[time-nuts] Reminder -- upcoming list changes

[John Ackermann N8UR]

Just a reminder that starting this Friday, June 15, postings to the 
febo.com mailing lists will need to use the new addresses -- 
@lists.febo.com instead of @febo.com.  You can start using the new 
addresses now.


The list server will be shut down for an hour or two on Friday to make 
the configuration change.


The transition to the new server will happen over the June 30 weekend -- 
the server will be shut down on Saturday, June 30, so the data can be 
moved to the new provider.  The lists should be back up no later than 
Tuesday, July 3.


By the way, if it wasn't clear in my other message -- after the move, 
the lists will still operate just as they did before, with the same 
administrators and moderators.


John
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[time-nuts] febo.com Mailing List Changes

[John Ackermann N8UR]

Some of you may know that febo.com lives on leased hardware at a data 
center.  That hardware is now at its end of service life, which means it 
won't be supported if it breaks.  After pondering the options for a 
replacement, I've decided that it's time to move away from dedicated 
hardware toward cloud-based services, and to offload some of the 
sysadmin responsibilities to people who know what they are doing.


As part of that, the febo.com mailing lists will be moving to a new list 
hosting provider.  I'm working to make the transition as seamless as 
possible.  You will not need to resubscribe to the mailing lists, or 
change any list settings.  The lists will continue to use the Mailman 
software and web interface, and will work just as they have been.


However, the address for posting messages will change.  Instead of 
sending to, for example, "time-nuts@febo.com" you'll now send to

"time-n...@lists.febo.com" -- just adding "lists." to the domain.

The new addresses should be working now.  On June 15, the old addresses 
will stop working; all postings after that date need to be to

@lists.febo.com.

Around July 1, the lists will move to the new hosting company.  We will 
probably turn the lists off for a day or two during that transition, and 
I'll send a note when that is about to happen.  When the lists come 
back, you should see no further changes.


A note about the list archives, which have been accessible by going to, 
for example, "https://www.febo.com/pipermail/time-nuts;, and which 
Google does a pretty good job of indexing.  Going forward, the archive 
URL will change as well, using the lists.febo.com domain.  That may 
impact search results until Google indexes the new site.  I'll maintain 
the existing archives as of the cutover date at the old URL to mitigate 
the problem.  Between June 15 and July 1, archive access may be a bit flaky.


This change will improve the reliability of the mailing lists, and 
remove several single points of failure.  It should allow the lists to 
continue indefinitely into the future.  I hope that the transition 
doesn't cause you too much inconvenience.  If you have any questions or 
concerns, please contact me directly at j...@febo.com.


John Ackermann
Your SysAdmin
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Re: [time-nuts] Possible new run of TNS-BUF High Isolation, Low Noise Buffer Amp boards

[John Ackermann N8UR]

Good news -- we had enough orders to justify doing a small production 
run of the TNS-BUF isolation amplifiers.  We'll be placing the order 
with our contract manufacturer this week, and expect delivery in six to 
eight weeks.


There will be a few extra boards available, so if you haven't ordered 
yet, there's still time.


John


On 05/08/2018 03:09 PM, John Ackermann N8UR wrote:
Back in October, 2016, TAPR did a build-to-order offering of the TNS-BUF 
low noise, high isolation buffer amplifier.  The original 2016 post is 
attached below.  All of those units sold out, and recently I've had a 
few questions about whether more will be available.


TAPR will do another one-off production run if we can get orders for at 
least 25 boards (the minimum to make manufacturing viable) by *June 1*. 
You can place an order by going to http://tapr.org/kits_tns-buf.  The 
price will be the same as the previous production -- $119 plus shipping.


If we receive orders for at least 25 boards by June 1, we will charge 
credit cards and place the production order with our contract 
manufacturer.  If we don't get 25 orders, we'll cancel the project and 
your card will not be charged.


We expect to ship finished TNS-BUF boards about 60 days after placing 
the production order.


Best regards,
John

 Forwarded Message 
Subject: [time-nuts] TNS-BUF High Isolation, Low Noise Buffer Amp Available
Date: Wed, 5 Oct 2016 10:15:46 -0400
From: John Ackermann N8UR 

I've previously mentioned a high performance buffer amplifier called the 
"TNS-BUF" that I built based on a design by Dr. Bruce Griffiths with 
further input from John Miles. Key numbers are:


*  Phase noise -140dBc/Hz at 1 Hertz offset, noise floor -175dBc/Hz.
     (PN plot attached)
*  Reverse isolation greater than 100dB; low enough that I can't make a
     trustworthy measurement.
*  Gain from -10 to +7 dB from 1 to 30 MHz; maximum output >18dBm.
*  Nominal 18VDC operation, but works down to 12V with lowered
     maximum output level.

There's information, including performance data and schematic, at
http://www.febo.com/pages/TNS-BUF

There seems to be some interest in an amplifier like this, so TAPR has 
decided to do a limited production run.  The amp is built with surface 
mount parts, so we thought an assembled and tested board was better than 
a kit.  The price will be $119 each.  But we have no idea how much 
interest there is, and we need to build a minimum of 25 units to make 
production feasible.


So, here's the deal:  you can order your TNS-BUF at

http://tapr.org/kits_tns-buf

through *October 20*.  If we receive orders for at least 25 boards by 
then, we will charge credit cards and place the production order with 
our contract manufacturer.  If we don't get 25 orders, we'll cancel the 
project and credit cards will not be charged.  There's no guarantee that 
boards will be available for later order.


We expect about 60 days between placing the manufacturing order and 
receipt of the boards at TAPR.  We'll ship to customers ASAP after 
receipt.  So that means you can expect to receive your order shortly 
after January 1.


So, go to http://tapr.org/kits_tns-buf now to place your order before 
the deadline!


John




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[time-nuts] A Request to the List

[John Ackermann N8UR]

TVB is traveling and not on-line as much as usual, so in his absence I'm 
going to ask everyone to please consider his request a couple of weeks 
ago to think before you post.


Please keep in mind that time-nuts isn't a chat room, and that every 
message doesn't require an individual response.  It's much better to 
have one thoughtful post than a dozen written on the fly.


Remember that 1800 "new message" flags go up each time you post.

Thanks,
John
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[time-nuts] Possible new run of TNS-BUF High Isolation, Low Noise Buffer Amp boards

[John Ackermann N8UR]

Back in October, 2016, TAPR did a build-to-order offering of the TNS-BUF 
low noise, high isolation buffer amplifier.  The original 2016 post is 
attached below.  All of those units sold out, and recently I've had a 
few questions about whether more will be available.


TAPR will do another one-off production run if we can get orders for at 
least 25 boards (the minimum to make manufacturing viable) by *June 1*. 
You can place an order by going to http://tapr.org/kits_tns-buf.  The 
price will be the same as the previous production -- $119 plus shipping.


If we receive orders for at least 25 boards by June 1, we will charge 
credit cards and place the production order with our contract 
manufacturer.  If we don't get 25 orders, we'll cancel the project and 
your card will not be charged.


We expect to ship finished TNS-BUF boards about 60 days after placing 
the production order.


Best regards,
John

 Forwarded Message 
Subject: [time-nuts] TNS-BUF High Isolation, Low Noise Buffer Amp Available
Date: Wed, 5 Oct 2016 10:15:46 -0400
From: John Ackermann N8UR <j...@febo.com>

I've previously mentioned a high performance buffer amplifier called the 
"TNS-BUF" that I built based on a design by Dr. Bruce Griffiths with 
further input from John Miles. Key numbers are:


*  Phase noise -140dBc/Hz at 1 Hertz offset, noise floor -175dBc/Hz.
(PN plot attached)
*  Reverse isolation greater than 100dB; low enough that I can't make a
trustworthy measurement.
*  Gain from -10 to +7 dB from 1 to 30 MHz; maximum output >18dBm.
*  Nominal 18VDC operation, but works down to 12V with lowered
maximum output level.

There's information, including performance data and schematic, at
http://www.febo.com/pages/TNS-BUF

There seems to be some interest in an amplifier like this, so TAPR has 
decided to do a limited production run.  The amp is built with surface 
mount parts, so we thought an assembled and tested board was better than 
a kit.  The price will be $119 each.  But we have no idea how much 
interest there is, and we need to build a minimum of 25 units to make 
production feasible.


So, here's the deal:  you can order your TNS-BUF at

http://tapr.org/kits_tns-buf

through *October 20*.  If we receive orders for at least 25 boards by 
then, we will charge credit cards and place the production order with 
our contract manufacturer.  If we don't get 25 orders, we'll cancel the 
project and credit cards will not be charged.  There's no guarantee that 
boards will be available for later order.


We expect about 60 days between placing the manufacturing order and 
receipt of the boards at TAPR.  We'll ship to customers ASAP after 
receipt.  So that means you can expect to receive your order shortly 
after January 1.


So, go to http://tapr.org/kits_tns-buf now to place your order before 
the deadline!


John


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Re: [time-nuts] WWVB: measuring local 60 KHz noise

[John Ackermann N8UR]

Long ago I did some WWVB signal-to-noise measurements with an HP 3586C 
selective voltmeter (commonly used by the FMT-nuts).  I measured the signal 
power at 60.0 kHz with 20 Hz bandwidth.  Then I measured the power a small 
offset plus and minus  (100 Hz?  I don't recall), and took the mean of the two 
to get the noise power.  I used a voltage-probe antenna.  

Since all readings were taken with the same bandwidth I didn't bother 
normalizing to 1 Hz, and just used the dBm difference between the signal and 
mean noise as the result.  I took measurements every 5 minutes or so to capture 
the 24 hour cycle of SNR.

John

On May 6, 2018, 1:09 PM, at 1:09 PM, Charles Steinmetz <csteinm...@yandex.com> 
wrote:
>Hal wrote:
>
>> I assume the problem is noise.  Is there any simple way to measure
>the noise
>> around 60 KHz?  How about not so simple?
>>
>> Extra credit for a way that others nuts can reproduce so we can
>compare the
>> noise at my location with other locations.
>
>For any location near a city, the noise level (QRM and QRN -- mostly
>the 
>former unless there is storm activity within a few hundred km) is 
>shockingly high.  High enough to be clearly seen and measured with a 
>good spectrum analyzer.  So the *simplest* way (but not necessarily the
>
>cheapest, depending on what is in your lab already) is to use a good 
>spec an with noise integration over the band of interest (e.g., HP
>3585A 
>or B).  You get noise density readings in volts per root Hz.  Divide by
>
>the antenna length and you have volts per root Hz per meter.
>
>Lacking a suitable spec an, any receiver with a reasonably narrow rx
>B/W 
>and a calibrated, input-referred detector can be used.  Wave analyzers 
>(frequency-selectable voltmeters, e.g., HP 3586) are good candidates,
>as 
>are some commercial receivers with calibrated "S" meters (e.g., Ten-Tec
>
>RX340).  It would also be pretty easy to design a simple "sniffer"-type
>
>receiver (input op-amp, active filter, logarithmic detector feeding a 
>standard 1mA meter movement) that could be calibrated by design from 
>first principles and that everyone interested could build for, perhaps,
>
>$25-30.
>
>In the suburbs of a fairly large US city with aerial electric service,
>I 
>generally see noise densities measured in tens to hundreds of uV per 
>root Hz per meter below 100kHz.  In other, similar locations I have
>seen 
>as much as hundreds of mV or more per root Hz per meter.  It depends on
>
>local factors (whether the electric service is buried or aerial, how 
>well the power utility maintains its equipment, how far away the
>nearest 
>industrial neighborhood is, how far between dwellings, how much noisy 
>technology the neighbors use, etc, etc.).
>
>In order to compare with others, everyone needs to use the same
>antenna. 
>  There are lots of possibilities, but for the sake of universality I 
>recommend a 1m vertical whip.  Everyone can make one of those.
>
>Note that this sort of antenna is NOT the best type to minimize
>received 
>noise and maximize received S/N ratio.  For that, you generally want a 
>balanced, shielded loop.
>
>Best regards,
>
>Charles
>
>
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Re: [time-nuts] Austron 2100 LORAN C manual I have a pdf!

[John C. Westmoreland, P.E.]

Hello Paul,

I wanted to say 'Thanks' - I downloaded that recently.

I'm obviously interested in any Austron schematics; manuals; references;
datasheets... .

73's,
John
AJ6BC


On Thu, Jul 30, 2015 at 9:46 AM, paul swed <paulsw...@gmail.com> wrote:

> In looking at the threads and putting away the Austron catalog I realized I
> have a 2100 pdf with schematics.
> Its 8.9 MB so will send it to the Diddiers KO4BB site tonight.
> Regards
> Paul
> WB8TSL
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Re: [time-nuts] 4046 replacement

[John Miles]

> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of
> donald collie
> Sent: Wednesday, April 18, 2018 2:40 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 4046 replacement
> 
> Thankyou Attila. I remember reading a book on PLL theory, recently,writen
> by a very knowledgable fellow, but I didn`t think to make a copy of his
> critique of the 4046. I recall that the nub of it was that the 4046 isn`t
> suitable for some applications because of a design flaw. Perhaps somebody
> in this group could explain further.
> Thankyou Bill, for the datasheet on the 74HCT9046, and your comments
> Cheers!..Don
> jnr ZL4GX

The tristate phase/freq comparator in the original 4046 had a dead-band problem 
that caused its gain to vary widely as it approached its normal operating point 
in a stable loop.  This wasn't so much a 'bug' as it was a consequence of the 
fact that there's effectively no gain when there's no phase error to correct.  

Ulrich Rohde's book indicates that this problem was first documented in 1978 in 
an EDN article by some authors named Egan and Clark.  Newer PFDs implement the 
'antibacklash' logic that Rohde mentions.  If you really must use a 4046, I'd 
look for a newer version whose data sheet explicitly addresses this problem.  
Better still, use a newer part.

Another workaround is to force the PFD to stay out of its dead zone by loading 
the output lightly, e.g. with a 1M resistor.  You can never compensate for this 
effect perfectly, though.  You can probably expect some downsides like worse 
reference suppression.  

-- john, KE5FX
Miles Design LLC

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Re: [time-nuts] femtosecond jitter

[John Larkin]

On 4/15/2018 2:17 PM, Magnus Danielson wrote:

Hi,

On 04/14/2018 06:45 PM, John Larkin wrote:

Hi, Magnus,

We did a little PC board that has two Analog Devices CML comparators
that feed the flop.

   https://www.dropbox.com/s/05ti1c57eush0uq/99S394A.pdf?dl=0

An external DAC tweaks the VBIAS voltage to slew the edge times across
one another, and an external ADC looks at the averaged flop outputs. The
jitter noise floor is probably dominated by the test signals, not the
flop under test.

Ah, thanks. Much clearer now!

You more tweak the voltage than actual timing, it's the slope property
that does the timing, but interesting never the less.


Downstream of the comparators, all the flop sees is time... not voltage 
shift. We used a sampling scope to calibrate the picoseconds-per-volt 
slope of the voltage input from the DAC.



--
** arb

John Larkin, President
Highland Technology, Inc
18 Otis Street
San Francisco, CA 94103

phone 415 551-1700   fax 551-5129
jjlar...@highlandtechnology.com
http://www.highlandtechnology.com

This is a Highland Technology confidential communication

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Re: [time-nuts] femtosecond jitter

[John Larkin]

Hi, Magnus,

We did a little PC board that has two Analog Devices CML comparators 
that feed the flop.


  https://www.dropbox.com/s/05ti1c57eush0uq/99S394A.pdf?dl=0

An external DAC tweaks the VBIAS voltage to slew the edge times across 
one another, and an external ADC looks at the averaged flop outputs. The 
jitter noise floor is probably dominated by the test signals, not the 
flop under test. We considered something like a micrometer-driven 
differential trombone line... note that 1 fs is one PPM of a nanosecond, 
how far light travels in 12 micro-inches.


The quantization is probably DAC resolution. The step function is just 
the integral of the histogram.


This is going into a test set that needs maybe 1 ps RMS noise floor, so 
this flop is hugely better than what we need. It's a big deal to set 
this up, so I don't think we'll do any more measurements.


As a bang-bang phase detector, with some lowpass filtering in the loop, 
this flop would have a noise floor in the attosecond range. You're 
right, temperature will dominate low-frequency noise, and not just in 
the flop.


