Re: [time-nuts] Alfred Loomis - an early time nut

[Clint Jay]

I've just received my June Radcom which contained news of the passing of a
Walter Blanchard who was involved in the development of Decca Navigator and
Loran C, he also worked on a GPS forerunner navigation system called
"Transit".

There's an obit at www.rsgb.org/sk which may contain more detail if there's
interest.

On Wed, 13 May 2020, 17:37 Gary Woods,  wrote:

> On Wed, 13 May 2020 09:23:45 -0600, you wrote:
>
> >Given all his accomplishments, he must have been a
> >"Renaissance Time_Nut"!
>
> My favorite quote from a bio of Loomis; he was shown the super secret
> British magnetron, and an engineer was trying to explain how it made
> high-power microwaves.
> Loomis listened and said, "Oh, it's a whistle!"
> (I dealt with it's megawatt descendent in the APS-20 radar).
> --
> Gary Woods O- K2AHC   Public keys at home.earthlink.net/~garygarlic, or
> get 0x1D64A93D via keyserver
> fingerprint =  E2 6F 50 93 7B C7 F3 CA  1F 8B 3C C0 B0 28 68
>
> --
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
>
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Re: [time-nuts] OCXO Support Board

[ew via time-nuts]

Thanks Mark for reminding me, spend 3 hours this morning reviewing designs to 
be released. Found a couple of problems. Also went back to look at the OCXO 
boards I released in 2018, found a problem on the board with no Amp, the SMA is 
not grounded. Easy to fix, but if some one wants new Gerber will publish 
it.Always try to have a third party check my designs. To many designs 30 this 
year.
Bert Kehren
In a message dated 5/13/2020 10:18:33 PM Eastern Standard Time, 
hol...@hotmail.com writes:

One thing that I recommend is that after completing the layout is to:1) step 
back and wait a few days2) enjoy a few adult beverages while waiting3) go back 
a re-check everything4) send it out to the board house
You'd be surprised how often simple, subtle, not so subtle 
glitches/tweaks/improvements show up after a pause in the process.
---
> Once you get going, a board is a weekend project. Indeed, a simple board 
> might be anevening project. There’s not a lot involved. 
> ___time-nuts mailing list -- 
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Re: [time-nuts] OCXO Support Board

[Bob kb8tq]

Hi

I would toss in:

If you are starting from scratch, pick a program that allows you to easily 
enter schematics as well as PCB layouts. Take the time to learn both sides
of the program. That will give you an automated check between the schematic
and the layout….. It also gives you a document to go back to / hand to others
to show what the board was intended to do. 

Bob

> On May 14, 2020, at 5:51 AM, ew via time-nuts  
> wrote:
> 
> Thanks Mark for reminding me, spend 3 hours this morning reviewing designs to 
> be released. Found a couple of problems. Also went back to look at the OCXO 
> boards I released in 2018, found a problem on the board with no Amp, the SMA 
> is not grounded. Easy to fix, but if some one wants new Gerber will publish 
> it.Always try to have a third party check my designs. To many designs 30 this 
> year.
> Bert Kehren
> In a message dated 5/13/2020 10:18:33 PM Eastern Standard Time, 
> hol...@hotmail.com writes:
> 
> One thing that I recommend is that after completing the layout is to:1) step 
> back and wait a few days2) enjoy a few adult beverages while waiting3) go 
> back a re-check everything4) send it out to the board house
> You'd be surprised how often simple, subtle, not so subtle 
> glitches/tweaks/improvements show up after a pause in the process.
> ---
>> Once you get going, a board is a weekend project. Indeed, a simple board 
>> might be anevening project. There’s not a lot involved. 
>> ___time-nuts mailing list -- 
>> time-n...@lists.febo.comTo unsubscribe, go to 
>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand follow 
>> the instructions there.
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Re: [time-nuts] OCXO Support Board

[Mike Ingle]

Hi All,

I will second Bob's comment on choosing a program with PCB - Schematic
integration.  I can heartily recommend Kicad.  I own Altium designer, but
work remotely for an American firm from Germany.  The US office uses PADs.
We have finally agreed on projects going forward to both use Kicad.  While
Altium designer is more mature, and a little smoother to use, all of the
programs have quirks, and require that you become familiar with them.  So
far I am not seeing any limitations in Kicad that would prevent getting
good boards made.  And, many  prototype oriented houses accept Kicad PCB
files directly (for example EUROCIRCUITS) , which saves you from generating
Gerbers and drill files.

And Kicad just keeps getting better.

