Re: [time-nuts] Microsemi up for sale?

[Gerhard Hoffmann]

Am 04.03.2018 um 04:04 schrieb Richard (Rick) Karlquist:

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.

I have seen that stunt at SHF Design in Berlin, don't dare to
calculate how long ago..

There were 2 lasers mixed with a 60 GHz beat frequency.
Playing with one of the Peltiers moved that to 50 GHz.
Easy to see the carrier creep on the spectrum analyzer.

Cheers, Gerhard


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Re: [time-nuts] 50 ohm drivers

[Gerhard Hoffmann]

Am 04.03.2018 um 03:17 schrieb David C. Partridge:

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 ...

Back in 80386 times, when AMD still cared about MSI, there were DRAM 
drivers with symmetrical output impedance for the Hi and Lo states. 
Today that is done by the PC chip set, with different levels.


Not very much later, I had a bus fight between a 74AS244 (saying LO!) 
and a prehistoric
Xilinx XC3020 FPGA (saying Hi!) . The AS244 was specc'ed at > 64 mA, 
used to be the
king of the hill. But the XC3020 _enforced_ a _valid HI_ . These CMOS 
thingies CAN drive

if you let them.

In my 10 MHz mod for the Lucent KS24361 I used 2 CMOS single gates with 
100 Ohms

each in series,
< 
https://www.flickr.com/photos/137684711@N07/32245910240/in/album-72157662535945536/lightbox/ 
   >


the falling edge looks like that:
< 
https://www.flickr.com/photos/137684711@N07/31781694064/in/album-72157662535945536/lightbox/ 
>


For the rising edge follow the arrow to the right.

Remember, when you terminate at the load with 50 Ohms, too, you get only
half the voltage. A 5V driver will deliver only 2.5V, nice for 2V5 CMOS, 
74HCT,

TTL and friends; quite OK for 3V3 CMOS.
I do like coax cable that is terminated in 50 Ohms.  On both sides.

Fairchild has a 74LVC family that features 7V abs max ratings; at 6.4V
that should produce picture book 3V3 levels.

Now I use 3 gates with 150 Ohms each; whatever the gate's output 
impedance is,

it doesn't matter any more against the 150 Ohm. Watch out that a gate with
elevated Vcc may need a higher HI level itself.

At 6V it rises/falls even somewhat faster.

The 3 single gates do not occupy more space than a SO-14, including their
termination resistors.

regards, Gerhard


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Re: [time-nuts] Z3801A OCXO manual trimming

[Tom Van Baak]

> Interesting point about the heater not working vs. the XTAL having drifted 
> too far.

Any logs you made of EFC percent over the past few months or years will help 
verify the off-the-rail theory.

Another thing to try -- turn-off the Z3801A for a couple of hours to let it 
cool. Disconnect the GPS antenna. Then power it up and monitor the frequency, 
say every 10 s or a minute, until it stabilizes. The shape of this warm-up 
curve will give you a hint if the oven(s) are working. Repeat the test with the 
outer oven disconnected to test the inner oven by itself.

/tvb

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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] Z3801A OCXO manual trimming

[Tom Holmes]

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 double 
> oven 10811 oscillators.
> Any ideas on the purpose of the outer heater (or whatever it is)?  Does the 
> double oven 10811 have a manual trimmer that I can adjust to bring the 
> oscillator back to the center of the EFC range?  Assuming that I can manually 
> adjust the OCXO back into adjustment range, will there be any issues with the 
> Z3801 performance, things like phase noise, short term stability, etc?
> Any suggestions will be most appreciated.
> Thanks,
> Tom
> ___
> time-nuts mailing 

Re: [time-nuts] While we are talking about Z3801's

[Hal Murray]

> Mine has quit achieving lock.
...
> After reading about someone else's trouble, i wonder if my OCXO has aged
> out.

Have you checked the status page?  Is the GPS unit seeing satellites?


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Microsemi up for sale?

[Richard (Rick) Karlquist]

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.

Rick

On 3/3/2018 6:18 PM, Hal Murray wrote:

Thanks.


rich...@karlquist.com said:

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



It turns out that, even now in 2018, optical pumping is not ready for prime
time in a working standard because the lasers drift over time.