John


On 4/14/2018 5:59 AM, Magnus Danielson wrote:

John,

How where these measurements done?
Also, it looks like you have a systematic component in there, about 80
fs guestimating from the plot creating essentially two tracks up the
slope that is the tell-tale of a sinuoid phase modulation of some source.

Considering the temperature stability that you nicely plotted as a
quadratic shape, it seems like a good thermal stability is needed, which
comes as no big chock.

Can do you do a longer measurement and accumulate the data in a
2D-histogram fashion? That is count occurrences for the amplitude/time
position and then color code it accordingly? That have proved to be a
good tool for analysis.

Cheers,
Magnus

On 04/13/2018 05:54 PM, John Larkin wrote:

If you walk the differential data and clock inputs of an NB7V52  CML
flipflop across one another in time, the equivalent jitter is below 20
fs RMS. That's what we're measuring, but our test rig may well dominate
the jitter, so the flop is probably better.

We're using this to test the jitter of some of our timing products, with
1/10 the noise floor and 1e-4 times the cost of other ways to do it.

https://www.dropbox.com/s/1i2yz7otty94o9l/NB7_Jitter_1.jpg?raw=1

https://www.dropbox.com/s/qahpb8uh1xr53vj/NB7_Steps.jpg?raw=1

https://www.dropbox.com/s/tpphhi79yxgzy34/NB7_tc.jpg?raw=1



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--
** arb

John Larkin, President
Highland Technology, Inc
18 Otis Street
San Francisco, CA 94103

phone 415 551-1700   fax 551-5129
jjlar...@highlandtechnology.com
http://www.highlandtechnology.com

This is a Highland Technology confidential communication

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[time-nuts] femtosecond jitter

[John Larkin]

If you walk the differential data and clock inputs of an NB7V52  CML 
flipflop across one another in time, the equivalent jitter is below 20 
fs RMS. That's what we're measuring, but our test rig may well dominate 
the jitter, so the flop is probably better.


We're using this to test the jitter of some of our timing products, with 
1/10 the noise floor and 1e-4 times the cost of other ways to do it.


https://www.dropbox.com/s/1i2yz7otty94o9l/NB7_Jitter_1.jpg?raw=1

https://www.dropbox.com/s/qahpb8uh1xr53vj/NB7_Steps.jpg?raw=1

https://www.dropbox.com/s/tpphhi79yxgzy34/NB7_tc.jpg?raw=1


--
** arb

John Larkin, President
Highland Technology, Inc
18 Otis Street
San Francisco, CA 94103

phone 415 551-1700   fax 551-5129
jjlar...@highlandtechnology.com
http://www.highlandtechnology.com

This is a Highland Technology confidential communication

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[time-nuts] Dual GPSDO - any advantage?

[John Green]

With regard to two GPSDOs, it is an interesting experiment. I have two
Tbolts, both 2.2 firmware, both fed from the same antenna, both with
factory default settings, and I see differences. They are about 2 feet
apart on my bench and everything is pretty stable, +/- 20 nS or so until
the heat kicks on. Then, the time difference between the two 10 MHz outputs
goes wild. Go figure.
Regarding eBay and deadbeat sellers, they are much better than in the past.
I got ripped off by an unscrupulous seller some years ago and eBay just
told me they had closed their eBay account. Today, If I don't get my item
fairly fast, I file a complaint right away. An unscrupulous seller will try
a delaying tactic to get you to wait until the time for eBay to do anything
has run out.  I had an issue with a Chinese seller once and PayPal told me
they couldn't issue a refund because they didn't have access to the
seller's bank account.
Yeah, sure. The worst abuse I have heard of by eBay/PayPal was a case where
a local guitar store owner sold a rather expensive, $4,000 + guitar to
someone in England. He got paid, then a few days later, he got an email
from eBay saying that the buyer had reported the item as fake and destroyed
it. They took the money back out of his bank account and wouldn't listen to
anything he had to say. Yes, there are unscrupulous buyers too.
Oh, I ordered one of those $9.50 GPSDOs too. I doubt I will ever see it. I
am not too optimistic about getting my money back either. We'll see.
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Re: [time-nuts] Wavecrest DTS2075

[John Ackermann N8UR]

It's more a burst-mode and averaging analyzer like the HP 5371/5372.  But it 
can do sustained time interval measurements if you mess around enough with the 
settings.  And the resolution is down in the very low picoseconds.

But it's big, awkwardly shaped, and has a jet turbine fan.

John

On Apr 10, 2018, 6:00 PM, at 6:00 PM, Bruce Griffiths 
<bruce.griffi...@xtra.co.nz> wrote:
>Its more accurate and has less measurement noise than the SR620.
>
>The input bandwidth is also greater.
>
>The accuracy is no better than that of a modern TDC chip, however its
>measurement noise is lower.
>
>Bruce
>
>> 
>> On 11 April 2018 at 07:17 Gerhard Hoffmann <dk...@arcor.de>
>wrote:
>> 
>> I have been offered a DTS2075. Is this generally regarded as a
>step
>> 
>> forward if you already have a SR620 or is it more or less the
>same
>> 
>> league? Are there any hidden pearls or caveats?
>> 
>> TIA and best regards,
>> 
>> Gerhard
>> 
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Re: [time-nuts] Cheap jitter measurements

[John Hawkinson]

Tom Van Baak <t...@leapsecond.com> wrote on Sun,  8 Apr 2018
at 12:36:52 -0700 in <55EB8D26CCDC4B1ABFBC53F95E4C0557@pc52>:

> My mental model of a black box computer running NTP
...
> Imagine the black box has two BNC connectors; one accepts an input
> pulse to be timed; one outputs a pulse at certain times.

Theory runs into reality. The problem is that NTP is easy to set up to do the 
former, and hard to set up to do the latter. Where "easy" means "it's commonly 
done" and "hard" means "I'm not aware that it's ever done" (not that I'm so 
expert that I would necessarily know if it were).

> To me this better than relying on NTP to tell you how NTP is doing,
> which as far as I can tell from live plots on the web, is all that
> most people do. Instead use real, external, physical
> measurement. The internal NTP stats are fine for tracking the
> performance of the PLL, but don't confuse that with actual timing.

One of the things that NTP does is it reports on its status with respect to 
other NTP peers. Yes, this is still "internal" to the "NTP universe," but it's 
also external to the device you have in front of you.

For instance, my ntp server currently reports that it is offset between .6 and 
2.1 millisecon
ds from 7 ntp peers it is talking to, and there's at least some reason to think 
these are not particularly correllated. That gives me reason to infer that my 
server's clock is probably not off by more than a few milliseconds. (This is 
not sub-ns timing, of course. It's intended to be illustrative. And for a 
variety of reasons this particular server's network connection is a bit 
unstable, so most NTP users can probably do a lot better.)

Yeah, that's not truly reliable, like I was comparing it to a truly external 
reference, but it's also not as meaningless as staring at internal parameters.

Indeed, one way in practice that ntp people measure ntp is to wire up an 
external reference to the "input BNC" of your black box, instruct the ntp 
server to monitor that PPS input but not use it in the clock monkeying 
algorithm, and then compare what NTP reports for the local clock with what it 
reports for other NTP peers. 

--jh...@mit.edu
  John Hawkinson
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Re: [time-nuts] Cheap jitter measurements

[John Ackermann N8UR]

I want to jump on Tom's post, and Bob's note at 1:14 on Saturday (that 
begins with "Just to be very clear..."  They both raise an important 
point about measurements.


With both NTP and GPSDO measurements a lot of folks focus heavily on 
what the "black box" is reporting about itself.  But self-contained 
measurements are really unrelated to actual performance.


As Bob mentioned, in a GPSDO you can look at tempco, humidco, voltageco, 
and all sorts of other things but the overall point of the system is to 
make those meaningless: the control loop(s) compensate for them.  If 
those internal error generators are reduced, it may make the system's 
work easier, but that improvement will have no effect on the quality of 
the output if the control loop is already properly compensating for it.


And in NTP, the software reports all sorts of interesting measurements, 
but none of them really tell you how close the computer's clock is to a 
local reference.  As Tom said, the real test is how the time tick coming 
out of the box compares with the time tick going into it.


The bottom line is that no self-contained measurement can tell you 
actual performance.  The *only* way to do that is to compare your box 
with an external reference whose error bounds are known.


After all, this is why we're time-nuts -- every time you acquire a 
clock, you also need to acquire a better clock to test it with. :-)


John

On 04/08/2018 03:36 PM, Tom Van Baak wrote:

What do you mean by "jitter" and what do you really want to do?

I mean jitter as NTP defines jitter.  Whatever that is.


I think you need to figure out what you want to do so you don't fool yourself.

ntpd is a PLL.  There is a low pass filter in the control loop.  It will
track the low frequency wander of the source.


Gary, Hal, Leo,

My mental model of a black box computer running NTP is that I should be able to 
give it a pulse (e.g., via parallel, serial, GPIO) and it tells me what time it 
was. Use a GPSDO / Rb / picDIV to generate precise pulses. Compare the known 
time of the pulse with the time the box says it was. Repeat many times, collect 
data, look at the statistics; just as we would for any clock.

Similarly, the box should be able to give me a pulse at a known time. In this 
case it records the time it thinks the pulse went out, and your GPSDO / Rb / 
TIC makes the actual measurement. Again, collect data and look at the 
statistics; just as we would for any clock.

Imagine the black box has two BNC connectors; one accepts an input pulse to be 
timed; one outputs a pulse at certain times. This allows a complete analysis of 
NTP operation. Should be true for both client or server. If you get down to 
nanosecond levels make sure to use equal length cables.

To me this better than relying on NTP to tell you how NTP is doing, which as 
far as I can tell from live plots on the web, is all that most people do. 
Instead use real, external, physical measurement. The internal NTP stats are 
fine for tracking the performance of the PLL, but don't confuse that with 
actual timing.

So this is why I'm excited to hear Gary wants a Rb timebase and a sub-ns 
counter. Someone will finally measure NTP for real, not rely on the internal 
numbers of NTP measuring itself. Or at least I hope that's what Gary is up to.

/tvb

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[time-nuts] Tbolt temperature sensitivity.

[John Green]

I don't use what LH says about temperature. I compare the 10 MHz output to
something else. With two Tbolts sitting about 2 feet apart on my bench,
both fed from the same antenna, both with factory settings, when the heat
kicks on, I see a change in the difference between the two. Comparing a
Tbolt to another, different GPSDO, the effect is even greater. Next step is
to compare the Tbolt to a rubidium source that has been adjusted to match
the Tbolt as closely as possible at a stable temperature. I suppose you
could say the the Tbolt stays *locked* to GPS since the difference never
gets to 100 nS, meaning they are always within 1 Hz. What I usually see
when comparing the Tbolt to another, different model GPSDO is that the time
difference between the two 10 MHz signals slips at a fairly constant rate,
going from zero past 100 nS, and then through zero, over and over. I also
tried comparing the 1 PPS and the time jumped around quite a bit. Since I
plan to actually use 10 MHz instead of 1 PPS, I decided to quit looking at
1 PPS.
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Re: [time-nuts] QRZed.... OT: 16 Khz VLF, Rugby, England

[John Green]

Fascinating! Thanks for posting.

On Fri, Apr 6, 2018 at 7:19 AM, D. Resor  wrote:

> I am sure some have seen this, however.
>
> 16 Khz VLF, Rugby, England
>
> https://www.youtube.com/watch?v=Unlg2gY2Zrs
>
>
>
>
>
>
>
> Donald R. Resor Jr. T. W. & T. C. Svc. Co.
>
> http://hammondorganservice.com
> Hammond USA warranty service
> "Most people don't have a sense of humor. They think they do, but they
> don't." --Jonathan Winters
>
>
>
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Re: [time-nuts] Environmental sensor recommendations.

[John Green]

Why has no one mentioned thermocouples?
I had some experience with thermistors a few years back designing thermal
attenuators and equalizers for CATV. NTC thermistors can have a large
change of resistance for a unit change in temperature. They aren't linear,
but there are formulas for computing resistance vs temp. PTC thermistors
have a much smaller change per unit change in temp., but are much more
linear. And, they are susceptible to self heating, which makes things
interesting. If I remember correctly, in my research something called an
RTD was supposed to be the king when it came to accuracy and repeatability.
As someone else has stated, the IC devices are supposed to be quite good,
but you have to interface with them.
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Re: [time-nuts] TV Signals as a frequency reference

[John Marvin]

Yeah, that's pretty much the story around the country. I also have some 
monitoring software (monitoring PSIP, video and audio data, not 
specifically for monitoring STT packets) that I run on the Denver and 
Cheyenne stations 24 hours a day. Very few have set their GPS-UTC offset 
to 18 seconds.  None are set to 0 though. The values range from 14 to 
18. Almost half of the stations are within 1-2 seconds of the actual 
time (when taking their mostly wrong GPS-UTC offset into account). But 
some are 10's of seconds off, some are 10's of minutes off, and one is 
about an hour off, and another about 5 hours off (currently).


The amazing thing is that every once in a while, some stations make a 
"correction". Sometimes it is to bring their error back down close to 
zero.  But some appear to make large changes in the wrong direction, 
e.g. -88 seconds to -195 seconds. Looks like some stations have someone 
setting the time based on their watch (if I had to guess), which is 
really off.


Doesn't give me much hope that the ATSC 3.0 standard will be implemented 
any better, given that the FCC has taken an even more hands off approach 
to this transition than the transition from analog to digital. I highly 
doubt we'll see many channels doing over the air 4K transmissions, i.e. 
they'll just use the better compression to stuff more crappy subchannels 
into their signal. But I'm getting pretty far away from time nuttery 
here, so I'll stop now.


John

On 4/2/2018 11:15 PM, Mark Sims wrote:

Here's a local guy's take on monitoring time and DST errors on the stations in 
the Dallas area:
http://home.earthlink.net/~schultdw/atsc/
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Re: [time-nuts] Ultralink

[John Ackermann N8UR]

Hi Brooke --

Yes, all the chips on the board are low power devices.  I'm measuring 
the receiver as drawing 0.9 MA at about 2.3 volts.


Update -- I moved the receiver and farted around with the wiring, and 
now the S-Meter is off the peg, responds to orientation changes, and I 
actually got a couple of indications of bits being decoded.  So, I think 
the hardware is working fine.


However, there must be a lot of local interference as decoding is very 
erratic and I'm nowhere near getting a full sequence.  I don't have any 
experience at this location with WWVB reception, so I'm not sure what to 
expect.  At my previous Ohio house a mile south of here the signals were 
very good and there were no noticeable problems with the Spectracom 
receivers (may they rest in peace).  Next step is to experiment with 
receiver placement.


John

On 03/30/2018 03:15 PM, Brooke Clarke wrote:

Hi John:

The U4226B chip operates at very high impedance levels in order to 
minimize battery drain in its main application, battery powered clocks.

So some sort of buffer is needed on all the output pins.

The 333 model, with the analog meter, was made for the folks working for 
WWVB as a way for them to know the transmitter was on the air.

http://www.prc68.com/I/timefreq.shtml#WWVBrcvr
http://www.prc68.com/I/Loop.shtml (WWVB)


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Re: [time-nuts] Ultralink

[John Ackermann N8UR]

On 03/30/2018 03:39 AM, Hal Murray wrote:


t...@leapsecond.com said:

I updated http://leapsecond.com/museum/ulio/ with more manuals, and many
exterior / interior photos of the 301 module.


Thanks. My 301 says it is a 30TH Rev-A - mostly through hole parts.  Same
layout.


Mine is the same.  Circuit is very simple.  The 20 pin IC is the U4226B 
receiver chip and it has two external 60 kHz filter resonators.  The 8 
pin DIP is a TLV2770C op amp which seems to be a buffer to drive the S 
meter from the very high impedance AGC test point on the receiver chip. 
And I am guessing that the 2N3904 transistor is a buffer for the time 
code output.


The modular cable connecting the receiver to the decoder is wired 
straight through, not reversed as most telephone cables are.  My fear is 
that someone (like me) might at one point have used a reverse cable and 
thus put reverse polarity on the board; I don't see any reverse power 
protection.


Later today I'll tap into the four conductors on the cable and see what 
signals I see on them, and also look for signs of life on the receiver chip.


