Re. DIY atomic "resonator"
Hi all.
As a first step, I wanted to build a specific hydrogen line (1.420 GHz) preamp.
Seems that some fluorescent tube starters do emit a very brief burst at around 1.4 GHz
during a specific portion of the initial switch-on surge when cold and actually observed this here.
Also relevant, this same preamp can be used for GPS and if you're living in an RF proof flat
with only one good radio station its hard to get any signal.
Has anyone else either built an atomic clock around a bare Rb lamp module "core" or attempted
to make a hydrogen maser?
It would be a fascinating project to integrate SDR as these are (with modifications) very accurate
and can be used to fine tune a lot of the oscillators etc with less hassle.
Thanks, -Andre in Guernsey
Andre
Now I know your location. So your questions make more sense to me.
With respect to home brewing atomic standards. There have been numerous
threads on time-nuts around this.
The fact is technology has obsoleted so many technologies that things like
Rb references can be had far cheaper used then home brewed. Or GPSDOs very
cheap and there is almost always a way to sneak an antenna outside. Just
have to work at it. (Been there, done that)
H masers are even more complex and again search time-nuts for details.There
have been really good threads on rebuilding used H Masers. Wow complicated!
So all of my comments are useful but the real question is what do you want
to accomplish? A good reference for your SDR. Build an atomic standard for
fun. Nothing wrong with any of these. But useful to understand your goal.
Regards
Paul
WB8TSL
On Tue, Apr 11, 2017 at 3:31 AM, Andre Andre@lanoe.net wrote:
Hi all.
As a first step, I wanted to build a specific hydrogen line (1.420 GHz)
preamp.
Seems that some fluorescent tube starters do emit a very brief burst at
around 1.4 GHz
during a specific portion of the initial switch-on surge when cold and
actually observed this here.
Also relevant, this same preamp can be used for GPS and if you're living
in an RF proof flat
with only one good radio station its hard to get any signal.
Has anyone else either built an atomic clock around a bare Rb lamp module
"core" or attempted
to make a hydrogen maser?
It would be a fascinating project to integrate SDR as these are (with
modifications) very accurate
and can be used to fine tune a lot of the oscillators etc with less hassle.
Thanks, -Andre in Guernsey
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mailman/listinfo/time-nuts
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On Tue, 11 Apr 2017 07:31:01 +0000
Andre Andre@Lanoe.net wrote:
Has anyone else either built an atomic clock around a bare Rb lamp module "core" or attempted
to make a hydrogen maser?
Building my own Rb vapor cell standard or H-maser is on my list
of Things-I-have-to-do-before-I-die :-)
If I had to do one of those now, I would go for a Rb vapor cell
with dual-resonance using an external cavity laser diode for pumping.
The electronics for such a thing are relatively easy, if you are not
afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't
cheap either. There was a discussion started by Bert[1] where I ventured
a rough calculation what I think it wold cost. Though I think I have
understimated the cost of an ECLD (it's more like 1k-5k from what I have read)
Attila Kinali
[1] search for "thinking outside the box" in the archives
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
On 4/11/2017 12:31 AM, Andre wrote:
Has anyone else either built an atomic clock around a bare Rb lamp module "core" or attempted
Not a DIY project, but I was the RF designer on the HP 10816 rubidium
standard, which never made it to product introduction (a half dozen
working pilot run units were built in 1982). I would say this task is
probably beyond the scope of a DIY project, at least for most
time-nuts. The Rb lamp drive circuit (particularly getting the
lamp to light up) is very challenging. The step recovery diode
multiplier is very challenging. The photodetector and loop
integrator is non trivial. The synthesizer is the one thing that
is easy in 2017. The oven is also no simple thing to get
low tempco. Unlike a crystal, you have a lot of heat being
generated by the lamp, etc. The lamp needs to be at a different
temperature than the other cells. You have to keep the tip
off at the lowest temperature to keep the Rb in place and not
"flood" the cell and block the light. Etc., etc.
This is in the category of projects where if you were qualified
to do it, your time is far too valuable to do it for the amount
of money you would save.