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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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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[time-nuts] While we are talking about Z3801's

[John Green]

Mine has quit achieving lock. It goes back a ways. I had it in storage for
a while. When I got it out of storage, It took about 2 weeks to lock. It
would go into holdover sometimes for no reason I could ever discover. I
lost the ability to communicate with it. Then, one of the Lucent DC/DC
converters blew. After replacing that, it locked for a few days then
refused to lock again. In desperation, I changed out all the tantalum
capacitors with no effect. Next, I purchased a replacement Motorola GPS
receiver off eBay and tried that. Nothing. It has been back in storage
since. I plan on checking the 10 MHz output to see if it still has one and
to see just how far off it is. After reading about someone else's trouble,
i wonder if my OCXO has aged out.
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Re: [time-nuts] Microsemi up for sale?

[Hal Murray]

Thanks.


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

> It turns out that, even now in 2018, optical pumping is not ready for prime
> time in a working standard because the lasers drift over time.

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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[time-nuts] 50 ohm drivers

[David C. Partridge]

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  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  
> > wrote:
> > 
> > Ideally one should use a Collins style optimised cascade of increasing 
> > bandwidth and gain limiting stages. The LTC6957 with its selectable input 
> > stage bandwidth has a performance that is comparable with the Holzworth 
> > sine to CMOS "amplifier" which is better than any comparator by itself. If 
> > the amplitude of the input signal is large enough (i.e. input slew rate 
> > seen by the gate is large enough) the performance of a single CMOS gate can 
> > be very good. However the performance of current CMOS gates degrades in 
> > this application with input frequencies of 100MHz and above.
> > 
> > Measuring the PN performance of CMOS gates used as sine to CMOS 
> > converters is on the todo list.
> > 
> > Bruce
> > 
> > > > 
> > > On 04 March 2018 at 06:38 "David C. Partridge" 
> > >  wrote:
> > > 
> > > You might consider using MC74VHC1GT14 or MC74VHC1G14 (Schmitt 
> > > trigger inverting buffers) depending on the exact voltage levels.
> > > 
> > > They are fast (74AC logic fast) single gate devices in SC70 
> > > (SOT-353) or SOT23-5 case and can drive 25mA output if needed.
> > > 
> > > I've seen documents saying that using fast logic gates can result 
> > > in lower jitter/phase noise. Bruce - do you know ?
> > > 
> > > David
> > > 
> > > -Original Message-
> > > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of 
> > > Ulf Kylenfall via time-nuts
> > > Sent: 03 March 2018 17:08
> > > To: Discussion of Precise Time and Frequency Measurement
> > > Subject: [time-nuts] LT1016 as a pulse shaper...
> > > 
> > > Gentlemen,
> > > I have so far been using LT1016 as a pulse shaper and also 
> > > whenever I needed toconvert a sine wave into TTL Logic levels. Some 
> > > hysteresis and all the decouplingand layout precautions as recommended by 
> > > LT.
> > > Are there any similar or better alternatives out there that could 
> > > be usedthat would provide lower jitter and that are less expenceive?
> > > Ulf Kylenfall
> > > SM6GXV
> > > 
> > > ___
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> > > to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > > 
> > > ___
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> > > 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 
> > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > > 
> > > > 
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[time-nuts] X72 and 1pps

[Mark Sims]

Try enabling the PPS input form the "P menu.

Also, to verify that it is using the PPS input try the  auto-tune command.  
It will set the TIC  and DDS tune word to to 0, collect data for for however 
long you requested (an hour is a good start), then calculate the drift rate and 
set the DDS tune word to put the device on frequency.  The EE command should 
set save the DDS word in EEPROM.If the unit is seeing the PPS input, you 
should see the PPS plot stepping as the DDS freq drifts.

Many of the X72 settings cannot be read back from the unit.  Heather maintains 
a "software eeprom" with the settings that it knows about in the file 
"tbeeprom.dat".  Until you update a setting, what is displayed for that setting 
may not be correct.  Use the "P" menu to set each of the settings so that 
Heather can learn what they are.  When Heather starts up, it restores all the 
last settings from the file.
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Re: [time-nuts] Z3801A OCXO manual trimming

[Ed Palmer]

On 2018-03-03 3:56 PM, Tom Curlee wrote:


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 double oven 10811 oscillators.


You might want to read the tear-down info here: 
http://www.realhamradio.com/GPS-oven-journey.htm .  The author suggests 
that this strange structure isn't a heater, but is just a way to 
thermally isolate the inside from the outside.  Seems a bit extreme, but 
HP sometimes did things like that.  Note that right at the bottom of the 
page, there's a link to another article where the fault is diagnosed and 
repaired.



Any ideas on the purpose of the outer heater (or whatever it is)?  Does the 
double oven 10811 have a manual trimmer that I can adjust to bring the 
oscillator back to the center of the EFC range?


