Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum 9700AT Programmable Time System

[Forrest Christian (List Account)]

Just curious, is there by chance a removable eprom or other programmable
device on these boards?

Assuming a fairly verbose scpi like command interface, I've occasionally
had luck reverse engineering a command set by looking through an eprom dump
for a list of commands?

Also, does this by chance respond to the standard scpi commands like *IDN?
and *TST?

On Mon, Apr 9, 2018, 12:24 PM Bill  wrote:

> I have two of these with 488  interfaces.
> Would appreciate any 488 info you get.
> br...@otelco.net
>
> -Original Message-
> From: Bob kb8tq
> Sent: Saturday, April 07, 2018 10:27 PM
> To: lee...@aol.com ; Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum
> 9700AT Programmable Time System
>
> Hi
>
> Actually the manual is moot on any sort of remote control. The RS-232
> section refers you to an insert
> in the back of the manual. I’d guess that the 488 stuff was done the same
> way.
>
> Nasty question: Are you sure you have the 488 option installed?  It would
> not be the first piece of gear
> produced that never really got a 488 firmware version …..
>
> Bob
>
> > On Apr 7, 2018, at 11:11 PM, Tom Leedy via time-nuts  >
> > wrote:
> >
> >
> > Hi:
> >
> > I am looking for the IEEE-488 codes and formats for a Datum 9700AT
> > Programmable Time System.  The 9700AT is a 1U time generator and
> > translator with slots in the back that can accept option cards with
> > various functionalities such as -488 and RS-232 interfaces, GPIO, and
> tape
> > searches.  What I need is the character strings to output the time for
> > the -488 interface.  The manual for the unit is here:
> >
> http://www1.symmetricom.com/media/files/support/ttm/product-manual/man-9700at-9710.pdf
> > However, it is silent on the details of the -488 interface.
> >
> > Any help would be appreciated and feel free to contact me offline.
> >
> > Many thanks!
> >
> > Tom Leedy
> > Clarksburg, MD
> >
> >
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Re: [time-nuts] Frequency deviations in Europe affect clocks

[Forrest Christian (List Account)]

When there is more demand than generation, the frequency of the grid
drops.   My understanding is that one particular country is pulling more
from the grid than they are generating, and for political/and or financial
reasons which are a bit unclear, noone is willing to generate enough power
to balance the grid.  For most of the generators, the most likely reason is
probably because they aren't wanting to generate the power for free.

In essence this power is being stolen from the grid and not being returned,
causing the frequency variation.

On Mar 9, 2018 12:06 AM, "David G. McGaw" 
wrote:

Can someone please explain why not paying your bills causes the grid and
therefore the clocks to slow down?  None of the reports, either for the
technical or lay person, give a reason.

David N1HAC



On 3/8/18 5:00 PM, Pieter-Tjerk de Boer wrote:

> Hello all,
>
> Here's my graph of the mains grid phase deviation over the last month, and
> for comparison the normal behaviour during the previous year:
>
>https://na01.safelinks.protection.outlook.com/?url=http:%
> 2F%2Fwwwhome.ewi.utwente.nl%2F~ptdeboer%2Fmisc%2Fmains-
> 2018.html&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.
> edu%7Cea149d08d4134d49c94908d58552ea8e%7C995b093648d640e5a31
> ebf689ec9446f%7C0%7C0%7C636561513531276977&sdata=LwRuSvSr0HO
> kxvFoI26uFxgjAxbFif6ytgxe4U2Q%2BQE%3D&reserved=0
>
>
> This is measured in Enschede, the Netherlands, by time-stamping every mains
> cycle using NTP for reference.
>
> Naturally, the 2018 part of the graph nicely matches the graph Detlef
> posted.
>
> Regards,
>Pieter-Tjerk de Boer (PA3FWM)
>
>
>
> On Thu, Mar 08, 2018 at 03:50:42PM +0100, d.schuec...@avm.de wrote:
>
>> Hi,
>>
>> from new years eve until today 00:00 the European Electricity Grid entsoe
>> lost 16891 sinewaves, nearly 338 seconds. Enclosed you find the sketch of
>> the development. From March 2 they are going to catch up again, it seems.
>>
>> I do a record of the grid frequency. My timebase is a TCXO, 0.4ppm off. I
>> get a frequency value for any single sinewave, precision is 1.4*10^-4 Hz.
>>
>> Cheers
>> Detlef Schücker
>> DD4WV
>>
>> (See attached file: lostseconds.pdf)
>>
>> "time-nuts"  schrieb am 08.03.2018 02:16:55:
>>
>> Von: Gerhard Hoffmann 
>>> An: time-nuts@febo.com
>>> Datum: 08.03.2018 02:41
>>> Betreff: Re: [time-nuts] Frequency deviations in Europe affect clocks
>>> Gesendet von: "time-nuts" 
>>>
>>>
>>>
>>> Am 07.03.2018 um 22:09 schrieb Poul-Henning Kamp:
>>>
 This explains why my oven clock and the time/temperature display
> on the building outside my apartment in Switzerland are six minutes
> slow since January. It was a great mystery to me.
>
 Can you get a picture of this ?  It would be wonderful to have for

