Re: [time-nuts] Tektronix FCA3103 ADEV measurement tau setting problem

[Richard (Rick) Karlquist]

On 5/28/2018 1:44 PM, Bob kb8tq wrote:

Hi

TimeLab will work with some counters and it will do most of the common plots. 
It is indeed free …..

Bob



The TimeLab manual says it will support any counter that can
dump data in Talk Only mode.  The Tek manual doesn't mention
Talk Only mode.  The TimeLab manual also (vaguely) says it
will support the HP53132, but doesn't specify if this is
simply referring to Talk Only mode, or a more complete interface.
The Tek manual says that it has a 53132 compatibility mode
available over GPIB using SCPI commands.  If the TimeLab
interface uses SCPI as well, I might be in business.  Does
anyone know about that?

Rick N6RK
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Re: [time-nuts] Tektronix FCA3103 ADEV measurement tau setting problem

[Richard (Rick) Karlquist]

On 5/29/2018 11:58 AM, gandalfg8--- via time-nuts wrote:



Unfortunately, I can't help with your enquiry, and am also somewhat confused, as I don't 
recall seeing a settings entry window for "tau" as a settings option for the 
built in ADEV function. I take it you do mean the built in option as in displaying 
results on the built in screen, or are you also using some external software?




Nigel, GM8PZR



I didn't explain this right.  The Tek counter allows me to set
"gate time" or something like that.  I am assuming that this
is the same as tau when measuring ADEV.  You'll never see
the word "tau" on the screen.  In any event, gate times less
than 200 ms (even 199 ms) don't appear to work for ADEV.

Rick, N6RK
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[time-nuts] Tektronix FCA3103 ADEV measurement tau setting problem

[Richard (Rick) Karlquist]

I have a Tek FCA3103 300 MHz counter that measures ADEV
as a built in function.  When I bring up the settings
menu for the measurement, it has an entry window for
"tau" (the averaging time, IE "sigma sub y of tau").
It defaults to 200 ms.  I can enter larger values and
ADEV gives reasonably results.  However, if I enter
smaller values, even 199 ms, I don't get any error
on the display, but I get clearly erroneous
results for ADEV. I read the manual and cannot find
anything to the effect that the instrument doesn't work
for less than 200 ms.

BTW, I asked Tek "customer no support" about it and
they were clueless.

1.  Is this pilot error?  Can anyone tell me the trick?

2.  Can anyone recommend a 300 MHz counter that measures
ADEV, correctly :-)?  Bonus question:  a counter that
measures Hadamard variance?

3.  Can anyone recommend a 300 MHz counter that can
measure ADEV and Hadamard using off the shelf software
that runs on a PC?  I don't write software :-)
Bonus question:  software to make these measurements
that works with the FCA3103 that I already have?

I have an NI GPIB-USB-HS to interface the counter
to the PC running the software if that helps.



Thanks

Rick N6RK
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Re: [time-nuts] Improving ocxo temp control

[Richard (Rick) Karlquist]

In my experience, the oven temperature controller is rarely
the determining factor for static oven performance.  This article
explains what the real determining factors are:

http://www.karlquist.com/oven.pdf

An analog oven temperature controller will be limited in
its dynamics by how much capacitance you are able to
design with.  Digital controllers get around this as well
as having the capability of double integration for much
better transient response.

Rick

On 5/18/2018 11:03 AM, Gilles Clement wrote:

Hi,
I am trying to improve performance of an OCXO.
Could you point me at a good design of a high resolution oven temperature 
controler please ? Preferably analog.
Thx much,
Gilles.


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Re: [time-nuts] Traveling to the US west coast

[Richard (Rick) Karlquist]

I'm also interested if it can be arranged.
It would be great to be able to meet Attila in person.

Rick

On 5/18/2018 9:36 AM, Jerry Hancock wrote:

Are you going to be in San Francisco area?  Maybe we could get a time-nuts 
breakfast together with a couple of us.

Regards,

Jerry




On May 17, 2018, at 11:25 PM, Attila Kinali  wrote:

Hi,

Some of you might already know, I will fly to the US west coast
to attend IFCS. Afterwards, I will be in Seattle for a couple of
days (from 25th to 31st). If you are in the area and want to meet up,
please drop me an email (off-list).


Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Better quartz crystals with single isotope ?

[Richard (Rick) Karlquist]

On 4/22/2018 10:20 AM, Bob kb8tq wrote:


Do we know anybody in the quartz business who needs a really cool
research project ?


You could put it on the list with the 1 Kg quartz resonator proposal …..

https://tf.nist.gov/general/pdf/2638.pdf 


Also an offshoot of people thinking about the implications of all this as it 
relates to resonators.


Bob



The cited article "must be true" because of its authors, I guess, but it
makes no sense to me.  They seem to be assuming that the resonant
frequency is inversely proportional to mass?  We all know three things:

1.  Frequency is inversely proportional to thickness.  Not mass.

2.  Frequency aging is affected by stress relaxation in well built
resonators.  The old idea that mass is gradually evaporating from
the resonator to the enclosure (glass enclosures) or mass is gradually
evaporating from the enclosure (metal enclosures) to depositing
on the resonator is simply obsolete in terms of current technology.
Thus again frequency is not a proxy for mass.

3. Resonators can "jump" in frequency without jumping in mass.

Given these facts, I am lost as how this is supposed to work.
Surely, the authors are well aware of the 3 items above.

Also, why does the resonator have to be a whole kilogram anyway.
If it weighed exactly 10 grams, couldn't you still compare it
to a kilogram using 100:1 leverage?

Can anyone straighten me out?

Rick
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[time-nuts] 1 kg standard (was:Re: Better quartz crystals with single isotope ?)

[Richard (Rick) Karlquist]

A neophyte question about this topic:  Since we know that 0.001
cubic meter of water displaces 1 liter, and that it weighs 1 kg,
and meters are based on wavelengths of light, why
do we need a separate artifact of mass?  Also, can we measure
the mass of the artifact in Paris based on water substitution?

Articles about this topic are always presented as if the answers
are obvious.

Don't they base 0 degree Celsius on the triple point of water?
What's wrong with that?


Rick

On 4/22/2018 10:20 AM, Bob kb8tq wrote:

Hi



On Apr 22, 2018, at 12:19 PM, Poul-Henning Kamp  wrote:

Silicon comes in a number of isotopes but 95% of it is Silicon-28.

When you make pure mono-crystaline silicon, you get 50-60% better
thermal conductivity if you only use Silicon-28 atoms.

Yes, you read that right:  50-60% improvement for removing the
remaining 5% other silicon isotopes, and for this and other reasons,
sorting silicon atoms by isotope is now a thing, which amongst other
side effects have made the Advogardo Project possible.

I can't help wonder if there may be similar interesting effects in
quartz crystals, if they were monoisotopic ?

Several relevant mechanisms can be imagined, lower internal damping,
higher stiffness etc. etc.

We know a LOT about quartz and have a very good theory for its
behaviours, but i find no signs anybody has ever touched monoisotopic
Quartz.

The obvious experiment is not rocket-science, nor does it demand
inordinate resources for amateurs, see for instance from 03:35:

https://archive.org/details/59554KrystallosCF

But it is clearly beyond what I have time to persue.

Do we know anybody in the quartz business who needs a really cool
research project ?


You could put it on the list with the 1 Kg quartz resonator proposal …..

https://tf.nist.gov/general/pdf/2638.pdf 


Also an offshoot of people thinking about the implications of all this as it 
relates to resonators.


Bob




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] 4046 replacement

[Richard (Rick) Karlquist]

On 4/18/2018 3:15 PM, Magnus Danielson wrote:


The real benefit of the 4044 and 4046 lies in that they where CMOS
devices and integrated well with other CMOS devices, and could help to


The original MC4044 is TTL, not CMOS.  There is a CMOS "CD4044"
but it is something completely different, not even a phase detector at all.

Rick N6RK
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Re: [time-nuts] 4046 replacement

[Richard (Rick) Karlquist]

On 4/18/2018 6:27 AM, Bob kb8tq wrote:

Hi

If this is a new build, why use a 4046 in the first place? There are many newer 
parts
that will do all sorts of things. If this is a repair of something that has 
been running
for years, is it > 5V supply to the chips? If so, you are pretty much stuck 
with 4000
series CMOS.

There are no fatal flaws in the 4046, but there are basic design limitations. 
Those
have been well documented over the years and here on the list. Going to a better
part is the answer for that stuff ( = get away from  any 4046 IC).

Bob



Any 4000 series CMOS, besides being extremely slow (prop
delay measured in MICROseconds), have a totem pole output
that momentarily short circuits the power supply when
switching and generates tremendous EMI.

I once wasted several weeks of time running down a spur
problem that I eventually traced to a 4XXX frequency divider.

Rick N6RK

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Re: [time-nuts] 4046 replacement

[Richard (Rick) Karlquist]

On 4/18/2018 4:34 AM, John Miles wrote:


Ulrich Rohde's book indicates that this problem was first documented in 1978 in 
an EDN article by some authors named Egan and Clark.  Newer PFDs implement the 
'antibacklash' logic that Rohde mentions.  If you really must use a 4046, I'd 
look for a newer version whose data sheet explicitly addresses this problem.  
Better still, use a newer part.


The book is incorrect.  A patent issued in 1976 (US4023116A)
covering the Fairchild 11C44 developed by Eric Breeze predates
the EDN article by several years.  I still remember the big
splash the 11C44 made when it was introduced in 1976. The Fairchild
ECL data book had a famous graph comparing it to the MC4044
in the dead zone.  In those days, Fairchild and Motorola
were going head to head.  I worked on a synthesizer in 1975
that used their brand new at the time 11C90 prescaler.

You can still get 11C44's of a sort by ordering NTE974's
that claim to be a replacement.

Rick N6RK
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Re: [time-nuts] Any guesses as to how Citizen is claiming ±1 second/year with using this AT-cut 8.4MHz XTAL?

[Richard (Rick) Karlquist]

The aging spec on the 10811 is 5 parts in 10^10 per day.
After 60 days, it could be off 30 ppb.  So what we
have here is a non-ovenized AT cut that is better
than an ovenized SC cut.  I'm sure.

I am reminded of the old Accutron ads.  The headlines
guaranteed so many seconds a day or whatever it was.
The fine print says they don't actually guarantee that.
The only remedy under that guarantee is that they
agree to adjust the watch to be in spec at the
watch repair shop and hand it back to you.  Thus,
they didn't have to worry about aging.  Just come
into the shop as often as necessary :-)

Rick N6RK

On 4/11/2018 9:26 AM, tn...@joshreply.com wrote:

That comes out to about 30ppb, and this is a pocket watch so they don’t seem
to depend on the temp stabilization of being attached to a human wrist.

  


https://www.ablogtowatch.com/wp-content/uploads/2018/03/Citizen-Cal-0100-Eco
-Drive-Movement-04.jpg

  


I’ve been reading about the new watch that contains this crystal for about a
month, but just saw some more detail today…

---

AT-CUT QUARTZ CRYSTAL OSCILLATOR

While AT-cut quartz crystals have indeed been in production and use since as
early as 1934, the technology is more common in larger applications and not
necessarily wristwatches. To address the needs of individuals seeking only
the most accurate performance in a wristwatch, Citizen sought to apply and
optimize this available technology in a way that could serve watch consumers
on a more direct and personal level. When working to reach the accuracy of
the Cal.0100, Citizen opted for an AT-cut quartz oscillator instead of a
more traditional tuning fork shape (XY cut). Perhaps most notably, AT-cut
variations allow for greater temperature tolerances, specifically in the
range of -40°C to +125°C. Additionally, this configuration allows for
reduced deviations caused by wearer orientation, which can cause significant
changes in accuracy that aren't negligible when attempting this kind of
performance. As a result, wearers will not have to worry about errors caused
by spatial orientation and positioning becomes less of a concern. The same
can be said about durability, which Citizen also improved upon in
conjunction with the AT-cut oscillator. After all, shock experienced in
day-to-day situations could easily prove detrimental even for quartz
movements. And when the goal is an annual accuracy of ±1 second, that just
isn't acceptable.

  


https://www.ablogtowatch.com/citizen-cal-0100-eco-drive-watch-movement/

---

  


Is this possible with an MXCO running across this wide temp range? How are
they compensating for aging at this level of precision?

  


Thanks!

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Re: [time-nuts] Weird Stuff Warehouse shutting down

[Richard (Rick) Karlquist]

On 4/7/2018 10:54 AM, Gary E. Miller wrote:


Sad news.  Weird Stuff, Haltek, and Halted were integral parts of
the Silicon Valley ecosystem.


Are you saying Halted is gone?

Last I heard, Halted was for sale because the owners are
retiring.  It could well be the next domino to fall.
They moved a few years ago, and their old bldg has been
torn down, along with the street and the entire neighborhood.
A hundred or so acres scraped.

Rick N6RK
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Re: [time-nuts] Microsemi up for sale?

[Richard (Rick) Karlquist]

When I was working on fiber optic communication test,
I remember hearing about lasers that were "tuned" with
variable Peltier coolers.  Power consumption is critical in
a cesium standard that can run on batteries.  Maybe
the power consumption of the coolers is a deal breaker.

Rick

On 3/3/2018 6:18 PM, Hal Murray wrote:

Thanks.


rich...@karlquist.com said:

2.  Magnetic state selection, as used in the 5071A, would be replaced by
optical pumping.  Len Cutler was heartbroken that HP/Agilent management
wouldn't fund this effort.



It turns out that, even now in 2018, optical pumping is not ready for prime
time in a working standard because the lasers drift over time.


Is there something fundamental in there, or is the lack of products because
nobody has made the big investment required to figure out how to do it.

What is the bandwidth of the laser?  What happens if it drifts slightly?  Can
it be servoed?  ...




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Re: [time-nuts] LT1016 as a pulse shaper...

[Richard (Rick) Karlquist]

In the 5071A, we squared up an 80 MHz clock with a 74AC04 gate
capacitively coupled with resistive bias to set it at half
the supply current; not a resistor from input to output as
you often see.

Ever since the LT1016 came out, it has been the "easy" way
to square up a sine wave.  Easy != high performance.  The
temperature drift of the delay time in the LT1016 is
very substantial.

Regarding ultra high speed comparators:  No you don't want
the fastest one you can get.  That just maximizes the jitter.
You merely want "good enough" speed.  In any event, comparators
are never a low jitter way to square up a sine wave.

Rick N6RK

On 3/3/2018 10:34 AM, Mark Sims wrote:

Look at the LPRO manual.  They have a couple of circuits that uses a single CMOS gate 
with a capacitively coupled input.   Wenzel has some very similar circuits on their web 
site (search for "Wenzel squarer").

