Re: [time-nuts] Internal 5 volt switching regulator on some "non-programmable" FE-5680A's

[David]

On Sun, 8 Jan 2012 14:23:02 -0800, Orin Eman 
wrote:

>On Sun, Jan 8, 2012 at 1:51 PM, Clint Turner  wrote:
>
>> Hello,
>>
>> After posting a few days ago about one of my '5680A's having the voltage
>> converter installed - but not connected - I've done a bit of
>> reverse-engineering and sleuthing around and (probably) have a fairly
>> complete picture of what it would take to populate that section of the
>> board.  That information may be found here:
>>
>> http://ka7oei.com/10_MHz_**Rubidium_FE-5680A.html
>>
>> This page is a work in progress, using my LPRO-101 page as a template and
>> unashamedly stealing a good chunk of its content - most of which is
>> directly applicable, anyway!
>>
>
>Are you sure about those resistor values?   They look like 5.11K and 5.62K
>(standard 1% values) to me.

I agree. Besides not requiring rare and expensive 4 significant digit
precision resistors which just happen to match the marking of the
standard 1% resistors, the nonstandard 12.95K and 11.15K on the
schematic would yield 5.23 volts.  5.62K and 5.11K will yield 5.08
volts from the nominal 2.42 volt reference on the LT1376.  The 5 volt
resistor selection in the data sheet would have been closer but maybe
they wanted the extra 7 millivolts or were compensating for the
feedback bias pin current.

If noise was so important I wonder why they did not use a lower noise
switching regulator or the LT1375 which supports oscillator
synchronization.

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

Re: [time-nuts] Simple GPSDO

[David]

On Mon, 09 Jan 2012 03:05:36 +0100, Magnus Danielson
 wrote:

>On 12/31/2011 08:15 AM, Charles P. Steinmetz wrote:
>> I know the thread began with a request for a "simple" DIY GPSDO, and
>> this may not be quite as simple as some might like. However, PPS
>> discipline is generally the simplest and most universal scheme from the
>> standpoint of interfacing to whatever GPS engine one has available. The
>> PRS10 has a clever system for PPS disclipine, using time-tagging for
>> phase detection, that mitigates the usual shortcomings of PPS discipline
>> and should be suitable for PIC/FPGA implementation.
>>
>> As implemented by SRS, the discipline parameters are more than
>> sufficiently adjustable for any need. For a homebrew version, the VCO
>> would be the quartz VCXO or Rb of your choice. The pre-filter (which is
>> selectable in the PRS10) would be a great help in dealing with the
>> jitter in a GPS PPS signal. PPS locking is discussed at pp. 14-18 of the
>> 2003 and 2005 manuals. (The manuals and Rev. H schematic are readily
>> available on the web.)
>
>The feedback is really just the PPS counter 0-999 modeled, and any 
>interpolation can be added without loss of generality. The time-tagging 
>is thus just sampling the state of the counter, and optionally add 
>interpolator value.
>
>You also want to have a quick-align that will reset the counter to 
>quickly jump into phase, before entering normal loop. That will save you 
>a lot of lock-in time as the phase will be in line... and worst-case 
>phase error can be half a second, so worst-case will 5 milion cycles 
>needs to be skewed, and doing that on the oscillator isn't very 
>time-efficient and causes for one hell of a initial phase error.

The design published in QST a couple years ago divided 5 MHz
oscillator by 16 to about 312 kHz and then did the phase comparison.

http://www.rt66.com/~shera/QST_GPS.pdf

>The pre-filtering exponential averager and PI-regulator is very cheap to 
>implement in a PIC, AVR or whatever. Just leave enough bits in there.
>
>I think a simple CPLD or FPGA will pull it off. You need 24 bit for 
>counting, 24 bit for time-stamp and a few more for logic. You can 
>compress the range for the time-stamp, as you only need to know "too 
>high", "too low" and a fairly small in-range value range. If you allow 
>for +/- 10 us error you only need 200 values... so there is only 8 bits.

For a simple design after frequency locking, I am leaning more toward
triggering a time to voltage converter off of the PPS output to
measure the phase and feeding that directly into a charge to voltage
integrator to adjust the oscillator.  The only digital state change is
from frequency to phase locking.

In a complex design, I would use the same time to voltage conversion
but include a calibration cycle and digitally filter in a PIC or
similar.  That would also allow direct evaluation of the PPS source.

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

Re: [time-nuts] Temperature and signal amp for 'Bay FE-5680A?

[David]

On Tue, 10 Jan 2012 21:57:49 +1300, Bruce Griffiths
 wrote:

>Hal Murray wrote:
>>
>> The TADD-3 uses 3 AC drivers in parallel, each going through a 51 ohm 
>> resistor.  Changing those resistors to 150 ohms should work.  Maybe a bit 
>> lower to account for the impedance in the drivers.  I'd probably check it 
>> with a scope.
>>
>That approach doesn't do anything for the Vcc and GND bounce exhibited 
>by the driver chip.
>GND and Vcc bounce is the cause of the high frequency ringing exhibited 
>by the TADD-3 outputs.
>This ringing can even be observed at the outputs of inverters whose 
>inputs are tied low or high in the same package
>
>Damping the crossover current induced transient in the supply leads 
>(bondwire and lead frame) inductance is one way to minimise this.
>A small resistor in series with the Vcc pin often works well, the 
>resistor value being chosen for near critical damping.
>
>Another problem with the TADD-3 is the sharing of a driver chip by 
>different input frequencies which leads to intermodulation between the 2 
>outputs.

I have never seen that much ground bounce before so assumed it was a
termination problem.  Was the driver chip decoupling inadequate?  That
at least would be easy enough to fix.

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

Re: [time-nuts] FE-5680A arrived

[David]

On Wed, 11 Jan 2012 08:35:56 -0600, Bob Smither 
wrote:

>Joseph Gray wrote:
>> I'm not seeing a PPS on either of these. All I see is about 17 mV P-P
>> of noise that looks like a multi-stepped sine wave. I'm using a TDS
>> 340 scope.
>
>I can see the 1 usec, 1pps on mine, but only if I use an analog storage scope.
>Although my HP54000 series scope triggers at 1PPS, for the life of me I cannot
>get it to display the 1 usec pulse :-(.

You might need to darken the oscilloscope environment or use a viewing
hood.  Some analog non-storage oscilloscopes, either because of design
or age, are not going to be able to display a short pulse at 1 second
intervals.  I tested this on my old but in good condition 2230 and it
could display it dimly in normal room light but my older worn 7603 can
not.

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

Re: [time-nuts] FE-5680A arrived

[David]

On Wed, 11 Jan 2012 08:37:02 -0800, Chris Albertson
 wrote:

>On Tue, Jan 10, 2012 at 10:11 PM, Joseph Gray  wrote:
>> I'm not seeing a PPS on either of these. All I see is about 17 mV P-P
>> of noise that looks like a multi-stepped sine wave. I'm using a TDS
>> 340 scope.
>>
>
>PPS is likely there.  I can't see it  on my Tek 465B scope either.

The TDS340 is a digital storage oscilloscope.  It should have no
problem at all displaying the pulse if it is there.

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

Re: [time-nuts] FE-5680A Mechanical Question

[David]

How would a GPSDRbO work?  Phase lock the DDS output to the GPS? Phase
lock a VCXO to the GPS and then phase lock to the RbO on loss of GPS
lock?

On Wed, 11 Jan 2012 22:55:58 -0600, "J. L. Trantham" 
wrote:

>Bill, Brian, Bill, and Peter,
>
>Thanks for the info.  All I need now is a 'project' to incorporate the unit
>into.
>
>In the back of my mind, I have the thought of a 'box' that will be battery
>powered or 110 VAC powered (perhaps with an internal SLA battery) and
>include a GPSDO and Rb unit (possibly a GPSDRbO) for the purpose of a
>'reference' for portable operation in the microwave regions.

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

Re: [time-nuts] FE-5680A Mechanical Question

[David]

On Wed, 11 Jan 2012 22:44:47 -0800, Hal Murray
 wrote:

>> How would a GPSDRbO work?
>
>The same as if you were building a GPSDO using a quartz oscillator.  Since 
>the Rb has better long term stability, you can use a longer time constant on 
>the filter.

But how do you adjust the RgO output frequency?  That's why I asked if
A DDS would be used.

Nevermind.  I just found it.  The RgO cell can be frequency adjusted
magnetically.

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

Re: [time-nuts] FE-5680A Mechanical Question

[David]

I was more interested in the technical details of how to adjust the
output of a RbO without sacrificing the short and long term stability.
I have seen a few designs that used a DDS to generate the 10 MHz
output which lends itself to this but they all suffer from DDS and
tuning noise.  I see now that the RbO can be adjusted with an external
magnetic field.

On Thu, 12 Jan 2012 07:34:44 -0600, "J. L. Trantham" 
wrote:

>David,
>
>I have been following discussions on the list about a GPSDRbO for a year or
>so.  Some interesting challenges and probably best implemented in a 'stable'
>environment rather than portable operation but as best I can tell, it would
>require a very stable and good antenna location, stable and clean power, and
>I was thinking of using something like an LPRO-101 with an Ext C Field
>input, a Shera type controller, and a GPS timing receiver, though, I suspect
>there are likely to be some 'multi-tasking' receivers out there that will
>look at several sources including GPS, GLOSNASS, etc.
>
>While the project might be fun, for portable work, it is likely far easier
>and probably just as good (almost), to use a Tbolt.
>
>In any event, something to think about for the future.
>
>Joe
>
>-Original Message-----
>From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>Behalf Of David
>Sent: Wednesday, January 11, 2012 11:12 PM
>To: Discussion of precise time and frequency measurement
>Subject: Re: [time-nuts] FE-5680A Mechanical Question
>
>
>How would a GPSDRbO work?  Phase lock the DDS output to the GPS? Phase lock
>a VCXO to the GPS and then phase lock to the RbO on loss of GPS lock?
>
>On Wed, 11 Jan 2012 22:55:58 -0600, "J. L. Trantham" 
>wrote:
>
>>Bill, Brian, Bill, and Peter,
>>
>>Thanks for the info.  All I need now is a 'project' to incorporate the 
>>unit into.
>>
>>In the back of my mind, I have the thought of a 'box' that will be 
>>battery powered or 110 VAC powered (perhaps with an internal SLA 
>>battery) and include a GPSDO and Rb unit (possibly a GPSDRbO) for the 
>>purpose of a 'reference' for portable operation in the microwave 
>>regions.
>
>___
>time-nuts mailing list -- time-nuts@febo.com
>To unsubscribe, go to
>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.
>
>
>___
>time-nuts mailing list -- time-nuts@febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

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

Re: [time-nuts] FE-5680A Mechanical Question

[David]

I thought maybe they applied some kind of complicated phase locked
loop frequency and phase addition or subtraction to the RbO output.  I
did not know that the RbO itself was so easily tuned.

A tuning loop for the DDS is how the noisy design worked.  It is not
clear to me if the phase noise was caused by low DDS tuning word
resolution or the DDS itself.  The SRS design locks the RbO to the GPS
1PPS with a time constant of up to 18 hours and then phased locks an
OCXO to generate the 10 MHz output.

Oddly enough, I ran into a similar problem in lack of tuning
resolution when I designed the source for the frequency to voltage
converter of my napkin GPSDO.  I ended up with a reciprocal DDS (as
best as I can describe it) to generate a low frequency high resolution
frequency source.

On Thu, 12 Jan 2012 10:43:15 -0500 (EST), ewkeh...@aol.com wrote:

>Bringing out the C field in my estimation does not effect long or short  
>term. External magnetic field I think is a joke. An other option is a loop 
>that  generates a tuning word for the DDS but that means your steps are 7 E-13.
>Bert Kehren
> 
> 
>In a message dated 1/12/2012 10:34:10 A.M. Eastern Standard Time,  
>davidwh...@gmail.com writes:
>
>I was  more interested in the technical details of how to adjust the
>output of a  RbO without sacrificing the short and long term stability.
>I have seen a  few designs that used a DDS to generate the 10 MHz
>output which lends  itself to this but they all suffer from DDS and
>tuning noise.  I see  now that the RbO can be adjusted with an external
>magnetic field.
>
>On  Thu, 12 Jan 2012 07:34:44 -0600, "J. L. Trantham"  
>wrote:
>
>>David,
>>
>>I have been  following discussions on the list about a GPSDRbO for a year  
>or
>>so.  Some interesting challenges and probably best implemented  in a 
>'stable'
>>environment rather than portable operation but as best I  can tell, it 
>would
>>require a very stable and good antenna location,  stable and clean power, 
>and
>>I was thinking of using something like an  LPRO-101 with an Ext C Field
>>input, a Shera type controller, and a GPS  timing receiver, though, I 
>suspect
>>there are likely to be some  'multi-tasking' receivers out there that will
>>look at several sources  including GPS, GLOSNASS, etc.
>>
>>While the project might be fun,  for portable work, it is likely far easier
>>and probably just as good  (almost), to use a Tbolt.
>>
>>In any event, something to think  about for the future.
>>
>>Joe
>>
>>-Original  Message-
>>From: time-nuts-boun...@febo.com  [mailto:time-nuts-boun...@febo.com] On
>>Behalf Of David
>>Sent:  Wednesday, January 11, 2012 11:12 PM
>>To: Discussion of precise time and  frequency measurement
>>Subject: Re: [time-nuts] FE-5680A Mechanical  Question
>>
>>
>>How would a GPSDRbO work?  Phase lock the  DDS output to the GPS? Phase 
>lock
>>a VCXO to the GPS and then phase lock  to the RbO on loss of GPS lock?
>>
>>On Wed, 11 Jan 2012 22:55:58  -0600, "J. L. Trantham"  
>>wrote:
>>
>>>Bill, Brian, Bill, and  Peter,
>>>
>>>Thanks for the info.  All I need now is a  'project' to incorporate the 
>>>unit into.
>>>
>>>In  the back of my mind, I have the thought of a 'box' that will be  
>>>battery powered or 110 VAC powered (perhaps with an internal SLA  
>>>battery) and include a GPSDO and Rb unit (possibly a GPSDRbO) for  the 
>>>purpose of a 'reference' for portable operation in the  microwave  
>>>regions.
>>
>>___
>>time-nuts  mailing list -- time-nuts@febo.com
>>To unsubscribe, go  to
>>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>and  follow the instructions  there.
>>
>>
>>___
>>time-nuts  mailing list -- time-nuts@febo.com
>>To unsubscribe, go to  
>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>and follow the  instructions  there.
>
>___
>time-nuts  mailing list -- time-nuts@febo.com
>To unsubscribe, go to  
>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the  instructions there.
>
>___
>time-nuts mailing list -- time-nuts@febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

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

Re: [time-nuts] Controlling FEI 5680A

[David]

I would just use a PIC, AVR, or ARM even if I had to use more than one
with some discrete logic on the side but I like solder, assembly, and
low level coding in that order.  If I find a small, cheap, easy to
use, and general purpose FPGA, I may look into that as well.

MIPS may be a special case for implementation.  The original Loongson
design (Chinese) lacked 4 instructions that MIPS still had IP
protection on.

On Sun, 15 Jan 2012 16:45:56 +0100, Magnus Danielson
 wrote:

>A short notice on embedded CPU/MPUs into FPGAs. Using PIC or AVR might 
>be tempting, but I consider any clone "dirty" from a rights perspective, 
>MIPS for instance have been very protective on their side, so has ARM. 
>So far has the SPARC been the only big one being accepted in their 
>LEON-x variants that I know of. We be sad to see the cotton industry 
>level being smashed by the big firm lawyers.
>
>So, either using the OpenRISC variants or similar. There is loads of 
>CPUs on the OpenCores website, but just because they are there do not 
>think they are free to use if they are clones of commercial stuff.
>
>I would either use one of the FPGA vendors CPUs and then write the core 
>in C, or use a free CPU.
>
>I could also roll my own CPU, as I have already done before, but 
>building a tool-chain including GCC is a bit of home-work. For my 
>application I haven't bothered, but it is tempting to get C capabilities.
>
>Then again, if someone could show that the PIC and/or AVR is free to 
>clone in FGPA, by showing a clear statement from the respective 
>technology holders, then that would be a way forward.
>
>I've done this analysis before, and so far I have not seen any 
>comprehensive open analysis covering these aspects.
>
>I fear that this is way off topic for this list, so I propose that this 
>aspects is continued on another list, such as the FPGA-Synth list, which 
>faces essentially the same problems.

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

Re: [time-nuts] Simple Super Ripple Eater

[David]

On Mon, 16 Jan 2012 12:48:24 -0500, michael taylor 
wrote:

>On Mon, Jan 16, 2012 at 12:17 PM, John Lofgren  wrote:
>> There have been discussions in the past about ways to reduce regulator 
>> output noise or clean-up oscillator or voltage reference power supplies.  
>> Here's an article from Design Ideas in Electronic Design that looks 
>> promising.  It has pretty decent rejection even at 1 Hz.
>>
>> http://electronicdesign.com/article/power/Simple-Super-Ripple-Eater-Also-Cleans-Battery-Based-Supply.aspx
>
>Am I wrong in assuming this is a similar to a circuit mentioned in
>time-nuts in the past in regards to voltage regulator noise, "Finesse
>Voltage Regulator Noise!" from Wenzel Associates?
>

It is a series configuration instead of a shunt configuration.  They
both accomplish the same thing but in different ways.  The Wenzel
design requires gain matching but should be unconditionally stable.

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

Re: [time-nuts] NTP for 64 bit windows

[David]

On Tue, 17 Jan 2012 10:46:19 +0100, "Anthony G. Atkielski"
 wrote:

>> Has anyone come across a NTP client that uses native 64 Win 7 code? I've
>> noticed all the 64 bit versions are running under WOW. I've use Meinberg
>> now found another source out of Poland.
>
>Windows has long had its own built-in NTP client. All you have to do
>is use that. You can change the parameters as needed (I always point
>the built-in client to my local NTP server and set the update
>frequency to once every few minutes, given the poor accuracy of PC
>clocks).