>>> future discussions...
>>> Does that help?
>>>
>>> <
>>> https://na01.safelinks.protection.outlook.com/?url=https%3A%
>>> 2F%2Fwww.flickr.com%2Fphotos%2F137684711%40N07%2F3887075044
>>> 0%2Fin%2F&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.
>>> edu%7Cea149d08d4134d49c94908d58552ea8e%7C995b093648d640e5a31
>>> ebf689ec9446f%7C0%7C0%7C636561513531276977&sdata=tOoi%
>>> 2BsnXyQjy0%2FGXCyOtOInytUmckrvoKGIO1G%2FRpnE%3D&reserved=0
>>>
>>> album-72157662535945536/
>>>   >
>>>
>>> Input to the counter is just an AC wall wart with a voltage divider to
>>>
>> 4Vpp.
>>
>>> Now, the frequency has risen to above 50.02 Hz constantly. It is in the
>>> middle of the night after all.
>>> They have to catch up.
>>>
>>> BTW I have decided to build an analog phase noise tester of my own. This
>>> weekend
>>> I did most of the mechanical things, but it is still in a kit state.
>>>
>>> The pictures are to the left of the 49 Hz-Pic.
>>> The 1-to-6 coax relays are part of the switchable lambda/4 delay line,
>>> so I can enforce
>>> quadrature everywhere above 5 MHz, including unknown amplifiers etc.
>>> Still looking for 2 more 1:6 relays.
>>>
>>> The mixers and dividers are in stereo, so I can do cross correlation in
>>> the 89441A.
>>> One of the mixer/preamp units is open, the ref oscillators will be
>>> MTI-260s on
>>> my oscillator carrier board.
>>>
>>> Have a good night,
>>> Gerhard
>>>
>>> ___
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>>>
>> https://na01.safelinks.protection.outlook.com/?url=https%3A%
>> 2F%2Fwww.febo.com%2Fcgi-bin%2Fmailman%2Flistinfo%2Ftime-
>> nuts&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Cea149d
>> 08d4134d49c94908d58552ea8e%7C995b093648d640e5a31ebf689ec9446
>> f%7C0%7C0%7C636561513531276977&sdata=WbFAlHeph%2BzrkQoiRBN4r
>> qFUp0zf5gdIeMP6LHzv%2FTw%3D&reserved=0
>>
>> and follow the instructions there.
>>>
>>
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>> mcgaw%40dartmouth.edu%7Cea1

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

[Forrest Christian (List Account)]

There is an announcement of the impending purchase on the Microchip website.

>From my perspective this is a good thing as I've been eyeing some of the
microsemi semiconductor products for some time for use in various designs
of mine and this is likely to make those products easier to incorporate due
to the microchip sales policies.

Not sure how this will work for the finished products they sell as
historically microchip has only been a semiconductor maker.  It wouldn't be
surprising to see microchip divest themselves of the assembled product
line.  I know microchip has divested themselves of small portions of
acquired businesses in the past when they didn't fit their roadmap.



On Mar 3, 2018 8:48 AM, "ewkehren via time-nuts"  wrote:

> The manager many not know but the market does and there have been
> announcements and the stock is up and for the day the fifth most active of
> all US markets. At 2 pm #2Bert Kehren
>
>
> Sent from my Galaxy Tab® A
>  Original message From: "Richard (Rick) Karlquist" <
> rich...@karlquist.com> Date: 3/3/18  9:30 AM  (GMT-05:00) To: Discussion
> of precise time and frequency measurement , Anders
> Wallin  Subject: Re: [time-nuts] Microsemi
> up for sale?
> I asked the CBT manager at Microsemi about this
> rumor and he disavowed any knowledge of this.
> He told me they were making 8 a week (not clear
> if this is just 5071A's, or includes replacement
> CBT's).  I don't remember the production ever
> being anywhere near this level.  The reason
> for the relatively brisk sales is that the risk
> of GPS spoofing means that various military and
> 3 letter agencies need to own dedicated 5071's.
> With a large installed base of 5071's, there will
> be a guaranteed market for replacement tubes.
> The US government considers the 5071A to be of
> great strategic importance and would be certain
> to "encourage" its continued production in case
> of any business reorganization.
>
> When we designed the 5071A twenty five years ago,
> it seemed that there were two safe bets:
>
> 1.  Working Cs standards (outside the lab) would
> obsoleted by what HP called "smart clocks" running
> off of GPS.
>
> 2.  Magnetic state selection, as used in the 5071A,
> would be replaced by optical pumping.  Len Cutler
> was heartbroken that HP/Agilent management wouldn't
> fund this effort.
>
> It turns out that, even now in 2018, optical pumping
> is not ready for prime time in a working standard
> because the lasers drift over time.  The 5071A's
> claim to fame is that you turn it on and it just
> works ... until it runs out of cesium.  That is
> another reason the 5071A isn't going away any time soon.
>
> Rick Karlquist N6RK
> Member: 5071A design team
>
> On 3/3/2018 1:22 AM, Anders Wallin wrote:
> > Just a change to the last part of the name then ;)
> > https://www.ft.com/content/10192a2a-1d99-11e8-956a-43db76e69936
> > "semi" -> "chip"
> >
> >
> > On Sat, Jan 27, 2018 at 1:27 AM, Clint Jay  wrote:
> >
> >> Perhaps of interest to the list
> >>
> >> https://www.theregister.co.uk/2018/01/25/microsemi/
> >>
> >> --
> >> Clint.
> >>
> >> *No trees were harmed in the sending of this mail. However, a large
> number
> >> of electrons were greatly inconvenienced.*
> >> ___
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Re: [time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block?

[Forrest Christian (List Account)]

So, I happen to have a full low-volume SMD assembly line here... for our
own products (although I did have similar thoughts to John about spinning a
couple of carrier boards for these type of parts but designed so they are
suitable for assembly on our line).

Our take on QFN's is that they're not as bad as one would imagine,
especially if one extends the pads outside of the QFN footprint so you can
have a chance of reworking them, since most re-work issues are an issue of
a bit of flux and heating the solder up to melting point.   I still try to
avoid them if at all possible, because I hate something you can't easily
inspect, and QFN's are pretty much in that category.  The problem with
inspection being that you have to generally have expensive inspection
equipment, the most common being an x-ray machine, in order to really tell
if the part is soldered correctly.  If you don't have this, you pretty much
have to rely on a functional test which can be problematic since there are
a lot of solder defects which result in boards which test fine, yet are not
truly soldered correctly - which fail in the field.

But, everytime that I've relented and used them, they've been remarkably
trouble-free, often easier to deal with than an equivalent pitch TQFP since
bridges/soldering seem to happen less often than on a leaded part, and
usually these issues clear just by applying some flux and reheating the
joints. Assuming you find the bridge/defect in the first place.

The especially troublesome QFN's are the ones with 'interior pads' since
there is no easy way to see how well they soldered, and reworking those
joints are a challenge.   The single ground mostly-thermal pad ones aren't
too bad (such as the part we're talking about), with the caveat that you
have to put some thought into how to handle the ground vias so they don't
suck the all the solder from the pad into the via holes.  This usually
means plugged vias (aka small enough that the plating fills 100% of the
hole).  In addition there is a lot of discussion about how much voiding
(unsoldered area) is acceptable on that center pad, and the answer
generally is that "it depends". But, when soldering, with a reasonable
stencil design, you're going to typically get more than enough fill to not
have any problems.

The QFN's with multiple interior pads, I've tried successfully to stay away
from, since it seems that defects are much more likely on these.  Although
there's a voltage regulator wih this pad style that I've got my eye on that
I'm seriously considering.  But that one is unique in that the center pads
share vias with perimeter pads, so you can just run a single pad all the
way from the edge under the unit, so it would still be possible to reheat
the joint.

I understand that some people have had luck hand-soldering QFN's with the
center pads by adding good sized vias where heat and possibly solder can be
applied *through* the board.  I'm not sure I would trust this for
production, though.

As far as doing this at home in a toaster oven, I wouldn't be surprised if
it was not only possible but worked well, assuming everything else was
fine.   With modern pastes and components, the soldering process is
remarkably insensitive to variations.

One hint:  If you do want to experiment, there are 'dummy components'
available which could help with the verification process and cost less than
the real chips.   If you search for "QFN44 dummy component" you'll find
topline and maybe another vendor or two.  These are definitely less
expensive than expensive parts, but in most cases, I've also discovered
that I have been able to find some other very low cost 'real' component in
the same package.

NXP has a app note at
https://www.nxp.com/docs/en/application-note/AN1902.pdf which covers the
basics of what I described above.