-- mike



On Thu, May 14, 2020 at 4:30 PM Bob kb8tq  wrote:

> Hi
>
> I would toss in:
>
> If you are starting from scratch, pick a program that allows you to easily
> enter schematics as well as PCB layouts. Take the time to learn both sides
> of the program. That will give you an automated check between the schematic
> and the layout….. It also gives you a document to go back to / hand to
> others
> to show what the board was intended to do.
>
> Bob
>
> > On May 14, 2020, at 5:51 AM, ew via time-nuts 
> wrote:
> >
> > Thanks Mark for reminding me, spend 3 hours this morning reviewing
> designs to be released. Found a couple of problems. Also went back to look
> at the OCXO boards I released in 2018, found a problem on the board with no
> Amp, the SMA is not grounded. Easy to fix, but if some one wants new Gerber
> will publish it.Always try to have a third party check my designs. To many
> designs 30 this year.
> > Bert Kehren
> > In a message dated 5/13/2020 10:18:33 PM Eastern Standard Time,
> hol...@hotmail.com writes:
> >
> > One thing that I recommend is that after completing the layout is to:1)
> step back and wait a few days2) enjoy a few adult beverages while waiting3)
> go back a re-check everything4) send it out to the board house
> > You'd be surprised how often simple, subtle, not so subtle
> glitches/tweaks/improvements show up after a pause in the process.
> > ---
> >> Once you get going, a board is a weekend project. Indeed, a simple
> board might be anevening project. There’s not a lot involved.
> ___time-nuts mailing list --
> time-n...@lists.febo.comTo unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand follow
> the instructions there.
> > ___
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> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
>
>
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Re: [time-nuts] OCXO Support Board

[Bob kb8tq]

Hi

Going from “pro” layout tools to KiCad, the only big thing that seems to
be missing is a “full feature” DRC (design rules check) process in KiCad. 
The tools I worked with in the past had much more fine grained rules checking
features. 

Probably not a big deal for a basement project. It would have stopped things
dead if we tried to run it at work. We had at least 4 layers of rules checking 
that ran before the board finally went out for fab …..

Bob

> On May 14, 2020, at 12:08 PM, Mike Ingle  wrote:
> 
> Hi All,
> 
> I will second Bob's comment on choosing a program with PCB - Schematic
> integration.  I can heartily recommend Kicad.  I own Altium designer, but
> work remotely for an American firm from Germany.  The US office uses PADs.
> We have finally agreed on projects going forward to both use Kicad.  While
> Altium designer is more mature, and a little smoother to use, all of the
> programs have quirks, and require that you become familiar with them.  So
> far I am not seeing any limitations in Kicad that would prevent getting
> good boards made.  And, many  prototype oriented houses accept Kicad PCB
> files directly (for example EUROCIRCUITS) , which saves you from generating
> Gerbers and drill files.
> 
> And Kicad just keeps getting better.
> 
> -- mike
> 
> 
> 
> On Thu, May 14, 2020 at 4:30 PM Bob kb8tq  wrote:
> 
>> Hi
>> 
>> I would toss in:
>> 
>> If you are starting from scratch, pick a program that allows you to easily
>> enter schematics as well as PCB layouts. Take the time to learn both sides
>> of the program. That will give you an automated check between the schematic
>> and the layout….. It also gives you a document to go back to / hand to
>> others
>> to show what the board was intended to do.
>> 
>> Bob
>> 
>>> On May 14, 2020, at 5:51 AM, ew via time-nuts 
>> wrote:
>>> 
>>> Thanks Mark for reminding me, spend 3 hours this morning reviewing
>> designs to be released. Found a couple of problems. Also went back to look
>> at the OCXO boards I released in 2018, found a problem on the board with no
>> Amp, the SMA is not grounded. Easy to fix, but if some one wants new Gerber
>> will publish it.Always try to have a third party check my designs. To many
>> designs 30 this year.
>>> Bert Kehren
>>> In a message dated 5/13/2020 10:18:33 PM Eastern Standard Time,
>> hol...@hotmail.com writes:
>>> 
>>> One thing that I recommend is that after completing the layout is to:1)
>> step back and wait a few days2) enjoy a few adult beverages while waiting3)
>> go back a re-check everything4) send it out to the board house
>>> You'd be surprised how often simple, subtle, not so subtle
>> glitches/tweaks/improvements show up after a pause in the process.
>>> ---
 Once you get going, a board is a weekend project. Indeed, a simple
>> board might be anevening project. There’s not a lot involved.
>> ___time-nuts mailing list --
>> time-n...@lists.febo.comTo unsubscribe, go to
>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand follow
>> the instructions there.
>>> ___
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe, go to
>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>>> and follow the instructions there.
>> 
>> 
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[time-nuts] FE-5680A tuning vs resonant peaks

[Jeff Woolsey]

I wonder if my FE-5680A is locking to the wrong resonance, or that I've
tweaked it too far off the main one.

Setup:

FE-5680A Rubidium oscillator with passive support/breakout board,
ostensibly regulated with an LM1084-ADJ. Trimble Thunderbolt GPSDO,
feeding an HP-53131A universal counter as external reference.

Powered up from cold, the Rb eventually locks around 999.95644 Hz. 
Turn the bench supply voltage down about 1.5V, and it becomes
1000.0089 Hz fairly quickly, later settling around 999.9988 Hz. 
While 2mHz accuracy is sufficient for my needs (let's face it, it's
overkill, and nominally better than any other 8-digit counter I have),
this is time-nuts after all.