I have had problems with the build in Windows NTP client getting
confused or giving up and then neglecting to mention the problem so I
still use Tardis:

http://www.kaska.demon.co.uk/

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

Re: [time-nuts] 5370A on ebay

[David]

Oh great.  Now everybody knows.  :)

On Tue, 17 Jan 2012 15:43:24 -0500, Bob Bownes 
wrote:

>if anyone is looking for a 5370, there is one on ebay that is currently
>listed for $29+shipping...
>
>http://www.ebay.com/itm/HP-Agilent-5370A-Universal-Time-Interval-Counter-/160714650831?pt=LH_DefaultDomain_0&hash=item256b56f4cf
>
>No financial interest, but that's a lot less than I paid for mine! ;)
>Probably worth it for the ocxo!
>
>Bob
>___
>time-nuts mailing list -- time-nuts@febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

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

Re: [time-nuts] Labeling project boxes/panels

[David]

I layout the design I want (autocad) and print it reversed 1:1 on
overhead projector film.  Then I cut and mount it printed side down
with 3M Super 77 spray adhesive.  The mylar film is very tough and
resistant to solvents.  I use an ink jet but a laser printer should
work as well.

A similar procedure works for punch out masks.

On Sat, 21 Jan 2012 17:33:26 -0500, "Charles P. Steinmetz"
 wrote:

>I'm tired of setting up silkscreening for one-off or small lot 
>projects, and am looking for new ways to neatly label panels 
>(generally painted metal, sometimes bare metal or 
>plastic).  Preferably, something that can be done on-premises without 
>needing to send graphics out and wait for delivery.  I'd like to be 
>able to do layouts on a pc -- at a minimum with letters and lines, 
>and hopefully the capability to paste graphics, as well.  I'm willing 
>to overcoat the labeling if necessary (preferably with a spray rather 
>than an adhesive film).  Duty will generally be indoor, but I'd like 
>the labeling to survive locations that get direct sun through a window.
>
>I'm familiar with the Dymo and Brother industrial tape labelers, but 
>would like something that is not so confined to available tape widths 
>(if I'm doing an overlay -- which I'm not in love with generally -- 
>I'd like to overlay the whole panel).  I don't know if the Scotchcal 
>family of products has anything useful for this.  I have heard of 
>materials available for (laser?) printers that create water-soluble 
>decals, but have not run across any.  I know there are heat-transfer 
>PC resist materials -- are there similar things oriented to panel 
>labeling (this would not address plastic panels, I presume)?  One 
>potential drawback of printed solutions (where the actual toner or 
>ink from the printer becomes the label) may be making light-colored 
>labels for dark panels.
>
>Anything else people like?  I know I said I disfavor sending out for 
>overlays, but if anybody thinks really highly of this method, and can 
>identify a good vendor, I'm willing to listen.

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

Re: [time-nuts] 15 volt power supply for FE-5680A on eBay

[David]

On Sat, 21 Jan 2012 17:20:39 -0600, "Paul F. Sehorne"
 wrote:

>On Wed, Jan 18, 2012 at 6:25 PM, Chris Albertson 
>wrote:
 What I bought is a 15V open frame supply from allelectronics.com for
 $11.50.  It turned out to be a very high quality power supply (Digikey
 has the same unit for almost $40)   This PS does not drop volts even
 with the line input and load  well out of spec (I tested 63VAC input
 to a 4A load briefly) ...
 This is the one I bought

 http://www.allelectronics.com/make-a-store/item/PS-152/15VDC-2.7A-POWER-SUPPLY/1.html

>>
>
>I ordered two of the above mentioned power supplies.  They arrived 
>today.  I tested both of them.
>Neither holds 15 volts.  At 2 amps they are down to 14 volts.  Even at 1 
>amp they are down to 14.5 vdc.

The total regulation specification is +/- 5% so within 14.25 to 15.75
volts under all conditions.  How high was your lead resistance?

http://iccnexergy.com/elpac/medical-power-supplies/open-frame/mta040/

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

Re: [time-nuts] HP5328A LEDS driver transistor

[David]

The package is a TO-202 with the tab cut off or at least the MPS-U51
uses a TO-202 package.  Be careful when you replace it because the
pinout is EBC which is deprecated in power transistor packages.

Ic = 2.0 A
Vceo = 30 V
Pd = 1 W @ Ta 25 C
hfe = 60 @ 0.1 A
Ft = 50 MHz min

This is a very non-critical application.  I agree with Brooke Clarke
that a 2N4403 will probably work fine.  If you want something closer
then there are any number of TO-126 and TO-225 transistors like the
MJE170 which will work but again, be careful of the pinout.

On Sun, 22 Jan 2012 10:41:23 -0800, Chris Albertson
 wrote:

>I have an eBay HP5328A counter with two dead digits on the display.  I
>figured out the problem was two dead transistors.  I can swap
>transistors with a good digit and the problem moves.
>
>I'd not worked on LED displays before.  Turns out only one digit is
>lit up at a time, they strobe the digits in sequence.  The dead
>transistor is the one that controls the all the anodes in the
>7-segment LED module.  The service manual describes the transistor
>like this:  "part number = 1853-0326", "description = TRANSISTOR PNP
>SI ... FT-50MHZ"
>The p/n 1853-0326 cross references to a Motorola MPS-U51.  The MPS-U51
>data sheet matches the part that fails so I'm sure I got a correct
>cross ref.
>I took a photo of the dead transistor.  It is on .1" perf board for
>scale.   You can read the "3-326" p/n and see the Motorola "M" logo.
>http://www.dropbox.com/gallery/28915695/1/HP5328A?h=da35c1
>
>I look up the spec in the mps-u51 and see it is a to-220 like case and
>can handle 1W.  I'm really surprised it burned out as I doubt an LED
>requires 1W even if showing an "8".  Reading the mps-u51 spec sheet I
>see it has a low saturation voltage.  Maybe that is why the selected
>it as it is being driven by 7400 TTL logic that goes through a
>connector and has some resistors involved.
>
>Question:  These seem to be hardtop find.  Can anyone suggest a good sub"

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

Re: [time-nuts] HP5328A LEDS driver transistor

[David]

On Mon, 23 Jan 2012 17:27:32 -0500, "Charles P. Steinmetz"
 wrote:

>Stan wrote:
>
>>The 5328A manual I have shows a 3.5 V supply (looks like it is used just
>>for the display).  But with a bit lower Vce sat drops, I'd guess you 
>>get around
>>1 V across the 10 ohm segment resistors.  Or only about 900 mA when all
>>9 segments are on (but at a low duty cycle).  Did HP also use a 5 V version
>>of the driver in some 5328A counters?
>
>Interesting.  I have 3 different sets of schematics for the 
>5328A.  The most legible of these (thus the one I consult first) 
>shows a 5 V supply for the display.  The other two show 3.5 V, as 
>yours does.  I cannot recall ever measuring the display supply 
>voltage in a 5328.
>
>Even with 900 mA per digit, I'd want a transistor with >/=2 A maximum 
>collector current for the digit drivers -- so I still think the 
>ZTX949 may be the best readily-available choice.

I am surprised the LED current is so high.  I always found diminishing
returns above 20 mA but some LED types are better than others for
multiplexed applications where the peak to average current is high.  8
x 20 mA also conveniently stays below the bond wire limit if you drive
7 segments plus the decimal point directly with a single IC without
multiplexing.

I would use a 2 amp or greater transistor just to keep the gain high
although I know those Zetex transistors much better about that.  I
think Fairchild has a similar line of high beta, high current, low
dissipation transistors now as well.

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

Re: [time-nuts] establishing your position w/o gps

[David]

I think James Burke discussed these clocks in one of his documentary
series.  Besides not using a pendulum, they were temperature
compensated by using materials with opposite temperature coefficients
of expansion and then gimbaled for use on a rolling and pitching ship.

Oddly enough, the phase locked loop came significantly earlier when a
clock maker used it to regulate pendulum clocks overnight to quickly
calibrate a new clock to a reference clock.

On Tue, 24 Jan 2012 17:50:54 +0100, Azelio Boriani
 wrote:

>Yes, the first real push was the Longitude Act (1714) and the Harrison's
>clocks.
>
>On Tue, Jan 24, 2012 at 5:36 PM, Chris Albertson
>wrote:
>
>> On Tue, Jan 24, 2012 at 3:16 AM, Attila Kinali  wrote:
>> > On Tue, 24 Jan 2012 11:04:08 +
>> > "Poul-Henning Kamp"  wrote:
>> >
>> >> In message <20120124115848.312d60bd4fccce4f3e71c...@kinali.ch>, Attila
>> Kinali w
>> >> rites:
>> >>
>> >> >All this talk about telling the time using stars or the sun made me
>> wonder
>> >> >how did people tell what position their telescopes had back in the days
>> >> >before GPS?
>>
>> Sailingships and trade was what pushed this.   At the time of Columbus
>> he was able to know his latitude within a few 10s of miles but even
>> after returning to Europe he did no know how far around the world he
>> had sailed.  Was it 1/3rd or 2/3rds?  They had no way to know.The
>> problem was that on one had a clock that should keep time well enough.
>>  They used hour glasses on board ship for short duration time keeping
>> but those were of no use on a longer ocean crossing.
>>
>> Later they discovered the idea of common view of the moons of Jupiter
>> and they could measure the time from local noon some even on Jupitor
>> while a person back home did the same thing.  Later when he got back
>> home they compare notes and then know the difference in longitude.
>>  Good ocean going clocks were still centuries away.But in the
>> 1500's they could only know the location after the fact when they
>> returned

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

Re: [time-nuts] Building a GPSDO & trouble using Jupiter-T

[David]

The sawtooth error in the PPS output and how they were able to correct
it externally was interesting.  I have seen that kind of problem
before in DDS and other applications.

I wonder what other GPS receivers provide either PPS outputs without
sawtooth noise or a correction message.

On Sun, 29 Jan 2012 20:40:52 -0800, Hal Murray
 wrote:

>
>> What do you mean by "average"?  Do you mean that the GPS and PLL must be
>> kept on for "20 minutes to hours", or did you mean that the PLL loop filter
>> must have a time constant of 20 minutes to several hours?
>
>You have to compare the characteristics of the oscillator with the 
>characteristics of your GPS receiver.
>
>If your local oscillator is very stable, then you want to average over long 
>times (hours, days).  If your local oscillator is a good thermometer and you 
>have a very good GPS receiver, then you want a shorter time constant 
>(minutes) so you can track temperature changes.
>
>Do you know about hanging bridges?  If not, please read Timing for VLBI by 
>Tom Clark and Rick Hambly.  It's got some wonderful graphs.  Once you 
>understand those, this discussion will get much more interesting.
>  http://gpstime.com/files/tow-time2009.pdf

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

Re: [time-nuts] GPS SDR (was: FE-.5680A trimming resolution)

[David]

On Wed, 1 Feb 2012 09:27:30 -0800, Chris Albertson
 wrote:

>On Wed, Feb 1, 2012 at 8:19 AM, Attila Kinali  wrote:
>> On Wed, 01 Feb 2012 09:07:23 -0500
>> John Ackermann N8UR  wrote:
>>
>>> There've been numerous threads on the Gnuradio mailing list about code
>>> to receive GPS using the Ettus Research USRP hardware.  I don't know
>>> whether anyone has actually made it work, but it appears that it's been
>>> the subject of quite a few academic projects.
>
>That is the problem with an academic projects typically something like
>this would be part of a Master's theses or a senior project.  and then
>the student graduates and was no more interrest in supporting it.
>
>I thought it might be interresting but then found out you need to buy
>$2,000+ worth of hardware for even start experimenting.Open Source
>SDR needs to run on a common affordable platform or it will never gain
>the critical mass of users that it take to make the project live
>longer then a few months.
>
>I think the way to go is to find a commercial GPS chip that has a low
>level interface and then build the uP controller using a common
>development system.   Both the chip and the uP board need to be,
>common, well documented and cheap.   Then with this you build an open
>source thunderbolt type device. An SDR that samples the microwave
>RF is going to be un-affordable, even mixing and down converting
>microwaves is not so simple as doing the same on HF ham bands.  But
>there might be low level GPS chip available for cheap.

One of the projects did just this but then the integrated circuit or
module that handled the RF and low level functions was discontinued.
For a while they scavenged the hardware from other products that used
it but then those dried up as well.

I believe the best option now would be to find a ubiquitous and well
documented receiver that provides low level access but I suspect they
no longer exist.

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

Re: [time-nuts] FE-5680A 1 pps photo

[David]

Odd.  Did Tektronix mark it Fluke PM3082? :)

It is nice to know that the current generation of digital cameras can
be used for this application.  It is too bad that the image has so
much noise.

On Thu, 2 Feb 2012 16:27:03 +, John Howell 
wrote:

>and here's another photo of the pulse from one of the newer breed of 
>FE-5680A that require the 5V.
>Taken with a Sony Cybershot H5, 8 sec exposure, 'scope is an elderly Tektronix 
>2252
>
>http://dl.dropbox.com/u/1690159/1PPS_1%20FE-5680E.jpg
>
>On 2 Feb 2012, at 15:50, Alberto di Bene wrote:
>
>> I managed to take a photo at the scope screen showing the 1 pps pulse
>> from an old FE-5680A (the one that does not need the 5V and does not
>> output the oscillator signal - just the 1pps).
>> 
>> Exposure was 30 sec, F9. The signal was barely visible with naked eye,
>> and some jittering is present. The room of course was in complete
>> darkness, but the reflex of the stand-by led of another instrument
>> can be seen...
>> 
>> http://dl.dropbox.com/u/15089947/1pps.gif

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

Re: [time-nuts] FE-5680A 1 pps photo

[David]

The probe compensation could be off.

What type of vertical plug-in was used?  The Tektronix 11000 series of
oscilloscopes scare me.

On Sat, 04 Feb 2012 00:36:13 -0800, Rex  wrote:

>Good image.
>
>So, if I read that right it is a pulse about 1 uS wide and goes from 
>base of zero volts to about 5.8 V.
>
>Curious why the high level is over 5 V? Is your 5 V supply to the 
>Rubidium unit up there?
>
>On 2/3/2012 8:52 PM, Bob Bownes wrote:
>> Just for completeness sake, here is a screen capture off of my DSA-602 of
>> the 1pps. Note that the trace starts 500ns _before_ the 1pps triggers the
>> capture. Ah the wonders of digital sampling.
>>
>>
>> http://www.fastbobs.com/pictures/1pps.jpg
>>
>> Also as a pdf
>>
>> http://www.fastbobs.com/pictures/1pps.pdf
>>
>> Bo

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

Re: [time-nuts] PICTIC II questions

[David]

On Tue, 7 Feb 2012 08:28:14 +0100, Attila Kinali 
wrote:

>On Sun, 5 Feb 2012 19:55:36 -0900 (AKST)
>"Richard H McCorkle"  wrote:
>
>>While using a faster timebase or higher interpolator gain increases
>> the resolution that doesn?t imply the accuracy will also increase. The
>> PICTIC II uses CMOS logic with propagation delays that vary with
>> temperature much more than the ECL logic used in a commercial counter
>> like the SR620, severely affecting the accuracy below about 250ps. The
>> interpolator was modeled after the SR620 design but simplified to use
>> the least amount of hardware possible to reduce the size and cost. As
>> the timebase rate is increased a smaller cap is used so stray
>> capacitance and the capacitance of the switching devices have a larger
>> effect on the charge linearity. The PICTIC II uses software calibration
>> methods that are not as precise as those in a commercial counter so the
>> accuracy is not specified other than to say it works well for GPS
>> monitoring applications at 1ns resolution with a 10 MHz timebase once
>> set up properly. If you want to log GPS data over months at a time then
>> a $50 PICTIC II should be sufficient for purpose. But if you want lab
>> grade accuracy over long time intervals with 25ps resolution then by
>> all means use a lab grade commercial counter like the SR620 and not a
>> PICTIC II!
>
>The PICTIC II might not be lab grade, but, frankly, i don't see any
>big problems in the design itself. Ie if one would replace the slow
>CMOS logic by something faster, lets say an FPGA (not an expensive
>highspeed one, but one in the 20-30USD range, available at Digikey/Mouser/..)
>and increase the clock speed to 100 or even 200MHz, then one ought to
>get a resolution in the lower ps range. And i guess, that an accuracy
>of 20-50ps should be acheivable.

I was looking at this problem during the simple disciplined oscillator
thread.  I wanted something that would allow continuous evaluation of
the jitter in the PPS signal itself independent of the GPS receiver.
The discrete design for the clock delay timer in a Tektronix 2230 or
2232 oscilloscope is good to 2 GS/s or 50 pS and their older 7T11
sampling sweep plug-in does even better than that with no high
frequency clock signals required.

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

Re: [time-nuts] PICTIC II questions

[David]

Step recovery diodes turn off fast but have a relatively long storage
time.  The fastest switched current integrators use schottky diodes.

On Tue, 7 Feb 2012 14:06:55 +0100, Azelio Boriani
 wrote:

>To enhance the PICTIC II performance can step recovery diodes be used?
>Maybe the fast turn off can boost the switching capabilities of the
>interpolator for best resolution...
>
>On Tue, Feb 7, 2012 at 12:35 PM, Hal Murray  wrote:
>
>>
>> att...@kinali.ch said:
>> > BTW: does anyone know how these days low cost FPGAs perform in terms of
>> > jitter? (the data sheets are kind of scarce in that regard). And how do
>> they
>> > compare to state of the art ECL logic?
>>
>> Generally, not good.
>>
>> The general problem is that they have a lot of logic and a lot of I/O
>> drivers
>> and shared power/ground pins.  Things are messy if you have multiple
>> clocks.
>> Things are better if you only have one clock and better if you don't have
>> any
>> nearby drivers switching at the same time.
>>
>> For a few critical signals, you could reclock in an external FF.

