Re: [time-nuts] HP5065a cfield issue

[paul swed]

For everyone when the cfield pot is at 0.0 its 2.5ma and at 9.9 its 6.38ma.
The jump is over 4 major divisions of the cfield pot and I still did not
match the reference..
So looking at the synth chart on page 3-9 started to see how far it had
gone.
Tube says the switch should be 8714 or -240 E-10 the switch setting that
works well is 7698 and that represents -230 E-10. Thats quite a change. But
the Cfield matches the reference at 3.5 and that takes 6 min and 53 seconds
to move 5ns. Could do better but ran out of time tonight) Its still
slightly fast. The green cont op lights and stays lit. Some of the chart
settings do not light the con op light. Will see if the unit actually stays
stable overnight or does it speed up or slow down.
If it does thats going to be tough to find.
Thanks everyone so far for your help.
Paul.

On Wed, Dec 2, 2020 at 7:51 PM Bob kb8tq  wrote:

> Hi
>
> Ok, if that still turns out to be correct … that’s just about 2 ppb. (
> 1.6667…).
> To do that with the C field, you would need to make a *major* change. It’s
> essentially the whole range of the pot. You already know that it’s off in
> the
> direction of needing more counts on the dial. I *think* the current is
> lowest
> at that end, but I could easily be wrong. Either you need zero current or
> 2X normal. Either way that should be easy to spot.
>
> Bob
>
>
>
> > On Dec 2, 2020, at 2:59 PM, paul swed  wrote:
> >
> > Yes absolutely it can go back and it is the same offset. I can get real
> > numbers from memory 3 seconds for 5ns drift and the units slow. Will
> > confirm and reshare.
> > Regards
> > Paul.
> >
> >
> > On Wed, Dec 2, 2020 at 2:52 PM Bob kb8tq  wrote:
> >
> >> Hi
> >>
> >> Just double checking….. Are we still after a change went past 1/3 of the
> >> pot range?
> >>
> >> Can we get the pot back to the original location and measure the
> frequency
> >> offset
> >> (even if only in a crude fashion)?
> >>
> >> Best guess is still that this should be a ppb or more of shift. If it’s
> >> down in the
> >> 4x10^-11 range then indeed, there’s something off in the C Field setup.
> >>
> >> Bob
> >>
> >>> On Dec 2, 2020, at 2:03 PM, paul swed  wrote:
> >>>
> >>> Corby will check. Though in looking at the cfield circuits it does
> appear
> >>> all to be correct. Its some other odd offset that has crept in.
> >>> Thanks
> >>>
> >>> On Wed, Dec 2, 2020 at 1:56 PM  wrote:
> >>>
>  Paul,
> 
>  One other thing to check.
> 
>  Put a DC coupled scope on the C-field pot wiper and rotate the pot
> back
>  and forth.
> 
>  Make sure there are no jumps or noise.
> 
>  Sometimes the pot gets noisy in a section.
> 
>  Rotating it back and forth across the bad sections will usually clean
> it
>  up.
> 
>  Cheers,
> 
>  Corby
> 
> 
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Re: [time-nuts] HP5061 Cesium ion pump question

[paul swed]

Andy
What a find and what luck you did it right from the start.
If you had not allowed it to pump down the way you did it may have mislead
you into thinking there was a big problem with the rest of the circuits not
turning on or pulsing on and off. All expected and normal in a gassy tube.
Its funny because I know of another HP Cesium or RB sitting in a barn in
Colorado and simply can't get the person to even drag it out for a picture.
Like you he found it on the side of the street years ago. Never powered it
up. Suspect it doesn't have a power cable.
Maybe I will try one more time. He has had health problems and can't really
lift. I suspect thats more of the issue.
Regards
Paul

On Wed, Dec 2, 2020 at 10:47 AM Andy Talbot  wrote:

> When I found my HP5061A lingering in a skip, soaked in rainwater some 20
> plus years ago, I thought I'd be lucky if it was only good for the OCXO,
> and never even contemplated it might be fully working.  I first left it in
> a warm room for a week to dry out then, without having a clue about how to
> get it going, tentatively plugged it in with the switch set to 'Caesium
> off', and just left it alone to stabilise.   With no instructions that
> seemed instinctively the right thing to do.   To my delight 5MHz appeared,
> so I borrowed a Rb standard from work to check, and the OCXO was clearly
> working well - very well - at first sight, just looking at traces on a
> scope, the OCXO seemed as stable  and accurate as the Rb was supposed to
> be.   I already had an MSF reference at that time, so comparisons were made
> against that too.
>
> Over a period of a couple of weeks I just left teh 5061A running and put
> out an appeal on the LF chat group on the  (still quite new then) Internet
> for anyone who could help me with a manual.   SOme kind person trusted me
> enough to actually post me their hard copy on loan, which I copied,
> returned the original and studied thoroughly.  And discovered
>
> THE FIRST THING TO DO when powering up from cold is to leave it in standby
> for several days / weeks to pump out the ions.   EXACTLY what I'd already
> done! Without thinking.  So as soon as I'd read that paragraph, following
> the instructions, tentatively switched to 'open-loop' and watched the meter
> showing beam current rise.  After an hour or so when it appeared to have
> settled,  (I was too excited to wait the recommended three) switched to
> 'OPER' and pressed the reset button.   The joy when the green light came on
> !   A working Cs standard, recovered as scrap from a skip.   The light went
> off after an hour, but pressing the button made it come back on, and it
> stayed on from then on.
>
> Further studying the manual, and vaguely knowing that unit's history and
> politics surrounding the original owning organisation, (don't ask, I won't
> say)  suggested there could actually  be a fair bit of life left in the
> tube - beam current certainly suggested so.The internal NiCd batteries
> were completely dead and had a few green crystals on them, so I removed the
> whole battery and its charging circuitry, substituted an LM317 regulator
> set for 27.2V and used a pair of (old second hand) lead acid gel cells as
> backup instead.   And there it sits to this day, on standby
> continuously for over 20 years with the Cs switched on when wanted.
>  Typically it only needs 35 - 45 minutes warm up, so I allow 1.5 - 2 hours
> before any serious tests that need full accuracy.   Ironically, it's been
> running for so long the only things to have failed have been my backup gel
> cells - floated in series at 27.2V, one set bulged alarmingly after some 13
> years, and another pair died such that it couldn't hold-up even standby for
> more than about 15 minutes when mains went off.   I replaced those only two
> weeks ago.
>
> The only thing I've never tried is calibrating out local magnetic field
> using Zeeman lines.   Not having the Cs running continuously, I suspect
> this would be a pointless exercise  anyway, and the loss of a few parts in
> 10^-13 don't over-worry me.
>
>
> Andy
> www.g4jnt.com
>
>
>
> On Wed, 2 Dec 2020 at 14:43, paul swed  wrote:
>
> > Morris
> > I do see that of the 3 HP5061s the results are different and do know each
> > tube leaks or internally emits stuff. But as you say maybe the metering
> is
> > off. It definitely trips out at 40ua.
> > I have my units that pulse like that and then settle down as the tube
> > clears.
> > But its hard to explain that if a unit is pumped down how quickly it
> > pollutes again.
> > Wondering if as an example the getter just releases its captured crud
> when
> > the power is removed. That way you are always pumping down mostly the
> same
> > stuff.
> > Just very curious.
> > Regards
> > Paul
> > WB8TSL
> >
> >
> > On Wed, Dec 2, 2020 at 6:23 AM  wrote:
> >
> > > I think there's quite a bit of variation in leakage rates between
> > > individual
> > > physics packages, and there's also variation in the accuracy of the
> > > 

