[time-nuts] Re: in-ground clock room

[Bob Bownes]

Temperature stability will vary with climate. Here in upstate NY, you’ll need 
to get to >50” of depth to start to get any real year round thermal stability. 
But a local civil engineer should know that number well. We also have to worry 
about water intrusion, even with concrete, depending on depth. 

Interesting subject. 



> On Sep 8, 2021, at 22:09, djl  wrote:
> 
> I think you can use precast concrete such as a septic tank or rings. My 
> measurements made a LONG time ago in NM indicate that a mere 18 inches depth 
> leads to less than one degree (God's units as revealed by the French) over 
> the period of a year. Bring wiring in via a trench at the surface level of 
> the top of the vault. Ideally, the cover should be insulation to near 
> surface, then soil. That's the one sticky point because as you will know, 
> thermal vortices will be set up in the vault air. very small slow fans may 
> control?  The flow can be modeled,  I think.
> Don
> 
>> On 2021-09-08 19:54, Tom Van Baak wrote:
>> I am considering a below ground "clock room" away from the house. This
>> will be for some low-drift quartz oscillators and also a couple of
>> precision pendulum clocks. The goal is long-term, unattended, and very
>> undisturbed operation.
>> For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So
>> that's vastly smaller than digging a basement, but much larger than
>> drilling a 8 inch round pipe. Digging down gives some natural
>> isolation and temperature regulation. A couple tons of concrete gives
>> high stability vertical walls for the pendulum clocks.
>> If any of you have personal or professional experience with the design
>> or construction of this sort of thing, especially experience with
>> precast (utility) vaults or poured concrete, please let me know.
>> In case this gets too off-topic for time-nuts, off-list email to me is
>> fine (t...@leapsecond.com).
>> Thanks,
>> /tvb
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> 
> 
> The whole world is a straight man.
> --
> Dr. Don Latham  AJ7LL
> PO Box 404, Frenchtown, MT, 59834
> VOX: 406-626-4304
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[time-nuts] Time to part with my 5370B and 5372A

[Bob Bownes]

Hey folks,

I've listed them elsewhere, but I have an HP 5370B (with the beaglebone
upgrade) and a 5372A I'm thinning from the TE herd. PM me for more details
if you are interested.

Thanks,
Bob
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Re: [time-nuts] Chinese NTP Time server

[Bob Bownes]

Brian,

TICC is one answer, HP 5370 would be another. They can often be had quite
reasonably on ebay and, short of a SRI counter, seem to be the standard.
There is one on ebay atm (item 401738800574) for 120 obo that, while
missing the red filter on the front, probably just needs to have the
timebase switch moved from 'EXT' to 'INT' on the back, (and maybe a jumper)
or to be fed 10Mhz from one of your GPSDOs. Assuming it is good. I've had
good luck with this particular problem.

Bob

On Tue, Jan 7, 2020 at 4:13 PM Brian Lloyd  wrote:

>
> OK, I tried the AD8055A op-amp in the buffer. Output now looks exactly
> like the output of the OCXO (square wave). Unloaded output is 3.2Vpp.
> Output into 50 ohms is +10dBm, nice and clean. So, if you buy one and
> want to add the components to get 10MHz sq-wave output, you need to add
> a TBA 1-1219 isolated DC/DC converter, and an AD8055A op-amp. Works
> great. Mouser has them in stock. While I do have hot-air SMD-rework
> capability, the SOIC-8 package was easy to hand-solder with a small tip
> on my Hakko solder station so I didn't have to go get solder paste.
>
> BTW, the price quoted for a unit WITH 10MHz output was $350,
> substantially more than the $201 for the non-10MHz unit. For $10 in
> parts I am happy. OK, it isn't sine-wave output. I don't have anything
> that requires a sine wave reference.
>
> So this meets my needs for NTP stratum-1 for the machines in my house,
> and 10MHz for my radios.
>
> Still, I wish to graduate to full time-nuttery status. I would like to
> do the ADEV analysis. Other references I have kicking around:
> Thunderbolt, Leo Bodenar GPSDO, Ephratom LPRO-101 Rb. Unfortunately I
> don't have a good, free-running OCXO for short-term comparison. Still, I
> suspect the Rb should work well enough for that. Also, the only device I
> have to DO the comparison is a Fluke T7260a. Thinking about a TICC. Advice?
>
> Brian, WB5BL
> --
>
>
>  
>
> Brian Lloyd
> 706 Flightline
> Spring Branch, TX 78070
> br...@lloyd.aero 
> +1.210.802.8359
>
>
>
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Re: [time-nuts] PC Time Servers

