subject:"\[time\-nuts\] homebrew H maser"

On Sun, 29 Aug 2010 09:51:46 -0700 (PDT)
J. Forster j...@quik.com wrote:

 If you took a modern approach by using factory built test equipment as
 building blocks (microwave synthesizer, lock-in amp, power supplies, etc)
 and commercial vacuum components (pumps, valves, fittings, controllers,
 etc. in Conflat or something like it), you could likely build up most of a
 system pretty easily.

And it would be pretty expensive too. Lab grade equipment, especially
in electronics, is very expensive as it has to accomodate for a broad
range of needs. Specialized electronics, even if it is a one-of-a-kind
thing and thus very expensive, is often cheaper because it is optimized
only for one case.
 
 Much of this stuff is available on eBay at pretty reasonable prices.

In the US, yes, not in Europe. Just try to find someone selling a
HP counter that is not 20a old on fleabay in Europe. While there
are a dozen in the US, there is at most one on the old continent.
If there is even one...


Attila Kinali
-- 
If you want to walk fast, walk alone.
If you want to walk far, walk together.
-- African proverb

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Re: [time-nuts] homebrew H maser

On Sun, 29 Aug 2010 10:11:47 -0700 (PDT)
J. Forster j...@quik.com wrote:

 I used to read Strong's book as bedtime reading.

And which book would that be, for those who have not read it?

Attila Kinali
-- 
If you want to walk fast, walk alone.
If you want to walk far, walk together.
-- African proverb

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Re: [time-nuts] homebrew H maser

On Sun, 29 Aug 2010 10:03:02 -0700 (PDT)
J. Forster j...@quik.com wrote:

 
 [snip]
  complicating aspect is the self-tuning stuff for which several
  strategies may be chosen.
 
  I'd start here at getting a cavity that is resonant at the frequency
  at all. Getting sub-milimeter precision in tooling is quite easy
  (given you have the tools and knowledge, or can pay someone to do it for
  you),
  but if the cavity has to be resonant within a couple of Hz of the
  1.4xxxGHz, then you have to get a precission in the range of 10^-9
  which basically impossible mechanically. So the cavity would need to have
  a mechanical tuning system too, but one that doesn't lower the cavity's
  Q or add any additional resonant modes.
 
 A tuning plunger driven with a Burleigh Inchworm, either through a bellows
 or with a vacuum Inchworm.

Yes, but that's only half of the story. How do you make it vacuum tight?
And how do you design the end in the cavity so that you do not create
unwanted resonant modi?

 
Attila Kinali
-- 
If you want to walk fast, walk alone.
If you want to walk far, walk together.
-- African proverb

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Re: [time-nuts] homebrew H maser

On Sun, 29 Aug 2010 16:26:05 -0400
Mark Kahrs mark.ka...@gmail.com wrote:

 The Hahvahd physics dept. has all number of interesting papers.
 
 For example there's Humphrey's
 dissertation:www.physics.harvard.edu/Thesespdfs/humphrey.pdf
 
 If you've ever wanted to make your own Rb cell, how about this
 one?cfa-www.harvard.edu/~dphil/work/coat.pdf
 http://cfa-www.harvard.edu/%7Edphil/work/coat.pdf%20

Thanks, i'll have a look at those.

Attila Kinali
-- 
If you want to walk fast, walk alone.
If you want to walk far, walk together.
-- African proverb

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Re: [time-nuts] homebrew H maser

Proceedures in Experimental Physics

-John

=


 On Sun, 29 Aug 2010 10:11:47 -0700 (PDT)
 J. Forster j...@quik.com wrote:

 I used to read Strong's book as bedtime reading.

 And which book would that be, for those who have not read it?

   Attila Kinali
 --
 If you want to walk fast, walk alone.
 If you want to walk far, walk together.
   -- African proverb





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Re: [time-nuts] homebrew H maser

Questions like yours are what makes a good experimental physicist.

As to vacuum tight, you use bellows or put the inchworm inside the vacuum.

As to RF leakage, a waveguide below cutoff is one way. Another is to
design a choke seal, a 1/4 wave stub with a high Q cavity as the open end.

-Jhn

===




 On Sun, 29 Aug 2010 10:03:02 -0700 (PDT)
 J. Forster j...@quik.com wrote:


 [snip]
  complicating aspect is the self-tuning stuff for which several
  strategies may be chosen.
 
  I'd start here at getting a cavity that is resonant at the frequency
  at all. Getting sub-milimeter precision in tooling is quite easy
  (given you have the tools and knowledge, or can pay someone to do it
 for
  you),
  but if the cavity has to be resonant within a couple of Hz of the
  1.4xxxGHz, then you have to get a precission in the range of 10^-9
  which basically impossible mechanically. So the cavity would need to
 have
  a mechanical tuning system too, but one that doesn't lower the
 cavity's
  Q or add any additional resonant modes.

 A tuning plunger driven with a Burleigh Inchworm, either through a
 bellows
 or with a vacuum Inchworm.

 Yes, but that's only half of the story. How do you make it vacuum tight?
 And how do you design the end in the cavity so that you do not create
 unwanted resonant modi?


   Attila Kinali
 --
 If you want to walk fast, walk alone.
 If you want to walk far, walk together.
   -- African proverb





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Re: [time-nuts] Homebrew H Maser

On Sun, 29 Aug 2010 13:27:13 -0700
Corby Dawson cdel...@juno.com wrote:

 -The triple magnetic shields are VERY important. The first time I removed
 the top
  shield to access the RF section the Maser stopped oscillating! Replacing
 the shield
 restored oscillations!

Hmm.. i'd guess that the oscillation went outside the cavity's resonant
range. Other than shifting the resonance frequency and spreading the
hyperfine lines, it should not have any other effect. But i might
be very well wrong.

 -The cavity does not have to be machined to super precise levels, in
 this Maser once the coarse setting (mechanical at factory) is made, the
 medium tuning is done by adjusting the cavity temperature. The fine is
 done with the cavity varactor. This cavity is aluminum.

