Re: [time-nuts] GPS disciplined OXCO

[Taka Kamiya via time-nuts]

Just about everybody on this list has extensive experience on GPSDO.  Once it 
gets going, OCXOs are very reliable.  I haven't had one fail, yet.  There are 
plenty available on eBay, too, and if one is not too critical, anything will do 
for general lab use.  

If this is your first time, my recommendation is a T-bolt.  While they may not 
be the cheapest, there are plenty to choose from.  There are vast amount of 
knowledge and experiences available.  Well supported and no surprises.  With 
add-on display board and all that, you can make yourself a nice self-contained 
unit for not much more than $300, depending on how well stocked your junk box 
is.
Personally, I tend to avoid ready-built eBay stuff.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, September 4, 2020, 8:12:20 PM EDT, Seth - Fran Taylor 
 wrote:  
 
 Anyone have any experience with any of the GPS Disciplined. Reliability?
Etc.

 

Symmetricom 10 MHz TTL/Sine OXCO sources offered on ebay? Usually in $150 to
$300 range.

 

Not ready to sink $500 or more into a rubidium source.

 

 

Seth L Taylor

Francine S Taylor

6585 Kensington Ln

Apt 401

Delray Beach FL 33446-3020

Email: kc2w...@gmail.com  

I Phone(s): 201-787-4492 (Fran); 201-874-7915 (Seth)

Home: 561-270-2873

 

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Re: [time-nuts] Quartzlock E10-MRX

[Taka Kamiya via time-nuts]

Will you elaborate on fan?  Just about everything I've read, use of fan was 
discouraged.  Natural convection over heat sink fins were recommended.  I've 
done limited testing.  When fan cooling, indeed temperature will go down, but 
current consumption stays higher indicating heating is often conducted to keep 
it hot inside.  How do I reconciliate these opposing conditions in actual use?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Tuesday, September 1, 2020, 2:08:04 PM EDT, Bob kb8tq  
wrote:  
 
 Hi

In this case there may not be much that can be done. In the more general case
( = a unit with a surface that mates to a heatsink) , it’s well worth doing 
something. 

I have an unfortunate lot of empirical evidence (on FRK’s and LPRO’s ) showing 
that 
a “no heatsink” setup is one with a short life. With no heatsink, a couple of 
years is
doing well on a surplus unit. With a heatsink, > 10 years is quite possible. 

How much heatsink? Is the next question. If you can get the baseplate down into 
the
40’s (C) that’s doing pretty well. A fan plus heatsink may be needed to get 
this done.
If a fan is involved, mag field could become an issue ( = Rb’s are sensitive to 
mag
field, as the fan speed changes the field *may* change). 

=

Indeed this is not always the official word from the Rb manufacturers. I’ve 
spent
considerable effort drinking beer with many of their marketing and engineering 
guys. The conversation is not *quite* the same when marketing it not at the 
table. 
I believe that they simply don’t have a body of long term data “in house” to 
study.

The fact that I’m not the only one seeing Rb’s die early is backed up on eBay. 
From time to time, you can find pretty large batches of “for parts” Rb’s. Date 
codes
often are *not* very far back in time.  

If they get cheap enough (like ~ $30) they can be fun to play with. You can 
pretty 
quickly work out that the electrolytic caps are the most likely failure points. 
Cap
swap outs may only fix 2/3 of them, but it’s quick and easy. You now have a pile
of $45 Rb’s ….

Bob




> On Sep 1, 2020, at 9:23 AM, Matthias Welwarsky  wrote:
> 
> On Dienstag, 1. September 2020 14:25:31 CEST Richard Katsch wrote:
>> Many thanks Matthias,Hugh.
>> 
>> The case doesn’t seem to have any direct method of fastening to a heatsink
>> but something can be arranged I’m sure. The manufacturer’s documents don’t
>> suggest anything. They do say that the base temperature can be up to 85
>> degrees C which seems awfully hot.
>> 
>> I haven’t measured the temperature other than a finger test that indicates
>> that more than 5 secs is uncomfortably hot. At that point I switched it off.
> 
> I wouldn't say "uncomfortably hot" is a cause for alarm. The lamp housing in 
> the LPRO-101 runs at 100°C, the resonance chamber at roughly the same temp. 
> You need Rb vapor at around that temperature (if that Rb is a traditional 
> construction) for the system to work.
> 
> Anyway, what else can you do? If it's broken, the chances of repairing it are 
> slim. If it works, no way to find out if it's in spec unless you run it. Just 
> watch for smoke ;)
> 
> BR,
> Matthias
> 
>> 
>> Best regards
>> Richard
>> 
>> On Tue, 1 Sep 2020 at 19:02, Hugh Blemings  wrote:
>>> Hiya,
>>> 
>>> 
>>> I'd wondered this also - my (limited) experience of Rbs are the
>>> 
>>> LPROs and they definitely need a heatsink (I have a nice story to
>>> 
>>> share about getting some made one day which I must write up, but I
>>> 
>>> digress)
>>> 
>>> 
>>> Curious, I dug around a bit and only data I can find is a two
>>> 
>>> pager on the manufacturer website -
>>> 
>>> https://www.quartzlock.com/product/Rubidium/rubidium-oscillators/E10-MRX
>>> 
>>> 
>>> The packaging itself doesn't appear to be designed with
>>> 
>>> heatsinking in mind, but perhaps there is an implicit expectation
>>> 
>>> of convection cooling at least to keep it manageable ?
>>> 
>>> 
>>> Any idea what case temperature you're seeing @Richard ?
>>> 
>>> 
>>> 
>>> 
>>> Cheers,
>>> 
>>> 
>>> Hugh
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> On 1/9/20 5:01 pm, Matthias Welwarsky
>>> 
>>> wrote:
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> On Dienstag, 1. September 2020 07:15:34 CEST Richard Katsch wrote:
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Hello All,
>>> 
>>> I have acquired a Quartzlock E10-MRX Rb 10 MHz standard. It appears to
>>> lock
>>> 
>>> and produce a nice sine wave that stays in phase with my Trimble Tbolt for
>>> 
>>> a time which exceeds my attention span!!!
>>> 
>>> It does however get hot in operation. As this is my first experience with
>>> a
>>> 
>>> Rb standard I don’t know whether this is normal or indicates that I need a
>>> 
>>> heat sink.
>>> 
>>> Any comments would be appreciated.
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> They're supposed to run hot, but excess temperature will degrade the
>>> stability
>>> 
>>> and shorten the lifetime of the electronics. It's hard to recommend what
>>> 
>>> heatsink they 

Re: [time-nuts] Satelles PNT from Iridium satellites

[Taka Kamiya via time-nuts]

I've done some quick research.  I do not see timing as one of the services 
provided.  I wonder if it can be achieved by just listening into what's already 
transmitted (like GPS) and do some math on our side. 

On more broader sense, was GPS originally designed to provide timing service?  
Or is it a byproduct of needing to measure location and speed, thus it needed a 
constant signal, and that using it to sync reference signal is just an 
ancillary and after-thought use cases?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, August 9, 2020, 9:21:23 PM EDT, Bob kb8tq  wrote: 
 
 
 Hi



> On Aug 9, 2020, at 7:03 PM, Tom Van Baak  wrote:
> 
> Hi Stu,
> 
> There's no problem with a semi-commercial posting here. You've been a member 
> for a decade and frequent contributor plus the subject matter is exactly 
> on-topic. So thanks for posting.
> 
> I spent a while on your web site and didn't uncover a trove of white papers. 
> If you could post some URL's that would be appreciated. You don't have to 
> worry about being less accurate than GPS. I mean, there are often far more 
> important factors than nanosecond precision.

To that point ( as accurate as GPS ) ….. GPS is simply a convent comparison 
system. Saying that 
this or that is better or worse at this or that tau is *not* the same as saying 
it has more or less value. 
It’s simply a system that is out there to be compared to.

Bob


> You didn't mention pricing; it's hard to imagine it's as free as GPS so that 
> seems like another disadvantage to me.
> 
> Your comment about fewer satellites is spot on. That will be taken care of if 
> you give SpaceX / Starlink a call and join that bandwagon. There are already 
> 597 Starlink [1] satellites up there vs. 82 Iridium [2] satellites, yes?
> 
> If you have entry-level / hobbyist grade evaluation kits I'm sure a number of 
> us would be very interested to try it out.
> 
> Thanks,
> /tvb
> 
> [1] https://en.wikipedia.org/wiki/Starlink
> 
> [2] https://en.wikipedia.org/wiki/Iridium_satellite_constellation
> 
> 
> On 8/9/2020 2:53 PM, Stewart Cobb wrote:
>> Taka Kamiya and Forrest Christian both asked recently about the alternative
>> satellite PNT system using the Iridium satellites. That system was
>> developed by my company, Satelles. It has been commercially available for
>> more than a year now.
>> 
>> The biggest advantage is that our signal is at least 30 dB stronger than
>> GNSS signals (the exact numbers depend on whether you're talking to
>> engineering or marketing :). You can easily get a usable signal in deep
>> jungle, or a data center in the middle of a building's basement, or even
>> inside a locked shipping container. The stronger signal is correspondingly
>> more difficult to jam or spoof than GNSS, and our signal has anti-spoofing
>> features as well.
>> 
>> The biggest disadvantage is that it is not quite as accurate as GPS,
>> because there are fewer satellites in view at any given time.
>> 
>> I don't want to quote exact timing numbers here, because they depend a lot
>> on system integration details, but you can easily steer an OCXO within a
>> few hundred nanoseconds of USNO time. With a rubidium, you can do
>> considerably better.
>> 
>> If you want to know more, our website is www.satellesinc.com.
>> 
>> (If this message has been too commercial, I apologize in advance. The
>> boundary between information and salesmanship is not always sharp.)
>> 
>> Cheers!
>> --Stu
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[time-nuts] Used VFD available for HP53132A (from USA)

[Taka Kamiya via time-nuts]

I just updated my HP53132A with new VFD.  The old one is available for just 
shipping cost.  I'm in Florida USA.The display is a bit dark as they are 
original to the units, but they are functional.  I have two of them.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] eLORAN in the Antipodes ? (was: Re: eLORAN will be on the air GRI 99600)

[Taka Kamiya via time-nuts]

Wouldn't such a long distance propagation result in less precision?  The signal 
will have to go through distance through air which isn't constant in dialectic 
values.  Wouldn't it be problematic for level of accuracy we pursue?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, August 7, 2020, 9:14:23 AM EDT, paul swed  
wrote:  
 
 I believe South Korea is indeed building new eLORAN chains. I have seen
mention of it.
With respect to distance In the US I could occasionally receive the
European West chain at night and in the winter. Thats about 3200 miles. It
would also be by skywave so that deteriorates accuracy.
Regards
Paul
WB8TSL

On Fri, Aug 7, 2020 at 5:26 AM Björn  wrote:

> Are not South Korea are building one? new eLoran chain?  Are they
> transmitting? But don’t underestimate the distances from south east Asia to
> the far side of Australia.
>
> /Björn
>
> Sent from my iPhone
>
> > On 7 Aug 2020, at 10:24, Poul-Henning Kamp  wrote:
> >
> > 
> > Hugh Blemings writes:
> >
> >> Been following this thread with the usual mixture of joy, awe and
> wonder
> >> (truly!) - fantastic stuff :)
> >>
> >> My read of the situation is that there is next to no chance of
> receiving
> >> any meaningful signal at the VLF frequencies in question down here in
> >> Melbourne - a great circle path of some 10,000 mi / 16000 km ?
> >
> > You might be able to pick out the Chinese Loran chains, I believe
> they're still up.
> >
> > (Use sdr.dh web-sdr's to find out ?)
> >
> > --
> > Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
> > p...@freebsd.org        | TCP/IP since RFC 956
> > FreeBSD committer      | BSD since 4.3-tahoe
> > Never attribute to malice what can adequately be explained by
> incompetence.
> >
> > ___
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> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
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>
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Re: [time-nuts] eLORAN will be on the air GRI 99600

[Taka Kamiya via time-nuts]

I think CDMA in this case is part of a cellular phone network, not a satellite 
system.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, August 6, 2020, 5:40:49 PM EDT, Bill Notfaded 
 wrote:  
 
 Isn't there also CDMA?  We used a EndRun Technologies system not long ago
that used a small short antenna that could be located inside and didn't
need a cable to the roof for a GPS antenna.  This was handy for rooms that
couldn't have anything penetrate the walls at all.  It was a good reference
and ntp server we used for years that only used time reference from CDMA
satellites.

Bill

On Thu, Aug 6, 2020, 1:43 PM jimlux  wrote:

> On 8/6/20 9:17 AM, Taka Kamiya via time-nuts wrote:
> > Someone in this thread mentioned "at least 2 satellite time and
> frequency solutions" exists already.  I only know of GPS (GNSS)
> constellations.  What's the other?
>
> Transit?
>
> I don't believe they are still operational, though.
>
>
> I wonder if one might be able to pick up time/frequency from a
> commercial TV broadcast transponder.  The transponders on the satellite
> are typically bent pipes (for C-band anyway), I would assume that the
> uplinks may or may not have stability comparable to terrestrial broadcast.
>
> One problem is, of course, that the satellites aren't in a stable
> location (at least on a "meters" scale) - but one could certainly do
> "common view" kinds of time transfer.
>
>
>
>
> >
> > ---
> > (Mr.) Taka Kamiya
> > KB4EMF / ex JF2DKG
> >
> >
> >      On Thursday, August 6, 2020, 12:01:27 PM EDT, paul swed <
> paulsw...@gmail.com> wrote:
> >
> >  Magnus
> > Its honestly by luck that I know anything. From the bits I have read
> Europe
> > seems far closer to eLORAN then we are. Perhaps 6 months ago the US
> > performed a series of tests 2 eLoran solutions and something like 6 or
> more
> > satellite solutions. I know the old Iridium satellites were in the tests
> > and some other LEO satellites.
> > But thats about it.
> > What we need is a cheap SDR LORAN C sniffer. Low power runs 24 X 7 and
> > turns a LED on if the stations active.
> > Oh well another project in the someday pile.
> > Regards
> > Paul
> > WB8TSL
> >
> > On Thu, Aug 6, 2020 at 2:42 AM Magnus Danielson 
> wrote:
> >
> >> Hi Paul,
> >>
> >> I only ask as you seem to track this thing the best here on time-nuts,
> >> as far as I have seen, such that it is your emails that keeps me best up
> >> to date with the progress.
> >>
> >> Cheers,
> >> Magnus
> >>
> >> On 2020-08-05 19:21, paul swed wrote:
> >>> Hi Magnus been a while since have emailed.
> >>> Its one site that was a test transmitter. Its in New Jersey, USA.
> >>> The goal of the testing I believe is to establish the viability of an
> >>> alternate PNT reference to GPS. Additionally the ability to communicate
> >>> some level of message broadcast. This should be identical to proposals
> I
> >>> have heard of in Europe.
> >>> But I have no direct relationship to any of this. Like you, a very
> >>> interested observer and hope that eLORAN wins the battle.
> >>> Unfortunately there are many alternate proposals such as using other
> >>> satellites. Hmmm if I wanted to advance my career in the Air Force or
> >> Space
> >>> Force (Yes thats actually real now).
> >>> Would I select the lowly reliable as heck eLORAN at sub $100 M/year to
> >>> operate. Or the glorious space based proposals in $B region. Never mind
> >>> that at least 3 countries now have demonstrated killer satellites.
> >>> Sorry for that editorial.
> >>> Regards
> >>> Paul
> >>> WB8TSL
> >>>
> >>> On Wed, Aug 5, 2020 at 11:04 AM Magnus Danielson 
> >> wrote:
> >>>
> >>>> Hi,
> >>>>
> >>>> Do you know that they would do test with two actual transmitter sites?
> >>>>
> >>>> Cheers,
> >>>> Magnus
> >>>>
> >>>> On 2020-08-05 16:00, paul swed wrote:
> >>>>> Hello to fellow time nuts.
> >>>>> Warm up those old Austrons. eLORAN out of New Jersey has been on the
> >> air
> >>>>> intermittently prior to a test run next week. Due to the storm they
> >> have
> >>>>> lost power and should have it back today or tomorrow.

