Re: [time-nuts] EFOS Maser turns 34!

[Poul-Henning Kamp]

In message <8ee9c792-a2f6-402d-9d07-f8929f656...@gmail.com>, John Ponsonby writ
es:

>   It turns out that the resonant frequency of the cavity is
> much more critically dependent on its diameter than on its length.

Copper has a quite high temperature expansion, so could you servo
that via the cavity temperature ?


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Line Voltage - USA

[Poul-Henning Kamp]

In message 

[time-nuts] Tom's PICDiv?

[Bob Stewart]

Hi all,
I was wondering if anyone makes a nice, complete unit from one of Tom's 
PICDivs; preferably with an external 10MHz input, a 10MHz output and a 1PPS 
output?  It would be nice if it also accepted a 1PPS in to sync the PIC's 
output to an external 1PPS source, but that's not a necessity.  I've got 
something kludged together here that I can drive from my Cs standard for 
testing, but I was hoping for something a bit more purpose made if anyone makes 
one?  Not looking for a kit or just a board, nor do I have any interest in 
making/marketing such a unit.

Bob -
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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Re: [time-nuts] Line Voltage - USA

[Bill Byrom]

That sounds like a dangerous idea to me. Lightning arrestors at service
entrances are designed to crowbar only for a cycle or so. As mentioned
earlier in this thread, residential distribution in the US nearly always
consists of a center-tapped balanced feed with the center tap grounded.
If you placed a separate AC crowbar on each 120 V leg to neutral, the
first one to trip would momentarily create a higher than normal voltage
(transient and cycle-to-cycle) on the other 120V leg until the
distribution transformer opens (or a wire melts). If the crowbar wasn't
designed correctly you could create a house fire around the service
entrance. I would let the utility company and the National Electric Code
be the guide, as legally required.


You can purchase voltage regulators or line conditioners (the names are
not very precise) which can prevent overvoltage conditions on a circuit
or even the whole house. A UPS or active line conditioner can be used to
provide voltage stability on a cycle to cycle basis. There is no reason
to kill the power to you and your neighbors for what could be many hours
during very cold or hot conditions at night just because the line
voltage is temporarily high at your house. :)
--

Bill Byrom N5BB







On Wed, Jan 4, 2017, at 06:56 PM, Bill Hawkins wrote:

> Wonder if these cases could be used on social media to create enough

> fear that there would be a market for AC crowbars capable of blowing

> line/pole transformer HV fuses? There's a few hits with Google, mostly
> for DC crowbars. Too bad relays are so slow.

> 

> Bill Hawkins


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Re: [time-nuts] Temperature (environmental) sensors

[albertson . chris]

Right on the page at adafruit there is a downloads link. This gets you to 
software read data from the board.   It uses SPI

Use one of those $3 arduino nanos to talk spi to the sensor and USB to a 
computer.   The linked software does that

> On Jan 4, 2017, at 11:32 AM, Dan Kemppainen  wrote:
> 
> does anyone on the list have 16Bit PIC code (pic24/dsPIC) C code for reading 
> these BME280 sensors laying around?
> 
> They really look like a neat little unit. Thanks to all for the heads up on 
> these ones!
> 
> Dan
> 
> 
> 
> 
>> 
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Re: [time-nuts] Temperature (environmental) sensors

[Didier Juges]

I have C code (for the 8051) that is simply the translation of what's in the 
app note. It does temperature and humidity but not the barometric pressure (no 
double precision float on that compiler).

Works exactly as advertised. I have two.

You can see one in action here:

http://www.ko4bb.com/tps/plottemp.php?file=D8B04CF343D6.csv=day

This is my wife's green house, with temperature in C and F and humidity.

Let me know if you are interested.

Didier KO4BB 


On January 4, 2017 1:32:24 PM CST, Dan Kemppainen  
wrote:
>Hi All,
>
>Just ordered a few of these BME280 sensor boards. Also ordered a FTDI 
>C232HM cable to try to SPI or to bit-bang data from the board directly 
>to the PC. If a PIC or similar is required, does anyone on the list
>have 
>16Bit PIC code (pic24/dsPIC) C code for reading these BME280 sensors 
>laying around?
>
>They really look like a neat little unit. Thanks to all for the heads
>up 
>on these ones!
>
>Dan
>
>
>
>
>On 1/4/2017 12:00 PM, time-nuts-requ...@febo.com wrote:
>> Message: 7
>> Date: Wed, 4 Jan 2017 09:53:24 -
>> From: "David J Taylor" 
>> To: "Discussion of precise time and frequency measurement"
>>  
>> Subject: Re: [time-nuts] Temperature (environmental) sensors
>> Message-ID: <076CCA551DC142C2A8D93CF02A4AD1A3@Alta>
>> Content-Type: text/plain; format=flowed; charset="UTF-8";
>>  reply-type=original
>>
>> I like the Bosch BME280 conneced to a Raspberry PI.
>>
>https://learn.adafruit.com/adafruit-bme280-humidity-barometric-pressure-temperature-sensor-breakout/pinouts
>>
>https://github.com/adafruit/Adafruit_Python_BME280/blob/master/README.md
>> --   Björn
>> 
>>
>> Some performance plots are here, with some comparison between the
>pressure
>> readings from various sensors.
>>
>>   http://www.satsignal.eu/mrtg/performance_air_temp.php
>>
>> This is on mixed Windows/Linux platforms.
>>
>> Cheers,
>> David
>> -- SatSignal Software - Quality software written to your requirements
>> Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk
>> Twitter: @gm8arv
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-- 
Sent from my Moto-X wireless tracker while I do other things.
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Re: [time-nuts] Line Voltage - USA

[Bill Hawkins]

Wonder if these cases could be used on social media to create enough
fear that there would be a market for AC crowbars capable of blowing
line/pole transformer HV fuses? There's a few hits with Google, mostly
for DC crowbars. Too bad relays are so slow.

Bill Hawkins


-Original Message-
From: Jeff AC0C
Sent: Wednesday, January 04, 2017 10:42 AM

The electric company in OKC repaired a pole problem at my parents house
there a few years back.  Somehow they managed to hook up the 240 across
a single leg of the 120.  Fried most of the electrical stuff in the
house and caused enough damage to the house to require a complete
rewiring.  Parents lived in a motel for about a month while the work was
done.  The insurance company and the utility were transparent, covering
all costs including replacement with new similar products without issue
(other than the inconvenience).  I think the electric company was
especially glad that a fire did not result and there was no legal action
as a result.