The thermal length constant of Al is 23e-6/K, which means that per
°C you get a pulling of about 23ppm of the frequency. Guestimating
that more than 20°C of heating should not be done to keep the whole
thing in a easy to handle range. Then we would have a maximum pulling
range of +/-230ppm, which means +/-10um precission on a 10cm diameter.
This is still a very thight tollerance. Not impossible, but not that
easy either.

 -Making a homebrew collimator (at the discharge bulb output) might be
 hard, google it and you will see it's  tricky.

I couldn't find anything telling me that it is difficult to do
when i did a quick search. If i understood it correctly, the collimator
for a H-maser is nothing else than a tight and straight pipe from the
H beam source to the state selector magnet. Did i misunderstand something
here?


 I have, somewhere, a scan of the two manuals. There is lots of theory and
 full schematics. Might be a good read if you are serious in trying to
 homebrew one.
 I'll dig them up and see if anyone could host them on a website. (Files
 are quite large!)

I would very much like to read those. Even if i dont build a maser.
As John suggested, it would be IMHO best to put them on Didier's site
as others might be interested as well. 

Attila Kinali
-- 
If you want to walk fast, walk alone.
If you want to walk far, walk together.
-- African proverb

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Re: [time-nuts] homebrew H maser

2010-08-31 Thread Francis Grosz

I think the book referred to is The Scientific American Book
of Projects for the Amateur Scientist by C. L. Stong (no r' in Stong) 
I too used to just read it - great book.  It's a collection of some of The
Amateur Scientist columns by Stong from Scientific American 
magazine.  Unfortunately it's out of print and used copies can be a 
bit pricey or hard to find.  There is a great deal available, however - a 
complete collection of all of The Amateur Scientist columns ever 
published on a CD for $27.  If anyone is interested, the link is

http://www.brightscience.com/

Francis

--
Original Message
 Date: Tue, 31 Aug 2010 18:06:38 +0200
 From: Attila Kinali att...@kinali.ch
 Subject: Re: [time-nuts] homebrew H maser
 To: j...@quik.com, Discussion of precise time and frequency
 measurement time-nuts@febo.com
 Message-ID: 20100831180638.16e4c656.att...@kinali.ch
 Content-Type: text/plain; charset=US-ASCII

 On Sun, 29 Aug 2010 10:11:47 -0700 (PDT)
 J. Forster j...@quik.com wrote:
 
 I used to read Strong's book as bedtime reading.
 
 And which book would that be, for those who have not read it?
 
 Attila Kinali

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Re: [time-nuts] homebrew H maser

Nope. Proceedures in Experimental Physics. A different Strong.

-John




 I think the book referred to is The Scientific American Book
 of Projects for the Amateur Scientist by C. L. Stong (no r' in Stong)
 I too used to just read it - great book.  It's a collection of some of
 The
 Amateur Scientist columns by Stong from Scientific American
 magazine.  Unfortunately it's out of print and used copies can be a
 bit pricey or hard to find.  There is a great deal available, however - a
 complete collection of all of The Amateur Scientist columns ever
 published on a CD for $27.  If anyone is interested, the link is

 http://www.brightscience.com/

 Francis

 --
 Original Message
 Date: Tue, 31 Aug 2010 18:06:38 +0200
 From: Attila Kinali att...@kinali.ch
 Subject: Re: [time-nuts] homebrew H maser
 To: j...@quik.com, Discussion of precise time and frequency
 measurement time-nuts@febo.com
 Message-ID: 20100831180638.16e4c656.att...@kinali.ch
 Content-Type: text/plain; charset=US-ASCII

 On Sun, 29 Aug 2010 10:11:47 -0700 (PDT)
 J. Forster j...@quik.com wrote:

 I used to read Strong's book as bedtime reading.

 And which book would that be, for those who have not read it?

 Attila Kinali

 ___
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 To unsubscribe, go to
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Re: [time-nuts] homebrew H maser

2010-08-31 Thread jimlux

Published or sold by lindsay books at a very reasonable price.  Its from the 
40s or 50s. Great book for build it from scratch
--Original Message--
From: J. Forster
Sender: time-nuts-boun...@febo.com
To: Attila Kinali
Cc: Discussion of precise time and frequency measurement
ReplyTo: j...@quik.com
ReplyTo: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] homebrew H maser
Sent: Aug 31, 2010 09:21

Proceedures in Experimental Physics

-John

=

 On Sun, 29 Aug 2010 10:11:47 -0700 (PDT)
 J. Forster j...@quik.com wrote:

 I used to read Strong's book as bedtime reading.

 And which book would that be, for those who have not read it?

   Attila Kinali
 --
 If you want to walk fast, walk alone.
 If you want to walk far, walk together.
   -- African proverb

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Sent via BlackBerry by ATT
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Re: [time-nuts] homebrew H maser

I didn't know of the current source. I've had mine for decades. Thanks.

If you are into experimental physics, it's good to know how to do things
from scratch, IMO. Even if you are going to use the latest toy out of a
new box.

-John

==


 Published or sold by lindsay books at a very reasonable price.  Its from
 the 40s or 50s. Great book for build it from scratch
 --Original Message--
 From: J. Forster
 Sender: time-nuts-boun...@febo.com
 To: Attila Kinali
 Cc: Discussion of precise time and frequency measurement
 ReplyTo: j...@quik.com
 ReplyTo: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] homebrew H maser
 Sent: Aug 31, 2010 09:21

 Proceedures in Experimental Physics

 -John

 =


 On Sun, 29 Aug 2010 10:11:47 -0700 (PDT)
 J. Forster j...@quik.com wrote:

 I used to read Strong's book as bedtime reading.

 And which book would that be, for those who have not read it?