Re: [time-nuts] HP5065a cfield issue

[Bob kb8tq]

Hi

Ok, if that still turns out to be correct … that’s just about 2 ppb. ( 
1.6667…). 
To do that with the C field, you would need to make a *major* change. It’s
essentially the whole range of the pot. You already know that it’s off in the 
direction of needing more counts on the dial. I *think* the current is lowest
at that end, but I could easily be wrong. Either you need zero current or 
2X normal. Either way that should be easy to spot.

Bob



> On Dec 2, 2020, at 2:59 PM, paul swed  wrote:
> 
> Yes absolutely it can go back and it is the same offset. I can get real
> numbers from memory 3 seconds for 5ns drift and the units slow. Will
> confirm and reshare.
> Regards
> Paul.
> 
> 
> On Wed, Dec 2, 2020 at 2:52 PM Bob kb8tq  wrote:
> 
>> Hi
>> 
>> Just double checking….. Are we still after a change went past 1/3 of the
>> pot range?
>> 
>> Can we get the pot back to the original location and measure the frequency
>> offset
>> (even if only in a crude fashion)?
>> 
>> Best guess is still that this should be a ppb or more of shift. If it’s
>> down in the
>> 4x10^-11 range then indeed, there’s something off in the C Field setup.
>> 
>> Bob
>> 
>>> On Dec 2, 2020, at 2:03 PM, paul swed  wrote:
>>> 
>>> Corby will check. Though in looking at the cfield circuits it does appear
>>> all to be correct. Its some other odd offset that has crept in.
>>> Thanks
>>> 
>>> On Wed, Dec 2, 2020 at 1:56 PM  wrote:
>>> 
 Paul,
 
 One other thing to check.
 
 Put a DC coupled scope on the C-field pot wiper and rotate the pot back
 and forth.
 
 Make sure there are no jumps or noise.
 
 Sometimes the pot gets noisy in a section.
 
 Rotating it back and forth across the bad sections will usually clean it
 up.
 
 Cheers,
 
 Corby
 
 
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Re: [time-nuts] HP5065a cfield issue

[paul swed]

Yes absolutely it can go back and it is the same offset. I can get real
numbers from memory 3 seconds for 5ns drift and the units slow. Will
confirm and reshare.
Regards
Paul.


On Wed, Dec 2, 2020 at 2:52 PM Bob kb8tq  wrote:

> Hi
>
> Just double checking….. Are we still after a change went past 1/3 of the
> pot range?
>
> Can we get the pot back to the original location and measure the frequency
> offset
> (even if only in a crude fashion)?
>
> Best guess is still that this should be a ppb or more of shift. If it’s
> down in the
> 4x10^-11 range then indeed, there’s something off in the C Field setup.
>
> Bob
>
> > On Dec 2, 2020, at 2:03 PM, paul swed  wrote:
> >
> > Corby will check. Though in looking at the cfield circuits it does appear
> > all to be correct. Its some other odd offset that has crept in.
> > Thanks
> >
> > On Wed, Dec 2, 2020 at 1:56 PM  wrote:
> >
> >> Paul,
> >>
> >> One other thing to check.
> >>
> >> Put a DC coupled scope on the C-field pot wiper and rotate the pot back
> >> and forth.
> >>
> >> Make sure there are no jumps or noise.
> >>
> >> Sometimes the pot gets noisy in a section.
> >>
> >> Rotating it back and forth across the bad sections will usually clean it
> >> up.
> >>
> >> Cheers,
> >>
> >> Corby
> >>
> >>
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> >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
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> >>
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Re: [time-nuts] HP5061 Cesium ion pump question

[paul swed]

Corby that explains what I have been seeing and wondering about over the
years I have had Cesiums. Get it all pumped down and then the next time I
get those bursts. I am letting a recent 5061 pump down. It seems to get
really dirty each time I start it but gets down to 16 on the meter after
some 48 hours. I run the Cesiums at least per quarter.
Really appreciate this insight you shared.
Thank you.
Paul
WB8TSL

On Wed, Dec 2, 2020 at 2:27 PM  wrote:

> The gettering in the tube is only for capturing any stray Cesium atoms
> that don't get caught in the main gettering patch. If the gettering fails
> or gets too loaded up then the Cesium background level will get too high
> causing poor SN.
>
> The ion pump is for any gases.
>
> When a tube is off for extended times any gas atoms lingering or leaking
> slowly into the tube than happen to impinge on either the mass
> Spectrometer filament or the Cs oven filaments get capture by the
> filaments. They function as excellent getters!  (this even if the ion
> pump is on)
>
> Now this is not by design but results in the filaments being "loaded"
> with the gas atoms.
>
> Then when you turn the tube on the filaments light up and expell a burst
> of gas.
>
> This of coarse causes the ion pump current to rise and trips off the
> filaments,
>
> Once the ion pump removes the burst the cycle repeats until the filaments
> have expelled the trapped gases.
>
> Then the ion pump can handle the load and pump the tube down completely.
>
> Cheers,
>
> Corby
>
>
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Re: [time-nuts] HP5065a cfield issue

[Bob kb8tq]

Hi

Just double checking….. Are we still after a change went past 1/3 of the pot 
range? 

Can we get the pot back to the original location and measure the frequency 
offset
(even if only in a crude fashion)? 

Best guess is still that this should be a ppb or more of shift. If it’s down in 
the
4x10^-11 range then indeed, there’s something off in the C Field setup.

Bob

> On Dec 2, 2020, at 2:03 PM, paul swed  wrote:
> 
> Corby will check. Though in looking at the cfield circuits it does appear
> all to be correct. Its some other odd offset that has crept in.
> Thanks
> 
> On Wed, Dec 2, 2020 at 1:56 PM  wrote:
> 
>> Paul,
>> 
>> One other thing to check.
>> 
>> Put a DC coupled scope on the C-field pot wiper and rotate the pot back
>> and forth.
>> 
>> Make sure there are no jumps or noise.
>> 
>> Sometimes the pot gets noisy in a section.
>> 
>> Rotating it back and forth across the bad sections will usually clean it
>> up.
>> 
>> Cheers,
>> 
>> Corby
>> 
>> 
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[time-nuts] HP5061 Cesium ion pump question

[cdelect]

The gettering in the tube is only for capturing any stray Cesium atoms
that don't get caught in the main gettering patch. If the gettering fails
or gets too loaded up then the Cesium background level will get too high
causing poor SN.

The ion pump is for any gases.

When a tube is off for extended times any gas atoms lingering or leaking
slowly into the tube than happen to impinge on either the mass
Spectrometer filament or the Cs oven filaments get capture by the
filaments. They function as excellent getters!  (this even if the ion
pump is on) 

Now this is not by design but results in the filaments being "loaded"
with the gas atoms.

Then when you turn the tube on the filaments light up and expell a burst
of gas.

This of coarse causes the ion pump current to rise and trips off the
filaments,

Once the ion pump removes the burst the cycle repeats until the filaments
have expelled the trapped gases.

Then the ion pump can handle the load and pump the tube down completely.

Cheers,

Corby


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Re: [time-nuts] HP5065a cfield issue

[paul swed]

Corby will check. Though in looking at the cfield circuits it does appear
all to be correct. Its some other odd offset that has crept in.
Thanks

On Wed, Dec 2, 2020 at 1:56 PM  wrote:

> Paul,
>
> One other thing to check.
>
> Put a DC coupled scope on the C-field pot wiper and rotate the pot back
> and forth.
>
> Make sure there are no jumps or noise.
>
> Sometimes the pot gets noisy in a section.
>
> Rotating it back and forth across the bad sections will usually clean it
> up.
>
> Cheers,
>
> Corby
>
>
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[time-nuts] HP5065a cfield issue

[cdelect]

Paul,

One other thing to check.

Put a DC coupled scope on the C-field pot wiper and rotate the pot back
and forth.

Make sure there are no jumps or noise.

Sometimes the pot gets noisy in a section.

Rotating it back and forth across the bad sections will usually clean it
up.

Cheers,

Corby


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Re: [time-nuts] 5370B / TimeLab question

[jimlux]

On 12/2/20 10:17 AM, djl wrote:

or:
https://ntrs.nasa.gov/citations/19870019361
from Charlie Greenhall



A nicer looking version is available at

https://ipnpr.jpl.nasa.gov/

click the 1980-189 button
use your browser's search function for Greenhall..

https://ipnpr.jpl.nasa.gov/progress_report/42-90/90S.PDF

(the search button on the website doesn't work. I just put in a ticket)


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Re: [time-nuts] 5370B / TimeLab question

[djl]

or:
https://ntrs.nasa.gov/citations/19870019361
from Charlie Greenhall

On 2020-12-01 15:52, Tom Van Baak wrote:

Hi Skip,

You are exactly right. And, surprisingly, this is correct and normal
for most TI counters.

The short answer is -- for your use case, a *zero deadtime* time
interval counter (TIC) or a timestamping counter (TSC), is what you
want.



The long answer is -- your problems is due to counter dead time. That
is, in TI mode, the counter waits for chA, and then waits for chB, and
then calculates and reports the chB-chA time interval measurement. The
latter takes finite time and depending on the counter it may consume
milliseconds or even tens of milliseconds. Part of it is CPU time,
part of it is I/O time (GPIB, RS232/USB, even LAN takes time).

So as chB drifts far away from chA, the next chA may occur during the
short busy measurement report window while the counter is "blind". The
counter then has to wait for the *next* next chA and this results in a
reduction in measurement rate from exactly 10 sps to exactly 5 sps.
Annoying as it is, it's actually a nice way to measure the counter's
deadtime ;-)

Note that this problem occurs with any TI measurement, but it is much
worse with a DMTD, so that's why you ran into already! If you were to
compare a OCXO/1PPS against a GPS/1PPS you might have to wait *years*
before a 1 s phase wrap, a counter deadtime issue, occurred.