My HP-531xx counter calibrator board uses on as the input squarer (with a 
74HCT86 as the gate).  I measured the ADEVs of the output and they were 
indistinguishable from the input.
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Re: [time-nuts] Output impedance of MC74VHC logic?

[Richard (Rick) Karlquist]

It's not just that you need to have small signal Thevenin source
impedance << 50 ohms, you also need to be able to
deliver sufficient current, at the rated logic
voltage swing of the device.  If the device is swinging
rail to rail, and you drive a 50 ohm load through a
50 ohm resistor in series with a blocking capacitor,
the device has to be able to source and sink 16.5 mA.
You can also estimate the Thevenin impedance from the
data sheet numbers giving voltage swing vs current.
You probably won't get rail to rail swing at 16.5 mA
with your gate, or any other CMOS gate.  In all
likelihood, you will want to do something like
use a 74__04 Hex Inverter with all 6 gates wired in
parallel.

If you follow your driver with a bandpass filter, it
should be a design that presents a high impedance to
the driver at harmonic frequencies so the gate can
be happy making a square wave of voltage.  This gives
an advantage of 4/pi in drive capability.

Rick N6RK

On 3/3/2018 4:09 AM, David C. Partridge wrote:

Using this to buffer output from an LPRO (74VHC1G14 (Schmitt trigger 3.3V
TTL compatible)), or an Efratom 105243-003 10MHz OCXO with CMS output
(74VHC1GU04 CMOS levels) in a 10MHz mod for the KS-24019 RFTGm-II.

To match well to 50R bandpass I want to add a series resistor to the output
but don't know the output impedance of these single logic gates.

Does anyone know what this is please?

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Re: [time-nuts] Microsemi up for sale?

[Richard (Rick) Karlquist]

I asked the CBT manager at Microsemi about this
rumor and he disavowed any knowledge of this.
He told me they were making 8 a week (not clear
if this is just 5071A's, or includes replacement
CBT's).  I don't remember the production ever
being anywhere near this level.  The reason
for the relatively brisk sales is that the risk
of GPS spoofing means that various military and
3 letter agencies need to own dedicated 5071's.
With a large installed base of 5071's, there will
be a guaranteed market for replacement tubes.
The US government considers the 5071A to be of
great strategic importance and would be certain
to "encourage" its continued production in case
of any business reorganization.

When we designed the 5071A twenty five years ago,
it seemed that there were two safe bets:

1.  Working Cs standards (outside the lab) would
obsoleted by what HP called "smart clocks" running
off of GPS.

2.  Magnetic state selection, as used in the 5071A,
would be replaced by optical pumping.  Len Cutler
was heartbroken that HP/Agilent management wouldn't
fund this effort.

It turns out that, even now in 2018, optical pumping
is not ready for prime time in a working standard
because the lasers drift over time.  The 5071A's
claim to fame is that you turn it on and it just
works ... until it runs out of cesium.  That is
another reason the 5071A isn't going away any time soon.

Rick Karlquist N6RK
Member: 5071A design team

On 3/3/2018 1:22 AM, Anders Wallin wrote:

Just a change to the last part of the name then ;)
https://www.ft.com/content/10192a2a-1d99-11e8-956a-43db76e69936
"semi" -> "chip"


On Sat, Jan 27, 2018 at 1:27 AM, Clint Jay <cjaysh...@gmail.com> wrote:


Perhaps of interest to the list

https://www.theregister.co.uk/2018/01/25/microsemi/

--
Clint.

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*
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Re: [time-nuts] question about HP 5601a harmonic generator

[Richard (Rick) Karlquist]

I extensively studied the 5061 harmonic generator when I
was designing the harmonic generator in the 5071A.
We are now going on 30 years since that work.  The diode
had some HP part number.  Even if you knew this part
number, you would need to have the Part Information Report
microfiche that gave the vendor part number.  The
chances of this diode still being available are very slim.
So you are not going to get an exact replacement, except
by cannibalizing another 5061 harmonic generator assembly,
assuming it doesn't also have a bad diode.  As far as
replacing it with a different diode, that too would be
questionable.  SRD's have magic unspecified parameters
when it comes to what they do in a circuit.  The 5061
generator in particular has extremely high efficiency
due to its unique design.  It was designed by a Korean
professor named Soon Choi (IIRC) who spent a summer
at HP.  He left no known documentation as to how the
design works, or how to specify the SRD.

After a long period of study, I concluded that I was
never going to match the efficiency in any simple
circuit.  The diode mounted directly in the waveguide
is the magic.  Fortunately, by that time, we could use
a phase locked DRO and get around this problem.  Len
Cutler in his usual style criticized me for "taking the
easy way out", but he eventually came around to my
way of thinking.

I will give you a little hope.  The harmonic generator
consists of a bunch of silver plated parts that are
supposed to fit together and achieve electrical conductivity.
After many years, the silver and tarnish and upset the
electrical conductivity.  You might try disassembling
the diode mount and cleaning up everything.  After
you reassemble it, you might have good news.

I will say that I have never heard of an SRD failing,
and as you say, it looks good at DC.  What possible
failure mechanism could selectively make the diode
stop generating harmonics but other wise be OK at DC?
Somehow let the pixie dust escape without letting the
smoke escape.  Seems unlikely.

Also check the drive circuitry.  SRD's need tricky components
to make them "step" correctly.  Again, poor grounding due
to corrosion could spoil the harmonic generation.

Rick Karlquist N6RK
Member of the 5071A design team

On 12/24/2017 3:54 AM, Kejia Lee wrote:

Dear All,

Happy Christmas!

May I know if anyone knows the part number or the specification of the step
recovery diode in the harmonic
generator for the old HP 5601A cesium frequency standard?

I recently received this toy. The cesium tube seems to be OK, and I had
located the problem being
no 9GHz from the waveguide. I checked the diode, the DC properties seems to
be OK, but just
can not generate frequency comb any more. I really hope I can repair it as
a personal new-year gift.

I will be really appreciated, if you had any suggestions.

Best regards,

K.
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Re: [time-nuts] Recently acquired 53132A

[Richard (Rick) Karlquist]

I worked in the HP Santa Clara Division frequency counter
section at the time of the development of the 53132A series, which had 
the internal code name of "Major League Baseball".  IIRC, the external

reference circuit in it was designed by a couple of
engineers who had no background in time nuttery and
did a mediocre job.  Someone else commented on a problem
with it not wanting to measure 10 MHz correctly.  I
never heard of that before, but it would not surprise
me, because the main measurement engine was designed
by a very excellent FPGA engineer without an extensive
background in time nuttery.  The problem mentioned might
have been too subtle.

The 53132 has many good points but is not perfect.

Rick

On 12/18/2017 11:23 AM, Pete Lancashire wrote:

Friday I acquired a 53132A

https://photos.app.goo.gl/xexnJcEmT8tEWXi73

It does not have any options.

It is from a place that sells "selected" E-waste. I was in a water damaged
box, and was from a DHL freight insurance sale. It's been in the box until
a couple weeks ago.

Anyway, until now I've not followed the conversation on the issues with
using the External Reference, which I would like to do. But don't see if
there
were any conclusions or anything that could be done other then the issues
where fixed in the "B" version.

Is there a problem and a 'fix' that I missed searching the archives ?

-pete
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Re: [time-nuts] Simple open source microcontroller solution to tune DDS needed

[Richard (Rick) Karlquist]

This looks like a very good starting point.  It's a superset
that I can just simplify.

Rick

On 12/13/2017 12:10 PM, Adrian Godwin wrote:

Maybe this one ?

http://www.qsl.net/pa3ckr/bascom%20and%20avr/ad9951/index.html

There are probably many others


On Wed, Dec 13, 2017 at 8:03 PM, Richard (Rick) Karlquist <
rich...@karlquist.com> wrote:


I need a very simple controller to tune a DDS with up/down
switches (imagine setting the time on a clock).  A DDS
chip, such as an AD9836 would go on a PC board and a couple
of pushbuttons would tell the controller to tune up or
down.

Before reinventing this wheel, I thought I would see if
anyone knows of a similar solution that can be leveraged.
What I would like is both hardware and software, where
the software could be edited to accommodate the up/down
buttons.  A last resort would be to write software from
scratch.  My software skills are extremely limited.
Cutting and pasting code might work for me.

I need to be able to embed this onto an existing PC board.
I can't use a preexisting "daughter" card, other than
to copy the design of the card.

Rick Karlquist
N6RK



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Re: [time-nuts] Simple open source microcontroller solution to tune DDS needed

[Richard (Rick) Karlquist]

I should have said AD9832.  But that was just an example
that would work.  I may choose a different one for whatever
reason.

Regarding the Arduino board:  that is what I would call
a "daughter" board, which I can't have.  Is the Arduino
board open source, so that I can just copy the schematic
of it to my own board?  Is the Arduino software also
open source?

Rick

On 12/13/2017 12:47 PM, Clint Jay wrote:

I think maybe you might have meant the AD9835 ?

Anyway, there are plenty of code examples out there, do you have a
processor in mind or are you free to use whatever is suggested?



On 13 Dec 2017 20:03, "Richard (Rick) Karlquist" <rich...@karlquist.com>
wrote:


I need a very simple controller to tune a DDS with up/down
switches (imagine setting the time on a clock).  A DDS
chip, such as an AD9836 would go on a PC board and a couple
of pushbuttons would tell the controller to tune up or
down.

Before reinventing this wheel, I thought I would see if
anyone knows of a similar solution that can be leveraged.
What I would like is both hardware and software, where
the software could be edited to accommodate the up/down
buttons.  A last resort would be to write software from
scratch.  My software skills are extremely limited.
Cutting and pasting code might work for me.

I need to be able to embed this onto an existing PC board.
I can't use a preexisting "daughter" card, other than
to copy the design of the card.

Rick Karlquist
N6RK



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[time-nuts] Simple open source microcontroller solution to tune DDS needed

[Richard (Rick) Karlquist]

I need a very simple controller to tune a DDS with up/down
switches (imagine setting the time on a clock).  A DDS
chip, such as an AD9836 would go on a PC board and a couple
of pushbuttons would tell the controller to tune up or
down.

Before reinventing this wheel, I thought I would see if
anyone knows of a similar solution that can be leveraged.
What I would like is both hardware and software, where
the software could be edited to accommodate the up/down
buttons.  A last resort would be to write software from
scratch.  My software skills are extremely limited.
Cutting and pasting code might work for me.

I need to be able to embed this onto an existing PC board.
I can't use a preexisting "daughter" card, other than
to copy the design of the card.

Rick Karlquist
N6RK



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Re: [time-nuts] Oscillators and Ovens

[Richard (Rick) Karlquist]

On 11/1/2017 3:44 PM, Dana Whitlow wrote:

Bob,

This discussion is getting really interesting.  In thinking about the
crystal Q versus
tuning range conundrum, two (presumably-overlapping) concerns come to mind:

1. The motional parameters of a high-Q crystal are such that the external
network
 needed to pull it very far would be wholly impractical.

2. Varactors themselves probably have pretty limited Q over much of their
range.

Is my thinking on the right track at all?

Dana  K8YUM




Sorry your thinking is NOT on the right track.

What determines the pullability of a crystal is the ratio of the
motional capacitance to the static capacitance, commonly denoted
as C1/C0.  The Q of the crystal has nothing to do with it.  The
only thing significant about the Q is that it limits the
how QUICKLY you can change the crystal frequency.

What determines the noise of a crystal is the intrinsic
flicker of frequency noise.  The Q has nothing to do with it.
If the Q is degraded somewhat by adding varactors to pull the
frequency, it doesn't affect the noise.  It is true that if
varactors are used, it is possible that the noise will be
degraded if the tuning voltage is not clean enough.  The
HP smart clocks were always limited by this problem because
no realizable voltage source was good enough, at least 20
years ago.

In the 5071, I modified the 10811 to increase its tuning range
by an order of magnitude.  This did not affect its noise
at all, AKAIK.  The zener diode reference in the 10811 is
actually quite good.  This modification was done to eliminate
the need to tweak the coarse tuning of the 10811 as it aged.

Having said this, with currently available technology, I recommend
using frequency synthesizers to do a "virtual pull"
on crystal oscillators, rather than trying to pull them
with varactors.

Rick N6RK
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Re: [time-nuts] Spice simulation of PSRR and phase noise

[Richard (Rick) Karlquist]

On 10/24/2017 11:10 AM, Hal Murray wrote:


aph...@comcast.net said:

   My applications were broadband. If I remember correctly,  aggressive
bandwidth limiting can cause phase shift problems due to  temperature
changes unless one is careful in the design of the filter.


Does anybody ovenize amplifiers and filters to avoid that problem?



This problem came up in the design of the 5071A.
I elected to avoid narrowband filters by using
some tricks described in my FCS paper of about
25 years ago.  I didn't find it necessary to ovenize
the output section.

By contrast, the 5061 had numerous narrow band filters
that were problematical.

Rick N6RK
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[time-nuts] HP 3048 question: how to export graphs?

[Richard (Rick) Karlquist]

I am running an HP 3048 under HTBasic and I
have a nice looking phase noise graph on the
screen.  I want to export the graph to the
world outside of RMB.  Using the "Hard Copy" or "Plot"
function keys does nothing, probably because
I don't have an HP-IB printer or plotter
connected.  (I actually have the extremely
rare HP-IB printer on hand, but I don't want a paper
copy, I want a .bmp or something like that).

I see that HTBasic has a Win-Print driver,
so I loaded that FWIW.  I don't see how to
make the RMB software connect to it.  The
HTBasic manual discusses how to print text
using this driver, but I want to print (or
plot) graphics.

The HTBasic site also shows a Microsoft
supplied HPGL filter that sounds like it
might emulate a pen plotter.  The HTBasic
manual says that you can write "PLOTTER IS
".  Maybe that will work.  I see
in the existing RMB code the program calls
line 25148 PLOTTER IS CRT and elsewhere
PLOTTER IS HPGL.  The 3048 help file says
holding down the shift key while pushing
the Plot button redirects to the HPGL plotter.
Can I simply replace "HPGL" with "
or something?

Then there are the Result (RESU) files.  Does
anyone know how to translate them into
anything readable?

As a last resort, I am using the keyboard's
"Print Screen" key to copy the screen to the
Windows 7 clipboard.  It is then available
to any Windows program.  That's clumsy but
better than nothing.

As a hardware engineer, even this simple software
stuff is above my pay grade.  Any help would
be appreciated.