Re: [time-nuts] eLORAN will be on the air GRI 99600

[Taka Kamiya via time-nuts]

Someone in this thread mentioned "at least 2 satellite time and frequency 
solutions" exists already.  I only know of GPS (GNSS) constellations.  What's 
the other?  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, August 6, 2020, 12:01:27 PM EDT, paul swed 
 wrote:  
 
 Magnus
Its honestly by luck that I know anything. From the bits I have read Europe
seems far closer to eLORAN then we are. Perhaps 6 months ago the US
performed a series of tests 2 eLoran solutions and something like 6 or more
satellite solutions. I know the old Iridium satellites were in the tests
and some other LEO satellites.
But thats about it.
What we need is a cheap SDR LORAN C sniffer. Low power runs 24 X 7 and
turns a LED on if the stations active.
Oh well another project in the someday pile.
Regards
Paul
WB8TSL

On Thu, Aug 6, 2020 at 2:42 AM Magnus Danielson  wrote:

> Hi Paul,
>
> I only ask as you seem to track this thing the best here on time-nuts,
> as far as I have seen, such that it is your emails that keeps me best up
> to date with the progress.
>
> Cheers,
> Magnus
>
> On 2020-08-05 19:21, paul swed wrote:
> > Hi Magnus been a while since have emailed.
> > Its one site that was a test transmitter. Its in New Jersey, USA.
> > The goal of the testing I believe is to establish the viability of an
> > alternate PNT reference to GPS. Additionally the ability to communicate
> > some level of message broadcast. This should be identical to proposals I
> > have heard of in Europe.
> > But I have no direct relationship to any of this. Like you, a very
> > interested observer and hope that eLORAN wins the battle.
> > Unfortunately there are many alternate proposals such as using other
> > satellites. Hmmm if I wanted to advance my career in the Air Force or
> Space
> > Force (Yes thats actually real now).
> > Would I select the lowly reliable as heck eLORAN at sub $100 M/year to
> > operate. Or the glorious space based proposals in $B region. Never mind
> > that at least 3 countries now have demonstrated killer satellites.
> > Sorry for that editorial.
> > Regards
> > Paul
> > WB8TSL
> >
> > On Wed, Aug 5, 2020 at 11:04 AM Magnus Danielson 
> wrote:
> >
> >> Hi,
> >>
> >> Do you know that they would do test with two actual transmitter sites?
> >>
> >> Cheers,
> >> Magnus
> >>
> >> On 2020-08-05 16:00, paul swed wrote:
> >>> Hello to fellow time nuts.
> >>> Warm up those old Austrons. eLORAN out of New Jersey has been on the
> air
> >>> intermittently prior to a test run next week. Due to the storm they
> have
> >>> lost power and should have it back today or tomorrow.
> >>> The intention will be on the air operation till the 20th. That's a long
> >>> run. Nice.
> >>> Seems the Austron 2100s can be had for reasonable money these days
> also.
> >>> Enjoy.
> >>> Paul
> >>> WB8TSL
> >>> ___
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Re: [time-nuts] Double balanced mixer question

[Taka Kamiya via time-nuts]

I think you basically ended up with an amplitude modulated (AM) signal with 
10MHz+1 as a carrier and 1Hz as side-band.  I'll be trying something like this 
soon.  If you use low pass filter at near audio frequency, it should eliminate 
this.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, July 23, 2020, 4:50:13 PM EDT, Richard (Rick) Karlquist 
 wrote:  
 
 Are you filtering out the 10.01 MHz image?

Rick N6RK

On 7/23/2020 11:01 AM, cdel...@juno.com wrote:
> Hi,
> 
> I'm feeding 5.0 MHZ and 5.01MHz into an HP10514A mixer.
> 
> A buffer and a 12dB attenuator feed each input and a 50 Ohm buffer amp
> (10Mhz) is on the output.
> 
> I get a nice sine output but get the 1Hz as amplitude variations.
> 
> Playing with input levels I can minimize the variations but the best I
> can get is a 3.2 V P-P with a .4 V P-P amplitude modulation.
> 
> Are there mixer schemes I can use that will eliminate the amplitude
> variations?
> 
> Cheers,
> 
> Corby
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Re: [time-nuts] Just any counter external reference and discipline mode.

[Taka Kamiya via time-nuts]

I'm sorry to interject a newbie question  I changed the title to 
distinguish from rest of the conversation.

I have heard this both ways about external references - whether it's used to 
phase lock internal source and used directly after some conditioning.  Both 
come from people on this list I trust.  Limiting discussion to HP counters from 
70s to 90s, which is the truth?  Were there exceptions?  If so, why?  (I'm not 
interested in injection locking)
If some are phase locking, what does it phase lock?  Most counters have options 
on internal reference (ie. HP53132A has standard, mid performance, high 
performance, and ultra performance)  Does it phase lock the standard that's 
always there?  Or try to phase lock optional reference?  I really don't see the 
need for phase locking, as only critical element is rise time - so rather, 
signal conditioning makes sense.  

At least for me, the general public, circuit diagram is not made available for 
later models.  I have no way to tell for sure what is being done inside.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, July 13, 2020, 12:39:53 PM EDT, jimlux  
wrote:  
 
 On 7/13/20 9:02 AM, Richard (Rick) Karlquist wrote:
> 
> 
> On 7/13/2020 6:26 AM, Wes wrote:
>> Hi Magnus,
>>
>> I did have the manual when I posed the original question but I had not 
>> delved into the cal procedure until you mentioned it.  It seems to be 
>> a bit complicated for what it does. I wonder how stable this is and 
>> how often might it need to be repeated. Why they didn't use the 
>> external reference more directly is a puzzle.
>>
>> I appreciate your time in looking into this.
>>
>> Regards,
>>
>> Wes
>>
>>
> 
> I don't know the specific engineer who designed this injection
> locking scheme, but IMHO it's a "too clever by half" sort of
> thing (and that's being charitable).  Unfortunately, I encountered many 
> examples of that in the 5334A, and other counters.  I took out around
> a dozen of these "clever" circuits in the process of replacing the
> 5334A with the 5334B.  The engineers involved were outside their
> lane as the saying goes; I actually talked to them about why they
> designed the circuit in that way.  Didn't have a valid reason IMHO.
> Just having been in that environment, I would be distrustful of the 5316 
> design for anything important application like time nuts work.
> Actually, I would be distrustful of any injection locking multiplier no 
> matter who designed it.  Unfortunately, you can't conclude that
> a design is good simply because it came out of HP.  In some ways,
> it was disillusioning to go to work for HP and see what is
> really going on.
> 

The same is true of NASA (and probably any big organization).

In most cases, there's not some rigorous process to choose the "best" 
design, often it's "the first design that works" that is selected.

Subsequent revisions will sometimes purge "clever but non-robust" 
solutions.  Technology advances will also make "couldn't work 10 years 
ago, but works now" changes, although there are plenty of examples which 
"let's do it that way, because if we change it, we have to spend time 
explaining why"


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[time-nuts] Multi-turn pot stupidity

[Taka Kamiya via time-nuts]

I'm sure experienced time-nutters won't do something like I did - because it 
was stupid.  But I'd like to share this nevertheless.

I need a multi-turn pot and I bought a cheap clone from Amazon - because it was 
cheap and delivery was next day.  It came with a multi-counter knob.  Well 
it's useless.  Backlash is really bad, adjustment jumps and jumps BACK, the 
knob is unreliable, to make it worse, the fact of locking the knob changes 
position of my careful alignment.
Using things like genuine Knobpot, I get nothing like this.  It just works.
Never again.  I'll have to do it over again with quality aprts.

PS.  I get kick out of clone's creative naming!
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Incorrect date on Thunderbolt

[Taka Kamiya via time-nuts]

I'm sure it's a ROLL-OVER issue where date string buffer for date isn't long 
enough.  Only thing we can do is to correct it in software.  Most "stuff" such 
as Lady Heather knows about this and if date is unreasonable, it will correct 
it when displaying date.  No fundamental fix at GPS level, as far as I know.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, July 2, 2020, 1:53:27 PM EDT, Keith E. Brandt, MD, MPH 
 wrote:  
 
 Apologies if this equine has been flagellated, but I wasn't pulling up 
anything in searches.

I pulled my Thunderbolt out of mothballs this week. It initialized and 
started tracking satellites very nicely, but the date is showing 
'16Nov00'. The day has incremented at UTC midnight the past 2 days and 
the time is accurate.

Is this a known issue? Suggestions on correcting?

Thanks,
Keith


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[time-nuts] HP5370B parts needed

[Taka Kamiya via time-nuts]

I am trying bring HP5370B back to life.  It is missing power supply board and 
display interface board.  If anyone has a spare or a junk machine and 
interested in selling, please let me know.
Display interface board is the one second from the left.  Power supply card is 
by itself, close to banks of filter capacitors.
Thank you.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Datum 102500-001 rubidium standard

[Taka Kamiya via time-nuts]

I just did a quick look-see.
Looks like Datum is a manufacturer
102500-001 is a part numberLPRO is a model
As far as I know, LPRO and LPRO-101 are the same unit.  The exact same design 
went through several ownership.
I have a few of those.  What's nice about it is EFC (electronic frequency 
control), aka fine tuning by external potentiometer spans very narrow frequence 
range.  It makes very nice to make precise adjustment.  Anything beyond that, 
there is an internal adjustment.  I have one that has an access hole on cover, 
I have another there isn't a hole but adjustment is inside.
More than likely, you won't need to touch those.
For first time, lock could take like 10 minutes.  That time gets shorter as you 
use them and eventually, 2 minutes or so for locking.

If it was sitting unused for a while, before making any adjustment, attach it 
to a reasonable sized heat sink and run for a month or more.  Frequency will 
drift back to spec in this period.  Please do not start adjusting too soon, as 
these internal pots have limited number of time you can adjust.  (not made for 
excessive use)
By the way, you got it for free?  Lucky you!
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, June 17, 2020, 4:50:56 PM EDT, Rick Commo 
 wrote:  
 
 I was given a Datum 102500-001 Rubidium standard today.  Searcing the Web for 
a manual for this particular model yielded nothing but I did run across a 
manual in PDF form for their LPRO unit.  I read through  and suspect that it 
might be more or less applicable to the unit I have.  At least the connector 
has the same number of pins and layout.

Does anyone on the list have more info on this unit that you can share with me. 
 I grabbed it up because it was free and came with a 24V switching supply.  As 
I find time I want  to build a GPSDO for my ham shack; but this could serve in 
the interim.

The current extent of my knowledge of these devices is knowing how to spell 
rubidium and that they are/were used as secondary time sources.  I will be 
doing research over the next few days trying to come up to speed; but any 
advice from the hive-mind of this group will be appreaciated.

Cheers & thanks,
-rick, K7LOG





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Re: [time-nuts] ThunderBolt question

[Taka Kamiya via time-nuts]

In case of thunderbolt, the manufacturer openly recommends use of 75 ohm cable. 
 The manufacturer openly states not to be concerned with a mismatch.  They are 
in manuals.  


--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

  
 
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Re: [time-nuts] ThunderBolt question

[Taka Kamiya via time-nuts]

50 ohm / 75 ohm question is really irrelevant in this kind of thing.  Trmble 
itself says in manual, not to be concerned with this apparent mismatch.
In my particular case, I have a home lab standard and existing system.  I have 
an antenna and network of distribution amplifiers.  They are all 50 ohms and N 
connectors.  Some ports have BNC adapters attached.  I have pretty much 
standardized everything to SMA, N, or BNC.

I boxed a power supply, T-bolt, and buffer amp in a metal case.  I bought a 
short cable (RG58) that goes from F to BNC.  On back of the case, I have BNC to 
N adapter.  I also have a few adapters that goes from F to BNC for the test 
bench.  It really doesn't matter what you use, as long as it makes a solid 
connection. 

Advantage of F connectors and RG6 are, cheap, abundant, and low loss for the 
size.  Advantage of having house standard is, less adapters and less 
headache.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, June 5, 2020, 7:22:33 PM EDT, Robert DiRosario 
 wrote:  
 
 I have a Trimble ThunderBolt GPSDO that I just received. It has an F 
connector for the antenna input, and BNC connectors for the 1 pps and 10 
MHz outputs. Is the receiver input impedance really 75 Ohms, or is it 50 
Ohms and they just used the F connector to distinguish it from the 
others? What do people do, just use a 50 Ohm antenna?

Thanks

Robert DiRosario

KA3ZYX

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[time-nuts] Answer found: HP53132A anomaly

[Taka Kamiya via time-nuts]

I hope this will be helpful to someone.  I recently had to take one to 
calibration and testing.

I have two HP53132A counters.  Recently I've noticed funny behavior when I 
tried to run self-diagnostic on Front End.  One counter always succeeds, but 
another one always fails.  The second counter succeeds if I use one particular 
cable.
I didn't get the result like this when I do "ALL" but if I do "Front End" 
individually, it happens.  There are differences between the two.  When you do 
ALL, there is no relay chattering, and it actually works without input 
connected to the reference out.  It's odd that same test behave differently.  
It may be version of firmware dependent.

So my setup was, from 10MHz in rear to a tee, coax to front input 1, tee out to 
input 2.  This always failed on this unit.  But always succeeded another unit.

I never noticed this, but THIS unit has a rear input BNC.  (never used those)  
The way it's configured, the input amp connects to front input, then branches 
off to the rear.  So if I'm using front connectors, this coax to the rear acts 
like a stub.  It causes this kind of fails.  When we connected the same except 
using REAR input, it works every time.  It is also very sensitive that it goes 
to input 1 first, then to input 2.  Backward connection also causes it to fail.

According to HP's service manual, it says when rear terminal is installed, 
performance of front terminal is not guaranteed.  

I also found out, last digit fluctuating in loop back test on this model is 
NORMAL.  53131A tends to stay very stable at 10.00.
This is not mentioned in manual.



--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] potential low-RFI power supply

[Taka Kamiya via time-nuts]

I bought one the moment information about this PS was posted here.  

Will you gentlemen come up with a testing method?  I have an audio FFT, 
spectrum analyzer up to 26.5GHz, O'scope of various kind, measuring receiver, 
frequency counters, 6 1/2 DMM and other assorted stuff to play with.  I, 
however, lack the experience and technique most of folks here have.
I'll be glad to run any test and post a result.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, May 18, 2020, 1:49:04 PM EDT, jimlux  
wrote:  
 
 On 5/18/20 10:19 AM, Joseph Gwinn wrote:
> On Mon, 18 May 2020 12:00:02 -0400, time-nuts-requ...@lists.febo.com
> wrote:
> Re: time-nuts Digest, Vol 190, Issue 30
> 
>> Message: 1
>> Date: Sun, 17 May 2020 12:53:42 -0600
>> From: Eric Scace 
>> To: Time Nuts email list 
>> Subject: [time-nuts] potential low-RFI power supply
>> Message-ID: 
>> Content-Type: text/plain;    charset=utf-8
>>
>> Pro Audio Engineering announced a sale (through Friday) on its
>> nominal 14 Vdc 4A switching supply
>> .
>> The test results
>> 
>> webpage compares noise on the DC output and noise frequency spectrum
>> under a variety of conditions with a lead-acid battery, an Astron
>> linear supply, and a variety of switching supplies from other
>> manufacturers.
>>
>> I have not used this and can?t vouch for its performance. Given
>> recent discussions here on supplies, the analysis might be
>> interesting. At least the supplier has attempted to quantify the
>> performance of its power supply and make that information available
>> to the prospective purchaser.
>>
>> It would be interesting to see comparable (or more suitable)
>> measurements made by others posted here.
> 
> Given that this power supply is intended for audio applications such as
> mixer boards, if the switching frequency exceeds say 200 KHz, none of
> the ripple spurs will matter, as they are far above the band.  Hmm.
> Unless that get too close to the sampling rate of some delta-sigma
> converter I suppose.

Actually, it's intended as a power supply for HF transceivers, so noise 
in the HF band is of interest. Especially if it's radiated from the 
power cable.

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[time-nuts] Baseline measurement with different standard. (same timebase for clock and DUT)

[Taka Kamiya via time-nuts]

I hear a term equipment noise, base line noise, and noise floor of the 
equipment all the time. I had a few concerning and unexpected result with 
recent tests so I've conducted tests of testing methods.  I'd like to verify, 
my understanding of the situation is correct.  I basically did baseline test of 
the same interval counter with different time standards.

I took an adev measurement of my time-interval counter using standard-A for 
both clock and input.I took another adev measurement using the same 
time-interval counter using standard-B for both clock and input.I repeated the 
same test with standard-C.Run time was 1 hour and interval was 1 second.  

Method of measurement was, time stamping interval measurement (OK, it was a 
TICC), clock was 10MHz and input A was fed with 1 pps from the same source.
Each represents Cesium, Rubidium, and GPSD.
My expectation was, I will get an over-lapping (right on top of each other) 
with very minor variations.  Since clock and the DUT was the same, why would 
there be any different
Surprising result (to me) was that they all started with different Adev value 
(origin) and sloped downwards at the slope -a (same value).  They were EXACTLY 
parallel from 1 second all the way to the end (which was 900 seconds but run 
time was 1 hour).  

