Re: [time-nuts] Anybody have suggestions for time related science fair projects?

[Van Horn, David]

Ah. The falling water goes up illusion.
https://www.youtube.com/watch?v=GBtHeR-hY9Y

-Original Message-
From: time-nuts  On Behalf Of ed breya
Sent: Monday, May 14, 2018 2:01 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Anybody have suggestions for time related science fair 
projects?

I don't know what sort of scientific level this contest is geared for, but 
would guess that for middle-school level, extreme numbers-oriented analysis of 
esoteric, time-nutty things may not dazzle, but bore the participants, judges, 
and audience.

It may be best to relate to more hands-on, everyday experience and observations 
of "normal" people. I like the suggestions about GPS and stroboscopic and 
lasery stuff, where one can maybe appreciate how modern everyday things work 
(like GPS, or how it's possible to talk to or send a picture to anyone in the 
world on your cell phone, and how these could not happen without precise time), 
or something visual and physical.

Some of the props should be "ordinary" things, like the a cell phone or GPS 
receiver, for example. Lasers are always good as long as there's a direct 
visual component to the observation. Strobe type stuff is particularly easy, 
because it's doable with mechanical and acoustical props, and signal 
measurement times are in reach of common lab equipment like generators, scopes, 
and counters, and of course there's a big visual experience component.

Small power visible lasers are common nowadays, so easy to use. Strobe lights 
are fairly common too, but maybe not so much as the other items. 
You can build (or buy) quite a nice strobe light nowadays using high-powered 
LEDs - the kind used for replacing incandescent and other illumination. This is 
quite easy and much safer than dealing with flash tubes, and is much more 
versatile. In fact, maybe this could even be a science fair project. The time 
element is in the stroboscopic effects and ability to slow or freeze apparent 
motion - almost everyone has observed this and can relate.

Ed
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Re: [time-nuts] GPS Timing Antenna Failure - Long

[Van Horn, David]

There's a great article out there on the web. It takes a bit of digging, but 
the title is "Low voltage, the incompetent ignition source".
They discuss fires on PCBs caused by trace contaminants and dendrite growth.  A 
PCB with sustained flame is shown, powered by a lithium coin cell.


-Original Message-
From: time-nuts  On Behalf Of Larry McDavid
Sent: Monday, May 14, 2018 9:19 AM
To: Time-Nuts Mail List 
Subject: Re: [time-nuts] GPS Timing Antenna Failure - Long

Usually, in electronics, when we hear about "whiskers" we think of tin whisker 
growth. That is surely real but not all whiskers are tin. In fact, some 
whiskers are organic rather than metallic; sometimes these are even somewhat 
semi-conducting. Such conductance paths lead to very confusing troubleshooting 
results!

Rosin solder flux, RA (Rosin Activated) or RMA (Rosin Mildly Activated), 
contains organics that aggressively clean oxides from PWB pads and metal leads 
of components. This activated flux is actually corrosive and will often do 
strange things if left in place. It used to be that this flux was removed by 
vapor-phase TCE cleaning but that chemical got into ground water and is no 
longer used for flux cleaning. But, there are aqueous saponifiers that can 
clean rosin flux effectively.

Often, the final water rinse from assembled PWB cleaning is checked for 
conductance, even high ohmic conductance, and cleaning not deemed complete 
until this test is passed. Leaving activated rosin solder flux on an assembled 
PWB is a really bad thing to do.

I don't know what was in the dark brown flux residue I found on my Symmetricom 
antenna board, but it should not have been there. It would not have produced 
tin whisker growth but it could easily have produced other conductance paths 
across the soldered coax pads. Those could have been RF paths and not have 
caused higher dc current draw by the antenna.

Again, I can't be certain the flux residue caused my GPS antenna failure, but I 
believe it very likely and that is supported by the end result of fixing the 
antenna.

Unless someone has something new to add, surely we have beaten this topic to 
death. I was only trying to help others who might have a similar GPS antenna 
failure.

Larry



On 5/13/2018 6:42 PM, Hal Murray wrote:
> 
>>   I can't count the number of times flux and whisker  growth has 
>> caused problems in circuitry and connectors.
> 
> A whisker might explain things.  Would that also show up as over-current?
> ...

--
Best wishes,

Larry McDavid W6FUB
Anaheim, California  (SE of Los Angeles, near Disneyland) 
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Re: [time-nuts] Anybody have suggestions for time related science fair projects?

[Van Horn, David]

What I remember was a brown or black disc with holes around the perimeter.
I remember a lot of holes.
This was around 1991 or so.

-Original Message-
From: time-nuts  On Behalf Of Bruce Griffiths
Sent: Saturday, May 12, 2018 4:39 PM
To: Discussion of precise time and frequency measurement 
Subject: Re: [time-nuts] Anybody have suggestions for time related science fair 
projects?

Like this so called star target?:
https://www.edmundoptics.com/test-targets/resolution-test-targets/1-black-1-white-glass-star-target-5deg-wedge-pair-angle/

Bruce
> On 13 May 2018 at 02:45 Bob kb8tq  wrote:
> 
> 
> Hi
> 
> 
> 
> > On May 12, 2018, at 7:01 AM, jimlux  wrote:
> > 
> > On 5/11/18 9:08 PM, Jeff Woolsey wrote:
> >> David.vanhorn wrote:
> >>> Measuring the speed of light (Fizeau or Michelson method? Other 
> >>> ways)
> >>> 
> >>> 
> >>> I saw a great demo of this at the Exploratorium in SF.  They had a long 
> >>> spool of fiber optic, a disc with holes, and a light source.  When 
> >>> static, if the light shines through the hole in the disc into the fiber, 
> >>> then you can see the light coming out the other end of the fiber through 
> >>> a different hole.   When rotating, you increase speed and the fiber 
> >>> output gets dimmer and dimmer till it's gone.   At that point, the light 
> >>> going into the fiber arrives when the other end is blocked, and vice 
> >>> versa.  High tech, but simple.
> >>> 
> >> My favorite exhibit that we never see anymore.   IIRC it was a quarter
> >> mile of fiber and a green laser.  And ISTR that the disc had one 
> >> hole on one arm and two radially on the other, but I can't remember 
> >> why.  I thought that the light would pass through the same hole 
> >> twice, once on the way in and on the way out when that same hole 
> >> rotated 180 degrees to the other end of the fiber.  The disk spun 
> >> somewhere around 50 rps (60 with an AC motor?).
> > 
> > 
> > 1km in free space would be 6 microseconds round trip. I'm not sure a disk 
> > spinning at 3600 rpm would work.  you'd need to have the "hole spacing" be 
> > on the order of 6 microseconds - and at 100 rps (6000 RPM), 10 ms/rev, 
> > you'd need the sending and receiving hole 6/1 of a rev apart (about 0.2 
> > degrees).
> > 
> > if you had 10 km of fiber, it would be a bit easier.
> 
> I think the term “long fiber” in this case should really be “very very 
> long”.  Exactly how the typical student funds the acquisition of something in 
> the “many miles” range, I have no idea.
> 
> You could use an optical grating of some sort as your “spinning disk”. 
> The end of the fiber is going to be mighty small. The spacing on the grating 
> could be quite tight. Where you get a circular part like that ….
> again no idea. 
> 
> Bob
> 
> 
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Re: [time-nuts] Anybody have suggestions for time related science fair projects?