I'm wondering if it isn't locking on a nearby secondary resonant peak. 
There's a graph at http://leapsecond.com/images/cfield.gif showing
resonant peaks for Cesium. I haven't yet found one for Rubidium. 
Knowing how far apart the peaks are, and the base oscillator (~50.5MHz)
that gets multiplied by 136 up to 6.8+GHz, perhaps one peak accounts for
the 50mHz difference I see.

Before coming up with this theory, I had tweaked the non-programmable
(per ka7oei.com) FE-5680A offset using a Windows-only program, perhaps
too far.

The other theory is that Lady Heather reports the TBolt OSC value
typically in the high tens of ppt (with similar variance tick-to-tick)
and in the hundreds of ppt a little less often, usually after a change
in satellites (logs available).  I wonder how that affects the counter
accuracy.

-- 
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel.  -Crow on solitaire



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Re: [time-nuts] OCXO Support Board

[Graham / KE9H]

Most of the PC board manufacturers run a rules check for your board against
their process capability.
I have had them catch some things from time to time that the design
tool missed.
For commercial business, I more rules checking is always better, but for
hobby and personal purposes, I think the combination is very adequate.
--- Graham


On Thu, May 14, 2020 at 12:26 PM Bob kb8tq  wrote:

> Hi
>
> Going from “pro” layout tools to KiCad, the only big thing that seems to
> be missing is a “full feature” DRC (design rules check) process in KiCad.
> The tools I worked with in the past had much more fine grained rules
> checking
> features.
>
> Probably not a big deal for a basement project. It would have stopped
> things
> dead if we tried to run it at work. We had at least 4 layers of rules
> checking
> that ran before the board finally went out for fab …..
>
> Bob
>
> > On May 14, 2020, at 12:08 PM, Mike Ingle  wrote:
> >
> > Hi All,
> >
> > I will second Bob's comment on choosing a program with PCB - Schematic
> > integration.  I can heartily recommend Kicad.  I own Altium designer, but
> > work remotely for an American firm from Germany.  The US office uses
> PADs.
> > We have finally agreed on projects going forward to both use Kicad.
> While
> > Altium designer is more mature, and a little smoother to use, all of the
> > programs have quirks, and require that you become familiar with them.  So
> > far I am not seeing any limitations in Kicad that would prevent getting
> > good boards made.  And, many  prototype oriented houses accept Kicad PCB
> > files directly (for example EUROCIRCUITS) , which saves you from
> generating
> > Gerbers and drill files.
> >
> > And Kicad just keeps getting better.
> >
> > -- mike
> >
> >
> >
> > On Thu, May 14, 2020 at 4:30 PM Bob kb8tq  wrote:
> >
> >> Hi
> >>
> >> I would toss in:
> >>
> >> If you are starting from scratch, pick a program that allows you to
> easily
> >> enter schematics as well as PCB layouts. Take the time to learn both
> sides
> >> of the program. That will give you an automated check between the
> schematic
> >> and the layout….. It also gives you a document to go back to / hand to
> >> others
> >> to show what the board was intended to do.
> >>
> >> Bob
> >>
> >>> On May 14, 2020, at 5:51 AM, ew via time-nuts <
> time-nuts@lists.febo.com>
> >> wrote:
> >>>
> >>> Thanks Mark for reminding me, spend 3 hours this morning reviewing
> >> designs to be released. Found a couple of problems. Also went back to
> look
> >> at the OCXO boards I released in 2018, found a problem on the board
> with no
> >> Amp, the SMA is not grounded. Easy to fix, but if some one wants new
> Gerber
> >> will publish it.Always try to have a third party check my designs. To
> many
> >> designs 30 this year.
> >>> Bert Kehren
> >>> In a message dated 5/13/2020 10:18:33 PM Eastern Standard Time,
> >> hol...@hotmail.com writes:
> >>>
> >>> One thing that I recommend is that after completing the layout is to:1)
> >> step back and wait a few days2) enjoy a few adult beverages while
> waiting3)
> >> go back a re-check everything4) send it out to the board house
> >>> You'd be surprised how often simple, subtle, not so subtle
> >> glitches/tweaks/improvements show up after a pause in the process.
> >>> ---
>  Once you get going, a board is a weekend project. Indeed, a simple
> >> board might be anevening project. There’s not a lot involved.
> >> ___time-nuts mailing list --
> >> time-n...@lists.febo.comTo unsubscribe, go to
> >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand
> follow
> >> the instructions there.
> >>> ___
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> >>> To unsubscribe, go to
> >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> >>> and follow the instructions there.
> >>
> >>
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Re: [time-nuts] Alfred Loomis - an early time nut

[Skip Withrow]

The Alfred Loomis story is very interesting.  Thanks for bringing it
up again.  The PBS American Experience episode is certainly worth
watching.

A question for TVB (or anyone else that might know), what happened to
the three Shortt clocks that he had?  Also of interest would be how
many still exist today, and how many in running condition (and
Fedchenko and Riefler)?