[Bob Bownes]

Localhost is yourself. Typically the IP address of 127.0.0.1

You could use LH to update the time on the machine she is running on. 

Bob

> On Dec 30, 2019, at 21:52, Richard Mogford  wrote:
> 
> I have not been on this list since 2016 and have some new time questions.
> 
> I am using a program called “Faros.”  It is for ham radio.  It controls a 
> radio receiver and automatically checks 18 transmitting beacons around the 
> world.  It displays the signal strength of each beacon.  This gives the radio 
> operator some idea of whether they could contact someone in that area.
> 
> Faros depends on an accurate time source that has consistent delays.  I guess 
> “delay” here means the time it takes for the time signal to get to the PC and 
> Faros.
> 
> There is an editable list of time servers in the software.  There is also a 
> test function that checks time source availability and delay.  The only one 
> that has very low delays (e.g., 1 ms) is called “localhost.”  All the other 
> servers have larger delays, such as 38 ms or more.
> 
> Can someone tell me what “localhost” is?
> 
> I have a simple GPS receiver (from Adafruit) connected to the PC that sends 
> data to Lady Heather.  Is there a way I can use the data from the GPS in 
> Faros?
> 
> Richard
> 
> 
> 
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Re: [time-nuts] Chinese NTP Time server

[Bob Bownes]

If you are referring to the panel I think you are referring to, I suspect an 
obstacle of some sort. The plot at my house has a similar artifact I can 
attribute to the hill to my north and the lack of elevation of the antenna. 

Bob

> On Dec 29, 2019, at 19:05, Kevin Rowett  wrote:
> 
> 
> 
>> On Dec 26, 2019, at 8:19 PM, xaos  wrote:
>> 
>> Brian,
>> 
>> I created a new web  page with some pics and a live output of the NTP server 
>> from "Lady Heather V5.0"
>> 
>> https://www.maximaphysics.com/GPS.shtml
>> 
> 
> Looking at the Sat plot in the lower right of the screen shot (sat position 
> versus SS), what causes, or contributes to the shading +-30 degrees?
> 
> Thanks.
> 
> KR
> 
> 
> 
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[time-nuts] Mac HP GPS Control

[Bob Bownes]

Long ago, I nabbed a demo copy of the Mac HP GPS Control software by Dave
Anderson GM6JJJ. Recently I tried to register my copy only to find he was
an SK and the registration part of his site is no longer in place.

Even though I suspect development has stopped, I'd be interested in getting
a 'real' copy. Anyone know if that is possible?

Thanks!
Bob
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Re: [time-nuts] Using commercial video amplifier for 10MHz clock distribution.

[Bob Bownes]

I have a few of the 2 in 5 out video distribution amps. I took one apart
and converted it to 50Ω from 75Ω, and to be honest, I can't really see a
difference.

Bob


On Fri, Oct 18, 2019 at 8:08 AM Charles Steinmetz 
wrote:

> Taka Kamiya wrote:
>
> > I am using Extron MDA 3V for distributing 10MHz at several places in my
> lab.  MDA3V is a one port in - 3 port out device made for VIDEO market and
> rather low end at that.  Input and output is 75 ohm and bandwidth extend to
> 150MHz or so.  Looking at 10MHz sine wave through it, it looks good.  No
> visible distortions.  Gain is unity between input and one of the ports.
> >
> > Couple of questions though.  This device is 75ohm.  It's easy to add
> 150ohm in parallel to a matching resister and make it 50ohm.  However, I'm
> guessing 50 ohm / 75 ohm mismatch is not really a big deal that I'm not
> doing anything about it.  Input and output cables are RG58 (50 ohm)  VSWR
> is 1.5, For external sync port, many equipment is not exactly spec'd for 50
> ohm, but often only spec'd for voltage or at db level without any specific
> impedance mentioned.  Recommended cable is 50 ohm though.  I typically shy
> away from consumer grade gear but looking inside, it's just an op-amp and
> registers.  If I use square wave which contains higher frequency
> components, would this be inadequate?
> > There are many web pages by people doing exactly what I'm doing with
> usually bigger Extron devices.  I'd like to consult the Time-Nut community
> of sanity in what I am doing.
>
> I published a doc with recommended mods to the opamp-based Extron video
> DAs for use as 1-10MHz clock/timing DAs:
>
> <
> http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Extron_ADA_6_modifications_for_use_as_10MHz_distribution_amp_STEINMETZ.pdf
> >
>
> Whether you make the changes or not, you may find some helpful
> information there.
>
> Best regards,
>
> Charles
>
>
>
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Re: [time-nuts] Cloudflare

[Bob Bownes]

Most of the good data centers I’ve used either offer a connection to a stratum 
1 server or are more than happy to put a antenna on the roof. Many offer 
microwave as a third redundant circuit path, which requires an antenna. All for 
a price, of course. 

When I worked for an ILEC, many moons ago, we had two and a half floors at 60 
Hudson St. Our stratum 1 antenna was literally glued to a window. Next to a 
10GHz dish. :)

My hotel in Toronto two weeks ago overlooked a building that was clearly 
someone’s data center, based on the 6 generators, massive AC, numerous 
microwave links, and yes, GPS bullet antennas, covering the roof. 

Bob

> On Jun 21, 2019, at 22:01, Sanjeev Gupta  wrote:
> 
> Bob,
> 
> The hardware is cheap.  The software is free.  The skills to deploy are
> widely available.  But...
> 
> A cable run from your rack in the middle of the datacenter, through to the
> roof, is either impossible or thousands of dollars and weeks of planning.
> 
> Data centers can run wires within the building for exorbitant costs, asking
> them to run one to the exterior is, well, impossible.
> 
> -- 
> Sanjeev Gupta
> +65 98551208 http://www.linkedin.com/in/ghane
> 
> 
>> On Sat, Jun 22, 2019 at 6:06 AM Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> Given the relatively low cost of a GPS based “Stratum 1” NTP, it’s not
>> real clear
>> why (at the end of the paper) they go off and “exchange emails
>> individually with the
>> organizations that run stratum 1 servers, as well as negotiate permission
>> to use them.”
>> to source the root time for the system. I would have thought that some
>> sort of combo
>> of on site and off site sources would be at the “top of the tree”.
>> 
>> Bob
>> 
>>> On Jun 21, 2019, at 2:20 PM, Marco Davids via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>>> 
>>> Opinions, anyone?
>>> 
>>> https://blog.cloudflare.com/secure-time/amp/
>>> 
>>> ("Introducing time.cloudflare.com")
>>> 
>>> --
>>> Marco
>>> 
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Re: [time-nuts] GPSDO 10MHZ Splitter

[Bob Bownes]

Sure, presuming the output is 50Ω, build a 50Ω power divider. The signal
will be 3dB down on each of the outgoing legs vs the input. Plenty of
designs if you google it.

If the output is TTL, feed a 74xx04 on pin 1, send pin 2 to 3 and 5, pick
up the output from 4 and 6. Or choose some other gate you have handy.

Bob


On Fri, Jun 21, 2019 at 12:07 PM Don Meadows  wrote:

> 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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Re: [time-nuts] inexpensive fiber optic distribution

[Bob Bownes]

To pull this back to time nuts territory, this brings up the idea of simply
using traditional ethernet infrastructure, be it 100M/1G/10G/whatever at
the PHY layer to achieve distribution of 1pps. The infrastructure is easily
enough interfaced to, even a simple microprocessor can do it, using
switches allows for distribution with known characteristics. Not sure that
you'd need to climb up even into Layer 2, but if you do, that would allow
for identification of the sources by MAC address. You's still have to worry
about collisions I suppose. There are other networking technologies that
could also be used with less impact and better characteristics, with
infiniband (lossless, low latency) coming immediately to mind.