[Van Horn, David]

Measuring the speed of light (Fizeau or Michelson method? Other ways)


I saw a great demo of this at the Exploratorium in SF.  They had a long spool 
of fiber optic, a disc with holes, and a light source.  When static, if the 
light shines through the hole in the disc into the fiber, then you can see the 
light coming out the other end of the fiber through a different hole.   When 
rotating, you increase speed and the fiber output gets dimmer and dimmer till 
it's gone.   At that point, the light going into the fiber arrives when the 
other end is blocked, and vice versa.  High tech, but simple.  
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Re: [time-nuts] Terrestrial GPS

[Van Horn, David]

I've seen wifi location reporting me almost 2000 miles east of where I am. 


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Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

[Van Horn, David]

"Some  of you are to young to remember when Javanese products were considered 
junk same storyBert Kehren"

I've lived through Japan, Taiwan, and now China.  Who's next?  😊




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Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

[Van Horn, David]

I wasn't making any comment about Chinese goods, just the component in question.

-Original Message-
From: time-nuts 
[mailto:time-nuts-bounces+david.vanhorn=backcountryaccess@febo.com] On 
Behalf Of William H. Fite
Sent: Thursday, February 22, 2018 2:40 PM
To: Discussion of precise time and frequency measurement 
Subject: Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

I wish people would lighten up on Chinese goods. Perhaps you are not aware that 
China builds for and sells to both the DOD and NASA. Chinese manufacturers 
build to the specs they are given. You want cheap crap, they'll build cheap 
crap. You want top quality, they'll build top quality.


On Thursday, February 22, 2018, Van Horn, David < 
david.vanh...@backcountryaccess.com> wrote:

> According to the data sheet, it looks pretty well in spec, and the 
> part has thermal shutdown.
> http://ww1.microchip.com/downloads/en/DeviceDoc/mic5203.pdf
>
> ESD hit maybe?
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--
Patriotism is supporting your country all the time, and your government when it 
deserves it.
--Mark Twain

We may be surprised at the people we find in heaven. God has a soft spot for 
sinners. His standards are quite low.
--Desmond Tutu
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Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

[Van Horn, David]

According to the data sheet, it looks pretty well in spec, and the part has 
thermal shutdown.
http://ww1.microchip.com/downloads/en/DeviceDoc/mic5203.pdf

ESD hit maybe?
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Re: [time-nuts] Anyone have experience with this antenna?

[Van Horn, David]

In a previous job, I used plastics to "lens" antennas at 2.4 GHz, shaping the 
patterns for more desirable results. 
XFDTD is a great software package for this application but it is expensive.
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Re: [time-nuts] HP 105B: Modern replacement for NiCad battery pack?

[Van Horn, David]

Memory... :)

I've induced the "memory effect" in NIMH cells and Nicad, and lead acid.  
Simply charge to the same point, then discharge to the same depth of discharge 
about 10x.
In the next cycle, discharge completely and you'll see the bump in pack voltage 
where you had discharged to previously.
Now charge and discharge again and note that the vaunted memory effect is gone.

In real use, you are highly unlikely to charge and discharge precisely to the 
same point that many times.
NASA uncovered this in testing batteries for satellites (very special NICAD 
batteries) where due to solar cells and orbital mechanics, plus very consistent 
loads, they were seeing the problem.

Normal use, where the pack is discharged to different points (a few percent 
different) is all you need to prevent this.



-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke
Sent: Friday, January 5, 2018 11:48 AM
To: Ulf Kylenfall via time-nuts
Subject: Re: [time-nuts] HP 105B: Modern replacement for NiCad battery pack?

Hi Ulf:

There's another problem with switching to Ni-MH and that's related to the heat 
generated when charging them.  You can charge Ni-Cad batteries without 
monitoring the pack temperature, but with Ni-MH cells you must monitor the pack 
temperature.  I would suggest avoiding the Ni-MH option.  Either:
1. Just use modern Ni-Cad cells, no memory and much higher capacity, no change 
to the charger, or . .
2. Update to one of the Li-xxx chemistries with a totally new charger.  These 
batteries have much lower self discharge rates and higher energy density.

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

 Original Message 
>   
> Gentlemen,
> I may have asked this question before...
> I am looking for a modern replacement for the NiCadbattery pack used in the 
> HP 105B. One such 105that I salvaged have been standing on a shelf with 
> thebatteries "happily boiling away".
> So, what kind of chemistry would be possible to usewithout to much re-design 
> of the charging circuitry?
> Ulf Kylenfall
> SM6GXV
>
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Re: [time-nuts] HP 105B: Modern replacement for NiCad battery pack?

[Van Horn, David]

In a former job I designed battery charging systems for NIMH cells.
Some cells will TOLERATE long term trickle, some spec ZERO trickle current.  
Get a data sheet and read it.  

Violating that spec, or low quality cells can get you a battery pack that will 
arbitrarily, and without even being connected to anything, suddenly overhead 
and spew boiling lye out the end. One prototype did this with the pack 
literally sitting disconnected on the desk while we were out for dinner.  It 
took a few layers off the PCB that was sitting nearby.

I had specified cells from a Japanese company, but the accountants insisted I 
use cells from China at half the price.   Cost us a 100% recall of battery 
packs.



-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims
Sent: Friday, January 5, 2018 10:54 AM
To: time-nuts@febo.com
Subject: [time-nuts] HP 105B: Modern replacement for NiCad battery pack?

Since NiMH cells typically have over twice the capacity of NiCad cells, a C/10 
charger will charge them at less than C/20.It's best to trickle charge NiMH 
cells in the C/30 to C/40 range, but depending on the cell C/20 might be OK.   
Measure your charge current on a discharged pack and calculate the C rate.  
Tweak the charger supply for a C/30 to C/40 rate.

--

NIMH is not necessarily a drop in. While it will work fine in the short term, 
crude chargers that implement constant trickle like C/10 can be (emphasis) 
tolerated (/emphasis) by some NIMH cells, and totally out of spec for others.
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Re: [time-nuts] HP 105B: Modern replacement for NiCad battery pack?

[Van Horn, David]

Nicads are still made.

NIMH is not necessarily a drop in. While it will work fine in the short term, 
crude chargers that implement constant trickle like C/10 can be (emphasis) 
tolerated (/emphasis) by some NIMH cells, and totally out of spec for others.

Modern chargers and NIMH is a good pairing, but if you must use the original 
NICAD charger, you likely need real NICADs for a long term solution.


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed
Sent: Friday, January 5, 2018 10:00 AM
To: Ulf Kylenfall; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 105B: Modern replacement for NiCad battery pack?

Ulf
A drop in replacement for nicads is nickle metal hydride or NiMh. Nicads are 
still available but can be expensive.
The other comment I would make is the 1970s charging circuits were pretty crude 
and lead to boiled batteries.
If your going to invest in an internal battery you may want to consider a 
smarter modern charger.
There seems to be all sorts of very nice boards out of China for little cost. 
Its amazing.
If you go the alternate approach you may consider Lithium batteries.
Drones seemed to have made a very nice market for batteries and smart chargers.
Regards
Paul
WB8TSL

On Fri, Jan 5, 2018 at 11:46 AM, Ulf Kylenfall via time-nuts < 
time-nuts@febo.com> wrote:

>
> Gentlemen,
> I may have asked this question before...
> I am looking for a modern replacement for the NiCadbattery pack used 
> in the HP 105B. One such 105that I salvaged have been standing on a 
> shelf with thebatteries "happily boiling away".
> So, what kind of chemistry would be possible to usewithout to much 
> re-design of the charging circuitry?
> Ulf Kylenfall
> SM6GXV
>
> ___
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> https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow 
> the instructions there.
>
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Re: [time-nuts] External cooling fans - source

[Van Horn, David]

In the US, I have seen line voltage as low as 70VAC and as high as 145VAC. 
That's what I design to.
The power companies say different, but my meters don't lie.