BTW -- Donald Resor pointed me to UTSource which shows several Chinese 
vendors as having them in stock.  I get nervous about whether they are 
the real thing or not, but will probably order a couple just in case. 
The chip is a 20 pin TSSOP package, which isn't too hard to rework but 
before putting hot air on the receiver board there are one or two 
surrounding parts one would want to remove to avoid collateral damage.


John
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Re: [time-nuts] Ultralink WWVB receiver manuals?

[John Ackermann N8UR]

Thanks to another list memo, I got the basic manual.  Got it fired up 
and while it does things, I think there's a problem.  The S Meter is 
pinned all the way over to the right (very, very strong signal) and 
stays there no matter how I shield the antenna.  And I never see any 
decoded bits.  I hope the receiver chip (U4226B, unobtanium except from 
China) isn't shot.  Will do more testing when I get some cycles free.


It would be very nice to have a direct NIST time source in the lab 
again, complete with PPS output.


Thanks!
John


On 03/29/2018 05:55 PM, Tom Van Baak wrote:

Congrats on your acquisition. The Ultralink WWVB receivers are very nice. It 
should still work -- it's an AM subcode (not carrier phase) receiver. If you 
have more questions let me know. These modules were the darling of precise time 
at the turn of the century; before mobile phones, before GPS was affordable. 
Ultralink discontinued the product line within a few years when the market for 
WWVB-based timing dried up.

Manuals here: http://leapsecond.com/museum/ulio/

Good question on the cable. If you don't see it in the manual let me know; I'll 
dig out my cable and have a look. Note the inner 4 of 6 pins are Vcc, TCO, AGC, 
gnd.

/tvb

- Original Message -
From: "John Ackermann N8UR" <j...@febo.com>
To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com>
Sent: Thursday, March 29, 2018 8:57 AM
Subject: [time-nuts] Ultralink WWVB receiver manuals?



I just acquired an Ultralink WWVB timecode receiver -- more
specifically, model 301 receiver and model 333 decoder.

I'm looking for documentation on these guys.  Anyone have a manual
they'd be willing to share?

The key questions are really just two:  (a) is the 6P6C modular cable
connecting the receiver and decoder straight, or reversed, and (b) what
are the four DIP switches on the back of the 333 used for?

Thanks for any info.

John
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[time-nuts] Ultralink WWVB receiver manuals?

[John Ackermann N8UR]

I just acquired an Ultralink WWVB timecode receiver -- more 
specifically, model 301 receiver and model 333 decoder.


I'm looking for documentation on these guys.  Anyone have a manual 
they'd be willing to share?


The key questions are really just two:  (a) is the 6P6C modular cable 
connecting the receiver and decoder straight, or reversed, and (b) what 
are the four DIP switches on the back of the 333 used for?


Thanks for any info.

John
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Re: [time-nuts] Introduction, new list member, Ms Tisha Hayes, AA4HA

[John Ackermann N8UR]

The impedance mismatch with the A or B models is't a real issue unless you're 
doing precise amplitude measurements.  Lots of folks use them for FMT work 
without issues. There are adapters available or buildable to deal with the odd 
Telco connectors.

John

On Mar 29, 2018, 3:04 AM, at 3:04 AM, Ruslan Nabioullin <rnabioul...@gmail.com> 
wrote:
>On Wed, Mar 28, 2018 at 9:49 PM, Tisha Hayes <tisha.ha...@gmail.com>
>wrote:
>
>> Perry and I would make our pilgrimages to the Huntsville Ham Fest and
>> usually I ended up buying equipment from him. One of the items he
>sent my
>> way was an HP 3586B that I am finally beginning to put to use.
>>
>
>Hmm that measuring receiver model (diffs can be found in:
>http://www.militaryradio.com/manuals/HP/hp3586-a-b-c.pdf ) was
>apparently
>intended for testing and troubleshooting purposes for those ancient
>FDM-based POTS trunk systems, not as a general-purpose HF measuring
>receiver (the HP 3586C)---I'm not sure how well they would function as
>HF
>receivers for WWV and CHU following impedance adaptation (b/c it
>doesn't
>have a 50 ohm unbalanced interface).
>
>In my case, I supply my time transfer volunteers with the following
>setup:
>
>vertical antenna -> TVSS -> preamplifier -> military rackmount
>preselector
>-> military/intelligence rackmount parametric demodulator or HP 3586C
>->
>Xeon NTP server via soundcard
>
>with GNU/Linux daemon software which commands the preselector and
>demodulator via GPIB.
>
>Still, WWV/CHU-derived public NTP nodes are virtually nonexistent, and
>therefore there's a strong need for them, regardless of the
>sophistication
>of the receiver, due to the pitfalls of GNSS.
>
>-Ruslan
>
>-- 
>Ruslan Nabioullin
>Wittgenstein Laboratories
>rnabioul...@gmail.com
>(508) 523-8535
>50 Louise Dr.
>Hollis, NH 03049
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Re: [time-nuts] ULN regulator with more current capability than LT3042?

[John Miles]

> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of John
> Ackermann N8UR
>
> Reviving the conversation about superb voltage regulators, I am looking
> for one to run the analog and PLL bits of a high performance frequency
> synthesizer chip.
> 
> The current drain looks to be about 160-180 mA at 1.8 V, which is
> uncomfortably close to the limit for the LT3042 (200 mA).  The
> manufacturer's evaluation board uses a MAX8869, which appears to be
> nowhere in the LT3042's league, but will source 1 A.
> 
> Any recommendations for a 1.8 V regulator a little beefier than the
> LT3042, but with similar noise performance?

These days, the best RF synthesizer and clock generator chips include dedicated 
low-noise LDOs inside the package.  It's rarely worthwhile to use a quieter 
regulator than the manufacturer recommends, or one that's quieter than whatever 
is on their own demo board. 

One very nifty example is the LMK61E2, which I X-rayed a while back:
http://www.ke5fx.com/LMK61E2_30kVp_20s.png

The overall package is only about 1 cm square.  The synthesizer has its own 
die, while the input regulators and (presumably) their bypass caps are mounted 
directly above the Vdd input pad.  According to TI, the PSRR of the internal 
LDO that runs the analog section is better than 70 dB at offsets below 1 MHz.  
So you could even power it directly from a switcher, assuming you keep a leash 
on its harmonics. 

-- john, KE5FX
Miles Design LLC


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Re: [time-nuts] Looking for information on True Position GPSDO.

[John Green]

Mark,
Yes, I saw that. My main interest at the moment is just getting the thing
working properly. It isn't.

On Tue, Mar 20, 2018 at 11:39 AM, Mark Sims  wrote:

> When I dumped the flash rom from one of the TruePosition units, we found a
> couple of commands that seem related to OCXO learning.   They are discussed
> a little in the thread on EEVBLOG.
>
> 
>
> > If you *do* go swapping around OCXO’s (or whatever) on a GPSDO board,
> it’s very nice to be able to change the internal “magic numbers” to get the
> control loop running properly again.
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Re: [time-nuts] ULN regulator with more current capability than LT3042?

[John Ackermann N8UR]

Thanks, all.  I think I'll end up using the 3042 with pass transistor, 
partly for reasons of cost.  I have no idea whether paralleling two 
3042s would result in lower noise from the device, and there are already 
three or four fairly pricey chips on the board.


I appreciate all the info!

John


On 03/18/2018 06:43 PM, Charles Steinmetz wrote:

Tom wrote:


Run two in parallel for twice the current and less noise?


This is actually a better solution than using an LT3045, for two 
reasons.  First, as Tom noted, by paralleling two devices, the noise is 
reduced by sqrt 2 = ~1.4:


"Designed as a precision current reference followed by a high 
performance voltage buffer, the LT3042 is easily paralleled to increase 
output current, spread heat on the PCB and further reduce noise -- 
output noise decreases by the square-root of the number of devices in 
parallel."  [LT Journal of Analog Innovation, v25 n1 Apr 2015]. 
<http://www.linear.com/docs/46398>


Second, it reduces the dissipation of each regulator, so they run 
cooler.  And as LT says, it allows spreading the heat on the board (but 
it is not advisable to put them too far apart).


The primary disadvantage is that two 3042s cost about half again more 
than one 3045.  Also, board space may be a factor in some applications.


So, unless you are extremely tight on board space or the ~1.5x cost 
increase is prohibitive, two 3042s in parallel are a better solution 
than one 3045 if you are seeking the lowest noise possible.


Best regards,

Charles


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[time-nuts] RE; True Position GPSDO.

[John Green]

Thanks to all who replied. You pointed me to a wealth of good information.
Seems lately that I have been getting let down in my Google searches. I
didn't find any of the stuff you led me to, but I should have. Hmmm. it may
be because I have been using Ecosia for searches instead of actually using
Google. Whatever, I should have found that information without needing
help. But, I am glad I did have help. Thanks much.


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Re: [time-nuts] ULN regulator with more current capability than LT3042?

[John Ackermann N8UR]

Thanks, Bruce!!!

On 03/18/2018 04:19 PM, Bruce Griffiths wrote:

Use an LT3045, its the 0.5A version of the LT3042.

Bruce

On 19 March 2018 at 09:13 John Ackermann N8UR <j...@febo.com> wrote:


Reviving the conversation about superb voltage regulators, I am looking
for one to run the analog and PLL bits of a high performance frequency
synthesizer chip.

The current drain looks to be about 160-180 mA at 1.8 V, which is
uncomfortably close to the limit for the LT3042 (200 mA).  The
manufacturer's evaluation board uses a MAX8869, which appears to be
nowhere in the LT3042's league, but will source 1 A.

Any recommendations for a 1.8 V regulator a little beefier than the
LT3042, but with similar noise performance?

Thanks!
John
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[time-nuts] ULN regulator with more current capability than LT3042?

[John Ackermann N8UR]

Reviving the conversation about superb voltage regulators, I am looking 
for one to run the analog and PLL bits of a high performance frequency 
synthesizer chip.


The current drain looks to be about 160-180 mA at 1.8 V, which is 
uncomfortably close to the limit for the LT3042 (200 mA).  The 
manufacturer's evaluation board uses a MAX8869, which appears to be 
nowhere in the LT3042's league, but will source 1 A.


Any recommendations for a 1.8 V regulator a little beefier than the 
LT3042, but with similar noise performance?


Thanks!
John
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[time-nuts] Looking for information on True Position GPSDO.

[John Green]

There is a small, about 3.5" by 4.5", GPSDO board being offered by several
sellers on eBay. I bought one from what looks to be the only US based
source. It is identified as True Position, Inc., and had a small CTS OCXO
and Furuno GT8031 on board. I found hook up information in one of the Asian
vendor's ads. When it arrived, I hooked it up and waited for it to achieve
GPS lock. I left it over night, but it never locked. This morning, I sent a
message to the seller requesting to return it. I looked around on eBay to
see what the going price was and discovered that the US source was about
1/3rd the price of the Asian vendors. I also noticed in one listing where
the seller mentioned that it will not discipline the 10 MHz unless you
entered a command by RS232. If you buy one, he will tell you what the
secret command is. Does anyone, perchance happen to know the secret
command? And, would you be willing to share? This isn't a bad looking
little board. I was thinking of pulling the little CTS oscillator and
replacing it with something better. The fact that you have to tell it to do
its thing is something of a bummer, but I think I can live with it.


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Re: [time-nuts] While we are talking about Z3801's

[John Green]

When I removed it from storage, communication was gone. It took a very long
while to lock, but did so and maintained lock for a couple of weeks before
going into holdover. It then locked back for a while.
I definitely need to do more trouble shooting on it before I give up
completely. It was the best unit I have. I also have a couple of
Thunderbolts, but I don't consider them in the same class as the Z3801.
I see Z3801s for sale on eBay, but I am reluctant to buy one. They are at
an age where things are going to fail. Also, for my needs, a Thunderbolt
would suffice. I just like the Z3801 better and would really like to get it
going again.

On Sun, Mar 4, 2018 at 9:27 PM, Hal Murray  wrote:

>
> kb...@n1k.org said:
> > If still nothing, put a scope on the RX output of the serial chip in the
> > 3801. Do the same  for the TX input of the same chip.
>
> I think the Z3801A prints out a version string at power up.  Sometimes that
> helps debug the transmit path.
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] While we are talking about Z3801's

[John Green]

Hal, I can't communicate with it. That has been gone for a while now.

On Sat, Mar 3, 2018 at 9:05 PM, Hal Murray  wrote:

> > Mine has quit achieving lock.
> ...
> > After reading about someone else's trouble, i wonder if my OCXO has aged
> > out.
>
> Have you checked the status page?  Is the GPS unit seeing satellites?
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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[time-nuts] While we are talking about Z3801's

[John Green]

Mine has quit achieving lock. It goes back a ways. I had it in storage for
a while. When I got it out of storage, It took about 2 weeks to lock. It
would go into holdover sometimes for no reason I could ever discover. I
lost the ability to communicate with it. Then, one of the Lucent DC/DC
converters blew. After replacing that, it locked for a few days then
refused to lock again. In desperation, I changed out all the tantalum
capacitors with no effect. Next, I purchased a replacement Motorola GPS
receiver off eBay and tried that. Nothing. It has been back in storage
since. I plan on checking the 10 MHz output to see if it still has one and
to see just how far off it is. After reading about someone else's trouble,
i wonder if my OCXO has aged out.
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Re: [time-nuts] Time nut over from the old days

[John Franke]

I still use them, both the Bliley and James Knights versions. Especially like 
them for 100 KC crystals.

John Franke
WA4WDL

> On February 28, 2018 at 12:22 PM Pete Lancashire <p...@petelancashire.com> 
> wrote:
> 
> 
> https://photos.app.goo.gl/gIw4P1RQHPk2t4K33
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[time-nuts] Need Oncore connector info.

[John Green]

I need the part number of the connector that the Motorola Oncore series GPS
receiver plugs into.  Does anyone have that info at hand?
Thanks in advance.
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[time-nuts] Assorted replies, and request for info

[John Miles]

Request for data from an off-list friend who is looking for info on an Ovenaire 
OCXO and/or the instrument it was used in:

> Could you send a post on my behalf asking if anyone else has an 
> Ovenaire 42-15 or if not, a Spectracom 8131 Frequency Standard Oscillator. 

This is from Dennis Tillman, who can be reached directly at dennis (at) 
ridesoft.com.

> Fun fact -- there's a wide spur at ~2 Hz on the 5065A phase noise plot. What
> do you think that is? On a hunch I opened the front panel and reset the
> blinking amber battery alarm lamp, and voila, that noise went away. Makes
> sense when you think of the power variations associated with a blinking
> incandescent lamp.

I hadn't heard of that one, but some other examples include 1-pps crosstalk on 
the 10 MHz output of some of the HP GPSDOs (which I've run into myself), and 
the inadvertent ~5 MHz comb generator that drives the indicator LED on the HP 
5370's reference clock interface PCB that Bruce Griffiths noticed several years 
ago.  Presumably neither of these faux pas were bad enough to be noticed by the 
original designers or their paying customers, but they probably would have been 
fixed if they had come to the attention of the people involved.  Goes to show 
how improved instrumentation can be a curse as well as a blessing.

Poul-Henning's observation on the 5065A integrator cap highlights the risk of 
erring too far in the opposite direction:

> When I experimented, I could hardly find *any* property that mattered
> for that capacitor, not even the exact capacitance, because the
> adjustment procedue handles that.

I have a feeling this is true of most of the components in that circuit.  The 
nice thing about an integrator is that it's also a low-pass filter.  And the 
nice thing about a closed loop is that it's, well, closed.

Before spending too much time arguing about whether the opamp should be 
replaced with an LT1012 or an AD797 or a cryocooled tunnel diode or whatever, 
I'd suggest replacing it with a 741 and seeing how much *worse* the performance 
gets.  It is easier to measure the effect of that kind of change.  If there is 
little or no harm in using the crappiest opamp you can find, that means that 
you can safely stop worrying about what the best one might be.  

> One of the TimePods that I had access to in the past was particularly good
> at telling you it was sitting on top of a power transformer. It didn’t matter 
> a
> lot which instrument the power transformer was in. For some weird 
> reason it was a good magnetometer at line frequencies. I never bothered to 
> send it back for analysis. Simply moving it onto the bench top (rather than 
> stacked on top of this or that) would take care of the issue.
> 
> As far as I could tell, it was just the one unit that had the issue. None of 
> the
> others in the fleet of TimePods seemed to behave this way. Given that they
> normally are very good at rejecting all sorts of crud and ground loops, it was
> somewhat odd to see.