  Attila Kinali
 --
 If you want to walk fast, walk alone.
 If you want to walk far, walk together.
  -- African proverb





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 To unsubscribe, go to
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 Sent via BlackBerry by ATT





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Re: [time-nuts] homebrew H maser

2010-08-31 Thread Don Latham

gee, i used to read that book over and over. the projects have two or more
wires leading off page to power supply, which i never had.
now that i have a lot of power supplies, my projects have wires leading 
to network analyzer... about out of reach now as all those power
supplies then. whine whine. i guess you can't win :-)
don

Francis Grosz
 I think the book referred to is The Scientific American Book
 of Projects for the Amateur Scientist by C. L. Stong (no r' in Stong)
 I too used to just read it - great book.  It's a collection of some of
 The
 Amateur Scientist columns by Stong from Scientific American
 magazine.  Unfortunately it's out of print and used copies can be a
 bit pricey or hard to find.  There is a great deal available, however - a
 complete collection of all of The Amateur Scientist columns ever
 published on a CD for $27.  If anyone is interested, the link is

 http://www.brightscience.com/

 Francis

 --
 Original Message
 Date: Tue, 31 Aug 2010 18:06:38 +0200
 From: Attila Kinali att...@kinali.ch
 Subject: Re: [time-nuts] homebrew H maser
 To: j...@quik.com, Discussion of precise time and frequency
 measurement time-nuts@febo.com
 Message-ID: 20100831180638.16e4c656.att...@kinali.ch
 Content-Type: text/plain; charset=US-ASCII

 On Sun, 29 Aug 2010 10:11:47 -0700 (PDT)
 J. Forster j...@quik.com wrote:

 I used to read Strong's book as bedtime reading.

 And which book would that be, for those who have not read it?

 Attila Kinali

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-- 
Neither the voice of authority nor the weight of reason and argument are
as significant as experiment, for thence comes quiet to the mind.
R. Bacon


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com


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Re: [time-nuts] homebrew H maser

2010-08-31 Thread Chuck Harris


The Scientific American guy is Stong.  The Procedures in Experimental
Physics guy is Strong.

I have original copies of each, and they are fun bedside readers.

-Chuck Harris

J. Forster wrote:

Nope. Proceedures in Experimental Physics. A different Strong.

-John





I think the book referred to is The Scientific American Book
of Projects for the Amateur Scientist by C. L. Stong (no r' in Stong)
I too used to just read it - great book.  It's a collection of some of
The
Amateur Scientist columns by Stong from Scientific American
magazine.  Unfortunately it's out of print and used copies can be a
bit pricey or hard to find.  There is a great deal available, however - a
complete collection of all of The Amateur Scientist columns ever
published on a CD for $27.  If anyone is interested, the link is

http://www.brightscience.com/

 Francis

--
Original Message

Date: Tue, 31 Aug 2010 18:06:38 +0200
From: Attila Kinaliatt...@kinali.ch
Subject: Re: [time-nuts] homebrew H maser
To: j...@quik.com, Discussion of precise time and frequency
measurementtime-nuts@febo.com
Message-ID:20100831180638.16e4c656.att...@kinali.ch
Content-Type: text/plain; charset=US-ASCII

On Sun, 29 Aug 2010 10:11:47 -0700 (PDT)
J. Forsterj...@quik.com  wrote:


I used to read Strong's book as bedtime reading.


And which book would that be, for those who have not read it?

Attila Kinali


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Re: [time-nuts] homebrew H maser

2010-08-30 Thread EWKehren

Thank you Bruce
This is very informative, not in my life time on ebay, but ground braking  
for things to come.
Bert Kehren
 
 
In a message dated 8/29/2010 4:32:13 P.M. Eastern Daylight Time,  
bruce.griffi...@xtra.co.nz writes:

http://tycho.usno.navy.mil/ptti/ptti2002/paper14.pdf
Bruce  Griffiths wrote:
  http://www.spectratime.com/product_downloads/PTTI_FCS_2005.pdf


  ewkeh...@aol.com wrote:
 Any links to reading material, would be  nice to learn what they did 
 to get
 a small package  and how small is it?
 Bert  Kehren


 In a message dated 8/29/2010  2:03:34 P.M. Eastern Daylight Time,
 p...@phk.freebsd.dk  writes:

 In   message3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com   writes:

 Do we know any thing about the Neuchatel  design for  Galileo?
 Bert Kehren
 There are  plenty of papers about  it.

 They started out with  an active design, and got it inside  spec
 (power/weight) but  found that the performance was not worth  the
 extra effort,  so they switched to a passive design to further
 reduce   weight/power.




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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Magnus Danielson


On 08/29/2010 03:55 PM, Attila Kinali wrote:

Moin,

I had a little bit too much time at hand this weekend and read a bit
about H masers. I was quite astonished to see how simple these devices
actually are. The electronics are basically a simple matter these days
(thanks to the abundance of GHz devices for cell phones and GPS receivers).

The only problem would be to build a high Q cavity, get a Teflon coated
quarz bulb of the right diameter, an apropriate atomic hydrogen beam source
and putting everything under high vacuum. Piece of cake ;-)

Thus i wondered whether anyone had ever build a H maser outside
national labs and and specialized companies. Looking at the time-nuts
archives, quite a few people asked about the feasibilty of such
an endeavor. A few times i read of people who actually attempted to build
one, but never was there any website or any other resource with their
results meantioned. Neither did big-g return any results when searching
for these homebrew H masers.

Does anyone know whether any of those people collected their results
somewhere? And if, where i could find them?


The physical package is definitely where most of the effort goes in. A 
complicating aspect is the self-tuning stuff for which several 
strategies may be chosen.


You need to balance the rate of the atoms, as both too few and too many 
kills the oscillation.


The size of the glass-bulb is not a fixed thing, during research and 
development different sizes glass-bulbs is used to establish the 
wall-shift aspects in order to adjust for it, which is needed in order 
to make absolute measurements on the free atom resonance or compensate 
into that regard.


As for reference, there is about one set of books and papers from a 
handful of journals and a bunch of patents which needs to the read in 
order to build up the knowledge-base for attempting something like it.


It's a complicated field and several traps to fall into on the way. It 
is a fairly sizeable project to attempt.


Cheers,
Magnus

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Poul-Henning Kamp

In message 4c7a6b01.3030...@rubidium.dyndns.org, Magnus Danielson writes:
On 08/29/2010 03:55 PM, Attila Kinali wrote:

It's a complicated field and several traps to fall into on the way. It 
is a fairly sizeable project to attempt.

Well, as with so much else, it depends what the level of ambition is.

If you just want to be able to point to the resonance and say I
did that, it is not intrinsically hard and none of the materials
are hard to get hold of or particularly poisonous.