When I first got the 3048, I tried PN3048.
I realize it can effortlessly export graphs.
According to the author, it does not support
various features that I need (and apparently
never will).  So I am stuck in the RMB world.

Rick N6RK
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Re: [time-nuts] 5071A Reference Oscillator ?

[Richard (Rick) Karlquist]

On 10/6/2017 9:32 PM, Artek Manuals wrote:

One of the few things I dont have a manual for

Can anyone tell me if there is an HP model number for the Reference 
Oscillator Assembly (A19) in the 5071A? Might be a  a 10544A ?


Thanks,



It was a 10811 that I modified to get more tuning range by replacing
the stock varactor with a hyperabrupt type, probably my favorite
MV209, but I can't remember for sure.

Just yesterday, I designed a phase modulator using an MV209.

Rick Karlquist N6RK
RF designer on 5071A
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Re: [time-nuts] Phase Noise Test Set For Sale

[Richard (Rick) Karlquist]

Just wanted to say hi, I didn't know you read this group.
Are you retired from Keysight?  I retired from Agilent
as a Keysight retiree in 2014 but got hired back to
Agilent (not Keysight) last year in the Mass
Spectrometer division.  Does Keysight still have the
frequency synthesis COT?

How much are you asking and are you willing to sell individual items? 
What software are you using?  Do you have any line stretchers,
phase shifters, frequency dividers, signal sources or buffer amplifiers 
etc to sell?


Rick

On 8/23/2017 5:07 PM, Eric Drucker wrote:

I am selling my HP 3048 phase noise test set as I don’t use it that much 
anymore. Complete with 5316 counter, 3561 and 3585 spectrum analyzers, and PC 
with windows phase noise software.

  


Eric Drucker (druc...@sonic.net)

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Re: [time-nuts] DAC performance

[Richard (Rick) Karlquist]

On 7/17/2017 1:41 PM, Attila Kinali wrote:

On Mon, 17 Jul 2017 12:07:29 -0700
"Richard (Rick) Karlquist" <rich...@karlquist.com> wrote:


On 7/17/2017 10:54 AM, Azelio Boriani wrote:

This implies that in a Rb or Cs there is not a voltage reference source?



Yes, that's right, there is no voltage reference with a material
effect on stability or accuracy.


How about the temperature and C-field control? Aren't those based
on keeping the output of a sensor stable compared to a voltage reference?

Attila Kinali



Good oven design is typically done with thermistor/resistor bridges 
which are ratiometric and definitely don't depend on a reference.

In the 5071A, the C field is controlled with
a Zeeman splitting check, hence no reference involved.  In
older Cs standards, the C field accuracy depended on a reference
but it didn't require a very good one to get sufficient accuracy
in the C field.  In Rb standards, the C field is so crude it
is often adjusted using a pot.

Rick N6RK
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Re: [time-nuts] DAC performance [WAS: Papers on timing for lunar laser ranging]

[Richard (Rick) Karlquist]

On 7/17/2017 10:54 AM, Azelio Boriani wrote:

This implies that in a Rb or Cs there is not a voltage reference source?



Yes, that's right, there is no voltage reference with a material
effect on stability or accuracy.

Rick N6RK
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Re: [time-nuts] DAC performance [WAS: Papers on timing for lunar laser ranging]

[Richard (Rick) Karlquist]

On 7/16/2017 1:51 PM, Bob kb8tq wrote:

Hi

One gotcha with any ADC or DAC is going to be the reference. There, you are in 
the same
“get what you pay for” dilemma. Stable and noisy, can do. Quiet and not very 
stable, can do.
Both stable and quiet, not so easy if you want it cheap.

Noise can also be the sigma delta ADC’s weak point. Even at slow rates, some of 
them need
a lot of averages to quiet down.



The reference initially used in the E1938A turned out to be too 
noisy/unstable.  It was non trivial to find an upgrade.  The

HP Smart Clocks of 20 years ago were limited in their performance
by the reference used.

Has there been much improvement in references in the intervening
20 years?

Rick N6RK
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Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Richard (Rick) Karlquist]

No one has brought up the issue of hermaphrodicity, so
I will.  Only PP's are hermaphroditic.  Why does this
matter?  It matters in the case of a battery.  A battery
is both a power source and a power sink.  In the PP
system, you can make a 3 way connection between a
power source, a power sink, and a battery, where
the battery float charges on the 12V bus it is connected
to.  Non-hermaphroditic connector schemes do not allow
a 3 way connection.  Attempting to do a work around
would require fabricating a special 3 way harness,
which would not be idiot proof.

This is the fundamental reason for using PP's.

If you never use batteries, then all the other
gendered connector schemes are fair game.

As far as connectors pulling out is concerned:
use a cable clamp to strain relieve the connection.

Rick N6RK
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[time-nuts] HP 4815 Vector Impedance Analyzer repair

[Richard (Rick) Karlquist]

I have a non-functional HP 4815, don't know if it
is the probe or the box.  A long time ago, there
was a fellow named George Standford (something like
that) who repaired these.  My old contact information
for him is no good.  Does anyone know if he is still
in business, or if there is any other place that
repairs these things?

Rick N6RK
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Re: [time-nuts] uC ADC resolution (was: Poor man's oven)

[Richard (Rick) Karlquist]

On 6/11/2017 6:09 AM, Magnus Danielson wrote:

Hi,

What papers would you recommend reading?

One of the things that we experimented on and improved was the passive 
wall to prohibit quick cooling of oven. A puff of air or the forced 
convection (fans) needed for other electronics would tie the metal 
shield very well to surrounding environment. Using a simple plastic 
wall/box as a windshield has a quite drastic effect at the rate of 
change in temperature, and allowed the oven to react better to it.
It has proven a very good strategy to reduce the systematic effect that 
eats up stability. As systematic effect, it should not be part of ADEV, 
but if you ADEV it is there loud and clear.


Cheers,
Magnus



On the E1938A, we tried externally cooling it by spraying it with
canned "freeze mist" and there was no observable fluctuation in
crystal temperature using the crystal in B mode (20 ppm/degree C).

Rick N6RK
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Re: [time-nuts] E1938 oven design

[Richard (Rick) Karlquist]

On 6/11/2017 8:59 AM, Attila Kinali wrote:


The exact insulation is relatively unimportant.
We even tried still air using a knife edge
cradle.  Didn't make much difference.




What is a knife edge cradle?


We wanted to test still air as insulation.
We couldn't just replace the insulation with
"nothing".  There had to be some kind of mechanical
support to keep the oven mass suspended inside the
outer case.  Our ME built a skeleton framework
made of plastic to support it.  In order to minimize
conduction thru the plastic, he designed in knife
edges where the plastic came into contact with the
oven mass.



One big question remains: How did you set the ratio
between face and rim heater? Was it determined at design
time and then just set the same for all units or was
it part of the production test?


During proof of concept phase in R, I peaked up the
thermal gain on each unit by trial and error.  I could
usually get a run with positive thermal gain, then
increment the ratio, and get a run with negative
thermal gain.  I could then interpolate to get the
ratio that should give "infinite" gain.  Maybe one
or two more runs after that would get me to where
the gain passed through infinity at some ambient
temperature, and was well into the millions over the
whole range.  At extremely high thermal gain, the
gain is not constant over ambient temperature.

I collected data on a number of units and then used
the average ratio as the production setting.  I
checked production units from time to time and they
typically ran well in the 100's of thousands for gain.

This compromise was workable because we individually
programmed the oven set point to the exact turnover
temperature.  This is a lot easier because it doesn't
require environmental chamber runs.  The E1983A software that
I "leaked" to the time-nuts community I believe has a
command that can be used to search for the turnover.


Rick N6RK



Attila Kinali


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Re: [time-nuts] backfill

[Richard (Rick) Karlquist]

On 6/8/2017 5:08 PM, Bob kb8tq wrote:

Hi

In this case hydrogen + oxygen (like from oxidized metal) goes to H20. You very 
much do
not want water running around inside your crystal holder… Helium is inert.

Bob



Exactly right Bob.  The 10811 guys used to go nuts
about keeping water out of their vacuum system.
There were certain temperatures known as "water
points" at which some water was released.
The retained water was in spite of the temperature
already being above 100 degrees C (boiling).
It has something to do with monolayers of
water molecules not boiling away.

Rick N6RK
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Re: [time-nuts] backfill

[Richard (Rick) Karlquist]

Bob is exactly right.  Read up on "mean free path" physics.
Just a little air will take care of conduction.
Full atmospheric pressure would drop the Q something like
a factor of 2.

In any event, conduction through the crystal mounts is
plenty adequate for the tiny thermal mass of the crystal
itself.  The mounts are embedded in the ceramic header,
which is fairly conductive.

Rick N6RK

On 6/8/2017 1:19 PM, Bob kb8tq wrote:

Hi

If you look at the thermal conductivity vs very low pressures, the conductivity
comes up pretty quickly from a hard vacuum. There is essentially no impact
on Q.

Bob


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Re: [time-nuts] E1938 oven design

[Richard (Rick) Karlquist]

Yes, that's right.  The copper oven mass
has two pieces:  a main piece and a lid.
The main piece has a wall around the outside
into which the cover fits, using an O-ring.
In the center, there is a cylindrical cavity
into which the crystal mounts.  It is like
a 10811 crystal, except the height is reduced.
In retrospect, there is no reason why the
10811 crystal shouldn't have been that size.
It is potted into the cavity, therefore, it
doesn't use the famous flat head 4-40 screw
welded to the can as in the 10811.  Thermistors
are potted into holes drilled in the cavity
wall.  The lid has screws that screw into
the cavity wall.

The main piece holds a circular PC board
containing the bridge oscillator circuit.
It has a big hole in the middle for the
crystal cavity.  The production people
immediately named it the "donut board."
And the finished oscillator is the "hockey
puck".

Summarizing, the crystal is very well thermally
connected to the copper oven mass.

There are 3 flex circuit heaters.  One for
the lid, one for the other face of the
main piece, and one that goes around the
outside.  The two face heaters are operated
together as one heater.  The ratio of heat
to the faces vs the outside rim is adjusted
for maximum thermal gain.  The rim heater is
the difference between under 1,000 gain and
over 1,000,000 gain.

We were stuck under 1,000 for a long time
using only face heaters.  I still remember the
day that I rigged up the first crude rim header
by winding a piece of magnet wire around the rim
and holding it in place with 5 min epoxy.  I
didn't know what else to try.  This seemed like
a Hail Mary play at the time, until I
measured the gain.  We instantly went to gains
above 20,000.  It seemed high at the time but
it was only the beginning.

The exact insulation is relatively unimportant.
We even tried still air using a knife edge
cradle.  Didn't make much difference.

Rick N6RK

On 6/8/2017 1:27 PM, Attila Kinali wrote:

On Wed, 7 Jun 2017 14:21:52 -0700
"Richard (Rick) Karlquist" <rich...@karlquist.com> wrote:



The crystal case is well connected to the oven mass and gets
heated by conduction.  I don't think radiation is a player.


Do I interpret the papers correctly, that the oven mass is
a closed can, with the crystal holder "molded" into it?
Then wrapped around it are the face and the rim heaters,
and outside those comes the insulation and the outer can?

Attila Kinali


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Re: [time-nuts] Poor man's oven

[Richard (Rick) Karlquist]

On 6/7/2017 1:09 PM, Attila Kinali wrote:


makes the PI loop better behaved. Also the thermal mass of the
crystal holder is quite small. Especially compared ot the 10811.


Actually, the oven mass of the E1938A is much heavier than the
10811 and is made of copper to boot.


Due to the flat puck design, I assume that the majority of the
heat going to the crystal holder is due to radiation (unless I
missed some insulation around the crystal). Radiation, albeit being
a high "resistivity" transport mechanism, has very low inherent
"capacitance". And thus the delay associated with this transport
mechanism is low.


The crystal case is well connected to the oven mass and gets
heated by conduction.  I don't think radiation is a player.


There are probably a lot more small design decisions in the E1938
that make it such a superb oven. More than I probably will ever
be able to figure out. And, I still am astonished how well it works.

Attila Kinalid


Rick N6RK
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Re: [time-nuts] MCXO and dual mode

[Richard (Rick) Karlquist]

On 6/6/2017 3:16 PM, Bob kb8tq wrote:

Hi

If you do the classic MCXO with two oscillator circuits and one resonator, the 
issue is
pretty simple. You have a load capacitance on the fundamental. You have a load 
capacitance
on the third overtone. Even if it is the exact same capacitor, the tuning 
sensitivity on
the fundamental is different than the sensitivity on the third overtone. As the 
load impedance
changes (parts do drift) the delta between the two modes will show up as an 
offset between
them. If you run through the math, it gives you a delta temperature. How much? 
How fast? Obviously
that depends. When I brought this up at the time with the authors of the paper, 
the reply was that
a recalibration of the MCXO was provided for for this reason.

Bob



I don't understand what you are talking about here.  The tempco
difference between modes is unrelated to load capacitance.  The
dual mode idea would work just as well if the oscillators
operated at series resonance.

[I attended this talk in person ~25 years ago; it got a lot of
interest].

The reason why the SC cut mode C and mode B dual mode patent
from HP fell out of favor was the problem with activity dips
in mode B.  Otherwise, it was a great idea.  It would still
be fine for an OCXO, where you just avoid activity dips.
However, the circuit design is very complicated.

Rick N6RK
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Re: [time-nuts] Poor man's oven

[Richard (Rick) Karlquist]

On Jun 6, 2017, at 7:10 PM, Chris Albertson  wrote:


There are more sophisticated control loop designs that can handle this
better, eg by using two temperature sensors, one at the crystal and
one at the heater. But designing them correctly is more difficult
than the normal PID loop.



In the E1938A oscillator, we used a PIDI^2 loop.  IOW, a PID
plus a double integrator.  This was Len Cutler's idea.
Once the constants were dialed in, this worked phenomenally
well in terms of transient response.  Even dumping in liquid
nitrogen full throttle into the environmental test chamber
barely wiggled the crystal temperature/frequency.

Rick N6RK
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Re: [time-nuts] Poor man's oven

[Richard (Rick) Karlquist]

On 6/6/2017 4:26 AM, Poul-Henning Kamp wrote:


But I cant imagine the ovens used are so perfect that they have the
same regulation performance at all temperatures.

I can choose the exterior temperature, which I should prefer ?

Disregard aging of electronics and materials, we all know that
stuff, what I'm interested in is at which exterior temperature
OCXO ovens work best ?



My experience has been that, while ovens may not be perfect,
they are inherently linear.  So the exterior temperature is
a don't care.

