Re: [time-nuts] Re. DIY atomic "resonator"

[Magnus Danielson]

Hi,

On that note we have Rick Karlquists article showing how he replaced the 
traditional syntheis chain with an oscillator at the target frequency, 
locked to the lower frequency. Benefit is in the phase-noise.

This was from the fine work on the 5071A.

This approach can be used for rubidiums too, if you care about phase 
noise going into the cavity.


The traditional chain has essentially only one oscillator, but one leg 
in the synthesis chain has a phase-modulation with the modulation 
frequency for the sensing of the atomic reference.


Cheers,
Magnus

On 04/13/2017 01:19 AM, Bob kb8tq wrote:

Hi

There are papers from the mid 90’s talking about improving the GPS Rb’s. Those 
parts are
as far as I know the best “production” Rb’s out there. The main comment seems 
to be that
phase noise (in it’s various forms) is a major contributor to the stability of 
the Rb’s….

Bob


On Apr 12, 2017, at 4:55 PM, Bert Kehren via time-nuts  
wrote:

Looking back at the dialog I started on Rb’s  and the repeated returns to
that subject allow me to make some comments,  observations and
recommendations.. I stayed on purpose away from participating  but learned a 
lot. It also
resulted in some off list dialogs with members  working on the subject off
list.
Rick’s discussion on why to use two  frequencies was for me an eye opener
and gives me clear directions on how to  proceed on frequency generation. The
single frequency project is dumped. Corby’s  work on filters again
influences our future steps. Using a laser diode and its  challenges again an 
eye
opener and a challenge. We have time nuts that have  working systems.
Let’s be honest, we have members with super  knowledge but very few have
the appetite to do something with it in the form of  hardware. Here is my
proposal that is based on walk before run.
FRK and M100 are next to the HP 5065A the  most promising Rb’s in what we
like to do. They are easy to work on specially  when you are 75/78 and in my
case have a macular  hole.
Optical Filter. Corby actually did insert a  filter in a M100 did however
not notice an improvement. When we discussed it  come to find out he forgot
to change the time constant so the cell did not  control the performance.
This was years ago and like many of us has his hands  full with projects. He
decided to pass his M100/FRK to an other time nut and  focus on HP and Maser.
We all benefit from these  efforts.
Back to filter we have dissected a FRK and a  M100 and are convinced that
there is a room for a filter, in case of the FRK,  very easy. Corby used a
M100, in my opinion more of a challenge. Will not try  it. After discussions
with Corby I now understand that the filter does not  filter out a particular
wavelength but most the noise that Rb lamps produce as  seen on optical
spectrum analyzers. It improves signal noise ratio after all  that is what is
all about. Once we have completed our current projects we may do  so.
We are also considering to review the  frequency generation using Rick’s
postings as guidance. All this needs measuring  capabilities which is what we
are working on. I am fortunate to have access to  Corby’s Maser but Juerg
does not have that. We are working on a solution.
There are many FRK/M100’s out there some  with low output lamps that would
be a natural for a Laser Diode replacement. The  mechanical makeup begs for
a Laser solution. The two units have a cell in size  only second to HP5065A
Going to  laser would also allow to reduce cell temperature again
contributing to an  improved signal noise ratio,
This is way off our expertise but it would  be nice if some one would take
the ball and run with it. I am convinced from off  list conversations that
$1000 is a reasonable  goal.
There is no guarantee that we will do the  filter depending what our
results will be on our present work so again maybe  some one would carry that
ball.
Both can be a first step for future work.  WALK
Bert Kehren


In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,
att...@kinali.ch writes:

On Tue,  11 Apr 2017 07:31:01 +
Andre  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 

Re: [time-nuts] Re. DIY atomic "resonator"

[Bruce Griffiths]

Typically External Cavity diode lasers use either the Littrow or the 
Littman-Metcalf configurations.

A typical Littrow configuration is:

http://www.moglabs.com/uploads/2/4/2/1/24212474/manual_ecd_rev4.20.pdf

Alternatively a cat eye external cavity can be used:

http://www.moglabs.com/uploads/2/4/2/1/24212474/moglabs_cel002_manual_rev108.pdf

To assist with tuning the laser a wavemeter is helpful:

http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/31/004/31004208.pdf

Other variants based on optical wedges or even a simple grating can also be 
used together with a CCD camera or equivalent to achieve an accuracy 
approaching a few pm.

Whilst AR coated laser diodes work best its also possible to use uncoated laser 
diodes.

Such diodes have been successfully used for atomic spectroscopy of rubidium 
vapour by several groups.

Temperature control of the laser diode and cavity are the most critical issues.

One can easily adapt standard optical mounts to make one's own ECDL but 
temperature control is critical for use in a rubidium standard.

Locking the laser to the absorption line of interest relaxes the required long 
term stability of the ECDL itself.  

