Re: [time-nuts] question about HP 5601a harmonic generator

[Morris Odell]

Hi,

Fortunately I have not had this problem but I did have to deal with a destroyed 
SRD in a HP 5110A  synthesizer driver a few years ago. The SRD in that device 
is maintained at an elevated temperature in a little oven and as a result of a 
thermostat failure it was reduced to a charred blob. With no possibility of 
finding an original  replacement I set the harmonic generator module up on the 
bench ( no easy feat!) and tried a range of different diodes to see if any of 
them would work. After a lot of experimentation I finally hit on a power 
varactor diode that was the final frequency multiplier in a junked cellphone 
transmitter from the original analog FM system that was eventually replaced 
with the current digital one. That diode was made by National Panasonic and is 
a gold plated stud mounted device. I had to fiddle around to fit it in but the 
5110A has not missed a beat since. Of course, in the 5110A it does operate at a 
much lower frequency than the 5061A, but it's original use was i
 n the upper VHF range I think.

If you can't find a replacement you might have to resort to similar 
experimentation .

Morris



> May I know if anyone knows the part number or the specification of the 
> step recovery diode in the harmonic generator for the old HP 5601A 
> cesium frequency standard?
> 


---
This email has been checked for viruses by AVG.
http://www.avg.com

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Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork

[Morris Odell]

> Most wristwatches do not have any temperature compensation. If worn, the 
> wristwatch is pretty close at the 25°C (the human body is a quite good and 
> temperature stable oven). The difference only starts to > show when the watch 
> isn't worn for long periods of time.

That explains my experience with the first microcontroller based clock I built 
years ago. I used a commercial module with a micro and some accessories 
including a watch crystal for timing. It's on a window ledge facing west in 
Australia where the temp varies during the year by 40°C. It was always a bit 
fast and I spent a lot of time checking my code to make sure I was dividing it 
by the right amount. I eventually tamed it by programming a short pause at 3:00 
am. I'm sure the temp of the watch crystal is very rarely 25°C!!

Morris

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Re: [time-nuts] Antique precision timing device without

[Morris Odell]

HI all,

Thanks to all those who responded to my post and also for the great pics of
other tuning forks. It's amazing that they were still being used for
electronic purposes as recently as the 1960s. Actually now that I think
about it I have seen little tuning forks used to check the function of
modern police speed radars so they still have some use. Musicians don't use
them any more - guitar players will know the little electronic tuning
devices clipped to the  neck of the instrument that displays the frequency
or key of each string. Doctors still use 125 Hz forks to test vibration
sense and higher frequency ones to test for conductive hearing loss. 

In answer to some of the questions posted: no there was no documentation
with the unit. The most useful thing was the "12 volts in" label on the
power socket so I knew where to start. The rest of it was necktop analysis.
The fork is maintained by means of a central electromagnet and small leaf
spring contacts on the tines - they also provide the 25 Hz power for the
motor which runs at 12 volts. Of course they would reduce the Q of the fork
a little and affect its resonance but I'm sure that was taken into  account
by the designer and the frequency & symmetry can be adjusted with the
weights on the ends. Operating current is about 0.5A at 12 volts when
running and 1A when the fork is not vibrating. There's a switch marked "Neon
Lamp" that controls the AC supply to a pair of clips between the tines of
the fork. They are about 3-4 inches apart and I have no idea what sort of
long thin tubular lamp would fit between them. Just for fun I'm going to
make a simple stroboscope with a 555 timer and some high intensity white
LEDs I have lying around to see if I can use it on the fork.

Cheers,

Morris

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[time-nuts] Antique precision timing device without electronics

[Morris Odell]

Hi all,

I was recently asked to resurrect this interesting device by a colleague who 
collects antique scientific instruments. It’s a "Chronoscope" made by the H. 
Tinsley company in London in the early 20th century and used to measure time 
intervals with the precision of those days. It's large and heavy in a polished 
wooden case with a top deck that hinges up to reveal the innards. 

The timing reference is a large tuning fork about 30 cm (1 foot) long and 
running at 25 cps. It's normally in a glass fronted housing (removed for the 
video) that includes a pair of hinged mechanical arms for starting it. It's 
maintained in oscillation by an electromagnet and contact arrangement powered 
from a 12V DC supply. The fork amplitude is controlled by a rheostat - too much 
and the tines impact on the magnet. The video frame rate makes the fork look 
slower than it actually is. I was able to extract a signal and measure the 
frequency with a modern GPS disciplined counter - it's 0.007% off its specified 
25 Hz! The frequency is too low for my HP 5372A so I was not able to easily get 
an idea of stability or do an ADEV measurement. The fork has quite a high Q and 
takes over a minute to stop oscillating after the power is turned off. There's 
a built in higher voltage AC power supply, probably a mains transformer, potted 
in beeswax in a polished wooden box inside that is intended to
  energise a large neon strobe lamp used to adjust the fork. Unfortunately the 
lamp was not with the unit and is no doubt irreplaceable. 

The 25 Hz signal is filtered by an LC network  and used to run a synchronous 
motor in the Chronoscope unit. Synchronous motors not being self-starting, you 
need to tweak a knob to get it going - there's a joke in there but I can't for 
the life of me think what it could be  The "Contact" switch and associated 
socket on the back controls an electromagnetic clutch that connects the 
clockwork counter mechanism to the motor and the contact "on" time is indicated 
on the dials with 10 mS resolution. 

There's not a single active device in there and after a clean and lube it runs 
very nicely from a modern 12V DC plugpack. My friend is very pleased with it 
and it will take pride of place in his collection. 

I'd be interested to know if any time nuts have knowledge or experience of this 
lovely instrument.

A video of it is at  https://youtu.be/i5S8WS9iN_E

Enjoy!

Morris

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Re: [time-nuts] Speaking clock

[Morris Odell]

Yes the monotonous voice is one reason why it shuts up after 2 minutes. There 
are better voice synthesizers available these days but I wanted to resurrect 
the old Votrax chip. Actually I suspect any voice wold get pretty irritating 
after many repetitions. My Toyota now has a choice of 3 GPS voices - we'll see 
how long that novelty lasts.

73, Morris

> Can I order one with a custom voice ? Say Dolly Parton or Sean Connery? 
> After about 15 minutes of the Steven Hawkins  one I would be tempted to 
> adjust the tone with an 8lb sledge hammer 8^)
-- 
> Dave

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[time-nuts] Speaking clock

[Morris Odell]

Hi all,

There was a thread about this a few weeks ago and I mentioned that I was
working on one with a "Stephen Hawking" voice - well here's a video:

https://youtu.be/lmg0YsHlB3g

So far it's not GPS controlled but that will come one day.

Cheers,

Morris

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[time-nuts] Speaking clock

[Morris Odell]

Hi Bill,

It uses a Votrax SC-01 speech synthesizer chip that I bought in a kit over 30 
years ago to use with the Apple II. The processor in this clock is an Atmel 
Mega-32 AVR and it gets its timing reference from the mains frequency. There's 
room to add a GPS receiver in future and make it recite the date as well as all 
sorts of other stuff. There's also a vintage IEI 40 column X 1 row vacuum 
fluorescent alphanumeric display that I had in the junque box for years, now 
resurrected to display the time and text as it speaks.  A PIR detector switches 
it on when someone is in front of it and it runs for a couple of minutes before 
going back to sleep. Inside all you can see is a few chips on boards, a speaker 
and a little power supply - nothing as impressive as the rotating disc clocks.

I like the idea that it sounds like Stephen Hawking, the man who has Isaac 
Newton's old job,  too.

I'm putting a few finishing touches to the wooden case and I'll put a video on 
YouTube when it's finished. It's winter down here in Australia and too cold in 
my garage to apply wood stain finishes!

Morris
--
Date: Wed, 6 Jul 2016 23:15:49 -0500
From: "Bill Hawkins" 

Hi Morris,

The idea of the author of "A Brief History of Time" telling the time
briefly has a certain appeal. 
Can you share some construction details? Even a parts list would be
useful.

Thanks,
Bill Hawkins


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Re: [time-nuts] Visiting Greenwich

[Morris Odell]

This is a terrific thread. I have been to Greenwich too and also some of the 
clock exhibits in London. There's a beautiful pendulum master and slave 
clock set up in the British Museum, and there's an original huge Caesium 
(British spelling!)  frequency standard in the Kensington Science Museum. 
The last time I was there in 2013 there was also a special feature 
exhibition about Alan Turing and the Bletchley code breakers.  I did pass 
through Bletchley station on the train about 20 years ago when I was in the 
UK but regrettably didn't have the time to stop there. I can recommend the 
climb up the hill at Greenwich to anyone - it's definitely worth the effort. 
They didn't allow photography of the Harrison clocks but I did manage to 
sneak one or two before the minder got to me :-)


I'd love to have a genuine electro-optical speaking clock. There's one in 
the Australian Telecom museum not far from where I live. There's also a 
terrific display of a complete electromechanical telephone exchange 
including a speaking clock in the telecommunications museum in Stockholm but 
as I don't speak Swedish I couldn't understand what it was saying.  I've 
just finished making a speaking clock using more modern technology, it uses 
a 30 year old speech synthesizer chip and sounds just like Stephen Hawking.


