[time-nuts] OT: MHz DIP

[Tom Van Baak]

Like many of us, I find my best bargains on eBay.
I happened to be searching for MHz DIP oscillators and ran across this item:

http://www.ebay.com/itm/151957504565

No replies necessary. If you are the lucky winner ("only 1 left"), please 
contact me, off-list ;-)

/tvb
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Jeremy Nichols]

My T-bolt is running on a Power-one International Series HCAS-60W-A supply,
hefty enough to run at least 4 more. Ripple and noise measure less than 100
micro-volts peak-to-peak. The T-bolt seems quite happy.

Jeremy


On Sunday, February 28, 2016, Dave M  wrote:

> Pete Lancashire wrote:
>
>> ... I was using an HP lab supply>>>
>>
>> Model ? Age ?
>>
>> My bench has some pretty old HP's even Harrison Lab branded supplies.
>> I
>> have had to re-cap a few of them.
>> In a way it is almost a curse how reliable their supplies were. You
>> always got the V and I you wanted so one
>> never thought about the filtering getting worse over the years.
>>
>> Also HP had two variations of their bench supplies. The basic ones
>> and the low noise versions. When I need
>> to make measurement like this, I make sure I'm using one of the low
>> noise/ripple models.
>>
>>
> Adding my few cents' worth to the power supply ripple/noise thoughts, I've
> found that the old linear supplies by Power Designs Inc were among the
> best, at considerably lower cost than the HP/Harrison Labs units.
> Ripple/Noise in the low millivolts and high microvolts, 0.01 - 0.005%
> regulation and temperature stability in the neighborhood of 0.01%/degC were
> common.
> I have a couple on my bench, and they just keep on working.  They still
> pop up at auction frequently.
>
> Cheers,
> Dave M
>
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-- 
Sent from Gmail Mobile
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Re: [time-nuts] HP 10544A Repair

[Glenn Little WB4UIV]

While in the navy, I had to repair a hp cesium standard.
The control circuit had the oscillator slewed to one limit, I do not 
remember whether high or low.

We had no spare parts to support this standard.
The only option was to run the standard open loop.
Over a period of two hours, I had the standard off for no more than 15 
minutes total.
To get the standard back on frequency, I had to compare this standard to 
the other standard using an oscilloscope to produce a Lissajous pattern.

I set the oscillator on frequency by stopping the rotation.
I checked it again in 6 hours and the pattern was fastly rotating.
I reset the frequency and checked it at 6 hour intervals.
It took two weeks for the oscillator to thermally stabilize after being 
off only 15 minutes.

Be prepared to have to wait to get the oscillator thermally stabilized.

I am not positive that this was a 10544A, but, it was a similar ovenized 
precision oscillator.



YMMV

73
Glenn
WB4UIV


On 2/28/2016 8:10 PM, Bob Camp wrote:

Hi

Except ….

The big steps give you more “thermal shock” on a BT and that slows things down.

Bob


On Feb 28, 2016, at 7:28 PM, Richard (Rick) Karlquist  
wrote:



On 2/28/2016 7:01 AM, Bob Camp wrote:

Hi

It’s not an electrical issue as much as a heat issue ….

Before you start, consider that you will be doing something like:

Move trimmer 1 turn CW
Wait 10 minutes
read frequency
Move trimmer 1 turn CW
wait / read
Move trimer 1/2 turn CCW
wait / read
Move trimmer 1/4 turn CW
wait / read
Move trimmer 1/8 turn CCW
wait / read
Move trimmer 1/16 turn CW
wait / read
Move trimmer 1/32 turn CW
wait / read

That is indeed an ideal version. You likely will do multiple steps at each of 
the stages rather
than get it right the first time. The part needs to be warmed up for a few days 
before you
can get to the 1/32 turn level. You also need a good standard to compare to.

Bob



Instead of that, start with the pot at max temp, and have the counter make 
measurements at, say, 1 second intervals as the oven warms up.
You can tell by looking at the plot what the peak frequency is.  Now
that you know the peak frequency you are shooting for, it will take
a lot less trial and error to find the oven setting that produces it.

Rick
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--
---
Glenn LittleARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIVwb4...@arrl.netAMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
---
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Re: [time-nuts] FW: Instrument BASIC

[Joseph Gray]

All this talk of Instrument BASIC brings up a question. Is the Windows
version "out there" somewhere? I know you can't buy it any more.

Joe Gray
W5JG


On Sun, Feb 28, 2016 at 5:11 PM, Daun Yeagley  wrote:
> Hi Magnus
>
> My memory is a bit faded on this, but the Instrument Basic on the 894xx is 
> pretty useful, and I'd recommend making use of it.  Instrument Basic is a 
> subset of "Rocky Mountain Basic" which was a very useful programming 
> language, especially for instrument control.  "Back in the day", I did some 
> programs for customers on the analyzers.  Another notable example was a 
> program that was written for performance proofs for ATSC (US digital TV 
> standard) by an engineer at Zenith.  It proved quite popular with TV 
> engineers because it pretty much automated the setup of the analyzer for 
> these tests.
> I don't know if I've still got any programming examples any more again, 
> that was a long time ago now!
> I also don't remember how difficult it is to add the option to an existing 
> analyzer.  Does your analyzer(s) have the option?
>
> Daun
>
> Daun E. Yeagley, II, N8ASB
>
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus 
> Danielson
> Sent: Saturday, February 27, 2016 11:06 AM
> To: Discussion of precise time and frequency measurement 
> Cc: mag...@rubidium.se
> Subject: [time-nuts] Instrument BASIC
>
> Fellow time-nuts,
>
> This is a little off the normal time-stuff, but I wonder if people just 
> happens to have some suitable input to give.
>
> I have a couple of HP89410A/89441A and would like to see if it would be nice 
> to see what could be done using the instrument BASIC. How would I be able to 
> enable or install it?
>
> Now, don't even bother to write comments about how you can do better using 
> software control from a PC with this and that tool, this is explicitly not 
> part of the question.
>
> Cheers,
> Magnus
> ___
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Dave M]

Pete Lancashire wrote:

... I was using an HP lab supply>>>

Model ? Age ?

My bench has some pretty old HP's even Harrison Lab branded supplies.
I
have had to re-cap a few of them.
In a way it is almost a curse how reliable their supplies were. You
always got the V and I you wanted so one
never thought about the filtering getting worse over the years.

Also HP had two variations of their bench supplies. The basic ones
and the low noise versions. When I need
to make measurement like this, I make sure I'm using one of the low
noise/ripple models.



Adding my few cents' worth to the power supply ripple/noise thoughts, I've 
found that the old linear supplies by Power Designs Inc were among the best, 
at considerably lower cost than the HP/Harrison Labs units.
Ripple/Noise in the low millivolts and high microvolts, 0.01 - 0.005% 
regulation and temperature stability in the neighborhood of 0.01%/degC were 
common.
I have a couple on my bench, and they just keep on working.  They still pop 
up at auction frequently.


Cheers,
Dave M 



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Re: [time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta  wrote:

> I am reviewing and expanding and for the NTPSec project <
> http://www.ntpsec.org >, a fork of NTP.
>

Apologies, this should have been:

I am reviewing and expanding and documentation for the NTPSec project <
http://www.ntpsec.org >, a fork of NTP.

-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] HP 10544A Repair

[Bob Camp]

Hi

Except …. 

The big steps give you more “thermal shock” on a BT and that slows things down. 

