[time-nuts] Newbie questions

[timenut]

Hi,

I am a newbie to this list. I have downloaded the archives and read about
5,000 of the past messages. I plan on building my own GPSDO, probably using a
LEA-6T (but LEA-7T or LEA-M8T would be good if I can find one affordably). I
have a MTI 260 on order (although it could wind up being a 261 since they all
appear to ship one or the other randomly).

Currently, my resources include a DMM (well, a couple) and soldering /
desoldering stations and quite a few tools. I also have an oscilloscope that I
am currently repairing - a 400Mhz Tektronix 2465BCT analog scope. I am waiting
on the final parts from Mouser. Once that is done I need to get it calibrated.
All of that will probably take me another month. I also need to finish fixing
my cassette deck - and then to finish writing a special recording program to
use raw device drivers to get around the fact that Windows is not real time. I
interrupted that project to work on the scope.

In the meantime, I am reading the time-nuts messages (and lots of other
things) to gather information and ideas about how I am going to do this and
generally to learn more.

So, I have some questions. Let me tell you a bit about me, so that you know
the context and my limitations. I am a retired programmer. I wrote just about
everything including device drivers, operating systems, utilities, various AI
programs, telephone systems, compilers, encryption, web applications and much
more. If I need to throw 50,000 LOC at a project, no problem. I have used many
languages including quite a few different assembly languages (I have also
written an assembler). I consider myself a mathematician / programmer,
although I haven't really needed Calculus or Differential Equations for
decades, so I am pretty rusty in that area. I do more work in formal logic
than higher mathematics. But, I THINK like a mathematician. Formalism and
abstraction come naturally to me.

During my career I also helped to debug hardware during S-100 days. I have
sporadically messed with electronics off and on, informally, with no education
in the area. Now that I am retired (and have more time, but less money - it IS
a zero sum game!), I am trying to learn more about electronics and start doing
hardware projects. I have never been into model building or anything similar,
so my construction skills are lacking. I understand a lot of things in theory,
but practice still eludes me. For example, knowing a part exists or
determining which of 10,000 apparently identical parts is the "right" choice.
It can hours or even days to find the "right" connector. In many cases, the
names or descriptions are completely meaningless. That all appears to be an
experience related issue, so I will (hopefully) overcome that in time.

I have no problem with soldering / desoldering, but I haven't designed or
built my own PCB yet. I have designed / redesigned some minor circuits,
especially on the power supply side. I can follow schematics reasonably well,
but I am not comfortable with Eagle or other PCB layout programs. Every time
I have tried one of those programs, half of the parts I needed were not
available. I have started using TinyCAD which is much easier to use. So, I
have a lot to learn. But, that is basically what I do, all day, every day. I'm
the type of person that gets bored easily and quickly. As #5 said "more input,
more input"!   6.02059991327962

Paradoxically, I have no interest in time. As in time of day, day of week,
etc.. I have never had a job where I got to work on time. My philosophy has
always been "go to bed when sleepy, get up when not". I was notorious in high
school for only showing up on test day. But, I am interested in being able to
timestamp events accurately and in measuring time (and other things). I am
also interested in how a very accurate frequency source can be used in
other applications and test instruments. That brings me to my desire to build
a GPSDO and my questions.

I understand the logarithmic scaling used for voltage and power. I even
understand why voltage uses a multiplier of 20 and power a multiplier of 10.
It makes sense when working with a wide range of values. However, my DMM, my
scope and generally schematics work directly with current, voltage and watts.
So, I am constantly seeing statements like an output is 7 dBm or 13 dBm. If I
knew the actual value for 0 dBm then the basic equations would resolve the
values. However, I have not found a consistent answer for that. When I have
attempted to work values backwards from various statements, again I don't get
a consistent value (probably because those statements were approximations and
not exact values). I always see statements that an increase of 6dBm doubles
the value. It is used so often that most people forget it is an approximation.
It is 6.02059991... and sometimes, it may make a difference. Worse, the zero
value appears to be different for different applications. In some it appears
to be completel

[time-nuts] HP5370B & HP5345B Front-End IC Redesign Effort

[Perry Sandeen via time-nuts]

Hi,
Wrote: Since the front end chips are mixed signal ASIC’s, it will take more 
than a bit of time to replace them directly. Re-doing the entire front panel 
board is the most likely way to “fix”the problem. The question is - why do that 
at all? Just do a PC instrument that does the same thing as the counter with 
way less effort…..
Well, I have two reasons not to.
First I have about $1800 invested in my 3 5370’s including  the new CPU boards 
and blowing that off is not in my budget. I’ll kludge the living daylights out 
of my units before blowing off my investment.
Second, I haven’t the slightest clue on how to do a PC instrument and I have to 
many other projects to finish to learn something new.
Also there was much discussion about A and B cooling in the past and it seems 
the only things some did to their units was the addition of fan(s) on the 
cooling fins.  I had an external fan on a B I was running and the thing still 
was too hot.
IMNSHO, I believe the front end chip failure is aggravated by the high interior 
heat level.  I’m committed to a number of other projects so it will be a while 
before I can work on mine.
I’ll either rip the whole PS out and put it on another chassis, try better 3 
terminal regulators instead of the installed pass transistors, install 
switching regulator PS’s in place of the original PS, cut holes in the top lid 
and install 10 or 12 computer fans. Or a combination of the afore mentioned.
I don’t give a rat’s behind how it will look. I’m only interested in it working 
properly.  I’ve spent 50 years in the electronics industry and I will find a 
way to skin this cat. I’ve done this to other equipment before. And when done 
I’ll tell the list how I did it.
Regards,
Perrier
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Re: [time-nuts] GPS PRN 32

[Charles Steinmetz]

Magnus wrote:

Interestingly enough they did not experience issues at the same 
time, it just started about the same time.


Presumably, each rx would be affected when it added one or more 
corrupted satellites to the constellation it was using for its 
solution.  Since each rx makes those decisions independently, one 
would not expect them to exhibit problems in exact synchrony.


Best regards,

Charles


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Re: [time-nuts] GPS jumps of -13.7 us?

[xaos]

Slashdot got it.

http://it.slashdot.org/story/16/01/26/1735223/discrepancy-detected-in-gps-time

On 01/26/2016 12:20 PM, Scott Newell wrote:
> At 09:12 AM 1/26/2016, Paul Boven wrote:
>
>> Has anyone else seen GPS time jump by -13.7 usec today?
>
> My tbolt locked ntp server saw an unusual spike of about that
> magnitude just after 00:00 1-26-2016 UTC. (The bump at 4 seconds
> is from the daily backup run.)
>
>
>
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Re: [time-nuts] GPS jumps of -13.7 us?

[Magnus Danielson]

Hi,

On 01/26/2016 11:46 PM, Martin Burnicki wrote:

Paul Boven wrote:

Hi everyone,

Has anyone else seen GPS time jump by -13.7 usec today?
I just heard from several geographically quite distributed radio
observatories that they have seen their GPS receiver(s) jump compared to
their in-house standards.


We were able to track this down today at Meinberg.

The problem was that some satellites were sending invalid UTC correction
parameters. The UTC correction parameter set not only contains current
leap second information but also coefficients (A0, A1, WNt, tot) for a
polynomial used to compensate the fractional difference between GPS time
and UTC(USNO).

Normally A0 (the constant offset) is very small, close to 0. WNt and tot
give the week number (truncated to 8 bits) and second-of-week for which
A0 is valid, i.e. the reference time for the time correction parameters.
WNt is currently about 89.

Today the faulty satellites sent about 13.7 microseconds for A0, and WNt
as well as tot were both 0. So when the GPS receiver updated its UTC
correction parameters from a faulty satellite the UTC correction jumped
from close to 0 to about 13.7 microseconds, which let the UTC time step,
and when the GPS receiver received the UTC parameter set from a healthy
satellite the UTC time stepped back.