What did I just do?  How can I make use of this graph?  Why are they all the 
same slope?  Why are they not overlapping?
I can assume one of the answers to be, clock and the TICC form an "equipment" 
and that line represents the base line FOR THAT standard.  That's as far as I 
can get.  If I can get a better explanations, I would very much like to hear 
it.  I also wonder if this would be the same situation for every counter and 
every method, but I can do that test later.
Thank you.


--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] potential low-RFI power supply

[Taka Kamiya via time-nuts]

I have an HP audio FFT that starts from sub 1Hz so I can do that when I get 
mine.  What kind of load shall I use for this?  Purely resistive load?  What 
kind of power?  Near 100%, 50% or??  I don't know off the top of head what the 
available RBW is.  It's HP3561A

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, May 17, 2020, 4:12:03 PM EDT, jimlux  
wrote:  
 
 On 5/17/20 11:53 AM, Eric Scace wrote:
> Pro Audio Engineering announced a sale (through Friday) on its nominal 14 Vdc 
> 4A switching supply 
> . The 
> test results 
>  webpage 
> compares noise on the DC output and noise frequency spectrum under a variety 
> of conditions with a lead-acid battery, an Astron linear supply, and a 
> variety of switching supplies from other manufacturers.
> 
> I have not used this and can’t vouch for its performance. Given recent 
> discussions here on supplies, the analysis might be interesting. At least the 
> supplier has attempted to quantify the performance of its power supply and 
> make that information available to the prospective purchaser.
> 
> It would be interesting to see comparable (or more suitable) measurements 
> made by others posted here.
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> 


Interesting.. It would have been nice to see spectrum analyzer plots 
from, say, 0 to 1 MHz with a much narrower resolution BW.  1 MHz/div 
with 300 kHz RBW isn't going to show the "row of discrete spurs" that 
the switchers put out.

4mV ripple isn't bad, or at least, it's better than most of the other 
switchers.  The Astron linear is given as 5mV, but the scope photo 
doesn't seem to show anything. At 5ms for the whole screen, you should 
see some variation for over the 8.33 ms ripple period.


I get that they're demonstrating the performance with a specific 
transceiver load - but I'd be interested in seeing measurements at zero, 
50%, and 100% load on a switcher.



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Re: [time-nuts] potential low-RFI power supply

[Taka Kamiya via time-nuts]

Looks promising!  I went ahead and purchased a piece.  With new switching 
supply COMPONENTS targeting audio market from various chip manufacturers, it is 
indeed a hopeful and promising development.  Now I'm wishing someone to make a 
piece one order of noise level less for "time-nuts" market.
A bit off topic but I've been playing with various time-nuts sources with 
internal regulation with various power sources, including bottom of the rung 
switchers.  (100mV +/- noise)  I'm finding perform surprisingly well.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, May 17, 2020, 2:54:28 PM EDT, Eric Scace  wrote: 
 
 
 Pro Audio Engineering announced a sale (through Friday) on its nominal 14 Vdc 
4A switching supply 
. The test 
results  
webpage compares noise on the DC output and noise frequency spectrum under a 
variety of conditions with a lead-acid battery, an Astron linear supply, and a 
variety of switching supplies from other manufacturers.

I have not used this and can’t vouch for its performance. Given recent 
discussions here on supplies, the analysis might be interesting. At least the 
supplier has attempted to quantify the performance of its power supply and make 
that information available to the prospective purchaser.

It would be interesting to see comparable (or more suitable) measurements made 
by others posted here.
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Re: [time-nuts] Power Supplies

[Taka Kamiya via time-nuts]

Similar story
I was using one of those small modules abundant on Amazon and eBay.  Buck 
converter and drop out board.  It was noisy so I put a ferrite bead on output 
side.  One worked ok.  Added another and that put the board into full 
oscillation and it outputted 37V into a DUT destroying it.  (It was set to 5v)

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, May 3, 2020, 12:26:30 PM EDT, Steve - Home  
wrote:  
 
 Thanks Ed, that was another solution I was considering. I’ve got a few LMs in 
a drawer, I’ll have to order a few LTs. 

Steve
WB0DBS



> On May 3, 2020, at 11:02 AM, ed breya  wrote:
> 
> If you have a supply with something north of 15V, and you'd like to make 12V 
> battery type voltage, it's easy to add an external solution with a low 
> dropout three-terminal regulator to take it down a bit and still get good 
> regulation. Look at LT1085 family, for example.
> 
> Ed
> 
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Re: [time-nuts] TICC / TimeLab fun

[Taka Kamiya via time-nuts]

I can concur with this.  When I have to measure 2 inputs using TICC, I always 
use lady heather for this reason.  Either that dump TICC output into a text 
file, check it first, then feed it into other tools.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, April 29, 2020, 8:33:59 PM EDT, Mark Sims 
 wrote:  
 
 Lady Heather's TICC parser does not expect alternating ABAB readings and 
handles the ABAB vs ABBA situation properly.
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Re: [time-nuts] GPS antenna splitter recommendation?

[Taka Kamiya via time-nuts]

Are you splitting power OUT OF GPSDO or are you splitting antenna into 
individual GPSDO?
Most, if not all GPSDO outputs power supply source to the antenna via the same 
connector RF signal comes in.  Simple splitters may or may not work.  There are 
GPS antenna splitters made for that.  HP/Symmetricon has 4 port device.
Symmetricom 58536A GPS 1x4 4-Way Active Antenna Signal Splitter Divider N 
Female | eBay

| 
| 
| 
|  |  |

 |

 |
| 
|  | 
Symmetricom 58536A GPS 1x4 4-Way Active Antenna Signal Splitter Divider ...

In wireless base station pplications, poor isolation can disable cell sites. DC 
power applied to the splitter is...
 |

 |

 |


If you shop around, you can find one for not much more than $100.  Beauty of 
this is, you can connect GPS to any port and only one will supply power to the 
antenna.  You can also daisy chain it.  I have 5 set up that way.





--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, April 29, 2020, 10:14:06 PM EDT, Frank O'Donnell 
 wrote:  
 
 On 4/29/20 6:01 PM, Bob kb8tq wrote:
> Here’s a few:

Bob, thanks very much for the suggestions.

Five of the seven splitters in your list appear to offer a total of two 
output ports. What I'm looking for is one that will accommodate 
(specifically) three or four ports.

Of the remaining two on the list, this one:

> https://www.ebay.com/itm/Mini-Circuits-ZN4PD1-63W-S-RF-Power-Splitter-250-6000MHz-Qty-Available-GOOD/133387795141?hash=item1f0e883ac5:g:tdoAAOSwAbxel2o~
>  
> 

has five outputs and costs $50. Probably usable, though I was wondering 
if going with additional output ports could increase possible loss? And 
also, the price isn't a show-stopper but is a little high for what I was 
hoping for.

The other one:

> https://www.ebay.com/itm/New-Mini-Circuits-ZB6PD-2-S-800-2000-MHz-Power-Splitter/114155096838?hash=item1a942c8b06:g:jNIAAOSwedNedT92
>  
> 

isn't entirely clear to me. The text says it's a three-port, but I count 
four visible connectors that look like output ports, and two more that 
might be hiding under caps. This one goes for $19.90.

Given all of that, do either of these two seem like the optimal way to 
go if I want to plug in three or four GPSDO's?

Thanks again,

Frank


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[time-nuts] Hetrodyning concept

[Taka Kamiya via time-nuts]

I have a question on heterodyining concept.
Say you have f1 and f2.  Say you have f1 <> f2.  Then the product is |f1+f2| 
and |f1-f2|.  (fundamental is not considered here)
What would happen f1 = f2?  If phase is the same, it will be 2sin(omega t).  
(amplitude doubles)  If phase is an odd multiple of pi radian different, result 
is zero.  (cancels out each other)
What I am trying to do is to first, understand this in case where f1 = f2, and 
second, mix f1 and f2 and get f3, which is a sum of f1 and f2.  Doubling won't 
do.
Can someone help me understand this?  I haven't seen discussion of cases where 
source frequencies are equal anywhere.



--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Soldering small stuffs...

[Taka Kamiya via time-nuts]

It's a very personal thing.  I have a few Optivisors and microscopes.  Thing 
about Optivisor is distortion and clarity of lenses.  Being a photography nut 
as well, those things bother me.  I also have a stereo zoom microscope 10x to 
40x and with a barrow lens at 0.5x, effectively making it 5x to 20x.  It is 
mounted on a long boom stand.  This is perfect for my needs.  5x to work, 20x 
to inspect.  

My stereo microscope is made by an Indian company, LaboMed, and cost about a 
double of some Amscope.  Despite the general reputation of Indian products, 
this is a very well made and a quality instrument.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, April 26, 2020, 1:01:46 AM EDT, Burt I. Weiner  
wrote:  
 
 I have an AM-SCOPE 7-35 magnification stereo microscope. I also have 
an OptiVisor with a 5x stereo lense that my son gave me about 10 
years ago. As nice as the microscope is, I generally wind up using 
the OptiVisor. I have to agree with you about trying to solder under 
a microscope.  It take a lot of practice.

Burt, K6OQK


At 05:38 PM 4/25/2020, Bill Notfaded wrote:
I bought some magnifying glasses with 5 sets of different power 
lenses you wear like glasses. It has built in led light and 
adjustable strap that hold it on your head off Amazon. Works great. I 
can do all small surface mount stuff with them. Plus I have my normal 
vision and hand eye coordination going that way. Soldering under a 
scope or on a video monitor is a lesson all in itself!

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
b...@att.net
K6OQK


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Re: [time-nuts] NTP server using an OCXO, GPS chip and Raspberry Pi

[Taka Kamiya via time-nuts]

I use Garmin 18 for this purpose.  It's like 80 dollars and it's smaller than a 
hockey puck.  It includes GPS, antenna, and RS232 like interface.  You MUST get 
LVD version.  USB version and PC version does not have 1 second PPS output.  
It's quite sensitive.  It's magnetic, so I stuck it on top of 18" rack and it's 
been running well for few years.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, April 24, 2020, 4:23:33 PM EDT, Bob kb8tq  wrote: 
 
 
 Hi

Assuming you can get a good sky view for the GPS / GNSS device, that’s about 
all you need. Feed it into whatever computer you decide to use and move on. The
OCXO is simply a power hungry “non contributor” in this case.

Bob

> On Apr 24, 2020, at 2:46 PM, Andreas Kempe  wrote:
> 
> Hello everyone,
> 
> I want to build an affordable quality time source for my computer
> club. I've been toying with the idea of using an oven controlled
> oscillator from Ebay for getting a reasonable (0,5 ppm frequency
> stability) 1 PPS signal and a cheap GSP chip with UART for syncing the
> time. I was thinking of running this on a Raspberry Pi with FreeBSD
> and its gpiopps driver.
> 
> Is this a reasonable setup for an affordable NTP server?
> 
> Cordially,
> Andreas Kempe
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Re: [time-nuts] GPSDO advice

[Taka Kamiya via time-nuts]

My first recommendation will be a Thunderbolt.  It's not the least expensive 
and it is not the best performing.  But the benefit of going with T-bolt is 
plenty of accessories (display board, etc) and wealth of information including 
how-to are available.  It is also supported by virtually all shareware and high 
quality GPSDO software.  

By the way, TAPR also sells a unit that takes 10MHz and generate 1 pps.  I have 
a few here and works as they claim.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, April 24, 2020, 12:57:44 PM EDT, Wes  wrote:  
 
 No, I'm not looking for advice on how to build one but what I might buy.  My 
need is strictly hobbyist (ham radio).  I currently have a Bodnar dual 
frequency 
unit, that gives me frequency and a TAPR, (Synergy Systems) that gives me 1 
pps, 
but I would like something that gives me both, with better performance 
(holdover).

The Jackson Lab FireFly-IIA  and the lookalike Symmetricom GPS-2500 both look 
interesting.  But, price and availability are elusive.  Any advice on these or 
alternatives will be appreciated.

Wes   N7WS


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Re: [time-nuts] Using speaker / earphone for PPS testing (not a question)

[Taka Kamiya via time-nuts]

Bob?  Are you making "Big Ben" out of your T-bolt?  

Really, my original post was meant to sort of show something interesting I 
happen to find.  Nothing serious.  Those really short pulse shouldn't be 
audible but most are.  I'm making a set of tools to quickly check my time 
sources.  That was for PPS.  (you know  I'm behind a rack stepping over 
wires and trying to see if pps is actually coming out?) 

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, April 22, 2020, 2:16:17 PM EDT, John Moran, Scawby Design 
 wrote:  
 
 Bob kb8tq - Wed, 22 Apr 2020 07:46:34 -0400

Said -

>
A lot also depends on what sort of voltage / power the speaker is expecting. 
If it's a high impedance voice coil gizmo things aren't going to be as easy as
with a piezo gizmo designed to work in a 1.3V battery powered greeting card. 

Where did I leave that 10KV output amplifier ?.. should be easy to find ?. :)
>

10kV may be a little excessive for normal devices and ears.

However, Texas Instruments make some rather nice piezoelectric haptic drivers 
that include an on-chip boost voltage generator that can supply up to 200v to 
drive the piezo disc ... more than enough to drive someone mad after a few 
hours of 1PPS ticking in the cellar. The device is a DRV8662 and is available 
from Digikey for $3.35. It is a small-pitch device (0.5mm) but not impossible 
to solder.

I will order a couple and see how they perform. I think I have some 4kHz 
resonant piezo discs that should ring quite nicely ... even when hit by a 
narrow pulse ... at 200v.

Data sheet here -

http://www.ti.com/lit/ds/symlink/drv8662.pdf

There are a couple of other information sheets referenced at the end of the 
data sheet.

John 


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Re: [time-nuts] Using speaker / earphone for PPS testing (not a question)

[Taka Kamiya via time-nuts]

Out of all signal source, the shortest 1 pps is PRS-10 at 10 micro second.  
T-bolt is quite short as well but I don't have a definite data.
For those, speaker method worked just fine.  I'm just sharing what I learned on 
happenstance.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, April 20, 2020, 11:05:02 PM EDT, Bill Byrom 
 wrote:  
 
 It's easy to trigger on short pulses on most oscilloscopes if you follow these 
steps:
(1) Do NOT use Auto Trigger mode. Instead use Normal trigger mode.
(2) Set the vertical coupling mode to DC.
(3) Set the vertical gain (volts/div) and offset so that the baseline (OFF 
voltage between pulses) and pulse ON voltage should both be visible on the 
vertical scale. 
(4) Set the trigger coupling mode to DC and the trigger source to the proper 
channel.
(5) Set the trigger voltage to the midpoint between the pulse OFF and ON 
voltage. 
(6) Set the trigger slope appropriately, depending on the polarity of the 1 PPS 
pulse.
(7) Many oscilloscopes have a trigger indicator LED. It should flash visibly on 
each 1 PPS signal.
(8) If you are using an analog scope which does NOT have a microchannel plate 
(which was used on the Tektronix 2467 family and a few other models), the pulse 
ON signal may be difficult to see at a fast time/div setting, even with a high 
scope intensity setting. But you can slow down the time/div of an analog scope 
to something easy to see, such as 10 ms/div. This will allow you to see a 
bright sweep each time the scope triggers, even if a short pulse can't be seen.
(9) When using a digital oscilloscope, turn on the peak detect display mode. 
This allows the oscilloscope to keep a high sampling rate even if the time/div 
is set for a moderately slow sweep.

If the 1 PPS signal is very short, you won't be able to hear it on a speaker 
with a direct connection as you describe. But you can use a pulse stretcher 
circuit (such as a 555 timer IC) to drive a LED or speaker with a long output 
pulse (such as 10 ms). If you use two 555 IC's (or a 556 dual timer IC), you 
can even configure one section as a one-shot and the other as a tone generator 
so that a beep is produced for each pulse. The 555 and 556 may be sold as  
LM555/LM556 or NE555/NE556.
--
Bill Byrom N5BB
Retired Tektronix Application Engineer

On Mon, Apr 20, 2020, at 9:25 PM, Taka Kamiya via time-nuts wrote:
> Maybe everyone but I knew, but I just did this and found it useful.
> 1 pps signal from some GPS are notoriously narrow and difficult to sync 
> on and see on scopes.  LED will barely light if some kind of stretcher 
> is not used.  If your purpose is ONLY to see if it's there or not, hook 
> up a small speaker, earphone, amplified or not, and you can hear the 
> tick-tick sound.  
> 
> I like DIYing and many times, I wonder if pps distribution circuit is 
> working.  I can tell a very short pulse that will barely register on 
> LED is clearly audible.
> I thought I'd share.
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
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[time-nuts] Using speaker / earphone for PPS testing (not a question)

[Taka Kamiya via time-nuts]

Maybe everyone but I knew, but I just did this and found it useful.
1 pps signal from some GPS are notoriously narrow and difficult to sync on and 
see on scopes.  LED will barely light if some kind of stretcher is not used.  
If your purpose is ONLY to see if it's there or not, hook up a small speaker, 
earphone, amplified or not, and you can hear the tick-tick sound.  