According to the tear-down, yes it does.


Assuming that I can manually adjust the OCXO back into adjustment range, will 
there be any issues with the Z3801 performance, things like phase noise, short 
term stability, etc?


AFAIK, it's just a 10811 with extended EFC range, so I don't see why 
tweaking the tuning would compromise anything.


Ed

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

[ewkehren via time-nuts]

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


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


Bruce

> 
> On 04 March 2018 at 10:34 Bruce Griffiths  
>wrote:
> 
> Ideally one should use a Collins style optimised cascade of increasing 
>bandwidth and gain limiting stages. The LTC6957 with its selectable input 
>stage bandwidth has a performance that is comparable with the Holzworth sine 
>to CMOS "amplifier" which is better than any comparator by itself. If the 
>amplitude of the input signal is large enough (i.e. input slew rate seen by 
>the gate is large enough) the performance of a single CMOS gate can be very 
>good. However the performance of current CMOS gates degrades in this 
>application with input frequencies of 100MHz and above.
> 
> Measuring the PN performance of CMOS gates used as sine to CMOS 
>converters is on the todo list.
> 
> Bruce
> 
> > > 
> > On 04 March 2018 at 06:38 "David C. Partridge" 
> > wrote:
> > 
> > You might consider using MC74VHC1GT14 or MC74VHC1G14 (Schmitt 
> >trigger inverting buffers) depending on the exact voltage levels.
> > 
> > They are fast (74AC logic fast) single gate devices in SC70 
> >(SOT-353) or SOT23-5 case and can drive 25mA output if needed.
> > 
> > I've seen documents saying that using fast logic gates can result 
> >in lower jitter/phase noise. Bruce - do you know ?
> > 
> > David
> > 
> > -Original Message-
> > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of 
> >Ulf Kylenfall via time-nuts
> > Sent: 03 March 2018 17:08
> > To: Discussion of Precise Time and Frequency Measurement
> > Subject: [time-nuts] LT1016 as a pulse shaper...
> > 
> > Gentlemen,
> > I have so far been using LT1016 as a pulse shaper and also whenever 
> >I needed toconvert a sine wave into TTL Logic levels. Some hysteresis and 
> >all the decouplingand layout precautions as recommended by LT.
> > Are there any similar or better alternatives out there that could 
> >be usedthat would provide lower jitter and that are less expenceive?
> > Ulf Kylenfall
> > SM6GXV
> > 
> > ___
> > 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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> > and follow the instructions there.
> > 
> > > 
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Re: [time-nuts] Setting Z3801 date

[Hal Murray]

> Setting the date should update the EEPROM.

Interesting.  It's not working that way on mine.  If I power cycle, it both 
T2 and Status page come up in Jul 1998.

Is my EEPROM worn out?  Older version of firmware?   ??

  HEWLETT-PACKARD,Z3801A,3542A01377,3543-A


-- 
These are my opinions.  I hate spam.



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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  
> wrote:
> 
> Ideally one should use a Collins style optimised cascade of increasing 
> bandwidth and gain limiting stages. The LTC6957 with its selectable input 
> stage bandwidth has a performance that is comparable with the Holzworth sine 
> to CMOS "amplifier" which is better than any comparator by itself. If the 
> amplitude of the input signal is large enough (i.e. input slew rate seen by 
> the gate is large enough) the performance of a single CMOS gate can be very 
> good. However the performance of current CMOS gates degrades in this 
> application with input frequencies of 100MHz and above.
> 
> Measuring the PN performance of CMOS gates used as sine to CMOS 
> converters is on the todo list.
> 
> Bruce
> 
> > > 
> > On 04 March 2018 at 06:38 "David C. Partridge" 
> >  wrote:
> > 
> > You might consider using MC74VHC1GT14 or MC74VHC1G14 (Schmitt 
> > trigger inverting buffers) depending on the exact voltage levels.
> > 
> > They are fast (74AC logic fast) single gate devices in SC70 
> > (SOT-353) or SOT23-5 case and can drive 25mA output if needed.
> > 
> > I've seen documents saying that using fast logic gates can result 
> > in lower jitter/phase noise. Bruce - do you know ?
> > 
> > David
> > 
> > -Original Message-
> > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of 
> > Ulf Kylenfall via time-nuts
> > Sent: 03 March 2018 17:08
> > To: Discussion of Precise Time and Frequency Measurement
> > Subject: [time-nuts] LT1016 as a pulse shaper...
> > 
> > Gentlemen,
> > I have so far been using LT1016 as a pulse shaper and also whenever 
> > I needed toconvert a sine wave into TTL Logic levels. Some hysteresis and 
> > all the decouplingand layout precautions as recommended by LT.
> > Are there any similar or better alternatives out there that could 
> > be usedthat would provide lower jitter and that are less expenceive?
> > Ulf Kylenfall
> > SM6GXV
> > 
> > ___
> > 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 
> > 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] LT1016 as a pulse shaper...