Morris
Melbourne, Australia
-
  Date: Wed, 6 Jul 2016 10:42:19 +1000
From: Jim Palfreyman 
To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Visiting Greenwich

Speaking of "speaking clocks" - here's two photos of the ones that used to
be used in Australia:

https://en.wikipedia.org/wiki/Speaking_clock#Australia

The top photo with rotating optical disks is a gorgeous piece of machinery.

The one below - I have one, and I keep it running.

:-)



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Re: [time-nuts] Fast risetime pulse generator

[Morris Odell]

Hi all,

Brooke Clark wrote:

> In the HP 5100 Frequency Synthesizer they use a heater on the SRD in order to 
> increase it's 
> lifetime so that the 3 MHz drive will generate the needed harmonics. 
> http://www.prc68.com/I/HP5100.shtml These 
> assemblies are no longer available and getting an SRD with a lifetime long 
> enough to work with a 3 MHz input is a common 
> as chicken teeth.  A solution is to get a large stud mounted Varactor and 
> these do have long lifetimes.

I was so pleased to see this. It mirrored my experience exactly. A few years 
ago I restored a 5100A and its 5110A exciter. The SRD heater in the 5110A had 
developed a failed thermostat and was a charred blob. I made up a test jig and 
tested lots and lots of different diodes and as it turned out, the best 
candidate was a stud mounted varactor out of a junked transmitter from the old 
VHF cellphone system. It's worked like a charm ever since. This post (and 
webpage) has explained it beautifully.

Morris



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Re: [time-nuts] Building a mains frequency monitor

[Morris Odell]

Hi all,

This is an interesting thread. I have built many clocks using the mains as a 
reference and have settled on a "belt and braces" approach that works well 
and does not seem to pass noise or transients. I begin with low voltage AC 
from the mains transformer and use it to feed the input diodes in a dual 
optocoupler back to back through a single pole LPF made up of the 
appropriate current limiting resistor and as big a cap as I can get away 
with. On the output side the phototransistors are paralleled and thus 
produce pulses at double the mains frequency. These are used to injection 
lock a free running oscillator made from one stage of a 1489 quad line 
receiver followed by another stage in cascade. The end result in a nice 
train of clean square waves. It's cheap and easy and doesn't take up too 
much PCB real estate.


Morris 



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Re: [time-nuts] Glass Envelope Quartz Crystals

[Morris Odell]

This is a very interesting discussion. I have experimented with some audio 
frequency crystals in the 3-6 kHz range. I don't know what they came out of but 
it was probably some sort of FDM telephony or telegraphy equipment. They're in 
the form of vacuum mounted bars with 4 plated terminals in tall 7 pin or octal 
tube envelopes. When suitably driven they oscillate audibly like a bell ringing 
and as a result of the very high Q they even keep ringing for a few seconds 
after the power is turned off. Unfortunately I don't have access to a 
stroboscope. I'd like to do something useful with them on display, perhaps a 
clock for people with presbyacusis who wouldn't notice the sound :-)

Morris

>> You have it right, iovane. At the least, they should be protected 
>> from light,
>> thermal radiation, and emf.   Won'drous things will happen if the 
>> crystal and
>> its structure are subjected to radiation through the glass. I'd 
>> suggest a foam gator wrap in a tin can as a minimum. Put the 
>> oscillator cat in there too.
>
>   I have a 100 kHz glass "Crystal Unit" made by G.E.C., type JCF/193 
> with a serial number and sealed in a valve/tube with seven pins.
> I removed it from my Eddystone EA12 that I bought from Tom Roberts, 
> G3YTO, SK 1985. It has a black shield with a spring inside at the top 
> so that it grips the base. The valve that produced 100 kHz markers for 
> dial calibration failed and I don't use the EA12 these days.
> It will be interesting to see how stable it is and what the effect of 
> light and heat on it is when I start experimenting.

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Re: [time-nuts] HP 5372A troubleshooting

[Morris Odell]

Adrian,

Thanks very much! I had no idea those scans were available for the 5371A. I'll 
download them at once.

Regards,

Morris
---
From: Adrian 

Morris,

you might want to download the 5371A service manuals which contain
schematics.
The 5372A being an 'upgraded' version of the 5371A, most of its parts
are identical.
Look for 05371-90018 (Vol.1) and 05371-90034 (Vol.2).
They should be available at www.keysight.com
The scan quality is surprisingly good.

The A10 regulator board is in Vol.2 on p. 7I-9.
The -15 are generated out of the unregulated +25V by a switch mode
regulator, so there should be much less (40kHz switch frequency) ripple
than described.
Otherwise the obvious electrolytics are to be suspected (in particular
C17, but also C7, C24).

Regards,
Adrian

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[time-nuts] HP 5372A troubleshooting

[Morris Odell]

Hi all,

I have been on a steep learning curve on my new 5372A. It's a lovely
instrument but does seem to have a higher degree of trigger jitter than I
would expect. Going on previous experience with other unrelated instruments
I began by checking the power supplies. (in fact it's hard to go much deeper
without the unobtainium extenders :-(

Anyway the power supplies all check out OK voltage wise but the -15 does
have a higher amount of twice mains freq ripple than the others. It's about
0.5 V p-p at the test point on the triple regulator board and looks like a
sawtooth i.e. what you see from inadequate filtering. The service manual is
unhelpful as it doesn't give schematics, just says to replace the regulator
board! The -15 features on the schematics for many other parts of the 5372A
that would be expected to contribute to trigger stability. 

My questions are:

1. Could anyone on the list with a functioning 5372A slip a scope probe onto
the -15V test point and check the ripple on a known good unit?

and

2. Has anyone had to deal with this this problem before?

Thanks,

Morris


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Re: [time-nuts] HP 5372A advice

[Morris Odell]

Thanks Gary,

Thanks very much for your very helpful reply. I found those 2 operators manuals 
and downloaded them. The Keysight website is slightly confusing as those 
manuals were not in the same place as the others I found. I now have some great 
reading to catch up on!!

Morris


From: Gary Chatters 
 [...]
>
> I have downloaded what's there, unfortunately there's no operator's manual 
> but I did the "Getting Started Guide" with the instrument. The prog manual 
> might stimulate me to get GPIB up and running.
>

The Keysight website has eight manuals for the HP5372A, including two 
versions of "5372A Frequency and Time Interval Analyzer Operating 
Manual".  Is this not what you need?

There are also a Service Manual and a Programming Manual and others.

[...]


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Re: [time-nuts] HP 5372A advice

[Morris Odell]

Thanks very much for your reply Magnus,

> I strongly advice you to download the manuals. It is an instrument that 
> is puzzling at times, so the manuals are needed. The upside is that they 
> are really interesting. The operators and programming manuals get you 
> understand what it really does. You also want the service manual.
> Anyway, last time I looked I could download them from Agilent/Keysight.

I have downloaded what's there, unfortunately there's no operator's manual but 
I did the "Getting Started Guide" with the instrument. The prog manual might 
stimulate me to get GPIB up and running.

> Trigger jitter. More importantly, now you see it!
> The trigger jitter follows the formula:

> t_jitter = e_n / S

> e_n is the noise voltage RMS value
> S is the slew-rate
> t_jitter is the trigger jitter RMS value


That explains it nicely! As you would expect the jitter is much less when a 
square wave is the input. I will look into the manuals to see the spec and what 
can be done about it. Measuring it as you suggest will be an interesting 
project. Maybe it's something that resulted from the long period of inactivity 
the device had. I will also check the power supplies for voltage accuracy and 
ripple. 

Thanks again,

Morris VK3DOC
Melbourne, Australia

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[time-nuts] HP 5372A advice

[Morris Odell]

Hi all,

I recently was fortunate enough to obtain one of these amazing instruments 
but regrettable no copy of the main operating manual. I find myself a bit 
puzzled by some of it's behaviour.


The unit is clean and passes all the self-tests. When I first got it it 
seemed to work very nicely looking at my in-house 10 MHz frequency standard 
which is a Z3815 GPSDO. It needed a new memory back up battery and once I 
replaced it I tried to do the input sensitivity recalibration procedure 
that's required. That procedure  requires the application of a 10 KHz 60 mv 
p-p sine wave and that's when I ran into trouble.


I have found that if I and try to look at low frequency signals with the 
5372A they appear to have enormous levels of variation and appear quite 
erratic. The histogram display just shows peaks all over the place. I have 
tried with 10 KHz from a 3325B and 100 KHz from a 8656B both of which use 
the GPSDO as a reference and they both show enormous variation. It's the 
same whether I use the GPSDO as a ref for the 5372A or it's own internal 
ref.  If I apply 10 MHz and above from either of the two generators all 
looks well but there are occasional glitches. Using the A or B inputs or 
swapping input pods makes no difference. With VHF and UHF frequencies up to 
the 990 MHz limit of the 8656B it seems to work perfectly using the C 
channel of the 5372B.


