[time-nuts] Re: HP z3816a DC power supply DIP switches

[Dave ZL3FJ]

If its anything like the Z3815A then the supply should provide 24 to 48V DC
at about 25W continuous, and
be capable of providing around 40W for 10 minutes while starting. (this
data is  from the unofficial manual for the  Z3815A that Murray Greenman,
ZL1BPU, produced some years ago when a number of the Z3815A/GPSR units
appeared on the surplus market down this way)
 DaveB, NZ

-Original Message-
From: ed breya [mailto:e...@telight.com] 
Sent: Wednesday, March 02, 2022 16:39
To: time-nuts@lists.febo.com
Subject: [time-nuts] Re: HP z3816a DC power supply DIP switches

Sam, I noticed in your last post that you're planning to use a printer type
PS. It may work if you luck out, but I suspect that it won't have enough
juice to get things up and running.

If it's anything like the typical ones I've seen, it's a small SMPS brick,
built for running ink-jet printers. These tend to be just heavy enough for
their normal purpose, but not much beyond. Actually, most SMPSs don't work
well for transient startup conditions like this. In this case, you have to
charge the big filter cap, and take on the negative input R, and the high
initial oven heater load. SMPSs tend to be very quick in protect-response,
and likely will current limit, by going into immediate fold-back, tick
(chirp), or trip (and manual reset) mode. You can of course, try it and see
- it shouldn't hurt anything. If it immediately faults, you can try letting
it do its own soft-start, by connecting the load first, then plugging the PS
into the line.

I think your best bet is to use a bench linear PS for experimenting - one
with way more current capability than you apparently need. Then you can
figure out how it all actually works before deciding on the long term
solution.

Ed
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[time-nuts] Re: Project Great

[Dave ZL3FJ]

Is the ISS a suitable platform?
I expect getting the experiment package on there would be quite another matter!
DaveB, NZ


-Original Message-
From: Tom Van Baak [mailto:t...@leapsecond.com] 
Sent: Sunday, November 28, 2021 20:09
To: time-nuts@lists.febo.com
Subject: [time-nuts] Re: Project Great

Hi Thomas,

Good to hear the experiment was contagious for you. If you have additional 
questions let me know.

Your suggestion about Mount Evans and Pikes Peak are excellent. You will enjoy 
this 2017 paper:

"An Undergraduate Test of Gravitational Time Dilation"
https://arxiv.org/abs/1710.07381
https://arxiv.org/pdf/1710.07381.pdf

---

As for CSAC, the news is not so good. I've worked with several groups to 
explore CSAC for gravitational time dilation experiments. Those clocks are so 
cute and small, it's irresistible; but the numbers just don't add up. Over a 
day their stability is in the low e-12's vs. a "real" cesium clock like a 5071A 
in the low e-14's. So when you are doing a relativity experiment trying to 
detect a frequency shift that's on the order of e-13's you reach for a 5071A 
instead of a CSAC. The performance is nearly 100 to 1.

One solution is a taller mountain. The best on the planet is Mauna Kea (Big 
Island, Hawaii) where you can literally drive from sea level to the summit 
(13,800 ft, 4200 m) in a few hours. The frequency shift up there is 4.5e-13, 
which is 40 ns per day. But still, to have even the slightest chance of success 
you'd want your clocks to be good to 1e-13 or better. CSAC aren't even close, 
and probably neither are telecom Rb.

I'm currently involved with another solution -- a HAB (High Altitude
Balloon) CSAC flight. Getting to 100,000 ft altitude is quite common. Up there, 
clocks run a whopping 3.3e-12 faster, which is 280 ns/day, or 12 ns/hour. This 
is a clear case where the amazing low mass and low power of a CSAC is a  
critical advantage. However, the numbers still aren't working out and the 
logistic and environmental conditions are brutal. I won't say it's impossible, 
but it may take years and a huge bag of tricks before it works or it's proved 
too impractical.

---

Jim, I'd be interested in any Cubesat / CSAC results. They don't exactly land 
in one piece so the typical round-trip clock comparison method wouldn't work. A 
direct frequency comparison might. In that case the drift and re-trace specs of 
a CSAC are probably more important than the stability.