[Bob kb8tq]

Hi

If you are simply dealing with 10 MHz sine waves (as many of us are). 

— and —

It’s a “matched” application ( = you know the level / the source and converter 
are tied together) 

— and —

You don’t mind an L network to match increase the Vpp when it goes to the gate

— and —

Once the performance of the circuit is better than any source you can drive it 
with, you 
don’t care. ( = you only care if it degrades the signal) 

You can do a very good job with a biased CMOS gate. Running at 5V (or even 
better 5.5) 
will out perform 3.3V. They are dirt cheap. They are easy to solder down in 
SOT-23 packages. 
They are reasonably robust in terms of overload. They perform pretty well when 
under driven
by modest amounts. They have nice short delay paths.

What’s not to like :)

Bob



> On Mar 3, 2018, at 4:34 PM, Bruce Griffiths  
> wrote:
> 
> Ideally one should use a Collins style optimised cascade of increasing 
> bandwidth and gain limiting stages. The LTC6957 with its selectable input 
> stage bandwidth has a performance that is comparable with the Holzworth sine 
> to CMOS "amplifier" which is better than any comparator by itself. If the 
> amplitude of the input signal is large enough (i.e. input slew rate seen by 
> the gate is large enough) the performance of a single CMOS gate can be very 
> good. However the performance of current CMOS gates degrades in this 
> application with input frequencies of 100MHz and above.
> 
> Measuring the PN performance of CMOS gates used as sine to CMOS converters is 
> on the todo list.
> 
> Bruce
> 
>> 
>>On 04 March 2018 at 06:38 "David C. Partridge" 
>>  wrote:
>> 
>>You might consider using MC74VHC1GT14 or MC74VHC1G14 (Schmitt trigger 
>> inverting buffers) depending on the exact voltage levels.
>> 
>>They are fast (74AC logic fast) single gate devices in SC70 (SOT-353) or 
>> SOT23-5 case and can drive 25mA output if needed.
>> 
>>I've seen documents saying that using fast logic gates can result in 
>> lower jitter/phase noise. Bruce - do you know ?
>> 
>>David
>> 
>>-Original Message-
>>From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Ulf 
>> Kylenfall via time-nuts
>>Sent: 03 March 2018 17:08
>>To: Discussion of Precise Time and Frequency Measurement
>>Subject: [time-nuts] LT1016 as a pulse shaper...
>> 
>>Gentlemen,
>>I have so far been using LT1016 as a pulse shaper and also whenever I 
>> needed toconvert a sine wave into TTL Logic levels. Some hysteresis and all 
>> the decouplingand layout precautions as recommended by LT.
>>Are there any similar or better alternatives out there that could be 
>> usedthat would provide lower jitter and that are less expenceive?
>>Ulf Kylenfall
>>SM6GXV
>> 
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>>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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> To unsubscribe, go to 
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> 
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[time-nuts] X72 and 1pps

[Matthias Jelen]

Hello Time-Nuts,

thanks to Mark´s breakout board I was able to fire up my X72 
rubidium. It seems to work fine.


FW is 5.19.

As far as I understand from the (rather crappy) manual, I 
should be able to discipline it to 1pps, but I wasn´t lucky 
using the commands from the manual.


I switched to Lady Heather. It looks like I get TIC results 
from the X72 - The mode is reported as "Free running", so I 
guess this is the difference between the incoming PPS and 
the local one. So far so good, but if I try to enable HW 
disciplining, nothing happens. Also strange, "PPS IN" is 
reported as "OFF"...


Did anyone on this list sucessfully discipline the X72 to 
external PPS? Or has a manual that fits better to the 5.19 
FW? Or can shine some light on how the X72 1PPS feature is 
supposed to work? Any hints are highly appreciated.


Thanks & regards,

Matthias
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Re: [time-nuts] Microsemi up for sale?