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-Original Message-
From: Hal Murray
Sent: Wednesday, January 04, 2017 2:42 AM

> Did the utility replace the damaged equipment?

A friend lived in a building when the city crew working on a transformer
put 440 on the line.  It blew out all the electronics in 12 condos -
mostly TVs.
I think toasters and refrigerators were OK.  There wasn't any question
that the city was at fault.  I don't remember how much paperwork they
had to go through to get reimbursed.  It might get sticky for something
like a time-nut with a lot of used gear that may not be easy to replace
at the original price.  (Could be a good excuse to clean up and start
over.)


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Re: [time-nuts] New stuff in my Tindie store

[Nick Sayer via time-nuts]

> On Dec 26, 2016, at 7:40 PM, Nick Sayer via time-nuts  
> wrote:
> 
> 
> The second one will be up next week, and it’s a simple GPS clock.

The listing for the clock is live now: 
https://www.tindie.com/products/nsayer/gps-clock/
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Re: [time-nuts] σ vs s in ADEV

[Tom Van Baak]

Hi Attila,

The plain ADEV calculation is essentially a measure of unexpected or unwanted 
drift in frequency; which is the 1st difference of frequency error; the 2nd 
difference of phase error; the 3rd difference in clock time itself.

When measuring the quality of a clock, the key idea is that initial phase 
doesn't matter (you can always manually set the time), and even initial 
frequency doesn't matter (you can often adjust the rate: whether pendulum, 
quartz or atomic clock), and so a more honest measure of intrinsic timekeeper 
stability is its ability to maintain frequency; that is, statistically 
speaking, the lower the change in frequency, tau to tau, the better. Change in 
frequency is frequency drift.

If you have N phase samples, you get N-1 frequency samples and N-2 drift 
samples. The standard ADEV calculation is simply based on the mean of those 
drift samples. (and you know Hadamard takes this one step deeper).

If you look a the code at http://leapsecond.com/tools/adev_lib.c you'll see I 
avoid the confusing issue of N-1, N, N+1 and simply count the number of terms 
in the rms sum. Not only does that give the correct result but IMHO it make it 
clear what is being averaged. The code passes the official NBS ADEV sample 
suite, agrees with Bill's Stable32, is used in John's TimeLab, and also Mark's 
Lady Heather.

I've never quite understood the pedantic separation of "sample" and 
"population" mean that statistic textbooks and academics love to discuss. They 
clearly have never measured oscillators. In my experience if you think there's 
an important difference between N and N-1, then that's nature's way of telling 
you to go back to sleep and wait until tomorrow when you have more data. If 
your N is too small your ADEV wanders all over the place (TimeLab is good at 
displaying this in real-time) -- meaning that the distinction between sample 
(n-1) and population (n) mean is beyond ridiculous; even if there's a "correct" 
textbook answer.

/tvb

- Original Message - 
From: "Attila Kinali" 
To: "Discussion of precise time and frequency measurement" 
Sent: Wednesday, January 04, 2017 12:12 PM
Subject: [time-nuts] σ vs s in ADEV


Hi,

A small detail caught my eye, when reading a paper that informally
introduced ADEV. In statistics, when calculating a variance over
a sample of a population the square-sum is divided by (n-1)(denoted by s in
statistics) instead of (n) (denoted by σ) in order to account for a small bias
the "standard" variance introduces 
(c.f. https://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation )
In almost all literature I have seen, ADEV is defined using an average,
i.e. dividing by (n) and very few use (n-1). 

My question is two-fold: Why is (n) being used even though it's known
to be an biased estimator? And why do people not use s when using (n-1)?

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] WWVB Simulator

[David]

Not all PC audio hardware includes such a low high frequency cutoff.

http://www.clarisonus.com/Research%20Reports/RR001-SoundCardEval/RR001-PCsoundCards.html

Based on the above review, the following cards which are still
available have a response that extends significantly above 60kHz:

http://www.m-audio.com/products/view/audiophile-192
http://www.lynxstudio.com/product_detail.asp?i=11
http://www.lynxstudio.com/product_detail.asp?i=12

On Wed, 4 Jan 2017 21:21:22 + (UTC), you wrote:

>A PC can certainly generate a lot of frequencies. But if you want to use the 
>audio channels at 60KHz there is a little problem. There is a brick wall 
>filter in the audio channel set at about 25 KHz. 
>
>Now I could set up the audio to output 15 KHz I and Q and mix it (quadrature 
>mixer) with 45 KHz X 4 (precision source)  to get 60 KHz. And then filter it 
>to get the 60 KHz. Which requires some op amps. And filters. A precision 45 
>KHz source. A gray code counter (divide by 4).  And stuff. 
>
>Easier to work at DC (my "audio" signal) and mix that up to 60 KHz directly. 
>Besides. I do like designing and building hardware.  Engineering is the art of 
>making what you want from what you can get at a profit. 
>I like Polywell Fusion.
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Re: [time-nuts] WWVB Simulator

[Hal Murray]

time-nuts@febo.com said:
> A PC can certainly generate a lot of frequencies. But if you want to use the
> audio channels at 60KHz there is a little problem. There is a brick wall
> filter in the audio channel set at about 25 KHz.  

The filters I'm familiar with in audio gear scale with the frequency you are 
clocking them at.

Is it possible/reasonable to overclock the audio output section of a typical 
OS?


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] WWVB Simulator

[M. Simon via time-nuts]

A PC can certainly generate a lot of frequencies. But if you want to use the 
audio channels at 60KHz there is a little problem. There is a brick wall filter 
in the audio channel set at about 25 KHz. 

Now I could set up the audio to output 15 KHz I and Q and mix it (quadrature 
mixer) with 45 KHz X 4 (precision source)  to get 60 KHz. And then filter it to 
get the 60 KHz. Which requires some op amps. And filters. A precision 45 KHz 
source. A gray code counter (divide by 4).  And stuff. 

Easier to work at DC (my "audio" signal) and mix that up to 60 KHz directly. 
Besides. I do like designing and building hardware.  Engineering is the art of 
making what you want from what you can get at a profit. 
I like Polywell Fusion.
 