I thought it might have been something to do with the synthesized nature of 
the 3325 and 8656 so I warmed up the old faithful 200CD at 10 KHz and it 
didn't make any difference although the 200CD would never be as stable as a 
more modern synthesized source locked to the GPS. I haven't tried it yet 
with anything higher in frequency although I do have a 2 GHz non-synthesized 
generator I could set up.


What's going on here? Any ideas? Do I need to change any of the input, 
trigger or arming settings? So far nothing I have tried in the way of 
changing settings makes any difference.


Thanks in anticipation,

Morris





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Re: [time-nuts] Generating a solid PPS from 10Mhz source

[Morris Odell]

Thanks to everyone who responded.

I guess I'm just showing my age (66). 

Of course all those considerations of cost etc are all true especially in the 
world of the professional who has to make the product feasible for the market. 
I'm a basement tinkerer with a well-stocked junk box for whom the more complex 
something is the better. I also have no time constraints. Whether it costs $1 
or $10 doesn't mean a lot in that world, it's still less than a bottle of good 
wine!

Morris

> Why use a board full of TTL when an $1 8-pin chip will do it ?


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Re: [time-nuts] Generating a solid PPS from 10Mhz source

[Morris Odell]

Am I missing something here?

I understand the ease and fun of programming up an AVR as much as anyone but 
surely this task could be accomplished  easily with a chain of fast 
synchronous TTL or CMOS dividers. A resynchronising FF could also be added 
at the end to  clean up the 1 pps if required. You wouldn't need to worry 
about the maths or OBOBs either.


Admittedly you would need more PCB real estate but that shouldn't be a big 
deal in most cases.


Morris




If anyone is interested in the equivalent functionality using an ATTiny25 
(for instance, if you’re already heavily invested in AVR instead of PIC, 
like I am), ping me. I’ve privately written code to solve almost the same 
problem and it could easily be adapted into doing the same job.






Is there an easy circuit to build that can consistently deliver a 1 PPS 
from a 10MHz source with excellent resolution and repeatability?  My 
first application is to test different 10MHz oscillators without a TIC 
always attached and then compare the PPS output change over time 
against a master GPSDO PPS with an HP53132A.


The circuit used for PPS generation would have to deliver consistent 
PPS output with preferably not more than 100ps noise or jitter, 
assuming a perfect source.  I'm totally guessing that for this 
resolution, the PPS would have to be generated and accurate to within 
0.001Hz every second.  If this is too difficult, maybe the integration 
time can be increased to generate one pulse every 10second or every 
100,000,000.00 cycles?



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Re: [time-nuts] Springer textbooks >10 years old now available for download as PDF at no cost

[Morris Odell]

Dunno about a court case, but my many years of experience of academic 
publishers is that they are very tight about releasing any freebies at all, 
even old ones. I was quite surprised to see that free pdfs were available and 
thought at the time that someone at Springer probably goofed.

Springer is not the worst of them but is certainly up there in terms of 
difficulty getting free access. Once you see a tantalising reference to 
something in a journal published by a top level academic publishers you usually 
know  that you will either have to pay or go through an institutional library 
to download it. 

Morris

> Seems to me that there was a court case where Springer was ordered to follow 
> through on its promise to release all books and academic papers to the public 
> domain after something like 5 or 10 years.

> Anybody else remember anything like that?

> -Chuck Harris


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[time-nuts] TAC32 not behaving properly

[Morris Odell]

Hi all,

I have what I hope is a minor problem with TAC32 software. I'm running it on
a Windows 7 machine and using it to monitor a Motorola VP Oncore receiver in
my master clock. The seems to work OK but when I turn on the sound effects
it only sounds the second ticks when it's synchronizing i.e. when the time
display is red. Once it's locked on to the receiver and the display turns
black the ticks stop but it still beeps at the head of each minute. In the
past it's worked properly but since I had the machine down while my study
was being renovated it's started doing this.

Has anyone else had this problem or know of a solution?

Thanks,

Morris


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Re: [time-nuts] Lord Vetinari wall clock

[Morris Odell]

Such a clock would be regularly irregular  in medical jargon. You could put 
it in a cardiologist's waiting room where patients with rhythm disorders are 
waiting but it might upset them :-)

Morris
--
Date: Sun, 02 Nov 2014 08:48:09 -0500
From: Mike Baker mp...@clanbaker.org
To: time-nuts@febo.com
Subject: [time-nuts] Lord Vetinari wall clock
Message-ID: 54563619.4010...@clanbaker.org
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Time-Nutters--

I have been tempted to build a (hacked) wall clock (after Lord Vetinari) that 
has an erratic second hand that sometimes skips ticks and sometimes ticks 
several times very rapidly but still keeps correct
time.   I would love to put one of these up on a doctor's
patient waiting room wall just to see what people's reactions are.
*

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Re: [time-nuts] microcontroller based IRIG generator

[Morris Odell]

I did this successfully a few years ago using an AVR 90S8535 to generate  
IRIG B so that I could use a vintage nixie IRIG display with a Trimble  
Lassen IQ GPS receiver that spoke NMEA IIRC.


I used one of the counters in the AVR to generate the 1 KHz carrier, read  
the serial output of the receiver with the USART in the AVR, translated it  
and generated a binary IRIG code to modulate the carrier by switching the  
bottom of a resistive divider up and down.


It wasn't too hard as I recall, and I was much less experienced in AVR  
programming in those days.


Morris





Date: Mon, 23 Jun 2014 12:26:40 -0400
From: Bob Bownes bow...@gmail.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] microcontroller based IRIG generator
Message-ID:
CACsYtUsmAdz_08+Z8sHEh=koPuCkko263ijh3HkA89yz=b0...@mail.gmail.com
Content-Type: text/plain; charset=UTF-8

I remember a few discussions over the last few years about building a
microcontroller (PIC, Arduino, MPS430, whatever floats your boat) based
IRIG generator. Did anyone ever get one working?


Thanks!
Bob


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[time-nuts] OT - indicator question

[Morris Odell]

Hi all,

I have a question a bit OT but related to time nuttery. I like making
unusual GPS controlled clocks including CRT displays like this:

https://www.youtube.com/watch?v=Jjs7AWL8B1k

A few years ago I picked up a 1970s vintage Japanese made Sperry Mk-8 Radar
indicator unit with the intention of making a large screen radar clock. It's
finally getting some bench time and before starting on a long and painful
reverse engineering effort I was wondering whether anyone might have some
data or schematics about it. It will be an interesting challenge - I've
never done anything with a magnetically deflected CRT before.

There are a few familiar bits such as the power supplies, video amp and IF
strip but there's also some other boards which might be sweep generators or
circle generators etc. Alas no deflection amplifiers - the yoke cable goes
to a connector on the back panel. It's all discrete technology, no ICs. 

If this sounds familiar to any of the knowledgeable people here I'd love to
hear from you .

Thanks,

Morris

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[time-nuts] Z3815 receiver transplant now fixed

[Morris Odell]

Hi all,

Well I've got it working absolutely perfectly now. My thanks to Dave Brown
of this list who sent me a manual for the GT-74! The problem wasn't the
receiver output message but the unusual antenna feed situation in the Z3815
that baffled me for a while. Briefly, GPS receivers feed the antenna
connection with DC for the amplifier in the antenna and sense when it's
under or over current for a software message re antenna health. In the Z3815
the receiver interface 5V antenna power pin is supplied with 5 V but the
antenna cable from the receiver is capacitively isolated and possibly loaded
(haven't checked yet) on the mother board and the antenna is fed from an
independent 5V antenna supply which is monitored on the mother board, hence
the alarm situation. I had an antenna directly connected to my new receiver
and put a suitable load on the antenna power pin of the Z3815 connector but
that didn't solve the problem. It wasn't till I loaded the (non-functional)
Z3815 antenna connection that the alarm was cleared. 

The u.fl antenna lead connector that comes with the receiver would, I think,
fit the connection on the mother board. Unfortunately the Chinese u.fl to
SMA connector that I wasted $1.60 on was perfidiously the wrong size so I
cut off the tiny connector in a fit of pique and terminated it on a BNC. No
matter, I can salvage the cable from the old receiver as I'm going to
butcher it anyway for the unusual 2mm pitch interface connector. Now that I
know what's what I'm going to make a new interface board on which to mount
the new receiver and then put it all together again.

If anyone here wants to go down the same route, let me know and I'll send
you the PCB pattern and schematic. I still use DOS based Easytrax to make
PCBs but print to a file which you can output to a printer if you can
remember how to drive a DOS window :-)

Morris VK3DOC

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Re: [time-nuts] Z3815A date problem fixed?

[Morris Odell]

Thanks for the reply Magnus. I know the frequency control function is
unaffected by the date problem but I'm far too obsessional to ignore it :-)

I contemplated the AVR solution to correct the code but once I looked at the
output of the receiver with a MAX232 as suggested here, I found there were
quite a few different and varying NMEA and proprietary sentences being sent
each second and most of them contained the time  date in one form or
another. Not knowing which ones the Z39815 relies on means they all have to
be identified and corrected. Programming an AVR to fix this would not be
beyond me but it would be complex and time consuming compared to the
receiver transplant and I'd still have to make the hardware for the AVR. It
would also mean finding a bit of room inside the Z3815 to fit an AVR board .
It's also sort of kludgy, like wearing gloves because your pen leaks. 