Rick N6RK
On 04/11/2017 05:54 PM, Richard (Rick) Karlquist wrote:
On 4/11/2017 12:31 AM, Andre wrote:
Has anyone else either built an atomic clock around a bare Rb lamp
module "core" or attempted
Not a DIY project, but I was the RF designer on the HP 10816 rubidium
standard, which never made it to product introduction (a half dozen
working pilot run units were built in 1982). I would say this task is
probably beyond the scope of a DIY project, at least for most
time-nuts.
Probably right.
The Rb lamp drive circuit (particularly getting the
lamp to light up) is very challenging.
There would be none. It would be replaced by a laser. That has its own
set of "problems" but different.
The step recovery diode multiplier is very challenging.
Today you would not go the SRD route in synthesis.
Besides, SRDs can be hard to find these days.
The photodetector and loop integrator is non trivial.
I'd expect the loop integrator to be done in digital, which eases up on
some of the design problems.
The synthesizer is the one thing that is easy in 2017.
Indeed-
The oven is also no simple thing to get
low tempco. Unlike a crystal, you have a lot of heat being
generated by the lamp, etc. The lamp needs to be at a different
temperature than the other cells.
Going down the laser-route, the balance of temperature between the cells
is no longer a relevant problem. Further, the lamp and its heat is gone.
You have to keep the tip
off at the lowest temperature to keep the Rb in place and not
"flood" the cell and block the light. Etc., etc.
You still have this problem, but not as a lamp problem but only for the
resonance cell part.
This is in the category of projects where if you were qualified
to do it, your time is far too valuable to do it for the amount
of money you would save.
This is the type of project you do not to save any money, but to spend
and learn.
Even if done in a much more modern fashion, avoiding several of the
traditional problems, there is plenty of issues to solve and handle.
Cheers,
Magnus
Hi
If you are going to do a Rb, probably the best place to start is with a salvaged physics
package out of one of the telecom Rb’s. That would let you get the “easy bits” worked
out on your side of the design. It would also let you lear how to address a few of the
more complex items sorted as well. Since the salvaged physics package performance
is likely better than what you would build in a basement, the performance of your device
would not be impacted in a negative way. Indeed it’s “cheating”, but it’s about the only
way to move the project forward.
I agree with Rick that Rb is by far the easiest one of the atomic devices to address. The complexity
of the device / design precision goes up quite a bit for the other candidates. To the degree
that Rb is complicated, it’s quite easy compared to the others. One way to view this is to
take a look at the minuscule size of the resonance response above the noise floor on even
a well made standard ….
Bob
On Apr 11, 2017, at 11:54 AM, Richard (Rick) Karlquist richard@karlquist.com wrote:
On 4/11/2017 12:31 AM, Andre wrote:
Has anyone else either built an atomic clock around a bare Rb lamp module "core" or attempted
Not a DIY project, but I was the RF designer on the HP 10816 rubidium
standard, which never made it to product introduction (a half dozen
working pilot run units were built in 1982). I would say this task is
probably beyond the scope of a DIY project, at least for most
time-nuts. The Rb lamp drive circuit (particularly getting the
lamp to light up) is very challenging. The step recovery diode
multiplier is very challenging. The photodetector and loop
integrator is non trivial. The synthesizer is the one thing that
is easy in 2017. The oven is also no simple thing to get
low tempco. Unlike a crystal, you have a lot of heat being
generated by the lamp, etc. The lamp needs to be at a different
temperature than the other cells. You have to keep the tip
off at the lowest temperature to keep the Rb in place and not
"flood" the cell and block the light. Etc., etc.
This is in the category of projects where if you were qualified
to do it, your time is far too valuable to do it for the amount
of money you would save.
Rick N6RK
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and follow the instructions there.
But, in the true time nuts tradition, I would expect it is time to trap an ion.
Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y
lester@veenstras.com
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Bob kb8tq
Sent: Tuesday, April 11, 2017 12:50 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Re. DIY atomic "resonator"
Hi
If you are going to do a Rb, probably the best place to start is with a salvaged physics package out of one of the telecom Rb’s. That would let you get the “easy bits” worked out on your side of the design. It would also let you lear how to address a few of the more complex items sorted as well. Since the salvaged physics package performance is likely better than what you would build in a basement, the performance of your device would not be impacted in a negative way. Indeed it’s “cheating”, but it’s about the only way to move the project forward.