On Wednesday, January 4, 2017 7:48 AM, Chris Albertson 
 wrote:
 
 

 You don't need to tie up a PC.    It could likely output the WWVB
signal while it was also surfing the web and reading emails.  60KHz
is NOTHING compared to displaying a you-tube video

In fact I bet your 48MHz uP could directly synthesize the signal.
Look at the ratio of 48 MHz / 60 KHz.  The uP can execute about 800
instructions during one cycle of a 60 KHz courier.    Your PC can do
a million operations during that same one cycle.

But go ahead.  I'm subscribed to another list dedicated to building
stuff with vacuum tubes.  I kind of enjoy building with that
technology.    I used to like building with 70'd vintage 74xxx TTL.
city is like lego blocks for big kids.  But as a practical matter if
you just want something to work, 21st century technology gets the job
done.




On Tue, Jan 3, 2017 at 6:49 PM, M. Simon via time-nuts
 wrote:
> Sure. I considered software. But I'm a hardware guy. I like designing boards. 
> The rig was designed to do amplitude and phase simply. The final design will 
> have a $5 48 MHz microprocessor included. I'm using that one because of speed 
> and memory. When that proves out I might redesign for a $2 24 MHz processor. 
> Onesies prices at Mouser
>
> Besides the hardware better illustrates the concepts than software. And I 
> don't have to tie up a PC if I don't want to.
>
> I haven't priced everything out yet because the design is not done. I'd be 
> surprised if the cost was over $20 in parts for everything - power supply not 
> included. PCB extra.
>
> Feel free to send this along to the list if you are inclined.
>
> Simon
>  Engineering is the art of making what you want from what you can get at a 
>profit.
> I like Polywell Fusion.
>
>
>    On Tuesday, January 3, 2017 5:53 AM, Hal Murray  
>wrote:
>
>
>
>
> time-nuts@febo.com said:
>> I have come up with a ridiculously simple WWVB simulator that simulates both
>> the AM modulation and the BPSK modulation.
>
> Did you consider software?
>
> Is the audio on a Raspberry Pi fast enough?
>
> I haven't looked at any details, but you can get ARM CPUs for ballpark of $5
> on eBay.  There is a good chance that one of their IO devices will let you
> send raw bits via a DMA channel.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



-- 

Chris Albertson
Redondo Beach, California

 
   
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Re: [time-nuts] WWVB Simulator

[Vlad]

Here is some nice work which was done for DCF77, Its not the same as 
WWVB, but worth to have a look how it was done.


http://endorphino.de/projects/electronics/timemanipulator/index_en.html



On 2017-01-04 14:29, paul swed wrote:

Simon
Like you I tend to like hardware. But today complete micros are so 
cheap
and powerful they make life easy. Heck a bit to complex use 2 or 3. I 
like

to follow the  "Get-er-done" philosophy.

That said search the time-nuts archive for the wwvb cheatn d-psk-r. It
knows how to create the bpsk time stream aligned to wwvb then flips a 
BPSK

switch to remove the BPSK. This allows all of the old phase tracking
receivers work without modifications.
I used an Arduino $8 maybe and shared all of the details and software 
with
the group. It preserves the old AM for radios that need that 
modulation.
So a corrected wwvb signal can be had for cheap and it works very well 
here

on the east coast. As well as wwvb ever did.

Have fun and use whatever technology you like as you are the do-er, you 
get

to choose.

Regards
Paul
WB8TSL

On Wed, Jan 4, 2017 at 2:48 AM, Chris Albertson 


wrote:


You don't need to tie up a PC.It could likely output the WWVB
signal while it was also surfing the web and reading emails.   60KHz
is NOTHING compared to displaying a you-tube video

In fact I bet your 48MHz uP could directly synthesize the signal.
Look at the ratio of 48 MHz / 60 KHz.  The uP can execute about 800
instructions during one cycle of a 60 KHz courier. Your PC can do
a million operations during that same one cycle.

But go ahead.  I'm subscribed to another list dedicated to building
stuff with vacuum tubes.  I kind of enjoy building with that
technology.I used to like building with 70'd vintage 74xxx TTL.
city is like lego blocks for big kids.   But as a practical matter if
you just want something to work, 21st century technology gets the job
done.




On Tue, Jan 3, 2017 at 6:49 PM, M. Simon via time-nuts
 wrote:
> Sure. I considered software. But I'm a hardware guy. I like designing
boards. The rig was designed to do amplitude and phase simply. The 
final
design will have a $5 48 MHz microprocessor included. I'm using that 
one
because of speed and memory. When that proves out I might redesign for 
a $2

24 MHz processor. Onesies prices at Mouser
>
> Besides the hardware better illustrates the concepts than software. And
I don't have to tie up a PC if I don't want to.
>
> I haven't priced everything out yet because the design is not done. I'd
be surprised if the cost was over $20 in parts for everything - power
supply not included. PCB extra.
>
> Feel free to send this along to the list if you are inclined.
>
> Simon
>  Engineering is the art of making what you want from what you can get at
a profit.
> I like Polywell Fusion.
>
>
> On Tuesday, January 3, 2017 5:53 AM, Hal Murray <
hmur...@megapathdsl.net> wrote:
>
>
>
>
> time-nuts@febo.com said:
>> I have come up with a ridiculously simple WWVB simulator that simulates
both
>> the AM modulation and the BPSK modulation.
>
> Did you consider software?
>
> Is the audio on a Raspberry Pi fast enough?
>
> I haven't looked at any details, but you can get ARM CPUs for ballpark
of $5
> on eBay.  There is a good chance that one of their IO devices will let
you
> send raw bits via a DMA channel.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
> and follow the instructions there.



--

Chris Albertson
Redondo Beach, California
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--
WBW,

V.P.
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Re: [time-nuts] σ vs s in ADEV

[Magnus Danielson]

Hi Attila,

On 01/04/2017 09:12 PM, Attila Kinali wrote:

Hi,

A small detail caught my eye, when reading a paper that informally
introduced ADEV. In statistics, when calculating a variance over
a sample of a population the square-sum is divided by (n-1)(denoted by s in
statistics) instead of (n) (denoted by σ) in order to account for a small bias
the "standard" variance introduces
(c.f. https://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation )
In almost all literature I have seen, ADEV is defined using an average,
i.e. dividing by (n) and very few use (n-1).

My question is two-fold: Why is (n) being used even though it's known
to be an biased estimator? And why do people not use s when using (n-1)?