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

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

[David]

On Fri, 10 Feb 2012 16:35:26 -0800, Chris Albertson
 wrote:

>On Fri, Feb 10, 2012 at 3:52 PM, Bob Camp  wrote:
>> Hi
>>
>> I think you will need some sort of analog detector to get what you are 
>> looking for.
>
>I don't think it needs to be analog.   For example you can xor the two
>10MHz signals and then sample the digital xor output then deduce its
>duty cycle by counting how many samples are 1 and how many are 0.
>You'd expect an equal number if there is a phase lock.   Might be best
>to sample a-periodically at random.
>
>Many designs put a low pass filter on the XOR but I think random
>polling allows the software to adjust the time constant and is cheaper
>to implement.  I think you'd have the latch the xor in a flipflop as
>it would move to fast for a uP to read.

All you need for this is the flip-flop.  Clock the flip-flop with the
1 PPS signal and capture whether the oscillator is leading or lagging.
This requires the 10 MHz oscillator to be within 1 Hz but if you
divide it down before the comparison, you can extend this range as
needed to handle wider initial oscillator frequencies and larger
amounts of PPS jitter.

The simple GPSDO design in QST a couple years ago did something like
this.

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

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

[David]

Flip-flops hardened against metastability are available.

I would try a track and hold before a sample and hold but I wonder how
accurate it would be having to rely on the oscillator waveform.  Fast
sample gates are non-trivial.  I believe better than either would be a
time to voltage converter which just needs a set/reset flip-flop and
switched current integrator.  Dig up the schematic for a Tektronix
2232 oscilloscope for a "simple" example that yields 50pS resolution
using late 1980s  technology.

I just recently ventured into the sampling oscilloscope world with a
7S11/S-4/7T11 setup.  The S-4 uses a traveling wave gate which avoids
the fast sample gate problem but I would consider that the far side of
esoteric since I have not studied it in detail yet.

On Fri, 10 Feb 2012 17:23:46 -0800 (PST), Robert LaJeunesse
 wrote:

>Sampling unsychronized signals with a DFF is problematic, since if setup and 
>hold times are not met the output could oscillate and maybe settle to some 
>noise 
>driven value. I can't help thinking that if you are sampling the 10MHz 
>signal at 
>1Hz the only way to get reasonable resolution is to sample the 10MHz sinewave 
>signal's fastest part with tight analog sample & hold. Looking at the result 
>wih 
>a slow, low-cost 24-bit A to D chip would give tremendous resolution - if the 
>drift was low enough. Use the ADC over a sub-range and add a small micro for 
>noise filtering and averaging and one can achieve measurements result in the 
>10s 
>of femtoseconds. 
>
>
>From: David 
>To: Discussion of precise time and frequency measurement 
>Sent: Fri, February 10, 2012 8:10:56 PM
>Subject: Re: [time-nuts] GPS lock of the FE5680. Current experiment and 
>question
>
>All you need for this is the flip-flop.  Clock the flip-flop with the
>1 PPS signal and capture whether the oscillator is leading or lagging.
>This requires the 10 MHz oscillator to be within 1 Hz but if you
>divide it down before the comparison, you can extend this range as
>needed to handle wider initial oscillator frequencies and larger
>amounts of PPS jitter.
>
>The simple GPSDO design in QST a couple years ago did something like
>this.

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

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

[David]

On Fri, 10 Feb 2012 17:28:53 -0800, Chris Albertson
 wrote:

>On Fri, Feb 10, 2012 at 5:10 PM, David  wrote:
>
>> All you need for this is the flip-flop.  Clock the flip-flop with the
>> 1 PPS signal and capture whether the oscillator is leading or lagging.
>
>I can see how this can detect lock.  If the FF is the same each second
>you are good.  But if it changes how do you know the direction of the
>change?

It only detects if the phase difference is leading or lagging.
Assuming that the frequency is locked, the FF should return a 50/50
distribution when phased locked.

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

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

[David]

On Fri, 10 Feb 2012 19:54:11 -0600, David 
wrote:

>Flip-flops hardened against metastability are available.
>
>I would try a track and hold before a sample and hold but I wonder how
>accurate it would be having to rely on the oscillator waveform.  Fast
>sample gates are non-trivial.  I believe better than either would be a
>time to voltage converter which just needs a set/reset flip-flop and
>switched current integrator.  Dig up the schematic for a Tektronix
>2232 oscilloscope for a "simple" example that yields 50pS resolution
>using late 1980s  technology.

My mistake.  That should be 500pS.

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

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

[David]

On Fri, 10 Feb 2012 18:19:53 -0800, Hal Murray
 wrote:

>> Flip-flops hardened against metastability are available.
>
>Do you have a part number in mind?

Some logic families are better than others.  In general you want
faster ones with shorter setup and hold times.

On Semiconductor has an interesting application note with some test
data.

http://www.onsemi.com/pub_link/Collateral/AN1504-D.PDF

National mentions "metastable hardened" in this 74HCT74 data sheet.
Notice the guaranteed worst case propagation delays:

http://eshop.engineering.uiowa.edu/NI/pdfs/00/53/DS005360.pdf

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

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

[David]

There are no temperature coefficient effects or calibration drift with
the current sources and ramp circuits in this case.  Between 1 PPS
measurements, there is more than enough time to gate a sample waveform
from the convenient 10 MHz source to the time to voltage converter to
calibrate it.

One interesting thing I just noticed with the Tektronix 2440 design is
that the trigger starts two different time to voltage converters.  One
measures to the positive sample clock edge and the other to the
negative sample clock edge so if one goes metastable, the other can be
used.

On Sat, 11 Feb 2012 10:54:40 -0500, paul swed 
wrote:

>Getting very interesting.
>Bob had mentioned just sample the 10 MC sine wave. What I used to do on
>homebrew Loran C.
>
>Thats easier to do because today its nothing to buffer that 10 MC signal to
>drive a fast sample and hold. This eliminates the ramp circuitry and
>constant current sources used in the ramp and tempco effects.
>
>This all seems to work out reasonably because the 5680s are in general
>pretty darn stable. (Boy is that a relative term in time-nuts land)
>
>Now to dig through the ole junk box for a sample and hold chips. Most
>likely older and useless. Go hunting at mouser or digikey for modern stuff.
>Hate to have to go to discrete pulsed diodes.
>Regards
>
>On Sat, Feb 11, 2012 at 10:33 AM, Azelio Boriani
>wrote:
>
>> This is the simplest part if a microprocessor can be used: by the serial
>> port you get the sawtooth correction in nS to be applied to the sampled
>> data. The sampled data must be converted to nS or the sawtooth correction
>> must  be converted in a suitable sampled data correction. It is possible
>> even to hardware correct the PPS with a delay line before using it  (see
>> the already mentioned gpstime.com/files/tow-time2011.pdf by Tom Clarck and
>> Rick Hambly).
>>
>> On Sat, Feb 11, 2012 at 1:45 PM, Bob Camp  wrote:
>>
>> > Another way to build an analog phase detector...
>> >
>> > Next layer on the onion is how to get the sawtooth correction out of the
>> > GPS and into your loop.
>> >
>> > On Feb 11, 2012, at 12:05 AM, Chris Albertson > >
>> > wrote:
>> >
>> > > All these different suggestions build down to one thing, the precision
>> > > with which you measure the phase when you sample it each second.  The
>> > > single flip flop will tell you which half cycle. a simple two bit
>> > > counter made with two '74 FFs tells you which half cycle and with
>> > > direction.
>> > >
>> > > The "best" maybe  is if you let the PPS set a FF and the 10MHz reset
>> > > it.  The FF's output gates a constant current to a capacitor and
>> > > charges it to some voltage.  Then you measure that with a 10-bit ADC.
>> > >  This measures the phase to maybe 1%, gives you direction and is
>> > > pretty cheap to build
>> > >
>> > > Let's see if I have the numbers right?  If you check a 10MHz signal
>> > > once per second with just the FF then you have 1E-7.  You would need
>> > > 1000 seconds for 1E-10.   But if you measure phase to 1/10th of a
>> > > cycle you get to 1E-10   ten faster.  Right?
>

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

Re: [time-nuts] GPS fade out, Sat/Sun

[David]

I do not see any space weather anomalies that would explain it so my
guess is a local problem.

On Sun, 12 Feb 2012 20:52:54 -0800, Hal Murray
 wrote:

>
>Did anybody else notice nything?  It might have been local noise/RFI.
>
>I'm in California (Silicon Valley).  It was about Sat noon-midnight local 
>time, 8PM Sat to 8AM Sun UTC.
>
>A TBolt and Z3801A went into holdover.  The TFOM on the Z3801A jumped up to 4 
>for a while.
>
>Most of my low cost GPS/NMEA units gave up.
>
>The thing that clued me in before I looked at the graphs of the log files was 
>the bright blue LED on a pair of Sure units stopped blinking.  (It really is 
>bright.  I normally run with a sheet of paper on top of them.)

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

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

[David]

On Fri, 10 Feb 2012 18:19:53 -0800, Hal Murray
 wrote:

>> Flip-flops hardened against metastability are available.
>
>Do you have a part number in mind?

Here is another one with 125pS of specified metastability if you can
spare 27mA at 5 volts:

http://www.onsemi.com/pub/Collateral/MC10EL31-D.PDF

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

Re: [time-nuts] Fwd: FE-5680A Contact FEI

[David]

I have been leaning more toward Agilent and away from Tektronix for
this very reason.

On Fri, 17 Feb 2012 09:17:54 -0700, Tom Knox 
wrote:

>I think that for many of us, we are both professional and hobbyist Time Nuts 
>and companies that encourage the hobbyist will find it pays of when we make 
>professional purchases. Agilent seems to be learning this lesson as they put 
>more and more manuals for obsolete products on line.   

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

Re: [time-nuts] How best to exchange Large files?

[David]

On Mon, 20 Feb 2012 19:41:31 +0100, Attila Kinali 
wrote:

>On Mon, 20 Feb 2012 09:52:39 -0800
>"WarrenS"  wrote:
>
>
>> Recording high speed and/or long general purpose raw Osc data, the file can 
>> become very large. 
>> I'm looking for a simple, fast and easy (and cheap) way to transfer large 
>> compressed data files of up to say a 100 MB between time-nuts.
>> I know there are all kinds places one can store large files that others can 
>> then have access to,  so I do not want to use the "OLD" way of breaking it 
>> up into many small pieces.
>> I do not need to do this very often, so I do not want to sign up for any 
>> long term thing or maintain a Friends or face book type thing, 
>> I'm just looking for an easy, temporary way (say lasting up to a week each) 
>> to transfer a few big files that are too large to email.
>
>How about using bittorrent? There are multiple free trackers out there,
>which can handle the coordination between the nodes, if you don't want
>to run your own (e.g. [1]).
>
>Alternatively, i could host the files as long as the traffic stays
>below a couple 10GB/month.
>
>   Attila Kinali
>
>[1] http://openbittorrent.com/

I have used uTorrent to distribute large data sets before using both
the trackerless protocol and the OpenBitTorrent tracker.  All I had to
provide was either the torrent file or the magnet URL.  The caveat of
course is that you need to leave your bittorrent client running to
seed the file or files and you will probably want to figure out your
port forwarding so you can accept incoming connections.

You would probably still want a simple web page though with the magnet
links or torrent files.

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

Re: [time-nuts] How best to exchange Large files?

[David]

I used Bittorrent last time to do this because of the ease and
reliability factor.  There is no resuming since it does not work that
way and the whole process was just set and forget.  HTTP and FTP can
usually resume aborted transfers as well but require explicit support
from both sides and in practice, we had problems with corruption. With
a file download service, the problem would have been resuming aborted
uploads.

Since I was only sharing with a couple of people, I just sent the
magnet links via chat but the torrent files themselves could have been
sent via email.  I do have home HTTP and FTP servers so using an open
directory to hold the torrent files for downloading could have been
done if it was a regular operation.

On Tue, 21 Feb 2012 23:16:08 +0100, ehydra  wrote:

>I think most users have ADSL, where the problem is the low upload 
>bandwidth. If the connection drops, the whole file is lost.
>
>The download is much faster and so there is a good change to save the 
>whole file.
>If not:
>If the web-browser and the file-owning server understand reconect, one 
>can retry the download and then the old file merges with the new part 
>without further effort.
>
>So I wonder if FTP does it the same way? Any experience?
>
>
>My problem is that I want to send a big file to another person, but my 
>internet upload bandwidth is way to small.
>
>Any suggestions? I run a web-server with PHP and a FTP-server.
>
>As I learned from the thread a torrent-app is not enough. Transfering 
>via POP3 looks impossible because seldom the two email-server will have 
>both account limitations beyond 100MB.



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

Re: [time-nuts] How best to exchange Large files?

[David]

On Tue, 21 Feb 2012 15:19:47 -0800, Chris Albertson
 wrote:

>Someone needs to also run a tracker.  THat is not hard to do and the
>tracker software is free.   Then you can give a group of people your
>file by publishing a short .torrent file. This is the best way to
>send a file to a large group.   But for one person it is no fasterthan
>FTP or HTTP.

Some clients have a tracker built in but you can also use the
OpenBittorrent tracker and trackerless torrents are possible if you
use DHT.

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

Re: [time-nuts] How best to exchange Large files?

[David]

On Wed, 22 Feb 2012 00:28:34 +0100, ehydra  wrote:

>David schrieb:
>> I used Bittorrent last time to do this because of the ease and
>> reliability factor.  There is no resuming since it does not work that
>> way and the whole process was just set and forget.  HTTP and FTP can
>> usually resume aborted transfers as well but require explicit support
>> from both sides and in practice, we had problems with corruption. With
>> a file download service, the problem would have been resuming aborted
>> uploads.
>>
>
>I'm a little confused. Does utorrent can work in a private mode? So I 
>send a magnet link to the consumer and he can connect to my utorrent 
>client? Does utorrent work as a server?

uTorrent and some other bittorrent clients have small trackers built
in that can be enabled and work fine for private transfers.

>Looks to me that there are different torrent protocols? I never 
>investigated it.

They added support for DHT, distributed hash tables, so it is also
possible to share files without any tracker support.

In practice for reliability, I usually added my uTorrent tracker, the
OpenBittorrent tracker, and DHT to the torrents I was sharing so any
client should have worked.

>If it works it looks like the simplest way.

Creating the torrent file to start with was the most complicated part.
You should also make sure you have an incoming IP port through your
NAT and firewall to support incoming connections.

I also usually sent along a PAR2 set or used RAR for end to end error
detection but only because of previous data corruption using HTTP and
FTP with large files.

One other advantage of using bittorrent is that whole directory
structures could be easily shared and the downloader could pick which
parts they wanted.

If some of your downloaders leave their clients running then they can
also upload to other downloaders speeding up the transfers.

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

Re: [time-nuts] Neutrinos not so fast? (defectove connector)

[David]

A transformer or differential signaling would also have the virtue of
allowing easy galvanic isolation to prevent ground loops.

Fiber optic and line receivers often set their switching threshold
using a positive and negative peak detector.  The same design works
very well for analog peak to peak automatic triggering in
oscilloscopes.

AN47-59, 50 MHz Adaptive Threshold Trigger Circuit:

http://www.linear.com/docs/4138

AN61-15, High Speed Adaptive Trigger Circuit:

http://www.linear.com/docs/4150

On Thu, 23 Feb 2012 16:01:55 +0100, Azelio Boriani
 wrote:

>To square a sine 10MHz you can use a 4:1 transformer with the center tap:
>connect the tap to GND and use a differential line receiver (ADM485,
>MAX485) connected to the differential signal that comes out from the
>transformer. The input of the transformer receives the single ended sine
>10MHz.
>
>On Thu, Feb 23, 2012 at 3:51 PM, Azelio Boriani 
>wrote:
>
>> And by using a differential pair is like halving the rise time: when one
>> arm rises the other falls, effectively doubling the speed of the crossing
>> and the sharpening of the trigger event. Sort of auto_ schmitt_trigger...
>>
>>
>> On Thu, Feb 23, 2012 at 3:45 PM, Azelio Boriani 
>> wrote:
>>
>>> I recommend the differential pair: here the trigger have to sense the
>>> crossing of the two signals and this crossing is well definite.
>>>
>>>
 Darn those finite rise times
 I've been bitten more than once by this very phenomenon (which I admit
 doesn't say a lot for me.. being bitten once is ok, but since I've had
 multiple bites...)

 But this brings up an interesting time-nut problem for the hive mind..

 If you had to design some scheme for interconnecting "boxes" and wanted
 to transmit an accurate time sync, what should it look like, so that you're
 insensitive to things like rise time.

 (maybe this harkens back to the discussion about 10 MHz, why sine vs
 square wave distribution)

 It has to be a single signal (maybe a differential pair), because
 otherwise, don't you have potential for skew between the multiple signals.

 Zerocrossing sort of works, if you take only one direction, but does
 asymmetry of the waveform screw you up?  (e.g. what's "zero".. is it half
 way between peak values + and -?)

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

Re: [time-nuts] OT - Portable Digital 'scope

[David]

Sampling oscilloscopes and digital storage oscilloscopes that support
equivalent time sampling do this very thing.  My Tektronix 2230 with a
20 MS/sec flash converter has a bandwidth of 100 MHz and a 2 GS/sec
equivalent time sampling rate.  A 7854 with a 500 kS/sec sampler (at
10 or 11 bits) and is good to at least 400 MHz.  A 7T11 samples at 50
kS/sec but has a 14 GHz bandwidth with an S-4 sampling head.

All of the above examples rely on repetitive signals and use one or
another form of time to voltage conversion.  The 2230 directly
measures the time difference between the trigger and sample clock with
a time to voltage converter.  The 7854 simultaneously samples the
signal and the sweep.  The 7T11 sequentially or randomly triggers the
sampler at different sweep positions.

