Re: [time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?

[Bruce Griffiths]

The better ones use optically contacted crystals to avoid browning of the 
adhesive due to the high power densities of the 1064nm laser required for 
efficient frequency doubling.

Brue
> On 11 June 2018 at 22:52 Dana Whitlow  wrote:
> 
> 
> Mark's description about how (most) green laser pointers work The better is a 
> bit in
> error, and is perhaps
> over-simplified- the reality is actually more fascinating yet:
> 
> First a diode laser operating at around 808 or 809 nm is used to optically
> pump a solid
> state laser which generates light at 1064 nm.  This light is then frequency
> doubled with an
> intra-cavity nonlinear element to produce the final  output at 532 nm.
>  For all this to work
> the optical elements must be critically aligned, and to me the most amazing
> thing about
> the low selling price is how this alignment is effected so cheaply.  One of
> these units I've
> opened up has the doubler crystal held down by a lump of cement on one
> side- it looks
> for all the world like it must have pushed into alignment and "held" there
> while the cement
> was cured.  Green pointers made in this way are characterized by quite good
> beam quality
> and very little wavelength spread from unit to unit. However, they are
> generally quite
> delicate and ruined by mechanical shock.
> 
> Although not commonly known, at least one outfit (Z-Bolt) is now selling
> "direct diode"
> green pointers, where there is just one laser which emits directly in the
> green, at around
> 515-530 nm.   These are much more robust, operate well over a wider
> temperature range,
> but have the usual poor beam quality (non-circular beam with some residual
> astigmatism)
> characteristic of diode lasers made with simple collimating optics.  And,
> the output
> wavelength spread from unit to unit is quite large.
> 
> Dana
> 
> 
> On Mon, Jun 11, 2018 at 2:43 AM, Mark Sims  wrote:
> 
> > Well, no.  Green laser pointers convert a rather high power 800 nm laser
> > to 1600 nm in one crystal then divide it to 533 nm in another one.   The
> > physics and manufacturing of them is best described as black magic.  They
> > are cheap because China developed the process to grow the crystals in bulk
> > and crank out zillions of them for consumer products.
> >
> > I suspect that a 1600-ish nm to 800-ish nm converter is not a stock
> > consumer-quantity device and will cost a pretty penny or two... like a
> > red/IR laser diode can be had for 50 cents and a telecom VCSEL diode can be
> > $500.
> >
> > --
> >
> > > It cannot be too much, given the fact that these are used in
> > green laser pointers.
> > ___
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> >
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Re: [time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?

[Bruce Griffiths]

PPLN (Periodically poled lithium Niobate) is the frequency doubler of choice 
for such applications however it needs to operated in a temperature regulated 
oven. 
To achieve efficient frequency doubling the input light needs to remain in sync 
with the frequency doubled output light as they propagate through the frequency 
doubler. The frequency doubler Crystal optical dispersion and directional 
dependent propagation ensures that a crystal aligned for 164/532nm operation is 
unlikely to function effectively for 1680/890nm operation.
PPLN however works well over a wide bandwidth.

Bruce
> On 11 June 2018 at 19:43 Mark Sims  wrote:
> 
> 
> Well, no.  Green laser pointers convert a rather high power 800 nm laser to 
> 1600 nm in one crystal then divide it to 533 nm in another one.   The physics 
> and manufacturing of them is best described as black magic.  They are cheap 
> because China developed the process to grow the crystals in bulk  and crank 
> out zillions of them for consumer products. 
> 
> I suspect that a 1600-ish nm to 800-ish nm converter is not a stock 
> consumer-quantity device and will cost a pretty penny or two... like a red/IR 
> laser diode can be had for 50 cents and a telecom VCSEL diode can be $500.
>  
> --
> 
> > It cannot be too much, given the fact that these are used in
> green laser pointers.
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Re: [time-nuts] ?==?utf-8?q? a newbie question: where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?

[Bruce Griffiths]

The output wavelength of a VCSEL is current and temperature dependent so using 
a low noise current source and regulating the chip temperature is usually 
necessary to allow locking to an atomic transition.
Most VCSELS for such applications include a peltier module within the housing.

Bruce 
> On 11 June 2018 at 19:26 Attila Kinali  wrote:
> 
> 
> On Mon, 11 Jun 2018 06:53:49 +0200
> Magnus Danielson  wrote:
> 
> > One might then ask what the availability and pricetag is for nonlinear
> > chrystal needed for frequency doubling.
> 
> It cannot be too much, given the fact that these are used in
> green laser pointers.
> 
> Though, I have to say I am astonished how expensive those VCSEL are.
> I would have guessed they are below $100/pcs, given that "normal"
> laser diodes are usually in the order of $10-$20.
> 
> 
>   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] a newbie question: where can I purchase 794.7nm VCSEL for building CPT rubidium clock?

[Bruce Griffiths]

Theres also

http://www.photonics.philips.com/application-areas/sensing/components

and

https://www.sacher-laser.com/home/industriallasers/point_and_line_laser_module/industrial_laser_modules/micron_laser.html
Bruce
> On 09 June 2018 at 20:54 mimitech mimitech  wrote:
> 
> 
> Thanks Attila for your suggestion.
> 
> I prefer the 780/795nm VCSEL scheme for its simplicity. After some
> searching, looks like the 780nm VCSELs are also not easy to source,
> although other types of 780nm LD are common.
> 
> I have purchased small amount of Vixar P/N “795S--BC01” 795nm single
> mode VCSEL from a local distributor, price is about $500/pcs. I'm not sure
> whether this model could work in CPT rubidium clock.
> 
> A more suitable model maybe Oclaro P/N “APM2101013300” 795nm single mode
> VCSEL, with unit price $800, which was proved to work as this paper
> "A compact atomic magnetometer for cubesats",
> https://open.bu.edu/bitstream/handle/2144/16303/Knechtel_bu_0017N_11402.pdf
> ,
> 
> this thesis "Ultra-Low Phase Noise Atomic Clock using Coherent Population
> Trapping (CPT) in Rubidium"
> http://etheses.whiterose.ac.uk/20073/1/Burtichelov_PhD_Thesis_with_papers_V7.pdf
> 
> and also it was used in commercial CPT rubidium clock - Microsemi SA.3xm
> series. The cheapest model is SA.31m priced about $1100 at Digikey /
> Mouser.
> 
> Another paper "VCSEL Laser System for Atomic Clocks"
> http://ixnovi.people.wm.edu/documents/NathanBelcherREUPaper.pdf test
> several VCSEL from different vendors and found the ULM 794.7 nm single mode
> VCSEL can work.
> 
> Thanks.
> 
> mimitech.
> 
> 
> On Tue, 5 Jun 2018 11:11:59 +0200, Attila Kinali  wrote:
> >
> > On Mon, 4 Jun 2018 21:31:56 +0800
> > mimitech mimitech  wrote:
> >
> > > I'm planning to build a CPT (coherent-population-trapping) rubidium
> clock
> > > as my next hobby project. The main purpose is to learn the principles
> > > behind CPT rubidium clock, and hopefully got similar or better
> performance
> > > than commercial miniature rubidium clock such as FE-5680A.
> >
> > Building a CPT clock is slightly more involved than you might think
> > at first. The laser diode is only one part of it. You will most likely
> > be able to improve on the short-term stability of the FE-5680 (which
> > is rather poor). But I doubt you will be able to improve much on
> > the long term stability, which is where things actually become
> interesting,
> > if you use a naive approach.
> >
> > Nevertheless, I have not seen many 794/795nm diodes around. The only
> > one that I have the datasheet of is the one from Vixar.
> > You might want want to consider going for the D2 line instead of the
> > D1 line, as 780nm diodes are more commonly available than 795nm. You will
> > also need to buy several of those and select the ones that come closest
> > to the wavelength at the desired opearating conditions (usuall spread
> > is +/-1nm to +/-10nm). Do not assume you can tune more than 0.1nm with
> > temperature and current (rule of thumb is that you get about 10GHz
> > per °C and mA). If you need more tuning range, you will need to add an
> > external cavity (can give you up to 5nm range), which then needs to be
> > tuned to the 3.45GHz (ie it's length needs to be approximately 8-9cm).
> >
> > Alternatively, you can get two S1-0780-XXX from Sacher Laser
> > (cost IIRC 2500€ each) and keep them 6.9GHz apart (using an optical PLL).
> > If you have enough money to spend, I'd go for two Cateye diode laser CEL's
> > from Moglabs (cost AFAIK 5000€ each)
> >
> > No matter what you choose, you will need some wavelength stabilization
> > scheme. You can either do that with the vapor cell itself or use
> > an additional cell and do a DVALL or a saturated absorption locking.
> > Note that this addtional cell will need to be without buffer gas.
> > An external cell will offer better stability and thus lower noise,
> > which directly translates into higher stability.
> >
> > As polarisation scheme, I suggest using σ+/σ- as it seems to be more
> > robust than the lin/lin schemes.
> >
> > 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] Anybody have suggestions for time related science fair projects?

[Bruce Griffiths]

At telecom wavelengths GDD can be quite low.
Laser source spectral widths can also be low.
At visible wavelengths an fiber length imbalance of 1m with a 1nm bandwidth 
light source makes interferometry impossible/difficult without GDD compensation 
even if delays are matched.
The moodulation bandwidth isnt an issue for this application but with a long 
enough fiber the source spectral bandwidth may be.
Polarisation locked single transverse mode VCSELs are inexpensive and typically 
have spectral bandwidths of 100MHz or so.


Bruce
> On 13 May 2018 at 11:31 Dana Whitlow <k8yumdoo...@gmail.com> wrote:
> 
> 
> Indeed; however, with single mode fiber the limit is not too bad.  At
> Arecibo we routinely ran bandwidths in
> excess of 1 GHz through fibers of about 1500 ft length with no problems.
> For the science fair project a
> bandwidth of a few MHz should suffice for lengths of, say, 500 ft.  It's
> just that I don't know how bad the
> multimode dispersion problem would be when using shorter wavelengths, and
> I'm sure not equipped to
> make any measurements at home now that I'm retired and far away from the
> observatory.
> 
> Dana
> 
> 
> On Sat, May 12, 2018 at 5:44 PM, Bruce Griffiths <bruce.griffi...@xtra.co.nz
> > wrote:
> 
> > Even with single mode fiber its finite group delay dispersion will likely
> > restrict the usable light source bandwidth.
> >
> > Bruce
> > > On 13 May 2018 at 03:38 Dana Whitlow <k8yumdoo...@gmail.com> wrote:
> > >
> > >
> > > It may  be that a nicely-written request to Corning could yield the loan
> > of
> > > a big spool of fiber
> > > for the duration of a science fair project.
> > >
> > > Another alternative, perhaps easier to implement, might be an
> > > electrically-driven light modulator
> > > at the detector end.  For the source, an LED or diode laser is easy to
> > > modulate at respectable
> > > rates.  This approach should allow use of such high frequencies that an
> > > open optical path using
> > > mirrors might even suffice.
> > >
> > > Or here's an intermediate scheme:
> > > If one were to use two modulated sources (or one with a beamsplitter),
> > with
> > > one path delayed
> > > by the long(ish) fiber and the other by a minimal-length local fiber,
> > > something resembling a streak
> > > camera (implemented with a rotating mirror) might permit use of
> > > substantially higher pulse rates
> > > than with a rotating disk, without incurring the need for anything very
> > > fancy in the way of mechanics.
> > > Only the modulated source should require a reasonably accurate drive
> > > frequency- the "detector"
> > > would be essentially self-calibrating.  A small mirror, say of cm size,
> > > could probably be safely
> > > rotated at Dremel speeds approaching 500 rev/s, and if 1 mrad angular
> > > resolution is attained,
> > > this would yield a resolution of ~160 ns.  So a fiber length of 500 ft
> > > (approx 750 ns one-way delay)
> > > should yield an angular separation of nearly five "dots" between delayed
> > > and undelayed dots.
> > > And if the sources are modulated at a rate such that a few pulse
> > > repetitions are visible in the
> > > field of view, the scheme is self-calibrating as long as the PRF and the
> > > velocity factor in the fiber
> > > are known.  Probably the only precision work would be the optics required
> > > to focus a reasonable
> > > amount of light from the source(s) onto the two fibers., and I believe
> > this
> > > requirement could be
> > > adequately met with microscope objectives borrowed from one's school's
> > > biology lab.
> > >
> > > A fly in the ointment is that if ordinary (read, inexpensive) IR fiber is
> > > used at convenient visible
> > > wavelengths, propagation will occur in more than one spatial mode, with
> > > different modes propagating
> > > at different speeds.   I don't know how much of a problem this would
> > > raise.  But it may be that if
> > > tweaking of the transmitting end illumination is done, both in angle and
> > > transverse position, most
> > > of the propagating light could be confined to a single mode.  I speak of
> > > visible wavelengths simply
> > > because using these avoids the cost of electronic detectors,
> > oscilloscopes,
> > > etc, potentially saving
> > > a lot on the cost of the experiment as well as making for a mor

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

[Bruce Griffiths]

Even with single mode fiber its finite group delay dispersion will likely 
restrict the usable light source bandwidth.

Bruce
> On 13 May 2018 at 03:38 Dana Whitlow  wrote:
> 
> 
> It may  be that a nicely-written request to Corning could yield the loan of
> a big spool of fiber 
> for the duration of a science fair project.
> 
> Another alternative, perhaps easier to implement, might be an
> electrically-driven light modulator
> at the detector end.  For the source, an LED or diode laser is easy to
> modulate at respectable
> rates.  This approach should allow use of such high frequencies that an
> open optical path using
> mirrors might even suffice.
> 
> Or here's an intermediate scheme:
> If one were to use two modulated sources (or one with a beamsplitter), with
> one path delayed
> by the long(ish) fiber and the other by a minimal-length local fiber,
> something resembling a streak
> camera (implemented with a rotating mirror) might permit use of
> substantially higher pulse rates
> than with a rotating disk, without incurring the need for anything very
> fancy in the way of mechanics.
> Only the modulated source should require a reasonably accurate drive
> frequency- the "detector"
> would be essentially self-calibrating.  A small mirror, say of cm size,
> could probably be safely
> rotated at Dremel speeds approaching 500 rev/s, and if 1 mrad angular
> resolution is attained,
> this would yield a resolution of ~160 ns.  So a fiber length of 500 ft
> (approx 750 ns one-way delay)
> should yield an angular separation of nearly five "dots" between delayed
> and undelayed dots.
> And if the sources are modulated at a rate such that a few pulse
> repetitions are visible in the
> field of view, the scheme is self-calibrating as long as the PRF and the
> velocity factor in the fiber
> are known.  Probably the only precision work would be the optics required
> to focus a reasonable
> amount of light from the source(s) onto the two fibers., and I believe this
> requirement could be
> adequately met with microscope objectives borrowed from one's school's
> biology lab.
> 
> A fly in the ointment is that if ordinary (read, inexpensive) IR fiber is
> used at convenient visible
> wavelengths, propagation will occur in more than one spatial mode, with
> different modes propagating
> at different speeds.   I don't know how much of a problem this would
> raise.  But it may be that if
> tweaking of the transmitting end illumination is done, both in angle and
> transverse position, most
> of the propagating light could be confined to a single mode.  I speak of
> visible wavelengths simply
> because using these avoids the cost of electronic detectors, oscilloscopes,
> etc, potentially saving
> a lot on the cost of the experiment as well as making for a more satisfying
> presentation.
> 
> Dana
> 
> 
> On Sat, May 12, 2018 at 9:45 AM, Bob kb8tq  wrote:
> 
> > Hi
> >
> >
> >
> > > On May 12, 2018, at 7:01 AM, jimlux  wrote:
> > >
> > > On 5/11/18 9:08 PM, Jeff Woolsey wrote:
> > >> David.vanhorn wrote:
> > >>> Measuring the speed of light (Fizeau or Michelson method? Other ways)
> > >>>
> > >>>
> > >>> I saw a great demo of this at the Exploratorium in SF.  They had a
> > long spool of fiber optic, a disc with holes, and a light source.  When
> > static, if the light shines through the hole in the disc into the fiber,
> > then you can see the light coming out the other end of the fiber through a
> > different hole.   When rotating, you increase speed and the fiber output
> > gets dimmer and dimmer till it's gone.   At that point, the light going
> > into the fiber arrives when the other end is blocked, and vice versa.  High
> > tech, but simple.
> > >>>
> > >> My favorite exhibit that we never see anymore.   IIRC it was a quarter
> > >> mile of fiber and a green laser.  And ISTR that the disc had one hole on
> > >> one arm and two radially on the other, but I can't remember why.  I
> > >> thought that the light would pass through the same hole twice, once on
> > >> the way in and on the way out when that same hole rotated 180 degrees to
> > >> the other end of the fiber.  The disk spun somewhere around 50 rps (60
> > >> with an AC motor?).
> > >
> > >
> > > 1km in free space would be 6 microseconds round trip. I'm not sure a
> > disk spinning at 3600 rpm would work.  you'd need to have the "hole
> > spacing" be on the order of 6 microseconds - and at 100 rps (6000 RPM), 10
> > ms/rev, you'd need the sending and receiving hole 6/1 of a rev apart
> > (about 0.2 degrees).
> > >
> > > if you had 10 km of fiber, it would be a bit easier.
> >
> > I think the term “long fiber” in this case should really be “very very
> > long”.  Exactly how the typical student
> > funds the acquisition of something in the “many miles” range, I have no
> > idea.
> >
> > You could use an optical grating of some sort as your “spinning disk”. The
> > end of the fiber is going to be

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

[Bruce Griffiths]

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

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

[Bruce Griffiths]

Thus a DDMTD using NB7V52's as the mixers should have useful performance

Bruce 
> On 14 April 2018 at 03:54 John Larkin  wrote:
> 
> 
> If you walk the differential data and clock inputs of an NB7V52  CML 
> flipflop across one another in time, the equivalent jitter is below 20 
> fs RMS. That's what we're measuring, but our test rig may well dominate 
> the jitter, so the flop is probably better.
> 
> We're using this to test the jitter of some of our timing products, with 
> 1/10 the noise floor and 1e-4 times the cost of other ways to do it.
> 
> https://www.dropbox.com/s/1i2yz7otty94o9l/NB7_Jitter_1.jpg?raw=1
> 
> https://www.dropbox.com/s/qahpb8uh1xr53vj/NB7_Steps.jpg?raw=1
> 
> https://www.dropbox.com/s/tpphhi79yxgzy34/NB7_tc.jpg?raw=1
> 
> 
> -- 
> ** arb
> 
> John Larkin, President
> Highland Technology, Inc
> 18 Otis Street
> San Francisco, CA 94103
> 
> phone 415 551-1700   fax 551-5129
> jjlar...@highlandtechnology.com
> http://www.highlandtechnology.com
> 
> This is a Highland Technology confidential communication
> 
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Re: [time-nuts] Wavecrest DTS2075

[Bruce Griffiths]

Its more accurate and has less measurement noise than the SR620.

The input bandwidth is also greater.

The accuracy is no better than that of a modern TDC chip, however its 
measurement noise is lower.

Bruce

> 
> On 11 April 2018 at 07:17 Gerhard Hoffmann  wrote:
> 
> I have been offered a DTS2075. Is this generally regarded as a step
> 
> forward if you already have a SR620 or is it more or less the same
> 
> league? Are there any hidden pearls or caveats?
> 
> TIA and best regards,
> 
> Gerhard
> 
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Re: [time-nuts] GPS ANTENNA

[Bruce Griffiths]

Just use a standard attenuator between a pair of bias T's with their dc ports 
connected together.

Bruce

> 
> On 02 April 2018 at 10:29 Azelio Boriani  wrote:
> 
> An unusual attenuator with a DC pass.
> 
> On Sun, Apr 1, 2018 at 10:21 PM, David C. Partridge
> 
>  wrote:
> 
> > > 
> > Or use a choke ring survey antenna and an attenuator :)
> > 
> > Dave
> > 
> > -Original Message-
> > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of 
> > Bob kb8tq
> > Sent: 01 April 2018 14:43
> > To: Discussion of precise time and frequency measurement
> > Subject: Re: [time-nuts] GPS ANTENNA
> > 
> > Hi
> > 
> > Indeed, it is *very* easy to put to much gain in front of a timing 
> > GNSS receiver. These beasts are trying to dig out a signal that you can’t 
> > even see with a spectrum analyzer.
> > It’s way to far below the noise floor to detect that way. They 
> > optimize things pretty tightly to get that done (and to hit a price target 
> > ….). Put to much gain in front of them and they get unhappy.
> > 
> > Making this even more crazy, the survey industry standard antenna 
> > *does* have a lot of gain. Survey receivers need way more gain in front of 
> > them than timing receivers. Put a survey antenna directly on a timing 
> > device and trouble will likely be the outcome. Equally, a survey instrument 
> > probably will not be happy with a timing receiver.
> > 
> > Why all this nonsense? As far as I can tell, it goes back to how 
> > the very early L1 / L2 survey boxes were designed back in the 1980’s and 
> > early 1990’s. They made a basic decision to put a lot of gain at the 
> > antenna. Motorola came along with their GPS modules later on. They made a 
> > *very* different decision about how to distribute the gain. There are very 
> > good arguments on both sides for why they did it this way.
> > The bottom line is still - you need to match things up …
> > 
> > Bob
> > 
> > > > > 
> > > On Apr 1, 2018, at 2:36 AM, cfo  wrote:
> > > 
> > > On Sat, 31 Mar 2018 10:58:19 -0500,
> > > donandarline-Re5JQEeQqe8AvxtiuMwx3w
> > > wrote:
> > > 
> > > > > > > 
> > > > I found a supplier for high quality GPS antennas at a 
> > > > very reasonable
> > > > price. PCTEL GPSL1-TMG-SPI-40NCB.
> > > > 
> > > > > > > 
> > > *** SNIP ***
> > > 
> > > I had one of those on 25m cable, and it worked fine on a 
> > > Tbolt , until
> > > i got an active antenna splitter that also had some gain.
> > > Then i had to replace it w. a 26dB version of same type, else 
> > > the
> > > "Jackson Lite" was loosing sync.
> > > 
> > > What i mean here, is that you can get too much gain too.
> > > 
> > > Btw: Good price.
> > > 
> > > CFO
> > > Denmark
> > > 
> > > ___
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> > > go to
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> > > and follow the instructions there.
> > > 
> > > > > 
> > ___
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> > and follow the instructions there.
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> > > 
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Re: [time-nuts] ULN regulator with more current capability than LT3042?

[Bruce Griffiths]

I have a quad LT3042 board somewhere.
I should get around to measuring its output noise.

Bruce 
> On 20 March 2018 at 03:11 John Ackermann N8UR  wrote:
> 
> 
> Thanks, all.  I think I'll end up using the 3042 with pass transistor, 
> partly for reasons of cost.  I have no idea whether paralleling two 
> 3042s would result in lower noise from the device, and there are already 
> three or four fairly pricey chips on the board.
> 
> I appreciate all the info!
> 
> John
> 
> 
> On 03/18/2018 06:43 PM, Charles Steinmetz wrote:
> > Tom wrote:
> > 
> >> Run two in parallel for twice the current and less noise?
> > 
> > This is actually a better solution than using an LT3045, for two 
> > reasons.  First, as Tom noted, by paralleling two devices, the noise is 
> > reduced by sqrt 2 = ~1.4:
> > 
> > "Designed as a precision current reference followed by a high 
> > performance voltage buffer, the LT3042 is easily paralleled to increase 
> > output current, spread heat on the PCB and further reduce noise -- 
> > output noise decreases by the square-root of the number of devices in 
> > parallel."  [LT Journal of Analog Innovation, v25 n1 Apr 2015]. 
> > 
> > 
> > Second, it reduces the dissipation of each regulator, so they run 
> > cooler.  And as LT says, it allows spreading the heat on the board (but 
> > it is not advisable to put them too far apart).
> > 
> > The primary disadvantage is that two 3042s cost about half again more 
> > than one 3045.  Also, board space may be a factor in some applications.
> > 
> > So, unless you are extremely tight on board space or the ~1.5x cost 
> > increase is prohibitive, two 3042s in parallel are a better solution 
> > than one 3045 if you are seeking the lowest noise possible.
> > 
> > Best regards,
> > 
> > Charles
> > 
> > 
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Re: [time-nuts] ULN regulator with more current capability than LT3042?