Bruce

> 
> On 13 April 2017 at 08:55 Bert Kehren via time-nuts  
> wrote:
> 
> Looking back at the dialog I started on Rb’s and the repeated returns to
> that subject allow me to make some comments, observations and
> recommendations.. I stayed on purpose away from participating but learned 
> a lot. It also
> resulted in some off list dialogs with members working on the subject off
> list.
> Rick’s discussion on why to use two frequencies was for me an eye opener
> and gives me clear directions on how to proceed on frequency generation. 
> The
> single frequency project is dumped. Corby’s work on filters again
> influences our future steps. Using a laser diode and its challenges again 
> an eye
> opener and a challenge. We have time nuts that have working systems.
> Let’s be honest, we have members with super knowledge but very few have
> the appetite to do something with it in the form of hardware. Here is my
> proposal that is based on walk before run.
> FRK and M100 are next to the HP 5065A the most promising Rb’s in what we
> like to do. They are easy to work on specially when you are 75/78 and in 
> my
> case have a macular hole.
> Optical Filter. Corby actually did insert a filter in a M100 did however
> not notice an improvement. When we discussed it come to find out he forgot
> to change the time constant so the cell did not control the performance.
> This was years ago and like many of us has his hands full with projects. 
> He
> decided to pass his M100/FRK to an other time nut and focus on HP and 
> Maser.
> We all benefit from these efforts.
> Back to filter we have dissected a FRK and a M100 and are convinced that
> there is a room for a filter, in case of the FRK, very easy. Corby used a
> M100, in my opinion more of a challenge. Will not try it. After 
> discussions
> with Corby I now understand that the filter does not filter out a 
> particular
> wavelength but most the noise that Rb lamps produce as seen on optical
> spectrum analyzers. It improves signal noise ratio after all that is what 
> is
> all about. Once we have completed our current projects we may do so.
> We are also considering to review the frequency generation using Rick’s
> postings as guidance. All this needs measuring capabilities which is what 
> we
> are working on. I am fortunate to have access to Corby’s Maser but Juerg
> does not have that. We are working on a solution.
> There are many FRK/M100’s out there some with low output lamps that would
> be a natural for a Laser Diode replacement. The mechanical makeup begs for
> a Laser solution. The two units have a cell in size only second to HP5065A
> Going to laser would also allow to reduce cell temperature again
> contributing to an improved signal noise ratio,
> This is way off our expertise but it would be nice if some one would take
> the ball and run with it. I am convinced from off list conversations that
> $1000 is a reasonable goal.
> There is no guarantee that we will do the filter depending what our
> results will be on our present work so again maybe some one would carry 
> that
> ball.
> Both can be a first step for future work. WALK
> Bert Kehren
> 
> In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,
> att...@kinali.ch writes:
> 
> On Tue, 11 Apr 2017 07:31:01 +
> Andre  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 

Re: [time-nuts] Re. DIY atomic "resonator"

[Scott McGrath]

One of the challenges with todays new WiFi standards i.e. 802.11ac/ad/ax is the 
doppler from office fluorescent lighting systems so much so that channel 
emulators like the Anite Propsim F8 emulate it at various pseudoranges to the 
AP and STA

That said old school noise sources were indeed gas discharge tubes

> On Apr 12, 2017, at 2:18 PM, jimlux <jim...@earthlink.net> wrote:
> 
>> On 4/12/17 10:28 AM, Dave B via time-nuts wrote:
>>> On 12/04/17 17:00, jimlux wrote:
>>> 
>>> Subject: Re: [time-nuts] Re. DIY atomic "resonator"
>>> Message-ID: <b3926cda-b4ff-2508-1be6-57c2fecf0...@earthlink.net>
>>> Content-Type: text/plain; charset=utf-8; format=flowed
>>> 
>>>> On 4/11/17 11:09 AM, Mark Sims wrote:
>>>> Apparently fluorescent tubes continuously emit a lot of other microwave 
>>>> signals.  I once built a  homodyne doppler "speed" radar kit (used a 
>>>> coffee can for the antenna).  The way you calibrated it was to point it at 
>>>> a florescent tube and and adjust the reading to a specific value.
>>>> 
>>>> --
>>> That's not because the tube is emitting..  It's a target reflector
>>> turning on and off at twice line frequency.
>>> In most homodyne radars, you filter out the DC (the reflections from
>>> stuff that's not moving), so anything that pulses on and off creates
>>> nice output.
>> 
>> This patent would seem to confirm that discharge tubes do generate
>> microwave noise, and with a DC powered tube too.  (Would different
>> gasses produce different microwave spectra?)
>> 
>> http://www.google.co.uk/patents/US2942204
> 
> They generate broadband noise - they're used as high power noise sources for 
> calibration.
> 
> Bracewell (I believe) used fluorescent tubes (driven by a reasonably stable 
> source) as a calibration and timing reference at a astronomy array -
> http://articles.adsabs.harvard.edu//full/2005JAHH8...75B/077.000.html
> 
> R. Bracewell and G. Swarup, "The Stanford microwave spectroheliograph 
> antenna, a microsteradian pencil beam interferometer," in IRE Transactions on 
> Antennas and Propagation, vol. 9, no. 1, pp. 22-30, January 1961.
> doi: 10.1109/TAP.1961.1144935
> 
> I particularly like the inclusion of "milling machines" in the keyword list
> keywords: {Microwave interferometry;Planar arrays;Radio telescopes;Reflector 
> antennas, arrays;Solar radiation;Brightness 
> temperature;Corona;Frequency;Microwave antennas;Milling 
> machines;Monitoring;Moon;Phase modulation;Sun;TV}
> 
> And fluorescent tubes have been used as a broad band source in a classroom 
> demo
> https://www.researchgate.net/publication/276280926_Demonstrating_the_Principles_of_Aperture_Synthesis_with_the_Very_Small_Radio_Telescope
> 
> 
> 
> I would suspect that the radiated field has some spectral bumps in it, 
> probably related the physical dimensions.  I doubt it would have any discrete 
> lines (although maybe it does..)
> 
> 
> 
> 
> 
>> 
>> I recall seeing such things sold surplus back in the early 70's, pity I
>> didn't know what they were back then.
> 
> There are also gas tubes in waveguides used as Radar T/R switches. when the 
> main bang happens, the tube ionizes shorting the waveguide and protecting the 
> receiver downstream.
> 
> 
>> 
>> There is also mention of huge mismatches in the guide when the tube was
>> not powered, that would support the homodyne speed calibration comment
>> by pointing it at a working (AC powered) florescent tube.  As Jim said,
>> a 100 (or 120) Hz "modulated reflector."
> 
> Yep.  There's been a fair amount of work over the past decades on using 
> modulated reflectors for measuring antenna patterns (e.g. on phased arrays).  
> You can have a diode/dipole suspended by resistive leads (with an impedance 
> of 377 ohms/square that are invisible) and turn it on and off.
> 
> Bolomey (I think) had an array of modulated reflectors, so you could measure 
> multiple points in the near field at the same time, and only need to scan in 
> one dimension. I can't remember if the reflectors were modulated at different 
> rates or with PN codes - either would work to separate the responses.
> 
> 
>> 
>> Regards to All.
>> 
>> Dave G0WBX (or G8KBV both still valid.)
>> 
>> ~~~
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
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>> and follow the instructions there.
>> 
> 
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Re: [time-nuts] Re. DIY atomic "resonator"