Better, I think, to transplant the receiver. The GT-8031 will suffer a
similar fate according to the spec, at midnight on December 31, 2079 but
I'll be 130 years old then so probably won't need to replace it again

Morris
 

From: Magnus Danielson mag...@rubidium.dyndns.org

On 24/01/14 11:59, Morris Odell wrote:
 Hi all,

 There was some consternation here 5 months ago when Z3815A GPSDOs began
 reporting a date 1024 weeks in the past. This was due to a storage
overflow
 condition in the Furuno GPS receiver in the Z3915A. The designers probably
 never anticipated that they would still be in use 20 years later
 Oscillator discipline was unaffected as the 1 pps was still good.

It's kind of expected that the oscillator discipline works, because all 
what has happen is that the conversion from GPS time to normal time 
(being GPS or UTC) has been unable to unwrap the GPS week number 
properly. It's really a problem with the system than with the receiver.

 Obsessional types like me looked for a solution. There didn't seem to be
any
 knowledge out there about reprogramming the receivers so it had to be a
 transplant.

Interesting approach. There is two things one can do: Toss in a small 
PIC/AVR/whatever that modifies the time, or update to a receiver which 
does not have the issue. You can also just completely ignore the fact :)

Cheers,
Magnus



--

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End of time-nuts Digest, Vol 114, Issue 96
**


-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2014.0.4259 / Virus Database: 3681/7031 - Release Date: 01/24/14

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[time-nuts] Z3815A date problem fixed?

[Morris Odell]

Hi all,

There was some consternation here 5 months ago when Z3815A GPSDOs began
reporting a date 1024 weeks in the past. This was due to a storage overflow
condition in the Furuno GPS receiver in the Z3915A. The designers probably
never anticipated that they would still be in use 20 years later
Oscillator discipline was unaffected as the 1 pps was still good.

Obsessional types like me looked for a solution. There didn't seem to be any
knowledge out there about reprogramming the receivers so it had to be a
transplant.

Furuno GT-8031 timing receivers are available on ebay and not prohibitively
expensive. They are about half the size of a matchbox and work at 3.3V TTL
levels. The interface connector is a 2mm pitch 2X5 pin header and the
antenna connection is a pigtail with a Hirose u.fl connector. The interface
is 9600,n,8,1.  I picked one up a few months ago and it took a while to get
the appropriate connectors etc but I eventually found enough time to make a
little interface PCB compete with a Li button cell backup battery. I lashed
it up tonight into the Z3815A and it works!!! 

The GPS locks the oscillator and the Z3815A reports the correct time  date.
As I write this it's been going for an hour or so and the survey is not
complete, the Z3815A still reporting reduced accuracy. It is showing an
antenna alarm for some reason so the yellow operation alarm LED is lit.
That may be because I'm powering the receiver externally at the moment and
there would be no current being drawn from the Z3815A 5 volt supply. I'll
work on that in the morning. The interface board draws a total of about 100
mA including the antenna current and I'm hoping that won't be high enough to
give an antenna alarm in the other direction. If so I'll have to change the
3.3 volt supply from being zener stabilized to being series voltage dropped.

More news as it breaks!!

Morris

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[time-nuts] Z3815A receiver transplant

[Morris Odell]

Hi all,

The Z3815A is working perfectly with the new receiver except for a
persistent antenna alarm. The new receiver is reporting the antenna is OK
but it must have a different self-test answer sentence to the old one. The
self-test is a PFEC sentence, which is proprietary to the manufacturer and
not part of the standard NMEA protocol. It's responding appropriately to
self-test requests from the motherboard but obviously there's a difference
in the answer sentence which reports antenna integrity. I've tested it with
two different antennas and they both see lots of sats  properly but still
produce that alarm. 

If anyone here has any documentation or manuals for the Furuno GT-74 I would
be very grateful for copies. If I can find the reason for the persistent
alarm and it's a difference in the self-test answer, I'll make up a new
interface with a microcontroller to emulate the old receiver and then it
will be indistinguishable!

Morris VK3DOC in Melbourne, Australia



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Re: [time-nuts] Reducing lab noise with LED lighting.

[Morris Odell]

I've tried that with a replacement tube that worked with the original
ballast, all you had to do was remove the starter.

The results were horrible. The tube was about a metre above my scope and
waving the probe about showed horrible spikes and damped oscillatory
waveforms up to several volts in amplitude. Needless to say I'm back to a
conventional fluoro.

The discussion about LED flicker was interesting. As I understand it the
human eye can act as a peak detector so it responds quite well to pulsed
lights at a high enough frequency. I'm currently (boom boom) illuminating an
ornamental vacuum tube display with a strip of white LEDs powered by full
wave rectified but unfiltered DC at 100 Hz (in a 50 Hz country). It's in an
otherwise dim corner and there's never been any hint of visible flicker to
me or anyone else. 

Morris

Date: Tue, 18 Sep 2012 17:22:44 -0500
From: Bob Smither smit...@c-c-i.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Reducing lab noise with LED lighting.

Has anyone tried the fluorescent replacement LED tubes? Apparently you
remove the ballast from the fixture and power the tube from the 120V AC
line.

Any chance these would reduce the noise in a lab from conventional
fluorescent tubes?

Thanks.


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[time-nuts] Fun with the Z3815

[Morris Odell]

HI all,

I posted a question recently here for a friend re a Z3815 not receiving,
having formerly been perfect.  Here's what he says now:

 I've done more testing with my HP3815A. Firstly I rewired the coax cable
between the external antenna connector and the PCB - there was some evidence
of snagging on the outside of the cable where it passes through the metal
casing. However, no improvement in performance resulted. Also the blocking
capacitor referred to turns out to be an inductor. DC is making it through
to the antenna amp, and there is continuity along the whole route from
N-connector to the Furuno GPS receiver input.

The status screen on Hyperterminal shows that something is happening,
however. The SYNCHRONIZATION section on the display showed outputs invalid,
TFOM = 9 and FFOM = 3 (i.e. no sync). But the ACQUISITION section showed
that although no satellites had been tracked, several had been detected - in
fact 9 of them.  Also, the correct date and time were displayed. The LAT and
LONG data was incorrect, being the original northern hemisphere figures.
Health monitor reads OK and there are no ALARMS. So the receiver appears to
be picking up enough information to show the satellites' PRN, EL and AZ (and
furthermore they change between readings) as well as the date and time.
What's more the time displayed is local time!

Any suggestions as to what's going on?

Morris


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[time-nuts] HP Z3815A manual/info needed

[Morris Odell]

Hi all,

A few of us down here in Oz have HP Z3815A GPS disciplined frequency
standards running. One of my friends, who does not belong to this group, has
had a fault develop in his unit which seems to be in the GPS receiver
section. The serial port terminal program  indicates that all is well but no
sats are being received even with an antenna change.

Are there any manuals or service information available for these units? Even
a block diagram? Any help gratefully accepted!

Regards to all,

Morris VK3DOC


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Re: [time-nuts] Best location for a GPS antenna...?

[Morris Odell]

I make GPS controlled clocks of various sorts and had been including cheap
Oncore receivers in them. In view of the inconvenience of needing a GPS
antenna feed for them I have decided to do something like this for local
distribution of the GPS sentence using little wireless modules such as the
Xbee or similar. I only need the RS-232 and pps and any small timing errors
introduced by the link won't be an issue for clock purposes. If you only use
the 1 pps for timing then the wireless modules could be a satisfactory
solution as errors will average out over the long period that is used for
disciplined oscillator controllers using the 1 pps.

Morris


   Buy a cheap Motorola Oncore receiver.   The
Oncore UT costs all of about $18 on eBay, buy four of them.The
only signal you need to bring into the workroom from an Oncore is PPS
and that is way easy to do using fiber.   The other signals (rs232)
can be connected as needed and that is not often.  Then you build a
standard GSPDO in the workshop.The initial cost is lower and the
engineering is simple (because only the PPS has to go over fiber)

The Oncore and GPSDO can give as good of result as the t-bolt.  It mostly
depends on how good the OCXO is, maybe even you build two GPSDOs running off
the same PPS the second one being  Rubinium based.
My $35 Rb can holdover for many weeks (at the level I need) if GPS is down.

Then you can install the t-bolt with an antenna you can disconnect and only
use the t-bolt now and then during good wearer to double check the GPSDO
that you can leave running 24x7


Chris Albertson
Redondo Beach, California




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Re: [time-nuts] Improving performance of a GPS antenna...?

[Morris Odell]

Thanks for the replies.

Yes it's definitely 5V from the receiver.

That advice re the pipe mount sounds good - that will be the next step!

Morris



--

Are you sure that the Oncore VP sends the right voltage to the antenna?  
This type needs 5 V and most pucks are designed for 3.3 V .  According 
to the manual the VP sends 5 V to the antenna but anyway it is easy to 
measure.