[Bruce Griffiths]

The details are on the LT3042 datasheet.

A small series ballast resistor is used in series with each output and the Iref 
terminals are connected in parallel so only the offset of the unity gain output 
buffer is of significance.

Bruce

> 
> On 20 March 2018 at 02:23 Peter Vince  wrote:
> 
> Please forgive this naive question, but I am concerned about the idea of
> simply running two regulators in parallel. Just like you don't put two
> batteries in parallel, how do you ensure accurate load balancing between
> the two? I would worry that one of them, with a fractionally higher
> voltage, would be driven into saturation, thus ruining any noise
> isolation. I must be missing something here?
> 
> Peter
> 
> On 18 March 2018 at 22:43, Charles Steinmetz  
> wrote:
> 
> > > 
> > Tom wrote:
> > 
> > Run two in parallel for twice the current and less noise?
> > >
> > 
> > This is actually a better solution than using an LT3045, for two 
> > reasons.
> > First, as Tom noted, by paralleling two devices, the noise is 
> > reduced by
> > sqrt 2 = ~1.4:
> > 
> > "Designed as a precision current reference followed by a high 
> > performance
> > voltage buffer, the LT3042 is easily paralleled to increase output 
> > current,
> > spread heat on the PCB and further reduce noise -- output noise 
> > decreases
> > by the square-root of the number of devices in parallel." [LT 
> > Journal of
> > Analog Innovation, v25 n1 Apr 2015]. 
> > 
> > 
> > Second, it reduces the dissipation of each regulator, so they run 
> > cooler.
> > And as LT says, it allows spreading the heat on the board (but it 
> > is not
> > advisable to put them too far apart).
> > 
> > The primary disadvantage is that two 3042s cost about half again 
> > more than
> > one 3045. Also, board space may be a factor in some applications.
> > 
> > So, unless you are extremely tight on board space or the ~1.5x cost
> > increase is prohibitive, two 3042s in parallel are a better 
> > solution than
> > one 3045 if you are seeking the lowest noise possible.
> > 
> > Best regards,
> > 
> > Charles
> > 
> > ___
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> > ailman/listinfo/time-nuts
> > and follow the instructions there.
> > 
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> > 
> > > 
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Re: [time-nuts] ULN regulator with more current capability than LT3042?

[Bruce Griffiths]

Use an LT3045, its the 0.5A version of the LT3042.

Bruce
> On 19 March 2018 at 09:13 John Ackermann N8UR  wrote:
> 
> 
> Reviving the conversation about superb voltage regulators, I am looking 
> for one to run the analog and PLL bits of a high performance frequency 
> synthesizer chip.
> 
> The current drain looks to be about 160-180 mA at 1.8 V, which is 
> uncomfortably close to the limit for the LT3042 (200 mA).  The 
> manufacturer's evaluation board uses a MAX8869, which appears to be 
> nowhere in the LT3042's league, but will source 1 A.
> 
> Any recommendations for a 1.8 V regulator a little beefier than the 
> LT3042, but with similar noise performance?
> 
> Thanks!
> John
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Re: [time-nuts] HP Xtal Osc Question

[Bruce Griffiths]

See final pages in:

http://www.hparchive.com/Manuals/HP-10811AB-Manual.pdf

The 60111 variant is a lower spec version intended for use in counters.

Bruce

> 
> On 07 March 2018 at 17:50 Perry Sandeen via time-nuts 
>  wrote:
> 
> List,
> When perusing HP xtal oscillators on ebay I noticed some cases were 
> marked HP 10811 and the same appearing unit was marked HP 10811-60111.
> Are both the same for TN purposes?
> If so what are the differences?
> Regards,
> Perrier
> 
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Re: [time-nuts] LT1016 as a pulse shaper...

[Bruce Griffiths]

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 <hmur...@megapathdsl.net> wrote:
> 
>     Bruce Griffiths <bruce.griffi...@xtra.co.nz> 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...

[Bruce Griffiths]

That just confirms that they are clueless when it comes to accurately measuring 
additive PN.

To get the real additive PN one would have to measure it for oneself.

If I had a suitable PCB board for it I would do the measurement properly.


Bruce

> 
> On 04 March 2018 at 23:59 Leo Bodnar <l...@leobodnar.com> wrote:
> 
> Not sure how calculated this - the PN chart for PL133-37 shows output 
> jitter barely lifting off the input jitter trace. LT do not say what their 
> input jitter is.
> 
> Additive jitter for 100MHz 12kHz-20MHz is 80fs for PLL133-37 and 90fs for 
> LTC6957 at more than 10 times lower price.
> 
> I would trust LT more but all this is still armchair engineering. The 
> only way to know is stick it on the board and check.
> 
> Note that PLL133-37 is AC coupled internally so not suitable for short 
> sharp spikes or low frequencies.
> 
> Cheers
> Leo
> 
> On 4 Mar 2018, at 10:20, Bruce Griffiths wrote:
> 
> > > 
> > Somewhat worse than an LTC6957 particularly at low offset 
> > frequencies.
> > 
> > Either that or the manufacturers PN noise measurement method 
> > doesn't work well at low offsets.
> > 
> > Bruce
> > 
> > On 04 March 2018 at 22:34 Leo Bodnar <l...@leobodnar.com> wrote:
> > 
> > Ulf,
> > 
> > What level of jitter would you consider acceptable?
> > 
> > Try PL133-37, I am using it for sinewave shaping on some of designs 
> > - including my 30ps pulser.
> > 
> > Leo
> > 
> > > 
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Re: [time-nuts] LT1016 as a pulse shaper...

[Bruce Griffiths]

Somewhat worse than an LTC6957 particularly at low offset frequencies.

Either that or the manufacturers PN noise measurement method doesn't work well 
at low offsets.

Bruce

> 
> On 04 March 2018 at 22:34 Leo Bodnar  wrote:
> 
> Ulf,
> 
> What level of jitter would you consider acceptable?
> 
> Try PL133-37, I am using it for sinewave shaping on some of designs - 
> including my 30ps pulser.
> 
> Leo
> 
> On 3 Mar 2018, at 21:56, time-nuts-requ...@febo.com wrote:
> 
> > > 
> > From: Ulf Kylenfall 
> > 
> > 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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Re: [time-nuts] Microsemi up for sale?

[Bruce Griffiths]

External cavity lasers with piezoelectric tuning (usually varies cavity length 
or tilts frequency selective grating) are usually used for such applications.

Sacher laser do some compact units with integrated Peltier cooler etc:

https://www.sacher-laser.com/home/industrial-lasers/point_and_line_laser_module/industrial_laser_modules/micron_laser.html

To get pricing registration is required.

They aren't cheap (a few thousand or so euros IIRC) but not too outrageous.

Bruce

> 
> On 04 March 2018 at 21:21 Magnus Danielson  
> wrote:
> 
> Hi,
> 
> On 03/04/2018 04:04 AM, Richard (Rick) Karlquist wrote:
> 
> > > 
> > When I was working on fiber optic communication test,
> > I remember hearing about lasers that were "tuned" with
> > variable Peltier coolers. Power consumption is critical in
> > a cesium standard that can run on batteries. Maybe
> > the power consumption of the coolers is a deal breaker.
> > 
> > > 
> The peltier elements is needed and nowdays integrated with laserdiodes.
> For telecom lasers, which is fully integrated, wavelength shift with
> temperature and Peltier elements is needed to temperature-stabilize them
> when you run DWDM, which is the telecom scenario which is close, as the
> ITU-T channels is 100 GHz apart on a 199 THz base for the 1550 nm window.
> 
> So, peltier elements is needed for sure.
> 
> However, I wonder if there really is much power involved.
> 
> Cheers,
> Magnus
> 
> > > 
> > Rick
> > 
> > On 3/3/2018 6:18 PM, Hal Murray wrote:
> > 
> > > > > 
> > > Thanks.
> > > 
> > > rich...@karlquist.com said:
> > > 
> > > > > > >1. 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.
> > > > 
> > > > > > > 
> > > Is there something fundamental in there, or is the lack of 
> > > products
> > > because
> > > nobody has made the big investment required to figure out how 
> > > to do it.
> > > 
> > > What is the bandwidth of the laser? What happens if it drifts
> > > slightly? Can
> > > it be servoed? ...
> > > 
> > > ___
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> > > > > 
> > > 
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Re: [time-nuts] Z3801A OCXO manual trimming

[Bruce Griffiths]

Monitoring the output frequency whilst the oven "heats" up may give additional 
clues as will monitoring the heater current.

Bruce

> 
> On 04 March 2018 at 16:12 Tom Holmes  wrote:
> 
> Bob...
> 
> Interesting point about the heater not working vs the XTAL having drifted 
> too far. Mine has the same symptoms as the others reported (EFC at the end of 
> its rope) but have not tackled it yet, figuring I'd have to dismantle the 
> whole thing. Certainly troubleshooting a non-operating heater would be much 
> more pleasant.
> 
> Thanks for that insight.
> 
> Tom Holmes, N8ZM
> 
> -Original Message-
> From: time-nuts  On Behalf Of Bob kb8tq
> Sent: Saturday, March 03, 2018 2:07 PM
> To: Tom Curlee ; Discussion of precise time and 
> frequency measurement 
> Subject: Re: [time-nuts] Z3801A OCXO manual trimming
> 
> Hi
> 
> First off some basics about OCXO’s.
> 
> In a single oven design, you have a heater that warms up the entire 
> crystal and the guts of the oscillator. It is on all the time and
> it gets things up to a temperature that makes sense for a given crystal. 
> It can be adjusted based on manufacturing data or by
> trial and error to match the characteristics of that crystal.
> 
> In a double oven design, you have two ovens that are on all the time. One 
> heats up the other one. They both work together to
> achieve the end result. The gain of one adds to the gain of the other to 
> give an improved result. On some double ovens, the
> entire heat range of the inner oven is only 10’s of degrees ….
> 
> In a boosted oven, you have a second heater to get things going when it 
> is very cold. This is an unusual approach and rarely
> seen. Its normally easier to just design a bit more power into the main 
> oven circuit. In a boosted design, the boost heat goes
> away in normal operation at typical temperatures. In normal operation, 
> the gain of the boost circuit does not count.
> 
> SO ….
> 
> The oscillator in the Z3801 is a boosted 10811. It is boosted to allow 
> them to hit a spec of -40C on the unit. At the time it was
> designed, there was talk about mounting these things in un-heated boxes 
> outdoors. After they got a bit further into all the
> details of the designs … that part went away. The spec still hung around 
> long enough to apply to very early designs.
> 
> The net result is that you can pretty much destroy the outer heater stuff 
> and the oscillator will work fine. There is no need
> for it in a typical lab. There are some alarm triggers that need to be 
> wired “ok” when you do so. The details are in the archives.
> 
> But …
> 
> Best guess if your unit is at max EFC = the “real” heater on the 10811 
> has quit working. To get at that, you will need to dig
> into the guts of the unit. Given the massive EFC on the Z3801 version of 
> the oscillator, it would take a crazy amount of aging
> to hit limit.
> 
> Bob
> 
> > > 
> > On Mar 3, 2018, at 1:37 PM, Tom Curlee  
> > wrote:
> > 
> > Since the Z3801A is being discussed, I thought I'd ask about an 
> > issue I'm having with my unit. I use my Z3801 as my working lab standard 
> > for the usual pieces of RF test equipment. In the past year or so I've had 
> > the unit drop out of lock and go into standby mode. Resetting/cycling power 
> > would bring it back into lock for a while, but it generally got worse and 
> > now stays in hold over mode. LH (thanks Mark Sims!!) reports that 
> > everything is operating normally except that the it has a PLL unlock. The 
> > one highly suspicious item is that the DAC is at 99.996902% - full output.
> > The unit shows it has over 94.5K hours run time, so I suspect that 
> > the OCXO has aged to the point that the EFC can't pull it into lock. I 
> > disassembled the OCXO to see if it had a trimmer capacitor like the 
> > standard 10811 units. After removing the outer case and foam insulation, I 
> > see that the outer heater is one of the thin printed circuit serpentine 
> > heaters on what I think is Kapton. That would need to be peeled off of the 
> > case to either get to the hole for the trimmer (if there is one) or to 
> > remove the cover for the inner case.
> > What I don't understand is the purpose of what looks like another 
> > coil or heater wrapped around the Kapton printed circuit heater stuck to 
> > the inner case. This second coil/heater is 2 layers of 1/8" thick red foam 
> > wrapped completely around the inner case, with fine copper wires wrapped 
> > over each layer. At least I think there are wires on each layer. This whole 
> > second heater is taped down and I don't want to dig any further until I 
> > know a bit more about what I'm doing or find that there isn't a trimmer on 
> > the 

Re: [time-nuts] 50 ohm drivers

[Bruce Griffiths]

These devices are only suitable for driving source terminated 50 ohm 
transmission lines not a 50 ohm load to ground (or even 1/2Vcc) to produce CMOS 
levels at the load.

If you are driving a low pass filter or similar intending to produce a sinewave 
output then its somewhat easier.

Even paralleling CMOS outputs won't produce quite a full CMOS swing across a 50 
ohm load.

The classical solution was to either double the swing and use both source and 
load termination or use the Thevenin equivalent using a switched current source.

If AC coupling were allowed push pull drive of a 1:1 RF transformer from a pair 
of complementary 25 ohm Zout CMOS drivers would produce a full amplitude swing 
across a 50 ohm load, however some dc biasing would be required at the load to 
achieve CMOS levels. 

Bruce

> 
> On 04 March 2018 at 15:17 "David C. Partridge" 
>  wrote:
> 
> Brice said:
> 
> > > 
> > . Some fast CMOS devices (esp clock drivers) have an output R close 
> > to 50
> > ohms as they are intended to drive 50 ohm source terminated 
> > transmission
> > lines.
> > 
> > > 
> Any in particular that you'd recommend? I need to drive a 50ohm line and a
> single gate inverter doesn't have the grunt to do so ...
> 
> Thanks
> David
> 
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Re: [time-nuts] LT1016 as a pulse shaper...

[Bruce Griffiths]

The attached circuit is suitable for testing the PN of various CMOS inveters 
etc used as sine to CMOS converters.
Just adjust the input LC network and resistors to suit the source, frequency, 
power and CMOS device Vcc.
Select  the resistor in series with the CMOS output to produce a total series R 
~ 68 ohms when the CMOS device output R is included. Some fast CMOS devices 
(esp clock drivers) have an output R close to 50 ohms as they are intended to 
drive 50 ohm source terminated transmision lines.
Output network LC values are selected to suit the output frequency of the CMOS 
device.

Bruce
> On 04 March 2018 at 10:56 Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote:
> 
> 
> 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 <bruce.griffi...@xtra.co.nz> 
> > 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" 
> > > <david.partri...@perdrix.co.uk> 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
> > > 
> > > ___
> > > 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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> > > and follow the instructions there.
> > > 
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> > > > 
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Re: [time-nuts] LT1016 as a pulse shaper...

[Bruce Griffiths]

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 <bruce.griffi...@xtra.co.nz> 
> 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" 
> > <david.partri...@perdrix.co.uk> 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
> > 
> > ___
> > 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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> > To unsubscribe, go to 
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> > and follow the instructions there.
> > 
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> > 
> > > 
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Re: [time-nuts] LT1016 as a pulse shaper...

[Bruce Griffiths]

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
> 
> ___
> 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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Re: [time-nuts] Rakon HSO-14

[Bruce Griffiths]

There is abrasive entrained in the fluid stream. Operation is in the ductile 
grinding regime so fluid pressures are around 6 bar or so, way below that used 
in abrasive water jet cutting.

It has been used to machine/polish crystal quartz waveplates and to 
machine/polish the surface of silicon wafers before uses for MEMS fabrication. 
Its even been used to carve channels in silicon wafers in such applications.

Bruce

 

> On 04 February 2018 at 15:26 Bob kb8tq <kb...@n1k.org> wrote:
> 
> Hi
> 
> Unfortunately ( at the rates you must use) the “blast it with a fire 
> hose” approach
> is not very fast…..
> 
> Bob
> 
> 
>     > > On Feb 3, 2018, at 8:15 PM, Bruce Griffiths 
> <bruce.griffi...@xtra.co.nz mailto:bruce.griffi...@xtra.co.nz > wrote:
> > 
> > 
> > Fluid jet polishing perhaps?
> > 
> > At least on fused quartz and optical glass there is no associated 
> > subsurface damage.
> > 
> > Bruce
> > 
> > > > > 
> > > On 04 February 2018 at 14:05 Bob kb8tq <kb...@n1k.org 
> > > mailto:kb...@n1k.org > wrote:
> > > 
> > > Hi
> > > 
> > > If you try “normal” machining techniques on a resonator, you 
> > > are very
> > > likely to create micro cracks in the material. Those are 
> > > *really* bad for
> > > aging and a few other issues ….. Much of the normal 
> > > production flow of the
> > > quartz is designed to keep the processes like sawing far 
> > > enough away
> > > from the “end product” that more gentle techniques can be 
> > > used to remove
> > > the (possibly) damaged material.
> > > 
> > > Since the slots are pretty darn small, there isn’t a lot of 
> > > room for this and that
> > > to be done when making them. There may well be better ways to 
> > > do the
> > > work today than back 20 or 30 years ago. It would still take 
> > > a *lot* of effort
> > > to validate a process.
> > > 
> > > Bob
> > > 
> > > > > > > 
> > > > On Feb 3, 2018, at 7:24 PM, Poul-Henning Kamp 
> > > > <p...@phk.freebsd.dk mailto:p...@phk.freebsd.dk > wrote:
> > > > 
> > > > 
> > > > In message 
> > > > <0f9a9acc-4cdf-780f-e633-616262264...@earthlink.net 
> > > > mailto:0f9a9acc-4cdf-780f-e633-616262264...@earthlink.net >, jimlux 
> > > > writes:
> > > > 
> > > > > > > > > 
> > > > > > > > > > > 
> > > > > > [1] Surprising to me is that modern 
> > > > > > dentists are highly kitted for
> > > > > > CNC-ing very hard ceramic materials at high 
> > > > > > precision.
> > > > > > 
> > > > > > > > > > > 
> > > > > But, small "tooth sized" pieces - how big is your 
> > > > > crystal.
> > > > > 
> > > > > > > > > 
> > > > Well, they appearantly make a mouth-full at a time, so 
> > > > that is
> > > > covered...
> > > > 
> > > > I don't think the dentist machines are precise enough 
> > > > though,
> > > > as I understood it, the state-of-the-art stuff has 
> > > > built in
> > > > laser-interferrometers etc.
> > > > 
> > > > --
> > > > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
> > > > p...@freebsd.org mailto: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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> > > > mailto: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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> > > mailto: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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Re: [time-nuts] Rakon HSO-14

[Bruce Griffiths]

Fluid jet polishing perhaps?

At least on fused quartz and optical glass there is no associated subsurface 
damage.

Bruce

> 
> On 04 February 2018 at 14:05 Bob kb8tq  wrote:
> 
> Hi
> 
> If you try “normal” machining techniques on a resonator, you are very
> likely to create micro cracks in the material. Those are *really* bad for
> aging and a few other issues ….. Much of the normal production flow of the
> quartz is designed to keep the processes like sawing far enough away
> from the “end product” that more gentle techniques can be used to remove
> the (possibly) damaged material.
> 
> Since the slots are pretty darn small, there isn’t a lot of room for this 
> and that
> to be done when making them. There may well be better ways to do the
> work today than back 20 or 30 years ago. It would still take a *lot* of 
> effort
> to validate a process.
> 
> Bob
> 
> > > 
> > On Feb 3, 2018, at 7:24 PM, Poul-Henning Kamp  
> > wrote:
> > 
> > 
> > In message <0f9a9acc-4cdf-780f-e633-616262264...@earthlink.net>, 
> > jimlux writes:
> > 
> > > > > 
> > > > > > > 
> > > > [1] Surprising to me is that modern dentists are highly 
> > > > kitted for
> > > > CNC-ing very hard ceramic materials at high precision.
> > > > 
> > > > > > > 
> > > But, small "tooth sized" pieces - how big is your crystal.
> > > 
> > > > > 
> > Well, they appearantly make a mouth-full at a time, so that is
> > covered...
> > 
> > I don't think the dentist machines are precise enough though,
> > as I understood it, the state-of-the-art stuff has built in
> > laser-interferrometers etc.
> > 
> > --
> > 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.
> > 
> > ___
> > 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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Re: [time-nuts] Sick Trimble TBolt

[Bruce Griffiths]

At least one model used a comparatively noisy wideband unity gain analog buffer 
IC.
Without the buffer the OCXO PN was is lower.

Bruce 
> On 31 January 2018 at 12:41 Chris Caudle  wrote:
> 
> 
> > What are the markings of the devices close to the BNC connector?
> 
> Just a guess based on some previous comments from Bob, you are probably
> looking for a logic gate, probably with an LC filter on the output.  Could
> also be some kind of MMIC device, but gate with a filter seems like a good
> possibility.
> Probably SOIC device, shouldn't be too hard to replace.
> 
> -- 
> Chris Caudle
> 
> 
> 
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Re: [time-nuts] Microsemi 3120A sold on eBay

[Bruce Griffiths]

http://www.chronos.co.uk/files/pdfs/mic/3120a.pdf

Bruce

> 
> On 28 January 2018 at 11:57 "Dr. Ulrich L. Rohde via time-nuts" 
>  wrote:
> 
> What are the specs ? 73 de N1UL
> 
> Sent from my iPhone
> 
> > > 
> > On Jan 27, 2018, at 5:38 PM, John Miles  wrote:
> > 
> > So, who's the lucky winner? Anyone on here? That's the first one of 
> > these
> > I've seen in the "secondary market," so to speak.
> > 
> > https://www.ebay.com/itm/332531180078
> > 
> > -- john
> > 
> > Miles Design LLC
> > 
> > ___
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> > 
> > > 
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Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

I wonder what the timing jitter is like.

It may be useful to measure it along with its additive PN.

Bruce

> 
> On 22 January 2018 at 07:31 Robert LaJeunesse  wrote:
> 
> How about using a single 8-pin DIP IC that is under $2.50? The Microchip 
> MIC4422AYN "gate driver" takes a 3.3V signal in and produces a fast 
> rail-to-rail output swing, with a 4.5V to 18V supply range. Typical output 
> resistance is sub 1 Ohm, so not a problem driving a series back-terminated 50 
> Ohm load. Note the 4422's rise and fall times are specified with a 10,000pF 
> load, given the primarily resistive load in this case the rise and fall 
> should be sub 10 ns (per p.5 of the data sheet). But do use beefy lo-Z traces 
> and hefty broadband supply bypassing, the MIC4422 can pump up to 9A into its 
> intended load.
> 
> Bob L.
> 
> > > 
> > Sent: Saturday, January 20, 2018 at 2:43 PM
> > From: "Jerry Hancock" 
> > To: "Discussion of precise time and frequency measurement" 
> > 
> > Subject: Re: [time-nuts] minimalist sine to square
> > 
> > ...
> > 
> > Now that I had the input conditioned, I need to drive a 50ohm load 
> > with the signal coming from the PICDIV. Can someone point me at a circuit 
> > using transistors and 10V if possible?
> > 
> > I am trying to duplicate one channel of the TADD2 so I can bring 
> > 10Mhz down to 10Khz.
> > 
> > Thanks
> > 
> > Jerry
> > 
> > > 
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Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

An npn emitter follower with collector connected to the 10V supply will produce 
a 4.2V swing in a 50 ohm load.