[Magnus Danielson]

Rick,

On 03/03/2018 03:30 PM, Richard (Rick) Karlquist wrote:
> I asked the CBT manager at Microsemi about this
> rumor and he disavowed any knowledge of this.
> He told me they were making 8 a week (not clear
> if this is just 5071A's, or includes replacement
> CBT's).  I don't remember the production ever
> being anywhere near this level.  The reason
> for the relatively brisk sales is that the risk
> of GPS spoofing means that various military and
> 3 letter agencies need to own dedicated 5071's.
> With a large installed base of 5071's, there will
> be a guaranteed market for replacement tubes.
> The US government considers the 5071A to be of
> great strategic importance and would be certain
> to "encourage" its continued production in case
> of any business reorganization.
> 
> When we designed the 5071A twenty five years ago,
> it seemed that there were two safe bets:
> 
> 1.  Working Cs standards (outside the lab) would
> obsoleted by what HP called "smart clocks" running
> off of GPS.

We sure have seen more or less "smart" clocks being put into use an
decommissioned for hobbyists delight.

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

Interestingly enough, Oscilloquartz claim to have one, showcasing it
etc. but it's been "coming real soon" for a bit of a time now. I do not
know how that progresses.

> 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.

Moving a technology from the lab environment into production is indeed a
challenge.

> The 5071A's claim to fame is that you turn it on and it just
> works ... until it runs out of cesium.  That is
> another reason the 5071A isn't going away any time soon.

It belongs clearly to the moderns cesiums which just operates and trims
up itself well. In my basement I currently have two where one had a
workiing CBT and failing electronics while the other had failed CBT and
working electronics. So I got to long-time borrow them to swap tubes and
use them. :)

Cheers,
Magnus
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Re: [time-nuts] Z3801A OCXO manual trimming

[Bob kb8tq]

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 double 
> oven 10811 oscillators.
> Any ideas on the purpose of the outer heater (or whatever it is)?  Does the 
> double oven 10811 have a manual trimmer that I can adjust to bring the 
> oscillator back to the center of the EFC range?  Assuming that I can manually 
> adjust the OCXO back into adjustment range, will there be any issues with the 
> Z3801 performance, things like phase noise, short term stability, etc?
> Any suggestions will be most appreciated.
> Thanks,
> Tom
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Re: [time-nuts] LT1016 as a pulse shaper...

[Richard (Rick) Karlquist]

In the 5071A, we squared up an 80 MHz clock with a 74AC04 gate
capacitively coupled with resistive bias to set it at half
the supply current; not a resistor from input to output as
you often see.

Ever since the LT1016 came out, it has been the "easy" way
to square up a sine wave.  Easy != high performance.  The
temperature drift of the delay time in the LT1016 is
very substantial.

Regarding ultra high speed comparators:  No you don't want
the fastest one you can get.  That just maximizes the jitter.
You merely want "good enough" speed.  In any event, comparators
are never a low jitter way to square up a sine wave.

Rick N6RK

On 3/3/2018 10:34 AM, Mark Sims wrote:

Look at the LPRO manual.  They have a couple of circuits that uses a single CMOS gate 
with a capacitively coupled input.   Wenzel has some very similar circuits on their web 
site (search for "Wenzel squarer").

My HP-531xx counter calibrator board uses on as the input squarer (with a 
74HCT86 as the gate).  I measured the ADEVs of the output and they were 
indistinguishable from the input.
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[time-nuts] Z3801A OCXO manual trimming

[Tom Curlee]

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 double oven 
10811 oscillators.
Any ideas on the purpose of the outer heater (or whatever it is)?  Does the 
double oven 10811 have a manual trimmer that I can adjust to bring the 
oscillator back to the center of the EFC range?  Assuming that I can manually 
adjust the OCXO back into adjustment range, will there be any issues with the 
Z3801 performance, things like phase noise, short term stability, etc?
Any suggestions will be most appreciated.
Thanks,
Tom
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Re: [time-nuts] Microsemi up for sale?

[Bob kb8tq]

Hi

There’s a big chunk of sales under the “not semiconductor” side of Microsemi.  
It may
not be big compared to an $8 billion sell price, but it’s not a trivial part of 
the company. 
Exactly what happens to things like the 5071 … we’ll see …..

How the sales policies of one or the other  company impact the new combine 
after a deal 
is always a bit unclear.  It may be a few years before that all gets worked 
out. Not all 
mergers get sorted on the first day. Their statement about $300 Million savings 
in the
third year might suggest a slow-er approach to consolidation. 

