time-nuts Digest, Vol 79, Issue 31

[gonzo .]

Thanks for the comments and suggestions.

I've dropped the heatsink temp to 69C simply by swapping the side panels (a small step in the right direction).

The internal fan makes a fair howl, so a small fan or two will hardly be noticed! The original fan is moving plenty or air, but it's sounding like the bearing is past it's prime.
I'll replace it as soon as I can find something suitable (110V fans are a bit thin on the ground around here).

Cheers,
Ian

> ------------------------------
>
> From: paul swed <paulswedb-***@public.gmane.org>
> Subject: Re: [time-nuts] HP 5370A temp
>
> Yup various components have been run hot.
> Like others in this group add a fan to the heat sink. Found a way to route a
> wire out from the raw 5 volt supply to run a 12 volt fan. Think I took one
> bolt out of the heat sink to route the wire. Think I added a resistor as I
> did not need a lot of air to calm the heat sink down.
>
> Definitely consider changing really stressed components they can be a bit
> brown and still be OK. Measure them.
> Good luck
> Regards
> Paul
> WB8TSL
>
>
> ------------------------------
>
> From: "Don Latham" <djl-***@public.gmane.org>
> Subject: Re: [time-nuts] HP 5370A temp
> To: "Discussion of precise time and frequency measurement"
>
> My 5370a's both run hot as heck. I used some cheap small c-clamps and some
> old heatsinks to increase the area of the hp heatsinks. You can also run
> an old fan if you have one. I've found that the whole era of Hp equipment
> runs too darn hot. 3325a, 8656a, etc. etc.
> Don
>
>
>
> --
> "Neither the voice of authority nor the weight of reason and argument are
> as significant as experiment, for thence comes quiet to the mind."
> R. Bacon
> "If you don't know what it is, don't poke it."
> Ghost in the Shell
>
>
> Dr. Don Latham AJ7LL
> Six Mile Systems LLP
> 17850 Six Mile Road
> POB 134
> Huson, MT, 59846
> VOX 406-626-4304
> www.lightningforensics.com
> www.sixmilesystems.com
>
>
>
>
> ------------------------------
>
> From: "Bob Camp" <lists-***@public.gmane.org>
> Subject: Re: [time-nuts] HP 5370A temp
> To: "'Discussion of precise time and frequency measurement'"

>
> Hi
>
> Gee, a low cost 5370....
>
> The nice thing is that even though it runs hot - it's done it for a *long*
> time. I certainly would not argue against a fan. They are a *very* good
> idea. However it's not going to turn to dust without one.
>
> I would definitely keep it clean and keep the back side open to air. As you
> have noted - make sure the vent holes are where they should be and
> unblocked. Stacking 5 or 10 on top of each other likely isn't a good idea
> either ....
>
> Bob
>
> ------------------------------
>From: "gbusg" <gbusg-***@public.gmane.org>
>Subject: Re: [time-nuts] HP 5370A temp
>To: "Discussion of precise time and frequency measurement"
>
>I think 61?C might be more typical, so 76?C seems pretty darn hot to me. I
>would make sure that your fan is running, and is mounted the right
>direction. (It should be blowing *into* the instrument.)
>
>Also make sure that the top instrument cover is installed. (The top cover
>must be in place so that the internal fan air currents will loop around and
>pass through vents, including the through-holes in the rear heat sink.)
>
>Greg

[Bob Bownes]

Ian,

I've dropped the temp and the noise level in my 'lab' by replacing
many of the old 110V fans whose bearings are getting on with more
modern 'silent' 12V fans that use less power, move more air, and are
far quieter than the 110 fans ever were. You can find them from a
number of sources online, and while rated at 12Vdc, they run pretty
well on anything from 5-15.

Bob


On Thu, Feb 10, 2011 at 4:14 PM, gonzo . <cadbloke-***@public.gmane.org> wrote:
>
>
>
>
> Thanks for the comments and suggestions.
>
> I've dropped the heatsink temp to 69C simply by swapping the side panels (a small step in the right direction).
>
> The internal fan makes a fair howl, so a small fan or two will hardly be noticed! The original fan is moving plenty or air, but it's sounding like the bearing is past it's prime.
> I'll replace it as soon as I can find something suitable (110V fans are a bit thin on the ground around here).
>
> Cheers,
> Ian
>

[Rick Karlquist]

Bob Bownes wrote:
> Ian,
>
> I've dropped the temp and the noise level in my 'lab' by replacing
> many of the old 110V fans whose bearings are getting on with more
> modern 'silent' 12V fans that use less power, move more air, and are
> far quieter than the 110 fans ever were. You can find them from a
> number of sources online, and while rated at 12Vdc, they run pretty
> well on anything from 5-15.

I don't see why changing the operating voltage of the fan would
make bearings last longer, move more air, or make less noise,
unless it allows the fan to run at a different RPM. Even then,
more air and less noise would seem to be mutually exclusive.

Rick

[Hal Murray]

richard-***@public.gmane.org said:
> I don't see why changing the operating voltage of the fan would make
> bearings last longer, move more air, or make less noise, unless it allows
> the fan to run at a different RPM. Even then, more air and less noise would
> seem to be mutually exclusive.

Somewhere in the past 10-20 years, people started paying much more attention
to how much noise fans make. For a given amount of air, most modern fans are
a lot quieter than old ones.

I think one big step is to keep the support bars away from the fan blades and/or make them smaller. There are probably some important details about the fan blade shape that I don't understand.


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

[Bob Bownes]

Not to mention improvements in motor design. The brushless motors have
gotten better and the change to lighter plastics has put much less
burden on the bearings, which while they might not last as long, sure
are a lot quieter. One of the parameters you can use now to select
fans is the noise factor for a given cfm. Simply replacing the old,
loud fans in 3 or 4 pieces of test gear has really quieted things down
for me.

As you say, the big changes are in getting more air to move with less
turbulence at a lower rpm by changes in blade design. Probably a few
former submarine prop designers making money in their retirement. ;)


On Thu, Feb 10, 2011 at 9:38 PM, Hal Murray <hmurray-8cQiHa/C+6Go9G/***@public.gmane.org> wrote:
>
> richard-***@public.gmane.org said:
>> I don't see why changing the operating voltage of the fan would make
>> bearings last longer, move more air, or make less noise, unless it allows
>> the fan to run at a different RPM.  Even then, more air and less noise would
>> seem to be mutually exclusive.
>
> Somewhere in the past 10-20 years, people started paying much more attention
> to how much noise fans make.  For a given amount of air, most modern fans are
> a lot quieter than old ones.
>
> I think one big step is to keep the support bars away from the fan blades and/or make them smaller.  There are probably some important details about the fan blade shape that I don't understand.
>
>
> --
> These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[Rick Karlquist]

It isn't clear why you need to change to 12V fans.
Why not "modern" 120V fans?

Rick

[bownes]

I've not seen 110v fans in 'ultraquiet'.



On Feb 10, 2011, at 11:37 PM, "Rick Karlquist" <richard-***@public.gmane.org> wrote:

> It isn't clear why you need to change to 12V fans.
> Why not "modern" 120V fans?
>
> Rick
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[mikes-kj5vH+ (Mike S)]

At 11:37 PM 2/10/2011, Rick Karlquist wrote...
>It isn't clear why you need to change to 12V fans.
>Why not "modern" 120V fans?

The PC market has driven the creation of quiet, low cost, 12V, 80mm
fans.

You can get a ball-bearing Pabst 8506N, which is comparable to the
original fan, 35 dba noise, 11 Watts, from Mouser for ~$45 shipped.

Or you can get a 12V ball-bearing fan with similar specs, which is 5
dba quieter, and draws 2 W, for $9 shipped. (
http://www.newegg.com/Product/Product.aspx?Item=N82E16811999107 ) You
could also get a 12V sleeve-bearing fan @24 dba for $10.

I have no idea how what noise rating the original Pamotor (Pabst) 8500C
had.

[paul swed]

With humor it was loud
Like the alternates

On Fri, Feb 11, 2011 at 9:16 AM, Mike S <mikes-kj5vH+***@public.gmane.org> wrote:

> At 11:37 PM 2/10/2011, Rick Karlquist wrote...
>
>> It isn't clear why you need to change to 12V fans.
>> Why not "modern" 120V fans?
>>
>
> The PC market has driven the creation of quiet, low cost, 12V, 80mm fans.
>
> You can get a ball-bearing Pabst 8506N, which is comparable to the original
> fan, 35 dba noise, 11 Watts, from Mouser for ~$45 shipped.
>
> Or you can get a 12V ball-bearing fan with similar specs, which is 5 dba
> quieter, and draws 2 W, for $9 shipped. (
> http://www.newegg.com/Product/Product.aspx?Item=N82E16811999107 ) You
> could also get a 12V sleeve-bearing fan @24 dba for $10.
>
> I have no idea how what noise rating the original Pamotor (Pabst) 8500C
> had.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[s***@public.gmane.org]

In many instruments, a lot of the fan noise is actually noise from the air blowing over obstructions, so changing the fan will not reduce that noise, unless the air flow is reduced. That will be generally true for the type of equipment that dissipates a lot of heat in a small package, like a Tek 492/494 spectrum analyzer.
Support bars and perforated panels just in front of the fan are often not helping with the noise or the air flow.
I think the 5370 is not that bad from an obstruction standpoint, and a lot of the noise is actually due to the age and design of the fan itself.
In some cases, mounting an AC fan on rubber mounts may help with vibrations, if you have the room.

I agree with Hal, in my experience, older AC fans with metal blades tend to be much noisier than recent DC fans with plastic blades for comparable air flow.

Didier KO4BB

Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: Hal Murray <hmurray-8cQiHa/C+6Go9G/***@public.gmane.org>
Sender: time-nuts-bounces-***@public.gmane.org
Date: Thu, 10 Feb 2011 18:38:11
To: Discussion of precise time and frequency measurement<time-nuts-***@public.gmane.org>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts-***@public.gmane.org>
Subject: Re: [time-nuts] time-nuts Digest, Vol 79, Issue 31


richard-***@public.gmane.org said:
> I don't see why changing the operating voltage of the fan would make
> bearings last longer, move more air, or make less noise, unless it allows
> the fan to run at a different RPM. Even then, more air and less noise would
> seem to be mutually exclusive.

Somewhere in the past 10-20 years, people started paying much more attention
to how much noise fans make. For a given amount of air, most modern fans are
a lot quieter than old ones.

I think one big step is to keep the support bars away from the fan blades and/or make them smaller. There are probably some important details about the fan blade shape that I don't understand.


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




_______________________________________________
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[s***@public.gmane.org]

Most AC fans of a given size will have a bigger motor than DC fans of the same size. That leaves less cross section for the air, therefore for the same air flow, air will have to move faster and be noisier. It is not a question of 12V versus 120V, its DC versus AC.

Didier KO4BB

------Original Message------
From: Rick Karlquist
Sender: time-nuts-bounces-***@public.gmane.org
To: Time-Nuts
ReplyTo: richard-***@public.gmane.org
ReplyTo: Time-Nuts
Subject: Re: [time-nuts] time-nuts Digest, Vol 79, Issue 31
Sent: Feb 10, 2011 10:37 PM

It isn't clear why you need to change to 12V fans.
Why not "modern" 120V fans?

Rick


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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


Sent from my Verizon Wireless BlackBerry

[Hal Murray]

richard-***@public.gmane.org said:
> FWIW, the E1938A oscillator control board had a "happy light" LED that
> flashed 1 time per second, and sure enough this corrupted the power supply
> and affected some applications. We added a command to turn it off.

Why should lights blink when they are happy?

Your eye is real good at noticing blinking things. Why not use blinking for
things that are broken and need attention?

Of course, with a PPS, blinking is an obvious thing to do: 1 resistor, 1 LED,
your eye does all the work.

I built a converter from blink on happy to blink on sad. I've been happy
with it.


--
These are my opinions. I hate spam.

[Magnus Danielson]

On 05/16/2012 05:25 AM, Hal Murray wrote:
>
> richard-***@public.gmane.org said:
>> FWIW, the E1938A oscillator control board had a "happy light" LED that
>> flashed 1 time per second, and sure enough this corrupted the power supply
>> and affected some applications. We added a command to turn it off.
>
> Why should lights blink when they are happy?
>
> Your eye is real good at noticing blinking things. Why not use blinking for
> things that are broken and need attention?
>
> Of course, with a PPS, blinking is an obvious thing to do: 1 resistor, 1 LED,
> your eye does all the work.
>
> I built a converter from blink on happy to blink on sad. I've been happy
> with it.

If you have a timer trigger that invert the LED drive, when it gets
stuck for whatever reason, then you will notice the lack of blinking.
This is why happy blinking is being used. It's really a form of simple
software debugging tool in its simplest form.

You could get a watchdog timer that would trigger an unhappy blinker.
More hardware.

Cheers,
Magnus

[s***@public.gmane.org]

It would be very easy to use a constant current to drive the LED and simply short it periodically to provide the blinking without supply current variations. You would still have short transients in the drive circuit, but these should be much easier to filter.

Didier KO4BB

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

-----Original Message-----
From: Magnus Danielson <magnus-0aYeopylZ8Qi5CQI31g/s0B+***@public.gmane.org>
Sender: time-nuts-bounces-***@public.gmane.org
Date: Wed, 16 May 2012 09:51:00
To: <time-nuts-***@public.gmane.org>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts-***@public.gmane.org>
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?

On 05/16/2012 05:25 AM, Hal Murray wrote:
>
> richard-***@public.gmane.org said:
>> FWIW, the E1938A oscillator control board had a "happy light" LED that
>> flashed 1 time per second, and sure enough this corrupted the power supply
>> and affected some applications. We added a command to turn it off.
>
> Why should lights blink when they are happy?
>
> Your eye is real good at noticing blinking things. Why not use blinking for
> things that are broken and need attention?
>
> Of course, with a PPS, blinking is an obvious thing to do: 1 resistor, 1 LED,
> your eye does all the work.
>
> I built a converter from blink on happy to blink on sad. I've been happy
> with it.

