Re: [time-nuts] Fwd: HP 53131A Power Off Mod

[Wayne Holder]

*Important Update:* due to a mistake in my thinking, I had to upgrade the
fuse I added to a 220V, 3A model to match the fuses on the internal
switching power supply.  My original plans were to mount the fuse on the
power supply PCB and use it only to fuse the small power adapter used to
power the relay.  But, when there was not enough space, I decided to use
the in-line fuse adapter, instead.  Completely overlooking the fact that
the in-line fuse would then need to handle the full power load.

The project page at
https://sites.google.com/site/wayneholder/hp-53131a-power-off-mod has been
updated accordingly.  Sorry for the mistake and I hope this hasn't
inconvenienced anyone.

*Wayne*



On Fri, May 18, 2018 at 4:56 PM, Wayne Holder 
wrote:

> The PCBs and Parts arrived and, after putting everything together and
> testing it, it all seems to work fine.  And, to document everything, I've
> put up a web page at my web site that describes the mod and how to
> implement it:
>
>   https://sites.google.com/site/wayneholder/hp-53131a-power-off-mod
>
> I had two spare board sets left.  One is claimed, but if someone would
> like the other set, send me your address and I'll send them your way.
>
> Wayne
>
> On Mon, May 7, 2018 at 10:27 PM, Tim Tuck  wrote:
>
>> Hi Wayne,
>>
>> Congrats on a nice simple mod !
>>
>> I have both a 53131 and 181 in need of these :)
>>
>> Can you share the gerbers for your PCBs and then I can cut them out on my
>> mill.
>>
>> I could probably make a few for any interested Australians, to save on
>> cross pond postage.
>>
>> thanks
>>
>> Tim
>>
>> On 8/05/2018 9:08 AM, Wayne Holder wrote:
>>
>>> I recently purchased a surplus HP 53131A and was surprised to see that
>>> it's
>>> designed to stay partially powered on, with the fan running, even when
>>> the
>>> power switch is in standby.  The manual says this is for timebase
>>> temperature stability but, since I plan to use with my Trimble
>>> Thunderbolt
>>> as the reference source, I don't really need this feature.  So, I decided
>>> to see if I could change this.
>>>
>>
>>
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Re: [time-nuts] Fwd: HP 53131A Power Off Mod

[Wayne Holder]

The PCBs and Parts arrived and, after putting everything together and
testing it, it all seems to work fine.  And, to document everything, I've
put up a web page at my web site that describes the mod and how to
implement it:

  https://sites.google.com/site/wayneholder/hp-53131a-power-off-mod

I had two spare board sets left.  One is claimed, but if someone would like
the other set, send me your address and I'll send them your way.

Wayne

On Mon, May 7, 2018 at 10:27 PM, Tim Tuck  wrote:

> Hi Wayne,
>
> Congrats on a nice simple mod !
>
> I have both a 53131 and 181 in need of these :)
>
> Can you share the gerbers for your PCBs and then I can cut them out on my
> mill.
>
> I could probably make a few for any interested Australians, to save on
> cross pond postage.
>
> thanks
>
> Tim
>
> On 8/05/2018 9:08 AM, Wayne Holder wrote:
>
>> I recently purchased a surplus HP 53131A and was surprised to see that
>> it's
>> designed to stay partially powered on, with the fan running, even when the
>> power switch is in standby.  The manual says this is for timebase
>> temperature stability but, since I plan to use with my Trimble Thunderbolt
>> as the reference source, I don't really need this feature.  So, I decided
>> to see if I could change this.
>>
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
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Re: [time-nuts] Anybody have suggestions for time related science fair projects?

[Wayne Holder]

Using a pendulum to measure gravity requires precision timekeeping.
Wikipedia has a nice discussion of this at
https://en.wikipedia.org/wiki/Pendulum#Gravity_measurement

There are number of very clever techniques developed long ago, such as
Henry Kater's design for a reversible, dual pivot pendulum that made it
possible to get quite precise measurements starting about the 1820s.  Then,
around 1835 Friedrich Bessel found ways to simplify calibration of Kater's
design and even cancel out errors due to air drag.  More interestingly,
gravity measuring pendulums became not of the earliest ways used to
standardize the measure of length, which shows how nearly all efforts at
standardization ultimately rely on accurate timekeeping.