/tvb


On 11/27/2021 12:37 PM, Thomas Valerio wrote:
> I think that Tom's GREAT adventure is kind of what sealed the deal 
> making me a time-nut or at least a time-nuts lurker, a lot of this 
> stuff is still little over my head, but I keep reading.
>
> If anyone is inclined and has the clocks and the kids ( I don't have 
> either ), there is always Mount Evans and Pikes Peak, although you may 
> have to leave the clocks behind overnight.  Mount Evans is still on my 
> bucket list but without clocks and two or three days of time to 
> monitor them, I don't think I will be doing the Mount Evans edition of 
> GREAT.  For anyone that is flush enough to afford or can beg, borrow 
> or steal access to a Microsemi chip scale atomic clock, I think a 
> Mount Evans edition would be an awesome addition to Tom's original work.
>
> Thomas Valerio
>
>
>> For newcomers to time-nuts, Andy is asking about my DIY gravitational 
>> time dilation experiment(s).
>>
>>   > What am I missing?
>>
>> It looks like you used the wrong value (or wrong units) for "h".
>>
>> The summit of Mt Rainier is 14411 ft (4400 m), but the highest point 
>> on Mt Rainier that is accessible by road is the Paradise visitors 
>> center at
>> 5400 ft. Our house is at 1000 ft elevation so the net difference in 
>> elevation of the clocks was 4400 ft (1340 m).
>>
>> The clock(s) on the mountain ran fast by gh/c² = 9.8 × 1340 / 
>> (3e8)² = 1.5e-13. Fast clocks gain time. We stayed for about 42 
>> hours so the net time dilation was 42×3600 × gh/c² = 22 ns.
>>
>> 
>>
>> For more information see the Project G.R.E.A.T. 2005 page:
>>
>> http://leapsecond.com/great2005/
>>
>> Better yet, these two recent talks from 2018 and 2020 cover all 3 
>> GREAT
>> experiments:
>>
>> > -VanBaak-GPS_Flying_Clocks_and_Relativity.pdf>
>>
>> > y.pdf>
>>
>> Lots of time nutty photos in both of those!
>>
>> /tvb
>>
>>
>> On 11/27/2021 7:33 AM, Andy Talbot wrote:
>>> Just been reading your adventures with 3 Cs clocks, a mountain and 3 
>>> kids, but I can't make the estimate of time dilation work out.
>>> You measured ~ 23ns and say it agrees with calculation
>>>
>>> The equation quoted in a related reference, for "low elevations" is 
>>> g.h/c² which if you plug in g = 9.81 m/s²  and h = 4300m for Mt 
>>> Rainer gives an expected value of 4.7 * 10^-16.
>>> Over 2 days, 2 * 86400s, that would be 81 ns in tota

[time-nuts] Re: Thunderbolt "good performance" example (Stewart Cobb)

[Dave ZL3FJ]

Attachments come through just fine here.
 DaveB, NZ

-Original Message-
From: Dave B via time-nuts [mailto:time-nuts@lists.febo.com] 
Sent: Sunday, July 25, 2021 19:37
To: time-nuts@lists.febo.com
Cc: Dave B
Subject: [time-nuts] Re: Thunderbolt "good performance" example (Stewart
Cobb)

> Hope you find this useful.
>
> Cheers!
> --Stu
> -- next part -- A message part incompatible 
> with plain text digests has been removed ...
> Name: LabMainTbolt-2021-04-29.png
> Type: image/png
> Size: 87301 bytes
> Desc: not available



Sadly, being a plain text only mail system, your screenshot graphic was not
passed on.

Best put it on a public page somewhere, and include a link to it in the
message text.

(Note that most social media based "user pages", are not "public" by
default.)

Best Regards.

Dave G8KBV

--
Created on and sent from a Unix like PC running and using free and open
source software:

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[time-nuts] Re: Best frequency to start for GHz synth ?

[Dave ZL3FJ]

Louis Essen was THE man - hence to the Essen Ring quartz oscillator which was a 
development from Dye's original work on that particular quartz configuration.  
The British PO used a bank of Essen Ring references as their standard  
immediately prior to- and I think during most of-  WW2.  Not sure re 
oscillation mode but IIRC the rings had to be suspended from several  silk 
threads.
DaveB, NZ



-Original Message-
From: Bob kb8tq [mailto:kb...@n1k.org] 
Sent: Thursday, April 01, 2021 15:16
To: Poul-Henning Kamp
Cc: Discussion of precise time and frequency measurement
Subject: [time-nuts] Re: Best frequency to start for GHz synth ?

Hi

Some of the early 100 KHz resonators were ring shaped. The British really 
pioneered this side of things ( while the US was still doing bars …) back in 
the 1930’s. AFIK the mode is not a whispering gallery. 

Given the low frequency of a 100 KHz resonator, a “not space limited” design 
might get to some pretty insane Q values. Meter level dimensions probably would 
be involved.
Good luck sourcing the raw quartz :) :) :) ( …. and yes, that’s only the first 
of a long list of issues ….).