[Bob kb8tq]

Hi

There are papers from the mid 90’s talking about improving the GPS Rb’s. Those 
parts are 
as far as I know the best “production” Rb’s out there. The main comment seems 
to be that 
phase noise (in it’s various forms) is a major contributor to the stability of 
the Rb’s….

Bob

> On Apr 12, 2017, at 4:55 PM, Bert Kehren via time-nuts  
> wrote:
> 
> Looking back at the dialog I started on Rb’s  and the repeated returns to 
> that subject allow me to make some comments,  observations and 
> recommendations.. I stayed on purpose away from participating  but learned a 
> lot. It also 
> resulted in some off list dialogs with members  working on the subject off 
> list.  
> Rick’s discussion on why to use two  frequencies was for me an eye opener 
> and gives me clear directions on how to  proceed on frequency generation. The 
> single frequency project is dumped. Corby’s  work on filters again 
> influences our future steps. Using a laser diode and its  challenges again an 
> eye 
> opener and a challenge. We have time nuts that have  working systems. 
> Let’s be honest, we have members with super  knowledge but very few have 
> the appetite to do something with it in the form of  hardware. Here is my 
> proposal that is based on walk before run.   
> FRK and M100 are next to the HP 5065A the  most promising Rb’s in what we 
> like to do. They are easy to work on specially  when you are 75/78 and in my 
> case have a macular  hole. 
> Optical Filter. Corby actually did insert a  filter in a M100 did however 
> not notice an improvement. When we discussed it  come to find out he forgot 
> to change the time constant so the cell did not  control the performance. 
> This was years ago and like many of us has his hands  full with projects. He 
> decided to pass his M100/FRK to an other time nut and  focus on HP and Maser. 
> We all benefit from these  efforts. 
> Back to filter we have dissected a FRK and a  M100 and are convinced that 
> there is a room for a filter, in case of the FRK,  very easy. Corby used a 
> M100, in my opinion more of a challenge. Will not try  it. After discussions 
> with Corby I now understand that the filter does not  filter out a particular 
> wavelength but most the noise that Rb lamps produce as  seen on optical 
> spectrum analyzers. It improves signal noise ratio after all  that is what is 
> all about. Once we have completed our current projects we may do  so. 
> We are also considering to review the  frequency generation using Rick’s 
> postings as guidance. All this needs measuring  capabilities which is what we 
> are working on. I am fortunate to have access to  Corby’s Maser but Juerg 
> does not have that. We are working on a solution.   
> There are many FRK/M100’s out there some  with low output lamps that would 
> be a natural for a Laser Diode replacement. The  mechanical makeup begs for 
> a Laser solution. The two units have a cell in size  only second to HP5065A  
> Going to  laser would also allow to reduce cell temperature again 
> contributing to an  improved signal noise ratio, 
> This is way off our expertise but it would  be nice if some one would take 
> the ball and run with it. I am convinced from off  list conversations that 
> $1000 is a reasonable  goal. 
> There is no guarantee that we will do the  filter depending what our 
> results will be on our present work so again maybe  some one would carry that 
> ball. 
> Both can be a first step for future work.  WALK
> Bert Kehren
> 
> 
> In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,  
> att...@kinali.ch writes:
> 
> On Tue,  11 Apr 2017 07:31:01 +
> Andre  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
> ___
> 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  

Re: [time-nuts] Re. DIY atomic "resonator"

[Richard (Rick) Karlquist]

Many decades ago, QST had an article about the
"Monode" RF noise generator.  No it wasn't an
April Fools joke; the Monode is simply a light
bulb.  You can probably download the article
from the arrl.org web site.

HP used to sell a fluorescent tube embedded in
a waveguide as a noise source.

These days, noise comm has a much easier
solution off the shelf.

Rick N6RK

On 4/12/2017 1:23 PM, Bob kb8tq wrote:

Hi


*All* incandescent lamps emit RF ….. They are a resistive device that is heated 
to well above
room temperature. People do use them in simple noise figure meters. The 
inductance of the
filament in a typical bulb restricts the bandwidth a bit. The are designs from 
at least the 1960’s
running around. I suspect the approach is much older and that’s just when I was 
introduced to
the technique (= built one).

Bob


On Apr 12, 2017, at 2:18 PM, David  wrote:

Some incandescent lamps can emit RF.

http://www.rexophone.com/?p=1081
http://www.radiomuseum.org/forum/rustika_lightbulb_fm_measurements.html

On Tue, 11 Apr 2017 18:09:52 +, you wrote:


Apparently fluorescent tubes continuously emit a lot of other microwave signals.  I once 
built a  homodyne doppler "speed" radar kit (used a coffee can for the 
antenna).  The way you calibrated it was to point it at a florescent tube and and adjust 
the reading to a specific value.




Seems that some fluorescent tube starters do emit a very brief burst at around 
1.4 GHz

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Re: [time-nuts] Re. DIY atomic "resonator"

[Bob kb8tq]

Hi


*All* incandescent lamps emit RF ….. They are a resistive device that is heated 
to well above
room temperature. People do use them in simple noise figure meters. The 
inductance of the 
filament in a typical bulb restricts the bandwidth a bit. The are designs from 
at least the 1960’s
running around. I suspect the approach is much older and that’s just when I was 
introduced to
the technique (= built one). 