The DS203 is relying on digital triggering after the ADC so equivalent
time sampling is possible but subject to aliasing of the reconstructed
trigger waveform itself.  I presume each acquisition record is aligned
with the waveform record before being merged.  Some more recent high
performance DSOs work this way.

On Thu, 23 Feb 2012 23:22:01 +0100, Azelio Boriani
 wrote:

>Actually, undersampling does use the alias effect to bring down the RF
>carrier. That is, the direct sampling radio concept cannot avoid the
>aliasing: it is exploited to avoid, for example, to sample a 2GHz carrier
>modulated with a 20MHz signal with a 4Gsample/second ADC (by the way, does
>it exist?). A simple 20Msample/second ADC would be enough. Yes, to analyze
>an analog signal in real time I doubt you can use this method, if the
>signal is periodic maybe... you can advance the sampling trigger a bit,
>cycle by cycle, and reconstruct the whole signal after this little amount
>has covered a full cycle.
>
>On Thu, Feb 23, 2012 at 10:56 PM, Jim Lux  wrote:
>
>> On 2/23/12 1:25 PM, Robert LaJeunesse wrote:
>>
>>> FWIW Rigol pushes their 40MHz Analog Devices part to 100 MHz without any
>>> problem
>>> (seen in eevblog teardown). Yes it's sort of cheating, but if the part
>>> works
>>> fine because all of the suppliers parts now yeild that fast due to an
>>> improved
>>> process well, it saves a few dollars / quid / drachma...
>>>
>>> And the 40MSPS is over full temp range, likely this is not a problem for
>>> the DSO
>>> 203 which has NO temp rating.
>>>
>>> Yes the "72MHz analog" channel rating makes no sense for something
>>> sampling at
>>> 72MSPS, Nyquist says you get at most 36 MHz bandwith.
>>>
>>
>> That doesn't mean you couldn't use a sampler running at, say, 50 MSPS to
>> look at a 110 MHz signal (something we actually do in a radio).
>>
>> There are lots of ADCs out there that have RF bandwidths of much more than
>> the sample rate, intended for use in direct sampling receivers. What
>> performance really depends on is how good the sample/hold or track/hold is
>> and what the sample jitter is.  (and of course, whether there's a stage in
>> front to keep unexpected signals from aliasing in)
>>
>> There are several ADCs out there that have GHz bandwidths and max sample
>> rates in the 100MSPS range.

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

Re: [time-nuts] OT - Portable Digital 'scope

[David]

Switched gain stages mean the bandwidth and transient response before
the ADC is going to change with different sensitivities unless both
are significantly limited which apparently is the case.

How do modern DSOs handle that?  I guess it would explain why I have
been told their front end calibration is so arduous.  If you lose the
calibration constants somehow, you might as well throw the
oscilloscope away.  Do any support user recalibration?

I agree that the floating input is a problem.  Maybe they got lucky
with that specific operational amplifier.

On Thu, 23 Feb 2012 13:25:51 -0800 (PST), Robert LaJeunesse
 wrote:

>FWIW Rigol pushes their 40MHz Analog Devices part to 100 MHz without any 
>problem 
>(seen in eevblog teardown). Yes it's sort of cheating, but if the part works 
>fine because all of the suppliers parts now yeild that fast due to an improved 
>process well, it saves a few dollars / quid / drachma...
>
>And the 40MSPS is over full temp range, likely this is not a problem for the 
>DSO 
>203 which has NO temp rating.
>
>Yes the "72MHz analog" channel rating makes no sense for something sampling at 
>72MSPS, Nyquist says you get at most 36 MHz bandwith. I saw no anti-aliasing 
>filter (well, C9 or C11 and C73 do some roll off) so who knows what the screen 
>will actually show. Might make a decent 10MHz scope, at which point the use of 
>FET solid-state relays doesn't concern me so much.
>
>I was surprised that they use trimmers on the input to match the channels, 
>that's a nice touch but does add some loading. The U1B op-amp is disconnected 
>for higher input voltage ranges so it doesn't overload and distort the signal, 
>which is processed by the U1A amp for those ranges. Perhaps not good that the 
>U1B input is left effectively floating.
>
>
>From: Attila Kinali 
>To: Discussion of precise time and frequency measurement 
>Sent: Thu, February 23, 2012 3:49:49 PM
>Subject: Re: [time-nuts] OT - Portable Digital 'scope
>
>On Thu, 23 Feb 2012 20:01:18 -
>"Rob Kimberley"  wrote:
>
>> I'm looking at Item: 300658066641 on EBay, and wanted to know if anyone in
>> the group had any experience of this product. I know this is way off topic,
>> but as a group it's nice to know what's out there and possibly useful in our
>> mutual hobby.
>
>It depends what you want to use it for. If you just want to have
>something protable that can show you roughly what's going on,
>then this might be a good thing. For anything else, especially measurements,
>i wouldnt trust it further than i can throw it.
>
>It's actually quite nice that they put the schematics online too,
>so their claims can be verified.
>
>First that jumps out is that they are using a AD9288-40 as ADC.
>Note the -40 there? It means it's an 40Msps ADC. Ie the maximum
>usable BW you can have is 20MHz (actually a bit lower). The analog
>circuitry doesn't seem too bright either, but i guess you should be
>able to get the 20MHz. I havent checked the exact circuitry so
>i cannot say whether the input circuit does filter at 20MHz. But
>as they claim to have 72MHz analog bandwidth, i would be very carefull
>about aliasing problems
>
>The input circuitry isn't very impressive either and has an undefined
>input capacitance (there is a trimmer there) somwhere between 5pF and 30pF
>(plus stray capacitances). I find it a it strange, that they disconnect one
>input of the frontend opamp... it might anything from going into saturation
>to start bouncing around... 
>The analog switches are rather on the cheap side, nothing you'd expect
>in an DSO, but well.. for that price :-)
>
>Also notice that the connectors used look like SMB or MCX antenna
>connectors. Ie those would not be able to withstand many mating/break
>cycles.
>
>Overall, i'd say a good portable gauge, but not much more.
>
>For a more indepth analysis i'd have to take the schematics apart
>into a readable format... 
>
>            Attila Kinali

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

Re: [time-nuts] OT - Portable Digital 'scope

[David]

If the bandwidth is really limited to 2 MHz, that is a rise and fall
time of 175ns.  Some of those PPS signals are barely wider than that.

On Thu, 23 Feb 2012 22:26:47 +0100, Azelio Boriani
 wrote:

>Yes, in my opinion the connectors are MCX and I totally agree with Attila
>about the 20MHz limit. Nice toy to just take a look at low speed signals,
>for example GPSDOs 10MHz and PPS, serial lines and so on.
>
>On Thu, Feb 23, 2012 at 9:49 PM, Attila Kinali  wrote:
>
>> On Thu, 23 Feb 2012 20:01:18 -
>> "Rob Kimberley"  wrote:
>>
>> > I'm looking at Item: 300658066641 on EBay, and wanted to know if anyone
>> in
>> > the group had any experience of this product. I know this is way off
>> topic,
>> > but as a group it's nice to know what's out there and possibly useful in
>> our
>> > mutual hobby.
>>
>> It depends what you want to use it for. If you just want to have
>> something protable that can show you roughly what's going on,
>> then this might be a good thing. For anything else, especially
>> measurements,
>> i wouldnt trust it further than i can throw it.
>>
>> It's actually quite nice that they put the schematics online too,
>> so their claims can be verified.
>>
>> First that jumps out is that they are using a AD9288-40 as ADC.
>> Note the -40 there? It means it's an 40Msps ADC. Ie the maximum
>> usable BW you can have is 20MHz (actually a bit lower). The analog
>> circuitry doesn't seem too bright either, but i guess you should be
>> able to get the 20MHz. I havent checked the exact circuitry so
>> i cannot say whether the input circuit does filter at 20MHz. But
>> as they claim to have 72MHz analog bandwidth, i would be very carefull
>> about aliasing problems
>>
>> The input circuitry isn't very impressive either and has an undefined
>> input capacitance (there is a trimmer there) somwhere between 5pF and 30pF
>> (plus stray capacitances). I find it a it strange, that they disconnect one
>> input of the frontend opamp... it might anything from going into saturation
>> to start bouncing around...
>> The analog switches are rather on the cheap side, nothing you'd expect
>> in an DSO, but well.. for that price :-)
>>
>> Also notice that the connectors used look like SMB or MCX antenna
>> connectors. Ie those would not be able to withstand many mating/break
>> cycles.
>>
>> Overall, i'd say a good portable gauge, but not much more.
>>
>> For a more indepth analysis i'd have to take the schematics apart
>> into a readable format...
>>
>>Attila Kinali
>>
>> --
>> Why does it take years to find the answers to
>> the questions one should have asked long ago?
>>
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>___
>time-nuts mailing list -- time-nuts@febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

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

Re: [time-nuts] Power Supply Noise Affects Thunderbolt 1 PPS

[David]

On Tue, 28 Feb 2012 00:13:18 -0500, "Charles P. Steinmetz"
 wrote:

>Ed wrote:
>
>>So, for best HF noise performance where the input noise may be 
>>large, it's best to use a follower or shunt regulator topology, 
>>despite the lower efficiency - unless efficiency is more important.
>
>To put it more bluntly, the last time I looked (it has been a while, 
>so there may be something new I haven't seen) LDOs were all 
>substantially inferior to standard regulators in terms of noise 
>feedthrough and HF load regulation.  The rule of thumb has always 
>been to avoid LDOs unless low dropout was the paramount concern.  Has 
>something changed with current LDO designs to make them competitive 
>with standard regulators in terms of noise feedthrough and HF load regulation?

As Ed points out, the topology makes a significant difference.

The common emitter/source low dropout designs also have problems with
frequency compensation because of the voltage gain in the power stage.
Negative regulators with NPN pass elements have the same problem
leading to the output capacitor requirement.  Usually they have worse
transient response.

The highest performance low dropout regulators I have seen use
emitter/source followers with a low current bias supply.

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

Re: [time-nuts] Power Supply Noise Affects Thunderbolt 1 PPS

[David]

The Linear Technology LT3070 (150mV @ 5A) , LT3071, LT1580 , and
LT1581 (700 mV @ 10A) are examples:

http://www.linear.com/product/LT1580

For comparison:

http://www.linear.com/product/LT1584

The LT1580 (0.8V @ 7A) has the same topology as the LT1584 (1.5V @ 7A)
except everything but the pass NPN is powered from a bias supply
brought out to a separate pin.  If the bias supply is connected to the
input supply, then it duplicates the dropout characteristics of the
LT1584.

On Mon, 27 Feb 2012 22:58:33 -0800, gary  wrote:

>I hate to be argumentative, but you can't be low drop out and use an 
>emitter follower. Draw the circuit and convince yourself. You would need 
>a high side driver scheme to drive the base/gate, and that require some 
>sort of boost converter. It can be done on switchmode chips, but not in 
>a linear circuit. Well unless you ship it with a battery.
>
>On 2/27/2012 9:51 PM, David wrote:
>> The highest performance low dropout regulators I have seen use
>> emitter/source followers with a low current bias supply.

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

Re: [time-nuts] FCC Chair Talks Spectrum, Gets GPS Letter

[David]

I see a big lack of details.  Form factor?  Insertion loss?  Frequency
change with temperature?  How does it compare with a standard Murata
filters?

On Fri, 09 Mar 2012 19:32:10 -0600, Michael Blazer
 wrote:

>Here's the link to the white paper: 
>http://javad.com/downloads/javadgnss/publications/20112312.pdf.  It was 
>originally linked from GPS World's news email.  It was originally posted 
>as a technical white paper.  I don't recall the 'Political Noise' lead 
>in, but then, I'm a technical person and try to avoid political noise 
>anyway.  After rereading it, it seems more like a 'I love me' piece.
>
>Mike
>
>On 3/8/2012 12:53 AM, Hal Murray wrote:
>> mbla...@satx.rr.com said:
>>> I read a white paper Javad put out touting their new (and cheaper to  build)
>>> front end filter.  Of course it is patented.  So guess where  everyone has
>>> to go should LS get the green light.
>> Was that filter included as part of the recent round of testing?  Did it 
>> work?
>>
>> I don't remember seeing any grand press releases along the lines of "just use
>> our filter".

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

Re: [time-nuts] FE5680A Calibration

[David]

I picked up a gimpy Beckman UC10 universal counter not long ago for
about $10 from Ebay.  Even better, I just repaired a Tektronix 7D15
(it has a whole board full of those junk TI integrated circuit sockets
which need to be replaced) although you need to leave an entire
oscilloscope mainframe on to use it.  The advantage of the later is
adjustable slope, sensitivity, and triggering.

On Wed, 14 Mar 2012 17:50:28 -0400, Bob Camp  wrote:

>At least the "don't mess to much with it" part has sunk in. That puts you 
>ahead of most people at this point.
>
>A usable counter should be a sub $100 sort of thing either at auction or 
>surplus. With some careful shopping it can be a sub $40 item.
>
>On Mar 14, 2012, at 4:25 PM, "Chris Stake"  wrote:
>
>> Hi Bob,
>> Thanks for pointing-out the noisy output of the FE5680A. I'll probably try
>> to lock a crystal oscillator to it.
>> Unfortunately I don't have a suitable counter.
>> I was hoping I could use some sort of higher frequency standard but I
>> confess I had not really grasped the fact that the unit may well be within
>> millihertz of the nominal frequency: too delicate to twiddle with anything
>> other than precision equipment and long timebases.
>> Kind regards
>> Chris
>> 
>>> -Original Message-
>>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>>> Behalf Of Bob Camp
>>> Sent: 14 March 2012 16:57
>>> To: 'Discussion of precise time and frequency measurement'
>>> Subject: Re: [time-nuts] FE5680A Calibration
>>> 
>>> Hi
>>> 
>>> Do you have a dual channel counter that you can put the GPS into on the
>>> "start" and the FE into as the "stop"? The HP 5334, 5335, and 5345 are all
>>> examples of this sort of counter.
>>> 
>>> Bob
>>> 
>>> -Original Message-
>>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>>> Behalf Of Chris Stake
>>> Sent: Wednesday, March 14, 2012 12:49 PM
>>> To: 'Discussion of precise time and frequency measurement'
>>> Subject: Re: [time-nuts] FE5680A Calibration
>>> 
>>> Nice idea,
>>> But I haven't got a DSO and the persistence of my scope isn't good enough
>>> to
>>> view 10Mhz sampled at 1pps.
>>> Chris
>>> 
 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of EB4APL
 Sent: 14 March 2012 15:46
 To: time-nuts@febo.com
 Subject: Re: [time-nuts] FE5680A Calibration
 
 My fast approach would be to trigger a scope with the 1 PPS from the GPS
 receiver and observe the how the 10 MHz output of your Rb drifts.  1
 full cycle per second is 1 e-7 so you'll need to use an stopwatch to
 time long periods when you are fine adjusting .
 Building (or buying) a GPSDO allows yo to make the comparison between
 both 10 MHz outputs without the jitter in the GPS receiver 1 PPS.
 Probably others in this list can suggest more elaborated and convenient
 approaches to this.
 
 On 14/03/2012 16:17, Chris Stake wrote:
> Hello all,
> 
> I purchased a FE5680A from a Chinese  Ebay vendor. I have connected it
 to a
> 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to
 drive
> a LED for the "locked" signal. I can communicate with it using the
 excellent
> Fe5680Calibrator software. As received the frequency offset is set to
 Zero
> and the unit seems to work well.
> 
> I plan to put it into service as a workshop frequency reference and so
 would
> like to set it close to 10.0Mhz. I have various oscillator modules,
 signal
> generators, SDR receivers, GPS receivers, a scanner, some uncalibrated
> test-gear. I live in a river valley in North Devon UK so radio
>>> reception
 is
> a bit restricted but I receive digital television via a masthead
 amplifier
> and long downlead.
> 
> Could someone please suggest a way of going about this?
> 
> 
> 
> Regards
> 
> Chris Stake
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-
 bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
 
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-
>>> bin/mailman/listinfo/time-
 nuts
 and follow the instructions there.
>>> 
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> 
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-
>>> nuts
>>> and follow the instructions there.
>> 
>> 
>> _

Re: [time-nuts] Experience with THS788 from TI?

[David]

I am surprised it is not more accurate and precise.  Even old discrete
designs can get down to 10ps or better.  I wonder what market it is
for where space is at that much of a premium.

On Wed, 21 Mar 2012 14:47:28 +0100, "Heinzmann, Stefan  (ALC NetworX
GmbH)"  wrote:

>I just discovered that TI makes a TDC chip called THS788, see 
>http://www.ti.com/product/ths788 for more info. Interesting specs, but rather 
>expensive. Has anyone from the list had a chance to experiment with this 
>device?

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

Re: [time-nuts] Experience with THS788 from TI?

[David]

On Wed, 21 Mar 2012 11:51:53 -0400, Ben Gamari 
wrote:

>On Wed, 21 Mar 2012 09:44:14 -0500, David  wrote:
>> I am surprised it is not more accurate and precise.  Even old discrete
>> designs can get down to 10ps or better.  I wonder what market it is
>> for where space is at that much of a premium.
>> 
>Out of curiosity, would you happen to have an example of discrete TDC
>design? Recently I've been exploring the TDC design space as these
>devices are a critical part of our experiments (I do spectroscopy of
>biological molecules). I'm currently (slowly) working on a FPGA TDC
>design (based on the PandaDAQ[1] and CERN's Spartan 6 TDC design) but it
>seems it will be non-trivial to get down to the 12 ns the commercial
>offerings provide (although at great cost). What would a discrete TDC
>design look like?  Are there any designs in the open?

I read through the THS788 datasheet.  TI DLL multiplies the 200
external clock to 1.2GHz for the 833ps basic cycle.  That is further
divided into 64 13ps time intervals which are latched to generate the
6 least significant bits of the time stamp.  I suspect the time
intervals are implemented as a locally generated 64 phase 1.2GHz
clock.