Bob

> On Mar 31, 2021, at 3:23 PM, Poul-Henning Kamp  wrote:
> 
>> If you were going insane on a fountain, you likely would go with one 
>> of the sapphire whispering gallery devices as the start of your 
>> chain. A good one will blow a quartz crystal based part away ….
> 
> That reminds me:
> 
> I think the first quartz-crystal at Bell Labs was ring-shaped, do you know if 
> that used a whispering gallery vibration mode ?
> 
> 
> -- 
> 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] Interesting widget for 5MHz standard fans

[Dave ZL3FJ]

Is the widget schematic on line anywhere?   Quick search doesn't find it.
DaveB, NZ

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of
cdel...@juno.com
Sent: Monday, February 15, 2021 08:45
To: time-nuts@lists.febo.com
Subject: [time-nuts] Interesting widget for 5MHz standard fans

Walter,

The widget is a module from the FTS 4050 series of Cesium standards.

I have a couple of these modules.

Schematics are in the manuals.

Cheers,

Corby


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Re: [time-nuts] The need for quartz crystals and mains frequency (was: Mains Frequency)

[Dave ZL3FJ]

That 'flag' feature can be found on the very early  (1930s) Telechron
digital display clock, the model 8B01, as a separator between the hours and
minutes digits.  A lever on the back panel allowed the user to reset the
flag from red to white when power was applied.
 Loss of AC power meant the synchronous motor that drove the digital dial
drum mechanism lost it's magnetic field - which allowed the flag to 'fall'
and display as red. The 8B01 has often been described as the world's first
digital clock-is this true?- Not sure.
DaveB, NZ


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Hal
Murray
Sent: Saturday, February 13, 2021 18:49
To: Discussion of precise time and frequency measurement
Cc: hmur...@megapathdsl.net
Subject: Re: [time-nuts] The need for quartz crystals and mains frequency
(was: Mains Frequency)


att...@kinali.ch said:
> And, please do not forget that modern mains frequency control is 
> something quite recent as well. Especially outside (west) Europe. 
> Having mains frequency powered clocks being off several minutes per 
> month was the norm
> 50-70 years ago.

I have a (fuzzy) data point from ~60 years ago.

I was in high school and got to tag along with a quick tour through Niagara
Mohawk's control room.  They were the power company for a large part of
upstate New York, including Syracuse where I lived.

I remember somebody pointing out a pair of clocks on the wall, one driven by
the line.  I wasn't enough of a time-nut to inquire about the source for the
reference clock.

--

Has anybody seen a good writeup on the history of clocks running off the
line frequency and power lines being used for timekeeping?

--

Anybody else remember the little red dot that was on a swinging flag behind
a little hole?  That was the analog equivalent of blinking 00:00.

When you set the time on a clock, the flag swung up and stuck to a magnetic
part of the motor.  The color on the part of the flag visible through the
hole in that position matched the color of the face.  When power was lost,
gravity pulled the flag down and that part was painted red.


--
These are my opinions.  I hate spam.




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Re: [time-nuts] A Research Proposal

[Dave ZL3FJ]

I have here a pair of instruments that were part  of a system used  at one time 
 in a power station here in NZ  to control the time error in one  part of the 
national grid. It controlled the selected generators and provided a real time 
display of the time error between a reference standard and the 50 Hz mains 
frequency.  The system comprised an HP 5280A reversible counter  with two 
inputs, one from the  mains 50 Hz as generated and one from the reference 
standard. These two inputs were arranged to add  counts from one input and 
subtract counts from the other, such that the counter displayed zero while the 
generated 50 Hz was accurate. Offsets from 50Hz were displayed as positive or 
negative counts. The reference input was derived from an HP 105A quartz 
oscillator and the system included provision to manually  synch that to the 
national standard time standard on an as required basis. The output of the 
5280A counter drove an HP 6933B D/A converter, the bi-polar DC output of which 
was used (both magnitude and sign)  to control the governors on some of the 
hydro generators. Dual HP 5321B clocks were used to display TOD from both 
sources.
 The 6933B is complete but the 5280A counter has been partly disassembled.  The 
5321Bs never got this far-neither did the 105A- who knows, it might still be 
being used  as a reference!

DaveB, NZ

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Bill 
Hawkins
Sent: Monday, July 08, 2019 06:48
To: Bob via time-nuts
Subject: Re: [time-nuts] A Research Proposal

Group,

We've discussed this before, but maybe it needs to be said again.

Line frequency is not constant.   There is no master PLL.  Approximate 
frequency is maintained by a central power dispatching office in each of the 
four (?) regions tied together by their power distribution grid.  The 
dispatcher's goal is to create the same number of cycles of AC each day.  IIRC, 
power is bought and sold by the number of cycles generated.   As the daytime 
load increases, the generators slow down a bit.  Note that it is not possible 
for each generating station to control its frequency, as that would not be 
stable.  Instead, the dispatcher asks various plant operators to generate more 
or less steam (or water flow) in order to increase the frequency.  When the 
load drops at night, the generators speed up a bit, and steam has to be 
reduced. At the end of the day, so to speak, the number of cycles generated is 
very nearly equal to the number generated if the line frequency had been steady 
at 60 (or 50) cycles per second.  Synchronous clocks stay accurate although 
they may be off by a few seconds as dispatchers scramble to get enough steam to 
keep up.