We have recorded a few of the faulty subframe words. If someone is
interested I can provide more detailed information. However, I'm
currently out of the office and don't have the information here right now.


You know I want more details. ;-)

I did see the report you guys sent to the USCG, good work there and good 
report.


I also some another report showing issues with other SVNs.

Cheers,
Magnus
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Re: [time-nuts] what is acceptable harmonic content & level for a 10Mhz standard?

[Bob Camp]

Hi

If your OCXO is putting out less than 0 dbm, it’s broke. Given the way these 
parts are treated
in the salvage loop, damage is not unusual. There are a *lot* of examples of 
surplus OCXO’s
with low output. Normally it’s a damaged output cap or something like it.  I’ve 
seen roughly half the units
in some lots come in that way ….

Bob

> On Jan 26, 2016, at 2:52 PM, walter shawlee 2  wrote:
> 
> I have been working on a compact portable 10Mhz bench standard
> using both an FE FE5680A Rb oscillator and an Oscilloquartz ovenized
> crystal oscillator.  I was curious to see how their short and long term 
> stability
> would work out, and I needed something to drive my 6502 amp to pipe the 
> signal to some bench instruments which could benefit from better master 
> references.  all of these were inexpensive ebay acquisitions, so the total 
> cost to make the package is maybe $250 plus a few weekends work and a 
> left-over but nice looking tilt-bail case & Condor 65W switching power supply.
> I drove everything from some independently, heavily post-filtered +15VDC 
> power.
> 
> to try and keep any unexpected interaction to a minimum, the outputs exit 
> though floating BNCs, so they don't have an unwanted ground loop at the case. 
>  only the FE5680A is physically grounded to the case for heatsinking, so the 
> connection is a single point.
> 
> while looking at the outputs of the two sources, I saw some surprising 20Mhz 
> harmonic content on my spectrum analyzer.  I expected a bit from the 5680A, 
> but it was actually much bigger on the OCXO, which had a chinese add-on dual 
> buffer board attached.  I had thought there might be some, so I also scored 
> some little 10Mhz BP filters at the same time and did some before/after tests.
> 
> here's what I got:
> 
> FE5680A 10Mhz (+5dBm), 20Mhz (-55dBm)  (with filter)
> 
> OCXO   10Mhz (-2dBm), 20Mhz (-35dBm) as received
> OCXO   10Mhz (-5dBm), 20Mhz (-60dBm) with filter
> 
> I hate to distribute any spurious RF around the lab, so I thought less 
> harmonic content was the better plan, although I realize that as a counter 
> time base source, it is probably irrelevant, but might play a role in my 
> 8656B RF generator as added unwanted spurs.  I was a bit disturbed by the low 
> level and harmonics from the OCXO assembly, so I thought some external 
> comments about norms were needed at this point before I go further.
> 
> what kind of harmonic content does everyone else see in their 10Mhz 
> standards?  the -5dBm level seems too low to me, I am used to 0 to +5-7dBm 
> from sources, but I have not tried to run it through the distribution amp 
> yet, so possibly that's enough.  I can try and dig into the totally 
> undocumented surface mounted chinese add-on board to improve things, and 
> increase the level, but hard to say what will happen there.
> 
> all comments and data welcome.
> all the best,
> walter
> 
> 
> 
> -- 
> Walter Shawlee 2, President
> Sphere Research Corporation
> 3394 Sunnyside Rd.,  West Kelowna,  BC
> V1Z 2V4  CANADA  Phone: (250) 769-1834
> walt...@sphere.bc.ca
> WS2: We're all in one boat, no matter how it looks to you.
> Love is all you need. (John Lennon)
> But, that doesn't mean other things don't come in handy. (WS2)
> 
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Re: [time-nuts] GPS jumps of -13.7 us?

[Martin Burnicki]

Paul Boven wrote:
> Hi everyone,
> 
> Has anyone else seen GPS time jump by -13.7 usec today?
> I just heard from several geographically quite distributed radio
> observatories that they have seen their GPS receiver(s) jump compared to
> their in-house standards.

We were able to track this down today at Meinberg.

The problem was that some satellites were sending invalid UTC correction
parameters. The UTC correction parameter set not only contains current
leap second information but also coefficients (A0, A1, WNt, tot) for a
polynomial used to compensate the fractional difference between GPS time
and UTC(USNO).

Normally A0 (the constant offset) is very small, close to 0. WNt and tot
give the week number (truncated to 8 bits) and second-of-week for which
A0 is valid, i.e. the reference time for the time correction parameters.
WNt is currently about 89.

Today the faulty satellites sent about 13.7 microseconds for A0, and WNt
as well as tot were both 0. So when the GPS receiver updated its UTC
correction parameters from a faulty satellite the UTC correction jumped
from close to 0 to about 13.7 microseconds, which let the UTC time step,
and when the GPS receiver received the UTC parameter set from a healthy
satellite the UTC time stepped back.

We have recorded a few of the faulty subframe words. If someone is
interested I can provide more detailed information. However, I'm
currently out of the office and don't have the information here right now.

Martin

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Re: [time-nuts] low noise multiplication to 100 MHz

[Cash Olsen]

About 10 years ago I demonstrated a Hot Air Reflow method that is simple
and needs no exotic tools and no heroic skills to solder surface mount
devices. I also supply the solder paste in a syringe with a modified
needle. The paste is Kester Easy Profile 256.

You can see my method at:
http://kd5ssj.com/solderpaste/smt-tools-and-process

You can order paste at: http://kd5ssj.com/solderpaste/smd-soldering

BTW the cost of the solder paste has been constant for ten years but the
cost of shipping is up more than 5x, the USPS just raised the cost of
shipping a padded envelope by about 25%.

--
S. Cash Olsen KD5SSJ
ARRL Technical Specialist

Message: 15
Date: Tue, 26 Jan 2016 01:50:47 -0500
From: Chuck Harris 
To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] low noise multiplication to 100 MHz
Message-ID: <56a71747.8040...@erols.com>
Content-Type: text/plain; charset=UTF-8; format=flowed

Hi Bert,

I have noticed that if I have the right magnification,
I can do amazing things.  Even the tiny age related
tremors that naturally occur in my hands reduce with
magnification.  The brain is a marvelous  servo mechanism.

Get a good 40x-80x zoom stereo microscope meant for
dissection, the type mounted on a boom, and I would bet
you too could deal with the small surface mount parts.

When I build with SMD, I always put all of the parts on
the top side, and use solder paste.  I used to put lots
of tiny dots out with a syringe that works a lot like a
caulking gun... only smaller.  But I found that simply
drawing a thin stripe of paste across the SMD pads
on the board, and then setting the part on the paste,
works just fine.  The solder draws towards the pads, and
leaves the space between the pins clear.  Occasionally
there will be some tiny balls sitting between the pins,
but they clean up when I clean the board with alcohol
and a brush...not that they hurt anything anyway.

The chips self center while they are floating on the
molten solder.  No need to touch them with a soldering
iron, or anything else.

I use a lab grade hot plate to bring the board up to reflow
temperature.  And I am off to the races.

For disassembly, I use an IR underboard heater, and a
hot air source... about 1/8 inch diameter, and move it
around the pin area until it melts, and then lift the
part free.

To put parts on an already populated board, I pre heat
the underside of the board to about 1/2-2/3 the way to
the solder melting temperature, and use a little gentle
hot air source to head the pads the rest of the way to
molten.  No need for soldering irons.

Practice on junk boards until it becomes natural.