Bob

> On Mar 3, 2018, at 12:45 PM, Forrest Christian (List Account) 
>  wrote:
> 
> There is an announcement of the impending purchase on the Microchip website.
> 
> From my perspective this is a good thing as I've been eyeing some of the
> microsemi semiconductor products for some time for use in various designs
> of mine and this is likely to make those products easier to incorporate due
> to the microchip sales policies.
> 
> Not sure how this will work for the finished products they sell as
> historically microchip has only been a semiconductor maker.  It wouldn't be
> surprising to see microchip divest themselves of the assembled product
> line.  I know microchip has divested themselves of small portions of
> acquired businesses in the past when they didn't fit their roadmap.
> 
> 
> 
> On Mar 3, 2018 8:48 AM, "ewkehren via time-nuts"  wrote:
> 
>> The manager many not know but the market does and there have been
>> announcements and the stock is up and for the day the fifth most active of
>> all US markets. At 2 pm #2Bert Kehren
>> 
>> 
>> Sent from my Galaxy Tab® A
>>  Original message From: "Richard (Rick) Karlquist" <
>> rich...@karlquist.com> Date: 3/3/18  9:30 AM  (GMT-05:00) To: Discussion
>> of precise time and frequency measurement , Anders
>> Wallin  Subject: Re: [time-nuts] Microsemi
>> up for sale?
>> I asked the CBT manager at Microsemi about this
>> rumor and he disavowed any knowledge of this.
>> He told me they were making 8 a week (not clear
>> if this is just 5071A's, or includes replacement
>> CBT's).  I don't remember the production ever
>> being anywhere near this level.  The reason
>> for the relatively brisk sales is that the risk
>> of GPS spoofing means that various military and
>> 3 letter agencies need to own dedicated 5071's.
>> With a large installed base of 5071's, there will
>> be a guaranteed market for replacement tubes.
>> The US government considers the 5071A to be of
>> great strategic importance and would be certain
>> to "encourage" its continued production in case
>> of any business reorganization.
>> 
>> When we designed the 5071A twenty five years ago,
>> it seemed that there were two safe bets:
>> 
>> 1.  Working Cs standards (outside the lab) would
>> obsoleted by what HP called "smart clocks" running
>> off of GPS.
>> 
>> 2.  Magnetic state selection, as used in the 5071A,
>> would be replaced by optical pumping.  Len Cutler
>> was heartbroken that HP/Agilent management wouldn't
>> fund this effort.
>> 
>> It turns out that, even now in 2018, optical pumping
>> is not ready for prime time in a working standard
>> because the lasers drift over time.  The 5071A's
>> claim to fame is that you turn it on and it just
>> works ... until it runs out of cesium.  That is
>> another reason the 5071A isn't going away any time soon.
>> 
>> Rick Karlquist N6RK
>> Member: 5071A design team
>> 
>> On 3/3/2018 1:22 AM, Anders Wallin wrote:
>>> Just a change to the last part of the name then ;)
>>> https://www.ft.com/content/10192a2a-1d99-11e8-956a-43db76e69936
>>> "semi" -> "chip"
>>> 
>>> 
>>> On Sat, Jan 27, 2018 at 1:27 AM, Clint Jay  wrote:
>>> 
 Perhaps of interest to the list
 
 https://www.theregister.co.uk/2018/01/25/microsemi/
 
 --
 Clint.
 
 *No trees were harmed in the sending of this mail. However, a large
>> number
 of electrons were greatly inconvenienced.*
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 mailman/listinfo/time-nuts
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>>> ___
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>> mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> 
>>> 
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[time-nuts] LT1016 as a pulse shaper...

[Mark Sims]

Look at the LPRO manual.  They have a couple of circuits that uses a single 
CMOS gate with a capacitively coupled input.   Wenzel has some very similar 
circuits on their web site (search for "Wenzel squarer").

My HP-531xx counter calibrator board uses on as the input squarer (with a 
74HCT86 as the gate).  I measured the ADEVs of the output and they were 
indistinguishable from the input.
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[time-nuts] Output impedance of MC74VHC logic?

[Mark Sims]

I don't know about the VHC family, buy the LVC1G family can drive 24 mA.

My interface boards for connecting the LPFRS/LPRO or the TS-RFS to my BNC/SMA 
connector board has a PICDIV for making a 1PPS signal and uses a 74LVC1G125 to 
buffer it.  Also my PRS10 interface uses one to buffer the 1PPS output.
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Re: [time-nuts] LT1016 as a pulse shaper...

[Mark Goldberg]

Search for ultra fast comparator yields TL3016 and AD8611, claims to be
faster pin compatible replacements.  I have found low parasitic capacitance
on the outputs of these types of comparators is important, and I have used
balanced hysteresis (use positive feedback from both + and - outputs). I
haven't needed jitter lower than 10 ns or so, with awful inputs, so have
not optimized for lower jitter.