Bob

> On Apr 12, 2017, at 2:18 PM, David  wrote:
> 
> Some incandescent lamps can emit RF.
> 
> http://www.rexophone.com/?p=1081
> http://www.radiomuseum.org/forum/rustika_lightbulb_fm_measurements.html
> 
> On Tue, 11 Apr 2017 18:09:52 +, you wrote:
> 
>> Apparently fluorescent tubes continuously emit a lot of other microwave 
>> signals.  I once built a  homodyne doppler "speed" radar kit (used a coffee 
>> can for the antenna).  The way you calibrated it was to point it at a 
>> florescent tube and and adjust the reading to a specific value.
>> 
>> 
>> 
>>> Seems that some fluorescent tube starters do emit a very brief burst at 
>>> around 1.4 GHz
> ___
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Re: [time-nuts] Re. DIY atomic "resonator"

[Bert Kehren via time-nuts]

Looking back at the dialog I started on Rb’s  and the repeated returns to 
that subject allow me to make some comments,  observations and 
recommendations.. I stayed on purpose away from participating  but learned a 
lot. It also 
resulted in some off list dialogs with members  working on the subject off 
list.  
Rick’s discussion on why to use two  frequencies was for me an eye opener 
and gives me clear directions on how to  proceed on frequency generation. The 
single frequency project is dumped. Corby’s  work on filters again 
influences our future steps. Using a laser diode and its  challenges again an 
eye 
opener and a challenge. We have time nuts that have  working systems. 
Let’s be honest, we have members with super  knowledge but very few have 
the appetite to do something with it in the form of  hardware. Here is my 
proposal that is based on walk before run.   
FRK and M100 are next to the HP 5065A the  most promising Rb’s in what we 
like to do. They are easy to work on specially  when you are 75/78 and in my 
case have a macular  hole. 
Optical Filter. Corby actually did insert a  filter in a M100 did however 
not notice an improvement. When we discussed it  come to find out he forgot 
to change the time constant so the cell did not  control the performance. 
This was years ago and like many of us has his hands  full with projects. He 
decided to pass his M100/FRK to an other time nut and  focus on HP and Maser. 
We all benefit from these  efforts. 
Back to filter we have dissected a FRK and a  M100 and are convinced that 
there is a room for a filter, in case of the FRK,  very easy. Corby used a 
M100, in my opinion more of a challenge. Will not try  it. After discussions 
with Corby I now understand that the filter does not  filter out a particular 
wavelength but most the noise that Rb lamps produce as  seen on optical 
spectrum analyzers. It improves signal noise ratio after all  that is what is 
all about. Once we have completed our current projects we may do  so. 
We are also considering to review the  frequency generation using Rick’s 
postings as guidance. All this needs measuring  capabilities which is what we 
are working on. I am fortunate to have access to  Corby’s Maser but Juerg 
does not have that. We are working on a solution.   
There are many FRK/M100’s out there some  with low output lamps that would 
be a natural for a Laser Diode replacement. The  mechanical makeup begs for 
a Laser solution. The two units have a cell in size  only second to HP5065A  
Going to  laser would also allow to reduce cell temperature again 
contributing to an  improved signal noise ratio, 
This is way off our expertise but it would  be nice if some one would take 
the ball and run with it. I am convinced from off  list conversations that 
$1000 is a reasonable  goal. 
There is no guarantee that we will do the  filter depending what our 
results will be on our present work so again maybe  some one would carry that 
ball. 
Both can be a first step for future work.  WALK
Bert Kehren
 
 
In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,  
att...@kinali.ch writes:

On Tue,  11 Apr 2017 07:31:01 +
Andre  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
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To unsubscribe, go to  
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Re: [time-nuts] Re. DIY atomic "resonator"

[David I. Emery]

On Wed, Apr 12, 2017 at 11:18:00AM -0700, jimlux wrote:
> Yep.  There's been a fair amount of work over the past decades on using 
> modulated reflectors for measuring antenna patterns (e.g. on phased 
> arrays).  You can have a diode/dipole suspended by resistive leads (with 
> an impedance of 377 ohms/square that are invisible) and turn it on and off.
> 
> Bolomey (I think) had an array of modulated reflectors, so you could 
> measure multiple points in the near field at the same time, and only 
> need to scan in one dimension. I can't remember if the reflectors were 
> modulated at different rates or with PN codes - either would work to 
> separate the responses.

In case some of you have not followed the Snowden (and related)
revelations about CSS/NSA/CIA snooping technology, apparently modulated
reflectors (corner reflectors with diode switches) are a standard trick
for ex-filtrating digital data streams from PCs and displays and the like
and have been used upwards into the Gigabit per second area...

Interesting to hear about using them for probing antenna
patterns...



-- 
  Dave Emery N1PRE/AE, d...@dieconsulting.com  DIE Consulting, Weston, Mass 
02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in 
celebration of what could have been, but wasn't and is not to be now either."