Wayne
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Re: [time-nuts] Fwd: HP 53131A Power Off Mod

[Wayne Holder]

Thanks!   I plan to publish the Gerber files and make them available to fab
at OSH Park as part of an a article I'll put up on my webpage at
https://sites.google.com/site/wayneholder/ but I want to make sure
everything works as expected before I do.  I'm still waiting for parts and
the PCBs to show up and I want to make sure every things works safely, as
AC voltages are involved.  So, it make take a week, or two before I'll know
if I need to fix anything, or redo one of the PCBs.

Wayne

On Mon, May 7, 2018 at 10:27 PM, Tim Tuck  wrote:

> Hi Wayne,
>
> Congrats on a nice simple mod !
>
> I have both a 53131 and 181 in need of these :)
>
> Can you share the gerbers for your PCBs and then I can cut them out on my
> mill.
>
> I could probably make a few for any interested Australians, to save on
> cross pond postage.
>
> thanks
>
> Tim
>
> On 8/05/2018 9:08 AM, Wayne Holder wrote:
>
>> I recently purchased a surplus HP 53131A and was surprised to see that
>> it's
>> designed to stay partially powered on, with the fan running, even when the
>> power switch is in standby.  The manual says this is for timebase
>> temperature stability but, since I plan to use with my Trimble Thunderbolt
>> as the reference source, I don't really need this feature.  So, I decided
>> to see if I could change this.
>>
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
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Re: [time-nuts] TCVCXO Adjustment

[Wayne Holder]

> The application is time stamping separate free running devices, in this
> case different video and audio recorders.  So the absolute time is
> arbitrary, but all the devices in use have to agree on the rate of time
> progression for as long as they are being used together.
> The typical requirement is that all the free running devices have timecode
> which will be aligned within one video frame, so ca. 33ms, at the end of
> the time of use.
> So for example, you are making some kind of video, you put all the
> timecode devices together and get their time synchronized, at which point
> they get separated and connected to various audio and video recording
> devices to output a timecode signal that the video and audio devices
> record along with their primary recordings, so that later you can line up
> the recordings from different machines and match same recording from
> different locations, angles, etc. and know they were from the same time.
> You want the last work of the day to still be synchronized to within
> closer than 33ms, so the maximum time you want to be able to work without
> getting your timecode generators back together to synchronize defines your
> drift rate which defines your acceptable accuracy.
> From common specifications it seems that the commercial products converged
> on 24 hours as the  use time limit, so 33ms/24 hours -> 0.033s/86400s ~
> 0.4ppm
>
> Yes, in principle you could use an arbitrary clock rate as well as an
> arbitrary  starting time, but that could only work if all the devices were
> exactly the same rate, so if you have to adjust the devices anyway, and
> some may be coming from 3rd parties that you don't have access to prior to
> use, then the only practical approach is for everyone to calibrate their
> devices to standard rate.
>

Yes, exactly,  You've described my use case much better than I did.  Thanks.


> I'll let the original poster ponder on whether GPS on board is a good
> thing or not, but I think you cannot count on GPS being available in use
> (could be inside a steel building, or a steel reinforced concrete
> building, with no RF reception), so you would still need a local
> oscillator which could hold the rate tightly enough to guarantee less than
> 33ms of phase drift over the course of a day.  Maybe you could relax that
> to "working day" and say it's only over 12 hours, not 24 hours.
>

As you point out, given the need to potentially interoperate with existing
timecode systems and the issue of problematic indoor reception, additional
power consumption, initial lock in time, etc., I think trying to use a GPS
in real time high create more problems than is solves.  But, having it
built in could make off-line calibration easier.


> What I think makes this potentially interesting to time-nuts is that the
> time requirements are pretty loose by time-nuts standards, but potentially
> some of the tricks that people come up with for getting ns level accuracy
> on hobby budgets could be applied to this to find a way for non-nuts (or
> at least not-yet-nuts) to get started on a really low budget.