I extensively characterized the E1938A oven.  By adjusting
the ratio of heat to the top/bottom vs edge, I was able to
get the thermal gain into the millions.  At that point,
finally a modicum of non-linearity showed up and the thermal
gain varied with ambient temperature.  It might be 2 million
at the ambient where I adjusted it, and drop to 1.5 million
when well away from that temperature.  Or it might change
sign at some ambient.  (Yes, you can have negative thermal
gain).  You shouldn't need to worry about this for any ordinary oven.

Rick N6RK
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[time-nuts] HP 3048 NI GP-IB cards help requested

[Richard (Rick) Karlquist]

I am trying to set up an HP 3048 system and
have read the KE5FX web page on the software.
I have successfully installed both PN3048 and
the HT Basic port of RMB.  The programs basically
appear to run correctly on my Windows 7 desktop.

HOWEVER, I don't have a GP-IB card.  According to
KE5FX, both the bus card and USB dongle types work.
It looks like current NI driver supports many
legacy cards.  I am curious about whether this
means that all of these cards will be OK, or if I
have to buy the latest card/dongle?  I would like
to be able to run both programs.  The HT Basic
site says that certain bus chips are incompatible
with its software, and I should call them for suggestions.

I would appreciate hearing from anyone who can vouch
for a compatible NI card/dongle, either current production
or a legacy one.  (If someone has one they want to
sell, let me know).  Ideally I would like to use the
same card/dongle for both the PN3048 and the HTBasic
programs.  In the PN3048 program, there is
a menu pick to select NI card of type 1 or type 2.
Does anyone know anything about that?

Rick N6RK


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Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[Richard (Rick) Karlquist]

I said no *manufacturer* does it this way.  NBS is not
a manufacturer.  In a one-off money-is-no-object non-portable
standard, you can make direct multiplication work.  It
will not work well in a 5061, because of RF leakage
issues specific to the 5061 that are well documented.
Bolting on a different synthesizer does nothing to change that.

The decision not to use direct multiplication has nothing to
do with not being able to figure out how to synthesize the
correct frequency.  Certainly by the time we did the 5071A,
we were already using DDS, and it wouldn't have been any
problem to synthesize for direct multiplication if we had
wanted to do that.  You seem to be doing it the hard way
(pre DDS) involving Diophantine equations.  So it's easier
to do direct multiply than it used to be, but that doesn't
necessarily mean you should do it that way.

Rick

On 6/2/2017 10:59 AM, Donald E. Pauly wrote:

https://www.febo.com/pipermail/time-nuts/2017-May/105566.html

A guy by the name of David W. Allan used direct multiplication to
build NBS-4 and NBS-5, see http://tf.nist.gov/general/pdf/65.pdf .  He
didn't see anything wrong with it.  He used a commercial frequency
standard modified from 5 mc to 5.006880 mc.  That in turn was
multiplied by 1836.  This was a multiplier chain of 2·2·3·3·3·17.
When multiplied to 9192 mc, this is 90 cycles low so the standard
would be forced high by 0.05 cps..  They measured the locked frequency
standard to determine the actual frequency of the cesium line.  I
propose NO multiplier chain.

What are the supposed problems in using a direct submultiple of the
cesium resonance?  It seems to me that all other techniques result in
more phase noise there.  I found the relationship 91.92631770
mc·(137,075/126,008)=99,999,999.98992 cps=100,000.000--0.01008 cps.
It is low by 0.1 ppb and therefore cannot be adjusted by C field
current.  The C field can only lower the frequency.  There is another
relationship that gives a higher frequency of a fraction of a part per
billion which is easily adjustable.  Perhaps HP was unaware that such
a frequency exists.

πθ°μΩω±√·Γλ
WB0KV


-- Forwarded message --
From: Richard (Rick) Karlquist <rich...@karlquist.com>
Date: Thu, Jun 1, 2017 at 10:01 PM
Subject: Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies
To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>, "Donald E. Pauly" <trojancow...@gmail.com>,
"rwa...@aol.com" <rwa...@aol.com>


Direct multiplication to 9192 MHz isn't used
by any manufacturer of any atomic clock that I
know of, due to its well known disadvantages.
I can state for a fact that it was summarily
rejected by the designers of the 5060/5061
(Cutler, et al).  In the 5071, I (being the
RF designer) also summarily rejected it.
The architecture that is instead used is indeed
complex and expensive as you say.  It is
also ACCURATE.

Rick


On 6/1/2017 7:04 PM, Donald E. Pauly wrote:


https://www.febo.com/pipermail/time-nuts/2017-May/105566.html

The lock system on the HP5071 is complex and expensive.  My plan to
improve the HP5061B is to to use a pair of third overtone crystals
running at 91.9 mc and 100 mc.  I have come up with the magic numbers
to lock them together.  This eliminates all multipliers with the
exception of the A4 board. The 12.61 mc synthesizer input presently
wastes half the microwave power produced by the 90 mc input in the
unused lower sideband. Therefore only half the 91.9 mc drive is
required.

Eight bit ECL dividers in one package are available to perform the
necessary lock.  When multiplied by 100 to the cesium resonance line,
the 91.9 mc frequency is a few cycles high so that C field currents
are reasonable. With crystal cuts for zero temperature coefficient at
25°C, it is possible to get along without an oven.  Room temperature
performance at 25°C±5°C is ±15·10^-9.  Oscillator warm up time would
be measured in seconds.

Square wave modulation of variable frequency and amplitude shows
promise for reducing the noise effects of the beam tube.  You can
smoothly change the lock time constant, deviation and frequency.  This
would avoid the big disturbance of the HP5061B when you switch from
OPR to LTC. (OPR=operate with 1 second time constant, LTC=operate with
100 second time constant)

πθ°μΩω±√·Γλ
WB0KV
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Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[Richard (Rick) Karlquist]

Direct multiplication to 9192 MHz isn't used
by any manufacturer of any atomic clock that I
know of, due to its well known disadvantages.
I can state for a fact that it was summarily
rejected by the designers of the 5060/5061
(Cutler, et al).  In the 5071, I (being the
RF designer) also summarily rejected it.
The architecture that is instead used is indeed
complex and expensive as you say.  It is
also ACCURATE.

Rick

On 6/1/2017 7:04 PM, Donald E. Pauly wrote:

https://www.febo.com/pipermail/time-nuts/2017-May/105566.html

The lock system on the HP5071 is complex and expensive.  My plan to
improve the HP5061B is to to use a pair of third overtone crystals
running at 91.9 mc and 100 mc.  I have come up with the magic numbers
to lock them together.  This eliminates all multipliers with the
exception of the A4 board. The 12.61 mc synthesizer input presently
wastes half the microwave power produced by the 90 mc input in the
unused lower sideband. Therefore only half the 91.9 mc drive is
required.

Eight bit ECL dividers in one package are available to perform the
necessary lock.  When multiplied by 100 to the cesium resonance line,
the 91.9 mc frequency is a few cycles high so that C field currents
are reasonable. With crystal cuts for zero temperature coefficient at
25°C, it is possible to get along without an oven.  Room temperature
performance at 25°C±5°C is ±15·10^-9.  Oscillator warm up time would
be measured in seconds.

Square wave modulation of variable frequency and amplitude shows
promise for reducing the noise effects of the beam tube.  You can
smoothly change the lock time constant, deviation and frequency.  This
would avoid the big disturbance of the HP5061B when you switch from
OPR to LTC. (OPR=operate with 1 second time constant, LTC=operate with
100 second time constant)

πθ°μΩω±√·Γλ
WB0KV
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Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Richard (Rick) Karlquist]

On 5/27/2017 2:08 PM, Donald E. Pauly wrote:


I am investigating the total redesign of the HP5061B lock system for
vastly improved performance.  It looks like the performance of the
HP5071A can be beaten by 10 to 1 for averaging times on the order of a
few seconds.

πθ°μΩω±√·Γλ
WB0KV



That's an interesting claim, but it could be valid.
The 5071A flywheel is a 10811 selected for performance
and modified to have additional electronic tuning
range (I was involved in that) but otherwise it is
plain vanilla 10811.  At a few seconds averaging time,
this oscillator is basically open loop.  It might be
possible to improve a 5071A by simply finding a 10811
with exceptional short term stability.  The tail of
the distribution curve went down at least an order of
magnitude, according to Jack Kusters at HP.

In any event, you could use an unmodified 5071A or maybe
a 5061B high performance option and discipline some
really good XO.  Certainly, the 10811 isn't the world's best
XO.  You'll need to prevent your XO from getting bothered
by microphonics, stray magnetic fields, 2G turnover, temperature
fluctuations, and humidity if not hermetic , etc.  The 5071A is
impervious to all that as it is.

Is that what you had in mind?

I remember before I worked for HP visiting JPL's Goldstone
tracking station.  They had a 5061A that disciplined a
hydrogen maser for VLBI.  They said a plain 5061A was useless for their
work.  OTOH, a hydrogen maser without drift correction was
also useless for their work.  They had a huge room with 100's
of racks of equipment, but the 5061A and H maser had their
own dedicated room.

Rick Karlquist N6RK
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Re: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies

[Richard (Rick) Karlquist]

Wow Tom, great posting.  All I can add is that in the 5061 there is
a tradeoff that the higher the C field is, the more sensitive it is
to errors.  That tempered the decision in the past.  With the 5071,
we have Zeeman line sampling so that the C field can be measured
by physics, not by precision magnetics.  IIRC, this allowed Len
Cutler to use a larger C field.  Separating the lines farther is
more important in the 5071A because the other error sources are
reduced.

Rick Karlquist

On 5/25/2017 9:23 PM, Tom Van Baak wrote:

Donald,

You're familiar with the 9,192,631,770 Hz definition of the SI second; but that's only 
for an "unperturbed" atom. The bad news is that in order to make the cesium 
beam operate at the central resonance peak one actually has to violate the SI definition 
and perturb it -- by applying a magnetic field (the so-called C-field), as well as other 
factors. This cannot be avoided. The good news is that the shift can be calculated.

In other words, because a magnetic field must be applied the actual cesium 
resonance frequency is not 9192.631770 MHz. The synthesizer locks to the peak, 
but the peak is at a slightly higher frequency than the nominal book value. 
This detailed note from hp may help:

http://leapsecond.com/museum/hp5062c/theory.htm

Different model beam tubes use different field strength / Zeeman frequency. 
Search the archives for lots of good postings about all these magic frequencies 
-- google: site:febo.com zeeman

If you want to see what the resonance peaks (all 7 of them) actually look after 
the C-field is applied see:

http://leapsecond.com/pages/cspeak/
and (poster size):
http://leapsecond.com/pages/cfield/

See also John's version:

http://www.ke5fx.com/cs.htm

One final comment -- the perturbed vs. unperturbed issue is far more complex 
than a single correction. To get an idea of the math and physics complexity of 
a laboratory Cs beam standard read some of these:

http://tf.nist.gov/general/pdf/1497.pdf
http://tf.nist.gov/general/pdf/65.pdf
http://tf.boulder.nist.gov/general/pdf/101.pdf

/tvb

- Original Message -
From: "Donald E. Pauly" <trojancow...@gmail.com>
To: "time-nuts" <time-nuts@febo.com>; "Donald E. Pauly" <trojancow...@gmail.com>
Sent: Thursday, May 25, 2017 7:55 PM
Subject: [time-nuts] HP5061B Versus HP5071 Cesium Line Frequencies


https://www.febo.com/pipermail/time-nuts/2017-May/105298.html

The synthesizer in the HP5061B generates a frequency of about
9,192,631,772.5 cps when the 5 mc oscillator is exactly on frequency.
First the 5 mc oscillator is multiplied by 18 to 90 mc on the A1
board.  That in turn is multiplied by 102 in the A4 board to give
9,180 mc.

The 5 mc is also divided by 4079 to produce 1,225.790635 cps.  That in
turn is multiplied by 10,305 to produce 12,631,772.5 cps.  This is
added to the 9180 mc in the A4 mixer to produce the final frequency of
9,192,631,772.5 cps approximately.  This is higher than the defined
frequency of 9,192,631,770 cps by about 2.5 cps or 271·10^-12.  If I
figured it right, the C field adjustment only has a range of
40·10^-12.  This seems to be insufficient to put the standard on
frequency.

Can anyone explain these mysteries?  Does anyone know why this
frequency was chosen?  Does anyone know the choice for the frequency
of the HP5071 cesium?

πθ°μΩω±√·Γλ
WB0KV
4,079=prime
10,305=5x9x229
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Re: [time-nuts] HP10811 Oscillator Thermal Fuse

[Richard (Rick) Karlquist]

On 5/11/2017 4:25 AM, Bob kb8tq wrote:


Ultimately it all came to no good. The energy conservation rules simply took 
over. Shutting
down everything during off hours became the way a lot of outfits did things. 
Don’t turn off all


A couple of comments on this, probably no surprise to many
time nuts.  All or most HP instruments with 10811's keep the
oven energized even if the instrument is turned "off".
Many classic HP instruments used power transformers for
power supplies.  The secondaries were regulated by a
combination of switches and linear regulators.  The
power module was mounted on the rear panel, along
with the transformer, to help get rid of the heat without
heating up the box too much.  The dilemma was that you
had to choose between four bad alternatives:

1.  Put the power switch on the rear panel.  This is
inconvenient for the user, especially if the unit is
racked.

2.  Put the power switch on the front panel.  This
entails running wiring with all the safety approvals
up to the front panel and back to the rear panel.
I don't know of this ever being done at HP.

3.  Have a button on the front panel that actuates
a long plastic shaft the goes to the real switch at
the back.  Works, but quite a hassle.

4.  What was usually done:  leave the power transformer
primary connected all the time and switch the secondaries.

The HP transformer shop would often scrimp on the amount
of iron in the transformer, which would increase the
core loss.  Their idea of good engineering practice was
to allow the loss to heat the transformer up 10's of
degrees.  Note that core loss is independent of how
much power you are drawing from the secondaries, if any.

So in the overall scheme of things, the 10811 is small
potatoes.  Once it is warmed up, it doesn't draw much
power.

Rick N6RK
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Re: [time-nuts] Fwd: HP10811 Oscillator Thermal Fuse

[Richard (Rick) Karlquist]

The view from inside HP when I worked with the people
who designed and built the 10811 some 35-40 years ago
was that:

1.  10811 ovens rarely fail.

2.  When they do fail, it is rarely because the oven
runs away.  I know I have never encountered a runaway.
No one at HP had a "trophy" on their desk of a runaway
10811.  People tend to collect stuff like that.  One
engineer did have a 10811 with a 45 caliber bullet
fired through it (long story).