Search google for "ultra fast comparator" and several turn up that are in
the low ns or hundreds of ps range for prop delay. ADCMP566, TL3116,
LMH7322, LTC6752, MAX9691 turn up among others. I haven't investigated or
used any of them.

Regards,

Mark Goldberg




On Sat, Mar 3, 2018 at 10:08 AM, Ulf Kylenfall via time-nuts <
time-nuts@febo.com> wrote:

>
> 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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> mailman/listinfo/time-nuts
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>
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Re: [time-nuts] Microsemi up for sale?

[Forrest Christian (List Account)]

There is an announcement of the impending purchase on the Microchip website.

>From my perspective this is a good thing as I've been eyeing some of the
microsemi semiconductor products for some time for use in various designs
of mine and this is likely to make those products easier to incorporate due
to the microchip sales policies.

Not sure how this will work for the finished products they sell as
historically microchip has only been a semiconductor maker.  It wouldn't be
surprising to see microchip divest themselves of the assembled product
line.  I know microchip has divested themselves of small portions of
acquired businesses in the past when they didn't fit their roadmap.



On Mar 3, 2018 8:48 AM, "ewkehren via time-nuts"  wrote:

> The manager many not know but the market does and there have been
> announcements and the stock is up and for the day the fifth most active of
> all US markets. At 2 pm #2Bert Kehren
>
>
> Sent from my Galaxy Tab® A
>  Original message From: "Richard (Rick) Karlquist" <
> rich...@karlquist.com> Date: 3/3/18  9:30 AM  (GMT-05:00) To: Discussion
> of precise time and frequency measurement , Anders
> Wallin  Subject: Re: [time-nuts] Microsemi
> up for sale?
> I asked the CBT manager at Microsemi about this
> rumor and he disavowed any knowledge of this.
> He told me they were making 8 a week (not clear
> if this is just 5071A's, or includes replacement
> CBT's).  I don't remember the production ever
> being anywhere near this level.  The reason
> for the relatively brisk sales is that the risk
> of GPS spoofing means that various military and
> 3 letter agencies need to own dedicated 5071's.
> With a large installed base of 5071's, there will
> be a guaranteed market for replacement tubes.
> The US government considers the 5071A to be of
> great strategic importance and would be certain
> to "encourage" its continued production in case
> of any business reorganization.
>
> When we designed the 5071A twenty five years ago,
> it seemed that there were two safe bets:
>
> 1.  Working Cs standards (outside the lab) would
> obsoleted by what HP called "smart clocks" running
> off of GPS.
>
> 2.  Magnetic state selection, as used in the 5071A,
> would be replaced by optical pumping.  Len Cutler
> was heartbroken that HP/Agilent management wouldn't
> fund this effort.
>
> It turns out that, even now in 2018, optical pumping
> is not ready for prime time in a working standard
> because the lasers drift over time.  The 5071A's
> claim to fame is that you turn it on and it just
> works ... until it runs out of cesium.  That is
> another reason the 5071A isn't going away any time soon.
>
> Rick Karlquist N6RK
> Member: 5071A design team
>
> On 3/3/2018 1:22 AM, Anders Wallin wrote:
> > Just a change to the last part of the name then ;)
> > https://www.ft.com/content/10192a2a-1d99-11e8-956a-43db76e69936
> > "semi" -> "chip"
> >
> >
> > On Sat, Jan 27, 2018 at 1:27 AM, Clint Jay  wrote:
> >
> >> Perhaps of interest to the list
> >>
> >> https://www.theregister.co.uk/2018/01/25/microsemi/
> >>
> >> --
> >> Clint.
> >>
> >> *No trees were harmed in the sending of this mail. However, a large
> number
> >> of electrons were greatly inconvenienced.*
> >> ___
> >> 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.
> >>
> > ___
> > 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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> mailman/listinfo/time-nuts
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>
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[time-nuts] Setting Z3801 date

[Mark Sims]

Setting the date should update the EEPROM.

---

> I think the second power down in there resets the date.
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Re: [time-nuts] LT1016 as a pulse shaper...

[David C. Partridge]

You might consider using MC74VHC1GT14 or MC74VHC1G14 (Schmitt trigger inverting 
buffers) depending on the exact voltage levels.

They are fast (74AC logic fast) single gate devices in SC70 (SOT-353) or 
SOT23-5 case and can drive 25mA output if needed.

I've seen documents saying that using fast logic gates can result in lower 
jitter/phase noise.  Bruce - do you know ?