Regards,
Ignacio, EB4APL



The timing antenna inside the pointed radome is a helix, not a
patch antenna.
Are helix antenna designed to be used with baseplates like the pie
tin?  (I'm not sure.) The obvious experiment is to remove the plate
and mount it as it was designed to be mounted on a pole.  It is very
easy to make a proper mount for this kind of antenna, just buy 3/4
pipe flang from any hardware store and a short section of 3/4 inch
pipe.  I was lucky to find the pipe flange had holes in the correct
location but one could also mount it to the flange using velcro or
double side foam tape.



Chris Albertson
Redondo Beach, California



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Re: [time-nuts] Improving performance of a GPS antenna...?

[Morris Odell]

Hi all,

While we're on this subject, I have a related question. 

I recently bought one of those cone shaped Lucent GPS timing antennas from a
vendor in China. I'm using it for one of my GPS controlled clocks which
contains a 6 channel Oncore VP receiver and is on the end of about 15 feet
of RG58. I mounted the antenna on a small Al plate about 10 X 20 cm attached
to a balcony rail 3 stories from the ground with a clear view of about 75%
of the sky.

I would have expected that the receiver would see quite a few satellites, a
similar arrangement with a magnetic puck antenna regularly sees up to 6
birds. The Lucent however regularly only sees one. Could this be due to the
way it's mounted?  Could the baseplate have something to do with it?

Any advice would be welcome.

Morris 


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Re: [time-nuts] looking for data on time code display

[Morris Odell]

 I had hoped the frequencies listed on the controls might trigger some
association in someone who's knowledgable about time-codes. 250 Hz 

 doesn't seem to be a legal IRIG time-code frequency, although 1 kHz is.

I'd try feeding it with various frequencies as others have suggested and see
what happens. It's unlikely to have been used with other time codes such as
SMPTE.

I have an earlier unit made by Datachron, now defunct, which looks
superficially similar but uses DTL logic. Mine is definitely an IRIG decoder
and the funny filter frequencies may have been meant for manually shuttling
tapes at non standard speeds. After a lot of messing around (a story in
itself)  I have resurrected mine and use it as a nixie clock, fed with IRIG
B generated by a modern micro from the output of a GPS receiver. There's
more logic in the $9 AVR chip than the whole IRIG decoder which would have
cost thousands when it was new!

And while I'm on the subject, anyone got any DTL JK flip flops to spare to
keep the old box going? I've had to replace quite a few chips which probably
died when the device was fed with higher than specified mains voltage in its
early life.  The +5V supply was unregulated :-(

Morris VK3DOC
Melbourne, Australia



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Re: [time-nuts] Serial to Excel utility.

[Morris Odell]

I have done this using hyperterm on an older PC. It produced a comma
delimited file that wasn't too hard to parse into columns and then import
into excel. You need to make sure there is a CR/LF after each sentence. I
haven't explored terminal programs on a more modern PC but I'm sure they are
do-able.

Regards,

Morris (VK3DOC)


Date: Mon, 7 Nov 2011 05:48:09 +1100
From: Nic McLean mclea...@bigpond.com
To: time-nuts@febo.com
Subject: [time-nuts] Serial to Excel utility.

Sorry folks for the slightly OT post.

Does anybody know of a utility that will import and parse the serial bit
stream from a GPS and put values into a couple of cells in an Excel
spreadsheet?

Regards,

Nic

VK2KXN / VK5ZAT



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Re: [time-nuts] Am I the only Time Nut who doesn't wear a watch?

[Morris Odell]

 Bravo, Rob.  I thought I was the lone voice crying in the wilderness in
support of watches.

My beater is an Omega Seamaster that goes everywhere and does everything
all the time.  My others tend to sit in their rocker boxes and seldom get
worn.

This was a very interesting thread. I have worn a watch for the last 50+
years and feel that something is missing without one. Even though my
professional activities (to say nothing of hobby pursuits) mean I have to
take it off from time to time I won't be without one. Looking at the time of
a mobile phone or computer just isn't the same and you can't trust wall
clocks you have no control over. There's nothing like the gesture of pushing
up a sleeve to see it or the ability to glance at it surreptitiously during
boring meetings :-)  My current quotidian timepiece is a Longines quartz
with an analog dial and a date window. It keeps very accurate time and the
crystal is remarkably scratch resistant. I have a Forbes nixie watch too for
appropriately nerdy occasions and an assortment of cheapies for travel.

I was in the amazing clock museum in the Beijing Forbidden City recently.
Has anyone else seen that? It houses an incredible collection of 18th and
19th century extreme high end clocks, from the collections of successive
emperors. They are of course all mechanical ( or water powered) and some are
of amazing complexity. One had a little automaton of a man sitting at a desk
writing down the time! I also saw my first Congreve clock while I was over
there. I am tempted to try and make a version of one if I ever get a year or
three to spare...

Cheers,

Morris










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[time-nuts] Godwin corollary (was Remotely read power meters)

[Morris Odell]

 Subject: Re: [time-nuts] Remotely read power meters
 
 
 This is OT for time-nuts.  Should we start another list for things like
 this?
  nuts-overflow?  nuts-OT?


I would like to propose a corollary to Godwin's Law* for technical
discussion groups. I have observed that every electronics technical group I
have ever belonged to (and are lots) eventually ends up discussing power
distribution! This one is perhaps atypical in that the topic of RCDs has not
come up yet but I'm sure if we wait long enough it will. It used to bug me
but now with very cheap bandwidth I just sit back and wait for the
discussion to get back to boatanchors, radio, oscilloscopes, test gear,
audio, microprocessors, time nuttery or whatever. It does degrade the S/N
ratio a bit though - I wonder if there's a noise-nuts out there to discuss
it on

:-)

Morris

* http://en.wikipedia.org/wiki/Godwin's_law


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Re: [time-nuts] 60 Hz measurement party

[Morris Odell]

 
  That sounds like a recipe for excitement - DC current into seawater
 should generate hydrogen on one and and oxygen on the other electrode.
 At 3000 amps, rather a lot of it.
 
 
 I imagine they keep the current density low enough that the gas is
 absorbed into the water as it's evolved.  But yes.. a fascinating
 concept.
**

Actually if you electrolyse salt water with DC you get Hydrogen  Chlorine
at the electrodes and sodium hydroxide dissolved in the water. That's how
salt water pool chlorinators work and why the pool get progressively
alkaline and needs to have hydrochloric acid added regularly to make up for
what's released by electrolytic action. Hopefully if it gets released in the
ocean the Cl2 gets reabsorbed quickly and the caustic soda gets diluted or
buffered. The H2 would end up in the atmosphere as it's not very water
soluble. 

I love this thread on the old style large synchronous motors. My first
engineering job was in a paper mill where they had quite a few of them on
various machines including the Ward Leonard sets that controlled the paper
machines. We were continually tweaking the excitation to try and get the
overall power factor down...

Morris



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Re: [time-nuts] 60 Hz measurement party

[Morris Odell]

 mean a second wire ?  Surely you do not mean they are using the earth
 (dirt) as a
 return path ?  That would be terribly inefficient !  

Down here in Australia, Single Wire Earth Return (SWER) is common for long
rural lines. They run at 12.7 kv (one phase of a 22 kv 3 phase line). At the
consumer end there is a pole mounted transformer and a fenced off earth
stake. It seems to work reasonably well even in dry conditions but you
occasionally hear stories of a large quadruped coming to nasty end if they
get inside the enclosure. Obviously there would be a radial potential field
in the ground and on the surface and quite a voltage can develop across
their legs.

Morris



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Re: [time-nuts] Z3815A and Z38xx software

[Morris Odell]

I've run my Z3815A with various programs including Z38xx. They all work
well. I like the Z38xx the best because of its extensive reporting including
ADEV etc. The software from Murray Greenman is pretty good too. Are you sure
the unit itself is OK?

AFAIK there's no official manual available. The reverse engineered manual
from Murray was all I needed to get it going. It's been on pretty well
continuously for 3-4 years now and hasn't missed a beat

Morris

 Date: Sat, 22 Jan 2011 21:39:57 -0500
 From: Bob Camp li...@rtty.us
 Subject: [time-nuts] Z3815A and Z38xx software

 Hi
 
 Is anybody else trying to run a Z3815A with the Z38xx software?
 
 I have one of the earlier units with a 1938 mounted in a very official
 looking HP box. Some of the status information looks backwards. The
 antenna shows ok when it's not and ERROR when it is ok. There's always
 the possibility of operator error, thus my question...
 
 I still haven't found a manual for this model on the net, so I'm flying
 a bit blind.
 
 Thanks!
 
 Bob
 
 
 --


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Re: [time-nuts] A different timenuts interest

[Morris Odell]

Hi all,

I would like to thank everyone who responded to my post. This is a wonderful
group of talented and erudite people and it was a pleasure to read the posts
(and private emails) on the subject of the Foucault pendulum. Where else
could the discussion range over timekeeping, mechanical suspension
arrangements, Tesla coils, Napoleon, sustaining systems, blades on the
pendulum bob, a host of references and all the other great stuff that turned
up.

This project is for a FP that will be part of an art installation. It's
unlikely to be permanent though unless a major gallery or collector likes
the work enough to buy it. Unfortunately this rules out commercial systems
costing tens of thousands of dollars.