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Re: [time-nuts] Re. DIY atomic "resonator"

[David]

Some incandescent lamps can emit RF.

http://www.rexophone.com/?p=1081
http://www.radiomuseum.org/forum/rustika_lightbulb_fm_measurements.html

On Tue, 11 Apr 2017 18:09:52 +, you wrote:

>Apparently fluorescent tubes continuously emit a lot of other microwave 
>signals.  I once built a  homodyne doppler "speed" radar kit (used a coffee 
>can for the antenna).  The way you calibrated it was to point it at a 
>florescent tube and and adjust the reading to a specific value.
>
>
>
>> Seems that some fluorescent tube starters do emit a very brief burst at 
>> around 1.4 GHz
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Re: [time-nuts] Re. DIY atomic "resonator"

[jimlux]

On 4/12/17 10:28 AM, Dave B via time-nuts wrote:

On 12/04/17 17:00, jimlux wrote:


Subject: Re: [time-nuts] Re. DIY atomic "resonator"
Message-ID: <b3926cda-b4ff-2508-1be6-57c2fecf0...@earthlink.net>
Content-Type: text/plain; charset=utf-8; format=flowed

On 4/11/17 11:09 AM, Mark Sims wrote:

Apparently fluorescent tubes continuously emit a lot of other microwave signals.  I once 
built a  homodyne doppler "speed" radar kit (used a coffee can for the 
antenna).  The way you calibrated it was to point it at a florescent tube and and adjust 
the reading to a specific value.

--

That's not because the tube is emitting..  It's a target reflector
turning on and off at twice line frequency.
In most homodyne radars, you filter out the DC (the reflections from
stuff that's not moving), so anything that pulses on and off creates
nice output.


This patent would seem to confirm that discharge tubes do generate
microwave noise, and with a DC powered tube too.  (Would different
gasses produce different microwave spectra?)

http://www.google.co.uk/patents/US2942204


They generate broadband noise - they're used as high power noise sources 
for calibration.


Bracewell (I believe) used fluorescent tubes (driven by a reasonably 
stable source) as a calibration and timing reference at a astronomy array -

http://articles.adsabs.harvard.edu//full/2005JAHH8...75B/077.000.html

R. Bracewell and G. Swarup, "The Stanford microwave spectroheliograph 
antenna, a microsteradian pencil beam interferometer," in IRE 
Transactions on Antennas and Propagation, vol. 9, no. 1, pp. 22-30, 
January 1961.

doi: 10.1109/TAP.1961.1144935

I particularly like the inclusion of "milling machines" in the keyword list
keywords: {Microwave interferometry;Planar arrays;Radio 
telescopes;Reflector antennas, arrays;Solar radiation;Brightness 
temperature;Corona;Frequency;Microwave antennas;Milling 
machines;Monitoring;Moon;Phase modulation;Sun;TV}


And fluorescent tubes have been used as a broad band source in a 
classroom demo

https://www.researchgate.net/publication/276280926_Demonstrating_the_Principles_of_Aperture_Synthesis_with_the_Very_Small_Radio_Telescope



I would suspect that the radiated field has some spectral bumps in it, 
probably related the physical dimensions.  I doubt it would have any 
discrete lines (although maybe it does..)








I recall seeing such things sold surplus back in the early 70's, pity I
didn't know what they were back then.


There are also gas tubes in waveguides used as Radar T/R switches. when 
the main bang happens, the tube ionizes shorting the waveguide and 
protecting the receiver downstream.





There is also mention of huge mismatches in the guide when the tube was
not powered, that would support the homodyne speed calibration comment
by pointing it at a working (AC powered) florescent tube.  As Jim said,
a 100 (or 120) Hz "modulated reflector."


Yep.  There's been a fair amount of work over the past decades on using 
modulated reflectors for measuring antenna patterns (e.g. on phased 
arrays).  You can have a diode/dipole suspended by resistive leads (with 
an impedance of 377 ohms/square that are invisible) and turn it on and off.


Bolomey (I think) had an array of modulated reflectors, so you could 
measure multiple points in the near field at the same time, and only 
need to scan in one dimension. I can't remember if the reflectors were 
modulated at different rates or with PN codes - either would work to 
separate the responses.





Regards to All.

Dave G0WBX (or G8KBV both still valid.)

~~~

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Re: [time-nuts] Re. DIY atomic "resonator"

[Dave B via time-nuts]

On 12/04/17 17:00, "Tom Van Baak" wrote:

> It turns out that OP (Andre) would like the readings of his vintage Black 
> Star (UK) Nova 2400[X] 8-digit 2.4 GHz bench frequency counter to be accurate 
> and stable to the 8th digit. That's all. The internal XO or TCXO is not good 
> enough for that last digit or two. Not to mention the cal date is 1996.
>
> So the good news is that he is *not* embarking on a life-long project to 
> build his own atomic clock. This thread is just a newbie looking for a simple 
> answer to an accuracy / stability / calibration question. His counter has a 
> BNC for external timebase, so ...
>
> I think it would help him if any UK/EU time-nuts:
> - have a 1e-9 or 1e-10 level OCXO to spare -- which he would have to 
> calibrate, or
> - can help him locate a surplus telecom Rb -- inherently good enough that 
> calibration is not even required, or
> - point him to a cheap newbie-friendly 10 MHz GPSDO -- if his environment 
> would make that possible and reliable.
Would this help?

http://www.leobodnar.com/shop/index.php?main_page=product_info_id=234

GPSDO with selectable output frequencies, including 10MHz.

No affiliation, but would appear to fit the bill, at a (not
unreasonable) cost, compared to some of the second user kit on "the bay"
at times...   And it's in the UK..

Regards.

Dave G0WBX (or G8KBV both valid.)

~~~

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Re: [time-nuts] Re. DIY atomic "resonator"

[Dave B via time-nuts]

On 12/04/17 17:00, jimlux wrote:

> Subject: Re: [time-nuts] Re. DIY atomic "resonator"
> Message-ID: <b3926cda-b4ff-2508-1be6-57c2fecf0...@earthlink.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> On 4/11/17 11:09 AM, Mark Sims wrote:
>> Apparently fluorescent tubes continuously emit a lot of other microwave 
>> signals.  I once built a  homodyne doppler "speed" radar kit (used a coffee 
>> can for the antenna).  The way you calibrated it was to point it at a 
>> florescent tube and and adjust the reading to a specific value.
>>
>> --
> That's not because the tube is emitting..  It's a target reflector 
> turning on and off at twice line frequency.
> In most homodyne radars, you filter out the DC (the reflections from 
> stuff that's not moving), so anything that pulses on and off creates 
> nice output.