Check out the design for the Tektronix 7T11/7T11A sampling sweep unit
or their earlier sampling sweep plug-ins.  The service manuals with
theory and schematics are available online.

You might also want to look at the clock delay timer design in the
Tektronix 2230/2232 and the 2440 oscilloscopes which is used to align
equivalent time acquisitions with the waveform record.

An all digital design like the THS788 does have a much higher
throughput but the analog designs I mention above did not have
throughput as a requirement.

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

Re: [time-nuts] DTV tuner chip usable for GPS front end?

[David]

On Wed, 21 Mar 2012 16:40:27 -, "David J Taylor"
 wrote:

>> I suppose there is limited interest in homebrew GPS receivers given how 
>> cheap the fully integrated chipsets are. However, just noticed the below 
>> tuner chip intended for DTV, actually lists GPS L1 as an applicable 
>> frequency.  A TV Tuner USB stick using this chip is available for $20, 
>> and some SDR type software is apparently working with it:
>> http://sdr.osmocom.org/trac/wiki/rtl-sdr   Has anyone here played with 
>> this device?
>>
>> from http://www.elonics.com/product.do?id=1
>> "The E4000 is a highly integrated multi band RF tuner IC implemented in 
>> CMOS, ideal for low power digital terrestrial TV and radio broadcast 
>> receiver solutions.  The E4000 contains a single input LNA with RF 
>> filter, whose centre frequency can be programmed over the complete 
>> frequency range from 64MHz to 1700MHz."
>>
>> Broadcast Standards
>>DVB-T (174-240MHz, 470-854MHz)
>>ISDB-T (470-862MHz)
>>DVB-H (470-854MHz, 1672-1678MHz)
>>CMMB (470-862MHz)
>>D-TMB (470-862MHz)
>>T-DMB (174-240MHz, 1452-1492MHz)
>>DAB (174-240MHz, 1452-1492MHz)
>>MediaFLO (470-862, 1452-1492MHz)
>>GPS L1 band (1575MHz)
>>
>> [...]
>
>.. and available ready built here:
>
>  http://www.funcubedongle.com/
>
>but perhaps not fast enough for you.

Or not wide enough in this case.  The FunCube technical FAQ says the
bandwidth is about 80 KHz as it is designed for narrow band reception
only and accessed as a standard USB sound device.  I do not quite
understand how 96 Ksamples/sec yields 80 KHz though:

Q. What is the bandwidth?
A. 96kHz is the quadrature sampling rate. Once the ADC’s decimation
filter skirts have been taken into account, you have about 80kHz.


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

Re: [time-nuts] Experience with THS788 from TI?

[David]

On Wed, 21 Mar 2012 18:52:33 -0400 (EDT), saidj...@aol.com wrote:

>Alternatively, if you want to design your own, you could use a  
>time-expander. It only requires a small micro with counter/timer, and a  
>little bit of 
>external circuitry for charging/discharging a precision cap. You  charge 
>fast gated by the signal to measure, then you discharge slowly (expanded  
>time) 
>and measure the amount of charge deposited on the cap. The Linear Appnote  
>I mentioned earlier already has most of the capacitor charge pump circuitry 
>in  it that you would need for this.
>
>The idea is to design the cap discharge and charge cycles at  different 
>time scales, say 1000x to 1, so that the capture time get's expanded  out to 
>intervals that the micro can measure. If the micro has say 60MHz counter  
>resolution (16.66ns) then a 1000x to 1 expansion would allow a 0.016ns (16ps)  
>resolution. Using say 2000x expansion and a 100MHz counter in the  micro 
>would get you to 5ps resolution.

The Tektronix 2230 and 2232 oscilloscopes I mentioned earlier work
this way.  The 2230 service manual gives a very detailed description
of the circuit.  The 2230 uses the 50ns sampling clock as a
calibration source and divides it into 200 counts for 250ps of
resolution which is all that was needed given the oscilloscope
bandwidth and record length.

The Tektronix 7T11/7T11A TTH (Time to Height converter) is
considerably more complex but has a resolution in the ps range and
high throughput (50Ksamples/sec) as well.  It uses an FET input
capacitance feedback integrator (Miller Integrator) with an FET reset
that includes gate charge compensation.  At the fastest sweep speed,
the output changes by 10ps/mv.  Part of the complexity comes from
being designed to measure negative time as well if the trigger and
strobe are reversed.

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

Re: [time-nuts] HP 3586B Power Supply Failures

[David]

I just went through this exercise with a pair of Tektronix PS503A
power supplies which differed in manufacturing date by 10 years.

On Wed, 21 Mar 2012 21:55:39 -0700 (PDT), Perry Sandeen
 wrote:

>The other day I had my second HP 3586B power supply board smoked.  It burned 
>both the PC board traces and the connector on the motherboard so badly it will 
>have to be replaced.  Also an inch or so of one trace on the mother board but 
>it looks like it will be repairable.  Fortunately I have a donor board for the 
>connector but it will probably be an all-day project to do the repair properly.
>
>An observation.  There AFAIK a fold-back current limiting circuit but it 
>didn’t help and the correct value of primary fuse did not blow.  This made me 
>an extremely unhappy camper.  I’m also going to try and figure out how to add 
>additional fuses.  
>
>So I went through the entire instrument and came up with a list of all the 
>Sprague TVA electrolytics that I am going to replace as they are dated coded 
>1983.
>
>So two questions.  One, can I safely double the capacitance of the filter 
>capacitors?  (I plan on using the 105C 10K hour high reliability Nichicon or 
>Panasonic units.)  

The inrush power will be larger but the current may be limited by the
circuit impedance.  The risk is that the rectifiers may not be able to
handle the larger surge current.

I used standard snap-in capacitors with the same diameter to replace
the aluminum can style capacitors.  They were about 1/4 the length but
could use the existing mounting hardware.

>Secondly, the tantalum filter caps seem OK but can they be replaced with the 
>same high quality aluminum electrolytics perhaps of a higher value of 
>capacitance?

The late Tektronix PS503A power supplies replaced the 4.7uF solid
tantalums with 10uF aluminum electrolytics.  When I was pouring over
the specifications of the Sprague 199D tantalums they originally used,
I found that in the general case, an aluminum electrolytic of twice
the value had roughly the same dissipation factor.

>Additionally, I plan on doing the same to all my vintage HP test equipment.  A 
>smoked 5370B would really, really, really, ruin my week.

I have had a couple of shorted tantalums but never with the dire
results you experienced.  In your case, I might change them all out as
well.

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

Re: [time-nuts] HP 3586B Power Supply Failures

[David]

On Thu, 22 Mar 2012 12:04:30 +0100, Attila Kinali 
wrote:

>On Wed, 21 Mar 2012 22:33:49 -0700
>"John Miles"  wrote:
>
>> I did this for a while, but I eventually realized that new
>> "computer grade" electrolytic capacitors no longer have the same
>> quality levels that they must have had in the 1970s and 1980s.
>>  Back then, orders of magnitude more of them would have been used in
>> production than are used today, and the manufacturers would have paid
>> more attention to what they were doing.   After my first few encounters
>> with high-ESR parts out of the retail box, I stopped replacing good ones. 
>
>That's not really true. More electrolytics are used today than were in the
>70s and 80s, mostly because a lot more electronics is build today.
>What is different though is that those electrolytics are more optimized
>to be cheap than they were before. Which means that you have to more
>carefully select the capacitor you are going to use. Main stuff you have
>to look for is: ESR, maximum ripple current, operating temperature.
>Especially the ripple current is important as this is what kills most
>electrolytics in "cheap" or not well designed circuits these days.

In the two Tektronix PS503As that I just rebuilt, out of 4 big
aluminum can style input and 4 small axial style output electrolytic
capacitors, the one of each set that went bad where marked "made in
mexico" and had no identifiable manufacturer.  The other 3 of each set
were clearly marked Mallory for the large input ones and Sprague for
the small output ones.

In some old switching power supplies I fixed a couple of weeks ago,
the axial Cornell Dubilier capacitors were in excellent shape while
almost every other capacitor was worn out.

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

Re: [time-nuts] Anyone familiar with SR-620 repair?

[David]

I just tracked down a shorted tantalum in a Tektronix DM501
multimeter.  It was on the output of the floating -12 volt supply
bridge rectifier before the regulator.  The current level was so low
that it never heated up although I burned two fingers on the push-pull
output transistors for the floating supply.  The regulator is on a
separate module but the supply was still shorted when I pulled it and
the bad tantalum was the only part left.

I have not seen a shorted tantalum before where it could not be surge
current related until now.

On Sat, 24 Mar 2012 00:08:12 -0400, Peter Gottlieb 
wrote:

>I had a HP 3326 which had a power supply in foldback. All the modules are 
>inaccessible unless you have a rather rare set of extenders anyway. The 
>voltmeter method quickly led me to the board and a bench supply and meter 
>again to the shorted cap. Very easy. Other times I've borrowed the FLIR camera 
>from work, also taught the new EEs that trick as well.  It is a true lifesaver 
>on dense surface mount boards. I haven't tried the liquid crystal sheet but it 
>seems like an interesting idea so long as everything is about the same height. 
>
>
>Peter
>
>On Mar 23, 2012, at 11:53 PM, li...@lazygranch.com wrote:
>
>> Prior to emission or IR microscope technology, liquid crystals was how you 
>> found hotspots on ICs. I've done this with a goop that you dispense with a 
>> syringe. 
>> 
>> One trick to make this more sensitive is you bring a soldering iron close to 
>> the  liquid crystals. Not so close as to cause a change, but you get them 
>> closer to the phase change point. 
>> 
>> 
>> -Original Message-
>> From: Skip Withrow 
>> Sender: time-nuts-boun...@febo.com
>> Date: Fri, 23 Mar 2012 21:07:45 
>> To: 
>> Reply-To: swith...@alum.mit.edu,
>>Discussion of precise time and frequency measurement
>>
>> Subject: [time-nuts] Anyone familiar with SR-620 repair?
>> 
>> You don't need expensive test equipment to find this kind of problem.  What
>> I use is a sheet of liquid crystal film with a transition temperature just
>> slightly above your room temperature.  Just lay it on the circuit board and
>> you can find where the power is being dissipated (even if pretty small) by
>> watching the colors change.
>> 
>> I think Omega Engineering sells a 8.5" x 11" sheet for about $18 if memory
>> serves me.  I have used this trick many times and it works great to find
>> shorted (bypass) caps.  No disconnecting anything, no milliohm meters, no 4
>> or 5 digit voltmeters.

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

Re: [time-nuts] Anyone familiar with SR-620 repair?

[David]

The capacitor was cool in this case because the floating supply was
current limited do to the design so the power dissipation was limited.
The transistors driving the isolation transformer were beta limited
and the output current after the transformer was on the order of 200
milliamps.  Had the capacitor been on the input side, the short
circuit current would have been an order of magnitude or two higher
and I expect it would have been hot or even caught on fire.  The only
thing that made it easy to find was that removing the post regulator
as a module left only that one capacitor in the circuit.

I actually have a far IR camera but did not get to breaking it out for
this project.  I did manage to burn two Mark I Fingers though on the
metal transistor cans.  The DM501 I fixed supports a simple delta Vbe
temperature probe so at some point I think I will build one.  All I
need is the LEMO connector.

I would really like to know though why it failed in a non-surge
related way at such a low current level.  Previously I have only seen
them fail where it could have been surge current related.

On Sat, 24 Mar 2012 06:45:12 -0700 (PDT), "J. Forster"
 wrote:

>Nope.
>
>The cap was cool because the thing was shorted and had no voltage across
>it. Power is V * I.
>
>As I said before, either an open or a short circuited component dissipates
>no power.
>
>The defective component is NOT always the hot one. A hot component is only
>a pointer to the fault, not necessarily the problem itself.
>
>This is especially true of fuses. Always ask "Why did the fuse blow??"
>
>-John
>
>=
>
>
>> I just tracked down a shorted tantalum in a Tektronix DM501
>> multimeter.  It was on the output of the floating -12 volt supply
>> bridge rectifier before the regulator.  The current level was so low
>> that it never heated up although I burned two fingers on the push-pull
>> output transistors for the floating supply.  The regulator is on a
>> separate module but the supply was still shorted when I pulled it and
>> the bad tantalum was the only part left.
>>
>> I have not seen a shorted tantalum before where it could not be surge
>> current related until now.
>>
>> On Sat, 24 Mar 2012 00:08:12 -0400, Peter Gottlieb 
>> wrote:
>>
>>>I had a HP 3326 which had a power supply in foldback. All the modules are
>>> inaccessible unless you have a rather rare set of extenders anyway. The
>>> voltmeter method quickly led me to the board and a bench supply and meter
>>> again to the shorted cap. Very easy. Other times I've borrowed the FLIR
>>> camera from work, also taught the new EEs that trick as well.  It is a
>>> true lifesaver on dense surface mount boards. I haven't tried the liquid
>>> crystal sheet but it seems like an interesting idea so long as everything
>>> is about the same height.
>>>
>>>
>>>Peter
>>>
>>>On Mar 23, 2012, at 11:53 PM, li...@lazygranch.com wrote:
>>>
 Prior to emission or IR microscope technology, liquid crystals was how
 you found hotspots on ICs. I've done this with a goop that you dispense
 with a syringe.

 One trick to make this more sensitive is you bring a soldering iron
 close to the  liquid crystals. Not so close as to cause a change, but
 you get them closer to the phase change point.


 -Original Message-
 From: Skip Withrow 
 Sender: time-nuts-boun...@febo.com
 Date: Fri, 23 Mar 2012 21:07:45
 To: 
 Reply-To: swith...@alum.mit.edu,
Discussion of precise time and frequency measurement

 Subject: [time-nuts] Anyone familiar with SR-620 repair?

 You don't need expensive test equipment to find this kind of problem.
 What
 I use is a sheet of liquid crystal film with a transition temperature
 just
 slightly above your room temperature.  Just lay it on the circuit board
 and
 you can find where the power is being dissipated (even if pretty small)
 by
 watching the colors change.

 I think Omega Engineering sells a 8.5" x 11" sheet for about $18 if
 memory
 serves me.  I have used this trick many times and it works great to
 find
 shorted (bypass) caps.  No disconnecting anything, no milliohm meters,
 no 4
 or 5 digit voltmeters.
>>
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>
>
>
>___
>time-nuts mailing list -- time-nuts@febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

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

Re: [time-nuts] Distribution amp - Use a video amp unit ?

[David]

On Sun, 25 Mar 2012 16:39:57 -0700, gary  wrote:

>I'm not so sure about the circuit. The base drive on Q3 is more of less 
>AC given that the resistor can only pull current out of the base. That 
>is, I don't see a DC bias on Q3.

R7, R8, and LED D2 sets the base voltage at about 1.8 volts through
R4.  Subtract Vbe and Q3's idle current will be about 36 milliamps set
by 1.2 volts across the 33 ohm emitter resistor.

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

Re: [time-nuts] Rigol scopes

[David]

On Wed, 18 Apr 2012 13:56:18 +, shali...@gmail.com wrote:

>That's why the default mode for a DSO should always be "pulse detect" or 
>whatever the manufacturer calls it, unless you know what you are doing. As far 
>as I know, all DSOs have this or an equivalent mode where the ADC runs at full 
>speed regardless of sweep speed, and the min and max readings between two 
>display points are stored. If you are in a condition that would otherwise 
>result in aliasing, the trace will look like a big fat trace, just like on an 
>analog scope if you are probing a 10MHz signal at 1mS/div.

Do the low end Rigol oscilloscopes actually support peak detection?
The manual only describes an envelope mode without any ability to set
the number of envelopes like a Tektronix 2440 can for single shot peak
detection.  When I was in the market for a DSO a couple years ago, the
Rigol representatives could not answer.  I ended up rebuilding an old
Tektronix 2230.

>You get the same issue with an analog sampling scope, except that those don't 
>have a "pulse detect" mode, so they WILL lie to you unless you know what you 
>are doing. It is not a "digital storage" issue, it is a sampling issue.

Sampling oscilloscopes are in a class all to their own and very
specialized.  Their low sample rates hinder capturing infrequent
events but if a repetitive glitch is there, they can still see it.  A
non-sampling oscilloscope with limited bandwidth could just as easily
miss a narrow pulse because of bandwidth constraints no matter how
high its sampling rate.

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

Re: [time-nuts] Rigol scopes

[David]

On Wed, 18 Apr 2012 08:38:52 -0500, Bob Smither 
wrote:

>On 04/17/2012 06:38 AM, Robert Atkinson wrote:
>> I quite like the HP 546xx series 'scopes. An "analog like" interface but good
>> DSO facilities. My regular 'scope at home is a 54645D mixed signal. Ideal for
>> lower speed logic/anlog circuits and 8 bit PICs. Takes up a lot less space
>> than a 16500x logic analyser! I still keep an older analog 'scope tucked away
>> though.
>
>Agreed.  I have two of the 54645Ds - my favorite scopes.  I added the 54657A
>module to one of them - gives it GPIB, more storage, and more measurements 
>(FFT,
>waveform math, ...)

My favorite oscilloscope is my 2230.  I did not buy a Rigol because as
far as I was able to determine, they do not support single shot peak
detect.

>I also have Tek 7000 and 5000 series analog scopes, along with a older Tek
>digital (Oh! - am I becoming a collector? :-).  These mainly gather dust these 
>days.

The more I use my 7000 series oscilloscopes the more I like them. 7A13
differential amplifiers allow safe probing of offline switching power
supplies, the dual independent time bases can trigger from and view
separate asynchronous signals, and the samplers while tricky to use
are great for high speed design.

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

Re: [time-nuts] Rigol scopes

[David]

I would agree that a DSO with a peak detect mode is the way to go for
general purpose work.  I just wish the cheap ones had delayed sweep
and faster waveform acquisition rates instead of long record lengths.

When I was diagnosing an offline switching power supply a few weeks
ago that was stuck in pulse mode, digital storage mode on my Tektronix
2230 saved the day.