On Thu, Mar 21, 2019 at 11:03 AM Julien Goodwin 
wrote:

>
> The lock in is almost entirely vendor profiteering, optical monitoring &
> wavelength switching are standards (where implemented), but plenty of
> vendors use (almost always trivially bypassable) lock-in to sell SFPs
> they rebrand from the same OEMs at up to 100x markup.
>
> The folk in the big telcos (or in my case, big content providers) who
> run the global backbones have plenty of stories.
>

As one of the guys who has to make these decisions for a big company, I
have to pipe up in our defense.

It has very little to do with profiteering, though it is easily seen as
such. In reality, there are a number of vendors of transceivers out there
(or other similar parts) ranging from excellent to really horrible. The
'lock-in' is to restrict the pool to those that have been qualified and
tested. This vastly reduces support and service hassles on both ends of the
phone call. The incremental revenue on a transceiver of, in one case I can
document, of about $600, even when multiplied by the number required for a
full system, isn't even in the decimal points of the total cost of the
system, which can easily exceed $3-4M.

Bob
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Re: [time-nuts] HP Stories: Battery Chargers, and a fading idolization of HP

[Bob Bownes]

> 
> Yes, those brown roughly 1" square caps used intact sheets of mica as 
> dielectric. You can easily split the mineral into uniform, thin, transparent 
> sheets.

Beware inclusions that will make the surface rough and change the behavior, 
particularly breakdown voltages. 

> The reconstituted caps are still around - used in high power RF circuits 
> (mica has really low loss, but high epsilon) and in Tesla coils (a sort of 
> special case high power RF). Most of them are surplus Russian/Soviet.
> 
Hmm, mica is pretty much hexagonal version of graphite/carbon/diamond created 
when there is a large axial force and the proper temperature. It is synthesized 
for many uses today, I’d be very surprised if precision high voltage caps was 
not one of them. 

That being said, thanks for the insights into the 5061A/B. Now I feel the need 
to go power mine up!
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Re: [time-nuts] Prescalers ?

[Bob Bownes]

Mark,

I had pretty good luck with a Hittite prescaler built into a board for the
5328 as outlined by Bert, VE2ZAZ.

http://ve2zaz.net/hp5328a/hp5328a_prescaler.htm

It's a wee bit deaf as frequency goes up, but works just fine!

Bob


On Thu, Jan 24, 2019 at 1:00 AM Mark Spencer 
wrote:

> Hi:
>
> I'm pondering ways I can use my  collection of time interval counters
> (most of which also have frequency counter modes) to measure the frequency
> of signals at frequencies up to 1.3 GHz.   None these units will deal with
> frequencies higher than 512 MHz.
>
> Does anyone have any suggestions for off the shelf time nut quality
> Prescalers ?  Or would I be better off just buying something along the
> lines of a suitably equipped 53131A or 53132A ?  (If I end up buying
> another counter I would rather buy another universal counter I could use
> for time nuts stuff, vs simply buying a frequency counter for this
> application.)
>
> Thanks in advance for any suggestions.
>
> Mark Spencer
>
> m...@alignedsolutions.com
>
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Re: [time-nuts] Atomic Clocks: It is important that they keep good time, Part 1

[Bob Bownes]

Interesting. I was wondering this as well now that time-nuts has gotten me
into collecting vintage (pre WWII) chronographs. Some are radium, some not,
most are in need of a good repaint either way.

But I do know that tritium gun sights are also a thing. Are those all
mil-surplus or using some secret source of tritium paint...

BTW, latest acquisition in the Vintage watch collection is a 1916 Waltham,
made nearby, with still a local watch shop specializing in them. Looking
forward to it's arrival.


