Re: [time-nuts] Dual GPSDO - any advantage?

[ewkehren via time-nuts]

We use Excell nice to make plots and when needed add calculations File is to 
large for time nuts contact me direct and I will send you an exampleBert Kehren


Sent from my Galaxy Tab® A
 Original message From: CORNACCHIA via time-nuts 
<time-nuts@febo.com> Date: 4/10/18  2:35 PM  (GMT-05:00) To: ewkehren via 
time-nuts <time-nuts@febo.com> Subject: Re: [time-nuts] Dual GPSDO - any 
advantage? 
 Bert may I ask how you created the charts (what software are you using).Thank 
You
    On Tuesday, April 10, 2018, 9:04:58 a.m. EDT, ewkehren via time-nuts 
<time-nuts@febo.com> wrote:  
 
 Looking at the pictures it is the same unit I bought. It is not dual oven bit 
trimble works with LH right now shows tracking 10 satelites.Attached  is data 
that made  me buy a second one for Jürg for $ 129  and one more for me for 
$9.50.What you see is highly filtered data to see long time changes to better 
understand if analog filtering os possible. Planning on using Wenzel 600 sec. 
Filter maybe up to 2000 seconds. Board is ready for order.Top plot is my data 
against my Cs 5061B bottom is original Tbolt against his FTS  Cs. We use 53132 
counters.I think  the new one lends it self better for filtering looking at 
both  with my Tracor, Trimble uses a  much shorter time constant and no short 
1E-10 changes you see on our standard units.Will keep you posted         Bert 
Kehren

Sent from my Galaxy Tab® A
 Original message From: Tim Shoppa <tsho...@gmail.com> Date: 
4/10/18  6:46 AM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement <time-nuts@febo.com> Subject: Re: [time-nuts] Dual GPSDO - any 
advantage? 
Most of the Chinese cheapo units have been frequency, not phase locked.

It would be great if you could put the GPSDO outputs into a 2 Channel scope and 
eyeball them for a while to see if they appear in phase (say plus-minus 20ns) 
over a few hours.

Tim N3QE

> On Apr 10, 2018, at 1:43 AM, donald collie <donaldbcol...@gmail.com> wrote:
> 
> I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
> error!] They are stated as being new, and use a Trimball dual oven OCXO. I
> plan to run these in parallel [2 antennas, 2 feedlines, and 2 GPSDO`s] It`s
> been said that a man with two watches is never happy - unless, of course,
> they agree with each other ;-). Being identical the outputs should be
> coherent, unless one becomes faulty [one advantage of having two - any
> discrepancy and you know something must be wrong]], but is there some
> crafty way I can squeeze a little more "accuracy" out of two than if I only
> used one?
> TIA for your commentsDonald
> Brett Collie ZL4GX
> 
> PS : I have no connection to the eBay seller. The US$9-50 seems to include
> a basic puck antenna, long downlead, and 4 interseries adaptors
> ___
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Re: [time-nuts] Dual GPSDO - any advantage?

[ewkehren via time-nuts]

Jürg will have to explain he is in Switzerland  will be tomorrowBert


Sent from my Galaxy Tab® A
 Original message From: CORNACCHIA via time-nuts 
<time-nuts@febo.com> Date: 4/10/18  2:35 PM  (GMT-05:00) To: ewkehren via 
time-nuts <time-nuts@febo.com> Subject: Re: [time-nuts] Dual GPSDO - any 
advantage? 
 Bert may I ask how you created the charts (what software are you using).Thank 
You
    On Tuesday, April 10, 2018, 9:04:58 a.m. EDT, ewkehren via time-nuts 
<time-nuts@febo.com> wrote:  
 
 Looking at the pictures it is the same unit I bought. It is not dual oven bit 
trimble works with LH right now shows tracking 10 satelites.Attached  is data 
that made  me buy a second one for Jürg for $ 129  and one more for me for 
$9.50.What you see is highly filtered data to see long time changes to better 
understand if analog filtering os possible. Planning on using Wenzel 600 sec. 
Filter maybe up to 2000 seconds. Board is ready for order.Top plot is my data 
against my Cs 5061B bottom is original Tbolt against his FTS  Cs. We use 53132 
counters.I think  the new one lends it self better for filtering looking at 
both  with my Tracor, Trimble uses a  much shorter time constant and no short 
1E-10 changes you see on our standard units.Will keep you posted         Bert 
Kehren

Sent from my Galaxy Tab® A
 Original message From: Tim Shoppa <tsho...@gmail.com> Date: 
4/10/18  6:46 AM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement <time-nuts@febo.com> Subject: Re: [time-nuts] Dual GPSDO - any 
advantage? 
Most of the Chinese cheapo units have been frequency, not phase locked.

It would be great if you could put the GPSDO outputs into a 2 Channel scope and 
eyeball them for a while to see if they appear in phase (say plus-minus 20ns) 
over a few hours.

Tim N3QE

> On Apr 10, 2018, at 1:43 AM, donald collie <donaldbcol...@gmail.com> wrote:
> 
> I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
> error!] They are stated as being new, and use a Trimball dual oven OCXO. I
> plan to run these in parallel [2 antennas, 2 feedlines, and 2 GPSDO`s] It`s
> been said that a man with two watches is never happy - unless, of course,
> they agree with each other ;-). Being identical the outputs should be
> coherent, unless one becomes faulty [one advantage of having two - any
> discrepancy and you know something must be wrong]], but is there some
> crafty way I can squeeze a little more "accuracy" out of two than if I only
> used one?
> TIA for your commentsDonald
> Brett Collie ZL4GX
> 
> PS : I have no connection to the eBay seller. The US$9-50 seems to include
> a basic puck antenna, long downlead, and 4 interseries adaptors
> ___
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Re: [time-nuts] Dual GPSDO - any advantage?

[ewkehren via time-nuts]

Most likely but PayPal will have to get involved since there are more than one 
of usBert Kehren


Sent from my Galaxy Tab® A
 Original message From: Clint Jay  Date: 
4/10/18  10:32 AM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: Re: [time-nuts] Dual GPSDO - any 
advantage? 
Ahh, I've found the listing, has anyone received one?

I hate to say this but I'm highly sceptical that they will ever turn up,
looks and smells very much like the standard eBay scam to me.





On 10 April 2018 at 14:52, Bob kb8tq  wrote:

> Hi
>
> Simple answer is that the “simple” approaches don’t do much to improve
> things.
> Errors are indeed un-correlated, even off of the same antenna. You *could*
> average the result off of the two. That might improve things by sqrt(2). My
> experience is that the bumps and lumps (when they do occur) are not the
> sort
> of thing that averages out nicely…..
>
> Bob
>
> > On Apr 10, 2018, at 1:43 AM, donald collie 
> wrote:
> >
> > I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
> > error!] They are stated as being new, and use a Trimball dual oven OCXO.
> I
> > plan to run these in parallel [2 antennas, 2 feedlines, and 2 GPSDO`s]
> It`s
> > been said that a man with two watches is never happy - unless, of course,
> > they agree with each other ;-). Being identical the outputs should be
> > coherent, unless one becomes faulty [one advantage of having two - any
> > discrepancy and you know something must be wrong]], but is there some
> > crafty way I can squeeze a little more "accuracy" out of two than if I
> only
> > used one?
> > TIA for your commentsDonald
> > Brett Collie ZL4GX
> >
> > PS : I have no connection to the eBay seller. The US$9-50 seems to
> include
> > a basic puck antenna, long downlead, and 4 interseries adaptors
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
>
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>



-- 
Clint. M0UAW IO83

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*
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Re: [time-nuts] Dual GPSDO - any advantage?

[ewkehren via time-nuts]

I have run 2 Tbolts from thee same antenna  in to my Tracor and see the 
corrections are in no way correlated.Bert Kehren


Sent from my Galaxy Tab® A
 Original message From: Florian Teply  Date: 
4/10/18  7:00 AM  (GMT-05:00) To: time-nuts@febo.com Subject: Re: [time-nuts] 
Dual GPSDO - any advantage? 
Am Tue, 10 Apr 2018 17:43:25 +1200
schrieb donald collie :

> I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
> error!] They are stated as being new, and use a Trimball dual oven
> OCXO. I plan to run these in parallel [2 antennas, 2 feedlines, and 2
> GPSDO`s] It`s been said that a man with two watches is never happy -
> unless, of course, they agree with each other ;-). Being identical
> the outputs should be coherent, unless one becomes faulty [one
> advantage of having two - any discrepancy and you know something must
> be wrong]], but is there some crafty way I can squeeze a little more
> "accuracy" out of two than if I only used one?
> TIA for your
> commentsDonald Brett
> Collie ZL4GX

well, my experience in that regard is very limited, not to say
nonexisting, thus take the following with a grain of salt.

Assuming a system with two antenna locations where one device would
be fed both antennas, one could potentially employ some extra
correction based on extra knowledge from these two antennas. Even
though the antenna location usually is known with limited accuracy
(error on the order of 1m), the relative location of two antennas can
be known to a much greater accurracy (order of centimetres or better).
If the system can take that extra information into account, one could
maybe gain some extra accuracy for the solution of time/location.
For example, if the antennas are mounted 1m apart, and everything else
being equal, it is a priori clear, that the calculated position for
both antennas should also be 1m apart. As the signal received by both
antennas should be correlated, while their respective noise
contribution is not, one should gain some SNR. If on top of that time
resolution of the receiver system is very high, one could even take the
phase shift between signals received from both signals into account
similar to the way beam steering is done with phased antenna arrays,
just on receive side, again improving SNR. 
So far for an integrated system, where all signals arew processed in
one place. Now, as I read it you'll rather have two entirely separate
receiver systems. Here, depending on how it is implemented in the
receivers, one could potentially  still gain something extra over a
single unit, but I'd bet this can only be done in postprocessing.
After all, receiver A has no access to the signals as received by
receiver B and vice versa, therefore the spatial relationship can not
be used while deriving the timing solution. Maybe the independent
position solutions could be used to correct the timing solutions after
the fact.

Best regards,
Florian
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Re: [time-nuts] Dual GPSDO - any advantage?

[ewkehren via time-nuts]

Looking at the pictures it is the same unit I bought. It is not dual oven bit 
trimble works with LH right now shows tracking 10 satelites.Attached  is data 
that made  me buy a second one for Jürg for $ 129  and one more for me for 
$9.50.What you see is highly filtered data to see long time changes to better 
understand if analog filtering os possible. Planning on using Wenzel 600 sec. 
Filter maybe up to 2000 seconds. Board is ready for order.Top plot is my data 
against my Cs 5061B bottom is original Tbolt against his FTS  Cs. We use 53132 
counters.I think  the new one lends it self better for filtering looking at 
both  with my Tracor, Trimble uses a  much shorter time constant and no short 
1E-10 changes you see on our standard units.Will keep you posted         Bert 
Kehren

Sent from my Galaxy Tab® A
 Original message From: Tim Shoppa  Date: 
4/10/18  6:46 AM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: Re: [time-nuts] Dual GPSDO - any 
advantage? 
Most of the Chinese cheapo units have been frequency, not phase locked.

It would be great if you could put the GPSDO outputs into a 2 Channel scope and 
eyeball them for a while to see if they appear in phase (say plus-minus 20ns) 
over a few hours.

Tim N3QE

> On Apr 10, 2018, at 1:43 AM, donald collie  wrote:
> 
> I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
> error!] They are stated as being new, and use a Trimball dual oven OCXO. I
> plan to run these in parallel [2 antennas, 2 feedlines, and 2 GPSDO`s] It`s
> been said that a man with two watches is never happy - unless, of course,
> they agree with each other ;-). Being identical the outputs should be
> coherent, unless one becomes faulty [one advantage of having two - any
> discrepancy and you know something must be wrong]], but is there some
> crafty way I can squeeze a little more "accuracy" out of two than if I only
> used one?
> TIA for your commentsDonald
> Brett Collie ZL4GX
> 
> PS : I have no connection to the eBay seller. The US$9-50 seems to include
> a basic puck antenna, long downlead, and 4 interseries adaptors
> ___
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Filter 500 Tb + Tb2.pdf
Description: Adobe PDF document
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Re: [time-nuts] Dual GPSDO - any advantage?

[ewkehren via time-nuts]

I bought one too, is a mistake, I am holding my breath  supposedly shipped I 
previously bought two one for Jürg because it's performance, easier to clean up 
            Bert Kehren


Sent from my Galaxy Tab® A
 Original message From: donald collie  
Date: 4/10/18  1:43 AM  (GMT-05:00) To: Discussion of precise time and 
frequency measurement  Subject: [time-nuts] Dual GPSDO - 
any advantage? 
I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
error!] They are stated as being new, and use a Trimball dual oven OCXO. I
plan to run these in parallel [2 antennas, 2 feedlines, and 2 GPSDO`s] It`s
been said that a man with two watches is never happy - unless, of course,
they agree with each other ;-). Being identical the outputs should be
coherent, unless one becomes faulty [one advantage of having two - any
discrepancy and you know something must be wrong]], but is there some
crafty way I can squeeze a little more "accuracy" out of two than if I only
used one?
TIA for your commentsDonald
Brett Collie ZL4GX

PS : I have no connection to the eBay seller. The US$9-50 seems to include
a basic puck antenna, long downlead, and 4 interseries adaptors
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Re: [time-nuts] Recommendations for Mains Power Monitor / Logger

[ewkehren via time-nuts]

My 20 year old Junghans`s had no problemBert Kehren Palm City Florida


Sent from my Galaxy Tab® A
 Original message From: Tom Van Baak  
Date: 3/11/18  8:32 AM  (GMT-05:00) To: Discussion of precise time and 
frequency measurement  Subject: Re: [time-nuts] 
Recommendations for Mains Power Monitor / Logger 
Bob,

Correct, measuring mains frequency to a couple of digits is not hard. What 
makes an interesting challenge is to monitor mains, "kitchen clock", phase 
drift. And to do it with cycle accuracy; no slips. Note that to measure down to 
1 cycle over 1 day is 0.2 ppm. Over a month, 6 ppb, and over a year, 5e-10. So 
the numbers add up and you see why we use atomic standards or GPS or even NTP 
as a long-term reference for this.

Your measurement system needs to have short- and long-term stability ~10x 
better than:
    http://leapsecond.com/pic/mains-adev-mdev-gnuplot-g4.png

Again, that's not asking a lot. But it makes a really fun project. Much of what 
you ever need to know about time & frequency metrology can be done by a student 
with $10 in parts and a 60 Hz outlet.

/tvb

p.s. Yes, it's very early here on the west coast, but I had to check how badly 
my WWVB clocks handled DST a few hours ago.

- Original Message - 
From: "Bob kb8tq" 
To: "Discussion of precise time and frequency measurement" 
Sent: Sunday, March 11, 2018 4:53 AM
Subject: Re: [time-nuts] Recommendations for Mains Power Monitor / Logger


Hi

So, how good is “good enough?”. My first attempt ran a counter with a 1 us 
period resolution. 
(remember, it was tube based …). That turned out to be major overkill in terms 
of line frequency
measurement. 60.123 Hz is doing pretty well in terms of line frequency. Even to 
get that level, you 
will be doing a bit of filtering (or you are  just watching the last two digits 
pop around randomly). 

Your typical time base in a PC is good to a few hundred ppm. That’s giving you 
an error in the 
fourth digit of your measurement. With a bit of luck, your sound card timebase 
may be 5X 
more accurate than your system clock. (or it may be worse …) it depends a bit 
on how fancy
your audio setup is. 

Adding NTP to your PC will correct for any long term errors. In a rational 
environment it should 
get you into the “few ppm” range short term and zero error long term. 

A GPS gizmo will get you into the parts per billion (or better) range. It might 
be 100’s of ppb, but it’s
still *way* better than your CPU clock. The usual auction sites have lots of 
candidates in the sub $50
range.There are also places that are happy to sell you shields with GPS devices 
on them.

A fancier yet solution is a GPSDO. We are well into overkill at this point. The 
advantage to using
one is that it may be the time / frequency standard for your entire lab setup. 
You are up in the 
$100 to $500 range for most of them. They will get you into 10’s or 100’s of 
parts per trillion. 

There are indeed *lots* of different time sources you could use. The number of 
alternatives is 
*much* larger than what’s on the list above.

Bob

> On Mar 10, 2018, at 11:46 PM, Tom Van Baak  wrote:
> 
>> I've done some Googling and have found any number of designs.
> 
> Pat,
> 
> 1) Safety. I usually use a low voltage step-down transformer. This gives 
> isolation and safety. Anything from 3 VAC to 24 VAC is fine.
> 
> 2) Trigger. There are dozens of schematics on the web for capturing the 
> zero-crossing of a low-voltage sine wave. You can easily go overboard on 
> this. Or just keep it simple and feed the signal through a resistor directly 
> into a microprocessor input. The internal clamping diodes do their thing. A 
> Schmitt trigger input is helpful but not necessary depending on how your 
> software makes the measurement.
> 
> 3) Timebase. Given the long-term accuracy of mains (seconds a day, seconds a 
> year) you don't need an atomic timebase. If you collect data for a couple of 
> days any old XO will be fine. If you plan to collect data for months you may 
> want a OCXO. Most of us just use cheap GPS receivers.
> 
> 4) Measurement. There are many ways to measure the signal. You can measure 
> frequency directly, as with a frequency counter. You get nice data but it may 
> not be perfect long-term due to dead time or gating effects in the counter.
> 
> So what most of us do is measure phase (time error) instead. One way is to 
> make time interval measurements from a given mains cycle to a GPS 1PPS tick 
> or vice versa, from each GPS/1PPS tick to the very next mains cycle. Either 
> way you get about sample per second. If you're in search of perfection it 
> gets a bit tricky when the two signals are in a coincidence zone.
> 
> The other approach is not to use a frequency or time interval counter at all. 
> Instead you timestamp each cycle, or every 60th cycle. Unix-like systems have 
> this capability. See 

Re: [time-nuts] LT1016 as a pulse shaper...

[ewkehren via time-nuts]

BruceWisjh I had known about it a week ago and we could have added a board to 
the A9 order. Next order is probably three weeks away ifIi can help contact me 
off list     Bert Kehren
Sent from my Galaxy Tab® A
 Original message From: Bruce Griffiths 
 Date: 3/4/18  8:32 PM  (GMT-05:00) To: Hal Murray 
, Discussion of precise time and frequency measurement 
 Subject: Re: [time-nuts] LT1016 as a pulse shaper... 
Since I have a Timepod all that I'd need would be a board that had SMA inputs 
and outputs with provision for an LC L network to  step up the input if 
necessary plus an RLC network on the output something like in the attachment.

If one doesnt have a Timepod or equivalent a low noise phase detector will 
suffice for the noisier sources. An adjustable phase shift network is required 
to achieve quadrature between the LO (driven directly from the splitter) and 
the RF input (driven by the DUT output).

The required phase shift adjustment range could perhaps be reduced by using a 
quadrature hybrid to split the test source instead of a standard splitter. The 
output of the phase detector is low pass filtered and amplified and fed to a 
high resolution ADC such as a sound card.

Bruce

> 
> On 05 March 2018 at 13:59 Hal Murray  wrote:
> 
> Bruce Griffiths  said:
> 
> > > 
> > If I had a suitable PCB board for it I would do the measurement 
> >properly.
> > 
> > > 
> What would a suitable board look like and/or what sort of gear do you 
>need to
> measure PN?
> 
> --
> These are my opinions. I hate spam.
> 
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Re: [time-nuts] LT1016 as a pulse shaper...

[ewkehren via time-nuts]

We only use three circuits Wenzel sn65ELT35 and LTC6957. For critical 
applications it is the LTC we refer to it in our designs the Bruce circuit the 
only problem is solderability, my eyes. Bought 25, to poor to buy junk and not 
smart  enough to select something less in critical applications.        Bert 
Kehren


Sent from my Galaxy Tab® A
 Original message From: Bruce Griffiths 
 Date: 3/3/18  4:56 PM  (GMT-05:00) To: "David C. 
Partridge" , Discussion of precise time and 
frequency measurement , Ulf Kylenfall  
Subject: Re: [time-nuts] LT1016 as a pulse shaper... 
Hystersis (exhibited by 74xx14 devices) results in AM to PM conversion which 
increases as the amount of hysteresis increases.


Bruce

> 
> On 04 March 2018 at 10:34 Bruce Griffiths  
>wrote:
> 
> Ideally one should use a Collins style optimised cascade of increasing 
>bandwidth and gain limiting stages. The LTC6957 with its selectable input 
>stage bandwidth has a performance that is comparable with the Holzworth sine 
>to CMOS "amplifier" which is better than any comparator by itself. If the 
>amplitude of the input signal is large enough (i.e. input slew rate seen by 
>the gate is large enough) the performance of a single CMOS gate can be very 
>good. However the performance of current CMOS gates degrades in this 
>application with input frequencies of 100MHz and above.
> 
> Measuring the PN performance of CMOS gates used as sine to CMOS 
>converters is on the todo list.
> 
> Bruce
> 
> > > 
> > On 04 March 2018 at 06:38 "David C. Partridge" 
> > wrote:
> > 
> > You might consider using MC74VHC1GT14 or MC74VHC1G14 (Schmitt 
> >trigger inverting buffers) depending on the exact voltage levels.
> > 
> > They are fast (74AC logic fast) single gate devices in SC70 
> >(SOT-353) or SOT23-5 case and can drive 25mA output if needed.
> > 
> > I've seen documents saying that using fast logic gates can result 
> >in lower jitter/phase noise. Bruce - do you know ?
> > 
> > David
> > 
> > -Original Message-
> > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of 
> >Ulf Kylenfall via time-nuts
> > Sent: 03 March 2018 17:08
> > To: Discussion of Precise Time and Frequency Measurement
> > Subject: [time-nuts] LT1016 as a pulse shaper...
> > 
> > Gentlemen,
> > I have so far been using LT1016 as a pulse shaper and also whenever 
> >I needed toconvert a sine wave into TTL Logic levels. Some hysteresis and 
> >all the decouplingand layout precautions as recommended by LT.
> > Are there any similar or better alternatives out there that could 
> >be usedthat would provide lower jitter and that are less expenceive?
> > 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] Microsemi up for sale?

[ewkehren via time-nuts]

The manager many not know but the market does and there have been announcements 
and the stock is up and for the day the fifth most active of all US markets. At 
2 pm #2    Bert Kehren


Sent from my Galaxy Tab® A
 Original message From: "Richard (Rick) Karlquist" 
 Date: 3/3/18  9:30 AM  (GMT-05:00) To: Discussion of 
precise time and frequency measurement , Anders Wallin 
 Subject: Re: [time-nuts] Microsemi up for sale? 
I asked the CBT manager at Microsemi about this
rumor and he disavowed any knowledge of this.
He told me they were making 8 a week (not clear
if this is just 5071A's, or includes replacement
CBT's).  I don't remember the production ever
being anywhere near this level.  The reason
for the relatively brisk sales is that the risk
of GPS spoofing means that various military and
3 letter agencies need to own dedicated 5071's.
With a large installed base of 5071's, there will
be a guaranteed market for replacement tubes.
The US government considers the 5071A to be of
great strategic importance and would be certain
to "encourage" its continued production in case
of any business reorganization.

When we designed the 5071A twenty five years ago,
it seemed that there were two safe bets:

1.  Working Cs standards (outside the lab) would
obsoleted by what HP called "smart clocks" running
off of GPS.

2.  Magnetic state selection, as used in the 5071A,
would be replaced by optical pumping.  Len Cutler
was heartbroken that HP/Agilent management wouldn't
fund this effort.

It turns out that, even now in 2018, optical pumping
is not ready for prime time in a working standard
because the lasers drift over time.  The 5071A's
claim to fame is that you turn it on and it just
works ... until it runs out of cesium.  That is
another reason the 5071A isn't going away any time soon.

