Re: [time-nuts] What's the lifetime for a HP Z3801a?

[mike cook]

Le 29/08/2010 04:26, Hal Murray a écrit :



Have a pair of Z3801a receivers and GPSCon. The running time readout for
both is greater than 16,000. They were around 5,000 when I got them from
somewhere south of here.

I assume the units are hours, but my copy of the manual doesn't say what the
units are.
Units are three hour periods - See the 58503B Operation and programming 
guide, 5-71
HP were pretty confident in the lifetime of their product as they allow 
a 4Gig count before rollover.

The are built for the telecom industry.  I'd expect most of them to last
10-20 years.

There is nothing inside that obviously wears out.  The electrolytic caps may
be the weak link.

365*24 is 8760 so 16K is only 2 years.  Youngsters.







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Re: [time-nuts] What's the lifetime for a HP Z3801a?

[Mike Feher]

I do not know how to read out the "run time", but, one of mine has been
running continuously for about 8 or more years now just since I have owned
it. Regards - Mike

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960



-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bill Hawkins
Sent: Saturday, August 28, 2010 7:31 PM
To: 'Discussion of precise time and frequency measurement'
Subject: [time-nuts] What's the lifetime for a HP Z3801a?

Have a pair of Z3801a receivers and GPSCon. The running time
readout for both is greater than 16,000. They were around 5,000
when I got them from somewhere south of here.

What kind of numbers do you have?

Bill Hawkins


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Re: [time-nuts] What's the lifetime for a HP Z3801a?

[mike cook]

  execute :DIAGnostic:LIFetime:COUNT?

Wow, that's a long time without a power cut.

Le 29/08/2010 12:30, Mike Feher a écrit :

I do not know how to read out the "run time", but, one of mine has been
running continuously for about 8 or more years now just since I have owned
it. Regards - Mike

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960



-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Bill Hawkins
Sent: Saturday, August 28, 2010 7:31 PM
To: 'Discussion of precise time and frequency measurement'
Subject: [time-nuts] What's the lifetime for a HP Z3801a?

Have a pair of Z3801a receivers and GPSCon. The running time
readout for both is greater than 16,000. They were around 5,000
when I got them from somewhere south of here.

What kind of numbers do you have?

Bill Hawkins


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[time-nuts] High resolution temperatur sensor ?

[Peter Krengel]

Hi group

watching tbolts disciplining it shows that is has a low resolution temperatur
sensor only which can be replaced by a high res. one.
Is there any document what typ it is and how to change it?

Thank you

regards
Peter, DG4EK 
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Re: [time-nuts] What's the lifetime for a HP Z3801a?

[Mike Feher]

Can I do that from SatStat? Well, you are right, there have been a few power
outages, but, hardly long enough to make any difference in the total run
time :). - Mike

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960




-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of mike cook
Sent: Sunday, August 29, 2010 7:16 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] What's the lifetime for a HP Z3801a?

   execute :DIAGnostic:LIFetime:COUNT?

Wow, that's a long time without a power cut.

Le 29/08/2010 12:30, Mike Feher a écrit :
> I do not know how to read out the "run time", but, one of mine has been
> running continuously for about 8 or more years now just since I have owned
> it. Regards - Mike
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>
>
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of Bill Hawkins
> Sent: Saturday, August 28, 2010 7:31 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] What's the lifetime for a HP Z3801a?
>
> Have a pair of Z3801a receivers and GPSCon. The running time
> readout for both is greater than 16,000. They were around 5,000
> when I got them from somewhere south of here.
>
> What kind of numbers do you have?
>
> Bill Hawkins
>
>
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>




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Re: [time-nuts] High resolution temperatur sensor ?

[Didier Juges]

Google "time-nuts thunderbolt temperature sensor"

Didier 

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Peter Krengel
Sent: Sunday, August 29, 2010 6:22 AM
To: time-nuts@febo.com
Subject: [time-nuts] High resolution temperatur sensor ?

Hi group

watching tbolts disciplining it shows that is has a low resolution
temperatur sensor only which can be replaced by a high res. one.
Is there any document what typ it is and how to change it?

Thank you

regards
Peter, DG4EK
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Re: [time-nuts] What's the lifetime for a HP Z3801a?

[Ulrich Bangert]

Mike,

> Can I do that from SatStat? 

