Re: [time-nuts] Robert G8RPI -- Odetics 325 PSU

[Robert Atkinson]

Hi Glenn,
  I agree 100% having repaired SMPSU's since the late 70's, However this 
particular unit is multi output, multi input and VERY densely packed. It would 
not be worth replascing all the caps.because you would have to totally 
dismantle the PSU to do it.
   
  Robert G8RPI.
  

Glenn Little WB4UIV <[EMAIL PROTECTED]> wrote:
  Roy and the group

SMPS have a very classic failure mode. As the design is finalized by 
a bean counter, and/or the person that designed the SMPS was not 
qualified to do so, we have capacitors pushed beyond what they were 
designed for. If you are lucky, the electrolytic capacitors are 105 
degrees C. If not they are 85 degrees C. In all probability, the 
capacitors are not rated for the service that they are being used .

To fix the supply replace all of the electrolytics with pulse rated, 
105 degree C parts. The SMPS uses high frequency for the energy 
transformation. The designer had to use fast diodes, but, because the 
cheaper capacitors will continue to, somewhat, operate for the period 
of the warranty, the cheaper capacitors are used.

Use the largest capacitor that will fit into the available space. A 
higher voltage capacitor will work fine. If you can measure the 
capacitor ESR, you will find that the ESR has climbed to a higher 
than acceptable level on the capacitors that are causing the problem.

If you check the new capacitors before you install them, you will 
probably find that they are just above the lower tolerance value. If 
the next higher value will fit, use it.

I replace failed electrolytic capacitors almost daily. I am the chief 
engineer at a TV station and see more problems with capacitors than 
anything else. Our equipment is highly abused by being left on 24/7.

Almost all SMPS problem that I have seen are capacitors. Many 
"technicians" cannot fix a SMPS as they cannot find a bad 
semiconductor and the capacitors will check close to the correct 
value with acceptable leakage. They cannot check the parameter, ESR, 
that is causing the problem.

Hope this helps.

73
Glenn
WB4UIV

At 02:04 PM 4/19/2008, you wrote:
>Hi Roy,
> I've looked at two of these PSU's that had failed and was unable 
> to repair either of them. (I'm a professional electronics engineer 
> and can fix most things) There were no obvious faults like leaking 
> capacitors or burnt up components. The topology of the 
> auto-switching between 28V DC and 115/230V AC is not obvious and 
> the PCB is very densely packed making it very hard to trace the 
> circuit or make measurements. The high voltage on the PCB makes it 
> hazardous to work on. I gave up and replaced them with a standard 
> mains input multi-output unit. I don't recall the voltages and 
> ratings (they were marked on the unit), but if you let me know what 
> they are I'll see if I have a suitable unit. email robert8rpi (at) yahoo.co.uk
>
> Regards,
>
> Robert G8RPI.
>
>Roy Phillips 
wrote:
> Hi Robert
>
>You may remember that we exchange info on the 325 SatSyc Receivers. 
>I remember that you said that the PSU was a weak point with the 
>system - you were right on , after finding a suitable antenna and 
>replacing the lithium battery in the Rx., it was running sweetly for 
>about 18 days, but yesterday it failed. The power fuse (AC input) 
>had blown, and following a quick inspection within the PSU - nothing 
>appears to be burnt out or visibly damaged. What was your experiece 
>of fault finding with this item. Before I proceed further, do you 
>have the schematic for the PSU - this is not in the normal manual - 
>its an AC to DC, and a DC to DC unit. Its a quality item, Model 
>VF100 -494-10/CX ,made by "Converter Concepts", and should be worth 
>restoration. Any ideas ?
>
>cheers
>
>Roy UP
>
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>
>
>-
> Yahoo! for Good helps you make a difference
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Re: [time-nuts] Robert G8RPI -- Odetics 325 PSU

[Roy Phillips]