Bob

> On Feb 28, 2016, at 7:28 PM, Richard (Rick) Karlquist  
> wrote:
> 
> 
> 
> On 2/28/2016 7:01 AM, Bob Camp wrote:
>> Hi
>> 
>> It’s not an electrical issue as much as a heat issue ….
>> 
>> Before you start, consider that you will be doing something like:
>> 
>> Move trimmer 1 turn CW
>> Wait 10 minutes
>> read frequency
>> Move trimmer 1 turn CW
>> wait / read
>> Move trimer 1/2 turn CCW
>> wait / read
>> Move trimmer 1/4 turn CW
>> wait / read
>> Move trimmer 1/8 turn CCW
>> wait / read
>> Move trimmer 1/16 turn CW
>> wait / read
>> Move trimmer 1/32 turn CW
>> wait / read
>> 
>> That is indeed an ideal version. You likely will do multiple steps at each 
>> of the stages rather
>> than get it right the first time. The part needs to be warmed up for a few 
>> days before you
>> can get to the 1/32 turn level. You also need a good standard to compare to.
>> 
>> Bob
>> 
> 
> Instead of that, start with the pot at max temp, and have the counter make 
> measurements at, say, 1 second intervals as the oven warms up.
> You can tell by looking at the plot what the peak frequency is.  Now
> that you know the peak frequency you are shooting for, it will take
> a lot less trial and error to find the oven setting that produces it.
> 
> Rick
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Re: [time-nuts] FW: Instrument BASIC

[Magnus Danielson]

Hi Daun,

Lacking the option I did ask the question how to enable or install it.
I think it would be a nice way of doing some things, knowing from 
previous experience, and in particular since it seems like it also can 
act as a GPIB controller, which is useful when interacting with other 
instruments.


Cheers,
Magnus

On 02/29/2016 01:11 AM, Daun Yeagley wrote:

Hi Magnus

My memory is a bit faded on this, but the Instrument Basic on the 894xx is pretty useful, and I'd 
recommend making use of it.  Instrument Basic is a subset of "Rocky Mountain Basic" which 
was a very useful programming language, especially for instrument control.  "Back in the 
day", I did some programs for customers on the analyzers.  Another notable example was a 
program that was written for performance proofs for ATSC (US digital TV standard) by an engineer at 
Zenith.  It proved quite popular with TV engineers because it pretty much automated the setup of 
the analyzer for these tests.
I don't know if I've still got any programming examples any more again, 
that was a long time ago now!
I also don't remember how difficult it is to add the option to an existing 
analyzer.  Does your analyzer(s) have the option?

Daun

Daun E. Yeagley, II, N8ASB


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus 
Danielson
Sent: Saturday, February 27, 2016 11:06 AM
To: Discussion of precise time and frequency measurement 
Cc: mag...@rubidium.se
Subject: [time-nuts] Instrument BASIC

Fellow time-nuts,

This is a little off the normal time-stuff, but I wonder if people just happens 
to have some suitable input to give.

I have a couple of HP89410A/89441A and would like to see if it would be nice to 
see what could be done using the instrument BASIC. How would I be able to 
enable or install it?

Now, don't even bother to write comments about how you can do better using 
software control from a PC with this and that tool, this is explicitly not part 
of the question.

Cheers,
Magnus
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Re: [time-nuts] HP 10544A Repair

[Richard (Rick) Karlquist]

On 2/28/2016 7:01 AM, Bob Camp wrote:

Hi

It’s not an electrical issue as much as a heat issue ….

Before you start, consider that you will be doing something like:

Move trimmer 1 turn CW
Wait 10 minutes
read frequency
Move trimmer 1 turn CW
wait / read
Move trimer 1/2 turn CCW
wait / read
Move trimmer 1/4 turn CW
wait / read
Move trimmer 1/8 turn CCW
wait / read
Move trimmer 1/16 turn CW
wait / read
Move trimmer 1/32 turn CW
wait / read

That is indeed an ideal version. You likely will do multiple steps at each of 
the stages rather
than get it right the first time. The part needs to be warmed up for a few days 
before you
can get to the 1/32 turn level. You also need a good standard to compare to.

Bob



Instead of that, start with the pot at max temp, and have the counter 
make measurements at, say, 1 second intervals as the oven warms up.

You can tell by looking at the plot what the peak frequency is.  Now
that you know the peak frequency you are shooting for, it will take
a lot less trial and error to find the oven setting that produces it.

Rick
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Re: [time-nuts] Lady Heather Server On Raspberry Pi 2 Model B?

[Adrian Godwin]

This turned out to be an easy way to run Lady Heather itself (herself ?) on
Linux - it works well under Wine, but identifying the serial port is a
problem. But run Heather with '/ip=localhost' and ser2net to connect to the
USB serial port and all is smooth.

I used the ser2net config line

45000:raw:0:/dev/serial/by-id/usb-Generic_USB_to_Serial_Converter_OCB6T5Y1-if00-port0:9600
8DATABITS ODD 1STOPBIT LOCAL

to identify a specific ftdi converter connected to a Trimble Resolution T
rather than a thunderbolt (it requires 8 / odd / 1)






On Tue, Jan 12, 2016 at 2:40 PM, Mike George  wrote:

> Ed:
>
> A few recommendations for troubleshooting.
>
> In /etc/ser2net.conf comment out the 4 default lines (/dev/ttyS0-3)
> so that the line Nick provided is the only config present.
>
> Stop ser2net:
>  /etc/init.d/ser2net stop
> then restart:
>  /etc/init.d/ser2net start
>
> Make sure ser2net is running:
>  ps -ef | grep ser2net
>
> If not, tail /var/log/syslog and see if any errors were reported on
> statrtup.
> Normally you just see a single line reporting successful startup.
>
> If it is running , make sure it is listening on the socket you specified
> (3200):
>netstat -tln | grep 3200
>
> you should see a line with 0.0.0.0:3200 under local address
>
> There is additional troubleshooting you can do depending on results
> of above steps.
>
> Good luck.
>
> Mike
>
> On 1/12/2016 03:58, Ed Armstrong wrote:
>
>> More details please. I've installed it, but can't make it work. My
>> USB/serial cable is /dev/ttyUSB0 just like yours. I used your .conf file.
>> But lady heather says connection rejected.
>>
>>
>> Ed
>>
>> On 1/11/2016 8:00 PM, Nick Sayer via time-nuts wrote:
>>
>>> I answered my own question. :)
>>>
>>> ser2net works perfectly as a “server” for LH. I’m using a USB to serial
>>> adapter and the ser2net.conf line for it is
>>>
>>> 3200:raw:0:/dev/ttyUSB0:9600 8DATABITS NONE 1STOPBIT LOCAL
>>>
>>> And for LH, /ip=n.n.n.n:3200 works.
>>>
>>> _
>>> time-nuts mailing list -- time-nuts@febo.com
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>>>
>>>
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>>
>>
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[time-nuts] FW: Instrument BASIC

[Daun Yeagley]

Hi Magnus

My memory is a bit faded on this, but the Instrument Basic on the 894xx is 
pretty useful, and I'd recommend making use of it.  Instrument Basic is a 
subset of "Rocky Mountain Basic" which was a very useful programming language, 
especially for instrument control.  "Back in the day", I did some programs for 
customers on the analyzers.  Another notable example was a program that was 
written for performance proofs for ATSC (US digital TV standard) by an engineer 
at Zenith.  It proved quite popular with TV engineers because it pretty much 
automated the setup of the analyzer for these tests.
I don't know if I've still got any programming examples any more again, 
that was a long time ago now!
I also don't remember how difficult it is to add the option to an existing 
analyzer.  Does your analyzer(s) have the option? 