One final note to mention:  Many/most QFN's are moisture sensitive.   This
pretty much means that once you open the package you have a limited amount
of time to either mount them, or put them in a dry box.  (or re-package
them in a moisture proof container with an appropriate dessicant pack).
 If this doesn't happen correctly, then the part absorbs enough moisture
from the air that when you bake it, the part cracks as it turns to steam.
 This is sometimes visible, sometimes not.  Either way, is causes
reliabilty issues.

The data I have access to indicates that the SI5340A is currently rated at
MSL2, which means that the 'open time' is 1 Year (assuming normal humidity
levels).  BUT... you never know until you get the package, and even then
you should double check with the manufacturer based on the exact
manufacturing date and factory.

On Thu, Jan 25, 2018 at 2:41 PM, Hal Murray  wrote:

>
> j...@febo.com said:
> > The challenge is that the chip is a 7x7 mm 44-QFN package and really
> wants
> > to be put on a six-layer circuit board.  That's doable, but  challenging,
> > for home assembly.
>
> Can anybody comment on the toaster oven approach?
>
> Is i

[time-nuts] Trimble thunderbolt accuracy expectations

[Forrest Christian (List Account)]

A couple of weeks back I caught my thunderbolt way out of lock, and doing
some sort of weird sawtooth oscillation in the DAC and PPS reading causing
the PPS alignment to swing +-50ns or so away from correct alignment (based
on some +-10ns GPS receivers I have here).After lots of attempts at
various things, I finally issued it a 'factory reset' command and it seems
to be a lot more healthy, but I'm not convinced this is as healthy as it
should be.   In particular, I seem to be getting an ADEV around 4.2e-10 at
1 tau, and 1.5e-12 at 1e5 tau which seems too high, based on various
discussions I've found on the net.

Seems like a good excuse to finally take the time to understand this unit,
and also start down the path of trying to get as accurate of a clock here
as possible within resonable financial constraints.   I'm primarily
interested in getting a highly-accurate UTC-aligned 1PPS source.
 Alignment to UTC is the primary goal, as this is in support of various
projects which rely on UTC aligned pulses.   An accurate 10Mhz frequency
source is only a nice side effect.   I should note that the thunderbolt has
(until now) been more than adequate for past projects, but I'm always
wanting something better... sounds like lots of people on this list
understand that disease.

So...back to the issue at hand:  I'm now trying to finally figure out how
understand all of the parameters and also trying to get my head around the
interrelation between all of the parameters.   I also understand that
there's some tuning possibilities which I'm looking at as well.   I haven't
yet opened it up to see what OCXO is in it.   I'd appreciate some guidance
as to what others look for when ascertaining the health of a thunderbolt,
and what I should be expecting as far as ranges on things that matter like
ADEV.

One parameter in particular that I'm trying to figure out how to determine
is what the expected offset from UTC/GPS is, i.e. +- a certain number of
ns.   I'd like to be able to look at the unit and determine how healthy it
is, and what level of uncertainty I should expect.   I know the ADEV is
based on the deviation of the PPS signal, but it doesn't sound like it's
related to the deviation from the UTC second.   I also see the PPS
parameter up at the top in Lady Heather, but this doesn't seem like it's
what I'm looking for.   Can someone clarify this for me?

-- 
*Forrest Christian, AC7DE* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com
  

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Re: [time-nuts] HP5065 - Some OP-Amp, FB and Teflon ...

[Forrest Christian (List Account)]

I am *not* an expert on the HP5065...  In fact, I just joined so I could
learn a bit more about precision timekeeping... have various reasons for
wanting a precision clock on the bench, and trying to figure things out.

So, the following is based on past experience with similar replacements, in
other devices.I looked up the schematic for the 5065A, couldn't find
the OPA111 anywhere, so I can't be extremely specific, but:

The LT1793 in particular is marketed as a drop-in replacement for the
OPA111, although some of the specs seem worse.

TI points people toward the OPA124 and OPA627 parts. In particular the
OPA627 is interesting in that it's available in the same TO-99 package that
the OPA111 is... and has similar specs.

I was hoping to locate the OPA111 on the schematic to at least try to
understand how it was used.   If you could point me to where it is found, I
might (50% chance) be able to be more helpful as well.



On Mon, Nov 27, 2017 at 11:37 PM, Ulf Kylenfall via time-nuts <
time-nuts@febo.com> wrote:

>
> Corby,
> Thanks for the information. I was not aware of the relocated resistor.
> Yes, it is the DC feed-throughs.
> Any thaughts on a possible replacement for OPA111?
> I have also duplicated the revised A7 AC-Amplifier boardusing film
> capacitors for the notch filters and modernOP-Amps. Since I have one old A7
> board as spare, I caneasily compare the performance.
> BR
> Ulf Kylenfall - SM6GXV
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-- 
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
forre...@imach.com | http://www.packetflux.com
  

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