If you can't then you can do it with my free Z38XX.

Best regards
Ulrich

> -Ursprüngliche Nachricht-
> Von: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] Im Auftrag von Mike Feher
> Gesendet: Sonntag, 29. August 2010 13:25
> An: 'Discussion of precise time and frequency measurement'
> Betreff: Re: [time-nuts] What's the lifetime for a HP Z3801a?
> 
> 
> Can I do that from SatStat? Well, you are right, there have 
> been a few power outages, but, hardly long enough to make any 
> difference in the total run time :). - Mike
> 
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
> 
> 
> 
> 
> -Original Message-
> From: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] On Behalf Of mike cook
> Sent: Sunday, August 29, 2010 7:16 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] What's the lifetime for a HP Z3801a?
> 
>execute :DIAGnostic:LIFetime:COUNT?
> 
> Wow, that's a long time without a power cut.
> 
> Le 29/08/2010 12:30, Mike Feher a écrit :
> > I do not know how to read out the "run time", but, one of mine has 
> > been running continuously for about 8 or more years now 
> just since I 
> > have owned it. Regards - Mike
> >
> > Mike B. Feher, N4FS
> > 89 Arnold Blvd.
> > Howell, NJ, 07731
> > 732-886-5960
> >
> >
> >
> > -Original Message-
> > From: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] 
> > On Behalf Of Bill Hawkins
> > Sent: Saturday, August 28, 2010 7:31 PM
> > To: 'Discussion of precise time and frequency measurement'
> > Subject: [time-nuts] What's the lifetime for a HP Z3801a?
> >
> > Have a pair of Z3801a receivers and GPSCon. The running 
> time readout 
> > for both is greater than 16,000. They were around 5,000 when I got 
> > them from somewhere south of here.
> >
> > What kind of numbers do you have?
> >
> > Bill Hawkins
> >
> >
> > ___
> > 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.
> >
> >
> > ___
> > 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] What's the lifetime for a HP Z3801a?

[Mike Feher]

Thanks Ulrich - I have been meaning to try your software anyway. Hope to
find some time for it soon. 73 - Mike

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960




-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Ulrich Bangert
Sent: Sunday, August 29, 2010 7:32 AM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] What's the lifetime for a HP Z3801a?

Mike,

> Can I do that from SatStat? 

If you can't then you can do it with my free Z38XX.

Best regards
Ulrich

> -Ursprüngliche Nachricht-
> Von: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] Im Auftrag von Mike Feher
> Gesendet: Sonntag, 29. August 2010 13:25
> An: 'Discussion of precise time and frequency measurement'
> Betreff: Re: [time-nuts] What's the lifetime for a HP Z3801a?
> 
> 
> Can I do that from SatStat? Well, you are right, there have 
> been a few power outages, but, hardly long enough to make any 
> difference in the total run time :). - Mike
> 
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
> 
> 
> 
> 
> -Original Message-
> From: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] On Behalf Of mike cook
> Sent: Sunday, August 29, 2010 7:16 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] What's the lifetime for a HP Z3801a?
> 
>execute :DIAGnostic:LIFetime:COUNT?
> 
> Wow, that's a long time without a power cut.
> 
> Le 29/08/2010 12:30, Mike Feher a écrit :
> > I do not know how to read out the "run time", but, one of mine has 
> > been running continuously for about 8 or more years now 
> just since I 
> > have owned it. Regards - Mike
> >
> > Mike B. Feher, N4FS
> > 89 Arnold Blvd.
> > Howell, NJ, 07731
> > 732-886-5960
> >
> >
> >
> > -Original Message-
> > From: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] 
> > On Behalf Of Bill Hawkins
> > Sent: Saturday, August 28, 2010 7:31 PM
> > To: 'Discussion of precise time and frequency measurement'
> > Subject: [time-nuts] What's the lifetime for a HP Z3801a?
> >
> > Have a pair of Z3801a receivers and GPSCon. The running 
> time readout 
> > for both is greater than 16,000. They were around 5,000 when I got 
> > them from somewhere south of here.
> >
> > What kind of numbers do you have?
> >
> > Bill Hawkins
> >
> >
> > ___
> > 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.
> >
> >
> > ___
> > 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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[time-nuts] homebrew H maser

[Attila Kinali]

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?