You see, a DMTD is a huge magnifier. The good news is that it
magnifies phase difference and magnifies short-term instability by a
factor of, say, 500,000. The bad news is that it also magnifies phase
wrapping by 500,000. So instead of having an annoying 1 s phase wrap
every couple of years, or even once a lifetime, you're going to see it
happen every couple of hours



Ok, that said, one solution to this mess is to use a timestamping
counter (TSC) instead of a time interval counter (TIC). Yes, your
TAPR/TICC will work perfectly for this. In fact, this is the main
reason that the TICC was designed to be a flexible dual, independent,
simultaneous, zero-deadtime, chA-*and*-chB timestamping counter
instead of a traditional hardcoded chA-*to*-chB time interval counter.

Another solution is to use a microcontroller-based timer that can do
multi-channel timestamp captures. I have used synchronized picPET's
for this in the past. But more recently, for Corby's new DMTD, I
created a six channel timer that can do timestamping or *zero
deadtime* time interval measurements. Right now this solution works
better than a 5370B or 53132A at 1/100th the price.

Still, if you have a TAPR/TICC use that instead of your 5370B.

/tvb


On 12/1/2020 12:04 PM, Skip Withrow wrote:

Hello Time-Nuts,
I have been having fun playing with the DMTD, but have a question
regarding data collection.

Obviously with a 10Hz offset oscillator I am feeding square waves with
a 100ms period to the START and STOP of the 5370B.  The trigger lights
are happily blinking away at 10Hz.  However, I seem to have two
different operating modes depending on the difference between the
START and STOP signals.

If the difference is small, no problem.  I get 10 samples per second
when TimeLab is run (TimeLab puts the 5370B in Talk Only mode, I
believe).  When the difference between START and STOP approaches
something larger than 50ms I start getting only 5 samples per second.
  I believe this is because the re-arm time misses the next START 
edge,

such that I get every other sample.

This definitely gives bad data for TimeLab.  So, the question is, how
do I straighten out this mess?  For long-term measurements with two
oscillators that have any kind offset/aging difference you are toast.
I have thought about maybe adding a 10Hz EXT ARM signal, but if it is
not at exactly the 10Hz difference frequency that could create
problems too (and it is a pain in the butt).

I would like to use the 5370B, but maybe it's time to switch to the 
TICC.


Any suggestions would be appreciated.

Thanks,
Skip Withrow

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--
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304


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Re: [time-nuts] HP5061 Cesium ion pump question

[Andy Talbot]

When I found my HP5061A lingering in a skip, soaked in rainwater some 20
plus years ago, I thought I'd be lucky if it was only good for the OCXO,
and never even contemplated it might be fully working.  I first left it in
a warm room for a week to dry out then, without having a clue about how to
get it going, tentatively plugged it in with the switch set to 'Caesium
off', and just left it alone to stabilise.   With no instructions that
seemed instinctively the right thing to do.   To my delight 5MHz appeared,
so I borrowed a Rb standard from work to check, and the OCXO was clearly
working well - very well - at first sight, just looking at traces on a
scope, the OCXO seemed as stable  and accurate as the Rb was supposed to
be.   I already had an MSF reference at that time, so comparisons were made
against that too.

Over a period of a couple of weeks I just left teh 5061A running and put
out an appeal on the LF chat group on the  (still quite new then) Internet
for anyone who could help me with a manual.   SOme kind person trusted me
enough to actually post me their hard copy on loan, which I copied,
returned the original and studied thoroughly.  And discovered

THE FIRST THING TO DO when powering up from cold is to leave it in standby
for several days / weeks to pump out the ions.   EXACTLY what I'd already
done! Without thinking.  So as soon as I'd read that paragraph, following
the instructions, tentatively switched to 'open-loop' and watched the meter
showing beam current rise.  After an hour or so when it appeared to have
settled,  (I was too excited to wait the recommended three) switched to
'OPER' and pressed the reset button.   The joy when the green light came on
!   A working Cs standard, recovered as scrap from a skip.   The light went
off after an hour, but pressing the button made it come back on, and it
stayed on from then on.

Further studying the manual, and vaguely knowing that unit's history and
politics surrounding the original owning organisation, (don't ask, I won't
say)  suggested there could actually  be a fair bit of life left in the
tube - beam current certainly suggested so.The internal NiCd batteries
were completely dead and had a few green crystals on them, so I removed the
whole battery and its charging circuitry, substituted an LM317 regulator
set for 27.2V and used a pair of (old second hand) lead acid gel cells as
backup instead.   And there it sits to this day, on standby
continuously for over 20 years with the Cs switched on when wanted.
 Typically it only needs 35 - 45 minutes warm up, so I allow 1.5 - 2 hours
before any serious tests that need full accuracy.   Ironically, it's been
running for so long the only things to have failed have been my backup gel
cells - floated in series at 27.2V, one set bulged alarmingly after some 13
years, and another pair died such that it couldn't hold-up even standby for
more than about 15 minutes when mains went off.   I replaced those only two
weeks ago.

The only thing I've never tried is calibrating out local magnetic field
using Zeeman lines.   Not having the Cs running continuously, I suspect
this would be a pointless exercise  anyway, and the loss of a few parts in
10^-13 don't over-worry me.