I like DIYing and many times, I wonder if pps distribution circuit is working.  
I can tell a very short pulse that will barely register on LED is clearly 
audible.
I thought I'd share.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] LightSquared is back now called Ligado

[Taka Kamiya via time-nuts]

The original article said 9.8dBW.  I guess 10 WATTS?  Kind of unusual unit 
expression

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, April 17, 2020, 4:38:36 PM EDT, Scott McGrath 
 wrote:  
 
 That was +9.8 on the terrrestrial microcell transmitters,

Yes this seems to have been sold with the assurance that the magic brickwall 
filters with 100db/octave slope will be included in every one.

But the asian manufacturer of said devices will neglect to include them and 
juice the power a wee bit to say +23...    

Of course this will hose every GPS system for miles around and for those of us 
who fly our multi thousand investment in ADS-B will be rendered useless as the 
ADS-B still uses L1.    In our club’s Cessna 172 the new ADS-B in/out compliant 
radio stack was 20,000 as we are close to a lot of controlled airspace.


  I dropped a note to AOPA on this.  Because remember the entire airway system 
is now supposed to be managed by aircraft exchanging position, bearing altitude 
and rate of climb dynamically to each other and ground stations instead of 
todays radar based system.

And say goodbye to our GPSDO’s

On Apr 17, 2020, at 2:59 PM, Bob kb8tq  wrote:

Hi

Was that +9.8 or -98 dbm ? :)

At -98 they probably *could* coexist with GPS. Not real clear how well there
system would work at that level though. 

Bob

> On Apr 17, 2020, at 1:37 PM, Scott McGrath  wrote:
> 
> Supposedly lowering Tx power on terrestrial network from +23 DBm to +9.8 DBm 
> will make everything better.  Ajit Pai is listening only to carriers and 
> ignoring DoD who is stating it will significantly degrade and/or make useless 
> the GPS system.  
> 
> Not to mention ADS-B which was installed at great expense by the private and 
> commercial aviation systems. And is totally dependent on the GPS segments 
> most affected by Ligado
> 
> Read and weep
> 
> https://arstechnica.com/tech-policy/2020/04/fcc-to-approve-5g-network-despite-military-saying-it-will-harm-gps/
> 
> 
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Re: [time-nuts] Phase measurement of my GPSDO

[Taka Kamiya via time-nuts]

Bob, Tobias, et al

TICC (TAPR) isn't problem free either.  It has a tendency to get TimeLab 
confused on data from port A and port B.  The data stream has identifier on 
them but TimeLab discards it.  Then it expects A and B comes alternately.  I 
communicated with both developers but for time being, the solution is to record 
the data and inspect. 

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Tuesday, April 14, 2020, 7:48:34 AM EDT, Bob kb8tq  
wrote:  
 
 Hi

If the phase slips are “well behaved” they can be handled. The problem 
with a dual channel setup is that they are often not well behaved.  The
period is 100 ns so a frequency drift of 1 ppb will put you in trouble in 
under 2 minutes. 

The only real answer is to do it properly and time tag the two outputs. 
Any other approach will get you yelling and screaming at the test set. 
Playing with two counters and not time tagging is in the “yelling and 
screaming” category as well. 

Get a TAPPR TICC if you really want to do a DMTD. 

Of course you *could* just use a single mixer. That works fine with the 
counter you already have. It will give you an A to B test just like a 
DMTD. The only limitation is the need to tune at least one of the oscillators 
in each pair. 

There is no requirement that you tune only one. If both are tunable, 
you could tune one to the high end of its range and the other to the low end. 
With most OCXO’s, there is plenty of tune range. 

Bob

> On Apr 14, 2020, at 2:23 AM, Tobias Pluess  wrote:
> 
> Hey Bob
> 
> ok now I see your point! you talk about the phase spillovers. Timelab and
> also Stable32 can correct for them, so it shouldn't be a problem, right?
> 
> But I agree, if you cannot correct for the spillovers it becomes even more
> difficult.
> 
> 
> Tobias
> 
> On Tue., 14 Apr. 2020, 01:38 Bob kb8tq,  wrote:
> 
>> Hi
>> 
>> The gotcha with using a conventional counter (as opposed to a time tagger)
>> is that you never know when things are going to “slip” past each other.
>> When they
>> do you get a major burp in your data. Bill’s setup is running a time
>> tagger ….
>> 
>> ( = It runs an internal time count, each edge gets “labeled” with a
>> precise time
>> stamp that is good to nanoseconds or picoseconds. A Time Interval Counter
>> simply measures the time between edges. That sounds like the same thing,
>> but
>> it’s not quite ….)
>> 
>> 
>>> On Apr 13, 2020, at 6:11 PM, Tobias Pluess  wrote:
>>> 
>>> Hi Bob
>>> 
>>> Riley suggests to use a single TIC
>>> 
>>> http://wriley.com/A%20Small%20DMTD%20System.pdf
>>> 
>>> when you look at the block diagram Fig. 4, you can see that one TIC
>> allows
>>> to compare two oscillators.
>>> I don't know exactly how, though :-)
>> 
>> The gotcha with using a conventional counter (as opposed to a time tagger)
>> is that you never know when things are going to “slip” past each other.
>> When they
>> do you get a major burp in your data. Bill’s setup is running a time
>> tagger ….
>> 
>>> 
>>> OK and I see your point on the 8663. I will try to use another reference!
>>> I definitely didn't keep mine on for a long time. I didn't use the signal
>>> generator for a while now, so it was unplugged for a few months. I assume
>>> that's far from optimal for the 10811's stability.
>> 
>> Best approach is to mount your reference off on it’s own and just power
>> it. That way
>> you don’t wear out all the guts of a fancy piece of gear.
>> 
>> Bob
>> 
>>> 
>>> 
>>> Tobias
>>> 
>>> 
>>> 
>>> On Mon., 13 Apr. 2020, 23:53 Bob kb8tq,  wrote:
>>> 
 Hi
 
> On Apr 13, 2020, at 5:06 PM, Tobias Pluess  wrote:
> 
> Hi Bob
> awesome, thanks! of course it is 1e6, not 1e7, I got a mistake :-)
> 
> Maybe I have some good OpAmps for this purpose in my box. I will try
>> it!
 of
 
 You need something that is quiet (like the OP-37) and has a pretty good
 slew
 rate. Past that, there are a lot of candidates. The TI OPA-228 family is
 one.
 
> course I saw that my setup was not ideal as there was a bit of noise on
 the
> signals which I guess does lead to some jitter in the trigger circuit
>> and
> therefore decreases my measurement noise floor.
 
 Typically a good limiter takes you from 3 or 4 digits up to 6 or 7 good
 digits.
 Net result is a measurement that’s good in the vicinity of parts in
>> 10^-13
 
> 
> Can you say something about how it would be done using a TIC?
> I don't have two identically good counters, but the HP 5335A could be
 used
> as TIC, couldn't it.
 
 The standard way of doing the test is to run two counters / two TIC/s /
 two whatever’s.
 I know of no practical way to do it with a single 5335.
 
> 
> And the offset source I used is not directly the HP 10811, but the HP
 8663A
> Signal generator internally uses a 10811 as reference source. But I
 didn't
> wait for days for it to warm 

Re: [time-nuts] Phase measurement of my GPSDO

[Taka Kamiya via time-nuts]

I am working on pretty much the same thing.  My HP105B has an HP11801 inside.  
There is no telling how long it has been off.  Frequency wandered ALL OVER THE 
PLACE.  It took 2 months of continuous operation to settle down and just do the 
normal aging/drifting.  

I have a same question as you do.  How come not just one HP5335?  Your test 
setup has two output.  One goes to start, the other goes to stop.  Measure the 
time interval.  Isn't that the goal?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, April 13, 2020, 5:53:52 PM EDT, Bob kb8tq  wrote: 
 
 
 Hi

> On Apr 13, 2020, at 5:06 PM, Tobias Pluess  wrote:
> 
> Hi Bob
> awesome, thanks! of course it is 1e6, not 1e7, I got a mistake :-)
> 
> Maybe I have some good OpAmps for this purpose in my box. I will try it! of

You need something that is quiet (like the OP-37) and has a pretty good slew
rate. Past that, there are a lot of candidates. The TI OPA-228 family is one. 

> course I saw that my setup was not ideal as there was a bit of noise on the
> signals which I guess does lead to some jitter in the trigger circuit and
> therefore decreases my measurement noise floor.

Typically a good limiter takes you from 3 or 4 digits up to 6 or 7 good digits. 
Net result is a measurement that’s good in the vicinity of parts in 10^-13

> 
> Can you say something about how it would be done using a TIC?
> I don't have two identically good counters, but the HP 5335A could be used
> as TIC, couldn't it.

The standard way of doing the test is to run two counters / two TIC/s / two 
whatever’s.
I know of no practical way to do it with a single 5335.

> 
> And the offset source I used is not directly the HP 10811, but the HP 8663A
> Signal generator internally uses a 10811 as reference source. But I didn't
> wait for days for it to warm up properly. (Should I?)

The 8663 synthesizer adds a *lot* of crud to the 10811. Regardless of how you
use the 10811, it needs to be on for a while. How long very much depends on 
just how long it’s been off. Best to keep it on all the time. 

> 
>> Fun !!!
> Yea, of course! :-)
> I already implemented the ADEV, MDEV and TDEV calculations in Matlab by
> myself. I use TimeLab to see what numbers I should expect, and then I want
> to compute it all myself in Matlab because I want to see how it actually
> works. ;-)

Be careful any time you code this stuff for the first time. It’s amazingly easy 
( = I’ve done it ….) to make minor errors. That’s in no way to suggest that
you should not code it up yourself. I generally do it in Excel or in C. 

Bob

> 
> 
> Best
> Tobias
> 
> 
> 
> On Mon, Apr 13, 2020 at 10:50 PM Bob kb8tq  wrote:
> 
>> Hi
>> 
>> Ok, first the math:
>> 
>> If your offset oscillator is 10 Hz high at 10 MHz, you have a:
>> 
>> 10,000,000 / 10 = 1,000,000 : 1 multiplier in front of the DMTD
>> 
>> You get to add a 6 to what Time Lab shows you.
>> 
>> If you are getting an ADEV at 1 second of 1x10^-4 then that multiplier
>> gets you to 1x10^-10
>> 
>> So, what’s going on?
>> 
>> You can’t feed the mixer outputs straight into a counter. The counter
>> front
>> end does not handle LF audio sine waves very well. You need to do an
>> op-amp based limiter. A pair of OP-37’s in each leg ( or something
>> similar)
>> should do the trick.
>> 
>> Second, the offset source needs to be pretty good. A 10811 tuned high with
>> both the mechanical trim and the EFC is a pretty good choice to start out.
>> 
>> If you only have one counter, simply ignore the second channel. You are now
>> running a single mixer. It still works as a comparison between the offset
>> oscillator
>> and your DUT.
>> 
>> If you want to do it properly as a DMTD, then you set up two counters. One
>> to measure mixer A and the other to measure mixer B.  Set them both up to
>> measure frequency. Time tag the data files so you know which reading
>> matches up with which.
>> 
>> Fun !!!
>> 
>> Bob
>> 
>>> On Apr 13, 2020, at 3:18 PM, Tobias Pluess  wrote:
>>> 
>>> Hi again Bob
>>> 
>>> I tried to do some measurements with a DMTD!
>>> In my junk box I found a little PCB from earlier experiments on that
>> topic,
>>> with a power splitter and two SRA-3H mixers, it was even already wired
>> for
>>> the DMTD configuration. So I gave it a try!
>>> As "transfer oscillator" I used my HP 8663A signal generator, and set it
>>> high in frequency by 10 Hz. To the two mixers, I connected the two 10MHz
>>> signals and at the mixer outputs, I put a little lowpass filter with
>> 100Hz
>>> corner frequency.
>>> The output signals from the two SRA-3 mixers are almost 0.5Vpp, so I
>> tried
>>> to feed them directly into the HP 5335A TIC and used the TI mode to
>> measure
>>> the delay between the two signals.
>>> This gives 10 readings/sec, which I try to process with TimeLab.
>>> It does give some interesting graphs, but I don't know yet how to
>> correctly
>>> set up TimeLab for this kind of measurement. I.e. now, I get an ADEV in
>> 

Re: [time-nuts] OCXO and fluctuations after EFC adjustment

[Taka Kamiya via time-nuts]

I wish such persons would write a book about the subject.  Audience will be 
small that it probably wouldn't make it a profitable venture.
As to coding, I wonder why it's a "touchy" subject  In assembly time, 
porting one architecture to another was a major undertaking.  One didn't 
"port", but one would have to basically re-architect and re-code.  Also, 
engineers did all kinds of odd things to get job done.  It's only recently that 
we have almost unlimited amount of memory and more than enough speed that many 
of us became lazy.  If lazy isn't the right word, reusability, 
self-documenting, etc became more important than write a smallest and most 
efficient code.
Myself, I once participated in a project (just two of us  my boss and me) 
where we had to use Z80 to read the data a large industrial machine puts out.  
It was coming out so fast, we couldn't code to read them.  So we had to use DMA 
to write directly write to memory, and when there is a break in stream, switch 
it over to CPU control and read them out.
I also recall Sun Microsystem used two 68000 CPU because certain interrupt 
didn't work right and it was essential for multi-tasking.  So they used two, 
one executing ahead of the other.  Somehow, they coded OS to back track and 
made multi-tasking work.  I thought it was very clever.
As to EFC, an odd man out is SRS PRS10.  It gives you 3 ways to do it.  An EFC 
input from outside, a 10 turn trimmer built into the box, or a programmatic 
control via DAC.  As far as I know, there is no trimmer.  At least it's not 
user accessible.  This is a very timely discussion as I am working on PRS-10 
project and 11081 project.  (two separate projects)

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, April 11, 2020, 3:02:13 PM EDT, Richard (Rick) Karlquist 
 wrote:  
 
 

On 4/11/2020 12:15 AM, John Moran, Scawby Design wrote:

> During my 50 years in the electronics industry I have always been puzzled 
> about one aspect of crystal oscillators. They go to great lengths to use a 
> precise piece of quartz as the heart, because of its unique properties, and 
> then add standard external components - capacitors, varactors, Zeners, etc. 
> to tweak its frequency. All these components vary far more than the original 
> piece of quartz ... hence my confusion.
> 
> I know it is practically impossible to grind a crystal to exactly the 
> frequency you want, and it then drifts over time, but what is the logic of 
> using relatively wildly varying components to adjust the quartz? Are their 
> temperature and ageing characteristics swamped by the superior crystal?
> 
> In all the papers I have ever read, the subject is never mentioned ... you 
> just add a variable capacitor and/or an EFC circuit and job done.
> 
> I guess this is showing my total ignorance here, but I would like to know.
> 
> Maybe this is at the heart of Rick's usual speech?
> 
> John
> 
>

For non-oven oscillators of ordinary precision (say 10 PPM over 0 to 
50°C), the low pullability of the crystal is such that adding
adjustment capacitors is not a big hazard.  An EFC circuit that
is inside some PLL of course is only at risk of adding some noise
from the drive circuit.  I can't remember ever seeing an EFC'ed
oscillators where the EFC was driven by, say, a pot.

In the case of the 10811, I have already posted about the
reference diode of special characteristics.  I don't remember
all the exact details of how it was chosen, but it was based
on proprietary knowledge.

Another anecdote of interest is that when the first 10811's were
being tested, they exhibited very bad aging.  It was eventually
determined after a lot of investigation that oil in the piston
trimmer was migrating around and tweaking the frequency.  I
don't remember whether the fix was using a different type of
oil, or having the vendor apply it selectively, or if they
deleted the oil completely.

This type of knowledge can basically only be learned by getting
a job working with the top experts in the field.  Before I worked
for HP, it became clear that I needed to get a job there in order
to figure out how their stuff worked.  I read HP manuals as much
as I could, but actually being there was the real secret.  I
asked as many people as possible about their particular expertise
in an effort to learn as much as possible.  The right approach is
necessary to get these experts to open up.  I was careful not to
wear out my welcome.

Every person is an expert in their particular field, and there
is always something to be learned from them.  A couple of ground
rules I formulated from experience:

1.  If they tell me something that I know is wrong, I usually just
thank them for the advice and then ignore it, rather than arguing.
Or "correcting" them!  Let them continue to believe what they
want to believe.  Sometimes I find out later that actually the
person was correct and I was wrong.

2.  Be extremely careful about asking "why 

Re: [time-nuts] OCXO and fluctuations after EFC adjustment

[Taka Kamiya via time-nuts]

Funny you should mention this.
During testing, I noticed an odd repetitive and modulated signal on ALL DC 
lines.  It looked like a typical AM modulated signal of 100KHz carrier and 
somewhere around 1KHz signal.  It was around 40mV p-p.