Thanks

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

[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

[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

[Attila Kinali]

On Sun, 29 Aug 2010 16:13:21 +0200
Magnus Danielson  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

[Attila Kinali]

On Sun, 29 Aug 2010 15:05:05 +
"Poul-Henning Kamp"  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] What's the lifetime for a HP Z3801a?

[Bill Hawkins]

Merci beaucoup, mike.

I hadn't done the right record-keeping to discover the actual units.

They've been running for 6-7 years, not two, so that works out.

Bill Hawkins

-Original Message-
From: mike cook
Sent: Sunday, August 29, 2010 2:44 AM

Le 29/08/2010 04:26, Hal Murray a écrit :
>
>> Have a pair of Z3801a receivers and GPSCon. The running time readout for
>> both is greater than 16,000. They were around 5,000 when I got them from
>> somewhere south of here.

> I assume the units are hours, but my copy of the manual doesn't say what
the
> units are.

Units are three hour periods - See the 58503B Operation and programming 
guide, 5-71.
HP were pretty confident in the lifetime of their product as they allow 
a 4 Gig count before rollover.


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Re: [time-nuts] What's the lifetime for a HP Z3801a?

[Dan Rae]

 My Z3801A is quite happy still plugging along at 35,208 units of life 
time...

dr

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Re: [time-nuts] homebrew H maser

[J. Forster]

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

[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
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Re: [time-nuts] homebrew H maser

[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

[J. Forster]

[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

[J. Forster]

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

[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

[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

[J. Forster]

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

[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

[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] Better GPS

[bg]

Hi,

> Hi
>
> I've been digging around at acc.igs.org. They seem to think that their
> clock models are good to below 0.05 ns. They compare that to a 2 ns number
> for the "as broadcast" models. 2 ns is a pretty familiar number if you
> look at a lot of TBolt plots. All of their data is online and available
> for download at some point in time past live. The longer you wait the
> better the data.

You can get some improvement even in 'real-time' by using the ultra-radid
(predicted) data available over Internet.

 http://igscb.jpl.nasa.gov/components/prods.html

> They really like the idea of L1/L2 receivers and fancy post processing.
> They also are after a lot more than just time. I still have not noticed
> any complete L1/L2 receivers for < $100, so I can't do their full solution
> approach. Ionospheric correction seems to be one big thing you loose by
> going single freq.

Yes, but you would only need one dual freq receiver to estimate the Iono.
Or have real time access to one in the vincinity. Another way, would be to
use the models for Iono and Tropo errors that are available in real time.
One example is the SBAS (Waas, Egnos, Msas, etc) signals. They should get
you down below 2 meters. Perhaps there are online models for prediction of
Iono related radio communications that could be useful.

Beeing connected to Internet opens a whole lot of possible improvements
not available for the classic standalone GPS receiver.

> There's a pretty good summary of all that at
> http://acc.igs.org/UsingIGSProductsVer21.pdf
>
> Since the TBolt sort but not quite of does carrier phase you might be able
> to use their data to improve things. I doubt that you would get to 50 ps,
> but even a 2 or 3X improvement would be worthwhile. Even getting it some
> of the time (midnight?) would still be useful. It would be a log lots of
> data and compare thing - not that unusual.
>
> Has anybody else dug into any of this?

I think we should examine the Tbolt measurement capabilities a little
further. One experiment that would eliminate local clock errors would be
to compare two Tbolts sharing both antenna and the same oscillator.

This is one avenue of might be improvements of the already good Tbolt
GPSDO. Other paths as controlling the temperature and optimizing control
parameters are ofcause also interesting.

> Is there a secret stash of cheap L1/L2 fixed location receivers out there
> that I haven't stumbled across?

Check with local surveying outfits, or close by CORS stations they might
have old receivers collecting dust.

--

   Björn


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Re: [time-nuts] homebrew H maser

[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

[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  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.

   




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Re: [time-nuts] homebrew H maser

[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



On Sun, Aug 29, 2010 at 11:07 AM, Attila Kinali  wrote:

> On Sun, 29 Aug 2010 16:13:21 +0200
> Magnus Danielson  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

[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

[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  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.