There is something very satisfying about the tick-tock of a pendulum
clock, though I realize the Shortt's were not direct drive.

Regards,
Skip Withrow

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Re: [time-nuts] Alfred Loomis - an early time nut

[Hal Murray]

t...@leapsecond.com said:
> Yes, the book about Loomis by Jennet Conant is highly recommended.

I thought it was a great read.

There is a CSPAN author interview on youtube.  Not much about time-nuttery but 
lots of stories about the people involved.  Her grandfather was president of 
Harvard during WW II and he was tangled up with much of the wartime research.

A Wall Street Tycoon and the Secret Palace of Science: Finance, Investing 
(2002)
  https://www.youtube.com/watch?v=w6U2yUNQRY8
57 minutes.



Not particularly time-nutty, but if you liked Tuxedo Park, there is a good 
chance you will enjoy this book too:
  The Invention that Changed the World
  How a small group of RADAR pioneers won the second world war and launched a 
technological revolution
Robert Buderi

He is one of the writers contributing comments to the PBS/American Experience 
story about Loomis.




-- 
These are my opinions.  I hate spam.




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Re: [time-nuts] OCXO Support Board

[Hal Murray]

kb...@n1k.org said:
> Probably not a big deal for a basement project. It would have stopped things
> dead if we tried to run it at work. We had at least 4 layers of rules
> checking  that ran before the board finally went out for fab ….. 

Could you give a few examples of the more obscure rules?

Do the low cost board shops give you enough info to check them?

Thanks.


-- 
These are my opinions.  I hate spam.




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[time-nuts] measuring timing variation in a web conference.

[jimlux]

A practical data source has become available for me to look at.
The lab had a virtual town hall, and one of the senior managers has a 
pendulum clock in the background. And, there were obvious drops in the 
video stream, because the pendulum would "jump" (it was commented on by 
viewers - "That stuttering clock was driving me crazy" )


I doubt the clock is actually pendulum regulated (it has the look of an 
art clock, probably battery driven).


It also brought up how good humans are at spotting slight irregularities 
in an otherwise regular motion. It's one of those hardwired 
capabilities, it's useful, whether you are prey or predator.


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Re: [time-nuts] measuring timing variation in a web conference.

[Poul-Henning Kamp]

In message <698338c4-f4df-444e-29eb-e7e8fa3b9...@earthlink.net>, jimlux writes:

>And, there were obvious drops in the 
>video stream, because the pendulum would "jump" (it was commented on by 
>viewers - "That stuttering clock was driving me crazy" )

... or he was devious enough to have bought a "Vetinari Clock":

https://www.instructables.com/id/Lord-Vetinari-Clock/


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

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Re: [time-nuts] OCXO Support Board

[Bob kb8tq]

Hi

Well, a full list of all the rules we ran against would run about 10 pages. I 
think 
that’s getting pretty far off topic for TimeNuts. I also, quite frankly never 
bothered
to memorize them all. 

A few examples of what one *might* do:

1) “Allow” a violation. Things like courtyard overlaps often are non-issues. A 
fancy
program would let you “allow” ( = suppress ) the error once you checked it out.

2) Zone based rules. The region under a BGA may be very tight in terms or 
clearances.
The rest of the board likely will not be. Having rule zones helps deal with 
this. 

3) Silk screen / mask rules. Getting the silk screen so it either shows right 
or is suppressed
is a pretty basic process. Doing it manually is a major pain. Indeed a number 
of “pro”
packages have the same issues. 

4) Extras. Duplicate holes should not get into the drill file. Dangling trace 
bits should be
spotted and flagged……..

Yes, this could go on and on.

No, the cheap board houses don’t check for this stuff. They just build and send 
it
back. If there’s a gotcha, you get it on the board. 

Bob

> On May 14, 2020, at 3:12 PM, Hal Murray  wrote:
> 
> 
> kb...@n1k.org said:
>> Probably not a big deal for a basement project. It would have stopped things
>> dead if we tried to run it at work. We had at least 4 layers of rules
>> checking  that ran before the board finally went out for fab ….. 
> 
> Could you give a few examples of the more obscure rules?
> 
> Do the low cost board shops give you enough info to check them?
> 
> Thanks.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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Re: [time-nuts] FE-5680A tuning vs resonant peaks

[gandalfg8--- via time-nuts]

Hmmm...
You mention varying suply voltage by 1.5V, but from where as a starting point?

It's been a while since I calibrated an FE5680A but looking back through my 
notes, doing it "properly" is, or was for me anyway, a non trivial exercise.I'm 
not familiar with the Windows software mentioned but the approach I remember 
was first to determine what, if any, offset was programmed into the unit as 
received, then to measure the frequency of the unit as received, then to 
calibrate the tuning itself by setting positive and negative tuning extremes 
and measuring the frequency range before interpolating to find an initial 
tuning word, followed by calculating a further approximation, and so on and so 
fifth, and of course eventually programming the FE5680A accordingly.