From my readings and suggestions from members of this group I have come to
understand the following:

The main issues in designing a FP are the sustaining  system, avoidance or
damping of elliptical motion and safety considerations in case the wire
breaks. Of course keeping fingers and draughts away is also a consideration.


Sustaining systems are mostly electromagnetic, either with a ring shaped
electromagnet at the top near the suspension point controlled by optical
sensors, or one or more coils below the centre point with a magnet on the
bob. This acts as both a sensor and motor. There is also a reluctance type
driver described using mains frequency solenoids. The most elegant system is
the parametric one where the suspension point is oscillated up and down
sinusoidally at twice the pendulum frequency and there are no horizontal
forces acting on the bob at all. I found a very complex mathematical
analysis if that. It would be an interesting challenge using optical sensors
and a stepper perhaps to move a cam or crank to realise that.

Avoidance of elliptical motion and increasing the Q of the oscillator is one
of the reasons why most FPs are so long with heavy bobs. Despite this I
found some articles on short FPs, including one hanging from the wall and
used as a clock with a pendulum less than a metre long. Elliptical movement
is often controlled by a Charron ring which interacts with the wire to
limit ellipsoidal movement. There are also magnetic eddy current damping
systems described and one elegant method which uses a precisely timed pulsed
sustaining system to cancel elliptical motion.

As was pointed out, FPs are not primarily time keeping devices but there is
a relationship between the period of their precession and the rotation of
the planet, which is also dependent on Latitude. Perhaps unsurprisingly,
someone has described a FP clock which required an electronic system to stop
it for a few hours in the middle of the night to sync its movement to the 24
hour cycle. One can easily see GPS control creeping in there :-)

I hope the discussion continues, It's been great so far. I'll keep the group
posted on progress.

Cheers,

Morris




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Re: [time-nuts] IRIG B

[Morris Odell]

I have done this with an AVR microcontroller and it turned out to be very
easy. Just program one output to generate a 1 KHz carrier and another to
modulate the amplitude using a resistive divider. A simple LPF will knock
the edges off the carrier and not affect the timing accuracy too much.

Receive is easy too if you have a micro with a comparator which can tell the
difference between the two amplitude levels. I would extract the carrier
first and feed it to another input of the micro to provide a phase reference
and then do the decoding all in firmware.

Morris

 
 
 i would think, given that the audio carrier is 1kHz-ish, that almost
 any
 of the small microcontrollers would work, using a single bit in/out
 with
 some RC signal conditioning.  Maybe a bit of a challenge for the
 receive.. you'd need two inputs with different resistors.
 


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Re: [time-nuts] Conducting Bench Top Material

[Morris Odell]

Just about every doctor's surgery or emergency room more than about 15 years
old will have had more than one thermometer broken in it. I'm sure there are
lots of little balls of mercury lurking in carpet fibres or between tiles in
those environments. It doesn't seem to have surfaced as an occupation health
hazard. You're more likely to encounter lead or sharp steel poisoning in
inner city ERs :-(

Morris


 Date: Sat, 30 Jan 2010 17:22:30 -0500
 From: Chuck Harris cfhar...@erols.com
 Subject: Re: [time-nuts] Conducting Bench Top Material
 
 Yes, and no.  When mercury hits the ground, it splatters into hundreds
 of
 miniballs of mercury.  When you walk on them, they further fracture,
 and
 by the time you are done, you have increased the surface area of the
 mini
 drop of mercury greatly... probably thousands of times.  That increases
 the mercury vapor emitted into the room.
 
 Is it harmful?  Maybe.  Maybe not.
 
***


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Re: [time-nuts] time-nuts] Digital Clock kit - no Integrated circuits!

[Morris Odell]

From: Steve Rooke sar10...@gmail.com
Subject: Re: [time-nuts] Digital Clock kit - no Integrated circuits!
To: Discussion of precise time and frequency measurement
time-nuts@febo.com

2010/1/9 Tom Clifton kc0...@yahoo.com:
 http://transistorclock.com/? has a very interesting (though a bit
expensive) kit for sale.??A 10 x 11 circuit board sporting nearly 200
transistors and 600 diodes to drive six seven-segment displays.? Suitable
for framing...? As delivered runs on 60hz but there is a note about
conversion to 50hz mains.? You can buy a? bare board, just the components or
a full kit.

 You must see it to believe it!

 Bah humbug! Stupid modern day design, it'll never be any good, you
 need to use valves to make real gear :-)

Not only do I have a 5245M but no less than TWO HP 524 counters. One's a B
with 88 valves, 6 neon columns and 2 meters for the last 2 digits, the other
is a D with a similar number of valves and, yes, 8 Nixies. They are driven
5245 style with neons  photoconductors.

When the 2 coutersaurii are going and their output waveforms are being
compared on the Tek 555 scoposaurus there are about 300 valves glowing away
and about 2.5 kW being dissipated. Definitely not to be done during the
Australian summer - 39C here today.

Morris



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Re: [time-nuts] ABC time signals in Tasmania/Australia wrong

[Morris Odell]

They appear to be spot-on here in Melbourne.

Morris


Date: Sun, 3 Jan 2010 12:14:05 +1100
From: Jim Palfreyman jim77...@gmail.com
Subject: [time-nuts] ABC time signals in Tasmania/Australia wrong

For the Down Under nuts,

The ABC radio time signals in Hobart are one second out. Is it a national
thing? Can others in the country check?

I rang the ABC locally on xmas eve but it is still not fixed.

Jim Palfreyman





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[time-nuts] 5061A questions

[Morris Odell]

Hi all,

I recently picked up another 5061A (my second now, I'm becoming a real
Time-Nut :-). The tube seems to be OK, it started up nicely and has been
working well for nearly a week. The Patek Phillipe clock ticks beautifully
in sync with the first one which has a good tube too but runs most of the
time from a Shera GPS controller built into the empty battery compartment.
The time difference between the two has settled down to only a few nS up 
down over the day. Unfortunately the counter I'm using, a 5345A, lacks the
GPIB option so I can't record it.

This one has two mods I'm not familiar with - No 03 and No H92. There's a
red LED labelled System Alarm on the front panel between the Continuous
operation lamp and the 5 MHz output jack. There's also a DB25 female
connector on the back marked J30 Alarm. It lacks the little door on the
top cover to allow adjustment of the clock and time offset - very
frustrating.

There was a battery in it, disconnected and well past it's use-by date. The
20 NiCad cells have gone to the recycler.

My questions are:

What are those options?
Can the battery charger be used with cells other than Nicads? 

Nicad cells are getting hard to find but there are plenty of NiMh cells
around and also lead acid batteries. Is it worth setting up a battery? I
have taken out the charger card temporarily. My first 5061A came without the
card so I have no experience of this.

Cheers to all,

Morris




 


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Re: [time-nuts] Any Time nuts in AU?

[Morris Odell]

Hi all,

Another one here in Melbourne :-)

Morris VK3DOC


From: Nic McLean mcle...@bigpond.com
Subject: Re: [time-nuts] Any Time nuts in AU?

Yes Ray there are quite a few of us!
Nic
VK2KXN / VK5ZAT
Sydney / Adelaide Hills; Australia.


Just a test to see if I can send to the mailing list and to find out how
many time nuts are in the land down under

Thanks Ray.






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Re: [time-nuts] Obscure terms

[Morris Odell]

 
There is a unit of force in the old fps system called the slug. Then you get
derivations such as work units of slug feet or loadings of slugs per square
foot etc. 


Morris



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Re: [time-nuts] Obscure terms

[Morris Odell]

Oh, and of course power in that system is slug-furlongs per fortnight. :-)

As for RCH, I work there from time to time and often grin privately at the
other meaning.

Morris

-Original Message-
From: Morris Odell [mailto:vilgo...@bigpond.net.au] 
Sent: Friday, 21 August 2009 7:19 AM
To: 'time-nuts@febo.com'
Subject: RE: [time-nuts] Obscure terms

 
There is a unit of force in the old fps system called the slug. Then you get
derivations such as work units of slug feet or loadings of slugs per square
foot etc. 


Morris



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Re: [time-nuts] time-nuts Digest, Vol 59, Issue 85

[Morris Odell]

I bought a manual from them a couple of years ago but on checking their 
website www.datachroninc.com it appears that the domain name is for sale. 
They lasted a long time but it looks like they've gone...


Regarding IRIG, there are several different flavours - IRIG A, B, C etc all 
with different data rates and frame specs. My ancient DTL driven Datachron 
has a selector switch on the front panel - maybe yours has one too, hidden 
somewhere



Morris



From: Robert Darlington rdarling...@gmail.com
Subject: [time-nuts] Datachron, Inc.
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Message-ID:
b3bd5fcb0906251807j7a8b1519ic9896c10526b2...@mail.gmail.com
Content-Type: text/plain; charset=ISO-8859-1

Hi guys,

What happened to Datachron? 



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[time-nuts] Trimble fails to leap

[Morris Odell]

Hi Nuts,

I wasn't sure which of the several GPS receivers here to monitor (the 
classic time nut conundrum) and of course, picked the wrong one. I have a 
Trimble Lassen IQ in a disciplined 5061A running in non-Cs mode. Using their 
IQ monitor program it showed no trace of the leap second - just went from 
23:59:59 to 00:00:00. I had a camera set up and everything :-(

When's the next one?