However it only works well if reflections from the load are small.

Otherwise, assuming that you want a 0-5V signal at the 50 ohm load  its 
possible to build a back matched driver using 3 BJTs that will switch 200mA 
into a 25 ohm load with transition times around 5ns or so. Faster transition 
times require using transistors  with ft's somewhat greater than 300MHz.

However the 10V rail current increases to 200mA when the output is 5V at the 50 
ohm load.

Bruce


> 
> On 21 January 2018 at 08:43 Jerry Hancock  wrote:
> 
> Tom might have started this as I was playing around with PICDIV and had 
> asked him the best conditioning circuit. Turned out I had all the parts to 
> copy the TADD-2 including the mini circuits transformer so that’s what I did. 
> It works well, pretty sensitive, etc. I’ve also used the bias trick with a 
> TTL or CMOS buffer when I needed to convert SPIDF signals to baseband for 
> driving an optical connection.
> 
> Now that I had the input conditioned, I need to drive a 50ohm load with 
> the signal coming from the PICDIV. Can someone point me at a circuit using 
> transistors and 10V if possible?
> 
> I am trying to duplicate one channel of the TADD2 so I can bring 10Mhz 
> down to 10Khz.
> 
> Thanks
> 
> Jerry
> 
> > > 
> > On Jan 20, 2018, at 11:21 AM, Poul-Henning Kamp 
> >  wrote:
> > 
> > 
> > In message , 
> > jimlux writes:
> > 
> > > > > 
> > > > > > > 
> > > > I played with that, I used a small transformer to 
> > > > balance the signal
> > > > and then into LVDS receiver through a voltage divider. 
> > > > Worked well,
> > > > but I didn't measure the jitter, it was just for a 
> > > > micro-controller.
> > > > 
> > > > > > > 
> > > You can also do it with capacitive dc block to one side, and 
> > > some
> > > resistors - the ap notes describe it. The receivers are a 
> > > fairly high Z
> > > input, so you pick the voltage divider resistors to make the 
> > > termination
> > > resistance right for the incoming signal.
> > > 
> > > > > 
> > Yes, but that doesn't give you galvanic isolation, which I think is 
> > almost
> > mandatory unless it is a metrology situation.
> > 
> > --
> > 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.
> > 
> > ___
> > 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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Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

Yes, I was just trying to see how far the circuit could be pushed (+27dBm input 
was still OK).

With +13dBm input peak diode current without 100R and 330R resistors is about 
20mA for the 3.3V circuit with an impedance step up from 50 to 400 ohm.

My 100MHz Wenzel OCXO has an output of around +19dBm or so.

I measure the output of all my sources before I connect them.

Bruce 

> 
> On 20 January 2018 at 15:27 Bob kb8tq <kb...@n1k.org> wrote:
> 
> Hi
> 
> My main point is that a +22 dbm (or even 16 dbm) OCXO is a *very* rare 
> item. If your
> signal generator is set to +22 dbm … shame on you. If the part can do 
> well over +7 to
> +13 dbm, that will cover the vast majority of the 10 MHz oscillators / 
> signal sources out there.
> 
> Bob
> 
> > > 
> > On Jan 19, 2018, at 8:51 PM, Bruce Griffiths 
> > <bruce.griffi...@xtra.co.nz> wrote:
> > 
> > Even the modern PICs spec 50mA max input currents.
> > Simulation indicates 20mA peak diode currents without the 330 ohm 
> > resistors for a 2V pp input, even more for higher input signal levels. If 
> > one can guarantee that input is around 1V pp then the extra diodes and 
> > resistors aren't required. If its possible that an input of 16dBm or more 
> > may be used then the extra diodes and resistors are required. I simulated 
> > the circuit for inputs up to +22dBm.
> > Current flowing in the IC protection diodes can degrade the timing 
> > jitter substantially (tens of picosec for HCMOS).
> > 
> > Bruce
> > 
> > > > > 
> > > On 20 January 2018 at 14:34 Bob kb8tq <kb...@n1k.org> wrote:
> > > 
> > > Hi
> > > 
> > > Unless you really beat on the thing for days on end, you can 
> > > do without the 330 ohm and 100 ohm
> > > resistors (along with the two diodes). Most modern gates have 
> > > pretty robust protection diodes. The
> > > source impedance is high enough after the transform that the 
> > > available current is pretty low. On a
> > > NC7SZ125 the negative diode is rated for 50 ma max and the 
> > > positive diode is rated for 20 ma
> > > 
> > > Some math:
> > > 
> > > If the two 1K’s properly terminate the circuit, you have a 
> > > 250 ohm source. (500 ohm load and 500 ohm
> > > transformed from the sine input). A 1V overdrive (1/2 V + and 
> > > 1/2 V -) will put 2 ma into the diodes on the
> > > peaks. The more likely case is that the negative is hit a bit 
> > > harder. The bias is most likely a bit below
> > > 1/2 Vcc for best symmetry.
> > > 
> > > None of this is to say you *should* hit the diodes. No matter 
> > > what sort they are, the performance will
> > > degrade a bit when you do. How much is of course a “that 
> > > depends”. Most of us are not driving the
> > > gate with a -180 dbc/Hz source and expecting -177 out of the 
> > > gate.
> > > 
> > > Bob
> > > 
> > > > > > > 
> > > > On Jan 19, 2018, at 8:14 PM, Bruce Griffiths 
> > > > <bruce.griffi...@xtra.co.nz> wrote:
> > > > 
> > > > Something like the attached circuit is suitable for 
> > > > driving the MCU clock input directly.
> > > > The diodes should be schottky signal diodes like the 
> > > > 1N5711 series. The series resistors limit the diode peak current and 
> > > > the CLK input protection network current. It should work with inputs 
> > > > from 1V pp to 8Vpp. If SMT components were used it should all fit on a 
> > > > DIP compatible daughter board.
> > > > 
> > > > Bruce
> > > > 
> > > > > > > > > 
> > > > > On 20 January 2018 at 12:37 Bob kb8tq 
> > > > > <kb...@n1k.org> wrote:
> > > > > 
> > > > > Bob
> > > > > 
> > > > > With a 1V p-p sort of output, a simple matching 
> > > > > network will get you into the 4 to 6V p-p range.
> > > > > Drive that into a 5V compatible CMOS gate and 
> > > > > move on …. If you have a super hot output, p

Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

Even the modern PICs spec 50mA max input currents.
Simulation indicates 20mA peak diode currents without the 330 ohm resistors for 
a 2V pp input, even more for higher input signal levels. If one can guarantee 
that input is around 1V pp then the extra diodes and resistors aren't required. 
If its possible that an input of 16dBm or more may be used then the extra 
diodes and resistors are required. I simulated the circuit for inputs up to 
+22dBm.
Current flowing in the IC protection diodes can degrade the timing jitter 
substantially (tens of picosec for HCMOS).

Bruce 
> On 20 January 2018 at 14:34 Bob kb8tq <kb...@n1k.org> wrote:
> 
> 
> Hi
> 
> Unless you really beat on the thing for days on end, you can do without the 
> 330 ohm and 100 ohm
> resistors (along with the two diodes). Most modern gates have pretty robust 
> protection diodes. The
> source impedance is high enough after the transform that the available 
> current is pretty low. On a
> NC7SZ125 the negative diode is rated for 50 ma max and the positive diode is 
> rated for 20 ma
> 
> Some math:
> 
> If the two 1K’s properly terminate the circuit, you have a 250 ohm source. 
> (500 ohm load and 500 ohm
> transformed from the sine input). A 1V overdrive (1/2 V + and 1/2 V -) will 
> put 2 ma into the diodes on the
> peaks.  The more likely case is that the negative is hit a bit harder. The 
> bias is most likely a bit below
> 1/2 Vcc for best symmetry. 
> 
> None of this is to say you *should* hit the diodes. No matter what sort they 
> are, the performance will 
> degrade a bit when you do. How much is of course a “that depends”. Most of us 
> are not driving the
> gate with a -180 dbc/Hz source and expecting -177 out of the gate.
> 
> Bob
> 
> > On Jan 19, 2018, at 8:14 PM, Bruce Griffiths <bruce.griffi...@xtra.co.nz> 
> > wrote:
> > 
> > Something like the attached circuit is suitable for  driving the MCU clock 
> > input directly.
> > The diodes should be schottky signal diodes like the 1N5711 series. The 
> > series resistors limit the diode peak current and the CLK input protection 
> > network current. It should work with inputs from 1V pp to 8Vpp. If SMT 
> > components were used it should all fit on a DIP compatible daughter board.
> > 
> > Bruce
> >> On 20 January 2018 at 12:37 Bob kb8tq <kb...@n1k.org> wrote:
> >> 
> >> 
> >> Bob
> >> 
> >> With a 1V p-p sort of output, a simple matching network will get you into 
> >> the 4 to 6V p-p range.
> >> Drive that into a 5V compatible CMOS gate and move on …. If you have a 
> >> super hot output, put 
> >> a 3 db pad on it. 
> >> 
> >> Bob
> >> 
> >>> On Jan 19, 2018, at 5:40 PM, Tom Van Baak <t...@leapsecond.com> wrote:
> >>> 
> >>>> Tom
> >>>> What's the input signal amplitude?
> >>>> What's the desired output signal (eg 5V CMOS, 3.3V CMOS etc)?
> >>>> Bruce
> >>> 
> >>> It's for a typical 5 or 10 MHz OCXO / Rb / Cs with sinewave output; say, 
> >>> 1 Vpp. The output should be 3.3 or 5 V depending on what the MCU needs. 
> >>> It doesn't have to have stunning performance: think breadboard, PIC, 
> >>> Arduino sort of stuff. I was looking for something in a PDIP-8 package; 
> >>> the same as all the picDIV or picPET chips I use. That's why older parts 
> >>> like µA9637 / DS9637 came to mind.
> >>> 
> >>> /tvb
> >>> 
> >>> ___
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> >>> and follow the instructions there.
> >> 
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> > 
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Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

That network was for a 10MHz input.

For 5MHz double the L and C values.

For 3.3V one could use a lower step up say from  50 to 400 ohms rather than 
from 50 to 800 ohms.

1uH and 150pF and change 1k6 resistors to 820R.

Swap the 5V supply for a 3.3V supply.

L and C values aren't critical 5% or somewhat looser tolerance should be 
suffice.

Bruce

> 
> On 20 January 2018 at 14:14 Bruce Griffiths <bruce.griffi...@xtra.co.nz> 
> wrote:
> 
> Something like the attached circuit is suitable for driving the MCU clock 
> input directly.
> The diodes should be schottky signal diodes like the 1N5711 series. The 
> series resistors limit the diode peak current and the CLK input protection 
> network current. It should work with inputs from 1V pp to 8Vpp. If SMT 
> components were used it should all fit on a DIP compatible daughter board.
> 
> Bruce
> 
> > > 
> > On 20 January 2018 at 12:37 Bob kb8tq <kb...@n1k.org> wrote:
> > 
> > Bob
> > 
> > With a 1V p-p sort of output, a simple matching network will get 
> > you into the 4 to 6V p-p range.
> > Drive that into a 5V compatible CMOS gate and move on …. If you 
> > have a super hot output, put
> > a 3 db pad on it.
> > 
> > Bob
> > 
> > > > > 
> > > On Jan 19, 2018, at 5:40 PM, Tom Van Baak 
> > > <t...@leapsecond.com> wrote:
> > > 
> > > > > > > 
> > > > Tom
> > > > What's the input signal amplitude?
> > > > What's the desired output signal (eg 5V CMOS, 3.3V CMOS 
> > > > etc)?
> > > > Bruce
> > > > 
> > > > > > > 
> > > It's for a typical 5 or 10 MHz OCXO / Rb / Cs with sinewave 
> > > output; say, 1 Vpp. The output should be 3.3 or 5 V depending on what the 
> > > MCU needs. It doesn't have to have stunning performance: think 
> > > breadboard, PIC, Arduino sort of stuff. I was looking for something in a 
> > > PDIP-8 package; the same as all the picDIV or picPET chips I use. That's 
> > > why older parts like µA9637 / DS9637 came to mind.
> > > 
> > > /tvb
> > > 
> > > ___
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> > > 
> > > > > 
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Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

Something like the attached circuit is suitable for  driving the MCU clock 
input directly.
The diodes should be schottky signal diodes like the 1N5711 series. The series 
resistors limit the diode peak current and the CLK input protection network 
current. It should work with inputs from 1V pp to 8Vpp. If SMT components were 
used it should all fit on a DIP compatible daughter board.

Bruce
> On 20 January 2018 at 12:37 Bob kb8tq  wrote:
> 
> 
> Bob
> 
> With a 1V p-p sort of output, a simple matching network will get you into the 
> 4 to 6V p-p range.
> Drive that into a 5V compatible CMOS gate and move on …. If you have a super 
> hot output, put 
> a 3 db pad on it. 
> 
> Bob
> 
> > On Jan 19, 2018, at 5:40 PM, Tom Van Baak  wrote:
> > 
> >> Tom
> >> What's the input signal amplitude?
> >> What's the desired output signal (eg 5V CMOS, 3.3V CMOS etc)?
> >> Bruce
> > 
> > It's for a typical 5 or 10 MHz OCXO / Rb / Cs with sinewave output; say, 1 
> > Vpp. The output should be 3.3 or 5 V depending on what the MCU needs. It 
> > doesn't have to have stunning performance: think breadboard, PIC, Arduino 
> > sort of stuff. I was looking for something in a PDIP-8 package; the same as 
> > all the picDIV or picPET chips I use. That's why older parts like µA9637 / 
> > DS9637 came to mind.
> > 
> > /tvb
> > 
> > ___
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Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

A fast DIP comparator such as an LT1016 should work but it won't perform well 
without an effective ground plane.

If a CMOS gate is used then a low Q LC impedance step up network or equivalent 
will be needed to increase the signal swing at the gate input. Add a couple of 
schottky diode clamps for overvoltage clamping (internal CMOS gate clamp 
devices usually degrade performance if they conduct).


Bruce

> 
> On 20 January 2018 at 11:40 Tom Van Baak  wrote:
> 
> > > 
> > Tom
> > What's the input signal amplitude?
> > What's the desired output signal (eg 5V CMOS, 3.3V CMOS etc)?
> > Bruce
> > 
> > > 
> It's for a typical 5 or 10 MHz OCXO / Rb / Cs with sinewave output; say, 
> 1 Vpp. The output should be 3.3 or 5 V depending on what the MCU needs. It 
> doesn't have to have stunning performance: think breadboard, PIC, Arduino 
> sort of stuff. I was looking for something in a PDIP-8 package; the same as 
> all the picDIV or picPET chips I use. That's why older parts like µA9637 / 
> DS9637 came to mind.
> 
> /tvb
> 
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Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

Now, if one added an optional TTL threshold 5V CMOS single gate inverter/buffer 
to produce 5V output when required and added an SMT 5V->3.3V regulator and 
mounted it all on a small PCB with pins to make it DIP compatible that would 
meet the brief and then some.

Otherwise an SMT (not many DIP ones left) comparator mounted on a DIP/SMT 
converter board would also work albeit with a PN/jitter performance penalty.

Bruce

> On 20 January 2018 at 11:37 Gerhard Hoffmann  wrote:
> 
> 
> 
> 
> Am 19.01.2018 um 20:31 schrieb Tom Van Baak:
> > John's TADD-2-mini [1] uses the Wenzel sine-to-square converter. It 
> > performs very well but requires +10 V.
> >
> > I'm looking for a solution that works at 5 V (e.g., USB powered) and also 
> > uses fewer parts. Wenzel also mentions using a differential line receiver 
> > [2]. That would be an ideal single-chip 5 V solution for me but the two 
> > parts he mentions, MC1489 [3] and SN55182 [4], don't appear fast enough for 
> > a 10 MHz input.
> >
> > Can any of you circuit experts suggest some line receivers that would work? 
> > Maybe DS9637 [5]? This isn't for cesium work so it doesn't have to be quite 
> > as good as the TADD-2.
> < http://cds.linear.com/docs/en/datasheet/6957fb.pdf >
> < http://cds.linear.com/docs/en/design-note/dn514f.pdf >
> 
> I have used it, found no problems. It is somewhat small :-)
> 
> regards, Gerhard
> 
> 
> 
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Re: [time-nuts] minimalist sine to square

[Bruce Griffiths]

Tom
What's the input signal amplitude?
What's the desired output signal (eg 5V CMOS, 3.3V CMOS etc)?
Bruce
> On 20 January 2018 at 08:31 Tom Van Baak  wrote:
> 
> 
> John's TADD-2-mini [1] uses the Wenzel sine-to-square converter. It performs 
> very well but requires +10 V.
> 
> I'm looking for a solution that works at 5 V (e.g., USB powered) and also 
> uses fewer parts. Wenzel also mentions using a differential line receiver 
> [2]. That would be an ideal single-chip 5 V solution for me but the two parts 
> he mentions, MC1489 [3] and SN55182 [4], don't appear fast enough for a 10 
> MHz input.
> 
> Can any of you circuit experts suggest some line receivers that would work? 
> Maybe DS9637 [5]? This isn't for cesium work so it doesn't have to be quite 
> as good as the TADD-2.
> 
> Thanks,
> /tvb
> 
> [1] http://www.tapr.org/~n8ur/T2_Mini_Manual.pdf
> [2] http://www.wenzel.com/documents/waveform.html
> [3] https://www.onsemi.com/pub/Collateral/MC1489-D.PDF
> [4] http://www.ti.com/lit/ds/slls092d/slls092d.pdf
> [5] http://www.ti.com/lit/ds/symlink/ds9637a.pdf
> 
> 
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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[Bruce Griffiths]

Yes, but the PN noise (outside the PLL bandwidth) will be much higher than with 
a classical multiplier.

Bruce

> 
> On 09 January 2018 at 02:14 Chris Wilson  wrote:
> 
> Hello Bruce, Sorry, this went to you direct as well, in error.
> 
> Thanks for the very fast reply! Would it be possible to use one of
> these frequency multiplier IC's? Sounds simpler, but maybe there are
> down sides?
> 
> 
> http://uk.farnell.com/on-semiconductor/nb3n502dg/pll-clock-multiplier-8soic/dp/2101849
> 
> on 08/01/2018 13:11 you wrote:
> 
> > > 
> > Divide the 10MHz by 2 and use a filter to extract the fifth
> > harmonic from the 5MHz square wave output.
> > 
> > Amplify the 25MHz output from the filter if required...
> > 
> > Bruce
> > 
> > On 09 January 2018 at 00:31 Chris Wilson  
> > wrote:
> > 
> > 08/01/2018 11:28
> > 
> > Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt
> > as a reference clock at 1v P to P square wave for a Si5351a
> > synthesizer chip please? I have the David Partridge divider board 
> > from
> > way back that is still going strong, but 25 MHz is not an option as 
> > it
> > divides only. Thanks, please keep replies to the level an idiot 
> > might
> > comprehend :)
> > 
> > --
> > Best Regards,
> > Chris Wilson.
> > mailto: ch...@chriswilson.tv
> > 
> > > 
> --
> Best Regards,
> Chris Wilson.
> 
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Re: [time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??

[Bruce Griffiths]

Divide the 10MHz by 2 and use a filter to extract the fifth harmonic from the 
5MHz square wave output.

Amplify the 25MHz output from the filter if required...

Bruce

> 
> On 09 January 2018 at 00:31 Chris Wilson  wrote:
> 
> 08/01/2018 11:28
> 
> Is there an easy way to get 25 or 27 MHz from my Trimble Thunderbolt
> as a reference clock at 1v P to P square wave for a Si5351a
> synthesizer chip please? I have the David Partridge divider board from
> way back that is still going strong, but 25 MHz is not an option as it
> divides only. Thanks, please keep replies to the level an idiot might
> comprehend :)
> 
> --
> Best Regards,
> Chris Wilson.
> mailto: ch...@chriswilson.tv
> 
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Re: [time-nuts] Skilled Math Editor(s) Needed

[Bruce Griffiths]

It was not my intent to suggest that Perry should continue the work using Latex.

I was merely considering the most effective and efficient way to complete this 
undertaking, whoever elects to pick it up.

The original is written in English so an extensive knowledge of French isn't 
required.

At 616 pages (according to the Amazon listing), or 1567 pages ( according to 
the google books entry)  the task isn't perhaps quite as daunting as I 
originally thought. 

Even so it may take 1-2 years at 3 pages/day.

Bruce

> 
> On 03 January 2018 at 19:27 Bill Hawkins  wrote:
> 
> Friends in time,
> 
> Perry has apparently reached a major change in his life, perhaps because
> of a doctor's diagnosis - but there are zillions of other reasons. It
> seems to me that he is looking for someone to pick up his project and
> run with it.
> 
> Advising him on the ways he could continue is probably not useful. He
> needs someone to take the baton and take it further.
> 
> I say this as one who has downsized by 75% in order to move into a life
> care community after my wife and I had cancer scares and no long term
> care insurance.
> 
> A cousin was the copy editor for Gone With the Wind and other Doubleday
> books. I seem to have inherited some of those genes. But I can't tell a
> bad equation from a good one, and my French ended in High School.
> 
> Happy new year to the best list on the Internet.
> 
> Bill Hawkins
> 
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Re: [time-nuts] Skilled Math Editor(s) Needed

[Bruce Griffiths]

Using Latex for the typesetting is probably the optimum solution for a 
Technical/Scientific publiication such as this.

Most such publications are typeset using Latex these days.

If one is familiar with Latex the odd typo when typesetting an equation (for 
example) can make it blatantly obvious that Latex was employed to typset a 
document.

Suitable templates are freely available along with toolsets for Nuclear 
Physics, Chemistry and Mathematics etc

Bruce  

> 
> On 03 January 2018 at 14:41 Perry Sandeen via time-nuts 
>  wrote:
> 
> HI,
> At the request of a TN member (who wishes to remain anonymous)I started 
> to reproduce:
> 
> The Quantum Physics of Atomic Frequency Standards Volume 1By Jacques 
> Vanier Division de Physique,Conseil National de Recherches, Ottawa and Claude 
> Audoin Laboratoire de I’Horloge Atomique, CentreNational de la Recherche 
> Scientifique, Universite Paris Sud, Orsay. From aphotocopy he had.
> 
> I tried to do this as its used price will cost you yourfirst born child.
> 
> The original copyright was 1989. The copyright has expired and the 
> document isnow in the public domain
> 
> So I digitally reproduced and translated it into AmericanEnglish in March 
> 2016. Additionalliberty in editing was taken. Many paragraphs contained more 
> than one subjectso using standard writing guidelines they were split up for 
> an easierunderstanding of the concepts being presented.
> 
> Many formulae had to be transferred images, and are veryclear, as 
> re-typing would have delayed this project to infinity. Lastly, textwas 
> transferred by OCR. Many drawings had to be edited using PhotoShop Elements 
> as the originals were smeared.
> 
> I spent about 200 hours doing this.
> 
> Some formula symbols were not accurately reproduced. I don’t have the 
> math ability needed toretype most formulae. No material was added or deleted
> 
> I can send to all who wish it a DVD with the 800+ Mbytes ofraw data and 
> the partial (5%) I have accomplished.
> 
> Due to permanent changes in my life I will never be able tospend time on 
> this again. I just don’t want delete the material.
> 
> Regards,
> 
> Perrier
> 
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Re: [time-nuts] New product: the TAPR "PulsePuppy"

[Bruce Griffiths]

An optional ressistor in series with gate output would be nice for reducing 
aberrations seen at a high impedance load at the end of a piece of 50 ohm coax.