Glenn
Thanks for the very incisive "inside" perspective on SMPS - I would 
certainly agree that the average SMPS unit is very much a 'budget' design, 
but this one is rather well made, and provides a DC 'back up' facility, so 
it would be nice to restore it. There is also the very real danger of 
contact with the input stages , with the UK AC supply power at 240 volts, 
this could be quite lethal. This particular item has both AC (90-240V) and 
DC (20-60V) input switching stages, making it even more difficult to 
unravel. I'm sure most engineers would rather bin a faulty unit than repair 
it. Long live the 'good old' linear supply, perhaps I should build one, as 
there is certainly space within the equipment.
Roy
- 
From: "Glenn Little WB4UIV" <[EMAIL PROTECTED]>
To: 
Sent: Sunday, April 20, 2008 5:04 AM
Subject: Re: [time-nuts] Robert G8RPI -- Odetics 325 PSU


> Roy and the group
>
> SMPS have a very classic failure mode. As the design is finalized by
> a bean counter, and/or the person that designed the SMPS was not
> qualified to do so, we have capacitors pushed beyond what they were
> designed for. If you are lucky, the electrolytic capacitors are 105
> degrees C. If not they are 85 degrees C. In all probability, the
> capacitors are not rated for the service that they are being used .
>
> To fix the supply replace all of the electrolytics with pulse rated,
> 105 degree C parts. The SMPS uses high frequency for the energy
> transformation. The designer had to use fast diodes, but, because the
> cheaper capacitors will continue to, somewhat, operate for the period
> of the warranty, the cheaper capacitors are used.
>
> Use the largest capacitor that will fit into the available space. A
> higher voltage capacitor will work fine. If you can measure the
> capacitor ESR, you will find that the ESR has climbed to a higher
> than acceptable level on the capacitors that are causing the problem.
>
> If you check the new capacitors before you install them, you will
> probably find that they are just above the lower tolerance value. If
> the next higher value will fit, use it.
>
> I replace failed electrolytic capacitors almost daily. I am the chief
> engineer at a TV station and see more problems with capacitors than
> anything else. Our equipment is highly abused by being left on 24/7.
>
> Almost all SMPS problem that I have seen are capacitors. Many
> "technicians" cannot fix a SMPS as they cannot find a bad
> semiconductor and the capacitors will check close to the correct
> value with acceptable leakage. They cannot check the parameter, ESR,
> that is causing the problem.
>
> Hope this helps.
>
> 73
> Glenn
> WB4UIV
>
> At 02:04 PM 4/19/2008, you wrote:
>>Hi Roy,
>>   I've looked at two of these PSU's that had failed and was unable
>> to repair either of them. (I'm a professional electronics engineer
>> and can fix most things) There were no obvious faults like leaking
>> capacitors or burnt up components. The topology of the
>> auto-switching between 28V DC  and 115/230V AC is not obvious and
>> the PCB is very densely packed making it very hard to trace the
>> circuit or make measurements. The high voltage on the PCB makes it
>> hazardous to work on. I gave up and replaced them with a standard
>> mains input multi-output unit. I don't recall the voltages and
>> ratings (they were marked on the unit), but if you let me know what
>> they are I'll see if I have a suitable unit. email robert8rpi (at) 
>> yahoo.co.uk
>>
>>   Regards,
>>
>>   Robert G8RPI.
>>
>>Roy Phillips <[EMAIL PROTECTED]> wrote:
>>   Hi Robert
>>
>>You may remember that we exchange info on the 325 SatSyc Receivers.
>>I remember that you said that the PSU was a weak point with the
>>system - you were right on , after finding a suitable antenna and
>>replacing the lithium battery in the Rx., it was running sweetly for
>>about 18 days, but yesterday it failed. The power fuse (AC input)
>>had blown, and following a quick inspection within the PSU - nothing
>>appears to be burnt out or visibly damaged. What was your experiece
>>of fault finding with this item. Before I proceed further, do you
>>have the schematic for the PSU - this is not in the normal manual -
>>its an AC to DC, and a DC to DC unit. Its a quality item, Model
>>VF100 -494-10/CX ,made by "Converter Concepts", and should be worth
>>restoration. Any ideas ?
>>
>>cheers
>>
>>Roy UP
>>
>>___
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>>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>>
>>
>>
>>-
>>  Yahoo! for Good helps you make a difference
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>
>
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Re: [time-nuts] Frequency reference

[David C. Partridge]

Paging Tom van Baak.   I replied to your offline email, but that email and
the follow up sent with delivery receipt requested seem not to have arrived.