Morris




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Re: [time-nuts] Oncore question

[Morris Odell]

Thanks to all those who replie don this subject. I'm using an old VP Oncore 
purely for timing.

The situation where the RTC stops at low voltage but the memory lingers on 
resulting in the wrong time for the Almanac is a fascinating one of which I 
was not aware. I may do some experiments to see at what voltage the RTC 
stops. In the meantime the discussion prompted a baord redesign to find some 
real estate for a Li cell :-)

Thanks again,

Morris 


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[time-nuts] Oncore question

[Morris Odell]

Hi Fellow Nuts,

I've been following the thread on parsing the Motorola receiver code with
 great interest. I have written AVR code to do this but have not gone to
 great trouble making it bullet proof as it was a non critical application 
in
 a Nixie clock. I programmed the receiver to send only one message, and then
 looked for the @@Ba string before I started counting bytes. I used the
 number of SVs byte to decide whether the data was good. Worked fine for me!

 I'm about to start another project with an Oncore so maybe I'll experiment
 with a more complex program this time.

 My question relates to the older Oncore VP receivers. I have one which had 
a
 dead memory battery. The receiver has an on-board battery charger for a
 rechargable Li cell but they are very hard to find down here. In the past
 I've used a conventional Li cell with a schottky diode to prevent the
 charger from forcing current down it's throat. I was wondering if there's
 any reason not to use a super cap. I only need it to support the memory for
 very short periods during power burps. Will the on-board charger be OK for 
a 1F
 super cap?

Any help or opinons much appreciated

Thanks,

Morris 


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Re: [time-nuts] Lassen IQ receiver

[Morris Odell]

Hi Mike,

The Lassen IQ is a little PCB mounted 12 channel receiver about half the 
size of a matchbox, which is intended for OEM applications. It's not easy to 
open to see what's inside. It uses tiny surface mount connectors to get 
signals in and out but there's no access to the oscillator if you want to 
use an external osc.  It doesn't have a built in antenna so the performance 
depends on the external antenna connected to it. It seems to handle 
constellation changes quite well as far as I can see. The application info 
says it can be used for navigation as well as timekeeping.

It has 2 serial ports as well as a 1 pps output. One serial port is used to 
control and read it using Trimble's TSIP binary protocol. There is free DOS 
and Windows software available from Trimble to do this. The other port can 
be configured to use TSIP, NMEA or Trimble's own ASCII protocol called TAIP.

I paid AU$70 about 2 years ago, which at the time was equivalent to about 
US$60. You could probably do better these days. I bought a bunch of old 6 
channel VP Oncore receivers about a year ago on ebay for AU12 each. They are 
ideal for timing aplications and clocks.

HTH,

Morris


  These units look interesting. Do you mind if I ask some questions?

  1. What kind of non-time keeping uses have you found for them?

  2. How  well do they work indoors? Do you have to be near  a window?
  What about inside a multi-story building?

  3. How well do they handle constellation changes? Is there an abrupt
  shift in position?

  4. Have you ever taken the shield off and looked inside? If  so, can
  you see the crystal oscillator and tell whether it is a bare crystal
  or a complete oscillator module?

  5. How  much  do  they  cost? Do you know  of  any  others  that are
  cheaper?

  Thanks for your help!

  Best Regards,

  Mike Monett

 

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Re: [time-nuts] Lassen IQ receiver

[Morris Odell]

Thanks again Bob,

Yes, that's what I thought it would do, but It doesn't seem to be so. My 
micro is programmed to identify the beginning of an NMEA string by the $ 
character and there's only one per sec. Maybe the second string is 
concatenated onto the first one without the dollar symbol.

Having said all that, in the time between my original post and this one I 
managed to get the TAIP output working and the micro to recognise it so I'm 
a happy man :-)

Morris

 Date: Sat, 11 Oct 2008 00:29:07 -0600
 From: Robert Darlington [EMAIL PROTECTED]
 Subject: Re: [time-nuts] Lassen IQ receiver

 As far as alternating, you'll get the various NMEA strings in the order 
 you
 choose (and the strings you choose) once a second.  You won't get one, 
 then
 the other, then back to the first.  It'll be several  all at once, and 
 that
 block will repeat once a second.  I suppose you could select just the two
 you want, but they'd come in on the same data burst, repeating once a
 second.

 first string
 second string
 1 second pause
 first string
 second string
 1 second pause
 etc.

 I don't know for sure if you can have port 1 setup with a particular set 
 of
 NMEA data strings and port 2 setup with a different set.  Assuming you 
 can't
 do that (meaning they have to be the same NMEA data), you can probably 
 have
 both ports spit out everything you'd need and ignore what you don't need 
 in
 software.

 -Bob


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[time-nuts] Lassen IQ receiver

[Morris Odell]

Hi all,

I'm using a Trimble Lassen IQ receiver for a Shera style GPSDO. That part 
works OK but I would also like to get serial data from the receiver's output 
port #2.

The receiver seems to respond to commands sent to port #1 but the desired 
outputs don't seem to appear.

Specifically I want to get two NMEA messages, GGA and ZDA, or alternatively 
the TAIP TM timing message. No matter how I instruct the receiver I don't 
see two NMEA messages, just the first one on the list I've sent to the 
receiver. The TAIP doen't seem to work at all.

Am I missing something here? Has anyone had any success with this device?

Thanks,

Morris


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Re: [time-nuts] I now have a clock accurate to 10E-6!!!

[Morris Odell]

You are a lucky man with foresight! One of the many bruises I have 
accumulated over years of kicking myself relates to passing up on an offer 
to obtain a couple of those.

I do have a rather mundane grandfather clock which would benefit from the 1 
pps treatment though. Just need to pursuade the domestic engineering 
manager..

Morris


 Date: Mon, 25 Aug 2008 17:40:14 +1000
 From: Jim Palfreyman [EMAIL PROTECTED]
 Subject: [time-nuts] I now have a clock accurate to 10E-6!!!
 To: Discussion of precise time and frequency measurement
 time-nuts@febo.com
 Message-ID:
 [EMAIL PROTECTED]
 Content-Type: text/plain; charset=iso-8859-1

 Hi Folks,

 Well I've had the best weekend since I've just acquired a pendulum clock
 that used to be a telecommunication time standard in the 50s. It is a 
 German
 made Siemens pendulum master clock that is about 150cm high and has a
 full-length seconds pendulum which is about a metre long. It is powered by
 48V to automatically wind the weight up and will maintain time for about 8
 hours without power.


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[time-nuts] another 5061A question

[Morris Odell]

Hi all,

As I wrote the other day, I got the 5061A going again and it hasn't missed a 
beat.

One thing I have noticed though, is that the Osc Oven indication on the 
meter doesn't change at all as  the unit warms up as the manual mentions it 
should. It remains on 45. The unit itself is a 105-6013 and gets warm and 
seems to function OK. Is this normal? I know these ovens have a 115V 
preheater which might be working even if the proportional heater is not.

The schematic shows that in the Osc Oven position the meter is connected 
across the heater in series with a thermal link. Does the absence of any 
variation mean that the heater or link is open or is the preheater keeping 
it close enough to temp so that the heater doesn't work too hard? How hard 
is it to open it up?

Unfortunately it's back on the rack and another project is on the bench. It 
might have to stay that way for a week or three, so there's no hurry to get 
back into it.

Cheers to all,

Morris




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Re: [time-nuts] 5061A ion pump P/S problem

[Morris Odell]

Corby,

Thanks very much for this advice. It turned out the spare unit was quite OK 
after all. It's installed as I type, and the 5061A is locked beautifully and 
showing the same freq as the Z3815A GPSDO on a HP 5345 counter. A check of 
the flop parameters shows the Cs tube is nice  healthy and all's right 
with the world!!!

The unit had been running with the mode switch in the Cs off position for 
a couple of years so the tube was well and truly pumped down. The ion 
current was very close to zero. I have a Shera controller circuit built into 
the unused battery compartment so most of the time it runs as a GPSDO but I 
like to exercise the Cesium from time to time too.

Thanks again Corby and everyone else who suggested ways to get it going 
again.

Morris

PS: my 5345 counter does not have the GPIB option so I can't do things like 
Allen plots. If anyone happens to have a junker with a GPIB card available 
I'd love to hear about it.



 From: corby d dawson [EMAIL PROTECTED]
 Subject: Re: [time-nuts] 5061A ion pump P/S problem
 To: time-nuts@febo.com
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain; charset=us-ascii

 Morris,

 You implied that you tested the spare module on the bench.

 You must connect the -side of the supply to the case of the module as
 well as the pin. (this occurs in the unit by its connection to the
 chassis)

 If you don't the supply floats and you will only read about 1/2 the
 voltage out.


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[time-nuts] HP 5061A problem

[Morris Odell]

Hi all,

My 5061A has failed and I've isolated the problem to a faulty A18, the +3500 
volt ion pump power supply.