Rick Karlquist N6RK
Member: 5071A design team

On 3/3/2018 1:22 AM, Anders Wallin wrote:
> Just a change to the last part of the name then ;)
> https://www.ft.com/content/10192a2a-1d99-11e8-956a-43db76e69936
> "semi" -> "chip"
> 
> 
> On Sat, Jan 27, 2018 at 1:27 AM, Clint Jay  wrote:
> 
>> Perhaps of interest to the list
>>
>> https://www.theregister.co.uk/2018/01/25/microsemi/
>>
>> --
>> Clint.
>>
>> *No trees were harmed in the sending of this mail. However, a large number
>> of electrons were greatly inconvenienced.*
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[time-nuts] M12 furono

[ewkehren via time-nuts]

What is latest on a group buy, have I missed something I am ready to buy        
Bert Kehren



Sent from my Galaxy Tab® A
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Re: [time-nuts] FRK

[ewkehren via time-nuts]

PaulI have never seen a FRK or M 100 that did not have a screw iin lamp but 
Attila`s unit looks like nothing I have seen before,  I am not a Corby but over 
time 20 units have passed through my hands      
Bert


Sent from my Galaxy Tab® A
 Original message From: paul swed  Date: 
2/27/18  1:45 PM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: Re: [time-nuts] FRK 
Bert what I assume is the FRK lamp. it has a few wires and then 2 pins out
of the side.
Unless those are for mounting the lamp.
Regards
Paul
WB8TSL

On Tue, Feb 27, 2018 at 11:21 AM, Attila Kinali  wrote:

> On Tue, 27 Feb 2018 09:01:31 -0500
> Bob kb8tq  wrote:
>
> > Judging from the date codes on some of the parts, I’d guess that
> > your FRL-L is from 1982. I’m only looking at a few parts that came
> > through well enough in the picture to read (and that have what look
> > like rational date codes …).
>
> Sorry, I didn't take much care when taking the pictures.
> I can do better ones later.
>
> But yes, the board has definitely an 80s vibe. The whole construction
> is different then what I am used to from 80s electronics, though.
> But I guess that's because it was designed and manufactured for
> hi-rel applications.
>
> Attila Kinali
>
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>  -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] FRK

[ewkehren via time-nuts]

Which one are you talking aboutBert Kehren


Sent from my Galaxy Tab® A
 Original message From: paul swed  Date: 
2/27/18  9:26 AM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: Re: [time-nuts] FRK 
Thanks for the pictures.
Curious on the rb lamp.
There seem to be 2 pins from the side. Is that a lamp start igniter?
Regards
Paul
WB8TSL

On Tue, Feb 27, 2018 at 9:01 AM, Bob kb8tq  wrote:

> Hi
>
> Judging from the date codes on some of the parts, I’d guess that
> your FRL-L is from 1982. I’m only looking at a few parts that came
> through well enough in the picture to read (and that have what look
> like rational date codes …).
>
> Bob
>
> > On Feb 27, 2018, at 5:30 AM, Attila Kinali  wrote:
> >
> > On Mon, 26 Feb 2018 20:04:56 -0800
> > "Tom Van Baak"  wrote:
> >
> >> Bert's M100 Rb teardown photos are now here:
> >>
> >> http://leapsecond.com/bert/m100.htm
> >
> > For those, who would like to see the rest of M100/FRK,
> > I just took pictures of my FRK-L that was sitting on my
> > desk for way too long:
> >
> > http://time.kinali.ch/Efratom_FRK-L/
> >
> > Yes, there are only the pictures of the four PCBs from outside.
> > I didn't want to take the FRK further appart, as that would
> > require a soldering iron, and I really should be doing something
> > else.
> >
> >   Attila Kinali
> >
> > --
> > It is upon moral qualities that a society is ultimately founded. All
> > the prosperity and technological sophistication in the world is of no
> > use without that foundation.
> > -- Miss Matheson, The Diamond Age, Neil Stephenson
> > ___
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> mailman/listinfo/time-nuts
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>
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Re: [time-nuts] FRK

[ewkehren via time-nuts]

Thank you Attila, I have seen many FRK`and M 100 but not one like yours. Some 
boards are very different and it is very difficult  to get proper 
documentation.Bert Kehren

Sent from my Galaxy Tab® A
 Original message From: Attila Kinali  Date: 
2/27/18  5:30 AM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: Re: [time-nuts] FRK 
On Mon, 26 Feb 2018 20:04:56 -0800
"Tom Van Baak"  wrote:

> Bert's M100 Rb teardown photos are now here:
> 
> http://leapsecond.com/bert/m100.htm

For those, who would like to see the rest of M100/FRK,
I just took pictures of my FRK-L that was sitting on my
desk for way too long:

http://time.kinali.ch/Efratom_FRK-L/

Yes, there are only the pictures of the four PCBs from outside.
I didn't want to take the FRK further appart, as that would
require a soldering iron, and I really should be doing something
else.

Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Replacement A9 boards for the HP 5065A

[ewkehren via time-nuts]

We have decided to go with the 1012 do we need to do any thing with pin 5Bert 
kehren


Sent from my Galaxy Tab® A
 Original message From: Attila Kinali  Date: 
2/26/18  9:53 AM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: Re: [time-nuts] Replacement A9 boards 
for the HP 5065A 
On Sat, 24 Feb 2018 23:44:16 -0500
Charles Steinmetz  wrote:

> Given the relatively low resistances at the op-amp inputs (10k ohms), 
> the ultra-low input "bias" (leakage) current of the 6240 is simply 
> unnecessary.  Any offset due to the input currents (within the general 
> range of any of these op-amps) is insignificant compared to the op-amp's 
> offset voltage.  Thus, offset voltage, offset voltage tempco, and offset 
> voltage long-tem drift are the critical parameters (as Poul-Henning 
> pointed out).  And here, the 1012 is clearly the best of the three.  In 
> addition to having the lowest input offset spec, the 1012 has guaranteed 
> maximum specifications for these important parameters.  The 6240 (for 
> good reason) is *not even rated* for long-term stability (drift). 
> (Long-term offset stability is a particular weakness of CMOS op-amps.)

Oh.. right, I didn't think about long term behaviour. Thanks for the correction!

BTW: How about using an LTC2057 then? Its input bias current  and
GBW spec is similar to the LT1012, but its offset voltage and drift
are far superior. Or would its charge injection noise be too large
for this application?

Attila Kinali



-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] FRK

[ewkehren via time-nuts]

Thank you I am presently only on my tablet I will be on my laptop in the 
morning do not think that there is much interest hardware or solder iron 1%Bert


Sent from my Galaxy Tab® A
 Original message From: Arnold Tibus <arnold.ti...@gmx.de> 
Date: 2/25/18  11:04 AM  (GMT-05:00) To: time-nuts@febo.com Subject: Re: 
[time-nuts] FRK 
Bert, you may upload it to this directory, which timenuts can then 
access and download as well, using this directory also:
https://my.hidrive.com/share/5fohndsi4k
The up- and downloads are much faster and there is no Mbit limit.
I will keep it open for a while. Give me a note if this ok for you.
Try it.
Of course, from time to time I will clean up a bit.

Regards,

Arnold, DK2WT

Am 25.02.2018 um 15:05 schrieb ewkehren via time-nuts:
> We have pictures of the guts of a M100 the file is 1.8 M off list or 
> permission to postBert Kehren
> 
> 
> Sent from my Galaxy Tab® A
> ___
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Re: [time-nuts] Replacement Backup Battery for 5065A?

[ewkehren via time-nuts]

Discooect I have seen them leak all over the placeBert Kehren 


Sent from my Galaxy Tab® A
 Original message From: Stan  Date: 
2/25/18  2:41 PM  (GMT-05:00) To: time-nuts@febo.com Subject: [time-nuts] 
Replacement Backup Battery for 5065A? 
With all this recent 5065A talk I decided to pull mine out of storage and fire 
it up. After a little time to let everything warm up and settle in, I'm happy 
to report that it's working just fine!

My 5065A has the battery backup option, and the battery is the original one 
(1420-0066, Energy Sales p/n ES710, 25.2V 1.4 Ah). Not surprisingly, the 
battery is quite dead. Does anyone any insight about installing a more modern 
battery (SLA or NiMH, perhaps) that will fit in the battery compartment in the 
5065A?

I've looked at a few small 12V/2.2Ah SLA batteries that are physically small 
enough that I should be able to fit a couple in the enclosure and connect them 
in series to get 24 volts out, but I want to wait until either I have assurance 
from someone with more experience than I that this will actually work, or a 
better idea about a more suitable replacement.

Thanks,
Stan

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[time-nuts] FRK

[ewkehren via time-nuts]

We have pictures of the guts of a M100 the file is 1.8 M off list or permission 
to postBert Kehren 


Sent from my Galaxy Tab® A
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Re: [time-nuts] Replacement A9 boards for the HP 5065A

[ewkehren via time-nuts]

Corby is still asleep, on the old board it was 0.5 uF and 100K now 5 uF and 
10K. Who knows what HP knew in the 60`s but it works and I dought that it is 
critical. No where is there any fine  tuning like two resistors in seriesBert 
Kehren 

Sent from my Galaxy Tab® A
 Original message From: Bill Hawkins  
Date: 2/24/18  10:26 PM  (GMT-05:00) To: 'Discussion of precise time and 
frequency measurement'  Subject: Re: [time-nuts] 
Replacement A9 boards for the HP 5065A 
Corby

A time constant is calculated from R and C.

If 50 milliseconds is the correct number, R for 5 mfd is 10,000 ohms.

You could use an aluminum electrolytic for the capacitor.

Can you tell us where the 50 ms number came from?

Regards,
Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of
cdel...@juno.com
Sent: Saturday, February 24, 2018 5:45 PM
To: time-nuts@febo.com
Subject: [time-nuts] Replacement A9 boards for the HP 5065A

Hi,

I'm working to make some replacement A9 boards for the HP 5065A to the
new style schematic.

Will share the Gerber file when done.

The integrator capacitor is a 1986 vintage TRW 5.0ufd 50V 10%
.42"DX1.0"L axial.

Of course it has an HP part number and no manufactures #.

Any guess as to what type it is?

Polycarbonate, polypropylene, ???

Just wanting to find a good modern replacement for its use. (Integrator
with a 50ms time constant.)

Thanks,

Corby

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Re: [time-nuts] "Super Rubidium" filter mod for PRS-10?

[ewkehren via time-nuts]

I still stand by FRK, next to HP largest cell, Corby did it with a M 100 much 
more difficult. I started on a FRK but because of a macular hole in my left eye 
had to stop.First  test  should be to change time constant and monitor 
performance.Remember the outstanding performance  of the HP is do to the fact 
that the optical unit takes over somewhere around 0.1 seconds.FRK is well 
documented and easy to work on.We have pictures have to compress to attach to 
time nuts or contact me off list.Again if some one wants to take over please 
contact me directBert Kehren 


Sent from my Galaxy Tab® A
 Original message From: Poul-Henning Kamp  
Date: 2/25/18  5:22 AM  (GMT-05:00) To: Discussion of precise time and 
frequency measurement , Stewart Cobb 
 Subject: Re: [time-nuts] "Super Rubidium" filter mod 
for PRS-10? 

In message 

Re: [time-nuts] Curious, how many t-nuts have 5065A

[ewkehren via time-nuts]

Old color and a little expensive only one partial pictureBert Kehren


Sent from my Galaxy Tab® A
 Original message From: Bob kb8tq  Date: 2/24/18 
 9:30 AM  (GMT-05:00) To: George Atkinson , 
Discussion of precise time and frequency measurement  
Subject: Re: [time-nuts] Curious, how many t-nuts have 5065A 
Hi

The “pickup only” part of the deal would be a bit of an issue for some of us :)

Bob

> On Feb 24, 2018, at 5:46 AM, George Atkinson via time-nuts 
>  wrote:
> 
> There is one on UK ebay at the moment but its not being given away. From the 
> one partial photograph it looks a bit rough.
> 
> https://www.ebay.co.uk/itm/HP-5065A-Rubidium-Frequency-Standard/183057846558?
> 
> Robert G8RPI.
> 
>> 
>>    On 24 February 2018 at 10:02 John Miles  wrote:
>> 
 
>>>    Hi
>>> 
>>>    Well, if anybody else is “giving away” 5065’s I’d certainly be 
>>>willing to
>>>    “accept”
>>>    one :)
>>> 
>>>    Bob
>>> 
 
>>    Be careful what you wish for. :) The unit Pete is talking about is a 
>>1969-era model, in nice overall shape but with the usual bad capacitors on 
>>the oven controller board. The lamp oven winding should be about 50 ohms 
>>cold, but is closer to a dead short. It will take a LOT of work to restore to 
>>working condition.
>> 
>>    The failed controller ran long enough to smoke a 1.5-ohm 1W resistor, 
>>1N400-something diode, and eventually the 1A line fuse ( 
>>http://www.ke5fx.com/5065A_A11_sm.jpg ). Needless to say the lamp PCB looks 
>>like something out of Fukushima. It'll need to be rebuilt from scratch after 
>>rewinding the heater.
>> 
>>    Seriously -- anyone with a 5065A who hasn't checked/replaced the caps on 
>>A11, don't let this happen to you. They aren't making any more of these 
>>puppies. If the caps on that board are original, don't bother to check them, 
>>just replace them, as Luciano suggests at 
>>http://www.timeok.it/hp5065a-corner-3/. No need for exotic parts, just put in 
>>whatever you have that is somewhere close to the original values.
>> 
>>    Not a bad idea to verify the ESR of the new parts you're installing as 
>>well.
>> 
>>    -- john, KE5FX
>>    Miles Design LLC
>> 
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Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

[ewkehren via time-nuts]

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


Sent from my Galaxy Tab® A
 Original message From: "Van Horn, David" 
 Date: 2/22/18  4:44 PM  (GMT-05:00) To: 
Discussion of precise time and frequency measurement  
Subject: Re: [time-nuts] Teardown of Chinese made eBay GPS antenna. 
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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--
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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] Curious, how many t-nuts have 5065A

[ewkehren via time-nuts]

Do not know but it is the holy grail of AV nuts short of a Maser  or 8607Bert 
Kehren


Sent from my Galaxy Tab® A
 Original message From: Pete Lancashire 
 Date: 2/22/18  9:44 AM  (GMT-05:00) To: Discussion of 
precise time and frequency measurement  Subject: 
[time-nuts] Curious, how many t-nuts have 5065A 
no reason other then  curious

-pete
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Re: [time-nuts] eBay GPS antenna.

[ewkehren via time-nuts]

Please keep us informed I bought onBert Kehren


Sent from my Galaxy Tab® A
 Original message From: John Green  Date: 
2/6/18  4:03 PM  (GMT-05:00) To: time-nuts@febo.com Subject: Re: [time-nuts] 
eBay GPS antenna. 
I kind of have to believe the specs. The two survey grade antennas I
already have, a Leica and a Trimble, both have regulators in the preamp
sections. The Leica has an 8 volt one and the Trimble has a 5 volt one. I
intend to hook it up to a variable supply and watch the current as I
increase voltage. If it has a regulator, the current should stabilize at an
input voltage just above what the internal preamp operates at. If not, it
should continue to rise. I am tempted to pry it apart, even if it risks
damage just so I can see for myself what they are using for the preamp
stages.
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Re: [time-nuts] Trimble Thunderbolt Issue

[ewkehren via time-nuts]

Do not toss, first check output of OCXO if good keep if you do not fiend the 
problem. If no output replace. If L H shows that it works bring OCXO output 
directly.Bert Kehren 


Sent from my Galaxy Tab® A
 Original message From: Richard Solomon  
Date: 1/26/18  1:39 PM  (GMT-05:00) To: time-nuts  Subject: 
[time-nuts] Trimble Thunderbolt Issue 
I have a T-Bolt whose 10 MHz output has dropped off to about 6 mV. Using T-Bolt 
Mon,

all the Alarms are Green and it shows Tracking 3 or 4 Satellites (small Hockey 
Puck Antenna).


Without a schematic I am lost as to where to look.


Anyone have any suggestions ? I had to toss an otherwise working T-Bolt.


Thanks for any assistance,


Dick, W1KSZ


Sent from Outlook
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Re: [time-nuts] Suggestion for a timing GPS receiver (Trimble / Ublox /other?)

[ewkehren via time-nuts]

The cheapest is not a 5T there are many 6 and 7 for $ 10. T gives you nothing 
unless you  have saw tooth correctionBerrt Kehren


Sent from my Galaxy Tab® A
 Original message From: Paride Legovini via time-nuts 
 Date: 1/23/18  12:24 PM  (GMT-05:00) To: 
time-nuts@febo.com Subject: Re: [time-nuts] Suggestion for a timing GPS 
receiver (Trimble /
  Ublox /other?) 
On 2018-01-23 08:11, David J Taylor via time-nuts wrote:
> Dear fellow nuts,
> 
> I plan to build a decent GPS/GNSS-based Stratum 1 NTP server, and I'm
> looking for a good and possibly affordable timing GPS receiver.
> []
> Am I overlooking something or missing interesting options?
> 
> Cheers,
> 
> Paride IZ3SUS
> 
> 
> Paride,
> 
> As Mark notes, you don't need a timing precision GPS receiver for NTP
> 
> [...]
>
> Stephen mentioned the newer series-8 ublox modules.  These are indeed
> excellent (and can receiver Galileo too)

Thanks David and thanks to you all for the advice you gave me, I
carefully read all your replies and learned quite a few things.

At this point I think I'll start tinkering with the cheapest module I
can get (and it will probably be a LEA-5T). Once I'll have everything
set up, if I'll be still having fun, I'll consider buying a newer
module, probably from the Ublox M8 family. We will see.

73,
Paride
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Re: [time-nuts] Holdover, RTC for Pi as NTP GPS source

[ewkehren via time-nuts]

Tbolt is a good oneBert Kehren


Sent from my Galaxy Tab® A
 Original message From: David J Taylor via time-nuts 
 Date: 11/1/17  12:07 PM  (GMT-05:00) To: 
time-nuts@febo.com Subject: Re: [time-nuts] Holdover, RTC for Pi as NTP GPS 
source 
From: Mark Sims

I have an analytical balance that reads down to micrograms.   The weigh 
chamber is surrounded by three layers of IR absorbing glass so that radiated 
body heat does not induce convection currents in the air.   I worked on a 
balance that had nanogram resolution (mostly wishful thinking in that spec). 
It operated in a vacuum.  30 bit mass-to-digital converters are rather 
finicky beasties.

It does not take all that good of a temperature sensor to detect changes in 
room temperature due to body heat (or fetching a beer from the fridge in the 
next room).  You are basically a 100 watt space heater... even larger for 
the more corpulent folks.
==

Temperature is indeed the killer.  My best Raspberry Pis for time-keeping 
are RasPi-1 and RasPi-4, both of which are in an unheated cupboard not 
exposed to sunlight, on the north side of the house with indoor patch GPS 
antennas.

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

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

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Re: [time-nuts] PRS10 PRBB Shematics

[ewkehren via time-nuts]

The PRS10 was intended as FRS alternative you can use the same plug with no 
changes on both unitsBert Kehren


Sent from my Galaxy Tab® A
 Original message From: Mark Sims  Date: 
10/7/17  1:58 PM  (GMT-05:00) To: time-nuts@febo.com Subject: [time-nuts] PRS10 
PRBB Shematics 
SRS sells the connector.   You might want to make sure you have a tube of 
ass-lube handy when you check the price...  It's around three times the 
distribution price.  SRS really should have used a standard D-sub and a couple 
of SMA connectors.

I considered laying out a PRBB clone, but didn't want to mess with sourcing 
that damn connector.  I wound uo buying the PRBB and the heatsink (and a tube 
'o lube).   Spent more for those than the PRS-10.   The heatsink they ship now 
does not seem to be nearly as good as the older one.  Also be aware that the 
SRS ordering page is not HTTPS and your credit card info is sent in plain 
text...  you might want to order over the phone.
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Re: [time-nuts] True Position GPSDP + Rb X72

[ewkehren via time-nuts]

Starting with a 10 second clean up loop for a FEI 5680/GPSDO to now 600 Seconds 
using Wenzel's j circuit for the Tbolt we have a variety of boards. I am 
presently out of country but when back will gladly attach some board designs, 
material cost is minimal  if there is interest.Bert Kehren


Sent from my Galaxy Tab® A
 Original message From: Hal Murray  
Date: 9/23/17  9:39 PM  (GMT-05:00) To: Discussion of precise time and 
frequency measurement  Cc: hmur...@megapathdsl.net Subject: 
Re: [time-nuts] True Position GPSDP + Rb X72 

kb...@n1k.org said:
> If the main use is feeding test gear (and not direct synthesis) an Rb may do
> pretty well. Most instruments assume a dirty reference signal and clean it
> up internally.  

What's the bandwidth on the typical cleanup PLL?  How well does that match 
the noise from a Rb?


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] OCXO inside the FEI AN/URQ-23

[ewkehren via time-nuts]

Thanks I have 2. Will run some tests. In my opinion ADEV does hide changes in 
Frequency and we see it when we compare ADEV plots with at the same time 
frequency measurements. We see it with your plots on the Tbolt. The URQ shows 
frequency specs 2E-12 most likely ADEVBert


Sent from my Galaxy Tab® A
 Original message From: Tom Van Baak  
Date: 7/25/17  11:37 AM  (GMT-05:00) To: Discussion of precise time and 
frequency measurement  Subject: Re: [time-nuts] OCXO inside 
the FEI AN/URQ-23 
Bert,

In the early days of time-nuts the URQ-10, and especially the URQ-23, were 
highly sought after because of their reported stability. By now they are quite 
rare. Do you have one?

If it's important I can dig one out from the closet and run tests for you.

> "Question if it is frequency or ADEV".

I'm not sure what you mean. There is no such thing as "frequency" vs. "ADEV".

/tvb

- Original Message - 
From: "Bert Kehren via time-nuts" 
To: 
Sent: Tuesday, July 25, 2017 7:48 AM
Subject: [time-nuts] OCXO inside the FEI AN/URQ-23


> Has any one run tests of the OCXO inside the AN/URQ-23. Data in the manual  
> looks promising. Question if it is frequency or ADEV
> Bert Kehren


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

[ewkehren via time-nuts]

Having  had a fan failure on a well insulated Rb we use a temperature sensor 
also used for compensation in to a PIC to shut down the systemBert Kehren

Sent from my Galaxy Tab® A
 Original message From: "David G. McGaw" 
 Date: 5/10/17  11:20 PM  (GMT-05:00) To: 
Discussion of precise time and frequency measurement  
Subject: Re: [time-nuts] Fwd: HP10811 Oscillator Thermal Fuse 
I too have had a fuse open up due to a failed thermistor in a HP10811.

David N1HAC


On 5/10/17 7:43 PM, Dan Rae wrote:
> As I reported the last time this subject came up, or maybe the time 
> before, the only time I had an open thermal fuse was in a 10811 that 
> had an open thermistor.  I was able to replace that and get the OCXO 
> working, but if the fuse had been replaced with a wire link I'm sure 
> the entire oven would have been toast.
>
> There have been two types of fuse fitted, all I those have are the 
> type that can be fitted with the plug in axial panasonic type, less 
> than a dollar from Digikey.  The older ovens had a different type but 
> I imagine it's similarly easy to replace.
>
> All my 10811s have the higher temperature Panasonic fuse fitted and I 
> sleep well at night...
>
> Dan
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Re: [time-nuts] Anyone using UBLOX LEA-M8F for GPSDO?

[ewkehren via time-nuts]

Neil we  have used M7 and I have boards contact me off list toBert Kehren 


Sent from my Galaxy Tab® A
 Original message From: Neil Smith G4DBN  Date: 
5/10/17  4:03 PM  (GMT-05:00) To: Discussion of precise time and frequency 
measurement  Subject: [time-nuts] Anyone using UBLOX 
LEA-M8F for GPSDO? 
I’ve just ordered an LEA-M8F board from CSG to save time and trouble making a 
PCB. I am intending to use it to discipline one of my 100MHz OCXOs, using a /5 
divider.  Has anyone on the list used this chip to discipline an external OCXO? 
Any experiences to share and suggestions to get best performance?  I have two 
100MHz OCXOs, one is locked to a G3RUH 10MHz GPSDO, the other to an Rb source.  
I use them to lock local oscillators for SHF transverters. I’ll be using this 
when out in the field with SHF sources up to 241GHz, so I don’t have to move 
the Rb source around.

No particular reason for choosing the LEA-M8F other than it looks interesting 
to play with. Actually, who needs a better reason!
Neil
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Re: [time-nuts] hm H Maser

[ewkehren via time-nuts]

Do we know what the PHM development for Galileo cost?