At that time I was using a similar test setup of a 53132A referenced to a 
Thunderbolt, although I did use a second Thunderbolt feeding the second channel 
of the 53132A as a confidence check.
Much as I love Lady Heather, hmmm just how kinky is that?:-), I don't rely too 
much on her reported offsets etc, preferring to trust hardware measurement for 
that, but would suggest that if she is showing your thunderbolt as locked and 
tracking a reasonable number of sats then experience suggests you should be 
able to trust your Thunderbolt as being on frequency.
Experience also suggests, at least with all the units I've seen, that the 
FE5680A generally reached the surplus market with a programmed offset of zero, 
presumably because that was good enough for its intended purpose.S, I would 
suggest that if you have any doubts at all the first obvious thing to do is to 
reprogram the offset to zero, and start again from there.
I'd be happy to share my programming notes, but must admit I'm having a bit of 
fun understanding them myself right now:-)

Nigel GM8PZR


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[time-nuts] Alfred Loomis - an early time nut

[Eric Scace]

> On 2020 May 14, at 14:21 , Skip Withrow  > wrote:
> […snip…]
> 
> A question for TVB (or anyone else that might know), what happened to
> the three Shortt clocks that he [Loomis] had?

   About 100 Shortt-Synchronome systems were manufactured. There is not a 
central database of locations for the surviving instruments, as far as I know. 
I know the location of maybe a dozen or so — but there are plenty more than 
that in existence. Some are still in the hands of their original owners; some 
are in museums; others are in private collections.

>  Also of interest would be how
> many still exist today, and how many in running condition

   Very few of the survivors of which I am aware are presently operating. The 
one at NIST’s library in Gaithersburg, for example, was maintained by a retired 
staff member. A few years ago he moved from the DC metro area. A vacuum leak 
developed in the master and the system stopped.

   The ClockWorks museum in London has had difficulty keeping their system 
operating. There are some tricks to its setup, the knowledge of which has not 
been well-maintained.

> (and
> Fedchenko

   Fedchenko engineered 4 pendulum-based systems:
a clone of the Shortt-Synchronome, of which the highest known serial number is 
#27. These were manufactured by Etalon in Leningrad. At present three complete 
(master + slave) systems are known exist, and two slave-only units. I’m not 
sure that any of the three complete systems are operational; two may be capable 
of starting up but their ability to run for long periods of time is unknown.
AChF #1 was a first generation prototype of the system for which Fedchenko is 
famous. It was placed in the first floor of a working building at KhGIMIP 
(Kharkov State Institute for Weights and Measures) and tested for 3 years 
(1955-1958) against the KKh-3 quartz clock. This model was not placed in 
production. Unless Etalon has it in archives, it may not have survived.
AChF #2 was a second generation prototype built in 1956 — maybe lost or perhaps 
in Etalon archives.
AChF #3: The highest known serial numbers, #36 and #37 (incomplete), came to 
light in the last six years. Thirteen survivors are known. Of these, four are 
in museums: one in Switzerland, one at the Greenwich Observatory, and two at 
the ClockWorks Museum (London). The remainder are in private hands. There is 
also an orphaned slave clock in private hands whose current location is unknown.
The Greenwich one was installed by Etalon as a gift and ran for a number of 
years but has stopped for unknown reasons — possibly a vacuum leak.  
Unfortunately it’s built into a display cabinet that would have to be 
disassembled in order to service the clock.
When I last visited, one of the two systems at Clockworks was operational but 
not kept in continuous service.
The operational condition of the system in Switzerland is unknown.
At least one system in private hands is kept operating, but not instrumented 
for measurements.

> and Riefler)?

   Riefler made a vast number of models. I don’t know of an inventory of the 
partial-vacuum tank clocks.

> There is something very satisfying about the tick-tock of a pendulum
> clock, though I realize the Shortt's were not direct drive.

   The seconds-driving contacts of the Shortt-Synchronome make plenty of “tick 
tock”! Synchronome used a weight-assisted contact mechanism to ensure a 
reliable “make” and the weight gets reset by a solenoid each second. With care, 
one can do a lot to quiet down the noise to acceptable residential levels. But 
that’s another lengthier discussion.

> 
> Regards,
> Skip Withrow


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[time-nuts] Teensy 4.1

[Adrian Godwin]

I just saw an update to the Teensy microcontroller line.
Teensys are somewhat like an arduino but generally with faster processors
and more memory.

The latest one, 4.1, has an ethernet interface with IEEE1588
packet timestamping.

https://www.pjrc.com/category/news/

I'm not on pjrc's staff etc, but I like his products and as far as I know
this is a 'first' for such an interface on a cheap, fast development board
($26, 600MHz).
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Re: [time-nuts] Teensy 4.1

[jimlux]

On 5/14/20 3:14 PM, Adrian Godwin wrote:

I just saw an update to the Teensy microcontroller line.
Teensys are somewhat like an arduino but generally with faster processors
and more memory.