That was exactly what I was hoping for when I placed my initial post.
While I've been following this list for many years, I still consider myself
a novice "nut" as there are still many, many things I still don't
understand about precision timekeeping.  I understand the basic idea behind
frequency calibration, but I don't really know how to account for all the
potential sources of error and handle them accordingly.  As I think I
mentioned before, I started out by reading this NIST doc
, which starts out
talking about the relationship between the measurement period and measure
phase error to the frequency offset.  So, my simplistic ideas for
calibration are, as follows:

Idea 1: Use a relative long timebase to measure the frequency offset and
tweak the DAC by one bit value at a time until the correction seems to
converge on a range of values and then call that calibrated. But, this
could take a long time and doesn't really give a way to tell the user how
long the calibration might take to complete.

Idea 2: Start with a short timebase, tweak until things seem to converge,
then shift to a longer timebase and repeat, as needed, to increase
accuracy.  It seems like this should be faster, but it's still seems like a
crude approach.

Idea 3: Come up with some sort of calculation (?) that takes into
consideration the accuracy and stability of the timebase and the
manufacturer's specs for the TCVCXO and use this to optimize the step 2
approach by setting limits on the starting and ending measurement periods
and perhaps the step size of the tweaks.  But, how do I know the accuracy
and stability of the reference timebase?

Wayne


On Sat, Apr 14, 2018 at 1:43 PM, Chris Caudle  wrote:

> On Sat, April 14, 2018 8:37 am, Bob kb8tq wrote:
> > big an issue as the TCXO. If it's a single location and the time is
> > arbitrary, then ma

Re: [time-nuts] TCVCXO Adjustment

[Wayne Holder]

Again, thanks for all the great feedback and suggestions.

> Are you familiar with these devices which I just found this week?
> https://tentaclesync.com/products

Yes, that's one of the lower cost commercial units available.  Another is
the NanoLockiIt by Ambient
,
which is company that's been making timecode products for many years.
Compared to more traditional prices for timecode generators, these are
relatively inexpensive at about $300.  However you need at least two, or
more generators to be useful, so that adds up pretty fast for an amateur
videographer, or starving film school student.  In contrast,  BOM for the
design I'm working on is less than $30 (the TCVCXO being, by far, the
most expensive part.)

My plan is to also write a desktop application, probably in Java to make it
portable, that the person building the devices could use to perform the
initial calibration and also setup various options.  So, the NTP-based
solution is attractive in that it doesn't require any additional hardware.
I'm a Mac user so, after a bit of reading the NTP implementation on the
Mac, I tried a few experiments.  Typing "ntpq -p" in the terminal
app produced this response:

 remote   refid  st t when poll reach   delay   offset
jitter

==

*usdal2-ntp-001. .GPSs.   1 u  428 1024  377   51.1311.944
1.153

and typing  "ntpq -c rl" printed out:

associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync,

version="ntpd 4.2.8p6@1.3265 Fri Feb  5 17:38:17 UTC 2016 (124.60.2~39)",

processor="x86_64", system="Darwin/16.7.0", leap=00, stratum=2,

precision=-20, rootdelay=51.131, rootdisp=34.160, refid=17.253.2.125,

reftime=de7ba9c1.937e5f86  Fri, Apr 13 2018 15:12:17.576,

clock=de7badf7.39f8d36a  Fri, Apr 13 2018 15:30:15.226, peer=7077, tc=10,

mintc=3, offset=1.944153, frequency=25.163, sys_jitter=0.00,

clk_jitter=0.745, clk_wander=0.001

I believe that the "precision" of -20 value on the 4th line is supposed to
be interpreted as 2^-20 seconds which, if my math is correct, works out to
be a precision of about 1 PPM. Is that correct?  If so, it would seem like
I should be able to use my system's internal clock to perform a "tweak" in
around 10,000 seconds, or a little less than 3 hours.  Does this seem
correct, or have I missed something?

Alternately, if I included a GPS receiver in the design, the whole process
could be done within the device, which would probably be the easiest
approach to calibration for the person building one.  This would increase
the cost and make the device larger, but users could then maintain
calibration by periodically keeping them plugged in for a few hours.  Or,
perhaps I could just design a 2nd board for a GPS "calibrator" module that
could be plugged into the timecode generators to calibrate them.  Hmm...
lots to think about.

Wayne
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Re: [time-nuts] TCVCXO Adjustment

[Wayne Holder]

First, thanks for all the comments and suggestions,  It's given me a lot to
think about and research.