-Chuck Harris

Bert Kehren via time-nuts wrote:
> We have looked at the LMK devices but with my 74 years would not try to
> solder it. There are other neat parts out there but again who is able to
> solder  them.
> Bert Kehren
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[time-nuts] Noise of LT3042 vs ECL noise (was: Generating a solid PPS from 10Mhz source)

[Attila Kinali]

Moin,

On Sun, 17 Jan 2016 17:32:58 +0100
Gerhard Hoffmann  wrote:

> BTW the extra quiet reference of the LT3042 is a current source, so 
> there is no real justification for the repeated claims here that ECL
> must be noisy because of its integrated current source.

I had a closer look at the datasheet of the LT3042 and disagree with you
on this conclusion. Yes, the LT3042 uses a current source into a resistor
as reference. But the resistor is bypassed by a HUGE ceramic capacitor.
The resulting low-pass filter has a cut-off frequency in the low hertz
region, if not sub-hertz. Or to cite the datasheet:

---
One problem that conventional linear regulators face is
that the resistor divider setting the output voltage gains up
the reference noise. In contrast, the LT3042's unity-gain
follower architecture presents no gain from the SET pin
to the output. Therefore, if a capacitor bypasses the SET
pin resistor, then the output noise is independent of the
programmed output voltage. The resultant output noise
is then set just by the error amplifier's noise -- typically
2nV/sqrt(Hz) from 10kHz to 1MHz and 0.8µVRMS in a 10Hz
to 100kHz bandwidth using a 4.7µF SET pin capacitor.
---

In contrast to that, the current sources in ECL circuits do not have a
bypass capacitor. Or rather, you cannot bypass the current source itself
as it is used as an infinitely large resistor for the differential "pairs"
in the ECL circuit.


If you decrease the value of the by-pass capacitor such that you get
a low pass cut-off frequency in the, let's say, 100Hz range, then you
should see the effect clearly in your measurements.



Attila Kinali
-- 
Reading can seriously damage your ignorance.
-- unknown
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Re: [time-nuts] what is acceptable harmonic content & level for a 10Mhz standard?

[Richard (Rick) Karlquist]

On 1/26/2016 11:52 AM, walter shawlee 2 wrote:

I have been working on a compact portable 10Mhz bench standard
using both an FE FE5680A Rb oscillator and an Oscilloquartz ovenized


It is important for a 10 MHz source to launch a pure sine wave
and also to have an accurate 50 ohm impedance at 10 MHz and its
harmonics.  This is because a sine wave is the only waveform
having the property that it is immune from distortion due to
reflections from poorly matched loads.  IE, sine wave with
multipath resolves again to a sine wave.  It is important to
have a broadband 50 ohm output impedance to absorb reflections
from loads, especially load-generated harmonics.  You didn't
ask, but you also want a lot of reverse isolation to avoid
pulling the OCXO.  All of these were addressed in the design
of the output section of the 5071A cesium standard.  It was
really quite non-trivial.  Specifically, the harmonics are
down over 80 dB.

Rick Karlquist N6RK
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Re: [time-nuts] low noise multiplication to 100 MHz

[Bryan _]

Chuck, what do you use for a hot air source. The good ones are very expensive. 
Wonder if there is something for the hobbyist. Have seen a few repair videos 
where they used just used a hot air stripper.
I had to yank a couple SMD resistors off a board the other day and had to use 
two soldering irons at each end of the resistor . If they are small enough 
you can add a glob of solder to the whole resistor, so both ends will melt.
Cheers

-=Bryan=-

> To: time-nuts@febo.com
> From: cfhar...@erols.com
> Date: Tue, 26 Jan 2016 01:50:47 -0500
> Subject: Re: [time-nuts] low noise multiplication to 100 MHz
> 
> Hi Bert,
> 
> I have noticed that if I have the right magnification,
> I can do amazing things.  Even the tiny age related
> tremors that naturally occur in my hands reduce with
> magnification.  The brain is a marvelous  servo mechanism.
> 
> Get a good 40x-80x zoom stereo microscope meant for
> dissection, the type mounted on a boom, and I would bet
> you too could deal with the small surface mount parts.
> 
> When I build with SMD, I always put all of the parts on
> the top side, and use solder paste.  I used to put lots
> of tiny dots out with a syringe that works a lot like a
> caulking gun... only smaller.  But I found that simply
> drawing a thin stripe of paste across the SMD pads
> on the board, and then setting the part on the paste,
> works just fine.  The solder draws towards the pads, and
> leaves the space between the pins clear.  Occasionally
> there will be some tiny balls sitting between the pins,
> but they clean up when I clean the board with alcohol
> and a brush...not that they hurt anything anyway.
> 
> The chips self center while they are floating on the
> molten solder.  No need to touch them with a soldering
> iron, or anything else.
> 
> I use a lab grade hot plate to bring the board up to reflow
> temperature.  And I am off to the races.
> 
> For disassembly, I use an IR underboard heater, and a
> hot air source... about 1/8 inch diameter, and move it
> around the pin area until it melts, and then lift the
> part free.
> 
> To put parts on an already populated board, I pre heat
> the underside of the board to about 1/2-2/3 the way to
> the solder melting temperature, and use a little gentle
> hot air source to head the pads the rest of the way to
> molten.  No need for soldering irons.
> 
> Practice on junk boards until it becomes natural.
> 
> -Chuck Harris
> 
> Bert Kehren via time-nuts wrote:
> > We have looked at the LMK devices but with my 74 years would not try to
> > solder it. There are other neat parts out there but again who is able to
> > solder  them.
> > Bert Kehren
> ___
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> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
  
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Re: [time-nuts] what is acceptable harmonic content & level for a 10Mhz standard?

[paul swed]

Walter that OCXO sure looks odd I would expect unfiltered to be a lot
better then that. I would guess that several possibilities exist.
The actual crystal is a 5 MHz and it feeds a doubler.
The chain has something thats gone non-linear. -5dbm seems low to me.
Oscilloquartz have a very fine reputation on time-nuts. I do not own one
nor most likely never will.
So you are right to ask and suspect.
Regards
Paul
WB8TSL

On Tue, Jan 26, 2016 at 2:52 PM, walter shawlee 2 
wrote:

> I have been working on a compact portable 10Mhz bench standard
> using both an FE FE5680A Rb oscillator and an Oscilloquartz ovenized
> crystal oscillator.  I was curious to see how their short and long term
> stability
> would work out, and I needed something to drive my 6502 amp to pipe the
> signal to some bench instruments which could benefit from better master
> references.  all of these were inexpensive ebay acquisitions, so the total
> cost to make the package is maybe $250 plus a few weekends work and a
> left-over but nice looking tilt-bail case & Condor 65W switching power
> supply.
> I drove everything from some independently, heavily post-filtered +15VDC
> power.
>
> to try and keep any unexpected interaction to a minimum, the outputs exit
> though floating BNCs, so they don't have an unwanted ground loop at the
> case.  only the FE5680A is physically grounded to the case for heatsinking,
> so the connection is a single point.
>
> while looking at the outputs of the two sources, I saw some surprising
> 20Mhz harmonic content on my spectrum analyzer.  I expected a bit from the
> 5680A, but it was actually much bigger on the OCXO, which had a chinese
> add-on dual buffer board attached.  I had thought there might be some, so I
> also scored some little 10Mhz BP filters at the same time and did some
> before/after tests.
>
> here's what I got:
>
> FE5680A 10Mhz (+5dBm), 20Mhz (-55dBm)  (with filter)
>
> OCXO   10Mhz (-2dBm), 20Mhz (-35dBm) as received
> OCXO   10Mhz (-5dBm), 20Mhz (-60dBm) with filter
>
> I hate to distribute any spurious RF around the lab, so I thought less
> harmonic content was the better plan, although I realize that as a counter
> time base source, it is probably irrelevant, but might play a role in my
> 8656B RF generator as added unwanted spurs.  I was a bit disturbed by the
> low level and harmonics from the OCXO assembly, so I thought some external
> comments about norms were needed at this point before I go further.
>
> what kind of harmonic content does everyone else see in their 10Mhz
> standards?  the -5dBm level seems too low to me, I am used to 0 to +5-7dBm
> from sources, but I have not tried to run it through the distribution amp
> yet, so possibly that's enough.  I can try and dig into the totally
> undocumented surface mounted chinese add-on board to improve things, and
> increase the level, but hard to say what will happen there.
>
> all comments and data welcome.
> all the best,
> walter
>
>
>
> --
> Walter Shawlee 2, President
> Sphere Research Corporation
> 3394 Sunnyside Rd.,  West Kelowna,  BC
> V1Z 2V4  CANADA  Phone: (250) 769-1834
> walt...@sphere.bc.ca
> WS2: We're all in one boat, no matter how it looks to you.
> Love is all you need. (John Lennon)
> But, that doesn't mean other things don't come in handy. (WS2)
>
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Re: [time-nuts] GPS PRN 32