Sent from Samsung tabletBob Camp  wrote:Hi

> On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>> 
>> Hi
>> 
>> Ok here are some rough numbers:
>> 
>>> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> 
>>> It would be interesting to see your breakdown of the costs and man hours
>>> for an H2 maser. I suspect that others would find cheaper/faster
> solutions.
>> 
>> $100M for the H2
>> 
>> $25M for the Rb
> 
> With all due respect,  and I apprectiate you have a good knowledge of this
> field, but that's not a breakdown of costs or man hours I wanted to see,
> but a cost which appears to be plucked from the air.

Hardly plucked from the air. The last Rb design that I was involved with was 
roughly 5X that expensive. 

> 
> There's a BIG difference between a volunteer effort where
> 
> * Salaries are not paid
> * Items of test equipment are likely to be borrowed or people provide
> access to them for no charge etc,
> * Academics are likely to provide consultancy for free, in return for being
> on papers published.
> * Software licenses could probably be obtained free,  or enough people get
> trials.

That’s where the 5:1 cost reduction comes from. 

> 
> compared to a commercial company building a maser where
> 
> * Salaries are paid
> * All equipment is purchased new
> * Bench power supplies with 3.5 digit displays are sent out for calibration
> each year.
> *  No outside body will do anything except at a commercial rate.
> * Flights are booked for meetings which could be done over the Internet.
> * High end software licenses are huge.
> 
>> $500M for the fountain.
> 
> But on what basis do you arrive at that figure?

The numbers that the people who have done it come up with when you talk to 
them. 

> 
>> To get sponsorship for anything remotely close to those numbers, you
>> need to have some massively good credentials.
>> 
>> Bob
> 
> Yes agreed at $500M. But someone like Tom, who does have massively good
> credentials, could perhaps get $500,000, and perhaps that wisely spent
> could get a fountain built.  Without knowing how you arrive at $500M, it is
> not possible for anyone to look at ways of shaving that cost.


This is *not* a cheap field to be doing things in ….

Bob

> 
> The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
> budget. It was at the time the world's  largest steerable radio telephone.
> Half a century later only 2 larger ones have been built.
> 
> Maybe I am too nieve.
> 
> Dave.
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Re: [time-nuts] Tbolt issues

[ewkehren via time-nuts]

Know all that that is why we decided not to do it. Not knowing all the ins and 
outs and limits of the Tbolts that is why I asked the question to begin with
Bert Kehren




Sent from Samsung tabletCharles Steinmetz  wrote:Bert 
wrote:

> On our to do list was temperature control and clean up loop.  In order to do
> an analog clean up we need short interval changes and that is why  I went
> on the list since we have not been able to do it and looking at past  posting
> have not found data that will get us there.

To do any kind of "cleanup" at tau=1S, you need a source that is better 
at that tau than the one you are trying to clean up.  But if you have 
that, why use it to clean up something else?  Just use it as your 
standard.  (One might respond that the point would be to use the Tbolt 
to discipline the better oscillator at longer tau to correct drift, but 
you would need a very long time constant -- thousands of seconds -- 
which you cannot achieve with an analog loop.)  I do not think there is 
any realistic possibility of doing the kind of cleanup you propose in 
the analog domain.

Are you absolutely certain you tried the Tbolt with the damping set to 
10 seconds or more?  Did you let it settle for several weeks before 
deciding it wasn't doing what you need?

Perhaps you can try one last time:

1. Do a hard reset back to factory settings
2. Change TC to 500 seconds and damping to 10-12
3. Set recovery jam synch to "ON" with a threshold of 55-65 nS
4. Set recovery max offset frequency to >=1000 (this is in ppb)
5. Put it in an undisturbed location, inside a box of some kind
6. Let it sit for a month
7. Now, measure it

If this is better, but not quite good enough, try damping settings of 30 
and 100.

Alternatively, for a 10MHz reference you can just forget about and use, 
buy another PRS10 and discipline it with the PPS from the Tbolt.  I'd 
recommend buying a new one from SRS so you know that it has the PPS 
discipline feature and you could get help from SRS to optimize the 
discipline for your needs (the discipline is very adjustable and it is 
easy to get confused).

Best regards,

Charles


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Re: [time-nuts] FE-5680A software calibration units ?

[ewkehren via time-nuts]

Depends on who you got it from




Sent from Samsung tabletNick Sayer via time-nuts  
wrote:When I got it, the setting was zero. That suggests to me that the factory 
tuning was erased, assuming that the factory tunes it the same way - by 
changing the value adjusted by that software.

> On Sep 21, 2015, at 4:34 AM, Bob Camp  wrote:
> 
> Hi
> 
> Assuming it shows locked, that would suggest that (for what ever reason) 
> it’s been re-tuned at some point after it left the factory.
> 
> Bob
> 
>> On Sep 20, 2015, at 9:06 PM, Nick Sayer via time-nuts  
>> wrote:
>> 
>> 
>>> On Sep 19, 2015, at 4:20 PM, Nick Sayer via time-nuts  
>>> wrote:
>>> […]
>>> I’ve tested it against GPS and as it came, it had about a 0.5 ppm error.
>> 
>> Oops. That was supposed to be 0.5 ppb - 500 ppt.
>> 
>> 
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> 

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Re: [time-nuts] time-nuts Digest, Vol 121, Issue 65

[EWKehren]

Hal there is not one straight answer, as mentioned before these units are  
intended for commercial applications with large temperature ranges. Most 
have  added frequency compensation using heater current sensing for C field  
adjustment or in the case of the FE  5680A DDS control. Looking close at  the 
5680 you can expect 4 E-11 per 1 C.
Bert Kehren
 
 
In a message dated 8/23/2014 9:42:15 P.M. Eastern Daylight Time,  
hmur...@megapathdsl.net writes:


kb...@n1k.org said:
 If you have a temperature stable  environment (or create one) you can get
 some very good results with an  (good) Rb locked to a (good) GPS via a 
proper
 long time constant  setup. It’s not easy, but it can be done. 

What's the temperature  sensitivity of the typical telco-surplus Rb unit?


-- 
These are  my opinions.  I hate  spam.



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Re: [time-nuts] EFC info on Trimble 34310-T OXCO

[EWKehren]

Charles 
I agree with every thing you wrote and I am implementing many of your  
recommendations. Forty years ago I bought a 15 foot Alu channel to make small  
frequency counter housings, always small, and at the time I did have access 
to a  machine shop so I made end plates. Still have five foot pieces now I 
cut then  off in 1 lb pieces and use them for tbolt, FE 405 B, FE 5650 and 
even a HP 10811  taken out of the can. As I said before am waiting for the 
small spheres and will  see what happens. Working on a GPSDO for the FE 5680A 
and the FE 405 B I did  find out the hard way what moving air will do. When AC 
season started my 405  tests showed the AC cycling it has a digital tuning 
resolution of 5.7 E-15.. The  nicely assembled packaged unit ended up in an 
other RS chassis with bubble  pack on each end reduced AC influence but you 
can still see it. If you like to  see some data contact me off list file is 
to large to post. Picture of my Alu  channel is attached.
Bert Kehren
 
 
 
In a message dated 8/23/2014 10:20:19 P.M. Eastern Daylight Time,  
csteinm...@yandex.com writes:

Ed  wrote:

I agree with your statement regarding the determination of  the 
optimum time constant, but, as Bob Camp mentioned, temperature  
change has a significant impact on setting the value.  My 'lab'  is a 
non-airconditioned bedroom.  My Tbolt doesn't have any  active 
temperature control.  If I set the time constant to the  point that 
Lady Heather thinks is optimum, I see large swings in PPS  offset 
when I open the window and the temperature changes by a few  degrees 
C.  If I leave the time constant at the default of 100  seconds, the 
swimgs are drastically reduced.  Active temperature  control is on my 
'round tuit' list.

Bert wrote:

As  to Ed's and Bob's comments our projects are not able to compete 
with  commercial products and I do not think that should be our 
goals.  Having spend extensive time on temperature control, I limit 
my self to  10 C and use fans on all Rb's and passive on OCXO's. 
Concern about  vibration induced noise on the  OCXO made me remove 
the fan on  the tbolt. Added a lot of mass and now ordered some foam 
balls from  China to fill the enclosure as some one recommended.

Well, yeah, it  goes without saying (or at least I thought it would) 
that one must keep  the rate of change of temperature of the OCXO low 
enough that its oven can  keep the crystal temperature within design 
bounds at all times.  I  just assume that any time nut would do this, 
since it is extremely simple  and costs next to nothing (look in the 
archives for my previous posts  about metal boxes, metal 
enclosures, and thermal capacitance in  connection with 
OCXOs).  Active temperature control is NOT  necessary.  Which is not 
to say it's a bad idea, it's just not  necessary to stabilize any OCXO 
worth owning by a time nut.  (I'm not  sure the MV-89 qualifies, even 
if you are lucky enough to get a good  one.  There has been some 
discussion on this list about the  temperature control loop being 
quasi-stable and tending to oscillate or  even latch under some conditions.)

I also see no reason why amateur  efforts cannot surpass the 
performance of commercial products,  particularly if we assume that 
the environmental conditions are limited to  those encountered in 
living space, not a radio shelter exposed to the  elements at a remote 
tower.  That is why I've been critical of  designs that aim only to do 
the best that can be done for $5, or the  best that can be done 
with a small ARM and 3 transistors.  Given  good design, there is no 
reason why an inexpensive DIY GPSDO shouldn't  handily outperform a 
Thunderbolt (using the same OCXO), with two  conditions: (i) 
environmental conditions are limited to those encountered  in living 
space, and (ii) performance during holdover is  neglected.

The reasons why most DIY designs do not work as well as  commercial 
designs, even if they use OCXOs of equal quality, is that their  
designers evidently cannot design ADPLLs of sufficient performance to  
do justice to the OCXO.  (This includes implementing whatever means  
of phase comparison and sampling are chosen, the DSP loop filter,  
sawtooth correction, and the NCO or DAC/EFC design.)  Doing all of  
this right isn't particularly expensive, it just takes a designer who  
has the skills and is willing to devote the effort.  As a mentor once  
told me, Good thinking isn't any more expensive than bad  thinking.

Some of the performance gain would be in reducing the rate  of 
temperature change seen by the OCXO, either passively as I have  
advocated and described before, or actively.  The other main  
improvement would be setting the PLL crossover out where it belongs,  
which becomes possible when the rate of change of temperature is  
controlled.  Avoiding a few common mistakes would provide some  
additional performance gains.

While the foam peanuts, which I  mentioned in a previous post, are 
helpful in 

Re: [time-nuts] time-nuts Digest, Vol 121, Issue 65

[EWKehren]

Bob which Efratom are you talking about?
Bert
 
 
In a message dated 8/24/2014 6:33:12 P.M. Eastern Daylight Time,  
kb...@n1k.org writes:

Hi

It is not what is done in the Efratom Rb’s. Their pps  input is set up to 
get things on frequency / on time quickly. The assumption  is that you plug 
it into a pps to get it “right” and then take off on your  mission. That 
takes them into the short (for a Rb) time constant region.  

Bob

On Aug 24, 2014, at 5:56 PM, Brooke Clarke  bro...@pacific.net wrote:

 Hi Bob:
 
 I think  that's what's done in the SRS PRS10
  http://www.prc68.com/I/PRS10.shtml
 
 Have Fun,
 
  Brooke Clarke
 http://www.PRC68.com
  http://www.end2partygovernment.com/2012Issues.html
  http://www.prc68.com/I/DietNutrition.html
 
 Bob Camp  wrote:
 Hi
 
 If you lock an Rb to GPS, you  need / want / should do it with a *very* 
long time constant. Numbers in the  one day to several days range are 
commonly seen. If you lock it up with a  tighter (shorter time constant) loop, 
it 
will just wander around as it follows  the GPS input. That’s what would 
happen if you hook your Rb to your Trimble  and turn on the disciplining on the 
Rb. It will significantly degrade the  stability of the Rb.
 
 If you have a temperature stable  environment (or create one) you can 
get some very good results with an (good)  Rb locked to a (good) GPS via a 
proper long time constant setup. It’s not  easy, but it can be done.
 
 Bob
  
 
 On Aug 23, 2014, at 6:31 PM, Ed Palmer  ed_pal...@sasktel.net wrote:
 
 Hi  Dave,
 
 On 8/23/2014 3:51 PM, Dave M  wrote:
 Thanks for that suggestion, Ed.  After a bit  of reading in the X72 
Reference Guide, it appears that the X72 does have a  1PPS input.  That would 
be considerably easier than trying to interface  the Rb into the GPSDO.  
Still trying to understand what the manual is  telling me. Next thing is to 
determine if my unit has that option enabled  (firmware option).  That will be 
a chore for after the holiday... really  busy next week.
 
 What would that (1PPS  disciplining) do for me... in terms of 
maintaining the Rb frequency accurately  set?  Would it be as accurate as 
having the 
Rb disciplined via the EFC  input?
 It's kind of overkill, but by connecting the 1 PPS from  the NTBW50AA 
to the X72, the X72 will be disciplined to the 1 PPS so the  frequency will 
be accurate.  The question is how well will it be  disciplined, i.e. what 
will the Allen Deviation graph look like.  I have  a few X72 and SA-22c (X72's 
cousin), but none of them have that option.   I don't know of any published 
data on it.  Maybe you can tell us how well  it performs.
 
 In general, I just don't see the  point of disciplining a Rb standard 
to GPS.  I don't understand what will  be gained by doing it.  I have a 
Z3801A and a Tbolt plus a free-running  FRK as a house standard.  I 
occasionally 
compare the FRK to the Z3801A  but the drift is so low (~1e-12 per month 
over 9 months) that I see no reason  to link them.
 
 One exception that I recently  discussed on another forum was a guy who 
lives in a ground floor, north-facing  condo.  He might need to have a 
disciplined Rb standard due to poor GPS  visibility.
 
 Ed
  
 Thanks,
 Dave M
  
 
 Message:  5
 Date: Fri, 22 Aug 2014 16:19:45  -0600
 From: Ed Palmer  ed_pal...@sasktel.net
 To: Discussion of  precise time and frequency measurement
  time-nuts@febo.com
 Subject: Re: [time-nuts]  EFC info on Trimble 34310-T OXCO
 Message-ID:  53f7c201.5070...@sasktel.net
 Content-Type:  text/plain; charset=ISO-8859-1; format=flowed
  
 Have you checked your X72 to see if it has the 1 PPS  discipline
 option?
 That would  be a lot easier (and probably better) than your  proposed
 transplant.
  
 Ed
 
  On 8/22/2014 12:39 PM, Dave M wrote:
 Does anyone  have any info on the OXCO in the Nortel/Trimble
  NTBW50AA-17 GPSTM receiver?  The OXCO is labeled as Trimble  
34310-T.
 I see some Trimble 34310-T oscillators on  Ebay with pinouts labeled,
 but no other  info.
 
 Specifically,  I'd like to know the EFC characteristics for it.   I'm
 thinking of the possibility of pulling the  OXCO out of the GPSTM and
 subbing in a 10 MHz  Rubidium, and using the GPSTM to discipline the
  Rubidium.  My Rubidium is a Symmetricom X72, recently purchased.   
It
 seems to be working  well.
 Does anyone know the differences between the  three OXCOs used in the
 GPSTM receivers (T, T2  and Oak)?
 
 Thanks  for some insight,
 Dave M
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Re: [time-nuts] EFC info on Trimble 34310-T OXCO

[EWKehren]

Charles
I use double bobble pack inside the Alu channel and I always start out by  
monitoring the OCXO and make sure it is at least 10 C below the spec range. 
The  tbolt is center located and I use a combination of rubber mounts but 
suspended  that they sell for hard drives and squares of double bubble pack. 
Vibration and  thermal.
Bert Kehren
 
 
In a message dated 8/24/2014 8:26:02 P.M. Eastern Daylight Time,  
csteinm...@yandex.com writes:

Bert  wrote:

As I said before am waiting for the small spheres and will  see what 
happens.

Monitor carefully, as I suspect the spheres will pack  too tightly 
leaving too little airspace.  You could easily burn down  an OCXO if 
this proves to be the case and the oven control loop goes  
unstable.  I'd put a thermal sensor on the OCXO itself for  testing.

Even if it doesn't burn down, you could find that the oven  
performance is degraded by (i) instability or quasi-instability of 
the  oven controller, or (ii) too much thermal resistance (remember, 
you want  to add as little thermal resistance as possible).

On the other hand,  mounting the OCXO as centrally as possible inside 
the outer enclosure on  thermally non-conducting standoffs (teflon or 
nylon), with at least an  inch of air on all six sides, has proven to 
work extremely  well.

When I described using packing peanuts (or similar) to break up  the 
airflow, it was in the context of having already mounted the OCXO as  
centrally as possible inside the outer enclosure on thermally  
non-conducting standoffs with at least an inch of air on all six  
sides.  And as I said, I have not found the additional step necessary  
once you have done this.  It may even be  counterproductive.

Best  regards,

Charles



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Re: [time-nuts] Ublox neo-7M GPS

[EWKehren]

Sorry but I disagree. Having done extensive work with the M7 and M6 in  
connection with the with GPSDO work we are doing we have characterized the 
units  extensively.  First from what we can see the difference between a SSR-6T 
 
and a $ 16 M6 is that one has a TCXO and outputs sawtooth correction data 
but  uncorrected both are the same. 
Last year we did extensive work on Brooks GPSDO and it works well with  
uncorrected M12's and ublox $ 16 M6's.  With a Morion we got 1  E-12.
With a geometry shrink in the M7 silicon higher frequency is possible and  
also lower power. Ublox most likely wants lower power and higher  
performance but not necessarily lower sawtooth because those OEM's that  need 
it will 
get a version with sawtooth data. Basic engine is still the same.  Time nuts 
are not a big enough market.  Sawtooth is smaller compared to the  M6 doe 
to the higher clock frequency and it is safe to assume that when they  come 
out with a M8 it will even be less.
On the universal controller we have a GPS filter not correction on the  
input that does improve performance. 
I took a page out of Ulrich's work when I saw a picture of his GPSDO where  
he thermally isolated his M12. With the FE 5680 work I made the M12 part of 
the  Rb by mounting it with metal stand offs to the backplate of the Rb.It 
in turn is  temperature controlled.
In the case of my FE 405B work I actually placed the M6 inside the OCXO  
took the battery off. I think I have a picture if interested.
Not knowing that it can not be done I did what I call a GPS-PLL using a M7. 
 Attached  is the board layout on the right side is what we are presently  
using with the Morion, on the left is a version for 5 V OCXO's so Hams can 
use  12 Volt. The one on the right is driven by readily available parts for 
any Ham  and no adjustments. Total cost not counting GPS and OCXO below $ 10. 
We are  still fine tuning the filter but right out of the box we got 1 
E-10. This is for  Ham's not time nut standard. Data exceeds attachment 
limitations but any one can  contact me off list and I will send it. We 
destroyed 
the M7 have not figured out  how but a new one is on order and once testing is 
completed schematics will also  be available.  I have the bad habit layouts 
first documentation maybe  second. Frustrating for the team, but I am 
getting better. As I said before  mainly for Ham's and one of our Australian 
team 
member will roll it out to the  Ham community. But any body is free to use 
it I just think time nuts can do  better.
Bert Kehren
 
 
In a message dated 8/21/2014 1:30:50 A.M. Eastern Daylight Time,  
ed_pal...@sasktel.net writes:

Thanks,  Tony.  That's good info.

So now we've confirmed that the neo-7M  has an NCO and it appears that 
it's resolution is 20 ns.  The data  sheet shows the 'Accuracy of time 
pulse signal' is 30 ns RMS and 60 ns for  99%, but it isn't clear whether 
they're referring to jitter or error with  respect to GPS seconds.

The original question was whether the neo-7M  would make a good GPSDO.  
As we've seen, the answer is no.   Cheap, yes.  Good, no. Setting aside 
the NCO issue, the neo-7M isn't  a timing receiver, it's a navigation 
receiver.  That limits it's  performance in many ways.

Ublox sells timing receivers, but they're  still NCO-based.  They're also 
significantly more expensive than the  navigation receivers. One example 
is Synergy Systems' SSR-6Tr if it's  still available.  It was announced, 
and discussed on this list, in  2012 but it still isn't listed on their 
web site so I don't know what it's  status is. It's based on the LEA-6T 
timing receiver which has a spec for  the 1 PPS is 'within 15 ns to 
GPS/UTC (1 sigma)'.  That can be  further reduced with some extra work.

If the performance of an  NCO-based unit isn't enough, you might want to 
consider Jackson Labs  GPSTCXO which is a real GPSDO.  More expensive 
than the NCO-based  units, but you get what you pay for.

No, I'm not associated with  Synergy or Jackson labs.

So Graham, if you survived the firestorm  started by your simple 
question, are you any wiser?

Ed

On  8/20/2014 7:56 PM, Tony wrote:
 On 19/08/2014 16:11, Ed Palmer  wrote:
 Does anyone have a neo-7M and an HP 5371A or a 5372A  Analyzer?  Use 
 the Histogram Time Interval function to  measure a block of samples. 
 That will show the length of the  samples with a resolution of 200 
 ps.  That's what I did a  couple of years ago when I analyzed the 
 Navsync CW-12 with the  old and new firmware.

 FWIW, I just had a look at the timepulse  on a NEO-7M. I configured it 
 to 10MHz, 50:50 duty cycle when locked,  disabled when out of lock. I 
 don't have any of those Analyzers so I  used an HP 54615B digital 
 scope. The period of the majority of cycles  was 104ns with 'random' 
 cycles being 84ns. I did not observe any  other cycle periods. I don't 
 know how accurate the time measurements  are on the scope, but it looks 
 like the timing is derived from an  approx 

Re: [time-nuts] Ublox neo-7M GPS

[EWKehren]

Ed
We may be talking past each other I had problems with the statement that  
the basic M6 and M7 are not suitable for GPSDO's. They are not GPSDO's in 
them  self but great GPS engines even without saw tooth correction which is an  
impossibility since the data is not available. But as you observed as 
frequency  goes up saw tooth comes down. But with frequency power goes up 
reduced 
by  smaller chip geometry. For the majority of applications power is # 1 
concern. We  are a minority. Pure material cost of our universal controller is 
below $ 15 but  once you add paying some one for kitting, shipping and 
handling it is a  challenge to keep it below $ 50.
Having in the past spend excessively for toys I get more pleasure by  
looking for very low cost solutions at top performance. That is what we do as a 
 
team.
Bert Kehren
 
 
 
In a message dated 8/21/2014 11:34:53 A.M. Eastern Daylight Time,  
ed_pal...@sasktel.net writes:

Hi  Bert,

I don't think we have any fundamental disagreement here.   Maybe just a 
difference in emphasis.

On 8/21/2014 4:34 AM,  ewkeh...@aol.com wrote:
 Sorry but I disagree. Having done extensive  work with the M7 and M6 in
 connection with the with GPSDO work we are  doing we have characterized 
the
 units  extensively.  First  from what we can see the difference between a 
SSR-6T and a $ 16 M6 is that one  has a TCXO and outputs sawtooth 
correction data but uncorrected both are the  same.

I agree that uncorrected results will be basically the  same.  Note the 
specs I stated for the navigation receiver (30ns rms,  60ns max) vs. the 
timing receiver (15ns rms, 60ns max).  Not a  huge difference.  But, 
timing receivers do have features that can  improve performance over 
navigation receivers. Some that come to mind are  position hold mode, 
TRAIM, maintaining performance with only one satellite  locked, sawtooth 
correction, and precision survey.  I haven't dug  through the Ublox data 
sheets to see which ones they support.  Some  are only useful during 
degraded conditions so it might be difficult to  test their 
effectiveness.  Some are automatic while some, like  sawtooth correction, 
require extra work to take advantage of.

You  mentioned the TCXO in the timing receiver.  Ublox says that it helps  
with acquisition and maintenance of satellite lock, but I don't think it  
has any significant effect on the quality of the 1 PPS or the variable  
frequency which will still be limited by the timing resolution (i.e.  
period) of the TCXO.  Is that right?