Based on the feedback I've received, I've started to investigate using the NTP
server approach suggested by Chris Caudle.  I also found this NIST Paper
 to be very useful, as it
gave me some insight into the measurement period needed to achieve a given
accuracy in the DUT given a certain level of deviation in the reference
used.  But, I think further reading will be required before I can reduce
this approach to a plan.  I anyone knows of additional info on using NTP to
calibrate precision oscillators, I'd appreciate hearing about it.

The basic unit of measurement for Longitudinal Timecode is the video frame
rate, or approximately 30 fps, depending on the video medium in use.
Current commercial Timecode Generators make claims like having a drift
of only 1 frame over 24 hours, so that's been my target for my design.   Based
on my math, I think a drift of only 1/30th of a second in 24 hours is
perhaps +/-0.5 PPP, or so, but someone please correct me if I'm wrong.
  Another solution used with older, less accurate timecode generators is to
periodically resync (or "Jam Sync") the different timecode generators to
the master timecode generator thoughout the day but, while I'm not a video
production expert, I think think this is a less desirable solution.

Using a GPS, as suggestion by Adrian Godwin, is also an option, as the PPS
signal could be used as a calibration reference.   Cheap, consumer GPS
modules have gotten quite cheap and, based on my own experience
using various uBlox modules, some can even function fairly well indoors
under some conditions.  However, I seem to recall some discussion here some
time back about the relative reliability of the PPS signal in some
situations.  I'll have to dig back though the archives and see if I can
learn anything from those threads.

To provide some additional details on my project for those that
are interested, the current plan is to build everything into a USB Stick
form factor.  The USB connection would be used to configure internal
options (frame rate, etc.), charge the internal Li-Poly battery and
also, potentially, perform the calibration.  The time code signal would
be output from a 3.5mm phone connector, so the suggestion to connect this
to the audio input of the computer doing the calibration also makes sense,
as this would take USB latency out of the picture (assuming that the sound
interface in the PC is not just implemented via a chip on the USB bus.)

Wayne
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[time-nuts] TCVCXO Adjustment

[Wayne Holder]

I'm designing a small, portable, SMPTE LTC Timecode Generator
 as an open source/hardware
project for amateur filmmakers and videographers.  LTC Timecode is
typically recorded on the audio tracks of cameras and sound recorders so
the video and sound comments can be automatically sync'd later.  I'm
planing on using a small, SMD TCVCXO such as the LFTVXO075806Cutt
,
which is spec'd at a frequency tolerance or +/- 1 PPM and a frequency
stability of 0.28 PPM and a yearly aging of +/- 1 PPM max/year which, to
me, seems pretty impressive for a part that costs about $8.

Since the TCVCXO includes a voltage control input, my plan is to also add
a 12-Bit Digital-to-Analog Converter with EEPROM Memory, such as the
Microchip MCP4725

to
provide a way to initially check and calibrate the frequency after surface
mount soldering and also later to compensate for aging.  But since this is
intended as an open source/hardware project rather than a commercially
manufactured one, I've been pondering how someone building the device would
be able to easily and reliably calibrate it.

I'm basing the design around the Arduino, so the device could, in theory,
use the USB Serial connection as a way to connect to a calibration program
running on a PC.  I have a few idea on how to attempt to do this, but this
is new territory for me, so I'm asking for advice and/or thoughts on how
feasible this might be.  Is this a crazy, impractical idea given that all
the builder will probably have available to perform the calibration is a
regular PC and an Internet connection, or is there a way to make it work?

Wayne
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Re: [time-nuts] Replacement A9 boards for the HP 5065A

[Wayne Holder]

>> The only thing I could provok, was that almost all capacitors I
>> tried were sensitive to touch.

Most ceramic caps are sensitive to "micro phonics" via the piezoelectric
effect, which can translate mechanical stress into electrical noise.


https://e2e.ti.com/blogs_/archives/b/precisionhub/archive/2014/12/19/stress-induced-outbursts-microphonics-in-ceramic-capacitors-part-1

Wayne


On Mon, Feb 26, 2018 at 2:05 PM, Poul-Henning Kamp 
wrote:

> 
> In message  gmail.com>, paul swed writes:
>
> >I reverse engineered the system and guess what cap was bad? The
> integrator.
> >So not being all that smart, I hooked 2 X 10 UF caps in series. Been
> >working like a champ for 18 years.
>
> That capacitor isn't nearly as important as people think.
>
> The input signal to the integrator is continuous and jump-free and
> the relevant timeconstant is sub-second.  Dielectric absorption
> doesn't matter when there are no voltage jumps.
>
> We all tune the EFC of the Xtal to set the meter to zero CONTROL
> voltage, which means there is no voltage for the capacitor to leak,
> so that doesn't matter either,
>
> If you pick a capacitor with a couple of hundred volts rating, its
> leakage current will be less than the air and the PCB near it anyway.
>
> When I experimented, I could hardly find *any* property that mattered
> for that capacitor, not even the exact capacitance, because the
> adjustment procedue handles that.
>
> The only thing I could provok, was that almost all capacitors I
> tried were sensitive to touch.
>
> I didn't establish if this was mechanical (and if so if it was the
> capacitor or something else on the board) or if it was thermal
> (capacitors have astounding tempcos).
>
> HP tied two O-rings around the capacitor they choose, I pressume
> that is a clue that they found something similar.
>
> The biggest issue is probably that most of the relevant capacitors
> are square blocks, like for instance TDK/KEMET B32774D8505K.
>
> TDK/KEMET C4GAJUD4500AA3J could be an option, but I suspect it
> is too big to fit in the existing PCB.
>
> Either way, cheap and plenty available.
>
> --
> 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] NEO-7M various modes

[Wayne Holder]

uBlox has a utility called u-center
 that's a free
download.  You can use it to configure the various output options (and
enable and disable different messages) and a then save this config back to
the module as the start up default.

Wayne

On Sat, Oct 28, 2017 at 3:12 PM, jimlux  wrote:

> I've got 4 NEO-7M-C modules hooked up to 7 beaglebone greens, side by
> side, and they're not behaving the same..
>
> I've got gpsd running, and I'm looking at the output of cgps and/or
> gpsmon, as well as ppstest
>
>
> Some emit NMEA sentences, others binary (ublox?) strings?
>
> Some get a fix and start toggling the 1pps line, others don't.
>
> Is there some command string one can send to them to put them into a known
> state (cold reset?) - the one that's working the best (I.e. has a fix AND
> toggles 1pps) seems to be putting out binary strings (when viewed with
> gpsmon).
>
>
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Re: [time-nuts] LPRO-101 BITE (~lock) Signal Always Low

[Wayne Holder]

The signal on pin 9 starts at about 7.2 volts then slowly increments up to
14.5 volts over a period of about 138 seconds.  It then seems to stay stuck
at 14.5 volts and only repeats the cycle if I power down,w wait and then
power back on.

Wayne

On Tue, Mar 22, 2016 at 3:23 PM, Bob Camp  wrote:

> Hi
>
> I’ve always found that pin 9 (EFC monitor) gave you a pretty good idea of
> the lock status.
>
> Bob
>
> > On Mar 22, 2016, at 8:43 AM, Wayne (gmail) 
> wrote:
> >
> > The BITE signal is the only way to to know if it has a lock...
> >
> > Wayne
> >
> >> On Mar 22, 2016, at 4:37 AM, Bob Camp  wrote:
> >>
> >> Hi
> >>
> >> There are probably a dozen or more things that contribute to the BITE
> output. It could be
> >> a regulator out of range. It also could be the VCXO nearing tune limit.
> If the unit locks up and
> >> seems to work, I’d ignore it and move on.
> >>
> >> Bob
> >>
> >>> On Mar 21, 2016, at 9:42 PM, Wayne Holder 
> wrote:
> >>>
> >>> I have a surplus LPRO-101 that seems to power up OK.  The power draw
> starts
> >>> at 1.7 Amps and then, after a few minutes, drops down to 600 mA, or so
> and,
> >>> after this startup, the output shows a 10.000 MHz signal thats 's
> >>> accurately as I can measure it.  The lamp voltage is 6.2 volts, which
> seems
> >>> within spec.  However, the BITE signal that's supposed to indicate lock
> >>> with a LOW level is always LOW and never changes.  The docs say that
> BITE
> >>> signal should start at a HIGH level to indicate no lock and then drop
> to a
> >>> LOW when lock is obtained.  So, this behavior seems all wrong.
> >>>
> >>> I opened the case and observed the purple glow of the lamp and probed
> >>> around IC U401, which buffers the BITE signal, and saw the same signal
> LOW
> >>> level.  U401 is getting 5 volt power and the inputs to the AND gate
> used as
> >>> a buffer for the BITE signal match what I'd expect.  But, lacking a
> proper
> >>> schematic, I'm not sure how to trace this back to the problem.  Has
> anyone
> >>> ever seen a symptom like this with an LPRO101?
> >>>
> >>> Wayne
> >>> ___
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Re: [time-nuts] LPRO-101 BITE (~lock) Signal Always Low