David

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Ulf Kylenfall 
via time-nuts
Sent: 03 March 2018 17:08
To: Discussion of Precise Time and Frequency Measurement
Subject: [time-nuts] LT1016 as a pulse shaper...

 
Gentlemen,
I have so far been using LT1016 as a pulse shaper and also whenever I needed 
toconvert a sine wave into TTL Logic levels. Some hysteresis and all the 
decouplingand layout precautions as recommended by LT.
Are there any similar or better alternatives out there that could be usedthat 
would provide lower jitter and that are less expenceive?
Ulf Kylenfall
SM6GXV
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[time-nuts] LT1016 as a pulse shaper...

[Ulf Kylenfall via time-nuts]

 
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] Output impedance of MC74VHC logic?

[Richard (Rick) Karlquist]

It's not just that you need to have small signal Thevenin source
impedance << 50 ohms, you also need to be able to
deliver sufficient current, at the rated logic
voltage swing of the device.  If the device is swinging
rail to rail, and you drive a 50 ohm load through a
50 ohm resistor in series with a blocking capacitor,
the device has to be able to source and sink 16.5 mA.
You can also estimate the Thevenin impedance from the
data sheet numbers giving voltage swing vs current.
You probably won't get rail to rail swing at 16.5 mA
with your gate, or any other CMOS gate.  In all
likelihood, you will want to do something like
use a 74__04 Hex Inverter with all 6 gates wired in
parallel.

If you follow your driver with a bandpass filter, it
should be a design that presents a high impedance to
the driver at harmonic frequencies so the gate can
be happy making a square wave of voltage.  This gives
an advantage of 4/pi in drive capability.

Rick N6RK

On 3/3/2018 4:09 AM, David C. Partridge wrote:

Using this to buffer output from an LPRO (74VHC1G14 (Schmitt trigger 3.3V
TTL compatible)), or an Efratom 105243-003 10MHz OCXO with CMS output
(74VHC1GU04 CMOS levels) in a 10MHz mod for the KS-24019 RFTGm-II.

To match well to 50R bandpass I want to add a series resistor to the output
but don't know the output impedance of these single logic gates.

Does anyone know what this is please?

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Re: [time-nuts] Microsemi up for sale?

[ewkehren via time-nuts]

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


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

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

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

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

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

Rick Karlquist N6RK
Member: 5071A design team

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

[Richard (Rick) Karlquist]

I asked the CBT manager at Microsemi about this
rumor and he disavowed any knowledge of this.
He told me they were making 8 a week (not clear
if this is just 5071A's, or includes replacement
CBT's).  I don't remember the production ever
being anywhere near this level.  The reason
for the relatively brisk sales is that the risk
of GPS spoofing means that various military and
3 letter agencies need to own dedicated 5071's.
With a large installed base of 5071's, there will
be a guaranteed market for replacement tubes.
The US government considers the 5071A to be of
great strategic importance and would be certain
to "encourage" its continued production in case
of any business reorganization.

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

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

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

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

Rick Karlquist N6RK
Member: 5071A design team

On 3/3/2018 1:22 AM, Anders Wallin wrote:

Just a change to the last part of the name then ;)
https://www.ft.com/content/10192a2a-1d99-11e8-956a-43db76e69936
"semi" -> "chip"


On Sat, Jan 27, 2018 at 1:27 AM, Clint Jay  wrote:


Perhaps of interest to the list

https://www.theregister.co.uk/2018/01/25/microsemi/

--
Clint.

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*
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[time-nuts] Output impedance of MC74VHC logic?

[David C. Partridge]

Using this to buffer output from an LPRO (74VHC1G14 (Schmitt trigger 3.3V
TTL compatible)), or an Efratom 105243-003 10MHz OCXO with CMS output
(74VHC1GU04 CMOS levels) in a 10MHz mod for the KS-24019 RFTGm-II.

To match well to 50R bandpass I want to add a series resistor to the output
but don't know the output impedance of these single logic gates.

Does anyone know what this is please?

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Re: [time-nuts] Microsemi up for sale?

[Anders Wallin]

Just a change to the last part of the name then ;)
https://www.ft.com/content/10192a2a-1d99-11e8-956a-43db76e69936
"semi" -> "chip"


On Sat, Jan 27, 2018 at 1:27 AM, Clint Jay  wrote:

> Perhaps of interest to the list
>
> https://www.theregister.co.uk/2018/01/25/microsemi/
>
> --
> Clint.
>
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
> ___
> 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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