 Last year we did  extensive work on Brooks GPSDO and it works well with
 uncorrected  M12's and ublox $ 16 M6's.  With a Morion we got 1  E-12.
  With a geometry shrink in the M7 silicon higher frequency is possible  
and
 also lower power. Ublox most likely wants lower power and  higher
 performance but not necessarily lower sawtooth because those  OEM's that  
need it will get a version with sawtooth data. Basic engine  is still the 
same.  Time nuts are not a big enough market.  Sawtooth  is smaller compared 
to the  M6 doe to the higher clock frequency and it  is safe to assume that 
when they  come out with a M8 it will even be  less.

I won't be surprised to find that sawtooth correction becomes  irrelevent 
due to higher clock speeds which results in small sawtooth  size.  The 
Navsync CW-12 has been around for some years now.  It  runs at 'up to 120 
MHz', whatever that means.  I've measured its' 1  PPS jitter as 4 or 5 ns 
(1 sigma) and about 20 to 25 ns max.  It  doesn't support sawtooth 
correction, but it hardly needs to.  I tied  it to an HP Z3817A GPSDO.  
That's not a typo.  It's a strange  beast that requires an external 1 PPS 
input.  It includes an E1938  oscillator.  The result was a 1 PPS jitter 
of  100 ps (1 sigma)  and  1 ns max.  That's better than my Z3801A or 
Tbolt. It might  be capable of even better performance.  There's a 
possibility that  the E1938 oscillator is noisier than it should be. I 
should repeat that  test with other GPS receivers to see if the output 
degrades due to the  higher jitter on the older receivers. Another 
project to add to the  list!

Higher clock speeds will also allow more processing.  I  don't know if 
that will allow improved performance or if the receivers  have already 
done everything that they can.

 On the universal  controller we have a GPS filter not correction on the
 input that does  improve performance.
 I took a page out of Ulrich's work when I saw a  picture of his GPSDO 
where
 he thermally isolated his M12. With the FE  5680 work I made the M12 part 
of
 the  Rb by mounting it with  metal stand offs to the backplate of the 
Rb.It
 in turn is   temperature controlled.
 In the case of my FE 405B work I actually  placed the M6 inside the OCXO
 took the battery off. I think I have a  picture if interested.

Yes, if you look in the manual for Jackson Lab's  GPSTCXO it says that 
shielding the board from drafts improves  performance.  You've taken that 

Re: [time-nuts] Ublox neo-7M GPS

[EWKehren]

Be patient as soon as we have finished rollout of the FE 5680A and FE 405 B 
 GPSDO  I will be off the list.
Bert Kehren
 
 
In a message dated 8/19/2014 9:31:50 P.M. Eastern Daylight Time,  
csteinm...@yandex.com writes:

Bert  wrote:

I guess time nuts like to talk about it but not fix  it.

Will you PLEASE quit beating this tired old drum?  All of us  know 
this is your opinion, although many of us have other explanations for  
the phenomena you think it explains.  We do not need you to repeat it  
every time you post, and it is offensive.

Best  regards,

Charles



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[time-nuts] DIY FE-5680A lobotomy (disable temp compensation)

[EWKehren]

There is no question that direct fan control in combination with a heat  
sink is the best solution and we use it on FRK and M 100 with proper thermal  
insulation we get 0.01 C on the back plate and better than 0.1 C on the 
front.  For us the FE 5680 A is not in that class so we looked for a solution 
that gives  us 0.1 C. 
The shape of the FE 5680 does not lend itself easily for fan cooling if you 
 want to mount it in a chassis horizontally, I did using two L shaped 
plates with  a back plate heat sink and fan. How ever few have access to metal 
work and it  gets quickly expensive. A picture is attached. I did extensive 
test with heat  pipes first with a power resistor on a Alu plate followed by 
tests with a FRS,  FE 5650 and FE 5680. You have to take in to consideration 
the function of the  heat pipe in other words set the temperature of the 
base plate above the boiling  point of the liquid. In my case 46 C was a good 
tradeoff between fan speed and  operating range of the fan. To much heat pipe 
can also be a problem. No question  a uprocessor controlled temperature 
control would be better, but till now  typical time nuts, all talk while we 
have working analog circuits and  boards.
If worried about temperature change across the unit it can not be totally  
be eliminated but if important enclose the unit totally in foam. Easy when 
you  use a heat pipe. I use a an 1/8 Alu base plate between the Rb and the 
heat pipe  so I can also tap threads in to it to hold the heat pipe and I did 
away with the  bottom plate of the FE 5680. Many options.
Bert Kehren
 
 
In a message dated 8/19/2014 3:02:49 A.M. Eastern Daylight Time,  
ed_pal...@sasktel.net writes:

Is a  heatpipe really appropriate for this application?  The heatpipe  
expects that the heat source wants to burn up and so there's lots of  
heat available to vaporize the liquid in the pipe.  It's not clear to  me 
whether that situation exists with these Rb standards.  My tests  with an 
FE-5680A showed a maximum temperature of about 62C without a  heatsink.  
That's far lower than a CPU or GPU.  Some of them run  at that 
temperature *with* the heatpipe.

I think that a  heatsink/fan (maybe from a video card) equipped with a 
PWM controller  might be a better fit.  Many of those combinations have a 
ducted fan  to provide better control of the airflow.  That would reduce 
the  effects of drafts and convection. One nuisance with using a video 
card  heatsink is that the back side typically has a raised area that 
contacts  the GPU.  For this application you'd have to have a flat back 
over  the entire heatsink.

Ed

On 8/18/2014 6:58 PM, Angus  wrote:
 On Fri, 04 Jul 2014 02:35:41 +0100, you  wrote:

 Hi Bert,

 I am thinking  about testing a heat pipe on a fan cooled setup I use.
 The first  temp controlled chassis I did used a peltier and works very
 well,  but was a lot more work to do and is much more power  hungry.

 The main problem I find is not the temp  controller itself, but rather
 the change in the temperature across  the chassis as the ambient
 changes. However good the temp  controller is, it only controls a
 single point, but other points  further away from the sensing
 thermistor can vary a  lot.
 I noticed you posted a picture of a heat pipe cooler a couple  of weeks
 ago - did you happen to compare the temperature across  the unit with
 direct fan cooling and the heat pipe cooler, or with  different heat
 pipes?

  Angus.

 I finally got around to playing with a couple of  laptop heat pipes,
 fixed to a 25x50x75mm block of aluminium which is  fixed to the 12mm
 thick baseplate.
 On a quick test of it, a  sensor near the end of the baseplate showed
 1.5-2x greater variation  with temperature compared with just having a
 fan blow directly onto  the baseplate.
 The oscillator also had to be allowed to run a few  degrees C hotter
 for the heatpipe coolers to work to the same max  ambient temp.

 One cooler had two heatpipes with about 12cm  between the aluminium
 block and the heatsink fins (cast in this case)  The other had a
 single, wider heat pipe with about 5cm between the  block and the
 heatsink (this time with a lot more fine  fins)

 The second cooler was rather more efficient, allowing a  extra degreee
 of cooling at the top end, but more problematic was that  it entered
 'bang-bang' mode with the analogue temperature controller  even sooner,
 and the temperature fluctuations there were greater. Both  were rather
 worse than with the fan just blowing onto the  baseplate.

 Using a PWM fan controller would help a good bit,  but getting more
 creative with a microcontroller would be better. That  way you can give
 the fan a minimum of a small kick every so often, and  vary the
 repetition rate as well as the duty cycle as more cooling is  needed.
 With feedback from the fan and even air temperature  monitoring, you
 could get a good idea of exactly how much cooling was  being applied.

 Another problem is that the 

Re: [time-nuts] Ublox neo-7M GPS

[EWKehren]

Knowing a litle bit about semiconductor production it is safe to assume  
that all 7M series divvices have the same chip and during production at ublox  
some features are disabled or enabled. The result is one mask set one chip 
run  and one inventory. 
I did see a recent announcement where a 7M can be used as a GPSDO one of  
the intended markets is micro cell sites.Will require an external XO.
In the meantime we have been playing with a $ 15 M7 ublox that can be  
programmed from 1 pps to 1 KHz and use it in a PLL. I call it a GPS PLL and is  
mainly intended for Ham's. Clark had years ago a similar circuits we have 
added  some mods. Using a Morion 89 we get better than 1 E-10 per second on 
first try..  There have been recent claims using 1000 seconds which is easy 
but this is per  second. Next steps are more fine tuning and lower cost XO's. 
Maybe even a  VCTCXO. As I said before intended for Ham's, field day, uwave 
and SDR. Not  really a time nut unit, but low cost off the shelf standard 
parts and no  adjustments all on a 5 X 5 cm board. With a Morion you have to 
start off with 15  V but there are OCXO's out there for 5 V. Ideal for 
fieldday 12 V.
Bert Kehren
 
 
 
In a message dated 8/19/2014 12:20:40 P.M. Eastern Daylight Time,  
coll...@navcanada.ca writes:

Good day  all,

On another list to which I subscribe, there has been chatter about  the 
Ublox neo-7M GPS receiver. It seems that the device's configurable  timepulse 
output is configurable from 0.25hz to 10 MHz as well as it's duty  cycle and 
can also be set to be one condition when the GPS is not locked and a  
different condition when locked (i.e. 1 PPS if not locked, 10KHz when  locked).

This seems all too good to be true. Sounds like a very simple  
self-contained GPSDO.

I don't know anything more about the device. I  have just downloaded the 
documents and will be spending some time reading  them.

I am curious if any other list members were aware of this feature  of this 
device and have had any first hand experiences with it.

There  is another model, the 7N. the 7M uses a simple crystal clock, the 7N 
a  TXCO.

Cheers, Graham ve3gtc


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Re: [time-nuts] Ublox neo-7M GPS

[EWKehren]

I recall when the LEA-M8F was announced that they mentioned a VCTCXO and  
maybe I wrongly assumed that they used it for sawtooth correction they also  
mention ability to control in addition an external OCXO. I previously 
suggested  using saw tooth correction information to tune a TCXO but that would 
require a  GPS module with sawtooth information and than it would be simpler 
to just use a  PIC and delay chip. Still do not understand why no one took me 
up on the offer  of chips and PCB. I guess time nuts like to talk about it 
but not fix it. How  many receivers are out there.
Bert Kehren.
 
 
In a message dated 8/19/2014 5:51:30 P.M. Eastern Daylight Time,  
kb...@n1k.org writes:

Hi

They are constrained by the same basic TCXO issues that  give you sawtooth 
correction. They do not use EFC to get the TCXO on  frequency. With sawtooth 
they give you a word that lets you know what’s going  on. With the NCO’s 
they often are doing very crude synthesis. They don’t put a  $48 DDS chip in 
a $10 GPS module. If you put one on a spectrum analyzer, it’s  not pretty ….

Bob

On Aug 19, 2014, at 5:46 PM, Said Jackson  saidj...@aol.com wrote:

 Tom,
 
 Btw part of  my frustration with this is that we sometimes get calls from 
customers asking  why they need our or others' GPSDOs for a couple 100 
dollars when they can buy  a CW or uBlox doing the same thing for a fraction 
of the cost.
  
 Most of them come back to us after evaluating these NCOs and finding  
that its not the same thing.
 
 You get what you pay for I  guess..
 
 Said
 
 Sent From iPhone
  
 On Aug 19, 2014, at 13:01, Tom Van Baak (lab)  t...@leapsecond.com 
wrote:
 
 Hal, as long as you  maintain long-term phase lock it's a disciplined 
oscillator. So, yes, a  carrier tracking WWVB receiver with sufficiently 
stable flywheel LO is a  WWVBDO.
 
 Said, too-short or too-long 100 ns cycles is  one thing. Still ok for 
many applications. But tell me more about extra or  missing pulses in the 
ublox-7. That sounds like a show stopper to  me.
 
 /tvb (i5s)
 
 On Aug  19, 2014, at 2:05 PM, Hal Murray hmur...@megapathdsl.net  
wrote:
 
 
 saidj...@aol.com  said:
 its not a GPSDO though, not even a simple one  :)
 It does not discipline an oscillator. It generates the  output by
 mathematically calculating how many phases it  has to add/drop in a 
second,
 then   digitally  adds/drops/extends/retards the phase of the output 
clock  to
 achieve an average of number of desired clock  cycles.
 
 Is there something about the term  GPSDO that says I have to do the D 
in the 
 analog domain  rather than the digital domain?
 
 I agree that  current technology doesn't give results that are useful 
for many  
 applications that currently use GPSDOs.  What if the  clock ran at a 
GHz?  10 
 GHz?  Sure, it would have  spurs, but would it be useful for some 
applications?
  
 Is a GPSDO still a GPSDO if the D/A driving the VCXO only has  a few 
bits?  
 How many bits does it need to be a real  GPSDO?
 
 Is a battery powered wall clock  listening to WWVB at 2 AM a WWVDO?  
It's got 
 a pretty  good ADEV if you go out far enough.
 
 --  
 These are my opinions.  I hate spam.
  
 
 
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[time-nuts] Mc Coy OCXO in HP equipment.

[EWKehren]

I am presently downsizing and that has also resulted in shrinking my HP 70  
000 series spectrum analyzer. Out with the 70310A OCXO reference. The unit 
has a  McCoy OSC92-13B OCXO. The original price was $ 5000 and the option 
with out OCXO  was a $ 2500 saving. Some OCXO. Does any one have any 
information on the unit  and is it used in other equipment. 
Thank you   Bert Kehren
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Re: [time-nuts] Lamp for FRK Rubidium Needed

[EWKehren]

Having had more than ten FRK's and M100's on my bench and once locked none  
where as low as any thing in E-9.  What you should buy is a ubox for $ 16  
shipping included and you will with your counter be able to get better than 
1  E-9 for testing.
Bert Kehren
 
 
In a message dated 8/10/2014 2:30:50 P.M. Eastern Daylight Time,  
ed_pal...@sasktel.net writes:

How did  you make the measurement that showed a 0.8 Hz difference? What 
are the  specs on your Racal reference?  When was it calibrated and 
against  what standard?  That will tell you how much confidence to put in 
it's  frequency.

As others have said, an FRK isn't a primary standard and  should be 
calibrated against a primary standard.  However, 0.8 Hz is  an error of 
8e-8.  I don't believe it's possible for a Rb standard to  lock and be 
that far off.

From your web site you seem to have quite  an assortment of HF radios.  
Do any of them have enough resolution to  do a quick check by using one 
of them as a transfer standard? Measure a  known-accurate radio station 
frequency and then measure both the Racal and  the FRK.

Ed

On 8/10/2014 4:01 AM, Peter wrote:

  Thanks to the help from members here I now have a locking FRK.

  My bulb looked pretty clear, and i couldnt find any deposits or bits
  inside, but decided to give it a good soaking at about 150 deg C using  
my
 hot air re-work gun for about 10 mins.

 I have  checked it against my Racal ovened reference and found a 
discrepancy
  of about 0.8 Hz.

 Now the million dollar question...Can I be  sure the FRK is good before I
 start to use it as my standard  frequency?

 Is the FRK constructed in such a way that the  frequency accuracy is 
assured,
 or do I need some way of verifying the  FRK, or calibrating it.

 I dont want to trim my ovened  reference to the rubidium, only to find the
 rubidium is not as  accurate as I thought?

 Sorry if dumb questions, but just  starting my quest for time nut 
status!!!

  Thanks

 Peter
  G0RSQ
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Re: [time-nuts] temperature sensor

[EWKehren]

Hi Tom
I agre the educational aspect of time nuts is great and I have learned a  
lot but it would be even more useful if discussions include what can be 
attained  and what may be in the reach of time nuts. I used to have a HP 2804A 
with  matched probe prom only used it once when developing a super efficient 
boat air  condition system running on batteries. After that used it to sort 
of calibrate  my YSI probes and sold the unit. I do not think I need any 
accuracy better than  0.1 C and feel comfortable having it. But if time nuts 
find a way to get an  affordable solution I would get one.
We use fan speed temperature control and at one time I did use it on a  
Tbolt. May revisit it discarded it because of my concern of fan noise  
transferring to the XTAL in the OCXO. 
We use it successfully with NTC embedded in the base plate of FRK's and  
using a separate sensor see 0.01C. Also use heat pipes. In all cases we use  
voltage control do to my lack of PIC programming experience. In our work the  
OCXO is not in the Rb  but Rb , fan and OCXO all have vibration isolation.  
The challenge is reliable fan start at low voltage if you want the unit  
stay constant over an ambient change of 10 C. Members have talked about u  
processor control but I have not seen any thing that works, many of the heat  
pipes used in laptop do have digital speed control, some one please step up 
to  the plate.
Back to the Tbolt it is tempting but right now I have to many things on my  
plate. I suggest controlling temperature in an enclosure within 0.1 C along 
with  added mass to the unit, reduce other heat sources in the unit. An 
other approach  would be a heat pipe again more thermal mass and all sides with 
thermal  isolation to reduce ambient temperature. influence. I have an 
analog fan conrtol  board and the plan is to make one available for those that 
buy a FE 5680A kit.  Again maybe some one steps to the plate and designs a 
digital control.
Bert Kehren
 
 
In a message dated 7/21/2014 3:17:16 A.M. Eastern Daylight Time,  
t...@leapsecond.com writes:

 What I am  missing in all these discussions is what do we want to  
archive 
  or is this an other paper only  discussion. I am used to  starting  out 
with a 
 goal, and tackle the challenge from there.
 We have  a saying in German Papier ist geduldig.  Translate You  can 
write  
 any thing on paper.  
 Bert Kehren

Hi  Bert,

Let me answer in two parts.

1) The issue of precision  temperature sensing is so key to the field of 
precise time  frequency  that any thread that attracts more information, 
anecdotes, and wisdom from the  group is very welcome. Quartz is such an 
amazing 
substance that its use as a  precision sensor is every bit as interesting 
as its use as a precision  timekeeper.

Not everything has to be goal oriented. Some discussions on  this list are 
pure enjoyment, others highly educational, and some simply plant  seeds. 
Starting with concrete goals is good for a business but when working  with 
precision timing as a hobby, as most of us are, goals are sometimes  secondary 
to just learning or playing around.

2) If you want an example  of a specific goal related to temperature, try 
this:

There have been  several discussions over the years about variable fan 
speed based temperature  control. I can't explain it, but I've always been 
suspicious of this  technique. It seems to me still air is inherently better 
than 
moving air.  Passive (no fan) is better than active (fan). And constant 
velocity is better  than turbulence is better than variable velocity. But I 
don't know for sure.  That's where experiments and measurement come in.

To satisfy my  curiosity and get actual data I'd like to place 6 or more 
tiny analog  high-resolution temperature sensors all around the OCXO of a 
Trimble  Thunderbolt. That's high-resolution both in temperature and in time. 
In 
other  words, no fake accuracy averaging allowed. The goal is to observe 
thermal  gradients in real-time and see how good, or how bad, the 
correlation is among  crystal temperature, case temperature, and DS1620 
temperature 
sensor (which is  mounted a considerable distance from the OCXO). The same 
technique, and maybe  even the same conclusions, might apply to  Rb.

/tvb

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Re: [time-nuts] temperature sensor

[EWKehren]

Slow is not a problem in our applications the loop takes care of that. Will 
 look in to PT 100.
Bert Kehren
 
 
In a message dated 7/21/2014 8:19:48 A.M. Eastern Daylight Time,  
alex...@ieee.org writes:

NTC are  not that very stable, they are amorphous material winch could  
recrystallize slowly and therefore change it's electrical behavior ,  
PT100 style is more reliable since it is pure  metal
73
Alex

On 7/21/2014 1:22 AM, Attila Kinali wrote:
  On Sun, 20 Jul 2014 23:18:38 -0700
 Tom Van Baak  t...@leapsecond.com wrote:

 To satisfy my curiosity  and get actual data I'd like to place 6 or more
 tiny analog  high-resolution temperature sensors all around the OCXO of a
  Trimble Thunderbolt. That's high-resolution both in temperature and in  
time.
 In other words, no fake accuracy averaging allowed. The  goal is to 
observe
 thermal gradients in real-time and see how  good, or how bad, the 
correlation
 is among crystal temperature,  case temperature, and DS1620 temperature
 sensor (which is mounted  a considerable distance from the OCXO). The 
same
 technique, and  maybe even the same conclusions, might apply to Rb.
 May i ask what  speaks about using PT100/PT1000 or NTCs?

 NTCs are dirt cheap,  but might need some calibration first, to
 get to time-nuts standards.  But PT100 aren't that much more expensive
 either.

  eg:
 The NTCALUG03 by Vishay don't look too bad, or if you want  PT100
 the M310 by Heraeus. The KN1510 by Heraeus look also nice, but  are
 a tad bit more expensive (about 20USD/pcs)


  Attila  Kinali


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Re: [time-nuts] temperature sensor

[EWKehren]

Thank you Charles
. As a first step I will fill one of my Tbolt boxes with small foam  
particles. Sounds like a good idea. I have one unit where I have given  
particular 
attention to low power from the power supply. 
Bert Kehren
 
 
In a message dated 7/21/2014 7:43:49 P.M. Eastern Daylight Time,  
csteinm...@yandex.com writes:

Tom  wrote:

There have been several discussions over the years about  variable 
fan speed based temperature control. I can't explain it, but  I've 
always been suspicious of this technique. It seems to me still  air 
is inherently better than moving air. Passive (no fan) is better  
than active (fan). And constant velocity is better than turbulence  
is better than variable velocity. But I don't know for  sure.

There is no such thing as still air, unless there is no  temperature 
gradient.  If there is any temperature gradient  (typically due to 
power dissipation), there will be convection  currents.  In a closed 
space (for example, internal to a TBolt or in  a sealed box that 
encloses a TBolt), these convection currents will set up  a flow 
pattern that may be benign or malicious with respect to keeping a  
particular part of the device at a constant temperature.  If the part  
you are particularly interested in is a creator of thermal gradients  
(as the OCXO in a TBolt is), analyzing this gets very complicated very  
fast.

Fans (speaking here of fans that circulate air internal to a  closed 
volume, not fans that exchange air between the inside and outside  of 
a volume) tend to mix up the air and reduce thermal gradients.   Then, 
the question becomes whether the circulation due to the fan has a  
patterned or a random thermal flow.  Typically, a random (diffused)  
pattern is best -- but it is relatively hard to achieve.  With  
careful design, active circulation is usually better than passive  
convection.  However, careful design is not easy.  Also, fans  raise 
a concern about vibration, which is a real worry with any precision  
oscillator.

One other possibility is to use passive techniques to  randomize (more 
or less) the passive convection.  This can be  achieved (to a degree) 
by filling the internal volume with low-density,  very porous 
insulation.  On a larger scale, a sealed box of, say, 2  cubic feet 
can be filled with common packing peanuts and the isolated  object 
placed in the middle.  Air will still circulate by convection,  but in 
a more random manner.  (There will also be less bulk  circulation, so 
the thermal gradient will be somewhat larger than  before.)  Applied 
to a TBolt, one might fill the inside of the TBolt  itself with 
smaller pieces of styrofoam (irregular shapes perhaps 6 or 7mm  in 
size).  [Spheres (styrofoam beads) may pack a bit too tightly for  
this, impeding airflow more than desired.]  The same can be done for  
a sealed box that encloses a TBolt or other oscillator.  I have  
achieved very good results with this method, when properly  applied.

I have done a fair amount of experimenting with and without  fans (but 
one must recognize that there are so many variables, even a lot  of 
experimenting really only scratches the surface), and have always  
found that passive circulation (within sealed volumes) works very 
well  when the object ultimately being controlled is an ovenized  
oscillator.  For tight control, which is needed for precision voltage  
references, DAQ circuits, and other precision process-control  
applications, I do use a thermostatically operated fan to exchange 
air  between the outermost sealed volume and ambient -- but even this 
I usually  find unnecessary if the ultimate object is minimizing the 
frequency drift  of an ovenized oscillator.

Finally, re.: fan control.  For a  brushless DC fan to run slowly, you 
need to feed it full voltage with  pulse-width modulation 
(PWM).  Even then, they will not run all  that slowly.  The 
Microchip TC642B fan controller (8 pin IC, about  $1.20) is a very 
handy part when you need a wide range of fan  speeds.  It uses 
commutation noise to sense fan rotation, and has a  stall routine 
that gives the fan a kick if it stalls (NB: this is a  feature of the 
642B, absent on the 642).  So, not only will it run  the fan at its 
lowest possible self-sustaining speed, you can also run the  fan much 
slower than its self-sustaining speed by letting it stall and be  
restarted periodically.  The fan looks like a windmill with three  
sheets to the wind below its self-sustaining speed, but it works  
extremely well and this operation does not damage the fan or the  
controller.