Bruce

> 
> On 24 December 2017 at 13:18 Bob kb8tq  wrote:
> 
> Hi
> 
> There’s a lot of debate out there about that.
> 
> When used as a variable resistor (two terminal device) there is no doubt 
> that a
> sereis resistor can help. When used as a voltage divider (three terminal 
> device)
> the claim by the pot manufacturing OCXO companies is that you are better 
> with
> no added resistors. The material in the pot is all same / same and the TC 
> as a
> divider is quite low. Yes, there are other opinions out there …..
> 
> Bob
> 
> > > 
> > On Dec 23, 2017, at 6:57 PM, Mark Sims  wrote:
> > 
> > Looks good and quite useful.
> > 
> > If you ever re-spin the board, I would recommend including a place 
> > for range limiting resistors on the ends of the EFC adjustment pot. That 
> > way they can be low TCR resistors and the TCR effects of the pot can be 
> > minimized and the EFC adjustment can be made less twitchy. But, at the 
> > expense of possibly needing to tweak the range resistors as the oscillator 
> > ages.
> > 
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Re: [time-nuts] Some more info on the 5065A optical unit

[Bruce Griffiths]

However the dimensions of the coil former vary with moisture content.
Impregnation with waxes and other organic materials merely serves to slow down 
the rate of absorption and doesn't prevent it.
Bruce 
> On 28 November 2017 at 12:36 Poul-Henning Kamp  wrote:
> 
> 
> 
> In message <2b66d682-15cf-465f-9a34-d7f7e7929...@n1k.org>, Bob kb8tq writes:
> 
> >Straight cardboard *is* an issue on RF coils in humidity.
> 
> The C-field coil is DC only.
> 
> -- 
> 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] HP5065A C-field mods and optical unit mods

[Bruce Griffiths]

What is the effect of the C-field coil dimension tempco?

At some point this will surely dominate overthe coil current tempco.

Bruce

> 
> On 22 November 2017 at 09:16 Charles Steinmetz  
> wrote:
> 
> Luciano wrote:
> 
> > > 
> > what you refer is the resistance relation referred to the LM299 
> > source around 14VDc but you have to consider
> > the tuning range of the pot, in the original HP5065A is 2E10-9.
> > Of course, it depends on the setting value of the variable 
> > resistance, but you have to consider a possible variation of 20PPM/c on 
> > 2E10-9.
> > 
> > > 
> No, you don't. The tempco that matters is the aggregate tempco of the
> series string. Only a very small portion of the string voltage appears
> across the pot, so a 20ppm tempco of that small part will cause a much
> smaller change in overall tempco of the series string.
> 
> Perhaps Corby will tell us what value the pot is, and then you can
> calculate the aggregate tempco of the string at various pot settings and
> see for yourself.
> 
> Charles
> 
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Re: [time-nuts] Input filter for data logger

[Bruce Griffiths]

The performance of virtually all CMOS gate sine to CMOS converters degrades 
significantly once the signal at the gate input exceeds the supplies 
sufficiently to cause the input protection circuitry to conduct. This effect is 
very easy to measure with HCMOS.

Bruce 

> 
> On 20 November 2017 at 14:20 Mark Sims  wrote:
> 
> Here are Wenzel's input circuits:
> http://www.wenzel.com/documents/waveform.html
> 
> The TAPR TICC uses a slightly modified version of the two transistor 
> circuit.
> 
> Also check out the LPRO-101 manual for their versions of the single CMOS 
> gate squarer. One thing they do is add an RC filter to the CMOS gate power 
> supply.
> 
> I use this version (with a 74HC86 as the input gate) on my HP-531xx time 
> interval calibrator circuit. Wenzel says an HC gate works better than AC 
> logic if you don't need to handle higher freqs. It provides surprisingly good 
> performance for such a simple circuit.
> 
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Re: [time-nuts] Input filter for data logger

[Bruce Griffiths]

Oops I meat to say:

Thats a MOSFET variant of a fairly standard JFET-BJT feedback amplifier.

Bruce

> On 20 November 2017 at 11:47 Bruce Griffiths <bruce.griffi...@xtra.co.nz> 
> wrote:
> 
> 
> Hoi Attila
> 
> That's a fairly standard JFET BJT negative feedback amp that's not 
> usually unstable.
> 
> The unity gain version has been employed as the input stage of various 
> high impedance oscilloscope preamps.
> 
> Bruce
> 
> > > 
> > On 20 November 2017 at 11:21 Attila Kinali <att...@kinali.ch> wrote:
> > 
> > On Sun, 19 Nov 2017 16:10:54 -0500
> > Vlad <t...@patoka.org> wrote:
> > 
> > > > > 
> > > Here is my schematic:
> > > 
> > > http://www.patoka.ca/OCXO/LOGGER/IMG_20171119_155907272.jpg
> > > 
> > > > > 
> > Ok.. I am surprised, this doesn't oscillate.
> > 
> > You have a two stage amplifier, where the second stage
> > has a negative feedback path into the first stage.
> > 
> > When a pulse comes in, the jfet will turn on and conduct
> > current through its drain and source resistors. When the
> > current reaches something around 6-8mA the pnp will start
> > conducting. But the collector current of the pnp goes into
> > the source resistor of the jfet. This will increase the
> > voltage on the source, thus decreasing the gate-source
> > voltage, thus turn the jfet off, which in turn will turn
> > the pnp off, which in then will stop conducting, thus
> > no current into the source resistor, thus the jfet will
> > start conducting again... I guess you get it.
> > 
> > > > > 
> > > I did some simple tests for this. In it seems it was OK up to 
> > > 10Mhz.
> > > 
> > > > > > > 
> > > > But guessing from what you showed, I would say that 
> > > > your amplifier
> > > > circuit isn't stable and has some gain peaking at 
> > > > around 10MHz.
> > > > There are two ways to proceed: Either optimize your 
> > > > circuit or
> > > > simplify it using modern components to the input signal 
> > > > you expect.
> > > > 
> > > > > > > 
> > > The main purpose for this circuit is to protect the MCU input 
> > > and make
> > > some sine to square conversion.
> > > 
> > > > > 
> > Use a biased 74AC04. That's the easiest. And you will have very
> > little noise degradation.
> > 
> > I would think that the MCU can probably take more abuse than the
> > 74AC. Modern ASICs have quite a bit of protection circuits on
> > their inputs. I am not sure whether the 74-families have seen
> > upgrades on their protection circuits in the last 30-40 years.
> > 
> > Attila Kinali
> > 
> > --
> > You know, the very powerful and the very stupid have one thing in 
> > common.
> > They don't alters their views to fit the facts, they alter the 
> > facts to
> > fit the views, which can be uncomfortable if you happen to be one 
> > of the
> > facts that needs altering. -- The Doctor
> > 
> > ___
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> > and follow the instructions there.
> > 
> > > 
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Re: [time-nuts] Input filter for data logger

[Bruce Griffiths]

Hoi Attila

That's a fairly standard JFET BJT negative feedback amp that's not usually 
unstable.

The unity gain version has been employed as the input stage of various high 
impedance oscilloscope preamps.

Bruce

> 
> On 20 November 2017 at 11:21 Attila Kinali  wrote:
> 
> On Sun, 19 Nov 2017 16:10:54 -0500
> Vlad  wrote:
> 
> > > 
> > Here is my schematic:
> > 
> > http://www.patoka.ca/OCXO/LOGGER/IMG_20171119_155907272.jpg
> > 
> > > 
> Ok.. I am surprised, this doesn't oscillate.
> 
> You have a two stage amplifier, where the second stage
> has a negative feedback path into the first stage.
> 
> When a pulse comes in, the jfet will turn on and conduct
> current through its drain and source resistors. When the
> current reaches something around 6-8mA the pnp will start
> conducting. But the collector current of the pnp goes into
> the source resistor of the jfet. This will increase the
> voltage on the source, thus decreasing the gate-source
> voltage, thus turn the jfet off, which in turn will turn
> the pnp off, which in then will stop conducting, thus
> no current into the source resistor, thus the jfet will
> start conducting again... I guess you get it.
> 
> > > 
> > I did some simple tests for this. In it seems it was OK up to 10Mhz.
> > 
> > > > > 
> > > But guessing from what you showed, I would say that your 
> > > amplifier
> > > circuit isn't stable and has some gain peaking at around 
> > > 10MHz.
> > > There are two ways to proceed: Either optimize your circuit or
> > > simplify it using modern components to the input signal you 
> > > expect.
> > > 
> > > > > 
> > The main purpose for this circuit is to protect the MCU input and 
> > make
> > some sine to square conversion.
> > 
> > > 
> Use a biased 74AC04. That's the easiest. And you will have very
> little noise degradation.
> 
> I would think that the MCU can probably take more abuse than the
> 74AC. Modern ASICs have quite a bit of protection circuits on
> their inputs. I am not sure whether the 74-families have seen
> upgrades on their protection circuits in the last 30-40 years.
> 
> Attila Kinali
> 
> --
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering. -- The Doctor
> 
> ___
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Re: [time-nuts] Phase noise measurement experiment by Andrew Holme

[Bruce Griffiths]

The 16 bit ADCs (at least the LTC lower sample rate ones ) tend to be a few 
dBc/Hz quieter.

However the difference is < 12 dBc/Hz.

Bruce

> 
> On 27 October 2017 at 14:35 Li Ang <379...@qq.com> wrote:
> 
> Hi
> I just found Andrew recently post a phase noise measruement page on 
> www.aholme.co.uk/PhaseNoise/Main.htm .
> 
> He uses 4-channel 14bit ADC to do the sampling work. -170dBc noise floor 
> seems not bad for me.
> 
> Since the cross correlation could reduce noise a lot, I am wondering what 
> the differences between 14 bits and 16 bits ADC are.
> 
> Regards
> Li Ang / BI7LNQ
> 
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Re: [time-nuts] Spice simulation of PSRR and phase noise

[Bruce Griffiths]

One has to provide noise models that work with the Spice transient simulation 
for all devices including resistors. Random number generators can be used but 
they need to be independent and must not repeat during the entire simulation.

Bruce

> 
> On 23 October 2017 at 10:25 Bruce Griffiths <bruce.griffi...@xtra.co.nz> 
> wrote:
> 
> If one for example wishes to estimate PN down to an offset of 1Hz then an 
> equivalent filter noise bandwidth of 0.1Hz or perhaps less is desirable (the 
> PN spectrum at low offsets is far from flat). To achive accurate noise 
> estimates a simulation time of at least 100 x the reciprocal of the 
> equivalent noise bandwidth is required. The resultant simulation for 1000 sec 
> or more takes considerably longer than 1000 sec to run.
> 
> Bruce
> 
> > > 
> > On 23 October 2017 at 03:23 Dana Whitlow <k8yumdoo...@gmail.com> 
> > wrote:
> > 
> > Hello Attila,
> > 
> > It seems to me that an AC simulation could never work since the
> > very generation of phase noise by the mechanisms that matter is
> > a modulation process at heart, automatically forcing one into the
> > realm of transient simulations.
> > 
> > But I am surprised about the simulation times that you speak of.
> > Would you be willing to post some information detailing your
> > methodology and an example "simple" circuit?
> > 
> > Dana
> > 
> > On Sun, Oct 22, 2017 at 7:53 AM, Attila Kinali <att...@kinali.ch> 
> > wrote:
> > 
> > > > > 
> > > > > > > 
> > > > Hi,
> > > > 
> > > > > > > 
> > > I have been looking into spice simulations of circuits, in 
> > > particular
> > > trying to extract PSRR and phase noise information. 
> > > Unfortunatelly,
> > > the obvious way of putting AC sources at the right places 
> > > does not
> > > work, as the (ideal) input signals are not small and drive 
> > > the circuit
> > > into non-linearities. Hence I have to do transient 
> > > simulations.
> > > But extracting PSRR and phase noise information out of a 
> > > transient
> > > simulation is cumbersome at best and takes a lot of 
> > > simulation time
> > > (we are talking about hours to days for simple circuits).
> > > 
> > > I am looking for guidelines and hints how to speed things up.
> > > Maybe even being able to use standard DC and AC analysis for 
> > > the
> > > circuit instead of transient. Unfortunately, my google-foo 
> > > was not
> > > strong enough to find approriate documentation.
> > > 
> > > Does someone have any hints what I should read or search for?
> > > 
> > > Thanks in advance
> > > 
> > > 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
> > > and follow the instructions there.
> > > 
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> > > > > > > 
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> > > > > > > 
> > > > > 
> > > 
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Re: [time-nuts] Spice simulation of PSRR and phase noise

[Bruce Griffiths]

If one for example wishes to estimate PN down to an offset of 1Hz then an 
equivalent filter noise bandwidth of 0.1Hz or perhaps less is desirable (the PN 
spectrum  at low offsets is far from flat). To achive accurate noise estimates 
a simulation time of at least 100 x the reciprocal of the equivalent noise 
bandwidth is required. The resultant simulation for 1000 sec or more takes 
considerably longer than 1000 sec to  run. 

Bruce

> 
> On 23 October 2017 at 03:23 Dana Whitlow  wrote:
> 
> Hello Attila,
> 
> It seems to me that an AC simulation could never work since the
> very generation of phase noise by the mechanisms that matter is
> a modulation process at heart, automatically forcing one into the
> realm of transient simulations.
> 
> But I am surprised about the simulation times that you speak of.
> Would you be willing to post some information detailing your
> methodology and an example "simple" circuit?
> 
> Dana
> 
> On Sun, Oct 22, 2017 at 7:53 AM, Attila Kinali  wrote:
> 
> > > 
> > Hi,
> > 
> > I have been looking into spice simulations of circuits, in 
> > particular
> > trying to extract PSRR and phase noise information. Unfortunatelly,
> > the obvious way of putting AC sources at the right places does not
> > work, as the (ideal) input signals are not small and drive the 
> > circuit
> > into non-linearities. Hence I have to do transient simulations.
> > But extracting PSRR and phase noise information out of a transient
> > simulation is cumbersome at best and takes a lot of simulation time
> > (we are talking about hours to days for simple circuits).
> > 
> > I am looking for guidelines and hints how to speed things up.
> > Maybe even being able to use standard DC and AC analysis for the
> > circuit instead of transient. Unfortunately, my google-foo was not
> > strong enough to find approriate documentation.
> > 
> > Does someone have any hints what I should read or search for?
> > 
> > Thanks in advance
> > 
> > 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
> > 
> > ___
> > 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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Re: [time-nuts] Spice simulation of PSRR and phase noise

[Bruce Griffiths]

Hoi Attila

Since close in phase noise can result from up conversion of supply noise etc 
via circuit non linearities, using an AC analysis won't work.

Only transient simulation or perhaps analytical modelling of the various non 
linearities will provide accurate estimates of upconverted PN. If you use 
transient simulation techniques increasing the level of the various noise 
sources above the actual levels encountered in real circuits and then 
correcting the resultant PN back to the level that would be encountered in the 
actual circuit (using the results of analytical modelling) may be a useful way 
to reduce simulation time or at least overcome some of the challenges 
associated with accurately determining low level PN from a simulation.

There are some in the LTSpice Yahoo group attempting this but they seem way out 
of touch with the amount of simulation data required. I've provided them with 
the appropriate formulae to extract PN from the the amplitude spectra. At the 
moment they appear bogged down with some somewhat trivial peripheral issues.

Bruce

> 
> On 23 October 2017 at 01:53 Attila Kinali  wrote:
> 
> Hi,
> 
> I have been looking into spice simulations of circuits, in particular
> trying to extract PSRR and phase noise information. Unfortunatelly,
> the obvious way of putting AC sources at the right places does not
> work, as the (ideal) input signals are not small and drive the circuit
> into non-linearities. Hence I have to do transient simulations.
> But extracting PSRR and phase noise information out of a transient
> simulation is cumbersome at best and takes a lot of simulation time
> (we are talking about hours to days for simple circuits).
> 
> I am looking for guidelines and hints how to speed things up.
> Maybe even being able to use standard DC and AC analysis for the
> circuit instead of transient. Unfortunately, my google-foo was not
> strong enough to find approriate documentation.
> 
> Does someone have any hints what I should read or search for?
> 
> Thanks in advance
> 
> 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] Fast Rise/Fall Time Pulser

[Bruce Griffiths]

It appears to be merely an ECL comparator;
https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/

Bruce
> On 11 October 2017 at 09:14 Magnus Danielson  
> wrote:
> 
> 
> Hi,
> 
> On 10/10/2017 09:42 PM, Brooke Clarke wrote:
> > Hi Larry:
> > 
> > How does it work.
> > When I was working with microwave semis it was either a tunnel diode or 
> > a Step Recovery Diode.
> > 
> 
> Looking at the pictures, it seems like the surface mounted chip marked 
> AJK AAA is the driver-chip that connects through a capacitor over to the 
> centerlead of the BNC output.
> 
> Some form of driver, and setup such that amplitude scale can be controlled.
> 
> Cheers,
> Magnus
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Re: [time-nuts] sine to square wave circuits - performance data?

[Bruce Griffiths]

Hoi Attila

I've unearthed the TAPR T2-mini.
I need to obtain an 8 pin DIP header so that I can connect pins 2 +3 on the PCB 
DIP socket.
Then I can test PN etc as function of input signal level at 10MHz. 
May take a week or so to arrive.
Meanwhile I have an optical interferometer to work on.
 
Bruce
> On 04 October 2017 at 20:23 Attila Kinali <att...@kinali.ch> wrote:
> 
> 
> Hoi Bruce,
> 
> 
> Thanks for the link. That's some nice data.
> 
> On Wed, 4 Oct 2017 12:02:35 +1300 (NZDT)
> Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote:
> 
> > I have measured the PN of the LTC6957-4 at 10MHz.
> > 
> > I could measure the PN of the TAPR variant of the Wenzel circuit as well as 
> > the PN of the comparator based circuit (with CMOS output buffer).  
> 
> This would be very helpful. I have wondered how the modified Wenzel
> circuit compared to an LTC6957 or a simple comparator.
> 
> 
>   Attila Kinali
> 
> 
> -- 
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering.  -- The Doctor
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Re: [time-nuts] sine to square wave circuits - performance data?

[Bruce Griffiths]

Substrate currents biasing on parasitic devices in  junction isolated process?
If so, then silicon on insulator CMOS may not exhibit the effect.
Bruce
> On 05 October 2017 at 10:18 Attila Kinali <att...@kinali.ch> wrote:
> 
> 
> On Thu, 5 Oct 2017 10:11:37 +1300 (NZDT)
> Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote:
> 
> > Just avoid current flowing in the input protection circuitry.
> > 
> > Once the protection circuit is activated the jitter increases significantly.
> 
> Do you know what the mechanism is, that increases jitter in this case?
> 
>   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] sine to square wave circuits - performance data?

[Bruce Griffiths]

Just avoid current flowing in the input protection circuitry.

Once the protection circuit is activated the jitter increases significantly.

Bruce

> 
> On 05 October 2017 at 04:21 Mark Sims  wrote:
> 
> Wenzel says an HC device tends to work better than an AC device in 
> squarer applications.
> 
> My calibrator board has a place for the feedback resistor so that I can 
> implement the second LPRO circuit (or add hysteresis to the squarer gate.
> 
> 
> 
> > > 
> > I find it interesting that a simple 74AC04 performs so well (given 
> > enough
> > input power) compared to even an LT1016.
> > 
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Re: [time-nuts] sine to square wave circuits - performance data?

[Bruce Griffiths]

John
Do you recall what the amplitude of the input signal to the Wenzel shaper was?

Since I used a 1:2 (3dB) terminated splitter for my measurements the input to 
the splitter is the same as the Timepod reference signal amplitude
 
Bruce
> On 04 October 2017 at 14:12 John Miles  wrote:
> 
> 
> > I have measured the PN of the LTC6957-4 at 10MHz.
> > 
> > I could measure the PN of the TAPR variant of the Wenzel circuit as well as
> > the PN of the comparator based circuit (with CMOS output buffer).
> > 
> 
> These plots came from the Wenzel diff-amp shaper:
> http://www.ke5fx.com/wenzel_resid_PN.png
> http://www.ke5fx.com/wenzel_resid_ADEV.png
> 
> I don't recall many details of the test setup, or how faithful my 
> implementation of the shaper was to Charles W.'s app note, but this is 
> representative of several plots I have lying around. Not bad performance at 
> all for the cost/complexity involved. 
> 
> -- john, KE5FX
> Miles Design LLC
> 
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Re: [time-nuts] sine to square wave circuits - performance data?

[Bruce Griffiths]

PN measurements for LTC6957-4 here:

http://www.ko4bb.com/getsimple/index.php?id=phase-noise-and-other-measurements-with-a-timepod

NB HX2410 plot below is for a Holzworth sine to CMOS converter.

Bruce

> On 04 October 2017 at 12:02 Bruce Griffiths <bruce.griffi...@xtra.co.nz> 
> wrote:
> 
> 
> Attila
> 
> I have measured the PN of the LTC6957-4 at 10MHz.
> 
> I could measure the PN of the TAPR variant of the Wenzel circuit as well 
> as the PN of the comparator based circuit (with CMOS output buffer).  
> 
> Bruce
> 
> > > 
> > On 04 October 2017 at 11:38 Attila Kinali <att...@kinali.ch> wrote:
> > 
> > Moin,
> > 
> > The last couple of days, I have been looking into sine to square
> > wave converters. There are a few proposed circuits[1-4] and there
> > is of course Collins' paper [5]. But I am unable to find actual
> > performance data of the different circuits. Does someone have
> > such data and would share it with me/us?
> > 
> > Attila Kinali
> > 
> > [1] http://www.wenzel.com/documents/waveform.html
> > [2] http://www.ko4bb.com/~bruce/ZeroCrossingDetectors.html
> > [3] http://www.ko4bb.com/~bruce/CLKSHPR.html
> > [4] https://www.tapr.org/kits_t2-mini.html
> > [5] "The Design of Low Jitter Hard Limiters", by Collins 1996
> > 
> > http://ieeexplore.ieee.org/document/494304/
> > --
> > You know, the very powerful and the very stupid have one thing in 
> > common.
> > They don't alters their views to fit the facts, they alter the 
> > facts to
> > fit the views, which can be uncomfortable if you happen to be one 
> > of the
> > facts that needs altering. -- The Doctor
> > 
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> > 
> > > 
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Re: [time-nuts] sine to square wave circuits - performance data?

[Bruce Griffiths]

Attila

I have measured the PN of the LTC6957-4 at 10MHz.

I could measure the PN of the TAPR variant of the Wenzel circuit as well as the 
PN of the comparator based circuit (with CMOS output buffer).  

Bruce

> 
> On 04 October 2017 at 11:38 Attila Kinali  wrote:
> 
> Moin,
> 
> The last couple of days, I have been looking into sine to square
> wave converters. There are a few proposed circuits[1-4] and there
> is of course Collins' paper [5]. But I am unable to find actual
> performance data of the different circuits. Does someone have
> such data and would share it with me/us?
> 
> Attila Kinali
> 
> [1] http://www.wenzel.com/documents/waveform.html
> [2] http://www.ko4bb.com/~bruce/ZeroCrossingDetectors.html
> [3] http://www.ko4bb.com/~bruce/CLKSHPR.html
> [4] https://www.tapr.org/kits_t2-mini.html
> [5] "The Design of Low Jitter Hard Limiters", by Collins 1996
> 
> http://ieeexplore.ieee.org/document/494304/
> --
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering. -- The Doctor
> 
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Re: [time-nuts] Isolated 1PPS-input for distribution-amp?

[Bruce Griffiths]

HCPL7101 and similar 50MBaud optocouplers claim 50ps rms jitter.

Some non optical isolated couplers specify ~30ps jitter.