The existing one has almost certainly has had the internal 200M resistor go 
open as the output voltage is about 5 kV and it does not decay quickly when 
the power is off.  The output voltage to the current sensing circuit is 0.

I have a replacement which I suspect is faulty - when energised from a +18 
volt source it only produces 2 kV which decays quickly and the sensor output 
is +20 when the thing is unloaded. That 200M resistor may have gone low! Is 
this one worth installing ie: will +2 kV pump enough ions?

So I'm looking for a replacement or advice from anyone who may have 
attempted to repair one.

If anyone has a parts donor of course I'd be happy to pay appropriately 
including shipping down here to Australia.

Morris 


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Re: [time-nuts] Antikythera

[Morris Odell]

- Original Message -  Date: Sat, 2 Aug 2008 18:59:09 -0400
 From: Mike Feher [EMAIL PROTECTED]
 Subject: [time-nuts] Antikythera
 To: 'Discussion of precise time and frequency measurement'
 time-nuts@febo.com
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain; charset=US-ASCII
 
 FYI - Mike
 
 http://www.nature.com/nature/videoarchive/antikythera/
 
See:

http://www.tatjavanvark.nl/antikythera/index.html

and take a look at the rest of her website as well!

Morris

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Re: [time-nuts] Oncore batteries

[Morris Odell]

 From: Matthew Smith [EMAIL PROTECTED]
 Subject: Re: [time-nuts] Oncore batteries
 Don't pull off the batteries! The boards are populated differently for
 battery/non-battery uses. Your external battery will not be connected to 
 the
 onboard RAM.

 Too late - at least for the 'stuck' unit, although I haven't powered it
 with anything connected to the battery pin.

snip

 What I'd be interested to know is whether the Oncores CAN be run without
 the backup battery.  As Randy says, TTFF is not a concern for me so I'd
 rather have a less complex system that can be restored to a known state
 simply by removing power.

I went through this quandary with the VP a few months ago and got lots of 
help from members of this list, thanks guys!!

Briefly the VP has an onboard rechargeable Lithium cell and there is a 
charging circuit to keep it topped up. The connection to pin 1 which is 
documented as the backup battery is actually open circuited. The batteries 
on the VPs I have used were either missing or dead. For timing applications 
where you don't care about TTFF you can get away with just running them as 
they are. Be aware that an old VP that has been on the shelf for a while 
might take a long tome to get going but that's another issue.

If you really want to have battery backup, either try to find a rechargeable 
solder-in Li cell or connect a schottky diode between the cell positive 
terminal and pin 1 of the connector so you can use an outboard conventional 
Li cell. The diode prevents the charging cct from trying to charge the 
non-rechargeable cell.

I found that the VP always starts up in binary mode which is fine for me as 
I designed the host system to communicate with it that way. I always thought 
you had to issue the @@Ci message with appropriate arguments  checksum to 
get it to communicate in NMEA 4800 baud but I've never tried it. I don't 
know whether that's a volatile setting or not.

Morris




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Re: [time-nuts] How best to compute local time from GPS

[Morris Odell]

David Forbes asked:

 2. If I have to store the time zone from the user's input, are the
 DST calculations reasonably straightforward these days?

It's not too difficult and you get a nice refresher in modulo-7 arithmetic. 
I did it in AVR assembler recently although I didn't try to make it 
universal. Our government down here in south-eastern Australia recently 
changed the DST changeover dates so I customised it for where I live. If you 
need to make it user settable that would mean you need to be able to enter 
the dates and UTC offsets as a menu item which would complicate things 
considerably. It'd be a fun programming challenge though :-)

 4. In general, is it better to let the user turn DST on and off or
 try to do it automatically? (I live in Arizona, which doesn't worship
 DST, so I have no experience in this matter.)

I put a 3 position (centre off) switch on the back panel of my clock. The 3 
positions are: Summer time, Auto, Winter time. That way after I'm demented 
or dead and gone if the gov't changes the rules again it can be changed 
manually.

I programmed the receiver for our local time offset from UTC. I then add or 
don't add an hour as the case may be.

Morris 


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Re: [time-nuts] GPS Antenna Cable Splicing

[Morris Odell]

 Date: Sat, 01 Mar 2008 19:52:03 +1030
 From: Matthew Smith [EMAIL PROTECTED]
 Subject: [time-nuts] GPS Antenna Cable Splicing
 To: Time Nuts List time-nuts@febo.com
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain; charset=UTF-8

 1) Can I actually extend the cables, or is 5m as far as I can go - all
 these are active antennae.

 2) My normal way of extending a bit of coax would be to splice in an
 appropriate length of similar cable.  To do this, I would strip the
 outer insulation for a couple of inches on both pieces, pulling back the
 braid.  I would then strip enough of the central insulation so that I
 can solder the two cores together.  I insulate this with tape or
 heatshrink, then solder the two braids together, wrap the whole thing
 with aluminium foil and use a glued heatshrink to case the whole lot.

Although the discussion here often revolves around the edge of the 
envelope, there are some things that might not need that level of detail. I 
have a similar problem, with a workshop in the basement and a GPS antenna on 
a balcony 3 stories up. I had a 15 metre length of RG213 running between 
those two places for a HF antenna which is no longer used. It already had 
UHF (PL-259) connectors on the end. I just made up a little adaptor for the 
GPS antenna lead using a cheap plastic box, a SO-239 socket and plenty of 
silicone sealant.

It works perfectly although I know a TDR would have apoplexy looking into 
it. I use it for non-critical stuff and testing, my Z3815A had a dedicated 
antenna with a proper lead.

Morris



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[time-nuts] VP oncore problem

[Morris Odell]

Hi all,

I wonder if anyone can help me with a problem I'm having with a VP Oncore 
receiver

I am building something which includes one of these receivers and it 
communicates with the host microcontroller via the VP's serial binary link. 
The host receives messages from the VP just fine. The problem arises when 
the host tries to send configuration commands to the VP. When this happens 
the VP only responds to the first of 4  messages (Total: about 40 bytes). It 
doesn't matter what order they are sent in a continuous string or whether or 
not there are time delays up to 5 seconds or dummy characters between them, 
the VP only acknowledges the first one and is deaf to any more. Once the 
system is restarted it will receive one more message before going deaf 
again.

The VP manual says the serial receive buffer will store up to 2048 
characters and act on them sequentially. This is obviously not happening. Am 
I missing something here?

TIA

Morris



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Re: [time-nuts] SVN23/PRN32 useable

[Morris Odell]

 Date: Wed, 27 Feb 2008 12:49:40 +0100 (CET)
 From: Magnus Danielson [EMAIL PROTECTED]
 Subject: Re: [time-nuts] SVN23/PRN32 useable

 The interesting thing would be for really old systems if they are able to 
 track
 it or not. Like old 6-channel receivers and such.

The old Oncore VP in my nixie clock was tracking PRN32 as part of its timing 
solution this morning down here in Melbourne Australia.

Morris




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Re: [time-nuts] favorite microcontroller module?

[Morris Odell]

Hi all,

This is a very interesting discussion. In the light of the wide range of 
expertise here, has anyone interfaced a VP Oncore receiver with micro, 
specifically an AVR? I'm in the process of doing that and am having some 
difficulties. I'd appreciate some advice from anyone who has done it 
successfully.

Thanks,

Morris 


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Re: [time-nuts] VP oncore question

[Morris Odell]

Randy Warner wrote:

 Morris,

 The easiest thing is to connect a jumper from Pin 1 of the 10-pin header 
 to
 one of the holes used to previously mount the battery. I would suggest
 putting a resistor (1-4.7K is fine) and diode in the middle of this wire 
 to
 limit current in case of any mistakes and prevent any possibility of the
 onboard charger from damaging your external battery. A couple of standard
 alkaline AAA cells will keep the VP backed up for MANY years.

Randy,

Thanks very much for this info. It confirms what I thought but it's nice to 
hear it from an expert!

Happy New Year,

Morris


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[time-nuts] Z3815A connectors

[Morris Odell]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Hi all,

Thanks to a friend's investigative skills, I have found the maker of the 
unusual coaxial connector block on the HP Z3815A GPSDO. See:

http://www.harting.com/en/en/en/sol/verbtech/prod/minicoax/description/03015/index.en.html

Has anyone here had any dealings with this manufacturer or have any idea 
whether sample or on-off quantities are available?

Morris




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Re: [time-nuts] HP 523B frequency counter Sputnik

[Morris Odell]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Hi all,

I have been lurking here for quite a while but here is something I can ask 
about!

 A little known piece of Sputnik history...

 http://www.hparchive.com/Journals/HPJ-1957-09-Sputnik.pdf

I have a couple of restored and working HP 524B/C counters, each 8 digits 
wide with nearly 100 tubes. They work well and the OCXOs in them are still 
pretty close to my two GPSDO references after 50 years! As it happens I have 
one out on the bench at the moment replacing the unobtainum delay line with 
a digital delay circuit. This article reminded me that I would love to find 
the matching 560A digital recorder - both my counters have the optional 
interface kit for it installed.

Even though I am down here in sunny Australia, our dollar is strong and I 
would love to hear from anyone who knows where one might be found.

Regards to all,

Morris Odell VK3DOC


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