On Mon, Jan 7, 2019 at 1:48 PM Warren Kumari  wrote:

> On Fri, Jan 4, 2019 at 6:59 PM Steve Allen  wrote:
>
> > On Fri 2019-01-04T17:05:21-0500 paul swed hath writ:
> > > Ed agree with your coment that a 30 or greater year old led may be
> > dimming.
> >
> > Not nearly as much as an entirely different clock illumination:
> > radium watch dial paint
>
> I remember my mom's wind-up travel clock glowing brightly.  50 years
> > later there is nothing.
>
>
>
> I used to have a Rolex submariner with a tritium paint based dial -- I
> really loved the watch, but the tritium had sufficiently decayed that it
> would no longer fluoresce - this didn't affect the utility, but made me
> sad It was made in ~1989 and marked SWISS T < 25 for "less than 25
> milliCurie" (apparently much less, they started out at ~5 milliCurie). In
> ~2016, the tritium would have decayed to ~1 milliCurie. Tritium paint is
> (apparently) no longer legal in the USA, but when I was in Hong Kong I
> found someone who had "new" paint, and willing to repaint the face --
> unfortunately I didn't have time on that trip to have it done, and when I
> went back a few months later the shop had closed down...
>
> There is a (apparently) a group of watch dial enthusiasts who get a
> specific brand of tritium based exit sign which has tritium paint embedded
> in the plastic (most tritium exit signs are the small gas capsules
> instead), grind them up and then extract the paint from the ground plastic
> using solvents. I briefly toyed with this idea before deciding this was bad
> mojo and sold the watch...
>
>
> > I brought it into the lab just to check that
> > it is still radioactive (wouldn't want to have lost that radium
> > somewhere).  It's the zinc sulfide crystals, the radiation damages
> > them and they stop producing light.
> >
>
> H. I wonder if that is actually what happens with the tritium paint -
> the dial I had would *just* have a visible glow if I had it in a perfectly
> dark room and let my eyes adjust for a while. If the tritium level had
> decayed from 5 milliCurie to 1 milliCurie I would have guessed that the
> glow should just have been 1/5th of original. The dial would still
> fluoresce nicely under UV, so I'm not sure what that means...
>
> W
>
>
> > --
> > Steve Allen  WGS-84
> (GPS)
> > UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat
> > +36.99855
> > 1156 High Street   Voice: +1 831 459 3046 Lng
> > -122.06015
> > Santa Cruz, CA 95064   http://www.ucolick.org/~sla/   Hgt +250 m
> >
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> >
>
>
> --
> I don't think the execution is relevant when it was obviously a bad idea in
> the first place.
> This is like putting rabid weasels in your pants, and later expressing
> regret at having chosen those particular rabid weasels and that pair of
> pants.
>---maf
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Re: [time-nuts] FCC OTA pre-emption and restrictions on GPS antennas [was: Short term 10MHz source]

[Bob Bownes]

My t'bolt uses a classic magnetic GPS antenna stuck to the top of an old
5.25" disk drive cover laying on top of the screen in the bubble covered
skylight in my office. Works as well as the timing antenna 30' the tower. :)

On Fri, Jan 4, 2019 at 6:08 PM ew via time-nuts 
wrote:

> Had in North Miami Beach that problems at some friends Condos. Used
> several times the sewer vent pipe every home seems to have. In one critical
> case (unfriendly neighbors) with flat roof cut the pipe off three inches
> from the roof used a coupling to the old cut off top pipe but drilled holes
> in it and inserted the attached. The young man got to enjoy Tbolt with LH.
> Mother liked it.Bert Kehren
> In a message dated 1/4/2019 4:16:00 PM Eastern Standard Time,
> hol...@hotmail.com writes:
>
> A friend of mine has his GPS antenna disguised as a bird feeder...  ground
> plane is a pizza pan.  Antenna mounted at the top of a clear tube filled
> with bird food... alas, no holes for the birds to get to the
> food.___time-nuts mailing list
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Re: [time-nuts] Atomic Clocks: It is important that they keep good time, Part 1

[Bob Bownes]

Add a tiny speaker so you can simulate the loud 'tick' of the analog clock.
;)

On Fri, Jan 4, 2019 at 4:29 PM ed breya  wrote:

> Paul, what do you mean by the display "looking pretty ratty?" As I
> recall, the original buck regulator had regulated output voltage around
> 5V for the LEDs. and the PMOS clock IC needed something around 12V.
> Whatever the LEDs run from, it should be regulated and well filtered. If
> the LEDs are dim, it could be the old displays themselves are
> deteriorated, or the regulation isn't right, or maybe a bad output
> filter cap on the buck converter. If the brightness is OK, but digit or
> segment intensities fluctuate with count, then it's probably a
> regulation issue.
>
> I used the shunt regulator to isolate the rest of the system from the
> large variation (about 3:1) in total LED current with readout values,
> and it was possible because I had made lower supplies anyway, via DC-DC
> converters. You wouldn't want to linear-regulate all the way down from
> the main supply around 24V, to a few V for the LEDs. As I recall, the
> peak load is in the 200-300 mA range at good brightness. The efficiency
> of the buck converter makes it practical to run this from the normal
> supply or battery voltage. I think the original deal was that on power
> failure it switched to battery mode, the buck converter was shut off to
> shed the LED load, and the clock IC stayed powered up to keep the right
> time. The button below the display could force it to show when needed.
> Mine will work the same way, when/if I ever finish all the details, but
> will have adjustable brightness, and maybe the option of still
> indicating time in backup mode, with very dim LED setting.
>
> Ed
>
>
>
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Re: [time-nuts] Racal Dana 9478 frequency distribution system with option 04B high stability oven (5x10^-10/day aging rate).

[Bob Bownes]

Video distribution amplifiers are a very good and inexpensive solution to
this problem. Think I paid $5US for my 24 port one (which is actually 3x
dual 1 in 4 out units). I converted one of them from 75 ohm to 50Ω and
didn't bother doing the rest as it made no discernible difference for
timing purposes.

On Thu, Nov 8, 2018 at 10:23 AM George Atkinson via time-nuts <
time-nuts@lists.febo.com> wrote:

>
> The 9478 is an excellent unit but slightly unconventional. It does not
> discipline the internal OXCO to the external standard when present. It has
> a 10MHz PLL VFO tat is locked to either the internal OCXO or external
> refernce depeding what is available. If the external reference is present
> te VFO is locked to that and the internal OCXO is on but not used. If the
> external refernce is missing the internal OXCO is used. Effectively when
> used with an external reference the internal OXCO is a backup.
> The service manual is out on the web nd it would nt be difficult to
> re-configure a 9478 as a dumb 10MHz Distribution unit but this would b a
> waste. 19" video distribution amplifiers are out there too.
> I do have a spare NOS Austron modular 3U 19" rack with distribution
> modules in it but I'd have to check exactly what it has and I'm in the USA
> at the moment. If you are interested I can look when I get bck next week.
> Robert G8RPI
>
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Re: [time-nuts] How can I measure time-delay of a cable with HP 5370B time-interval counter?

[Bob Bownes]

Have you tried with just a single pulse?