[Magnus Danielson]

Hi,

It seems that several SVNs (PRN 2, 6, 7, 9 and 23) got feed bad data. 
This is not the first instance, it seems that single SVNs have had bad 
data the last couple of days.


When our 4 GPS receivers at work got "hit" at midnight, it got our 
attention. Interestingly enough they did not experience issues at the 
same time, it just started about the same time.


Several of my customers also reported issues. Turns out that more people 
seen this.


It will be interesting when a proper analysis comes on this.

Cheers,
Magnus

On 01/26/2016 05:43 PM, Charles Curry wrote:

Tom

This is what I sent unchecked Rich Text (HTML) now

Has anyone noticed GPS problems today?

It looks like PRN32 / SVN 23 went faulty yesterday and was taken out of service 
last night at 22:00 ZULU

http://www.navcen.uscg.gov/?Do=gpsShowNanu&num=2016008

We've seen issues with a number of timing receivers so far.

Best Regards,

Charles
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Managing Director
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All data and information contained in this e-mail is in confidence and is the 
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other work without the prior written consent of the discloser and/or copyright 
owner.

--- Original Message ---

From: "Tom Van Baak" 
To: "Charles Curry" 
Cc: "John Ackerman" 
Date: Tue, 26 Jan 2016 08:11:21 -0800
Subject: Re: GPS PRN 32

Hi Charles,

Your posting just now is completely blank (see below).
Was this an accident? Or perhaps your email client is configured for HTML-only 
instead of TEXT or TEXT+HTML.
Let me know if I can help.

Thanks,
/tvb

- Original Message -
From: "Charles Curry" 
To: "John Ackerman" 
Sent: Tuesday, January 26, 2016 7:26 AM
Subject: GPS PRN 32






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[time-nuts] what is acceptable harmonic content & level for a 10Mhz standard?

[walter shawlee 2]

I have been working on a compact portable 10Mhz bench standard
using both an FE FE5680A Rb oscillator and an Oscilloquartz ovenized
crystal oscillator.  I was curious to see how their short and long term 
stability
would work out, and I needed something to drive my 6502 amp to pipe the signal 
to some bench instruments which could benefit from better master references.  
all of these were inexpensive ebay acquisitions, so the total cost to make the 
package is maybe $250 plus a few weekends work and a left-over but nice looking 
tilt-bail case & Condor 65W switching power supply.

I drove everything from some independently, heavily post-filtered +15VDC power.

to try and keep any unexpected interaction to a minimum, the outputs exit though 
floating BNCs, so they don't have an unwanted ground loop at the case.  only the 
FE5680A is physically grounded to the case for heatsinking, so the connection is 
a single point.


while looking at the outputs of the two sources, I saw some surprising 20Mhz 
harmonic content on my spectrum analyzer.  I expected a bit from the 5680A, but 
it was actually much bigger on the OCXO, which had a chinese add-on dual buffer 
board attached.  I had thought there might be some, so I also scored some little 
10Mhz BP filters at the same time and did some before/after tests.


here's what I got:

FE5680A 10Mhz (+5dBm), 20Mhz (-55dBm)  (with filter)

OCXO   10Mhz (-2dBm), 20Mhz (-35dBm) as received
OCXO   10Mhz (-5dBm), 20Mhz (-60dBm) with filter

I hate to distribute any spurious RF around the lab, so I thought less harmonic 
content was the better plan, although I realize that as a counter time base 
source, it is probably irrelevant, but might play a role in my 8656B RF 
generator as added unwanted spurs.  I was a bit disturbed by the low level and 
harmonics from the OCXO assembly, so I thought some external comments about 
norms were needed at this point before I go further.


what kind of harmonic content does everyone else see in their 10Mhz standards?  
the -5dBm level seems too low to me, I am used to 0 to +5-7dBm from sources, but 
I have not tried to run it through the distribution amp yet, so possibly that's 
enough.  I can try and dig into the totally undocumented surface mounted chinese 
add-on board to improve things, and increase the level, but hard to say what 
will happen there.


all comments and data welcome.
all the best,
walter



--
Walter Shawlee 2, President
Sphere Research Corporation
3394 Sunnyside Rd.,  West Kelowna,  BC
V1Z 2V4  CANADA  Phone: (250) 769-1834
walt...@sphere.bc.ca
WS2: We're all in one boat, no matter how it looks to you.
Love is all you need. (John Lennon)
But, that doesn't mean other things don't come in handy. (WS2)

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Re: [time-nuts] GPS jumps of -13.7 us?

[Ed Palmer]

Here's what my Z3801A saw using Z38XX.  00:00 on the graph = 06:00 UTC.  
My location is ~N50, W104.  I don't know what SVNs were used. I'm not 
logging that data.


Ed

On 2016-01-26 11:00 AM, time-nuts-requ...@febo.com wrote:

Message: 3
Date: Tue, 26 Jan 2016 16:12:41 +0100
From: Paul Boven 
To: Discussion of precise time and frequency measurement

Subject: [time-nuts] GPS jumps of -13.7 us?
Message-ID: <56a78ce9.20...@xs4all.nl>
Content-Type: text/plain; charset=utf-8; format=flowed

Hi everyone,

Has anyone else seen GPS time jump by -13.7 usec today?
I just heard from several geographically quite distributed radio
observatories that they have seen their GPS receiver(s) jump compared to
their in-house standards.

Regards, Paul Boven.



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Re: [time-nuts] low noise multiplication to 100 MHz

[Garry Thorp]

Jim,

3) Input and output level (?)
the oscillator is a HCMOS output, so figure swinging about 3.5V


Any multiplier configuration will produce lots of different harmonics, and will 
need fairly serious filtering after it if you want a clean 100MHz.

If you have a 20MHz oscillator with CMOS output, it should produce a healthy 
component at 100MHz provided its output is reasonably symmetrical, say ~55:45 
or better. The easiest (and probably lowest noise) approach might be to extract 
the 100MHz component directly. A common-base circuit such as the attached 
sketch would probably work OK.

Rin is needed to avoid overloading the CMOS output. The input tuned circuit Q 
could be made quite high, as its ESR can be incorporated into Rin. As this 
would take very little signal current from the oscillator at 20MHz or 60MHz, 
most of the CMOS output current capability would be available at 100MHz.

A common-emitter amplifier with a tuned emitter load would take less current 
from the oscillator, but probably isn't practical if you only have 5V regulated 
supply available.

Garry


CMOS oscillator x5.pdf
Description: CMOS oscillator x5.pdf
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Re: [time-nuts] GPS PRN 32

[Charles Curry]

Tom

This is what I sent unchecked Rich Text (HTML) now

Has anyone noticed GPS problems today?