On Thu, 19 Apr 2012 21:54:16 +, shali...@gmail.com wrote:

>"A non-sampling oscilloscope with limited bandwidth could just as easily
>miss a narrow pulse because of bandwidth constraints no matter how
>high its sampling rate."
>
>That is the point of the thread. Even a wide bandwidth analog scope used to 
>show a 500nS pulse at a 200Hz repetition rate will have a hard time, while any 
>DSO worth the name will have no problem with it.
>
>Didier KO4BB
>
>Sent from my BlackBerry Wireless thingy while I do other things...
>
>-Original Message-
>From: David 
>Sender: time-nuts-boun...@febo.com
>Date: Wed, 18 Apr 2012 18:11:29 
>To: Discussion of precise time and frequency measurement
>Reply-To: Discussion of precise time and frequency measurement
>   
>Subject: Re: [time-nuts] Rigol scopes
>
>On Wed, 18 Apr 2012 13:56:18 +, shali...@gmail.com wrote:
>
>>That's why the default mode for a DSO should always be "pulse detect" or 
>>whatever the manufacturer calls it, unless you know what you are doing. As 
>>far as I know, all DSOs have this or an equivalent mode where the ADC runs at 
>>full speed regardless of sweep speed, and the min and max readings between 
>>two display points are stored. If you are in a condition that would otherwise 
>>result in aliasing, the trace will look like a big fat trace, just like on an 
>>analog scope if you are probing a 10MHz signal at 1mS/div.
>
>Do the low end Rigol oscilloscopes actually support peak detection?
>The manual only describes an envelope mode without any ability to set
>the number of envelopes like a Tektronix 2440 can for single shot peak
>detection.  When I was in the market for a DSO a couple years ago, the
>Rigol representatives could not answer.  I ended up rebuilding an old
>Tektronix 2230.
>
>>You get the same issue with an analog sampling scope, except that those don't 
>>have a "pulse detect" mode, so they WILL lie to you unless you know what you 
>>are doing. It is not a "digital storage" issue, it is a sampling issue.
>
>Sampling oscilloscopes are in a class all to their own and very
>specialized.  Their low sample rates hinder capturing infrequent
>events but if a repetitive glitch is there, they can still see it.  A
>non-sampling oscilloscope with limited bandwidth could just as easily
>miss a narrow pulse because of bandwidth constraints no matter how
>high its sampling rate.
>
>___
>time-nuts mailing list -- time-nuts@febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.
>___
>time-nuts mailing list -- time-nuts@febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

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

Re: [time-nuts] PICTIC II ready-made?

[David]

Their technology paper talks a lot about differential inputs and
outputs but their 74G series is naturally all single ended.  They also
discuss using multiple bond wires to reduce inductance so maybe that
was all that was needed.

They sell through an Ebay store but given the price of $3 per chip and
$2 for shipping and handling, I would be inclined to design with
readily available ECL which is not much more expensive.

On Wed, 25 Apr 2012 19:17:43 -0300, Daniel Mendes 
wrote:

>
>About replacing the 74ACT175... there´s a company called "Potato Semi" 
>(well.. they make "chips", right?) whose sole business is to make damn 
>fast 74 logic. Their chips can be bought at ebay in small quantities. 
>Look at this 600MHz D flip flop:
>
>http://www.potatosemi.com/potatosemiweb/datasheet/PO74G74A.pdf
>
>Daniel
>
>Em 25/04/2012 16:15, Bruce Griffiths escreveu:
>> Chris Albertson wrote:
>>> On Wed, Apr 25, 2012 at 9:37 AM, Don Latham  wrote:
>>>
 I forgot to add that a simple redrafting of the II as an Arduino shield
 with appropriate chips and chip passives would accomplish the desired
 end without losing the very careful engineering and testing that has
 already been done?
 Would be nice to have a way to change caps without soldering as well,
 maybe just some .1" jumpers?
>>>
>>> Yes, MOST of the design could be re-used.  As an Arduino shield there 
>>> is no
>>> need for a PIC or RS-232 interface becusethe Arduino does that function.
>>>   You'd need to replace the 74ACT175 part but that is not hard.
>>>
>>> About changing the cap values without soldering.  I guess you could push
>>> the leads into a 0.1 inch header strip or install several and use a DIP
>>> switch to select which are "in".   But I don't know if the extra 
>>> inductance
>>> al that wiring adds is enough to worry about.
>>>
>> The time to digital converter (TDC) section is merely an interpolator 
>> that measures the delay of a synchroniser.
>> The TDC range should be about 2 clock periods to accommodate the range 
>> of synchroniser delays and to facilitate calibration.
>> Unless one is changing the synchroniser clock period there is no need 
>> to vary the TDC gain.
>> The SR620 uses a similar interpolator and has only a single 
>> interpolator range.
>> The range is extended by counting the number of synchroniser clock 
>> periods between synchroniser output transitions of interest.
>> When measuring the time interval between 2 signals a pair of 
>> synchronisers and interpolators are used.
>>
>> Interpolator nonlinearity can be measured by using a statistical fill 
>> the buckets technique which uses nothing but a pair of noisy 
>> asynchronous oscillators with high reverse isolation to avoid 
>> injection locking.
>>
>> If a suitable ADC is used the interpolator can be simplified 
>> considerably whilst improving its performance.
>> Minor nonlinearities are of little significance, as long as they are 
>> repeatable and relatively stable they can be easily corrected in 
>> software.
>>
>> Bruce

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

Re: [time-nuts] PICTIC II ready-made?

[David]

On Wed, 25 Apr 2012 11:13:42 -0700, Chris Albertson
 wrote:

>On Wed, Apr 25, 2012 at 9:37 AM, Don Latham  wrote:
>
>> I forgot to add that a simple redrafting of the II as an Arduino shield
>> with appropriate chips and chip passives would accomplish the desired
>> end without losing the very careful engineering and testing that has
>> already been done?
>> Would be nice to have a way to change caps without soldering as well,
>> maybe just some .1" jumpers?
>
>Yes, MOST of the design could be re-used.  As an Arduino shield there is no
>need for a PIC or RS-232 interface becusethe Arduino does that function.
> You'd need to replace the 74ACT175 part but that is not hard.
>
>About changing the cap values without soldering.  I guess you could push
>the leads into a 0.1 inch header strip or install several and use a DIP
>switch to select which are "in".   But I don't know if the extra inductance
>al that wiring adds is enough to worry about.

One problem with the design in this case is that it requires 8 or 9
I/O pins making the use of additional Arduino shields difficult. Would
you add tri-state buffering and a chip select?

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

Re: [time-nuts] PICTIC II ready-made?

[David]

On Wed, 25 Apr 2012 21:26:25 +0200, Attila Kinali 
wrote:

>Hi Bruce,
>
>On Thu, 26 Apr 2012 07:15:41 +1200
>Bruce Griffiths  wrote:
>
>> If a suitable ADC is used the interpolator can be simplified 
>> considerably whilst improving its performance.
>
>Could you tell a little bit more about what a "suitable ADC" for
>a time interpolator is? And how exactly does it help to simplify
>the interpolator?

If you add a second lower current source or sink, then you can get
away with a LM311 class comparator and one fast timer channel in the
microcontroller.  The input pulse width charges the capacitor and the
timer counts how long it takes to slowly discharge.  Since the
conversion is integrating instead of sampling, it has better noise
immunity.

The Tektronix 2440 uses this technique to get about 50ps resolution.

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

Re: [time-nuts] GPS, USGS Early Earthquake Warning

[David]

On Fri, 27 Apr 2012 00:55:40 -0700, Hal Murray
 wrote:

>
>Fun talk at the USGS last (Thur) night:
>  ShakeAlert!
>  --building an earthquake early warning system for California
>  by Doug Given
>
>He's a good speaker.  If you get a chance to hear him, go for it.
>  http://online.wr.usgs.gov/calendar/
>The video should be up in their archives in a few days.
>  http://online.wr.usgs.gov/calendar/2012.html
>(scroll down to April)
>
>The basic idea is to detect an earthquake at location X, and then spread the 
>word using telecommunications.  Earthquakes propagate at 2 miles/sec so 
>phone/internet is much faster.  Ballpark is 30-60 seconds of warning.
>
>The reason this might be interesting for time-nuts is that he mentioned using 
>GPS to supplement seismometers.  The context is that they need the answer in 
>a few seconds.  I didn't catch any details.
>
>It's unlikely that they are doing any fancy post-processing.  I suppose it's 
>possible that they have streamlined the traditional post-processing setup so 
>that they can do it in a few seconds.  Maybe that is mostly getting an early 
>look at the data the traditional post-processing processing uses.

Through the 80s and 90s I monitored the W6FXN 2 meter amateur radio
repeater which was located near Cal Poly Pomona.  It was setup to
rebroadcast one of the USGS tone modulated seismic sensors when it
deviated from rest.  The warning time depended on the geometry but was
typically 5 to 10 seconds for Orange County since most of the
earthquakes like Whittier-Narrows, Loma Prieta, and Northridge
originated closer to the seismometer than where I lived.

It did not distinguish between local and far earthquakes but you could
hear the separation in the S and P waves and tell small from large
with a little experience.  I also heard the last couple of underground
atomic tests.

Latency in the warning was on the order of milliseconds.

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

Re: [time-nuts] PICTIC II ready-made?

[David]

On Fri, 27 Apr 2012 15:52:33 +0200, Attila Kinali 
wrote:

>On Wed, 25 Apr 2012 19:17:43 -0300
>Daniel Mendes  wrote:
>
>> About replacing the 74ACT175... there´s a company called "Potato Semi" 
>> (well.. they make "chips", right?) whose sole business is to make damn 
>> fast 74 logic. Their chips can be bought at ebay in small quantities. 
>> Look at this 600MHz D flip flop:
>> 
>> http://www.potatosemi.com/potatosemiweb/datasheet/PO74G74A.pdf
>
>Hmm... looks interesting. Though, i probably would take
>standard ECL instead of those because of higher availability
>(you can get them from mouser, digikey & co).

I would like to see some real world test results.  They charge $3 per
74G chip plus shipping through their Ebay store so the total price is
not much lower than ECL from Mouser or Digikey.

>But good to know that at least someone is still trying to improve
>standard 74xx devices, for all those who do not want to use an CPLD/FPGA.

I have been going through various papers plus the Xilinx and Altera
forums reading about time delay counter design in connection with a
project I am working on involving equivalent time and high bandwidth
sampling.  One of the problems they have with the FPGA and CPLD
designs in significant input jitter even before the delay time chain
is considered.  For best results, all I/Os and other functions have to
be inactive during the measurement.  One of the papers discussed
disabling the LED heartbeat indicator to gain about 50ps of accuracy.

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

Re: [time-nuts] PICTIC II ready-made?

[David]

On Fri, 27 Apr 2012 16:30:11 +0200, Attila Kinali 
wrote:

>On Wed, 25 Apr 2012 23:30:45 -0500
>David  wrote:
>
>> If you add a second lower current source or sink, then you can get
>> away with a LM311 class comparator and one fast timer channel in the
>> microcontroller.  The input pulse width charges the capacitor and the
>> timer counts how long it takes to slowly discharge.  Since the
>> conversion is integrating instead of sampling, it has better noise
>> immunity.
>
>Yes, a dual slope time strecher would work too. I'm not sure, but
>i would guess this aproach would be a lot more limited by the noise
>and device variations.

It would be a lot more immune to noise.  Both integrating and sampling
designs suffer from the same device variations which can be removed
through self calibration.

>Usually a timing input of an uC runs with a counter in the region
>of 100MHz max, ie +/-5ns resolution. To get to 50ps, one would need
>to stretch it by a factor of 100 at least, better 1000 to get some
>headroom for calibration in software. This means that the currents
>have to have a factor of 1000 in between. Using a charge current
>somewhere between 10 to 100mA would yield to a discharge current
>between 10 to 100uA. Keeping the two current sources stabile
>enough for the ratio to stay stable would be already quite an
>acheivment. Also keeping the leakage currents at bay would be
>quite some feat...

That is about the performance level of the Tektronix 2440 delay time
counter.  The counter only runs at 40 MHz but both edges of the 500
MHz sampling clock are used with two integrators so that metastability
can be detected and resolved.  The charge current is fixed at about
25mA and the discharge current is set during self calibration to
maintain a 1250:1 ratio at about 20uA.

Stability should not be a problem in the analog design when self
calibration is used and that is required at higher performance levels
anyway.  Even the high offset voltage and bias current of the bipolar
technology LM311 only contributes offset and gain error which is how
they got away with 100pf of integration capacitance.

>In contrast to that, a 16bit ADC is dirty cheap and a 24bits are readily
>available. I haven't had a look at it yet, but if the capacitive charge
>redistribution ADCs simplifiy the circuitry that much as Bruce has said, then
>you could get "easily" 16-18bit resolution. Combine that with a 100MHz
>reference clock, then you get a nominal resolution 150-40fs(!). 
>Acheiving 10ps resolution should be then a piece of cake and 1ps possible.
>(yes, i know that 10ps is not that easy...)

Charge redistribution ADCs by design have a built in sample and hold
which can simplify external circuitry and like delta-sigma converters,
they can be built on a digital logic process.  In this case, the
simplification is in comparison to non-sampling converters where the
signal level has to be constant during the conversion cycle for valid
results.

The advantage with the dual slope design is that it is integrating so
high frequency noise is ignored.  Controlling noise in a
microcontroller sampling ADC even at the 10 bit level is a significant
challenge.  In a conservative design, I usually start by figuring the
loss of one bit do to DNL and another bit do to noise.  If you want
better performance, the ADC either needs to be integrating or external
where noise can be better controlled.

I have been looking at a better than 10ps performance design but not
primarily for GPS timing applications.  I am more interested in
equivalent time sampling and high bandwidth sequential or random time
sampling.  The later can not use an integrating converter because of
sampling rate requirements.

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

Re: [time-nuts] PICTIC II ready-made?

[David]

I have been looking at CPLD and FPGA designs for aggregating the logic
required but keep running up against their lack of jitter
specifications for asynchronous applications.  Is the part and
development cost worth replacing a handful of discrete logic when the
CPLD or FPGA is dedicated to such a small function?

I figured I would just have to try a couple of designs and measure how
well they do.

On Fri, 27 Apr 2012 10:54:57 -0400 (EDT), ewkeh...@aol.com wrote:

>The Altera Max 3000A as I mentioned before will do all TTL devices, it has  
>an extensive library easy to use and very cheap. All That at 200 MHz. I 
>became a  believer and others I introduced to it love it to. In an hour from 
>downloading  the free software you can have your first design. If I can do it 
>every body can  do it.  
>Bert Kehren
> 
> 
>In a message dated 4/27/2012 9:53:16 A.M. Eastern Daylight Time,  
>att...@kinali.ch writes:
>
>On Wed,  25 Apr 2012 19:17:43 -0300
>Daniel Mendes   wrote:
>
>> About replacing the 74ACT175... there´s a company called  "Potato Semi" 
>> (well.. they make "chips", right?) whose sole business  is to make damn 
>> fast 74 logic. Their chips can be bought at ebay in  small quantities. 
>> Look at this 600MHz D flip flop:
>> 
>>  http://www.potatosemi.com/potatosemiweb/datasheet/PO74G74A.pdf
>
>Hmm...  looks interesting. Though, i probably would take
>standard ECL instead of  those because of higher availability
>(you can get them from mouser, digikey  & co).
>
>But good to know that at least someone is still trying to  improve
>standard 74xx devices, for all those who do not want to use an  CPLD/FPGA.
>
>
>Attila  Kinali

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

Re: [time-nuts] pictic improvements was PICTIC II ready-made?

[David]

On Fri, 27 Apr 2012 10:19:17 -0500, "Stanley" 
wrote:

>Several practical replacements were provided if the 74ac175 dip was 
>impossible to find, see the wiki :
>http://ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
>
>The issue was the voltage level of on and off  not the speed of the chip, 
>one goal of the project was to keep the interpolators as simple as possible 
>and to use the PIC as much as possible. So the design has several options: 
>no interpolators, interpolators with and without the 2x gain buffer, plus 
>the option of a faster clock speed as a way to reduce the need for 
>interpolators.
>
>From my stand point the simple or low-cost made it possible to have as many 
>TICs, many more than any other way.

I agree.

I apologize if my comments came across as criticisms of the PICTIC II
design.  My intention was to suggest possible alternatives and to
learn something in the discussion.

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

Re: [time-nuts] Pre-industrial timekeeping accuracy RE: Lifetime of glass containers

[David]

I'm getting slightly suspicious about the assumptions as to what was
available 2000 years ago, the remarkable Antikythera Mechanism points to
some technologies of 2000 years ago being almost up to medieval European
standards. Clearly Antikythera indicates there were a few stunning items
around, the fact that there is virtually no trace remaining of anything else
indicates the technology was very rare in its own time but its hard to
imagine a mechanisim like this being invented from nowhere to solely to make
one item and not pointing to small numbers of other intricate instruments
being made. The people who made the Antikythera Mechanism would surely have
been motivated to attempt timekeeping, Antikythera shows a competent
technology had been developed, we are very lucky to have any evidence after
2 millenia of such a rare device. Links:

http://news.bbc.co.uk/1/hi/sci/tech/6191462.stm

http://www.math.sunysb.edu/~tony/whatsnew/column/antikytheraI-0400/kyth1.htm
l

http://www.math.sunysb.edu/~tony/whatsnew/column/antikytheraII-0500/diff1.ht
ml

> Returning to a more time-nuts-y topic..
> 
> What sort of time measurement accuracy would folks 2000 years 
> ago have had?
> 
> For instance, were they aware of the (relative) constancy of 
> the swings of a pendulum of constant length?
> 
> I remember stories from school about Galileo using his pulse 
> as a clock. They're probably apocryphal, and I would think 
> that he would have easy access to other things that tick once 
> a second or there abouts (dripping water, etc, if not swings 
> of a pendulum).  
> 
> I'm also familiar with the famous Shakespearean anachronism 
> of the striking clock in "Julius Caesar", and the usual 
> commentary says the Romans had only sundials and clepsydra.  
> So how good is a clepsydra?  What if we go back a 1000 years?  
> 
>



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

Re: [time-nuts] upgrading agilent 53132 counter

[David]

Hi Alain

> i would upgrade my 53132 with an OCXO 10811, i have the 
> module, but i was told i 
> have to change the power supply too.
> It's yet the original HP 0950-2496 from Delta,  model :  
> DPS-43DL-2 (47 Watts). The remplacement type should be a HP 
> 53132-60208 (from the HP doc)  but i have 
> not the model ref from the fabricant.