Few of the problems Ramsey fought in the early 1950'ies are relevante
today, for instance, the entire detection issue is trivially solved
with USRP/GnuRadio.

I would tend to think that $10k in materials would get you pretty
close.

I think the most recent H-maser design is Neuchatels design for
the Galileo GNSS.

Building a _good_ (ie: metrology grade) hydrogen maser, sounds like
the last significant thing you did in your life, however many years
you have left...

Poul-Henning

PS: And if you even manage to build something which works half the
time, and do not suffer from ethics, there is a finite but very
profitable market for audiopholery, and I'm sure somebody is willing
to eliminate the last traces of jitter in his CD-player for just
under $100k...

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Attila Kinali

On Sun, 29 Aug 2010 16:13:21 +0200
Magnus Danielson mag...@rubidium.dyndns.org wrote:

 On 08/29/2010 03:55 PM, Attila Kinali wrote:
  Does anyone know whether any of those people collected their results
  somewhere? And if, where i could find them?
 
 The physical package is definitely where most of the effort goes in.

I know, that's why i'm asking.
The papers i've read sofar all suggest that the difficult part is to
compensate for cavity detuning, wall shift and second order doppler
effect. Somehow all these papers seem to assume that getting an
oscillation at all is so easy that everyone could do it (yes, i know that
this is normal with scientific papers).

I thought, that if someone build a homebrew H maser, he'd write about
the difficulties getting there. Which would be a very interesting reading
and teach a lot about the physics (and tool making, mechanics, etc)
of these devices.

 A 
 complicating aspect is the self-tuning stuff for which several 
 strategies may be chosen.

I'd start here at getting a cavity that is resonant at the frequency
at all. Getting sub-milimeter precision in tooling is quite easy
(given you have the tools and knowledge, or can pay someone to do it for you),
but if the cavity has to be resonant within a couple of Hz of the
1.4xxxGHz, then you have to get a precission in the range of 10^-9
which basically impossible mechanically. So the cavity would need to have
a mechanical tuning system too, but one that doesn't lower the cavity's
Q or add any additional resonant modes.

 You need to balance the rate of the atoms, as both too few and too many 
 kills the oscillation.

Or get to the basic requirement of getting a pure H2 source to feed
the beam source. The beam source itself, including the dissociator,
would be a formidable project to do at home by itself.
 
 The size of the glass-bulb is not a fixed thing, during research and 
 development different sizes glass-bulbs is used to establish the 
 wall-shift aspects in order to adjust for it, which is needed in order 
 to make absolute measurements on the free atom resonance or compensate 
 into that regard.

Interestingly, i think that the bulb would be the easiest part
these days. At least around here, there are a few glas blowers
for the chemical/pharmaceutical industry that also do single pieces.
Getting it coated would only involve finding a company that does
teflon coating (there do seem enough of them). From what i gather
it's shape doesnt have to be exactly spherical down to the 
sub-milimeter range.

 As for reference, there is about one set of books and papers from a 
 handful of journals and a bunch of patents which needs to the read in 
 order to build up the knowledge-base for attempting something like it.

Which papers/books would you recommend reading?

And no, i don't think i'd attempt to build a H maser.
I'm quite confident i could do the electronics part, but i know that
i don't know anything when it comes to mechanics. Much less about
handling high vacuum and atomic gas beams.

 It's a complicated field and several traps to fall into on the way. It 
 is a fairly sizeable project to attempt.

Yes, but it's fun to read about it :-)

Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Attila Kinali

On Sun, 29 Aug 2010 15:05:05 +
Poul-Henning Kamp p...@phk.freebsd.dk wrote:

 In message 4c7a6b01.3030...@rubidium.dyndns.org, Magnus Danielson writes:
 On 08/29/2010 03:55 PM, Attila Kinali wrote:
 
 It's a complicated field and several traps to fall into on the way. It 
 is a fairly sizeable project to attempt.
 
 Well, as with so much else, it depends what the level of ambition is.
 
 If you just want to be able to point to the resonance and say I
 did that, it is not intrinsically hard and none of the materials
 are hard to get hold of or particularly poisonous.

True. But i don't think i'd get even that far considering my
knowledge in this part of physics, especially in actually building
such devices.
 
 Few of the problems Ramsey fought in the early 1950'ies are relevante
 today, for instance, the entire detection issue is trivially solved
 with USRP/GnuRadio.

Yes, all the electronics problems are basically solved these days.

 I would tend to think that $10k in materials would get you pretty
 close.

I think so too. Though, things like high vacuum pumps are quite
expensive, even used ones.

 I think the most recent H-maser design is Neuchatels design for
 the Galileo GNSS.

Yes, that one seems to be a very neat devices. And quite small too.
I wonder whether i should drive to Neuchchâtel and ask them for 
a tour trough their labs :-)

 Building a _good_ (ie: metrology grade) hydrogen maser, sounds like
 the last significant thing you did in your life, however many years
 you have left...


Being a time-nut might get you there ;-)
 
 PS: And if you even manage to build something which works half the
 time, and do not suffer from ethics, there is a finite but very
 profitable market for audiopholery, and I'm sure somebody is willing
 to eliminate the last traces of jitter in his CD-player for just
 under $100k...

ROTFL

Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] homebrew H maser

If you took a modern approach by using factory built test equipment as
building blocks (microwave synthesizer, lock-in amp, power supplies, etc)
and commercial vacuum components (pumps, valves, fittings, controllers,
etc. in Conflat or something like it), you could likely build up most of a
system pretty easily.

You could probably even build much of the specialized stuff from the
Meccano like vacuum parts made by Kimball Physics.

Much of this stuff is available on eBay at pretty reasonable prices.

In thinking about it, it would be a terrific project to run with LabView!

PLEASE! Don't tempt me further!!

Best,

-John

=



 In message 4c7a6b01.3030...@rubidium.dyndns.org, Magnus Danielson
 writes:
On 08/29/2010 03:55 PM, Attila Kinali wrote:

It's a complicated field and several traps to fall into on the way. It
is a fairly sizeable project to attempt.

 Well, as with so much else, it depends what the level of ambition is.