3.  From a business perspective, a failure is a failure
and so there is no business reason to have a fuse.

4.  Because the fuse could not be soldered in, it had
to be socketed, and the socket failures exceeded any
oven runaways by a good margin.  Therefore, it made
the "failure rate" worse.  That is all that matters to
the bean counters.

5.  The one and only reason it was in there at all
was the concern about toxic gases being released from
the foam.  Even without a runaway, foams tend to have
a "slow burn" and outgas "stuff" all the time.  Various
foams were evaluated to balance that issue with thermal
resistance and with the big issue with foam which is
mechanical fatigue.  This is similar to the wear out
of foam mattresses.

What should have been done with the thermal fuse would
have been to put crimp lugs on the leads and attach
the crimp lugs with screws.  However, there was no space
for all that stuff.

Rick N6RK


On 5/10/2017 4:43 PM, Dan Rae wrote:

As I reported the last time this subject came up, or maybe the time
before, the only time I had an open thermal fuse was in a 10811 that had
an open thermistor.  I was able to replace that and get the OCXO
working, but if the fuse had been replaced with a wire link I'm sure the
entire oven would have been toast.

There have been two types of fuse fitted, all I those have are the type
that can be fitted with the plug in axial panasonic type, less than a
dollar from Digikey.  The older ovens had a different type but I imagine
it's similarly easy to replace.

All my 10811s have the higher temperature Panasonic fuse fitted and I
sleep well at night...

Dan
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Re: [time-nuts] Counter Internal Oscillator Importance with External Reference?

[Richard (Rick) Karlquist]

On 5/9/2017 12:05 AM, Poul-Henning Kamp wrote:


I'm sure that modern counters like 53230 are better at this than


The 53230 oven oscillator option in an inferior oscillator to
the 10811, by an order of magnitude.  So in this case,
modern != better.

Rick
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Re: [time-nuts] HP E1938A question

[Richard (Rick) Karlquist]

I know that it will run on Windows 2000.  It was originally
written on Windows NT4.

Rick

On 4/24/2017 11:06 PM, gandal...@aol.com wrote:

Thanks Rick, I understand better now.

The turn over label is still on the crystal but not the matching label
on the PCB.

So far I've not been able to get the software to run but will try
with some older versions of Windows and see how it goes with those.

Nigel GM8PZR

In a message dated 24/04/2017 17:28:56 GMT Summer Time,
rich...@karlquist.com writes:

The main issue is that the oven will no longer be at the
crystal turnover temperature.  If you are using it in
a benign environment, you might not need the extreme
thermal performance enabled by being dead nuts on the
turnover.  You still have an oven with thermal gain
in the 100's of thousands.

The test software had the ability to sweep the oven temperature
and allow you to find the turn over.  There was some way to
then set the oven to this temperature.  I don't know if anyone
currently knows how to make the software do this anymore.
I knew at one time, but have long forgotten.

Rick N6RK

On 4/24/2017 5:41 AM, GandalfG8--- via time-nuts wrote:
> I've just received an Ebay purchased E1938A, haven't tested it yet
although
>  I do have a 14 day return option, but unlike previous purchases
of these
> the serial number label is missing from the rear of the PCB so I
have no
> obvious  way of knowing if the crystal is matched to the PCB.
>
> Does anybody know if there's any embedded information that can be
accessed
> that indicates the serial number of the board, or is there any
other way I
> can  check if the crystal and PCB are matched?
>
> If not, what issues could I expect from an unmatched crystal and  PCB?
>
> Nigel GM8PZR
>
>
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>


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Re: [time-nuts] HP E1938A question

[Richard (Rick) Karlquist]

The main issue is that the oven will no longer be at the
crystal turnover temperature.  If you are using it in
a benign environment, you might not need the extreme
thermal performance enabled by being dead nuts on the
turnover.  You still have an oven with thermal gain
in the 100's of thousands.

The test software had the ability to sweep the oven temperature
and allow you to find the turn over.  There was some way to
then set the oven to this temperature.  I don't know if anyone
currently knows how to make the software do this anymore.
I knew at one time, but have long forgotten.

Rick N6RK

On 4/24/2017 5:41 AM, GandalfG8--- via time-nuts wrote:

I've just received an Ebay purchased E1938A, haven't tested it yet although
 I do have a 14 day return option, but unlike previous purchases of these
the serial number label is missing from the rear of the PCB so I have no
obvious  way of knowing if the crystal is matched to the PCB.

Does anybody know if there's any embedded information that can be accessed
that indicates the serial number of the board, or is there any other way I
can  check if the crystal and PCB are matched?

If not, what issues could I expect from an unmatched crystal and  PCB?

Nigel GM8PZR


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Re: [time-nuts] HP E1938

[Richard (Rick) Karlquist]

It's been 20 years, but I will try to recap what I remember
about this connector.  I believe there were 3 customers,
and one of them required the DB connector with coax inserts
for reasons of backward compatibility.  I think this
vendor was Motorola.  We did not actually use the coax
inserts, but left them blank and ran the RF, etc on
ordinary pins.  I believe you can make an ordinary male
DB-25 mate with these insert versions by clipping off some
of the pins that would be blocked by the female insert
version.  I vaguely remember that the other 2 vendors
used gender changers or something.  There might have
an issue with the mating plane location being different
for different customers.

I am sure that time-nuts, being talented at repurposing,
will be able to think about this problem and come up with
a simple solution to interfacing with these boards.
No need to buy insert type connectors.  I never had
any trouble making cables that connected to these units
using plain vanilla DB25's.

Rick N6RK

On 4/15/2017 10:42 AM, Larry McDavid wrote:

Ok, so a standard DB 25-pin socket-contact connector will mate with the
on-board connector with the center hole and missing pins. That's good!

I now notice a comment on your webpages about this device in which you
mention a schematic. Do you have a schematic of this board? If so, can
you point to it or send me a copy.

I was unaware of the complete packaged unit on eBay; thanks for that.

Another poster mentioned the wiring of the connector on the full
instrument version power connector; is that pin-out and spec available?

Larry


On 4/15/2017 5:05 AM, Tom Van Baak wrote:

I purchased one of these HP E1938 OCXO recently on eBay but have not yet
received it.

Is that special D-Submin connector a receptacle-shell, pin contact
version? Will a standard plug-shell, socket contact 25-pin D-Submin
fit it?


Hi,

I'll cc the group here since we may get some useful comments.

I'm not exactly sure what you mean. The E1938A oscillators that I've
seen and tested look like this:

http://www.leapsecond.com/museum/e1938a/

And those can be interfaced with a simple D-sub DB25 connector on the
PCB. For connections, see that page, or any number of postings about
the E1938 in the time-nuts archives.

Note that on eBay there are at least three variations of E1938A
oscillator. The item#'s below are just random search picks (I have no
affiliation with any buyers or sellers) and I also know not all
surplus refurbished surplus recycled surplus stuff works. But we do
this because when they did work, they are sometimes totally amazing.

1) There's the bare "puck" alone, as in
http://www.ebay.com/itm/290829077542 -- and I have no idea where one
would start with that item since all the support circuitry on the PCB
would have to be re-created by hand.

2) There's the integrated PCB assembly, as in
http://www.ebay.com/itm/181043193416 -- which is more like what I tested.

3) There's the full instrument version, as in
http://www.ebay.com/itm/171293069062 -- which is most likely to work,
or be less hacked up, or dented, or salvaged, or rusted. It even has
all the connectors and power supplies, and GPS, etc.

If any other time nuts have experience with each of these methods to
obtain a E1938 oscillator, please let us know.




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Re: [time-nuts] OCXO Soft-Start

[Richard (Rick) Karlquist]

10.9 MHz is likely the B-mode of the SC cut.
(It's a different mode, not a different overtone).
This mode has a tempco of 20 ppm and is used
to do thermometry.

IMHO, there is NO excuse for the oscillator
designer to design an oscillator that doesn't
oscillate unconditionally in the right mode.
NONE!  What was the actual manufacturer of
the OCXO? (AFAIK, Trimble doesn't make their
own).

My old boss at Zeta Labs (a really great boss)
used to walk up to people who were testing
their latest circuit and momentarily turn
down the current limit on each of the power
supplies to see if the circuit recovered
correctly.  It often didn't, and then it
was back to the drawing board...

Rick

On 4/12/2017 2:38 PM, Scott Stobbe wrote:

Hello,

I wanted to see if I could soft-start a used OCXO (Trimble 34310) during
warm-up. By default with an appropriately rated 12 VDC supply, the OCXO
starts the heater at about 8 W, and eventually settles down to 2 W for
20-25 degC ambient temperature. Figure Attached.

The good news is it does startup with either a current limited or power
limited supply. Albeit, for the constant current case the start-up time is
dramatically longer. Figures Attached.

The bad news, but interesting tangent is that when this particular OCXO is
soft-started, it doesn't oscillate at 10 MHz! It starts up on a spurious
overtone at 10.9 MHz. There isn't even a hint of 10 MHz in the output
spectrum just the 10.9 MHz tone (and some noise from the banana clip-leads
loop-antenna). So this is a bit of a pain for soft-starting because,
although the oven eventually comes into regulation, the oscillator is
running on the wrong frequency.

I'm not sure what the tempCo of the 10.9 MHz crystal mode is, but its a
pretty great temperature probe of the crystal (literally). You can see the
sinusoidal frequency disturbance of this tone has the same periodicity as
that of the heater current (~50 s). So I don't know if the heater is
oscillating at the uK level or mK level, will need to find out the tempCo
of this crystal mode. Neat to see the oven dynamics.

Hopefully once the oven is settled at temp, I can load switch the OCXO for
10 or 100 ms and get it to startup on the correct 10 MHz mode. With a 10+ W
rated supply it starts up on 10 MHz every time.



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

[Richard (Rick) Karlquist]

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

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

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

Rick N6RK

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

Hi


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

Bob


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

Some incandescent lamps can emit RF.

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

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


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




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

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

[Richard (Rick) Karlquist]

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

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

Rick N6RK

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

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


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Re: [time-nuts] a link to a explanation of Rb vs Cs?

[Richard (Rick) Karlquist]

The "magic" of Rb in a gas cell standard is that you
can make an optical filter cell out of radioactive
Rb87 isotope that allows you to selectively optically pump
to the quantum level you need.  It is just "luck"
that the absorption line falls where you need it.
And the RF pumping is at a doable 6.8 GHz.

I think the CSAC uses lasers so all of this doesn't
apply.

Cesium of course is part of the definition of the second,
so it's good to use for that reason.

It is a different discussion as to why Cs was chosen
to define the second, but the line being at 9.2 GHz might have had 
something to do with it.  That's a doable frequency in terms

of technology 60 years ago.

Rick N6RK

On 4/11/2017 1:54 PM, jimlux wrote:

On 4/11/17 12:34 PM, Attila Kinali wrote:

Hoi Jim,

On Tue, 11 Apr 2017 07:30:38 -0700
jimlux  wrote:


I'm looking for a link to point to an explanation (at a basic level) of
the difference between Rb and Cs references, and what the tradeoffs are.
I googled a bit, but all I got were some explanations of the differences
in things like vapor pressure, etc.


What exactly are you looking for? A comparison of Rb vapor cell
standards vs Cs vapor cell standards? Or a general comparison
why different kind of standards are built with Rb and Cs?

For the former, there is a paper that has some of the details
why Cs was choosen over Rb for the CSAC in one of the papers.
(Which I currently cannot find...)

For the latter, there is no easy answer and a lot come from
technicalities (difference in handling) and what people were
able to build. There are some fundamental differences in which
elements get you what kind of stability for different kinds of
atomic clocks, but I have seen very little on that and it's quite
spread over various papers and books.


precisely why I asked..

The wikipedia article isn't bad in terms of covering the gas cell vs
beam in words, but I was hoping for something with pictures..

Encyclopedia Brittanica, perhaps.. except that they only talk about
caesium beam






Attila Kinali



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

[Richard (Rick) Karlquist]

On 4/11/2017 12:31 AM, Andre wrote:


Has anyone else either built an atomic clock around a bare Rb lamp module 
"core" or attempted



Not a DIY project, but I was the RF designer on the HP 10816 rubidium
standard, which never made it to product introduction (a half dozen
working pilot run units were built in 1982).  I would say this task is
probably beyond the scope of a DIY project, at least for most
time-nuts.  The Rb lamp drive circuit (particularly getting the
lamp to light up) is very challenging.  The step recovery diode
multiplier is very challenging.  The photodetector and loop
integrator is non trivial.  The synthesizer is the one thing that
is easy in 2017.  The oven is also no simple thing to get
low tempco.  Unlike a crystal, you have a lot of heat being
generated by the lamp, etc. The lamp needs to be at a different
temperature than the other cells.  You have to keep the tip
off at the lowest temperature to keep the Rb in place and not
"flood" the cell and block the light.  Etc., etc.

This is in the category of projects where if you were qualified
to do it, your time is far too valuable to do it for the amount
of money you would save.

Rick N6RK
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Re: [time-nuts] The ultraAtomic clock for home

[Richard (Rick) Karlquist]

In the office where I work, they have 5 clocks on the wall
showing local time here at HQ and at 4 other company sites.  It
is embarrassing that the clocks are always a few minutes
off from each other.  I can see where these would make sense.

Rick N6RK



On 4/5/2017 4:30 AM, Bob kb8tq wrote:

HI

UTC I understand. I’ve used that feature on “atomic” clocks in the past.
I’m still a bit unclear on how many people will set up a wall of clocks running
on a dozen or so time zones. Obviously the people making clocks are
very much in favor of doing that :)

Bob


On Apr 4, 2017, at 7:56 PM, Richard (Rick) Karlquist <rich...@karlquist.com> 
wrote:



On 4/4/2017 3:19 PM, Bob kb8tq wrote:

Hi

Based on their web site, the model you saw is the one and only version that
does the new modulation. One very useful feature is the ability to set it to
any time zone world wide. I guess I missed the note on the WWVB coverage
area expanding to cover the entire planet …..:)

Bob



This feature is mainly so you can set the time zone for GMT/UTC.
Hopefully, there is a way to turn off daylight savings time as well.
Many previous atomic clocks covered only the time zones near Boulder
and could not display UTC.

Rick N6RK
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Re: [time-nuts] The ultraAtomic clock for home

[Richard (Rick) Karlquist]

Why? oh why? is this only available as an analog clock??
I am wondering if Lacrosse only has the rights to an analog
version and that a higher priced digital version will
show up in some "professional" line from another vendor.
This is at least a plausible theory because this is
a well known business model:  "incremental" revenue
that doesn't "cannibalize" the cash cow.  At least
this is/was popular with HP/Agilent/Keysight management
where I work(ed).