First off all, you need keep number of phase samples (N) or number 
frequency samples (M) separate.


As you derivate the phase samples, you loose the phase bias from the 
samples, so the remaining degree of freedom becomes one less. This is 
the same as number of frequency samples, so any average will be (N-1) 
which is the number of frequency samples M, so M=N-1 is motivated both ways.


Now, as you do an Allan Deviation/Variance estimator, you do second 
derivation, so they the also the frequency bias gets derivated out, and 
another degree of freedom is lost, so as you average you have only M-1 
drift estimates which is what you average over, or N-2.


The ADEV core function is just the square of second derivate of phase, 
and then you do an ensemble average over those squares.


No wonders the formulas become like these:
https://en.wikipedia.org/wiki/Allan_variance#Fixed_.CF.84_estimators

There is nothing magic really.

A hint for the use of s, consider the frequency stability. See Allan 1966.

Cheers,
Magnus
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[time-nuts] σ vs s in ADEV

[Attila Kinali]

Hi,

A small detail caught my eye, when reading a paper that informally
introduced ADEV. In statistics, when calculating a variance over
a sample of a population the square-sum is divided by (n-1)(denoted by s in
statistics) instead of (n) (denoted by σ) in order to account for a small bias
the "standard" variance introduces 
(c.f. https://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation )
In almost all literature I have seen, ADEV is defined using an average,
i.e. dividing by (n) and very few use (n-1). 

My question is two-fold: Why is (n) being used even though it's known
to be an biased estimator? And why do people not use s when using (n-1)?

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] Temperature (environmental) sensors

[Dan Kemppainen]

Hi All,

Just ordered a few of these BME280 sensor boards. Also ordered a FTDI 
C232HM cable to try to SPI or to bit-bang data from the board directly 
to the PC. If a PIC or similar is required, does anyone on the list have 
16Bit PIC code (pic24/dsPIC) C code for reading these BME280 sensors 
laying around?


They really look like a neat little unit. Thanks to all for the heads up 
on these ones!


Dan




On 1/4/2017 12:00 PM, time-nuts-requ...@febo.com wrote:

Message: 7
Date: Wed, 4 Jan 2017 09:53:24 -
From: "David J Taylor" 
To: "Discussion of precise time and frequency measurement"

Subject: Re: [time-nuts] Temperature (environmental) sensors
Message-ID: <076CCA551DC142C2A8D93CF02A4AD1A3@Alta>
Content-Type: text/plain; format=flowed; charset="UTF-8";
reply-type=original

I like the Bosch BME280 conneced to a Raspberry PI.
https://learn.adafruit.com/adafruit-bme280-humidity-barometric-pressure-temperature-sensor-breakout/pinouts
https://github.com/adafruit/Adafruit_Python_BME280/blob/master/README.md
--   Björn


Some performance plots are here, with some comparison between the pressure
readings from various sensors.

  http://www.satsignal.eu/mrtg/performance_air_temp.php

This is on mixed Windows/Linux platforms.

Cheers,
David
-- SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv

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Re: [time-nuts] WWVB Simulator

[paul swed]

Simon
Like you I tend to like hardware. But today complete micros are so cheap
and powerful they make life easy. Heck a bit to complex use 2 or 3. I like
to follow the  "Get-er-done" philosophy.

That said search the time-nuts archive for the wwvb cheatn d-psk-r. It
knows how to create the bpsk time stream aligned to wwvb then flips a BPSK
switch to remove the BPSK. This allows all of the old phase tracking
receivers work without modifications.
I used an Arduino $8 maybe and shared all of the details and software with
the group. It preserves the old AM for radios that need that modulation.
So a corrected wwvb signal can be had for cheap and it works very well here
on the east coast. As well as wwvb ever did.

Have fun and use whatever technology you like as you are the do-er, you get
to choose.

Regards
Paul
WB8TSL

On Wed, Jan 4, 2017 at 2:48 AM, Chris Albertson 
wrote:

> You don't need to tie up a PC.It could likely output the WWVB
> signal while it was also surfing the web and reading emails.   60KHz
> is NOTHING compared to displaying a you-tube video
>
> In fact I bet your 48MHz uP could directly synthesize the signal.
> Look at the ratio of 48 MHz / 60 KHz.  The uP can execute about 800
> instructions during one cycle of a 60 KHz courier. Your PC can do
> a million operations during that same one cycle.
>
> But go ahead.  I'm subscribed to another list dedicated to building
> stuff with vacuum tubes.  I kind of enjoy building with that
> technology.I used to like building with 70'd vintage 74xxx TTL.
> city is like lego blocks for big kids.   But as a practical matter if
> you just want something to work, 21st century technology gets the job
> done.
>
>
>
>
> On Tue, Jan 3, 2017 at 6:49 PM, M. Simon via time-nuts
>  wrote:
> > Sure. I considered software. But I'm a hardware guy. I like designing
> boards. The rig was designed to do amplitude and phase simply. The final
> design will have a $5 48 MHz microprocessor included. I'm using that one
> because of speed and memory. When that proves out I might redesign for a $2
> 24 MHz processor. Onesies prices at Mouser
> >
> > Besides the hardware better illustrates the concepts than software. And
> I don't have to tie up a PC if I don't want to.
> >
> > I haven't priced everything out yet because the design is not done. I'd
> be surprised if the cost was over $20 in parts for everything - power
> supply not included. PCB extra.
> >
> > Feel free to send this along to the list if you are inclined.
> >
> > Simon
> >  Engineering is the art of making what you want from what you can get at
> a profit.
> > I like Polywell Fusion.
> >
> >
> > On Tuesday, January 3, 2017 5:53 AM, Hal Murray <
> hmur...@megapathdsl.net> wrote:
> >
> >
> >
> >
> > time-nuts@febo.com said:
> >> I have come up with a ridiculously simple WWVB simulator that simulates
> both
> >> the AM modulation and the BPSK modulation.
> >
> > Did you consider software?
> >
> > Is the audio on a Raspberry Pi fast enough?
> >
> > I haven't looked at any details, but you can get ARM CPUs for ballpark
> of $5
> > on eBay.  There is a good chance that one of their IO devices will let
> you
> > send raw bits via a DMA channel.
> >
> >
> >
> > --
> > These are my opinions.  I hate spam.
> >
> >
> >
> >
> >
> >
> >
> > ___
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> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Line Voltage - USA

[Van Horn, David]

HAHAHAHAHAHA.   No,

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jeremy Nichols
Sent: Tuesday, January 3, 2017 11:48 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Line Voltage - USA

Did the utility replace the damaged equipment?