I've seen similar behavior here, not only with respect to units responding 
differently to 60/120 Hz magnetic interference, but also at higher offsets in 
the absence of an obvious coupling mechanism.  There was one case where a 
TimePod I was working with picked up an unstable low-level spur near 25 kHz 
from an LED aquarium light fixture several meters away.  Other units swapped 
into the same position did not show the spur at all, and I was never able to 
narrow down the cause with any certainty.  I don't have a good explanation for 
any of the above, unfortunately.

That being said, Phil Hobbs posted something on sci.electronics.design the 
other day that I thought was subtly insightful, even though he was just stating 
an obvious point.  Namely, ground loops are inherently very low impedance 
phenomena, often occurring in the milliohm range.  Especially when dealing with 
anodized aluminum hardware like the TimePod's enclosure, the difference between 
a test setup where all the coax shields act as a near-perfect shorted 
transformer turn versus one with significant loss might come down to small 
differences in fastener torque, or perhaps a missing star washer.  So it's 
possible to envision a scenario where tightening up all the proverbial loose 
screws actually makes a magnetically-coupled spur worse.  

Lifting a coax shield is usually not the best solution to ground loops, but 
Phil's offhand comment made me wonder about the effects of deliberately adding 
just a few ohms of series R.  It's on my list of things to look into when I 
have time.

-- john, KE5FX
Miles Design LLC


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Re: [time-nuts] Selling Time and Frequency Equipment

[John Miles]

> To echo Attila, just sayin.

$4000 is up there, but not outrageous IMO.  If you have a $4000 budget and 
don't actually need a primary standard, a well-kept 5065A is a good way to go.  
At taus less than a few hours they can outperform the best 5071As, even before 
Corby's mod is applied.  And they can be left powered on full time.

You can't do any better for the same money, put it that way.  5065As with the 
optical-filter mod are more appropriately compared to passive H-masers than to 
cesium standards.

-- john, KE5FX
Miles Design LLC


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Re: [time-nuts] Curious, how many t-nuts have 5065A

[John Miles]

> Hi
> 
> Well, if anybody else is “giving away” 5065’s I’d certainly be willing to
> “accept”
> one :)
> 
> Bob

Be careful what you wish for. :) The unit Pete is talking about is a 1969-era 
model, in nice overall shape but with the usual bad capacitors on the oven 
controller board.  The lamp oven winding should be about 50 ohms cold, but is 
closer to a dead short.  It will take a LOT of work to restore to working 
condition. 

The failed controller ran long enough to smoke a 1.5-ohm 1W resistor, 
1N400-something diode, and eventually the 1A line fuse ( 
http://www.ke5fx.com/5065A_A11_sm.jpg ).  Needless to say the lamp PCB looks 
like something out of Fukushima.  It'll need to be rebuilt from scratch after 
rewinding the heater.

Seriously -- anyone with a 5065A who hasn't checked/replaced the caps on A11, 
don't let this happen to you.  They aren't making any more of these puppies.  
If the caps on that board are original, don't bother to check them, just 
replace them, as Luciano suggests at http://www.timeok.it/hp5065a-corner-3/.  
No need for exotic parts, just put in whatever you have that is somewhere close 
to the original values.  

Not a bad idea to verify the ESR of the new parts you're installing as well.

-- john, KE5FX
Miles Design LLC


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[time-nuts] Chinese made eBay antenna breakdown.

[John Green]

I didn't mean to imply that all Chinese made products are garbage. But,
some of them are. And, has been said, that is because people want to pay
the absolute lowest prices for stuff. The company I recently retired from
has a long history with Chinese competition. We had a product that had but
one American competitor. We thought, foolishly, that being a low cost item
with a modest annual sales volume, he wouldn't have to worry about foreign
competition. We didn't take into account our main customer who would slit
your throat over a tenth of a cent. It wasn't long before we began seeing
competing products from China. At first, they either did what was cheapest
without regard for RF concerns, or they copied us exactly. However, in
recent years, I have seen Chinese products that show the result of some
real engineering talent. In some cases, they are better than ours. These
are parts that are molded in plastic, and the foreign competition certainly
knows a lot more about molding than we do. Their parts are cosmetically
superior to ours in almost every instance. Lately, I have suggested that we
obtain some of these products and copy them. That is what it has come to.
I noticed that the enable input is tied to the voltage input. I thought
that it may have seen too high a voltage, but the specs say it should be
able to take 20 volts. So, I don't really see any reason it should have
failed. I will put a new 3.3 volt regulator in and see if I can get it to
work. I want to do comparisons to other antennas. The rest of the circuitry
looks OK to me.
There is one SAW bandpass filter per band. Not like the Trimble, but should
work fine for my purposes.
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[time-nuts] Teardown of Chinese made eBay GPS antenna.

[John Green]

For those who have been following the saga of the Chinese made, eBay
purchased antenna that failed, I may have an answer as to why it failed.
I had to destructively disassemble it. I just could not get it apart any
other way. I used a Chinese version of a Dremel tool with a metal saw
blade. After making a huge mess with plastic particles everywhere, it
revealed a circular FR4 board with two patch antennas mounted, one atop the
other. I assume the smaller one to be the L1, and the larger to be L2. This
part looks almost identical to the Trimble Microcentered antenna I worked
on recently. On the back side of this is a metal shield  about 3 by 3
inches soldered to the circular FR4 board. I switched to a abrasive wheel
and took off some of the solder holding the shield to the board. Then,
using a small screw driver, I went around the shield breaking the solder
loose. The shield off revealed that the coax goes to some capacitors that
couple RF out and through an inductor with some capacitors to ground and
finally to a SOT23-5 package labelled LK33. This appears to be a Micrel
MIC5203 3.3 volt regulator. It is shorted on the input side. I believe that
putting anything over 7.5 volts on the input exceeded the power dissipation
rating and caused it to fail. I plan on wiring up a more robust 3.3 volt
regulator in its place and trying again. It looks like I will be able to re
solder the shield back. The watertight integrity is gone for good. I think
I can find a plastic box I can mount it in so I can at least experiment
with it. I have sent a message to the seller detailing my findings. The
Micrel part lists a 20 volt maximum input voltage, so in theory at least,
this might have worked, and there might be some of these out there that
don't fail.
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Re: [time-nuts] Furuno GT-8031 breakout board

[John Green]

Maek Sims wrote:  I have several Motorola compatible GPS receivers... and
not one of them does a perfect emulation of the Motorola devices.  Some are
quite close and not likely to cause problems... others are superiorly
craptastic.

Are there any readily available boards that will substitute for the
Motorola board in a Z3801?
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Re: [time-nuts] eBay GPS antenna test.

[John Green]

Bob wrote:  Hi

Just so people don’t get to down on eBay antennas:

I have gotten some deals on eBay I just couldn't have gotten elsewhere.
That is a nice looking antenna. A bit pricey for my budget. I thought just
north of $100 for a used Leica choke ring job was about it. The Trimble
antenna I got recently had issues, so I got it cheap and fixed the
mechanical problems. I think I have one of those HP timing antennas I have
heard mentioned here. I need to dig it up. I think I also have a PC Tel
model around somewhere. I still haven't gotten the top off that Chinese
made one that bit the dust at 12 volts. I need to get it apart somehow. I
think it can probably be repaired. I can at least let the seller know what
went bad.


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[time-nuts] eBay GPS antenna test.

[John Green]

Bob wrote:  Sitting here casually reading the data sheets for some of the
modern Trimble
survey receivers - they have gone to 7.2V (just below your 7.5V trigger
point)
as an antenna supply voltage.

Who knows what that might imply relative to this antenna.

After getting my refund, I sent the seller a message saying that I would
buy another if he could assure me it would work at 12 volts. He replied
that he needed to get his hands on a couple and do some testing first. The
antenna that I received seems to be different to the one pictured in the
eBay listing. At least the labels are different. I get the feeling he is
kind of a third party dealing with someone in China who is wholesaling
antennas made by someone else. Who really knows what spec. these are made
to, or by who. In my former place of employment, we made an SMB terminator.
Basically, a 75 ohm resistor soldered across the pins of an SMB connector,
then molded in black plastic. We bought the connectors from a Chinese
supplier who supplied them in individual plastic bags. We had to cut the
parts out of the bags before processing, which added a labor step. We tried
to get the supplier to sell them to us packaged in bulk, but they refused.
We decided that they were actually buying them from someone else and just
doing a passthru. The connectors themselves would change from time to time,
which caused problems in molding, and sometimes caused the electrical
performance to degrade. Getting parts to reliably meet a specification from
China can be a problem. I can't even imagine the issues that could arise
when you try to source an assembly, or completed product.


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[time-nuts] eBay GPS antenna test results.

[John Green]

They have issued a refund. The seller said that my antenna was defective.
This is kind of a strange outfit. They are in Russia selling Chinese goods,
shipped from China.  Since I don't have to return it, I will disassemble it
to see what went bad. I replied that if he could assure me that it would
work on 12 volts, I might order another.
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[time-nuts] eBay GPS antenna test results.

[John Green]

I opened a "Not as listed" case and heard back from the seller. They said
that the antenna is definitely 3.3 to 18 volts and have sold several that
are in operation. They wanted to know specifically how I tested the
antenna, why I thought it shorted, and if I actually ever hooked it to a
GPS receiver. I answered as best I could but haven't heard anything
further. eBay seems to like pictures or videos. Though problematic, I
suppose I could take some pictures. I offered to do so in my response to
the seller. They do seem a bit more responsive to buyer complaints than in
previous years. I recently ordered a 64 Gb micro SD card from a US based
seller. I got a message from eBay stating that they had removed the listing
but that everything should be OK. I never received the SD card, and after a
month, checked PayPal and saw that I had been charged for it. I contacted
eBay and they refunded my money the next day.
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[time-nuts] eBay GPS antenna test results.

[John Green]

Bob wrote:
Is it labeled 3.3 to 18V on the antenna?

No, the writing on the antenna is all Chinese. The specs published on eBay
state that it is.
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Re: [time-nuts] eBay GPS antenna test results.

[John Green]

To those who doubted that the antenna was actually a 3.3 to 18 volt design,
it seems you were correct. Today, I hooked it up to a variable power supply
and slowly raised the DC voltage fed to the antenna. It began to pull
current at about 2.9 volts and at 3.3 volts, took about 40 mA. I continued
to slowly raise the voltage. At about 7.5 volts, the current suddenly
dropped to 10 mA. At just below 12 volts, it suddenly increased to 80 mA
and the supply went into current limit. I increased the current limit to
130 mA and repeated the exercise. Everything went as above until I reached
12 volts and the current went to 130 mA and the supply went into current
limit. Lowering the voltage didn't lower the current. I disconnected it,
waited a minute, and tried again. Yep, shorted. It would have worked well
with the T bolt, but would have blown anyway if I tried to use it with my
12 volt supply and bias T. I guess I will get inside it somehow to see if
it can be repaired. My first attempt ended in failure. I guess I need a
bigger screwdriver with which to pry the top off. I am going to contact the
seller and tell them it was not as advertised. I kind of doubt that will
get me anything, but it won't hurt to try. There is a saying about
experience being a cruel teacher. You get the results first, and the lesson
after. Oh well.
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[time-nuts] PulsePuppy Status

[John Ackermann N8UR]

For those who ordered a PulsePuppy oscillator carrier board from TAPR -- 
we quoted early February delivery so I wanted to give a quick update.


The boards are in hand and the kits ready to go, except... USPS managed 
to lose the box of programmed PICs on its way from my house to the TAPR 
office.  I should be getting a new batch from Mouser tomorrow, and have 
them on the way back to the office by Monday (via UPS this time).  With 
luck, we should be able to ship kits by the end of next week.


Sorry for the delay; if not for the lost package we would have shipped 
last week.


(If you're not familiar with the PulsePuppy, here's the link: 
https://www.tapr.org/kits_pp.html.  We'll have plenty of kits available 
once the PIC chip problem is solved.)


John
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Re: [time-nuts] eBay GPS antenna discussion.

[John Green]

Dr. David Kirkby wrote:
Another RF engineer, who I don't know from working with antennas, said to
me that antennas are a still a charlatan's paradise.

Those words rang true to me. I have yet to see a yagi type antenna that, in
practice actually produced the gain it was specified to produce. True, I
don't have a proper chamber in which to test antennas. I can only do real
world comparisons. I have a pretty large collection of various 900 mHz
antennas and on occasion, I set up my home made antenna test range and do
measurements. This consists of a 900 MHz handie talkie with power turned
down as low as it will go and PTT fastened down with a rubber band. Several
hundred feet away, on a deck attached to my house at a height of about 10
feet, I have an HP 8924C to measure levels. First, I measure a home made
groundplane for reference. Then the antennas to be tested are attached and
measured. I realize that there are multiple places where error can and does
creep in. But, I have found that when I actually try to use the antennas
tested, the results are pretty accurate for real world conditions. I
haven't found a good way just yet to test GPS antennas. There are just too
many things besides gain to be considered. Many of which are beyond my
capabilities.
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Re: [time-nuts] eBay GPS antenna.

[John Green]

I kind of have to believe the specs. The two survey grade antennas I
already have, a Leica and a Trimble, both have regulators in the preamp
sections. The Leica has an 8 volt one and the Trimble has a 5 volt one. I
intend to hook it up to a variable supply and watch the current as I
increase voltage. If it has a regulator, the current should stabilize at an
input voltage just above what the internal preamp operates at. If not, it
should continue to rise. I am tempted to pry it apart, even if it risks
damage just so I can see for myself what they are using for the preamp
stages.
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Re: [time-nuts] eBay GPS antenna.

[John Green]

It should work with a T bolt since its range is 3.3 to 18 volts. I also
have a good bias T and GPS type splitter that only passes power to one port
that I can also use. I hope the gain isn't a problem. I live in the
country, so local RF shouldn't be an issue. I can scrounge up some pads if
need be. I plan on starting out with the Leica if I can retrieve it from
its present location. Then, I will probably compare that to the Trimble and
later the Chinese made one. I also have a couple of the type they use at
cellsites, one of which is a Motorola. Something tells me that the Leica
will be the eventual winner. It is the only one that is a choke ring type.
I keep looking on eBay for a reasonably priced unit that will work with the
new L5 civilian band birds. Nothing so far.
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Re: [time-nuts] eBay GPS antenna.

[John Green]

Thanks for the responses. It looks similar to but not exactly like the two
antennas referenced. They say the preamp is 3 to 5.5 volts, whereas the
eBay antenna says its preamp is good from 3.3 to 18 volts, indicating I can
run it off 12 volts. Regarding the internals, I must have somehow missed
the photo which clearly shows it to be a patch antenna. It looks pretty
similar to the Trimble I asked about recently, inside, that is. That
Trimble had been dropped from a great height. The nylon screws that hold
the actual antenna assembly had all been broken. I ordered new ones and
replaced them. Disassembly was easy, reassembly not so much. Mine was made
to have the groundplane, but doesn't have it. I suspect that since I am not
doing surveying, it won't matter all that much. I bought an adapter for the
5/8 by 11 thread it uses and have a pvc pipe mount ready to go up. My
location is not ideal. It will be atop a 40 foot Rohn 25 tower, but there
are tall trees nearby. Since my Z3801 died, I don't have much of a GPSDO to
use the antenna with. Just a couple of T bolts and some kind of postcard
sized unit I need to build a housing and power supply for. Still, enough to
experiment with.
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[time-nuts] Anyone have experience with this antenna?

[John Green]

https://www.ebay.com/itm/High-Precision-L1-L2-GNSS-GPS-GLONASS-BeiDou-RTK-CORS-survey-antenna/162718512935?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

Listed on eBay as a L1/L2 antenna with decent specs. They seem to indicate
it is as good as a choke ring antenna. I suspect it is just a patch in a
fancy package. That is what the Leica and Trimble survey grade antennas I
have contain anyway. I bought one but haven't had the chance to do any
testing. I couldn't figure out how to get to the insides to take a peek
without damaging it. My antenna testing abilities are pretty feeble.
Mostly, I will just compare it to the Leica and Trimble to see how many
satellites it sees and look at position wander of the uBlox. Is there any
simple way to judge the quality of a GPS antenna?
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Re: [time-nuts] Rakon HSO-14

[John Ackermann N8UR]

Here's a link to data on an 8607-008.  You may recognize the bottom plot 
from a recent posting. :-)  But the ADEV and PN data at the top of the 
page is from the factory test data.  The ADEV doesn't explicitly say so, 
but I strongly believe it's based on comparison with a "gold standard" 8607.


http://febo.com/pages/oscillators/bva/

John


On 02/04/2018 02:38 PM, Bob kb8tq wrote:

Hi

Obviously you need two more 8607’s ….. :)

I suspect you are correct and the OCXO is doing better than the close in data 
suggests.