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jeremy Nichols
Sent: Tuesday, December 19, 2017 9:20 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] External cooling fans - source

I put a small external fan on my 5370B, which keeps the heat sink at a 
reasonable low temperature (Time-Nut content) -but- (Nixon segué) the power 
company here also runs the voltage all the way up to the limit (126VAC) because 
"many of our [rural, like me] customers are all-electric and the load tends to 
pull the voltage down during times of peak use." The voltage got so high I 
finally put a recorder on it and walked the results into their office. In 
response, they attached their recorder to my connection and ran it for a couple 
of weeks before agreeing with me. Then they reluctantly turned the transformer 
down a notch so we stay below 126VAC now.

Jeremy

On Tue, Dec 19, 2017 at 5:44 AM Bob kb8tq  wrote:

> Hi
>
> Yes, this *is* a bit off topic. Sorry about that … I’m sure it’ll 
> never / ever happen again :) …. ummm …. today ….
>
> The voltage that supply feeds are set to is as much a public relations 
> issue as a technical one. People would routinely complain “the lights 
> are to dim”.
> Voltage
> gets bumped up. Complaints drop off. Eventually you are right at (or 
> as you observe marginally above) the max limits. Since the power 
> company is paid by the watt, the added power usage (if any) is not a 
> big deal. The call outs for checks
> *are* a big
> deal to them ….. complaints impact the metrics by which they are judged ….
>
> Bob
>
> > On Dec 19, 2017, at 12:48 AM, Dr. David Kirkby <
> drkir...@kirkbymicrowave.co.uk> wrote:
> >
> > On 18 December 2017 at 23:11, Charles Steinmetz 
> > 
> > wrote:
> >
> >> From time to time, the subject of external cooling fans comes up -- 
> >> for example, in discussions of the HP 5370A/B with their steaming 
> >> hot heatsinks.  I have several times recommended very quiet, all-metal, 4"
> desk
> >> fans as ideal for the job, but have not been able to suggest a source.
> >>
> >
> > For what it is worth, my 5370B run very hot, which forced me to 
> > check my mains voltage as I knew every time I had done a quick 
> > measurement, the voltage was above 230 V. So for a few days I logged 
> > the voltage, and
> found
> > it was consistently high. The maximum permitted here in the UK is 
> > 253 V, but I measured mine at 255.x volts. It was the heat of the 
> > 5370B that forced me to contact the electricity supply company (UK 
> > Power Networks), who logged the voltage for 4 days. I have a 3-phase 
> > supply here, which is unusual for a domestic property, but each of 
> > the 3 phases was
> consistently
> > high. I managed to get the supply company to reduce the voltage by 5%.
> That
> > made a *significant* difference in the heatsink temperature of the 
> > 5370B, and a significant difference to to the exhaust temperature of 
> > my HP 7 series system.
> >
> > I'm not saying an extra fan is not a good idea, but it is certainly 
> > worth ensuring the mains voltage is not too high. I was told by UK 
> > Power
> Networks
> > that they aim for 245-250 V in rural areas - this is despite the UK 
> > is supposed to be 230 -6%/+10%. On equipment with linear power 
> > supplies, a
> few
> > extra volts can lead to a significant increase in the amount of heat 
> > the regulators produce. 10% extra voltage does *not* equate to 10% 
> > extra
> power
> > dissipation, but considerably more.
> >
> > I found quite a reluctance on the part of the UK Power Networks to 
> > reduce the voltage. Even though it was was on average more than 5% 
> > high, the technical manager who took ownership of the problem only 
> > wanted to reduce the voltage by 2.5%, despite they could easily 
> > reduce it 5%. Luckily,
> when
> > the engineers came to adjust the supply voltage, (which they do by
> changing
> > the taps on the 11 kV primary), I managed to convince them that 
> > there
> were
> > very few properties on the transformer, and the furthest was an old
> couple
> > that used very little electricity. So they did reduce it 5%, which 
> > is the maximum they could. But they warned me that if there were 
> > complaints of
> low
> > voltage, they would have to increase it 2.5%. Luckily for me, nobody 
> > locally noticed the reduction in mains voltage, and it is still on
> average
> > over 230 V.
> >
> > It would be interesting to know how low the AC input can go on a 
> > 5370B before the regulators fail to regulate. Given they are the 
> > sort of instrument one might want to run for long periods, running 
> > one on a UPS, with a transformer to reduce the output of the UPS, 
> > might not be such a
> bad
> > idea.
> >
> >
> >> Charles
> >>
> >
> > Dave
> >

Re: [time-nuts] Trimble Thunderbolt no longer determines the correct date

[Van Horn, David]

Hmm.. Just a while ago, I watched the heather display on ours go to 12:59:59 
and stop...

Still giving me 10 MHz though which is all I really need.
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Re: [time-nuts] Power connectors continued

[Van Horn, David]

I have a design rule that I've used for decades: "If it fits, it works, or it 
does no harm."


-Original Message-


Why so many connecter types?   So you don't cross stuff up.

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Re: [time-nuts] How to love your Power Poles.

[Van Horn, David]

One thing I love about them is that you can create odd geometries.
All my ham gear, and generally anything I own that's 12V has APPs in the OC 
Races standard.
All lead acid sources are also same.

I could see using a different geometry for lithium batteries and the stuff that 
goes with them, and different colors, like black and orange or black and yellow 
to differentiate three and four cell packs.

They aren't the solution to every problem, but they are pretty slick.

I use big powerpoles on my jumper cables.  The other end is standard clips.  My 
battery has a permanent pigtail.  So I connect to the dead battery, then plug 
in which makes the connection safely away from either battery.

-Original Message-


That said I do have some power pole cables.  They work good for 12VDC lead acid 
battery type stuff.  But NEVER use then for exotic battery
chemistries.   Fires are not good.  and it WILL happen if you use PP
on Lithium type batteries, an accident waiting to happen.

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Re: [time-nuts] backfill (was: Poor man's oven)

[Van Horn, David]

Wouldn't the low density of helium reduce some mechanical friction?
I realize the motions are small but they are motions. 

The "Cousteau effect"?  :)
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Re: [time-nuts] Poor man's oven

[Van Horn, David]

You can feed in an external AREF, but look at the data sheet for the particular 
AVR chip.
One thing which is commonly ignored in Arduino-Land is the I/O pin leakage 
current and the maximum source impedance specs.
You are well advised to buffer the voltage you are reading, or make sure the 
source is low enough impedance that those errors won't get you.

All uCs have these issues, I just see this error made a lot in Arduino land.  
My 3D printer is Arduino based, and uses a 100k thermistor driving the Arduino 
directly.
The community makes claims that a degree or two of temperature change is 
important, and yet the circuit isn't capable of that much accuracy.



-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Harman
Sent: Tuesday, June 6, 2017 11:09 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Poor man's oven

On Tue, Jun 6, 2017 at 10:00 AM, Riley, Ian C CTR NSWC Philadelphia, 515 < 
ian.riley@navy.mil> wrote:

> Is there a practical minimum for what voltage you can feed into AREF?
>

It is hard to find on the data sheet, but the minimum voltage for an Arduino's 
AREF is the internal analog reference voltage - 1.1V for the Uno, 2.56V for the 
Leonardo or Micro. The 32U4 chip in the Leo and Micro has options for 
differential analog input and gains of 10, 40, or 200 but they are not 
supported by the Arduino IDE - you have to set the internal registers directly 
to use them. Also the input amplifier is pretty slow.


-- 

--Jim Harman
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Re: [time-nuts] Machining some aluminum help!

[Van Horn, David]

For popping off the lid, a few threaded holes in the lid would be nice.  Insert 
screws and let them push against the body and push the lid off.


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of ed breya
Sent: Thursday, May 25, 2017 3:08 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Machining some aluminum help!