[Wayne Holder]

I don't currently have a way to accurately measure the frequency of the
output, but my assumption is that oscillator is running, but not locked.  I
did some more poking around and found that the crystal volts monitor (pin
9) starts low (around 4 volts) and then slowly rises as the unit runs.  It
rises to about 14 volts and then stops.  So, this may be a similar problem
to what you described.  However, lacking proper schematics, I'm not sure
where to look next.

Wayne

On Tue, Mar 22, 2016 at 8:43 AM, iovane--- via time-nuts  wrote:

> Wayne,
>
> are you sure your LPRO actually locks? You say you have measured 10.000 MHz
> but you don't mention the other decimals. Some years ago I characterized
> some
> LPROs of mine, and from my notebook I take that, on one sample for
> instance,
> prior to lock the frequency swept up and down between (about) 9.999860 and
> 10.000230. Such a span was rather typical among units. A faulty unit of
> mine
> remained stuck at the upper limit without reversing the sweep. This was
> due to
> a faulty resistor in one of the two (upper) voltage comparator circuits.
> Anyway
> I don't know if this would affect the BITE, but I suggest you to check the
> other decimals.
>
> Antonio I8IOV
>
> >
> >The BITE signal is the only way to to know if it has a lock...
> >
> >Wayne
> >
> >> On Mar 22, 2016, at 4:37 AM, Bob Camp  wrote:
> >>
> >> Hi
> >>
> >> There are probably a dozen or more things that contribute to the BITE
> output. It could be
> >> a regulator out of range. It also could be the VCXO nearing tune limit.
> If
> the unit locks up and
> >> seems to work, I’d ignore it and move on.
> >>
> >> Bob
> >>
> >>> On Mar 21, 2016, at 9:42 PM, Wayne Holder 
> wrote:
> >>>
> >>> I have a surplus LPRO-101 that seems to power up OK.  The power draw
> starts
> >>> at 1.7 Amps and then, after a few minutes, drops down to 600 mA, or so
> and,
> >>> after this startup, the output shows a 10.000 MHz signal thats 's
> >>> accurately as I can measure it.  The lamp voltage is 6.2 volts, which
> seems
> >>> within spec.  However, the BITE signal that's supposed to indicate lock
> >>> with a LOW level is always LOW and never changes.  The docs say that
> BITE
> >>> signal should start at a HIGH level to indicate no lock and then drop
> to a
> >>> LOW when lock is obtained.  So, this behavior seems all wrong.
> >>>
> >>> I opened the case and observed the purple glow of the lamp and probed
> >>> around IC U401, which buffers the BITE signal, and saw the same signal
> LOW
> >>> level.  U401 is getting 5 volt power and the inputs to the AND gate
> used
> as
> >>> a buffer for the BITE signal match what I'd expect.  But, lacking a
> proper
> >>> schematic, I'm not sure how to trace this back to the problem.  Has
> anyone
> >>> ever seen a symptom like this with an LPRO101?
> >>>
> >>> Wayne
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[time-nuts] LPRO-101 BITE (~lock) Signal Always Low

[Wayne Holder]

I have a surplus LPRO-101 that seems to power up OK.  The power draw starts
at 1.7 Amps and then, after a few minutes, drops down to 600 mA, or so and,
after this startup, the output shows a 10.000 MHz signal thats 's
accurately as I can measure it.  The lamp voltage is 6.2 volts, which seems
within spec.  However, the BITE signal that's supposed to indicate lock
with a LOW level is always LOW and never changes.  The docs say that BITE
signal should start at a HIGH level to indicate no lock and then drop to a
LOW when lock is obtained.  So, this behavior seems all wrong.