The latest one, 4.1, has an ethernet interface with IEEE1588
packet timestamping.

https://www.pjrc.com/category/news/

I'm not on pjrc's staff etc, but I like his products and as far as I know
this is a 'first' for such an interface on a cheap, fast development board
($26, 600MHz).


That's very cool.

I've been using Teensys since 3.0.  In fact, I ran some clock 
performance tests on 5 teensy 3.1s - nothing unusual found.



I like the teensys because they have decent ADC (16 bit differential) 
and DAC (not PWM DAC), so you can actually do some interesting audio 
frequency stuff (like using them as a doppler radar processor to detect 
heartbeats).




I'm glad they're still pushing the envelope.

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Re: [time-nuts] Teensy 4.1

[Bill Notfaded]

It's pretty legit and can run like any other Arduino does.  With 100Mbit
physical Ethernet built in that's pretty big for a tiny board.  It
supports the precision time protocol (PTP). Also known as IEEE 1588, this
protocol allows for synchronizing connected devices with sub-microsecond
precision.  The size, price and features with that physical Ethernet is BIG!

It has built in micro SD slot now too with more GPIO as well!  Hot dang!

Real-time microcontroller with a high-throughput data pipe = pretty bad
@ss.  $26.85 not bad at all 4 what you get!

Bill

On Thu, May 14, 2020, 3:15 PM Adrian Godwin  wrote:

> I just saw an update to the Teensy microcontroller line.
> Teensys are somewhat like an arduino but generally with faster processors
> and more memory.
>
> The latest one, 4.1, has an ethernet interface with IEEE1588
> packet timestamping.
>
> https://www.pjrc.com/category/news/
>
> I'm not on pjrc's staff etc, but I like his products and as far as I know
> this is a 'first' for such an interface on a cheap, fast development board
> ($26, 600MHz).
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Re: [time-nuts] OCXO Support Board

[John Ackermann N8UR]

On 5/14/20 5:07 PM, Bob kb8tq wrote:

> No, the cheap board houses don’t check for this stuff. They just build and 
> send it
> back. If there’s a gotcha, you get it on the board. 

I was pleasantly surprised last week when Seeed Fusion contacted me to
point out a problem where two vias were too close together (by a couple
of thousandths).  They asked if they could reduce the hole diameters
slightly to correct.  I agreed, they made the change, and the boards are
with DHL right now.  So they do have a process to kick at least some
issues to human beings for resolution, rather than just rejecting the job.

BTW, two things I've learned from my current project:

1.  Seeed claims that they can do down to 4mil trace width and spacing,
and down to 0.2mm holes, but those add extra charges.  For their $4.95
for ten boards deal, the minimums are 6mils and 0.5mm holes (why can't
they pick one dimension system for the specs???)  Go smaller and the
price goes up 10x or more.

2.  Where I had the clearance problem was on a USB C connector.
Whatever advantages they have, they are a pain to route and solder.  The
one I used (which seems fairly common) has both through hole and SMT
pads, and the space to get all the signals lines connected and routed is
very, very tight.  The smaller trace and hole sizes would have made the
job easier, but I wasn't willing to jack up the cost for that.

John



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Re: [time-nuts] Teensy 4.1

[Didier Juges]

I just got a Teensy 4.0, OSHPark edition (it was $18 when I bought a set of
boards a couple of weeks ago).
I have not done anything with it yet but I am looking forward to.
I have not looked at the differences with the 4.1.

Didier KO4BB

On Thu, May 14, 2020, 5:15 PM Adrian Godwin  wrote:

> I just saw an update to the Teensy microcontroller line.
> Teensys are somewhat like an arduino but generally with faster processors
> and more memory.
>
> The latest one, 4.1, has an ethernet interface with IEEE1588
> packet timestamping.
>
> https://www.pjrc.com/category/news/
>
> I'm not on pjrc's staff etc, but I like his products and as far as I know
> this is a 'first' for such an interface on a cheap, fast development board
> ($26, 600MHz).
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Re: [time-nuts] Teensy 4.1

[Philip Gladstone]

I like the look of the 4.1 especially once they sell the Ethernet kit. I'll
port my NTP/PTP server over to it as it is a lot smaller (and cheaper) than
the current board that I'm using. Happily the Teensy is supported by
ChibiOS which is the OS that I used before.

Philip

On Thu, May 14, 2020 at 7:35 PM Didier Juges  wrote:

> I just got a Teensy 4.0, OSHPark edition (it was $18 when I bought a set of
> boards a couple of weeks ago).
> I have not done anything with it yet but I am looking forward to.
> I have not looked at the differences with the 4.1.
>
> Didier KO4BB
>
> On Thu, May 14, 2020, 5:15 PM Adrian Godwin  wrote:
>
> > I just saw an update to the Teensy microcontroller line.
> > Teensys are somewhat like an arduino but generally with faster processors
> > and more memory.
> >
> > The latest one, 4.1, has an ethernet interface with IEEE1588
> > packet timestamping.
> >
> > https://www.pjrc.com/category/news/
> >
> > I'm not on pjrc's staff etc, but I like his products and as far as I know
> > this is a 'first' for such an interface on a cheap, fast development
> board
> > ($26, 600MHz).
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Re: [time-nuts] OCXO Support Board

[Gerhard Hoffmann]

Am 15.05.20 um 01:25 schrieb John Ackermann N8UR:

On 5/14/20 5:07 PM, Bob kb8tq wrote:


No, the cheap board houses don’t check for this stuff. They just build and send 
it
back. If there’s a gotcha, you get it on the board.