This is the first time I've looked at time-nuts in about a month, and I noticed 
the run about this project. I'm very late to the party, but have a few 
suggestions that may help - if it's not too late. I quickly scanned many of the 
posts, and agree with many of the ideas. Please forgive if my suggestions are 
redundant to what's already been said.

First, I assume that the aluminum box is a simple extrusion, so it will likely 
be a soft alloy that will tend to gall horribly with machining - especially bad 
for anything that needs high precision. With these kinds of material, go big, 
starting with bigger fasteners. With 1/4" walls, you can easily up it to 6-32 
or 8-32, as long as the holes are fairly shallow, and you can jig it up for 
good centering and plumbness. With
4-40 and blind holes, you're just asking for trouble - especially taking a 
chance 40 times. The tap drill will be quite skinny, and prone to deform and 
wander as it goes in, and can easily be snapped off when it stalls due to the 
galling - and that's just the drilling stage - the tapping will be worse.

Bigger threads give you a chance to get it done with fewer fasteners and holes, 
and much less grief. The thread depth should allow for at least one 
pitch-diameter of penetration for strength, but preferably two or more, so you 
don't have to worry about finding exact right screw lengths that won't bottom 
out. Depending on the thickness of the end plates, you could get down to two or 
three fasteners per side to hold the small pressure needed.

If you're using a drill press, punch mark the hole centers, then use a center 
drill to make the pilot holes for the tap drill. If you're freehand drilling, 
put the piece on the floor and drill downward, keeping it as plumb as possible. 
Definitely use an oil or other lubricant for all the drilling and tapping 
operations.

For sealing, I'd recommend against fancy o-ring features and such - these are 
also harder to machine cleanly in soft aluminum, and add unnecessary 
complexity. If the end caps need regular remove and replace operations, then go 
with a pliable gasket, have more fasteners to get more uniform compression, and 
make the threads deeper so they'll last longer. If the sealing is one-time, or 
seldom needs to be broken, I'd recommend using a gasket sealing goop that will 
work fine with few fasteners and even rough surface finish. My favorite is 
Permatex #2 "Form-A-Gasket Sealant," which I've used for all sorts of stuff 
over fifty years (back then it was Radiator Specialties brand). Don't use a 
silicone goop unless you want to spend a lot of time scraping off the old stuff 
if it needs to be opened. If you do use a goop, it's a good idea to machine in 
features for prying the lids off, such as gasket-plane screwdriver slots, or 
extra tapped through-holes in line with the mounting holes on of the l
 id.

Ed
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Re: [time-nuts] HP10811 Oscillator Thermal Fuse

[Van Horn, David]

The original article was from Kodiak consulting.  Good thing I saved a copy. 
Thanks for the link to this one. 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Donald E. Pauly
Sent: Thursday, May 11, 2017 6:57 PM
To: time-nuts; Donald E. Pauly
Subject: [time-nuts] HP10811 Oscillator Thermal Fuse

https://www.febo.com/pipermail/time-nuts/2017-May/date.html

While I find traces of your article quoted, it seems to have vanished.
It lead me to this interesting article of 16 pages on electronic fires by a 
fire investigator.  There is a lot here for designers when it comes to 
preventing fires from your products.  I would never have dreamed of some of the 
ways that fires can start.

http://dri.org/docs/default-source/dri-online/course-materials/2016/fire-science/08-dangerous-things-come-in-small-packages.pdf


πθ°μΩω±√·Γλ
WB0KVV

-- Forwarded message --
From: Van Horn, David 
Date: Thu, May 11, 2017 at 4:31 PM
Subject: Re: [time-nuts] Fwd: HP10811 Oscillator Thermal Fuse
To: Discussion of precise time and frequency measurement 


There's an excellent article out there on the web called "Low Voltage, the 
incompetent ignition source"  I highly recommend a read.
I dealt with a case like this a couple years ago.  Failed fet in an H bridge 
caused a fault which the brick SMPS picked up as a short, and went into 
"hiccup" mode on.
The energy delivered in "hiccup" mode was about 1W average, and that was 
enough, after several hours, to cause ignition and sustained flame on the PCB.

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Re: [time-nuts] Fwd: HP10811 Oscillator Thermal Fuse

[Van Horn, David]

There's an excellent article out there on the web called "Low Voltage, the 
incompetent ignition source"  I highly recommend a read. 
I dealt with a case like this a couple years ago.  Failed fet in an H bridge 
caused a fault which the brick SMPS picked up as a short, and went into 
"hiccup" mode on.
The energy delivered in "hiccup" mode was about 1W average, and that was 
enough, after several hours, to cause ignition and sustained flame on the PCB.

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Re: [time-nuts] TAPR Oncore M12+ kit

[Van Horn, David]

Milling internally and externally to the perimeter of the board is a price 
adder, but is routinely done and not expensive.

I've done round PCBs with large, oddly shaped "round" holes in the middle, 
impossible to drill. 
I've done PCBs where the outer corners had to be milled to a specific radius.
I hold a patent on milling out a serpentine spring from the PCB material to 
support a magnetic read head.  (Saved us a ton in expenses for springs, 
brackets, screws and cables!)

Some of these low end shops may not actually have a mill, they may only have 
drills.  You sure wouldn’t want to try to mill with a PCB drill bit.

If they are objecting to milling, use a different shop.
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Re: [time-nuts] Bye-Bye Crystals

[Van Horn, David]

In my design I need 10ppM, and then I divide by 8.  Software can't correct for 
anything.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Bownes
Sent: Tuesday, March 14, 2017 10:50 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Bye-Bye Crystals

not to mention +/- a few hundred ppm is not a big deal.

You can always correct for it in software. ;)


On Tue, Mar 14, 2017 at 8:49 AM, jimlux  wrote:

> On 3/14/17 5:04 AM, Bob Camp wrote:
>
>> Hi
>>
>> The cost difference between a complete oscillator package and a 
>> simple
>>> crystal is tiny.  The osc is often cheaper if you include board 
>>> space or engineering time.
>>>
>>
>> Purchased in volume, the difference it the price of a crystal vs a 
>> complete XO is enormous. You will see at least a 10:1 cost savings on 
>> the crystal and likely more than that.  Simply attaching a crystal to 
>> the internal oscillator inside a chip is nearly zero engineering 
>> cost.  If your product is cost sensitive and not super tight 
>> tolerance … you go with the crystal.
>>
>>
> And that crystal business (gazillions of inexpensive 16 MHz crystals) 
> is very different from making an approximately 12 MHz crystal used in 
> a VCXO that will be FMed and multiplied up by 36 to make a 430 MHz 
> transmitter, oh, and that matches whatever temperature compensation 
> scheme GE used in 1970.
>
>
>
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Re: [time-nuts] Bye-Bye Crystals

[Van Horn, David]

Probably true for many things.   My current design has six crystals, and 
exactly none of them could be replaced by an oscillator module. 
Power and space considerations mostly. 

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

[Van Horn, David]

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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Re: [time-nuts] Totally unrelated, but..

[Van Horn, David]

Possible, but it should not need that, and the original design didn't include 
it.


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray
Sent: Wednesday, December 7, 2016 10:35 PM
To: Discussion of precise time and frequency measurement
Cc: hmur...@megapathdsl.net
Subject: Re: [time-nuts] Totally unrelated, but..


kb...@n1k.org said:
>> the cool thing about those parts is that their PSRR extends up to 
>> several MHz.  A lot of LDOs have good PSRR to kHz.
> Which to bring it back to noise in radios ….. could be the issue 
> there. The device isn’t oscillating, it’s just not blocking the crud from 
> upstream.