If you have a timer trigger that invert the LED drive, when it gets
stuck for whatever reason, then you will notice the lack of blinking.
This is why happy blinking is being used. It's really a form of simple
software debugging tool in its simplest form.

You could get a watchdog timer that would trigger an unhappy blinker.
More hardware.

Cheers,
Magnus

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time-nuts mailing list -- time-nuts-***@public.gmane.org
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[Magnus Danielson]

On 05/16/2012 02:21 PM, shalimr9-***@public.gmane.org wrote:
> It would be very easy to use a constant current to drive the LED and simply short it periodically to provide the blinking without supply current variations. You would still have short transients in the drive circuit, but these should be much easier to filter.

Agreed. You could also have a pair of LEDs and alternate which of them
is lit.

Then, to reduce the impact on the PPS signals, the LED on/off could be
forced to be phase-shifted to the PPS.

Cheers,
Magnus

[Dave Martindale]

But if the LED transition was offset any significant amount of time from
the PPS, you wouldn't be able to use it to set your watch!

Dave :-)

On Wed, May 16, 2012 at 10:57 AM, Magnus Danielson <
magnus-0aYeopylZ8Qi5CQI31g/s0B+***@public.gmane.org> wrote:

>
> Then, to reduce the impact on the PPS signals, the LED on/off could be
> forced to be phase-shifted to the PPS.
>
>
>

[Magnus Danielson]

On 05/16/2012 07:42 PM, Dave Martindale wrote:
> But if the LED transition was offset any significant amount of time from
> the PPS, you wouldn't be able to use it to set your watch!
>
> Dave :-)

Well, the offset compensates for the protein computer delay.

Cheers,
Magnus

>
> On Wed, May 16, 2012 at 10:57 AM, Magnus Danielson<
> magnus-0aYeopylZ8Qi5CQI31g/s0B+***@public.gmane.org> wrote:
>
>>
>> Then, to reduce the impact on the PPS signals, the LED on/off could be
>> forced to be phase-shifted to the PPS.
>>
>>
>>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[Tom Holmes]

The LED current could also be switched with a very long rise/fall time so
that there isn't any transient, in the abrupt sense of the word. Who's gonna
see the difference?

Tom Holmes, N8ZM
Tipp City, OH
EM79


> -----Original Message-----
> From: time-nuts-bounces-***@public.gmane.org [mailto:time-nuts-bounces-***@public.gmane.org] On
> Behalf Of Magnus Danielson
> Sent: Wednesday, May 16, 2012 10:57 AM
> To: time-nuts-***@public.gmane.org
> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
>
> On 05/16/2012 02:21 PM, shalimr9-***@public.gmane.org wrote:
> > It would be very easy to use a constant current to drive the LED and
simply
> short it periodically to provide the blinking without supply current
variations. You
> would still have short transients in the drive circuit, but these should
be much
> easier to filter.
>
> Agreed. You could also have a pair of LEDs and alternate which of them is
lit.
>
> Then, to reduce the impact on the PPS signals, the LED on/off could be
forced to
> be phase-shifted to the PPS.
>
> Cheers,
> Magnus
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[Mike Naruta AA8K]

On 05/17/2012 05:38 AM, Tom Holmes wrote:
> The LED current could also be switched with a very long rise/fall time so
> that there isn't any transient, in the abrupt sense of the word. Who's gonna
> see the difference?


In a group that has GPS synchronized clock hands?

HERESY!

:)

>
> Tom Holmes, N8ZM
> Tipp City, OH
> EM79
>
>

[Michael Blazer]

I always thought it was nice to have the pretty LEDs showing the power
supplies are working, but then you have to find the one that's not lit.
I've seen others that have a 'fail' indicator, but if the power supply
is dead, what powers the fail LED.

The B-1B test stations have an interface board with status LEDs behind a
smoked plexiglass door. One version of the CCA has the 90° LEDs facing
backwards.

Mike

On 5/15/2012 10:25 PM, Hal Murray wrote:
> richard-***@public.gmane.org said:
>> FWIW, the E1938A oscillator control board had a "happy light" LED that
>> flashed 1 time per second, and sure enough this corrupted the power supply
>> and affected some applications. We added a command to turn it off.
> Why should lights blink when they are happy?
>
> Your eye is real good at noticing blinking things. Why not use blinking for
> things that are broken and need attention?
>
> Of course, with a PPS, blinking is an obvious thing to do: 1 resistor, 1 LED,
> your eye does all the work.
>
> I built a converter from blink on happy to blink on sad. I've been happy
> with it.
>
>

[Hal Murray]

richard-***@public.gmane.org said:
> No it doesn't use a cheap crystal. It uses a *special* SC cut crystal. This
> crystal could very easily cost more than an OCXO crystal.

What's special about it?

I assume the cost-more aspect would be to allow an overall goodness factor competitive with an OCXO in the low power corner of the marketplace. It might be cheaper overall to use a good crystal and a uP to correct for temperature than provide the power to run the oven.

--------

The other area where a uP is useful is in an environment with high vibration. It can correct for acceleration as well as temperature. There were several good URLs mention on this list in the past year or two. The context was radar on helicopters. Helicopters are full of vibrations/accelerations. The numbers work out such that the frequency broadening due to vibration is interesting if your radar is looking for slowly moving things like people.

----------

Crazy question dept:

What do low cost rubidium oscillators do when vibrating? Is it dominated by the cleanup crystal?



--
These are my opinions. I hate spam.

[Bob Camp]

Hi

An OCXO crystal needs to be "good" only at one temperature. The crystal in an MCXO needs to do well over a wide range of temperatures. That complicates things quite a bit.

Bob

On Aug 30, 2012, at 12:22 AM, Hal Murray <hmurray-8cQiHa/C+6Go9G/***@public.gmane.org> wrote:

>
> richard-***@public.gmane.org said:
>> No it doesn't use a cheap crystal. It uses a *special* SC cut crystal. This
>> crystal could very easily cost more than an OCXO crystal.
>
> What's special about it?
>
> I assume the cost-more aspect would be to allow an overall goodness factor competitive with an OCXO in the low power corner of the marketplace. It might be cheaper overall to use a good crystal and a uP to correct for temperature than provide the power to run the oven.
>
> --------
>
> The other area where a uP is useful is in an environment with high vibration. It can correct for acceleration as well as temperature. There were several good URLs mention on this list in the past year or two. The context was radar on helicopters. Helicopters are full of vibrations/accelerations. The numbers work out such that the frequency broadening due to vibration is interesting if your radar is looking for slowly moving things like people.
>
> ----------
>
> Crazy question dept:
>
> What do low cost rubidium oscillators do when vibrating? Is it dominated by the cleanup crystal?
>
>
>
> --
> These are my opinions. I hate spam.
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[Jim Lux]

On 8/29/12 9:22 PM, Hal Murray wrote:
>
> richard-***@public.gmane.org said:
>> No it doesn't use a cheap crystal. It uses a *special* SC cut crystal. This
>> crystal could very easily cost more than an OCXO crystal.

http://www.q-tech.com/mcxo.html

>
> What's special about it?
Has to support the overtones properly. Not only does it have to be a
good oscillator crystal, it also has to be a good thermometer

>
> I assume the cost-more aspect would be to allow an overall goodness factor competitive with an OCXO in the low power corner of the marketplace. It might be cheaper overall to use a good crystal and a uP to correct for temperature than provide the power to run the oven.
>

Power consumption, size, etc. Also, faster startup time (no waiting for
an oven to stabilize)

> --------
>
> The other area where a uP is useful is in an environment with high vibration. It can correct for acceleration as well as temperature. There were several good URLs mention on this list in the past year or two. The context was radar on helicopters. Helicopters are full of vibrations/accelerations. The numbers work out such that the frequency broadening due to vibration is interesting if your radar is looking for slowly moving things like people.
>
> ----------
>
> Crazy question dept:
>
> What do low cost rubidium oscillators do when vibrating? Is it dominated by the cleanup crystal?
>
>
>

[Rick Karlquist]

Hal Murray wrote:
>
> richard-***@public.gmane.org said:
>> No it doesn't use a cheap crystal. It uses a *special* SC cut crystal.
>> This
>> crystal could very easily cost more than an OCXO crystal.
>
> What's special about it?

First, it has to have no activity dips over the full
operating temperature range. OCXO crystals only have to work
at the oven temperature. Activity dips, according to John Vig,
are the reason whey they don't use mode B to sense temperature.

Second, it has to be cut correctly so that the beat note between
the fundamental times 3 and 3rd overtone modes is a useful
indicator of temperature.


>
> I assume the cost-more aspect would be to allow an overall goodness factor
> competitive with an OCXO in the low power corner of the marketplace. It
> might be cheaper overall to use a good crystal and a uP to correct for
> temperature than provide the power to run the oven.

Again, the MCXO is not a poor man's OCXO. It tends to be used
in applications such as manpack radios where battery constraints
rule out ovens, regardless of cost.


>
> --------
>
> The other area where a uP is useful is in an environment with high
> vibration. It can correct for acceleration as well as temperature. There

I've never heard of this being done. Do you have a reference?


Rick Karlquist N6RK

[Dennis Ferguson]

On 30 Aug, 2012, at 13:14 , Rick Karlquist wrote:
>> The other area where a uP is useful is in an environment with high
>> vibration. It can correct for acceleration as well as temperature. There
>
> I've never heard of this being done. Do you have a reference?

I'm not sure how that would be done with a single crystal but I heard
a talk by David Allan about a (carefully oriented) array of 6 crystals
for which that was done. A Kalman filter which understood the physics
of acceleration effects was applied to the output of the 6 crystals
to produce a composite clock and, as a side effect, inertial navigation
information. This allowed the composite clock to be corrected for
g-effects as well as providing the same data that would be output by
a conventional, mechanical inertial navigation unit.

I think the target application was a drone aircraft, with the clock
output ending up at a GPS receiver while the inertial data was used
as a fallback if the GPS was jammed and as a sanity check to detect
GPS spoofing. This seemed like a nice one-stone-several-birds solution.
I have a copy of the powerpoint somewhere, but I've not seen this
written down anywhere else.

Dennis Ferguson

[S***@public.gmane.org]

There are some drawbacks to this type of SC-cut MCXO I would think, and it
could possibly be replaced by a much higher performance Symmetricom CSAC,
probably at a lower cost and higher availability:

* Q-tech MCXO is ITAR controlled, CSAC is not
* MCXO has 20ppb over temp stability, CSAC has 1ppb spec, typical units can
be much lower than that. Our GPSTCXO has 75ppb over temp, not much more
than the MCXO, but probably at 1/10th the cost.
* The G-sensitivity of CSAC is at least 50x better than the MCXO (its so
low, its very hard to measure)
* Aging of MCXO is much higher (order of magnitude)
* Symmetricom is a big player, Q-tech is relatively small and unknown
* I remember that there are patents on the MCXO held by FEI?
* Power consumption is very similar, future CSAC units will have much lower
power than the MCXO.

The MCXO does have lower phase noise, it's an SC-cut cyrstal after all. But
with CSAC's now becoming available from multiple sources, why use an MCXO?

bye,
Said




In a message dated 8/30/2012 10:35:56 Pacific Daylight Time,
richard-***@public.gmane.org writes:

First, it has to have no activity dips over the full
operating temperature range. OCXO crystals only have to work
at the oven temperature. Activity dips, according to John Vig,
are the reason whey they don't use mode B to sense temperature.

Second, it has to be cut correctly so that the beat note between
the fundamental times 3 and 3rd overtone modes is a useful
indicator of temperature.

[Bob Camp]

Hi

The original patents on the MCXO are government property. One of the Ft.
Monmouth guys came up with the fundamental / third overtone idea back in the
80's. Several (at least three) companies were licensed by the government to
make the part.

Bob

-----Original Message-----
From: time-nuts-bounces-***@public.gmane.org [mailto:time-nuts-bounces-***@public.gmane.org] On
Behalf Of SAIDJACK-***@public.gmane.org
Sent: Thursday, August 30, 2012 2:54 PM
To: richard-***@public.gmane.org; time-nuts-***@public.gmane.org
Subject: Re: [time-nuts] oscillators

There are some drawbacks to this type of SC-cut MCXO I would think, and it
could possibly be replaced by a much higher performance Symmetricom CSAC,
probably at a lower cost and higher availability:

* Q-tech MCXO is ITAR controlled, CSAC is not
* MCXO has 20ppb over temp stability, CSAC has 1ppb spec, typical units can
be much lower than that. Our GPSTCXO has 75ppb over temp, not much more
than the MCXO, but probably at 1/10th the cost.
* The G-sensitivity of CSAC is at least 50x better than the MCXO (its so
low, its very hard to measure)
* Aging of MCXO is much higher (order of magnitude)
* Symmetricom is a big player, Q-tech is relatively small and unknown
* I remember that there are patents on the MCXO held by FEI?
* Power consumption is very similar, future CSAC units will have much lower
power than the MCXO.

The MCXO does have lower phase noise, it's an SC-cut cyrstal after all. But
with CSAC's now becoming available from multiple sources, why use an MCXO?

bye,
Said




In a message dated 8/30/2012 10:35:56 Pacific Daylight Time,
richard-***@public.gmane.org writes:

First, it has to have no activity dips over the full
operating temperature range. OCXO crystals only have to work
at the oven temperature. Activity dips, according to John Vig,
are the reason whey they don't use mode B to sense temperature.

Second, it has to be cut correctly so that the beat note between
the fundamental times 3 and 3rd overtone modes is a useful
indicator of temperature.



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To unsubscribe, go to
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and follow the instructions there.