Daun

Daun E. Yeagley, II, N8ASB


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus 
Danielson
Sent: Saturday, February 27, 2016 11:06 AM
To: Discussion of precise time and frequency measurement 
Cc: mag...@rubidium.se
Subject: [time-nuts] Instrument BASIC

Fellow time-nuts,

This is a little off the normal time-stuff, but I wonder if people just happens 
to have some suitable input to give.

I have a couple of HP89410A/89441A and would like to see if it would be nice to 
see what could be done using the instrument BASIC. How would I be able to 
enable or install it?

Now, don't even bother to write comments about how you can do better using 
software control from a PC with this and that tool, this is explicitly not part 
of the question.

Cheers,
Magnus
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Bob Camp]

Hi

We have at least one example of the spurs being in the 40 to 80 Hz range 
“depending”. That strongly suggests that the original analysis is correct and 
that it is a spur in the OCXO rather than line noise induced issues in a test
setup.

Bob

> On Feb 28, 2016, at 5:49 PM, Bill Byrom  wrote:
> 
> If the spurs are at exactly 60 Hz multiples (not 120 Hz or 180 Hz) and
> you are in an area with 60 Hz line power you might have magnetic field
> coupling from nearby power transformers. Normal conductive shielding
> won't solve this issue, and Mu-Metal or other high permeability low
> frequency materials must be used. The voltage induced in ground loops by
> AC magnetic field depends on the area enclosed by the loop, so twisting
> wiring can help in some cases.
> 
> I suggest a test as follows:
> * If possible, move the DUT (device under test) to an area which is at
>   least a couple of meters from AC mains power lines and transformers
>   connected to AC mains power. Power the DUT from a battery based
>   supply. Keep any galvanic connection (any conductive wires or metal
>   cases touching metal benches) away from the DUT, except a single
>   safety ground wire.
> * If that's not easy (and I don't that level of isolation is practical
>   for most of us), then turn off all AC mains line powered equipment
>   within a couple of meters of the DUT. Unplug all equipment nearby
>   from the AC mains power line, then plug the power supply used by the
>   DUT and the minimum test equipment required for the 60 Hz spur test
>   into a single quality AC power strip. This single AC power strip
>   (with only the DUT supply and critical test equipment) should be the
>   only item plugged into the nearby AC mains power sockets. Using a
>   single quality power strip will establish a safety wire ground which
>   is nearly a single point ground. In some buildings there can be
>   problems if the safety ground wires for different AC mains line
>   sockets have different potentials due to connected equipment or water
>   pipe or other external connections.
> * Keep any transformers which are plugged into the AC mains line power
>   as far as possible from the DUT and the connections between the power
>   supply, DUT, and any test equipment.
> * Be sure to turn off any nearby AC mains line powered lighting in the
>   area and see if that changes the spurs.
> * Connect a heavy gauge (such as #10) copper wire between the metal
>   chassis or other ground point on the test equipment, power supply,
>   and DUT and see if the spur level changes. If it does, then you have
>   ground loop problems. The effective source impedance of magnetically
>   coupled currents is very low, so it can be difficult to eliminate
>   them completely. Single point ground systems are usually a good idea.
> --
> Bill Byrom N5BB
> 
> 
> 
> On Sun, Feb 28, 2016, at 12:22 PM, Adrian Godwin wrote:
>> Could it be microphonic capacitors, or the crystal itself ?
>> Have you got a big old heavy power supply with a buzzing transformer on
>> your workbench ?
>> 
> 
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Re: [time-nuts] HP 10544A Repair

[Charles Steinmetz]

Jim wrote:


Can you tell what the cut is if you have the blank in front of you?


You can do it directly with x-ray crystallography.  Otherwise, you 
need to characterize multiple crystal parameters and infer the cut 
from those, which may not be particularly accurate.


Best regards,

Charles


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[time-nuts] HP 10544A Repair

[Frank Stellmach]

Hello Nigel ,

I already have done a similar repair on a 10811, described here:

https://www.febo.com/pipermail/time-nuts/2012-January/062228.html

A comparison of the 10811 manual, p. 8-16 and schematic, let me strongly 
assume, that the 10544 has exactly the same type of NTC inside.


This NTC also has 100k @ 25°C, and 9k93k @ 80.0°C, 8k60 @ 84.0°C as the 
max. temperature.


I chose the new NTC from epcos for an exact match of the  R/T curve, and 
it's a precision type, 1% for R25 and B values , very reproducible, 
interchangeable and stable. The sample had been characterised by epcos 
at 25°C and 100°C, so R25 and B are extremely well in the middle of the 
spec, and I have 9 EA left...


Maybe you need one.. if you are located in NL, that would be no problem.

I did not find the 10544 manual, describing the correct procedure to 
correctly trim R4, but I assume you would 'simply' have to find a 
minimum or maximum in frequency, depending on the characteristics of the 
BT cut.


But I also assume that this trimmer is not accessible from outside?
Maybe difficult to trim , in this case.

Frank
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Re: [time-nuts] HP 10544A Repair

[Bob Camp]

Hi

Ok a bit more of the story. 

It’s easy to simply turn on the device and see how it warms up. Back when it 
was made, the 
SC did not yet exist. The only thing it could be was a BT. With an X-ray setup 
you can absolutely 
tell it’s a BT. With the blank and a pair of calipers you can make a darn good 
guess it’s a BT. 

Since HP did not make their own blanks, the “competition” was the source of 
their blanks. No need
for those guys to guess about anything. 

Despite all of this logical and rational thinking, the BT remained a “top 
secret” sort of thing as far
as (at least certain people at) HP were concerned. Those who were concerned 
also had the route
to the HP PR machine so that’s the story that went out to the world. 

Those involved left HP long ago. The whole thing became a non-issue once the 
10811 came out. 
What is the most amazing thing to me is that 30 years after it became a 
non-issue there still is 
confusion about the topic. 

Bob

> On Feb 28, 2016, at 11:48 AM, jimlux  wrote:
> 
> On 2/28/16 6:23 AM, Bob Camp wrote:
>> Hi
>> 
>> The whole “BT Cut” issue was a big top secret in HP. They spent a lot of 
>> time obscuring
>> the fact that they used BT’s. The belief was that if any of the other 
>> outfits figured out that
>> was what they were doing, the competition would have better OCXO’s.
>> 
> 
> 
> Can you tell what the cut is if you have the blank in front of you?
> 
> Wouldn't the competition just buy an instrument with the oscillator, saw it 
> open, and measure it?
> 
> 
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Re: [time-nuts] WWVB format change in 2012

[Bob Camp]

Hi

WWVB and WWV (like any radio uncorrected radio system) has fairly predictable 
shifts
associated with the day / night ionosphere. One *could* fix that issue with a 
table
based on station location. I do not know of any library of code that does that 
already. 

The next “layer” of trouble comes from how the low cost receivers are 
implemented. The
common issue is local noise. The common solution is a narrowband crystal filter 
in front
of the receiver. The bandwidth of that filter (and to some extent it’s 
temperature dependance) place
a “best case” limit on performance in the 10’s to 100’s of ms range depending 
on the 
exact details. There are higher performance receivers (but not a lot of them) 
that do get into
the single digit ms range. At that point the propagation issue mentioned above 
needs some
work. 

Further complicating things is the distance factor. A user in Denver with 
ground wave “view” 
of the transmitter will do *much* better than the numbers above. A user in 
Miami or Bangor ME 
may be very lucky to get close to the numbers above on an intermittent basis. 