Long story short, it was the oscilloscope probe that was picking up the signal. 
 Different scope and different probe showed there are no such signal on any of 
my power lines.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, April 11, 2020, 12:56:26 PM EDT, Joseph Gwinn 
 wrote:  
 
 On Sat, 11 Apr 2020 00:24:45 -0400, time-nuts-requ...@lists.febo.com 
wrote:
Re: time-nuts Digest, Vol 189, Issue 18

> 
> Message: 4
> Date: Fri, 10 Apr 2020 13:23:22 -0400
> From: Bob kb8tq 
> To: Taka Kamiya , Discussion of precise time and
>     frequency measurement 
> Subject: Re: [time-nuts] OCXO and fluctuations after EFC adjustment
> Message-ID: <99642a49-8cdf-42d4-9039-7a5e7ff23...@n1k.org>
> Content-Type: text/plain;    charset=us-ascii
> 
> Hi
> 
> EFC changes by themselves are pretty much instantaneous. If you are seeing
> post tune drift, it likely is from the pot or from things like a 
> temperature change (or draft) when you go near the part. 
> 
> If your grounds are a bit intertwined, the change in oven current will give 
you
> a delta voltage on the ground. That can get into the EFC. Taking care of 
this 
> is harder than it seems. The 10811 has an independent ground return for the 
> oven, so it at least is *possible* to do in this case.
> 
> A good starting point is to hook up a DVM on your pot. Watch the voltage 
after
> you do a tune adjustment. If the drift you are after is in the parts 
> in 10^-12 range, that may take a pretty good DVM. 

Note that that many DVMs inject noise back into whatever they are 
measuring.  This could be interesting if one is measuring a 
frequency-control voltage.  A RC low pass filter may be useful.

Joe Gwinn

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Re: [time-nuts] OCXO and fluctuations after EFC adjustment

[Taka Kamiya via time-nuts]

What I noticed over years of taking things apart is that manufacturers use 
precision parts when its needed and use ordinary parts elsewhere.  

For me, selecting parts is often not a possible proposition.  I do not own 
ultra precision test equipment and/or environmental chamber.  With intrusion of 
counterfeit and/or out-of-spec parts in market, it is getting very difficult to 
ensure what I have is what I think I have.  An only thing I can do is to buy 
from reputable sources when it counts and bite the bullet and buy well spec'd 
parts.  Even that does not guarantee genuine parts depending on where 
fakes/remarks are getting in.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, April 11, 2020, 11:11:56 AM EDT, Bob kb8tq  
wrote:  
 
 Hi

Well, if you make OCXO’s that way, you will not be in business 
for very long. At least not selling to the major OEM’s ( or to any
customer who actually checks the parts).

Bob

> On Apr 11, 2020, at 10:26 AM, David C. Partridge 
>  wrote:
> 
> Well, that's how it's supposed to be done, but these days the usual (and 
> often only) criterion other than part value (e.g. 15V 200uF +/- 10%) seems to 
> be cost (cheapest == best).
> 
> Sad isn't it.
> 
> David
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Bob 
> kb8tq
> Sent: 11 April 2020 14:05
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] OCXO and fluctuations after EFC adjustment
> 
> Hi
> 
> Bottom line is that, as long as one is careful about *which* vendors supply 
> which
> parts, normal parts do the job. Nobody is going to publish that selection 
> process 
> or the results. They very much want the “other guy” to have to do it on their 
> own. 
> 
> The 78L12 might look just like one from 5 other vendors. It also might work 
> 10X 
> better than the others. Those caps may look pretty normal. They came from 
> “this guy” and not “those guys”. That cheap looking thermistor might have 
> spent 
> a few years in evaluation before it was approved for use. 
> 
> There is a lot of work that goes into component selection. It simply does not 
> result in $20 bulk metal film parts with 0.2 ppm/ C specs getting used. It is 
> a 
> lot more difficult to spot in the finished product. 
> 
> Bob
> 
> 
> 
> 
> 
>> On Apr 11, 2020, at 3:15 AM, John Moran, Scawby Design 
>>  wrote:
>> 
>> On Fri, 10 April 2020 14:31:53 -0700 Rick wrote:
>> 
>> 
>>> At this time, I will give my usual speech about IMHO the fact that
>> 
>>> since the invention of the DDS on a chip, EFC should no longer be used
>> 
>>> for high performance oscillators.
>> 
>> During my 50 years in the electronics industry I have always been puzzled 
>> about one aspect of crystal oscillators. They go to great lengths to use a 
>> precise piece of quartz as the heart, because of its unique properties, and 
>> then add standard external components - capacitors, varactors, Zeners, etc. 
>> to tweak its frequency. All these components vary far more than the original 
>> piece of quartz ... hence my confusion.
>> 
>> I know it is practically impossible to grind a crystal to exactly the 
>> frequency you want, and it then drifts over time, but what is the logic of 
>> using relatively wildly varying components to adjust the quartz? Are their 
>> temperature and ageing characteristics swamped by the superior crystal?
>> 
>> In all the papers I have ever read, the subject is never mentioned ... you 
>> just add a variable capacitor and/or an EFC circuit and job done.
>> 
>> I guess this is showing my total ignorance here, but I would like to know.
>> 
>> Maybe this is at the heart of Rick's usual speech?
>> 
>> John
>> 
>> 
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[time-nuts] OCXO and fluctuations after EFC adjustment

[Taka Kamiya via time-nuts]

I have a few HP10811 and was thinking of making an interesting setup:  A setup 
where frequency is purposely offset by user defined amount by few Hz, and make 
it selectable.

Under normal setup, I would use a potentiometer and EFC control the frequency.  
When I adjust EFC, the frequency immediately moves but then drifts.  It takes 
an hour or so to settle down again, then I have to readjust.  Due to precision 
of my testing setup, I am unable to quantify this.  

Is this a nature of OCXO in general or is this unique to HP10811?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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[time-nuts] Buffer amplifier, OP Amp, vs MMIC, vs discrete?

[Taka Kamiya via time-nuts]

I'm seeing a fairly obvious trend on this list.  When it comes to buffer 
amplifiers, many people, in fact, most I've seen recommends fast OP Amp.  
Discrete Amp, such as ones from K5FX design, NIST design, Clifton amp, and 
others are mentioned only sometimes.  Trends are similar for distribution amps. 
 Video amps are generally not recommended.

But I have never seen a suggestion of MMIC like ones from Mini-circuits.  There 
are few that work from DC, fairly good NF, but often too high of gain.  Other 
than high gain, are there reason NOT to use MMIC?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] PRS-10 PPS output

[Taka Kamiya via time-nuts]

I've seen this with my own.  You are catching the leading edge of ringing of 
the signal.  

Since the output is CMOS, and high impedance, it really doesn't have enough 
current to push through low impedance cables.  Try shorter and different cable. 
 Terminate it with 50 ohms.  Set the trigger level little higher.  In my setup, 
the cable is actually a very short twisted pair, and only 2" long into a buffer 
board.

You might want to look at what your PRS-10 is set to, as far as pulse width is 
concerned.  Also, use much longer horizontal scan rate.  The standard pulse 
width is 10 MICRO second.  Your image is capturing beginning of the pulse but 
not the whole of it.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, April 3, 2020, 3:21:09 PM EDT, Mike Ingle 
 wrote:  
 
 Hello fellow nuts,

I just received my PRS-10 with boardlet and heat sink, and I have a
question regarding my PPS output signal.
My output looks strange, (but usable).  I have attached a couple
screen-shots of my scope/
The first is with 50 ohm termination after 5foot of 5g-58 cable, the second
is without termination.

--mike
[image: pps_term.png]
[image: pps_unterm.png]
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Re: [time-nuts] Phase measurement of my GPSDO

[Taka Kamiya via time-nuts]

I had trouble understanding this as well.
Your PPS is derived from 10MHz internally by variety of method but usually by 
dividing of some kind.  So the error rate of 10MHz and PPS is usually the same 
of similar.  Please note, I said RATE.  If one moves by 1%, the other moves 1%.
DMTD is mixing.  Take 10MHz and mix 10MHz + 10Hz.  The product is 20MHz + 10Hz, 
and 10Hz.  You cut off the former and use the latter.  Assuming your I/F source 
is completely stable, If the source moves 10Hz, your result moves 10Hz as well. 
 10Hz output suddenly becomes 20Hz.  100% increase.
I hope you can see 100% change is easier to measure than 1% change.
I have HP5335A as well as HP53132A.  I've been using the latter but they work 
similarly.  Multiple measurement and averaging.  You can actually see the 
fluctuation.  But as John and Bob said, they show better than the reality.  

I hate to tell you this, but an only way to really understand this is to 
actually try it.  I spent 2 months on this stuff and now I vaguely understand 
it.  Well, understand it enough to tell you what I just said.  Just reading 
about it, it sounds very difficult and confusing.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, April 3, 2020, 12:01:18 PM EDT, Tobias Pluess  
wrote:  
 
 Hi John

Yes, I totally agree with you and I also understand the difference.
But what I still don't understand is the following:
Obviously, my 5335A is not accurate/precise enough to measure below 1e-9
for short tau. Currently I am comparing the 1PPS signals, but when I change
that and use the DMTD method, I will still compare some 1Hz signals, and
the counter is still not able to resolve stuff that is lower than 1e-9. So
why would the DMTD work better?
I totally see that the error is somehow multiplied, but if my GPSDO is good
(which I hope it is :-)) the error will still be very small - perhaps in
the 1e-9 or 1e-10 region, so too low for my 5335A. Not?


Tobias

On Fri, Apr 3, 2020 at 5:34 PM John Ackermann N8UR  wrote:

> I think the difference is between *mixing* or *dividing* down to a low
> frequency.
>
> When you divide, you divide the noise along with the carrier frequency.
>
> When you mix, you "translate" the noise.  If the signal bounces around
> 0.1 Hz at 10 MHz (awful, I know), when you divide to 1 PPS the noise is
> also divided by 1e7 so the ratio remains the same.
>
> But if you mix via a 9.999 999 MHz local oscillator, now your output at
> 1 Hz still has 0.1 Hz of noise on it.  i.e., it's the same absolute
> value of noise as you started with.  So you measure that absolute value
> but don't compare it to the mixed down 1 Hz frequency, compare it to the
> original 10 MHz frequency.  It's basically an error multiplier.
>
> John
> 
>
> On 4/3/20 11:25 AM, Tobias Pluess wrote:
> > Hi again Bob,
> >
> > yes you describe a simple DMTD measurement. But could you tell me what
> the
> > difference is between that and comparing the 1PPS pulses?
> > I mean, I could set the 10811 high in frequency by just 1Hz, and then it
> > would result in two 1Hz signals which are then compared.
> > Which is essentially the same as comparing two 1PPS signals, isn't it?
> > Ok there is a minor difference: since the 1PPS signals are divided down
> > from 10MHz, their noise is also divided down, which is not the case for
> the
> > DMTD.
> > However, in the end I am comparing signals in the 1Hz to 5Hz or 10Hz
> > region, and apparently, the 5335A is not suitable for those, at least not
> > with the desired stability, is it?
> >
> >
> > Tobias
> >
> > On Fri, Apr 3, 2020 at 1:45 PM Bob kb8tq  wrote:
> >
> >> Hi
> >>
> >> The quick way to do this is with a single mixer. Take something like an
> old
> >> 10811 and use the coarse tune to set it high in frequency by 5 to 10 Hz.
> >>
> >> Then feed it into an RPD-1 mixer and pull out the 5 to 10 Hz audio tone.
> >> That tone is the *difference* between the 10811 and your device under
> >> test.
> >> If the DUT moves 1 Hz, the audio tone changes by 1 Hz.
> >>
> >> If you measured the 10 MHz on the DUT, that 1 Hz would be a very small
> >> shift
> >> ( 0.1 ppm ). At 10 Hz it’s a 10% change. You have “amplified” the change
> >> in frequency by the ratio of 10 MHz to 10 Hz ( so a million X increase
> ).
> >>
> >> *IF* you could tack that on to the ADEV plot of your 5335 ( no, it’s not
> >> that
> >> simple) your 7x10^-10 at 1 second would become more 7x10^-16 at 1
> >> second.
> >>
> >> The reason its not quite that simple is that the input circuit on the
> >> counter
> >> really does not handle a 10 Hz audio tone as well as it handles a 10 MHz
> >> RF signal. Instead of getting 9 digits a second, you probably will get
> >> three
> >> *good* digits a second and another 6 digits of noise.
> >>
> >> The good news is that an op amp used as a preamp ( to get you up to
> maybe
> >> 32 V p-p rather than a volt or so) and another op amp or three as
> limiters
> >> will
> >> get you up around 6 

Re: [time-nuts] Crystal filters in test equipment

[Taka Kamiya via time-nuts]

I don't have sophisticated instruments, so I did a basic test.  Feed 2MHz into 
a spectrum analyzer and place a 2MHz crystal in series.  I didn't concern 
myself with impedance matching or any other details.  Just a coax in and out.

It basically acts like a very sharp filter.  What it does to phase noise, etc, 
is beyond my ability to measure.  I'll have to remember this trick  It 
might come in handy!

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, March 26, 2020, 7:32:24 PM EDT, Perry Sandeen via time-nuts 
 wrote:  
 
 Learned Gentlemen,
Both the HP 106 and 107 have a post oscillator crystal filter.  There is also a 
10 MHz crystal filter used in my Tracor 527E FDM.
So the question I have is there anything to be gained by adding 10 MHz crystal 
filters to the 10811 and similar OCXO's?  They are very inexpensive to purchase.
Regards,
Perrier
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Re: [time-nuts] Noise Floor

[Taka Kamiya via time-nuts]

Yes.  The first page says that, along with several entries in the spec sheet.  
Then, on page 6 lists absolute maximum.  12.6V (I was .1V off).  To me, that's 
awfully close.  I chose not to go there, especially when 9V gave me what I 
wanted in the first place.

In many ways and places, I've learned not to get too close to the maximum 
rating of devices.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, March 26, 2020, 4:48:25 PM EDT, Charles Steinmetz 
 wrote:  
 
 Taka Kamiya wrote:

> According to the datasheet, AD8007's absolute max is 12.5V.  It's a bit scary 
> to go to 12V.

Not at all.  Look at the first page of the datasheet, which recommends 
supplies from 5v to 12v.  I've deployed thousands of them running at 12v 
(usually, +/- 6v) with superb reliability.

That said, today I use modern CFB amps with 36v supply ratings for these 
jobs, and if I had a Z1 I would certainly retrofit it with one 
without a second thought.  There is no substitute for headroom!

Best regards,

Charles



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Re: [time-nuts] Noise Floor

[Taka Kamiya via time-nuts]

According to the datasheet, AD8007's absolute max is 12.5V.  It's a bit scary 
to go to 12V.  I was able to reduce the gain to zero dB, and get a clean and 
respectable 11.5dBm output.  With this, I'm perfectly happy.  I would 
experiment with other changes if I had a meaningful way to measure its impact, 
but I do not.
Thanks for your advice!

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, March 25, 2020, 5:28:16 PM EDT, Charles Steinmetz 
 wrote:  
 
 Taka Kamiya wrote:
> I've been playing around with Clifton amplifier as well.  Mine, input is 
> terminated with 50 ohm register, and rest is unmodified, so it has 6dB gain.  
> I have a 10dB pad on input side.  I, too, noticed there will be a severe 
> clipping with driving it too hard.    *  *  *  I with there was a little more 
> room there

Bob wrote:
>> Maybe there's some noise in those resistors
>> Well. maybe not so much.
 >>
>> If you drive this board so it has a couple db more output, it goes into 
>> clipping. When that happens  yuck.
 >> Noise and ADEV both are massively impacted.
>> You very much do *not* want to overdrive this board.  *  *  *
>> I would stick with 12 dbm or less

You can buy some headroom by raising the supply voltage.  There is an 
on-card LM78L09 9v voltage regulator (U902) that can safely be raised to 
12v (LM78L12).  This will get you cleanly to and a bit past the 
traditional +13 dBm (1v rms) standard reference level.  Of course, you 
will need to make sure the raw supply voltage is >15v.

As to noise, the 200 ohm resistor on the opamp's noninverting input 
(R901) accounts for nearly 6dB of the amplifier noise (assuming an 
effective source impedance of 50 ohms).  Reducing this to, say, 33 ohms 
will lower the noise floor a few dB.

Finally, the state of CFB video amplifier development has advanced 
dramatically in the 20 years since the AD8007 was introduced.  New 
amplifiers with supply voltage ratings up to 36v are available (allowing 
about 10dB greater headroom than the 8007), and many of the newer opamps 
clip much more gracefully than the 8007 when you do hit the limit (but 
you really want not to do that in any measurement application).