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Re: [time-nuts] homebrew H maser

[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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[time-nuts] Z3801A version issues - was Re: Substitute GPS in a Z3801A

[Matthew Kaufman]

 I believe I've found a difference between the faulty units and the 
working units... The faulty ones come up as 1/1/1997 when you do 
:SYSTEM:PRESET, the good ones come up as 1/1/1998. Does this difference 
ring any bells for anyone?


Matthew Kaufman

On 6/24/2010 8:41 AM, Matthew Kaufman wrote:
I now have *two* Z3801A units which misbehave in the following way 
(which this thread reminded me of):


The GPS status says it acquires quite a few (5-6) satellites with high 
signal strength... then after a minute or two, for no apparent reason, 
it loses *all* of them simultaneously but immediately goes back into 
"acquiring" for the ones it was seeing, and a few seconds later, 
they're all back. During this time, survey (if in progress) is halted 
and then restarts and runs for a bit before halting again when it 
loses everything briefly again. Then, within days, the unit ends up 
out of lock... if I go check it, I see it doing the same thing, and 
when the satellites are being received it is in "fine frequency 
adjust" mode, but so far off the 1pps phase that it really has no hope 
of re-locking before the next time it drops and then reacquires all 
the satellites.


This is independent of antenna, location, and 48v power source... one 
unit apparently has been this way since I got it, the other worked 
fine for months and then developed this problem.


Without knowing more, I'm thinking it might simply be a bad GPS 
receiver board, thus the idea of trying to find a replacement, perhaps 
one that is better at staying acquired, has crossed my mind.


Matthew Kaufman

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Re: [time-nuts] What's the lifetime for a HP Z3801a?

[Hal Murray]

mike.c...@orange.fr said:
> Units are three hour periods - See the 58503B Operation and programming
> guide, 5-71 HP were pretty confident in the lifetime of their product as
> they allow  a 4Gig count before rollover. 

Thanks.

I wonder why they tossed in the factor of 3.  Hours seems like a fine unit.  
(With 32 bits, seconds is even reasonable.  That's 136 years, or 68 years if 
you trip over the sign bit.)



-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] Homebrew H Maser

[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

[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" 
Sender: time-nuts-boun...@febo.com
Date: Sun, 29 Aug 2010 16:39:42 
To: Discussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement

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

[J. Forster]

Yes and no.

I watched while a cryogenic MASER experiment was done at Harvard.

First off, a H MASER built at Smithsonian Astrophysical Observatory, was
set up and a GPS set up as a comparison. This was late 1980s.

That MASER was used as a reference for a synthesizer which was swept a
Hertz two around the 1421 MHz frequency to excite the cavity. The cavity
was peaked with a reflectometer using a narrow sweep and then H was added.
Parameters were adjusted while the cavity microwave field monitored.

The RF field was pulsed, as I remember, and they watched as the RF decayed
in a damped exponential. You could see what was happening to the gain of
the medium, the decay took longer, and parameters were slowly adjusted to
the point where there was enough gain to oscillate and thing "took off".

Fun stuff, if you have lots of time.

Best,

-J0ohn

==

> 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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>
>



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Re: [time-nuts] Homebrew H Maser

[Bob Paddock]

On Sun, Aug 29, 2010 at 7:56 PM, Didier Juges  wrote:

> >> 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.
>

Try the old DjVu Solo 3.1 program that you can download from here:
http://djvu.org/resources/
I've seen it turn 100M page scans into 100K files.  If you want to turn the
DjVu into a PDF, use the Print command to a PDF driver, such as GhostScript,
or Acrobat.


-- 
http://blog.softwaresafety.net/
http://www.designer-iii.com/
http://www.wearablesmartsensors.com/
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Re: [time-nuts] Z3801A version issues - was Re: Substitute GPS in a Z3801A

[paul swed]

I seem to remember a rollover about then that obsoleted older gps units.