On Tue, Jan 3, 2017 at 9:33 PM Van Horn, David < 
david.vanh...@backcountryaccess.com> wrote:

> I once had some odd equipment failures which we found out were caused 
> by the line voltage being at 142V.
>
> This was in the mid 80's in Costa Mesa CA.  The tech they sent out 
> told me they had us on the wrong transformer tap.
>
>
>
> Lowest I've seen was 70V in Hawaii, with everyone coming home about 
> 5PM and switching on air conditioners.  We had to run our TV on a 
> variac and adjust the voltage to keep the picture from shrinking.
>
>
>
> Since those days, that's the numbers I design equipment to, if it is 
> to run from 115V supplies.  That rule has never let me down.
>
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> --
Sent from Gmail Mobile
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Re: [time-nuts] Line Voltage - USA

[Jeff AC0C]

The electric company in OKC repaired a pole problem at my parents house 
there a few years back.  Somehow they managed to hook up the 240 across a 
single leg of the 120.  Fried most of the electrical stuff in the house and 
caused enough damage to the house to require a complete rewiring.  Parents 
lived in a motel for about a month while the work was done.  The insurance 
company and the utility were transparent, covering all costs including 
replacement with new similar products without issue (other than the 
inconvenience).  I think the electric company was especially glad that a 
fire did not result and there was no legal action as a result.


73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-Original Message- 
From: Hal Murray

Sent: Wednesday, January 04, 2017 2:42 AM
To: Discussion of precise time and frequency measurement
Cc: hmur...@megapathdsl.net
Subject: Re: [time-nuts] Line Voltage - USA


Did the utility replace the damaged equipment?


A friend lived in a building when the city crew working on a transformer put
440 on the line.  It blew out all the electronics in 12 condos - mostly TVs.
I think toasters and refrigerators were OK.  There wasn't any question that
the city was at fault.  I don't remember how much paperwork they had to go
through to get reimbursed.  It might get sticky for something like a 
time-nut

with a lot of used gear that may not be easy to replace at the original
price.  (Could be a good excuse to clean up and start over.)

How much trouble do hams have with their insurance companies?


--
These are my opinions.  I hate spam.



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Re: [time-nuts] Datum GPSDO up and running

[Chris Albertson]

How to know if your 10MHz reference is accurate?If you happen you
have a "known-good" 10MHz reference you compare your new one to the
old one.But lacking and "old one" and any other sophisticated time
interval counters you can get a two channel oscilloscope and put your
10MHz signal on channel A and the a 1 pulse per second chanel on B and
observer the phase.  (where in the 10Mhz sine wave does the leading
edge of the 1PPS cut.Watch his for some time, maybe for hours and
see the the phase is constant.   It is easy to "eyeball" a 45 degree
change.

If the phase remains constant for 1 second the frequency is "good" to
one part in 10 million.  If it stays in phase for 100 seconds the the
frequency is 100x better and so on.

There might be better ways but this is easy to understand and do and
gives a level on confidence because "you see it with your own eyes".

But how do you know the 1PPS is accurate.   Ether just rust the GPS
that what it says "locked" is it locked or spend $15 and buy a second
GPS,

On Tue, Jan 3, 2017 at 8:35 PM, J  wrote:
> Hello fellow time-nuts, newbie here with a couple of questions...
>
>
> I hooked it up to a Datum Starloc II today. After a short delay I see this
> under DSP Mon:
>
>  My objective is to get an accurate 10MHz reference to drive a frequency
> counter, Spectrum Analyzer etc.
>
> Lady Heather is less cooperative, sometimes the GUI is mostly black ,
> while other times I get the following screen, however the clock is not
> updating
>
>
> My first question is how do I know when the GPSDO is actually disciplined,
> i.e. when can I trust the 10MHz output?
>
> There is a fair bit of displayd data on the above screens, some of it self
> explanatory and some of it not, I have not had a chance to read the LH
> manual yet, any obvious tips for getting it up and running with a Starloc
> II?
>
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Datum GPSDO up and running

[Vlad]

On the image from LH, it says "no data from COM port". You probably need 
to do some tweaks to make it works. May be USB2SERIAL is picky. Also it 
worth to check the COM port settings.


I have similar StarLockII which works ok with current LH. The only 
concern is device itself. For some uncertain reason its struggle with 
Survey. The workaround I found - to specify Lat/Long/Alt manually. As 
those one defined - the unit start works perfectly fine. Another little 
"features" for that StartLockII: its always will shows 30 degree 
temperature, and I need to force 1PPS output on (its off by default).
Also I noticed, if its not set (survey, disciplining) - the 10Mhz 
frequency is far from this value.



On 2017-01-03 23:35, J wrote:

Hello fellow time-nuts, newbie here with a couple of questions...


I hooked it up to a Datum Starloc II today. After a short delay I see 
this

under DSP Mon:

 My objective is to get an accurate 10MHz reference to drive a 
frequency

counter, Spectrum Analyzer etc.

​Lady Heather is less cooperative, sometimes the GUI is mostly black 
,

while other times I get the following screen, however the clock is not
updating

​
My first question is how do I know when the GPSDO is actually 
disciplined,

i.e. when can I trust the 10MHz output?

There is a fair bit of displayd data on the above screens, some of it 
self

explanatory and some of it not, I have not had a chance to read the LH
manual yet, any obvious tips for getting it up and running with a 
Starloc

II?

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--
WBW,

V.P.
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Re: [time-nuts] Line Voltage - USA

[Mark Spencer]

Hi David.   I've been told that in Canada the residential supply voltage in a 
neighbourhood is often set to account for the voltage drop in typical 
residential branch circuits. 

The last time the supply voltage in my home was checked it read 125 volts from 
each "service pole" to neutral or 250 volts from service pole to service pole.  
 The voltage on most of my normal branch circuits was typically 122 volts or 
so.   The minor issue for me is that I had a number of dedicated branch 
circuits using larger than normal wire installed that only served one load each 
so the voltage drop on those circuits was negligible.

(I also had the electrical service upgraded which involved larger supply 
conductors to the house which in turn would also have had less voltage drop.)