Many of these new CFB amplifiers have been discussed here on the list, 
and each has its own fans.  One I like that doesn't get mentioned much 
is the LME49713.  It is discontinued, but still available from Rochester 
Electronics and others.  But there are lots of good choices.

Best regards,

Charles



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Re: [time-nuts] Noise Floor

[Taka Kamiya via time-nuts]

I've been playing around with Clifton amplifier as well.  Mine, input is 
terminated with 50 ohm register, and rest is unmodified, so it has 6dB gain.  I 
have a 10dB pad on input side.  I, too, noticed there will be a severe clipping 
with driving it too hard.  I plan to zero the gain and retest.  Without proper 
termination on input side, it showed phantom gain of 10dB.?
I stayed conservative and output is 7dBm.  I with there was a little more room 
there  Looks pretty clean spectral density wise.  (frequency is 10MHz)

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, March 25, 2020, 2:00:08 PM EDT, kb...@n1k.org  
wrote:  
 
 Hi

So, here we have a couple of plots of a Clifton Labs Z1 amplifier board.  
It's a part that several list members (including myself) 
have recommended using.  The board has the "stock" high input impedance and has 
been modified for 0 db gain (470 ohm resistor so
just over 0 db ...). There is a 6 db pad between the splitter and the amp to 
terminate things.  The run is fairly short so the data is a bit rough. 
For a better look, an overnight run would show a bit more detail. 

Phase noise looks pretty good. ADEV has some weird "stuff" going on. Time to 
start tearing the board apart to see what's wrong with it?
Maybe there's some noise in those resistors  let's go 

Well. maybe not so much. If you go back and dig up the original plots in 
this thread, the ADEV is *essentially* at the "noise 
floor" of the measurement system. There are sure to be some wobbles in a 
shorter ADEV run so it's not a 1:1 sort of thing. 
Phase noise wise, everything from about 80 Hz and lower is at noise floor. The 
data out at 100 KHz offset suggests that for a low 
phase noise system, this board would degrade the typical 10811 by a slight bit 
"wideband". 

Since noise floor likely changes with things like drive level and frequency, to 
be 100% sure of the floor, one would need to repeat the original
test at this frequency and these levels. I'm not that ambitious  What I have 
tells me pretty well when I've hit the limit. It keeps me from 
going crazy "debugging" a board that actually does not have a problem. (or if 
there's a problem, my quick test can't see it )

Some other Z1 trivia:

If you drive this board so it has a couple db more output, it goes into 
clipping. When that happens  yuck. Noise and ADEV both are massively
impacted. You very much do *not* want to overdrive this board. (This is also 
true of most amplifiers)  At ~14 dbm out at 5 MHz  you are in clipping. 
I would stick with 12 dbm or less (at 5 MHz ... who knows about other 
frequencies ...).  

Dropping gain to zero db with the resistors on the board is better than doing 
the same with a pad on the input. The wideband phase noise is a bit 
better when done with the resistors. Very much like the front end on a radio 


Fun !!!

Bob



-Original Message-
From: time-nuts  On Behalf Of jimlux
Sent: Tuesday, March 24, 2020 7:31 PM
To: time-nuts@lists.febo.com
Subject: Re: [time-nuts] Noise Floor

On 3/24/20 2:17 PM, John Miles wrote:
>>> It would be interesting to know what ADC was used and if there's an
>>> SDR-board out there that uses the same ADC.
>>
>> Uh.. I remember John telling me what ADC it was, but I forgot, sorry.
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Re: [time-nuts] Accuracy results with Trimble Thunderbolt?

[Taka Kamiya via time-nuts]

Antenna mask of zero degrees is actually NOT good.  You get satellites going in 
and out of your antenna's view too often (because satellite can pop in and out 
of horizon, and other obstructions), cause switches in satellite used, and that 
contribute to fluctuations.  10 to 20 degree, in most cases, will give you 
better results.  I'd suggest seeing what it is set to and adjust accordingly.  
"Auto" anything will assume a lot of things, and what it arrives isn't always 
the best.

Also, what T-bolt outputs and LH displays isn't an actual measurement of the 
output.  It's a computed figure.  I don't actually look at it...  as long as 
it's locked, I'm pretty happy.
By the way...  I have a lot of GPSDO in my lab.  Short term fluctuation of 
output vary quiet a bit.  That is quite normal.  It is designed to give you a 
good average over time.  (hours to days)

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, March 20, 2020, 5:51:27 PM EDT, Frank O'Donnell 
 wrote:  
 
 I hope you all don't mind a novice-level question, but I'd be interested 
in any feedback on what I'm seeing with the accuracy of the 10 MHz 
signal out on my Trimble Thunderbolt.

I bought the Thunderbolt last year used on eBay, and it appears to be of 
about 2001 vintage. Most recently it's been running continuously for 
about 2 1/2 months, attached to a roof-mounted Lucent PCTEL 26db twist 
antenna with a clear view of the sky, with the receiver located in a 
room with a relatively stable temperature. Lady Heather and Thunderbolt 
Monitor both appear to report it to be well settled-in. My main use of 
the Thunderbolt is to supply a 10 MHz reference signal to an HP3586B and 
HP3336B for frequency measurement purposes.

At the beginning of this month I remember typically seeing about 20 ppt 
accuracy for the 10 MHz reference as reported in Heather. I then used 
Heather commands to initiate an autoset of oscillator parameters (set 
antenna elevation mask angle to 0 with FE keyboard command and set 
signal level mask to 1 with FL command in order to allow collection of 
signal level data across full sky; clear signal level history with CM 
keyboard command; let run at least 6-12 hours to build up new satellite 
signal level map; issue “” autotune command, allow time to complete). 
Now I seem to be seeing about 60 ppt accuracy on average.

For my purposes, these differences are probably academic -- if I'm doing 
my math right, 60 ppt in a 10 MHz signal is 0.0006 Hz, far down in the 
noise of frequency variation due to Doppler etc. Still, I guess I've 
drunk enough of the Koolaid to wonder about the accuracy level and any 
ways to improve it.

So, some questions. Is it possible that the increase in the error seen 
could be due to the oscillator parameter autoset sequence that I ran? If 
so, is there a way to remedy this? What would be typical accuracy for 
the 10 MHz reference on a Thunderbolt? Is there anything else I can do 
with the Thunderbolt itself to increase the accuracy?

If I want to consider an alternative to the Thunderbolt that might offer 
better accuracy, is there a logical next step?

Thanks for any suggestions,

Frank


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Re: [time-nuts] HP 106B on Ebay

[Taka Kamiya via time-nuts]

I saw this one.
What scares me is that the seller appears to be competent in testing his 
frequency counter, oscilloscope plugin, and other equipment, but on this one he 
says, "not sure how to operate".  My alarm went off and I didn't bid.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, March 20, 2020, 2:49:34 PM EDT, Bob kb8tq  wrote: 
 
 
 Hi

I’m guessing that it is a dewar based OCXO. If so, the *big* question is: Can 
the boys at UPS / Fed Ex / DHL / USPS (your pick) get it to you
without cracking the glass bottle? I’ve had reasonable success at shipping them 
( = dewar based OCXO’s not HP106’s)  in, but not 100%
success. Replacing dewars is generally not an easy task.

Bob

> On Mar 20, 2020, at 12:49 PM, Perry Sandeen via time-nuts 
>  wrote:
> 
> Gents,
> This is the only one I've ever seen on ebay in 15+ years.  Sold as parts only 
> but it has a clean 5Mhz output.  No bids so far at $499. Auction ends Sat 
> 1:52 PDST.  (I'd buy it if my discretionary financial situation was better).
> Regards,
> Perrier
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Re: [time-nuts] Modern Rb atomic reference vs classic Cs

[Taka Kamiya via time-nuts]

Paul and Bob are my valuable mentors, and I trust their opinion.
I do have an old working Cs but my go-to are GPSDO.  For most part, it's more 
than sufficient.  I also have ex-telecom Rb.  There aren't too many things one 
of them can't do, except for measuring themselves.  In my lab, the "lab 
standard" is GPSDO and backup is Rb.
At a hobby level, one of the big issue (at least to me) is power consumption, 
and the heat they generate.  My lab gets significantly warm.  Plus, instant 
availability of GPSDO and Rb (because they are always on) is hard to beat.  To 
save Cs, I only turn on mine when needed, then wait for 2 days.
To be honest, I'd love to have an HP5071A with warranty.  But it's far beyond 
affordable range for me.  Also, a "standard" I can't trust isn't a standard.  I 
am not good enough to properly care for Cs and I don't have good enough 
measuring system.  It takes a lot to keep Cs happy and usable in many ways.
Signed, on laziest ham.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, March 14, 2020, 12:14:43 PM EDT, paul swed 
 wrote:  
 
 I will chime in here also. It is indeed great to say you have a cesium. HP
5061s are just good fun to play with. It teaches you that as much as you
think you know you actually don't. But they do honestly take care and
feeding especially in the tail-end market that i can afford.
So to Bobs comment if you want a good reference for time-nuttery the GPSDO
is a really effortless way to go. Hard to say if RB or Xtal is better it
depends on what you might get at a flea market. But there is a lot to be
said for turn it on and be happy. I actually run a GPSD-TCXO as a instant
on sort of right there for my ham stuff. Power consumption sub 10 Watts.
Then flip to a HP3801 or any number of alternates including Cesium for
serious stuff like D-PSK-R development.
Signed one lazy ham.
Regards
Paul
WB8TSL

On Sat, Mar 14, 2020 at 8:31 AM Bob kb8tq  wrote:

> Hi
>
> Backing off a bit, as long as GPS is doing it’s part ( or your GNSS system
> of
> choice …) an OCXO based setup may do as well as / better than your typical
> “almost dead” used Cs standard.
>
> It is very easy to find a used Cs with a dead tube. It is quite hard to
> find one
> with a tube that is fully up to original specs / runs for years. Finding
> replacement
> tubes is ( and always has been) a very involved process. There are way
> more
> used / dead tubes out there than used / working.
>
> Buying a new tube is in the “forget about it” price range. There also is
> no practical
> way to rebuild one. You can do this or that trick to maybe get a bit more
> time out
> of this or that tube … but maybe not.
>
> Thus the pair of dead 5061’s sitting in the basement.
>
> Bob
>
> > On Mar 14, 2020, at 12:06 AM, Peter Membrey  wrote:
> >
> > Hi guys,
> >
> > Potentially a bit of a loaded topic, but I'm really curious as to what
> the consensus is on this. For the research I've been doing over the past
> few years, I've been predominantly using an SRS FS-725 (which uses the
> PRS-10) disciplined by a Microsemi S650 (with the Rb option, though it
> never went into holdover).
> >
> > Modern Caesium references are expensive compared to the FS-725, but now
> and then more classic Caesium references become available such as the HP
> 5061A. These still aren't cheap (actually, not far off a brand new PRS-10)
> so I was wondering how do they generally compare with a modern Rb?
> >
> > If I have a PRS-10 that's being disciplined by a good GPS source, would
> I see any benefit if I replaced the PRS-10 with an HP5061A (particularly in
> terms of stability)?
> >
> > Thanks in advance!
> >
> > Kind Regards,
> >
> >
> > Peter Membrey
> >
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[time-nuts] Free equipment cart for anyone willing to pick it up at near Orlando, Florida, USA

[Taka Kamiya via time-nuts]

I have a "Tek Lab Cart Model 3" in pretty nice shape available for FREE.  The 
only caviet is, you must come and pick it up yourself.  I live in Zip Code 
32703 which is near Orlando, Florida, USA.  I cannot ship this.  Please contact 
me off list, if interested.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Buying and using used Cesium Beam Standards

[Taka Kamiya via time-nuts]

I am a Time-Nut in training.  I am still learning.  So I can only contribute a 
small amount.
I have an old Cesium standard by FTS, model FTS4040A.  Amazingly, it still 
locks.  Amazingly, it's still holding stable.  So far, works every time and 
frequency is the same.  But a big question remains  for how long?  The 
answer is, I'll know when it no longer locks.  In talking to professionals and 
TimeNuts, there is a way to extend life time a bit, and if you keep watching, 
it will show tell-tale sign of the tube about to quit, but there is no really 
big red light warning about its death.
Even when you don't use the box and is turned off, "the time clock" (I mean 
wearing out) slows but still is ticking.  All things sealed will leak very very 
slowly.  Everything contained will slowly be consumed.  Per manual, every 6 
months, you must turn it on and let the vacuum pump do its thing, or otherwise 
you will end up with contaminated and compromised tube.  I understand newer 
machines has a stand-by mode where pump is running but the rest is not.  Mine 
does not have such feature.  Every time I need it, I turned it on and wait for 
few days, then use it for a bit then shut it down.  It's not as useful as you 
might think.
But as mine is still usable after 25 to 30 years and with original tube, I 
guess rarely used and well cared for standard can last.

I bought mine from a local dealer for a good price.  So if it quits, so be it.  
Replacement tubes are $30K to $40K range.  There is no way I can afford it.  
Getting one in second hand market, forget it, unless you luck out.  There is an 
individual on this mailing list whom in the past had a batch of it and helped 
out many, as I understand.  But still usable tubes just don't become available. 
 Personally, I have never seen it on eBay in few years I've been watching.  
Just to show how "sad" the situation is, I bought a non-working HP5071A with 
high-performance tube for $50.  I just took it apart for parts.  This is a $70K 
equipment!  It's really worth only for parts.

I will be more than happy to answer any "don't know what to ask" question you 
may have.  If I know it, I'll help you out.  You can ask me anything without 
fear!  But chance of me knowing something is rare at this moment.
By the way  if I am going to buy one in used market, it will either be from 
a local source or from someone on this mailing list.  It is a well known secret 
that most dealers on eBay who advertise "tested" mean turned it on and red 
light came on.  
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Tuesday, March 10, 2020, 8:00:45 PM EDT, Forrest Christian (List 
Account)  wrote:  
 
 I noted Skip Winthrow's message about the listing of a Cesium standard on
eBay.

I've had some questions generally about these used standards for some time
now, figured this was a good time to ask them.

So let's assume I buy a used unit in working condition.  I get it here, it
works fine, and everything is up to spec.  Let's also assume that I really
only need it operational a week or two a couple of times a year during
periods I'm doing measurements that require the stability of the Cesium
standard.

What is the best way to improve the odds that this used gear is
working properly when I need it?  I'm asking primarily because I know that
the cesium tube itself wears out, and replacing the tube does not often
make financial sense.  I guess I'm asking is if the 'wearout clock' on the
tube stops if the unit is powered off and is on the shelf, or if there's
something else one does to extend the life of these units.

All of the other questions I have are probably more in the category of "I'm
not sure what questions to ask".  I've owned/used/fixed a fair bit of used
test equipment over the years, but this seems to be in an entirely
different category.  I've never had any experience with these at all, so if
anyone would like to pontificate with any wisdom or experience in the
basics of acquiring and using a Cesium standard I'd appreciate it.

-- 
- Forrest
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[time-nuts] HP5071A parts available

[Taka Kamiya via time-nuts]

Hi,
Over the last weekend, I took apart an HP5071A with a high performance tube 
option.  The tube was entirely exhausted but as far as I am aware, other 
components are still in good shape.  I'm keeping the front panel, CBT, and an 
oven oscillator but other parts are available.  If someone needs something, 
please contact me offline if interested.  Parts are free for this community as 
a token of appreciation for all the help I received.  Depending on the actual 
cost, I may ask you to cover the shipping cost.

Due to the nature of the equipment, I am not taking a risk.  I'm sorry, this 
offer is for US folks only.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Looking for HP105B addendum for HP11801 oscillator upgrade

[Taka Kamiya via time-nuts]

Thank you!  I just downloaded it, and that is what I was looking for.  

My HP105B is showing strange symptom. OVEN meter reading is always at full 
scale and frequency tends to wander.  This will certainly help.  Thank you 
again.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, March 6, 2020, 10:53:14 AM EST, Charles Steinmetz 
 wrote:  
 
 Taka Kamiya wrote:

> I have an HP105B with a newer HP11801 oscillator.  *  *  *    According to 
> archive, this particular update was never a part of the main manual but was 
> covered in separate 1/2" thick yellow booklet.  Does anyone have a soft-copy 
> of this?

What I have is a 39-page document of "Manual Updating Changes" dated 
April 5, 1989 that covers the update ("This supplement adapts your 
manual to instruments with serial numbers prefixed through 2848A.").  It 
has schematics.

This is available at ko4bb.com as a .zip file, somewhat confusingly 
named "HP 105B Crystal Oscillator Service Manual-HP105B PSU.zip."