It looks like PRN32 / SVN 23 went faulty yesterday and was taken out of service 
last night at 22:00 ZULU

http://www.navcen.uscg.gov/?Do=gpsShowNanu&num=2016008

We've seen issues with a number of timing receivers so far.

Best Regards,

Charles
___
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Managing Director
Chronos Technology Ltd


http://www.chronos.co.uk/index.php/en/company-info/whos-who#CC
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Mobile: +44 (0)7786 336 001

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www.gps-world.biz
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This email has been sent to you by Chronos Technology Limited; Registered in 
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All data and information contained in this e-mail is in confidence and is the 
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owner.

--- Original Message ---

From: "Tom Van Baak" 
To: "Charles Curry" 
Cc: "John Ackerman" 
Date: Tue, 26 Jan 2016 08:11:21 -0800
Subject: Re: GPS PRN 32

Hi Charles,

Your posting just now is completely blank (see below).
Was this an accident? Or perhaps your email client is configured for HTML-only 
instead of TEXT or TEXT+HTML.
Let me know if I can help.

Thanks,
/tvb

- Original Message -
From: "Charles Curry" 
To: "John Ackerman" 
Sent: Tuesday, January 26, 2016 7:26 AM
Subject: GPS PRN 32


>

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[time-nuts] 58503A does not track

[claude . ff]

Hello list !

I have a HP 58503A who  worked fine for two years. 
After a short power cut, it does not lock on GPS. I tried some commandsn  
including :SYST:PRESET but nothing works

Here's a :SYSTEM:STATUS ? after the PRESET and after waiting a few hours :


--- Receiver Status ---

SYNCHRONIZATION ... [ Outputs Invalid ]
SmartClock Mode ___   Reference Outputs ___
   Locked TFOM 9 FFOM 3
   Recovery   1PPS TI  --
   Holdover   HOLD THR 1.000 us
>> Power-up: GPS acquisition  Holdover Uncertainty 
  Predict  --

ACQUISITION .. [ GPS 1PPS Invalid ]
Tracking: 0    Not Tracking: 6    Time 
   PRN  El  AzUTC  16:06:43 [?] 29 Feb 2016
   * 1  -- ---GPS 1PPS Invalid: not tracking
   * 6  -- ---ANT DLY  0 ns
   * 9  -- ---Position 
   *14  -- ---MODE Survey:  0% complete
   *22  -- --- Suspended: track <4 sats
   *24  -- ---INIT LAT N 596:30:43.423
  INIT LON E 596:31:10.845
ELEV MASK 10 deg   *attempting to track  +21474708.00 m  
(MSL)
HEALTH MONITOR . [ OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK

I tried to set the date with :GPS:INIT:DATE 2016,01,26 but this command has no 
effect.

Setting the LAT and LON with :GPS:POS «myposition» works.

--- Receiver Status ---
 
SYNCHRONIZATION ... [ Outputs Invalid ]
SmartClock Mode ___   Reference Outputs ___
   Locked TFOM 9 FFOM 3
   Recovery   1PPS TI  --
   Holdover   HOLD THR 1.000 us
>> Power-up: GPS acquisition  Holdover Uncertainty 
  Predict  --

ACQUISITION .. [ GPS 1PPS Invalid ]
Tracking: 0    Not Tracking: 6    Time 
   PRN  El  AzUTC  02:58:13 [?] 24 Mar 2016
   * 3  -- ---GPS 1PPS Invalid: not tracking
   * 4  -- ---ANT DLY  0 ns
   * 8  -- ---Position 
   * 9  -- ---MODE Hold
   *23  -- ---
   *29  -- ---LAT  Nblah blah
  LON  Eblah blah
ELEV MASK 10 deg   *attempting to track   HGT  +194.57 m  (MSL)
HEALTH MONITOR . [ OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK 


But the unit is still not tracking, it sees the birds because the PRN are 
changing but
does not calculate the "El" and "Az"  ...

Here is the output of  :DIAGnostic:LOG:READ:ALL? 

Log 001:20160122.00:00:00:  Log cleared
Log 002:20160122.00:00:00:  System preset
Log 003:20160122.00:00:35:  Self-test failed
Log 004:20160122.00:12:38:  Position hold mode started

As you can see, the date is 2016-01-22, it's the date when the power cut 
happened .

And when I run  :GPSYSTEM:POSITION:SURVEY ONCE, I get the same first status 
with crazy
lattidude and longitude.


Finally a self test *TST? gives +0 and the ALARM LED and the LOCK LED are off.

I've tried with a second antenna and have the same problem :-(

Can someone give me an advice for this problem ? The receiver looks dead, no ?

Thanks in advance,


Claude
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Re: [time-nuts] Z3801 misbehavior

[John Green]

Thanks guys. I'll hook it up to the regular power supply and let it cook
for a while. I have a uBlox board I want to check for jitter, but I'll need
that '3801 to check it against. The fun part will just have to wait.
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Re: [time-nuts] low noise multiplication to 100 MHz

[Chuck Harris]

One last post on this off topic subject: Eyes.

The younger folk will think eye problems amount to near
or farsightedness... maybe a little astigmatism.  The
slightly older folk (37+) will know about presbyopia...
the loss of your close working focus... your arms get
shorter.

Then there are the 60+ folks who know about a whole new
spectrum of problems.  For you the macular degeneration,
for me the detached vitreous humor from my retina.

These result in holes in the vision, or ghosts and shadows
that float into and out of view.  Fun!

Microscopes cause problems with the 60+ kinds of vision
problems because they hold the eyes steady, and accentuate
the floaters and holes.  You can't just shift your eyes
and look around them because the scope needs each eye to
be accurately fixed on axis with the optical path for it
to work.

Fortunately there is a way out of this problem, and it is
a pretty cheap one too.  The little CCD or CMOS video camera,
and an LCD monitor.  This allows your eyes to look up, down
and around on the screen, and you get the needed
magnification, but because of the way your brain works, you
won't notice the floaters, and macular holes...  You just
look around them, and your brain fills in the gaps.  You do
lose your stereo optic distance clues, but there are more
expensive ways of correcting that too.

The more expensive solution is the Mantis, a large flat
screened stereo optic microscope that is supposed to help
provide the distance clues.  I haven't used one, but I have
heard good things from those that have.  Not exactly cheap,
but getting old has its costs.

You can work in SMD electronics when you get old.

-Chuck Harris

Bert Kehren via time-nuts wrote:

Chuck
Thank you for your advice, I will print it out and when needed experiment.
We use SMD.s and two of our tem members are very good at it, I do limited
stuff  and have some tools but also a macular hole in one eye. In designs I
try to stay  with solder able SMD's and we have projects like the AD9913
which gets to the  limit what I will consider. I did not do the soldering.
Bert

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Re: [time-nuts] GPS jumps of -13.7 us?

[Scott Newell]

At 09:12 AM 1/26/2016, Paul Boven wrote:


Has anyone else seen GPS time jump by -13.7 usec today?


My tbolt locked ntp server saw an unusual spike of about that 
magnitude just after 00:00 1-26-2016 UTC. (The bump at 4 seconds 
is from the daily backup run.)


--
newell  N5TNL
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Re: [time-nuts] GPS jumps of -13.7 us?

[Tom Van Baak]

The GPSCon "International Z3801A web plot" page is still active:

http://www.realhamradio.com/GPS_websites_list.htm

Most of the entries are stale but here's a few that show the recent glitch 
nicely:

http://www.shaunmerrigan.info/timeandfreq/gpscon/gpsstat.htm
http://www.shaunmerrigan.info/timeandfreq/gpscon1/gpsstat.htm
http://www.shaunmerrigan.info/timeandfreq/gpscon2/gpsstat.htm

/tvb

- Original Message - 
From: "Poul-Henning Kamp" 
To: "Discussion of precise time and frequency measurement" 
; "Paul Boven" 
Sent: Tuesday, January 26, 2016 8:32 AM
Subject: Re: [time-nuts] GPS jumps of -13.7 us?