I opened the case and observed the purple glow of the lamp and probed
around IC U401, which buffers the BITE signal, and saw the same signal LOW
level.  U401 is getting 5 volt power and the inputs to the AND gate used as
a buffer for the BITE signal match what I'd expect.  But, lacking a proper
schematic, I'm not sure how to trace this back to the problem.  Has anyone
ever seen a symptom like this with an LPRO101?

Wayne
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Re: [time-nuts] UBlox GPSDO

[Wayne Holder]

Thanks to everyone for all the great replies.  I figured that the 10 MHz
output would have a fair bit of jitter/phase noise, but I figured I could
use something like a SiLabs Si5317 to clean it up, as per this app note:

  https://www.silabs.com/Support%20Documents/TechnicalDocs/AN513.pdf

Page 4 of the app note says it "*can accept a noisy reference clock at any
frequency from 1 to 710 MHz and provide two ultra-low jitter (0.3 ps rms,
12 kHz to 20 MHz) output clocks at the same frequency.*"  Thats seems
decent to me, but I'm a novice at this.  Anyone have any thoughts, or
caveats on this plan?

Wayne
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[time-nuts] UBlox GPSDO

[Wayne Holder]

According to page 51 of the protocol manual for the UBlox NEO-M* series GPS
modules, the timepulse can be programmed to output a 10 MHz signal rather
than a 1 PPS signal:


http://www.u-blox.com/images/downloads/Product_Docs/u-bloxM8_ReceiverDescriptionProtocolSpec_(UBX-13003221)_Public.pdf

I'm curious if anyone has tried this.  Seems like a possible way to get an
inexpensive GPSDO, as these modules are very inexpensive.

Wayne
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Re: [time-nuts] Sources for Mission Time Clock

[Wayne Holder]

I think that display was built using modules like this:

  http://www.decadecounter.com/vta/articleview.php?item=511

I see them on e-bay from time to time under "in-line readout", but they're
rather expensive and you'd need quite a few,  If you can settle for 7
segment, a modern display you could use is:

  https://www.sparkfun.com/products/8530

Or, perhaps these:


http://www.seeedstudio.com/depot/7-Segment-Display-3-Inches-Green-p-1224.html

But, 7 segment just doesn't quite capture that retro feel, IMO.

Wayne

On Sun, Jan 11, 2015 at 7:30 AM, Martin A Flynn 
wrote:

> I am looking for a GMT/GET mission time clock  that has the following
> characteristics:
>
>  * Reads T minus prior to launch or deployment,  T plus after.
>  * Second display for GMT.
>  * Simulating it on a PC display would be OK, would prefer an LED/LCD
>version for wall mounting
>
> There is a example of what I am looking for in the background of this
> photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg   .   We have
> NTP, IRIG-B, and a 1 PPS source to work with.
>
> Any suggestions on a cost-effective way to accomplish this?
>
> Cheers
> Martin Flynn
>
>
>
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Re: [time-nuts] Si5351A

[Wayne Holder]

The specs for period, cycle-to-cycle and phase jitter are on page 6 of the
data sheet, which is here:

  http://www.adafruit.com/datasheets/Si5351.pdf

Wayne

On Tue, Nov 11, 2014 at 12:49 PM, Joseph Gray  wrote:

> Some of you have probably already heard of this new clock generator chip
> from Si. News of a board with this chip from Adafruit just came up on a
> local Amateur list today. A quick Google shows that some folks have used
> this chip in homebrew SSB rigs.
>
> My concern would be that when this chip generated frequencies that required
> non-integer PLL ratios, that the jitter would be unacceptable for SSB use,
> and even worse for CW.
>
> As for the Adafruit board, they are using a crystal spec'ed for 30ppm
> accuracy and stability. Not something I'd want to use in a radio. Perhaps
> the "C" version of the chip, fed by a TCXO.
>
> What do you think about the jitter issue?
>
> Joe Gray
> W5JG
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Re: [time-nuts] Divide by five

[Wayne Holder]

I do a lot of work with SMD parts and would be happy to solder up and
SOIC-16 version of the 74AC161, such as this one:


http://www.digikey.com/product-search/en?pv633=35&k=74AC161&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25

onto a dip break out board, such as this one:

  https://www.adafruit.com/products/1207

Or, if you need something more complex, I do a lot of PCB design using OSH
Park  and I'd be happy to whip up a simple PCB for
you.  It takes a few weeks to turn around a board, but it's a very
economical service ($5 a square inch for three copies.)