For time transfer, you have “carrier phase ambiguity” due to the day night 
propagation shifts. Simply
put the time delay to the transmitter caused the received signal to vary by 
more than one cycle. That 
makes it a less than ideal source of time. For precision use, a WWVB system 
often does a 
carrier measure at a single time per day. The phase data is averaged over may 
days to make
a precision estimate. This works ok for a frequency based (think GPSDO) type 
system). For autonomous 
timing it’s not a practical solution. 

Bob


> On Feb 28, 2016, at 11:15 AM, Sanjeev Gupta  wrote:
> 
> On Sun, Feb 28, 2016 at 10:57 PM, Bob Camp  wrote:
> 
>> The new WWVB format is troublesome for older gear that looks at carrier
>> phase as a source of precision timing. The NTP driver does not do this.
>> 
>> The new WWVB format is fine for any gear that recovers time from the
>> AM modulation on the carrier. This is what the NTP driver *does* do.
>> 
> 
> This is a very clear phrasing, thanks.
> 
> My understanding is that existing commercially-available equipment that
> recovers time from the AM carrier provides an accuracy on the order of a
> milli-second.  Anything better required tracking phase.
> 
> So, what would the (NTP with current WWVB equipment) accuracy and jitter be?
> 
> I appreciate that we seem to be moving towards a GPS-monoculture, but how
> close is the (NTP with WWVB AM) to the 50 microseconds number?
> 
> -- 
> Sanjeev Gupta
> +65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] Next step up from basic GPS/PPS timekeeping

[Neil Green]

On 25 Feb 2016, at 9:07 pm, Jim Harman  wrote:

> On Thu, Feb 25, 2016 at 1:08 PM, Neil Green  wrote:
> 
>> I’ve decided to build this:
>> 
>> http://www.hackersbench.com/Projects/1Hz/
> 
> Good start!
> 
> Once you have built it and observed how sensitive it is to temperature
> variations, you might want to take a look at this:
> 
> https://www.adafruit.com/products/3013

So, after some fighting and frustration and sleeping on it, I successfully 
assembled the circuit I linked to above and powered it from a regulated 5V 
breadboard power supply:

http://86.17.250.240/IMG_1750s.jpg

I had a DS3231 lying around so, as per Jim Harman’s suggestion I used its 32K 
output instead of a cheapo 32.768Hz crystal. The results were initially as 
disappointing as I’d expected but, after ensuring that the oscillator *and* the 
32k output of the DS3231 were enabled, and building a custom kernel for the 
Raspberry Pi to include KPPS processing, things improved dramatically. A 
typical output of 'ppstest /dev/pps0':

source 0 - assert 1456678708.00032, sequence: 3205 - clear  0.0, 
sequence: 0
source 0 - assert 1456678709.01034, sequence: 3206 - clear  0.0, 
sequence: 0
source 0 - assert 1456678710.00034, sequence: 3207 - clear  0.0, 
sequence: 0
source 0 - assert 1456678711.01035, sequence: 3208 - clear  0.0, 
sequence: 0
source 0 - assert 1456678712.04033, sequence: 3209 - clear  0.0, 
sequence: 0
source 0 - assert 1456678713.01035, sequence: 3210 - clear  0.0, 
sequence: 0
source 0 - assert 1456678714.00033, sequence: 3211 - clear  0.0, 
sequence: 0
source 0 - assert 1456678715.01035, sequence: 3212 - clear  0.0, 
sequence: 0
source 0 - assert 1456678716.00034, sequence: 3213 - clear  0.0, 
sequence: 0
source 0 - assert 1456678717.01034, sequence: 3214 - clear  0.0, 
sequence: 0
source 0 - assert 1456678718.01034, sequence: 3215 - clear  0.0, 
sequence: 0
source 0 - assert 1456678719.01034, sequence: 3216 - clear  0.0, 
sequence: 0
source 0 - assert 1456678720.00035, sequence: 3217 - clear  0.0, 
sequence: 0
source 0 - assert 1456678721.00034, sequence: 3218 - clear  0.0, 
sequence: 0
source 0 - assert 1456678722.01034, sequence: 3219 - clear  0.0, 
sequence: 0
source 0 - assert 1456678723.02034, sequence: 3220 - clear  0.0, 
sequence: 0
source 0 - assert 1456678724.00033, sequence: 3221 - clear  0.0, 
sequence: 0

As you can see, the numbers are jumping about a bit but they are comparable to 
the GPS PPS output I have running of another Pi. The next stage is to tidy 
everything up, simplify where possible, shrink it and try to squeeze it into an 
enclosure. After that I'll maybe try to get my head around a 10mHz to 1hz 
version.

Thanks to everyone who offered advice. It was all helpful.

Neil.
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Bill Byrom]

If the spurs are at exactly 60 Hz multiples (not 120 Hz or 180 Hz) and
you are in an area with 60 Hz line power you might have magnetic field
coupling from nearby power transformers. Normal conductive shielding
won't solve this issue, and Mu-Metal or other high permeability low
frequency materials must be used. The voltage induced in ground loops by
AC magnetic field depends on the area enclosed by the loop, so twisting
wiring can help in some cases.

I suggest a test as follows:
 * If possible, move the DUT (device under test) to an area which is at
   least a couple of meters from AC mains power lines and transformers
   connected to AC mains power. Power the DUT from a battery based
   supply. Keep any galvanic connection (any conductive wires or metal
   cases touching metal benches) away from the DUT, except a single
   safety ground wire.
 * If that's not easy (and I don't that level of isolation is practical
   for most of us), then turn off all AC mains line powered equipment
   within a couple of meters of the DUT. Unplug all equipment nearby
   from the AC mains power line, then plug the power supply used by the
   DUT and the minimum test equipment required for the 60 Hz spur test
   into a single quality AC power strip. This single AC power strip
   (with only the DUT supply and critical test equipment) should be the
   only item plugged into the nearby AC mains power sockets. Using a
   single quality power strip will establish a safety wire ground which
   is nearly a single point ground. In some buildings there can be
   problems if the safety ground wires for different AC mains line
   sockets have different potentials due to connected equipment or water
   pipe or other external connections.
 * Keep any transformers which are plugged into the AC mains line power
   as far as possible from the DUT and the connections between the power
   supply, DUT, and any test equipment.
 * Be sure to turn off any nearby AC mains line powered lighting in the
   area and see if that changes the spurs.
 * Connect a heavy gauge (such as #10) copper wire between the metal
   chassis or other ground point on the test equipment, power supply,
   and DUT and see if the spur level changes. If it does, then you have
   ground loop problems. The effective source impedance of magnetically
   coupled currents is very low, so it can be difficult to eliminate
   them completely. Single point ground systems are usually a good idea.
--
Bill Byrom N5BB
 
 
 
On Sun, Feb 28, 2016, at 12:22 PM, Adrian Godwin wrote:
> Could it be microphonic capacitors, or the crystal itself ?
> Have you got a big old heavy power supply with a buzzing transformer on
> your workbench ?
>  
 
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Pete Lancashire]

... I was using an HP lab supply>>>

Model ? Age ?

My bench has some pretty old HP's even Harrison Lab branded supplies. I
have had to re-cap a few of them.
In a way it is almost a curse how reliable their supplies were. You always
got the V and I you wanted so one
never thought about the filtering getting worse over the years.

Also HP had two variations of their bench supplies. The basic ones and the
low noise versions. When I need
to make measurement like this, I make sure I'm using one of the low
noise/ripple models.

Another thing that is pretty easy to eliminate is radiated 60 Hz. Build a
cell (box). A very simple disposable one
can be from a corrugated box, aluminum foil, and a few feed through
connections.

Any lighting not based on piece of tungsten wire ?