> 
> In message <56a78ce9.20...@xs4all.nl>, Paul Boven writes:
> 
>>Has anyone else seen GPS time jump by -13.7 usec today?
>>I just heard from several geographically quite distributed radio 
>>observatories that they have seen their GPS receiver(s) jump compared to 
>>their in-house standards.
> 
> Here is a quick plot:
> 
> http://phk.freebsd.dk/misc/20160126_gps.svg
> 
> The two receivers see the same (number of) satelites, but the jumps
> happen at widely different times.
> 
> Magnitude around 14 microseconds seems confirmed.
> 
> These are both Oncore timing receivers.
> 
> 
> -- 
> 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] GPS jumps of -13.7 us?

[Poul-Henning Kamp]

In message <56a78ce9.20...@xs4all.nl>, Paul Boven writes:

>Has anyone else seen GPS time jump by -13.7 usec today?
>I just heard from several geographically quite distributed radio 
>observatories that they have seen their GPS receiver(s) jump compared to 
>their in-house standards.

Here is a quick plot:

http://phk.freebsd.dk/misc/20160126_gps.svg

The two receivers see the same (number of) satelites, but the jumps
happen at widely different times.

Magnitude around 14 microseconds seems confirmed.

These are both Oncore timing receivers.


-- 
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] GPS jumps of -13.7 us?

[Tom Van Baak]

Paul,

I've received inquires about the 13 us jump since 8 PM last night (PST).

Possibly related: http://www.navcen.uscg.gov/?Do=gpsShowNanu&num=2016008

Check your logs to see if your receiver is using SVN23/PRN32.

/tvb

- Original Message - 
From: "Paul Boven" 
To: "Discussion of precise time and frequency measurement" 
Sent: Tuesday, January 26, 2016 7:12 AM
Subject: [time-nuts] GPS jumps of -13.7 us?


> Hi everyone,
> 
> Has anyone else seen GPS time jump by -13.7 usec today?
> I just heard from several geographically quite distributed radio 
> observatories that they have seen their GPS receiver(s) jump compared to 
> their in-house standards.
> 
> Regards, Paul Boven.

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Re: [time-nuts] GPS jumps of -13.7 us?

[Attila Kinali]

On Tue, 26 Jan 2016 16:12:41 +0100
Paul Boven  wrote:

> Has anyone else seen GPS time jump by -13.7 usec today?
> I just heard from several geographically quite distributed radio 
> observatories that they have seen their GPS receiver(s) jump compared to 
> their in-house standards.

Do you have references to those reports? 
The only one i've seen is from the Finnish Alto University Observatory:
https://blogs.aalto.fi/metsahovi/gps-kellonajan-outo-hyppays-huomattiin-metsahovissa/#.VqecHW-Vtpg


Attila Kinali

-- 
Reading can seriously damage your ignorance.
-- unknown
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Re: [time-nuts] Z3801 misbehaving

[paul swed]

Good comment on leaving it on for a long time if the almanac has been lost.
You see nothing accept the green pwr led and I have seen 48 hours to lock.
I added a batter 2 X AA and that keeps the almanac and enhances startup.
But nothing like a modern 30 sec or less receiver.
WB8TSL

On Tue, Jan 26, 2016 at 5:30 AM, Artek Manuals 
wrote:

> John
> I am no expert but I have been playing ( A lot) with my Z3801 during the
> last month, after having it in storage for 15 years !
>
> What software program are you running, under what operating system?
> Can you see the satellites being tracked in the receiver status window in
> SATSTAT? on the computer?
>
> I have had very poor success using the Belkin USB to serial adapters And
> picked up a laptop running a real RS-232 port and Windows XP.
>
> Without being able to see commands and the Receiver Status on the computer
> it can be a bit hard to troubleshoot blind this beast.
>
> In my case I still get glitchy things going on with Z38xx program by the
> German fellow and I had to revert back to SATSTAT to do set up. Then I
> revert back to Z38xx for its graphics displays of the data once the
> receiver settles in
>
> Dave
>
>
>
>
>
>
>  On 1/25/2016 8:54 PM, John Green wrote:
>
>> After running continuously for about 3 years at work, I stored my Z3801
>> for
>> a little over a year. I recently took it out of storage and when I hooked
>> it up, all I get is a power on light. The front panel LEDs light in
>> sequence and the 6 inside blink red once and then the last one blinks
>> continuously as always. Thing is, it never locks on GPS. I even left it on
>> over night. When run on 27 volts, it starts out at about 1.1 amps, then
>> after about 10 minutes, goes up to 1.26 amps. Then, after about 30 more
>> minutes, it settles down to .88 amps and stays there. The OCXO gets warm.
>> I
>> haven't checked for 10 MHz out, but I am pretty sure it is there. I hooked
>> it up to my netbook but I get no response from it at all. I am using one
>> of
>> those USB to serial devices and it used to work. I am looking for a PC
>> with
>> a real serial port to try. I know the antenna is good. It works with one
>> of
>> those Symmetricom GPSDO cards.  Having heard about the evils of tantalum
>> capacitors for years, I replaced them all except for those on the GPS
>> receiver board itself. All the test points that call out a voltage read
>> correctly. I'm thinking of trying a new GPS board next. I have had this
>> thing a long time and it has always just worked. Any ideas what the
>> problem
>> is?
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>>
>>
>
> --
> Dave
> manu...@artekmanuals.com
> www.ArtekManuals.com
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
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>
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> and follow the instructions there.
>
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Re: [time-nuts] GPS jumps of -13.7 us?

[Poul-Henning Kamp]

In message <56a78ce9.20...@xs4all.nl>, Paul Boven writes:

>Has anyone else seen GPS time jump by -13.7 usec today?
>I just heard from several geographically quite distributed radio 
>observatories that they have seen their GPS receiver(s) jump compared to 
>their in-house standards.

My logging indicates that there has been some kind of disturbances
today, I'll see what I can pull out of the data.

What puzzles me is that two receivers, 100km apart, does not show it
happening at the same time.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
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Re: [time-nuts] GPS jumps of -13.7 us?

[Tim Shoppa]

Indeed, multiple Z3801A GPSCON pages show an impulse step for by the amount
you describe. I would describe the graphs as showing a positive TI step
followed by negative TI step. My reading of the graphs shows that it is
consistent with the 13.7 usec you describe.

Am attempting to attach some EFC/TI graphs. Everyone seems to configure
their scales a little differently.

Tim N3QE



On Tue, Jan 26, 2016 at 10:12 AM, Paul Boven  wrote:

> Hi everyone,
>
> Has anyone else seen GPS time jump by -13.7 usec today?
> I just heard from several geographically quite distributed radio
> observatories that they have seen their GPS receiver(s) jump compared to
> their in-house standards.
>
> Regards, Paul Boven.
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Re: [time-nuts] Z3801 misbehaving

[Charles Steinmetz]

John wrote:


I even left it on over night.


It may need longer than overnight to assemble an almanac and 
initialize everything.  Leave it on for a week before you panic.


Best regards,

Charles


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Re: [time-nuts] Z3801 misbehaving

[Artek Manuals]

there are two versions a 24V version and a 48V version ... If you look 
at the back of the Z3801 there will be a "dot" on which voltage your 
unit is powered for . ...The 48V version is the more common.  Since your 
unit is going through the full LED cycle on 27V supply I suspect that 
you do have the correct voltage.