On Sun, Aug 29, 2010 at 5:40 PM, Matthew Kaufman  wrote:

>  I believe I've found a difference between the faulty units and the working
> units... The faulty ones come up as 1/1/1997 when you do :SYSTEM:PRESET, the
> good ones come up as 1/1/1998. Does this difference ring any bells for
> anyone?
>
> Matthew Kaufman
>
> On 6/24/2010 8:41 AM, Matthew Kaufman wrote:
>
>> I now have *two* Z3801A units which misbehave in the following way (which
>> this thread reminded me of):
>>
>> The GPS status says it acquires quite a few (5-6) satellites with high
>> signal strength... then after a minute or two, for no apparent reason, it
>> loses *all* of them simultaneously but immediately goes back into
>> "acquiring" for the ones it was seeing, and a few seconds later, they're all
>> back. During this time, survey (if in progress) is halted and then restarts
>> and runs for a bit before halting again when it loses everything briefly
>> again. Then, within days, the unit ends up out of lock... if I go check it,
>> I see it doing the same thing, and when the satellites are being received it
>> is in "fine frequency adjust" mode, but so far off the 1pps phase that it
>> really has no hope of re-locking before the next time it drops and then
>> reacquires all the satellites.
>>
>> This is independent of antenna, location, and 48v power source... one unit
>> apparently has been this way since I got it, the other worked fine for
>> months and then developed this problem.
>>
>> Without knowing more, I'm thinking it might simply be a bad GPS receiver
>> board, thus the idea of trying to find a replacement, perhaps one that is
>> better at staying acquired, has crossed my mind.
>>
>> Matthew Kaufman
>>
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>
>
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[time-nuts] HP-5342A Questions

[Mark Gulbrandsen]

I recently aquired an HP- 5342A microwave counter. It has a blown fuse on the 
10 to 500 meg input jack. Does anyone know the correct value of this fuse? I 
assume it's a Pico Fuse and I do find a fuse listed for the A-2 board that is 
.1 amp @ 125 volts fast blow. However, the fuse which is inside the BNC jack is 
actually part of the A-1 board. Any help properly identifying this fuse would 
be greatly appreciated.  Also, if anyone out there has a unit they are 
stripping I need a new sampler HP PN is 5088-7022. The one in this unit is bad.
 
Thanks in advance for your kind help!
 
Mark
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[time-nuts] PICTIC II chip order, CLOSED.

[Robert Darlington]

Just an update.   Ordering of the PICTIC II chips from me is now closed.   I
might do a run in a few months if there is demand.  I'll get the chips
ordered tonight or tomorrow and will do my best to get them out to you guys
by the end of next weekend.

Just an FYI for those that are interested, I'm using an up to date firmware
version of the PICStart Plus device programmer with MPLAB (whatever is
current).  I haven't touched the original code, nor have I compiled the code
other than as a test.  My compiled code is the same size as the original hex
code, but I'm still using the original hex file since I didn't do a binary
compare to verify they're the same.  I program and verify every chip that
comes out of the programmer to make sure the code is on there right.

Enjoy,
Bob
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Re: [time-nuts] Z3801A version issues - was Re: Substitute GPS in a Z3801A

[mike cook]

 would that have shown up in a firmware version id change?

try *IDN? and see if there is any correlation Matthew.



Le 30/08/2010 03:23, paul swed a écrit :

I seem to remember a rollover about then that obsoleted older gps units.

On Sun, Aug 29, 2010 at 5:40 PM, Matthew Kaufman  wrote:


  I believe I've found a difference between the faulty units and the working
units... The faulty ones come up as 1/1/1997 when you do :SYSTEM:PRESET, the
good ones come up as 1/1/1998. Does this difference ring any bells for
anyone?

Matthew Kaufman

On 6/24/2010 8:41 AM, Matthew Kaufman wrote:


I now have *two* Z3801A units which misbehave in the following way (which
this thread reminded me of):

The GPS status says it acquires quite a few (5-6) satellites with high
signal strength... then after a minute or two, for no apparent reason, it
loses *all* of them simultaneously but immediately goes back into
"acquiring" for the ones it was seeing, and a few seconds later, they're all
back. During this time, survey (if in progress) is halted and then restarts
and runs for a bit before halting again when it loses everything briefly
again. Then, within days, the unit ends up out of lock... if I go check it,
I see it doing the same thing, and when the satellites are being received it
is in "fine frequency adjust" mode, but so far off the 1pps phase that it
really has no hope of re-locking before the next time it drops and then
reacquires all the satellites.

This is independent of antenna, location, and 48v power source... one unit
apparently has been this way since I got it, the other worked fine for
months and then developed this problem.

Without knowing more, I'm thinking it might simply be a bad GPS receiver
board, thus the idea of trying to find a replacement, perhaps one that is
better at staying acquired, has crossed my mind.

Matthew Kaufman

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