Best  regards,

Charles



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Re: [time-nuts] temperature sensor

[EWKehren]

What I am missing in all these discussions is what do we want to  archive 
or is this an other paper only  discussion. I am used to  starting out with a 
goal, and tackle the challenge from there.
We have a saying in German Papier ist geduldig.  Translate You  can write 
any thing on paper.  
Bert Kehren
 
 
In a message dated 7/20/2014 12:39:24 P.M. Eastern Daylight Time,  
att...@kinali.ch writes:

Moin,

On  Sun, 20 Jul 2014 07:55:23 -0700
Tom Van Baak t...@leapsecond.com  wrote:

 Thanks for this level of detail. Fascinating. Is the  fundamental physics
 behind the quartz angle-of-cut well understood, or  does this fall into
 advanced alchemy and industrial magic?

From  what i gathered from my excursion into solid state phyiscs, the
properties  of crystals can be calculated easily. If i'm not mistaken
the SC cut was  calculated before it was experimentally proven (sorry,
cannot find the  reference for that).

There are also several software packages to  simulate quartz crystals.
(e.g. CS-01 from maxis-01)


 I  understand about the time constant now. Yes, on the order of a
 few  seconds makes sense. Would it be possible to have other mounting
  techniques that improve environmental contact with the crystal?

The  problem here is, that any closer contact will lead to damping
of the  crystal. Probably the best solution is, as Bob Camp said,
to use SAW  instead of BAW.

 Do you know of any commercial quartz crystals  (say, in the $1 to $10 
range)
 that have been optimized for large  tempco at room temperature? Or 
optimized
 for linearity over a large  range (e.g., -40 to +40 C)?

As Bernd Neubig mentioned, Axtal has  some:
http://www.axtal.com/English/Products/PiezoSensors/TemperatureSensors/

As  none of the usual distributors carries them, i have no idea what
the price  is. Maybe Bernd can answer that question.

I'm pretty sure other quartz  manufacturers have some as well.

 I was able to test
 one  once, a 5x7mm XO, but I don't know any more about it other than it  
came
 from Switzerland.

Hmm... The only quartz manufacturer in  Switzerland that is still producing
anything, is AFAIK Microcrystal. I'm  not aware of any other (after 
Oscilloquartz got bought and their quartz  business integrated into 
Microcrystal).

Unless you got it over Quarz AG  (www.quarz.ch) which is merly a 
distributor.
(Yes, they sell beauty  products too... )

BTW: for some reason, i did not get the two mails  from Andras Pummer
which you quoted at the end of your mail. They don't  seem to be in
the archives either.

Attila Kinali


-- 
I pity people who can't find  laughter or at least some bit of amusement in
the little doings of the day.  I believe I could find something ridiculous
even in the saddest moment, if  necessary. It has nothing to do with being
superficial. It's a matter of  joy in life.
-- Sophie  Scholl
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Re: [time-nuts] sine to square wave converter

[EWKehren]

Bruce, 
please make those tests it will help me to how to proceed and probably many 
 other time nuts.
Bert Kehren
 
 
In a message dated 7/11/2014 3:50:36 A.M. Eastern Daylight Time,  
br...@ko4bb.com writes:

The  Achilles heel of that biasing technique is that the emitter currents 
of  the
pair of pnp's is affected by the noise on the 20V supply.
The 20V  supply noise is only attenuated by a factor of 5 or so when  both
transistors have equal collector currents.

I have both an LTC  evaluation board for the LTC6957 and a Holzworth sine 
to CMOS
converter as  well as a Timepod so I could measure the phase noise of both 
of
these for  various 10MHz input signal levels.

Bruce

 On July 10, 2014  at 8:21 PM Charles Steinmetz csteinm...@yandex.com  
wrote:


 Bruce wrote:

 Currently  Linear Technology's sine to square wave devices with 
selectable
  filtering (LTC6957 series) are better in that they are a closer
  approximation to
 the ideal zero crossing detector.
  Failing that the next best is perhaps an AC coupled (both at input
  and between
 emitters) differential pair of 2N3906's or  similar.

 My initial results with the LTC6957 did not produce  lower phase noise
 at 10MHz than an optimized Wenzel two-PNP circuit  (it may be possible
 to do better than my initial experiments with the  6957).

 Here is the circuit I use:

  Emacs!


 Using a 20v supply reduces the input  feedthrough due to Q1's B-E
 capacitance, which tends to give the  output square wave a sloping top.

 Using MPSH81s rather than  2N3906s helps with feedthrough, also, as
 well as reducing the rise and  fall times (both about 2-4 nS with this
 circuit, depending on how hard  it is driven, if it is built with
 proper attention to layout and stray  capacitance).

 Some will insist that the LM329 is overkill, but  the base bias can be
 a significant source (even the dominant source)  of phase
 noise/jitter. The stability and low noise of the 329  improve
 performance materially -- even a TL431 or 1N829 is  measurably
 inferior. An LM399 is somewhat better than the 329, but I  have not
 found it necessary in practice. (Note that the pullup  resistor is
 not shown -- 1.5k to 10k metal film from the 329 to +20v,  not critical.)

 Some additional improvement can be achieved by  using the PNP devices
 in an HFA3096 or HFA3128 array, but I have  generally not seen the
 need for this in practic. As drawn, this  circuit has lower residual
 PN than any 10MHz oscillator I have  measured.

 Works best with input levels from 1 to 10Vpp (350mV  to 3.5Vrms sine
 wave). There is a small duty cycle asymmetry (high  longer than low),
 which depends on drive level. Using faster devices  (such as HFA3096
 or HFA3128) reduces the asymmetry. If this is a  problem, a resistor
 can be added from the base of Q1 to ground to trim  out the asymmetry
 if the input level is well controlled. Otherwise,  the mean output
 voltage can be detected, compared to a reference, and  used to adjust
 either base voltage with a servo loop.

  Best regards,

 Charles


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[time-nuts] sine to square wave converter

[EWKehren]

As part of the FE 405 B project a separate output circuit is in the works.  
The universal controller and auxiliary board are the same as used in the 
FE5680A  GPSDO but because of the very low ADEV a separate circuit board that 
divides by  three and has also two ground isolated transformer outputs is in 
the works.The  question is what is the best sine to square wave converter 
with the lowest ADEV  contribution. I am looking at Bruce's circuit using the 
ADCMP600. Any other  ideas?
Thanks   Bert Kehren
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[time-nuts] FE 5680A disciplined controller

[EWKehren]

The development phase of the FE 5680A disciplined controller is nearing  
its completion in no small part thanks to Scott's work on frequency/  
temperature control. As I have pointed out in the past we have no plans to use  
the 
5680 so Juerg  is considering selling his FE5680A along with controller  and 
auxiliary assembled and tested.. If some one in Europe preferable in  
Switzerland is interested please contact Juerg off list   _j.koegel@bluewin.ch_ 
(mailto:j.koe...@bluewin.ch) . Would also help with  independent test before 
roll out.
Nert Kehren
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Re: [time-nuts] sine to square wave converter

[ewkehren]

Thank you Alex I have that info I am concerned about rise time
Bert Kehren




Sent from Samsung tabletAlexander Pummer alex...@ieee.org wrote:
look Charles Wenzel's waveform conversion: 
http://www.wenzel.com/documents/waveform.html
73
Alex

On 7/10/2014 11:40 AM, br...@ko4bb.com wrote:
 On July 10, 2014 at 10:55 AM ewkeh...@aol.com wrote:


 As part of the FE 405 B project a separate output circuit is in the works.
 The universal controller and auxiliary board are the same as used in the
 FE5680A GPSDO but because of the very low ADEV a separate circuit board that
 divides by three and has also two ground isolated transformer outputs is in
 the works.The question is what is the best sine to square wave converter
 with the lowest ADEV contribution. I am looking at Bruce's circuit using the
 ADCMP600. Any other ideas?
 Thanks Bert Kehren
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 Although  CERN likes that circuit for its ruggedness and versatility its a
 little noisier than some alternative circuits.

 Currently Linear Technology's sine to square wave devices with selectable
 filtering (LTC6957 series) are better in that they are a closer approximation 
 to
 the ideal zero crossing detector.
 Failing that the next best is perhaps an AC coupled  (both at input and 
 between
 emitters) differential pair of 2N3906's or similar.

 Bruce
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Re: [time-nuts] sine to square wave converter

[EWKehren]

Magnus
Thank you for your recommendation I use Wenzel extensively as a matter of  
fact I just completed in the last three days two boards that have Wenzel on 
it  and in my projects I can count 14 boards. Rise and fall time is my 
concern but I  am open to suggestions that is why I turned to the list looking 
for the  best.
Thanks again   Bert Kehren
 
 
In a message dated 7/10/2014 3:09:52 P.M. Eastern Daylight Time,  
mag...@rubidium.dyndns.org writes:

Bert,

On  07/10/2014 04:55 PM, ewkeh...@aol.com wrote:
 As part of the FE 405 B  project a separate output circuit is in the 
works.
 The universal  controller and auxiliary board are the same as used in the
  FE5680A  GPSDO but because of the very low ADEV a separate circuit board 
 that
 divides by  three and has also two ground isolated  transformer outputs 
is in
 the works.The  question is what is the  best sine to square wave converter
 with the lowest ADEV   contribution. I am looking at Bruce's circuit 
using the
 ADCMP600. Any  other  ideas?

Do look at the Wenzel clockshaper [1], look at the  TADD-2 [2] schematic. 
It's a PNP long-tail pair. The strategy is to  provide modest gain. A 
known strategy to reduce 1/f noise and to some  degree thermal 
differences is naturally feedback, as you will find in the  NIST papers.
Once you have the slew-rate up, going in for the kill with a  straight 
comparator should give you all the nice output slew-rate you can  wish for.

Thus, this is not all that different to the mixer-setup you  have done.

I have modified my TADD-2 such that one of the output  channels is fed 
from the input circuit, and this provides me with a  squared up version. 
For a counter such as DTS-2070C, the difference is  significant, which 
helps to show the potential of this simple  design.

I think the basic approach can be improved, and how far one has  to go 
depends on how clean source you have. You end up with interesting  
measurement problems.

An indirect way to measure the goodness of a  squarer is to insert some 
known sine disturbance at say 30 or 40 dB below  the signal. A straight 
comparator won't work very well. Be careful with  selectivity of LC, as 
it is a nice way to become temperature dependent, so  low-Q solutions is 
needed.

Cheers,
Magnus

[1]  http://www.wenzel.com/documents/waveform.html
[2]  https://www.tapr.org/kits_tadd-2.html
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Re: [time-nuts] sine to square wave converter

[EWKehren]

Will the added stage negatively effect ADEV?
Bert
 
 
In a message dated 7/10/2014 3:48:44 P.M. Eastern Daylight Time,  
mag...@rubidium.dyndns.org writes:

Bert,

OK, good that you are familiar with it, it was not  obvious in that message.

If you consider it as the first stage, and  that you then can put another 
(faster) stage after it until you go for  comparator. It's just the same 
thing as the multistage for beat-note, but  you run at a higher 
frequency. That way you should increase your slew-rate  step-wise.

Cheers,
Magnus

On 07/10/2014 09:37 PM,  ewkeh...@aol.com wrote:
 Magnus
 Thank you for your  recommendation I use Wenzel extensively as a matter of
 fact I just  completed in the last three days two boards that have Wenzel 
on
  it  and in my projects I can count 14 boards. Rise and fall time is  my
 concern but I  am open to suggestions that is why I turned to  the list 
looking
 for the  best.
 Thanks againBert Kehren


 In a message dated 7/10/2014 3:09:52 P.M.  Eastern Daylight Time,
 mag...@rubidium.dyndns.org  writes:

 Bert,

 On  07/10/2014 04:55 PM,  ewkeh...@aol.com wrote:
 As part of the FE 405 B  project a  separate output circuit is in the
 works.
 The  universal  controller and auxiliary board are the same as used in  
the
   FE5680A  GPSDO but because of the very low  ADEV a separate circuit 
board
   that
 divides  by  three and has also two ground isolated  transformer  outputs
 is in
 the works.The  question is what is  the  best sine to square wave 
converter
 with the lowest  ADEV   contribution. I am looking at Bruce's circuit
 using  the
 ADCMP600. Any  other  ideas?

 Do look  at the Wenzel clockshaper [1], look at the  TADD-2 [2] schematic.
  It's a PNP long-tail pair. The strategy is to  provide modest gain.  A
 known strategy to reduce 1/f noise and to some  degree  thermal
 differences is naturally feedback, as you will find in  the  NIST papers.
 Once you have the slew-rate up, going in for  the kill with a  straight
 comparator should give you all the nice  output slew-rate you can  wish 
for.

 Thus, this is not all  that different to the mixer-setup you  have done.

 I have  modified my TADD-2 such that one of the output  channels is fed
  from the input circuit, and this provides me with a  squared up  version.
 For a counter such as DTS-2070C, the difference is   significant, which
 helps to show the potential of this simple   design.

 I think the basic approach can be improved, and how  far one has  to go
 depends on how clean source you have. You  end up with interesting
 measurement problems.

 An  indirect way to measure the goodness of a  squarer is to insert  some
 known sine disturbance at say 30 or 40 dB below  the signal.  A straight
 comparator won't work very well. Be careful with   selectivity of LC, as
 it is a nice way to become temperature  dependent, so  low-Q solutions is
 needed.

  Cheers,
 Magnus

 [1]   http://www.wenzel.com/documents/waveform.html
 [2]   https://www.tapr.org/kits_tadd-2.html
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Re: [time-nuts] Interesting frequency standard project

[EWKehren]

In the seventies I did for some friends that had FCC First class licenses a 
 counter that on the input had three J/K F/F's to subtract the IF from the 
LO.  They modified receivers including running the IF in to saturation and 
they  certified stations without going there.. I think measurements had to be 
done on  a monthly basis. Since they where also HAM's they also used them 
on frequency  contests.
Bert Kehren
 
 
In a message dated 7/5/2014 12:56:24 P.M. Eastern Daylight Time,  
alw.k...@gmail.com writes:

As stated AM stations in US must maintain 20 Hz accuracy. Most are well  
within that tolerance. I have measured many AM station's frequency as a  
function of my employment before retirement.

Now  comes HD radio. While the merits of HD AM radio are very much open 
to  debate, one benefit is that the equipment for HD is GPS locked. If you 
can  find an HD AM station you can probably bet they are very close to 
being 
on  frequency. The ones I have measured have been right on and push the 
limits  of my test equipment.

Al, retired, mostly
AKA k9si


  Date: Sat, 05 Jul 2014 06:20:36 -0400
 From: Dale H. Cook  starc...@plymouthcolony.net
 To: time-nuts@febo.com
  Subject: Re: [time-nuts] Interesting frequency standard  project

 At 06:27 PM 7/4/2014, Hal Murray  wrote:

... we have no requirement for that level of  stability on the MW 
broadcasts.

How  stable are they?

 That varies greatly from station to station  depending upon what 
 transmitter they are running. Note also that  compliance with the 20 Hz 
 accuracy requirement varies so you would  only want to use stations owned 
 by companies with a good record of  compliance with Part 73.

 Dale H. Cook, Contract Engineer,  Roanoke/Lynchburg, VA
  http://plymouthcolony.net/starcityeng/index.html

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Re: [time-nuts] DIY FE-5680A lobotomy (disable temp compensation)

[EWKehren]

Good Morning Angus
Let me start out by saying the FE5680A project was intended for time nuts  
and the unit will not be part of our bench, so the work on it is limited. As 
far  as Rb's are concerned our focus is on FRK and HP5065. Looking back I 
would most  likely not suggested it, had I known how much time it took up. 
How ever it also  made us take an other look at Rb control, switching from 
analog to digital and  resulted in looking at the FE 405 B. So it is worth it.
Using heat pipe for the FE 5680 was the outcome of many test with heat  
sinks and other heat pipes. The big advantage of the heat pipe is the ease of  
removing the heat but it also has its limitation. Its biggest limitation is 
the  fact that it works on the principle of converting a liquid to a vapor a 
process  that takes a lot of heat. so you can not expect it to bring the 
temperature down  to 20 degrees. And to much heat pipe is not good either. In 
the one you see in  the picture I may have to deactivate one of the pipes. 
The ALU p;ate is 3/16  and the LM335 is on the back. I took out the bottom 
plate of the 5680 and  between the two mounting holes of the ALU spine is 
plenty of room to install a  SMD version of the 335. Temperature is 40C but not 
that critical but range is  limited by the function of a heat pipe.
You may want to experiment and if you are going to do some serious work  
contact me off list, not secrets, but the pictures can not be attached on this 
 list because of file size limitation.
When I first got the 5680 I did a crude temperature control using a fan a  
heat sink from an ATT Rb a LM335 along with a bang bang op amp circuit. I  
previously published picture and schematic. Temperature stability was better  
than 0.1 C. We have done extensive work on controlling the back plate  
temperature of a FRK and now get 0.01 C. We learned a lot and I like to share 
it 
 since it will also apply to the heat pipe. The biggest problem is the fan. 
We do  not have speed control but vary the speed by changing the fan 
voltage. We use a  linear controller also previously published but have to be 
concerned about fan  starting voltage. We want to be able to hold constant 
temperature over a 10C  ambient change. Found that 12 V fan is best and at the 
same time looked for low  noise. Learned also that more heat from the back 
plane helped with the operating  range. Now all voltage regulators and the fan 
power transistor are along with  heat sinks are mounted on the back plate. 
Side benefit is more stable voltage  out of the regulators.
This would be an ideal project for time nuts, since the results will apply  
to other Rb's not only the 5680 and benefit the community. I will stay out 
of  the discussion since we have our hands full.
Bert Kehren
 
 
In a message dated 7/3/2014 9:37:27 P.M. Eastern Daylight Time,  
not.ag...@btinternet.com writes:


Hi  Bert,

I am thinking about testing a heat pipe on a fan cooled setup I  use.
The first temp controlled chassis I did used a peltier and works  very
well, but was a lot more work to do and is much more power hungry.  

The main problem I find is not the temp controller itself, but  rather
the change in the temperature across the chassis as the  ambient
changes. However good the temp controller is, it only controls  a
single point, but other points further away from the  sensing
thermistor can vary a lot. 
I noticed you posted a picture of a  heat pipe cooler a couple of weeks
ago - did you happen to compare the  temperature across the unit with
direct fan cooling and the heat pipe  cooler, or with different heat
pipes?

Angus.



On Sat,  28 Jun 2014 12:37:37 -0400 (EDT), you wrote:

Will someone beside us  use heat pipe. Would love to have an impendent  
input. What does  it take to get a test going. Scott has done a lot of 
work, how   
about some one else step up to the plate. There are a lot of time nuts  
out 
there  with the 5680A,many for the first time will have a  very good 
reference and some  of our experts with proper  equipment can make a big 
difference.
Bert Kehren
 
  
In a message dated 6/28/2014 12:20:12 P.M. Eastern Daylight  Time,  
newell+timen...@n5tnl.com writes:

At  04:32  AM 6/28/2014, wb6bnq wrote:

monitoring process  ?  In other  words have you traced out the 
connections  to see what is driving the  pin you think is the temperature 
 
input ?

No. I've only traced back from  the ADC  input to the voltage divider.


The next big question  is  have you monitored the frequency and its 
stability,  externally, to  observe what effects are taking place when  
you disable this input to  the A/D ?

I have  not.


That sounds complicated and messy  but  may be easier than it 
appears.  An appropriate  container  would be:

It does sound messy. I don't think  I'm willing to dunk one of  my  units.
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[time-nuts] FE 5680A GPSDO update

[EWKehren]

First let me thank again Scott Newell for all the work he has  done. The 
links included in this post where made possible by Scott. All three  exceed 
the limit of time nuts but will give you a better understanding as to  what is 
going on. First removing the 10 K resistor changes the Rb frequency any  
where between 2 to 3.5 E-10 upward. It is a function of the temperature of the 
 device. In the first link you will see what happened right after removing 
the 10  K.
http://n5tnl.com/time/fe-5680a/gpsdo/JK5680A_Test35.xls  Allow me to explain
The first collum is time in seconds followed by time in hours. The third  
is phase input measured by the loop The loop will try to set it to 14080.  We 
call that the set point. The next column shows the delta to the set point  
followed by the control word send to the unit and its 2's compliment. 2's  
compliment since in this case it is mostly a very large negative number 
easier  to read. Finally the status word which shows a 1 saying it is unlocked 
followed  by a 0 other options are glitch hold and alpha. the third column 
shows which  mode. The way it is presently programmed it will advance to Mode 5 
and  alpha.  That would show up here as 15.
Before the modification this Rb showed when settled -124. The 1 pps comes  
from a $ 16 ublox M7 no sawtooth correction.. At about 18.5 hours the GPS 
filter  is activated with a 12 setting and you notice a dramatic change in the 
control  word. still has a few more steps. What you see is frequency 
correction do to  influences like GPS Rb and its temperature. Rb has only a 
heatsink, no  temperature control.
Next this mornings readings.  
http://n5tnl.com/time/fe-5680a/gpsdo/JK5680A_Test35c.xls.  This is more of the 
same but you see a dramatic change between 
day  (left) and night (right) allowing me to check when he is not  working.
Summarizing temperature control is not a requirement but the curve will  be 
flattened if the Rb is held at a constant temperature. Each digit is a 
change  of 6.8-13. but it is not directly correlated to the output frequency, 
what it  says it is the control word that according to the filter function 
tries to set  it exactly to 10 MHz. The plot that I attached so many times may 
contribute to  the frequency in 1 second increments that most likely is 
reduced by disabling  the heater current sensing but there may be other  
sources.
That is why I feel strong about a clean up loop. Those happy with what  you 
see stop right now. Again thanks to Scott here is a link to the Auxillary  
board schematic. 
http://n5tnl.com/time/fe-5680a/gpsdo/AUXILLARYBOARDrevA27-04-2014.pdf   I did 
post a picture but to file limitation was not able to 
post  the schematic. It has room for power conditioning a PIC and two flexible 
outpu  circuits. First the PIC takes the output of the controller (attached) 
and  modifies it in such a way that it can drive a FTDI USB adapter to 
store the  output without PC requirement. The code is presently in PIC Basic 
would like to  find some one to write PIC code so we can use FTDI and a I2C 
display. Scott is  looking at it but if some one has the expertise would  help.
The outputs can be individually set to 5 or 10  MHz.
A third board is presently in the works by an other time nut. All boards  
will be in Gerber. He is working on a temperature control board. All boards 
are  5 X 5 cm.  What is missing is a clean up filter board. I am looking for  
someone that can do it in Gerber, please contact me off list. We have a 
circuit  but it is on expressPCB and should be modified for this  application.
I look at it the following way. More than half the cost of the kit  is 
taken  up by pay pal, shipping kitting etc. Boards are the smallest  cost part 
and going from one to 4 will only increase the kit cost by $ 5. In my  book a 
bargain. 
Comments are appreciated
Bert Kehren
Some may not get this post because AOL for instance flags it as  spam

Typical  RS 232 output.doc
Description: Binary data
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[time-nuts] FE 5680A GPSDO update second link problem

[EWKehren]

Some how a dot snuck in at the end of the second link after the s you can  
use the old link and delete the dot or use this one
http://n5tnl.com/time/fe-5680a/gpsdo/JK5680A_Test35c.xls
Sorry about  that
Bert Kehren
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[time-nuts] Ulrich Bangert

[EWKehren]