 If you just want to be able to point to the resonance and say I
 did that, it is not intrinsically hard and none of the materials
 are hard to get hold of or particularly poisonous.

 Few of the problems Ramsey fought in the early 1950'ies are relevante
 today, for instance, the entire detection issue is trivially solved
 with USRP/GnuRadio.

 I would tend to think that $10k in materials would get you pretty
 close.

 I think the most recent H-maser design is Neuchatels design for
 the Galileo GNSS.

 Building a _good_ (ie: metrology grade) hydrogen maser, sounds like
 the last significant thing you did in your life, however many years
 you have left...

 Poul-Henning

 PS: And if you even manage to build something which works half the
 time, and do not suffer from ethics, there is a finite but very
 profitable market for audiopholery, and I'm sure somebody is willing
 to eliminate the last traces of jitter in his CD-player for just
 under $100k...

 --
 Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
 p...@freebsd.org | TCP/IP since RFC 956
 FreeBSD committer   | BSD since 4.3-tahoe
 Never attribute to malice what can adequately be explained by
 incompetence.

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 To unsubscribe, go to
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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Poul-Henning Kamp

In message 57157.12.6.201.2.1283100706.squir...@popaccts.quikus.com, J. Fors
ter writes:

In thinking about it, it would be a terrific project to run with LabView!

Rubbish, LabView would _never_ be able to do that.

PLEASE! Don't tempt me further!!

Ooops, sorry!  :-)

Poul-Henning

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread jimlux


J. Forster wrote:

If you took a modern approach by using factory built test equipment as
building blocks (microwave synthesizer, lock-in amp, power supplies, etc)
and commercial vacuum components (pumps, valves, fittings, controllers,
etc. in Conflat or something like it), you could likely build up most of a
system pretty easily.




You definitely need a copy of this book
http://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0813340063/ref=tmm_pap_title_0/182-2347235-0798235

Building Scientific Apparatus by Moore, Davies, and Coplan

How to build that ion gun, or cobble together the high vacuum system, 
etc. Lots of useful references..


You'd also do well to get a catalog from Kurt.J.Lesker Company 
(http://www.lesker.com/)  and from several of the vacuum equipment 
companies.  Vacuum stuff is available used quite widely.



Between the book and the catalog(s), you've got plenty of reading and 
dreaming material for months.



Be aware, though, that high vacuum is like amateur telescope mirror 
making.. frustrating, tedious, and gratifying when it works.  There's a 
surprising amount of craft in it.  (and entirely in keeping with 
time-nuttery)


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Re: [time-nuts] homebrew H maser


[snip]
 complicating aspect is the self-tuning stuff for which several
 strategies may be chosen.

 I'd start here at getting a cavity that is resonant at the frequency
 at all. Getting sub-milimeter precision in tooling is quite easy
 (given you have the tools and knowledge, or can pay someone to do it for
 you),
 but if the cavity has to be resonant within a couple of Hz of the
 1.4xxxGHz, then you have to get a precission in the range of 10^-9
 which basically impossible mechanically. So the cavity would need to have
 a mechanical tuning system too, but one that doesn't lower the cavity's
 Q or add any additional resonant modes.

A tuning plunger driven with a Burleigh Inchworm, either through a bellows
or with a vacuum Inchworm.

 You need to balance the rate of the atoms, as both too few and too many
 kills the oscillation.

There are commercial adjustable leaks and Mass Flow Controllers by MKS for
example.

 Or get to the basic requirement of getting a pure H2 source to feed
 the beam source. The beam source itself, including the dissociator,
 would be a formidable project to do at home by itself.

Kimball Physics sells parts for doing this.

 The size of the glass-bulb is not a fixed thing, during research and
 development different sizes glass-bulbs is used to establish the
 wall-shift aspects in order to adjust for it, which is needed in order
 to make absolute measurements on the free atom resonance or compensate
 into that regard.

 Interestingly, i think that the bulb would be the easiest part
 these days. At least around here, there are a few glas blowers
 for the chemical/pharmaceutical industry that also do single pieces.
 Getting it coated would only involve finding a company that does
 teflon coating (there do seem enough of them). From what i gather
 it's shape doesnt have to be exactly spherical down to the
 sub-milimeter range.

 As for reference, there is about one set of books and papers from a
 handful of journals and a bunch of patents which needs to the read in
 order to build up the knowledge-base for attempting something like it.

 Which papers/books would you recommend reading?

 And no, i don't think i'd attempt to build a H maser.
 I'm quite confident i could do the electronics part, but i know that
 i don't know anything when it comes to mechanics. Much less about
 handling high vacuum and atomic gas beams.

The pumping is pretty straight forward. You would likely need a source of
LN2, at least for a while. The vacuum needs to be clean, which means
traps. Sorbtion  ion or Ti sub pumps would be a better idea.

 It's a complicated field and several traps to fall into on the way. It
 is a fairly sizeable project to attempt.

 Yes, but it's fun to read about it :-)

   Attila Kinali


Best,

-John

===


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Re: [time-nuts] homebrew H maser

I used to read Strong's book as bedtime reading.

WARNING: There are few things more addictive than collecting:

Conflat Vacuum Fittings
Standard Taper Glassware
and worst:
Linos (Spindler Hoyer) MicroBench and NanoBench optical breadboarding.

BE WARNED!

-John

J. Forster wrote:
If you took a modern approach by using factory built test equipment as
building blocks (microwave synthesizer, lock-in amp, power supplies,
etc)
and commercial vacuum components (pumps, valves, fittings, controllers,
etc. in Conflat or something like it), you could likely build up most of
a
system pretty easily.

You definitely need a copy of this book
http://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0813340063/ref=tmm_pap_title_0/182-2347235-0798235

Building Scientific Apparatus by Moore, Davies, and Coplan

How to build that ion gun, or cobble together the high vacuum system,
etc. Lots of useful references..

You'd also do well to get a catalog from Kurt.J.Lesker Company
(http://www.lesker.com/) and from several of the vacuum equipment
companies. Vacuum stuff is available used quite widely.

Between the book and the catalog(s), you've got plenty of reading and
dreaming material for months.