So yes, you can get phase data within a region but you must compensate timing 
data as the frequency varies.

The regions are connected to each other for purposes of power sharing with DC 
transmission lines.  These use inverters to convert between AC and DC. The AC 
frequency is controlled by the grid that it is tied to.  Phase angle can be 
changed to change the amount and direction of the power transferred.

So no, you can't compare data from different regions, unless you want to know 
which way DC power is flowing.

I hope this was informative.

Bill Hawkins


On Thu, Jul 4, 2019, at 2:00 PM, Andy Backus wrote:
> Historically, and even today, the steady frequency of AC power has 
> been used for timekeeping.  So there may be interest here in the 
> following research proposal:
> 
> Within a given power distribution grid, several observers as widely 
> separated geographically as possible, time stamp the first two zero 
> crossings of the power line after each UTC second – over the course of
> 24 hours (86,400 pairs of data).
> 
> Popularly conceived, all the components of a power distribution grid 
> are phase locked – though, of course, power is taken in and out by 
> varying degrees of lead or lag.  Frequency is maintained by a constant 
> balancing act between load and generation.
> 
> Typical power distribution grids, however, are sized on a scale of 
> thousands of miles.  “Locking phase,” then, is problematic simply on 
> the basis of the limits of information transmission rate.  Even at c, 
> every 1000 miles takes 5 ms, which represents a third to a quarter of 
> the period of the AC power waveform.
> 
> Many interesting phenomena might result from that reality, which 
> suggests a certain constrained flexibility over large distances – 
> almost as if the system is like a large lake of viscous liquid.  When 
> there are local disturbances such as rapid load changes or sudden 
> generation adjustments, for example, it is quite possible harmonic 
> ripples could be propagated through the system.
> 
> Such effects could be observed by comparing phase data across 
> significant distances within a distribution grid.
> 
> Andy Backus
> Bellingham, WA
> USA
> 
> 
> From: tim

Re: [time-nuts] GPSDO 10MHZ Splitter

[Dave ZL3FJ]

As regards the GPSDO, check this out-
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=301
I think there's also a US distributor somewhere..
DaveB, NZ

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Don 
Meadows
Sent: Saturday, June 22, 2019 02:28
To: time-nuts@lists.febo.com
Subject: [time-nuts] GPSDO 10MHZ Splitter

Is there an easy, and cheap way to add a splitter the 10Mhz signal from GPSDO, 
without going to a distribution amplifier to feed two different devices?

I really don’t want to build a complicated project, or spend $200.00 dollars 
for an 8 output distribution amp off the net.  One output would be dedicated 
for my  counter time base, and the other would be an ‘extra’ 
10MHZ source for another counter, or just to display on the scope.

I don’t have a GPSDO yet, I just can’t decide on one.
I am leaning to the Trimble, but it’s still undecided.

Could anyone comment on buying a “Refurbished by Seller”
GPSDO on E-bay. They are a few dollars cheaper, but I really want one I can 
have trust and confidence in.

Sorry for the long post.
Thanks, Don



Sent from Mail for Windows 10

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[time-nuts] Quick Start Giude for HP 53310A Modulation Domain Analyser

[Dave ZL3FJ]

Can anyone point me to a downloadable copy of the above document?  I have
most other docs for the instrument but the Quick Start Guide has eluded me
so far. Not sure I really need it (then again, I might!) but be nice to get
a copy for the sake of completeness.
DaveB, NZ





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Re: [time-nuts] Looking for a reference oscillator called XRef-VS made by VK3HZ for TS-2000

[Dave ZL3FJ]

There's a device- also originating in VK land-  in prototype testing phase
at present  that is similar to the x-Ref and reputed to be much cheaper. No
idea when it will be available.
73
 Dave, ZL3FJ


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Wayne
Sent: Thursday, September 13, 2018 11:43
To: timen...@rudius.net; 'Discussion of precise time and frequency
measurement'
Subject: Re: [time-nuts] Looking for a reference oscillator called XRef-VS
made by VK3HZ for TS-2000

Hi Bo,
The AutoPLL does look promising.  I think I'll have a discussion with Steen
about my application and perhaps order the unit for testing.
Thank you for your input.  Much appreciated.
73
Wayne, WA7NE

-Original Message-
From: time-nuts  On Behalf Of Bo Hansen
Sent: Wednesday, September 12, 2018 1:43 AM
To: time-nuts@lists.febo.com
Subject: Re: [time-nuts] Looking for a reference oscillator called XRef-VS
made by VK3HZ for TS-2000

Hi Wayne

I am not 100% sure but can you use the this AutoPLL:
<http://oz5n.dk/AUTO-PLL.htm>

Availability: <http://oz5n.dk/>

Bo, OZ2M

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