 
After talking with Hartmut off list and finding out that  no family lives 
close by I decided to send this letter shown below in German,  hand written 
on German condolence stationary to his neighbor and friend. The  English 
translation is below. 
Sehr geehrte Herr Hackfeld, 
Als Erstes möchte ich mein herzlichstes Beileid an Sie  als Freund und an 
Ulrichs Familie ausdrücken.  Mein Name ist Bert Kehren.  Ich hatte die Ehre, 
wie viele von uns  „Time Nuts,“ direkten Kontakt mit Ulrich zu haben.  Es 
sind viele „Time Nuts“ weltweit die  um Ulrich trauern.  Ulrich war  einer, 
der immer wieder durch seine Beigaben unser Wissen  erweiterte. 
Seine Hinterlassenschaft ist [u.A.] ein Programm, das er  entwickelt und 
uns kostenlos zur Verfügung gestellt hat.  Es ist ein Eckpfeiler unserer 
Arbeit und  wird auch weiter so bleiben. 
Er wird immer bei den „Time Nuts“  in Gedanken bleiben.   
Ich bitte Sie, meine Anteilnahme auch an seine Familie  auszurichten. 
In Trauer, 
Bert Kehren  
Dear  Mr. Hackfeld, 
First, I would like to express my deepest sympathy, to  you as his friend 
and to Ulrich’s family.  My name is Bert Kehren.  As  did many of us “Time 
Nuts,” I had the honor of being in direct contact with  Ulrich.  There are 
many “Time Nuts”  around the world who are mourning him.  He was someone 
whose input always expanded our  knowledge. 
His  legacy, among other things, is a program which he developed and which 
he  provided to us free of charge.  It  is one of the pillars of our work 
and will continue to be  so. 
He  will always remain in the thoughts of us “Time  Nuts.” 
I  would ask you to express my sympathy to his family as  well. 
Sadly, 
Bert  Kehren
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Re: [time-nuts] DIY FE-5680A lobotomy (disable temp compensation)

[EWKehren]

 
Because the 96K attachment needs moderator approval I am sending it again  
without attachment. It is the one I posted before and shows clearly the  
frequency jumps. So here is the rest of it.
Magnus
Sorry but I disagree with your statement. First and foremost we have to  
accept that these devices are not intended for time nuts (metrology). Already 
my  first 1985 FRK monitors the cell current and adjusts the C field  
accordingly. The HP 5065 does not since it is not intended for the same market, 
 
it relies on its temperature control of the total A12 assembly. A closer look 
at  FE specs you will notice the following statement  including frequency 
over  or undershoot at any fast or slow temperature slew rate. How do you 
think they  do it. In the case of units that have a DDS in the control loop 
they do it with  the DDS. How else do you explain the attached plot. Again my 
apologies for not  remembering who posted it. I noticed the jumps and 
mentioned them when I first  took a look at the 5680 I did use temperature 
control in a crude way using what  I call the Bang Bang fan control on an ATT 
FRS 
heatsink. My YSI did not register  any changes but the 5680 noticed and was 
visible using my Tracor 527 E.
The 5680 is not a unit that we will use it turned in to a distraction but  
we did the controller for time nuts. Our focus when it comes to temperature  
control is on the FRK that is why Juerg who focused on the 5680 only uses a 
heat  sink. Working out of a basement that is next to a garage data in the 
winter  looks a lot more stable than now. We monitor the tuning word which 
has a  resolution of 6.8 E-13 and when you see no change over long time 
periods in  January and changes now exceeding E-12 now to start asking why. The 
differences  are garage door is open more often and the sun shines part of 
the time directly  in to his basement lab.
When the loop is in the long time constant mode to take advantage of the  
GPS accuracy resolution which increases with time,  jumps by the 5680  DDS 
are no help. It all depends what ultimate accuracy time nuts want out of the  
5680. A good fan control along with a fixed setting the temperature ADC 
input  used for frequency control will yield best results. Work by time nuts  
will help we are not going to do it.
The reason is we are totally tied up with work on using the FE 405 B. I  
stumbled by accident on to it and bought some for testing. Initial tests show  
for me unbelievable performance specially when it comes to ADEV. It is 
perfect  for GPSDO applications since it is all digital control with a step 
resolution of  6 e-15. How ever it is also not all perfect since I did detected 
jumps that I  could not explain. Since our testing capabilities are limited 
I did make Tom  aware of the unit and he has now caught the bug.  
http://leapsecond.com/pages/fe405/  . We  think we have traced the problem to 
again 
frequency control using oven current  have disabled it and hope to have better 
data to prove that the 3 E-12 jumps are  due to the current monitor. Stay 
tuned. Hope it does not change the ADEV. Not  many of you have OCXO's with 
that low ADEV.
We are also using the controller for this device and results look very  
promising.
That is why we call it the Universal Controller. In the future it will  
control many other devices.
But for now please those of you that have the equpment and the expertize  
focus on the  FE 5680 A to make it a viable low cost house reference for a  
large # of time nuts.
Bert Kehren

 
 
In a message dated 6/28/2014 3:21:48 A.M. Eastern Daylight Time,  
mag...@rubidium.dyndns.org writes:

Hi,

I  fail to see what the benefit is of removing this unless a better temp  
compensation scheme is used. It is not likely to interfer with the external  
loop as it reduces the midterm noise that is systematic. It does add some  
higher rate noise but that is quantization errors of the systematics it  
reduces. I like to see measurement that support the claim and I am skeptic. As  
I see it you give the external loop more systematic noise to dampen and the  
tighter loop you make the more you will  expose.

Cheers, 
Magnus

div  Originalmeddelande /divdivFrån: Scott Newell  
newell+timen...@n5tnl.com  /divdivDatum:28-06-2014  03:50  (GMT+01:00)  
/divdivTill: time-nuts@febo.com /divdivRubrik:  [time-nuts] DIY 
FE-5680A lobotomy (disable temp compensation)  /divdiv
/divBert asked me to send an update on the  FE-5680 tempco mod progress.

It appears that the FE-5680A temperature  signal (or maybe it's really 
a current sense signal?) can be disabled by  removing a single 10k 
0805 surface mount resistor.

Using Elio  Corbolante's terrific high-res scans, I've noted the 
resistor location:  http://www.n5tnl.com/time/fe-5680a/lobotomy.png

Why would you want to  disable temperature compensation? As we've 
seen, the unit's firmware will  adjust the DDS frequency as the 
temperature signal changes. If you're  using 

Re: [time-nuts] DIY FE-5680A lobotomy (disable temp compensation)

[EWKehren]

Thanks Bob for putting it in perspective, 0.05 C is very doable, looks like 
 it is also used in some OCXO's.
Bert Kehren
PS  on a related subject I just pulled PROCEEDINGS OF THE ANNUAL  SYMPOSIUM 
ON FREQUENCY CONLTROL ATLANTIC CITY in the late 70's did attend a few  
because of my involvement in GPS but then did not understand half of it and now 
 
want to check what I have learned since. Very interesting reading.
 
 
In a message dated 6/28/2014 9:36:32 A.M. Eastern Daylight Time,  
kb...@n1k.org writes:

Hi

Most of these lightweight Rb’s do the same thing. They  watch the oven 
current on one or the other section and try to guess the  external temperature. 
Based on that guess they do a simple temperature  correction on the unit. 
The older analog units feed a DC signal into the EFC.  The newer digital units 
feed a signal into the DDS.

In both cases  (analog and digital), the ADEV of the units can be improved 
by disabling this  “feature”. That of course assumes you are at a constant 
(as in very constant)  abient temperature. In the case of the analog part, it
’s the noise on the  heater current that gets you. In the case of the 
digital approach, it’s the  tuning granularity of the DDS that messes things up 
(and possibly heater  current noise as well). 

How constant is “very constant”? That depends  on the Rb you have. A good 
bet is that your device runs better than 2 to 4 ppb  over a 100C range 
without the compensation turned on. That gives you 20 to 40  ppt per degree C. 
To 
hit 1 ppt you would need to control the device to better  than 0.05 C. If 
you simply want to hit the 0.1 ppb temperature spec, then you  only need a 
two degree control. If you look at the temperature compensation  data words 
(ddd steps), some Rb’s in a batch are much better than others, so  there is no 
easy way to be sure of the results ahead of time.  

Bob

On Jun 28, 2014, at 3:21 AM, Magnus Danielson  mag...@rubidium.dyndns.org 
wrote:

 Hi,
 
 I  fail to see what the benefit is of removing this unless a better temp  
compensation scheme is used. It is not likely to interfer with the external 
 loop as it reduces the midterm noise that is systematic. It does add some  
higher rate noise but that is quantization errors of the systematics it  
reduces. I like to see measurement that support the claim and I am skeptic. As 
 I see it you give the external loop more systematic noise to dampen and 
the  tighter loop you make the more you will expose.
 
 Cheers,  
 Magnus
 
 div Originalmeddelande  /divdivFrån: Scott Newell  
newell+timen...@n5tnl.com  /divdivDatum:28-06-2014  03:50  (GMT+01:00) 
 /divdivTill: time-nuts@febo.com /divdivRubrik:  [time-nuts] DIY 
FE-5680A lobotomy (disable temp compensation)  /divdiv
 /divBert asked me to send an update on  the FE-5680 tempco mod progress.
 
 It appears that the FE-5680A  temperature signal (or maybe it's really 
 a current sense signal?) can  be disabled by removing a single 10k 
 0805 surface mount  resistor.
 
 Using Elio Corbolante's terrific high-res scans,  I've noted the 
 resistor location:  http://www.n5tnl.com/time/fe-5680a/lobotomy.png
 
 Why would you  want to disable temperature compensation? As we've 
 seen, the unit's  firmware will adjust the DDS frequency as the 
 temperature signal  changes. If you're using the '5680 inside a 
 control loop, it's likely  to conflict. By removing the resistor, that 
 channel of the 12 bit ADC  will be tied to ground through an existing 
 2.21k resistor. The unit  will see a constant 0 counts from the ADC 
 and assume it's really  cold.
 
 I modified one unit and monitored it for a few hours  over a range of 
 temps, running it nice and hot with no heatsink, then  blasting it 
 with a fan and placing it on an ice-cold heatsink. I  observed no 
 change in the DDS tuning words.
 
 It's a  really easy mod--remove four screws, set aside the insulator 
 sheet,  and apply your hot leucotome/soldering iron.
 
 
 I've  also found a simple mod to replace the temperature signal with 
 the  output of the unused trimpot. This allows you to simulate any 
  temperature you want. If there's any interest, I'll set up a test and 
  monitor the DDS tuning words as the unit's firmware tries to adjust 
  to the fake temp signal.
 
 
 -- 
 newell   N5TNL
 
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Re: [time-nuts] DIY FE-5680A lobotomy (disable temp compensation)

[EWKehren]

I can only answer some of your questions. The tuning word is modified by  
the temperature but if it came back to the same oven current it will again 
have  the same tuning word to the DDS.
Since we have not fount a temperature sensor they most likely use oven  
current that Bob mentioned.
If you do not plan to use it with a controller I would not recommend  
disconnecting it but if you have good temperature control you should not see a  
difference.
The controller can not selectively enable or disable the temperature sensor 
 and it would not make sense since the controller has no info as to 
temperature  and enabling the frequency control do to temperature would most 
likely 
cause a  frequency step.. The answer is use a laptop heat pipe it will do a 
great job  when portable and takes little power, Just received some more 
recharable lithium  12 V 9.8 A batteries. Light weight and low cost 
Bert Kehren
 
In a message dated 6/27/2014 11:04:31 P.M. Eastern Daylight Time,  
albertson.ch...@gmail.com writes:

So the  FE5680A will actually change the DDS tuning word based on an
internal  temperature sensor?

I could see why you might ant to disable this or  maybe not depending
on how it works.  Does the FE5680 first read the  user programmed word,
apply a delta then write it back or does it ignore  user settings.   I
can't believe it would overwrite a user  programmed running word.

But this also means there is a sensitive  temperature sensor inside the
FE5680.  Is there any way to read this  sensor via the serial port?

What software are you using to communicate  with the FE5680.  I'd like
to try doe experiments.   1) see  if we can take advantage some how of
the existence of the temp sensor and  2) possibly use the analog input
(a faked temp sensor) to control the  FE5680.


The problem with disconnecting the temperature sensor is  much worse
performance when the GPS is not available in hold over  mode.   GPS
rarely fails but I'm sure some people disconnect the  GPS to use the Rb
as a portable frequency reference.   It would  be good if it were
temperature compensated while in holdover.

One  experiment comes to mind:  If the resister is removed, can there
GPSDO  controller selectively enable and disable  temperature
compensation?

What software are you using to support  your testing?



On Fri, Jun 27, 2014 at 6:50 PM, Scott Newell  newell+timen...@n5tnl.com 
wrote:
 Bert asked me to send an  update on the FE-5680 tempco mod progress.

 It appears that the  FE-5680A temperature signal (or maybe it's really a
 current sense  signal?) can be disabled by removing a single 10k 0805 
surface
 mount  resistor.

 Using Elio Corbolante's terrific high-res scans,  I've noted the resistor
 location:  http://www.n5tnl.com/time/fe-5680a/lobotomy.png

 Why would you  want to disable temperature compensation? As we've seen, 
the
 unit's  firmware will adjust the DDS frequency as the temperature signal
  changes. If you're using the '5680 inside a control loop, it's likely  to
 conflict. By removing the resistor, that channel of the 12 bit ADC  will 
be
 tied to ground through an existing 2.21k resistor. The unit  will see a
 constant 0 counts from the ADC and assume it's really  cold.

 I modified one unit and monitored it for a few hours  over a range of 
temps,
 running it nice and hot with no heatsink, then  blasting it with a fan and
 placing it on an ice-cold heatsink. I  observed no change in the DDS 
tuning
 words.

 It's a  really easy mod--remove four screws, set aside the insulator 
sheet,
  and apply your hot leucotome/soldering iron.


 I've also  found a simple mod to replace the temperature signal with the
 output  of the unused trimpot. This allows you to simulate any temperature
 you  want. If there's any interest, I'll set up a test and monitor the DDS
  tuning words as the unit's firmware tries to adjust to the fake temp  
signal.


 --
 newell  N5TNL

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-- 

Chris Albertson
Redondo  Beach,  California
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Re: [time-nuts] DIY FE-5680A lobotomy (disable temp compensation)

[EWKehren]

Will someone beside us use heat pipe. Would love to have an impendent  
input. What does it take to get a test going. Scott has done a lot of work, how 
 
about some one else step up to the plate. There are a lot of time nuts out 
there  with the 5680A,many for the first time will have a very good 
reference and some  of our experts with proper equipment can make a big 
difference.
Bert Kehren
 
 
In a message dated 6/28/2014 12:20:12 P.M. Eastern Daylight Time,  
newell+timen...@n5tnl.com writes:

At 04:32  AM 6/28/2014, wb6bnq wrote:

monitoring process ?  In other  words have you traced out the 
connections to see what is driving the  pin you think is the temperature 
input ?

No. I've only traced back from  the ADC input to the voltage divider.


The next big question is  have you monitored the frequency and its 
stability, externally, to  observe what effects are taking place when 
you disable this input to  the A/D ?

I have not.


That sounds complicated and messy  but may be easier than it 
appears.  An appropriate container  would be:

It does sound messy. I don't think I'm willing to dunk one of  my units.


-- 
newell  N5TNL  

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[time-nuts] FE 5680 A GPSDO (frequency control)

[EWKehren]

I probably should have called it more correctly frequency  control. Thanks 
to the help from Scott N5TNL we clearly where able to watch the  DDS as fan 
cooling was added and removed from the Rb. Only a small change  resulted in 
the DDS tuning word changing by 89 which is a frequency change of 6  e-11. 
The source has to be a temperature sensing element feeding one input to  the 
4 channel 12 bit ADC. Some one please work this issue identify and  disable 
that sensor and run a test verifying that tuning is not  lost.
Thank you
Bert Kehren
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[time-nuts] FE5680 GPS Disciplined Controller Update

[EWKehren]

The response has been very positive such that a $ 45 kit is doable. Working 
 on getting at least two beta tests lined up.
However it is disappointing that no one has stepped up to tackle the  
temperature problem. how many have looked at the temperature attachment and  
clicked on the N5TNL link. Let me make it clear that yes the GPSDO will work 
but 
 there will be one or two orders of magnitude degradation without active 
fan  temperature control unless the internal temperature compensation is  
disabled.
I like to float an other idea I did attach a picture of the auxiliary board 
 which we also use on other projects. That board along with inductors and  
two mini circuit transformers could be added to the kit for an extra $  
8.00. Other parts are readily available. Going forward it would make sense to  
have a temperature control board and a clean up loop board. We have them but  
they are express PCB. if members would be willing to do a Gerber version I 
will  gladly work with them off list and than they could be added for an 
extra $ 4.00  to the kit.  We do not have the time. Total kit would be $ 57.00 
maybe $  55.00 including four 5 X 5 cm. boards.
Let me know what you think.
Bert Kehren
 
 
In a message dated 6/19/2014 2:56:52 P.M. Eastern Daylight Time,  
t...@leapsecond.com writes:


-  Original Message - 
From: Chris Albertson  albertson.ch...@gmail.com
To: Discussion of precise time and  frequency measurement 
time-nuts@febo.com
Sent: Thursday, June 19,  2014 8:31 AM
Subject: Re: [time-nuts] FE5680 GPS Disciplined  Controller


 I've been working in the same thing BUT I don't  want anyone who builds it
 to need a PCB.  And I want the firmware  to load over USB so there is no
 need to ship programmed chips or deal  with external programmers.   I 
think
 I can get the cost  below $20. That said I doubt I'll get 1E-13
  performance out of my Rb.
 
 My little Arduino based controller  has been running now for a couple 
months
 and keeping a crystal in  lock.  The board has a pins left over for a 
serial
 port that I'll  hook up to the Rb.
 
 The trick to getting the cost down is NOT  to do a custom PCB.  Take
 advantage of one of the uP development  boards and then for under $5 you 
get
 the USB interface, D/A and A/D,  serial ports, timers and quite a bit of
 logic all  1/3rd the size  of a credit card.
 
 
 On Thu, Jun 19, 2014 at 12:57 AM,  Jan Boutsen jan.bout...@telenet.be
 wrote:
 
  Count me in for an assembled and tested board. Great project.
  Jan




 - Original  Message -
 From: ewkeh...@aol.com
 To:  time-nuts@febo.com
 Sent: Wednesday, June 18, 2014 8:49  PM
 Subject: [time-nuts] FE5680 GPS Disciplined  Controller



 FE5680 GPS  Disciplined  Controller
 With all the FE  5680 rubidium  oscillators being used as door stops out
 there some of us  decided  to develop a GPSDO for it. The main question 
we
  have:
 Is there sufficient  interest among time nuts for a  discipline 
controller
 for the FE5680 to make it  available?  Looking at the postings over the 
last
 two years I am not so   sure.
 The  construction and preliminary testing of a Brooks  Shera style GPS
 discipline  controller for the later version  (6.81e-13 resolution) of 
the
 FE5680
 has been   completed. We are trying to determine the number of people 
that
  would be  interested in obtaining an FE5680 discipline controller (if  
there
 is
 sufficient  interest about $45 a kit  shipping included, $75 for an
 assembled and tested  board,  international orders for an additional $5)
 when
 it  is
 released.
 We are also looking for three Beta   testers that would be willing to
 purchase, assemble, and test our  Beta release  controller kit with their
 own
  FE5680A and GPS receiver or Tbolt and provide  feedback. Please send  an
 email to
 _EWKehren@aol.com_  (mailto:ewkeh...@aol.com)   Subject Time-Nuts FE 
5680A,
  if you would be interested in being one of the three  Beta testers. A  
key
 requirement is the willingness to get to it right away,  the  board 
assembly
 takes about 30 minutes. Instrumentation  to measure results is  also a
 requirement. We obtained  impressive results using a cheap ublox 6M
  receiver.

 The  FE5680 GPS discipline controller  is a small (2” x 2”) board using 
8
 DIP’s and 1  SOT23-5  package powered by +5v with 0.1” headers for all
  inputs
 and outputs. Our  plan is to have the kit supplier  solder in the only 
SMD
 device on the board. A  GPS receiver  1PPS and 10 MHz sine from the 
FE5680
 feed the board with two  9600  baud serial ports sending TTL level tuning
 commands to  the FE5680 and receiving  commands from and sending status  
data
 to a
 PC for data logging and system  control  via a simple terminal program.
 In the chip count are  two  opto couplers that allow the use of isolated 
TTL
 to USB  conversion. These  USB adapters are readily available and  
furnish
 the 5 V necessary for the  secondary of the opto  circuit. An option is 
to
 not
 use the 

Re: [time-nuts] FE5680 GPS Disciplined Controller Update

[EWKehren]

Again we are talking past each other I am talking about temperature  
compensation with the DDS that ideally should be removed. Those steps  upset 
any 
loop.
Bert
 
 
In a message dated 6/24/2014 6:38:48 P.M. Eastern Daylight Time,  
hol...@hotmail.com writes:

Check  out the temperature control code in Lady Heather.  It uses a nice 
PID  controller algorithm (from Warren Sarkison) to PWM modulate a fan to 
stabilize  the environment around the Tbolt.  It can achieve millidegree range  
stability...  I have seen long term RMS values of the temperature plot  less 
than a few micro-degrees.   The standard Tbolt oscillator has a  rather 
horrible tempco...

I'll post some recommendations/findings about  various environmental 
sensors I tried while I was building my  weather/envionmental sensor package.   
Hint:  the  MS5611  pressure sensor chip is very nice.  Has 24 bit ADCs for 
the pressure and  temperature readings and produces very stable readings with 
a 100 Hz update  rate.
--
However it is disappointing that no one has stepped up  to tackle the  
temperature problem.   
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Re: [time-nuts] FE5680 GPS Disciplined Controller Update

[EWKehren]

Lets be clear the 1 E-13 is a totally different project and does not relate 
 to the FE 5680 A.  Yes most likely we will use the same universal  
controller but with different code, same board. GPS crosses the 1 E-13 line at  
10 seconds little more than a day. I whish it was just temperature as I  
mentioned we are able to hold the back plate of a FRK at 0.01 C. But that is 
the  easy part. 
Bert Kehren
 
 
In a message dated 6/24/2014 8:06:52 P.M. Eastern Daylight Time,  
kb...@n1k.org writes:

Hi

If:

1)  You are after better than 1.0 x  10^-13 accuracy
2) You are getting 1 to 9x10^-9 at one second ADEV out of  your GPS 
3) You have a telecom Rb with 1 to 5x10^-10 temp coef over a 70C  delta
4) Your Rb self heats 20 to 30C in still air

Here’s some  math:

You will need at least 10,000 seconds to get a single frequency  estimate 
and likely 100,000 seconds.

You are likely to go through temp  cycles in a room at a 30 to 90 minute 
rate. (1800 to 3600 sec).

Your  room temp swings are *way* outside your likely loop. The Rb will have 
to deal  with them by it’s self.

——

Your Rb is “sort of” compensated in  the temcom units. It’s more like a 
TCXO than an OCXO. 1x10^-10 over 50C would  give you 2x10^-12 per degree C. 
That may be better or worse than the sample  you have. The “worse” really 
comes in  when you have one that’s a  parabola or third order temp curve. 

At least around here a room swing  of 2 to 4 C is pretty normal with the 
heat or air-conditioning turned on. That  gets you into the 4 to 8x10^-12 
swing range. In a typical garage you are at  10C and 2x10^-11. 

If you want that to be *below* your 1x10^-13 goal,  you have to knock it 
down by about 100X. 

——

Is the goal  rational? Well this is Time Nuts …. It is roughly the sort of 
goal Bert has  said they are after. 

Most of the lightweight Rb’s have a major ADEV  hump when the temperature 
compensation cuts in. Without *good* temperature  stabilization, you will not 
disable this correction. There’s no real way to  know what the ADEV is 
without this hunting until you do it. Because of the  self heating (and 
gradients), it’s not a real easy thing to do. 

If you  are using an ensemble of parts to get the ADEV, temperature likely 
will  correlate between them. You will not get the “group vote” to suppress 
it the  way you some other sources of ADEV.

——


Yes, I’m sure Bert  can cross the T’s and dot the i’s better than I can, 
but that’s a pretty good  outline of the problem.

Bob




On Jun 24, 2014, at 4:34  PM, Tom Van Baak t...@leapsecond.com wrote:

 However it  is disappointing that no one has stepped up to tackle the  
  temperature problem. how many have looked at the temperature attachment 
 and  
 clicked on the N5TNL link. Let me make it clear that  yes the GPSDO will 
work but 
 there will be one or two orders of  magnitude degradation without active 
 fan  temperature  control unless the internal temperature compensation 
is  
  disabled.
 
 Can you clarify the two orders of magnitude  claim? That's hard for me 
to believe, I think, without seeing the ADEV plots  or actual lab report.
 