Would a simple L-C type filter on the input side solve that?

--
These are my opinions.  I hate spam.



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Re: [time-nuts] Totally unrelated, but..

[Van Horn, David]

I did check the circuit through the whole range that it should operate in, 
based on component data sheets. No issues.
I also carefully varied the voltage right around where the regulator output is, 
to see if there was some very narrow band of sensitivity.
Nothing.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Joe Leikhim
Sent: Wednesday, December 7, 2016 12:31 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Totally unrelated, but..

Could the low noise parts actually be counterfeit, relabeled as such?

Is the circuit the regulator feeds sensitive to a narrow band of voltage that 
the "good regulator" is outside of?

Try replacing the regulator with a battery supply and resistor divider to 
attain the working voltage. Move the voltage around. A good potentiometer and 
stiff filter capacitors are recommended so as not to introduce "pot noise".

Is something corrupting your test procedure?  I had a circuit that misbehaved 
due to floating logic pins reacting to static electricity on the work bench. 
Another time a diode was photosensitive.



--
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

jleik...@leikhim.com

407-982-0446

WWW.LEIKHIM.COM

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Re: [time-nuts] Totally unrelated, but..

[Van Horn, David]

Yes, I hit one of those. I forget the frequency other than around 1 MHz, but it 
was pretty warm when it shouldn't have been, and it was several volts amplitude.

This thing I'm chasing is much more subtle.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Chuck Harris
Sent: Wednesday, December 7, 2016 1:57 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Totally unrelated, but..

I don't think so.  I first ran into a batch of LM340-5's that were excellent 
oscillators back in the 1970's... long before counterfeiting was even remotely 
possible.

The symptom is the regulator puts out only 4.5 out of 5V.

LM309's were, however, totally immune.

Usually, I had to be really bad to make it happen, things like using clip leads 
between the power supply and load with the LM340-5 dangling in between.

The answer is as simple as a couple of 0.1uf ceramic caps soldered right at the 
input and ground, and the output and ground pins.

LDO (low dropout) regulators are very susceptible to oscillation.  They need to 
have a couple of hundred uf of good quality capacitance right on the input and 
output leads.  Where people usually get in trouble, is in not knowing that 
electrolytic capacitors lose most of their capacitance as the temperature 
starts hovering around 0C.

The circuit works great on the bench, but fails when out hanging on a light 
pole...

-Chuck Harris

Joe Leikhim wrote:
> Could the low noise parts actually be counterfeit, relabeled as such?
> 
> Is the circuit the regulator feeds sensitive to a narrow band of 
> voltage that the "good regulator" is outside of?
> 
> Try replacing the regulator with a battery supply and resistor divider 
> to attain the working voltage. Move the voltage around. A good 
> potentiometer and stiff filter capacitors are recommended so as not to 
> introduce "pot noise".
> 
> Is something corrupting your test procedure?  I had a circuit that 
> misbehaved due to floating logic pins reacting to static electricity 
> on the work bench. Another time a diode was photosensitive.
> 
> 
> 
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Re: [time-nuts] Totally unrelated, but..

[Van Horn, David]

I replaced the original caps, and I added caps, I substituted good Jonhansen RF 
caps, and Tanceram caps. 
No help at all.

The layout and routing is as good as I could do, and the only improvement I 
could see possible would be to move one cap closer to the reg.
The difference would be less than the tolerance of part placement on the 
existing pads.

Fortunately this isn't a critical piece of equipment, but I want it working 
RIGHT before I put it back in service.
It's a custom receiver for 457 kHz.


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Graham / KE9H
Sent: Wednesday, December 7, 2016 10:41 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Totally unrelated, but..

Remember that the internal Voltage reference in the original three terminal 
regulator designs is a Zener.
(Zeners are also useful as RF white noise sources.) The regulator is generally 
an amplifier with DC feedback.
If you look at the application notes on the early regulators, they require 
capacitors to ground on both the input and outputs.
If these capacitors are missing, or too low in value, or not good capacitors at 
RF frequencies, then the Zener noise is amplified by the regulator amplifier 
and pushed out the output port.
I would experiment by putting a good ceramic 0.1uF cap to ground, right at the 
regulator output port.


--- Graham

==


On Wed, Dec 7, 2016 at 10:43 AM, Bob Camp  wrote:

> Hi
>
> You probably have proven one of the most basic design truths: Parts 
> will
> *always* oscillate just
> outside the bandwidth of your test gear” :). A few other possible issues:
>
> 1) Something else is oscillating and it is simply interacting with the 
> regulator in an odd way.
> 2) The oscillation / noise is at a very low level and it’s below your 
> test gear’s noise floor
> 3) Testing stops the oscillation
>
> Bob
>
> > On Dec 6, 2016, at 4:24 PM, Van Horn, David  backcountryaccess.com> wrote:
> >
> > Lots of discussion on here about low noise regulation so someone may
> know what to look for.
> >
> > I have a receiver which is getting a lot of interference from somewhere.
> > Antenna disconnected, interference still high.
> > After much poking around, we found that replacing a voltage 
> > regulator
> with a slightly different part cures the problem.
> > Running that section on external battery is also fine, so it appears 
> > the
> original regulator causes some problem.
> > We tried various batteries over a range of voltages within the chip
> spec, and couldn't make it have a problem.
> >
> > I looked at the reg input and output with scope and spectrum 
> > analyzer,
> and I don't see anything that indicates excessive noise or oscillation.
> > The PCB layout is as tight as you could ask for. Fat tracks, lots of
> ground, I couldn't lay it out any better.
> > Replacing the input and output caps didn't change anything.
> > Replacing the input and output caps with parts that should be 
> > "better",
> like Johanson Tancerams or tantalums has no effect.
> >
> > Just for laughs, we tried a number of different regulator chips, all 
> > new
> from the reel.
> > The parts with the quietest and with the most noisy specs caused
> problems.
> > One part, with a noise spec more or less in the middle of the spread 
> > is
> the one that works.
> >
> > So what is it that a monolithic regulator (linear) can do which is 
> > not
> observable on a scope or SA, which would cause a receiver to think 
> it's getting a signal or significant noise in band?
> > Everything else in the system is shut down, I am sure the regulator 
> > chip
> is the culprit, but so far I don't see how it's causing the problem.
> > I could just use the quiet chip and move on, but experience tells me
> that I'd just have problems again down the road.  That's voodoo, not 
> science.
> >
> >
> > Ideas?
> >
> >
> >
> > --
> > David VanHorn
> > Lead Hardware Engineer
> >
> > Backcountry Access, Inc.
> > 2820 Wilderness Pl, Unit H
> > Boulder, CO  80301 USA
> > phone: 303-417-1345 x110
> > email: david.vanh...@backcountryaccess.com<mailto:david.vanhorn@
> backcountryaccess.com>
> >
> > ___
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> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
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Re: [time-nuts] Totally unrelated, but..

[Van Horn, David]

The probes don't seem to affect anything.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Andy
Sent: Wednesday, December 7, 2016 7:56 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Totally unrelated, but..

>
> I looked at the reg input and output with scope and spectrum analyzer, 
> and I don't see anything that indicates excessive noise or oscillation.
>

Does the receiver's noise persist with the scope or spectrum analyzer attached? 
 Connecting their probes might temporarily "fix" the problem so that it can 
never be observed.

Andy
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Re: [time-nuts] Totally unrelated, but..

[Van Horn, David]

Well so far at least #3 is not true.

It may be something happening below the noise floor or outside the bandwidth, 
but I was looking from 0-5MHz.
I have 3Ghz+ available, but I wouldn't expect these parts to be that fast.

It's a mystery, but I love solving mysteries.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp
Sent: Wednesday, December 7, 2016 9:43 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Totally unrelated, but..