This patent would seem to confirm that discharge tubes do generate
microwave noise, and with a DC powered tube too.  (Would different
gasses produce different microwave spectra?)

http://www.google.co.uk/patents/US2942204

I recall seeing such things sold surplus back in the early 70's, pity I
didn't know what they were back then.

There is also mention of huge mismatches in the guide when the tube was
not powered, that would support the homodyne speed calibration comment
by pointing it at a working (AC powered) florescent tube.  As Jim said,
a 100 (or 120) Hz "modulated reflector."

Regards to All.

Dave G0WBX (or G8KBV both still valid.)

~~~

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Re: [time-nuts] Re. DIY atomic "resonator"

[Bob kb8tq]

Hi

According to the data sheet the X version of the 2400 has a TCXO in it. The 
“not an X” has an XO. “Setability” of the XO is <0.5 ppm and
the TCXO is rated at 0.2 ppm. Maximum resolution on the device occurs with a 20 
MHz input. That gives you +/- 0.05 ppm. The 200 MHz
range is scaled by 10 and the 2.4 GHz input is scaled by 128. Neither one gives 
higher resolution than you get at 20 MHz. A source good
to 0.05 ppm would only degrade the device by 1 LSB. A 0.01 ppm source would be 
adequate to ensure the final LSB is good. Any of the 
normal eBay telecom Rb’s would likely be good enough forever and ever, even 
without calibration. I have yet to see one that was off by 
> 0.001 ppm. 

Bob


> On Apr 12, 2017, at 10:01 AM, Tom Van Baak <t...@leapsecond.com> wrote:
> 
> An update about this thread...
> 
> It turns out that OP (Andre) would like the readings of his vintage Black 
> Star (UK) Nova 2400[X] 8-digit 2.4 GHz bench frequency counter to be accurate 
> and stable to the 8th digit. That's all. The internal XO or TCXO is not good 
> enough for that last digit or two. Not to mention the cal date is 1996.
> 
> So the good news is that he is *not* embarking on a life-long project to 
> build his own atomic clock. This thread is just a newbie looking for a simple 
> answer to an accuracy / stability / calibration question. His counter has a 
> BNC for external timebase, so ...
> 
> I think it would help him if any UK/EU time-nuts:
> - have a 1e-9 or 1e-10 level OCXO to spare -- which he would have to 
> calibrate, or
> - can help him locate a surplus telecom Rb -- inherently good enough that 
> calibration is not even required, or
> - point him to a cheap newbie-friendly 10 MHz GPSDO -- if his environment 
> would make that possible and reliable.
> 
> I would guess that a mere 8-digits of accuracy/stability should cost no more 
> than 100 these days. If you can help, please send him email, off-list.
> 
> Again, OP is not looking for laboratory-grade accuracy or to build his own 
> atomic clock from scratch. It's just an 8 digit counter.
> 
> /tvb
> 
> - Original Message - 
> From: "Andre" <an...@lanoe.net>
> To: <time-nuts@febo.com>
> Sent: Tuesday, April 11, 2017 12:31 AM
> Subject: [time-nuts] 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
> 
> 
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Re: [time-nuts] Re. DIY atomic "resonator"

[John Ackermann N8UR]

I investigated police radar stuff a long time ago, and for a while had 
an old X band unit shaped just like a searchlight, with analog meter. 
What I learned then was that even on the newer units, the tuning fork 
was specified to provide an independent means to verify the accuracy of 
the unit in the field.


I also remember hearing that the radar sales reps had a special gift 
they would hand out to friends: a tuning fork marked "60 MPH" but that 
rang at a lower frequency, so you could use it to "calibrate" the unit 
to read higher than actual.  I heard that it was popular among the 
speed-trap crowd.


On 04/12/2017 09:25 AM, jimlux wrote:

On 4/11/17 11:09 AM, Mark Sims wrote:

Apparently fluorescent tubes continuously emit a lot of other
microwave signals.  I once built a  homodyne doppler "speed" radar kit
(used a coffee can for the antenna).  The way you calibrated it was to
point it at a florescent tube and and adjust the reading to a specific
value.

--



That's not because the tube is emitting..  It's a target reflector
turning on and off at twice line frequency.
In most homodyne radars, you filter out the DC (the reflections from
stuff that's not moving), so anything that pulses on and off creates
nice output.

At 10.525 GHz, the Doppler is about 70 Hz/ (m/sec), 31 Hz/(mi/hr)

at 24GHz, 160 and 71 Hz, respectively

Most simple speed guns just have an audio frequency counter on the
output of the mixer diode(s).  Older units use a Gunn oscillator, newer
ones use a DRO.  Some have a pair of detectors so you can distinguish
motion towards and away.

The old "calibrate with a tuning fork" for police radar wasn't
calibrating the RF frequency (a 1000 ppm change of the gunn oscillator
isn't a big deal.. this is a "3%" kind of measurement) - it was
calibrating the audio frequency counter, which, in very early units,
used an RC timebase. (or an actual analog meter reading) I cannot
imagine a crystal oscillator bad enough that a tuning fork  would be
better.  - if XO based speed guns were checked with a tuning fork it's
for one of two reasons:
1) the purchasing requirement said "A tuning fork for calibration shall
be provided" (based on an older design)
2) it provides a "functional test" and you don't really care what the
frequency is, as long as it lights up anything reasonable

Homodyne/Doppler radars are fun
(http://home.earthlink.net/~w6rmk/radar10g.htm) and can form the basis
of a business that saves lives
(https://www.nasa.gov/jpl/finder-search-and-rescue-technology-helped-save-lives-in-nepal)


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Re: [time-nuts] Re. DIY atomic "resonator" 6GHz synthesizer from ADI

[paul swed]

But it is as Richard said and after he sent it I remembered reading about
it in the "Quantum beat".
The trick is to get that accurate frequencies sideband to land on the RB or
CS frequency. Just 1 sideband. So using a large step synthesizer and then