 I mean, even a cheap XO or TCXO or OCXO  can be disciplined against GPS 
and achieve superb results. Temperature (or  rather, temperature rate of 
change) has little effect short-term. Temperature  also has little to zero 
effect long-term. So it's only in the, what, tau 100  to 1000 or maybe 1 
second range that temperature even matters. As long as  the LO is locked to 
GPS; 
I assume you're not talking about holdover.
  
 Obviously you'd want a slightly shorter loop time constant for a  
non-temperature-controlled Rb than a fancy temperature-controlled Rb. But does  
this really make a one or two *orders of magnitude* difference?
  
 /tvb
 
 
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Re: [time-nuts] temperature sensor

[EWKehren]

We use NTC 10K with the FRK. Precision is not important.We have to play  
with the settings in order to have fan starting voltage over the full temp.  
range.
Bert Kehren
 
 
In a message dated 6/24/2014 8:12:45 P.M. Eastern Daylight Time,  
shali...@gmail.com writes:

After  having tried just about every solution under the sun, my opinion is 
that  within the ambient temperature range (up to at least 100°C) and 
homebrew  budgets, nothing beats an NTC thermistor. 

They are inexpensive, have a  large output and interface most easily with a 
microcontroller's ADC in  ratiometric mode requiring a single precision 
resistor. Even cheap ones have a  1% tolerance which is more precision than you 
will ever need.

My  favorite is a 10k at 25°C with a B factor of 3380 at 25/85 that costs 
$1.25 at  Digikey. The math to derive the temperature from the ADC reading is 
simple  (you do need the log function) and a mundane 12 bit ADC gives you 
temperature  with a fraction of a degree resolution and much better than a 
degree absolute  precision if you actually needed it. With a 2.5V reference 
(like those in my  favorite Silabs uC), self heating is negligible, even in 
open air (a fraction  of a degree).

This is implemented in my Thunderbolt Monitor kit  software to measure 
ambient temperature.

If you need better resolution  than what you can get by directly measuring 
the voltage at the junction of the  resistor and thermistor (due to limited 
resolution of the ADC), add one op-amp  and three resistors, or use the PGA 
if your microcontroller has  one.

Didier KO4BB


On June 24, 2014 6:43:07 PM CDT, Chris  Albertson 
albertson.ch...@gmail.com wrote:
On Tue, Jun 24, 2014  at 3:24 PM, Mark Sims hol...@hotmail.com wrote:

  ...
 However it is disappointing that no one has stepped up to  tackle the
 temperature problem.


I can post  what I have.  It's a uP based PWM fan controller.  It is  a
stand
alone device that does not know anything about the  FE5680 but it would
be
easy to add into any GPSDO using the  GPSDO's existing uP provided there
were enough extra analog pins  available.  It uses the Arduino software
environment but I built  it using a bare 8-pin DIP.  The problem with it
is
I do not  have a good temperature sensor, The ones I tried are noisy.  
SO
I'm looking forward to your sensor info.

My  first controller used a comparator chip.  Then I figured the uP  was
the
same cost and same 8-pin package but could do things  like PID, data
logging, led status blinking and whatever.  This  is a start on the
code
that works just like the comparator and  uses a pot for the user to
adjust a
set point.

If  you see a way to make this better post the changes.
Some things I will  do are (1) use better sensor, (2) use PID library,
(3)
measure  ambient air  temp.
FanController.ino
https://dl.dropboxusercontent.com/u/28915695/FanController.ino

BTW  is there any design info on the FE5680 controller.  Schematics  of
source code?



-- 

Chris  Albertson
Redondo Beach,  California
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-- 
Sent from my Motorola Droid Razr  HD 4G LTE wireless tracker while I do 
other  things.
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Re: [time-nuts] Sad news Ulrich Bangert

[EWKehren]

It is a shock and a loss not just to time nuts but many others that where  
touched and benefited from him.
Like in the case of Brooks I know what I will do and I urge those of you  
that knew him through any type of contact make the old fashioned proper thing 
by  sending his wife a letter or card
 
Frau Ina Bangert, 
Ortholzer Weg 1, 
27243 Gross Ippener 
Germany
Bert Kehren
 
 
In a message dated 6/22/2014 12:36:22 P.M. Eastern Daylight Time,  
ail...@t-online.de writes:

I am shocked to  hear that.

Urich was a very helpful friend, I've learned a lot from  him. I'm so 
sorry to hear that.

Please allow me to say some words  in Ulrichs (and my) native language.

Die Nachricht vom Tode Urich's hat  mich sehr getroffen. Ich habe ihn als 
einen hilfsbereiten und offenen  Menschen kennen gelernt, aber leider nie 
persönlich kennen lernen können.  Bitte, lieber Hartmut, falls Du Kontakt 
hast, richte der Familie mein  herzliches Beileid aus.

Thank you very much.

Volker -  DF9PL


Am 20.06.2014 22:52, schrieb Hartmut Paesler:
 Dear  group,

 unfortunately I have to deliver the sad news that  Ulrich Bangert, DF6JB
 passed away on 11/06, aged 59.

  Best regards,

 Hartmut DL1YDD


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Re: [time-nuts] HP E3610A Power supply

[EWKehren]

Paul we need to talk about 405 many things happening. I will be out from 11 
 till 3 otherwise at home.
Bert
 
 
In a message dated 6/18/2014 10:41:32 P.M. Eastern Daylight Time,  
paulsw...@gmail.com writes:

Bert  just finding out that google mail is treating your emails as spam!
Not sure  if the message appears but as you can see it questions who you 
are.
I found  numbers of missing emails a few minutes  ago.
Regards
Paul
WB8TSL


On Thu, May 22, 2014 at 7:59 AM,  ewkeh...@aol.com wrote:

 This may be off topic but I did  check with Tom and many time nuts may 
have
 HP E3610A power supplies on  their bench and mine smoked a ublox GPS so 
that
  makes it topic  related..
 The reference section has some 1 uF 50V capacitors and in my  unit one
 shorted. The reference section has fuses on the board but  they did not
 open. The
  7912 overheated and shorted  out,  traces are discolored the op amp  
shows
 signs of  overheating and burned out. The result was the output went  to
  30V+
  and next morning the ublox chip plastic showed where the  chip  smoked. 
As
 a minimum I recommend replacing the 1 uF  capacitors with new quality  
caps,
 I also ordered 15 V 5 W zeners  and 0.5 A 20 mm glass fuses.
 Bert Kehren
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Re: [time-nuts] FE5680 GPS Disciplined Controller

[EWKehren]

 
Tom 
I am not concerned having followed the discussions lets see what comes from 
 it. Based on the response, we will have our hands full.
Let me make clear I take credit for instigating it but it  involved five 
people that at this time have chosen not to be  mentioned.
Bert.

 
 
In a message dated 6/19/2014 2:48:13 P.M. Eastern Daylight Time,  
t...@leapsecond.com writes:

Chris,

I'm glad you're making progress on your Arduino  GPSDO. You've mentioned it 
in a dozen postings the past half year. Perhaps you  will post the source 
code sketch, full design, and actual phase / frequency /  adev results some 
day. Many of us are willing to help as independent testers  and see actual 
results.

Meanwhile... Now would be the time for you to  let Bert have the stage; he 
has an actual working design, with PCB, and  several tests in progress. 
High-performance results. This represents a year of  work on his part, and 
others who have freely collaborated and contributed to  all aspects of his 
project. It's really nice.

Please do not hijack the  thread of another time nut's superb effort. Some 
week it will be your turn to  post final results of your project. This is 
not the  week.

Thanks,
/tvb

- Original Message - 
From:  Chris Albertson albertson.ch...@gmail.com
To: Discussion of  precise time and frequency measurement 
time-nuts@febo.com
Sent:  Thursday, June 19, 2014 8:31 AM
Subject: Re: [time-nuts] FE5680 GPS  Disciplined Controller


 I've been working in the same thing BUT  I don't want anyone who builds it
 to need a PCB.  And I want the  firmware to load over USB so there is no
 need to ship programmed chips  or deal with external programmers.   I 
think
 I can get the  cost below $20. That said I doubt I'll get 1E-13
  performance out of my Rb.
 
 My little Arduino based controller  has been running now for a couple 
months
 and keeping a crystal in  lock.  The board has a pins left over for a 
serial
 port that I'll  hook up to the Rb.
 
 The trick to getting the cost down is NOT  to do a custom PCB.  Take
 advantage of one of the uP development  boards and then for under $5 you 
get
 the USB interface, D/A and A/D,  serial ports, timers and quite a bit of
 logic all  1/3rd the size  of a credit  card.


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[time-nuts] Ublox 7

[EWKehren]

Having used lately ublox 6M for GPSDO work I decided to buy a couple of MAX 
 7C's on ebay for $ 16.00 181293242043
Super results.  We are going to do some saw tooth analysis but most  likely 
will not post them because the deterioration of the list has resulted in  
many on the real time nuts have gone away and do like we do every thing off  
list since this has deteriorated in to a chat room with the majority of the  
listings not time or frequency related. 
Serious time nuts can contact me off list and maybe be added to the group.  
We are doing some neat projects.
Bert Kehren
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Re: [time-nuts] Ublox 7

[EWKehren]

Don
I will continue to be part of the list but am frustrated with the loss of  
some of the best we used to have and I do not consider my self one of them, 
but  I learned immensely from then. I am not the only one with that opinion 
looking  at the number of responses I am getting. 
I do not know how long you have been on the list but it used to be  
different and better.
Bert Kehren
.
 
 
In a message dated 5/24/2014 12:33:47 P.M. Eastern Daylight Time,  
d...@montana.com writes:

Sorry to  lose you, Bert.
Evidently a new exclusive group is just what you  need.
Don

ewkeh...@aol.com
 Having used lately ublox 6M for  GPSDO work I decided to buy a couple of 
MAX
  7C's on ebay for $  16.00 181293242043
 Super results.  We are  going to do some saw tooth analysis but most  
likely
 will not  post them because the deterioration of the list has resulted in
 many  on the real time nuts have gone away and do like we do every thing 
off
  list since this has deteriorated in to a chat room with the majority of  
the
 listings not time or frequency related.
 Serious time nuts  can contact me off list and maybe be added to the 
group.
 We are doing  some neat projects.
 Bert Kehren
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-- 
The power of accurate  observation is commonly called cynicism by those who
have not got  it.
-George Bernard Shaw

Dr. Don Latham AJ7LL
Six Mile Systems  LLC
17850 Six Mile Road
Huson, MT, 59846
mail:  POBox  404
Frenchtown MT 59834-0404
VOX 406-626-4304
Skype:  buffler2
www.lightningforensics.com
www.sixmilesystems.com


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Re: [time-nuts] Ublox 7

[EWKehren]

There have been a couple of questions on and off list. as to the specific  
listing. I did forget to mention one thing. The unit comes with a built in  
antenna.  For time application not exactly what we want Not easy to take  
off since it is a block of ceramic with a pin through the center with little  
tolerance. Un soldering will not do doe to the heat sink created by the  
ceramic. Best way is to put the ceramic in a vice on its side excerpt a lot of  
pressure and it will brake or use a center punch or small hammer while it 
is  under pressure. It will shatter. next remove the pieces with a knife 
since there  is some glue. Now you are left with a pin. If you want to use the 
hole find a  way to hold the board, heat the pin with a soldering iron and 
wiggle it  out.  Did it with two units no problem.
Bert Kehren
 
 
 
In a message dated 5/24/2014 5:57:04 P.M. Eastern Daylight Time,  
slbur...@gmail.com writes:

While I agree  the noise has risen quite a bit, as a mostly lurker here, 
I've learned quite a  bit just watching the conversations.  Indeed when Dr. 
Bruce posts I'm  invariably driven into days of additional study to ponder his 
responses  :-)

Maybe someone could throw up a web page with the Ublox 7 findings  if you 
don't want to discuss on this list?  I have a selfish self  interest as I too 
have a couple of 7's on the way to the US from  China!

Scott

 On May 24, 2014, at 10:07 AM, Hans Holzach  hans.holz...@gmail.com 
wrote:
 
 bert,
 
  and how, please, are us newbies and dabblers supposed to learn from you, 
the  elite time-nuts, when you keep your discoveries secret, only 
accessible to a  group of hand-picked individuals? of course, this is a free 
world, 
and you,  like everybody, is free to share or not to share your knowledge. 
however, this  is my place to learn, and you don't do me a favour by saying 
goodbye to the  group. why not share your knowledge here, ignore the silly 
questions of the  not so bright, but give them the opportunity to follow your 
discussions with  the ones that are on a par with you? that i'd appreciate 
very much!
  
 hans
 
   ...because the deterioration of  the list has resulted in many on
   the real time nuts have  gone away and do like we do every thing off
   list since  this has deteriorated in to a chat room with the majority
of the listings not time or frequency related. Serious time nuts  can
   contact me off list and maybe be added to the  group.
 
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[time-nuts] HP E3610A Power supply

[EWKehren]

This may be off topic but I did check with Tom and many time nuts may have  
HP E3610A power supplies on their bench and mine smoked a ublox GPS so that 
 makes it topic related..
The reference section has some 1 uF 50V capacitors and in my unit one  
shorted. The reference section has fuses on the board but they did not open. 
The 
 7912 overheated and shorted out,  traces are discolored the op amp  shows 
signs of overheating and burned out. The result was the output went  to 30V+ 
 and next morning the ublox chip plastic showed where the chip  smoked. As 
a minimum I recommend replacing the 1 uF capacitors with new quality  caps, 
I also ordered 15 V 5 W zeners and 0.5 A 20 mm glass fuses.
Bert Kehren
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Re: [time-nuts] HP E3610A Power supply

[EWKehren]

Brooke NO
Bert
 
 
In a message dated 5/22/2014 3:12:56 P.M. Eastern Daylight Time,  
bro...@pacific.net writes:

Hi  Bert:

My E3617A has a front panel adjustment screw for Over Voltage  Protection.
Does the E3610 have  that?
http://www.prc68.com/I/Capacitors.shtml#SupCMeas

Have  Fun,

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

ewkeh...@aol.com  wrote:
 This may be off topic but I did check with Tom and many time  nuts may 
have
 HP E3610A power supplies on their bench and mine smoked  a ublox GPS so 
that
   makes it topic related..
 The  reference section has some 1 uF 50V capacitors and in my unit one
  shorted. The reference section has fuses on the board but they did not 
open.  The
   7912 overheated and shorted out,  traces are  discolored the op amp  
shows
 signs of overheating and burned out.  The result was the output went  to 
30V+
   and next  morning the ublox chip plastic showed where the chip  smoked. 
As
  a minimum I recommend replacing the 1 uF capacitors with new quality   
caps,
 I also ordered 15 V 5 W zeners and 0.5 A 20 mm glass  fuses.
 Bert Kehren
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Re: [time-nuts] OT - Need a German speaker

[EWKehren]

Joe
I am German living in the US. The site does ship to the US and once the  
product is available middle June If necessary I will be glad to help. 
How ever we have time nuts living in Germany and some probably have bought  
from this site. They can log in and find out what then payment options 
are.Most  likely you will be able to place the order and pay for it and have it 
shipped to  you. Shipping will be E 5.90 from what I can tell. But it will 
be clear once the  product is available. 
At the time if necessary I will be glad to get on the phone with you and  
talk you through the process. 
Bert Kehren
 
 
In a message dated 5/17/2014 11:28:17 P.M. Eastern Daylight Time,  
jg...@zianet.com writes:

Are  there any German speakers who live in the USA on this list? I need
someone  to order me a small kit from a German web site. I'll pay you
up front to  order this for  me.

http://www.box73.de/product_info.php?products_id=945

It is a  speech compressor kit that plugs into the mic of an FT-817. If
you can  help, please email me offline.

Joe  Gray
W5JG
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Re: [time-nuts] Can (will) a M12+T generate a negative sawtooth message ?

[EWKehren]

I think there is confusion between where there is a negative delay. Yes the 
 M12 can have a negative value but in order to correct for the full range 
of the  saw tooth at zero the DS chip has to add 128 nsec delay plus the zero 
value.  Depending on the message it ads or subtracts from that value. As 
saw teeth  get smaller there are chips with .25 and .5 nsec. steps. Later GPS 
units  have messages with higher resolution steps.
Bert Kehren
 
 
In a message dated 5/18/2014 8:26:31 P.M. Eastern Daylight Time,  
t...@leapsecond.com writes:

-128 is  0x80
+127 is 0x7F

If in doubt, just look at the sawtooth correction  messages coming out of 
your M12.

/tvb (i5s)

On May 18, 2014, at  4:17 PM, Chris Albertson albertson.ch...@gmail.com  
wrote:

 Chris,
 
 The manual clearly  states -128 to +127. What's your problem with that?
 
 Yes it  gives that range.  It says the value is stored in 8 bits.
  
 But how is it stored?  Certainly not as sign bit and 7 bit  magnitude
 or you could not have -128.They don't say but  options are either
 an assumed bias of -128 or twos complement.   I bet it's an assumed
 bias.
 
 
 --  
 
 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] Can (will) a M12+T generate a negative sawtooth message ?

[EWKehren]

The question is what is the definition on time. Yes it will be always 140  
nsec late to what the M12 calls zero. Good for a GPSDO. How ever if you want 
it  to relate to NIST time more hardware is needed unless you can 
compensate that  140 nsec in antenna delay.
A simple solution would be a preset counter that at 10 MHz takes out  
999 counts and the last 100 nsec are controlled by the DS chip. Using 100  
MHz and you can use 10 nsec and 0.1 nsec. resolution. Counter is simple to  
implement synchronizer on input and output and a PIC in between, or all 
discrete  logic or a 32 cell Altera G/A.In all cases the counter is hard wired 
and 
the GPS  receiver controls the DS chip.
Bert Kehren
 
 
In a message dated 5/18/2014 7:59:06 P.M. Eastern Daylight Time,  
t...@leapsecond.com writes:

Hal,

Yes, there are negative delays. The goal is that the  physical 1PPS output 
is, on average, exactly on-time. If designed right, that  means as many 
negative offset pulses occur as positive offset pulses. The  spread gives you 
the RMS value. 

This is exactly what you want for a  GPS timing receiver.

/tvb (i5s)

 On May 18, 2014, at 1:42  PM, Hal Murray hmur...@megapathdsl.net wrote:
 
  
 The ref output is the minimal delay through the chip covering the  input 
and 
 output pad buffers.  It will vary slightly with  temperature and voltage.
 
 There are no negative delays in that  sort of chip.  It's just a bunch of 
 gates/buffers with a  carefully calibrated delay.  (For a negative delay, 
you 
 would  need something like a PLL.)
 
 If the delay from the M12+T might  be negative, set the antenna cable 
delay to 
 be a bit short and add on  a constant in  software.
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[time-nuts] FTS 1200 transistor replacement

[EWKehren]

Traced the problem of my FTS 1200 to the first BC109 Transistor on the  
A2/A3 AGS/Amplifier board. Since it is right after the Oscillator transistor 
low  noise is critical. This unit is at least 30 years old and my question is, 
what  transistor will have even lower noise than the than low noise BC 109. 
Voltage is  6.43 V.
Thanks  Bert Kehren
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Re: [time-nuts] FTS 1200 transistor replacement

[EWKehren]

Thanks for all the help. I do have a couple of BC 109 but I thought with  
all the work to carefully disassemble the unit that after 30 years there 
would  be a better transistor.
Thanks again
Bert Kehren
 
 
In a message dated 5/17/2014 6:47:55 P.M. Eastern Daylight Time,  
csteinm...@yandex.com writes:

Bert  wrote:

what  transistor will have even lower noise than the  than low noise BC 
109.

Generally speaking, the baseband noise of a  bipolar transistor is 
most strongly influenced by the transistor's base  spreading 
resistance.  Of course, the transistor also needs to have  whatever 
other characteristics are required in the application circuit --  in 
particular, adequate current gain and transition frequency at the  
operating point and sufficiently low input capacitance -- and these  
may be mutually exclusive with lowest base spreading  resistance.

The 2SD786 and MPSA18 may be good candidates.  That  said, I seriously 
doubt you will get usefully better phase noise by using  a better 
transistor in this location.

Best  regards,

Charles



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Re: [time-nuts] Datum 4065A Cs Tube Response

[EWKehren]

The original price of the STEL1173CL was $ 125 in quantity 10 so $ 65 is a  
bargain.  I have no idea as to how it is used in the 4065A but if it is  
limited to 13 frequencies it may be worth wile to take a look at the AD 9913 
it  is capable to produce very precise frequencies exceeding its 32 bits, tvb 
did  run tests on a board we build and I have extra boards available. Has a 
PIC on it  that may help to emulate. Most likely will it not be the only 
STEL  failure.
Bert Kehren
 
 
In a message dated 5/5/2014 5:15:01 P.M. Eastern Daylight Time,  
ed_pal...@sasktel.net writes:

I know very  little about today's DDS chips, but I think that emulating 
the STEL-1173  would be a challenge.  It provides 48 bit frequency 
resolution.   I counted 13 different frequencies that are used to monitor 
the signal to  make sure that it's on frequency. Based on the manual, 
they were shifting  it many times per second. I'm not surprised the chip 
died - they worked it  to death!

Ed

On 5/5/2014 6:49 AM, paul swed wrote:
 I  will agree with Joe. I have a CS tube thats darn near impossible to  
read
 the beam current and yet it still locks. That truly amazes me. I  seem to
 recall other comments ages ago about that chip failing. There  should be a
 way to emulate it these days with all of the DDS chips and  such that are
 available.
 Good luck.
 Regards
  Paul.
 WB8TSL


 On Mon, May 5, 2014 at 8:20 AM,  J. L. Trantham jlt...@att.net wrote:

  Ed,

 If I have the math correct, and you are measuring  the voltage to ground
 through a 10 MegOhm input impedance DMM, you  have about 7.5 nA beam 
current
 which seems a bit low compared to  what I remember of the HP 5061A.
   However,
  you still have a definable 'peak' with a 'peak to valley' voltage of  
about
 60 mV or a 'useful signal current' of about 6 nA.  If  your unit's 
circuitry
 can properly amplify that and keep it a  clean signal, it should work.
 However, I would recommend setting  the OCXO precisely on frequency with 
a
 GPSDO before trying to  close the loop and 'locking' the signal to the CS
 tube.  It  will dramatically lower the work load of getting everything
  adjusted properly, particularly in a setting of low beam  current.

 Somehow, the value of 40 nA sticks in my mind  from the 5061A.  The 5061A
 manual says end of life of the HP  CS tube is a peak beam current of 8 
nA or
 less.  However, I  have units with less current and they still lock.  
The HP
  manual also says to measure the voltage at the output of the tube with  
a
 100
 MegOhm or higher input impedance DMM.  If  yours is less, that may
 artificially lower your  values.

 EOL of the tube is a multifactor issue,  including Signal to Noise ratio 
and
 the 'useful signal current' to  'background current' ratio.  The 
'background
 current' is what  you see with no RF signal applied to the tube.  Have 
you
  measured that?  A ratio of 1 is EOL per the HP manual.  If yours is  
about
 4.5 nA, as suggested by the 'off peak' values shown, or  less, you still
 have
 a useful signal and, hopefully, a  useful tube.

 I'd recommend continuing with the  repair.

 Good luck.

  Joe

 -Original Message-
 From:  time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
  Behalf Of Ed Palmer
 Sent: Monday, May 05, 2014 12:46  AM
 To: Discussion of precise time and frequency  measurement
 Subject: [time-nuts] Datum 4065A Cs Tube  Response

 I'm playing with my first Cs standard.   It's a Datum 4065A which 
appears to
 have a dead STEL-1173  synthesizer.  Before I put too much effort into
 replacing  that, I thought I'd check the tube and see if it has any life
  left.  I've attached a chart showing the response of the central  peak.

 My methodology was similar to TVB's as shown  here:
 http://www.leapsecond.com/pages/cspeak except that I  measured the tube
 output directly with a digital voltmeter.   The system is reporting 
wildly
 varying levels for the beam current  so I didn't want to use any of it's
  circuitry.

 Does this look like a usable tube?   Healthy or on it's last legs? What
 response levels are typical for  a Datum 7504A tube?  I see that these
 levels
 are  somewhat lower than those shown on leapsecond for the 5061A tube,  
but
 that could just be the specifics of the  measurement.