Good luck.

Mark Spencer



> On Jan 4, 2017, at 5:41 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
>> On 4 January 2017 at 09:34, Poul-Henning Kamp  wrote:
>> 
>> 
>> 
>>> Do you have a reference to this +6%? I've heard from various sources that
>>> the UK is 230 -6%/+10%.  If the EU dictates otherwise, then I'm certainly
>>> over the 6% limit. I may or may not be over the 10% limit.
>> 
>> There was a transitional range, but I belive it has expired.
>> 
>> In 240V countries it was -6%/+10%.
>> 
>> In 220V countries it was -10%/+6%
>> 
>> 
>> --
>> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> 
> I measured my voltage overnight in a peak hold at 255.10 V RMS as close to
> the meter as I could. One of the phases goes via a 100 A switch to the
> garage. I measured on the input of that switch. At 230+10% the maximum
> permissible is 253 V, but mine went to 255.10 V. That was measured on a
> Tektronix DMM916 (40,000 counter) meter, which has not been calibrated
> since I bought it new about 20 years ago.
> 
> I spoke to a friend of mine who worked at the CEGB. He thought I might have
> a tough time getting the electricity company to do anything about 2.1 V if
> it was expensive for them to do.
> 
> I was going to report my findings today at
> 
> http://www.ukpowernetworks.co.uk/internet/en/power-cuts/report-it/report-general-issue-form/
> 
> but having spoken to him, I think I'll monitor for a few more nights and
> see if the problem gets worst than 2.1 V outside the specification.
> 
> The specification of the meter is +/- 0.7% + 4 counts, so measuring at 253
> V (maximum permissible mains voltage), the meter specification is +/- 1.81
> V, so there's no doubt that a measurement of 2.10 V above the maximum with
> a meter that's not recently been calibrated, is a bit on the dubious side.
> 
> Perhaps I need something a bit more convincing before reporting this. I was
> thinking of buying a Keysight handheld, but whilst some are cheap, anything
> with a reasonable amount of functionality is quite expensive.
> 
> Dave
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Re: [time-nuts] EFOS Maser turns 34!

[John Ponsonby]

Re: EFOS Maser turns 34!

In a hydrogen maser the hydrogen atoms have to be confined in a 
storage-bulb within which the oscillating RF magnetic field is all in-phase. 
The storage-bulb has to be made from fused quartz for mechanical stability and 
for very low dielectric loss. The bulb has to be very thin walled, say 1mm to 
keep the dielectric loading and the dielectric loss acceptably small. For an 
active maser the product of the loaded Q-factor of the cavity and the "filling 
factor" of the storage bulb has to exceed a certain minimum value. The filling 
factor is a function of the shape of the storage bulb. Now fused quart is very 
difficult stuff and it can only be worked white hot "in the flame" and very few 
people can do it. It is much more difficult to work than ordinary glass 
blowing. You can't expect a storage-bulb to be made very exactly to an 
engineering drawing. As a result the cavity has to be machined to suit the 
given storage-bulb. The guys at Oscilloquartz told me that after making a lot 
of EFOS m
 asers they eventually got their quartz bulb maker to make the bulbs 
interchangeable between cavities but you can't expect such accuracy if you want 
to make a one-off maser. The first time I had bulbs made the wall thickness was 
far too great. The quartz people said thay had no way of measuring the wall 
thickness. I said I can weigh the bulb and thus deduce the average thickness, 
indeed it was obvious just holding it the hand that it was too heavy.
It turns out that the resonant frequency of the cavity is much more 
critically dependent on its diameter than on its length. So it would be best to 
be able to mount the bulb in the cavity and to measure the resonant frequency 
with the cavity still in the lathe to avoid having to recentre the cavity each 
time one needs to take off a few thou (mils to you in the US). The loaded Q 
should be about 35,000 and the resonance is so narrow that one has to off-set 
tune the cavity so that it is on-tune when it is in vacuum and when it is at 
the chosen working temperature (40°C is a common choice). For an aluminium 
cavity the resonant frequency shifts about one bandwidth per °C of temperature 
change. 
These are matters that need to be understood if one contemplates making 
one's own H-maser.

John P
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Re: [time-nuts] Line Voltage - USA

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 4 January 2017 at 14:25, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

>
> I just phoned Tektronix and they want £160 (GBP) + VAT to calibrate this
> 6000 count handheld DMM. Ouch. I will not bother with that.
>

Sorry, 60,000 touch - 4 3/4 digits.
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Re: [time-nuts] Line Voltage - USA

[Dr. David Kirkby (Kirkby Microwave Ltd)]

Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT,
UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)

On 4 January 2017 at 14:06, David C. Partridge <
david.partri...@perdrix.co.uk> wrote:

> Time to call your supply co.
>
> Dave
>

I think I'll wait a few more days and collect some more data. I'm just too
close to the upper limit to be confident it is not the uncertainty in my
instruments.

I'd also feel a bit happier if the meter was not 20 years old and had a
valid calibration certificate. I just phoned Tektronix and they want £160
(GBP) + VAT to calibrate this 6000 count handheld DMM. Ouch. I will not
bother with that.

Keysight are quoting $210.00 (USD) to do a 6.5 digit 3457A. That's more
attractive, but a 3457A is not really suited to logging data next to an
electricity meter. It is just not practical to get a GPIB connection there.

Dave




>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dr.
> David Kirkby (Kirkby Microwave Ltd)
> Sent: 04 January 2017 13:42
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Line Voltage - USA
>
> I measured my voltage overnight in a peak hold at 255.10 V RMS as close to
> the meter as I could.
>
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Re: [time-nuts] Line Voltage - USA

[David C. Partridge]

Time to call your supply co.

Dave

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dr. David 
Kirkby (Kirkby Microwave Ltd)
Sent: 04 January 2017 13:42
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Line Voltage - USA

I measured my voltage overnight in a peak hold at 255.10 V RMS as close to the 
meter as I could.