[Jim Lux]

On 8/30/12 12:37 PM, Bob Camp wrote:
> Hi
>
> The original patents on the MCXO are government property. One of the Ft.
> Monmouth guys came up with the fundamental / third overtone idea back in the
> 80's. Several (at least three) companies were licensed by the government to
> make the part.
>
>

Gotta be careful there..

A lot of times these days, the government doesn't own the patent, they
get a "government use" license. If it was a civil servant doing the
work, then, yes, government owns it, and anyone can use it. However, if
it was a contractor at a government facility, or developed under a
contract (particularly a university), then it might be much stickier.
If you wanted to build something to sell to the government, then getting
a license is easy. But for the general public, perhaps not.

Working at JPL, which is part of Cal Tech, on NASA's nickle, we're made
VERY aware of exactly who owns the fruits of our brains, and who gets to
use it. The Bayh Dole act has many unexpected consequences.


These days, a lot of the people working at government labs are not civil
servants, but are "Technical Support and Engineering Personnel". This
allows them to report a lower headcount of government employees.

[Bob Camp]

Hi

The guy(s) who did the original work were indeed full time DOD employees.

Bob

On Aug 30, 2012, at 8:11 PM, Jim Lux <jimlux-***@public.gmane.org> wrote:

> On 8/30/12 12:37 PM, Bob Camp wrote:
>> Hi
>>
>> The original patents on the MCXO are government property. One of the Ft.
>> Monmouth guys came up with the fundamental / third overtone idea back in the
>> 80's. Several (at least three) companies were licensed by the government to
>> make the part.
>>
>>
>
> Gotta be careful there..
>
> A lot of times these days, the government doesn't own the patent, they get a "government use" license. If it was a civil servant doing the work, then, yes, government owns it, and anyone can use it. However, if it was a contractor at a government facility, or developed under a contract (particularly a university), then it might be much stickier. If you wanted to build something to sell to the government, then getting a license is easy. But for the general public, perhaps not.
>
> Working at JPL, which is part of Cal Tech, on NASA's nickle, we're made VERY aware of exactly who owns the fruits of our brains, and who gets to use it. The Bayh Dole act has many unexpected consequences.
>
>
> These days, a lot of the people working at government labs are not civil servants, but are "Technical Support and Engineering Personnel". This allows them to report a lower headcount of government employees.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[jmfranke]

If a civil servant was the inventor, the government is assigned the rights
and no one can use it for other than government applications without a
license. At one time I helped license government patents to companies.

John

--------------------------------------------------
From: "Jim Lux" <jimlux-***@public.gmane.org>
Sent: Thursday, August 30, 2012 8:11 PM
To: <time-nuts-***@public.gmane.org>
Subject: Re: [time-nuts] oscillators

> On 8/30/12 12:37 PM, Bob Camp wrote:
>> Hi
>>
>> The original patents on the MCXO are government property. One of the Ft.
>> Monmouth guys came up with the fundamental / third overtone idea back in
>> the
>> 80's. Several (at least three) companies were licensed by the government
>> to
>> make the part.
>>
>>
>
> Gotta be careful there..
>
> A lot of times these days, the government doesn't own the patent, they get
> a "government use" license. If it was a civil servant doing the work,
> then, yes, government owns it, and anyone can use it. However, if it was
> a contractor at a government facility, or developed under a contract
> (particularly a university), then it might be much stickier. If you wanted
> to build something to sell to the government, then getting a license is
> easy. But for the general public, perhaps not.
>
> Working at JPL, which is part of Cal Tech, on NASA's nickle, we're made
> VERY aware of exactly who owns the fruits of our brains, and who gets to
> use it. The Bayh Dole act has many unexpected consequences.
>
>
> These days, a lot of the people working at government labs are not civil
> servants, but are "Technical Support and Engineering Personnel". This
> allows them to report a lower headcount of government employees.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[Bob Camp]

Hi

Indeed, at least three companies received licenses.

Bob

On Aug 30, 2012, at 10:14 PM, "jmfranke" <jmfranke-***@public.gmane.org> wrote:

> If a civil servant was the inventor, the government is assigned the rights and no one can use it for other than government applications without a license. At one time I helped license government patents to companies.
>
> John
>
> --------------------------------------------------
> From: "Jim Lux" <jimlux-***@public.gmane.org>
> Sent: Thursday, August 30, 2012 8:11 PM
> To: <time-nuts-***@public.gmane.org>
> Subject: Re: [time-nuts] oscillators
>
>> On 8/30/12 12:37 PM, Bob Camp wrote:
>>> Hi
>>>
>>> The original patents on the MCXO are government property. One of the Ft.
>>> Monmouth guys came up with the fundamental / third overtone idea back in the
>>> 80's. Several (at least three) companies were licensed by the government to
>>> make the part.
>>>
>>>
>>
>> Gotta be careful there..
>>
>> A lot of times these days, the government doesn't own the patent, they get a "government use" license. If it was a civil servant doing the work, then, yes, government owns it, and anyone can use it. However, if it was a contractor at a government facility, or developed under a contract (particularly a university), then it might be much stickier. If you wanted to build something to sell to the government, then getting a license is easy. But for the general public, perhaps not.
>>
>> Working at JPL, which is part of Cal Tech, on NASA's nickle, we're made VERY aware of exactly who owns the fruits of our brains, and who gets to use it. The Bayh Dole act has many unexpected consequences.
>>
>>
>> These days, a lot of the people working at government labs are not civil servants, but are "Technical Support and Engineering Personnel". This allows them to report a lower headcount of government employees.
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts-***@public.gmane.org
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[Javier Herrero]

El 30/08/2012 20:53, SAIDJACK-***@public.gmane.org escribió:
> There are some drawbacks to this type of SC-cut MCXO I would think, and it
> could possibly be replaced by a much higher performance Symmetricom CSAC,
> probably at a lower cost and higher availability:
>
> * Q-tech MCXO is ITAR controlled, CSAC is not
> * MCXO has 20ppb over temp stability, CSAC has 1ppb spec, typical units can
> be much lower than that. Our GPSTCXO has 75ppb over temp, not much more
> than the MCXO, but probably at 1/10th the cost.
> * The G-sensitivity of CSAC is at least 50x better than the MCXO (its so
> low, its very hard to measure)
> * Aging of MCXO is much higher (order of magnitude)
> * Symmetricom is a big player, Q-tech is relatively small and unknown
> * I remember that there are patents on the MCXO held by FEI?
> * Power consumption is very similar, future CSAC units will have much lower
> power than the MCXO.
>
> The MCXO does have lower phase noise, it's an SC-cut cyrstal after all. But
> with CSAC's now becoming available from multiple sources, why use an MCXO?
>
> bye,
> Said
>
As you say about G-sensitivity, let time pass until the CSAC is also
ITAR controlled ;) It will no take too much.

Regards,

Javier

[Hal Murray]

richard-***@public.gmane.org said:
>> The other area where a uP is useful is in an environment
>> with high vibration. It can correct for acceleration as well
>> as temperature.

> I've never heard of this being done. Do you have a reference?

This is probably the paper I was thinking of. Looks like I made up the uP
part. Sorry for the confusion. It's a fun read even if it doesn't mention
uP.

http://www.freqelec.com/oscillators/g-comp_qz_brfg_04-07.pdf

"g"- Compensated, Miniature,
High Performance Quartz
Crystal Oscillators

Frequency
Electronics Inc.
Hugo Fruehauf
hxf-***@public.gmane.org
April 2007


From:
http://www.febo.com/pipermail/time-nuts/2010-February/044414.html


--
These are my opinions. I hate spam.

[Hal Murray]

richard-***@public.gmane.org said:
> I have an Outback S-Lite tractor GPS with a serial port with NMEA. Is there
> ready-to-use software to read out in lat/long from this port? Maybe I can
> talk to it with hyperterminal and make it just keep sending lat/long once
> per second or something. Is there a command set?

NMEA is just text. Normally, they send a clump of "sentences" every second
so something as simple as hyperterminal should work. If you find something
that looks like lat/long, it probably is.


Some/most devices have a way to turn individual sentence types on/off.
That's usually a proprietary command so you will have to find a data sheet
for your specific device. (or just ignore/filter the stuff you don't want)


--
These are my opinions. I hate spam.

[Hal Murray]

richard-***@public.gmane.org said:
> I have an HP laptop with docking station and the docking station provides
> serial and parallel ports. The question is: are these "real" ports (just
> like built ins) or do they behave as USB dongle versions? One could easily
> imagine that the docking station did nothing more sophisticated that
> emulating a USB dongle, but then again, it does access the docking connector
> so there is some hope it connects directly to the bus.

I'll bet they are real.

You could look in the BIOS and/or count pins on the docking connector.

I have a Dell laptop with a similar setup. Linux thinks they are real. The
serial port is real enough to get good PPS results.


--
These are my opinions. I hate spam.

[Hal Murray]

> Forget about it. This is well beyond even the lunatic fringe of pulling.

So how far can I pull a crystal?

Does it depend upon the cut or anything that turns into price?


--
These are my opinions. I hate spam.

[Volker Esper]

If you need a very "clean" signal - what would mean, stable (and
accurate) you'll have to purchase one. There are manufacturers that do
the job for, say, 30 Dollars? if it is a normal cut. If you like to get
a crystal for a specific temperature to build your own oven (to achieve
a very stable frequency) you can use an "SC-cut" - what is propably much
more expensive.

Volker



Am 18.01.2013 01:16, schrieb Hal Murray:
>> Forget about it. This is well beyond even the lunatic fringe of pulling.
>
> So how far can I pull a crystal?
>
> Does it depend upon the cut or anything that turns into price?
>
>

[Volker Esper]

Here an example manufactorer in my country:
http://www.quarztechnik.com/eng/hochfrequentequarze.html

or
http://www.icmfg.com/


Am 18.01.2013 01:31, schrieb Volker Esper:
>
> If you need a very "clean" signal - what would mean, stable (and
> accurate) you'll have to purchase one. There are manufacturers that do
> the job for, say, 30 Dollars? if it is a normal cut. If you like to get
> a crystal for a specific temperature to build your own oven (to achieve
> a very stable frequency) you can use an "SC-cut" - what is propably much
> more expensive.
>
> Volker
>
>
>
> Am 18.01.2013 01:16, schrieb Hal Murray:
>>> Forget about it. This is well beyond even the lunatic fringe of pulling.
>>
>> So how far can I pull a crystal?
>>
>> Does it depend upon the cut or anything that turns into price?
>>
>>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

[Bob Camp]

Hi

You can always use a crystal as a capacitor in just about any oscillator circuit. The question becomes at what point does it stop doing anything other than behave like a capacitor.

The accurate way to figure this out is to know the motional capacitance of the crystal. From that and the C0 you can do some modeling and see what you get.

More simple answer - anything past about 0.1% is a bit silly even with an easy to pull crystal. If you have very modest goals, 0.3 or 0.4% is possible. If your goals are modest, a VCO might also do just as well.

Bob

On Jan 17, 2013, at 7:16 PM, Hal Murray <hmurray-8cQiHa/C+6Go9G/***@public.gmane.org> wrote:

>> Forget about it. This is well beyond even the lunatic fringe of pulling.
>
> So how far can I pull a crystal?
>
> Does it depend upon the cut or anything that turns into price?
>
>
> --
> These are my opinions. I hate spam.
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[Hal Murray]

> Can someone in the know clarify this?

I'm not in the know.

Several years ago, I found a short chunk of coax that the cable TV guys had
left on the ground. It included a piece of heavy wall shrink tubing. There
was a layer of sticky goop between the coax and the shrink tubing.


--
These are my opinions. I hate spam.

[David]

On Sat, 13 Apr 2013 14:07:05 -0700, Hal Murray
<hmurray-8cQiHa/C+6Go9G/***@public.gmane.org> wrote:

>> Can someone in the know clarify this?
>
>I'm not in the know.
>
>Several years ago, I found a short chunk of coax that the cable TV guys had
>left on the ground. It included a piece of heavy wall shrink tubing. There
>was a layer of sticky goop between the coax and the shrink tubing.

They make adhesive lined or dual wall heat shrink tubing for
applications requiring a better seal:

http://www.3m.com/product/information/Heat-Shrink-Adhesive-Lined-Tubing.html
http://www.buyheatshrink.com/heatshrinktubing/3to1adhesive.htm

[Peter Gottlieb]

Think of heat shrink with a layer of hot melt glue on the inside. Such stuff is
used in most outdoor and especially underground utility wiring. Shrink the
tubing and it melts the glue and the contracting tubing forces the glue into
every crevice making a great waterproof splice.


On 4/13/2013 5:07 PM, Hal Murray wrote:
>> Can someone in the know clarify this?
> I'm not in the know.
>
> Several years ago, I found a short chunk of coax that the cable TV guys had
> left on the ground. It included a piece of heavy wall shrink tubing. There
> was a layer of sticky goop between the coax and the shrink tubing.
>
>

[DaveH]

Kind of a cool technology -- they bombard the outside of the tube with an
electron beam that cross-links the polymer but leaves the inside untouched.
The outside becomes hard but still shrinks. The inside just melts into a
goo when heated.