 Thanks,

  Ed
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Re: [time-nuts] Low cost GPS module for 100ns timestamping error

[EWKehren]

I am not advertising for DX but I have bought 4 with good results and their 
 units have a 5 V regulator on it. Some have even a TTL to RS converter on  
board.
Bert Kehren
 
 
In a message dated 5/2/2014 11:40:47 P.M. Eastern Daylight Time,  
tn...@toneh.demon.co.uk writes:

On  03/05/2014 00:59, ewkeh...@aol.com wrote:
 Welcome to the nuts  Tony

Thanks, Bert.

 You are not specifying exactly how  accurate time has to be but in my book
 and based on tests the most  reasonable priced GPS with 1 pps is a 
 Ublox 6M
 that  you  can get with antenna for less than $ 22 antenna included from
  _www.DX.com_  (http://www.DX.com) . They have volume discount. 
  Shipping is  very
 slow but included. They seem to be presently  out of the 1 pps version but
 all ublox units have a 1 pps output and I  use with and without and all 
 I do is
   solder a  wire to pin 3.
 Bert Kehren

As I said in my first post I'd like  to achieve an accuracy of better 
than 100ns - or 50ns if possible at  reasonable cost.

I had come across the Ublox 6M when I was looking  earlier, but I 
misunderstood the data sheet and thought it was only the  expensive 
($135) LEA/NEO-6T versions which provided timing. Definitely  worth a 
closer look - the NEO-6M is specced at 30ns RMS which is good  enough. 
The power consumption is a little higher than I would have  liked  at 
37mA/3V, but still rather less than  others.

Thanks,
Tony
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Re: [time-nuts] Low cost GPS module for 100ns timestamping error

[EWKehren]

Tony 
There seem to be many variables. Cost, power, how many, overall stability  
etc. Most likely you will find that the GPS module is not the most expensive 
 part but the VCXO. It also makes a large difference if it is one off or a 
larger  volume is needed. You can always find a bargain, and maybe a close 
out sale but  if you have to look at a continuous supply the picture changes 
dramatically and  also the design.
Bert Kehren
 
 
In a message dated 5/2/2014 11:40:47 P.M. Eastern Daylight Time,  
tn...@toneh.demon.co.uk writes:

On  03/05/2014 00:59, ewkeh...@aol.com wrote:
 Welcome to the nuts  Tony

Thanks, Bert.

 You are not specifying exactly how  accurate time has to be but in my book
 and based on tests the most  reasonable priced GPS with 1 pps is a 
 Ublox 6M
 that  you  can get with antenna for less than $ 22 antenna included from
  _www.DX.com_  (http://www.DX.com) . They have volume discount. 
  Shipping is  very
 slow but included. They seem to be presently  out of the 1 pps version but
 all ublox units have a 1 pps output and I  use with and without and all 
 I do is
   solder a  wire to pin 3.
 Bert Kehren

As I said in my first post I'd like  to achieve an accuracy of better 
than 100ns - or 50ns if possible at  reasonable cost.

I had come across the Ublox 6M when I was looking  earlier, but I 
misunderstood the data sheet and thought it was only the  expensive 
($135) LEA/NEO-6T versions which provided timing. Definitely  worth a 
closer look - the NEO-6M is specced at 30ns RMS which is good  enough. 
The power consumption is a little higher than I would have  liked  at 
37mA/3V, but still rather less than  others.

Thanks,
Tony
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Re: [time-nuts] Low cost GPS module for 100ns timestamping error

[EWKehren]

Welcome to the nuts Tony
You are not specifying exactly how accurate time has to be but in my book  
and based on tests the most reasonable priced GPS with 1 pps is a Ublox 6M 
that  you can get with antenna for less than $ 22 antenna included from 
_www.DX.com_ (http://www.DX.com) . They have volume discount. Shipping is  very 
slow but included. They seem to be presently out of the 1 pps version but  
all ublox units have a 1 pps output and I use with and without and all I do is 
 solder a wire to pin 3.
Bert Kehren
 
 
In a message dated 5/2/2014 7:02:57 P.M. Eastern Daylight Time,  
tn...@toneh.demon.co.uk writes:

Hi, I'm  new here so please be gentle!

I'm considering designing and building  some dataloggers, probably ARM 
Cortex based (eg. STM32F4xx), which record  the time of infrequent 
events, preferably to better than 100ns and if  possible better than 
50nS. The data loggers will be continuously powered,  in fixed locations 
and should have reasonably good views of the sky so the  use of a low 
cost GPS module should be feasible. I believe it shouldn't be  too 
difficult to resolve the PPS timing to +/- 5ns or better with a  100MHz+ 
microcontroller clock, but obviously jitter would add to the error  
requiring the GPS to be better than perhaps 90ns or so worst  case.

Inevitably cost and power constraints apply - ideally the GPS  would cost 
less than $20 (in quantities of 100), and  $15 would be  good, but it 
doesn't seem easy to find very lost cost receivers with  timing outputs 
that are properly specified, presumably because of the  relative market 
volumes. The power consumption of most timing receivers  also seem to be 
higher than navigation units - eg. the Trimble SMT-x spec  is 100mA 
compared to the ADAfruit MTK3339-based module which draws 20mA  (but they 
are a bit too expensive at $24 apiece).

There are several  cheap modules that have PPS outputs but no accuracy 
specification; it's  possible that these could be used with sufficient 
averaging/filtering of  the PPS output. Actually repeatability is the 
important requirement rather  than accuracy as they could be calibrated. 
Perhaps even a PPS o/p is not  absolutely necessary - could the NEMA 
output timing be used given enough  averaging and a sufficiently stable 
oscillator? Compromising the timing  accuracy requirement a bit to say 
150ns may be acceptable if the GPS  device is cheap enough.

I understand that the PPS outputs of some cheap  modules sometimes become 
ill-behaved, but in this application the time  stamp can be adjusted (or 
anomalous clocks ignored) post-event if  necessary to correct for 
temporary disturbances.

This also raises  questions about the short term stability of the 
microcontroller oscillator  required to maintain sufficient accuracy when 
GPS timing is temporarily  lost for some reason - but how long would that 
need to be? 30s? 5 minutes?  30 minutes? An OCXO or a Stratum-3 TXCO 
would be too expensive, but  oscillator manufacturers don't seem to 
publish short term frequency  stability specifications for low cost/low 
power oscillators, and finding  such information isn't easy. Can anyone 
point to figures for a typical  non-TXCO low cost oscillator, 10 or 16MHz?

I did find this study,  http://tf.nist.gov/general/pdf/2276.pdf, 
measuring the stability of some  low cost quartz wristwatches which gives 
some interesting data of 20 to  65ppb Allan deviation over 100s. That, 
but a 32kHz oscillator might give  rise to jitter problems when 
multiplied up to a suitable  frequency.

Some oscillator datasheets specify Allan deviation values,  but I guess 
what I need for estimating worst case timestamp error during  holdover 
periods are actually MTIE values. Is there any way to estimate  the 
latter from Allan deviations specs? Would an ADev of 65 x 10^-9 over  
100s imply up to 6.5us of error after 100s?

Any thoughts?  Thanks,
Tony  H

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Re: [time-nuts] Rb vs.Crystal OCXO

[EWKehren]

The thunderbolt is one of the best timing devices but not for frequency, if 
 you want high resolution. Over time it is ok but high resolution short 
gate  times and you see the frequency changes. They use the OCXO to correct for 
timing  error and if you have a Tracor 527E you can see it. Also how else 
do you think  they control the 1 pps.
Bert Kehren
 
 
In a message dated 4/26/2014 1:52:10 P.M. Eastern Daylight Time,  
csteinm...@yandex.com writes:

Magnus  wrote:

The PRS-10 have a nice little trick in it, it stores the  previous 
OCXO steering value, so on power-up it sets the OCXO to  this

The PRS-10 has quite a number of nice tricks, in addition to  
particularly good engineering and high-quality construction of the  
basic physics package and support circuitry.  The OP (and others)  
should not expect the same level of performance from $30-$100 ebay  
Rubidiums (LPRO, FRS, FE-56xx, etc., etc.).

Very good to excellent  OCXOs are available readily for $5 to 
$50.  IMO, those should be the  standard of comparison for any 
aspiring time nut.  I'm not aware of  any economy Rubidium that has 
close-in phase noise or low-to-medium-tau  AVAR nearly as good as one 
of these very good OCXOs.  As mentioned by  others, some Ru may do 
better than a TCXO close in and at low tau.   But so what?  The TCXO 
should not be a time nut's standard of  comparison as far as a lab 
standard is concerned.

One quickly  concludes that a good GPSDO, which includes a good OCXO, 
is the optimal  solution for most time nuts.  The OCXO has excellent 
stability with  respect to close-in phase noise and low-to-medium-tau 
AVAR, and is  disciplined by the GPS for excellent stability at longer 
tau.   Probably the best turn-key solution is a Trimble Thunderbolt 
(although  prices have risen in the last few years, so they are not 
the bargain they  once were).  Other, less expensive Trimble units 
that are also  supported by the Lady Heather monitoring program are 
available on ebay,  and are probably the best bet today for 
bargain-hunters.  While I  applaud the recent efforts to build simple 
DIY GPSDOs using inexpensive  microcontrollers, from what I have seen 
so far most of them do not yet  have the programming sophistication, 
particularly in the PLL loop filter  and the houskeeping functions, to 
rival a good off-the-shelf GPSDO from a  quality manufacturer.

Final thought for specifying/designing/buying a  GPSDO for time nuts 
purposes:  Do not settle for a low-quality  crystal oscillator (and 
especially not a TCXO).  You will never  achieve best performance at 
tau  about 100 seconds that way.   Insist on a 10811-quality OCXO 
(one of the many nice things about the  Thunderbolt is that it has a 
very good OCXO).

Best  regards,

Charles



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Re: [time-nuts] New timing receivers?

[EWKehren]

And quite a few companies use them.
 
 
In a message dated 4/26/2014 8:27:57 P.M. Eastern Daylight Time,  
li...@rtty.us writes:

Hi

There are a number of timing receivers on the market.  They still are a 
very small percentage of the total units sold. A lot of  people play with the 
uBlox parts.

Bob

On Apr 26, 2014, at 7:59  PM, Jim Miller j...@jtmiller.com wrote:

 I'm reading though  the manual for my recently acquired M12+T which I'm
 looking forward to  using.
 
 I notice that the manual is dated 09FEB05.
  
 So the M12+T has been around for about a decade.
 
 Are  there more recent timing receivers available now or has the ubiquity 
 of
 the consumer GPS market distracted all investment from timing  receivers
 except at the high end?
 
 Thanks
  
 Jim AB3CV
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Re: [time-nuts] How to accurately measure an oscillator's temperature.

[EWKehren]

Chris
 I am not sure if you want to measure temperature or control a fan. To  
measure there are many options depending on how much money you want to spend. 
To control I suggest either a LM 335 or a NTC resistor. I have worked  
extensively with both and for measuring I have now downsized to a YSI. Used to  
have a HP XTAL thermometer.
Spend a lot of time and money on temperature control on Rb's and OCXO's all 
 part of GPSDO's and have come to the conclusion on OCXO's a combination of 
 thermal Isolation and thermal mass is the best solution and on Rb's fans. 
Spend  a year playing with concepts on the FE5680 with all kind of fans and 
heat sinks  and aluminum shapes till it hit me the answer was right in front 
of me. In my  opinion a fan/heat pipe out of an old laptop is the cheapest 
and best solution,  low cost, low noise, no special assemblies and easy to 
control. Use an aluminum  plate as the interface or use the bottom plate 
directly and use one of the  bottom screws to hold your sensor it is internally 
directly tied to the spine of  the Rb. Wide variety available on ebay under 
CPU fan.
Bert Kehren
 
 
In a message dated 4/23/2014 10:38:11 P.M. Eastern Daylight Time,  
albertson.ch...@gmail.com writes:

I have  both an OCXO and an FE-5680 Rb oscillator and I'd like to track
their  temperatures.

What is the best why to measure?   Maybe each  has a different best method

The OCXO is just a small steel can.   Is measuring the steel can temperature
the best why to go.  Epoxy some  kind of sensor to it?

The Rb is mounded to a large heat sink and there  is a fan.  I want to
control the fan so as to keep the Rb temperature  constant.

In both cases I tried using TMP36 three terminal sensors and  just got
noise.  The reported temperature was up and down more than  2C.The fan
controller just chases noise.

BTW the fan  based temperature control is effective.  The FE5680 gets very
warm in  it's box but if I give the 12V fan even 8 volts the heat sink
quickly  cools.  I want to throttle the fan to keep the Rb at  constant
temperature but the temperature data I'm getting is not very  good.

The problem I think is that any sensor I have is on the outside  of the
oscillator and is effected by cooling air   What are  others doing?   What's
the best kind of sensor.

--  

Chris Albertson
Redondo Beach,  California
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Re: [time-nuts] Looking for GPSDO for home use

[EWKehren]

Having done extensive testing on the ublox 6M that you can buy with antenna 
 for less than $ 23 new from DX.com I can say with certainty that the 1 Hz 
pulse  is better than 1 E-9 accurate, closer to E-10. Depending on the 
counter it could  be used to adjust a frequency counter to that accuracy. I am 
not talking time,  it does have a saw tooth element but the period is 
constant. Before some one  says for an extra $ 20 you can get the T version I 
have 
one with M12 imulator  and M12+'s, but the challenge is in making low cost do 
great things.
We do not have the time but some one may want to explore using a PlL with a 
 VCXO using the ! KHz that the 6M can be programmed to. Depending how the 1 
KHz  is generated and the proper filter 1 E-10 may be a possibility.
Bert Kehren
 
 
In a message dated 4/16/2014 11:07:21 A.M. Eastern Daylight Time,  
albertson.ch...@gmail.com writes:

On Tue, Apr 15,  2014 at 10:09 PM, David J Taylor 
david-tay...@blueyonder.co.uk  wrote:

 []
 Even 1 PPS output seems like a workable  starting point, but at the
expense of a different and/or more difficult  path to get to a 10 MHz
reference signal I seek.

 Any  advance or pointer to source (reasonable cost, whatever that means!)
would  be appreciated.


Any GPS receiver with 1PPS is OK.All  PPS signals are interchangeable.
It is just a 5 volt 1Hz square wave.   The raising edge of the wave is
right at the tick of a new  second.

The GPSDO is simple too.  It counts the cycles of the  10MHz oscillator from
one PPS raising edge to the next and it should get  exactly 10,000,000
cycles.   If more or less are counted the  software moves the voltage on
OXCO's control pin up or  down.

Controllers can be more complex, but this much will get you  started.  The
simplest next step is to count for 10 seconds and get to  0.1 Hz then add an
interpolator and get to milli Hz

If you are going  to buy and set up a GPS receiver. The hardest part is the
antenna.  It  is best if it can see the entire sky, horizon to horizon and
if it is not  near any reflecting surfaces.  It is best if the antenna is
mounted on  a mast on the tallest building but a modern GPS will work if the
antenna is  playing on the desk near a window.  You can connect a computer
and get  software to plot data from inside the GPS but really all you need
to go is  apply power and get the PPS.

The old Motorola Oncore series of GPS is  reliable and low cost.   The
UT has a PPS one sigma error of  about 50 nanoseconds which is good
enough  they sell for under  $20.   The current new state of the art
version is about $60 or  $35 used.
Here is an  example
Motorola-UT-Plus-Oncore-Timing-GPS-Modulehttp://www.ebay.com/itm/ONLY-1PSC-
Motorola-UT-Plus-Oncore-Timing-GPS-Module-1pps-NTP-/301132856857?pt=US_Ham_R
adio_Transmittershash=item461ceabe19
Be  SURE to buy the timing version.  There are non-timing or  navigation
versions.  Make sure it says timing in the  description.

GPS receivers spew out tons of data but you can ignore it  all.  All you
need is the PPS signal.

-- 

Chris  Albertson
Redondo Beach,  California
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Re: [time-nuts] GPS antenna in silicon/RTV encapsulation

[EWKehren]

The Gerber Baby Food Jar at Wall Mart $ 0.49 
 
 
In a message dated 4/15/2014 1:03:40 P.M. Eastern Daylight Time,  
jim...@earthlink.net writes:

On  4/15/14, 8:13 AM, ewkeh...@aol.com wrote:
 Working off list on a super  high performance GPSDO but low cost thanks 
to a
   time nut  (sorry forgot his name) he directed me to DX.com which have 
ublox
  with  antenna for lwss than $ 23. Super performance and though they are  
out
 of the one  with 1 pps all you have to do is solder directly  to the 
module.
 Have both  versions. Attached you see what I did  with the antenna but 
found
 out the hard  way that when it rains  the concave bottom fills with water,
 still works but not  as  good. So last night I made it flat with 3M Marine
 5200 slow cure that  I have  extensive experience with from boating. Will 
take a
 full  week to cure but if it  does not work I can always remove it and  
start
 over


There is a similar approach using a small  display dome which is 
basically a round bottom beaker kind of shape  designed to go on a wooden 
base. It can just as easily go on a big cork or  stopper, or a disk cut 
out of a HDPE cutting board.


Googling  display dome will show you copious choices. or somewhere like  
glassdomes.com

Of course, if you have a supply of canning jars or  babyfood jars, then 
you can use those. Nothing says the jar has to be  mounted with the axis 
vertical. You could do it sideways (like a ship in a  bottle) to help 
solve the rain in the punt  problem.


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Re: [time-nuts] GPS antenna in silicon/RTV encapsulation

[EWKehren]

Having five GPSDO's running and some for over 14 years I have a very  
sophisticated and expensive antenna system. This is part of a project that with 
 
the disappearance of Tbolts and other commercial GPSDO's to make available 
to  time nuts state of the art performance at an affordable price, 
specifically  those that have a hard time justifying large expenditures. To me 
the fun 
is in  the challenge and maximum performance at minimum cost is fun. Stay 
tuned.
Bert Kehren.
 
 
In a message dated 4/15/2014 4:05:38 P.M. Eastern Daylight Time,  
albertson.ch...@gmail.com writes:

Actually I used  a home canning type wide mouth mason jar.I thought
about a  fish bowl but there are not threads for mounting.   Then I  got
smarter and spend $29 on a real timing antenna and it''s been on the  roof
for years.  The jar on a stick works but has very poor  WAF.


On Tue, Apr 15, 2014 at 12:05 PM, Jim Lux  jim...@earthlink.net wrote:

 On 4/15/14, 11:02 AM,  ewkeh...@aol.com wrote:

 The Gerber Baby Food Jar at Wall  Mart $ 0.49

  Is there a particular kind of food  that works best? Perhaps strained
 prunes has the best  regularity?


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-- 

Chris  Albertson
Redondo Beach,  California
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Re: [time-nuts] GPS antenna in silicon/RTV encapsulation

[EWKehren]

Washed all three down the sink
Bert Kehren
 
 
In a message dated 4/15/2014 3:18:34 P.M. Eastern Daylight Time,  
jim...@earthlink.net writes:

On  4/15/14, 11:02 AM, ewkeh...@aol.com wrote:
 The Gerber Baby Food Jar at  Wall Mart $ 0.49

Is there a particular kind of food that works  best? Perhaps strained 
prunes has the best  regularity?


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[time-nuts] GPS antenna in silicon/RTV encapsulation

[EWKehren]

Am experimenting with small low cost GPS antennas and am considering as an  
alternative RTV/silicon. Any information on RF attenuation of RTV/silicon 
at 1.6  GHz ?
Bert Kehren
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Re: [time-nuts] FEI-5660 Rubidium Oscillator

[EWKehren]

All Rb's have XO's and with the exception of the HP5065C all Rb's influence 
 long term stability only the only exception is the HP which uses a TC 
below  0.1.sec, and as Corbe demonstrated ADEV is controlled below 1 sec. by 
the 
cell.  The same can not be said with other Rb's.
Bert Kehren
 
 
In a message dated 3/28/2014 7:33:45 A.M. Eastern Daylight Time,  
li...@rtty.us writes:

Hi

Crystals are susceptible to vibration. That’s pretty well  documented. They 
have resonances in the mount structure. They have a 2G tip  sensitivity. 

Audio when it “impacts” an oscillator induces vibration.  If your noise 
source is a rocket engine, then the vibration is “non trivial”.  You do 
indeed see phase noise on the oscillator from audio  …

Bob

On Mar 27, 2014, at 11:42 PM, Tom Van Baak  t...@leapsecond.com wrote:

 More seriously, I'm assuming  you're advocating rock for the thermal 
mass 
 and/or  mechanical.  What about a 100 pound box of sand?
 
  Mechanical. I figured a OCXO might be susceptible to microphonics, 
especially  in a recording studio. But if it's down to the level of 1 lsb of 
the 
digital  sampling, then no worries.
 
 Has anyone on the list ever  measured this effect, even on a cheap 
crystal?
 
 /tvb
  
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Re: [time-nuts] Using GPS to Fine Tune a Rubidium Frequency Standard.

[EWKehren]

The QEX unit is a spin off of the Shera, how ever the DAC is only 12 bits  
covering the full tuning range of the Rb. Shera does it better with 18 bits 
and  has additional features. I would not spend the money to get a copy.
Bert Kehren
 
 
In a message dated 3/28/2014 2:42:55 P.M. Eastern Daylight Time,  
mgeo...@tuffmail.us writes:

Anders:

I am a QEX subscriber and have that issue but I  haven't built
the circuit.

The author referenced Brooks Shera as the  basis for his work.

He uses a Trimble Resolution T GPS for a PPS  reference and an
LPRO-101 Rubidium oscillator for the 10MHz.
His circuit  divides the 10MHz output from Rb by 100 and
compares the phase of the  100kHz against the PPS.
A PIC16 MCU is the controller and uses the phase  data to control
an external DAC to drive the Rb frequency control  pin.

There were a couple of other time  frequency related articles  in 2013
if you decide to get the CD.

Mike

On 3/21/2014 09:20,  Anders Time wrote:
 Does anyone have a copy of the QEX 2013 november  article(Bill Kaune) 
Using
 GPS to Fine Tune a Rubidium Frequency  Standard?

 I´m really interested in this subject, but I can´t  find this magazine in
 Sweden. I have contacted QEX, but it is very  difficult to buy 
back-issues.

 Have any one built this  frequency standard and can tell me more about the
 project?
 You  can access the source code for the project here:
  
http://www.arrl.org/files/file/QEX%20Binaries/2013/November_13/11x13_Kaune_PIC_Code.zip

  /Anders
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Re: [time-nuts] Hanging bridge question

[EWKehren]

The lowest cost solution is a DS chip in combination with a PIC. How ever  
has any one thought about a fix by going to the source of the problem. The 
TCXO.  Use a DDS with internal multiplier like the AD9851 or AD 9913 and use 
the  sawtooth message from the GRS receiver and change the frequency. An 
other  alternative would be to use the sawtooth word to fine tune a TCXO or any 
VCXO  for that matter.
Bert Kehren
 
 
In a message dated 3/25/2014 7:28:11 A.M. Eastern Daylight Time,  
p...@phk.freebsd.dk writes:

In  message 6b362a4d-834a-4733-bed8-fcfec0ccb...@rtty.us, Bob Camp  
writes:

I should add here, that you _can_ do a little bit better than  the
sawtooth correction.

We know, or at least assume, that the GPS's  internal clock is step-less
and slowly changing, so if you put a predictive  filter on this stuff,
it can actually do a reasonable job at estimating  which way the rounding
of the sawtooth correction went (since it is  integral ns).

This reduces the random rounding error on the sawtooth  correction
from +/- 0.5 ns to something like +/- 0.3 ns.

Totally not  worth it, but a cool and educational project :-)

-- 
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] Hanging bridge question

[EWKehren]

Yes if you want to use it only in a GPSDO and it is being done but if you  
are a time nut you may want the 1 PPS..
Bert Kehren
 
 
In a message dated 3/25/2014 6:33:12 P.M. Eastern Daylight Time,  
albertson.ch...@gmail.com writes:

On Tue,  Mar 25, 2014 at 5:44 AM, ewkeh...@aol.com wrote:

 The  lowest cost solution is a DS chip in combination with a PIC. How  
ever


The lowest cost solution is to do the correct entirely in  software.
After the measure the phase, simply add the  correction.

All you need to know is the phase.  There is not point  in correcting
the pulse, you don't need a corrected pulse.  What you  want is a
measurement of the phase.


Chris Albertson
Redondo  Beach,  California
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