On Sat, Feb 27, 2016 at 1:07 PM, Rob Sherwood.  wrote:

> I cannot say exactly, as I measured it as 59 Hz.  VA7OJ measured it as 60
> Hz.  I was using an HP lab supply, and Adam was using some other lab
> supply.  I put a 500 uF capacitor across the Vcc pin and it had no effect.
> I don't think it has anything to do with the power supply since both of us
> saw the same thing.  If an attachment will go through this reflector, I can
> post a spectrum analyzer screen shot.
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of jimlux
> Sent: Saturday, February 27, 2016 12:07 PM
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Inside a CTS 1960017 OCXO
>
>
>
> On 2/27/16 9:35 AM, Rob Sherwood. wrote:
> > Hi Dan,
> >
> > I purchased two of these, and VA7OJ one.  One of mine is defective, and
> the seller is going to replace it.  What was disappointing was all the
> spurious at 60 Hz intervals relatively close-in to the 10 MHz carrier.  I
> suppose if all one wants is a reasonably accurate 10 MHz, then they work
> OK.  My good one and Adam's unit were 1x10^7 low in frequency once warmed
> up, and there are pins for frequency adjustment and sync to another
> standard.  However if one wanted it for an oscillator with good close-in
> phase noise, the spurs ruin that hope.
> >
> > Do you know if there is a chopper at 60 Hz that runs the proportional
> oven that is the source of all the spurious?
> >
>
>
> Is it right at line frequency, or is it "close" to 60 Hz?
>
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Re: [time-nuts] WWVB format change in 2012

[Paul]

On Sun, Feb 28, 2016 at 2:09 AM, Sanjeev Gupta  wrote:

>
> Among NTPSec's goals are a smaller, auditable, code-base; hence support for
> receivers last available in the early-1990s is being removed.
>

I'm a bit confused by your question and the responses.

There are (I believe) three audio drivers supporting WWV, CHU and IRIG.
These drivers are receiver agnostic.  If you can get audio they work.  The
documented accuracy for WWV is within 1 millisecond of the time pulse.

There are multiple drivers supporting WWV/CHU/DCF.  These are for specific
families of RF receivers which produce a digital stream of some sort (e.g.
ISA bus communication).

Presumably the latter are what you're looking at as obsolete (e.g.
Truetime, Traconix, Chronolog, Ultralink etc. [and my apologies if any of
these are not obsolete]).

Perhaps you could clarify your intent.
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Re: [time-nuts] HP 10544A Repair

[Magnus Danielson]

Jim,

Why cut it open? It is relatively easy to measure just by power the 
oscillator up. Just in this thread is an echo of a discussion we had 
many years ago that explains the method.


The temperature curve for AT, BT and SC-cut is known and quite 
different, so just measure the heat-up curve from room temperature to 
oven temperature will be distinct for these types. I think the IT-cut 
can also be identified uniquely this way.


If you have the crystal blank, you can use X-ray to see the 
crystal-orientation.


Cheers,
Magnus

On 02/28/2016 05:48 PM, jimlux wrote:

On 2/28/16 6:23 AM, Bob Camp wrote:

Hi

The whole “BT Cut” issue was a big top secret in HP. They spent a lot
of time obscuring
the fact that they used BT’s. The belief was that if any of the other
outfits figured out that
was what they were doing, the competition would have better OCXO’s.




Can you tell what the cut is if you have the blank in front of you?

Wouldn't the competition just buy an instrument with the oscillator, saw
it open, and measure it?


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Re: [time-nuts] WWVB format change in 2012

[jimlux]

On 2/28/16 7:07 AM, Sanjeev Gupta wrote:

On Sun, Feb 28, 2016 at 9:45 PM, Tim Shoppa  wrote:


Support for WWV in ntpd using the wwv_audio refclock is very good and
delivers jitters substantially less than a millisecond. I have been using
this for over a decade.



Thank you.  In particular, WWV, as compared to WWVB.


What you're looking at (unless you're very close to WWV or WWVH) is the 
uncertainty in the skywave path through the ionosphere.





Is there an on-web reference that I can document, so that the NTPSec
developers can decide on if and how to support WWV.



A reference to what WWV radiates as a signal?
http://www.nist.gov/pml/div688/grp40/wwv.cfm

http://tf.nist.gov/general/pdf/1383.pdf



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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Adrian Godwin]

Could it be microphonic capacitors, or the crystal itself ?
Have you got a big old heavy power supply with a buzzing transformer on
your workbench ?


On Sun, Feb 28, 2016 at 3:04 PM, Daniel Watson 
wrote:

> Hi,
>
> I put one in a freezer and measured the current draw. At -12*C, it drew
> about 320 mA steady state (1.6W).
>
> Dan
>
> On Sat, Feb 27, 2016 at 7:30 PM, Rob Sherwood.  wrote:
>
> > The part draws 600 mA during warm-up, and drops to around 230 to 200 mA
> > when stabilized.
> > Rob
> > NC0B
> >
> > -Original Message-
> > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
> Camp
> > Sent: Saturday, February 27, 2016 2:26 PM
> > To: Discussion of precise time and frequency measurement
> > Subject: Re: [time-nuts] Inside a CTS 1960017 OCXO
> >
> >
> >
> > Hi
> >
> > A small air gap is actually a better insulator than conventional foam.
> You
> > don’t get much of a convection cell going at those spacings. The part
> > likely pulls a bit over a watt at room.
> >
> > If you put an insulator on the gizmo you increase it’s thermal gain. That
> > will most likely make the temperature performance significantly worse.
> See
> > the good old papers on the HP super ovens for all the details.
> >
> > Bob
> >
> > > On Feb 27, 2016, at 12:44 PM, Tom Miller 
> > wrote:
> > >
> > >
> > > - Original Message - From: "Daniel Watson"
> > > 
> > > To: 
> > > Sent: Saturday, February 27, 2016 11:48 AM
> > > Subject: [time-nuts] Inside a CTS 1960017 OCXO
> > >
> > >
> > >> Hi,
> > >>
> > >> I'm sure many of you are tracking the cheap CTS 10MHz OCXOs available
> > >> on eBay right now. I purchased a case of them, and decided to crack
> one
> > open.
> > >> I took pictures along the way, thinking that might be interesting to
> > >> the list. Here is the blog post if you are interested:
> > >>
> > >> http://syncchannel.blogspot.com/2016/02/10mhz-ocxo-teardown-cts-19600
> > >> 17.html
> > >>
> > >> Comments on the internal construction of the OCXO are welcome. It
> > >> seems pretty straightforward inside though.
> > >>
> > >>
> > >> Best regards,
> > >>
> > >> Dan W.
> > >
> > > Looks like it would use a lot of power in a cold environment. Maybe a
> > second oven would be nice. They seem to have marked the turnover temp on
> > the xtal.
> > >
> > > Regards
> > > ___
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> > and follow the instructions there.
> >
> >
> >
> > --
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> >
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Re: [time-nuts] WWVB format change in 2012

[James Flynn]

Sanjeev Gupta  writes:


> that as a result of the change, precision equipment may not be able to
> recover a usable signal from the new modulation scheme, rendering it
> useless for the sub-100 microsec disciplining.

In fact, the new scheme may actually help with accurate ON-TIME 
determination.  Currently, I have a proof-of-concept research system 
running that routinely keeps time to well within the rather broad 100 uS 
range when compared to GPS. This system does not yet use the phase 
information, but uses other techniques to extract the ON-TIME information 
from the signal (which still has to be corrected for propagation delays.) 
Future work will include using the phase information and I am confident 
this will only improve the results.