I was pleasantly surprised last week when Seeed Fusion contacted me to
point out a problem where two vias were too close together (by a couple
of thousandths).  They asked if they could reduce the hole diameters

I had the same good experience with PCBway.

I used these 0.9 * 0.9 mm GaN FETs, and that does not mean 0.9mm gate 
length:

https://www.digikey.de/product-detail/de/epc/EPC2038/917-1138-1-ND/5774048

and used the proposed Altium footprints from EPC. These pull the
solder mask onto the pad which is unusual but maybe essential for
a smooth soldering experience. I'm sure that EPC have experimented with 
that.


PCBway emailed me directly and we cleared that up that it was intentional.
They still produced the board on the same day, and soldering was easy.
Very satisfied customer.

Nevertheless I'll try JLCpcb next week. They now have a proxy man somewhere
here in .de who gets one box from China a day and forwards the contents
to the different customers after the customs work is done, via normal 
local registered mail.

The import VAT is then already done and billed by JLCpcb.
DHL Express is a royal pain to deal with.

Cheers, Gerhard


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[time-nuts] f-multipliers from VHF to 10 GHz

[Gerhard Hoffmann]

I have a potential project in the electron spin spectroscopy sector and 
I need
one or two clean signal sources in the 10 GHz range. Phase noise at, 
say, 50 Hz offset

is important, but anything below 110 dBc  does not care.
That probably calls for a multiplied crystal. These Hittite PLLs from AD 
seem to be

just not good enough, maybe they'd work if pushed, but no reserve left.
Are there any known proven multipliers chains from VHF to 10 GHz?

Cheers, Gerhard

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Re: [time-nuts] f-multipliers from VHF to 10 GHz

[Mike Garvey via time-nuts]

Cesium is 9.192 GHz; use a Cs standard design as a point of departure...?
Mike 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Gerhard 
Hoffmann
Sent: Thursday, May 14, 2020 20:58
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] f-multipliers from VHF to 10 GHz

I have a potential project in the electron spin spectroscopy sector and 
I need
one or two clean signal sources in the 10 GHz range. Phase noise at, 
say, 50 Hz offset
is important, but anything below 110 dBc  does not care.
That probably calls for a multiplied crystal. These Hittite PLLs from AD 
seem to be
just not good enough, maybe they'd work if pushed, but no reserve left.
Are there any known proven multipliers chains from VHF to 10 GHz?

Cheers, Gerhard

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Re: [time-nuts] f-multipliers from VHF to 10 GHz

[Bill Byrom]

Wenzel Associates (www.wenzel.com) In Austin TX can build custom rack mounted 
multiplied very low phase noise crystal sources. I have used their custom 
microwave multiplied crystal sources at my pre-retirement job (Tektronix RF 
Application Engineer) with a 12.5 GHz output. A few of my customers also 
evaluated and purchased these sources for driving the 12.5 GHz external clock 
input of the Tektronix AWG7A/B series AWG's and 70KSX series oscilloscopes. 
My experience with this multiplied source was about 2 to 4 years ago, but they 
probably can still build these. I think the price was roughly US $15,000 for a 
rack mounted semi-custom system source.

One customer purchased the Wenzel golden multiplied 12.5 GHz source to get very 
low phase noise output of a Tektronix AWG70K AWG to generate microwave chirps 
for use in electron spin spectroscopy. The AWG70K has an internal moderate 
performance PLL synthesizer but that wasn't good enough for the spectroscopy 
experiments. When you use the Wenzel 12.5 GHz external clock, the phase noise 
of the AWG is dominated by the external clock. There is some small additional 
phase noise due to the AWG clock edge detection and SiGe DAC wideband noise. 
Another customer needed to generat very low phase noise RADAR signals.

As I remember the Wenzel product block diagram, they used a 10 MHz internal 
crystal reference oscillator as the master frequency reference with optional 
EFC electrical frequency control input. A higher frequency very low phase noise 
VHF crystal oscillator (between 100-200 MHz, I believe) was locked to the 10 
MHz internal or external reference, and that VHF oscillator was multiplied and 
filtered in several stages to get to the microwave range (such as 10 to 12.5 
GHz). They could customize their system to provide auxiliary lower frequency 
outputs from any of the multiplier stages.