Andy
www.g4jnt.com



On Wed, 2 Dec 2020 at 14:43, paul swed  wrote:

> Morris
> I do see that of the 3 HP5061s the results are different and do know each
> tube leaks or internally emits stuff. But as you say maybe the metering is
> off. It definitely trips out at 40ua.
> I have my units that pulse like that and then settle down as the tube
> clears.
> But its hard to explain that if a unit is pumped down how quickly it
> pollutes again.
> Wondering if as an example the getter just releases its captured crud when
> the power is removed. That way you are always pumping down mostly the same
> stuff.
> Just very curious.
> Regards
> Paul
> WB8TSL
>
>
> On Wed, Dec 2, 2020 at 6:23 AM  wrote:
>
> > I think there's quite a bit of variation in leakage rates between
> > individual
> > physics packages, and there's also variation in the accuracy of the
> > metering. I recently started up my spare 5061A after over a year in
> > storage.
> > The Ion current meter showed zero with the Cs off but about 40 in the
> Open
> > Loop position. I tried connecting an external +3500V supply through a
> > microammeter as described in the manual and that showed less than 10 uA.
> > The
> > unit kept trying to start and pulsed for about 12 hours at a peak reading
> > of
> > 40 and then settled down nicely to a zero reading and hasn't missed  a
> beat
> > since.
> >
> > I have a spare tube sitting here that hasn't been powered up for several
> > years. It was removed from a junked 5061A that wouldn't start at all but
> > after the unit was parted out some failed caps were found in one of the
> > modules that could have explained the fault. I plan to try it on the
> bench
> > with the +3500 V supply and microammeter but I don't know whether I can
> > trust 

Re: [time-nuts] HP5065a cfield issue

[Bob kb8tq]

Hi

Ok, if the synth is off the “suspect” list …. *and* it’s a good solid lock.

Back to the C field. 

If it jumped 4x10^-11, that’s a very different thing than jumping 2x10^-9. 
Finding
the “source” of a 0.04 ppb shift is going to be a lot harder than finding a 2 
ppb
gotcha. Best to nail down the shift first …

Suspects for a small shift: 

There are a *lot* of parts (like electrolytic caps) in the voltage regulator 
circuit.
That feeds the C field current source and the rest of the system. A quick check 
of the 20V supply might help narrow that a bit. 

Suspects for a large shift:

Just like the heater windings, it is at least possible that the mag field 
winding
shorts out in some way. An ohm meter check with both sides of the winding 
disconnected ( so floating winding to ground / case ) would be the first step 
in that investigation …

Yes, there are a lot of other things that could go on that list …

Bob

> On Dec 2, 2020, at 9:14 AM, paul swed  wrote:
> 
> Hello to the group.
> Last night I dug further into the 5065 along with a lot of reading.
> The synth is producing the correct frequency according to the charts here and 
> in the manual.
> I also now see that any logic I may have assumed about the thumbwheel 
> switches is completely wrong. 
> The test tonight will actually use some different numbers. As an example the 
> switch should be 8714 the next increment is actually 8333 according to the 
> manual. So want to see what that actually does.Likewise there is a number on 
> the other side of 8714.
> But none of this explains why the system jumped at least 4 X E-11 (Or is that 
> 40?) after years of only very small minor division changes.
> Regards
> Paul
> WB8TSL
> 
> On Tue, Dec 1, 2020 at 5:34 PM Poul-Henning Kamp  > wrote:
> > To make any sense at all out of the synthesizer settings, you need the 
> > magic table in
> > the manual. They are very random and not all settings actually work ( = 
> > produce a 
> > stable output). 
> 
> A few of the entries have very much longer moduli than the rest,
> and those will probably be less stable for that reason.
> 
> I suspect the published list was tweaked to ensure even-ish coverage.
> 
> I once hacked a small python script (attached) to reproduce the table
> from the manual, here is the output from it:
> 
> +---+-+
> | Thumb   Offset Freq   |  ThumbOffset Freq   |
> +---+-+
> | 0001  -213.719 5314955.00 |  9348  -1000.603 5314417.19 |
> | 0002  -199.087 5314965.00 |  7885   -995.309 5314420.81 |
> | 0003  -923.334 5314470.00 |  9189   -986.777 5314426.64 |
> | 0004  -616.078 5314680.00 |  9030   -977.471 5314433.00 |
> | 0005  -602.910 5314689.00 |  8871   -970.785 5314437.57 |
> | 5691  -940.723 5314458.12 |  8712   -965.767 5314441.00 |
> | 5726  -596.318 5314693.51 |  8394   -958.686 5314445.84 |
> | 5952  -191.236 5314970.37 |  7758   -950.566 5314451.39 |
> | 5980  -621.015 5314676.63 |  5691   -940.723 5314458.12 |
> | 6301  -221.040 5314950.00 |  9841   -930.036 5314465.42 |
> | 6518  -916.829 5314474.45 |  0003   -923.334 5314470.00 |
> | 6519  -784.650 5314564.79 |  6518   -916.829 5314474.45 |
> | 7013  -591.165 5314697.03 |  7472   -911.838 5314477.86 |
> | 7207   -40.474 5315073.41 |  8267   -903.497 5314483.56 |
> | 7318   -55.120 5315063.40 |  8744   -893.401 5314490.46 |
> | 7443  -408.216 5314822.07 |  8903   -888.104 5314494.08 |
> | 7472  -911.838 5314477.86 |  9062   -880.993 5314498.94 |
> | 7603  -181.446 5314977.06 |  9221   -870.970 5314505.79 |
> | 7696  -630.493 5314670.15 |  8601   -864.270 5314510.37 |
> | 7697  -430.586 5314806.78 |  9380   -855.827 5314516.14 |
> | 7698  -230.489 5314943.54 |  8919   -844.913 5314523.60 |
> | 7743  -766.959 5314576.88 |  8458   -840.524 5314526.60 |
> | 7758  -950.566 5314451.39 |  9539   -830.236 5314533.63 |
> |   -309.118 5314889.80 |  7854   -822.836 5314538.69 |
> | 7792  -492.447 5314764.50 |  8776   -817.274 5314542.49 |
> | 7854  -822.836 5314538.69 |  9237   -809.431 5314547.85 |
> | 7885  -995.309 5314420.81 |  8935   -800.433 5314554.00 |
> | 7888  -341.848 5314867.43 |  8029   -789.973 5314561.15 |
> | 7918  -731.156 5314601.35 |  6519   -784.650 5314564.79 |
> | 7919  -509.961 5314752.53 |  9698   -777.681 5314569.55 |
> | 8014  -582.532 5314702.93 |  7743   -766.959 5314576.88 |
> | 8029  -789.973 5314561.15 |  8347   -763.037 5314579.56 |
> | 8031  -322.490 5314880.66 |  8951   -754.594 5314585.33 |
> | 8142  -360.488 5314854.69 |  9253   -745.259 5314591.71 |
> | 8238  -172.783 5314982.98 |  8808   -737.036 5314597.33 |
> | 8253  -403.313 5314825.42 |  7918   -731.156 5314601.35 |
> | 8267  -903.497 5314483.56 |  9555   -723.253 5314606.75 |
> | 8333  -240.028 