Rick N6RK


On 4/4/2017 8:00 PM, paul swed wrote:

Really can't say that its c-max or not. Since if you try to download
anything from the sight the links are dead. But I do believe its the true
wwvb bpsk decoder. If it is the cme 8000 that chip works impressively well
even in New England.
But this is the first time I have stumbled across anything that used it if
I am guessing correctly. Heck I seem to remember it was supposed to be out
some 2-3 years ago around Christmas.
Regards
Paul
WB8TSL

On Tue, Apr 4, 2017 at 9:04 PM, Tim Shoppa  wrote:


I have been happy with the Casio Waveceptor watches. They can display UTC.

They seem to reliably set themselves between midnight and 3AM each morning
when I'm wearing them here in Maryland, more reliably than the (non-PSK)
WWVB wall clocks.

The Casio WV58A-1AVCR is a plastic LCD watch for $28 that lasts a couple
years. The face scuffs easily and the band only lasts a little more than a
year before needing replacement.

I upgraded to the Metal-body-metal-band Casio WVA-M640D-1ACR almost a year
ago and am very happy. Analog display for local time, and the LCD display
can show UTC. About $90.

Tim N3QE
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Re: [time-nuts] The ultraAtomic clock for home

[Richard (Rick) Karlquist]

On 4/4/2017 3:19 PM, Bob kb8tq wrote:

Hi

Based on their web site, the model you saw is the one and only version that
does the new modulation. One very useful feature is the ability to set it to
any time zone world wide. I guess I missed the note on the WWVB coverage
area expanding to cover the entire planet …..:)

Bob



This feature is mainly so you can set the time zone for GMT/UTC.
Hopefully, there is a way to turn off daylight savings time as well.
Many previous atomic clocks covered only the time zones near Boulder
and could not display UTC.

Rick N6RK
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Re: [time-nuts] Time Dilation tinkering

[Richard (Rick) Karlquist]

On 3/21/2017 7:12 PM, Chris Albertson wrote:

"flight" there is the word.Why drive up a mountain?   Take the clock
with you inside the pressurized cabin of a commercial airliner next time
you are on one of those 10 hour trans=pacific flights.   You be taller then
any mountain and it is actually cheaper then a weather balloon.


Yes Len Cutler did that 50 years ago, but the velocity of the plane also
has relativistic effects, so it's not a pure play.

Rick
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Richard (Rick) Karlquist]

On 3/18/2017 3:13 AM, Magnus Danielson wrote:

The NIST-7 was a optically pumped cesium beam, and a pre-cursor to the
fountain clocks. There should be a bunch of papers on it.



I am however somewhat wondering about if we will see this coming out of
Oscilloquartz. We will see.



NIST-7 has a reversible beam, which cancels out end to end phase
error in the CBT.  That works in terms of being a frequency standard,
but not for a clock, because you don't have continuous operation.
NIST-7 is also much longer than the 5071A or the Oscilloquartz offering.
So they are not really comparable beyond sharing optical pumping.

Rick
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Richard (Rick) Karlquist]

Len Cutler was all set to build an optically
pumped Cs beam 20 years ago.  Even then, he could get the lasers.
He was only missing one thing:  money.  HP management never
agreed to fund it. The paper conspicuously omits any spec
on absolute accuracy.  The optical pumping does nothing to
improve that AFAIK.  It still depends on phase error in the CBT.
The 5071 has a guaranteed accuracy of 10^-12, and is typically
several times better than that.

It is surprising that none of the various makers of the 5071A
ever made an optical version.  I wonder what they are thinking
now that someone else has done it.

Rick




On 3/17/2017 7:48 PM, cdel...@juno.com wrote:

Looks like Oscilloquartz is getting ready to sell this commercially!
Will give the 5071A a run for the money!
Reliability should go way up as:
-No electron multiplier
-No ionizer filament
-No state selection magnets
Also all the fiddley bits (laser diodes and photodetectors) are external
to the tube and can be easily updated as needed.

https://www.slideshare.net/ADVAOpticalNetworking/performance-results-of-a
n-optically-pumped-cesium-beam-clock

Cheers,

Corby

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Re: [time-nuts] Bye-Bye Crystals

[Richard (Rick) Karlquist]

On 3/15/2017 4:45 AM, Bob Camp wrote:

Hi

Where do you plan on getting an OCXO grade crystal at an odd frequency like
that? Much of the performance of a good OCXO is in the crystal. Doing a proper
design on one is a lot of work. You *might* think that having a design for 
5.00
MHz would give you a good design for 5.50 MHz. I have empirical evidence 
that
this isn’t the case. Many years later, I’m still utterly amazed that this is 
the way things
work in the crystal business ….( = it’s not just a design issue, it’s also a 
business decision)



Some 30 years ago when GPS was in its infancy, the hardware utilized
OCXO's at 10.23 MHz.  Somehow, HP got suckered into trying to make
modified 10811's that ran at that frequency vs 10 MHz.  Jack Kusters
tried to explain to anyone who would listen that this was a major
redesign of the crystal, because he would have to deal with a new
set of anharmonic spurious modes.  Although only a 2.3% frequency 
change, everything is different.  In terms of business decisions,

only something with as much "juice" as GPS could have gotten Jack
to make a custom frequency.  As it turned out, a few dozen crystals
were made, and that was the end of it.  I managed to snag them
before they were thrown out, in case they might be useful for
something.

The original poster wanted not only an odd frequency (which I don't
recommend for the reasons above) but also wanted to varactor tune
the oscillator.  I also don't recommend doing that because of the
difficulty of generating a clean enough DC voltage.  Against my
advice, the HP smart clocks were tuned with DAC's driving varactors.
They never really got that to work up to their expectations.
Synthesis is so advanced now, 20 years later, that there is
no reason IMHO to voltage tune an OXCO.

Rick
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Re: [time-nuts] Bye-Bye Crystals

[Richard (Rick) Karlquist]

On 3/14/2017 4:03 AM, Bruce Griffiths wrote:



Looking at oscillator circuits like the HP10811A will give some idea of some of 
the additional complexity required for a overtone operation. Dissecting a few 
ocxos may also be helpful. Some start with a 10MHz crystal and a Colpitts 
sustaining stage and use a 74HC74 or similar to  divide the 10Mhz by 2 and 
drive the output pin. Even when a sinewave output is required often a CMOS 
inverter drives the output pin via an LC filter.

Bruce



I don't agree here.  The 10811 is not a good tutorial for general 
oscillator design.  Because it is SC cut, it has a complicated

mode suppression network across the base emitter junction to
suppress mode B as well as the fundamental.

The E1983A oscillator uses the same crystal (in a low profile
package).  You can read my paper about it and see that I
used a very simple bridged tee oscillator circuit.  That is
all you need to select the right overtone and mode.

This is the same circuit that I used at Zeta Labs 40 years
ago to design hundreds of custom VCXO's, up to the 9th
overtone.  It simply worked every time, unlike various other
designs that were in use at Zeta.

Around 1985, I got a consulting gig at Equatorial Communications
to redesign their 5th overtone VCXO.  Only about half of the
crystals would work in their circuit.  They had thousands
of "reject" crystals.  I just used my old Zeta circuit and
all the crystals started working again.

Equatorial owned the 10 meter dish that you used to see on
your right going south on 237 just before passing over
Central Expressway in Mountain View.

Rick N6RK


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Re: [time-nuts] Bye-Bye Crystals

[Richard (Rick) Karlquist]

A complete oscillator consists of the crystal integrated with the 
electronics.  A loose crystal is just a resonator, and the buyer has to 
supply his own electronics.  You rarely see the latter any more in 
applications other  than oven oscillators.  The same thing happened in 
SAW resonators.  About all you can buy now are SAW oscillators.


Rick N6RK

On 3/13/2017 12:07 AM, Bryan _ wrote:

sorry, what do you mean by "complete oscillator" have outnumbered loose 
crystals?


-=Bryan=-



From: time-nuts <time-nuts-boun...@febo.com> on behalf of Richard (Rick) Karlquist 
<rich...@karlquist.com>
Sent: March 12, 2017 4:38 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Bye-Bye Crystals

I got a job in 1975 to design Konel's first synthesized radio, which
was to obsolete their crystal controlled radios.  That's over 40 years
ago.  The other trend (not mentioned) is that since 20 years ago or
so, complete oscillator sales have vastly outnumbered sales of loose
crystals.

Rick N6RK

On 3/11/2017 8:51 PM, Bob Camp wrote:

Hi

International’s main business  was re-channeling non-synthesized radios and 
replacing
broken crystals in various pieces of com gear. It’s been a *lot* of years since 
the last of the
non-synthesized radios came out. The business probably has been dropping off 
pretty steadily
for many years …

Bob


On Mar 11, 2017, at 10:39 PM, jimlux <jim...@earthlink.net> wrote:

On 3/11/17 4:30 PM, Scott McGrath wrote:

From the tone of the letter it sounds like the bank cancelled line of credit,


Or, he wants to retire and nobody wants to carry it on.  His dad started it in 
1950, the son picked it up in 1970.  It's 47 years later.



Which is stupid given that much of their line is military which is getting a 
huge boost in spending


Plenty of other crystal and oscillator manufacturers around.

There's also a change in what kinds of crystals are needed.   I suspect most things being built and 
designed today use the crystal as a "master oscillator" that is used to drive some sort 
of synthesis chain. The need for "I have to have a 12.345,324 Hz crystal" is going away.





On Mar 11, 2017, at 4:56 PM, Bryan _ <bpl...@outlook.com> wrote:

Disappearing or manufacturing just moving overseas?. Video at the bottom is 
interesting, classic.


http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/

[https://www.bing.com/th?id=OVF.LElrlkkbByR3K%2f6qfaeHjg=Api]<http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/>

So Long, and Thanks for all the 
Crystals<http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/>
hackaday.com
There was a time when anyone involved with radio transmitting -- ham operators, 
CB'ers, scanner enthusiasts, or remote control model fans -- had a collection 
of ...







-=Bryan=-
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_

Re: [time-nuts] Bye-Bye Crystals

[Richard (Rick) Karlquist]

I got a job in 1975 to design Konel's first synthesized radio, which
was to obsolete their crystal controlled radios.  That's over 40 years
ago.  The other trend (not mentioned) is that since 20 years ago or
so, complete oscillator sales have vastly outnumbered sales of loose
crystals.

Rick N6RK

On 3/11/2017 8:51 PM, Bob Camp wrote:

Hi

International’s main business  was re-channeling non-synthesized radios and 
replacing
broken crystals in various pieces of com gear. It’s been a *lot* of years since 
the last of the
non-synthesized radios came out. The business probably has been dropping off 
pretty steadily
for many years …

Bob


On Mar 11, 2017, at 10:39 PM, jimlux  wrote:

On 3/11/17 4:30 PM, Scott McGrath wrote:

From the tone of the letter it sounds like the bank cancelled line of credit,


Or, he wants to retire and nobody wants to carry it on.  His dad started it in 
1950, the son picked it up in 1970.  It's 47 years later.



Which is stupid given that much of their line is military which is getting a 
huge boost in spending


Plenty of other crystal and oscillator manufacturers around.

There's also a change in what kinds of crystals are needed.   I suspect most things being built and 
designed today use the crystal as a "master oscillator" that is used to drive some sort 
of synthesis chain. The need for "I have to have a 12.345,324 Hz crystal" is going away.





On Mar 11, 2017, at 4:56 PM, Bryan _  wrote:

Disappearing or manufacturing just moving overseas?. Video at the bottom is 
interesting, classic.


http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/



-=Bryan=-
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Re: [time-nuts] Have done some more cutting on the Cs beam tube

[Richard (Rick) Karlquist]

On 2/18/2017 7:43 PM, Tom Van Baak wrote:

Unless yours is a high-perf 5061 tube I wonder if the degaussing coil even 
exists. Did you pull it from an option /004 frame? Check if there's a separate 
pair of degaussing wires coming from the tube and heading to the rear panel of 
the instrument. That would make a total of 6 coil wires.

Corby will know all of this for sure.

/tvb



I remember that the degausser product that drove the
degaussing coil was a very low priority because Len
Cutler et al insisted that it was unnecessary to
degauss the CBT, at least in the 5071A.  It finally
got produced just to satisfy a few customers who
believed they wanted it.

Rick
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Re: [time-nuts] Optimal oscillator topology for diffrent frequency range

[Richard (Rick) Karlquist]

Agreed, for low phase noise FLOOR, it is imperative to
take the signal out through the crystal.  However, for
close in noise (say ADEV at t=1), the Driscoll has
worked well for me.  I have been able to reach ADEV
= 10^-11 at 100 MHz at using suitable resonators.

Rick

On 2/6/2017 4:35 AM, ka2...@aol.com wrote:

Not quiet, using the crystal also as filter gives much better numbers ,
73 de Ulrich N1UL

In a message dated 2/6/2017 7:30:33 A.M. Eastern Standard Time,
rich...@karlquist.com writes:

I would say the 2 stage "Driscoll" oscillator is the
way to go.  I have had good luck with it up to 100 MHz.
The first stage has the crystal in series with the
emitter, but is otherwise a grounded emitter stage.
The second stage is in cascode as a grounded base.
The important operating condition is that only
the second stage limits.  First publications on
it were in the early 1970's (search Michael Driscoll).

Rick Karlquist N6RK

On 2/6/2017 1:06 AM, Yeti Yetos wrote:
> Good morning,
> What's the optimal  oscillator topology for low phase noise (low
frequency
> noise and phase noise floor) for  25Mhz/50Mhz/100Mhz frequency
range.?
>
> Best regards, Rafal
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Re: [time-nuts] Optimal oscillator topology for diffrent frequency range

[Richard (Rick) Karlquist]

I would say the 2 stage "Driscoll" oscillator is the
way to go.  I have had good luck with it up to 100 MHz.
The first stage has the crystal in series with the
emitter, but is otherwise a grounded emitter stage.
The second stage is in cascode as a grounded base.
The important operating condition is that only
the second stage limits.  First publications on
it were in the early 1970's (search Michael Driscoll).

Rick Karlquist N6RK

On 2/6/2017 1:06 AM, Yeti Yetos wrote:

Good morning,
What's the optimal  oscillator topology for low phase noise (low frequency
noise and phase noise floor) for  25Mhz/50Mhz/100Mhz frequency  range.?

Best regards, Rafal
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Re: [time-nuts] What interrupts aging?

[Richard (Rick) Karlquist]

On 2/5/2017 4:19 PM, Peter Reilley wrote:

I am curious: is the quartz in a high quality quartz crystal perfect?
That is; is the

crystalline lattice perfect, without flaws or impurities?   I assume
that the quartz is

grown in a furnace, can we grow perfect quartz crystals?