Be aware, though, that high vacuum is like amateur telescope mirror
making.. frustrating, tedious, and gratifying when it works. There's a
surprising amount of craft in it. (and entirely in keeping with
time-nuttery)

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread EWKehren

Do we know any thing about the Neuchatel design for Galileo?
Bert Kehren
 
 
In a message dated 8/29/2010 11:05:58 A.M. Eastern Daylight Time,  
p...@phk.freebsd.dk writes:

In  message 4c7a6b01.3030...@rubidium.dyndns.org, Magnus Danielson  
writes:
On 08/29/2010 03:55 PM, Attila Kinali wrote:

It's a  complicated field and several traps to fall into on the way. It 
is a  fairly sizeable project to attempt.

Well, as with so much else, it  depends what the level of ambition is.

If you just want to be able to  point to the resonance and say I
did that, it is not intrinsically hard  and none of the materials
are hard to get hold of or particularly  poisonous.

Few of the problems Ramsey fought in the early 1950'ies are  relevante
today, for instance, the entire detection issue is trivially  solved
with USRP/GnuRadio.

I would tend to think that $10k in  materials would get you pretty
close.

I think the most recent  H-maser design is Neuchatels design for
the Galileo GNSS.

Building a  _good_ (ie: metrology grade) hydrogen maser, sounds like
the last  significant thing you did in your life, however many years
you have  left...

Poul-Henning

PS: And if you even manage to build  something which works half the
time, and do not suffer from ethics, there  is a finite but very
profitable market for audiopholery, and I'm sure  somebody is willing
to eliminate the last traces of jitter in his CD-player  for just
under $100k...

-- 
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice  what can adequately be explained by  
incompetence.

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Poul-Henning Kamp

In message 3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com writes:

Do we know any thing about the Neuchatel design for Galileo?
Bert Kehren

There are plenty of papers about it.

They started out with an active design, and got it inside spec
(power/weight) but found that the performance was not worth the
extra effort, so they switched to a passive design to further
reduce weight/power.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] homebrew H maser

This is very true. Norman Ramsey built one out of aluminum. It was at
least 6 feet in diameter and 8 feet long, at a guess. When I frequented
that lab (mid-late 80s), it was too big to get it out the door room so had
shelves inside to store equipment. It was inside a giant wooden crate,
easily 10' cubial.

-John

==



[snip]
 The size of the glass-bulb is not a fixed thing, during research and
 development different sizes glass-bulbs is used to establish the
 wall-shift aspects in order to adjust for it, which is needed in order
 to make absolute measurements on the free atom resonance or compensate
 into that regard.

 As for reference, there is about one set of books and papers from a
 handful of journals and a bunch of patents which needs to the read in
 order to build up the knowledge-base for attempting something like it.

 It's a complicated field and several traps to fall into on the way. It
 is a fairly sizeable project to attempt.

 Cheers,
 Magnus

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread jimlux


Poul-Henning Kamp wrote:

In message 3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com writes:


Do we know any thing about the Neuchatel design for Galileo?
Bert Kehren


There are plenty of papers about it.

They started out with an active design, and got it inside spec
(power/weight) but found that the performance was not worth the
extra effort, so they switched to a passive design to further
reduce weight/power.




there's also the Mercury Ion clock.. the physics package looks fairly 
simple...


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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Chuck Harris


jimlux wrote:

J. Forster wrote:

If you took a modern approach by using factory built test equipment as
building blocks (microwave synthesizer, lock-in amp, power supplies, etc)
and commercial vacuum components (pumps, valves, fittings, controllers,
etc. in Conflat or something like it), you could likely build up most
of a
system pretty easily.




You definitely need a copy of this book
http://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0813340063/ref=tmm_pap_title_0/182-2347235-0798235


Building Scientific Apparatus by Moore, Davies, and Coplan


It's Davis, as in C.C. Davis of the University of Maryland, my former
MS thesis adviser.

Its a great book, but very expensive.

-Chuck Harris

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread EWKehren

Any links to reading material, would be nice to learn what they did to get  
a small package and how small is it?
Bert Kehren
 
 
In a message dated 8/29/2010 2:03:34 P.M. Eastern Daylight Time,  
p...@phk.freebsd.dk writes:

In  message 3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com  writes:

Do we know any thing about the Neuchatel design for  Galileo?
Bert Kehren

There are plenty of papers about  it.

They started out with an active design, and got it inside  spec
(power/weight) but found that the performance was not worth  the
extra effort, so they switched to a passive design to further
reduce  weight/power.

-- 
Poul-Henning Kamp   | UNIX  since Zilog Zeus 3.20
p...@freebsd.org |  TCP/IP since RFC 956
FreeBSD committer   | BSD  since 4.3-tahoe
Never attribute to malice what can adequately  be explained by  
incompetence.

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Bruce Griffiths


http://www.spectratime.com/product_downloads/PTTI_FCS_2005.pdf


ewkeh...@aol.com wrote:

Any links to reading material, would be nice to learn what they did to get
a small package and how small is it?
Bert Kehren


In a message dated 8/29/2010 2:03:34 P.M. Eastern Daylight Time,
p...@phk.freebsd.dk writes:

In  message3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com  writes:

   

Do we know any thing about the Neuchatel design for  Galileo?
Bert Kehren
 

There are plenty of papers about  it.

They started out with an active design, and got it inside  spec
(power/weight) but found that the performance was not worth  the
extra effort, so they switched to a passive design to further
reduce  weight/power.

   




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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Mark Kahrs

The Hahvahd physics dept. has all number of interesting papers.

For example there's Humphrey's
dissertation:www.physics.harvard.edu/Thesespdfs/humphrey.pdf

If you've ever wanted to make your own Rb cell, how about this
one?cfa-www.harvard.edu/~dphil/work/coat.pdf
http://cfa-www.harvard.edu/%7Edphil/work/coat.pdf%20


On Sun, Aug 29, 2010 at 11:07 AM, Attila Kinali att...@kinali.ch wrote:

 On Sun, 29 Aug 2010 16:13:21 +0200
 Magnus Danielson mag...@rubidium.dyndns.org wrote:

  On 08/29/2010 03:55 PM, Attila Kinali wrote:
   Does anyone know whether any of those people collected their results
   somewhere? And if, where i could find them?
 