Visit the "manuals" page 
 and search for 
"hp105" (do not type the quotation marks).

The .zip file contains two files, 37 pages of text plus 2 pages of 
full-size schematics.

Best regards,

Charles



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[time-nuts] Looking for HP105B addendum for HP11801 oscillator upgrade

[Taka Kamiya via time-nuts]

I have an HP105B with a newer HP11801 oscillator.  When switching to OVEN 
position, meter goes to full scale and stays there forever.  It has been over a 
week this way.  Also, the frequency is unstable.  According to archive, this 
particular update was never a part of the main manual but was covered in 
separate 1/2" thick yellow booklet.  Does anyone have a soft-copy of this?
All I found in archive was "contact me via DM" and was over 15 years ago.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Time-Nutters-- Adding Rubidium to a Thunderbolt...?

[Taka Kamiya via time-nuts]

Hi
I'm doing it.  I've taken PRS-10 which has PPS IN feature and fed it with PPS 
from Trimble.  It is still work in progress but the mechanism works.  Time 
constant of the PRS-10 is set to very long time (8 hours?) from factory when 
signal is present on PPS-10.  

Problem I'm encountering is that I get precise time by the nature of Trimble 
but Adev worsens.  This is because PPS of T-bolt has more jitter than stability 
of PRS-10 itself.  While PRS-10 is still providing stable signal, T-bolt pushes 
and pulls. Also, lock is achieved in few minutes but to truly synchronize, it 
takes weeks.  It contradicts what I just said but push and pull is more like a 
nudge, so initial synchronization takes forever.
PPS IN pin on PRS-10 is dual purpose.  You must make sure a jumper is set 
correctly, or it won't work.  My finding is that PPS from GPSDO works much 
better than just GPS, and this is because raw PPS from JUST GPS does not enjoy 
pre-processing.  GPSDO's PPS is regenerated by steered signal, and not direct 
from satellites.
It is an interesting experiment.  Getting it to work was easy.  Getting it to 
work well, I'm still working on it.



--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, March 2, 2020, 1:21:16 AM EST, mp...@clanbaker.org 
 wrote:  
 
 Hello, Time-Nutters--

Is it possible to add/combine/mate a rubidium osc to a Trimble
Thunderbolt GPSDO?

Have there been any examples of this that I could use as a guide?

Thanks for any info/feedback on this!!

Mike Baker
Gainesville/Micanopy
Florida USA
***


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Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

[Taka Kamiya via time-nuts]

YES, please.  tkami...@yahoo.com.
So far, I've taken HP105B and did adev frequency reading based, T.I. based 
adev, and while at it, I am doing PRS-10 T.I. based.
I have a question.  My 1 second reference for channel A is coming from GPS 
based 1 second.  I understand it's only 10E-8 precision on second to second 
basis?  Is this sufficient for OCXO and Rb based oscillators?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, February 29, 2020, 7:21:28 PM EST, Magnus Danielson 
 wrote:  
 
 Hi,

On 2020-02-29 23:10, Taka Kamiya via time-nuts wrote:
> One question for Magnus.
>
> Ch A start - pps (standard)Ch B stop - DUT
> On item 4, you said "frequency of the signal on time B".  That much is 
> obvious.  But then you said: "give it the time-base of the period on the 
> A-channel".  Will you explain this?
> Say I give 1 Hz, period is 1s.  Say I give 10Hz, period is 0.1s.  Is this 
> what you mean?
Yes. Exactly.
> I'm using HP5370A.  This instruction is valid on this TI counter, correct??
Yes. It will work.
>
> A request for everyone:
> I am conducting an one hour measurement on HP105B.  Does anyone have 1 hour 
> plot of this signal generator handy?  If so, will you DM me a copy?  For some 
> reason, I cannot find one on the great Internet.

I have one of the 00105 oscillator ,as mounted and free-running in a
HP5065A, against hydrogen maser at hand. I can locate that and send you
if you wish. It's longer than 1 hour, but you get additional precision
from this.

Cheers,
Magnus

>
> --- clip from Magnus's previous email--
> A setup I use a lot is this:
> 1) Connect a reference oscillator to produce a 1 Hz or 10 Hz signal and
> feed into a counter Channel A/TI-start channel. For PPS signals, I make
> sure to trigger a but up on the rising edge not to false-trigger. For
> some counters this means turning of automatic trigger and set it to 1 V
> manually. It is important that no false triggers occurs.
>
> 2) Connect a signal under test to Channel B/TI-stop. Adjust trigger to
> through-zero or up on the edge as suitable.
>
> 3) TI-mode, continuous trigger
>
> 4) Collect data in TimeLab, give TimeLab the frequency of the signal on
> B-channel, give it the time-base of the period on the A-channel.
>
> 5) Look at data as it comes in. Look at phase view, frequency view,
> wrapped phase. Look at the ADEV, how the upper end flaps with data, but
> how the same tau becomes more and more stable as it comes 
> in.-
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
>  
>
>    On Friday, February 21, 2020, 9:26:47 PM EST, Magnus Danielson via 
>time-nuts  wrote:  
>  
>  Hi Taka,
>
> On 2020-02-21 23:26, Taka Kamiya via time-nuts wrote:
>> I'm sorry, I messed up.  I jumped on more advance topic than I intended.  
>> I'm sure there were answers in the replies but they must have gone way over 
>> my head because some of original questions still remain.  I bulletized (is 
>> that a word?) the original question with my NEW understanding.  Would 
>> someone please respond for me, point-to-point?
> No problem. No worries. I hope you end up reading these and the other
> replies again and acquire good knowledge. I know it's like drinking from
> a fire-hoze, but you did ask some very relevant and fair questions.
>> 1)  A frequency counter that measures DUT basically puts out a reading every 
>> second during the measurement.  When TimeLab is well into 1000s or so, it is 
>> still reading every second; it does not change the gate time to say, 1000s.  
>> I understand now, Adev is about phase, not the frequency.  But assuming DUT 
>> is sine wave, if there is enough phase change, frequency do change.  I think 
>> of phase change as frequency change that is less than full cycle.  So how 
>> does counters that outputs every 1 second end up in tau of 1000s?  It will 
>> entirely miss phase change that spans more than 1 cycle.
> ADEV is about the frequency stability. ADEV can be calculated using
> phase or frequency measures. We tend to prefer using phase measures from
> Time-Interval Counters for these things.
>
> OK, so let's say that we want to output a counter which provides output
> of frequency estimates but for a time-base which is longer than 1 s,
> even if we output results every 1 s?
>
> Classically counters could not do that. You acquired a start-value,
> waited the time-base, acquired a stop-value, calculated a result to
> display and then arm to get a new start-value for the next result. Such
> counters will have a limit that the rate of readings will be limited by
> the time-base, so if it is set to 10 s,

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

[Taka Kamiya via time-nuts]

One question for Magnus.

Ch A start - pps (standard)Ch B stop - DUT
On item 4, you said "frequency of the signal on time B".  That much is obvious. 
 But then you said: "give it the time-base of the period on the A-channel".  
Will you explain this?
Say I give 1 Hz, period is 1s.  Say I give 10Hz, period is 0.1s.  Is this what 
you mean?
I'm using HP5370A.  This instruction is valid on this TI counter, correct??

A request for everyone:
I am conducting an one hour measurement on HP105B.  Does anyone have 1 hour 
plot of this signal generator handy?  If so, will you DM me a copy?  For some 
reason, I cannot find one on the great Internet.

--- clip from Magnus's previous email--
A setup I use a lot is this:
1) Connect a reference oscillator to produce a 1 Hz or 10 Hz signal and
feed into a counter Channel A/TI-start channel. For PPS signals, I make
sure to trigger a but up on the rising edge not to false-trigger. For
some counters this means turning of automatic trigger and set it to 1 V
manually. It is important that no false triggers occurs.

2) Connect a signal under test to Channel B/TI-stop. Adjust trigger to
through-zero or up on the edge as suitable.

3) TI-mode, continuous trigger

4) Collect data in TimeLab, give TimeLab the frequency of the signal on
B-channel, give it the time-base of the period on the A-channel.

5) Look at data as it comes in. Look at phase view, frequency view,
wrapped phase. Look at the ADEV, how the upper end flaps with data, but
how the same tau becomes more and more stable as it comes 
in.-
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, February 21, 2020, 9:26:47 PM EST, Magnus Danielson via 
time-nuts  wrote:  
 
 Hi Taka,

On 2020-02-21 23:26, Taka Kamiya via time-nuts wrote:
> I'm sorry, I messed up.  I jumped on more advance topic than I intended.  I'm 
> sure there were answers in the replies but they must have gone way over my 
> head because some of original questions still remain.  I bulletized (is that 
> a word?) the original question with my NEW understanding.  Would someone 
> please respond for me, point-to-point?
No problem. No worries. I hope you end up reading these and the other
replies again and acquire good knowledge. I know it's like drinking from
a fire-hoze, but you did ask some very relevant and fair questions.
>
> 1)  A frequency counter that measures DUT basically puts out a reading every 
> second during the measurement.  When TimeLab is well into 1000s or so, it is 
> still reading every second; it does not change the gate time to say, 1000s.  
> I understand now, Adev is about phase, not the frequency.  But assuming DUT 
> is sine wave, if there is enough phase change, frequency do change.  I think 
> of phase change as frequency change that is less than full cycle.  So how 
> does counters that outputs every 1 second end up in tau of 1000s?  It will 
> entirely miss phase change that spans more than 1 cycle.

ADEV is about the frequency stability. ADEV can be calculated using
phase or frequency measures. We tend to prefer using phase measures from
Time-Interval Counters for these things.

OK, so let's say that we want to output a counter which provides output
of frequency estimates but for a time-base which is longer than 1 s,
even if we output results every 1 s?

Classically counters could not do that. You acquired a start-value,
waited the time-base, acquired a stop-value, calculated a result to
display and then arm to get a new start-value for the next result. Such
counters will have a limit that the rate of readings will be limited by
the time-base, so if it is set to 10 s, only every 10 s and output is
produced.

To tackle this, one needs a counter that can interleave frequency
measurements, so that it generates new start-points at the update rate
even if the stop-point has not occurred. So, for a time-base of 10 s and
an update rate of 1 s, then every 1 s a new start-trigger is produced,
and then remembered until a stop trigger can be produced, at which time
the start-trigger 10 s back is used to estimate the frequency. In fact,
for this to work, the stop trigger time-stamp is also the start trigger
time-stamp for a new measurement. You can do this with any time-base
really, and the degree of interleaving only depends on the number of
start-points one can keep in memory.

> 2)  I recall reading on TICC manual, in time interval mode, anything that's 
> reasonably good is good enough, because it has time stamp and the count 
> reading.  Clock is used to chunk the data.  Is this still true?  Through this 
> discussion, I ended up with conclusion that there is no inherent advantage 
> over TI measurement when compared to frequency measurement.  Am I 
> understanding this correctly?

There is benefits in time-measures over frequency measures when one
monitors

Re: [time-nuts] A simple sampling DMTD

[Taka Kamiya via time-nuts]

I woke up this morning, check my HP105B, it's absolutely going nuts.  Heater 
temp down, frequency ALL OVER the place.  No output in any of the ports.  
Sigh.  eBay strikes again!

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, February 23, 2020, 7:52:02 PM EST, Bob kb8tq via time-nuts 
 wrote:  
 
 Hi

Ok, but thats “high pass in the RF section”. You really do not have an audio 
high pass 
filter the way you would in a more typical DMTD. 

If it’s any comfort, I’m sitting here looking at a very different box. It also 
has “wobbles”
as you get into parts in 10^-16. That might change a bit if the draft coming 
through the
window was a bit less.

Bob

> On Feb 23, 2020, at 6:12 PM, Jan-Derk Bakker  wrote:
> 
> Dear Bob,
> 
> The capacitors are 47n NP0/C0G types (Kemet C0805C473K3GAC7800), picked for 
> low tempco (and low DF and other non-ideal behavior). I've not spotted any 
> hysteresis artefacts in these in previous designs, but I haven't measured 
> their performance in this circuit.
> 
> Forgot to mention in the previous message: the baluns are transformers 
> (M/A-COM MABAES0060), so the only DC the ADC should see is its own input 
> offset (plus offset current across the 25R input filter resistors). Full 
> schematic is here ( http://www.lartmaker.nl/time-nuts/DMTD_rev0.99.pdf 
>  ; needs cleanup, but all 
> connections are there).
> 
> JDB.
> 
> On Sun, Feb 23, 2020 at 10:13 PM Bob kb8tq  > wrote:
> Hi
> 
> What does the temperature coefficient of your “hardware HPF” filter caps look 
> like?
> Are they a type that has significant hysteresis?
> 
> Bob
> 
> > On Feb 23, 2020, at 3:05 PM, Jan-Derk Bakker via time-nuts 
> > mailto:time-nuts@lists.febo.com>> wrote:
> > 
> > Dear Attila,
> > 
> > Thanks for the heads up.
> > 
> > I am currently using a HPF both in hardware (capacitive coupling into the
> > balun driving the ADC inputs) and in software before the ZCD. This should
> > counteract the first-order effects of this offset, although second-order
> > effects (converter nonlinearity et al) will of course still be an issue.
> > The plots you've quoted include (different kinds of) DC offset correction
> > for all but the "unfiltered" data; getting an efficient DC offset
> > correction working in real time on this 8-bit platform was indeed one of
> > the main challenges of the software-only approach.
> > 
> > The FPGA daughterboard is currently in production at Eurocircuits; I hope
> > to have time to work on those the coming month. I'll also try to book some
> > time in our climate chamber. (I've had one of our GPSDO-designs running in
> > our general labs since before Christmas; surrounding it with bottles of
> > water works well enough to low pass filter temperature swings, but I still
> > see 6 degrees C swings overnight as out HVAC only runs during business
> > hours.)
> > 
> > To be continued,
> > 
> > JDB.
> > 
> > On Sun, Feb 23, 2020 at 8:11 PM Attila Kinali via time-nuts <
> > time-nuts@lists.febo.com > wrote:
> > 
> >> Good evening!
> >> 
> >> I'm going through some old stuff...
> >> 
> >> 
> >> On Wed, 27 Nov 2019 00:29:19 +0100
> >> Jan-Derk Bakker mailto:jdbak...@gmail.com>> wrote:
> >> 
> >>> This has yielded a combined "simple" signal
> >>> processing path of a differentiator, a double comb filter and the offset
> >>> estimator, which is getting very close in performance to the "ideal" band
> >>> pass filter (OADEV of 3.77e-13@tau=1s versus 3.25e-13@tau=1s for the
> >> BPF;
> >>> full plot:
> >>> 
> >> http://www.lartmaker.nl/time-nuts/DMTD%20self-noise%20OADEV%20with%20PLL%20and%20various%20filters.pdf
> >>  
> >> 
> >>> for this 60-second recording:
> >>> 
> >> http://www.lartmaker.nl/time-nuts/600ksec%20run%20with%20PLL,%2010811%20through%20splitter.png
> >>  
> >> 
> >>> . OADEV past ~1000sec is severely compromised by the fact that the
> >>> measurement setup is in my home lab which sees temperature swings of up
> >> to
> >>> 20 degrees C and which does get bumped from time to time. Longer runs in
> >> a
> >>> more controlled setting forthcoming).
> >> 
> >> 
> >> I can offer an explanation for the large effect of the zero correction seen
> >> here. The LTC2140 is specified to have a +/-10µV/°C drift (at 1Vpp
> >> setting).
> >> Converted into phase error due to zero crossing shift, this turns into
> >> a phase shift of +/-1ps/°C @ 10MHz. Note, the shift is given as +/- and
> >> per channel, which means, it could very well be that the channels are
> >> not matched in their temperature characteristics and thus the total phase
> >> shift could be +/-2ps/°C ... though total shift being closer to 0.5ps/°C is
> >> more likely.

Re: [time-nuts] A simple sampling DMTD

[Taka Kamiya via time-nuts]

I took over master bedroom for my lab, and I have a gate for dog entry 
prevention.  All cables are over-head.  I need protection from 2 legged and 4 
legged variety.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, February 24, 2020, 10:47:20 AM EST, Bob kb8tq via time-nuts 
 wrote:  
 
 Hi

…… looking at the data this morning. It appears that in my case *somebody* 
(I’m blaming the dog) must have bumped the setup. There is a very obvious 
set of steps in the phase data. The overnight run has no similar steps. 
Sometimes
getting everything away from the test is a good thing …..