Do you or your ISP have a (silent) spam trapper that is putting my mails in
the bin without sending a delivery receipt?

Thanks
Dave
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of David C. Partridge
Sent: 17 April 2008 16:00
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Frequency reference

Give me time (accurate time of course) - we all have to start with one
standard.

Seriously though, if I've got that sort of budget, can I do better than a
thunderbolt?

Thanks
Dave


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Re: [time-nuts] Frequency reference

[Chuck Harris]

Most experienced people refuse to send delivery receipts.  To send them would
validate their address to all of the spammers that blindly spam every email
address they can scrape off of the internet.

-Chuck Harris

David C. Partridge wrote:
> Paging Tom van Baak.   I replied to your offline email, but that email and
> the follow up sent with delivery receipt requested seem not to have arrived.
> 
> Do you or your ISP have a (silent) spam trapper that is putting my mails in
> the bin without sending a delivery receipt?
> 
> Thanks
> Dave
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of David C. Partridge
> Sent: 17 April 2008 16:00
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] Frequency reference
> 
> Give me time (accurate time of course) - we all have to start with one
> standard.
> 
> Seriously though, if I've got that sort of budget, can I do better than a
> thunderbolt?
> 
> Thanks
> Dave
> 
> 
> ___
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> 

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Re: [time-nuts] Frequency reference

[Attila Kinali]

On Thu, 17 Apr 2008 08:47:48 -0700 (GMT-07:00)
"Richard W. Solomon" <[EMAIL PROTECTED]> wrote:

> You can build a very good GPSDO for about $100 in parts.

Stupid question, but if one builds his on frequency
reference, how can you be sure it's acurate and precise?

Or to but it in other words: how do you measure self build
devices?

Attila Kinali

-- 
The true CS students do not need to know how to program.
They learn how to abstract the process of programming to
the point of making programmers obsolete.
-- Jabber in #holo

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Re: [time-nuts] Frequency reference

[Jim Lux]

Quoting Attila Kinali <[EMAIL PROTECTED]>, on Sun 20 Apr 2008 05:50:21 AM PDT:

> On Thu, 17 Apr 2008 08:47:48 -0700 (GMT-07:00)
> "Richard W. Solomon" <[EMAIL PROTECTED]> wrote:
>
>> You can build a very good GPSDO for about $100 in parts.
>
> Stupid question, but if one builds his on frequency
> reference, how can you be sure it's acurate and precise?


not a stupid question at all..PhD dissertations have been written  
about answering it.

>
> Or to but it in other words: how do you measure self build
> devices?

Build 2 or 3, and compare them against each other. (can't have too  
many frequency and time standards...)


or, take it to somewhere that has a higher quality standard and compare

or, just trust that the performance is inherent in the design, and if  
it works at all, it's good enough. Typically, if you are building a  
copy of a known good design, this is a good start.


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Re: [time-nuts] Frequency reference

[Didier Juges]

> Attila Kinali <[EMAIL PROTECTED]>, on Sun 20 Apr 2008 
> 05:50:21 AM PDT:
> 
> > On Thu, 17 Apr 2008 08:47:48 -0700 (GMT-07:00) "Richard W. Solomon" 
> > <[EMAIL PROTECTED]> wrote:
> >
> >> You can build a very good GPSDO for about $100 in parts.
> >
> > Stupid question, but if one builds his on frequency 
> reference, how can 
> > you be sure it's acurate and precise?
> 

If you track the correction voltage of a GPSDO over time and compare it to
that of a comparable GPSDO (there is plenty of data to compare to on Tom Van
Baak's web site leapsecond.com), you gain some confidence that your unit is
performing comparably. Since GPS is referenced to UTC (maybe not from a
metrology standpoint, but good enough for most other applications), it is a
standard by and of itself.

For very basic frequency standard, other reference frequency signals are
available over the air (WWV, DCF, Loran and other), but of those, only Loran
would qualify as a time standard, the others are at best frequency standards
because of the variation in propagation that are difficult or impossible to
compensate for HF/LF signals.

Now, this is time-nuts, so monitoring this mailing list for a while will
show you that there is much more than meet the eyes.