The Tek AWG70K series arbitrary waveform generators have an external clock 
input with a range of 6.25-12.5 GHz. The external clock is double clocked on 
both rising and falling edges. So with a 12.5 GHz sine input, the internal 
10-bit SiGe DAC is clocked at 25 GS/s. The AWG70001A and AWG70001B offset two 
of the 25 GS/s DACs by 180 degrees to get 50 GS/s AWG performance with a 
sin(x)/x usable bandwidth of nearly 20 GHz.
--
Bill Byrom N5BB
Retired in Nov 2019 from Tektronix after 32 years as an AE


On Thu, May 14, 2020, at 7:58 PM, Gerhard Hoffmann wrote:
> I have a potential project in the electron spin spectroscopy sector and 
> I need
> one or two clean signal sources in the 10 GHz range. Phase noise at, 
> say, 50 Hz offset
> is important, but anything below 110 dBc  does not care.
> That probably calls for a multiplied crystal. These Hittite PLLs from AD 
> seem to be
> just not good enough, maybe they'd work if pushed, but no reserve left.
> Are there any known proven multipliers chains from VHF to 10 GHz?
> 
> Cheers, Gerhard
> 
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Re: [time-nuts] FE-5680A tuning vs resonant peaks

[Jeff Woolsey]

> Hmmm...
> You mention varying suply voltage by 1.5V, but from where as a starting point?

Sorry, that is a red herring.  The regulator on the support board needs
enough headroom to regulate to 15V for the FE5680A.  Thus anything less
than about 17V input will drag down the voltage into the unit, and the
frequency rises. I got down to 14V--the unit remains locked but 10MHz
doesn't.  (It also doesn't help that the voltage display on the power
supply is about half a volt off.)  On the other hand, the regulator has
a high-temp cutoff which I managed to hit at around 20V--there is no
real heat sink on the support card.  Usually it's running around 80C;
cutoff at 125C.


> It's been a while since I calibrated an FE5680A but looking back through my 
> notes, doing it "properly" is, or was for me anyway, a non trivial 
> exercise.I'm not familiar with the Windows software mentioned but the 
> approach I remember was first to determine what, if any, offset was 
> programmed into the unit as received,


The software I'm using doesn't seem to be able to read and display the
previous offset  Sigh.


> then to measure the frequency of the unit as received, then to calibrate the 
> tuning itself by setting positive and negative tuning extremes and measuring 
> the frequency range before interpolating to find an initial tuning word, 
> followed by calculating a further approximation, and so on and so fifth, and 
> of course eventually programming the FE5680A accordingly.


Which is what I should be doing instead of winging it


> At that time I was using a similar test setup of a 53132A referenced to a 
> Thunderbolt, although I did use a second Thunderbolt feeding the second 
> channel of the 53132A as a confidence check.


Somebody should push me to pulling the trigger on buying a little ublox
LEA M8F-based GPSDO (VCTCXO) (currently on that auction site).   It
would replace a wireless cellphone eval kit (with ublox LEON chip) I
picked up MAD-magazine-cheap at a flea market that I managed to short
out the TIMEPULSE on...  My tools are too big for soldering a wire to
surface-mount, let alone replacing the chip.


> Much as I love Lady Heather, hmmm just how kinky is that?:-), I don't rely 
> too much on her reported offsets etc,

The particular figure I think I'm looking at is straight out of the
TBolt.  It's "10MHz offset" bytes 20-23 in the 0x8F-AC report packet.
All that LH does is multiply it by 1000 to report it as parts per
trillion.  The TBolt is measuring the frequency offset of the 10MHz
output relative to GPS/UTC in parts per billion.  Positive values
indicate the 10MHz clock is running slow relative to GPS/UTC.   Watching
this value in LH shows a lot of jitter.  I try to take measurements on
the counter when this value is closest to 0.  This is impossible to
predict, of course.  Next best would be to correlate this value with the
readings I take (via GPIB) from the counter.  My impression is that the
Rb may be more stable over the short term than the GPSDO, but I'd like
to be more certain.


> preferring to trust hardware measurement for that, but would suggest that if 
> she is showing your thunderbolt as locked and tracking a reasonable number of 
> sats then experience suggests you should be able to trust your Thunderbolt as 
> being on frequency.


Trust but verify...


> Experience also suggests, at least with all the units I've seen, that the 
> FE5680A generally reached the surplus market with a programmed offset of 
> zero, presumably because that was good enough for its intended purpose.S, 
> I would suggest that if you have any doubts at all the first obvious thing to 
> do is to reprogram the offset to zero, and start again from there.
> I'd be happy to share my programming notes, but must admit I'm having a bit 
> of fun understanding them myself right now:-)
>
>
I have to pay more attention to whether increasing the offset I send
makes the frequency rise or fall.  And it has to be a fairly large
offset to make the output change obvious.  The manual isn't very clear
whether this offset is for the 50.5MHz oscillator or for the divided
result (to give 10MHz independently).  I'd expect the latter.

I suppose I should re-learn how linear regression works on my calculator.

-- 
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel.  -Crow on solitaire

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