Since I know your are running Z38xx software I would revert back to the 
SATSTAT to get things settled down. I have had command string errors 
with Z38xx which I dont get with SATSTAT


Dave
NR1DX
ArtekManuals


On 1/26/2016 7:56 AM, paul swed wrote:

John
The 3801s are getting very old at this point. I know mine has started to
show a loss of lock occasionally on the oscillator. Intermittent problems
are very tough.
What jumps out to me is the 27 volts. That seems low as I recall. I run at
48 V. I understand there were several models made so what I mention may not
be correct.
The other thing is there is a small regulator on the power board.
I know on my unit one of the regulated outputs on the switcher failed and I
simply replaced it with another small block switcher. Though as you mention
your voltages appears fine.
Regards
Paul
WB8TSL

On Mon, Jan 25, 2016 at 8:54 PM, John Green  wrote:


After running continuously for about 3 years at work, I stored my Z3801 for
a little over a year. I recently took it out of storage and when I hooked
it up, all I get is a power on light. The front panel LEDs light in
sequence and the 6 inside blink red once and then the last one blinks
continuously as always. Thing is, it never locks on GPS. I even left it on
over night. When run on 27 volts, it starts out at about 1.1 amps, then
after about 10 minutes, goes up to 1.26 amps. Then, after about 30 more
minutes, it settles down to .88 amps and stays there. The OCXO gets warm. I
haven't checked for 10 MHz out, but I am pretty sure it is there. I hooked
it up to my netbook but I get no response from it at all. I am using one of
those USB to serial devices and it used to work. I am looking for a PC with
a real serial port to try. I know the antenna is good. It works with one of
those Symmetricom GPSDO cards.  Having heard about the evils of tantalum
capacitors for years, I replaced them all except for those on the GPS
receiver board itself. All the test points that call out a voltage read
correctly. I'm thinking of trying a new GPS board next. I have had this
thing a long time and it has always just worked. Any ideas what the problem
is?
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Re: [time-nuts] Z3801 misbehaving

[Artek Manuals]

On 1/26/2016 12:54 AM, Hal Murray wrote:

I'm thinking of trying a new GPS board next.

A bad GPS board won't prevent communication to the main CPU.

You might try capturing the output when you power it on.  It sends out
something.  I forget what, probably the ID string..  If that doesn't work,
try a scope.  You might have the PC running at the wrong baud rate.


Hal makes a good point the Z3801 RS232 port is not exactly standard make 
sure the COM port settings in Z38xx and in the set up on the computer 
(CONTROL PANEL) are set to 19200baud, 7, 1, ODD. BOTH have to be set up 
as these are not computer industry "standard"


Dave
NR1DX
ArtekManuals

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Re: [time-nuts] low noise multiplication to 100 MHz

[Bert Kehren via time-nuts]

Chuck
Thank you for your advice, I will print it out and when needed experiment.  
We use SMD.s and two of our tem members are very good at it, I do limited 
stuff  and have some tools but also a macular hole in one eye. In designs I 
try to stay  with solder able SMD's and we have projects like the AD9913 
which gets to the  limit what I will consider. I did not do the soldering.
Bert
 
 
In a message dated 1/26/2016 10:00:51 A.M. Eastern Standard Time,  
cfhar...@erols.com writes:

Hi  Bert,

I have noticed that if I have the right magnification,
I can  do amazing things.  Even the tiny age related
tremors that naturally  occur in my hands reduce with
magnification.  The brain is a  marvelous  servo mechanism.

Get a good 40x-80x zoom stereo  microscope meant for
dissection, the type mounted on a boom, and I would  bet
you too could deal with the small surface mount parts.

When I  build with SMD, I always put all of the parts on
the top side, and use  solder paste.  I used to put lots
of tiny dots out with a syringe that  works a lot like a
caulking gun... only smaller.  But I found that  simply
drawing a thin stripe of paste across the SMD pads
on the board,  and then setting the part on the paste,
works just fine.  The solder  draws towards the pads, and
leaves the space between the pins clear.   Occasionally
there will be some tiny balls sitting between the pins,
but  they clean up when I clean the board with alcohol
and a brush...not that  they hurt anything anyway.

The chips self center while they are  floating on the
molten solder.  No need to touch them with a  soldering
iron, or anything else.

I use a lab grade hot plate to  bring the board up to reflow
temperature.  And I am off to the  races.

For disassembly, I use an IR underboard heater, and a
hot air  source... about 1/8 inch diameter, and move it
around the pin area until it  melts, and then lift the
part free.

To put parts on an already  populated board, I pre heat
the underside of the board to about 1/2-2/3 the  way to
the solder melting temperature, and use a little gentle
hot air  source to head the pads the rest of the way to
molten.  No need for  soldering irons.

Practice on junk boards until it becomes  natural.

-Chuck Harris

Bert Kehren via time-nuts wrote:
>  We have looked at the LMK devices but with my 74 years would not try  to
> solder it. There are other neat parts out there but again who is  able to
> solder  them.
> Bert  Kehren
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[time-nuts] GPS jumps of -13.7 us?

[Paul Boven]

Hi everyone,

Has anyone else seen GPS time jump by -13.7 usec today?
I just heard from several geographically quite distributed radio 
observatories that they have seen their GPS receiver(s) jump compared to 
their in-house standards.


Regards, Paul Boven.
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Re: [time-nuts] Schlumberger FA2527 ocxo

[gianni]

> Hi
> I have a OCXO marked Schlumberger Adret 622 used in Adret 4101A Frequency 
> standard receiver
> I do not know if it is similar but performance seem OK
> It is a cube of about 70 mm with DB9 output connector ; frequency is 5MHz 
> with external pot adj.
> The ADEV seem good: data here 
> 
> schematics here:
> 
> 
> 
> 

Gianni
Il 25 gennaio 2016 12:32:29 +01:00, Luca Dal Passo  ha 
scritto:

> Hi group,
> Does anyone know something about the Schlumberger type FA2527 5MHz
> OCXO?
> It seems to be a good unit, with mumetal shield, coarse and fine frequency
> adj multiturn pots, fine temperature trimmer, good voltage regulator, good
> assembly and internal cylindrical thermal chamber surronded by a wire
> resistence (double oven?).
> It was used in Schlumberger electronic counters in the seventies or
> eighties as a high stability option.
> I'm trying to understand pin out and supply voltage, but I wish to know
> some more information about functions of pins, and specifications.
> Nothing found on the net.
> Thank you in advance!
> Luca
> iw2lje
> Milano
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Re: [time-nuts] Z3801 misbehaving

[paul swed]

John
The 3801s are getting very old at this point. I know mine has started to
show a loss of lock occasionally on the oscillator. Intermittent problems
are very tough.
What jumps out to me is the 27 volts. That seems low as I recall. I run at
48 V. I understand there were several models made so what I mention may not
be correct.
The other thing is there is a small regulator on the power board.
I know on my unit one of the regulated outputs on the switcher failed and I
simply replaced it with another small block switcher. Though as you mention
your voltages appears fine.
Regards
Paul
WB8TSL

On Mon, Jan 25, 2016 at 8:54 PM, John Green  wrote:

> After running continuously for about 3 years at work, I stored my Z3801 for
> a little over a year. I recently took it out of storage and when I hooked
> it up, all I get is a power on light. The front panel LEDs light in
> sequence and the 6 inside blink red once and then the last one blinks
> continuously as always. Thing is, it never locks on GPS. I even left it on
> over night. When run on 27 volts, it starts out at about 1.1 amps, then
> after about 10 minutes, goes up to 1.26 amps. Then, after about 30 more
> minutes, it settles down to .88 amps and stays there. The OCXO gets warm. I
> haven't checked for 10 MHz out, but I am pretty sure it is there. I hooked
> it up to my netbook but I get no response from it at all. I am using one of
> those USB to serial devices and it used to work. I am looking for a PC with
> a real serial port to try. I know the antenna is good. It works with one of
> those Symmetricom GPSDO cards.  Having heard about the evils of tantalum
> capacitors for years, I replaced them all except for those on the GPS
> receiver board itself. All the test points that call out a voltage read
> correctly. I'm thinking of trying a new GPS board next. I have had this
> thing a long time and it has always just worked. Any ideas what the problem
> is?
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Re: [time-nuts] Z3801 misbehaving

[Artek Manuals]

John
I am no expert but I have been playing ( A lot) with my Z3801 during the 
last month, after having it in storage for 15 years !