Dave

> -----Original Message-----
> From: time-nuts-bounces-***@public.gmane.org
> [mailto:time-nuts-bounces-***@public.gmane.org] On Behalf Of Peter Gottlieb
> Sent: Saturday, April 13, 2013 15:24
> To: time-nuts-***@public.gmane.org
> Subject: Re: [time-nuts] Connectors
>
> Think of heat shrink with a layer of hot melt glue on the
> inside. Such stuff is
> used in most outdoor and especially underground utility
> wiring. Shrink the
> tubing and it melts the glue and the contracting tubing
> forces the glue into
> every crevice making a great waterproof splice.
>
>
> On 4/13/2013 5:07 PM, Hal Murray wrote:
> >> Can someone in the know clarify this?
> > I'm not in the know.
> >
> > Several years ago, I found a short chunk of coax that the
> cable TV guys had
> > left on the ground. It included a piece of heavy wall
> shrink tubing. There
> > was a layer of sticky goop between the coax and the shrink tubing.
> >
> >
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[Robert Atkinson]

Hi Dave,
Not quite, they do use irradiation crosslinking to make the heatshrink tube, but the hotmelt adhesive is a completly separate layer. They do different combinations of tube and glue for different applications. Really cool are the pre-forms that look like a parallel tube but shrink down into two sises with a smooth transition. The mold the final shape and then streach it (hot) into a parallel tube. They also do multiple entry versions. Raychem are leaders in this. They also do shrink metal parts.

Robert G8RPI.



________________________________
From: DaveH <info-7e6btGqTaFu1f5U2huucgCSYu/***@public.gmane.org>
To: nerd-H+***@public.gmane.org; 'Discussion of precise time and frequency measurement' <time-nuts-***@public.gmane.org>
Sent: Sunday, 14 April 2013, 3:08
Subject: Re: [time-nuts] Connectors


Kind of a cool technology -- they bombard the outside of the tube with an
electron beam that cross-links the polymer but leaves the inside untouched.
The outside becomes hard but still shrinks.  The inside just melts into a
goo when heated.

Dave

> -----Original Message-----
> From: time-nuts-bounces-***@public.gmane.org
> [mailto:time-nuts-bounces-***@public.gmane.org] On Behalf Of Peter Gottlieb
> Sent: Saturday, April 13, 2013 15:24
> To: time-nuts-***@public.gmane.org
> Subject: Re: [time-nuts] Connectors
>
> Think of heat shrink with a layer of hot melt glue on the
> inside. Such stuff is
> used in most outdoor and especially underground utility
> wiring.  Shrink the
> tubing and it melts the glue and the contracting tubing
> forces the glue into
> every crevice making a great waterproof splice.
>
>
> On 4/13/2013 5:07 PM, Hal Murray wrote:
> >> Can someone in the know clarify this?
> > I'm not in the know.
> >
> > Several years ago, I found a short chunk of coax that the
> cable TV guys had
> > left on the ground.  It included a piece of heavy wall
> shrink tubing.  There
> > was a layer of sticky goop between the coax and the shrink tubing.
> >
> >
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

_______________________________________________
time-nuts mailing list -- time-nuts-***@public.gmane.org
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[Didier]

Raychem invented that process 50 years ago with polyolefin. Now everybody makes it with all kinds of materials. If it had been invented by Disney, they would have copyrighted it instead of patented it and nobody else would make it :)
Didier


DaveH <info-7e6btGqTaFu1f5U2huucgCSYu/***@public.gmane.org> wrote:

>Kind of a cool technology -- they bombard the outside of the tube with
>an
>electron beam that cross-links the polymer but leaves the inside
>untouched.
>The outside becomes hard but still shrinks. The inside just melts into
>a
>goo when heated.
>
>Dave
>
>> -----Original Message-----
>> From: time-nuts-bounces-***@public.gmane.org
>> [mailto:time-nuts-bounces-***@public.gmane.org] On Behalf Of Peter Gottlieb
>> Sent: Saturday, April 13, 2013 15:24
>> To: time-nuts-***@public.gmane.org
>> Subject: Re: [time-nuts] Connectors
>>
>> Think of heat shrink with a layer of hot melt glue on the
>> inside. Such stuff is
>> used in most outdoor and especially underground utility
>> wiring. Shrink the
>> tubing and it melts the glue and the contracting tubing
>> forces the glue into
>> every crevice making a great waterproof splice.
>>
>>
>> On 4/13/2013 5:07 PM, Hal Murray wrote:
>> >> Can someone in the know clarify this?
>> > I'm not in the know.
>> >
>> > Several years ago, I found a short chunk of coax that the
>> cable TV guys had
>> > left on the ground. It included a piece of heavy wall
>> shrink tubing. There
>> > was a layer of sticky goop between the coax and the shrink tubing.
>> >
>> >
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts-***@public.gmane.org
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
>_______________________________________________
>time-nuts mailing list -- time-nuts-***@public.gmane.org
>To unsubscribe, go to
>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

--
Sent from my Nexus 7 tablet.

[Chris Albertson]

This stuff really does work. You heat it until the hot melt glue just
starts to be squeezed out the ends of the tube. There are two grades. The
best is a 4:1 shrink the cheaper kind is 3:1. It is really hard to remove
it is decide to take it apart later.

This is sold by WM. They are only a mile from my house so it is hard to
resist buying it there. Best quality bet not
cheap.<http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&storeId=11151&productId=35291&langId=-1#.UWrspb_pl4o>

Here is another source of it one
more<http://www.buyheatshrink.com/heatshrinktubing/4to1adhesive.htm>


On Sun, Apr 14, 2013 at 4:15 AM, Didier <shalimr9-***@public.gmane.org> wrote:

> Raychem invented that process 50 years ago with polyolefin. Now everybody
> makes it with all kinds of materials. If it had been invented by Disney,
> they would have copyrighted it instead of patented it and nobody else would
> make it :)
> Didier
>
>
> DaveH <info-7e6btGqTaFu1f5U2huucgCSYu/***@public.gmane.org> wrote:
>
> >Kind of a cool technology -- they bombard the outside of the tube with
> >an
> >electron beam that cross-links the polymer but leaves the inside
> >untouched.
> >The outside becomes hard but still shrinks. The inside just melts into
> >a
> >goo when heated.
> >
> >Dave
> >
> >> -----Original Message-----
> >> From: time-nuts-bounces-***@public.gmane.org
> >> [mailto:time-nuts-bounces-***@public.gmane.org] On Behalf Of Peter Gottlieb
> >> Sent: Saturday, April 13, 2013 15:24
> >> To: time-nuts-***@public.gmane.org
> >> Subject: Re: [time-nuts] Connectors
> >>
> >> Think of heat shrink with a layer of hot melt glue on the
> >> inside. Such stuff is
> >> used in most outdoor and especially underground utility
> >> wiring. Shrink the
> >> tubing and it melts the glue and the contracting tubing
> >> forces the glue into
> >> every crevice making a great waterproof splice.
> >>
> >>
> >> On 4/13/2013 5:07 PM, Hal Murray wrote:
> >> >> Can someone in the know clarify this?
> >> > I'm not in the know.
> >> >
> >> > Several years ago, I found a short chunk of coax that the
> >> cable TV guys had
> >> > left on the ground. It included a piece of heavy wall
> >> shrink tubing. There
> >> > was a layer of sticky goop between the coax and the shrink tubing.
> >> >
> >> >
> >>
> >> _______________________________________________
> >> time-nuts mailing list -- time-nuts-***@public.gmane.org
> >> To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >
> >_______________________________________________
> >time-nuts mailing list -- time-nuts-***@public.gmane.org
> >To unsubscribe, go to
> >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>
> --
> Sent from my Nexus 7 tablet.
> _______________________________________________
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>



--

Chris Albertson
Redondo Beach, California

[paul swed]

Yes its from the heat shrink.
When they shrink the wrap it forms an air proof seal.
Regards
Paul
WB8TSL


On Sat, Apr 13, 2013 at 5:07 PM, Hal Murray <hmurray-8cQiHa/C+6Go9G/***@public.gmane.org> wrote:

> > Can someone in the know clarify this?
>
> I'm not in the know.
>
> Several years ago, I found a short chunk of coax that the cable TV guys had
> left on the ground. It included a piece of heavy wall shrink tubing.
> There
> was a layer of sticky goop between the coax and the shrink tubing.
>
>
> --
> These are my opinions. I hate spam.
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

[Hal Murray]

richard-***@public.gmane.org said:
> Can anyone on the list point me to a true two channel counter that would
> just measure the two sources? We are working around 200 MHz, but could
> possibly prescale.

What level of accuracy do you need?

Could you feed both clocks and possibly a 3rd reference clock into a FPGA?


--
These are my opinions. I hate spam.

[Hal Murray]

> 1. There is a theoretical QF product for quartz. Being at 5 MHz basically
> doubles your Q, all other things being equal.

Doesn't that Q gain from the QF product go away if you have to PLL it up to
10 MHz or 100 MHz which is what you really want?

[I was about to ask why not go to 1 MHz, but Bob Camp answered that already.]

--
These are my opinions. I hate spam.

[Richard (Rick) Karlquist]

In a free running (non crystal controlled) oscillator,
the oscillator with the highest Q (regardless of frequency)
will have the best phase noise, if all oscillators are
normallized to the same frequency by ideal multiplication.
So the Q gain doesn't go away in that sense.

Having said that, in crystal oscillators, Q doesn't
determine noise in the first place, so the point is moot.

Rick Karlquist N6RK

On 11/1/2013 8:48 PM, Hal Murray wrote:
>
>> 1. There is a theoretical QF product for quartz. Being at 5 MHz basically
>> doubles your Q, all other things being equal.
>
> Doesn't that Q gain from the QF product go away if you have to PLL it up to
> 10 MHz or 100 MHz which is what you really want?
>
> [I was about to ask why not go to 1 MHz, but Bob Camp answered that already.]
>

[Hal Murray]

richard-***@public.gmane.org said:
> I want to use WWVB because I want to be able to mention to visitors that the
> clock links to an ensemble of 5071A cesium standards, and I was one of the
> designers of the 5071A, the actual atomic clock. ...

Neat.

What does the Air Force use as a reference for GPS? Maybe you need two
clocks. :)





--
These are my opinions. I hate spam.

[Clint Turner]

Other than WWVB-based frequency references/clocks that lock onto the 60
kHz carrier itself, I'm not aware of any WWVB-based clocks that were the
slightest-bit affected by format change (e.g. the addition of the
low-rate BPSK): Please point me to any references to the contrary if
you find them.

Co-incident with the WWVB format change there were a number of WWVB
clocks that quit working - namely, a few of the older "SkyScan" models,
but this had nothing at all to do with the format change, but rather an
error in the silicon that caused them to fail to automatically set
themselves (after initially doing so when first powered-up). For WWVB,
the timing of the manifestation of this bug was most unfortunate and
there is/was quite a bit of information on the net that continues to
propel this myth.

Being a bit of a nerd and Time Nut I went out of my way to determine the
actual cause of this problem.

There is this:

http://ka7oei.blogspot.com/2013/02/did-nist-break-bunch-of-radio.html

In this, I determined that at least with this receiver, its detection
bandwidth was far too wide to be adversely affected by the phase
reversal which - in theory - could skew the timing of the recovered
amplitude waveform of the time code modulation. From this I concluded
that the TRF receivers used by these inexpensive clocks weren't likely
to be affected in the least by the BPSK.

And secondly, there is this:

http://ka7oei.blogspot.com/2013/03/yes-nist-did-break-bunch-of-radio.html

In short, I created my own, local WWVB signal and demonstrated to my
satisfaction that the real problem with these particular clocks was that
they couldn't tolerate dates beyond a certain range. A shame, too,
since these same clocks will happily display UTC with no DST - although
they would sync at "Midnight" and early morning for their set time zone
which means that they would sync during daylight hours: Not a problem
here in Utah where we have mV/m signal levels, but it could be
disastrous for stations farther east where usable signals are available
only in the wee hours of the morning! (These clocks also had a bug that
would cause them to delay a day during the spring change onto DST -
disconcerting on the morning of the time change if it was set to local
time with DST!)

73,

Clint
KA7OEI


> Wouldn't that be nice!
>
> They implement a new format which destroys much of the installed
> infrastructure, then don't actually produce the 'better replacement'.
>
> How very LORAN!
>
> -John

[Hal Murray]

richard-***@public.gmane.org said:
> Solid dielectric cable and connectors of 3.5 mm size are mode limited to 18
> GHz. That is why there is so much stuff rated at 18 GHz as opposed to 16 or
> 20 GHz.

Thanks. That's what I was looking for.

Wiki says that SMA works to 18 GHz and the 3.5 mm is good for 34 GHz.
http://en.wikipedia.org/wiki/SMA_connector#Variations



--
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[Jim Lux]

On 2/26/14 12:44 AM, Hal Murray wrote:
>
> richard-***@public.gmane.org said:
>> Solid dielectric cable and connectors of 3.5 mm size are mode limited to 18
>> GHz. That is why there is so much stuff rated at 18 GHz as opposed to 16 or
>> 20 GHz.
>
> Thanks. That's what I was looking for.
>
> Wiki says that SMA works to 18 GHz and the 3.5 mm is good for 34 GHz.
> http://en.wikipedia.org/wiki/SMA_connector#Variations
>
>

And, as pointed out earlier, the market is smaller, so volumes are
smaller, and driving the price down from being able to change to truly
mass production is harder.

There's also a manufacturing tolerance issue. The higher you go, the
tighter the mechanical tolerances get. I suspect there is a huge amount
of tooling out there for SMA connectors and other things of that size
where the machining tolerances are "good enough" for SMA and 18GHz, but
not "good enough" for higher.

That drives all sorts of things.

THere's also semiconductor parts. Lots and lots of stuff in the under
12-13 GHz range that are inexpensive. A fair amount up to 18-ish, and
then it sort of falls off.

There, it's driven by market, which in turn is driven by international
allocations. DBS satellites at 12-13 GHz is a high volume market, so
there's lots of things like MMIC low noise amplifiers. Likewise
anything around 2.45 or 5.1-5.8 GHz. You see a big break in RF
equipment model capability at 3GHz and 6GHz, and I suspect that's driven
by the desire to test cellphones and wifi and BT (<3 GHz) and
802.11a/802.11n, WiMax, etc at <6GHz.