  The physical package is definitely where most of the effort goes in.

 I know, that's why i'm asking.
 The papers i've read sofar all suggest that the difficult part is to
 compensate for cavity detuning, wall shift and second order doppler
 effect. Somehow all these papers seem to assume that getting an
 oscillation at all is so easy that everyone could do it (yes, i know that
 this is normal with scientific papers).

 I thought, that if someone build a homebrew H maser, he'd write about
 the difficulties getting there. Which would be a very interesting reading
 and teach a lot about the physics (and tool making, mechanics, etc)
 of these devices.

  A
  complicating aspect is the self-tuning stuff for which several
  strategies may be chosen.

 I'd start here at getting a cavity that is resonant at the frequency
 at all. Getting sub-milimeter precision in tooling is quite easy
 (given you have the tools and knowledge, or can pay someone to do it for
 you),
 but if the cavity has to be resonant within a couple of Hz of the
 1.4xxxGHz, then you have to get a precission in the range of 10^-9
 which basically impossible mechanically. So the cavity would need to have
 a mechanical tuning system too, but one that doesn't lower the cavity's
 Q or add any additional resonant modes.

  You need to balance the rate of the atoms, as both too few and too many
  kills the oscillation.

 Or get to the basic requirement of getting a pure H2 source to feed
 the beam source. The beam source itself, including the dissociator,
 would be a formidable project to do at home by itself.

  The size of the glass-bulb is not a fixed thing, during research and
  development different sizes glass-bulbs is used to establish the
  wall-shift aspects in order to adjust for it, which is needed in order
  to make absolute measurements on the free atom resonance or compensate
  into that regard.

 Interestingly, i think that the bulb would be the easiest part
 these days. At least around here, there are a few glas blowers
 for the chemical/pharmaceutical industry that also do single pieces.
 Getting it coated would only involve finding a company that does
 teflon coating (there do seem enough of them). From what i gather
 it's shape doesnt have to be exactly spherical down to the
 sub-milimeter range.

  As for reference, there is about one set of books and papers from a
  handful of journals and a bunch of patents which needs to the read in
  order to build up the knowledge-base for attempting something like it.

 Which papers/books would you recommend reading?

 And no, i don't think i'd attempt to build a H maser.
 I'm quite confident i could do the electronics part, but i know that
 i don't know anything when it comes to mechanics. Much less about
 handling high vacuum and atomic gas beams.

  It's a complicated field and several traps to fall into on the way. It
  is a fairly sizeable project to attempt.

 Yes, but it's fun to read about it :-)

Attila Kinali

 --
 The trouble with you, Shev, is you don't say anything until you've saved
 up a whole truckload of damned heavy brick arguments and then you dump
 them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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[time-nuts] Homebrew H Maser

2010-08-29 Thread Corby Dawson

After keeping an old EFOS 2 H maser running the last couple or three
years here are a few bits of advice.

-The triple magnetic shields are VERY important. The first time I removed
the top
 shield to access the RF section the Maser stopped oscillating! Replacing
the shield
restored oscillations!
-The cavity does not have to be machined to super precise levels, in
this Maser once the coarse setting (mechanical at factory) is made, the
medium tuning is done by adjusting the cavity temperature. The fine is
done with the cavity varactor. This cavity is aluminum.
-from a cold start it takes about 1 week for the ovens to come up to
operating temp.!
-this maser has two vacuum sections, an outer that enclosed the cavity
and thermally insulates it. This allows the cavity temperature to be
regulated to within .001 degree C. The inner chamber keeps the cavity
evacuated so all you have in it is the H atoms.
-Making a homebrew collimator (at the discharge bulb output) might be
hard, google it and you will see it's  tricky.
-As stated the electronics are pretty easy these days. Main points are a
low Insertion loss, high isolation circulator on the cavity output, a low
noise figure RF amp and a low noise downconvertor.

I have, somewhere, a scan of the two manuals. There is lots of theory and
full schematics. Might be a good read if you are serious in trying to
homebrew one.
I'll dig them up and see if anyone could host them on a website. (Files
are quite large!)

Corby Dawson

1 Tip for Losing Weight
Cut down 2 lbs per week by using this 1 weird old tip
http://thirdpartyoffers.juno.com/TGL3141/4c7ac2d3136f9d283cm04duc

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Re: [time-nuts] homebrew H maser

2010-08-29 Thread Bruce Griffiths


http://tycho.usno.navy.mil/ptti/ptti2002/paper14.pdf
Bruce Griffiths wrote:

http://www.spectratime.com/product_downloads/PTTI_FCS_2005.pdf


ewkeh...@aol.com wrote:
Any links to reading material, would be nice to learn what they did 
to get

a small package and how small is it?
Bert Kehren


In a message dated 8/29/2010 2:03:34 P.M. Eastern Daylight Time,
p...@phk.freebsd.dk writes:

In  message3e227.34d2ee82.39abf...@aol.com, ewkeh...@aol.com  writes:


Do we know any thing about the Neuchatel design for  Galileo?
Bert Kehren

There are plenty of papers about  it.

They started out with an active design, and got it inside  spec
(power/weight) but found that the performance was not worth  the
extra effort, so they switched to a passive design to further
reduce  weight/power.





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Re: [time-nuts] homebrew H maser

2010-08-29 Thread jimlux


Chuck Harris wrote:

jimlux wrote:

J. Forster wrote:

If you took a modern approach by using factory built test equipment as
building blocks (microwave synthesizer, lock-in amp, power supplies, 
etc)

and commercial vacuum components (pumps, valves, fittings, controllers,
etc. in Conflat or something like it), you could likely build up most
of a
system pretty easily.




You definitely need a copy of this book
http://www.amazon.com/Building-Scientific-Apparatus-John-Moore/dp/0813340063/ref=tmm_pap_title_0/182-2347235-0798235 




Building Scientific Apparatus by Moore, Davies, and Coplan


It's Davis, as in C.C. Davis of the University of Maryland, my former
MS thesis adviser.


Sorry about that... yes..


Its a great book, but very expensive.



worth every penny if you're doing this sort of thing..