Re: [time-nuts] HP5065a cfield issue

[paul swed]

Hello to the group.
Last night I dug further into the 5065 along with a lot of reading.
The synth is producing the correct frequency according to the charts here
and in the manual.
I also now see that any logic I may have assumed about the
thumbwheel switches is completely wrong.
The test tonight will actually use some different numbers. As an example
the switch should be 8714 the next increment is actually 8333 according to
the manual. So want to see what that actually does.Likewise there is a
number on the other side of 8714.
But none of this explains why the system jumped at least 4 X E-11 (Or is
that 40?) after years of only very small minor division changes.
Regards
Paul
WB8TSL

On Tue, Dec 1, 2020 at 5:34 PM Poul-Henning Kamp  wrote:

> > To make any sense at all out of the synthesizer settings, you need the
> magic table in
> > the manual. They are very random and not all settings actually work ( =
> produce a
> > stable output).
>
> A few of the entries have very much longer moduli than the rest,
> and those will probably be less stable for that reason.
>
> I suspect the published list was tweaked to ensure even-ish coverage.
>
> I once hacked a small python script (attached) to reproduce the table
> from the manual, here is the output from it:
>
> +---+-+
> | Thumb   Offset Freq   |  ThumbOffset Freq   |
> +---+-+
> | 0001  -213.719 5314955.00 |  9348  -1000.603 5314417.19 |
> | 0002  -199.087 5314965.00 |  7885   -995.309 5314420.81 |
> | 0003  -923.334 5314470.00 |  9189   -986.777 5314426.64 |
> | 0004  -616.078 5314680.00 |  9030   -977.471 5314433.00 |
> | 0005  -602.910 5314689.00 |  8871   -970.785 5314437.57 |
> | 5691  -940.723 5314458.12 |  8712   -965.767 5314441.00 |
> | 5726  -596.318 5314693.51 |  8394   -958.686 5314445.84 |
> | 5952  -191.236 5314970.37 |  7758   -950.566 5314451.39 |
> | 5980  -621.015 5314676.63 |  5691   -940.723 5314458.12 |
> | 6301  -221.040 5314950.00 |  9841   -930.036 5314465.42 |
> | 6518  -916.829 5314474.45 |  0003   -923.334 5314470.00 |
> | 6519  -784.650 5314564.79 |  6518   -916.829 5314474.45 |
> | 7013  -591.165 5314697.03 |  7472   -911.838 5314477.86 |
> | 7207   -40.474 5315073.41 |  8267   -903.497 5314483.56 |
> | 7318   -55.120 5315063.40 |  8744   -893.401 5314490.46 |
> | 7443  -408.216 5314822.07 |  8903   -888.104 5314494.08 |
> | 7472  -911.838 5314477.86 |  9062   -880.993 5314498.94 |
> | 7603  -181.446 5314977.06 |  9221   -870.970 5314505.79 |
> | 7696  -630.493 5314670.15 |  8601   -864.270 5314510.37 |
> | 7697  -430.586 5314806.78 |  9380   -855.827 5314516.14 |
> | 7698  -230.489 5314943.54 |  8919   -844.913 5314523.60 |
> | 7743  -766.959 5314576.88 |  8458   -840.524 5314526.60 |
> | 7758  -950.566 5314451.39 |  9539   -830.236 5314533.63 |
> |   -309.118 5314889.80 |  7854   -822.836 5314538.69 |
> | 7792  -492.447 5314764.50 |  8776   -817.274 5314542.49 |
> | 7854  -822.836 5314538.69 |  9237   -809.431 5314547.85 |
> | 7885  -995.309 5314420.81 |  8935   -800.433 5314554.00 |
> | 7888  -341.848 5314867.43 |  8029   -789.973 5314561.15 |
> | 7918  -731.156 5314601.35 |  6519   -784.650 5314564.79 |
> | 7919  -509.961 5314752.53 |  9698   -777.681 5314569.55 |
> | 8014  -582.532 5314702.93 |  7743   -766.959 5314576.88 |
> | 8029  -789.973 5314561.15 |  8347   -763.037 5314579.56 |
> | 8031  -322.490 5314880.66 |  8951   -754.594 5314585.33 |
> | 8142  -360.488 5314854.69 |  9253   -745.259 5314591.71 |
> | 8238  -172.783 5314982.98 |  8808   -737.036 5314597.33 |
> | 8253  -403.313 5314825.42 |  7918   -731.156 5314601.35 |
> | 8267  -903.497 5314483.56 |  9555   -723.253 5314606.75 |
> | 8333  -240.028 5314937.02 |  8522   -712.134 5314614.35 |
> | 8347  -763.037 5314579.56 |  8967   -707.335 5314617.63 |
> | 8379  -702.976 5314620.61 |  8379   -702.976 5314620.61 |
> | 8394  -958.686 5314445.84 |  9412   -695.293 5314625.86 |
> | 8397   -97.666 5315034.32 |  8681   -685.857 5314632.31 |
> | 8411  -640.485 5314663.32 |  9269   -678.277 5314637.49 |
> | 8413   -60.283 5315059.87 |  9126   -666.821 5314645.32 |
> | 8429   -22.139 5315085.94 |  8983   -658.598 5314650.94 |
> | 8458  -840.524 5314526.60 |  8697   -647.552 5314658.49 |
> | 8459  -541.900 5314730.70 |  8411   -640.485 5314663.32 |
> | 8491  -472.679 5314778.01 |  7696   -630.493 5314670.15 |
> | 8522  -712.134 5314614.35 |  5980   -621.015 5314676.63 |
> | 8556-6.016 5315096.96 |  0004   -616.078 5314680.00 |
> | 8571  -286.087 5314905.54 |  9857   -608.295 5314685.32 |
> | 8586  -572.113 5314710.05 |  0005   -602.910 5314689.00 |
> | 8601  -864.270 5314510.37 |  5726   -596.318 5314693.51 |
> | 8618  -497.231 