Bob


On Feb 4, 2018, at 8:33 AM, Tom Van Baak <t...@leapsecond.com> wrote:

FYI: here's an old plot where I evaluated an Oscilloquartz 8607 BVA against a 
H-maser. It gets down to 8e-14 but is likely a bit better. On this plot, I 
suspect the short-term numbers were not the BVA oscillator or the TSC 5110A 
analyzer, but the H-maser.

/tvb
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Re: [time-nuts] More on SiLabs 5340

[John Miles]

> -Original Message-
> There is a small detail that puzzles me: the ADEV for the internal
> reference 10MHz and 30MHz bends upwards at tau greater than 0.1s.
> Shouldn't that be visible by a change in slope in the phase noise
> plot at ~10Hz as well?
> 
>   Attila Kinali


Linear drift (which is what's happening here) has a bigger effect on the 
overall gestalt of an ADEV plot than it will on a phase noise plot.  This is 
because long-term drift looks similar to DC offset or noise at extremely low 
frequencies, both of which are attenuated by an HPF stage prior to each FFT 
segment.  But ADEV doesn't benefit from DC removal, and since it doesn't 
converge in the presence of drift, you get the usual upturn in the trace at 
increasing taus. 

When you see a highly-elevated noise trace at low offset frequencies, it's also 
a good idea to check for glitches in the 'f' measurement view, although in this 
case the L(f) spectrum is very typical of these sorts of parts. 

-- john, KE5FX
Miles Design LLC


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Re: [time-nuts] More on SiLabs 5340

[John Ackermann N8UR]

On 01/29/2018 04:54 PM, Chris Caudle wrote:

On Mon, January 29, 2018 2:38 pm, John Ackermann N8UR wrote:

The close-in phase noise is quite amazing, but the floor is much worse
than in free-run mode.


That phase noise plot doesn't look quite right, what PLL bandwidth did you
set?


Sorry for the earlier null reply.  I just used the settings that the 
ClockBuilder software came up with (which IIRC don't offer any choices 
about loop bandwidth in the "wizard").  I haven't yet dug into the 
register options, but I'm sure that there are ways to optimize.


John
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Re: [time-nuts] More on SiLabs 5340

[John Ackermann N8UR]

On Jan 29, 2018, 4:54 PM, at 4:54 PM, Chris Caudle <ch...@chriscaudle.org> 
wrote:
>On Mon, January 29, 2018 2:38 pm, John Ackermann N8UR wrote:
>> The close-in phase noise is quite amazing, but the floor is much
>worse
>> than in free-run mode.
>
>That phase noise plot doesn't look quite right, what PLL bandwidth did
>you
>set?
>
>-- 
>Chris Caudle
>
>
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Re: [time-nuts] Si5340 synthesizer chip performance

[John Ackermann N8UR]

The reference was a 5 MHz Wenzel ULN and the instrument was a Miles TimePod.

On Jan 28, 2018, 8:13 PM, at 8:13 PM, Jerry Hancock <je...@hanler.com> wrote:
>John, what device did you use for the test?
>
>
>Regards,
>
>Jerry
>
>
>Jerry Hancock
>je...@hanler.com
>(415) 215-3779
>
>> On Jan 28, 2018, at 4:23 PM, John Ackermann N8UR <j...@febo.com>
>wrote:
>> 
>> I received the Si5340A evaluation board from Digikey on Friday and
>fired it up yesterday.  I used the SiLabs "ClockBuilder" software to
>configure four outputs -- 10 MHz, 15 MHz, 29.999 999 9 MHz, and 144.2
>MHz -- all using the 45 MHz crystal that comes with the EVM.  Attached
>is a phase noise plot of the 10 MHz and 29.999 999 9 MHz signals.  I
>would say this isn't too bad!  This performance is certainly sufficient
>for any of the RF work I have in mind.
>> 
>> The ADEV was another matter -- about 1e-9 at 1 second, working its
>way uphill from there.  But what do you expect from a bare crystal?
>> 
>> John
>> 
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[time-nuts] Si5340 synthesizer chip performance

[John Ackermann N8UR]

I received the Si5340A evaluation board from Digikey on Friday and fired 
it up yesterday.  I used the SiLabs "ClockBuilder" software to configure 
four outputs -- 10 MHz, 15 MHz, 29.999 999 9 MHz, and 144.2 MHz -- all 
using the 45 MHz crystal that comes with the EVM.  Attached is a phase 
noise plot of the 10 MHz and 29.999 999 9 MHz signals.  I would say this 
isn't too bad!  This performance is certainly sufficient for any of the 
RF work I have in mind.


The ADEV was another matter -- about 1e-9 at 1 second, working its way 
uphill from there.  But what do you expect from a bare crystal?


John

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Re: [time-nuts] Microsemi 3120A sold on eBay

[John Allen]

It is interesting to note that the seller is in Salem, MA, a few miles south of 
Microsemi in Beverly, MA.

PS: Here is a list of the many acquisitions they have made:
https://www.microsemi.com/company/acquisitions

John K1AE

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of John Miles
Sent: Saturday, January 27, 2018 6:49 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Microsemi 3120A sold on eBay

They're essentially the same as the original TimePod 5330A specs  ( 
http://www.miles.io/TimePod_5330A_user_manual.pdf page 11).  The 3120A doesn't 
display noise at offsets below 1 Hz, though, while the 5330A went down to 0.01 
Hz.  Also, some of the TimePod features are "added-value" software options in 
the 3120A, but it's not clear if this unit came with any of the license keys.  

The final selling price seems fairly reasonable considering the sparse details 
provided by the seller.  If someone on the list bought it and it doesn't have 
the software CD, drop me a note offline and I'll hook you up.

-- john, KE5FX
Miles Design LLC

> What are the specs ? 73 de N1UL
> 
> Sent from my iPhone
> 
> > On Jan 27, 2018, at 5:38 PM, John Miles <j...@miles.io> wrote:
> >
> > So, who's the lucky winner?  Anyone on here?  That's the first one of these
> > I've seen in the "secondary market," so to speak.
> >
> >
> >
> > https://www.ebay.com/itm/332531180078
> >

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---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

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Re: [time-nuts] Microsemi 3120A sold on eBay

[John Miles]

They're essentially the same as the original TimePod 5330A specs  ( 
http://www.miles.io/TimePod_5330A_user_manual.pdf page 11).  The 3120A doesn't 
display noise at offsets below 1 Hz, though, while the 5330A went down to 0.01 
Hz.  Also, some of the TimePod features are "added-value" software options in 
the 3120A, but it's not clear if this unit came with any of the license keys.  

The final selling price seems fairly reasonable considering the sparse details 
provided by the seller.  If someone on the list bought it and it doesn't have 
the software CD, drop me a note offline and I'll hook you up.

-- john, KE5FX
Miles Design LLC

> What are the specs ? 73 de N1UL
> 
> Sent from my iPhone
> 
> > On Jan 27, 2018, at 5:38 PM, John Miles <j...@miles.io> wrote:
> >
> > So, who's the lucky winner?  Anyone on here?  That's the first one of these
> > I've seen in the "secondary market," so to speak.
> >
> >
> >
> > https://www.ebay.com/itm/332531180078
> >

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[time-nuts] Microsemi 3120A sold on eBay

[John Miles]

So, who's the lucky winner?  Anyone on here?  That's the first one of these
I've seen in the "secondary market," so to speak.

 

https://www.ebay.com/itm/332531180078

 

-- john

Miles Design LLC

 

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[time-nuts] TNS-BUF bare boards

[John Ackermann N8UR]

Some time ago TAPR did a one-time run of a very low noise, very high 
isolation buffer amplifier.  The assembled boards are sold out, but we 
had some extra blank boards made and finally (after a long story) got 
those delivered from Hungary to the office.


If you're interested in a TNS-BUF board, they are $15 plus shipping and 
you can order via the button at http://tapr.org/kits_tns-buf.html


I'm working on a publishable bill of materials for the parts to stuff 
the boards, and will put a link to it on that web page ASAP.


John
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Re: [time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block?

[John Ackermann N8UR]

Yes, I was planning to include bypasses, and I've been convinced to put 
at least the 1.8V regulator on the board as well.  And to think about 
the interconnects.


Adding the crystal does make the layout more complex -- they put a 
ground pour on its own layer underneath it, and I think (but am not 
sure) that the connections complicate selecting an external oscillator. 
I'll look into the pain tradeoff.


On 01/25/2018 04:08 PM, Robert LaJeunesse wrote:

John, I appreciate your minimalist goal, but I'll second Bill's section about including 
the power supply voltage regulator and bypassing. Finding a good regulator with wideband 
line regulation/rejection could prove a real search, and such a fast chip as the Si5340 
will need excellent broadband supply bypassing. So keep these key components tight to the 
chip, on the same PCB obviously. The need for a 4- to 6-layer board screams "keep 
critical loops tight"! FYI a regulator (of needed RF performance) producing 3.3V for 
VDDA will likely have an absolute max input voltage of 6V or so. Having a 5V supply 
requirement will not be a serious limitation of the overall system design. I'm sure you 
know the 1.8V supply regulators should not be fed from VDDA (3.3V), but I'll mention it 
anyway.

With that much on the PCB adding a small crystal can't add significantly to the cost, 
so why not? It allows R of the chip and outputs before having to hook up one's 
10MHz reference. As such crystal quality / stability / etc. are of little concern - 
just size & cost.

I also like the previous suggestion of castellated connections on the board edge - 
easy to solder to a board and easy to solder wires to. If you make the castellations 
on 0.1" (or 2mm) centers then it becomes possible to use common header pins as 
well. Just keeping your options open there.

Bob L.


Sent: Thursday, January 25, 2018 at 3:23 PM
From: "John Ackermann N8UR" <j...@febo.com>
To: time-nuts@febo.com
Subject: Re: [time-nuts] Slightly OT: interest in a four-output, ultra-low 
jitter, synthesizer block?

Hi Bill --

And that's exactly what I *don't* want to do. :-)  The reason is that I
have several different projects in mind (and everyone else will have
their own requirements) and only want to deal with the difficult package
once.

The idea is to make a minimal carrier to deal with the tiny part and
six-layer board.  Then all the ancillary stuff (including the MCU that's
needed to program the chip) goes onto the board designed for that
project.  This isn't intended to be a finished product, just a building
block.

73,
John

On 01/25/2018 03:12 PM, wb6bnq wrote:

Hi John,

Thanks for the response.  Here is my 2 cents:

Well, due to the level of difficulty in chip mounting, I would prefer to
see a complete project. I.E., power supply for a single input of 12
volts and regulators the necessary chip values, proper input protection
for the 10 MHz input level and single ended outputs of the appropriate
levels (I am assuming more than 3 volts) or an amplifier stage for
arriving at such.  Equally have RF connectors (SMA would be good) on the
board perhaps.

Of course as cheap as possible, hi hi.  A carrier board arrangement
would be useless to me.  My application would be to provide signals for
things like my Quicksilver SDR receiver, among other uses.

If you are interested, I can show you a nice little ABS (I think) box
that has EMI built-in that I used for a project that should be more than
large enough for your needs.

Thanks for reading,

73BillWB6BNQ


John Ackermann N8UR wrote:


Hi Bill --

I should have been more clear: this design will be for a simple case:
one reference clock input, four outputs.  The chip can do all sorts of
fancy tricks, but I'm looking for a source of four low jitter outputs
derived from a 10 MHz external reference (not using crystal or
on-board oscillator).  Many of the pins are unused in that configuration.

I'm not looking to make a universal carrier for the chip, but to meet
what I suspect is a common time-nut/ham radio desire for a clean
multi-channel synthesizer.

On 01/25/2018 02:02 PM, wb6bnq wrote:


Hi John,

After looking at the data sheet, it seems way more involved then just
making a carrier board for it.  Besides the power supply
requirements, various design selections would dictate different
circuit layouts for different purposes.  Even trying to do a general
purpose application would possibly require having several different
output configurations and possibly a couple of input configurations
as well.  That would imply a rather detailed PCB and that chip
package style is a serious pain in the ass for [what amounts to]
hobbyists.  So it would seem the logical course would be to do
serious design application and see if an in-house component mounting
job would be feasible.

I notice that the data sheet says the jitter specs are only best when
using The internal crystal oscillator frequency between 48 and 54
MHz.

Re: [time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block?

[John Ackermann N8UR]

Hi Bill --

And that's exactly what I *don't* want to do. :-)  The reason is that I 
have several different projects in mind (and everyone else will have 
their own requirements) and only want to deal with the difficult package 
once.


The idea is to make a minimal carrier to deal with the tiny part and 
six-layer board.  Then all the ancillary stuff (including the MCU that's 
needed to program the chip) goes onto the board designed for that 
project.  This isn't intended to be a finished product, just a building 
block.


73,
John

On 01/25/2018 03:12 PM, wb6bnq wrote:

Hi John,

Thanks for the response.  Here is my 2 cents:

Well, due to the level of difficulty in chip mounting, I would prefer to 
see a complete project. I.E., power supply for a single input of 12 
volts and regulators the necessary chip values, proper input protection 
for the 10 MHz input level and single ended outputs of the appropriate 
levels (I am assuming more than 3 volts) or an amplifier stage for 
arriving at such.  Equally have RF connectors (SMA would be good) on the 
board perhaps.


Of course as cheap as possible, hi hi.  A carrier board arrangement 
would be useless to me.  My application would be to provide signals for 
things like my Quicksilver SDR receiver, among other uses.


If you are interested, I can show you a nice little ABS (I think) box 
that has EMI built-in that I used for a project that should be more than 
large enough for your needs.


Thanks for reading,

73BillWB6BNQ


John Ackermann N8UR wrote:


Hi Bill --

I should have been more clear: this design will be for a simple case: 
one reference clock input, four outputs.  The chip can do all sorts of 
fancy tricks, but I'm looking for a source of four low jitter outputs 
derived from a 10 MHz external reference (not using crystal or 
on-board oscillator).  Many of the pins are unused in that configuration.


I'm not looking to make a universal carrier for the chip, but to meet 
what I suspect is a common time-nut/ham radio desire for a clean 
multi-channel synthesizer.


On 01/25/2018 02:02 PM, wb6bnq wrote:


Hi John,

After looking at the data sheet, it seems way more involved then just 
making a carrier board for it.  Besides the power supply 
requirements, various design selections would dictate different 
circuit layouts for different purposes.  Even trying to do a general 
purpose application would possibly require having several different 
output configurations and possibly a couple of input configurations 
as well.  That would imply a rather detailed PCB and that chip 
package style is a serious pain in the ass for [what amounts to] 
hobbyists.  So it would seem the logical course would be to do 
serious design application and see if an in-house component mounting 
job would be feasible.


I notice that the data sheet says the jitter specs are only best when 
using The internal crystal oscillator frequency between 48 and 54 
MHz. It was unclear to me that the same would apply to using the 
non-crystal inputs.


Perhaps you could indicate what you are attempting to do with it and 
how you are going to accomplish your goals ?


73BillWB6BNQ


John Ackermann N8UR wrote:

After the recent discussion about Silicon Labs clock generators, I 
looked at their Si5340A part and think it will be useful for a ham 
radio project I'm working on.  While it can do other things, for my 
use it would use a 10 MHz input clock and generate 4 independent 
outputs in the range of 100 kHz to 1028 MHz.  Its jitter is <100fs, 
which translates to "not bad" phase noise.  Here's the data sheet if 
you're interested:


http://www.silabs.com/documents/public/data-sheets/Si5341-40-D-DataSheet.pdf 



The challenge is that the chip is a 7x7 mm 44-QFN package and really 
wants to be put on a six-layer circuit board.  That's doable, but 
challenging, for home assembly.


Rather than designing the chip into a larger circuit board, I'm 
thinking of doing a small "carrier" board that would include just 
the chip and critical bypass caps and have headers to plug into the 
main board. Then, you could just drop the carrier into a 
project-specific board and not have to worry about the complex 
layout and mounting.  I have a contract manufacturer who can build 
these up, if there's enough quantity to justify the setup cost.