Hi

You probably have proven one of the most basic design truths: Parts will 
*always* oscillate just outside the bandwidth of your test gear” :). A few 
other possible issues:

1) Something else is oscillating and it is simply interacting with the 
regulator in an odd way.
2) The oscillation / noise is at a very low level and it’s below your test 
gear’s noise floor
3) Testing stops the oscillation 

Bob

> On Dec 6, 2016, at 4:24 PM, Van Horn, David 
>  wrote:
> 
> Lots of discussion on here about low noise regulation so someone may know 
> what to look for.
> 
> I have a receiver which is getting a lot of interference from somewhere.
> Antenna disconnected, interference still high.
> After much poking around, we found that replacing a voltage regulator with a 
> slightly different part cures the problem.
> Running that section on external battery is also fine, so it appears the 
> original regulator causes some problem.
> We tried various batteries over a range of voltages within the chip spec, and 
> couldn't make it have a problem.
> 
> I looked at the reg input and output with scope and spectrum analyzer, and I 
> don't see anything that indicates excessive noise or oscillation.
> The PCB layout is as tight as you could ask for. Fat tracks, lots of ground, 
> I couldn't lay it out any better.
> Replacing the input and output caps didn't change anything.
> Replacing the input and output caps with parts that should be "better", like 
> Johanson Tancerams or tantalums has no effect.
> 
> Just for laughs, we tried a number of different regulator chips, all new from 
> the reel.
> The parts with the quietest and with the most noisy specs caused problems.
> One part, with a noise spec more or less in the middle of the spread is the 
> one that works.
> 
> So what is it that a monolithic regulator (linear) can do which is not 
> observable on a scope or SA, which would cause a receiver to think it's 
> getting a signal or significant noise in band?
> Everything else in the system is shut down, I am sure the regulator chip is 
> the culprit, but so far I don't see how it's causing the problem.
> I could just use the quiet chip and move on, but experience tells me that I'd 
> just have problems again down the road.  That's voodoo, not science.
> 
> 
> Ideas?
> 
> 
> 
> --
> David VanHorn
> Lead Hardware Engineer
> 
> Backcountry Access, Inc.
> 2820 Wilderness Pl, Unit H
> Boulder, CO  80301 USA
> phone: 303-417-1345  x110
> email: 
> david.vanh...@backcountryaccess.com<mailto:david.vanhorn@backcountryac
> cess.com>
> 
> ___
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[time-nuts] Totally unrelated, but..

[Van Horn, David]

Lots of discussion on here about low noise regulation so someone may know what 
to look for.

I have a receiver which is getting a lot of interference from somewhere.
Antenna disconnected, interference still high.
After much poking around, we found that replacing a voltage regulator with a 
slightly different part cures the problem.
Running that section on external battery is also fine, so it appears the 
original regulator causes some problem.
We tried various batteries over a range of voltages within the chip spec, and 
couldn't make it have a problem.

I looked at the reg input and output with scope and spectrum analyzer, and I 
don't see anything that indicates excessive noise or oscillation.
The PCB layout is as tight as you could ask for. Fat tracks, lots of ground, I 
couldn't lay it out any better.
Replacing the input and output caps didn't change anything.
Replacing the input and output caps with parts that should be "better", like 
Johanson Tancerams or tantalums has no effect.

Just for laughs, we tried a number of different regulator chips, all new from 
the reel.
The parts with the quietest and with the most noisy specs caused problems.
One part, with a noise spec more or less in the middle of the spread is the one 
that works.

So what is it that a monolithic regulator (linear) can do which is not 
observable on a scope or SA, which would cause a receiver to think it's getting 
a signal or significant noise in band?
Everything else in the system is shut down, I am sure the regulator chip is the 
culprit, but so far I don't see how it's causing the problem.
I could just use the quiet chip and move on, but experience tells me that I'd 
just have problems again down the road.  That's voodoo, not science.


Ideas?



--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: 
david.vanh...@backcountryaccess.com

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Re: [time-nuts] UCCM GPSDO

[Van Horn, David]

Yes.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Glen Hoag
Sent: Monday, December 5, 2016 12:14 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] UCCM GPSDO

94V-0 is a UL flame retardancy test, if I recall correctly. 

Sent from my iPhone

> On Dec 5, 2016, at 12:34, Tim Shoppa  wrote:
> 
> I was trying to guess what acronym (or backronym) UCCM might stand for.
> Then I did an E-bay search and found all the PC boards with "94V-0" in 
> their part numbers for sale E-bay. Ha! Literally thousands of hits.
> 
> Tim N3QE
> 
>> On Mon, Dec 5, 2016 at 7:42 AM, Bob Camp  wrote:
>> 
>> Hi
>> 
>> I’d bet it’s an inventory label put on by their customer. If so a 
>> good bet would be something like China Unicom.
>> 
>> Bob
>> 
>>> On Dec 4, 2016, at 5:50 PM, Larry McDavid  wrote:
>>> 
>>> Does anyone know the origin of the "UCCM" designation for the 
>>> Trimble
>> GPSDO boards recently popular here?
>>> 
>>> Is "UCCM" a valid model number, is it an acronym or is it something else?
>>> 
>>> I've packaged several of these Trimble boards and I've seen about 
>>> four
>> others, none of which was marked "UCCM." I've seen one on-line 
>> picture of a packaged board that shows a separate label with "UCCM" marked.
>>> 
>>> GPSCon already supports these "UCCM" boards and the next release of 
>>> Lady
>> Heather is expected to support them also, so there is some acceptance 
>> of this "UCCM" designation. But, what is the origin of this term and 
>> is it valid?
>>> 
>>> --
>>> Best wishes,
>>> 
>>> Larry McDavid W6FUB
>>> Anaheim, California  (SE of Los Angeles, near Disneyland) 
>>> ___
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Re: [time-nuts] Nutty time-nuttery with WWVB

[Van Horn, David]

I have, for many years, wished the FCC would get serious on enforcement. 
I've dealt with CEOs who said basically "ok, so it's illegal, who's going to 
catch us?"
I have on occasion had to physically stop shipments from being made.

If we had enforcement with TEETH then it would be easy to make the case to 
management that they stand a good chance of getting spanked in the wallet.
That's the only place a corporation has pain receptors.
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Re: [time-nuts] Nutty time-nuttery with WWVB

[Van Horn, David]

Enforcement.. It would be nice.


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Alex Pummer
Sent: Thursday, November 10, 2016 10:39 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Nutty time-nuttery with WWVB

And how about that many, many "radiator" which are moving up and down with 
their carriers and don't give a damn about FCC Part 15 and radiating radiating 
day and night with substantial power, I meant that FFC approved and not 
approved switching mode power supplies, of which every household has a hand 
full of it?