Re: [time-nuts] HP5061 Cesium ion pump question

[paul swed]

Morris
I do see that of the 3 HP5061s the results are different and do know each
tube leaks or internally emits stuff. But as you say maybe the metering is
off. It definitely trips out at 40ua.
I have my units that pulse like that and then settle down as the tube
clears.
But its hard to explain that if a unit is pumped down how quickly it
pollutes again.
Wondering if as an example the getter just releases its captured crud when
the power is removed. That way you are always pumping down mostly the same
stuff.
Just very curious.
Regards
Paul
WB8TSL


On Wed, Dec 2, 2020 at 6:23 AM  wrote:

> I think there's quite a bit of variation in leakage rates between
> individual
> physics packages, and there's also variation in the accuracy of the
> metering. I recently started up my spare 5061A after over a year in
> storage.
> The Ion current meter showed zero with the Cs off but about 40 in the Open
> Loop position. I tried connecting an external +3500V supply through a
> microammeter as described in the manual and that showed less than 10 uA.
> The
> unit kept trying to start and pulsed for about 12 hours at a peak reading
> of
> 40 and then settled down nicely to a zero reading and hasn't missed  a beat
> since.
>
> I have a spare tube sitting here that hasn't been powered up for several
> years. It was removed from a junked 5061A that wouldn't start at all but
> after the unit was parted out some failed caps were found in one of the
> modules that could have explained the fault. I plan to try it on the bench
> with the +3500 V supply and microammeter but I don't know whether I can
> trust the reading. If the tube in one of my functioning units fails one day
> then I'll give it a try.
>
> Morris
>
> --
> From: paul swed 
> To: Time-nuts 
> Subject: [time-nuts] HP5061 Cesium ion pump question
>
>
> During my HP 5061Cesium testing last week I was watching the ion pump
> current and am curious.
> What is the typical behavior people see on the tube after say 3 months of
> being turned off.
> With 3 units I see one that pumps doen from 8 to 2 in 40 minutes. Another
> maybe at 25 and takes 28 hours to get to 18. Just seems to be all over the
> place.
> Regards
> Paul
> WB8TSL
>
>
> --
>
> Message: 10
> Date: Tue, 01 Dec 2020 06:19:25 +
> From: "Poul-Henning Kamp" 
> To: Discussion of precise time and frequency measurement
> , paul swed 
> Subject: Re: [time-nuts] HP5065a cfield issue
> Message-ID: <86443.1606803...@critter.freebsd.dk>
> Content-Type: text/plain; charset="us-ascii"
>
> 
> paul swed writes:
>
> > Guessing far less than 3 ma. by adding up resistors.
>
> More like typical 4 mA: there is a factory select resistor in
> parallel with the current-setting resistor.
>
>
> --
> 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.
>
>
>
> --
>
> Message: 11
> Date: Tue, 1 Dec 2020 10:40:54 + (UTC)
> From: ew 
> To: time-nuts@lists.febo.com
> Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna
> Message-ID: <1292998389.3097482.1606819254...@mail.yahoo.com>
> Content-Type: text/plain; charset="utf-8"
>
> Jim, I agree. As part of my OSA 8607A GPSDO project I planned to place the
> OCXO in an aluminium box to eliminate pressure change. Step one included
> buying a separate unit to make sure the rubber gasket did do the job.
> Attached first results. Temperature does change pressure more than ambient.
> The vertical steps are the result of gentle tightening the lid, did not
> know
> how much lid had to be tightened. Now I know and have a 10 day test
> running.
> With AC running, the AC control at the other end of the house lab
> temperature stays within ! C. Today a cold front hit, no AC and temperature
> will drop more than 1 C. Taking advantage of the forecast I am extending
> the
> test for a couple more days.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Doe to the low power
> dissipation of the 8607 fan cooling is not an option but I will use the box
> , seal it and characterize the 8607 for pressure and temperature and use
> external pressure and temperature sensors for compensation once combined
> with a new generation GPSDO.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ??
>
>
>
> I'll bet pressure changes inside the "sealed" radome due to temperature
> changes are bigger than those due to local barometer changes.
>
> But an interesting thing - water vapor will go through cracks, porosity,
> that liquid water will not. The commercial success of GoreTex is an
> example of this, but cracks, o-rings that aren't quite right, etc. are
> also ways it can happen.
>
> Making a truly hermetic box is hard.
>
> >
> > -Original Message-
> > From: 

Re: [time-nuts] HP5061 Cesium ion pump question

[vilgotch1]

I think there's quite a bit of variation in leakage rates between individual
physics packages, and there's also variation in the accuracy of the
metering. I recently started up my spare 5061A after over a year in storage.
The Ion current meter showed zero with the Cs off but about 40 in the Open
Loop position. I tried connecting an external +3500V supply through a
microammeter as described in the manual and that showed less than 10 uA. The
unit kept trying to start and pulsed for about 12 hours at a peak reading of
40 and then settled down nicely to a zero reading and hasn't missed  a beat
since.

I have a spare tube sitting here that hasn't been powered up for several
years. It was removed from a junked 5061A that wouldn't start at all but
after the unit was parted out some failed caps were found in one of the
modules that could have explained the fault. I plan to try it on the bench
with the +3500 V supply and microammeter but I don't know whether I can
trust the reading. If the tube in one of my functioning units fails one day
then I'll give it a try.