Parts that are cheap and easy to use lead to interesting products like
the SignalHound spectrum analyzer, but I don't expect to see a 50GHz
SignalHound any time soon. ($900 for 4.4 GHz, $2k for 12.4GHz). You
could probably *build* a front end converter for a signal hound fairly
inexpensively, but the parts for, say, 32 GHz would cost as much as the
Signal Hound backend.

[Bob Camp]

Hi

One of the more common explanations for the 18 GHz “upper limit” is that the broad water vapor absorption peak at about 23 GHz made systems less practical as you went up from 18. I suspect the same water issues make certain types of parts more difficult to fabricate.

Bob

On Feb 26, 2014, at 9:01 AM, Jim Lux <jimlux-***@public.gmane.org> wrote:

> On 2/26/14 12:44 AM, Hal Murray wrote:
>>
>> richard-***@public.gmane.org said:
>>> Solid dielectric cable and connectors of 3.5 mm size are mode limited to 18
>>> GHz. That is why there is so much stuff rated at 18 GHz as opposed to 16 or
>>> 20 GHz.
>>
>> Thanks. That's what I was looking for.
>>
>> Wiki says that SMA works to 18 GHz and the 3.5 mm is good for 34 GHz.
>> http://en.wikipedia.org/wiki/SMA_connector#Variations
>>
>>
>
> And, as pointed out earlier, the market is smaller, so volumes are smaller, and driving the price down from being able to change to truly mass production is harder.
>
> There's also a manufacturing tolerance issue. The higher you go, the tighter the mechanical tolerances get. I suspect there is a huge amount of tooling out there for SMA connectors and other things of that size where the machining tolerances are "good enough" for SMA and 18GHz, but not "good enough" for higher.
>
> That drives all sorts of things.
>
> THere's also semiconductor parts. Lots and lots of stuff in the under 12-13 GHz range that are inexpensive. A fair amount up to 18-ish, and then it sort of falls off.
>
> There, it's driven by market, which in turn is driven by international allocations. DBS satellites at 12-13 GHz is a high volume market, so there's lots of things like MMIC low noise amplifiers. Likewise anything around 2.45 or 5.1-5.8 GHz. You see a big break in RF equipment model capability at 3GHz and 6GHz, and I suspect that's driven by the desire to test cellphones and wifi and BT (<3 GHz) and 802.11a/802.11n, WiMax, etc at <6GHz.
>
> Parts that are cheap and easy to use lead to interesting products like the SignalHound spectrum analyzer, but I don't expect to see a 50GHz SignalHound any time soon. ($900 for 4.4 GHz, $2k for 12.4GHz). You could probably *build* a front end converter for a signal hound fairly inexpensively, but the parts for, say, 32 GHz would cost as much as the Signal Hound backend.
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[Hal Murray]

richard-***@public.gmane.org said:
> Still, there was no way to guarantee that a crystal in the future would
> never have a jump or sudden change in aging.

> What was really needed was an ensemble of oscillators, but that was not
> economically competitive with rubidium.

How many would you need? Is 3 enough?

How well could you do with several low(er) cost oscillators relative to one
good but expensive one? It might be an interesting experiment in a nutty
sort of way.



--
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[Richard (Rick) Karlquist]

On 4/11/2014 11:04 AM, Hal Murray wrote:

> How many would you need? Is 3 enough?
>
> How well could you do with several low(er) cost oscillators relative to one
> good but expensive one? It might be an interesting experiment in a nutty
> sort of way.
>

My guess would be 3 would be a minimum, so you
could have a majority vote. Len Cutler's group
actually built an experimental ensemble of 9 or
10, but it didn't seem to come to fruition.
For this to make any sense, you would need to be
able to cherry pick 9 or 10 really good oscillators.
However, there was no way to get the production
line to sign on to this.

David Allan had
this interesting concept to the effect that if
you had a sufficient number of wristwatches
(maybe 1000) and you averaged them together
you could somehow get a quality clock, or at
least 31.6 times better. Kind of like the
notion of 1000 monkeys with 1000 typewriters...

Rick

[bownes]

Interesting idea. It might be an interesting experiment to couple a large number of inexpensive xtals to see how it impacts effects such as sudden changes in a single xtal.

With sufficient monitoring of each one, you could even tune the coupling to amplify/attenuate the results of the 'good' and 'bad' ones over some interval.

Of course, what effect this has on things like phase noise, drift, and so on is a whole different matter.

Bob

> On Apr 11, 2014, at 14:14, "Richard (Rick) Karlquist" <richard-***@public.gmane.org> wrote:
>
>> On 4/11/2014 11:04 AM, Hal Murray wrote:
>>
>> How many would you need? Is 3 enough?
>>
>> How well could you do with several low(er) cost oscillators relative to one
>> good but expensive one? It might be an interesting experiment in a nutty
>> sort of way.
>
> My guess would be 3 would be a minimum, so you
> could have a majority vote. Len Cutler's group
> actually built an experimental ensemble of 9 or
> 10, but it didn't seem to come to fruition.
> For this to make any sense, you would need to be
> able to cherry pick 9 or 10 really good oscillators.
> However, there was no way to get the production
> line to sign on to this.
>
> David Allan had
> this interesting concept to the effect that if
> you had a sufficient number of wristwatches
> (maybe 1000) and you averaged them together
> you could somehow get a quality clock, or at
> least 31.6 times better. Kind of like the
> notion of 1000 monkeys with 1000 typewriters...
>
> Rick
> _______________________________________________
> time-nuts mailing list -- time-nuts-***@public.gmane.org
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

[Chris Albertson]

Look at what NTP does to select "good" clocks when it has many to choose
from. It does not simply average them.

It looks at the noise in each one and then sees which clocks have
overlapping error bars. It assumes that all good clocks have the same time
within limits of their precision. Then from the good clocks there is a
second level weeding out process then finally it does a weighted average of
the remainders where I think those with less jitter get more weight.

It would not be impossible to do this with 10MHz oscillators. Certainly a
simple average is not a good idea as a broken unit can pull the entire
average way down. I think you'd have to check reasonableness first and
eliminate outliers I think today you might simply digitize the signals
and figure out which were best using software.

In short the output is "ensemble time" (not "average time") but there is a
careful selection of who is allowed to be member of the ensemble.

I used a joke last week to explain to a class why we don't use averages,
with no other qualifications. The joke is "Bill Gates walks into a bar....
What's the average net worth of everyone in the bar? Maybe $250 million."

My point was that it is hard to describe a population that is not Gaussian
distributed. "Stuck" and jumping crystals are not Gaussian. You'd have to
detect the misbehaving devices.



David Allan had
> this interesting concept to the effect that if
> you had a sufficient number of wristwatches
> (maybe 1000) and you averaged them together
> you could somehow get a quality clock, or at
> least 31.6 times better. Kind of like the
> notion of 1000 monkeys with 1000 typewriters...
>
--

Chris Albertson
Redondo Beach, California

[Magnus Danielson]

On 11/04/14 21:38, Chris Albertson wrote:
> Look at what NTP does to select "good" clocks when it has many to choose
> from. It does not simply average them.
>
> It looks at the noise in each one and then sees which clocks have
> overlapping error bars. It assumes that all good clocks have the same time
> within limits of their precision. Then from the good clocks there is a
> second level weeding out process then finally it does a weighted average of
> the remainders where I think those with less jitter get more weight.
>
> It would not be impossible to do this with 10MHz oscillators. Certainly a
> simple average is not a good idea as a broken unit can pull the entire
> average way down. I think you'd have to check reasonableness first and
> eliminate outliers I think today you might simply digitize the signals
> and figure out which were best using software.
>
> In short the output is "ensemble time" (not "average time") but there is a
> careful selection of who is allowed to be member of the ensemble.

NTP uses the ensamble clock style that Dave Allan developed for the NBS
AT time-scale and originally programmed on a PDP-7. Applying this type
of phase-comparison, estimate stability, weighing and updating ensamble
stability should indeed be possible to do. You need three or more
clocks, but one of these can be the GPS when you have it.

Jim Gray pointed out that it is important to watch your data. At
NBS/NIST they started to see some 1/f⁴ noise on one of their standards.
They could not figure it out. Turned out that the cleaning-lady was
pushing the standard over the floor once a week in order to clean under
it. This systematic "noise" where not in their standard model, but they
learned.

A frequency jump on the crystal oscillator in a control-loop will be
tracked in eventually, so it will look more like a phase-spike than a
frequency jump. Atomic clock FLLs will however not track in the full
phase difference, at least not guaranteed to do.

> I used a joke last week to explain to a class why we don't use averages,
> with no other qualifications. The joke is "Bill Gates walks into a bar....
> What's the average net worth of everyone in the bar? Maybe $250 million."
>
> My point was that it is hard to describe a population that is not Gaussian
> distributed. "Stuck" and jumping crystals are not Gaussian. You'd have to
> detect the misbehaving devices.

Indeed.

Cheers,
Magnus
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[WarrenS]

Ulrich

Thanks for posting the reference.
Very interesting and useful. The clues they give sounds like enough
information to do the Smartclock loop control things that they talk about.

ws

***************************
Hi Brooke,

> HP had some way around SA that improved the timekeeping.

HP called it the "Smartclock Algorithm" and you can find some very basic
information about it here:

http://www.hpl.hp.com/hpjournal/96dec/dec96a9.pdf

I have been trying months to find a reference on how it REALLY works but it
seems that this is one of the better kept secrets of HP.

Best regards

Ulrich

[Hal Murray]

***@karlquist.com said:
> I used a CPLD in a 900 GHz (that's right 900 GHz) optical sampling scope
> timebase. It was great because you just write a 17 bit counter in VHDL and
> there it is. You don't have to know anything about building digital
> hardware any more (40 years of experience wasted). Nobody cares about look
> ahead carry, etc.

Is that really true? Or perhaps, what fraction of the digital design space
does it apply to?

How fast was your counter running? How fast would it run? Was it a simple
counter or was there enable/up/down/load type gating involved?

What would you have done if you needed to run a bit faster? Could you buy a
faster chip? How much more could you get with tricky logic?

I agree that modern tools and parts have allowed a lot more people to build
digital circuits.



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[Bob Camp]

Hi

> On Jun 5, 2015, at 11:19 PM, Hal Murray <***@megapathdsl.net> wrote:
>
>
> ***@karlquist.com said:
>> I used a CPLD in a 900 GHz (that's right 900 GHz) optical sampling scope
>> timebase. It was great because you just write a 17 bit counter in VHDL and
>> there it is. You don't have to know anything about building digital
>> hardware any more (40 years of experience wasted). Nobody cares about look
>> ahead carry, etc.
>
> Is that really true?

Yes, it’s really true.

> Or perhaps, what fraction of the digital design space
> does it apply to?

The portion that does not take the design directly to an ASIC. (at
least in industry). Essentially the only thing done with discrete logic
these days are minor i/o chores.

>
> How fast was your counter running?
> How fast would it run?

That depends entirely on which FPGA or CPLD you buy. An old 100 MHz part will not
go as fast as a 800 MHz part. In this case speed is the toggle rate on the counter.

> Was it a simple
> counter or was there enable/up/down/load type gating involved?
>
> What would you have done if you needed to run a bit faster?

Bought a faster FPGA or gone to an ASIC.

> Could you buy a
> faster chip?

For enough money there’s always a faster chip :)

> How much more could you get with tricky logic?

The days of “tricky logic” ( = stuff the software does not understand) are now
the days of “hand place (route) the gates in the FPGA”. It’s routing delay that
gets you before gate speed in most cases. The software routers have gotten
awfully good ….

>
> I agree that modern tools and parts have allowed a lot more people to build
> digital circuits.

They did that only after they had been allowing mass conversion of designs over
to silicon for about two decades. The tools you see today are nothing like what
you had to use in the early 1990’s.

The other thing that the design software has done is that it’s forced people to
face up to timing constraints. Just as in the semiconductor industry, there is now
a “process spec” that is used to constrain the design. If it passes when fully
constrained and checked, it will work in production. No more blue wires. No more
“oops!” re-spins on $20,000 pc boards.

Bob

>
>
>
> --
> These are my opinions. I hate spam.
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-***@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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[Attila Kinali]

On Sat, 6 Jun 2015 09:52:11 -0400
Bob Camp <***@n1k.org> wrote:

> > Was it a simple
> > counter or was there enable/up/down/load type gating involved?
> >
> > What would you have done if you needed to run a bit faster?
>
> Bought a faster FPGA or gone to an ASIC.
>
> > Could you buy a
> > faster chip?
>
> For enough money there’s always a faster chip :)

Even if it is OT, to give this a little economic perspective:
Today, an ASIC starts to be cheaper than an FPGA solution at production
volumes somewhere between 1000 and 10'000 pieces (in total).
If you have working (synchronous) VHDL code, going ASIC is pretty
straight forward and is mostly automatic. There are several fabs
in Europe and Asia that offer node sizes between 180nm and 35nm
for even very small runs and help you to convert your FPGA code
to proper ASIC designs.

A simple ASIC project is cheap enough, that some universities offer
courses where students (in a master course) design their own chips,
let them produce and measure their performance later, all cost covered
by the university. (If i remember correctly, the cost was around 10kUSD
per design and for 20 dies, half of them in QFP, half as nacked die)

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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[Bob Camp]

Hi

Last time I saw university multi project wafer prices, the cost was around $5K for a
run on a “not state of the art” fab process. That included absolutely nothing
in the way of design assistance. It was strictly “we fab what you told us to do”. The
“run date” for the chips was also a bit vague. They used space on other design runs, so
you got about a 3 month window on when your parts might run. Eventually you got back
a waffle pack with some die to go wire bond up.

Often the trick was to take the work of several students and put in on a single chip. The
*hope* was that nothing pathogenic happened in any of the designs to render the
whole thing useless.

The gotcha on ASIC’s os (of course) the running cost of this stuff. If you are using a bunch
of parts is’t not to bad. If not, the phone call every 4 years or so about “you need to
buy a new mask set for $XXX,XXX” gets a bit old. For a state of the art process add
at least one more X to that number.