Pete.



Even a perfect crystal has thermal stress as the temperature changes.

Rick
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Re: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year

[Richard (Rick) Karlquist]

I downloaded the following:

eagle-win64.exe
eagle-win64-7.7.0.exe
eagle-win64-7.7.0.exe.INF

What is the difference between these files in terms of installing this 
version?  Which file do I run?  Do I need the other ones to go along

with it?

(Similarly, for LINUX, there is the same set of files, except
substitute "run" for "exe")

Rick N6RK
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[time-nuts] OT: Eagle PC CAD now Autodesk, $500/year

[Richard (Rick) Karlquist]

Off topic, but probably a lot of disgrunted Eagle users on this list.
Its official, you will now have to pay $500 per year for a
professional license from Autodesk.  The spin meistering of the
announcement would make George Orwell proud.  I don't see any way they
can keep me from just using the license I currently own, at least
on the OS's it supports.  (Parenthetically, like many users, I
am also digging in my heels in terms of staying at Windows 7).

Still, the question arises:  are there any affordable alternatives?
Don't have to be entirely free.  I am looking for any trends out
there as to what tool will attract a critical mass of users in
the future.  There is strength in numbers.

Comments?

Rick N6RK
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Re: [time-nuts] 10MHz to 25MHz

[Richard (Rick) Karlquist]

On 1/19/2017 5:40 AM, David wrote:


oscillator.  In some applications I would also be concerned about the
phase of a narrow bandpass filter changing with temperature.


The 5061 has tuned bandpass filter multipliers which have exactly this 
problem.  A temperature ramp causes a phase ramp which is the same as a

frequency offset.

Rick N6RK
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Re: [time-nuts] 10MHz to 25MHz

[Richard (Rick) Karlquist]

On 1/18/2017 6:34 PM, David wrote:


An alternative very simple design I might try is a variation of the
active frequency multiplier where the 5th harmonic is filtered
directly from the output of the digital divide by two stage.


That's a useful trick to reduce the filtering burden.  Having said
that, if you need good spectral purity, the filtering is still
going to be very non-trivial.  The original poster is obviously
not an expert in filters and will not be successful trying that
approach, except for very low performance design.  Even if
you are a filter expert, components are hard to get.

Rick N6RK
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Re: [time-nuts] 10MHz to 25MHz

[Richard (Rick) Karlquist]

A better and easier way is to phase lock a crystal oscillator.
I would use a 50 MHz VCXO and divide the output by 2 to get a
25 MHz square wave.

Rick N6RK

On 1/18/2017 10:28 AM, Loren Moline WA7SKT wrote:

Hello,

I am looking for a good X5 multiplier to use to generate a 25MHz signal from my 
10MHz OCXO. I want to divide by 2 and multiply by 5 with a bandpass filter in 
the output and then a 3.3 volt 25MHz signal out.


Maybe someone has better ways?


Loren Moline  WA7SKT

Member: Pacific Northwest VHF Society and ARRL
Member: Hearsat Satellite Monitoring Group.  www.uhf-satcom.com
Member: CVARS-Chehalis Valley Amateur Radio Society
Starchat IRC: Channel = #hearsat
RF Electronics: Starchat IRC: Channel = #rfelectronics
Grid: CN86mr
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[time-nuts] HP counter basic oscillators

[Richard (Rick) Karlquist]

On 12/27/2016 11:48 AM, GandalfG8--- via time-nuts wrote:


All the 5313x counter basic oscillators are indeed extraordinarily poor,
and I've always assumed that their only purpose was to  demonstrate that the
unit was basically functional.



I don't know exactly what is in the 5313X counters, but it might be
like what was in the 5334A counter that I inherited when I was
project manager on the 5334B counter.  Namely, it was an oscillator
utilizing an ECL line receiver as the active device.  The same
design had been used at my previous employer (Zeta Labs).  The
design is championed by engineers who know nothing about designing
crystal oscillators.  Unlike designs using a transistor, the gate
oscillator requires no skill to design and will pretty much
oscillate without fail, and will never squegg.  There is also no
need to convert a sine wave to a logic level signal.

What's not to like about that?  A lot, it turns out.  The temperature 
stability and phase noise are horrible, you have no control over the 
amount of drive to the crystal, and it burns a lot of current for no 
good reason.


I think the usage model breaks down into 3 categories:

1.  You are using the counter for some relatively crude measurement
for example of the frequency of a 555 oscillator, so even the Mickey
Mouse oscillator is good enough.

2.  You need real precision and should move right up to a 10811.

3.  You have an external 10 MHz reference.  For example, at HP,
we had a cesium standard that was distributed around the plant.
This was called the "house standard".  At Zeta Labs we had
an HP105 for the house standard.

Rick N6RK

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Re: [time-nuts] Totally unrelated, but..

[Richard (Rick) Karlquist]

On 12/7/2016 12:16 PM, Clint Jay wrote:

I was looking for a low noise regulator to power a log amp/detector earlier
this year and was rather surprised to find the 78xx regulators were
considerably better than many of the "low noise" devices.



Are you kidding me?  Check out the Linear Technology LT3042 and
LT3045 with 2 (yes, TWO) NANOVOLTS/root-Hz spot noise.  Orders of 
magnitude better than the 78XX introduced 45 years ago.


Rick N6RK
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Re: [time-nuts] Excel logarithmic function (was Thermal impact on OCXO)

[Richard (Rick) Karlquist]

On 11/24/2016 5:16 AM, Bob Camp wrote:


The biggest challenge is to take out the “early stuff”. One approach is to fit
the same equation twice with the time constant restricted to a range on each.
For most OCXO’s (90%) the equation when fit early represents an upper limit
to the drift. You might get a another element that comes in and is apparent
after a year or two. It might be replaced by another element after five or ten 
years.
They generally (~80%) represent a change in sign (negative drift vs positive).

If you look at the “other 10%” some have really poor aging and are not shipped.
Some are very erratic and simply can not be fit. Some of the 90% are fit with a
“upper limit” because they exhibit no measurable aging over the 30 days (or 
whatever)
of testing.

If you take the bad aging (out of spec) parts out of the pile, those are the 
ones
with the best fit. They have very pretty curves and they stick to those curves
for a *long* time. They have a single dominant cause for their aging ( = the 
defect).
The rest of the parts have all of the causes bashed down by the process so that
over a 20 or 30 year span, there probably is no single dominant cause.

Bob




This excellent response channels what Jack Kusters used to say.  The
idea that aging follows any predicable pattern might have been true
decades ago.  For example, I remember being told in 1974 that
everyone knew that metal crystals aged downward and glass crystals
aged upward.  It was true at the time, but those aging processes
have been beat down.  According to Jack, 10811/E1938A aging is
primarily "stress relaxation".  It could be either direction and
a given crystal can change direction over time.  On top of that,
crystals have frequency "jumps" at unpredictable intervals.  At
HP, we had an "aging system" that watched crystals to try to reject
bad actors and find the well behaved ones.  The problem was that the
longer you watched an oscillator, the better chance of catching
it in the act of jumping.  They didn't necessarily get better
over time (over many months).  No matter how many crystals we
looked at, we never found one that had atomic like aging.

My observation is that the systematic (therefore predictable)
aging processes have been eliminated by improved manufacturing
techniques, leaving the true random (unpredictable) aging
processes.

The one thing I can say is that it is good to keep the crystal
ovenized at all times.  Even a momentary oven outage tends to
reboot aging.

Rick
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Re: [time-nuts] HP 55300A

[Richard (Rick) Karlquist]

When I was testing the E1938A I used to run the environmental
test chamber up to 85 degrees C, let the unit stabilize for
a while, and then dump liquid nitrogen into the chamber
to go to -55 degrees C in something like 2 minutes.  The
temperature inside the crystal oven fluctuated maybe a millidegree
and the frequency fluctuated maybe 5 parts in 10^-12 during
this event.  IE, you don't need to worry about a fan blowing
on your OCXO, if it is any good.

Rick

On 11/20/2016 6:41 AM, Gary Neilson wrote:

I recently got a HP55300A on ebay for parts. It works fine but runs on 48V.

I am going  to install a AC supply inside and also place a fan on the
top for cooling.

I hope the air flow will not cool the OCXO too much.

I am also looking for documentation. I have the User manual but am
looking for the Programming Manual.

Thanks

Gary Neilson

K5DSR

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Re: [time-nuts] Question about AD9832 "I out Full Scale" (what does it mean?)

[Richard (Rick) Karlquist]

Well, here is response from ADI:

Quote:
If I remember correctly, this part implements a differential DAC current 
source, but only one of the outputs is bonded externally.
In this case, the current settle by Rset should  be divided by 2..., 
which explain your results.

I'll update the DS as soon as this has been confirmed.
Unquote...

This sounded reasonable when I first read it, but then I realized
that what he was talking about would explain a factor of 2 error
in output VOLTAGE, but not current.  So I think he confused himself.

It should be interesting to see if he can "confirm" it.

Stay tuned.

Rick

On 11/18/2016 1:27 AM, David G. McGaw wrote:

There is something wrong with the example.  The output is single-ended,
so using info from the AD9832 data sheet with Rset=3.9K and Rload=300
ohms as shown in the EVB schematic, it should go from 0 to 3.88mA and 0
to 1.16V.  Figure 12 shows only half this, including only about .3V DC
bias instead of .58V.

I apologize.  As a former Analog Devices applications engineer (Digital
Audio Group), I find this data sheet and user guide poorly written.
They have a lot of digital and almost no analog information.

David N1HAC


On 11/17/16 11:09 PM, Richard (Rick) Karlquist wrote:

Trying to figure out what "Iout Full Scale" means on the AD9832.
Some time nuts may have used this one.

On page 7 of this doc:

http://www.analog.com/media/en/technical-documentation/user-guides/UG-313.pdf


It shows the AD9832 output as 572 mV peak to peak
across 300 ohms.  This works out to 1.9 mA peak to
peak current through the resistor.  But Rset on the
board is 3.9K, which is supposed to give a value
for so-called "Iout Full Scale" of 3.878 mA.

I would have thought (just guessing) that peak to
peak output current would be equal to Iout Full
Scale, but it appears to be only half of that.

Can anyone clarify this?

Rick
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Re: [time-nuts] Need for a document comparing time interval counters

[Richard (Rick) Karlquist]

On 11/21/2016 1:10 PM, Bob Camp wrote:

Hi

With both counters running on the same external standard (and no internal 
OCXO), the 53230
beats the 53132 both on frequency and time. It also has slightly better 
isolation of the 10 MHz
internals so the “dead zone” at 10 MHz is not quite as bad. I have no idea how 
either one
works with the OCXO option … I’ve never seen either one with an OCXO.

Bob



I remember when the 10 MHz section of the 53132 was designed.
The designers had little knowledge of how to do that correctly.
It wasn't their fault; it was the fault of the manager who
assigned the task to them.

Rick
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Re: [time-nuts] Need for a document comparing time interval counters

[Richard (Rick) Karlquist]

I had a 53230 the last few years I worked for Agilent.
The oven oscillator in it is inferior to a 10811.
Its only claim to fame IMHO is that it can measure
Allan Deviation.  Turns out that we really needed
Hadamard, but it doesn't do that.  It is very expensive.
The old Santa Clara Division with the counter expertise
has now been gone nearly 20 years.  The counter line
has been offshored.  The expertise over there is
a complete unknown.

Rick

On 11/19/2016 5:55 PM, Dr. David Kirkby wrote:

If anyone has the time & inclination, a document comparing different time 
interval counters would be useful to budding time nuts. There are quite a few 
different models at prices that are affordable to many.

I have had a HP 5370B and a Stanford Research  SR620, but have neither now. I 
regretted selling the HP, but then after buying the SR620, I swapped that and a 
4.2 GHz HP signal generator for an HP 4291B 1.8 GHz impedance and material 
analyzer.

I was looking for something cheap,  but see a used Keysight 53230A on eBay for 
considerably more than a new one from Keysight. It had a "make offer" so I 
could not resist pointing out a new one is much less, and making a redicously low offer 
of $1000. I doubt it will be accepted,  but one never knows.  I once got a current 
Ketsight product for 2% of the current price,  so anything is possible.

But a  comparison of TI counters,  and a discussion of the important 
specifications would be njce.


.Dave.
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[time-nuts] Question about AD9832 "I out Full Scale" (what does it mean?)

[Richard (Rick) Karlquist]

Trying to figure out what "Iout Full Scale" means on the AD9832.
Some time nuts may have used this one.

On page 7 of this doc:

http://www.analog.com/media/en/technical-documentation/user-guides/UG-313.pdf

It shows the AD9832 output as 572 mV peak to peak
across 300 ohms.  This works out to 1.9 mA peak to
peak current through the resistor.  But Rset on the
board is 3.9K, which is supposed to give a value
for so-called "Iout Full Scale" of 3.878 mA.

I would have thought (just guessing) that peak to
peak output current would be equal to Iout Full
Scale, but it appears to be only half of that.

Can anyone clarify this?

Rick
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Re: [time-nuts] Do the HP 5334A & 5335A counter/timers take the same oven oscillator?

[Richard (Rick) Karlquist]

In general, any 10811 with an edge card type connector
in interchangeable in any instrument, in terms of basic
functionality.  The only differences
are that various part numbers in the 10811 family are
selected for certain critical specs.  Certainly, between
the 5334 and 5335, they are interchangeable.  OTOH,
an instrument like the 8662A might not meet phase noise
without the "official" version of 10811.

A 10811 also must work in any 10544 socket, although the
reverse isn't necessarily true.

The 5334A (as opposed to the 5334B that I was the project
manager on) has a poorly regulated power supply that causes the oven
power voltage to drop to only +12V during warmup, which
is supposedly below the +15V minimum and the +20V nominal.
It turns out that +12V is sufficient to cause the oven
to warm up.  It is not sufficient to operate the oven
well in a steady state.  However, once the oven current
cuts back, the power supply voltage goes back up to over
15 volts so everything works.  I fixed this problem in
the 5334B.  I don't know if the 5335 has a similar problem.

Rick
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Re: [time-nuts] Sapphire oscillators

[Richard (Rick) Karlquist]

A lot of hype has been coming out of the left coast down
under for many years, with this being the latest example.
This technology tends to produce the world's most sensitive
microphone.  It's also a fairly sensitive thermometer, too,
which the helium bath tends to mask.  The prices asked
have tended to be fairly high.  Agilent (now Keysight) has made sapphire
resonators like this for use at room temperature on an
experimental basis.  They have a considerably better
design; I just happened to be talking to the designer
today, who is no longer with Keysight.  Last I heard
(2014) they were struggling with microphonics.  There
was also the well known problem of insufficient management
support for the technology.