Didier

Internal Virus Database is out-of-date.
Checked by AVG. 
Version: 7.5.519 / Virus Database: 269.22.5/1358 - Release Date: 4/3/2008
6:36 PM
 


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Re: [time-nuts] Frequency reference

[Richard W. Solomon]

You can never be absolutely sure of your frequency, no matter how
you measure it. That is the Holy Grail that the folks on this list
pursue but can never attain.

Since the GPSDO I built (actually two of them) uses the GPS satellite
system for frequency control, I feel it's as good as you can get in
this price range.

One experiment I tried to confirm that they actually worked was:
One GPSDO 10 MHz output was used as the external reference for an
EIP 535 Counter. The second GPSDO was used to lock up a 1 GHz PLO
brick set to 970.000 MHz. Reading the output of the 970 MHz brick
on the EIP counter produced a reading of 970 000 000. The last zero
did fluctuate +/- 1 digit randomly.

If I can resolve 1 Hz at 970 MHz, that's good enough for me and my
uses for it.

Can anyone do better for $100 ??

73, Dick, W1KSZ 

-Original Message-
>From: Attila Kinali <[EMAIL PROTECTED]>
>Sent: Apr 20, 2008 5:50 AM
>To: "Richard W. Solomon" <[EMAIL PROTECTED]>, Discussion of precise time and 
>frequency measurement 
>Cc: Discussion of precise time and frequency measurement 
>Subject: Re: [time-nuts] Frequency reference
>
>On Thu, 17 Apr 2008 08:47:48 -0700 (GMT-07:00)
>"Richard W. Solomon" <[EMAIL PROTECTED]> wrote:
>
>> You can build a very good GPSDO for about $100 in parts.
>
>Stupid question, but if one builds his on frequency
>reference, how can you be sure it's acurate and precise?
>
>Or to but it in other words: how do you measure self build
>devices?
>
>   Attila Kinali
>
>-- 
>The true CS students do not need to know how to program.
>They learn how to abstract the process of programming to
>the point of making programmers obsolete.
>   -- Jabber in #holo


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[time-nuts] Y2K again: Tuesday 03:14:07 GMT, January 19, 2038

[Brooke Clarke]

Hi:

This is the rollover date for "C" language date functions that count the 
seconds since 00:00:00 1 Jan 1970 with a signed 32 bit integer.

One second after after 03:14:07 GMT, January 19, 2038 is in 1901.

-- 
Have Fun,

Brooke Clarke
http://www.prc68.com/P/Prod.html  Products I make and sell
http://www.prc68.com/Alpha.shtml  All my web pages listed based on html name
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam

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Re: [time-nuts] Y2K again: Tuesday 03:14:07 GMT, January 19, 2038

[Poul-Henning Kamp]

In message <[EMAIL PROTECTED]>, Brooke Clarke writes:
>Hi:
>
>This is the rollover date for "C" language date functions that count the 
>seconds since 00:00:00 1 Jan 1970 with a signed 32 bit integer.
>
>One second after after 03:14:07 GMT, January 19, 2038 is in 1901.

I think you can take it as read that all relevant OS's will have
a 64bit time_t before then.

How many applications there are, which assume sizeof(time_t) == 4 is
anyones guess.

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

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Re: [time-nuts] Y2K again: Tuesday 03:14:07 GMT, January 19, 2038

[Brooke Clarke]

Hi:

I should have mentioned the failures have just started.  If you subtract 30 
years from the subject date you get:  03:14:07 GMT, January 19, 2008
Financial institutions that do 30 year mortgage calculations are the ones who 
were bitten.

Have Fun,

Brooke Clarke
http://www.prc68.com/P/Prod.html  Products I make and sell
http://www.prc68.com/Alpha.shtml  All my web pages listed based on html name
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam


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[time-nuts] Match Stick Clock

[Neon John]

One of the coolest art clocks I've seen in awhile

http://www.christiaanpostma.nl/

Flash animation of it working here:

http://technabob.com/blog/2008/04/19/word-clock-slowly-reveals-the-time-with-text/

John

--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Ever stop to think, and forget to start again?


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Re: [time-nuts] Frequency reference

[Attila Kinali]

On Sun, 20 Apr 2008 09:25:37 -0700
Jim Lux <[EMAIL PROTECTED]> wrote:

> > Stupid question, but if one builds his on frequency
> > reference, how can you be sure it's acurate and precise?
>
> not a stupid question at all..PhD dissertations have been written  
> about answering it.