What software program are you running, under what operating system?
Can you see the satellites being tracked in the receiver status window 
in SATSTAT? on the computer?


I have had very poor success using the Belkin USB to serial adapters And 
picked up a laptop running a real RS-232 port and Windows XP.


Without being able to see commands and the Receiver Status on the 
computer it can be a bit hard to troubleshoot blind this beast.


In my case I still get glitchy things going on with Z38xx program by the 
German fellow and I had to revert back to SATSTAT to do set up. Then I 
revert back to Z38xx for its graphics displays of the data once the 
receiver settles in


Dave





 On 1/25/2016 8:54 PM, John Green wrote:

After running continuously for about 3 years at work, I stored my Z3801 for
a little over a year. I recently took it out of storage and when I hooked
it up, all I get is a power on light. The front panel LEDs light in
sequence and the 6 inside blink red once and then the last one blinks
continuously as always. Thing is, it never locks on GPS. I even left it on
over night. When run on 27 volts, it starts out at about 1.1 amps, then
after about 10 minutes, goes up to 1.26 amps. Then, after about 30 more
minutes, it settles down to .88 amps and stays there. The OCXO gets warm. I
haven't checked for 10 MHz out, but I am pretty sure it is there. I hooked
it up to my netbook but I get no response from it at all. I am using one of
those USB to serial devices and it used to work. I am looking for a PC with
a real serial port to try. I know the antenna is good. It works with one of
those Symmetricom GPSDO cards.  Having heard about the evils of tantalum
capacitors for years, I replaced them all except for those on the GPS
receiver board itself. All the test points that call out a voltage read
correctly. I'm thinking of trying a new GPS board next. I have had this
thing a long time and it has always just worked. Any ideas what the problem
is?
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Dave
manu...@artekmanuals.com
www.ArtekManuals.com


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Re: [time-nuts] low noise multiplication to 100 MHz

[Bob Camp]

Hi



> On Jan 25, 2016, at 8:36 PM, Gerhard Hoffmann  wrote:
> 
> Am 25.01.2016 um 18:20 schrieb Graham / KE9H:
>> There are clock distribution parts designed to do this low noise frequency
>> conversion and distribution.
>> 
>> Consider TI  LMK04100
>> 
>> 
>> 150 fs class jitter.
>> 
> But only if you integrate the noise only from 12 kHz offset to 20 MHz.
> It is a telecom spec.

You take the phase noise over that range and calculate the jitter from the 
phase noise. 
There is no “phase” (as in audio phase) information in the phase noise 
information you collect. There is just 
amplitude. Since you do not have angle information, you have to make some 
assumptions
about how the noise in each region sums up. 

How much of a difference can that be? Take a look at how the Fourier components 
of an impulse
add up. The angle of the components can matter quite a bit. Keep the same 
amplitudes, but fiddle
the angles between the components — you get a very different waveform. 

The calculation has the nice property that you *can* do the math with normal 
data. Run on 
broadband noise it works pretty well. When you get into noise regions that 
*may* have 
correlated noise (say from a modulation process). 

So, yes, there are a number of questions you need to ask when you see a jitter 
spec. A
number done by the formula will be very different 12 KHz to 20 MHz compared to 
1 Hz to 
100 KHz. The directly measured noise may be different from either number.

Bob 


> 
> regards, Gerhard
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Re: [time-nuts] low noise multiplication to 100 MHz

[Chuck Harris]

Hi Bert,

I have noticed that if I have the right magnification,
I can do amazing things.  Even the tiny age related
tremors that naturally occur in my hands reduce with
magnification.  The brain is a marvelous  servo mechanism.

Get a good 40x-80x zoom stereo microscope meant for
dissection, the type mounted on a boom, and I would bet
you too could deal with the small surface mount parts.

When I build with SMD, I always put all of the parts on
the top side, and use solder paste.  I used to put lots
of tiny dots out with a syringe that works a lot like a
caulking gun... only smaller.  But I found that simply
drawing a thin stripe of paste across the SMD pads
on the board, and then setting the part on the paste,
works just fine.  The solder draws towards the pads, and
leaves the space between the pins clear.  Occasionally
there will be some tiny balls sitting between the pins,
but they clean up when I clean the board with alcohol
and a brush...not that they hurt anything anyway.

The chips self center while they are floating on the
molten solder.  No need to touch them with a soldering
iron, or anything else.

I use a lab grade hot plate to bring the board up to reflow
temperature.  And I am off to the races.

For disassembly, I use an IR underboard heater, and a
hot air source... about 1/8 inch diameter, and move it
around the pin area until it melts, and then lift the
part free.

To put parts on an already populated board, I pre heat
the underside of the board to about 1/2-2/3 the way to
the solder melting temperature, and use a little gentle
hot air source to head the pads the rest of the way to
molten.  No need for soldering irons.

Practice on junk boards until it becomes natural.

-Chuck Harris

Bert Kehren via time-nuts wrote:

We have looked at the LMK devices but with my 74 years would not try to
solder it. There are other neat parts out there but again who is able to
solder  them.
Bert Kehren

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[time-nuts] The cross-correlation catastrophe

[Magnus Danielson]

Fellow time-nuts,

Over a year and a half or so, we have been starting to grasp the various 
aspects of the cross-correlation catastrophe. This consists of two 
properties, one is the insertion of anti-correlated noise into the two 
channels, and then when cross-correlated it produced a subtracting 
"energy" reducing the level and even inverting the sign. Thus, there is 
a bias in the estimation and overoptimistic or even seemingly physically 
impossible (until you understand the mechanics). This have been 
occupying the mind of some of the best folks we have in the field.
Just interacting and discussing this with some of them have been a great 
learning experience. Anyway, here is a write-up that covers it sufficiently:


http://arxiv.org/abs/1512.06160

So, now you know why I look suspiciously at too low noise-levels.

Cheers,
Magnus
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[time-nuts] low noise multiplication to 100 MHz

[Mark Sims]

Actually not hard to do...  lay out circuit board (free version of Eagle),  
have boards fab'd at Oshpark.com or your favorite Chinese proto shop (I like 
gojgo.com).   Have solder paste stencil made at oshstencils.com.  Squeege 
solder paste down with a credit card.  Place components by hand.  Reflow board 
with a modified toaster oven,  electric skillet,  hot air tool, etc.

If you want to get anywhere in electronics these days,  you really need to get 
set up to do simple SMD work.  It's not hard or expensive.   The days of point 
to point wiring of vacuum tubes to terminal strips be looong gone.  
Through-hole and DIP packages are not far behind.

---
> There are other neat parts out there but again who is able to 
solder  them. 
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Re: [time-nuts] Z3801 misbehaving

[Hal Murray]

> I'm thinking of trying a new GPS board next.

A bad GPS board won't prevent communication to the main CPU.

You might try capturing the output when you power it on.  It sends out 
something.  I forget what, probably the ID string..  If that doesn't work, 
try a scope.  You might have the PC running at the wrong baud rate.


-- 
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