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Re: [time-nuts] Line Voltage - USA

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 4 January 2017 at 09:34, Poul-Henning Kamp  wrote:

> 
>
> >Do you have a reference to this +6%? I've heard from various sources that
> >the UK is 230 -6%/+10%.  If the EU dictates otherwise, then I'm certainly
> >over the 6% limit. I may or may not be over the 10% limit.
>
> There was a transitional range, but I belive it has expired.
>
> In 240V countries it was -6%/+10%.
>
> In 220V countries it was -10%/+6%
>
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
>

I measured my voltage overnight in a peak hold at 255.10 V RMS as close to
the meter as I could. One of the phases goes via a 100 A switch to the
garage. I measured on the input of that switch. At 230+10% the maximum
permissible is 253 V, but mine went to 255.10 V. That was measured on a
Tektronix DMM916 (40,000 counter) meter, which has not been calibrated
since I bought it new about 20 years ago.

I spoke to a friend of mine who worked at the CEGB. He thought I might have
a tough time getting the electricity company to do anything about 2.1 V if
it was expensive for them to do.

I was going to report my findings today at

http://www.ukpowernetworks.co.uk/internet/en/power-cuts/report-it/report-general-issue-form/

but having spoken to him, I think I'll monitor for a few more nights and
see if the problem gets worst than 2.1 V outside the specification.

The specification of the meter is +/- 0.7% + 4 counts, so measuring at 253
V (maximum permissible mains voltage), the meter specification is +/- 1.81
V, so there's no doubt that a measurement of 2.10 V above the maximum with
a meter that's not recently been calibrated, is a bit on the dubious side.

Perhaps I need something a bit more convincing before reporting this. I was
thinking of buying a Keysight handheld, but whilst some are cheap, anything
with a reasonable amount of functionality is quite expensive.

Dave
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Re: [time-nuts] Line Voltage - USA

[Bob Camp]

Hi

> On Jan 4, 2017, at 3:42 AM, Hal Murray  wrote:
> 
>> Did the utility replace the damaged equipment?
> 
> A friend lived in a building when the city crew working on a transformer put 
> 440 on the line.  It blew out all the electronics in 12 condos - mostly TVs.  
> I think toasters and refrigerators were OK.  There wasn't any question that 
> the city was at fault.  I don't remember how much paperwork they had to go 
> through to get reimbursed.  It might get sticky for something like a time-nut 
> with a lot of used gear that may not be easy to replace at the original 
> price.  (Could be a good excuse to clean up and start over.)
> 
> How much trouble do hams have with their insurance companies?



In some cases quite a lot. They paid the claim and dropped us. The way
they did it, getting insurance again at a rational price ( < 5X what we had
been paying) was a major pain. We did find a rational company and have
been very happy with them for 40 years now. Each time the guys who 
dropped us call to get us to switch, I tell them the story ….

Bob


> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Line Voltage - USA

[Bob Bownes]

> How much trouble do hams have with their insurance companies?


Typically very little if you have a rider to cover it. Costs a few $ a year

Had my basement flood a number of years back and take out a few k worth of 
vintage computer gear. Not a problem. Covered to replacement cost. 

I have a similar rider to cover TE. The biggest problem is they want all the 
serial #'s, which is a constantly changing target of course. 

Bob
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Re: [time-nuts] Line Voltage - USA

[David C. Partridge]

I think you meant :

In 240V countries it was -10%/+6%.

In 220V countries it was -6%/+10%

Cheers
Dave



-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Poul-Henning 
Kamp
Sent: 04 January 2017 09:34
To: Discussion of precise time and frequency measurement; Dr. David Kirkby 
(Kirkby Microwave Ltd)
Subject: Re: [time-nuts] Line Voltage - USA
There was a transitional range, but I belive it has expired.

In 240V countries it was -6%/+10%.

In 220V countries it was -10%/+6%

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Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

[wb6bnq]

Hello Mathias,

I did mis-speak.  You're correct that only 32 bits (8 hex digits) are 
used to program the DDS chip.  As Mark points out they store a 64 bit 
number and only use 56 bits but he does not elaborate on what is done 
with the bits beyond 32.  Also, after reviewing my comment on the “R” 
number, I see that I did not really convey what my mind was trying to 
compose.


Let me try again and see if I can be clearer.  The Rb physics package, 
itself, is an extremely narrow filter that, under certain conditions, is 
stable to some finite degree with an extremely small drift.  One 
function that can modify the filter is a magnetic field.  By shielding 
all external magnetic influences except for what is purposefully 
introduced, the finite frequency of this filter can be varied by a small 
amount.  This is what the C-field adjustment is doing.


Yes, I do think the outer can covering is a MU-metal shield.  The bottom 
plate where the connector is located is not.


A Rubidium frequency standard is a controllable crystal oscillator fed 
through the Rb filter with a feedback signal from the filter to keep the 
crystal oscillator centered on the Rb filter.  By making very small 
changes to the Rb filter, the crystal oscillator frequency can be 
steered.  Over the long term of many months the Rb filter is more stable 
than a crystal oscillator and thus becomes a higher level standard 
relative to a good crystal oscillator for the long term (months).


In the scheme of things, the Rb filter is narrower than the crystal is 
and these adjustments are very small compared to the Rb frequency (6 
GHz).  So setting the C-field to minimum and adjusting the final output 
frequency with the DDS to the closest step just below the desired 
frequency and then adjusting the C-field, by external comparison, to the 
correct wanted frequency achieves the desired result.


I know the calculator that comes with Windows XP will produce the 
correct mathematical results.  I think the Windows version 7 does the 
same.  I do not have Windows 10 and therefore cannot address that one, 
if there is one.  Even EXCEL spreadsheet does not do the job properly.  
So use caution with your calculations.


However, with all that said, it means nothing if you cannot properly 
measure the final value against an external standard of greater 
accuracy.  Acquiring the equipment to do the external measurements is 
where the real cost comes in.


At the minimum you will need a good “timing” GPSDO and I would highly 
recommend the Trimble Thunderbolt (properly set-up of course).  The next 
item is a good time interval counter like a HP 5335 with GPIB 
capability.  Add a GPIB controller to acquire the needed data, 
specifically one of these two 
https://www.sparkfun.com/search/results?term=gpib would be an excellent 
choice.  With these three items you can make a computer version of a 
strip chart measuring the delta difference in frequence between the 
Thunderbolt and the Rb.


Hopefully the above helps to clear up your query ?

BillWB6BNQ

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Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

[Attila Kinali]

Hoi Mathias!