If there are dissertations written on this, are there any
good ones to read?
 
> > Or to but it in other words: how do you measure self build
> > devices?
> 
> Build 2 or 3, and compare them against each other. (can't have too  
> many frequency and time standards...)

Well.. then you have to build multiple frequency sources
that exhibit different physical behaviour, otherwise
slight changes in the enviroment that degrate your
precision will go unnoticed (ie, if all sources have
the same temperature coefficient then temperature
changes will affect all of them the same way making
you unable to measure this effect)
 
> or, take it to somewhere that has a higher quality standard and compare

Which is quite difficult if you don't have access to a physics
lab which you can use for a few days to weeks.
 
> or, just trust that the performance is inherent in the design, and if  
> it works at all, it's good enough. Typically, if you are building a  
> copy of a known good design, this is a good start.

I'm an engineer, i don't trust anything i cannot measure,
because i know that errors and mistakes are inherent in any design :-)

Attila Kinali

-- 
The true CS students do not need to know how to program.
They learn how to abstract the process of programming to
the point of making programmers obsolete.
-- Jabber in #holo

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Re: [time-nuts] Frequency reference

[Attila Kinali]

On Sun, 20 Apr 2008 11:28:51 -0700 (GMT-07:00)
"Richard W. Solomon" <[EMAIL PROTECTED]> wrote:

> One experiment I tried to confirm that they actually worked was:
> One GPSDO 10 MHz output was used as the external reference for an
> EIP 535 Counter. The second GPSDO was used to lock up a 1 GHz PLO
> brick set to 970.000 MHz. Reading the output of the 970 MHz brick
> on the EIP counter produced a reading of 970 000 000. The last zero
> did fluctuate +/- 1 digit randomly.

How did you keep the phase noise of the 10MHz reference
for the 970MHz signal low?

Attila Kinali

-- 
The true CS students do not need to know how to program.
They learn how to abstract the process of programming to
the point of making programmers obsolete.
-- Jabber in #holo

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Re: [time-nuts] Match Stick Clock

[Robert Lutwak]

Must be a drag to set.

-RL

---
Robert Lutwak
Symmetricom - Technology Realization Center
[EMAIL PROTECTED](Business)
[EMAIL PROTECTED]   (Personal)
(978) 232-1461  (Desk)
(339) 927-7896  (Mobile)
(978) 927-4099  (Facsimile)

- Original Message - 
From: "Neon John" <[EMAIL PROTECTED]>
To: 
Sent: Sunday, April 20, 2008 7:09 PM
Subject: [time-nuts] Match Stick Clock


> One of the coolest art clocks I've seen in awhile
>
> http://www.christiaanpostma.nl/
>
> Flash animation of it working here:
>
> http://technabob.com/blog/2008/04/19/word-clock-slowly-reveals-the-time-with-text/
>
> John
>
> --
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> http://www.johndearmond.com <-- best little blog on the net!
> Tellico Plains, Occupied TN
> Ever stop to think, and forget to start again?
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] Y2K again: Tuesday 03:14:07 GMT, January 19, 2038

[M. Warner Losh]

In message: <[EMAIL PROTECTED]>
Brooke Clarke <[EMAIL PROTECTED]> writes:
: I should have mentioned the failures have just started.  If you subtract 30 
: years from the subject date you get:  03:14:07 GMT, January 19, 2008
: Financial institutions that do 30 year mortgage calculations are the ones who 
: were bitten.

They are the ones that were bitten by y2k bug in 1970 and use sensible
data types instead.

Warner

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Re: [time-nuts] Frequency reference

[Richard W. Solomon]

I didn't worry about it. As the old Philosopher once said:
..."It will be what it will be"... .