> A supplementary question: If you have your own homebrew for these 
signals,
> do you use them as a refclock for NTP?

While the proof-of-concept system is not being used for a refclock for 
NTP, it is able to keep time as described above and FREQUENCY to the under 
1 E-10 range. I am still working to improve that and hope to verify it in 
a way directly traceable to NIST.

James Flynn
California State University Northridge




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Re: [time-nuts] WWVB format change in 2012

[Majdi S. Abbas]

On Sun, Feb 28, 2016 at 03:09:32PM +0800, Sanjeev Gupta wrote:
> I am reviewing and expanding and for the NTPSec project <
> http://www.ntpsec.org >, a fork of NTP.
> 
> Among NTPSec's goals are a smaller, auditable, code-base; hence support for
> receivers last available in the early-1990s is being removed.

I'm not sure I would make that assumption.  Given recent attacks
on NTP (that will ultimately require a new protocol to fix), the ability 
of more upstream references is better than fewer.

Stripping things out that would provide more sources of trusted
time appears to be at odds with making NTP "more secure."

> I have been on this list for some years (thank you), but as I am in
> Singapore, I did not pay attention to the WWVB format change.  I understand
> that as a result of the change, precision equipment may not be able to
> recover a usable signal from the new modulation scheme, rendering it
> useless for the sub-100 microsec disciplining.

So the common, cheaper receivers that just looked at the AM 
envelope are unaffected.  Higher grade, phase tracking receivers were
affected, but can be modified to restore the carrier, and thus are
still operable.

> However, I am not clear if WWV and WWVH are still usable by commercially
> available equipment, or of such equipment is also obsolete now.

WWV and WWVH have worked pretty much the same way they do now
for decades; I have running WWV and WWVH refclocks, even the TrueTime
TL_3 (in REFCLOCK_TRUE.)

Where this gets sticky is there is support for older receivers
(say, OMEGA and the like), in the same refclocks (continuing to use
TRUE as an example here.)

So, you could safely remove the bits pertaining to OMEGA, but
I'd retain the WWV, WWVB, TCU, and XL-DC support.)  Since the XL-DC
is a GPS, I suppose you could implement support for it in gpsd.

Other, older refclocks are in a similar state, where one
vendor used more or less the same serial protocol regardless of 
what the actual reference was.

What are you trying to do?  Kill the refclocks entirely, or
just pare them down to essentials?

Cheers,

--msa 
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Re: [time-nuts] HP 10544A Repair

[jimlux]

On 2/28/16 6:23 AM, Bob Camp wrote:

Hi

The whole “BT Cut” issue was a big top secret in HP. They spent a lot of time 
obscuring
the fact that they used BT’s. The belief was that if any of the other outfits 
figured out that
was what they were doing, the competition would have better OCXO’s.




Can you tell what the cut is if you have the blank in front of you?

Wouldn't the competition just buy an instrument with the oscillator, saw 
it open, and measure it?



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Re: [time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

On Sun, Feb 28, 2016 at 10:57 PM, Bob Camp  wrote:

> The new WWVB format is troublesome for older gear that looks at carrier
> phase as a source of precision timing. The NTP driver does not do this.
>
> The new WWVB format is fine for any gear that recovers time from the
> AM modulation on the carrier. This is what the NTP driver *does* do.
>

This is a very clear phrasing, thanks.

My understanding is that existing commercially-available equipment that
recovers time from the AM carrier provides an accuracy on the order of a
milli-second.  Anything better required tracking phase.

So, what would the (NTP with current WWVB equipment) accuracy and jitter be?

I appreciate that we seem to be moving towards a GPS-monoculture, but how
close is the (NTP with WWVB AM) to the 50 microseconds number?

-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

On Sun, Feb 28, 2016 at 9:45 PM, Tim Shoppa  wrote:

> Support for WWV in ntpd using the wwv_audio refclock is very good and
> delivers jitters substantially less than a millisecond. I have been using
> this for over a decade.
>

Thank you.  In particular, WWV, as compared to WWVB.

Is there an on-web reference that I can document, so that the NTPSec
developers can decide on if and how to support WWV.

-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Daniel Watson]

Hi,

I put one in a freezer and measured the current draw. At -12*C, it drew
about 320 mA steady state (1.6W).

Dan

On Sat, Feb 27, 2016 at 7:30 PM, Rob Sherwood.  wrote:

> The part draws 600 mA during warm-up, and drops to around 230 to 200 mA
> when stabilized.
> Rob
> NC0B
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp
> Sent: Saturday, February 27, 2016 2:26 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Inside a CTS 1960017 OCXO
>
>
>
> Hi
>
> A small air gap is actually a better insulator than conventional foam. You
> don’t get much of a convection cell going at those spacings. The part
> likely pulls a bit over a watt at room.
>
> If you put an insulator on the gizmo you increase it’s thermal gain. That
> will most likely make the temperature performance significantly worse. See
> the good old papers on the HP super ovens for all the details.
>
> Bob
>
> > On Feb 27, 2016, at 12:44 PM, Tom Miller 
> wrote:
> >
> >
> > - Original Message - From: "Daniel Watson"
> > 
> > To: 
> > Sent: Saturday, February 27, 2016 11:48 AM
> > Subject: [time-nuts] Inside a CTS 1960017 OCXO
> >
> >
> >> Hi,
> >>
> >> I'm sure many of you are tracking the cheap CTS 10MHz OCXOs available
> >> on eBay right now. I purchased a case of them, and decided to crack one
> open.
> >> I took pictures along the way, thinking that might be interesting to
> >> the list. Here is the blog post if you are interested:
> >>
> >> http://syncchannel.blogspot.com/2016/02/10mhz-ocxo-teardown-cts-19600
> >> 17.html
> >>
> >> Comments on the internal construction of the OCXO are welcome. It
> >> seems pretty straightforward inside though.
> >>
> >>
> >> Best regards,
> >>
> >> Dan W.
> >
> > Looks like it would use a lot of power in a cold environment. Maybe a
> second oven would be nice. They seem to have marked the turnover temp on
> the xtal.
> >
> > Regards
> > ___
> > 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.
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Re: [time-nuts] WWVB format change in 2012

[Bob Camp]

Hi


Ok, I think we have a bit of a terminology issue here. 

The new WWVB format is troublesome for older gear that looks at carrier 
phase as a source of precision timing. The NTP driver does not do this.

The new WWVB format is fine for any gear that recovers time from the 
AM modulation on the carrier. This is what the NTP driver *does* do. 

Simply put - WWVB and NTP work just as well today as they did 20 years
ago. 

As a “future project”, adding a driver to NTP to work with the bitstream from 
the new phase modulation would be a nice thing. At the moment the number
of receivers capable of handling this modulation is pretty small. I would 
wait until there is at least one commercial product on the market before
a driver is written.

Bob

> On Feb 28, 2016, at 2:09 AM, Sanjeev Gupta  wrote:
> 
> Hi,
> 
> I am reviewing and expanding and for the NTPSec project <
> http://www.ntpsec.org >, a fork of NTP.
> 
> Among NTPSec's goals are a smaller, auditable, code-base; hence support for
> receivers last available in the early-1990s is being removed.
> 
> I have been on this list for some years (thank you), but as I am in
> Singapore, I did not pay attention to the WWVB format change.  I understand
> that as a result of the change, precision equipment may not be able to
> recover a usable signal from the new modulation scheme, rendering it
> useless for the sub-100 microsec disciplining.
> 
> However, I am not clear if WWV and WWVH are still usable by commercially
> available equipment, or of such equipment is also obsolete now.
> 
> I have read Wikipedia, the NIST pages, etc, and am still confused.  Could
> someone summarise current state:
> 
> 
>   1. Are there commercially (or widely-used) receivers for professional
>   use which listen to the WWVB signal?
>   2. Are there commercially (or widely-used) receivers for professional
>   use which listen to the WWV(H) signal?
> 
> A supplementary question: If you have your own homebrew for these signals,
> do you use them as a refclock for NTP?
> 
> Thank you
> 
> 
> -- 
> Sanjeev Gupta
> +65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] HP 10544A Repair

[Bob Camp]

Hi

It’s not an electrical issue as much as a heat issue ….