If you'd be interested acquiring in one or more of these, please 
drop me a line off-list (jra at febo dot com).  I don't think this 
will be a TAPR project, but if there's enough interest to build 25 
of these carriers, I can probably make that happen.  And remember -- 
this is just the chip; you'll need to provide the rest of the circuit.


John
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Re: [time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block?

[John Ackermann N8UR]

Hi Bill --

I should have been more clear: this design will be for a simple case: 
one reference clock input, four outputs.  The chip can do all sorts of 
fancy tricks, but I'm looking for a source of four low jitter outputs 
derived from a 10 MHz external reference (not using crystal or on-board 
oscillator).  Many of the pins are unused in that configuration.


I'm not looking to make a universal carrier for the chip, but to meet 
what I suspect is a common time-nut/ham radio desire for a clean 
multi-channel synthesizer.


On 01/25/2018 02:02 PM, wb6bnq wrote:

Hi John,

After looking at the data sheet, it seems way more involved then just 
making a carrier board for it.  Besides the power supply requirements, 
various design selections would dictate different circuit layouts for 
different purposes.  Even trying to do a general purpose application 
would possibly require having several different output configurations 
and possibly a couple of input configurations as well.  That would imply 
a rather detailed PCB and that chip package style is a serious pain in 
the ass for [what amounts to] hobbyists.  So it would seem the logical 
course would be to do serious design application and see if an in-house 
component mounting job would be feasible.


I notice that the data sheet says the jitter specs are only best when 
using The internal crystal oscillator frequency between 48 and 54 MHz. 
It was unclear to me that the same would apply to using the non-crystal 
inputs.


Perhaps you could indicate what you are attempting to do with it and how 
you are going to accomplish your goals ?


73BillWB6BNQ


John Ackermann N8UR wrote:

After the recent discussion about Silicon Labs clock generators, I 
looked at their Si5340A part and think it will be useful for a ham 
radio project I'm working on.  While it can do other things, for my 
use it would use a 10 MHz input clock and generate 4 independent 
outputs in the range of 100 kHz to 1028 MHz.  Its jitter is <100fs, 
which translates to "not bad" phase noise.  Here's the data sheet if 
you're interested:


http://www.silabs.com/documents/public/data-sheets/Si5341-40-D-DataSheet.pdf 



The challenge is that the chip is a 7x7 mm 44-QFN package and really 
wants to be put on a six-layer circuit board.  That's doable, but 
challenging, for home assembly.


Rather than designing the chip into a larger circuit board, I'm 
thinking of doing a small "carrier" board that would include just the 
chip and critical bypass caps and have headers to plug into the main 
board. Then, you could just drop the carrier into a project-specific 
board and not have to worry about the complex layout and mounting.  I 
have a contract manufacturer who can build these up, if there's enough 
quantity to justify the setup cost.


If you'd be interested acquiring in one or more of these, please drop 
me a line off-list (jra at febo dot com).  I don't think this will be 
a TAPR project, but if there's enough interest to build 25 of these 
carriers, I can probably make that happen.  And remember -- this is 
just the chip; you'll need to provide the rest of the circuit.


John
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[time-nuts] Slightly OT: interest in a four-output, ultra-low jitter, synthesizer block?

[John Ackermann N8UR]

After the recent discussion about Silicon Labs clock generators, I 
looked at their Si5340A part and think it will be useful for a ham radio 
project I'm working on.  While it can do other things, for my use it 
would use a 10 MHz input clock and generate 4 independent outputs in the 
range of 100 kHz to 1028 MHz.  Its jitter is <100fs, which translates to 
"not bad" phase noise.  Here's the data sheet if you're interested:


http://www.silabs.com/documents/public/data-sheets/Si5341-40-D-DataSheet.pdf

The challenge is that the chip is a 7x7 mm 44-QFN package and really 
wants to be put on a six-layer circuit board.  That's doable, but 
challenging, for home assembly.


Rather than designing the chip into a larger circuit board, I'm thinking 
of doing a small "carrier" board that would include just the chip and 
critical bypass caps and have headers to plug into the main board. 
Then, you could just drop the carrier into a project-specific board and 
not have to worry about the complex layout and mounting.  I have a 
contract manufacturer who can build these up, if there's enough quantity 
to justify the setup cost.


If you'd be interested acquiring in one or more of these, please drop me 
a line off-list (jra at febo dot com).  I don't think this will be a 
TAPR project, but if there's enough interest to build 25 of these 
carriers, I can probably make that happen.  And remember -- this is just 
the chip; you'll need to provide the rest of the circuit.


John
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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[John Ackermann N8UR]

Hi Mark --

Thanks!  To clarify, when you say you've found "it" acceptable, you're 
referring to the 5328?


What caught my eye about the 5351 was the three (or eight) outputs.  My 
idea was to build a board that would provide independent LO oscillators 
for multiple VHF/UHF transverters.  It looks like the 5328 has two 
outputs, which is still useful but would require putting two or three of 
them on the board.  Which isn't the end of the world.


Thanks,
John


On 1/19/2018 8:56 AM, Mark Goldberg wrote:

On Jan 19, 2018 6:01 AM, "John Ackermann N8UR" <j...@febo.com> wrote:


Sorry to hijack the thread, but the Si5351 looks interesting for another
project I'm working on.  I know it specifies "low jitter" but has anyone
looked at the phase noise?  Is it usable for RF applications?




Datasheet states jitter in the 40-70 ps range. That is not very good. If
you want something suitable for RF applications, look at the Si5328. It has
jitter on the order of 300fs.

I believe Leo Bodnar uses it in his GPSDOs and I can confirm the phase
noise and Allan Deviation others have found and it is suitable for me for
RF applications. It is not nearly as good as the Thunderbolt though. It
will generate almost any frequency you want.

Mark





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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[John Ackermann N8UR]

Sorry to hijack the thread, but the Si5351 looks interesting for another 
project I'm working on.  I know it specifies "low jitter" but has anyone 
looked at the phase noise?  Is it usable for RF applications?


Thanks,
John


On 01/18/2018 08:53 AM, D. Jeff Dionne wrote:

Chris,

You don't need to do that.  The SiLabs part will accept the 10MHz sin from an 
OCXO directly into the XA pin.  That pin normally connects to a crystal, so 
there is a high gain amp in the chip to square it up already... I did the tests 
a while back, see the thread here:

https://www.silabs.com/community/timing/forum.topic.html/si5351_msop10_packag-wocK

Caveats: others had trouble with biasing, and found just squaring the OCXO up 
first worked for them. SiLabs software is not set up to allow any other 
frequencies except 25 or 27MHz, so you do need to calculate the register values 
yourself.

J.


Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt as a 
reference clock at 1v P to P square wave for a Si5351a synthesizer chip please? 
I have the David Partridge divider board from way back that is still going 
strong, but 25 MHz is not an option as it divides only. Thanks, please keep 
replies to the level an idiot might comprehend :) -- Best Regards, Chris 
Wilson. mailto: chris at chriswilson.tv

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[time-nuts] Looking for information regarding Trimble 33429-00 microcentered GPS antenna.

[John Green]

I have been gone for a good while, but now that I am officially retired, I
thought I would get back into the time/frequency hobby. I recently bought a
Trimble 33429-00 antenna off eBay. I can't seem to find much on the
internet about it. Google has not been my friend. First, I assume the
"micro centered" refers to the phase center being located with precision.
Mine was meant to be used with the ground plane, which did not come with
it, so the marks indication the part to be pointed north are missing. It
doesn't matter in my use since I won't be surveying anyway. Can someone
tell me what voltage it takes? I decided that the Leica choke ring antenna
I got a while back took 12 volts because the power input went to an 8 volt
regulator, and I figured 12 volts should work ok. On this one, the power
goes to a 2951 adjustable regulator, leaving me a bit in the dark. I will
probably try hooking an adjustable power supply to it and slowly raising
the voltage until the output of the regulator stabilizes. They seem to have
made two versions of this antenna. One with groundplane, and one without.
Since I will be feeding a GPSDO, would a groundplane be of benefit? In
looking through the archives, it seems I have missed a lot of good
discussions. Good to be back.
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[time-nuts] MTI-Milliren OCXO Issue

[John C. Westmoreland, P.E.]

Hello All,

Just wondering - has anyone made any recent purchases with MTI-Milliren
regarding OCXO's?

I've had a recent interaction with them that makes me think their OCXO's
could go the way of the
dinosaur; maybe it's just me; hoping someone on the list has some recent
experience with MTI-Milliren and can respond.

Thanks In Advance,
John W.
AJ6BC
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Re: [time-nuts] LED replacement screen for 53131A 53132A!!??

[John Allen]

Hi Mark - will it drive LEDs?  Are you going to build some of these up?  Are 
there more VFDs available on eBay?

Thanks, John (2 53131s and one 53132)

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims
Sent: Saturday, January 06, 2018 5:29 PM
To: time-nuts@febo.com
Subject: [time-nuts] LED replacement screen for 53131A 53132A!!??

I have worked out a design for a replacement 531xx front panel that uses a 
micro and LCD module to emulate the VFD display.  I was going to do it when my 
VFD died, but just bought a couple of spare VFDs off of Ebay.

The 531xx front panel board basically has a bunch of elastomer switch contact 
pads and a couple VFD drivers with shift register inputs.  The output bit of 
the shift register chain is fed back to the motherboard for self tests.  I seem 
to remember that one of the VFD drivers also scans the keyboard.   

The replacement front panel micro would take in the shift register data pulses 
and convert the data to a format that could be drawn on the LCD display.  Of 
course you could use whatever type of display you like if LCDs are not to your 
taste.
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---
This email has been checked for viruses by Avast antivirus software.
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Re: [time-nuts] Skilled Maths Editor(s) Needed

[John Ponsonby]

When it first came out I wrote a review of the two volume work:
"The Quantum Physics of Atomic Frequency Standards" By Jacques Vanier and 
Claude Audoin 
for a well known journal. Not only was I paid handsomely but I was given the 
book(s) to keep.
It is true it is written in English but it uses french idioms which suggests 
the two francophone authors actually wrote it or at least thought of it in 
french initially.
As it is a valuable and much treasured work I’d be reluctant to let it out of 
my hands but I’d be quite prepared to copy a few pages to replace those that 
are “smeared” in the photocopy in Perry Sandeen’s possession.
John P


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Re: [time-nuts] Stable32 now available

[John Ackermann N8UR]

FWIW, for me the hardest part of working with Stable32 is getting the 
input scaling and other parameters like timestamps correct.  If you 
think like a mathematician, you'll probably do fine.  But I don't, and 
when working in particular with frequency data it always takes me a few 
tries to get it right.


But Stable32 is superb software, and this is a wonderful contribution. 
Thanks, Bill!


John


On 01/02/2018 09:46 AM, Tom Van Baak wrote:

 From "Paul Alfille" <paul.alfi...@gmail.com>:
Is the code be available, or just the compiled binary?


I've asked Bill for clarification and will relay any information.



 From "paul swed" <paulsw...@gmail.com>
I suspect we need a Stable32 for dummies book.


When I first started using Stable32 I tried to document each step. See examples 
like:

http://leapsecond.com/pages/ahm-phm/maser1.htm
http://leapsecond.com/pages/doug-rb/
http://leapsecond.com/pages/osa8607-dat/
http://leapsecond.com/pages/hp5065-dat/
http://leapsecond.com/pages/8607-drift/



 From "Magnus Danielson" <mag...@rubidium.dyndns.org>
Now, the code needs to be maintained. I personally also would like to
see it run natively on Linux, it does run on Linux under Wine.


Stable32 seems highly integrated with the "graphic/win" plotting package 
(www.sciend.com). That may be one of the problems porting the code to unix. But hang on, 
and we'll let Bill tell us for sure.



 From "Dr. David Kirkby" <drkir...@kirkbymicrowave.co.uk>
Perhaps someone who has both the book and the software, would comment if
the book is very out of date, or would still be useful.


The book is wonderful. The software hasn't fundamentally changed.
Bill also maintains a fantastic site at http://www.wriley.com/ where you will 
find 100+ documents worth reading.

/tvb

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Re: [time-nuts] TAPR "PulsePuppy" Pot Selection

[John Ackermann N8UR]

I didn't really notice much backlash, though when setting oscillators I try to 
approach (slowly) from one direction until it's "good enough" and then stop, to 
avoid that problem.

On Dec 24, 2017, 11:28 AM, at 11:28 AM, Dana Whitlow <k8yumdoo...@gmail.com> 
wrote:
>John,
>
>Do you notice a backlash effect when homing in on the desired setting
>with
>those
>tripots?  I last used such things back in the 1980's, and remember
>often
>having
>enough backlash to make close trimming rather difficult.
>
>I wonder if they have gotten better in that regard.
>
>Dana
>
>On Sun, Dec 24, 2017 at 9:58 AM, John Ackermann N8UR <j...@febo.com>
>wrote:
>
>> I'm glad that the PulsePuppy post spawned some good discussion!
>>
>> The pot I'm using is a Bournes 3296W-1-103LF which is a 25-turn, 10K,
>> cermet pot, spec'd at 100ppm/degree, so it's not anything super
>fancy. The
>> number of turns provides decent setability, and it seems to be a good
>match
>> for the class of oscillator the PulsePuppy is designed for -- I found
>that
>> I could trim the Isotemp oscillator without problems.
>>
>> I'll admit up front that the PulsePuppy wasn't designed as a host for
>> ultra-stable oscillators.  I tried to keep the circuit board size and
>cost
>> down, as well as the number of components that users would have to
>> install.  And since the EFC trimmer is one of those user-installed
>parts,
>> it's possible to substitute as nice a pot as you'd like.  I have one
>unit
>> that's hooked up to an external precision pot with a turn-counter
>dial
>> (just because it was there).
>>
>> John
>> 
>>
>> On 12/24/2017 03:57 AM, Mark Goldberg wrote:
>>
>>> Can you specify what pot you have used? I am using some for my TCXO
>boards
>>> and am not quite happy with the settability or mechanical stability.
>>> resulting in noise and higher Allan Deviation.
>>>
>>> A low noise regulator driving it also helped.
>>>
>>> I subscribe to the opinion to not use any extra resistors. When the
>pot is
>>> used as a voltage divider, theoretically it should have the same TC
>>> throughout, so temperature effects should not affect the divide
>ratio or
>>> the output. Only the input impedance of the control voltage input to
>the
>>> oscillator relative to the effective resistance of the pot will
>provide
>>> some effect with temperature.
>>>
>>> Mark
>>> ___
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>>> ailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
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>> and follow the instructions there.
>>
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Re: [time-nuts] TAPR "PulsePuppy" Pot Selection

[John Ackermann N8UR]

I'm glad that the PulsePuppy post spawned some good discussion!

The pot I'm using is a Bournes 3296W-1-103LF which is a 25-turn, 10K, 
cermet pot, spec'd at 100ppm/degree, so it's not anything super fancy. 
The number of turns provides decent setability, and it seems to be a 
good match for the class of oscillator the PulsePuppy is designed for -- 
I found that I could trim the Isotemp oscillator without problems.


I'll admit up front that the PulsePuppy wasn't designed as a host for 
ultra-stable oscillators.  I tried to keep the circuit board size and 
cost down, as well as the number of components that users would have to 
install.  And since the EFC trimmer is one of those user-installed 
parts, it's possible to substitute as nice a pot as you'd like.  I have 
one unit that's hooked up to an external precision pot with a 
turn-counter dial (just because it was there).


John

On 12/24/2017 03:57 AM, Mark Goldberg wrote:

Can you specify what pot you have used? I am using some for my TCXO boards
and am not quite happy with the settability or mechanical stability.
resulting in noise and higher Allan Deviation.

A low noise regulator driving it also helped.

I subscribe to the opinion to not use any extra resistors. When the pot is
used as a voltage divider, theoretically it should have the same TC
throughout, so temperature effects should not affect the divide ratio or
the output. Only the input impedance of the control voltage input to the
oscillator relative to the effective resistance of the pot will provide
some effect with temperature.

Mark
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Re: [time-nuts] New product: the TAPR "PulsePuppy"

[John Ackermann N8UR]

Absolutely... the plot is mainly to show what to expect from the little OCXO, 
not the board.  It ain't a BVA, but for the price and size, it's not bad.