73, Dick, W1KSZ

-Original Message-
>From: Attila Kinali <[EMAIL PROTECTED]>
>Sent: Apr 20, 2008 4:25 PM
>To: "Richard W. Solomon" <[EMAIL PROTECTED]>
>Cc: Discussion of precise time and frequency measurement 
>Subject: Re: [time-nuts] Frequency reference
>
>On Sun, 20 Apr 2008 11:28:51 -0700 (GMT-07:00)
>"Richard W. Solomon" <[EMAIL PROTECTED]> wrote:
>
>> One experiment I tried to confirm that they actually worked was:
>> One GPSDO 10 MHz output was used as the external reference for an
>> EIP 535 Counter. The second GPSDO was used to lock up a 1 GHz PLO
>> brick set to 970.000 MHz. Reading the output of the 970 MHz brick
>> on the EIP counter produced a reading of 970 000 000. The last zero
>> did fluctuate +/- 1 digit randomly.
>
>How did you keep the phase noise of the 10MHz reference
>for the 970MHz signal low?
>
>   Attila Kinali
>
>-- 
>The true CS students do not need to know how to program.
>They learn how to abstract the process of programming to
>the point of making programmers obsolete.
>   -- Jabber in #holo


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Re: [time-nuts] Y2K again: Tuesday 03:14:07 GMT, January 19, 2038

[Matthew Smith]

Quoth Brooke Clarke at 2008-04-21 04:59...
> This is the rollover date for "C" language date functions that count the 
> seconds since 00:00:00 1 Jan 1970 with a signed 32 bit integer.
> 
> One second after after 03:14:07 GMT, January 19, 2038 is in 1901.

This has been known about for some time - there is even a reference to 
it in the book 'Standard C Date/Time Library' by Lance Latham, published 
some 10 years ago (preparing for Y2K).  See section 1.8.5, 'Other 
Flavors of Doomsday'.  I would add that this is actually quite an 
interesting book in some of the background that it gives on various 
temporal orders.

For most of us, the Unix date problem will be a non-issue as we will 
either a) be retired or b) have passed away by then, making it an SEP 
(Someone Else's Problem) ;-)

On the subject of books (not meaning to hijack your thread, Brooke,) I'm 
about two-thirds of the way through 'History of the Hour - Clocks and 
Modern Temporal Orders' by Gerhard Dohrn-van Rossum.  Despite the rather 
dry-sounding title, I am finding this very engaging reading and would 
recommend it most wholeheartedly to my fellow temporophiles.

Cheers

M


-- 
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy

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Re: [time-nuts] Frequency reference

[Alan Melia]

It does not matter how many references you build you will never know how
good they are. There can only one judgement "goodness", and this is
comparison with the national standard. You reference may even be "better"
that a national standard but must be judged against the national standard.
Most countries provided a certification scheme for your reference but you
will pay a lot of money for that, else you use one of the distributed
national standards and then you must know the degradation in the
distribution system which is normally made available. There are several NIST
(NPL in the UK) monographs I believesurely that is the place to start.

Alan G3NYK

- Original Message -
From: "Attila Kinali" <[EMAIL PROTECTED]>
To: "Jim Lux" <[EMAIL PROTECTED]>
Cc: "Discussion of precise time and frequency measurement"

Sent: Monday, April 21, 2008 12:23 AM
Subject: Re: [time-nuts] Frequency reference


> On Sun, 20 Apr 2008 09:25:37 -0700
> Jim Lux <[EMAIL PROTECTED]> wrote:
>
> > > Stupid question, but if one builds his on frequency
> > > reference, how can you be sure it's acurate and precise?
> >
> > not a stupid question at all..PhD dissertations have been written
> > about answering it.
>
> If there are dissertations written on this, are there any
> good ones to read?
>
> > > Or to but it in other words: how do you measure self build
> > > devices?
> >
> > Build 2 or 3, and compare them against each other. (can't have too
> > many frequency and time standards...)
>
> Well.. then you have to build multiple frequency sources
> that exhibit different physical behaviour, otherwise
> slight changes in the enviroment that degrate your
> precision will go unnoticed (ie, if all sources have
> the same temperature coefficient then temperature
> changes will affect all of them the same way making
> you unable to measure this effect)
>
> > or, take it to somewhere that has a higher quality standard and compare
>
> Which is quite difficult if you don't have access to a physics
> lab which you can use for a few days to weeks.
>
> > or, just trust that the performance is inherent in the design, and if
> > it works at all, it's good enough. Typically, if you are building a
> > copy of a known good design, this is a good start.
>
> I'm an engineer, i don't trust anything i cannot measure,
> because i know that errors and mistakes are inherent in any design :-)
>
> Attila Kinali
>
> --
> The true CS students do not need to know how to program.
> They learn how to abstract the process of programming to
> the point of making programmers obsolete.
> -- Jabber in #holo
>
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[time-nuts] Ovenaire 10 MHz OSC 49-69 PIN OUT