Another issue is identifying the electronics that can
utilize this signal without degrading it.  And how to
measure this electronics to prove it isn't degrading
the signal.

Before the sapphire craze, HP/Agilent developed a
1 GHz dielectric resonator cavity (not a coaxial
resonator) that was huge.  The "puck" rivaled a
hockey puck.  I don't believe this ever got productized.
It was another big microphone of course.

Another HP experimental oscillator was a VCO that
covered an octave using around 100 varactor diodes.
It was called the "wagon wheel oscillator".  Again,
it was a hero experiment.  The total RF power was
enormous.

Just putting all this into perspective.

Rick


On 11/9/2016 4:20 PM, Jim Palfreyman wrote:

Anyone got any comments on this?

http://www.theleadsouthaustralia.com.au/industries/technology/worlds-most-precise-clock-set-for-commercial-countdown/


Jim Palfreyman
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Re: [time-nuts] 5071A with ATTENTION flashing

[Richard (Rick) Karlquist]

Regarding error codes in the 5071A.  This "feature"
was an afterthought.  All of us hardware designers
brought out test points that were easy to implement
and then the microcontroller polled them and software
was written to give error reports.  We did what was
easy on already finished board designs; not what
would be optimum if designing from the ground up.
If you can repair a 5071 based on the error code,
consider yourself lucky.

It is analogous to that old gag about the drunk
who is crawling around under the only street light
in the neighborhood.  A bystander asks him what
he is doing and he says he is searching for his
wallet that he lost.  The bystander asks him where
he lost it and he says "on the next block".
The bystander asks him why search here and he
says this is the only place with light.

Rick
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Re: [time-nuts] Thinking outside the box a super reference

[Richard (Rick) Karlquist]

One of the main limiting factors in the 5061 was
microwave leakage.  An excellent Italian engineer
named DiMarchi mastered the so called "top cover
effect", where removing the top cover changed the
frequency.  He had a small business going refurbishing
5061's by cleaning up the waveguide gasketing, etc.
If any 9192.63177 reaches the beam at one end or
the other, it will upset the phase balance.  In
the 5071, phase balance is the main limiting factor
in accuracy.  They go to extreme measures to make
the cavity absolutely symmetrical using fabrication
techniques analogous to "self aligning" IC masking.
In the 5071, the only place 9192 shows up is in the
microwave module that is directly attached to the
coax to waveguide transition into the cavity.
There are no frequencies anywhere that are sub
harmonics of 9192.  Incidentally, there are no
frequencies anywhere that are coherent with
50 Hz, 60 Hz, etc line frequencies.  Nothing
is by accident when Len Cutler is involved.

In terms of basic synthesizer architecture, the
mix from 9280 to 9192 using 87 is described by
the technical term "free lunch" :-)  We pick
up two decades of resolution.  Furthermore, we
don't have to filter out 9280 or 9367 because
they are ignored by the CBT.  One of the reasons
for going up from 12 to 87 was to get these
spurs safely removed from anything that would
interact quantum mechanically with the cesium
line tail.  With the increased accuracy, 12
was no longer high enough.

Rick

On 11/5/2016 7:39 AM, Attila Kinali wrote:

Hoi Rick,

On Sat, 5 Nov 2016 07:17:21 -0700
"Richard (Rick) Karlquist" <rich...@karlquist.com> wrote:


I think this is all described in the 1992 FCS papers,
but the executive summary is that a direct synthesizer
on 9192.63177 is to be avoided at all costs because
of the danger of it leaking into the CBT cavity.
This is also the reason why you don't multiply up
a subharmonic of this frequency.



I don't get what you mean with "danger of leaking into the CBT cavity"?
When signal leakage into the cavity is a problem, shouldn't that also
exist for the signal after the mixer? And what does this leaking actually
mean? The 9192.63177 is supposed to end up in the cavity anyways.

Attila Kinali


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Re: [time-nuts] Thinking outside the box a super reference

[Richard (Rick) Karlquist]

On 11/5/2016 12:18 AM, Poul-Henning Kamp wrote:


In message <768ee5a7-1c53-06cf-cf36-ec75e2901...@karlquist.com>, "Richard (Rick) 
Karlquist" w
rites:


Reminds me of an interesting Jack Kusters story.
There was some customer who was having problems with
his atomic clocks being noisy (I don't remember exactly
the story) but the bottom line was that they determined
it was because of helium contamination.


How would helium make his clocks noisy ?

Isn't it more likely that it was the alphas from the
radon decay that did it by their charge ?


I probably am not remembering the story exactly, but
I do definitely remember it had to do with unexplained
helium, which they tried to blame Kusters company for.
He said there was a simple explanation, namely radon
gas emitting alpha particles that turn into helium
and helium can diffuse into "sealed" containers.
He basically told them that if they dropped the issue,
it wouldn't be necessary for him to publicize the fact
that their plant was full of radon.  It was really
funny when Jack himself told it.

Rick

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Re: [time-nuts] Thinking outside the box a super reference

[Richard (Rick) Karlquist]

I think this is all described in the 1992 FCS papers,
but the executive summary is that a direct synthesizer
on 9192.63177 is to be avoided at all costs because
of the danger of it leaking into the CBT cavity.
This is also the reason why you don't multiply up
a subharmonic of this frequency.
It would also have made the synthesizer a lot more
complicated.  We multiplied 10 to 320 and then used
an SRD to get to 9280 and applied a sideband at 87.36
MHz to it.  The 87.36 MHz synthesizer was a phase
locked VCXO using a 5th OT crystal.

It took me a long time for me to sell this to Len Cutler.
It was pretty advanced for 1989.

Rick

On 11/4/2016 7:12 PM, paul swed wrote:

Rick on the pll DRO I agree with you for today.
So is it built for 9180 and then the 12.63 is mixed with it? Or is it
actually a direct PLL precisely at the frequency so not even the
synthesizer is used?
Regards
Paul
WB8TSL

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Re: [time-nuts] Thinking outside the box a super reference

[Richard (Rick) Karlquist]

On 11/4/2016 5:24 PM, Poul-Henning Kamp wrote:

Yes, that sounds about right for an isotope with a 40 billion years
half-life.



The problem with the half life number is that the cylinder
still was marked "radioactive" complex with the radiation
symbol.  Radioactivity (for legal purposes) is a binary
property.  We used to mark CBT's "cesium device, non radioactive"
because the work "cesium" means "cesium 137 nuclear fallout"
to many people.

Reminds me of an interesting Jack Kusters story.
There was some customer who was having problems with
his atomic clocks being noisy (I don't remember exactly
the story) but the bottom line was that they determined
it was because of helium contamination.  Kusters was
called in to answer to the customer about this contamination
and how they were going to fix it.  Kusters measured the
air in the customer's plant and found that in contained
helium.  But the customer did not use helium at all in the
plant.  Kusters pointed out that that could mean only one
thing:  the plant had a radon problem, and radon breaks down
into helium.  Kusters told the customer that if they
dropped the complaint, he wouldn't have to say anything
about radon to anyone.  That was the last heard about the
helium problem.

Rick

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Re: [time-nuts] Thinking outside the box a super reference

[Richard (Rick) Karlquist]

On 11/4/2016 4:04 PM, Poul-Henning Kamp wrote:


Historically resonance cavities were used so that step/avalance
diode multipliers had enough power to excite them.  Today we have
semiconductors which work at those frequencies.



A great deal of complexity in the 5061 went into
exciting an SRD at 90 MHz and getting a sufficient
line at 9180 MHz to put on a sideband at 9192.
I spent a lot of time trying to do this during the
5071 project and was never able to get anywhere
near the efficiency that the 5061 waveguide structure
was able to do.  It was designed by a visiting Korean
professor, so he wasn't around to mentor me.
The 10816 also used an SRD, and it was also a
struggle, although I was able to make it work.

Fortunately, we were able to replace all this with a
DRO and PLL, and that was 25 years ago.  At this time,
it is even more of a no brainer that you don't want
to knock yourself out trying to make an SRD multiplier
work.  Also, these days, it is harder than ever to
purchase good SRD's.

Rick
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Re: [time-nuts] Satellite TV messed up, how is GPS time

[Richard (Rick) Karlquist]

On 11/4/2016 2:51 PM, Don Murray via time-nuts wrote:

DirecTV and DishNetwork are on Ku-Band platforms.
Ku-Band is not affected by sun outage.

Don
W4WJ



The backhaul on C band might be affected.

Rick
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Re: [time-nuts] Thinking outside the box a super reference

[Richard (Rick) Karlquist]

On 11/3/2016 1:07 PM, Bert Kehren via time-nuts wrote:


Over the past there has been talk about building from  scratch high
performance references. I think consensus was that it is out of  reach. In the 
mean


I was on the design team for the HP 10816 mini rubidium
which leveraged the production capabilities of the
HP 5065 such as glass blowing, etc., although what we
called "glassware" was much smaller in the 10811
than the 5065.  IMHO, the glassware
is the critical item.  Of the glassware, the lamp is
probably the most finicky.  The glassware used some
glass type (forgot the number) that was only slightly
removed from fused quartz.  Very difficult to work
with.  Also, one of the Rb isotopes is slightly radioactive.
35 years ago, the guy in the next cubicle got away with
storing it under his desk.  He also happily smoked
cigarettes all day at his desk.  Another ERA.

HP IIRC supplied "RVFR" assemblies to customers who wanted
to roll their own electronics to use in military applications
where the 5065 wasn't suitable.  I would consider approaching
current manufacturers of Rb standards to see if they would
make glassware to order.

Another thing to consider is optically pumped Rb.  This is
now possible with available lasers.  There are some DARPA
projects in this area that I know of.  I can put you in
contact with the right person.  Optical pumping gets rid of
the lamp hassle and the radioactive isotope for the filter
cell.

The rest of the standard can be built in a garage using various
contract manufacturers available online.   If I can give any advice 
about this project, feel free to throw me some questions.


Rick Karlquist N6RK

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Re: [time-nuts] So what’s inside that Cs Beam Tube anyway?

[Richard (Rick) Karlquist]

On 11/2/2016 10:23 AM, Tom Van Baak wrote:

Hi Rick,



You know the famous 1971 Hafele-Keating experiment with four 5061 cesium clocks 
flying around the world. Several years later, a more precise measurement was 
made by Carroll Alley using better clocks. What I read is that he got Len 
Cutler to hack the 5061A so that its beam current would be higher, thereby 
improving performance for the duration of the experiment. Same tube, just 
different operating parameters.



Never heard that story.  You gotta love it:  a hot rod atomic clock.

Rick
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Re: [time-nuts] So what’s inside that Cs Beam Tube anyway?

[Richard (Rick) Karlquist]

This has probably been covered here before, but, at least going
to the 5071A, now 25 years ago!, all CBT's, whether high
performance or not, have the same amount of cesium inside.
This means that the standard performance (never call it
"low" performance) CBT has enough cesium to last 30 years!
Thus for those tubes, we can rule out cesium replenishment
even if it were possible.

Rick

On 11/1/2016 8:38 PM, Mark Sims wrote:

You mean I can't just drill a hole in,  wash out the old cesium with some tap 
water ;-),  toss in some new cesium, suck out the air,  bung a cork in the 
hole, and call it a day?   Drat! foiled again...

---


Because it's not that easy. We are talking about a high vacuum system here.

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Re: [time-nuts] Cs tube pics

[Richard (Rick) Karlquist]

On 10/31/2016 10:18 PM, Tom Van Baak wrote:


So if you keep hacking on your tube(s) you should get to the same point as they 
did. If nothing else, you can use my photos of hp's display as a hint of where 
and where not to cut! Note that the shinny copper will look fantastic at first 
but may dull over time. The chemists on the list can recommend how to preserve 
it.

When you're all done you'll realize just how amazing it is that an entire 
atomic physics laboratory can be reduced to the size of a 2L water bottle, with 
a 68000 CPU playing the role of the grad student. It can run 24x7 for 10 to 20 
years and remain accurate to better than 1e-13. That's why everyone should own 
a cesium standard after they grow tired of playing with GPSDO.

/tvb
___


Thanks for posting that Tom.  You make me feel
like I'm still relevant :-)

Rick
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Re: [time-nuts] So what’s inside that Cs Beam Tube anyway?

[Richard (Rick) Karlquist]

I remember when they made tubes in Santa Clara, they
would assemble them and do some tests without breaking
the Cs ampule.  A fair percentage would fail and would
go to a machinist using a big lathe to cut
them open to be rebuilt.  It was very important that
the Cs had not been released yet.

Rick
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Re: [time-nuts] So what’s inside that Cs Beam Tube anyway?

[Richard (Rick) Karlquist]

The ghost of Jack Kusters is now spinning in his grave on
this Halloween night.  Jack was a fairly opinionated
guy and it didn't take much to get him excited.

Jack used to rail against people who asked this naive
question.  There are any number of reasons why this
doesn't make sense.  One major one is that everything
in the tube is thoroughly "cesiated" as Jack put it.
Another is:  how do you determine which parts to replace?
Another is:  is this economically feasible?

Rick
N6RK

On 10/31/2016 2:50 PM, ed breya wrote:


It's a shame that they're not built in such a way that just the wear-out
parts could be replaced, and not wasting all the rest of the design and
craftsmanship that's probably just fine.

Ed
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Re: [time-nuts] Difference in manufacturing for fundamental tone, 3rd, and 5th overtone crystals

[Richard (Rick) Karlquist]

On 10/27/2016 4:50 PM, Bob Camp wrote:

Hi

Crystals are highly optimized for the specific overtone they are
intended to operate on. In fact, you can fiddle them to the point
that they no longer have a “fundamental” response.

Bob



That's interesting.  Every overtone crystal I have played with
would happily oscillate at the fundamental.  How do they
get rid of the fundamental?

Rick
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Re: [time-nuts] Temp/Humidity control systems?

[Richard (Rick) Karlquist]

On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:

I may have the opportunity to build a small "clock room" and am
considering whether I could make it an environmentally controlled space.
 I'd like to learn about the options for doing this.

The space would probably be 6x8 feet or so, in a basement with one
outside wall.



I'm lost with the basic concept here.  Help me understand this.

If you go in and out of this room through a door, I don't
know how you prevent large fluctuations in temp/humidity.
You would probably need an air lock.

Is it a "room" where humans go, or just a "chamber" that is
locked up most of the time?

Rick N6RK
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