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Re: [time-nuts] Homebrew H Maser

2010-08-29 Thread John Miles


 After keeping an old EFOS 2 H maser running the last couple or three
 years here are a few bits of advice.

 -The triple magnetic shields are VERY important. The first time I removed
 the top
  shield to access the RF section the Maser stopped oscillating! Replacing
 the shield
 restored oscillations!

As I understand it, not only the intensity of the ambient H-field but its
orientation is critical.  Sounds like you either pulled the 1,0 - 0,0
transition frequency too far for the control loop to compensate, or the
static field was no longer oriented properly with respect to the cavity's TE
mode axis.

The impression I got from my reading on the subjecct is that tuning an
H-maser isn't something you can do incrementally.  It's not a conventional
RF tank circuit -- there's a list of factors as long as your arm that have
to be just right, or you will get nothing at all for your trouble.  Getting
those factors right seems to require a graduate-level understanding of both
the materials and the math.  Ars longa, vita brevis.

 -this maser has two vacuum sections, an outer that enclosed the cavity
 and thermally insulates it. This allows the cavity temperature to be
 regulated to within .001 degree C. The inner chamber keeps the cavity
 evacuated so all you have in it is the H atoms.

I imagine the cavity has to be pretty stout not to either collapse from
barometric pressure or flex excessively.

 I'll dig them up and see if anyone could host them on a website. (Files
 are quite large!)

It would be great if you could upload these to the Manuals page at
www.ko4bb.com.  I've looked over the Symmetricom maser's manual but it's
pretty terse.

 Building Scientific Apparatus by Moore, Davies, and Coplan

 It's Davis, as in C.C. Davis of the University of Maryland, my former
 MS thesis adviser.

 Sorry about that... yes..
 Its a great book, but very expensive.
 worth every penny if you're doing this sort of thing..

The current edition is $70 at Amazon, not too bad by textbook standards.
It's a good book, but often more valuable as a pointer for further reading
than as a practical, up-to-date handbook.  Seems like a good overview of
vacuum technology.

The book you really want to start with is Major's The Quantum Beat, IMHO.

In thinking about it, it would be a terrific project to run with LabView!
Rubbish, LabView would _never_ be able to do that.

(Shrug) PLLs are PLLs.  I don't see a role for a PC in the cavity tuning or
oscillator disciplining loops, but that's a very small part of the overall
control picture.  Most of the actual software work would involve UI design
for monitoring (and ideally graphing) the dozens of operating parameters
over time.  It would probably make the most sense to use either analog or
microcontroller-based controls for the realtime (RF) loops, and use Labview
or another instrumentation package to monitor everything.

There are also various high-latency thermal loops that could be controlled
as well as monitored by Labview-like software on the PC.

-- john, KE5FX


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Re: [time-nuts] Homebrew H Maser

2010-08-29 Thread Didier Juges

 I'll dig them up and see if anyone could host them on a website. (Files
 are quite large!)

It would be great if you could upload these to the Manuals page at
www.ko4bb.com.  

That would be great. If the files are really big (over 100MB) and if your 
internet access is not truly broadband, you may find it more convenient to put 
them on a CD/DVD and snail mail them to me if you prefer.

Either way is fine with me

Didier KO4BB
 
 
Sent from my BlackBerry Wireless thingy while I do other things...

-Original Message-
From: John Miles jmi...@pop.net
Sender: time-nuts-boun...@febo.com
Date: Sun, 29 Aug 2010 16:39:42 
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Homebrew H Maser


 After keeping an old EFOS 2 H maser running the last couple or three
 years here are a few bits of advice.

 -The triple magnetic shields are VERY important. The first time I removed
 the top
  shield to access the RF section the Maser stopped oscillating! Replacing
 the shield
 restored oscillations!

As I understand it, not only the intensity of the ambient H-field but its
orientation is critical.  Sounds like you either pulled the 1,0 - 0,0
transition frequency too far for the control loop to compensate, or the
static field was no longer oriented properly with respect to the cavity's TE
mode axis.

The impression I got from my reading on the subjecct is that tuning an
H-maser isn't something you can do incrementally.  It's not a conventional
RF tank circuit -- there's a list of factors as long as your arm that have
to be just right, or you will get nothing at all for your trouble.  Getting
those factors right seems to require a graduate-level understanding of both
the materials and the math.  Ars longa, vita brevis.

 -this maser has two vacuum sections, an outer that enclosed the cavity
 and thermally insulates it. This allows the cavity temperature to be
 regulated to within .001 degree C. The inner chamber keeps the cavity
 evacuated so all you have in it is the H atoms.

I imagine the cavity has to be pretty stout not to either collapse from
barometric pressure or flex excessively.

 I'll dig them up and see if anyone could host them on a website. (Files
 are quite large!)

It would be great if you could upload these to the Manuals page at
www.ko4bb.com.  I've looked over the Symmetricom maser's manual but it's
pretty terse.

 Building Scientific Apparatus by Moore, Davies, and Coplan

 It's Davis, as in C.C. Davis of the University of Maryland, my former
 MS thesis adviser.

 Sorry about that... yes..
 Its a great book, but very expensive.
 worth every penny if you're doing this sort of thing..

The current edition is $70 at Amazon, not too bad by textbook standards.
It's a good book, but often more valuable as a pointer for further reading
than as a practical, up-to-date handbook.  Seems like a good overview of
vacuum technology.

The book you really want to start with is Major's The Quantum Beat, IMHO.

In thinking about it, it would be a terrific project to run with LabView!
Rubbish, LabView would _never_ be able to do that.

(Shrug) PLLs are PLLs.  I don't see a role for a PC in the cavity tuning or
oscillator disciplining loops, but that's a very small part of the overall
control picture.  Most of the actual software work would involve UI design
for monitoring (and ideally graphing) the dozens of operating parameters
over time.  It would probably make the most sense to use either analog or
microcontroller-based controls for the realtime (RF) loops, and use Labview
or another instrumentation package to monitor everything.

There are also various high-latency thermal loops that could be controlled
as well as monitored by Labview-like software on the PC.

-- john, KE5FX


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Re: [time-nuts] Homebrew H Maser