Bruce

> 
> On 01 September 2017 at 00:12 Anders Wallin  
> wrote:
> 
> Hi all,
> I'm looking for a solution for galvanic isolation of a 1PPS signal-input 
> to
> a distribution amplifier.
> 
> We have an old box using HCPL-2411 at the input followed by 74LS04, but 
> the
> degraded rise-time (from below 3ns out of a clock, to >12 ns out of the
> box) and increased jitter (from below TIC-resolution of 20ps out of the
> clock to 700ps std.dev at 100s out of the box) are now limiting our
> measurements.
> 
> Does anyone have experience with a circuit with good rise-time and low
> jitter?
> Should I look for better optoisolators, or pulse-transformers, or 
> something
> else?
> 
> thanks for your input!
> Anders
> 
> PS. I started on publishing my distribution-amplifier (non isolated) on 
> the
> ohwr.org site, see https://www.ohwr.org/projects/pda-8ch-fda-8ch/wiki/wiki
> 
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Bruce Griffiths]

With a sinewave input LF feedback from the 74AC04 output to the shaper inputs 
could be used to regulate the output duty cycle by adjusting the switching 
threshold. However ensuring that the input amplitude is sufficiently large to 
override potential LF oscillation. The LF feedback will also compensate for 
delay asymmetry in the 74AC04 as well.

The output transition times of ACMOS is relatively slow compared to modern 
LVCMOS parts.  

Bruce 
> On 09 July 2017 at 12:15 Mark Sims  wrote:
> 
> 
> I think the way the fine cal works by checking the the intervals between four 
> different edges that a lot of asymmetries in the signals are nulled out in 
> the software.
> 
> How good are 1:2 180 degree phase shifters at exactly shifting by 180 
> degrees?   At what cost?   
> 
> Also coax and RF relays cost a lot.   Pretty soon your BOM cost is over what 
> a 59992A will run... assuming you can find one.
> 
> So far my design is tending towards:  10MHz ref input -> Minicircuits doubler 
> -> Wenzel squarer -> 74AC74 divider -> 74AC04 buffer -> level shifter.  The 
> doubler/divider might not be needed,  but I think it will give a more 
> symmetric output.  I might include a space for a 10 MHz TTL oscillator for 
> non time-nut users... hopefully it might be stable enough over the short time 
> interval for a cal measurement cycle.
> 
> For the gain cal an 5V LM4040 (or other) reference.   Routing signals to the 
> output BNC's via 2P4T slide switches.  The slide switches might be a weak 
> link... but they are less than 50 cents each.  Whatever, it should beat the 
> pants off doing just the "quick TI cal"
> 
> The reason I started looking into this is that I want to upgrade the old 
> firmware to a much newer version that allows the comma separators in the 
> decimal digits.   Upgrading the firmware requires a new calibration.
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters

[Bruce Griffiths]

The simplest solution to the divider and clock shaper is perhaps to use an 
LTC6954. The LTC6954 offers PECL/CMOS and LVDS outputs together with a low 
jitter (sub ps) programmable (SPI) divider (1-63).A couple of coax relays like 
those from Dow Key microwave together with some hardline and a couple of 
splitters could be used to implement the signal switching. 

> 
> On 09 July 2017 at 09:53 Hal Murray  wrote:
> 
> t...@leapsecond.com said:
> 
> > > 
> > The PIC dividers are good to a couple ps. I suspect the larger 
> > issue is the
> > PCB and wiring design.
> > 
> > > 
> What does "good" mean?
> 
> I'd expect the variations due to power or temperature would be easy to
> measure.
> 
> Delay through classic CMOS is linear with absolute temperature and inverse
> linear with supply voltage.
> 
> The classic way to get time-nuts level noise on FPGA outputs is to wiggle 
> a
> nearby pin. That shouldn't be a problem with a dedicated PIC but would
> probably show up if you are generating multiple frequencies.
> 
> --
> These are my opinions. I hate spam.
> 
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Bruce Griffiths]

A run of the mill 2 way power splitter has better than 10ps phase matching at 
100MHz there are few digital devices that offer that degree of matching at best 
they are usually 10x worse.

Bruce

> 
> On 09 July 2017 at 06:58 Mark Sims  wrote:
> 
> Yes, they do show up... but usually for big-ish bucks. I want to build a 
> small affordable replacement that anybody with a 531xx can have.
> 
> My design is currently leaning towards a board with the clock generator 
> and a 5V reference for the gain calibration (they spec 5V +/- 1mV). I was 
> going to use a couple of 2P4T slide switches to route open circuit, 5V, 
> normal clock, and inverted clock to the two output connectors.
> 
> I think the cost to build would be in the $20 range and fit on a 2x2" or 
> so circuit board... certainly more attractive than a $500 big ancient box 
> with unobtainium parts in it. The board should be able to perform all the 
> calibration steps for the counter.
> 
> I don't think the signal requirements are super critical. They are using 
> 1:2 splitters and splitter/180 degree phase shifters and relays to generate 
> the output signals passively from the inputs. I think a digital clock 
> generator would be a LOT more accurate than those phase shifters.
> 
> 
> 
> > > 
> > Actually, you can get J06 HP-59992A calibrators on eBay.
> > 
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Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Bruce Griffiths]

They aren't idiot proof though.

I've seen them assembled backwards so that the contact occurred on the flat 
springs with predictable results. 

Bruce

> 
> On 22 June 2017 at 19:19 Tom Van Baak  wrote:
> 
> Wes, Don,
> 
> I am quite surprised at the negative reaction to Anderson Power Pole 
> connectors. I have found them the best DC connector out there. I have used 
> them for a decade or two for all my DC feeds and have never had a problem: in 
> my home lab, my car, even for my laptop charger. They are inexpensive, 
> reliable, genderless (hermaphroditic) and easy to crimp. I use them for my 
> 5V, 12V, 24V, and 48V supplies as well as my DC backup systems.
> 
> What on earth are you doing with them that causes them to disconnect? I 
> mean, they are not meant for towing or lifting or rappelling. For critical 
> applications there is a plastic gizmo that keeps them mated; or just use a 
> square or figure 8 knot on the cables.
> 
> /tvb
> 
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Re: [time-nuts] Charles Wenzel GPSDO

[Bruce Griffiths]

The monostable is a bit of a kludge.
Surely using a shift register to synchronise the PPS to 10MHz (or 1MHz) and 
comparing (using the same gated integrator arrangement) the synchroniser delay 
against a fixed pulse width generated by different taps on the same SR would be 
somewhat more stable? The fixed pulse width should be integer + 0.5 Shift 
Register clock periods. Ideally one would also remove the sawtooth error from 
the PPS before synchronising it.

Brucee 
 
> On 22 June 2017 at 12:50 paul swed  wrote:
> 
> 
> Love the flexibility and the simplicity. You could use about anything.
> Simple enough to try for fun.
> Regards
> Paul
> WB8TSL
> 
> On Wed, Jun 21, 2017 at 7:05 PM, Graham  wrote:
> 
> > Very cool.
> >
> > I too have a dislike for these coaxial type power connectors for just the
> > same reason, same goes for mini and micro USB and the like.
> >
> > I do use a lot of Power Pole connectors (crimped with a proper crimping
> > tool - not soldered) but in an application like this where there is
> > sufficient space I like to use 4 pin XLR connectors (Neutrik is my
> > preference). These are good for 10 amps, polarized, and lock in place and 4
> > pin simply because that is what I started to use many (many) years ago (3
> > pin for audio and 5 pin for data).
> >
> > cheers, Graham ve3gtc
> >
> >
> > On 2017-06-21 21:36, Brooke Clarke wrote:
> >
> >> Hi Chuck:
> >>
> >> I'd replace the push on DC power connector with a high force Power Pole.
> >> I can't count how many times one of these push on connectors has worked
> >> itself loose.
> >> http://www.prc68.com/I/PowerPole.shtml
> >>
> >>
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Re: [time-nuts] SR620/PM66xx/CNT-90 input stages

[Bruce Griffiths]

Your assumptions about my comment are unfounded. It was just intended as an 
additional reason as to why direct connection to a comparator input isnt a good 
idea with a high source impedance. The original post asked why a buffer was 
needed.

 Bruce

> 
> On 21 June 2017 at 22:14 Charles Steinmetz  wrote:
> 
> Bruce wrote:
> 
> > > 
> > If the source impendance at dc is 10k at dc a bias current of a few
> > microamp produces a dc offset of tens of millivolts which may be an
> > issue if the signal amplitude is low and has a low slew rate.
> > 
> > > 
> Jeez, Bruce, it was nothing but a thought experiment to illustrate why
> an amplifier's DC input current is not a reliable proxy for input
> impedance It was not a suggestion for how to design an amplifier input.
> And that should have been obvious to you -- I'm sure it was to
> everyone else.
> 
> Get a life.
> 
> Charles
> 
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Re: [time-nuts] SR620/PM66xx/CNT-90 input stages

[Bruce Griffiths]

If the source impendance at dc is 10k at dc a bias current of a few microamp 
produces a dc offset of tens of millivolts which may be an issue if the signal 
amplitude is low and has a low slew rate. 

Bruce

> 
> On 21 June 2017 at 09:11 Charles Steinmetz  wrote:
> 
> Attila wrote:
> 
> > > 
> > Now, if the downstream circuit would be low
> > impedance, I could understand that, but the sink is a comparator 
> > with a
> > high impedance input (only a few µA input current). I am sure the 
> > engineers
> > had a good reason to add those amplifiers, but I cannot guess why. 
> > Would
> > someone be so kind and enlighten me?
> > 
> > > 
> I was going tp post the Smith chart for the input of the AD96885/7 ECL
> comparator they use, but was surprised to find that AD did not include
> it on the datasheet. However, just from the spec table we can see why a
> buffer is necessary:
> 
> Input Resistance: 200k ohms
> Input Capacitance: 2pF
> 
> For starters, even at low frequencies the input impedance is only 200k
> ohms, much less than the 1Mohm rated impedance. Further, the
> capacitance seriously degrades bandwidth to as low as 400kHz (this
> depends on the source impedance, but even with a 10kohm source the BW is
> only 8MHz).
> 
> (Note that the input current spec is not necessarily a good proxy for
> input impedance -- consider a FET-input amplifier with an input current
> of 1uA and a 100k gate resistor.)
> 
> Best regards,
> 
> Charles
> 
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Re: [time-nuts] SR620/PM66xx/CNT-90 input stages

[Bruce Griffiths]

Its somewhat difficult to achieve a 1Megohm input with just a bipolar 
comparator input stage especially if AC coupling is required.

Bruce

> 
> On 20 June 2017 at 19:20 Attila Kinali  wrote:
> 
> Hi,
> 
> I had a look at the PM668x[1] and CNT-90[2] schematics yesterday and
> noticed one thing: The input stages are strikingly similar to the
> SR620[3] (down to the parts used) and all of them have a gain 1 amplifier
> infront of the comparator. The PM668x service manual explicitly calls it
> "impedance converter", even. Now, if the downstream circuit would be low
> impedance, I could understand that, but the sink is a comparator with a
> high impedance input (only a few µA input current). I am sure the 
> engineers
> had a good reason to add those amplifiers, but I cannot guess why. Would
> someone be so kind and enlighten me?
> 
> Attila Kinali
> 
> [1] 
> http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Fluke/Fluke_PM6681_Service_Manual.pdf
> [2] http://assets.fluke.com/manuals/6690smeng.pdf
> [3] 
> http://www.ko4bb.com/getsimple/index.php?id=download=02_GPS_Timing/Stanford_Research_Systems/SR620_Universal_Time_Interval_Counter_Schematics.pdf
>  
> http://www.ko4bb.com/getsimple/index.php?id=download=02_GPS_Timing/Stanford_Research_Systems/SR620_Universal_Time_Interval_Counter_Schematics.pdf
> 
> --
> 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] backfill

[Bruce Griffiths]

alpha quartz to beta quartz phase transition at 573C amongst other factors.

Bruce

> 
> On 10 June 2017 at 12:31 Hal Murray  wrote:
> 
> > > 
> > You can’t quite process a crystal at 300C, but you can get close.
> > 
> > > 
> What happens if you get it too hot or too long? What's the limiting 
> factor?
> 
> --
> These are my opinions. I hate spam.
> 
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Bruce Griffiths]

Additional info/papers on Thermistor stability:

http://www.digikey.com/en/pdf/u/us-sensor/us-sensor-stability-long-term-aging

https://www.thermistor.com/sites/default/files/specsheets/T150-Series-Stability.pdf

https://www.vishay.com/docs/49498/ntcs-e3-smt_vmn-pt0283.pdf

>From LIGO:

http://www.aspe.net/publications/Annual_2008/POSTERS/08UNCER/2643.PDF

Bruce


> 
> On 06 June 2017 at 09:49 Bruce Griffiths <bruce.griffi...@xtra.co.nz> 
> wrote:
> 
> Here's a NIST paper on Thermistor stability:
> 
> http://nvlpubs.nist.gov/nistpubs/jres/83/jresv83n3p247_A1b.pdf
> 
> Bruce
> 
> > > 
> > On 06 June 2017 at 01:45 Bob kb8tq <kb...@n1k.org> wrote:
> > 
> > Hi
> > 
> > Well, as part of the process of designing them into OCXO’s you do 
> > indeed check their long term stability.
> > The test is done in an indirect fashion so you only come up with a 
> > “it’s below the limit” sort of number. The
> > typical process involves running a group of OCXO’s on turn to check 
> > the frequency and then shifting them
> > off turn to make a sort of thermometer. After a few months of 
> > frequency readings you take them back to turn
> > for a while. Relative frequency shift math gives you a stability 
> > number for the thermistor and the rest of the
> > circuitry. You may repeat the run for months / shift process a 
> > couple of times. If the answer isn’t “I can’t see
> > a difference” you look for a new thermistor. Since it’s a long 
> > drawn out test, the tendency is to stick with a
> > vendor’s part for quite a while. The parts also tend to be design 
> > specific so what works in my (say SMT)
> > design may not work well in your (say chip and wire) design.
> > 
> > Bob
> > 
> > > > > 
> > > > > > > 
> > > > On Jun 5, 2017, at 9:20 AM, romeo987 
> > > > <romeo...@westnet.com.au> wrote:
> > > > 
> > > > > > > 
> > > Hi, guys
> > > I have been following time nuts and volt nuts for some time 
> > > out of interest and fascination. Although my personal backyard hobby is 
> > > more along a volt nuts line, the two worlds often collide - like in this 
> > > discussion of temperature sensors, and in particular their long term 
> > > stability. NTC thermistors appear to be very commonly used in ovens used 
> > > to stabilize voltage references (solid state as well as chemical) . I 
> > > have long wondered about their stability. If, as Bruce asserts, "high 
> > > quality thermistors can achieve drifts of around 1mK/month" then it 
> > > appears that this level of drift is a significant factor in the 
> > > "apparent" aging of, say, a bank of Weston cells (which is still my best 
> > > backyard shot at a voltage reference).
> > > 
> > > I have had no luck with Google; Bruce's statement is the 
> > > first quantified allusion that I have seen to this subject. Is there any 
> > > actual data available on the long term performance of NTC sensors?
> > > 
> > > Roman
> > > 
> > > > > > > 
> > > > > > > > > 
> > > > > > > > > > > 
> > > > > > On 5 Jun 2017, at 9:53 AM, Bruce Griffiths 
> > > > > > <bruce.griffi...@xtra.co.nz> wrote:
> > > > > > 
> > > > > > > > > > > 
> > > > > > > > > 
> > > > The other issue that needs to be considered is the 
> > > > drift in temperature sensor characteristics when operated at a constant 
> > > > temperature (as is typical in a continuously operated crystal oven). 
> > > > High quality thermistors can achieve drifts of around 1mK/month. Its 
> > > > unlikely that something as complex as an AD590 will achieve a similar 
> > > > drift (1nA/month in a operating current of 300uA or so at 25C). High 
> > > > quality PRT sensors drift even less than thermistors when operating at 
> > > > constant temperature.
> > > > 
> > > > Bruce
> > > > 
> > > > > > > > > 
> > > &g

Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Bruce Griffiths]

Here's a NIST paper on Thermistor stability:

http://nvlpubs.nist.gov/nistpubs/jres/83/jresv83n3p247_A1b.pdf

Bruce

> 
> On 06 June 2017 at 01:45 Bob kb8tq <kb...@n1k.org> wrote:
> 
> Hi
> 
> Well, as part of the process of designing them into OCXO’s you do indeed 
> check their long term stability.
> The test is done in an indirect fashion so you only come up with a “it’s 
> below the limit” sort of number. The
> typical process involves running a group of OCXO’s on turn to check the 
> frequency and then shifting them
> off turn to make a sort of thermometer. After a few months of frequency 
> readings you take them back to turn
> for a while. Relative frequency shift math gives you a stability number 
> for the thermistor and the rest of the
> circuitry. You may repeat the run for months / shift process a couple of 
> times. If the answer isn’t “I can’t see
> a difference” you look for a new thermistor. Since it’s a long drawn out 
> test, the tendency is to stick with a
> vendor’s part for quite a while. The parts also tend to be design 
> specific so what works in my (say SMT)
> design may not work well in your (say chip and wire) design.
> 
> Bob
> 
> > > 
> > On Jun 5, 2017, at 9:20 AM, romeo987 <romeo...@westnet.com.au> 
> > wrote:
> > 
> > Hi, guys
> > I have been following time nuts and volt nuts for some time out of 
> > interest and fascination. Although my personal backyard hobby is more along 
> > a volt nuts line, the two worlds often collide - like in this discussion of 
> > temperature sensors, and in particular their long term stability. NTC 
> > thermistors appear to be very commonly used in ovens used to stabilize 
> > voltage references (solid state as well as chemical) . I have long wondered 
> > about their stability. If, as Bruce asserts, "high quality thermistors can 
> > achieve drifts of around 1mK/month" then it appears that this level of 
> > drift is a significant factor in the "apparent" aging of, say, a bank of 
> > Weston cells (which is still my best backyard shot at a voltage reference).
> > 
> > I have had no luck with Google; Bruce's statement is the first 
> > quantified allusion that I have seen to this subject. Is there any actual 
> > data available on the long term performance of NTC sensors?
> > 
> > Roman
> > 
> > > > > 
> > > On 5 Jun 2017, at 9:53 AM, Bruce Griffiths 
> > > <bruce.griffi...@xtra.co.nz> wrote:
> > > 
> > > The other issue that needs to be considered is the drift in 
> > > temperature sensor characteristics when operated at a constant 
> > > temperature (as is typical in a continuously operated crystal oven). High 
> > > quality thermistors can achieve drifts of around 1mK/month. Its unlikely 
> > > that something as complex as an AD590 will achieve a similar drift 
> > > (1nA/month in a operating current of 300uA or so at 25C). High quality 
> > > PRT sensors drift even less than thermistors when operating at constant 
> > > temperature.
> > > 
> > > Bruce
> > > 
> > > > > > > 
> > > > .On 05 June 2017 at 11:59 Attila Kinali 
> > > > <att...@kinali.ch> wrote:
> > > > 
> > > > Moin,
> > > > 
> > > > This discussion is kind of getting heated.
> > > > Let's put some facts in, to steer it away from
> > > > opinion based discussion.
> > > > 
> > > > On Sun, 4 Jun 2017 08:44:33 -0700
> > > > "Donald E. Pauly" <trojancow...@gmail.com> wrote:
> > > > 
> > > > > > > > > 
> > > > > I stand by my remark that thermistors have been 
> > > > > obsolete for over 40
> > > > > years. The only exception that I know of is 
> > > > > cesium beam tubes that
> > > > > must withstand a 350° C bakeout. Thermistors are 
> > > > > unstable and
> > > > > manufactured with a witches brew straight out of 
> > > > > MacBeth. Their
> > > > > output voltages are tiny and are they 
> > > > > inconvenient to use at different
> > > > >

Re: [time-nuts] poor-man's oven

[Bruce Griffiths]

Yes, I have a TEC mounted on a convection heatsink that illustrates that point.
Initially ice forms on the cold surface but eventually the heatsink temperature 
rises sufficiently that the ice melts. A larger blown heatsink or perhaps a 
water cooled heatsink would be necessary if this setup was intended for 
anything other than a demonstration of this issue.

Bruce  

> On 05 June 2017 at 13:58 Bob kb8tq  wrote:
> 
> 
> Hi
> 
> Many times people underestimate the amount of heat sinking required with a 
> TEC. If you get into fans, they 
> introduce a whole new set of issues ….It’s not just the heat you are getting 
> out of the “oven”. The TEC it’s self
> makes a pretty good thermal short (compared to foam insulation). You have to 
> “pump” across that as well. 
> 
> Bob
> 
> > On Jun 4, 2017, at 9:38 PM, Ellen Franke  wrote:
> > 
> > My concern with using a TEC is that, heating or cooling, you are left with 
> > one cold surface and that surface will collect condensation which is a 
> > source for corrosion.
> > John WA4WDL
> > 
> > 
> >> On June 4, 2017 at 8:12 PM Attila Kinali  wrote:
> >> 
> >> 
> >> Moin Chris,
> >> 
> >> On Sun, 4 Jun 2017 13:49:29 -0700
> >> Chris Albertson  wrote:
> >> 
> >>> We used the pelter because we preferred a cool "oven" to a hot one.   The
> >>> theory has that we get less electronic noise so we ran the TEC in cooling
> >>> mode.   But for your use a resistive heater would be cheaper.   But in
> >>> either case you see a coffee mug with a round chunk of Al shoved in and
> >>> heat sink fins showing.
> >> 
> >> What is the reason why you'd expect less noise with a TEC?
> >> 
> >>Attila Kinali
> >> 
> >> -- 
> >> You know, the very powerful and the very stupid have one thing in common.
> >> They don't alters their views to fit the facts, they alter the facts to
> >> fit the views, which can be uncomfortable if you happen to be one of the
> >> facts that needs altering.  -- The Doctor
> >> ___
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> >> To unsubscribe, go to 
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> >> and follow the instructions there.
> > ___
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Re: [time-nuts] poor-man's oven

[Bruce Griffiths]

Really??

The circuitry employed is something of a joke surely?

Relying on the   MOSFET characteristics to limit warm up current is unwise.

The temperature sensor also would appear to suffer from large variations in 
output from one part to another.

Bruce

> 
> On 05 June 2017 at 01:21 "R. Kuehn"  wrote:
> 
> Maybe you want to check out the work of Hans Summers he has done some
> impressive low cost stuff:
> http://www.hanssummers.com/ocxosynth.html
> http://www.qrp-labs.com/ocxokit.html
> 
> Ralph
> 
> On Sun, Jun 4, 2017 at 07:19 jimlux  wrote:
> 
> > > 
> > I recall some years ago folks were talking about putting a PTC
> > thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the 
> > frequency
> > as a sort of poor-man's OCXO.
> > It's also referenced at
> > http://www.setileague.org/askdr/xtaloven.htm
> > where he says "order of magnitude improvement" with no numbers 
> > (from 1%
> > to 0.1% or from 1 ppb to 0.1 ppb?)
> > 
> > I wonder how well that actually works.
> > 
> > Say you bought an inexpensive (perhaps non TC) XO and an equally
> > inexpensive thermistor, glued on on the other, hooked em both up to 
> > 3.3
> > or 5V.
> > 
> > Yeah, there's issues with room air blowing on it, and tolerances in 
> > both
> > the XO and thermistor, so your absolute frequency accuracy may not 
> > be so
> > hot. But what sort of medium to long term performance can one 
> > expect.
> > 
> > I did some searches, because I'm sure we've discussed this before, 
> > but I
> > couldn't find it. There was some stuff from Oct 2007, but that was 
> > in
> > the context of a more complex circuit, and the thermistor was the
> > sensor. (discussions of TE devices too)
> > 
> > ___
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Re: [time-nuts] Temperature sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)

[Bruce Griffiths]

The other issue that needs to be considered is the drift in temperature sensor 
characteristics when operated at a constant temperature (as is typical in a 
continuously operated crystal oven). High quality thermistors can achieve 
drifts of around 1mK/month. Its unlikely that something as complex as an AD590 
will achieve a similar drift (1nA/month in a operating current of 300uA or so 
at 25C). High quality PRT sensors drift even less than thermistors when 
operating at constant temperature.