73
KJ6UHN
Alex

On 11/10/2016 9:22 AM, William H. Fite wrote:
> I heartily second Charles' admonition regarding FCC PART 15 unlicensed 
> transmissions. Part 15 explicitly states that an unlicensed operator 
> may not cause interference with any licensed transmission. Because of 
> the specific purpose of WWV/WWVB transmissions, any discernible 
> leakage detectable by any other user is prima facie evidence of 
> unlawful transmission and subject to a heavy fine. I assure you that 
> any licensed Part 97 user who detects your emissions over the top of 
> WWVB is quite likely to rat you out to Uncle Charlie. And should, may 
> I say, because you will be interfering with a public service. "I am 
> just syncing my clocks" is not going to impress the guys who appear in 
> your driveway in a white van with RDF antennas on the roof.
>
> Sobe very damned sure that you are not radiating a discernible 
> signal outside of the immediate vicinity of your clocks.
>
> Bill
> KJ4SLP
>
>
>
> On Thursday, November 10, 2016, Charles Steinmetz 
> 
> wrote:
>
>> Peter wrote:
>>
>> Could I implement my own personal WWVB transmitter that would
>>> be powerful enough to be picked up by the clocks in my house?
>>>   *   *   *
>>> Has anyone tried this?
>>>
>> Some on the list have, and I'm sure they will provide the details.
>>
>> Others have mentioned the potential problems with interference to 
>> other WWVB users.  For starters, make sure you study and understand 
>> Part 15 of the FCC rules before you put it on the air, or you could 
>> face a nasty enforcement action.  (Even if you are Part 15-compliant, 
>> you may still screw up other users' reception and get a visit from 
>> the FCC when they complain.  I operate several very sensitive 60kHz 
>> receivers -- if you live in my neighborhood, I'm almost certain to be 
>> unhappy about anything you
>> deploy.)
>>
>> Note that the problem with most "atomic" clocks that I've seen is 
>> actually not insufficient signal (in the wee hours of the morning, 
>> when they try to synch).  It is either excessive QRM, or orienting 
>> the clock so its antenna has a null toward Fort Collins.  Make sure 
>> the antenna has a major lobe toward Fort Collins (this may require 
>> relocating the entire clock or bringing the antenna out so you can 
>> orient it independently), and that it is well clear of the AC mains 
>> distribution wiring in your house and any other sources of QRM (wall 
>> warts, CFL lamps, LED lamps, etc. (this may also require relocating the 
>> clock).
>>
>> The typical clock using a loopstick antenna has lobes to the front 
>> and rear, and nulls to the sides.  Thus, mounting the clock on the 
>> western exterior wall (for users on the east coast) is usually best.  
>> Putting it directly in front of a west-facing window may help.
>>
>> Best regards,
>>
>> Charles
>>
>>
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>> the instructions there.
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>

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Re: [time-nuts] Temp/Humidity control systems

[Van Horn, David]

There is a wax which melts at 70F.  Phase change stores and releases a lot of 
heat.

Somewhat optimistic IMHO
https://www.wired.com/2015/05/table-sucks-heat-lower-ac-bills/

http://www.stacoolvest.com/news/

Technical:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4809117/
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Re: [time-nuts] For those that insist on using switching power supplies

[Van Horn, David]

To be fair here, phone chargers have almost no requirement to be quiet other 
than conducted and radiated emissions limits.
It's charging a battery.

As a designer of some fairly quiet SMPS systems, this feels like "look how bad 
a family car this tractor is".

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Re: [time-nuts] OXCO Spurious Output at Line Frequencies

[Van Horn, David]

Perhaps the aliens are replying to our signals, mostly saying "SHUT UP!!!"

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Poul-Henning 
Kamp
Sent: Wednesday, July 13, 2016 2:18 AM
To: Discussion of precise time and frequency measurement; Bob Camp
Subject: Re: [time-nuts] OXCO Spurious Output at Line Frequencies


In message <8bde1988-7c6b-4a20-9cbc-927cd8e85...@n1k.org>, Bob Camp writes:

>Simply running test gear on batteries did not do the job. Ultimately we 
>wound up in the middle of an Illinois corn field with a bunch of gear 
>modified to run purely on batteries. The spur did go down, but it never 
>fully went away.

Illinois is not going to be particular quiet place in that respect.

There are a lot of very big antennae all over the civilized world, in the form 
of power transmission lines, and they radiate when their phase-loading is not 
perfectly balanced.

As antennas they're horribly inefficient, the wavelengths are five and six 
thousand kilometers, but they do have the advantage of the the biggest 
transmitters in the world, and they are all phase synchronized in rather large 
geographies.

Dome C on Antartica is probably your best bet these days, provided you get far 
enough away from the gensets.

Poul-Henning

PS: I've heard from several sources a saga about when South Africa inaugurated 
the worlds longest high-voltage line, from hydropower at the north of the 
country to consumers a the south, and very little power came out at the far 
end.  The punch linie being that orbiting space-craft suffered a lot of 50Hz 
field strength while they debugged that issue.

-- 
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] HP5370 power supply measurements

[Van Horn, David]

Have you tried a 110V shaded pole motor fan?  Only 60Hz magnetic noise, no 
brushless commutation or brushes.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims
Sent: Wednesday, July 13, 2016 9:50 AM
To: time-nuts@febo.com
Subject: [time-nuts] HP5370 power supply measurements

I have replaced the fans in all my 5370's with quiet 12V  (150-250 mA) 
brushless DC fans running off of the 10V rail.   I placed themocouples around 
the inside of the unit and compared before and after temperatures and found no 
significant differences.  I have used several different models of fans... 
whatever the local surplus store had at the time.

I also replaced the fans in my HP16500 logic analyzers  (aka pizza ovens)  with 
much quieter fans.

-

> Speaking of fan noise -- you can't really get away with replacing the
internal fan with one that moves less air, so it is hard to find a replacement 
that generates significantly less noise.  If you find one, 
please share the make and model -- all 5370 owners would love to know.  
  
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Re: [time-nuts] How to properly characterize 32kHz oscillators manually and with a microcontroller?

[Van Horn, David]

>That all assumes you have turned interrupts off for some reason. Common 
>reasons  could be that you are in another interrupt service routine or that 
>you are executing interrupt related code. 
>
>Bob


What I saw in their interrupt routine was a "full boat" implementation, pretty 
typical for C code, saving registers without regard for what happens in the 
ISR, but nothing about the interrupts being turned off. 
If you mean not having re-enabled ints during the ISR, then yes, and that is 
how I would urge anyone to write an ISR.   The reason that you would re-enable 
ints during an ISR is that your ISR takes too long.
Making the ISR take even longer isn't really a solution.   Write faster ISRs. 

The key is to do absolutely as little housekeeping as needed, and have the ISR 
do as little as possible.

I have had cases where I didn't even preserve SREG because what I was doing in 
the ISR didn't alter SREG. 

Don't blame the hardware for poor implementation of software.

There really is no actual minimum code in an ISR.  In one case, I had a useful 
ISR that had actually no code in it!.  A very special case, but they happen. 
What I showed is my typical intro and outro code for probably 90% of what I 
write.  I avoid pushing and popping because it wastes time.  Copying SREG into 
a dedicated register is faster. Using dedicated ISR registers is faster than 
pushing and popping to free up registers.  

All this pushing and popping causes deep stack usage, which isn't even an 
option on some processors.  When your stack collides with your data, you're 
toast. It is to your significant advantage to minimize stack usage.

I will typically put a stack guard below where I expect the stack to live, and 
monitor that in the "sanity check" routine for any changes.  The sanity check 
routine looks at this and other things that I know should never change, and if 
they are not the correct values, then the watchdog won't be reset.  The sanity 
check routine is also the only place that the watchdog gets reset.WDRs 
scattered through the code are symptomatic of poorly written code.



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Re: [time-nuts] How to properly characterize 32kHz oscillators manually and with a microcontroller?

[Van Horn, David]

O M G..

So I followed the link and saw how they do it.Wow.  They write interrupts 
like the DMV processes applications. I can only imagine what this looks like on 
the PIC, where every instruction takes 4x as many cycles.
All of that pushing and popping is PRECISELY what you need to avoid. 
Pushing any register that the ISR does not actually change is totally insane.
My average ISR is far shorter than their intro and outro code.

"C" does not cooperate easily with this, but you can declare your interrupts 
"naked" and write them in assembler so as to avoid this insanity.