another to get the finer detail is a reasonable way to go.
Regards


On Tue, Apr 11, 2017 at 10:13 PM, Bob kb8tq  wrote:

> Hi
>
> If you make the cells in the basement (or even in most factories) the
> ability to have a wide range
> synthesizer will come in handy. The whole “6.834xxx GHz” thing is
> dependent on a number of variables.
> It is not at all uncommon to produce cells that come out 10’s or 100’s of
> KHz off of the “right number”.
> Wide range synthesizer = higher yield.
>
> Bob
>
> > On Apr 11, 2017, at 10:00 PM, Richard (Rick) Karlquist <
> rich...@karlquist.com> wrote:
> >
> > You always want two frequency sources.  One generates a carrier
> > frequency offset many MHz from 6.834 GHz and the other frequency
> > source modulates the carrier with a sideband that is at the
> > exact ~6.834 GHz frequency that finds the atomic line.  The
> > sideband is in turn modulated with audio to find the exact
> > center of the line.  This is now the easiest section to
> > design.
> >
> > This architecture automatically gives you gobs of resolution.
> > Of course you always have the C field for infinite resolution.
> > The other thing it does is prevent RF leaks from exciting the
> > atoms, since the strong LO is safely offset from 6.834.
> >
> > Rick N6RK
> >
> > On 4/11/2017 2:59 PM, paul swed wrote:
> >> When I read about the frequency generation in the Rb or CS there are
> >> normally many numbers associated with the actual frequency. Down to at
> >> least the 1 Hz level. Many of these PLLs are intended for multi-KHz
> steps.
> >> I speculate you might need 2 PLLs one thats very fine in I hz increments
> >> that gets added to something like these PLLs that step in 200 KHz
> >> increments.
> >> Regards
> >> Paul
> >> WB8TSL
> >>
> > ___
> > 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.
>
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Re: [time-nuts] Re. DIY atomic "resonator"

[jimlux]

On 4/11/17 11:09 AM, Mark Sims wrote:

Apparently fluorescent tubes continuously emit a lot of other microwave signals.  I once 
built a  homodyne doppler "speed" radar kit (used a coffee can for the 
antenna).  The way you calibrated it was to point it at a florescent tube and and adjust 
the reading to a specific value.

--



That's not because the tube is emitting..  It's a target reflector 
turning on and off at twice line frequency.
In most homodyne radars, you filter out the DC (the reflections from 
stuff that's not moving), so anything that pulses on and off creates 
nice output.


At 10.525 GHz, the Doppler is about 70 Hz/ (m/sec), 31 Hz/(mi/hr)

at 24GHz, 160 and 71 Hz, respectively

Most simple speed guns just have an audio frequency counter on the 
output of the mixer diode(s).  Older units use a Gunn oscillator, newer 
ones use a DRO.  Some have a pair of detectors so you can distinguish 
motion towards and away.


The old "calibrate with a tuning fork" for police radar wasn't 
calibrating the RF frequency (a 1000 ppm change of the gunn oscillator 
isn't a big deal.. this is a "3%" kind of measurement) - it was 
calibrating the audio frequency counter, which, in very early units, 
used an RC timebase. (or an actual analog meter reading) I cannot 
imagine a crystal oscillator bad enough that a tuning fork  would be 
better.  - if XO based speed guns were checked with a tuning fork it's 
for one of two reasons:
1) the purchasing requirement said "A tuning fork for calibration shall 
be provided" (based on an older design)
2) it provides a "functional test" and you don't really care what the 
frequency is, as long as it lights up anything reasonable


Homodyne/Doppler radars are fun 
(http://home.earthlink.net/~w6rmk/radar10g.htm) and can form the basis 
of a business that saves lives 
(https://www.nasa.gov/jpl/finder-search-and-rescue-technology-helped-save-lives-in-nepal)


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Re: [time-nuts] Re. DIY atomic "resonator"

[Tom Van Baak]

An update about this thread...

It turns out that OP (Andre) would like the readings of his vintage Black Star 
(UK) Nova 2400[X] 8-digit 2.4 GHz bench frequency counter to be accurate and 
stable to the 8th digit. That's all. The internal XO or TCXO is not good enough 
for that last digit or two. Not to mention the cal date is 1996.

So the good news is that he is *not* embarking on a life-long project to build 
his own atomic clock. This thread is just a newbie looking for a simple answer 
to an accuracy / stability / calibration question. His counter has a BNC for 
external timebase, so ...

I think it would help him if any UK/EU time-nuts:
- have a 1e-9 or 1e-10 level OCXO to spare -- which he would have to calibrate, 
or
- can help him locate a surplus telecom Rb -- inherently good enough that 
calibration is not even required, or
- point him to a cheap newbie-friendly 10 MHz GPSDO -- if his environment would 
make that possible and reliable.

I would guess that a mere 8-digits of accuracy/stability should cost no more 
than 100 these days. If you can help, please send him email, off-list.

Again, OP is not looking for laboratory-grade accuracy or to build his own 
atomic clock from scratch. It's just an 8 digit counter.

/tvb

- Original Message - 
From: "Andre" <an...@lanoe.net>
To: <time-nuts@febo.com>
Sent: Tuesday, April 11, 2017 12:31 AM
Subject: [time-nuts] 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


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[time-nuts] Re. DIY atomic "resonator"

[Mark Sims]

Apparently fluorescent tubes continuously emit a lot of other microwave 
signals.  I once built a  homodyne doppler "speed" radar kit (used a coffee can 
for the antenna).  The way you calibrated it was to point it at a florescent 
tube and and adjust the reading to a specific value.



> Seems that some fluorescent tube starters do emit a very brief burst at 
> around 1.4 GHz
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Re: [time-nuts] Re. DIY atomic "resonator" 6GHz synthesizer from ADI

[Bob kb8tq]

Hi

If you make the cells in the basement (or even in most factories) the ability 
to have a wide range