[jshank]

Hi,
I have an Ovenaire 10 MHz OSC 49-69 ser.no. 20823-3 which I am in need of a 
pin-out and or any  other information.
Thanks,
Jeff 
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Re: [time-nuts] using Fury GPSDO with Rb

[SAIDJACK]

Hello Ulrich,
 
This is so true. See Tom's phase noise tests of a  Russian Rubidium prototype 
disciplined by a Fury GPSDO. Lot's of times  there is not much space to put a 
good OCXO inside the Rb's case.
 
BTW: using the Fury's 1PPS input, that unit can be used as a cleanup  loop 
for dirty Rb's that have 1PPS outputs.
 
_http://www.leapsecond.com/pages/fury/phase.htm_ 
(http://www.leapsecond.com/pages/fury/phase.htm) 
 
I just fired up my FTS1200-100 tonight for testing, it's dead on 5MHz. Does  
anyone have a good circuit idea to go from 5MHz to 10MHz? I was thinking of  
something similar to the HP5370B input circuit - basically a tuned amplifier  
locking onto the 10MHz overtone.
 
bye,
Said
 
 
In a message dated 4/19/2008 06:33:21 Pacific Daylight Time,  
[EMAIL PROTECTED] writes:

temperature related frequency changes in a typical flat. Given the  fact
that most rbs's stability at short observation times is worse that  that
of good xtal oscillators this makes the FTS1200 the best choice in  my
GPSDO despite of owning an LPRO101 and an FRK-L.

Best  regards
Ulrich




**Need a new ride? Check out the largest site for U.S. used car 
listings at AOL Autos.  
(http://autos.aol.com/used?NCID=aolcmp0030002851)
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Re: [time-nuts] Ovenaire 10 MHz OSC 49-69 PIN OUT

[Didier Juges]

Have you checked my manuals page?

http://www.ko4bb.com/cgi-bin/manuals.pl

Search for "Ovenair"

There are pictures and an email indicating the Ovenair 49-62 was Option 1
for the HP 8656A signal generator, and information is available in that
manual. Send me a direct email if you can't find the manual.

Didier KO4BB 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of jshank
> Sent: Sunday, April 20, 2008 6:55 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Ovenaire 10 MHz OSC 49-69 PIN OUT
> 
> Hi,
> I have an Ovenaire 10 MHz OSC 49-69 ser.no. 20823-3 which I 
> am in need of a pin-out and or any  other information.
> Thanks,
> Jeff

Internal Virus Database is out-of-date.
Checked by AVG. 
Version: 7.5.519 / Virus Database: 269.22.5/1358 - Release Date: 4/3/2008
6:36 PM
 


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Re: [time-nuts] using Fury GPSDO with Rb

[Bruce Griffiths]

[EMAIL PROTECTED] wrote:
> Hello Ulrich,
>  
> This is so true. See Tom's phase noise tests of a  Russian Rubidium prototype 
> disciplined by a Fury GPSDO. Lot's of times  there is not much space to put a 
> good OCXO inside the Rb's case.
>  
> BTW: using the Fury's 1PPS input, that unit can be used as a cleanup  loop 
> for dirty Rb's that have 1PPS outputs.
>  
> _http://www.leapsecond.com/pages/fury/phase.htm_ 
> (http://www.leapsecond.com/pages/fury/phase.htm) 
>  
> I just fired up my FTS1200-100 tonight for testing, it's dead on 5MHz. Does  
> anyone have a good circuit idea to go from 5MHz to 10MHz? I was thinking of  
> something similar to the HP5370B input circuit - basically a tuned amplifier  
> locking onto the 10MHz overtone.
>  
> bye,
> Said
>  
>   
Said

If you want better performance than the 5370 frequency multiplier chain 
you should use a low phase noise frequency multiplier such as one of 
those listed or depicted at:
http://www.eds-fl.com/~bruce/FrequencyMultipliers.html 


Bruce

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