> On Oct 28, 2018, at 20:49, Dr. David Kirkby  
> wrote:
> 
> I'm trying to do something which would seem conceptually easy, but I'm
> getting results I can't understand. I wish to measure the delay (in
> seconds) of a bit of length of coaxial cable.
> 
> I'm feeding a sine wave from a Stanford Research DS345 30 MHz function
> generator via a coax to the START input of the counter, then with a BNC
> T-piece, of 480 mm of 50 ohm cable to the STOP input of the counter. Here's
> a photo of the complete setup.
> 
> https://www.kirkbymicrowave.co.uk/Experiments/Delay-of-coax/Path-is-signal-generator-to-start-then-stop.jpg
> 
> I've set the 5370B's START impedance to be 1 M ohm, and the STOP to be 50
> ohms, so the function generator should see a 50 ohm load, as 1 M ohm in
> parallel with 50 ohms is virtually 50 ohms.
> 
> The switch position on the counter are as shown here
> 
> https://www.kirkbymicrowave.co.uk/Experiments/Delay-of-coax/switch-postitions.jpg
> 
> So the main settings are
> 
> * TI mode.
> * +/- TI
> * START. 1 M ohm, positive slope, level to preset position (0 V)
> * STOP 50 ohm, positive slope, level to preset position (0 V)
> 
> With the cable 480 mm in length, the velocity factor of the cable being
> approximately 0.7, I would have expected an electrical length of around 686
> mm, and so a delay of
> 
> time =  distance / velocity = 0.686 / 3e8
> = 2.29 ns.
> 
> I would not be surprised by small changes in delay with frequency, which is
> what I wanted to investigate. But I'm getting the following readings, for
> different frequencies of the function generator
> 
> 1 kHz - unstable readings, around 100~300 us.
> 10 kHz  -> -21.3 us
> 50 kHz -> -4.27 us
> 100 kHz -> -1.90 us
> 250 kHz -> - 528 ns
> 500 kHz -> 1.837 us
> 1 MHz -> 956 ns
> 2 MHz -> 490 ns
> 3 MHz -> -2.6 ns
> 4 MHz -> -0.33 ns
> 5 MHz -> 0.90 ns
> 6 MHz -> 1.50 ns
> 7 MHz -> 1.93 ns
> 8 MHz -> 2.15 ns
> 9 MHz -> 2.38 ns
> 10 MHz -> 2.52 ns
> 11 MHz -> 2.60 ns
> 20 MHz -> 2.85 ns
> 30 MHz -> 2.80 ns
> 
> The numbers look believable  with a frequency input of 10 MHz or more. I
> did not do the complete set again, but using a cable of 1.53 m in length,
> where I would expect the delay to be around 7.29 ns, the results were
> 
> 1 MHz  -> -26.51 ns
> 5 MHz -> 9.70 ns
> 10 MHz -> 9.70 ns
> 15 MHz -> -57.81 ns
> 20 MHz -> -41.64 ns
> 30 MHz -> 7.13 ns
> 
> Note, the function generator and counter do not share a common frequency
> standard for this test. I have not tried it with them locked to the same 10
> MHz reference, but I somewhat doubt that is the cause of these issues.
> 
> I must be missing something, but I'm not sure what it is.
> 
> -- 
> Dr David Kirkby Ph.D C.Eng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
> Essex, CM3 6DT, United Kingdom.
> Registered in England and Wales as company number 08914892
> https://www.kirkbymicrowave.co.uk/
> Tel 01621-680100 / +44 1621-680100
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[time-nuts] TIC part NLA

[Bob Bownes]

A while back, there was a discussion on a part used in an older TIC (IIRC)
design that had changed pinout between 74xx and 74{LS,ALS,H,F,etc}xx and
the design used the older part. Does anyone remember what the part number
was? I found a largeish stash of 74xx parts last time I was scouring the
surplus places in Sunnyvale/San Jose, but I couldn't for the life of me
remember what it was. I seem to recall it was a flip flop of some sort, but
the exact part number escaped me.

If anyone can remember, please let me know off list.

Thanks!
Bob
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Re: [time-nuts] NIST

[Bob Bownes]

Mark,

That would be most useful and free folks from a few of the proprietary
satellite tracker programs. One could write a 'shim' to consume the output
from a tcp/udp (or serial) port and convert to the proper format for a
chosen polar or az/el rotor.

Bob


On Sat, Sep 1, 2018 at 2:00 PM Mark Sims  wrote:

> I recently added a feature to Lady Heather that can output the sun and
> moon positions to a port.  This was for use by solar trackers and moon
> bounce antennas.   It would be easy to modify that code to output the
> position of a satellite (or all satellites) if you wanted to keep an
> antenna pointed at a specific satellite.
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Re: [time-nuts] Setting Time on WSPR Radio Transmitter

[Bob Bownes]

I can heartily recommend the QRP-Labs wspr beacon kit with GPS. It pull the
time from an attached GPS module and will beacon on 2m and below. Once
assembled and configured with your callsign and the bands you want to xmit
on  it Just Plain Works. It can even provide 1pps out.

Pick the right GPS module and you get 10MHz out as well!