synthesizer will come in handy. The whole “6.834xxx GHz” thing is dependent on 
a number of variables. 
It is not at all uncommon to produce cells that come out 10’s or 100’s of KHz 
off of the “right number”.
Wide range synthesizer = higher yield. 

Bob

> On Apr 11, 2017, at 10:00 PM, Richard (Rick) Karlquist 
>  wrote:
> 
> You always want two frequency sources.  One generates a carrier
> frequency offset many MHz from 6.834 GHz and the other frequency
> source modulates the carrier with a sideband that is at the
> exact ~6.834 GHz frequency that finds the atomic line.  The
> sideband is in turn modulated with audio to find the exact
> center of the line.  This is now the easiest section to
> design.
> 
> This architecture automatically gives you gobs of resolution.
> Of course you always have the C field for infinite resolution.
> The other thing it does is prevent RF leaks from exciting the
> atoms, since the strong LO is safely offset from 6.834.
> 
> Rick N6RK
> 
> On 4/11/2017 2:59 PM, paul swed wrote:
>> When I read about the frequency generation in the Rb or CS there are
>> normally many numbers associated with the actual frequency. Down to at
>> least the 1 Hz level. Many of these PLLs are intended for multi-KHz steps.
>> I speculate you might need 2 PLLs one thats very fine in I hz increments
>> that gets added to something like these PLLs that step in 200 KHz
>> increments.
>> Regards
>> Paul
>> WB8TSL
>> 
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Re: [time-nuts] Re. DIY atomic "resonator" 6GHz synthesizer from ADI

[Richard (Rick) Karlquist]

You always want two frequency sources.  One generates a carrier
frequency offset many MHz from 6.834 GHz and the other frequency
source modulates the carrier with a sideband that is at the
exact ~6.834 GHz frequency that finds the atomic line.  The
sideband is in turn modulated with audio to find the exact
center of the line.  This is now the easiest section to
design.

This architecture automatically gives you gobs of resolution.
Of course you always have the C field for infinite resolution.
The other thing it does is prevent RF leaks from exciting the
atoms, since the strong LO is safely offset from 6.834.

Rick N6RK

On 4/11/2017 2:59 PM, paul swed wrote:

When I read about the frequency generation in the Rb or CS there are
normally many numbers associated with the actual frequency. Down to at
least the 1 Hz level. Many of these PLLs are intended for multi-KHz steps.
I speculate you might need 2 PLLs one thats very fine in I hz increments
that gets added to something like these PLLs that step in 200 KHz
increments.
Regards
Paul
WB8TSL


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Re: [time-nuts] Re. DIY atomic "resonator" 6GHz synthesizer from ADI

[paul swed]

When I read about the frequency generation in the Rb or CS there are
normally many numbers associated with the actual frequency. Down to at
least the 1 Hz level. Many of these PLLs are intended for multi-KHz steps.
I speculate you might need 2 PLLs one thats very fine in I hz increments
that gets added to something like these PLLs that step in 200 KHz
increments.
Regards
Paul
WB8TSL

On Tue, Apr 11, 2017 at 2:32 PM, Alex Pummer  wrote:

> the are 6GHc synthesizer chips from ADI available see here
> http://www.analog.com/en/analog-dialogue/articles/design-a-
> direct-6-ghz-local-oscillator.html
>
> 73
>
> KJ6UHN
>
> Alex
>
>
> On 4/11/2017 8:29 AM, Attila Kinali wrote:
>
>> On Tue, 11 Apr 2017 07:31:01 +
>> Andre  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
>>
>>
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Re: [time-nuts] Re. DIY atomic "resonator"

[jimlux]

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.




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Re: [time-nuts] Re. DIY atomic "resonator" 6GHz synthesizer from ADI

[Alex Pummer]

the are 6GHc synthesizer chips from ADI available see here 
http://www.analog.com/en/analog-dialogue/articles/design-a-direct-6-ghz-local-oscillator.html


73

KJ6UHN

Alex


On 4/11/2017 8:29 AM, Attila Kinali wrote:

On Tue, 11 Apr 2017 07:31:01 +
Andre  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



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Re: [time-nuts] Re. DIY atomic "resonator"-- replacing SDRs

[Alex Pummer]

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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-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.8012 / Virus Database: 4769/14290 - Release Date: 
04/11/17


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Re: [time-nuts] Re. DIY atomic "resonator"

[Lester Veenstra]

But, in the true time nuts tradition, I would expect it is time to trap an ion.

Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y
les...@veenstras.com
-Original Message-
From: time-nuts [mailto:time-nuts-boun...@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

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Re: [time-nuts] Re. DIY atomic "resonator"

[Bob kb8tq]

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 
>  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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Re: [time-nuts] Re. DIY atomic "resonator"

[Magnus Danielson]

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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Re: [time-nuts] Re. DIY atomic "resonator"

[Attila Kinali]

On Tue, 11 Apr 2017 07:31:01 +
Andre  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
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Re: [time-nuts] Re. DIY atomic "resonator"

[Richard (Rick) Karlquist]

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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Re: [time-nuts] Re. DIY atomic "resonator"

[paul swed]

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  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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[time-nuts] Re. DIY atomic "resonator"

[Andre]

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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