Coming back to timing. Once you go to an ASIC, the ability to optimize for low
jitter / good ADEV (or whatever) comes into the picture. There is no reason why
there should be any worse performance on the ASIC than on any logic family
you can find. All of the previous caveats about phase noise floors go away. That’s
not to say that things like crosstalk between two pads that are 0.05 mm apart suddenly
vanishes. You still have to take care of the i/o part of the design.

Bob

> On Jun 6, 2015, at 1:49 PM, Attila Kinali <***@kinali.ch> wrote:
>
> On Sat, 6 Jun 2015 09:52:11 -0400
> Bob Camp <***@n1k.org> wrote:
>
>>> Was it a simple
>>> counter or was there enable/up/down/load type gating involved?
>>>
>>> What would you have done if you needed to run a bit faster?
>>
>> Bought a faster FPGA or gone to an ASIC.
>>
>>> Could you buy a
>>> faster chip?
>>
>> For enough money there’s always a faster chip :)
>
> Even if it is OT, to give this a little economic perspective:
> Today, an ASIC starts to be cheaper than an FPGA solution at production
> volumes somewhere between 1000 and 10'000 pieces (in total).
> If you have working (synchronous) VHDL code, going ASIC is pretty
> straight forward and is mostly automatic. There are several fabs
> in Europe and Asia that offer node sizes between 180nm and 35nm
> for even very small runs and help you to convert your FPGA code
> to proper ASIC designs.
>
> A simple ASIC project is cheap enough, that some universities offer
> courses where students (in a master course) design their own chips,
> let them produce and measure their performance later, all cost covered
> by the university. (If i remember correctly, the cost was around 10kUSD
> per design and for 20 dies, half of them in QFP, half as nacked die)
>
> 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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[David C. Partridge]

My reading so far of what's been said in this thread is that you might get good results using a CPLD/FPGA as a divider but ... .

Bruce pointed me to Rubiola's paper <http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf>, and while I'm sure the lambda divider is excellent, there's a definite problem of needing to re-square the output after every stage if you want a multi-stage design. This makes me wonder if you'd end up adding enough additional jitter/phase noise to more than counteract the benefit of the lambda divider (which produces a stepped triangle wave). TANSTAAFL seems to apply here.

My biggest concern is that if I build a multi-stage divider (*) using a single CPLD or FPGA, I could end up with cross-talk problems similar that encountered with multi-gate logic packages. I don't think it makes sense to use a CPLD if you need to use a separate package for each stage.

I'm also a bit concerned by Bob Camp's comment:

>they might get to -16x dbc/ Hz region. That compares to the -174 dbc / Hz you could expect under similar conditions with something like AC or faster CMOS

which suggests that it will be (at least 10dB) worse than my existing design :(

I guess that it might work if the output were re-synched to the input using external D-flops after the main grunt work is done in a CPLD/FPGA.

I'm also a bothered by the findings in <http://rubiola.org/pdf-articles/conference/2014-eftf-Noise-in-digital-components.pdf> which indicate that the lowest noise devices tested were the Altera Max 3000 series which Altera dsecribe as "Mature" so may be at risk of obsolescence

Thanks to all for the discussion to date.

(*) similar to my previous effort made with 74AC logic.

Thanks again
Dave

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[Bob Camp]

Hi

As always, the real answer is “that depends”.

If you are dividing to 1 pps from 10 MHz, the CPLD or FPGA is a fine answer to the question. It will give you some cool bells and whistles (like sync and advance / retard) without adding anything to the budget. If you wish to re-sync the output with a single gate D-FF running on the “wrong edge” of the 10 MHz, that’s easily done and it adds virtually nothing to the board space or cost.

If you are building a low noise PLL and going from 160 MHz down to a 40 MHz analog phase detector (with a floor of -170 dbc/ Hz), the CLPD or FPGA isn’t a good choice. You can do the complete divide with a single package part and get lower noise.

The board with the 160 MHz PLL on it is going to be a single purpose layout and it will live it’s life doing one thing. The board with the 1 pps
divider might get re-purposed to do a variety of things. A “universal” FPGA board with some basic timing stuff (connectors / re-sync flip flops / input gates) on it might be a very useful thing to have around …..

> On Jun 7, 2015, at 6:23 AM, David C. Partridge <***@perdrix.co.uk> wrote:
>
> My reading so far of what's been said in this thread is that you might get good results using a CPLD/FPGA as a divider but ... .
>
> Bruce pointed me to Rubiola's paper <http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf>, and while I'm sure the lambda divider is excellent, there's a definite problem of needing to re-square the output after every stage if you want a multi-stage design. This makes me wonder if you'd end up adding enough additional jitter/phase noise to more than counteract the benefit of the lambda divider (which produces a stepped triangle wave). TANSTAAFL seems to apply here.
>
> My biggest concern is that if I build a multi-stage divider (*) using a single CPLD or FPGA, I could end up with cross-talk problems similar that encountered with multi-gate logic packages.

Internal cross talk on FPGA’s and CPLD’s is pretty much a non-issue. That assumes that the board is properly laid out and the supplies are
well bypassed. Input and output cross talk can be reduced (but not always eliminated) by running differential inputs and putting “threat” signals on different i/o banks from each other.

The “properly laid out” constraint with a FPGA / CPLD forces you to a > 2 layer board pretty fast. Depending on the density and a few other things you may be past 6 layers. Yes that costs money.

Bob

> I don't think it makes sense to use a CPLD if you need to use a separate package for each stage.
>
> I'm also a bit concerned by Bob Camp's comment:
>
>> they might get to -16x dbc/ Hz region. That compares to the -174 dbc / Hz you could expect under similar conditions with something like AC or faster CMOS
>
> which suggests that it will be (at least 10dB) worse than my existing design :(
>
> I guess that it might work if the output were re-synched to the input using external D-flops after the main grunt work is done in a CPLD/FPGA.
>
> I'm also a bothered by the findings in <http://rubiola.org/pdf-articles/conference/2014-eftf-Noise-in-digital-components.pdf> which indicate that the lowest noise devices tested were the Altera Max 3000 series which Altera dsecribe as "Mature" so may be at risk of obsolescence
>
> Thanks to all for the discussion to date.
>
> (*) similar to my previous effort made with 74AC logic.
>
> Thanks again
> Dave
>
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[cfo]

On Sun, 07 Jun 2015 11:23:40 +0100, David C. Partridge wrote:

> My reading so far of what's been said in this thread is that you might
> get good results using a CPLD/FPGA as a divider but ... .
..
..
..
> Thanks again Dave

Is this going to be an "open source" project, or something you buy ?

CFO

--
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[David C. Partridge]

I'm up for either ... My thoughts are to try it out on a development board and if it works, maybe build a few for possible sale, and also release Gerbers and VHDL files.

Regards,
David Partridge
-----Original Message-----
From: time-nuts [mailto:time-nuts-***@febo.com] On Behalf Of cfo
Sent: 08 June 2015 15:09
To: time-***@febo.com
Subject: Re: [time-nuts] Using CPLD/FPGA or similar for frequency divider

On Sun, 07 Jun 2015 11:23:40 +0100, David C. Partridge wrote:

> My reading so far of what's been said in this thread is that you might
> get good results using a CPLD/FPGA as a divider but ... .
..
..
..
> Thanks again Dave

Is this going to be an "open source" project, or something you buy ?

CFO

--
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[cfo]

On Mon, 08 Jun 2015 16:27:26 +0100, David C. Partridge wrote:

> I'm up for either ... My thoughts are to try it out on a development
> board and if it works, maybe build a few for possible sale, and also
> release Gerbers and VHDL files.
>
> Regards,
> David Partridge

I have these cheap cards , that might be a nice start.

CPLD Altera EPM240 (make sure you get the blue board)
Ebay: 271520142479

Fpga (2 onboard PLL's) older Cyclone2 , but prob ok.
Ebay: 400630255386


Programmer:
Ebay: 200943750380

If they could be the heart of the system, then everybody could get
started cheap.

I'm using Quartus2 on Linux (Mint17) , works ok.
But Modelsim needs some extra libs to function.


CFO

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[Dan Watson]

This thread really makes me want to do an FPGA timing project. I have a
Papilio One on hand, which uses the Spartan 3E.

But what to do with it? It has to be something much more interesting than
what a PicDiv or simple logic can do to make it worth my time. Hmm...



Dan

On Mon, Jun 8, 2015 at 3:42 PM, cfo <***@luna.dyndns.dk> wrote:

> On Mon, 08 Jun 2015 16:27:26 +0100, David C. Partridge wrote:
>
> > I'm up for either ... My thoughts are to try it out on a development
> > board and if it works, maybe build a few for possible sale, and also
> > release Gerbers and VHDL files.
> >
> > Regards,
> > David Partridge
>
> I have these cheap cards , that might be a nice start.
>
> CPLD Altera EPM240 (make sure you get the blue board)
> Ebay: 271520142479
>
> Fpga (2 onboard PLL's) older Cyclone2 , but prob ok.
> Ebay: 400630255386
>
>
> Programmer:
> Ebay: 200943750380
>
> If they could be the heart of the system, then everybody could get
> started cheap.
>
> I'm using Quartus2 on Linux (Mint17) , works ok.
> But Modelsim needs some extra libs to function.
>
>
> CFO
>
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[Richard (Rick) Karlquist]

The counter only had to run at ~50 MHz, on account of our
mode locked laser ran at that frequency. I don't remember
what the CPLD was rated at.

Rick

On 6/5/2015 8:19 PM, Hal Murray wrote:
>
> ***@karlquist.com said:
>> I used a CPLD in a 900 GHz (that's right 900 GHz) optical sampling scope
>> timebase. It was great because you just write a 17 bit counter in VHDL and
>> there it is. You don't have to know anything about building digital
>> hardware any more (40 years of experience wasted). Nobody cares about look
>> ahead carry, etc.
>
> Is that really true? Or perhaps, what fraction of the digital design space
> does it apply to?
>
> How fast was your counter running? How fast would it run? Was it a simple
> counter or was there enable/up/down/load type gating involved?
>
> What would you have done if you needed to run a bit faster? Could you buy a
> faster chip? How much more could you get with tricky logic?
>
> I agree that modern tools and parts have allowed a lot more people to build
> digital circuits.
>
>
>
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[Bob Camp]

Hi

Here’s an example:

http://parts.arrow.com/item/detail/arrow-development-tools/bemicromax10#pg2e

https://www.altera.com/products/fpga/max-series/max-10/overview.highResolutionDisplay.html

There are other outfits that make similar parts that are at least as good. This is considered a
low end chip right now. The part on the demo board is a mid point for the part size wise.

It will run 400 MHz clocks without much bother at all. It also is quite happy doing multiple modulo
divides to take those clocks down to multiple 1 pps outputs *and* have a load function on the
counter. You have enough room to use them as time tags on inputs to the FPGA and store a few
hours worth of data in memory.

Can you do better with a faster part? sure can. Can you find cheaper parts? yes again. Is there
a competitor’s part that will do it cheaper / faster / easier (pick one) - most certainly.

If you can enter a schematic into free software, you can design a pps divider with a part like this.
No need to learn a programming language to work with one. The process is roughly the same as
learning a new pcb layout tool. Yes it runs on Linux and on Windows.

I can’t buy the parts on the demo board for what they sell the board for. I can’t buy an 8 -10
layer board that size in single piece for what they sell the demo board for. I can’t get it assembled
(BGA’s …) in one piece for what they sell the demo board for. I also can’t do multiples
of that counter with discrete logic on a board that size. I also can’t buy all the chips that a
counter that fast going that low would require (plus the board) for what the demo board
costs. Bottom line, to use them, just buy them already on a board and mount that on
whatever you are doing.

No I’m not trying to sell you that demo board. I’m also not trying to convince you that there is one
and only one family of parts that are worth using. The point is - the world started going over to
FPGA’s in the mid 1980’s. Discrete logic design started to die out with ASIC’s in the early 1970’s.
For large scale stuff it was dead by the end of the 1970’s. Forty years later, there are very few
places (other than i/o) that discrete gates get used.

The world has changed a lot since the 1970’s. Design any UART’s with discrete logic since about 1971?

Bob

> On Jun 5, 2015, at 11:19 PM, Hal Murray <***@megapathdsl.net> wrote:
>
>
> ***@karlquist.com said:
>> I used a CPLD in a 900 GHz (that's right 900 GHz) optical sampling scope
>> timebase. It was great because you just write a 17 bit counter in VHDL and
>> there it is. You don't have to know anything about building digital
>> hardware any more (40 years of experience wasted). Nobody cares about look
>> ahead carry, etc.
>
> Is that really true? Or perhaps, what fraction of the digital design space
> does it apply to?
>
> How fast was your counter running? How fast would it run? Was it a simple
> counter or was there enable/up/down/load type gating involved?
>
> What would you have done if you needed to run a bit faster? Could you buy a
> faster chip? How much more could you get with tricky logic?
>
> I agree that modern tools and parts have allowed a lot more people to build
> digital circuits.
>
>
>
> --
> These are my opinions. I hate spam.
>
>
>
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[Hal Murray]

***@karlquist.com said:
> Can someone explain to me how this is going to work in light of the fact that
> each clock is in a different gravitational field?

They just shift from measuring time to measuring gravity. :)

Time too good to be true
By Daniel Kleppner
March 2006
http://scitation.aip.org/content/aip/magazine/physicstoday/article/59/3/10.1063/1.2195297

----------

Speaking of gravity...

A few weeks ago, I went to a talk on LIGO. If you ever get a chance to hear David Reitze, grab it. He's good. He's got a talk on YouTube, but it's several years old.

These are the guys trying to detect gravity waves. If you think time-nuts are nutty...