On Dec 23, 2017, 4:56 PM, at 4:56 PM, Bob kb8tq <kb...@n1k.org> wrote:
>Hi
>
>Looks neat !!!
>
>It is a pretty good bet that everything you see in the ADEV plot is a
>function of the 
>specific OCXO you put on the board. Put another way, the. board’s ADEV
>is way
>better than the ADEV of the OCXO. It’s a very safe bet that everything
>past 2 seconds
>or is the OCXO. 
>
>Bob
>
>> On Dec 23, 2017, at 4:00 PM, John Ackermann N8UR <j...@febo.com>
>wrote:
>> 
>> I've developed a little board called the PulsePuppy that supports
>surplus OCXOs in the common "Eurocase" form factor to provide outputs
>at 10 MHz, or at 1 PPS/10 PPS/100PPS using an on-board 12F675 PIC with
>one of TVB's picDIV firmware images.
>> 
>> The attached pictures show one prototype unit in closeup, and a panel
>of three that are used for TICC counter production testing (providing
>one 10 MHz and two independent PPS outputs).  Also attached is an ADEV
>plot of the inexpensive Isotemp OCXO131-100 oscillator I'm using to
>give an idea of the performance you can expect from these small
>oscillators (they and others like them are available from several eBay
>sources for <$30).
>> 
>> The PulsePuppy is available from TAPR as a semi-kit and can be
>ordered at http://tapr.org/kits_pp.html for $69.  We expect to ship the
>kits in mid-February (delivery of the boards from our contract
>manufacturer is the gating factor).
>> 
>> The assembly manual with schematics can be downloaded at
>http://www.tapr.org/~n8ur/PulsePuppy_Manual.pdfm but here are the specs
>in brief:
>> 
>> * Footprint for either Eurocase OCXO or Crystek CXOH20-BP-10.000
>>  TCXO (TAPR has a bunch of these TCXOs remaining from another project
>>  and, while they last, is offering them bundled with the PulsePuppy
>>  for an attractive price).
>> 
>> * PPS divider uses TVB PD-13 firmware that includes capability to
>>  synchronize to an external clock.
>> 
>> * TTL-level output at jumper-selectable 10 MHz, 100 PPS, 10 PPS,
>>  or 1 PPS rates.
>> 
>> * A BNC output connector is included, but the board contains a
>footprint
>>  to install a user-provided SMA.
>> 
>> * 25-turn EFC trimmer with 0-5V range.
>> 
>> * Option to support sine-wave as well as square wave oscillators.
>> 
>> * Board dimensions are 1.5 x 3.5 inches.
>> 
>> TAPR is offering the PulsePuppy as a "semi-kit" that includes the
>printed circuit board with all surface-mount components installed, and
>a handful of through-hole parts (like voltage regulators, jumpers, and
>connectors) for the user to install.  By leaving these parts for the
>user, the board can be customized -- for example to use different
>voltages or to support a sine-wave oscillator.
>> 
>> Note that the kit DOES NOT include the oscillator, unless you buy the
>Crystek TCXO bundle.
>> 
>> Happy Holidays to all!
>> 
>> John
>>
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Re: [time-nuts] New product: the TAPR "PulsePuppy"

[John Ackermann N8UR]

Sorry, a typo got into the URL for the manual.  Remove the extraneous 
"m" after ".pdf": http://www.tapr.org/~n8ur/PulsePuppy_Manual.pdf


On 12/23/2017 04:00 PM, John Ackermann N8UR wrote:
I've developed a little board called the PulsePuppy that supports 
surplus OCXOs in the common "Eurocase" form factor to provide outputs at 
10 MHz, or at 1 PPS/10 PPS/100PPS using an on-board 12F675 PIC with one 
of TVB's picDIV firmware images.


The attached pictures show one prototype unit in closeup, and a panel of 
three that are used for TICC counter production testing (providing one 
10 MHz and two independent PPS outputs).  Also attached is an ADEV plot 
of the inexpensive Isotemp OCXO131-100 oscillator I'm using to give an 
idea of the performance you can expect from these small oscillators 
(they and others like them are available from several eBay sources for 
<$30).


The PulsePuppy is available from TAPR as a semi-kit and can be ordered 
at http://tapr.org/kits_pp.html for $69.  We expect to ship the kits in 
mid-February (delivery of the boards from our contract manufacturer is 
the gating factor).


The assembly manual with schematics can be downloaded at 
http://www.tapr.org/~n8ur/PulsePuppy_Manual.pdfm but here are the specs 
in brief:


* Footprint for either Eurocase OCXO or Crystek CXOH20-BP-10.000
   TCXO (TAPR has a bunch of these TCXOs remaining from another project
   and, while they last, is offering them bundled with the PulsePuppy
   for an attractive price).

* PPS divider uses TVB PD-13 firmware that includes capability to
   synchronize to an external clock.

* TTL-level output at jumper-selectable 10 MHz, 100 PPS, 10 PPS,
   or 1 PPS rates.

* A BNC output connector is included, but the board contains a footprint
   to install a user-provided SMA.

* 25-turn EFC trimmer with 0-5V range.

* Option to support sine-wave as well as square wave oscillators.

* Board dimensions are 1.5 x 3.5 inches.

TAPR is offering the PulsePuppy as a "semi-kit" that includes the 
printed circuit board with all surface-mount components installed, and a 
handful of through-hole parts (like voltage regulators, jumpers, and 
connectors) for the user to install.  By leaving these parts for the 
user, the board can be customized -- for example to use different 
voltages or to support a sine-wave oscillator.


Note that the kit DOES NOT include the oscillator, unless you buy the 
Crystek TCXO bundle.


Happy Holidays to all!

John


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Re: [time-nuts] On the IETF leap-seconds.list SHA1

[John Hawkinson]

Umm, the presence of a copy of the IANA TZ distribution at 
https://www.ietf.org/timezones/ is not evidence of an "IETF leap-seconds list." 
This is bizarre, and probably a web server configuration error that even 
exists. The IETF is not involved in this list. I guess this shows why Google is 
an unreliable indicator of authority.

https://www.ietf.org/timezones/data/leap-seconds.list
is not a URL anyone should be depending on.

https://data.iana.org/time-zones/code/leap-seconds.list
is perhaps a better URL for the file in the tz distribution, but I'd hestitate 
to call it canonical. Start at https://www.iana.org/time-zones.

But then the tz database isn't an authorative source, either. Per the NEWS file:

The 'leapseconds' file is now generated automatically from a
new file 'leap-seconds.list', which is a copy of
<ftp://time.nist.gov/pub/leap-seconds.list>.
A new source file 'leapseconds.awk' implements this.
The goal is simplification of the future maintenance of 'leapseconds'.

That is, it's just a copy of NIST's file.

Your email would make a lot more sense if you had included the URLs directly 
rather than referring to your source code and output file that happen to 
contain them.

--jh...@mit.edu
  John Hawkinson

Anders Wallin <anders.e.e.wal...@gmail.com> wrote on Wed, 20 Dec 2017
at 13:51:21 +0200 in 

[time-nuts] TICC counters available again

[John Ackermann N8UR]

TAPR sold out the first run of TICC timestamping counters but we just 
took delivery of a second batch, and we're now taking orders.  See 
http://tapr.org/kits_ticc for details.



John

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Re: [time-nuts] Simple open source microcontroller solution to tune DDS needed

[John Reid]

Bascom is a Basic compiler, for AVR chips if my memory serves right.






> On Dec 13, 2017, at 12:10 PM, Adrian Godwin  wrote:
>
> Maybe this one ?
>
> http://www.qsl.net/pa3ckr/bascom%20and%20avr/ad9951/index.html
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Re: [time-nuts] HP5065 - Some OP-Amp, FB and Teflon

[John Franke]

Great story! Congratulations on the recovery and restoration.

John WA4WDL

> On November 28, 2017 at 1:52 PM Ulf Kylenfall via time-nuts 
> <time-nuts@febo.com> wrote:
> 
> 
>  
> All,
> Your comments regarding my hobby project are appreciated.
> The story behind the first 5065A that I was able to bring back to life was 
> that I encountered it when I was 13 yearsold in 1968, taking part in the 
> schools intern programme (first experience about what a job was and what 
> engineersdo in their work). I was given a tour of the Onsla Space Observatory 
> and the 5065A, the pride of the observatorywas shown to me. (I was not 
> allowed to touch it.) In the late 90's it was decomissioned because of the 
> burned Rubidium cavityheater and would eventually have gone into the 
> recycling container had I not salvaged it almost 50 years later.
> 
> (I found the OPA111 link in one of the answers in the thread and purchased 
> the remaining 3 pieces.)
> Ulf - SM6GXV
> 
> 
> 
> 
> 
> 
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Re: [time-nuts] H-maser drift

[John Ponsonby]

There seem to be a lot of misunderstandings about H-masers. To set the record 
straight note:
1. The flow of hydrogen is generally controlled using a palladium membrane, 
though a palladium-silver alloy is to be preferred because it is less likely to 
crack. Only hydrogen will diffuse through the palladium-silver membrane, so as 
well as being a temperature controlled regulator it is also a filter. Indeed it 
is an isotopic filter through which even deuterium doesn’t pass. The protons 
are thought to migrate through the membrane and recombine on the output surface 
first into atoms and then into H2 molecules. I used thin walled 
palladium-silver tubes which had roughly the dimensions of a match stick. 
Hydrogen on the inside was at about twice atmospheric pressure with output into 
“vacuum” on the outside. Control is by heating with a large current flowing 
along the rather low resistance tube. Russian H-masers use nickel tubes rather 
than the more expensive palladium-silver. Such a “palladium leak” requires only 
a few seconds on Turn-On to settle to a steady flow.  
2. Hydrogen from the "palladium leak” passes to a “dissociator" which is a 
small bulb made of heavily boronated glass, e.g. Pyrex, in which the H2 
molecules are dissociated into H atoms by a non-contacting RF discharge. Atomic 
hydrogen recombines very readily on any metal surface so the discharge is 
either by magnetic or electric field acting through the glass wall. Metals are 
charactersised by having conduction bands full of free electrons. Boron is an 
electron acceptor, so Pyrex is very unlike a metal and it has a low surface 
recombination rate. Not as low as FEP120 (See 5. below) but one can’t line a 
discharge bulb with it.
3. The very high Q RF cavity (loaded Q ≈ 36000), which is tuned very exactly to 
the hydrogen frequency of 1,420,405,751Hz, operates in the TE011 mode in which 
the oscillating RF magnetic field is toroidal, going up the middle and down the 
outer part of the cavity. The resonant frequency is much more sensitively 
dependent on the cavity diameter than on its length.
4. Inside the cavity is the "storage bulb" which is made not of glass but of 
fused quartz. It is typically about 1mm thick. Fused quartz is chosen for its 
exceptionally low RF loss tangent. But of course it has a dielectric constant 
which results in its loading the cavity which is thus a little smaller than one 
first thinks. Since it is very difficult to manufacture quartz bulbs to normal 
engineering tolerances it is not possible to calculate how much the cavity will 
be loaded. So it is not unusual to manufacture the cavity to match the given 
storage bulb. 
5. The inside of the storage bulb is coated typically with a layer of FEP120, a 
Dupont product akin to Teflon. An H atom can make of the order of 10,000 
bounces off its surface without change of quantum state. Also H atoms won’t 
stick to the coating. (Non-stick frying pans are coated with FEP120 and what is 
true for an egg is true for an atom.)
6. The shape of the storage bulb should be chosen to maximize the “filling 
factor”. This is defined as: η’=Vb^2b/Vc<Ha^2>c  Here the numerator is the 
product of the storage bulb volume Vb times the square of the mean of the z 
component of the RF magnetic field Hz averaged over the internal volume of the 
bulb b, and the denominator is the product of the cavity volume Vc times the 
mean of the square of the magnitude of the RF magnetic field Ha averaged over 
the entire volume of the cavity c. A spherical bulb is non-optimal though may 
early masers had spherical storage bulbs.
7. The RF discharge generates UV. This shines up the beam path and illuminates 
the bulb coating in the region where the incoming atoms first make contact with 
the bulb coating. This UV undoubtledly damages the FEP120 coating. The 
deterioration of the coating may be one of the causes of long term drift.
Cheers
John P
 
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Re: [time-nuts] Deaf Z3801

[John Franke]

Try:


Shut off power to the GPS receiver

Disconnect the GPS antenna downlead

Reapply power to the GPS receiver

Enter  :GPS:INIT:DATE 2017,01,01 (The only space is between DATE and 2017)

Reconnect the GPS antenna downlead and wait


John

> 
> On November 14, 2017 at 10:43 PM Bob Bownes <bow...@gmail.com> wrote:
> 
> I put my 3801 back in service the day before yesterday, or tried to. It’s 
> been on the shelf for about a year (off).
> 
> I powered it up, and while it sees a few sats, it will not acquire any. 
> Changing to a known good antenna (off the NTP server) makes no difference.
> 
> Anyone seen the behavior before? The location data is good, but the 
> time/date are way out.
> 
> Thanks!
> Bob
> 
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Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency

[John Miles]

> Yes, exactly those. With no input, would they be expected to be 4 kHz off?
> The spec for the standard part wants the input to be within 1e-7. I would
> not expect them to be so far off free running.

That does seem like a lot.  I'd expect a few hundred Hz of error at the most.
 
> I saw 13 MHz on the 500-14273 and stayed away from those.
> 
> Do you know of any part numbers that use 10 MHz in? Wenzel would not tell
> me the exact specs of the 500 series parts available on ebay and only sent
> me the specs for the standard 501-14057 that takes 10 MHz.

Most of the 100 and 200 MHz bricks I've seen work with either 5 or 10 MHz .  I 
don't know if I've seen any 80 MHz units that do.  All of the ones I've bought 
on eBay have been from the customer-proprietary 500- series with unusual input 
frequencies.

> Do you know what the pll lock output does when the input frequency is off?
> These toggle high for any frequencies I have put in.

Not offhand.  If there's a PFD inside it should be easy to zero in on the right 
frequency, but if there's only a phase detector you may need to set up a sweep 
and watch the tuning-voltage output on a scope.  I don't remember it taking 
very long to find the correct input frequencies for the ones I bought, though.  
 

-- john, KE5FX
Miles Design LLC

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Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency

[John Miles]

Sounds like he's talking about the small 'bricks' that Wenzel sells with 
internal PLL-disciplined OCXOs.  Some of these expect oddball input 
frequencies.  Just looking at the 80 MHz parts on the shelf around here, 
500-14273 wants a 13 MHz input, 500-25010 uses 24.576 MHz, and 500-25009  uses 
19.2 MHz.   So that's probably the issue, if two of them seem to be failing the 
same way.

-- john, KE5FX
Miles Design LLC


> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
> Camp
> Sent: Sunday, November 12, 2017 2:03 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency
> 
> Hi
> 
> I guess my point was more that there is not a VCO / PLL combo in an OCXO.
> 
> If dropping the supply gets you on frequency, then you have moved things a
> lot
> with that voltage change. 50 PPM is a lot of delta T on any normal OCXO
> crystal.
> That strongly suggests there is something wrong in the control circuit.
> 
> Bob
> 
> > On Nov 12, 2017, at 2:52 PM, Mark Goldberg <marklgoldb...@gmail.com>
> wrote:
> >
> > The standard oscillator, 501-14057 (
> > www.wenzel.com/wp-content/parts/501-14057.pdf) will lock to an
> external 10
> > MHz reference and this one is marked "80 MHz" and "15V on the label.
> Maybe
> > someone swapped the labels. I did try lowering the supply voltage. It got
> > to 80 MHz at about 11V and still did not lock to the reference. This
> > oscillator is specified at 1e-6/year aging. That is way less than it is off
> > now.
> >

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Re: [time-nuts] Phase noise measurement experiment by Andrew Holme

[John Miles]

> But be aware, that measurements close to the limit of thermal noise
> will make your measurement go sour. There the noise of your splitter
> will cause an anti-correlation effect and the measured noise will
> suddenly drop way below thermal noise. Craig Nelson and Archita Hati
> from NIST, Enrico Rubiola from FEMTO, Magnus from time-nuts and several
> others have been discussing this for a couple of years now at PTTI,
> IFCS and EFTF.
> (e.g. https://www.nist.gov/publications/cross-spectral-collapse-anti-
> correlated-thermal-noise-power-splitters )

Cross-spectral collapse due to thermal noise is basically Mother Nature 
complaining that we're trying to do something that's physically ill-advised, by 
trying to measure the noise in a system at levels near the thermal floor of the 
termination resistance that's necessary to define such a system in the first 
place.  Unfortunately the issue can affect measurements at levels several dB 
higher than the thermal floor, making it a genuine occupational hazard.