Bruce

> 
> .On 05 June 2017 at 11:59 Attila Kinali  wrote:
> 
> Moin,
> 
> This discussion is kind of getting heated.
> Let's put some facts in, to steer it away from
> opinion based discussion.
> 
> On Sun, 4 Jun 2017 08:44:33 -0700
> "Donald E. Pauly"  wrote:
> 
> > > 
> > I stand by my remark that thermistors have been obsolete for over 40
> > years. The only exception that I know of is cesium beam tubes that
> > must withstand a 350° C bakeout. Thermistors are unstable and
> > manufactured with a witches brew straight out of MacBeth. Their
> > output voltages are tiny and are they inconvenient to use at 
> > different
> > temperatures.
> > 
> > > 
> If you really mean thermistors, and not, as Bob suggested thermocouples,
> then I have to disagree. The most stable temperature sensors are
> platinum wire sensors. The standards class PRT's are the gold standard
> when it comes to temperature measurement, for a quite wide range
> (-260°C to +960°C) and are considered very stable. They offer (absolute)
> accuracies in the order of 10mK in the temperature range below 400°C.
> Even industrial grade PRT sensors give you an absolute accuracy better
> than 0.1K up to 200-300°C. The "cheap" PT100 are more of the order of 
> 1-10°C
> accuracy... all numbers just using a two-point calibration.
> 
> For more information on this see [1] chapter 6 and [2] for industrial 
> sensors.
> 
> NTC sensors have a higher variablity of their parameters in production
> and are usually specified in % of temperature relative to their reference
> point, which is usually 25°C. Typical values are 0.1% to 5%. Additionally
> there is a deviation from the reference point, specified in °C, which
> is usually in the order of 0.1°C to 1°C.
> 
> The NTC sensors are less accurate than PT sensors, but offer the advantage
> of higher resistance (thus lower self-heating), higher slope (thus better
> precision). Biggest disadvantage is their non-linear curve. Their price
> is also a fraction of PT sensors and due to that you can have them in
> many different forms, from the 0201 SMD resistor, to a large stainless
> steal pipe that goes into a chemical tank. NTCs are the workhorse in
> todays temperature measurement and control designs.
> 
> The next category are band-gap sensors like the AD590. Their biggest
> advantage is that their 0 point is fix at 0K (and very accurately so).
> Ie they can be used with single point calibration and achieve 1°C accuracy
> this way. Their biggest drawback their large thermal mass and large
> insulating case, because they are basically an standard, analog IC.
> Ie their main use is in devices where there is a lot of convection and
> slow temperature change. Due to their simple and and quite linear
> characteristics, they are often used in purely analog temperature
> control circuits, or where a linearization is not feasible.
> But only if price isn't an issue (they cost 10-1000 times as
> much as an PTC). Their biggest disadvantage, beside their slow
> thermal raction time, is their large noise uncorrelated to the
> supply voltage, and thus cannot be compensated by ratiometric measurement.
> They are also more suceptible to mechanical stress than NTC's and PT's,
> due to their construction. Similar to voltage references (which they
> actually are), their aging is quite substantial and cannot be neglected
> in precision application.
> With a 3 point calibration, better than 0.5°C accuracy can be achieved
> (modulo aging) within their operating temperature range, which is
> rather limited, compared to the other sensor types.
> 
> I don't know enough about thermocouples to say much about them, beside
> that they are cumbersome to work with (e.g. the cold contact) and
> produce a low voltage (several µV) output with quite high impedance,
> which makes the analog electronics difficult to design as well.
> 
> With todays electronics, the easiest sensors to work with are NTC and
> PT100/PT1000 as most high resolution delta-sigma ADCs have direct support
> for 3 and/or 4 wire measurement of those, including compensation for
> reference voltage/current variation. Using a uC as control element
> also 

Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Bruce Griffiths]

Thermomechanical fatigue can significantly reduce the lifetime of Peltier 
devices if the ripple current flowing in the Peltier device is too high. This 
can become an issue with switchmode drive to a Peltier cooler.

Bruce


> 
> On 03 June 2017 at 11:02 jimlux  wrote:
> 
> On 6/2/17 2:51 PM, Donald E. Pauly wrote:
> 
> > > 
> > This is an improvement of 476 to 1. You apparently have not thought
> > thru what improvements are possible with thermal coolers/heaters.
> > Among these is near instant warm up and greatly reduced power for
> > thermal management.
> > 
> > > 
> without getting into the whole crystal issue, one of the advantages of a
> heater is that it can be VERY simple (and hence reliable, just on a
> parts count basis). With a decent package, once it's hot, the power
> required to keep it hot can be quite low.
> 
> With a heat/cool, you need to be able to have a bipolar supply to the
> peltier device, and they're not particularly efficient (that is, to
> extract 1 Watt of heat, you're putting in significantly more than 1 watt
> of DC, and rejecting 1+X watts to the outside world.
> 
> And then, if you use a linear power supply/amplifier to drive the
> device, that is probably a class A device, and somewhat lossy. A
> switcher would be more efficient, but then you have the problem of
> switching noise, in close proximity to the crystal. You could put a big
> low pass filter in, but now you're adding even more components.
> 
> There are undoubtedly some cases where the thermoelectric scheme would
> work better - for instance, you have a system with a TCXO and it's
> really set up for the TCXO to be at 25C, and you want to regulate that.
> 
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Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies

[Bruce Griffiths]

With an AT crystal, manufacturing tolerances will likely ensure that the 
inflection point slope is non zero whereas the same manufacturing tolerances 
will merely change the turnover temperature. Its likely that a more 
manufacturable design will result if one operates at a turnover point (with the 
oven temperature adjusted to the actual turnover) than trying to achieve a 
sufficiently low slope at an inflection point. Even for a one off design one 
the selection process required to achieve a sufficiently low slope at the 
inflection point may prove expensive. 

Bruce

> 
> On 03 June 2017 at 09:51 "Donald E. Pauly"  wrote:
> 
> # 2 is not true. A cut has either two turning points or zero. Where
> both turning points exist there are two temperatures at which the
> temperature coefficient of frequency is zero. Cut 0 on figure 6 at
> https://coloradocrystal.com/applications has no turnover point. It is
> neither fish nor fowl. Cut 6 is the normal AT curve with extremes of
> ±16 ppm for -55° C thru +105° C. All curves normally intersect at 25°
> C rather than the 27° C shown. 25° C is half way between -55° C thru
> +105° C. Curve 6 is the Tchebychev polynomial y=4x^3-3x and curve 0
> is y=4x^3.
> 
> Consider the standard AT cut which has turnover points at -15° C and
> 65° C. The lower turnover would ordinarily not be used in ovens. A
> set point error of ±1° C in the upper turnover point at 65° C results
> in a frequency error of +14.875·10^-9. For cut 0, that same ±1° error
> in room temperature results in a frequency error of ±31.25·10^-12.
> This is an improvement of 476 to 1. You apparently have not thought
> thru what improvements are possible with thermal coolers/heaters.
> Among these is near instant warm up and greatly reduced power for
> thermal management.
> 
> πθ°μΩω±√·Γ
> WB0KVV
> 
> -- Forwarded message --
> From: Bob kb8tq 
> Date: Fri, Jun 2, 2017 at 12:43 PM
> Subject: Re: HP5061B Versus HP5071 Cesium Line Frequencies
> To: "Donald E. Pauly" 
> 
> Hi
> 
> Which statement is not true:
> 
> 1) That there is a tolerance on the cut angle of a crystal?
> 
> 2) That true zero temperature coefficient only happens at the turn?
> 
> 3) That heater based controllers are impossible to build?
> 
> Bob
> 
> On Jun 2, 2017, at 3:40 PM, Donald E. Pauly  
> wrote:
> 
> That is not true. I say that thermal coolers have made ovens
> obsolete. A zero temperature coefficient at room temperature is
> easier to hit than a zero temperature at the upper turnover point when
> such a thing exists. See
> curve 0 in Figure 6 at https://coloradocrystal.com/applications/ .
> 
> πθ°μΩω±√·Γ
> WB0KVV
> 
> On Friday, June 2, 2017, Bob kb8tq  wrote:
> >
> 
> > > 
> > Hi
> > 
> > Any real crystal you buy will have a tolerance on the angle. In the 
> > case of a crystal cut for turn
> > the temperature will be a bit different and you will match your 
> > oven to it. If you attempt a zero
> > angle cut, you will never really hit it and there is no way to 
> > compensate for the problem.
> > 
> > Bob
> > 
> > ___
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> > To unsubscribe, go to 
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> > 
> > > 
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Re: [time-nuts] Counter Internal Oscillator Importance with External Reference?

[Bruce Griffiths]

CERN have flagged another potential issue with the 53230A in that every so 
often seemingly randomly communications go hawire.

Bruce 

> 
> On 10 May 2017 at 04:46 "Richard (Rick) Karlquist" 
>  wrote:
> 
> On 5/9/2017 12:05 AM, Poul-Henning Kamp wrote:
> >
> 
> > > 
> > I'm sure that modern counters like 53230 are better at this than
> > 
> > > 
> The 53230 oven oscillator option in an inferior oscillator to
> the 10811, by an order of magnitude. So in this case,
> modern != better.
> 
> Rick
> 
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Re: [time-nuts] Frequency counter questions

[Bruce Griffiths]

Use a USB or LSB mixer, it only requires a few more parts and a little 
ingenuity.

Bruce

> 
> On 27 April 2017 at 06:52 al wolfe  wrote:
> 
> I am surprised that no one has mentioned the idea of heterodyning a
> known frequency with the unknown to measure the unknown. I use a
> Minicircuits doubly balanced mixer fed on one port from a PTS160
> synthesizer that is locked to 10 mhz. from a TrueTime xl-ak GPS locked
> receiver. The second port is fed by the unknown though an attenuator.
> The third port of the mixer gives me the sum and difference. If the
> difference is an audio note then a cheep but frequency locked counter
> will read out the difference or measure the period of the beat note
> which can be added to the frequency of the synthesizer. A program such
> as Lady Heather can also be used to determine the audio frequency to
> much less then sub-cycle accuracy. The only fly in the ointment is
> figuring out which side of the unknown the synthesizer is set to.
> 
> Alternatively, the PTS160 with 0.1 cycle control can be set to nearly
> zero beat with the unknown. Then watching either lissajous or dual
> trace scope patterns and timing the beat notes one can get the unknown
> frequency very close.
> 
> Al, retired, mostly
> AKA k9si
> 
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Re: [time-nuts] Frequency counter questions

[Bruce Griffiths]

Reciprocal counter where one measures the period of the output of a divide by N 
and then takes the reciprocal of this period multiplied by N as the frequency 
of the divider input. With a 100MHz clock one can achieve ~ 0.01ppm resolution  
for a 1 second averaging time. if one uses interpolators with 100ps resolution 
(equivalent to a 10GHz clock)  the resolution improves to ~0.1ppb for a 1s 
averaging time.

Bruce

> 
> On 24 April 2017 at 13:25 Jerry Hancock  wrote:
> 
> For some reason I am not getting the individual emails so I apologize for 
> not replying more promptly. I’ll have to check my profile.
> 
> As far as I can tell from the notes, and by the way, the number of notes 
> was why I was trying to move this off list, to get to .001hz I need to 
> measure over 1000 seconds. This is ok. Since I am looking for an average over 
> time anyway, this is not a problem. By the way I am using a GPSDO and planned 
> to use it divided down for the gate.
> 
> The only reason I mentioned a prescaler was that there was a 12 digit 
> counter schematic on the web that looked pretty complete. This person used a 
> prescaler and I was trying to wrap my head around how this helped with 
> resolution and I guess from the replies, that is not a practical solution 
> (using a prescaler) when you want high resolution unless I use the inverse 
> operation which I can’t remember what it is called off the top of my head.
> 
> I’ve seen some HP 12 digit counters but since I have a GPSDO and who 
> knows how many micro development boards around here, I thought I would take a 
> run at it.
> 
> So to summarize, if I limit my high resolution to 99,999,999.999hz and 
> use a gate of 1000 seconds, would that get me to .01hz? If not, then what 
> would the possible resolution be?
> 
> Thanks for all the input, very helpful.
> 
> Jerry
> 
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Re: [time-nuts] HP E1938

[Bruce Griffiths]

More precisely the active EFC range is +1.25 to +3.75V with an absolute minimum 
of 0V and an absolute max of +5V.

At least this is the range that the pseudo differential AD7714 ADC inputs 
monitoring the EFC are configured for.

Bruce

> On 16 April 2017 at 14:57 Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote:
> 
> 
> 0 to +5V dc max, however only the 0 to 2.5V range appears measurable by 
> the AD7714 ADC on the PCB.
> 
> Increasing the EFC voltage decreases the capacitance in series with the 
> crystal requiring an increase in the inductance exhibited by the crystal 
> hence requiring a lower oscillator frequency.
> 
> Bruce
> 
> > > 
> > On 16 April 2017 at 13:01 Larry McDavid <lmcda...@lmceng.com> wrote:
> > 
> > The units now available on eBay have various types of D-Subminiature
> > connectors and can be on either side of the board. I will have to 
> > wait
> > until my unit arrives to see what I get. It should be possible, if
> > necessary, to remove the connector and replace it with a more 
> > convenient
> > D-Submin connector on the desired side of the board.
> > 
> > I did not originally note the additional zip'd info available from 
> > that
> > eBay website but now have those files. Thanks for that link.
> > 
> > So far, I have not seen any spec for the EFC voltage and polarities 
> > used
> > in the "Integrated PWB." Anyone know that?
> > 
> > The "full instrument" version also available now on eBay is a 
> > complete
> > GPSDO but at $130 plus $80 shipping. I really don't need yet another
> > GPSDO but would use the integrated PWB assembly for a low ADEV
> > free-running 10 MHz source. I have a HP 10811D for that now but will
> > evaluate this new unit for performance.
> > 
> > Anyone have experience doing this and know the EFC requirements?
> > 
> > Larry
> > 
> > On 4/15/2017 4:01 PM, Richard (Rick) Karlquist wrote:
> > 
> > > > > 
> > > It's been 20 years, but I will try to recap what I remember
> > > about this connector. I believe there were 3 customers,
> > > and one of them required the DB connector with coax inserts
> > > for reasons of backward compatibility. I think this
> > > vendor was Motorola. We did not actually use the coax
> > > inserts, but left them blank and ran the RF, etc on
> > > ordinary pins. I believe you can make an ordinary male
> > > DB-25 mate with these insert versions by clipping off some
> > > of the pins that would be blocked by the female insert
> > > version. I vaguely remember that the other 2 vendors
> > > used gender changers or something. There might have
> > > an issue with the mating plane location being different
> > > for different customers.
> > > 
> > > I am sure that time-nuts, being talented at repurposing,
> > > will be able to think about this problem and come up with
> > > a simple solution to interfacing with these boards.
> > > No need to buy insert type connectors. I never had
> > > any trouble making cables that connected to these units
> > > using plain vanilla DB25's.
> > > 
> > > Rick N6RK
> > > 
> > > On 4/15/2017 10:42 AM, Larry McDavid wrote:
> > > 
> > > > > > > 
> > > > Ok, so a standard DB 25-pin socket-contact connector 
> > > > will mate with the
> > > > on-board connector with the center hole and missing 
> > > > pins. That's good!
> > > > 
> > > > I now notice a comment on your webpages about this 
> > > > device in which you
> > > > mention a schematic. Do you have a schematic of this 
> > > > board? If so, can
> > > > you point to it or send me a copy.
> > > > 
> > > > I was unaware of the complete packaged unit on eBay; 
> > > > thanks for that.
> > > > 
> > > > Another poster mentioned the wiring of the connector on 
> > > > the full
> > >

Re: [time-nuts] HP E1938

[Bruce Griffiths]

0 to +5V dc max, however only the 0 to 2.5V range appears measurable by the 
AD7714 ADC on the PCB.

Increasing the EFC voltage decreases the capacitance in series with the crystal 
requiring an increase in the inductance exhibited by the crystal hence 
requiring a lower oscillator frequency.

Bruce

> 
> On 16 April 2017 at 13:01 Larry McDavid  wrote:
> 
> The units now available on eBay have various types of D-Subminiature
> connectors and can be on either side of the board. I will have to wait
> until my unit arrives to see what I get. It should be possible, if
> necessary, to remove the connector and replace it with a more convenient
> D-Submin connector on the desired side of the board.
> 
> I did not originally note the additional zip'd info available from that
> eBay website but now have those files. Thanks for that link.
> 
> So far, I have not seen any spec for the EFC voltage and polarities used
> in the "Integrated PWB." Anyone know that?
> 
> The "full instrument" version also available now on eBay is a complete
> GPSDO but at $130 plus $80 shipping. I really don't need yet another
> GPSDO but would use the integrated PWB assembly for a low ADEV
> free-running 10 MHz source. I have a HP 10811D for that now but will
> evaluate this new unit for performance.
> 
> Anyone have experience doing this and know the EFC requirements?
> 
> Larry
> 
> On 4/15/2017 4:01 PM, Richard (Rick) Karlquist wrote:
> 
> > > 
> > It's been 20 years, but I will try to recap what I remember
> > about this connector. I believe there were 3 customers,
> > and one of them required the DB connector with coax inserts
> > for reasons of backward compatibility. I think this
> > vendor was Motorola. We did not actually use the coax
> > inserts, but left them blank and ran the RF, etc on
> > ordinary pins. I believe you can make an ordinary male
> > DB-25 mate with these insert versions by clipping off some
> > of the pins that would be blocked by the female insert
> > version. I vaguely remember that the other 2 vendors
> > used gender changers or something. There might have
> > an issue with the mating plane location being different
> > for different customers.
> > 
> > I am sure that time-nuts, being talented at repurposing,
> > will be able to think about this problem and come up with
> > a simple solution to interfacing with these boards.
> > No need to buy insert type connectors. I never had
> > any trouble making cables that connected to these units
> > using plain vanilla DB25's.
> > 
> > Rick N6RK
> > 
> > On 4/15/2017 10:42 AM, Larry McDavid wrote:
> > 
> > > > > 
> > > Ok, so a standard DB 25-pin socket-contact connector will 
> > > mate with the
> > > on-board connector with the center hole and missing pins. 
> > > That's good!
> > > 
> > > I now notice a comment on your webpages about this device in 
> > > which you
> > > mention a schematic. Do you have a schematic of this board? 
> > > If so, can
> > > you point to it or send me a copy.
> > > 
> > > I was unaware of the complete packaged unit on eBay; thanks 
> > > for that.
> > > 
> > > Another poster mentioned the wiring of the connector on the 
> > > full
> > > instrument version power connector; is that pin-out and spec 
> > > available?
> > > 
> > > Larry
> > > 
> > > On 4/15/2017 5:05 AM, Tom Van Baak wrote:
> > > 
> > > > > > > 
> > > > > > > > > 
> > > > > I purchased one of these HP E1938 OCXO recently 
> > > > > on eBay but have not
> > > > > yet
> > > > > received it.
> > > > > 
> > > > > Is that special D-Submin connector a 
> > > > > receptacle-shell, pin contact
> > > > > version? Will a standard plug-shell, socket 
> > > > > contact 25-pin D-Submin
> > > > > fit it?
> > > > > 
> > > > > > > > > 
> > > > Hi,
> > > > 
> > > > I'll cc the group here since we may get some useful 
> > > > comments.
> > > > 
> > > > I'm not exactly sure what you mean. The E1938A 
> > > > oscillators that I've
> > > > seen and tested look like this:
> > > > 
> > > > http://www.leapsecond.com/museum/e1938a/
> > > > 
> > > > And those can be interfaced with a simple D-sub DB25 
> > > > connector on the
> > > > PCB. For connections, see that page, or any number of 
> > > > postings about
> > > > the E1938 in the time-nuts archives.
> > > > 
> > > > Note that on eBay 

Re: [time-nuts] HP E1938

[Bruce Griffiths]

Tom

#1 proved useful when this sub assembly failed (no 10MHz output) in my E1938A.

Someday I'll disassemble it to see what exactly failed. 

Also have #3 which works well when one figures out the connections on the PCB 
and the unusual backplane connector.


Bruce

> 
> On 16 April 2017 at 00:05 Tom Van Baak  wrote:
> 
> > > 
> > I purchased one of these HP E1938 OCXO recently on eBay but have 
> > not yet
> > received it.
> > 
> > Is that special D-Submin connector a receptacle-shell, pin contact
> > version? Will a standard plug-shell, socket contact 25-pin D-Submin 
> > fit it?
> > 
> > > 
> Hi,
> 
> I'll cc the group here since we may get some useful comments.
> 
> I'm not exactly sure what you mean. The E1938A oscillators that I've seen 
> and tested look like this:
> 
> http://www.leapsecond.com/museum/e1938a/
> 
> And those can be interfaced with a simple D-sub DB25 connector on the 
> PCB. For connections, see that page, or any number of postings about the 
> E1938 in the time-nuts archives.
> 
> Note that on eBay there are at least three variations of E1938A 
> oscillator. The item#'s below are just random search picks (I have no 
> affiliation with any buyers or sellers) and I also know not all surplus 
> refurbished surplus recycled surplus stuff works. But we do this because when 
> they did work, they are sometimes totally amazing.
> 
> 1) There's the bare "puck" alone, as in 
> http://www.ebay.com/itm/290829077542 -- and I have no idea where one would 
> start with that item since all the support circuitry on the PCB would have to 
> be re-created by hand.
> 
> 2) There's the integrated PCB assembly, as in 
> http://www.ebay.com/itm/181043193416 -- which is more like what I tested.
> 
> 3) There's the full instrument version, as in 
> http://www.ebay.com/itm/171293069062 -- which is most likely to work, or be 
> less hacked up, or dented, or salvaged, or rusted. It even has all the 
> connectors and power supplies, and GPS, etc.
> 
> If any other time nuts have experience with each of these methods to 
> obtain a E1938 oscillator, please let us know.
> 
> Thanks,
> /tvb
> 
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Re: [time-nuts] Re. DIY atomic "resonator"

[Bruce Griffiths]

Typically External Cavity diode lasers use either the Littrow or the 
Littman-Metcalf configurations.

A typical Littrow configuration is:

http://www.moglabs.com/uploads/2/4/2/1/24212474/manual_ecd_rev4.20.pdf

Alternatively a cat eye external cavity can be used:

http://www.moglabs.com/uploads/2/4/2/1/24212474/moglabs_cel002_manual_rev108.pdf

To assist with tuning the laser a wavemeter is helpful:

http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/31/004/31004208.pdf

Other variants based on optical wedges or even a simple grating can also be 
used together with a CCD camera or equivalent to achieve an accuracy 
approaching a few pm.

Whilst AR coated laser diodes work best its also possible to use uncoated laser 
diodes.

Such diodes have been successfully used for atomic spectroscopy of rubidium 
vapour by several groups.

Temperature control of the laser diode and cavity are the most critical issues.

One can easily adapt standard optical mounts to make one's own ECDL but 
temperature control is critical for use in a rubidium standard.

Locking the laser to the absorption line of interest relaxes the required long 
term stability of the ECDL itself.  