Before you start, consider that you will be doing something like:

Move trimmer 1 turn CW
Wait 10 minutes
read frequency
Move trimmer 1 turn CW
wait / read
Move trimer 1/2 turn CCW
wait / read
Move trimmer 1/4 turn CW
wait / read
Move trimmer 1/8 turn CCW
wait / read
Move trimmer 1/16 turn CW
wait / read
Move trimmer 1/32 turn CW
wait / read

That is indeed an ideal version. You likely will do multiple steps at each of 
the stages rather 
than get it right the first time. The part needs to be warmed up for a few days 
before you 
can get to the 1/32 turn level. You also need a good standard to compare to.

Bob


> On Feb 28, 2016, at 2:53 AM, Nigel Vander Houwen 
>  wrote:
> 
> Mark,
> 
> I don’t see that referenced in the documentation, and the frequency 
> adjustment pot appears to be plastic, but I will compare a non-conductive 
> tool, to a conductive one to see if it makes a difference.
> 
> Nigel
> 
>> On Feb 27, 2016, at 19:11, Mark Sims  wrote:
>> 
>> Also, when messing with a 10544A be aware that  that the frequency tuning 
>> adjustment must be made with an insulated tool.  
>> 
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Re: [time-nuts] HP 10544A Repair

[Bob Camp]

Hi

The whole “BT Cut” issue was a big top secret in HP. They spent a lot of time 
obscuring 
the fact that they used BT’s. The belief was that if any of the other outfits 
figured out that
was what they were doing, the competition would have better OCXO’s. 

Watch the frequency as it turns on. An AT will go down a bunch in frequency as 
it warms up. 
An SC or BT will go up. 

Bob

> On Feb 27, 2016, at 11:38 PM, Nigel Vander Houwen 
>  wrote:
> 
> Bob,
> 
> I’m not sure what type is in it. It *is* a 10544A, not one of the 10811 
> devices. The references I’ve found indicate the 10544A being an AT type. If 
> it’s of any use, the date codes on the parts in the oven control circuit 
> indicate it was built in the latter part of ’77.
> 
> I can’t say I’ve got a whole lot of experience looking at this, but should I 
> expect to see a curve along the values, of which there would either be a 
> minimum or maximum? That would be fairly indicative.
> 
> Rick,
> 
> The thermistor was not an exact replacement, and I couldn’t find any 
> specifications beyond 9.93KOhm @ 80C referenced on the schematic. I don’t 
> know that the pot wasn’t turned during the original debugging of why the 
> crystal wasn’t on frequency, so my best bet now unfortunately is to find the 
> set point myself.
> 
> Nigel
> 
> 
> 
>> On Feb 27, 2016, at 19:39, Richard (Rick) Karlquist  
>> wrote:
>> 
>> If you replaced the thermistor with an exact replacement,
>> then you shouldn't need to change the pot.  If you didn't
>> replace the thermistor with an exact replacement, then you
>> should carefully measure the resistance of the pot as you
>> found it.  (I hope you did not fool with it already.)  From
>> the pot resistance, and the thermistor curve specs of
>> the original thermistor, you should be able to calculate
>> the factory oven temperature set point.  You can then
>> calculate the new pot resistance based on the specs
>> for the replacement thermistor.
>> 
>> Trying to determine the turn over temperature as you
>> described (which was done with an automated system
>> in the E1938A) would be extremely cumbersome when
>> done by hand.  It would be a last resort if you fooled
>> with the pot.
>> 
>> Rick
>> 
>> On 2/27/2016 6:48 PM, Nigel Vander Houwen wrote:
>>> Hello All,
>>> 
>>> Relatively new to the group, but thought I’d ask for a bit of advice. I 
>>> have an old HP 10544A ovenized oscillator that was pull from some equipment 
>>> some time ago because it got too far off frequency to phase lock with the 
>>> external reference. It looks like the thermistor in the oven controller 
>>> failed, and just wouldn’t ever turn the oven on.
>>> 
>>> I’ve replaced the thermistor, and the oven is working properly again, but I 
>>> need to tune the temperature as appropriate for this crystal. I’ve read 
>>> that this involves plotting crystal frequency vs temperature, so I’ll need 
>>> to adjust the potentiometer inside, close it up again, wait for temperature 
>>> to stabilize, and take a frequency measurement, and iterate.
>>> 
>>> If I’ve understood what I’ve read correctly, I’m looking for a flat in the 
>>> frequency response of the crystal with regards to temperature.
>>> 
>>> I do have a HP 5345A referenced from a thunderbolt to do the frequency 
>>> measurement.
>>> 
>>> Am I on the right track? Further insights? Etc?
>>> 
>>> Thanks all!
>>> Nigel
>>> K7NVH
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Alex Pummer]

Hi Dan
 how many of these oscillators have that low freq.hum?
73
KJ6UHN
Alex

On 2/27/2016 6:25 PM, Daniel Watson wrote:

Hi,

Attached is a plot of the output frequency difference from 10MHz during
warm-up. I believe this indicates the crystal is SC cut.

The VREF and EFC pins on the unit do work. The VREF is 4.1V.

I probed around the board of the unit I cracked open and found a low
frequency oscillation. It seems to vary from 40 to 90 Hz depending on where
the unit is in the warm-up cycle, and what I'm doing to it. With the can
cut off, the unit draws almost 50% more power than normal trying to
maintain temperature, so it's possible this is offset from what has been
reported in normal units.

In the photos, you may have noticed two sets of large, unpopulated pads on
the board near the output. I experimented with putting 10uF capacitors
across those. That killed the output, but the low frequency oscillation
could still be detected further back in the circuit.


Dan

On Sat, Feb 27, 2016 at 1:10 PM, Joseph Gray  wrote:


Nice teardown. I was looking at that listing just yesterday. I am tempted,
but don't know what I'd do with 40.

The real question is, how do they perform?

Joe Gray
W5JG
On Feb 27, 2016 9:48 AM, "Daniel Watson"  wrote:


Hi,

I'm sure many of you are tracking the cheap CTS 10MHz OCXOs available on
eBay right now. I purchased a case of them, and decided to crack one

open.

I took pictures along the way, thinking that might be interesting to the
list. Here is the blog post if you are interested:




http://syncchannel.blogspot.com/2016/02/10mhz-ocxo-teardown-cts-1960017.html

Comments on the internal construction of the OCXO are welcome. It seems
pretty straightforward inside though.


Best regards,

Dan W.
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Rob Sherwood .]

The part draws 600 mA during warm-up, and drops to around 230 to 200 mA when 
stabilized.
Rob
NC0B

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp
Sent: Saturday, February 27, 2016 2:26 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Inside a CTS 1960017 OCXO



Hi

A small air gap is actually a better insulator than conventional foam. You 
don’t get much of a convection cell going at those spacings. The part likely 
pulls a bit over a watt at room.