On the bright side, splitter topologies that use a single resistive load with 
no differential-mode termination have little or no vulnerability to this 
phenomenon.  Of course the common-mode termination imposes its own noise floor, 
but that's life in this particular universe.   

That being said, it's still a bit of an awkward situation for designers of 
future test sets.  We can't use Wilkinson splitters anymore -- or at least we 
shouldn't, given what's been learned over the past couple of years.  As a 
result, some customers' best devices may suddenly start looking noisier than 
they did when measured on earlier instruments, or (worse) when measured on 
competing ones.  Those customers may not respond agreeably when advised to dunk 
the termination in liquid helium...

> > Since the cross correlation could reduce noise a lot, I am wondering what
> > the differences between 14 bits and 16 bits ADC are.

None to speak of.  The original TSC 5120A used 14-bit parts while the later 
test sets have used 16-bit parts, and the performance limits are essentially 
identical.  Once you go below a certain point, generally well below -170 
dBc/Hz, you tend to run into a correlation floor that arises from one or more 
different causes unrelated to the quantization precision itself.  These effects 
seem to arise in and near the S/H stage and aren't improved by going beyond 
14-bit precision. 

-- john, KE5FX
Miles Design LLC


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Re: [time-nuts] chrony vs ntpd

[John Ackermann N8UR]

Jim, I thought about using an RF-input sync pulse for alignment during 
the Solar Eclipse measurement experiment, but ended up running out of 
time to implement it.  But some very crude experiments indicated that 
it's not hard to generate an edge out of a PPS that creates a comb well 
past HF.  My idea was to do a divide-by-sixty to end up with 
pulse-per-minute rather than PPS.  The lower rate would be less annoying 
to filter out of the results.


I'm interested to hear if you end up doing this, and if so how.

John


On 10/28/2017 12:04 PM, jimlux wrote:
Now that I have successfully connected my GPS receiver to my beagle and 
I'm getting pps ticks into the driver, etc. (thanks to info from several 
folks on this list!) the question arises of whether to use ntpd or chrony.


For my particular application, I'm more interested in synchronizing time 
on the local machine, not necessarily being a NTP server - all of my 
beagles have a GPS on them.  Of course, there may be times when a GPS 
doesn't work, or something else comes up where it would be useful for 
one of the machines to "get time" from somewhere else.


What I am doing is using the Beagle to capture RF samples (RTL-SDR) in a 
distributed array, with wireless connections among the nodes.  The 
processing isn't necessarily real-time (maybe later..), for now, it's 
"trigger some seconds of capture at approximately the same time" and 
post process in matlab/octave.


There's all kinds of nondeterministic latency issues with the 
USB/RTL-SDR path, so I'm under no illusion that I can capture samples 
aligned to the 1pps.  However, what I *can* do is generate a "sync 
pulse" from the 1 pps and feed it into the RTL's RF input in some (TBD) 
way.
And the 1pps might give me a clever way to calibrate the frequency drift 
of the RTLSDR's clock.


Right now, I'm interested in HF signals (so the period is 30 ns at the 
top end, and 500 ns at the bottom end)




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Re: [time-nuts] Distribution divider/amplifier for 10MHz GPSDO

[John Ackermann N8UR]

On 10/23/2017 04:52 PM, Hal Murray wrote:

But if any of the EXT REF are low-z inputs, that won't work so well.


Unless there is only one.  Then you can use it as the last one and you don't
need the explicit terminator.


Good point.
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Re: [time-nuts] Distribution divider/amplifier for 10MHz GPSDO

[John Ackermann N8UR]

To some extent, it depends on the load presented by each device.  The 
"EXT REF" input on many pieces of test equipment is fairly high 
impedance (maybe 10k?) and you can drive several of those with a single 
output, putting a 50 ohm load at the end of the line to provide a 
reasonable termination.*  I seem to recall that three HP boxes worked 
nicely off one line, but when I added a fourth things got flaky.


But if any of the EXT REF are low-z inputs, that won't work so well.

FWIW, Spectracom had a distribution system (8140 series) that had 
amplified "tap" boxes that were daisy-chained together on a single coax 
run.  The driver put 12 volts DC on the cable along with 10 MHz, and 
that powered the taps.  You could put several taps on a single line.  I 
once measured the phase noise of the system and while it wasn't up to a 
really good distribution amplifier, it was perfectly adequate for normal 
RF testing.


John

* Mismatch causes reflections, which can screw up square wave edges or 
sine wave zero-crossings, increasing jitter.  SWR is usually a bigger 
issue for RF distribution than amplitude loss.


On 10/23/2017 01:49 PM, Jeremy Elson wrote:

I was about to ask a related question of the list: when do you need a
distribution amplifier, and when is it sufficient to just have a single
(linear) run of coax?

I have a GPSDO (Nick Sayer's device) that I want to use to feed a few other
pieces of equipment in my lab (an HP5335A, John Ackermann's beautiful TICC,
and a Rigol signal generator). Is it safe to have RG174 coming out of the
GPSDO, tapping into it with a BNC T-junction that plugs into the back of
each device that needs the 10mhz input, and then terminating the strand
with a 50 ohm terminator? (In other words, the way thinnet Ethernet was
wired back in the day.) As long as the signal goes in a straight line, not
a "Y" (i.e. no cables attached to the t-junction taps, just a direct input
into a high-z input) it seems like it should work. Do I need a distribution
amplifier? Or is that, say, if the signal needs to split off in multiple
directions and you don't want to fill your lab with a space-filling curve
of coax?

-Jeremy

On Mon, Oct 23, 2017 at 10:26 AM, Bob kb8tq <kb...@n1k.org> wrote:


Hi

The correct answer to any real question like this is “that depends”.

For anything that I normally run as test gear, noise outside a very narrow
bandwidth really
does not matter much. The test gear *assumes* (by design) that the
reference signal going
into the “ref in” jack is not very clean. It does various tricks with
filters and PLL’s to “scrub”
the input.

If we are talking about the reference into one side of a phase noise test
set, then
the situation is a bit different. The test set is simply going to tell me
what the combined
noise is on the two inputs. If one is significantly more noisy than the
other, that’s pretty
much all I will see. In this case, my answer is “don’t use a distributed
signal”. Use a
stand alone source as your reference and isolate it from the rest of the
world.

In any case, making a super duper distribution gizmo and feeding it with a
noisy signal
is not going to make the signal any better. Most GPSDO’s have relatively
noisy outputs.
Some are better than others. None that I have seen on the surplus market
are what
I would call quiet at the output jack of the GPSDO. They either have an
ocean of spurs
or a lot of phase noise. Some have both ….

Any time you boost a bunch of signals up to high levels, you create “crud”
running around your
lab / shack. One of the most basic questions should always be “do I really
need this signal?”. Next
should be “how can I have a shorter run?”.  I have many pieces of gear
that are rarely used.
They use odd references. When I need to use them I rig a reference. That
gets shut down
once the gear goes back to storage. …. no more birdies every 100 KHz …. No
need for
tripple shielded coax ….

Simple answer:

Square up the 10 MHz (or whatever) by matching it into a 5.5 V powered
high speed CMOS
gate. The NC7SZ series is one of many families you can use. A NC7SZ125 is
not a bad gate
to pick. Distribute the square wave to however many output amps as you
need. Each one
is another of the same gates with the output matched via a 50 ohm to 50
ohm lowpass Tee network
with a low Q ( < 2). Likely pad down the output a bit to keep it at a
rational level.  Build up however
many you need for however many frequencies you require. Very normal linear
regulator chips
are fine for the power. Careful bypassing and solid ground planes are
always a good idea.
Parts cost wise, postage is likely to cost you more than the components.
There are …. errr…
many thousands …. of multi output amps of this basic  design out there ….
they seem to
work pretty well.

Yes, there are *lots* of possible twists and turns to this. I’m only
guessing about the gear you
are trying to run and what you are trying to do with it.

Bob






On Oct

Re: [time-nuts] HP 3048 question: how to export graphs?

[John Miles]

I don't believe there's a way to save images from within HTBasic, although 
there certainly should be.  I use the "Snipping Tool" accessory in Windows 7 
for that sort of thing.  It probably exists in all versions of WIndows 
including 10, but who knows what they call it these days.  

 If you create a shortcut key for the tool, it's easy to invoke whenever 
needed.   Hit ctrl-shift-C (in my case), wait for the tool to come up, and drag 
a box around the graph or other content to be cropped and saved.  The image can 
then be saved as a .PNG, .GIF, or .JPG, or pasted directly into a document.

The RESU files saved by 3048A.BAS are similar to the .res files saved by 
PN3048, and PN3048 can load them directly if you select 'All files' in the 
file-open dialog.   You can then save the graph or the entire window as a .PNG 
file.  TimeLab ( http://www.miles.io/timelab/beta.htm ) can also import them 
(File->Import .RES or .PNP noise data) and save images (File->Save image or 
.TIM file or File->Copy image to clipboard).  But if all you want is a .PNG, 
the snipping tool is much easier than dealing with any of this stuff.

-- john, KE5FX

> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of
> Richard (Rick) Karlquist
> Sent: Sunday, October 15, 2017 12:03 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] HP 3048 question: how to export graphs?
> 
> I am running an HP 3048 under HTBasic and I
> have a nice looking phase noise graph on the
> screen.  I want to export the graph to the
> world outside of RMB...

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Re: [time-nuts] 5071A Reference Oscillator ?

[John Miles]

> One of the few things I dont have a manual for
> 
> Can anyone tell me if there is an HP model number for the Reference
> Oscillator Assembly (A19) in the 5071A? Might be a  a 10544A ?
> 

The OCXO was 05071-60219.  As Rick says, it was a modified 10811.  The 10544 
was long gone by the 5071A's time.

See the Mejia-Norton document in the ko4bb.com Manuals section for the exact 
specs...

-- john, KE5FX
Miles Design LLC

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Re: [time-nuts] sine to square wave circuits - performance data?

[John Ackermann N8UR]

The inductor in the T2-Mini is nothing special.

On Oct 4, 2017, 12:57 PM, at 12:57 PM, Attila Kinali  wrote:
>On Wed, 4 Oct 2017 12:02:35 +1300 (NZDT)
>Bruce Griffiths  wrote:
>
>> I could measure the PN of the TAPR variant of the Wenzel circuit
>> as well as the PN of the comparator based circuit (with CMOS output
>buffer).  
>
>
>BTW: one thing that has been bothering me with the TAPR variant of the
>Wenzel circuit is the 100µH inductor in the tail of the diff-pair.
>As it presents an impedance of approximately 6k at 10MHz it is cruical
>to the working of the diff-pair (which would otherwise be just two
>independent transistors). But I was unable to find a 100µH inductor
>with a self-resonance frequency significantly higher than 10MHz.
>Quite to the contrary, most seem to mingle around 1MHz. This poses
>two questions:
>
>1) does the TADD2 mini use a special inductor?
>
>and
>
>2) Given the 100µH inductor has an SFR somewhere in the range of 1-5MHz
>and is likely to have significant core losses around and/or above
>10MHz,
>doesn't this limit the performance of the circuit quite significantly?
>
>I have been thinking of replacing the inductor with a current source
>(simple current mirror) and at least in the spice simulations it looks
>decent. No idea of the noise performance, though.
>
>   Attila Kinali
>-- 
>It is upon moral qualities that a society is ultimately founded. All 
>the prosperity and technological sophistication in the world is of no 
>use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] sine to square wave circuits - performance data?

[John Miles]

> Do you recall what the amplitude of the input signal to the Wenzel shaper
> was?
> 
> Since I used a 1:2 (3dB) terminated splitter for my measurements the input
> to the splitter is the same as the Timepod reference signal amplitude
> 

I was using a similar setup, so the shaper input would have been +4 to +5 dBm.  
My intention at the time was probably to feed it a signal comparable to the 
lowest levels commonly seen from typical 10 MHz sources.  It may or may not do 
better at higher input levels, but it'll obviously get worse once the level 
goes below a certain point.

-- john, KE5FX
Miles Design LLC


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Re: [time-nuts] sine to square wave circuits - performance data?

[John Miles]

> I have measured the PN of the LTC6957-4 at 10MHz.
> 
> I could measure the PN of the TAPR variant of the Wenzel circuit as well as
> the PN of the comparator based circuit (with CMOS output buffer).
> 

These plots came from the Wenzel diff-amp shaper:
http://www.ke5fx.com/wenzel_resid_PN.png
http://www.ke5fx.com/wenzel_resid_ADEV.png

I don't recall many details of the test setup, or how faithful my 
implementation of the shaper was to Charles W.'s app note, but this is 
representative of several plots I have lying around. Not bad performance at all 
for the cost/complexity involved. 

-- john, KE5FX
Miles Design LLC

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Re: [time-nuts] Weird GPSDO behavior

[John Hawkinson]

I would have thought the easy test is to run the GPSDO on battery power 
(perhaps with a UPS). Maybe that's not so easy?

--jh...@mit.edu
  John Hawkinson
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Re: [time-nuts] PN on internal/external references and Cross correlation

[John Miles]

> Thanks for clarifying this issue! I may use references with close-in PN
> (1Hz-1kHz) 10 dB noisier than the DUT, however as you said it may
> require an overnight run for 1 Hz offset, which isn't the nice part... I
> assume then that speeding up the measurement process can only be
> obtained using references sources at least quieter than the DUT.

A 10-dB deficit may not be too bad, since the performance improvement isn't 
linear with time.  If your instrument takes 8 hours to drop the measurement 
floor by 20 dB, for instance, it will only take 4 hours to achieve 18.5 dB of 
improvement, or 2 hours for 17 dB.   So if each of the references is 10 dB 
noisier than the DUT, their effect will be mostly gone after 2 hours.

-- john, KE5FX
Miles Design LLC


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Re: [time-nuts] PN on internal/external references and Cross correlation

[John Miles]

> In a PN measurement system with a dual channel cross correlation is there a
> simple rule of thumb for how low should be the PN of the (external)
> references compared to the DUT? (even with a 20 dB noise floor
> improvement with 1 cross correlations)

If you have two references, then it's OK for them to be somewhat noisier than 
the DUT.  Their contribution will average out of the cross spectrum over time 
just like the rest of the instrument noise.  There is no penalty in accuracy, 
only in measurement time.

Given a choice, you're better off using references with good close-in noise 
performance rather than good broadband performance, since it takes longer for 
those FFT segments to converge.  You can achieve 20 dB of noise floor 
improvement at offsets >10 kHz within a few minutes, but a 20-dB improvement at 
1 Hz might require running overnight or even longer.

> In the case of the references
> have an equal noise contribution compared to the DUT will the results suffer
> from loss of accuracy?

With two references it's not a problem.  If you have only one reference source 
-- or if your measurement setup doesn't do cross correlation at all -- then the 
reference needs to be at least 10 dB quieter than the expected DUT performance 
to keep its contribution below 0.5 dB.  

-- john, KE5FX
Miles Design LLC


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[time-nuts] Symmetricom S200 Antenna Disgnostic and Replacement Recommendation

[John Laur]

All,

Does anyone have a good recommendation for an inexpensive but effective
replacement antenna for a Symmetricom/Microsemi S200 or S250? These units
use a 12V receiver and also have an antenna open/good/short status alarm.

My antenna recently went to showing open alarm and the receiver will no
longer lock. I purchased an inexpensive marine-type antenna which appeared
to be 12V tolerant but triggers the short alarm.

I know that it is possible that the antenna could be fine like this and the
alarm could be ignored, but even still I would prefer that the antenna
current alarm remain functional. Does anyone have a recommendation for an
effective but inexpensive antenna that tolerates 12V and consumes an
appropriate amount of current to pacify the alarm? In the event that my
antenna was damaged by something like a nearby lightning strike that also
could have damaged the receiver, I would prefer to at least test with an
appropriate antenna before either risking more damage or deciding to
attempt a more invasive repair.

Thanks for any info!
John Laur K5IT
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