Bruce

> 
> On 13 April 2017 at 08:55 Bert Kehren via time-nuts  
> wrote:
> 
> Looking back at the dialog I started on Rb’s and the repeated returns to
> that subject allow me to make some comments, observations and
> recommendations.. I stayed on purpose away from participating but learned 
> a lot. It also
> resulted in some off list dialogs with members working on the subject off
> list.
> Rick’s discussion on why to use two frequencies was for me an eye opener
> and gives me clear directions on how to proceed on frequency generation. 
> The
> single frequency project is dumped. Corby’s work on filters again
> influences our future steps. Using a laser diode and its challenges again 
> an eye
> opener and a challenge. We have time nuts that have working systems.
> Let’s be honest, we have members with super knowledge but very few have
> the appetite to do something with it in the form of hardware. Here is my
> proposal that is based on walk before run.
> FRK and M100 are next to the HP 5065A the most promising Rb’s in what we
> like to do. They are easy to work on specially when you are 75/78 and in 
> my
> case have a macular hole.
> Optical Filter. Corby actually did insert a filter in a M100 did however
> not notice an improvement. When we discussed it come to find out he forgot
> to change the time constant so the cell did not control the performance.
> This was years ago and like many of us has his hands full with projects. 
> He
> decided to pass his M100/FRK to an other time nut and focus on HP and 
> Maser.
> We all benefit from these efforts.
> Back to filter we have dissected a FRK and a M100 and are convinced that
> there is a room for a filter, in case of the FRK, very easy. Corby used a
> M100, in my opinion more of a challenge. Will not try it. After 
> discussions
> with Corby I now understand that the filter does not filter out a 
> particular
> wavelength but most the noise that Rb lamps produce as seen on optical
> spectrum analyzers. It improves signal noise ratio after all that is what 
> is
> all about. Once we have completed our current projects we may do so.
> We are also considering to review the frequency generation using Rick’s
> postings as guidance. All this needs measuring capabilities which is what 
> we
> are working on. I am fortunate to have access to Corby’s Maser but Juerg
> does not have that. We are working on a solution.
> There are many FRK/M100’s out there some with low output lamps that would
> be a natural for a Laser Diode replacement. The mechanical makeup begs for
> a Laser solution. The two units have a cell in size only second to HP5065A
> Going to laser would also allow to reduce cell temperature again
> contributing to an improved signal noise ratio,
> This is way off our expertise but it would be nice if some one would take
> the ball and run with it. I am convinced from off list conversations that
> $1000 is a reasonable goal.
> There is no guarantee that we will do the filter depending what our
> results will be on our present work so again maybe some one would carry 
> that
> ball.
> Both can be a first step for future work. WALK
> Bert Kehren
> 
> In a message dated 4/11/2017 12:02:09 P.M. Eastern Daylight Time,
> att...@kinali.ch writes:
> 
> On Tue, 11 Apr 2017 07:31:01 +
> Andre  wrote:
> 
> > > 
> > Has anyone else either built an atomic clock around a bare Rb lamp
> > module "core" or attempted
> > 
> > to make a hydrogen maser?
> > 
> > > 
> Building my own Rb vapor cell standard or H-maser is on 

Re: [time-nuts] TAPR TICC boxed

[Bruce Griffiths]

The gold standard is a random pulse source.
Using something like a SPAD as the source of random pulses is popular as the 
average rate can be easily adjusted by changing the light level. It also avoids 
using radioactive sources.

Bruce
> On 03 April 2017 at 15:05 Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote:
> 
> 
> For even more fun you could try to detect the PTFE phase change  at around 
> 20C using a cable with PTFE dielectric.
> 
> A pulse source with somewhat more pulse to pulse jitter may be more useful in 
> that averaging will occur over a wider range of fine interpolator codes.
> 
> Bruce
> 
> > 
> > On 03 April 2017 at 05:34 Mark Sims <hol...@hotmail.com> wrote:
> > 
> > I implemented the channel offset compensation feature specifically to 
> > make measuring cable delays more accurate. I wanted to measure my TDR 
> > calibration cable and another very precision delay line. I used Heather to 
> > null out the channel/connector delays and then replaced one of the "T" 
> > cables with the TDR cable.
> > 
> > My test setup / TICC was coming up with a -306 ps channel offset error. 
> > The test signal was the 1PPS output of a FTS4060 cesium. Connecting / 
> > reconnecting one of the test setup cables and re-doing the offset test (I 
> > was averaging for 1800 seconds) could produce compensation values that 
> > varied from -300 ps to -325 ps. Just de-doing the offset test without 
> > messing with the cables produced values around -300 to -310 ps.
> > 
> > BNC connectors aren't the best for precision timing. I need to re-run 
> > the test with SMA cables / T adapter and the precision HP connector torque 
> > wrench and see what that looks like. It would also be fun to lay a coax 
> > outdoors and see how the delay changes over a day as it heats/cools.
> > 
> > 
> > 
> > > > 
> > > Some “cables” have very long delay numbers.
> > > 
> > > ___
> > > 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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Re: [time-nuts] TAPR TICC boxed (input protection)

[Bruce Griffiths]

A protection diode needs to also have a fast turn on with little or no 
overshoot of the forward voltage. 

Reverse recovery time can be an issue if one is relying on the clamp for 
protection against a periodic overload such as when an input is overdriven by a 
sinewave input and one wishes to make useful measurements whilst this occurs.

The internal protection diodes of HCMOS devices can severely degrade the device 
propagation delay jitter when they conduct.

Bruce
> On 05 April 2017 at 06:05 David  wrote:
> 
> 
> Low current measurements take a lot of time on the automatic test
> equipment and time in this case is measured in seconds.  The same
> applies to low frequency noise.
> 
> For an example, take a look at the National (now TI) LMC6001 and
> LMC6081:
> 
> https://goo.gl/LCY2vR
> 
> Unlike National, TI does not care about input bias current in their
> selection guides so you will have to look that up in the datasheets:
> 
> http://www.ti.com/product/lmc6001
> http://www.ti.com/product/lmc6081
> 
> The difference in the parts is that the LMC6001 is tested for an Ib of
> 25fA and below and this is reflected in the price which is $5.76
> instead of the $0.83 of the LMC6081.
> 
> Right about the time that the LMC6001 was released, Robert Pease wrote
> some articles talking about the bias current testing and the
> economics.
> 
> The same thing applies to all of those small signal transistors with
> 25, 50, and 100nA leakage specifications.  Those numbers are simply
> good enough for typical applications and what the tester can handle in
> the time allotted and have nothing to do with the actual transistor
> performance.
> 
> So collector-base junctions make good low leakage high voltage diodes
> although they are slow which does not normally matter for an input
> protection circuit and may even be preferable.  Emitter-base junctions
> make good low leakage fast diodes but with low breakdown voltages.
> 
> The cheapest guaranteed low leakage diode is probably some variety of
> 4117/4118/4119 n-channel JFET.
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Re: [time-nuts] TAPR TICC boxed

[Bruce Griffiths]

http://www.spacetechexpo.eu/assets/files/2015/Recent-Developments-in-Phase-Stable-Cables.pdf

is a more readily accessible source of data on coax cable delay tempco et.

Bruce

> 
> On 04 April 2017 at 00:13 Bruce Griffiths <bruce.griffi...@xtra.co.nz> 
> wrote:
> 
> Copper jacketed low density PTFE insulated coax cables typically exhibit 
> a net phase change of over 1000ppm during the PTFE phase transition. See 
> figure 2 p14 of the Cables and connectors supplement to March 2017 microwave 
> journal. Solid PTFE insulated cables exhibit an even greater (2 -3x) phase 
> change. to achieve a phase shift tempco of 10ppm/C either hermetically selaed 
> silicon dioxide powder insulated coax or "phase tracking" semirigid or better 
> phase tracking flexible coax is required.
> 
> Bruce
> 
> > > 
> > On 03 April 2017 at 21:22 Attila Kinali <att...@kinali.ch> wrote:
> > 
> > On Mon, 3 Apr 2017 15:05:55 +1200 (NZST)
> > Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote:
> > 
> > > > > 
> > > > > > > 
> > > > For even more fun you could try to detect the PTFE 
> > > > phase change at around 20C using a cable with PTFE dielectric.
> > > > 
> > > > This will require several 100 meters of cable to be 
> > > > measureable with
> > > > the TICC. Modern cables are all <500ppm/K, good cables 
> > > > <10ppm/K, phase
> > > > stable cables reach even <1ppm/K. Measuring a change of 
> > > > 10ppm with
> > > > a resolution of 60ps means that the delay has to be in 
> > > > the order of 6µs,
> > > > which is close to 1000m of cable. Even if dithering 
> > > > gives another facor
> > > > of 10, this still means 100m of cable.
> > > > 
> > > > > > > 
> > > > > 
> > For this level of comparison I would suggest to use a sinusoidal 
> > signal,
> > instead of a pulse, and do phase comparison, which gives a 
> > resolution
> > in the order of 1ps with very little effort, thus reducing the 
> > required
> > cable length to 10-20 meters.
> > 
> > Attila Kinali
> > 
> > [1] "Temperature Stability of Coaxial Cables", Czuba and Sikora, 
> > 2011
> > http://przyrbwn.icm.edu.pl/APP/PDF/119/a119z4p17.pdf
> > 
> > --
> > 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
> > 
> > ___
> > 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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> > and follow the instructions there.
> > 
> > > 
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Re: [time-nuts] TAPR TICC boxed

[Bruce Griffiths]

Copper jacketed low density PTFE insulated coax cables typically exhibit a net 
phase change of over 1000ppm during the PTFE phase transition. See figure 2 p14 
of the Cables and connectors supplement to March 2017 microwave journal. Solid 
PTFE insulated cables exhibit an even greater (2 -3x) phase change. to achieve 
a phase shift tempco of 10ppm/C either hermetically selaed silicon dioxide 
powder insulated coax or "phase tracking" semirigid or better phase tracking 
flexible coax is required. 

Bruce

> 
> On 03 April 2017 at 21:22 Attila Kinali <att...@kinali.ch> wrote:
> 
> On Mon, 3 Apr 2017 15:05:55 +1200 (NZST)
> Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote:
> 
> > > 
> > For even more fun you could try to detect the PTFE phase change at 
> > around 20C using a cable with PTFE dielectric.
> > 
> > > 
> This will require several 100 meters of cable to be measureable with
> the TICC. Modern cables are all <500ppm/K, good cables <10ppm/K, phase
> stable cables reach even <1ppm/K. Measuring a change of 10ppm with
> a resolution of 60ps means that the delay has to be in the order of 6µs,
> which is close to 1000m of cable. Even if dithering gives another facor
> of 10, this still means 100m of cable.
> 
> For this level of comparison I would suggest to use a sinusoidal signal,
> instead of a pulse, and do phase comparison, which gives a resolution
> in the order of 1ps with very little effort, thus reducing the required
> cable length to 10-20 meters.
> 
> Attila Kinali
> 
> [1] "Temperature Stability of Coaxial Cables", Czuba and Sikora, 2011
> http://przyrbwn.icm.edu.pl/APP/PDF/119/a119z4p17.pdf
> 
> --
> 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] TAPR TICC boxed

[Bruce Griffiths]

For even more fun you could try to detect the PTFE phase change  at around 20C 
using a cable with PTFE dielectric.

A pulse source with somewhat more pulse to pulse jitter may be more useful in 
that averaging will occur over a wider range of fine interpolator codes.

Bruce

> 
> On 03 April 2017 at 05:34 Mark Sims  wrote:
> 
> I implemented the channel offset compensation feature specifically to 
> make measuring cable delays more accurate. I wanted to measure my TDR 
> calibration cable and another very precision delay line. I used Heather to 
> null out the channel/connector delays and then replaced one of the "T" cables 
> with the TDR cable.
> 
> My test setup / TICC was coming up with a -306 ps channel offset error. 
> The test signal was the 1PPS output of a FTS4060 cesium. Connecting / 
> reconnecting one of the test setup cables and re-doing the offset test (I was 
> averaging for 1800 seconds) could produce compensation values that varied 
> from -300 ps to -325 ps. Just de-doing the offset test without messing with 
> the cables produced values around -300 to -310 ps.
> 
> BNC connectors aren't the best for precision timing. I need to re-run the 
> test with SMA cables / T adapter and the precision HP connector torque wrench 
> and see what that looks like. It would also be fun to lay a coax outdoors and 
> see how the delay changes over a day as it heats/cools.
> 
> 
> 
> > > 
> > Some “cables” have very long delay numbers.
> > 
> > ___
> > 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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Re: [time-nuts] TAPR TICC boxed

[Bruce Griffiths]

Its usually not possible to uniquely assign individual channel delays in this 
way, however swapping cables allows the cable delay mismatch to be eliminated 
from the measurement of the differential delay between channels.
Eliminating the effect of cable delay mismatch can be useful when adjusting 
narrowband quadrature splitters ect.

Bruce
> On 02 April 2017 at 13:38 Mark Sims  wrote:
> 
> 
> The new TICC support in Lady Heather has an "autotune" function that can null 
> out the cable and channel delays.  You connect a signal (like 1PPS) to both 
> channels through matched cables (like via a T adapter) and it averages the 
> difference and sets the "FUDGE" factor for one of the channels to null out 
> the net offset.  It doesn't null each channel individually.You might be 
> able to swap the cables and work out how to allocate the offset to each 
> channel.My unit has a channel offset of -305 ps (part of which could be 
> due to mismatches in the "T" cables / connectors).
> 
> Autotune also calculates the FIXED TIME2 values if you want to play with that 
> feature which can allegedly reduce the device noise by sqrt(2).  I'm not sure 
> how well that works since the TIME2 values do drift over time and I don't 
> know how much of an error in the TIME2 settings affects the device enough to 
> make it perform worse than with the default automatic TIME2 mode.
> 
> -
> 
> >  The whole delay difference thing does get into a “do you care?” sort of 
> > category. The 
> testing process you are doing may well calibrate out (or ignore) an offset of 
> this nature. 
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Re: [time-nuts] TAPR TICC boxed

[Bruce Griffiths]

The common mode propagation delay dispersion is also likely to be significant 
unless one uses an SiGe ECL/CML comparator.

Calibrating this or actually the differential dispersion between channels is an 
interesting but not insoluble issue.

Bruce 

> 
> On 01 April 2017 at 18:49 Scott Stobbe <scott.j.sto...@gmail.com> wrote:
> 
> Also interesting the LTC6752 is rail-rail input. Any rail-rail input opamp
> I've used ends up with an ugly bump in input offset voltage transitioning
> from the nmos or npn diff pair to the pmos or nmos. I'm not sure how good
> or bad a rail-rail comparator may behave when common-mode biased in that
> region.
> 
>     On Fri, Mar 31, 2017 at 11:22 PM Bruce Griffiths 
> <bruce.griffi...@xtra.co.nz>
> wrote:
> 
> > > 
> > Attempting sub nanosecond timing with an actual 1Mohm source is an
> > exercise in futility. There are very few cases where one would want 
> > to
> > attempt precision timing measurements with such a high impedance 
> > source.
> > The 1M pulldown on the TICC input is merely intended to maintain a 
> > valid
> > logic input should the user leave that input disconnected. In 
> > actual use
> > with PPS signals the source impedance is in most cases a few tens 
> > of ohms.
> > If one wishes to have a 1Mohm input impedance for use with AC 
> > coupled
> > signals then a low noise FET input buffer preceding the comparator 
> > is
> > required.
> > 
> > Protection diodes in this application not only need to have low 
> > leakage,
> > they also need to turn on and off fast enough to be useful.
> > 
> > The propagation delay dispersion (both vs common mode and vs 
> > overdrive)
> > also need to be considered along with the comparator jitter.
> > 
> > Bruce
> > 
> > and overdrive (both vs overdrive and vs input common modeOn 01 
> > April 2017
> > at 15:34 Scott Stobbe <scott.j.sto...@gmail.com> wrote:
> > 
> > Fwiw, for a precision comparator you'll probably want a bipolar 
> > front end
> > for a lower flicker corner and better offset stability over cmos. 
> > For
> > high-speeds the diffpair is going to be biased fairly rich for 
> > bandwidth.
> > So you will more than likey have input bias currents of 100's of nA 
> > to uA
> > on your comparator. Which is not great with a 1 megohm source.
> > 
> > On Fri, Mar 31, 2017 at 9:08 PM Charles Steinmetz 
> > <csteinm...@yandex.com>
> > wrote:
> > 
> > Mark wrote:
> > 
> > I thought about using the clamp diodes as protection but was a bit
> > worried about power supply noise leaking through the diodes and 
> > adding some
> > jitter to the input signals...
> > 
> > It is a definite worry even with a low-noise, 50 ohm input, and a
> > potential disaster with a 1Mohm input. Common signal diodes (1N4148,
> > 1N914, 1N916, 1N4448, etc.) are specified for 5-10nA of reverse 
> > current.
> > Even a low-leakage signal diode (e.g., 1N3595) typically has several
> > hundred pA of leakage. Note that the concern isn't just power supply
> > noise -- the leakage current itself is quite noisy.
> > 
> > For low-picoamp diodes at a decent price, I use either (1) the B-C 
> > diode
> > of a small-signal BJT, or (2) the gate diode of a small-geometry 
> > JFET.
> > A 2N5550 makes a good high-voltage, low-leakage diode with leakage
> > current of ~30pA. Small signal HF transistors like the MPSH10 and
> > 2N5179 (and their SMD and PN variants) are good for ~5pA, while the 
> > gate
> > diode of a PN4417A JFET (or SMD variant) has reverse leakage 
> > current of
> > ~1pA (achieving this in practice requires a very clean board and 
> > good
> > layout).
> > 
> > I posted some actual leakage test results to Didier's site, which 
> > can be
> > downloaded at
> > <
> > 
> > 
> > http://www.ko4bb.com/getsimple/index.php?id=download=03_App_Notes_-_Proceedings/Reverse_leakage_of_diode-connected_BJTs_and_FETs_measurement_results.pdf
> >  
> > http://www.ko4bb.com/getsimple/index.php?id=download=03_App_Notes_-_Proceedings/Reverse_leakage_of_diode-connected_BJTs_and_FETs_measurement_results.pdf
&g

Re: [time-nuts] TAPR TICC boxed

[Bruce Griffiths]

Attempting sub nanosecond timing with an actual 1Mohm source is an exercise in 
futility. There are very few cases where one would want to attempt precision 
timing measurements with such a high impedance source. The 1M pulldown on the 
TICC input is merely intended to maintain a valid logic input should the user 
leave that input disconnected. In actual use with PPS signals the source 
impedance is in most cases a few tens of ohms. If one wishes to have a 1Mohm 
input impedance for use with AC coupled signals then a low noise FET input 
buffer preceding the comparator is required.

Protection diodes in this application not only need to have low leakage,  they 
also need to turn on and off fast enough to be useful.

The propagation delay dispersion (both vs common mode and vs overdrive) also 
need to be considered along with the comparator jitter.


Bruce

> 
>  and overdrive (both vs overdrive and vs input common modeOn 01 April 
> 2017 at 15:34 Scott Stobbe  wrote:
> 
> Fwiw, for a precision comparator you'll probably want a bipolar front end
> for a lower flicker corner and better offset stability over cmos. For
> high-speeds the diffpair is going to be biased fairly rich for bandwidth.
> So you will more than likey have input bias currents of 100's of nA to uA
> on your comparator. Which is not great with a 1 megohm source.
> 
> On Fri, Mar 31, 2017 at 9:08 PM Charles Steinmetz 
> wrote:
> 
> > > 
> > Mark wrote:
> > 
> > > > > 
> > > I thought about using the clamp diodes as protection but was 
> > > a bit
> > > worried about power supply noise leaking through the diodes 
> > > and adding some
> > > jitter to the input signals...
> > > 
> > > > > 
> > It is a definite worry even with a low-noise, 50 ohm input, and a
> > potential disaster with a 1Mohm input. Common signal diodes (1N4148,
> > 1N914, 1N916, 1N4448, etc.) are specified for 5-10nA of reverse 
> > current.
> > Even a low-leakage signal diode (e.g., 1N3595) typically has several
> > hundred pA of leakage. Note that the concern isn't just power supply
> > noise -- the leakage current itself is quite noisy.
> > 
> > For low-picoamp diodes at a decent price, I use either (1) the B-C 
> > diode
> > of a small-signal BJT, or (2) the gate diode of a small-geometry 
> > JFET.
> > A 2N5550 makes a good high-voltage, low-leakage diode with leakage
> > current of ~30pA. Small signal HF transistors like the MPSH10 and
> > 2N5179 (and their SMD and PN variants) are good for ~5pA, while the 
> > gate
> > diode of a PN4417A JFET (or SMD variant) has reverse leakage 
> > current of
> > ~1pA (achieving this in practice requires a very clean board and 
> > good
> > layout).
> > 
> > I posted some actual leakage test results to Didier's site, which 
> > can be
> > downloaded at
> > <
> > 
> > http://www.ko4bb.com/getsimple/index.php?id=download=03_App_Notes_-_Proceedings/Reverse_leakage_of_diode-connected_BJTs_and_FETs_measurement_results.pdf
> >  
> > http://www.ko4bb.com/getsimple/index.php?id=download=03_App_Notes_-_Proceedings/Reverse_leakage_of_diode-connected_BJTs_and_FETs_measurement_results.pdf
> > 
> > > > > 
> > > .
> > > This document shows the connections I used to obtain the data.
> > > 
> > > The TICC doesn't have the resolution for it to matter or 
> > > justify a
> > > HP5370 or better quality front end. I'll probably go with a 
> > > fast
> > > comparator to implement the variable threshold input.
> > > 
> > > > > 
> > Properly applied, a fast comparator will have lower jitter than the 
> > rest
> > of the errors, and is an excellent choice. Bruce suggested the 
> > LTC6752,
> > which is a great part if you need high toggle speeds (100s of MHz) 
> > or
> > ultra-fast edges. But you don't need high toggle rates and may not 
> > need
> > ultra-fast edges. Repeatability and stability are more important 
> > than
> > raw speed in this application. The LT1719, LT1720, or TLV3501 may 
> > work
> > just as well for your purpose, and they are significantly less 
> > fussy to
> > apply.
> > 
> > Note that the LTC6752 series is an improved replacement for the 
> > ADCMP60x
> > series, which itself is an improved replacement for the MAX999. Of
> > these three, the LTC6752 is the clear winner in my tests. If you do
> > choose it (or similar), make sure you look at the transitions with
> > something that will honestly show you any chatter at frequencies up 
> > to
> > at least several GHz. It only takes a little transition chatter to
> > knock the potential timing 

Re: [time-nuts] TAPR TICC boxed

[Bruce Griffiths]

A single or dual supply CMOS output comparator should suffice together with 
some diode clamps.

Since the TICC only resolves a few tens of picosec the choice of comparator etc 
isnt critical.

LTC6752 (~$US2) or similar perhaps? 

A single supply comparator should suffice unless you want to measure NECL or 
similar signals.

Bruce

> 
> On 31 March 2017 at 09:15 Mark Sims  wrote:
> 
> What did you do for input protection?
> 
> I want to build an input system for the TICC that incorporates some input 
> protection, switchable terminator, possibly settable threshold and edge 
> selects, and a switchable PICDIV divider like the TADD-2 Mini. That would 
> allow inputs of <1 .. 100 (or maybe up to 1000) PPS and 1/5/10/15 MHz inputs.
> 
> The main problem I'm having is coming up with an input squarer circuit 
> that is simple and cheap but can handle basically DC-15 MHz. Anybody got any 
> ideas?
> 
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Re: [time-nuts] Single ended or differential input to TDC chip

[Bruce Griffiths]

Attila

Differential inputs, either LVDS or PECL compatible, together with a fast 
single supply comparator for the CMOS to PECL to LVDS/differential PECL would 
be the conservative approach. Ultra fast comparators with aaa delay belo 
2ns are readilyy available.

Alternatively a CMOS to LVDS converter like:

http://www.analog.com/media/en/technical-documentation/data-sheets/ADN4661.pdf

could be used.

There are commercial TDCs that claim similar resolution that use CMOS inputs.

One could provide both CMOS and differential inputs so that if the CMOS inputs 
prove problematic one could just use the differential inputs.