Bob


On Fri, Jun 22, 2018 at 2:41 PM, Brian Lloyd  wrote:

> On Fri, Jun 22, 2018 at 1:27 PM, Hal Murray 
> wrote:
>
> >
> > bro...@pacific.net said:
> > > I'm experimenting with a WSPR beacon transmitter and part of how it
> works
> > > depends on pushing the start button at exactly  2 seconds past the
> > minute.
> >
> > What do you mean by "exactly"?
> >
>
> I think WSPR has a +/-2s window for the start of a transmission. It really
> isn't all that "exact" and certainly nothing in the way of time-nuts
> definition of accuracy.
>
> The most popular WSPR implementation runs on a PC and uses a sound-card to
> generate the baseband signal and then uses an SSB transceiver to upconvert
> to the desired output frequency. Even worst-case the standard NTP
> implementation on Windows is more than sufficient for synchronization.
>
> --
>
>
>
> Brian Lloyd
> 706 Flightline
> Spring Branch, TX 78070
> br...@lloyd.aero
> +1.210.802-8FLY (1.210.802-8359)
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Re: [time-nuts] Affordable PoE 6-digit time displays?

[Bob Bownes]

Power over Ethernet. 48V shipped down the ethernet wires. Generally used to
power IP telephones, but WiFi Access points and other technologies have
jumped on the bandwagon as well.



On Mon, Jun 18, 2018 at 12:25 PM, Mike Feher  wrote:

> Hi all -
>
> Sorry for an ignorant question from an old man, but what does PoE stand
> for? Thanks & Regards - Mike
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell NJ 07731
> 848-245-9115
>
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Re: [time-nuts] Affordable PoE 6-digit time displays?

[Bob Bownes]

IRIG-B generator/displays candy had on eBay for very little money. There’s one 
currently listed for about $10. 

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F202337773272

Feeding one of these with the aforementioned NTP to IRIG – B is the easy 
solution. And they look great at the top of the rack!

I have a couple of these, and they drift significantly more than I would like, 
about 2 to 3 seconds a month. If anyone has seen the manual to one of these, 
I’d love to see a copy, as the input on the back are unmarked. 

> On Jun 15, 2018, at 14:38, Tim Shoppa  wrote:
> 
> At work we have POE LED clocks, I think 2.5", circa $400-$500. So your $300
> price you've been seeing is about right.
> 
> In terms of homebrew:
> 
> I bought a bunch of 3.5" high green Seven-segment displays 10+ years ago.
> Cheap, really cheap at the time!
> 
> Was always intending to build a 6-digit clock with them but never got
> around to it.
> 
> I have been having fun with ESP8266's (small cheap microcontrollers with
> WiFi) for other projects. If I were to do a NTP clock it would use the
> ESP8266 and NTP protocol over Wi-Fi. Not real NTPD, just NTP UDP packets
> plus a teeny bit of local dead reckoning.
> 
> Tim N3QE
> 
> On Thu, Jun 14, 2018 at 9:15 PM, David Andersen 
> wrote:
> 
>> I'd hoped that ebay or aliexpress would yield a bounty given how seemingly
>> simple these are, but I'm drawing a blank (and finding a lot of $300+ new
>> options).  Anyone have a favorite source for either flat wall-mount or
>> rackmount displays that will pull from an NTP/SNTP/whatever server?
>> 
>> (if wall-mount, PoE is optimal).  Used good.  Cheap good.  Looks good next
>> to my random collection of antiquated time measurement gear provides
>> amusement value but isn't really critical. :-)
>> 
>> Thanks!
>> 
>>  -Dave
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Re: [time-nuts] Affordable PoE 6-digit time displays?

[Bob Bownes]

Hal,

I remember there being such a thing, but a search of the ntp site turns up
nothing. Anything you can provide would be most welcome.

Thanks!
Bob


On Fri, Jun 15, 2018 at 12:20 AM, Hal Murray 
wrote:

>
> bow...@gmail.com said:
> > I’m still hunting for something that will take NTP in and put IRIG out.
> There
> > is probably someone doing it with a Pi or an Arduino.
>
> There is a module in the ntp package/collection that puts out IRIG from
> the
> system clock.  You can use NTP if you want to keep your clock sane.  I
> forget
> the name.  I'll fish it out if you can't find it.
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
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