On Tue, 03 Jan 2017 17:55:32 +0100
Mathias Weyland  wrote:

> On 2017-01-02 12:18, Attila Kinali wrote:

> > May I ask what you want to achieve? Resp. what you need a 10MHz
> > reference for?
> 
> I've always been wondering about those devices, I guess out of pure
> curiosity. Once I learned that those were available for cheap I knew
> I had to get one. But there is a secondary goal, which is to have
> a standard around to check my other gear against every now and then.
> Lately, I've been building and repairing 1.3 GHz radios and lost
> some time because I did not realize how much off both of my service
> monitors where. I could get away with a properly calibrated OCXO
> but the Rb was so much more sexy. So for the most part I need the
> 10 MHz for my own entertainment. :-)

So it's the usual curiosity and the need to have a reference for
your 23cm radios? For the latter I would recommend using a GPSDO
like the Trimble Thunderbolt or the Jacksonlabs Fury. There are also
a few Trimble OEM GPSDOs on ebay, but I have very little knowledge
about those. Advantage of an GPSDO over an Rb is that you know it's
on frequency, while with an Rb it can be off without you knowing it,
if the electronics or the physics package is defect. Of course, the
disadvantages are that most GPSDOs are made for fixed positions and
need a couple of hours of operation to achieve their nominal accuracy.
The short/mid-term stability (between 10s and ~1000s) is also slightly
worse than compared to an Rb.

To get the best of both worlds, there are a couple of GPSD-Rb around,
but commercial ones are usually quite expensive and modifying regular
GPSDOs to Rb is not always possible (at the very least you need to change
the control loop amplification).

BTW: there is a whole new way of looking at statistics of time series
in the field of time and frequency control, which you might find interesting.
The NIST Technote 1337[1] and NIST special publication 1065[2] give a nice
overview of the methods applied.

> > In general I would agree with Bill Houlne's comment that it's 
> > probably
> > easier to use a different reference that already has a 10MHz output.
> > Also keep in mind, that an output that has been designed as an PPS 
> > output
> > might not work as well as an output for 10MHz.
> 
> Yes I agree with that, but I'd also say that based on the reading I
> have done, it would be foolish to assume to get something that is
> guaranteed to work anyway. With all the things that could go wrong in
> general (dead unit, worn-out discharge lamp, drifted sweeping 
> boundaries
> of the oscillator etc.), the 1 pps to 10 MHz conversion for this 
> particular
> model(!) seems fairly straight forward. 

Most of the units sold on ebay work fairly well. And even a worn out
discharge lamp can often be recovered using a hot air gun.

> On the output issue you are rising: This particular model has a DDS 
> that
> takes a 50ish MHz reference and synthesizes another frequency which is
> a power of 2. A coax cable is taking that to a divider board where it's
> brought down to 1 Hz. This is all happening outside of the physics
> package. The plan is to reconfigure the DDS to synthesize 10 MHz 
> instead and bring out that coax. 

Ah..ok. That should work then.

> I would have to open a hole on the face plate
> to do that, but I'm fairly confident that this outer enclosure does not
> contribute to the actual magnetic shielding of the chamber... All
> modifications are strictly outside of the physics package (i.e. no
> water jet cutting...)

Unfortunately, it's not that easy :-)
I don't know the exact construction of the FE-5650, but usually the physics
package is just a normal aluminium microwave cavity, without shielding.
The mu-metal shield is usually the housing of the whole device itself.
Why this kind of construction is usually employed I do not know, but it
makes any modification of the case cumbersome. Mu-metal itself is quite
sensitive to shock and vibration and will lose (part of) its permeability
when being machined. You can of course try to drill as slowly as possible
to keep the heat and vibration at a minimum, but I have no idea how well
this works and I do not have any hard numbers on the sensitivity of
mu-metal either.

Attila Kinali

[1] "Characterization of Clocks and Oscillators", NIST Technote 1337,
by Sullivan, Allan, Howe, Walls, 1990
http://tf.nist.gov/general/pdf/868.pdf

[2] "Handbook of Frequency Stability Analysis" NIST Special Pub 1065,
by W.J. Riley, 2008
http://tf.nist.gov/timefreq/general/pdf/2220.pdf

-- 
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] Temperature (environmental) sensors

[David J Taylor]

I like the Bosch BME280 conneced to a Raspberry PI.
https://learn.adafruit.com/adafruit-bme280-humidity-barometric-pressure-temperature-sensor-breakout/pinouts
https://github.com/adafruit/Adafruit_Python_BME280/blob/master/README.md
--   Björn


Some performance plots are here, with some comparison between the pressure 
readings from various sensors.


 http://www.satsignal.eu/mrtg/performance_air_temp.php

This is on mixed Windows/Linux platforms.

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 


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Re: [time-nuts] Line Voltage - USA

[Poul-Henning Kamp]

In message 

Re: [time-nuts] Observations of NTP during the leap second

[Martin Burnicki]

Deirdre O'Byrne wrote:
> My setup is a raspberry pi running Linux 4.1.19 and ntpd version 4.2.6p5.
> It's being fed a PPS signal from a GPS receiver, and also checks the time
> against the ntp pool.
> 
> For the second starting at 23:59:58.0 UTC, NTP was reporting second number
> 0xdc12c4fe, and had its leap second flag set.
> 
> For the second starting at 23:59:59.0 UTC, NTP was reporting second number
> 0xdc12c4ff, and the leap second flag was *not* set!
> 
> For the second starting at 23:59:60.0 UTC, NTP was again reporting second
> number 0xdc12c4ff, and the leap second flag was not set.
> 
> For the second starting at 00:00:00.0 UTC, NTP was reporting second number
> 0xdc12c500, and the leap second flag was not set.
> 
> I would have thought NTP would have the leap second flag set at least until
> 23:59:60.0.

This was a bug in in ntpd 4.2.6, which has been fixed in 4.2.8. See:
http://bugs.ntp.org/show_bug.cgi?id=2250

Martin
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Re: [time-nuts] Line Voltage - USA

[Hal Murray]

> Did the utility replace the damaged equipment?

A friend lived in a building when the city crew working on a transformer put 
440 on the line.  It blew out all the electronics in 12 condos - mostly TVs.  
I think toasters and refrigerators were OK.  There wasn't any question that 
the city was at fault.  I don't remember how much paperwork they had to go 
through to get reimbursed.  It might get sticky for something like a time-nut 
with a lot of used gear that may not be easy to replace at the original 
price.  (Could be a good excuse to clean up and start over.)

How much trouble do hams have with their insurance companies?


-- 
These are my opinions.  I hate spam.



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