Wayne

On Fri, Nov 7, 2014 at 1:12 PM, Joseph Gray  wrote:

> I need to divide a 125 Mhz clock by five. I have looked on Mouser and every
> chip I find is either obsolete or in SMT. Can anyone recommend a chip that
> is fast enough and comes in DIP?
>
> Joe Gray
> W5JG
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Re: [time-nuts] New Guy, has HP 5061A with DATUM 7105A tube seeks advice

[Wayne Holder]

> http://www.artekmanuals.com has a nice scan of the manual if you can't
> find a clean copy online.  You will need to become familiar with the manual
> sooner or later.
>

So, I ordered the manual from Artek and got a download link, but could
never get the manual to download.  The download instructions said I could
not use Safari, or Chrome, so that left me with Firefox, as I'm a Mac
user.  But, no matter what I tried, the download kept asking me for a user
and password to save the file.  I could read it, but not save it.  So, I
emailed to complain and got back this bit of snark:

*FOLLOW THE INSTRUCTIONS  the left click /right click  stuff is important,
large secure files ( this one is 60+MB) behave differently than small PDF's
this is because of the way Adobe and the browser share page memory*

*Also make sure you are using Adobe reader AFTER the download not during.
the idea is DOWNLOAD and SAVE the  view, If you are viewing during the
downloaded you are not really downloading ..a common error*
*Over 200 people have downloaded files in the last 30 days without incident*

*If this doesn't make sense to you in the MAC world we are happy to refund
your money and you can reorder a CD in the mail*


So, tried again several times, following his instructions exactly but, no
result.  I documented the steps I followed and emailed back (rather
snarkily, too) that his instructions didn't work.  I also called up a
friend with a PC and asked him to comer over and help me out.  But, by the
time the arrived, the seller, Artek, without any further response,
cancelled my order, refunded my money and deactivated the download link.

So, taking him at his word, I ordered a copy on CD from eBay (from the same
seller.)  But, a few minutes later, I got a response back from eBay saying
that my order had been cancelled by the seller.  Hmm...

So, can anyone point me to another source for this manual.  My serial
number begins with 2248A, so I need the manual that goes with this serial
range.

Wayne
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Re: [time-nuts] New Guy, has HP 5061A with DATUM 7105A tube seeks advice

[Wayne Holder]

> If you get the tube working, you should use a counter or Lissajous display
> with a GPS or rubidium standard to preset it to the correct resonance peak
> frequency for lockup.  The tube will probably be pretty noisy at first.  If
> it also has weak beam current, which is common, it will be very difficult
> to find the right peak without cheating.
>

I have a Trimble Thunderbolt GPS Disciplined Clock.  Is that going to be
good enough to set the correct resonance peak frequency for lockup?

BTW, thanks for the link to a source for a manual.  I've ordered a copy for
my serial number range.

Wayne
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[time-nuts] New Guy, has HP 5061A with DATUM 7105A tube seeks advice

[Wayne Holder]

I recently picked up a 5061A surplus, but have no idea whether it works or
not.  The first hurdle is getting a power cord, but I'm still waiting for
the proper connector to show up (the first one I ordered had the wrong
orientation on the 3 pins.)  In the meantime, I've been reading though what
materials I can find online in order to figure out how to  try and safely
turn it on and see if the tube is OK, or dead.

However after removing the top cover, I can see that my unit doesn't seem
to contain the typical kind of cesium tube assembly I see in the HP docs
I've found online.  Instead, it has a tube made by DATUM with the following
markings on the label:

Model: 7105A
Serial: 9951991226
Part No: 03667-501
Oven Temp: 92 degrees C
Oven Monitor Therm: 101 Ohms
EMV: 2000 DC
NSN __ 5960 01214 7475

Can anyone tell me about this model and why it might have a DATUM tube
rather than the kind I see in the HP oc?  Also, any advice on how to safely
check it out?

I bought this thing out of curiosity but, upon looking inside at all the
various dials and switches and multi-turn potentiometers, I find I'm rather
intimated by it, even though I have a fairly decent background in
electronics.

Wayne
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