I say this as someone who has been developing on the AVR platform for something 
like 20 years.   My first application was on the 8515, and they didn't even 
have production silicon yet. My development was done on a chip with date code 
"ES"  (Engineering Sample)


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Re: [time-nuts] How to properly characterize 32kHz oscillators manually and with a microcontroller?

[Van Horn, David]

p...@heypete.com said:
> I'm a little concerned about the speed at which the pulses need to be
> counted. The 32kHz pulses come in every ~30.5 microseconds, and handling an
> interrupt on an ATmega328 running at 16MHz takes about 5.125 microseconds[1]

Huh?

Instruction cycle time is 62.5nS for almost all instructions at that clock.
That’s a pretty long ISR by my standards.

1: Reserve a couple of registers for handling data inside ISRs, avoiding push 
and pop.
2: Reserve a register for holding SREG during the ISR.

ISR:in STEMP,SREG
At this point you can fearlessly trash SREG and ITEMP and ITEMP2
Do Stuff using ITEMP and ITEMP2.
Do as little as practical in the ISR, letting the non-isr code do the 
heavy lifting.
Out SREG,STEMP
RETI

Optionally, set a register (I usually call it "ZERO") to 0x00 to speed up 16 
bit operations.
Keep data you need FAST in registers in the low page, rather than in RAM.





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Re: [time-nuts] Mains Frequency Monitor with the PIC 16F1619 (Daniel Watson)

[Van Horn, David]

Amusing story:

Back in high school,  Ewa Beach Hawaii, I used to notice that the second hand 
on the clocks would sometimes slow significantly.  This turned out to be caused 
by the man who would later become my father in law.
He ran the steel mill, melting old cars into rebar, which was electrically 
fired, and would slow down the Kahe point generator when he started the melt.   

I assume they dialed out those "bumps" through the day.

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Re: [time-nuts] GPS altitude somewhat wrong?

[Van Horn, David]

Using the thunderbolt here.

I only asked because a co-worker spotted the altitude and thought it was 
"wrong" for boulder.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims
Sent: Thursday, June 9, 2016 10:56 AM
To: time-nuts@febo.com
Subject: [time-nuts] GPS altitude somewhat wrong?

You have to be careful with a lot of modern GPS receivers.   Many implement 
some sort of "position pinning".   If they do not detect significant movement,  
they either stop updating the coordinates  or heavily filter it...  you do not 
see the actual computed location.  On some receivers you have to move well over 
10 meters before the position un-pins.
--
> CEP(95) of 1.5 meters over 1,000 seconds. 
>   
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Re: [time-nuts] GPS altitude somewhat wrong?

[Van Horn, David]

-Original Message-
From: time-nuts 
[mailto:time-nuts-bounces+david.vanhorn=backcountryaccess@febo.com] On 
Behalf Of Michael Perrett
Sent: Wednesday, June 8, 2016 4:33 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPS altitude somewhat wrong?

A couple of things come to mind:
1) Is this a single measurement or an average over at least 24 hours?

60+ hours

2) Did you get your elevation via the receiver survey mode (recommended)?

This is what's currently being displayed in LH after a 60 hour survey

3) How close is your "nominal" elevation measurement and what makes you think 
it is truth?

Damifino.  :)

4) The vertical component of the GPS position solution is typically 50% worse 
accuracy and a lot noisier than the horizontal measurement. If you have a good 
horizontal measurement it is unlikely you have a "wrong answer"
on elevation since your receiver is using the same data, just solving the 
equation for a different variable.

5) What is your satellite mask angle? The geometry (hence accuracy) degrades as 
an increasing function with mask angle. Suggest for the survey mode you use as 
low a mask angle as possible (typically 5 to 10 degrees).

Currently set to 5 degrees, which I know is low, but I wanted to see what the 
whole sky map looks like.
I will dial it up as we get things settled in.


Finally, your 214' error is outrageous. For a surveyed position the answer 
should be with +/- 10'.

Ok..



Michael Perrett

On Wed, Jun 8, 2016 at 1:33 PM, Van Horn, David < 
david.vanh...@backcountryaccess.com> wrote:

>
> I have just installed a Thunderbolt here to get our time and frequency 
> equipment all on the same page.
> As I was looking at the display on Lady Heather, I was noticing that 
> the GPS altitude seems rather wrong.
> We are in Boulder CO, which is nominally 5430' and the antenna is 
> about 20' off the ground.
> The display (near overdetermined position) reads 1589.72991 meters or 
> 5216 and change in feet.
> Altitude is a big deal around here. :)
>
> I suppose 214' isn't that outrageous, but it does bring me to a question:
>
> How accurate is the altitude number really?
>
> Thanks.
>
>
> --
> David VanHorn
> Lead Hardware Engineer
>
> Backcountry Access, Inc.
> 2820 Wilderness Pl, Unit H
> Boulder, CO  80301 USA
> phone: 303-417-1345 x110
> email: david.vanh...@backcountryaccess.com david.vanh...@backcountryaccess.com>
>
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Re: [time-nuts] GPS altitude somewhat wrong?

[Van Horn, David]

I'm satisfied that it's reasonably accurate now. 
It is interesting how much elevation can change without really being obvious to 
a person on the ground. 



-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Michael Perrett
Sent: Wednesday, June 8, 2016 5:28 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPS altitude somewhat wrong?

I just checked Google Earth and the elevation of your office is 5260', only 
about 24' off of your GPS estimate if that is your location.
Michael

On Wed, Jun 8, 2016 at 1:33 PM, Van Horn, David < 
david.vanh...@backcountryaccess.com> wrote:

>
> I have just installed a Thunderbolt here to get our time and frequency 
> equipment all on the same page.
> As I was looking at the display on Lady Heather, I was noticing that 
> the GPS altitude seems rather wrong.
> We are in Boulder CO, which is nominally 5430' and the antenna is 
> about 20' off the ground.
> The display (near overdetermined position) reads 1589.72991 meters or 
> 5216 and change in feet.
> Altitude is a big deal around here. :)
>
> I suppose 214' isn't that outrageous, but it does bring me to a question:
>
> How accurate is the altitude number really?
>
> Thanks.
>
>
> --
> David VanHorn
> Lead Hardware Engineer
>
> Backcountry Access, Inc.
> 2820 Wilderness Pl, Unit H
> Boulder, CO  80301 USA
> phone: 303-417-1345 x110
> email: david.vanh...@backcountryaccess.com david.vanh...@backcountryaccess.com>
>
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Re: [time-nuts] GPS altitude somewhat wrong?

[Van Horn, David]

Some of that is probably the difference between the geoid (what your surveyed 
maps report height relative to) and the WGS84 ellipsoid (what your GPS reports 
heights relative to).  At Boulder that difference is only about 15 meters, 
though.

Generally with VDOP < 2 and a reasonably modern receiver the accuracy of a GPS 
altitude measurement should be better than about 20 meters.
I'm not sure if the Thunderbolt counts as such.

How flat is Boulder?  Do you have a proper surveyed elevation of your location?

I do not.

The readout is plausibly right, but it is displaying to the nearest tenth of a 
millimeter which I thought was somewhat optimistic.  :)

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[time-nuts] GPS altitude somewhat wrong?

[Van Horn, David]

I have just installed a Thunderbolt here to get our time and frequency 
equipment all on the same page.
As I was looking at the display on Lady Heather, I was noticing that the GPS 
altitude seems rather wrong.
We are in Boulder CO, which is nominally 5430' and the antenna is about 20' off 
the ground.
The display (near overdetermined position) reads 1589.72991 meters or 5216 and 
change in feet.
Altitude is a big deal around here. :)

I suppose 214' isn't that outrageous, but it does bring me to a question:

How accurate is the altitude number really?

Thanks.


--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: 
david.vanh...@backcountryaccess.com

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