Morris
 
--
From: paul swed 
To: Time-nuts 
Subject: [time-nuts] HP5061 Cesium ion pump question


During my HP 5061Cesium testing last week I was watching the ion pump
current and am curious.
What is the typical behavior people see on the tube after say 3 months of
being turned off.
With 3 units I see one that pumps doen from 8 to 2 in 40 minutes. Another
maybe at 25 and takes 28 hours to get to 18. Just seems to be all over the
place.
Regards
Paul
WB8TSL


--

Message: 10
Date: Tue, 01 Dec 2020 06:19:25 +
From: "Poul-Henning Kamp" 
To: Discussion of precise time and frequency measurement
, paul swed 
Subject: Re: [time-nuts] HP5065a cfield issue
Message-ID: <86443.1606803...@critter.freebsd.dk>
Content-Type: text/plain; charset="us-ascii"


paul swed writes:

> Guessing far less than 3 ma. by adding up resistors.

More like typical 4 mA: there is a factory select resistor in
parallel with the current-setting resistor.


-- 
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.



--

Message: 11
Date: Tue, 1 Dec 2020 10:40:54 + (UTC)
From: ew 
To: time-nuts@lists.febo.com
Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna
Message-ID: <1292998389.3097482.1606819254...@mail.yahoo.com>
Content-Type: text/plain; charset="utf-8"

Jim, I agree. As part of my OSA 8607A GPSDO project I planned to place the
OCXO in an aluminium box to eliminate pressure change. Step one included
buying a separate unit to make sure the rubber gasket did do the job.
Attached first results. Temperature does change pressure more than ambient.
The vertical steps are the result of gentle tightening the lid, did not know
how much lid had to be tightened. Now I know and have a 10 day test running.
With AC running, the AC control at the other end of the house lab
temperature stays within ! C. Today a cold front hit, no AC and temperature
will drop more than 1 C. Taking advantage of the forecast I am extending the
test for a couple more days.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Doe to the low power
dissipation of the 8607 fan cooling is not an option but I will use the box
, seal it and characterize the 8607 for pressure and temperature and use
external pressure and temperature sensors for compensation once combined
with a new generation GPSDO.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ??



I'll bet pressure changes inside the "sealed" radome due to temperature 
changes are bigger than those due to local barometer changes.

But an interesting thing - water vapor will go through cracks, porosity, 
that liquid water will not. The commercial success of GoreTex is an 
example of this, but cracks, o-rings that aren't quite right, etc. are 
also ways it can happen.

Making a truly hermetic box is hard.

> 
> -Original Message-
> From: Poul-Henning Kamp 
> Sent: Sunday, November 29, 2020 11:19 PM
> To: Discussion of precise time and frequency measurement
; Art Sepin 
> Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna
> 
> 
> 
>> It's obvious from the photo that the O-Ring seal failed its purpose
>> over its many years of service. Has the unit totally failed or does the
electronic portion still function?
> 
> No, the electronics is stone dead.
> 
> To me it looks more like water ingress through micro-cracks in the
plastic-dome, and the O-ring did its job and kept that water in.
> 
> The microcracks are uniform and seem to follow the molding flow, and that
is probably to be expected in our climate:? We have a lot of humid
freeze-thaw cycles.
> 
> I wonder if buffing the radomes with car-wax would 

Re: [time-nuts] Voyager space probe question

[Andrew Rodland]

RTGs, much like solar cells, have a terminal voltage that drops pretty much 
linearly with the current you draw from them, and a "maximum power point" 
where V*I reaches a maximum (see for example page 37 and several later pages 
from https://apps.dtic.mil/dtic/tr/fulltext/u2/a057483.pdf ). As they age, the 
open-circuit voltage goes down, and so does the maximum-power current. So the 
goal with load shedding is to keep the current to a level where the RTG 
develops a sufficient voltage to make everyone happy. Exact details depend on 
what kind of regulators you have downstream (I have no clue, in Voyager's 
case).

Andrew

On Sunday, November 29, 2020 3:39:37 PM EST Jeremy Nichols wrote:
> As the RTGs aged, the Voyagers were commanded to shed parts of their load.
> Did the RTG voltage drop, was it the current-supplying capability (or both)
> and how did that affect the oscillators, if at all?
> 
> Jeremy
> N6WFO
> 
> On Sun, Nov 29, 2020 at 10:11 AM jimlux  wrote:
> > For those interested in a "typical" (hah!) TCXO spec for a space radio,
> > generically similar to the Electra UHF radios on and orbiting Mars, it's
> > attached.
> > 
> > The excessively precise frequency (49.244. MHz) is because it
> > matched a particular channel assignment for S-band, and the idea was to
> > have the PN code (which is about 3 MHz, proportional to the carrier) be
> > exactly 16 samples long.
> > 
> > This is in pre "we can trust an NCO/DDS" days.  When it takes years to
> > build your spacecraft, ordering a crystal with a 24 month lead time to
> > get the frequency "just right" isn't considered a problem. Historically,
> > the SDST used a VCXO with a crystal at the frequency at 8*f0, where f0
> > is about 9.xx MHz, and multiplies up by 880 to the transmit frequency
> > between 8.4-8.45 GHz.
> > 
> > Today, we use 50 or 100 MHz oscillators (Electra uses 24 MHz, but it's
> > an older design) and synthesize the carrier with a DDS feeding a PLL.
> > For instance, the Iris cube-sat transponder uses a 50 MHz oscillator,
> > and that drives a DDS running at 20 MHz, which is multiplied up in an
> > integer N PLL to the carrier frequency.
> > 
> > This is because the missions are shorter development time, and we don't
> > want to have to know the frequency until after the radios are built (or
> > at least, the oscillators are ordered). For Iris, there were 7 of them
> > built for the Artemis-1 mission, and the frequencies are all over the
> > space science X-band allocation.
> > 
> > The SDST and older used a DRO as the microwave oscillator, and they just
> > don't have the tuning range needed to cover 50-100 MHz tuning range (and
> > lordy, we tried a bunch of techniques) - not do mention that DROs have
> > noticeable microphonics because the physical cavity is part of the
> > resonator.
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