They are looking for the chirp as a pair of neutron stars or black holes spiral into each other. Their signal is in the ballpark of 1 kHz. Their typical frequency plot is full of spurs.

During the talk, he said their laser was stable to 1E-23
That caught my attention. After the talk I asked. The response was roughly: "That's only for a few seconds. At DC it wanders all over the place."

Their resonator is 4 km long.


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[Hal Murray]

***@karlquist.com said:
> The 2N5179 in the 10811 is selected for minimum beta and Ft at 20 mA, which
> is the start up condition due to the ALC being at full gain. It has a
> special HP part number, so you wouldn't know this just looking at the parts
> list.

How much of a difference does that selection step make?

I'd expect the parts within a batch to be very similar, more so for mature
parts.


--
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[Richard (Rick) Karlquist]

On 10/28/2015 10:38 AM, Hal Murray wrote:
>
> ***@karlquist.com said:
>> The 2N5179 in the 10811 is selected for minimum beta and Ft at 20 mA, which
>> is the start up condition due to the ALC being at full gain. It has a
>> special HP part number, so you wouldn't know this just looking at the parts
>> list.
>
> How much of a difference does that selection step make?
>
> I'd expect the parts within a batch to be very similar, more so for mature
> parts.
>
>

All I can tell you is that Burgoon found a non-zero number of
2N5179's that wouldn't start. Knowing the way things were done,
he probably got a response from the vendor to the effect that
it was simply an unspecified parameter and they only guarantee
JEDEC specs and the transistor(s) he found were not a fluke.
HP greatly discouraged the batch qualification paradigm, although
the did resort to it when justified. It was not justified for
the 10811.

Rick
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[KA2WEU--- via time-nuts]

This oscillator seems to have been more a frequency standard then a noise
standard. Today's 10 MHz oscillators are different/better, such a crystal is
no longer available/made.

I have more experience with 100 MHz, 125 and 128 MHz. Once I am back in the
USA I will send some measured results and comments.

Thank for this reference :

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf

Ulrich


In a message dated 10/28/2015 7:01:16 P.M. W. Europe Standard Time,
***@megapathdsl.net writes:


***@karlquist.com said:
> The 2N5179 in the 10811 is selected for minimum beta and Ft at 20 mA,
which
> is the start up condition due to the ALC being at full gain. It has a
> special HP part number, so you wouldn't know this just looking at the
parts
> list.

How much of a difference does that selection step make?

I'd expect the parts within a batch to be very similar, more so for mature

parts.


--
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[Gerhard Hoffmann]

Am 28.10.2015 um 19:22 schrieb KA2WEU--- via time-nuts:
> This oscillator seems to have been more a frequency standard then a noise
> standard. Today's 10 MHz oscillators are different/better, such a crystal is
> no longer available/made.
>
Yes. Rubiola gives it the credit of being able to be mass-produced, and
it _was_
one successful product. There is a section in "hacking oscillators" on it;
my copy of the book is 200 miles away right now.

regards,

Gerhard, DK4XP


(see www.rubiola.org)
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[Richard (Rick) Karlquist]

Do you have a specific URL for "hacking oscillators"? I can't
find it on Rubiola's web site.

Rick

On 10/28/2015 1:32 PM, Gerhard Hoffmann wrote:
> Am 28.10.2015 um 19:22 schrieb KA2WEU--- via time-nuts:
>> This oscillator seems to have been more a frequency standard then a noise
>> standard. Today's 10 MHz oscillators are different/better, such a
>> crystal is
>> no longer available/made.
> Yes. Rubiola gives it the credit of being able to be mass-produced, and
> it _was_
> one successful product. There is a section in "hacking oscillators" on it;
> my copy of the book is 200 miles away right now.
>
> regards,
>
> Gerhard, DK4XP
>
>
> (see www.rubiola.org)
> _______________________________________________
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[Gerhard Hoffmann]

Am 28.10.2015 um 23:04 schrieb Richard (Rick) Karlquist:
> Do you have a specific URL for "hacking oscillators"? I can't
> find it on Rubiola's web site.
It is a chapter in his book where he analyzes the form of the noise spectra.
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[Mod Mix]

6 - Oscillator hacking pp. 150-191 -
http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511812798&cid=CBO9780511812798A053
2 Oscillator hacking - http://arxiv.org/pdf/physics/0502143.pdf
A weird example; The effect of the output buffer; Oscillator hacking -
http://rubiola.org/pdf-slides/2009T-MPQ-Short-course-on-stable-oscillators.pdf

hth
Ulli

Am 28.10.2015 um 23:04 schrieb Richard (Rick) Karlquist:
> Do you have a specific URL for "hacking oscillators"? I can't
> find it on Rubiola's web site.
>
> Rick

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[Magnus Danielson]

It's chapter 6 in his phase noise book.

Cheers,
Magnus

On 10/28/2015 11:04 PM, Richard (Rick) Karlquist wrote:
> Do you have a specific URL for "hacking oscillators"? I can't
> find it on Rubiola's web site.
>
> Rick
>
> On 10/28/2015 1:32 PM, Gerhard Hoffmann wrote:
>> Am 28.10.2015 um 19:22 schrieb KA2WEU--- via time-nuts:
>>> This oscillator seems to have been more a frequency standard then a
>>> noise
>>> standard. Today's 10 MHz oscillators are different/better, such a
>>> crystal is
>>> no longer available/made.
>> Yes. Rubiola gives it the credit of being able to be mass-produced, and
>> it _was_
>> one successful product. There is a section in "hacking oscillators" on
>> it;
>> my copy of the book is 200 miles away right now.
>>
>> regards,
>>
>> Gerhard, DK4XP
>>
>>
>> (see www.rubiola.org)
>> _______________________________________________
> _______________________________________________
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[Adrian]

That's chapter 6 of his book.
http://rubiola.org/indexx-oscillator-noise.html
Just scroll down for the phase noise plots.
The left hand column of plots contains the essentials.

Adrian



Richard (Rick) Karlquist schrieb:
> Do you have a specific URL for "hacking oscillators"? I can't
> find it on Rubiola's web site.
>
> Rick
>
> On 10/28/2015 1:32 PM, Gerhard Hoffmann wrote:
>> Am 28.10.2015 um 19:22 schrieb KA2WEU--- via time-nuts:
>>> This oscillator seems to have been more a frequency standard then a
>>> noise
>>> standard. Today's 10 MHz oscillators are different/better, such a
>>> crystal is
>>> no longer available/made.
>> Yes. Rubiola gives it the credit of being able to be mass-produced, and
>> it _was_
>> one successful product. There is a section in "hacking oscillators"
>> on it;
>> my copy of the book is 200 miles away right now.
>>
>> regards,
>>
>> Gerhard, DK4XP
>>
>>
>> (see www.rubiola.org)
>> _______________________________________________
> _______________________________________________
> time-nuts mailing list -- time-***@febo.com
> To unsubscribe, go to
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[Jim Lux]

On 10/28/15 4:29 PM, Adrian wrote:
> That's chapter 6 of his book.
> http://rubiola.org/indexx-oscillator-noise.html
> Just scroll down for the phase noise plots.
> The left hand column of plots contains the essentials.
>
> Adrian
>
>
>

what would be nice is some similar simple analysis for lower performing
oscillators.. (like the oscillator in a PC, or run of the mill 1-10 ppm
TCXOs)


tvb has some on his website.

I guess there's stuff around, but it's not all gathered together.


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[Alexander Pummer]

Hi Rick,
any info on how Wenzel makes that low noise oscillators?
73
KJ6UHN
Alex

On 10/28/2015 3:04 PM, Richard (Rick) Karlquist wrote:
> Do you have a specific URL for "hacking oscillators"? I can't
> find it on Rubiola's web site.
>
> Rick
>
> On 10/28/2015 1:32 PM, Gerhard Hoffmann wrote:
>> Am 28.10.2015 um 19:22 schrieb KA2WEU--- via time-nuts:
>>> This oscillator seems to have been more a frequency standard then a
>>> noise
>>> standard. Today's 10 MHz oscillators are different/better, such a
>>> crystal is
>>> no longer available/made.
>> Yes. Rubiola gives it the credit of being able to be mass-produced, and
>> it _was_
>> one successful product. There is a section in "hacking oscillators"
>> on it;
>> my copy of the book is 200 miles away right now.
>>
>> regards,
>>
>> Gerhard, DK4XP
>>
>>
>> (see www.rubiola.org)
>> _______________________________________________
> _______________________________________________
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>
> -----
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> 10/28/15

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[Bob Camp]

Hi

They do it pretty much the same way everybody else makes the same
sort of oscillators. Design, build, tune / select, test, re-tune/ select, re-test.
The amount of test / tune depends enormously on what level of oscillator
is being made. > 80% of the volume shipped gets relatively less effort than
the other 20%.

Bob

> On Oct 28, 2015, at 6:24 PM, Alexander Pummer <***@ieee.org> wrote:
>
> Hi Rick,
> any info on how Wenzel makes that low noise oscillators?
> 73
> KJ6UHN
> Alex
>
> On 10/28/2015 3:04 PM, Richard (Rick) Karlquist wrote:
>> Do you have a specific URL for "hacking oscillators"? I can't
>> find it on Rubiola's web site.
>>
>> Rick
>>
>> On 10/28/2015 1:32 PM, Gerhard Hoffmann wrote:
>>> Am 28.10.2015 um 19:22 schrieb KA2WEU--- via time-nuts:
>>>> This oscillator seems to have been more a frequency standard then a noise
>>>> standard. Today's 10 MHz oscillators are different/better, such a
>>>> crystal is
>>>> no longer available/made.
>>> Yes. Rubiola gives it the credit of being able to be mass-produced, and
>>> it _was_
>>> one successful product. There is a section in "hacking oscillators" on it;
>>> my copy of the book is 200 miles away right now.
>>>
>>> regards,
>>>
>>> Gerhard, DK4XP
>>>
>>>
>>> (see www.rubiola.org)
>>> _______________________________________________
>> _______________________________________________
>> time-nuts mailing list -- time-***@febo.com
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>> and follow the instructions there.
>>
>>
>> -----
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>> Checked by AVG - www.avg.com
>> Version: 2016.0.7163 / Virus Database: 4457/10906 - Release Date: 10/28/15
>
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[KA2WEU--- via time-nuts]

Yes, more the termination .... Ulrich


In a message dated 10/28/2015 9:02:56 P.M. W. Europe Standard Time,
***@rubidium.dyndns.org writes:

Hi,

It is well worth mentioning that a crystal filter on the output can
become a challenge, as the source impedance can be far from 50 Ohm, and
thus a bit of a challenge depending on how you measure.

Cheers,
Magnus

On 10/28/2015 06:11 AM, Bruce Griffiths wrote:
> Ulrich
>
> Surely you meant to write
>
> PN(SSB) = -177 -Pout + NF
>
> If we attempt to apply this equation to the 10811A for which you
measured a PN floor of -174dBc/Hz
> this implies that
>
> NF - Pout = 3dB
>
> Best case (NF = 0dB - unlikely! Pout would need to be much higher for
nonn zero NF)
>
> Pout =-3dBm or 500uW.
>
> The question is identifying this power.
> The crystal dissipation is 50uW (HP Journal March 1981 p24)
> The signal power dissipated in the CB stage input R is around 10% of
this or about 5uW.
>
> The answer to this conundrum is surely that the equation for PN doesn't
apply directly in this case
> for offset frequencies outside the crystal bandwidth.
> The Crystal actually bandpass filters the signal and PN noise generated
by oscillator.
> For offset frequencies outside the crystal bandwidth the oscillator
generated PN is greatly attenuated
> so that the noise of the buffer amplifier chain (CB stage plus output
amplifiers) dominates.
> In calculating the noise floor of the buffer amplifier chain the fact
that the crystal has
> a high impedance at these frequencies should be taken into account.
>
> Bruce
>
>
> On Wednesday, 28 October 2015 8:34 AM, "***@aol.com"
<***@aol.com> wrote:
>
>
> I have bought and measured the hp10811 at about -174dBc/Hz. The
interesting thing is the feedback capacitor from collector to base which
changes Rin=1/gm. Unless the circuit has a hidden Q mulitplier the PN (SSB) can
never be better then 177 (kT) in dBm + Pout in dBm - NF of the oscillator
transistor. Many of the GB stages are potentially unstable , so the
"hopeful' best PN (SSB) is 177dbm + Pout ! AT 100 Mhz the leaing values are
-146/100Hz offset and - 183 far out and high crystal dissipation, 2mW or so
Ulrich In a message dated 10/27/2015 4:17:16 P.M. W. Europe Standard Time,
***@xtra.co.nz writes:
> As Rick has pointed out numerous times when the output signal is
extracted via the crystal by a CB stage (or cascade thereof) the PN floor is
determined by the ratio of the amplifier equivalent input noise current to the
crystal current. That is the amplifier equivalent input noise current at
frequencies for which the crystal impedance is high. If one neglects this
crucial point one comes to the conclusion (e.g. see Eq 4.-1 page 274 of Ulrich
Rohde's: Microwave and Wireless Synthesisers Theory and Design.) that with
a crystal current of 1.4mA rms and a crystal esr of 50 ohms that the XO PN
floor cannot be lower than -154dBc/Hz. Even the XO circuit in the ARRL
handbook (attributed to Ulrich) using this method of signal extraction has a
measured PN floor of -168dBc/Hz. Many other XO's (including the 10811A
which uses a crystal current of 1mA ) have an actual PN significantly lower
than this. One would have thought that this glaring discrepancy between
"theory" and practice
would
> have been noticed and corrected by now.
> Bruce
>
>
> On Tuesday, 27 October 2015 6:01 PM, Richard (Rick) Karlquist
<***@karlquist.com> wrote:
>
>
> The oscillator transistor and buffer amplifier are basically
> the same as the HP 10811, except for the absence of mode
> suppressors. The difference here is that the oscillator
> self limits in the oscillator transistor, whereas the 10811
> has ALC. The discontinuous operation of the transistor,
> as explained by Driscoll some 45 years ago, is undesirable
> because it increases the load resistance the crystal sees.
> The 2 transistor "Driscoll oscillator" fixes this problem
> by using an additional stage that limits instead of the
> oscillator transistor. This has been widely used for
> decades. It is interesting to note that the 10811 ALC
> works by varying the DC bias current in the oscillator
> transistor. This is in contrast to the elaborate DC
> bias current stabilization here.
>
> I have demonstrated that the close in phase noise in
> the 10811 is entirely due to the flicker noise of the
> crystal. The only place where the 10811 circuit comes
> into play is beyond 1 kHz from the carrier, where the
> Burgoon patent circuit (which apparently has prior art
> from Ulrich Rhode) reduces the phase noise floor. I
> have built two different oscillator circuits for 10811
> crystals and have measured the flicker noise as being
> the same as the intrinsic noise of the crystal.
>
> Thus, obsessing over noise in oscillators circuits may
> be overkill, unless you are planning to use a much
> better crystal (BVA, etc). OTOH, it might be advantageous
> to improve the reverse isolation by adding additional
> grounded base buffer stages. There are various NBS/NIST
> papers where several grounded base stages are cascaded.
> I did this in the HP 10816 rubidium standard.
>
> It is good to see time-nuts learning about oscillator
> circuit by building them.
>
> Rick Karlquist N6RK
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[Hal Murray]

***@karlquist.com said:
> If you replaced the thermistor with an exact replacement, then you shouldn't
> need to change the pot. ...

