.
HP 5061A and B units that have a synthesizer freq. of 12.6317725 Mhz are
configured for a lower value of C-field current by selecting a higher
value series resistor on the A15 board. In this case any tube installed
(5061A/B 5060 4050 4060) will operate at the 53.53Khz zeeman frequency.
HP 5061A and B units and 5060A units that have a synthesizer frequency of
12.6317716 Mhz are configured for a higher C-field current due to a lower
value series resistor in the C-field circuit. In this case any installed
tube will operate with a 42.82Khz zeeman frequency.
Problems arise when synthesizer and or A15 modules are swapped around
indiscriminantly leaving a unit with modules that do not match!
Since the HP and FTS tubes C-field windings are designed to provide the
same field for a given input they are interchangeable. You can operate
any of these tubes at a 42.82 or 53.53Khz zeeman. I usually just stick
with how the mainframe came configured.
I don't remember what I ended up with as far as the zeeman freq. was
concerned when I installed a Frequency Electronics tube into a 5061A, but
do remember the line width was quite broad in keeping with the reduced
accuracy spec. of the FE tubes. (Same spec. as the 5062C tube)
I have installed FTS tubes into the 5062C giving it the +-7Z10-12th
accuracy spec. and did have to modify the synthesizer for 42.82Khz and
set the C-field accordingly.
Hope this helps!
Corby_
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On 10/28/2012 01:13 AM, Chuck Harris wrote:
Two things come to mind:
- is this the high performance tube? Perhaps it has a different
Zeeman frequency than the standard tube? - a non HP replacement tube? FTS Cs beam tubes are way different
Zeeman frequencies than HP.
A high performance tube should give you better signal to noise.
A non HP tube might give you a somewhat different C-field setting for
same center lock-in.
The physics of Cs-133 is still the same, and the RF-chain is still the
same. If not, someone has to teach me something new, or at least inform
me why the high performance tubes are so much different.
Cheers,
Magnus
Is there perhaps a hemisphere jumper for the sign of nulling fields?
-John
==========
On 10/28/2012 01:13 AM, Chuck Harris wrote:
Two things come to mind:
- is this the high performance tube? Perhaps it has a different
Zeeman frequency than the standard tube? - a non HP replacement tube? FTS Cs beam tubes are way different
Zeeman frequencies than HP.
A high performance tube should give you better signal to noise.
A non HP tube might give you a somewhat different C-field setting for
same center lock-in.
The physics of Cs-133 is still the same, and the RF-chain is still the
same. If not, someone has to teach me something new, or at least inform
me why the high performance tubes are so much different.
Cheers,
Magnus
time-nuts mailing list -- time-nuts@febo.com
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https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Magnus Danielson wrote:
On 10/28/2012 01:13 AM, Chuck Harris wrote:
Two things come to mind:
- is this the high performance tube? Perhaps it has a different
Zeeman frequency than the standard tube? - a non HP replacement tube? FTS Cs beam tubes are way different
Zeeman frequencies than HP.
A high performance tube should give you better signal to noise.
A non HP tube might give you a somewhat different C-field setting for same center
lock-in.
The FTS tubes in my 4050 have a Zeeman frequency of around 43KHz, which if
my estimate is right is about 10KHz different from the HP Zeeman frequency
of around 53KHz. And as I recall, the little HP submarine C-Beam has yet
another Zeeman frequency, but I can't dig up its manual at the moment.
AFAIK, the Zeeman frequency is very much dependent on the architecture of
the particular physics package.
-Chuck Harris
The physics of Cs-133 is still the same, and the RF-chain is still the same. If not,
someone has to teach me something new, or at least inform me why the high performance
tubes are so much different.
Cheers,
Magnus
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and follow the instructions there.
Chuck,
Information about the HP submarine cesium standard (5062c) as well as details about Zeeman splitting are here:
http://www.leapsecond.com/museum/hp5062c/theory.htm
/tvb (iPhone4)
On Oct 28, 2012, at 1:25 AM, Chuck Harris cfharris@erols.com wrote:
Magnus Danielson wrote:
On 10/28/2012 01:13 AM, Chuck Harris wrote:
Two things come to mind:
- is this the high performance tube? Perhaps it has a different
Zeeman frequency than the standard tube? - a non HP replacement tube? FTS Cs beam tubes are way different
Zeeman frequencies than HP.
A high performance tube should give you better signal to noise.
A non HP tube might give you a somewhat different C-field setting for same center
lock-in.
The FTS tubes in my 4050 have a Zeeman frequency of around 43KHz, which if
my estimate is right is about 10KHz different from the HP Zeeman frequency
of around 53KHz. And as I recall, the little HP submarine C-Beam has yet
another Zeeman frequency, but I can't dig up its manual at the moment.
AFAIK, the Zeeman frequency is very much dependent on the architecture of
the particular physics package.
-Chuck Harris
The physics of Cs-133 is still the same, and the RF-chain is still the same. If not,
someone has to teach me something new, or at least inform me why the high performance
tubes are so much different.
Cheers,
Magnus
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Cs tube ADEV is related to S/N ratio which is dependent on beam flux (the formula is in any quantum physics textbook).To achieve higher beam currents high-perf tubes run the oven at a higher temp (which is why their lifetime is much shorter).
So yes the RF chain is the same. But the oven controller set point is different and the E/M may be configured differently to accommodate the higher signal levels.
/tvb (iPhone4)
On Oct 27, 2012, at 8:07 PM, Magnus Danielson magnus@rubidium.dyndns.org wrote:
On 10/28/2012 01:13 AM, Chuck Harris wrote:
Two things come to mind:
- is this the high performance tube? Perhaps it has a different
Zeeman frequency than the standard tube? - a non HP replacement tube? FTS Cs beam tubes are way different
Zeeman frequencies than HP.
A high performance tube should give you better signal to noise.
A non HP tube might give you a somewhat different C-field setting for same center lock-in.
The physics of Cs-133 is still the same, and the RF-chain is still the same. If not, someone has to teach me something new, or at least inform me why the high performance tubes are so much different.
Cheers,
Magnus
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.