I agree with Rick that Rb is by far the easiest one of the atomic devices to address. The complexity of the device / design precision goes up quite a bit for the other candidates. To the degree that Rb is complicated, it’s quite easy compared to the others. One way to view this is to take a look at the minuscule size of the resonance response above the noise floor on even a well made standard ….
Bob
YES SDRs [step Recovery Diodes] is hard to find today, but there many--
PIN -- diodes, which exhibits that effect, even some standard rectifier
diodes could be used for, despite of that Magnus is right, today are
better solutions available e.g. PLLs with 10GHz prescalers
73
KJ6UHN
Alex
On 4/11/2017 9:22 AM, Magnus Danielson wrote:
On 04/11/2017 05:54 PM, Richard (Rick) Karlquist wrote:
On 4/11/2017 12:31 AM, Andre wrote:
Has anyone else either built an atomic clock around a bare Rb lamp
module "core" or attempted
Not a DIY project, but I was the RF designer on the HP 10816 rubidium
standard, which never made it to product introduction (a half dozen
working pilot run units were built in 1982). I would say this task is
probably beyond the scope of a DIY project, at least for most
time-nuts.
Probably right.
The Rb lamp drive circuit (particularly getting the
lamp to light up) is very challenging.
There would be none. It would be replaced by a laser. That has its own
set of "problems" but different.
The step recovery diode multiplier is very challenging.
Today you would not go the SRD route in synthesis.
Besides, SRDs can be hard to find these days.
The photodetector and loop integrator is non trivial.
I'd expect the loop integrator to be done in digital, which eases up
on some of the design problems.
The synthesizer is the one thing that is easy in 2017.
Indeed-
The oven is also no simple thing to get
low tempco. Unlike a crystal, you have a lot of heat being
generated by the lamp, etc. The lamp needs to be at a different
temperature than the other cells.
Going down the laser-route, the balance of temperature between the
cells is no longer a relevant problem. Further, the lamp and its heat
is gone.
You have to keep the tip
off at the lowest temperature to keep the Rb in place and not
"flood" the cell and block the light. Etc., etc.
You still have this problem, but not as a lamp problem but only for
the resonance cell part.
This is in the category of projects where if you were qualified
to do it, your time is far too valuable to do it for the amount
of money you would save.
This is the type of project you do not to save any money, but to spend
and learn.
Even if done in a much more modern fashion, avoiding several of the
traditional problems, there is plenty of issues to solve and handle.
Cheers,
Magnus
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73
KJ6UHN
Alex
On 4/11/2017 8:29 AM, Attila Kinali wrote:
On Tue, 11 Apr 2017 07:31:01 +0000
Andre Andre@Lanoe.net wrote:
Has anyone else either built an atomic clock around a bare Rb lamp module "core" or attempted
to make a hydrogen maser?
Building my own Rb vapor cell standard or H-maser is on my list
of Things-I-have-to-do-before-I-die :-)
If I had to do one of those now, I would go for a Rb vapor cell
with dual-resonance using an external cavity laser diode for pumping.
The electronics for such a thing are relatively easy, if you are not
afraid of Jiga-Hurts and using these pesky QFN packages. But it isn't
cheap either. There was a discussion started by Bert[1] where I ventured
a rough calculation what I think it wold cost. Though I think I have
understimated the cost of an ECLD (it's more like 1k-5k from what I have read)
Attila Kinali
[1] search for "thinking outside the box" in the archives
On 4/11/17 9:22 AM, Magnus Danielson and Rick Karlquist wrote:
This is in the category of projects where if you were qualified
to do it, your time is far too valuable to do it for the amount
of money you would save.
This is the type of project you do not to save any money, but to spend
and learn.
Even if done in a much more modern fashion, avoiding several of the
traditional problems, there is plenty of issues to solve and handle.
I would agree, after watching the folks in my area doing the Cold Atom
Lab (which makes Rb Bose Einstein Condensates in a "benchtop" unit) here
at JPL. It's similar in many ways to building a Rb reference.. lasers,
Rb cells, etc.; countless things to do, to figure out, and none of them
are easy.