If you put an insulator on the gizmo you increase it’s thermal gain. That will 
most likely make the temperature performance significantly worse. See the good 
old papers on the HP super ovens for all the details.

Bob

> On Feb 27, 2016, at 12:44 PM, Tom Miller  wrote:
> 
> 
> - Original Message - From: "Daniel Watson" 
> 
> To: 
> Sent: Saturday, February 27, 2016 11:48 AM
> Subject: [time-nuts] Inside a CTS 1960017 OCXO
> 
> 
>> Hi,
>> 
>> I'm sure many of you are tracking the cheap CTS 10MHz OCXOs available 
>> on eBay right now. I purchased a case of them, and decided to crack one open.
>> I took pictures along the way, thinking that might be interesting to 
>> the list. Here is the blog post if you are interested:
>> 
>> http://syncchannel.blogspot.com/2016/02/10mhz-ocxo-teardown-cts-19600
>> 17.html
>> 
>> Comments on the internal construction of the OCXO are welcome. It 
>> seems pretty straightforward inside though.
>> 
>> 
>> Best regards,
>> 
>> Dan W.
> 
> Looks like it would use a lot of power in a cold environment. Maybe a second 
> oven would be nice. They seem to have marked the turnover temp on the xtal.
> 
> Regards
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Re: [time-nuts] WWVB format change in 2012

[Tim Shoppa]

Having a diversity of refclocks is important for any real NTP
implementation. There is a strong tendency towards a GPS monoculture and
the implementers must work against it.

Support for WWV in ntpd using the wwv_audio refclock is very good and
delivers jitters substantially less than a millisecond. I have been using
this for over a decade.

ntpd also supports CHU.

Here is a recent article showing how to use the BPSK format of WWVB:
http://www.arrl.org/files/file/QEX_Next_Issue/2015/Nov-Dec_2015/Magliacane.pdf

Tim N3QE

On Sun, Feb 28, 2016 at 2:09 AM, Sanjeev Gupta  wrote:

> Hi,
>
> I am reviewing and expanding and for the NTPSec project <
> http://www.ntpsec.org >, a fork of NTP.
>
> Among NTPSec's goals are a smaller, auditable, code-base; hence support for
> receivers last available in the early-1990s is being removed.
>
> I have been on this list for some years (thank you), but as I am in
> Singapore, I did not pay attention to the WWVB format change.  I understand
> that as a result of the change, precision equipment may not be able to
> recover a usable signal from the new modulation scheme, rendering it
> useless for the sub-100 microsec disciplining.
>
> However, I am not clear if WWV and WWVH are still usable by commercially
> available equipment, or of such equipment is also obsolete now.
>
> I have read Wikipedia, the NIST pages, etc, and am still confused.  Could
> someone summarise current state:
>
>
>1. Are there commercially (or widely-used) receivers for professional
>use which listen to the WWVB signal?
>2. Are there commercially (or widely-used) receivers for professional
>use which listen to the WWV(H) signal?
>
> A supplementary question: If you have your own homebrew for these signals,
> do you use them as a refclock for NTP?
>
> Thank you
>
>
> --
> Sanjeev Gupta
> +65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] MTI 260-0624-D OCXO

[Angus]

On Sat, 20 Feb 2016 14:56:47 -0500, you wrote:

>I think that there are a lot of unexplored possibilities, but I definitely am
>not convinced that it sets either the inner or outer oven temperature. There
>are simply better ways to do that in production.

Hi Mike,

On the two that I tested, it appeared to adjust the temperature of
both of the ovens.

One was a 5 MHz 260-0545-B. The outer oven was at 78.2 degC and at
least around that point the temp changed at about 1 degC per turn. The
EFC adjustment on this one was not quite enough to bring the frequency
to exactly 5 MHz, but the oven temp did look to be close to correct.

The other was a 16.384 MHz 260-0546-G which was unused old stock, but
had overall poor stability. It turned out that the oven temp on it was
1-3/8 turns from the turnover point, but when or how that happened I
don't know.

It would be interesting to hear from somebody who knows how this type
of thing is actually adjusted in production. 

Angus.


>> If this is a double oven, there are two oven circuits and two oven 
>> controllers.
>> Both would have a set point and both would be adjusted somehow. The pot
>> may be the adjustment on the outer oven. Get things all set up and packaged,
>> then adjust the outer oven to make things do what the should do.
>
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Re: [time-nuts] HP 10544A Repair

[Nigel Vander Houwen]

Hal,

It depends a lot on the thermistor. As with any component, there are higher 
precision models that would be pretty repeatable within a model number, and 
cheaper ones that will be somewhat less repeatable. In this case I didn’t have 
a specific model number, nor specific nominal/beta values, so I chose a 
reasonable 100K NTC thermistor, and am adjusting for that.

Nigel

> On Feb 27, 2016, at 20:21, Hal Murray  wrote:
> 
> 
> rich...@karlquist.com said:
>> If you replaced the thermistor with an exact replacement, then you shouldn't
>> need to change the pot.  ...
> 
> How repeatable are thermistors?  How close do you need/want to get the 
> temperature?
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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[time-nuts] WWVB format change in 2012

[Sanjeev Gupta]

Hi,

I am reviewing and expanding and for the NTPSec project <
http://www.ntpsec.org >, a fork of NTP.

Among NTPSec's goals are a smaller, auditable, code-base; hence support for
receivers last available in the early-1990s is being removed.

I have been on this list for some years (thank you), but as I am in
Singapore, I did not pay attention to the WWVB format change.  I understand
that as a result of the change, precision equipment may not be able to
recover a usable signal from the new modulation scheme, rendering it
useless for the sub-100 microsec disciplining.

However, I am not clear if WWV and WWVH are still usable by commercially
available equipment, or of such equipment is also obsolete now.

I have read Wikipedia, the NIST pages, etc, and am still confused.  Could
someone summarise current state:


   1. Are there commercially (or widely-used) receivers for professional
   use which listen to the WWVB signal?
   2. Are there commercially (or widely-used) receivers for professional
   use which listen to the WWV(H) signal?

A supplementary question: If you have your own homebrew for these signals,
do you use them as a refclock for NTP?

Thank you


-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
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Re: [time-nuts] HP 10544A Repair

[Nigel Vander Houwen]

Mark,

I don’t see that referenced in the documentation, and the frequency adjustment 
pot appears to be plastic, but I will compare a non-conductive tool, to a 
conductive one to see if it makes a difference.

Nigel

> On Feb 27, 2016, at 19:11, Mark Sims  wrote:
> 
> Also, when messing with a 10544A be aware that  that the frequency tuning 
> adjustment must be made with an insulated tool.   
> 
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Re: [time-nuts] Inside a CTS 1960017 OCXO

[Rob Sherwood .]

I would have to make the measurement again with the HP supply off.
I have measured my Rubidium and my GPSDO and never seen anything like this 
spectra of close-spaced spurious. 
I'll send you some more data direct.
Rob
NC0B


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray
Sent: Saturday, February 27, 2016 3:32 PM
To: Discussion of precise time and frequency measurement
Cc: hmur...@megapathdsl.net
Subject: Re: [time-nuts] Inside a CTS 1960017 OCXO




r...@nc0b.com said:
> I cannot say exactly, as I measured it as 59 Hz.  VA7OJ measured it as 
> 60 Hz.  I was using an HP lab supply, and Adam was using some other lab 
> supply.
>  I put a 500 uF capacitor across the Vcc pin and it had no effect.  I 
> don't think it has anything to do with the power supply since both of 
> us saw the same thing. ...

How much line noise is floating around the lab?  What does the spectrum 
analyzer see if you power off the DUT?




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