Bruce

> 
> On 28 March 2017 at 05:05 Attila Kinali  wrote:
> 
> Hi,
> 
> We (the group I am with and a group at TU Vienna) are currently designing
> an ASIC (digital 65nm process) that will contain a TDC part. The TDC will
> be a simple delay line TDC design using differential buffers, which we
> expect to give us something in the order of 20ps of resolution (hopefully
> better, but we will not know until we get post-layout simulation data).
> We are loosely following the design CERN came up with for their new TDC 
> chip[1].
> 
> Now, the TDC expects a differential input, but the system gets 
> single-ended
> pulses as input (50R coax input, level likely to be CMOS 3.3V, but level 
> not
> fixed yet, ie can be freely choosen). I can either convert these 
> single-ended
> signals into differential off-chip or on-chip. Unfortunately, I lack 
> knowledge
> and experience to judge either approach. The issues I see are:
> 
> * Single-ended input in a chip might lead to shifting ground potential
>   on the chip and thus to measurment jitter.
> * There are different architectures to preform the single-ended to 
> differential
>   conversion on-chip, but I have no clue which one to choose or even 
> how
>   to judge them without extensive simulations for which we do not 
> have the
>   time, know-how and probably not even the tools.
> * Conversion to differential off-chip means another component off-chip
>   that might introduce additional delay uncertainty (our application 
> is
>   very sensitive to that) and an unknown amount of jitter.
> 
> My google foo has been so far not strong enough to find answers to these
> questions.
> 
> I would appreciate if someone could give me some hints in this matter
> or tell me where I could find appropriate literature and maybe even
> tell me whether I am missing anything.
> 
> Thanks in advance
> 
> Attila Kinali
> 
> [1] 
> https://indico.cern.ch/event/228972/contributions/1539621/attachments/378552/526492/TDC_TWEPP_2013.pdf
> --
> 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] Sub 20 ps time detection

[Bruce Griffiths]

Mohammad

The LTC6957-4 is inputs are intended to be AC coupled.

With  AC coupling a variable rate pulse will experience varying switching 
thresholds.

A constant fraction discriminator minimises timing walk when the pulse 
amplitude varies whilst the ristetime remains constant. 

If the pulse risetime also varies a more complex amplitude and risetime 
compensated discriminator is necessary to minimise timing walk.

For minimum timing jitter there will be an optimum zero crossing detector 
bandwidth.

Bruce

> 
> On 26 March 2017 at 05:32 Mohammad-Hadi Sohrabi  
> wrote:
> 
> Hello,
> I have been following the posts here for a while and learned alot. I
> thought I could get some help as well.
> I need to detect less than 20 ps between two incoming pulses from a
> detector. pulses are 5ns wide and the rise time and fall time is around 
> 2ns
> each.
> I am planning to use a constant fraction discriminator, simply a fast
> comparator with less than 500 MHz bandwidth for zero crossing detection 
> and
> providing a very sharp edge. Then this can be fed into a TDC such as GPX2
> or anything of this sort. I think these can be fairly easily implemented 
> on
> FR4.
> Recently I stumbled upon LTC6957-4 logic converter from another 
> discussion.
> Can anyone guide me if this can be used for producing a sharp edge from a
> pulse that I mentioned? Datasheet suggests 0.5 ns rise time is possible 
> but
> I think this is for single tone sine wave and not a short pulse.
> 
> Bests,
> Mohammad
> 
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Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Bruce Griffiths]

An Early (~1980?) NS/FEI paper on optically pumped cesium beam tubes:

http://tf.nist.gov/general/pdf/732.pdf

Bruce

> 
> On 18 March 2017 at 17:28 "Richard (Rick) Karlquist" 
>  wrote:
> 
> Len Cutler was all set to build an optically
> pumped Cs beam 20 years ago. Even then, he could get the lasers.
> He was only missing one thing: money. HP management never
> agreed to fund it. The paper conspicuously omits any spec
> on absolute accuracy. The optical pumping does nothing to
> improve that AFAIK. It still depends on phase error in the CBT.
> The 5071 has a guaranteed accuracy of 10^-12, and is typically
> several times better than that.
> 
> It is surprising that none of the various makers of the 5071A
> ever made an optical version. I wonder what they are thinking
> now that someone else has done it.
> 
> Rick
> 
> On 3/17/2017 7:48 PM, cdel...@juno.com wrote:
> 
> > > 
> > Looks like Oscilloquartz is getting ready to sell this commercially!
> > Will give the 5071A a run for the money!
> > Reliability should go way up as:
> > -No electron multiplier
> > -No ionizer filament
> > -No state selection magnets
> > Also all the fiddley bits (laser diodes and photodetectors) are 
> > external
> > to the tube and can be easily updated as needed.
> > 
> > 
> > https://www.slideshare.net/ADVAOpticalNetworking/performance-results-of-a
> > n-optically-pumped-cesium-beam-clock
> > 
> > Cheers,
> > 
> > Corby
> > 
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> > > 
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Re: [time-nuts] TDC-GPX2 TDC chip

[Bruce Griffiths]

The apparent drift will be determined largely by that of the reference 
oscillator due to the embedded continuous interpolator calibration. Placing it 
in an oven will probably degrade the resolution due to the bin size tempco.

All time interval instruments have an offset between channels, This is easily 
measured and corrected for. 

The performance as stated in the datasheet appears comparable if not better 
than a typical 5370A/B when one takes the various sources of nonlinearity and 
crosstalk in a 5370A/B into account. It certainly consumes less power even 
after the power consumption of a good ocxo is added.  Its also somewhat cheaper.

However a comprehensive evaluation of its performance beyond that given in the 
datasheet is required.

A comprehensive test of the performance of a n actual 5370A/B would also be 
useful.

Bruce

> 
> On 16 March 2017 at 15:54 Bill Byrom  wrote:
> 
> "the large print giveth and the small print taketh away"
> 
> (Quoted from this great description of modern life:
> 
> http://www.tomwaits.com/songs/song/322/Step_Right_Up/ )
> 
> I'm not trying to be too critical, but look carefully at the datasheet
> for that part:
> http://ams.com/eng/content/download/951531/2270299/381482
> 
> The "accuracy" can in no way be described as 10 ps. In high
> resolution mode:
> 
> * Single shot RMS time resolution: 10 ps typical, 15 ps maximum
> 
> * Integral non-linearity: 20 ps max
> 
> * Differential non-linearity: 5 ps typ
> 
> * Channel to channel isolation: 20 ps typ, 100 ps max
> 
> * Offset error: 200 ps typ
> 
> * Offset error drift vs temperature: 1.5 ps typ, 3 ps max / K
> 
> * FWHM (full width half maximum) histogram: 20-25 ps
> 
> So if the temperature changes 6 F (3.3 C), the measurement may drift by
> 10 ps. The single shot absolute uncertainty due to jitter (see the
> histogram) could easily be +/- 25 ps. There is no mention of long-term
> drift, since that isn't a typical use of this part. It would be
> interesting to put one in a simple oven and see how it drifts over a
> 
> few months.
> --
> 
> Bill Byrom N5BB
> 
> - Original message -
> 
> From: Christopher Hoover 
> 
> To: Discussion of precise time and frequency measurement 
> 
> Subject: [time-nuts] TDC-GPX2 TDC chip
> 
> Date: Wed, 15 Mar 2017 15:28:20 -0700
> 
> 
> http://ams.com/eng/Products/Precision-Time-Measurement/Time-to-Digital-Converters/TDC-GPX2
> 
> Claims to have single-shot accuracy of 10 ps.
> 
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Re: [time-nuts] TDC-GPX2 TDC chip

[Bruce Griffiths]

The datasheet is less than convincing.
The change in resolution/noise with time delay isnt well documented.
Performance may differ when a 1MHz reference clock is used as opposed to the 
10MHz clock they appear to have used for some of the plots on the datasheet.
The customer support person appears to know little useful about tdcs.
Have been debating how to establish the actual performance.

A) use random source(s) to produce data for the fill the buckets histogram test.
For statistically useful results an extremely large number of random events is 
required.
e.g. for a 10MHz reference clock and 10ps bits need around 10,000 hits per bin 
for 1% rms
statistical variation in bin event totals. i.e. about 1E8 total events.
With a 1MHz reference clock need at least 1E9 events.

B) Use a pair of 10MHz oscillators with a small frequency offset between them 
one of which is used as the reference clock whilst the other is divided down to 
produce a suitable event rate. The leading edge of each successive event is 
swept slowly at a uniform rate across the reference clock cycle in steps of say 
10fs or so per event. This requires that the sources have very low spur levels 
at least 120dB below the carrier and preferably more.
The reference 10MHz can be divided down to 5MHz, 2MHz or 1MHZ for testing with 
lower reference clock frequencies.

c) As above but use a single 10MHz source that acts both as reference clock for 
the TDC and as the input source for an extremely low spur offset generator, the 
output of which is divided down to create a suitable event rate.

D) Compare the TDC measurements with those obtained with a significantly lower 
noise TDC.
Still (a few of us at least) working on this. Initial crude and somewhat noisy 
setup suggested better than 10ps rms (limited somewhat by jitter of divider 
chain used to produce trigger signal). A later version achieved around 3ps rms. 
However comprehensive testing is still to be done.

Bruce

> 
> On 16 March 2017 at 11:28 Christopher Hoover  wrote:
> 
> 
> http://ams.com/eng/Products/Precision-Time-Measurement/Time-to-Digital-Converters/TDC-GPX2
> 
> Claims to have single-shot accuracy of 10 ps.
> 
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Re: [time-nuts] Bye-Bye Crystals

[Bruce Griffiths]

Bob

He stated 0.01Hz EFC tuning range was adequate.
Gave no spec as to how close to nominal frequency is required though.

Bruce
> On 16 March 2017 at 10:53 Bob Camp <kb...@n1k.org> wrote:
> 
> 
> Hi
> 
> By most modern definitions, “high stability” starts around 1x10^-12 (1 ppt)  
> at a tau of 1 second to 
> 10 seconds. There are $20 eBay OCXO’s that run at that level.  With a 
> fundamental crystal you 
> aren’t going to get to that point. 
> 
> How much EFC range are you after? 
> 
> How good a CNC setup do you have?
> 
> What kind of temperature test setup do you have? 
> 
> Simply put, the design approach is a “test over temperature / collect data -> 
> optimize” loop. 
> Without good frequency vs temperature data, you are flying totally blind. 
> Even on a production
> design, this is how it’s done. The parts you fiddle are likely to be odd 
> shaped chunks of metal 
> that fit here or there. 
> 
> Bob
> 
> > On Mar 15, 2017, at 3:36 PM, Gilles Clement <clemg...@club-internet.fr> 
> > wrote:
> > 
> > Hi, 
> > I have a bunch of 5.184Mhz crystals. Large metallic tanks: HC33U case
> > Maybe not OCXO grade, but I build a simple oscillator with a 4060 chip
> > placed in a double oven, and reached 10E-9 short term stability up to 10sec 
> > tau.
> > Not bad, so wondering if I can get better with a more advanced design. 
> > Gilles. 
> > 
> > 
> >> Le 15 mars 2017 à 12:45, Bob Camp <kb...@n1k.org> a écrit :
> >> 
> >> Hi
> >> 
> >> Where do you plan on getting an OCXO grade crystal at an odd frequency 
> >> like 
> >> that? Much of the performance of a good OCXO is in the crystal. Doing a 
> >> proper 
> >> design on one is a lot of work. You *might* think that having a design for 
> >> 5.00
> >> MHz would give you a good design for 5.50 MHz. I have empirical 
> >> evidence that
> >> this isn’t the case. Many years later, I’m still utterly amazed that this 
> >> is the way things
> >> work in the crystal business ….( = it’s not just a design issue, it’s also 
> >> a business decision) 
> >> 
> >> More or less the crystal needs to be:
> >> 
> >> 1) Cut specifically to have a turn at a temperature that makes sense for 
> >> your application.
> >> 2) A “large blank” design (for it’s frequency)
> >> 3) In a cold weld package (most of the normal crystals are resistance weld)
> >> 4) Run through a high vacuum / high temperature process
> >> 5) Be plated with gold rather than something like silver or aluminum 
> >> (unless it’s at VHF).
> >> 6) Have a motional capacitance that makes sense for your EFC range ( 
> >> normally = minimize)
> >> 7) Preferably be an SC or modified SC cut. 
> >> 
> >> This is for a high stability part. The list does keep going on for a 
> >> while, but that should 
> >> give you a pretty good idea. 
> >> 
> >> Bob
> >> 
> >>> On Mar 15, 2017, at 3:11 AM, Gilles Clement <clemg...@club-internet.fr> 
> >>> wrote:
> >>> 
> >>> Hi, 
> >>> So what is the « best » design for DIY a high stability OCVXO ? 
> >>> I am looking after one, needed for an exotic frequency : 5184kHZ 
> >>> Thx, 
> >>> Gilles. 
> >>> 
> >>> 
> >>>> Le 14 mars 2017 à 18:02, Richard (Rick) Karlquist 
> >>>> <rich...@karlquist.com> a écrit :
> >>>> 
> >>>> 
> >>>> 
> >>>> On 3/14/2017 4:03 AM, Bruce Griffiths wrote:
> >>>> 
> >>>>> 
> >>>>> Looking at oscillator circuits like the HP10811A will give some idea of 
> >>>>> some of the additional complexity required for a overtone operation. 
> >>>>> Dissecting a few ocxos may also be helpful. Some start with a 10MHz 
> >>>>> crystal and a Colpitts sustaining stage and use a 74HC74 or similar to  
> >>>>> divide the 10Mhz by 2 and drive the output pin. Even when a sinewave 
> >>>>> output is required often a CMOS inverter drives the output pin via an 
> >>>>> LC filter.
> >>>>> 
> >>>>> Bruce
> >>>>> 
> >>>> 
> >>>> I don't agree here.  The 10811 is not a good tutorial for general 
> >>>> oscillator design.  Because it is SC cut, it has a complicated
> >>>> mode suppression network ac

Re: [time-nuts] Bye-Bye Crystals

[Bruce Griffiths]

Most likely AT cut fundamental (although there are other possibilities.) 
designed for operation around room temperature.

Do you have the manufacturer's specs for these?

What is the change in frequency between room temperature and oven temperature?

What is the operating temperature of the inner oven?

Bruce

> 
> On 16 March 2017 at 08:36 Gilles Clement <clemg...@club-internet.fr> 
> wrote:
> 
> Hi,
> I have a bunch of 5.184Mhz crystals. Large metallic tanks: HC33U case
> Maybe not OCXO grade, but I build a simple oscillator with a 4060 chip
> placed in a double oven, and reached 10E-9 short term stability up to 
> 10sec tau.
> Not bad, so wondering if I can get better with a more advanced design.
> Gilles.
> 
> > > 
> > Le 15 mars 2017 à 12:45, Bob Camp <kb...@n1k.org> a écrit :
> > 
> > Hi
> > 
> > Where do you plan on getting an OCXO grade crystal at an odd 
> > frequency like
> > that? Much of the performance of a good OCXO is in the crystal. 
> > Doing a proper
> > design on one is a lot of work. You *might* think that having a 
> > design for 5.00
> > MHz would give you a good design for 5.50 MHz. I have empirical 
> > evidence that
> > this isn’t the case. Many years later, I’m still utterly amazed 
> > that this is the way things
> > work in the crystal business ….( = it’s not just a design issue, 
> > it’s also a business decision)
> > 
> > More or less the crystal needs to be:
> > 
> > 1) Cut specifically to have a turn at a temperature that makes 
> > sense for your application.
> > 2) A “large blank” design (for it’s frequency)
> > 3) In a cold weld package (most of the normal crystals are 
> > resistance weld)
> > 4) Run through a high vacuum / high temperature process
> > 5) Be plated with gold rather than something like silver or 
> > aluminum (unless it’s at VHF).
> > 6) Have a motional capacitance that makes sense for your EFC range 
> > ( normally = minimize)
> > 7) Preferably be an SC or modified SC cut.
> > 
> > This is for a high stability part. The list does keep going on for 
> > a while, but that should
> > give you a pretty good idea.
> > 
> > Bob
> > 
> > > > > 
> > > On Mar 15, 2017, at 3:11 AM, Gilles Clement 
> > > <clemg...@club-internet.fr> wrote:
> > > 
> > > Hi,
> > > So what is the « best » design for DIY a high stability OCVXO 
> > > ?
> > > I am looking after one, needed for an exotic frequency : 
> > > 5184kHZ
> > > Thx,
> > > Gilles.
> > > 
> > > > > > > 
> > > > Le 14 mars 2017 à 18:02, Richard (Rick) Karlquist 
> > > > <rich...@karlquist.com> a écrit :
> > > > 
> > > > On 3/14/2017 4:03 AM, Bruce Griffiths wrote:
> > > > 
> > > > > > > > > 
> > > > > Looking at oscillator circuits like the HP10811A 
> > > > > will give some idea of some of the additional complexity required for 
> > > > > a overtone operation. Dissecting a few ocxos may also be helpful. 
> > > > > Some start with a 10MHz crystal and a Colpitts sustaining stage and 
> > > > > use a 74HC74 or similar to divide the 10Mhz by 2 and drive the output 
> > > > > pin. Even when a sinewave output is required often a CMOS inverter 
> > > > > drives the output pin via an LC filter.
> > > > > 
> > > > > Bruce
> > > > > 
> > > > > > > > > 
> > > > I don't agree here. The 10811 is not a good tutorial 
> > > > for general oscillator design. Because it is SC cut, it has a 
> > > > complicated
> > > > mode suppression network across the base emitter 
> > > > junction to
> > > > suppress mode B as well as the fundamental.
> > > > 
> > > > The E1983A oscillator uses the same crystal (in a low 
> > > > profile
> > > > package). You can read my paper about it and see that I
> > > > used a very

Re: [time-nuts] Bye-Bye Crystals

[Bruce Griffiths]

Gilles

What is the required tuning range for the OCVXO?

Bruce

> 
> On 15 March 2017 at 20:11 Gilles Clement <clemg...@club-internet.fr> 
> wrote:
> 
> Hi,
> So what is the « best » design for DIY a high stability OCVXO ?
> I am looking after one, needed for an exotic frequency : 5184kHZ
> Thx,
> Gilles.
> 
> > > 
> > Le 14 mars 2017 à 18:02, Richard (Rick) Karlquist 
> > <rich...@karlquist.com> a écrit :
> > 
> > On 3/14/2017 4:03 AM, Bruce Griffiths wrote:
> > 
> > > > > 
> > > Looking at oscillator circuits like the HP10811A will give 
> > > some idea of some of the additional complexity required for a overtone 
> > > operation. Dissecting a few ocxos may also be helpful. Some start with a 
> > > 10MHz crystal and a Colpitts sustaining stage and use a 74HC74 or similar 
> > > to divide the 10Mhz by 2 and drive the output pin. Even when a sinewave 
> > > output is required often a CMOS inverter drives the output pin via an LC 
> > > filter.
> > > 
> > > Bruce
> > > 
> > > > > 
> > I don't agree here. The 10811 is not a good tutorial for general 
> > oscillator design. Because it is SC cut, it has a complicated
> > mode suppression network across the base emitter junction to
> > suppress mode B as well as the fundamental.
> > 
> > The E1983A oscillator uses the same crystal (in a low profile
> > package). You can read my paper about it and see that I
> > used a very simple bridged tee oscillator circuit. That is
> > all you need to select the right overtone and mode.
> > 
> > This is the same circuit that I used at Zeta Labs 40 years
> > ago to design hundreds of custom VCXO's, up to the 9th
> > overtone. It simply worked every time, unlike various other
> > designs that were in use at Zeta.
> > 
> > Around 1985, I got a consulting gig at Equatorial Communications
> > to redesign their 5th overtone VCXO. Only about half of the
> > crystals would work in their circuit. They had thousands
> > of "reject" crystals. I just used my old Zeta circuit and
> > all the crystals started working again.
> > 
> > Equatorial owned the 10 meter dish that you used to see on
> > your right going south on 237 just before passing over
> > Central Expressway in Mountain View.
> > 
> > Rick N6RK
> > 
> > ___
> > 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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Re: [time-nuts] Bye-Bye Crystals

[Bruce Griffiths]

Rick

Yes, the 10811A is a good example of the sort of kludge that is required when 
one tries to adapt the Colpitts XO to work with an overtone crystal.
However, apart from that, the design is still a lot better than those in most 
of the ham publications (eg. clamp diodes on JFET gates to limit the amplitude 
etc).

The E1938A bridged T oscillator along with some of Driscoll's many XO circuits 
are simpler and more effective.  

Bruce

> On 15 March 2017 at 06:02 "Richard (Rick) Karlquist" <rich...@karlquist.com> 
> wrote:
> 
> 
> 
> 
> On 3/14/2017 4:03 AM, Bruce Griffiths wrote:
> 
> >
> > Looking at oscillator circuits like the HP10811A will give some idea of 
> > some of the additional complexity required for a overtone operation. 
> > Dissecting a few ocxos may also be helpful. Some start with a 10MHz crystal 
> > and a Colpitts sustaining stage and use a 74HC74 or similar to  divide the 
> > 10Mhz by 2 and drive the output pin. Even when a sinewave output is 
> > required often a CMOS inverter drives the output pin via an LC filter.
> >
> > Bruce
> >
> 
> I don't agree here.  The 10811 is not a good tutorial for general 
> oscillator design.  Because it is SC cut, it has a complicated
> mode suppression network across the base emitter junction to
> suppress mode B as well as the fundamental.
> 
> The E1983A oscillator uses the same crystal (in a low profile
> package).  You can read my paper about it and see that I
> used a very simple bridged tee oscillator circuit.  That is
> all you need to select the right overtone and mode.
> 
> This is the same circuit that I used at Zeta Labs 40 years
> ago to design hundreds of custom VCXO's, up to the 9th
> overtone.  It simply worked every time, unlike various other
> designs that were in use at Zeta.
> 
> Around 1985, I got a consulting gig at Equatorial Communications
> to redesign their 5th overtone VCXO.  Only about half of the
> crystals would work in their circuit.  They had thousands
> of "reject" crystals.  I just used my old Zeta circuit and
> all the crystals started working again.
> 
> Equatorial owned the 10 meter dish that you used to see on
> your right going south on 237 just before passing over
> Central Expressway in Mountain View.
> 
> Rick N6RK
> 
>
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Re: [time-nuts] Bye-Bye Crystals

[Bruce Griffiths]

For a sinewave oscillator

http://www.wenzel.com/wp-content/uploads/xtalosc.pdf

is a start for fundamental crystals.

However the npn transistor operates a little too close to saturation for my 
liking.

A small change to the biasing of the npn will fix this.

With overtone crystal operation mode suppression is necessary to ensure the 
crystal operates on the desired overtone.

Amateur literature on crystal oscillators and even LC oscillators includes 
quite a few relatively poor circuits.

Looking at oscillator circuits like the HP10811A will give some idea of some of 
the additional complexity required for a overtone operation. Dissecting a few 
ocxos may also be helpful. Some start with a 10MHz crystal and a Colpitts 
sustaining stage and use a 74HC74 or similar to  divide the 10Mhz by 2 and 
drive the output pin. Even when a sinewave output is required often a CMOS 
inverter drives the output pin via an LC filter.

Bruce

> 
> On 14 March 2017 at 21:44 Hal Murray  wrote:
> 
> artgod...@gmail.com said:
> 
> > > 
> > I'm not after quality - I do have an application in mind but it 
> > doesn't need
> > to compete with mass production. Just wondering if it's feasible to 
> > make
> > something crude that will resonate.
> > 
> > > 
> Are you doing this for fun or ???
> 
> Feasible? Sure. Cheaper? That depends.
> 
> The cost difference between a complete oscillator package and a simple
> crystal is tiny. The osc is often cheaper if you include board space or
> engineering time.
> 
> Is your background digital or analog? Do you want a sine wave or a clock?
> 
> My background is primarily digital. If the chip you are using has 2 pins
> setup to drive a crystal, you can probably get it to run reliably by
> following the data sheet and/or app notes. The usual recipe is 2 tiny caps
> and a big resistor. (big in resistance, not physically big)
> 
> An advantage of using a crystal with the on-chip amplifier that I didn't
> mention last time is that you save the osc power if you power down that
> corner of the chip.
> 
> If you want a sine wave, you are out of my comfort zone. I'd probably look
> in ham radio literature.
> 
> They make logic chips like a 74HCU04, U for unbuffered. One of their uses 
> is
> for making oscillators. I've never done it. Try google.
> 
> --
> These are my opinions. I hate spam.
> 
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