I have a 54132 with the opt 012 'US OVEN'(OCXO 10811) and the 12.4GHz Ch3.
I've had a look at the PSU, it's the DPS-43DP-2, manufacturer is Delta I
think. I guess the unit was made in year 2000. I'd recommend that if you can
store an image of the eproms when you have it open, I've seen quite a few
reporting eprom errors on power up so I'm running on copies with the
originals and their images in storage 

Regards
David
GM4HJQ



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

Re: [time-nuts] upgrading agilent 53132 counter

[David]

Hi Alain

I can't help with the differences in the PSUs, there is little you can tell
by looking at the unit. I wonder if it might be easier to run the OCXO from
a new additional supply housed in the unit, there appears to be space for
this (?) and feed the 10MHz into the external REF I/P?  There are options.

> effectively, at power on, i have a message : rom failed, but 
> it seems to have no importance, since after actioning the 
> run touch, it works well (why ???). Do you really need an 
> image of the eprom ? 

Regarding the eproms, your fault description matches what I've seen in 3 or
4 units, all at first glance functional. The worry is that the fault clearly
was not there a few years ago and you have got to assume the worst, why
should it stop degrading? The blank parts are Am29F010B flash and were cheap
and available when I looked. Let me know if you want the image files I
generated of good parts emailed, the set of images etc in various formats is
about 1.7M (4 parts in 3 different file formats). 

David



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

Re: [time-nuts] upgrading agilent 53132 counter

[David]

Hi Alain

> So, how can i receive your files?

The ROM version you have is what I have (3944) so that eliminates worries
about incompatibilities (memory maps etc). 
I've sent a file to your email address, unzip it and the four images are
there in three formats with a readme.txt file and copies of the flash data
sheet.

Regards
David



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

Re: [time-nuts] 7150+ filter problem

[David]

> 
> 15 minutes is all it took for the signature ffzzt pop of 
> the filter letting go.
> 
> It has (to say the least), forced the issue.
> 
> Now I've removed all the solder around the earth pin, but I 
> still can't get the cover off. Does it just require brute 
> force to pull it off or there something else holding it on?

>> never taken an FN372 apart, not really worth it as?they are 
>> about ?25 from RS components. Most filters are epoxy potted 
>> so I think you will have to use a lot of brute force to open 
>> it up and then break up the epoxy.

I went the brutal route, I think I 'peeled' the metal (in strips) off the
potting and then just cut everything out from the back until I found the
three pins. As for is it worth fixing, when I've fixed something I know how
it's been done and who is to blame next time. Besides, £25 for a mains
filter is painful when the whole meter cost £20 via fleabay - it's one of
those Scottish things.

David
GM4HJQ



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

Re: [time-nuts] Cycling of Peltier junction (Jerome Peters)

[David]

 Might be worth a glance:

http://www.eevblog.com/2010/07/25/eevblog-101-hacking-your-own-peltier-lab-thermal-chamber/


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

Re: [time-nuts] Setting clocks 100 years ago

[David]

> Other Timeballs that I know are 

Another for the list, some of you will have visited Edinburgh which has 
run a time gun and ball since the 1860s. I'll spare you the usual links, 
the foot of this link shows the time gun correction maps that the 
Edinburgh time nut of the 1860s would would subscribe to.


http://www.edinphoto.org.uk/1_edin/1_edinburgh_history_-_time-gun.htm

Also linked via that page is a video showing the gun and ball working 
today :


http://www.youtube.com/watch?v=Anrgx2Cap3E&feature=player_embedded

Much more fun than GPS...




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

[time-nuts] JJY 40, Fukushima

[David]

I've not seen it mentioned but VLF time stations are on topic here. I 
saw that the  Mount Ootakadoya VLF (40kHz) transmitter in Fukushima 
prefecture is off air :


"Time Signal. 50kW. Transmission is stopped since 10h46 UT on March 12, 
2011 because of the evacuation of the area around the Fukushima Nuclear 
Power Station damaged by the March 11, 2011 earthquake and tsunami JJY-40."


(http://sidstation.loudet.org/stations-list-en.xhtml)

Although inland, the station is close to the Fukushima Daiichi power 
plant so it's going to be down for a while, best wishes to the folk who 
operate the transmitter.


http://www.tele.soumu.go.jp/e/sys/fees/purpose/other/index.htm

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

Re: [time-nuts] How accurate are cheap radio controlled clocks?

[David]

I've got one of the cheap radio-controlled clocks? I was listing to
radio 4 the other day and herd the time signal. The radio controlled
clock was about 3 seconds off. I was a bit surprised it was so far
off. I'm just wondering how accurate these things are.

David,

Be aware that if listening via digital radio (or worse, digital TV)
there is a delay in the transmission chain of up to several seconds
(DTV). I expect you know that already! Use the FM signal for best results.

I was using 198.00 kHz longwave here in the UK. Unless there's some digital
processing going on before the signal is AM modulated, this can't explain the
problem.


David,

I'd back what David Taylor says that I casually see my cheap Casio watch 
maintaining sync via the NPL Anthorn 60kHz signal within a second of BBC 
R4 LW pips although it appears we are in the same neighbourhood. I back 
the idea that the clock is not syncing for one of the aforementioned 
reasons (local noise, clock orientation etc). Bear in mind R4 LW at 
Droitwitch is not a single national service, there are two other 
transmitters that tend to be forgotten, the R4 198kHz signal Dave & I 
pick up may be the one transmitted from Westerglen rather than the NPL 
monitored signal from Droitwich (see 1). I've never seen anything 
authoritative regarding how the Scottish transmitters are controlled for 
carrier stability or modulation delay (audio or time code) nor anything 
about mutual interference zones. The NPL reports relate only to 
Droitwich carrier accuracy (2).


For the timenut, remember that R4 LW has a largely forgotten time code 
feature (3) which frees you from having to listen to the pips and John 
Humphrys, I wonder if anyone is monitoring this?


(1) http://en.wikipedia.org/wiki/Droitwich_transmitting_station
(2) 
http://www.npl.co.uk/science-technology/time-frequency/time/products-and-services/droitwich-bulletins

(3) http://downloads.bbc.co.uk/rd/pubs/reports/1984-19.pdf

Regards
David




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

[time-nuts] LightSquared again.

[David]

This might amuse,

"LightSquared promises to replace satellite push-to-talk kit"

http://www.theregister.co.uk/2011/07/27/lightsquared_ptt/

--


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

Re: [time-nuts] Xtal-like Colpitts Oscillator, time-nuts Digest, Vol 44, Issue 62

[David]

> Message: 2
> Date: Mon, 31 Mar 2008 21:20:43 +
> From: Jenny Lee <[EMAIL PROTECTED]>
> Subject: [time-nuts] Xtal-like Colpitts Oscillator
> To: 
> Message-ID: <[EMAIL PROTECTED]>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> 
> Hi Everyone,  I was hoping to get some words of wisdom on my 
> oscillator that only oscillates in simulation!  I have .

Are you sure it simulates? Transistor looks reverse biased, some odd looking
values, Cout too small, 10nF more probable, L2 too large, a real component
is probably well past self resonance at 34MHz, C7 too large. The direct
drive into a 50 ohm load may be ambitious, I'd have expected a buffer amp on
the oscillator output giving a higher load Z to your osc. Check the DC bias
without a resonator, check the system as a buffer without the resonator or
C1 fitted etc.

Hope this helps.

David




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

[time-nuts] 8. 74ac112 and 74ac164 sources and 200 Ohm resistors (time-nuts Digest, Vol 48, Issue 35)

[David]

An easy answer to :

> I'm also hunting 200 Ohm 0.25W 1206 case thick film 
> resistors.  I can buy a reel of 5000 at about USD34 from RS 
> Components, but don't really need quite
> as many as that!!!   300 ohm don't seem any easier :-(
> 
> Yes, I know these aren't in the standard resistor sequence.

Using standard E12 values:
220R in parallel with 2k2 is exactly 200R.
330R in parallel with 3k3 is exactly 300R.

Just stack the two parts on the single footprint, sadly I knew the answers
without calculating, need to get out more

David






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

Re: [time-nuts] NavSync CW12 and CW25

[David]

Ed,

I've been playing with a CW12, it basically appears to do what they say but
I will not confirm any numbers for the moment, it certainly compares to my
VLF derived 10MHz signals. I was looking to build a GPSDO and 10MHz from the
GPS Rx seemed a better starting point than 1PPS.

I'm only now near to completing part two of the exercise, phase locking a
10MHz double oven XO to the CW12 10MHz, the phase noise on the CW12 output
is rather significant and needs cleaning for most applications. The ssb
numbers I see from the CW12 (using an HP8560E) relative to the 10MHz carrier
are :

1kHz -80 dBc/Hz
10kHz -102 dBc/Hz
100kHz -109 dBc/Hz
1MHz -126 dBc/Hz

The signal is far from a pure line, close in there is a set of sidebands
based on harmonics of 132 with the fundamental at -22dBc, there are various
synthesis artefacts. This unit clearly needs filtering.

The PLL I've built to clean it up is essentially a simple 2nd/3rd order loop
with the phase comparison at 78kHz (sigs divided by 128), my model claims
the 3dB closed bandwidth will be 0.3 Hz and sideband suppression about 127dB
at 1kHz offset in principle. In reality I'll need to play with it to look at
the real world limitations of acquisition, loop BW, analogue offsets etc .

The OCXO I'm locking is a Temex part, a 'Doc1478-D" which seems to be from
their S110 series. It claims to manage -145dBc at 1kHz offset. There were on
ebay at low cost a while ago, everything else has largely been built from
scrap which has biased the design ever so slightly, the less it costs the
more amusing the project if you are not doing it for a customer.

The slight disappointment has been the lack of support information about the
CW12 on the web, when I spoke to them in March they said their site was
going to be updated by the end of that month, clearly they have dropped the
ball somewhere but the email support seems responsive. I think I've seen the
CW25 appear in a recent GPSDO from Quartzlock, have a look at :

http://www.quartzlock.com/cgi-bin/servepage.cgi?usr=61390&page=tech_DS_E8-X.
pdf

This appears to use a DDS/PLL to clean the reference clock rather than a
large and expensive OCXO.

Starting afresh I may have gone for the CW25 but I've got the CW12 so not
thought much more about it.

Regards
David Mackenzie (GM4HJQ)



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

Re: [time-nuts] Low temperature coefficient capacitors for DMTD

[David Forbes]

Polycarbonate film production ceased about 10 years ago.

Bruce



They're not quite dead yet...

http://www.polycarbonatecapacitors.com/

But I wouldn't use them unless forced to at gunpoint, since they are quite the 
boutique item these days.


I too have had good success with the PPS capacitors.


--David Forbes


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

Re: [time-nuts] [OT] Ikea Lamp

[David Martindale]

There are multiple versions, including wall-mount and one that clamps onto
the edge of an object like a bookshelf.  Here is the family:

http://www.ikea.com/us/en/search/?query=jansjo

They all probably have the same LED head.  If you don't need a long
gooseneck, the wall and clamp versions are the cheapest way to get the head
plus a short gooseneck.  They give a circle of light with a fairly sharp
cutoff at the edge of the circle.  Think of it as something that will fit
into many of the places where you would really like to have a fiber optic
light source, but at 1/5 the cost.

The little wall wart is a regulated constant-current supply (not constant
voltage), which ought to make the light output relatively constant despite
LED temperature changes and wire resistance changes.  However, I find that
the cheap inline switch has contacts that tend to get dirty or oxidize, and
the LED flickers until I flip the switch on and off a couple of times to
clean the contacts.  If you're going to modify it anyway, install a better
switch.

I have two of these.  One clamp-base is mounted on my computer desk, up
high, where it illuminates my keyboard without washing out the monitor.  The
other has the weighted desk base, and it's useful as a reading lamp as well
as illuminating things under the stereomicroscope, and looking inside
cluttered equipment chassis.

  Dave

On Fri, Jan 29, 2010 at 8:59 AM, Brooke Clarke  wrote:

> Hi Poul:
>
> Can the base be hung on a wall?
> http://www.ikea.com/us/en/catalog/products/10128734
>
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
>
>
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[time-nuts] Quasi-OT: The nixie watch is again available

[David Forbes]

Fellow time-nuts,

Please forgive the tangential and blatantly commercial subject 
matter. I remember that a few of you expressed interest in my nixie 
tube wristwatch when I last mentioned it.


I have finally gotten it back into production after a too-long hiatus 
brought on by obsolete parts.


http://www.nixiewatch.com/

And no, it doesn't have a rubidium oscillator. But you can adjust the 
crystal oscillator frequency (test point provided) and obsess over 
its inadequacies as a precision time source. And the Woz wears one.

--

--David Forbes, Tucson, AZ
http://www.cathodecorner.com/


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

Re: [time-nuts] Rb Oscillator - rather fundamental question

[David Forbes]

Matthew Smith wrote:

Quoth Poul-Henning Kamp at 2010-02-23 20:22...

In message <4b83a33c.1010...@smiffytech.com>, Matthew Smith writes:

Simple and rather fundamental question: does the common or garden 
rubidium oscillator constitute an atomic clock?

Yes.
...


Many thanks for the responses and ensuing discussion that has
considerably value-added to the yes/no nature of my original question ;-)

Now I know a lot more about primary/secondary standards than I did a
(9,192,631,770 Cs wobbles * 86400) ago.

I can now proceed with my unconventional calendar design (a cascade of
dekatrons) knowing that it will be driven by an atomic ticker.

BTW: does anyone know if a 0.55V p-t-p sine wave from an Rb source would
be enough to clock an Atmel AVR microcontroller?  The crystal/clock
input *is* an amplifier, but didn't know if I'd need to do anything to
the signal first, to get it closer to the 5V logic level.

Cheers

M



Matthew,

The signal you describe could be fed through a small-value capacitor (perhaps 
100 pF) right into the microcontroller. The amplifier must be internally biased, 
otherwise it wouldn't work with a crystal.


You will want to put a protection circuit on the input if you have an exposed 
coax connector leading to the outside world, in case of a static discharge to 
the center pin of the cable. A series resistor of several Kohm followed by the 
capacitor in series with the signal, plus a pair of 1N4148 diodes connected in 
reverse-bias to Gnd and Vcc from the input pin of the MCU, are usually sufficient.



--David Forbes

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

Re: [time-nuts] nubie querie

[David Forbes]

At 10:25 AM -0800 3/4/10, Brooke Clarke wrote:

Hi Tom:

In the last slide you show a sand timer.  Do you have accuracy data for it?



Wouldn't that depend on the consistency with which the human flips 
the hour glass? They don't flip themselves, you know.


--

--David Forbes, Tucson, AZ
http://www.cathodecorner.com/


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

Re: [time-nuts] nubie querie

[David Forbes]

Hal Murray wrote:

rich...@karlquist.com said:

I vaguely remember reading that pulsars have some fantastic stability
like 1E-20.  I don't remember how they established this. 


Do you remember how long ago you read that?  It might have been some 
handwaving back before they had good data.


For a while, the astronomers were seriously trying to take back the official 
clock from the physicists.  They didn't make it.  I think a lot of the 
interest started when somebody discovered a pulsar ticking at close to 1 KHz. 
 That was in 1982.


They have collected enough data to see things like star-quakes which are 
glitches in the rotation rate due to geologic type shifts similar to the 
recent discussion of 1.26 microseconds per day from the Chile quake.


They decay by gravitational radiation and speed up when accretion adds more 
momentum and energy.


That's what I remember from reading the literature on pulsars as well. They act 
a lot like quartz crystals, in fact, with frequency drift and frequency jumps.


In short, there is no macro-scale clock that will ever work as well as an atomic 
clock, since an atomic clock depends on the behavior of subatomic particles with 
a handful of state variables, whereas a macro-scale clock depends on the 
behavior of large and changing lumps of disparate matter with gazillions of 
state variables.


I realized as a teenager that the difficulty of predicting the future is 
geometrically (or so) proportional to the number of state variables. So the 
cesium clock is one of the few gadgets whose future behavior can be predicted to 
any reasonable extent.


--David Forbes

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

Re: [time-nuts] 5370A vs 5370B

[David Forbes]

At 4:10 PM + 3/10/10, Mark Sims wrote:
Yes,  I replace the standard HP fan with a MUCH quieter one.   I get 
mine from a local surplus shop.  It is made by AAVID.  it draws 120 
mA at 12V and I  run it off the 10V supply (which is somewhat over 
10V).


Before getting all whiny about overheating,  careful HP engineers 
putting that obnoxious hurricane in for a reason,  etc...  know that 
I put several thermocouples all over the guts of the machine and 
found no significant changes in cooling.   I have had modified 
machines running continuously for many years.



It's reasonable to assume that HP engineers put in twice as much fan 
as needed by 95% of their customers, to prevent problems with that 
last 5% that run the thing in an extreme environment. If the 
counter's spec sheet says it will run at 50C, then it's gotta be able 
to run for a couple years at 50C without failure. So your 25C office 
can use a much quieter fan.


Our telescope at 3500m altitude, on the other hand, needs all the fan 
noise it can get since the thin air is only 50% as effective at 
cooling as sea-level air is.