How repeatable are thermistors? How close do you need/want to get the
temperature?


--
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[Nigel Vander Houwen]

Hal,

It depends a lot on the thermistor. As with any component, there are higher precision models that would be pretty repeatable within a model number, and cheaper ones that will be somewhat less repeatable. In this case I didn’t have a specific model number, nor specific nominal/beta values, so I chose a reasonable 100K NTC thermistor, and am adjusting for that.

Nigel

> On Feb 27, 2016, at 20:21, Hal Murray <***@megapathdsl.net> wrote:
>
>
> ***@karlquist.com said:
>> If you replaced the thermistor with an exact replacement, then you shouldn't
>> need to change the pot. ...
>
> How repeatable are thermistors? How close do you need/want to get the
> temperature?
>
>
> --
> These are my opinions. I hate spam.
>
>
>
> _______________________________________________
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[Bob Camp]

Hi

Thermistors are often spec’d in terms of a tolerance on a value at a calibration temperature and a
tolerance on a value for “beta” that goes into the standard thermistor R/T calculation. Typical parts
are calibrated at something like 25C and you might get 1 or 2% at that point if you spend enough
money. With a normal tolerance on beta, that 1 or 2% becomes a small part of the tolerance by the time
you get past 40C.

Can you get a large batch calibrated at a higher temperature? Sure you can. They already are expensive
parts and when you put an adder on top of that … the finance guys math goes tilt. If you need a very
accurate number, the old style approaches were to turn hunt the oven or to measure the value of the part
in a “local standard temperature of 95C” oil bath.

Pretty much nobody does an OCXO either of those ways anymore. It’s all automated and uses a couple
of measurements to set the part to best measured temperature performance. At some point in the performance
equation, you don’t do anything more than take a guess at oven temperature and things work “good enough”
for that spec.

Bob



> On Feb 27, 2016, at 11:21 PM, Hal Murray <***@megapathdsl.net> wrote:
>
>
> ***@karlquist.com said:
>> If you replaced the thermistor with an exact replacement, then you shouldn't
>> need to change the pot. ...
>
> How repeatable are thermistors? How close do you need/want to get the
> temperature?
>
>
> --
> These are my opinions. I hate spam.
>
>
>
> _______________________________________________
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[Hal Murray]

***@karlquist.com said:
> Also in 1996, phase microsteppers were already legacy technology and didn't
> have a good reputation for spectral purity. Another non-panacea.

What is a phase microstepper and/or how does it compare to a DDS?

(Google gets lots of hits, but they all refer to motors.)


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[Anders Wallin]

> ***@karlquist.com said:
> > Also in 1996, phase microsteppers were already legacy technology and
> didn't
> > have a good reputation for spectral purity. Another non-panacea.
>
> What is a phase microstepper and/or how does it compare to a DDS?
>
> (Google gets lots of hits, but they all refer to motors.)
>


H-maser aging is typically compensated by something like
spectratime femto-stepper
http://www.spectratime.com/products/itest/clock-instruments/FemtoStepper/
microsemi AOG
http://www.microsemi.com/products/timing-synchronization-systems/time-frequency-references/active-hydrogen-maser/aog-110
(there are probably others, please post if you know about them!)

afaik they contain a OCXO/BVA that is steered based on a DMTD measurement
against the input reference.


AW
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[Bruce Griffiths]

No, the first one merely uses a pair of cascaded heterodyne PLLs as shown on p3 of the manual.A diophantine setup may be useful here if one wished to construct something similar.

Bruce


From: Anders Wallin <***@gmail.com>
To: Discussion of precise time and frequency measurement <time-***@febo.com>
Sent: Friday, 22 July 2016 7:49 PM
Subject: Re: [time-nuts] NCOCXO anyone?

> ***@karlquist.com said:
> > Also in 1996, phase microsteppers were already legacy technology and
> didn't
> > have a good reputation for spectral purity.  Another non-panacea.
>
> What is a phase microstepper and/or how does it compare to a DDS?
>
> (Google gets lots of hits, but they all refer to motors.)
>


H-maser aging is typically compensated by something like
spectratime femto-stepper
http://www.spectratime.com/products/itest/clock-instruments/FemtoStepper/
microsemi AOG
http://www.microsemi.com/products/timing-synchronization-systems/time-frequency-references/active-hydrogen-maser/aog-110
(there are probably others, please post if you know about them!)

afaik they contain a OCXO/BVA that is steered based on a DMTD measurement
against the input reference.


AW
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[Ole Petter Rønningen]

SpectraDynamics HROG 5/10

http://www.spectradynamics.com/products/hrog-10-high-resolution-phase-and-frequency-offset-generator/

On 22. jul. 2016, at 09.49, Anders Wallin <***@gmail.com> wrote:

>> ***@karlquist.com said:
>>> Also in 1996, phase microsteppers were already legacy technology and
>> didn't
>>> have a good reputation for spectral purity. Another non-panacea.
>>
>> What is a phase microstepper and/or how does it compare to a DDS?
>>
>> (Google gets lots of hits, but they all refer to motors.)
>
>
> H-maser aging is typically compensated by something like
> spectratime femto-stepper
> http://www.spectratime.com/products/itest/clock-instruments/FemtoStepper/
> microsemi AOG
> http://www.microsemi.com/products/timing-synchronization-systems/time-frequency-references/active-hydrogen-maser/aog-110
> (there are probably others, please post if you know about them!)
>
> afaik they contain a OCXO/BVA that is steered based on a DMTD measurement
> against the input reference.
>
>
> AW
> _______________________________________________
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[Hal Murray]

***@karlquist.com said:
> That's what we tried to do with the E1938A. A multiplying DAC is used based
> on a reference that is ovenized instead the crystal oven. That certainly
> eliminated the tempco issue with the reference, but then we discovered 1/f
> noise on the reference. We had to redesign with a different reference.

That still leaves the temperature quirks of the DAC and amplifiers.

Has anybody put the DAC and all of the analog stuff inside the oven? Seems
like an obvious idea so somebody has probably patented it.


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[Chris Caudle]

On Fri, July 22, 2016 2:15 pm, Hal Murray wrote:
> Has anybody put the DAC and all of the analog stuff inside the oven?

I ran across some OCXO's with a DAC inside the oven a few years back.
They were 5MHz instead of the 10MHz I was looking for so I didn't buy them
at the time. I have forgotten the vendor, but I seem to recall they had a
Maxim DAC inside the oven.

--
Chris Caudle


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[James Flynn]

Hal Murray <***@...> writes:


> That still leaves the temperature quirks of the DAC and amplifiers.
>
> Has anybody put the DAC and all of the analog stuff inside the oven?
Seems
> like an obvious idea so somebody has probably patented it.
>

I am using a 5 MHz custom built design which has everything inside the
outer oven in a double oven.

This includes:

Precision regulators for DC supply.
24 bit DAC
Reference for DAC
All analog devices, resistors and capacitors after DAC.
All buffer amplifiers from oscillator.

Unit only has raw DC and I2C lines for inputs and 5MHz sine wave out at
3 volts p-p.

It also seemed the obvious way to go in the design.

Performance is difficult to measure with equipment on hand. Waiting on
funding for experiment which includes equipment traceable to NIST.




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[Richard (Rick) Karlquist]

On 7/24/2016 6:44 AM, James Flynn wrote:
> Hal Murray <***@...> writes:
>> Has anybody put the DAC and all of the analog stuff inside the oven?
> Seems
>> like an obvious idea so somebody has probably patented it.
>>
>
> I am using a 5 MHz custom built design which has everything inside the
> outer oven in a double oven.
>
> This includes:
>
> Precision regulators for DC supply.
> 24 bit DAC
> Reference for DAC
> All analog devices, resistors and capacitors after DAC.
> All buffer amplifiers from oscillator.
>
> Unit only has raw DC and I2C lines for inputs and 5MHz sine wave out at
> 3 volts p-p.
>
> It also seemed the obvious way to go in the design.

IMHO, it isn't obvious that this is the way to go.
Nor is it a "free lunch" as it seems to be envisioned.
The last thing you want in an oven is a lot of
added thermal overhead, especially in a double oven
where you already fighting against running out of
temperature range. If you want to ovenize everything
but the kitchen sink, put it in it's own oven that is
separate from the crystal oven.

I also don't like intermingling digital signals with the
analog oscillator signal.

Have you measured the thermal gain of your outer oven?
I suspect it's not much. You could use inner oven
current draw as a proxy.

Rick
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[James Flynn]

Richard (Rick) Karlquist <***@...> writes:


> The last thing you want in an oven is a lot of
> added thermal overhead, especially in a double oven
> where you already fighting against running out of
> temperature range. If you want to ovenize everything
> but the kitchen sink, put it in it's own oven that is
> separate from the crystal oven.

The thermal overhead is quite small compared to the power required for
the outer oven to hold temperature. 80mW maximum as opposed to about 1
watt.

I did a comparison of the temperature rise of running the unit
essentially as a single, inner oven with the rest of the electronics
mentioned in the outer "box", and then turning on the outer heater. The
Q from the inner oven was far and away the dominant factor.

Putting the DAC inside the outer oven was the obvious solution for me,
as opposed to putting them outside in ambient. I did consider thermal
compensation, but again the outer oven would be able to keep things
within a fraction of a degree over the range of normal ambient in the
lab.

Separate ovens seems to be inviting noise getting into the signal lines
between the two ovens.

>
> I also don't like intermingling digital signals with the
> analog oscillator signal.

Not sure what you mean by "intermingling". There are separate ground
returns for the oscillator output (transformer isolated) and the digital
signals. There is a low pass filter between DAC and oscillator control
to minimize noise getting across. Also digital circuits and oscillator
have their own individual precision regulators.

>
> Have you measured the thermal gain of your outer oven?
> I suspect it's not much. You could use inner oven
> current draw as a proxy.

I did a while ago and remember it was on the order of 50 - 100. But I
have changed the design somewhat and should do it again when the
experiment gets going.






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[Bob Camp]

Hi

A typical double oven design runs about 10 mw or so in the circuitry
in the inner oven. The “stuff” inside the outer oven likely doubles that number.
The rest of the circuit is put outside the outer oven to reduce heat rise. There
could be another 40 mw in that part of the circuit. Everything else is controlled
power to heat things and will go to zero at the highest temperature.

If you run the inner oven at an offset of 3 to 5 C from the outer, the inner
heater will likely not pull more than 40 mw and may pull quite a bit less.

Bob


> On Jul 24, 2016, at 4:45 PM, James Flynn <***@csun.edu> wrote:
>
> Richard (Rick) Karlquist <***@...> writes:
>
>
>> The last thing you want in an oven is a lot of
>> added thermal overhead, especially in a double oven
>> where you already fighting against running out of
>> temperature range. If you want to ovenize everything
>> but the kitchen sink, put it in it's own oven that is
>> separate from the crystal oven.
>
> The thermal overhead is quite small compared to the power required for
> the outer oven to hold temperature. 80mW maximum as opposed to about 1
> watt.
>
> I did a comparison of the temperature rise of running the unit
> essentially as a single, inner oven with the rest of the electronics
> mentioned in the outer "box", and then turning on the outer heater. The
> Q from the inner oven was far and away the dominant factor.
>
> Putting the DAC inside the outer oven was the obvious solution for me,
> as opposed to putting them outside in ambient. I did consider thermal
> compensation, but again the outer oven would be able to keep things
> within a fraction of a degree over the range of normal ambient in the
> lab.
>
> Separate ovens seems to be inviting noise getting into the signal lines
> between the two ovens.
>
>>
>> I also don't like intermingling digital signals with the
>> analog oscillator signal.
>
> Not sure what you mean by "intermingling". There are separate ground
> returns for the oscillator output (transformer isolated) and the digital
> signals. There is a low pass filter between DAC and oscillator control
> to minimize noise getting across. Also digital circuits and oscillator
> have their own individual precision regulators.
>
>>
>> Have you measured the thermal gain of your outer oven?
>> I suspect it's not much. You could use inner oven
>> current draw as a proxy.
>
> I did a while ago and remember it was on the order of 50 - 100. But I
> have changed the design somewhat and should do it again when the
> experiment gets going.
>
>
>
>
>
>
> _______________________________________________
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