--

--David Forbes, Tucson, AZ
http://www.cathodecorner.com/


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

Re: [time-nuts] nubie querie

[David Forbes]

Hal Murray wrote:

This, and similar impressive accomplishments, has prompted some
lunchtime discussion at work (JPL).. One of us (N5BF) has been
contemplating what it would take to do an amateur EarthVenusEarth
(after some of his experiments doing EME with 5 watts).. 


Perhaps a better question is:  What is the bandwidth?

What sort of signal do I have to receive in order to claim contact?  Is one 
bit/blob of energy at the right time/frequency good enough, or do I have to 
demodulate the signal and extract a few bits of data?




Marconi claimed credit for the first transatlantic communication by sending the 
letter S in Morse code. That sounds like a fine standard - one byte of data. 
It's statistically significant.


With regard to the restoration and use of a derelict radio telescope for amateur 
radio, that's a fine example of amateurs putting themselves to a big task and 
succeeding. I work on radio telescopes, so I know how big a task that is.


--David Forbes

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

Re: [time-nuts] Frequency divider board PCBs

[David Smith]

David, 

Thank you for the information. Please put me down for one of the boards.

73,

Dave Smith W6TE
  - Original Message - 
  From: David C. Partridge<mailto:david.partri...@dsl.pipex.com> 
  To: 'Discussion of precise time and frequency 
measurement'<mailto:time-nuts@febo.com> 
  Sent: Tuesday, March 16, 2010 11:52 AM
  Subject: Re: [time-nuts] Frequency divider board PCBs



  
http://www.perdrix.co.uk/FrequencyDivider/Frequency%20Divider%202%20Schematic.pdf>>
  
http://www.perdrix.co.uk/FrequencyDivider/Frequency%20Divider%202.pdf>>

  Regards,
  David Partridge
  Email:david.partri...@perdrix.co.uk

  -Original Message-
  From: time-nuts-boun...@febo.com<mailto:time-nuts-boun...@febo.com> 
[mailto:time-nuts-boun...@febo.com] On
  Behalf Of David C. Partridge
  Sent: 16 March 2010 16:12
  To: david.partri...@perdrix.co.uk<mailto:david.partri...@perdrix.co.uk>; 
'Discussion of precise time and frequency
  measurement'
  Subject: Re: [time-nuts] Frequency divider board PCBs

  I now have statements of intent for 21 boards.  This will result in a unit
  price of about GBP20 plus shipping.

  If I can get the interest level up to close to 50 boards, the unit price
  comes down to about GBP14.50.

  Thanks to those who suggested other suppliers outside UK, but I'd prefer to
  deal with a local agent even if the actual fab plant is in Guangzhou.

  Cheers
  Dave
  -Original Message-
  From: time-nuts-boun...@febo.com<mailto:time-nuts-boun...@febo.com> 
[mailto:time-nuts-boun...@febo.com] On
  Behalf Of David C. Partridge
  Sent: 14 March 2010 11:42
  To: 'Discussion of precise time and frequency measurement'
  Subject: Re: [time-nuts] Frequency divider board PCBs

  I now have eight statements of intent - only a few more ...

  Cheers
  David Partridge

  -Original Message-
  From: time-nuts-boun...@febo.com<mailto:time-nuts-boun...@febo.com> 
[mailto:time-nuts-boun...@febo.com] On
  Behalf Of David C. Partridge
  Sent: 13 March 2010 10:01
  To: 'Discussion of precise time and frequency measurement';
  teksco...@yahoogroups.com<mailto:teksco...@yahoogroups.com>; 
hp_agilent_equipm...@yahoogroups.com<mailto:hp_agilent_equipm...@yahoogroups.com>;
  testequiptra...@yahoogroups.com<mailto:testequiptra...@yahoogroups.com>; 
tekscop...@yahoogroups.com<mailto:tekscop...@yahoogroups.com>
  Subject: [time-nuts] Frequency divider board PCBs

  > I'm considering getting another batch of PCBs made up for the 
  > frequency
  divider design I sold a number of the other year.



  ___
  time-nuts mailing list -- time-nuts@febo.com<mailto:time-nuts@febo.com> To 
unsubscribe, go to
  
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
  and follow the instructions there.


  ___
  time-nuts mailing list -- time-nuts@febo.com<mailto:time-nuts@febo.com> To 
unsubscribe, go to
  
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
  and follow the instructions there.


  ___
  time-nuts mailing list -- time-nuts@febo.com<mailto:time-nuts@febo.com>
  To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
  and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] OT - New Mexico travel and the VLA

[David Forbes]

Bill Hawkins wrote:

I'll be driving around NM the week of April 19th from Albuquerque to the
VLA... up to Los Alamos for the Bradbury museum...


Never mind the museums in Los Alamos, go to The Black Hole!

Ed Grothus died last year, but it's still the most amazing surplus store on the 
planet.


--David Forbes

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

Re: [time-nuts] What time is it anyway?

[David Forbes]

At 11:11 AM -0400 3/27/10, Bob Camp wrote:


I would bet that if you went deep enough into the details, that the 
Army at some point was less than enthusiastic about having to ask 
the Navy when ever they wanted to know what time it was.


My guess is that the Army just asked Western Union, who asked the Navy.

--

--David Forbes, Tucson, AZ
http://www.cathodecorner.com/


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

Re: [time-nuts] [OT] degausing

[David Martindale]

In the case of compasses, a balanced needle tends to tilt to align with the
vertical as well as horizontal component of the earth's magnetic field - so
it's level at the equator, north end low in the northern hemisphere, and
south end low in the southern hemisphere.  But you want the needle level so
it doesn't drag on the capsule and so the pivot works the way it was
designed.  So northern hemisphere compasses have excess weight on the south
side in order to give an approximately level needle despite the tilt in the
magnetic field in that area.

Recta makes compasses with magnet and pointer as two separate parts, linked
by a bearing whose axis goes east-west.  The magnet is free to tilt.  The
needle indicates the azimuth portion of the magnet position, but ignores any
tilt component and remains level in the capsule.  They call it a "global"
compass because a single version works everywhere (that a compass can be
used at all).

However, I don't see how the earth's tilted field prevents a CRT from being
used in both hemispheres.  I can see how it might need to be realigned,
since it uses permanent magnets on the yoke and their field will be
influenced by the earth's local field.  But a different model for the
southern hemisphere?

 Dave

On Thu, Apr 15, 2010 at 5:07 PM, wa1...@att.net  wrote:

> FWIW.A good high quality compass needs to be designed based on what
> region of the earth you plan to use it in. The Suunto ones I have are marked
> with a US region code.
>
> -Brian, WA1ZMS
>
>
> On Apr 15, 2010, at 7:58 PM, Kit Scally  wrote:
>
>  Craig,
>>
>> If memory serves me correctly, Philips "better quality" PAL colour TV's
>> in the late 70's to early 80's "inverted" the CRT for us in the Southern
>> Hemisphere.  The TV's were clearly marked as such on the packing box.
>>
>> For reasons unknown, Japanese-made colour TV's never seemed to have this
>> problem.  Even though I was working professionally with these beasts at
>> the time in a TV station, I never figured out why Jap TV's seemed immune
>> to this problem whilst those made by our Dutch friends were not.
>>
>> OOLLM I guess.
>>
>>
>> Kit
>> VK2LL
>> Sydney
>>
>>
>> Message: 4
>> Date: Thu, 15 Apr 2010 08:21:03 -0700
>> From: "Craig S McCartney" 
>> Subject: Re: [time-nuts] [OT] degausing
>> To: "Discussion of precise time and frequency measurement"
>>   
>> Message-ID:
>>
>> <9fedd04e51e8c045bc6fbcbc49346072381...@smbuserver.on-sitetraining.local
>>
>>>
>>>
>> Content-Type: text/plain;charset="us-ascii"
>>
>>
>> A bit off topic, but likely interesting to time-nuts:
>>
>>> snip

>>> So, we had a HDTV monitor that doubled as a earth hemisphere detector,
>> using magnetic flux differential.  Needless to say, we only used it in
>> northern hemisphere shows after that.
>>
>>
>> Craig McCartney
>> WA8DRZ
>>
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] The USCG really wants to bury Loran-C

[David Forbes]

Poul-Henning Kamp wrote:


http://news.bbc.co.uk/2/hi/americas/8653754.stm



At least they didn't hit the building with the tower!

I like how the BBC helpfully offers several more demolition videos at the end.

--David Forbes



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

[time-nuts] Info on Lucent RFG-TB?

[David Woodhead]

I recently picked up a Lucent RFG-RB. It seems to work but don't really need 
the 15MHz output. Does anyone have a schematic for this unit?

Thanks.

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

Re: [time-nuts] Digital tight PLL method

[David Martindale]

Hmm.  From here in Vancouver Canada, the name resolves to the same address,
pings fail, and the given URL gets me the web page.

Try using the top-level page address:
http://tf.nist.gov/phase/Properties/main.htm
(Looks like the whole set of pages is worth reading anyway).

 Dave

On Thu, May 27, 2010 at 7:44 AM, Steve Rooke  wrote:

> Well, I've tried it from a Windows 7 install here and still cannot get
> it up using Firefox or IE so it must be some sort of regional
> blocking. Windows troubleshooter under IE could not suggest an answer
> for this but there again that's hardly surprising.
>
> $ nslookup tf.nist.gov
> Server: 127.0.0.1
> Address:127.0.0.1#53
>
> Non-authoritative answer:
> tf.nist.gov canonical name = tf.boulder.nist.gov.
> tf.boulder.nist.gov canonical name = symp17.boulder.nist.gov.
> Name:   symp17.boulder.nist.gov
> Address: 132.163.4.169
>
> Seems to resolve fine but trying to ping it fails (still that is no
> indication of a problem).
>
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] FRS-C TTL / sine outboard filter question

[David Smith]

Leigh, I have the same FRS-C TTL unit. I do not have a manual.

Would you be so kind as to send the conversation info to me?

Thanks,

Dave W6TE
  - Original Message - 
  From: Leigh L. Klotz, Jr WA5ZNU 
  To: time nuts 
  Sent: Tuesday, June 22, 2010 9:54 PM
  Subject: [time-nuts] FRS-C TTL / sine outboard filter question


  At the local flea market, I picked up what appears to be an Efratom 
  FRS-C.  It is marked "TTL" internally.  It has the passive connector 
  board, but not the active board with the 15 MHz synthesizer on it.

  Mine is marked "TTL" internally.  The service manual has a chart showing 
  the differences between the sine and TTL options, and I converted it to 
  the sine version by changing a jumper to a resistor and populating an LC 
  filter with 10uH and 100pF (~5 MHz).  I also terminated the RF 
  connection on the connector board with a 47 ohm resistor to ground.

  The output now doesn't have the tremendous overshoot it used to have, 
  but it's also not very sinusoidal.  That's not surprising given the 
  simplicity of the on-board filter.

  Instead of a multi-stage LC filter, I wondered about a crystal ladder 
  filter: since the output frequency is fixed, the high Q and low cost of 
  the crystal filter might be an advantage, but I wasn't sure about how 
  effective xtal ladder filters are at suppressing harmonics, as each 
  individual crystals would have odd overtone responses, so it might not 
  be a good plan.

  Does anyone have practical experience with a filter topology for 
  cleaning up the output of the FRS-C at 10 MHz?

  Leigh.

  P.S. Just so that I can be topical, note that the FRS-C has a C-field 
  adjustment 0-5V input, so I could use it as the reference oscillator for 
  a TPLL.


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

Re: [time-nuts] Handy iPhone app

[David Martindale]

I have an iPod Touch.  It's an iPhone without the cellular radio, the
camera, the GPS, or the compass, but it runs most of the same applications.
Emerald Time works fine on it.

As far as I can tell, Apple refuses to acknowledge any timing precision
finer than minutes in their user interface.  It displays the time on the top
of most windows, but only to 1 minute resolution.  You can manually set the
date and time, but only to within 1 minute precision.  The date and time
setting widget doesn't display seconds, and doesn't provide a way to reset
seconds to zero, or to temporarily stop the clock until the seconds are
synchronized with the correct time.

The Touch clearly doesn't get time from a cellular base station.  It doesn't
seem to get its time set from the computer it syncs to either (at least not
from a Windows PC).  My PC clock is set pretty accurately by a program
called "Nixie Clock" (it agrees with Emerald Time within 200 ms), while the
time on the Touch is 145 seconds off.  Doing a sync with the PC does *not*
correct the time at all.

So I guess the only choice available to the Touch owner is manual time
setting.  By looking at when the minutes roll over, or running Emerald time
and reading the error, you can get within 30 seconds of the correct time,
and that's all.  The Touch internal clock isn't terribly accurate either.
Someday I should measure it to see how bad it is, but a quartz watch is
better.

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

Re: [time-nuts] surface mount (was PICTIC II Parts from Mouser)

[David Martindale]

You'll probably also find that your fine motor control improves a bunch when
you can actually *see* what you are doing in 3D.  I got a stereo microscope
a year or two ago, and I'm amazed at how finely I can control the tip of a
pair of tweezers or a knife point or soldering iron under the microscope.
It works much better than trying to do the same thing with a one-eyed
magnifier like a loupe, partly because a microscope gives you more working
distance, but mostly because of the full 3D view of what you're doing.

My first stereo microscope was a surplus AO 40 that cost $100, so being able
to see what you're doing doesn't have to be expensive.

 Dave

On Tue, Jul 20, 2010 at 10:51 AM, Chuck Harris  wrote:

> Stanley,
>
> Your brain will do an excellent job of translating your finger
> motion to the micro motions necessary to move surface mount parts
> around with tweezers.  Barring disease, the usual solution to finger
> jitter is to keep tweezers pressure light, and lay off the coffee.
>
> Even if you do jitter a bit, there are many tricks you can use to
> keep it to a minimum.  I use the little finger on my tweezers hand
> as a balance point for my hand.  Just the act of having it touch the
> stage, or board removes all of the jitter.
>
>
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] A different timenuts interest

[David Martindale]

On Wed, Jul 21, 2010 at 7:57 PM, J. Forster  wrote:

> > I remember one someplace in London too.
>
> Science Museum in South Kensington, I'd expect, but I've not been there
> 20+ years.
>
>
Yes, they have one in one of their open multi-storey stairwells.  If I
remember correctly, the energy input is provided by lifting and lowering the
pivot point slightly in sync with the swing, rather than anything done at
the bob end.

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

Re: [time-nuts] NPR Story I heard this morning

[David McGaw]

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

Re: [time-nuts] NPR Story I heard this morning

[David McGaw]

The highest accessible peak in the Adirondacks I think would be 
Whiteface at 4,867 ft, though that would be by ski lift and not all the 
way to the top.  The highest point accessible by car in the Northeast 
would be Mt. Washington here in New Hampshire at 6288 ft.  Hmm...


David


On 11/3/14 1:02 PM, Hal Murray wrote:

x...@darksmile.net  said:

I was planning a similar trip from Astoria Queens, NYC which is sea level,
to Adirondack Mountains, upstate New York.

You will need clocks that are better than Tom's.  :)

He parked at 5,000 feet.  Do any roads go that high in the Adirondacks?  How
high can you park?

What's the efficiency of the generator in a parked car compared to a portable
generator?  What's the right unit?  kilo-watt-hours per gallon?  How does a
normal car compare to a hybrid?





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

Re: [time-nuts] DIP Is Dead R.I.P

[David McGaw]

As long as the chip in question is still available in surface mount, one 
can use a SM to DIP adapter.  I use these all the time to evaluate and 
prototype with SM chips.  It would be expensive to rechip a whole unit, 
but onesies in case of a failure is OK.


David


On 11/9/14 10:36 PM, Bob Camp wrote:

Hi

There is one thing to consider:

At the point that the monthly rent on the storage spaces equals Y

— and —

As you add more spares it goes to 2 x Y

— and —

There 12 months in a year

— and —

This *will* go on for years

How much is a brand new bench full of gear?

How much is a bench full of stuff you use on a regular basis?

H……

Ok, here’s my numbers:

Storage is $500 a month right now. It’s full.

Probably 80% of what is over there has been there or someplace just like it for > 
10 years. ( = I’ve run that sort of bill for > 10 years)

Maybe 50% of what is over there, is > 20 years. ( = I’ve run ~2/3 that bill for 
a lot longer)

Ok, so let’s use 10 years for a start.

That’s 6K a year times 10 years…. $60K ….

Ok but that’s not all. I’ve moved the stuff twice on inter-state moves. I also 
*paid* for it with *cash* that I no longer have. That cash could have been 
earning interest for the last 10 or more years. The same cash in the bank 
applies to the rent money. Then there’s the time it will take to troubleshoot / 
cal / revitalize each of the gizmos. It does not just take parts. I think it’s 
over $100K and close to $200K without a lot of thought going into it. That’s a 
lot of test gear if you buy the cheap PC connected modern stuff.

H ….. how may more spares?

Ok, so how many KS-24361’s was that ???

Bob

(anyone who relays *any* of those numbers to my wife will be shot …)



On Nov 8, 2014, at 7:47 PM, Perry Sandeen via time-nuts  
wrote:

List,

Wrote: The days of DIP parts are drawing to a close.

I was shocked, absolutely shocked, really, when I looked at
the latest Mouser catalog about the lack of PDIP I.C.’s.

That said, we are faced with a dilemma.

In all my HP test equipment I probably have 500 or more PDip
IC’s, so what to do to keep the equipment running properly?

My first two thoughts are to re-cap all the power supplies
and attempt to have greater cooling, especially in the notoriously hot 5370B
units. For them I've given thought to using external switching regulator
supplies or removing the heat sink and making it a separate module or external
dropping resistors.

Another choice maybe is to replace some of the original 74
series with LPS or similar later types to reduce internal instrument heat.

It may be time to get a number of *running spares* from
reputable Ebay sellers.

Perhaps all of the above in different proportions. I have
far, far too much money in HP test equipment just to sit and watch my units
fail one by one.

Regards,

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

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


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