Bob

> On Feb 23, 2020, at 7:51 PM, Bob kb8tq  wrote:
> 
> Hi
> 
> Ok, but thats “high pass in the RF section”. You really do not have an audio 
> high pass 
> filter the way you would in a more typical DMTD. 
> 
> If it’s any comfort, I’m sitting here looking at a very different box. It 
> also has “wobbles”
> as you get into parts in 10^-16. That might change a bit if the draft coming 
> through the
> window was a bit less.
> 
> Bob
> 
>> On Feb 23, 2020, at 6:12 PM, Jan-Derk Bakker > > wrote:
>> 
>> Dear Bob,
>> 
>> The capacitors are 47n NP0/C0G types (Kemet C0805C473K3GAC7800), picked for 
>> low tempco (and low DF and other non-ideal behavior). I've not spotted any 
>> hysteresis artefacts in these in previous designs, but I haven't measured 
>> their performance in this circuit.
>> 
>> Forgot to mention in the previous message: the baluns are transformers 
>> (M/A-COM MABAES0060), so the only DC the ADC should see is its own input 
>> offset (plus offset current across the 25R input filter resistors). Full 
>> schematic is here ( http://www.lartmaker.nl/time-nuts/DMTD_rev0.99.pdf 
>>  ; needs cleanup, but 
>> all connections are there).
>> 
>> JDB.
>> 
>> On Sun, Feb 23, 2020 at 10:13 PM Bob kb8tq > > wrote:
>> Hi
>> 
>> What does the temperature coefficient of your “hardware HPF” filter caps 
>> look like?
>> Are they a type that has significant hysteresis?
>> 
>> Bob
>> 
>> > On Feb 23, 2020, at 3:05 PM, Jan-Derk Bakker via time-nuts 
>> > mailto:time-nuts@lists.febo.com>> wrote:
>> > 
>> > Dear Attila,
>> > 
>> > Thanks for the heads up.
>> > 
>> > I am currently using a HPF both in hardware (capacitive coupling into the
>> > balun driving the ADC inputs) and in software before the ZCD. This should
>> > counteract the first-order effects of this offset, although second-order
>> > effects (converter nonlinearity et al) will of course still be an issue.
>> > The plots you've quoted include (different kinds of) DC offset correction
>> > for all but the "unfiltered" data; getting an efficient DC offset
>> > correction working in real time on this 8-bit platform was indeed one of
>> > the main challenges of the software-only approach.
>> > 
>> > The FPGA daughterboard is currently in production at Eurocircuits; I hope
>> > to have time to work on those the coming month. I'll also try to book some
>> > time in our climate chamber. (I've had one of our GPSDO-designs running in
>> > our general labs since before Christmas; surrounding it with bottles of
>> > water works well enough to low pass filter temperature swings, but I still
>> > see 6 degrees C swings overnight as out HVAC only runs during business
>> > hours.)
>> > 
>> > To be continued,
>> > 
>> > JDB.
>> > 
>> > On Sun, Feb 23, 2020 at 8:11 PM Attila Kinali via time-nuts <
>> > time-nuts@lists.febo.com > wrote:
>> > 
>> >> Good evening!
>> >> 
>> >> I'm going through some old stuff...
>> >> 
>> >> 
>> >> On Wed, 27 Nov 2019 00:29:19 +0100
>> >> Jan-Derk Bakker mailto:jdbak...@gmail.com>> wrote:
>> >> 
>> >>> This has yielded a combined "simple" signal
>> >>> processing path of a differentiator, a double comb filter and the offset
>> >>> estimator, which is getting very close in performance to the "ideal" band
>> >>> pass filter (OADEV of 3.77e-13@tau=1s versus 3.25e-13@tau=1s for the
>> >> BPF;
>> >>> full plot:
>> >>> 
>> >> http://www.lartmaker.nl/time-nuts/DMTD%20self-noise%20OADEV%20with%20PLL%20and%20various%20filters.pdf
>> >>  
>> >> 
>> >>> for this 60-second recording:
>> >>> 
>> >> http://www.lartmaker.nl/time-nuts/600ksec%20run%20with%20PLL,%2010811%20through%20splitter.png
>> >>  
>> >> 
>> >>> . OADEV past ~1000sec is severely compromised by the fact that the
>> >>> measurement setup is in my home lab which sees temperature swings of up
>> >> to
>> >>> 20 degrees C and which does get bumped from time to time. Longer runs in
>> >> a
>> >>> more controlled setting forthcoming).
>> >> 
>> >> 
>> >> I can offer an explanation for the large effect of the zero correction 
>> >> 

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

[Taka Kamiya via time-nuts]

As I understand, 3 cornered hat is nothing more than system of equations where 
you have 3 variables and 3 equations, that allows for solving for each.  I'm 
going to hold off on that one.  I forgot about thermal and equipment's internal 
noise.  It all makes sense.  I hope to be doing some measuring this weekend if 
all works as planned (hope, hope, hope)
I mentioned earlier, I have various standards.  I also have TAPR's board to 
create 1 pps from any standards I have.  To start and follow your last example 
on how-to, what would you recommend for DUT and the standard?  I'd like to do 
one that I can show you, and immediately say if it's what you'd expect or not.
I have newly repaired HP105B, PRS10, Efratom FRK-c?, LPRO-101, and various 
GPSDO including T-bolt proper.  For the counter, I think I'll use the old HP 
interval counter, rather than 50132A.  The latter is all menu driven.  It's so 
easy to mis-set or otherwise screw it up and not notice it.  HP5370A is all 
switches and knobs.  How long of measurement?  In my experience, 2 days will 
show the inflection point.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, February 22, 2020, 3:03:37 AM EST, Magnus Danielson via 
time-nuts  wrote:  
 
 Hi Taka,

On 2020-02-22 04:55, Taka Kamiya via time-nuts wrote:
> It's not like drinking from a fire hydrant.  It's like drowning in hoover 
> dam, get sucked into an inlet, pulverized by turbine blade, and getting spit 
> out into a stream.  
Hmm, not exactly what I had hoped for as your experience... whatever,
hope it is worth it.
>
> One question :  
>
> You said this: 
> "The resolution of your counter tells you about where your 1/tau curve
> will cut tau = 1 s, and it goes from there. There is a slight scaling
> factor, but if we assume it is 1 for now, it is pretty simple. Your
> 5335A has 1 ns single-shot resolution, this gives 1E-9 at 1 s, but 1E-10
> at 10 s, 1E-11 at 100 s and 1E-12 at 1000 s. You see very clearly when
> the linear slope ends and "lands" in the noise, at which time the noise
> becomes dominant and is giving you the interesting reading."
> By using the same logic, I can keep going up and up on longer gate time and 
> tau keeps getting better and better.  I know at one point, inflection happens 
> and that indicates noise taking over.  But what kind of noise (phase?) and 
> how does that happen?

OK. Good question.

The instrument noise in itself can be while phase noise and flicker
phase noise. The resolution limit will be a systematic disturbance. All
these three has the same 1/tau slope so from these three, nothing
happens as tau increases. At some point naturally will thermal
instability come in, but that will be another systematic, but it will be
hard to cancel. So that is the limit of the instrument.

However, the noise of the reference and DUT will dominate for larger
taus, and thus it will be good enough to measure that noise. Besides,
length of measurement becomes a limit.

>   Only thing that changes in this equation is the gate time.  Everything is 
> constant.  You mean gate time is no longer accurate enough to support the 
> minute shift in phase?
> I'm still confused about the precision (not accuracy) of the time base.  Am I 
> still ultimately constrained by this?
There are ways to get around it.
>   Without DMTD, or some kind of pre-scaling of DUT, if I measure Rb with time 
> base using another Rb, they are both rubber-bands, correct?
Now, what you can do is to do a three-cornered hat measurement.
Essentially you measure three sources at once as three pair-wise
measurements. You calculate your ADEV of each pair. Now, as you have the
noises n1, n2 and n3 of each source, measurement m1 = n1+n2, m2 = n1+n3
and m3 = n2+n3. This equation problem can be solved to bring out n1, n2
and n3 separate. The trouble is, this does not always work out as
precisely as one would like, because the measurements isn't precise and
well converged. Therefore it is a bit of sensitive process, but if one
gets it working, you can achieve the separation.
> I'm infinitely curious by nature.  I need to know everything, even to a 
> minute detail, to be satisfied.  I hope you don't get tired of this.    

So far, you ask relevant questions that can be given an answer. Being a
curious person myself, I've digged down.

Cheers,
Magnus



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Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

[Taka Kamiya via time-nuts]

It's not like drinking from a fire hydrant.  It's like drowning in hoover dam, 
get sucked into an inlet, pulverized by turbine blade, and getting spit out 
into a stream.  

One question :  

You said this: 
"The resolution of your counter tells you about where your 1/tau curve
will cut tau = 1 s, and it goes from there. There is a slight scaling
factor, but if we assume it is 1 for now, it is pretty simple. Your
5335A has 1 ns single-shot resolution, this gives 1E-9 at 1 s, but 1E-10
at 10 s, 1E-11 at 100 s and 1E-12 at 1000 s. You see very clearly when
the linear slope ends and "lands" in the noise, at which time the noise
becomes dominant and is giving you the interesting reading."
By using the same logic, I can keep going up and up on longer gate time and tau 
keeps getting better and better.  I know at one point, inflection happens and 
that indicates noise taking over.  But what kind of noise (phase?) and how does 
that happen?  Only thing that changes in this equation is the gate time.  
Everything is constant.  You mean gate time is no longer accurate enough to 
support the minute shift in phase?
I'm still confused about the precision (not accuracy) of the time base.  Am I 
still ultimately constrained by this?  Without DMTD, or some kind of 
pre-scaling of DUT, if I measure Rb with time base using another Rb, they are 
both rubber-bands, correct?
I'm infinitely curious by nature.  I need to know everything, even to a minute 
detail, to be satisfied.  I hope you don't get tired of this.    
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, February 21, 2020, 9:26:47 PM EST, Magnus Danielson via 
time-nuts  wrote:  
 
 Hi Taka,

On 2020-02-21 23:26, Taka Kamiya via time-nuts wrote:
> I'm sorry, I messed up.  I jumped on more advance topic than I intended.  I'm 
> sure there were answers in the replies but they must have gone way over my 
> head because some of original questions still remain.  I bulletized (is that 
> a word?) the original question with my NEW understanding.  Would someone 
> please respond for me, point-to-point?
No problem. No worries. I hope you end up reading these and the other
replies again and acquire good knowledge. I know it's like drinking from
a fire-hoze, but you did ask some very relevant and fair questions.
>
> 1)  A frequency counter that measures DUT basically puts out a reading every 
> second during the measurement.  When TimeLab is well into 1000s or so, it is 
> still reading every second; it does not change the gate time to say, 1000s.  
> I understand now, Adev is about phase, not the frequency.  But assuming DUT 
> is sine wave, if there is enough phase change, frequency do change.  I think 
> of phase change as frequency change that is less than full cycle.  So how 
> does counters that outputs every 1 second end up in tau of 1000s?  It will 
> entirely miss phase change that spans more than 1 cycle.

ADEV is about the frequency stability. ADEV can be calculated using
phase or frequency measures. We tend to prefer using phase measures from
Time-Interval Counters for these things.

OK, so let's say that we want to output a counter which provides output
of frequency estimates but for a time-base which is longer than 1 s,
even if we output results every 1 s?

Classically counters could not do that. You acquired a start-value,
waited the time-base, acquired a stop-value, calculated a result to
display and then arm to get a new start-value for the next result. Such
counters will have a limit that the rate of readings will be limited by
the time-base, so if it is set to 10 s, only every 10 s and output is
produced.

To tackle this, one needs a counter that can interleave frequency
measurements, so that it generates new start-points at the update rate
even if the stop-point has not occurred. So, for a time-base of 10 s and
an update rate of 1 s, then every 1 s a new start-trigger is produced,
and then remembered until a stop trigger can be produced, at which time
the start-trigger 10 s back is used to estimate the frequency. In fact,
for this to work, the stop trigger time-stamp is also the start trigger
time-stamp for a new measurement. You can do this with any time-base
really, and the degree of interleaving only depends on the number of
start-points one can keep in memory.

> 2)  I recall reading on TICC manual, in time interval mode, anything that's 
> reasonably good is good enough, because it has time stamp and the count 
> reading.  Clock is used to chunk the data.  Is this still true?  Through this 
> discussion, I ended up with conclusion that there is no inherent advantage 
> over TI measurement when compared to frequency measurement.  Am I 
> understanding this correctly?

There is benefits in time-measures over frequency measures when one
monitors long-term properties. Also, as one tries to create a
phase-curve from frequency

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

[Taka Kamiya via time-nuts]

I was in electronics in big ways in 70s.  Then had a long break and came back 
to it in last few years.  Back then, if I wanted 1s resolution, the gate time 
had to be 1s.  So measuring ns and ps was pretty much impossible.  As I 
understand it, HP53132A (my main counter) takes thousands of samples (I assume 
t samples) to arrive at most likely real frequency.  That was something I had 
hard time wrapping my head around.  

I understand most of what you said, but I've never taken statistics, so I am 
guessing on some part.  I can see how adev goes down as tau gets longer.  
Basically, averaging is taking place.  But I am still not sure why at some 
point, it goes back up.  I understand noise will start to take effect, but the 
same noise has been there all along while adev was going down.  Then, why is 
this inflection point where sign of slope suddenly changes?  

Also, to reach adev(tau=10), it takes longer than 10 seconds.  Manual for 
TimeLab basically says more samples are taken than just 10, but does not 
elaborate further.  Say it takes 50 seconds to get there, and say that's the 
lowest point of adev, does that mean it is the best to set gate time to 10 
second or 50 second?  (or even, take whatever gate time and repeat the 
measurement until accumulated gate time equals tau?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, February 20, 2020, 7:54:22 PM EST, Magnus Danielson 
 wrote:  
 
 Hi Taka,

On 2020-02-20 19:40, Taka Kamiya via time-nuts wrote:
> I have a question concerning frequency standard and their Allen deviation.  
> (to measure Allen Dev in frequency mode using TimeLab)
>
> It is commonly said that for shorter tau measurement, I'd need OCXO because 
> it's short tau jitter is superior to just about anything else.  Also, it is 
> said that for longer tau measurement, I'd need something like Rb or Cs which 
> has superior stability over longer term.
Seems reasonably correct.
> Here's the question part.  A frequency counter that measures DUT basically 
> puts out a reading every second during the measurement.  When TimeLab is well 
> into 1000s or so, it is still reading every second; it does not change the 
> gate time to say, 1000s.
> That being the case, why this consensus of what time source to use for what 
> tau?
> I recall reading on TICC, in time interval mode, anything that's reasonably 
> good is good enough.  I'm aware TI mode and Freq mode is entirely different, 
> but it is the same in fact that measurement is made for very short time span 
> AT A TIME.
> I'm still trying to wrap my small head around this.  

OK.

I can understand that this is confusing. You are not alone being
confused about it, so don't worry.

As you measure frequency, you "count" a number of cycles over some time,
hence the name frequency counter. The number of periods (sometimes
called events) over the observation time (also known as time-base or
tau) can be used to estimate frequency like this:

f = events / time

while it is practical that average period time becomes

t = time / events

In modern counters (that is starting from early 70thies) we can
interpolate time to achieve better time-resolution for the integer
number of events.

This is all nice and dandy, but now consider that the start and stop
events is rather represented by time-stamps in some clock x, such that
for the measurements we have

time = x_stop - x_start

This does not really change anything for the measurements, but it helps
to bridge over to the measurement of Allan deviation for multiple tau.
It turns out that trying to build a standard deviation for the estimated
frequency becomes hard, so that is why a more indirect method had to be
applied, but the Allan deviation fills the role of the standard
deviation for the frequency estimation of two phase-samples being the
time-base time tau inbetween. As we now combine the counters noise-floor
with that of the reference, the Allan deviation plots provide a slopes
of different directions due to different noises. At the lowest point on
the curve, is where the least deviation of frequency measurement occurs.
Due to the characteristics of a crystal oscillator to that of the
rubidium, cesium or hydrogen maser, the lowest point occurs at different
taus, and provide different values. Lowest value is better, so there is
where I should select the time-base for my frequency measurement. So,
this may be at 10 s, 100 s or 1000 s, which means that the frequency
measurement should be using start and stop measurements with that
distance. OK, fine. So what about TimeLab in all this. Well, as we
measure with a TIC we collect a bunch of phase-samples at some base
rate, such as 10 Hz or whatever. TimeLab and other tools can then use
this to calculate Allan Deviation for a number of different taus simply
by using three samples, these being tau in between and algoritmically do
that for

[time-nuts] Frequency standards for different tau in Allen Dev measurement

[Taka Kamiya via time-nuts]

I have a question concerning frequency standard and their Allen deviation.  (to 
measure Allen Dev in frequency mode using TimeLab)

It is commonly said that for shorter tau measurement, I'd need OCXO because 
it's short tau jitter is superior to just about anything else.  Also, it is 
said that for longer tau measurement, I'd need something like Rb or Cs which 
has superior stability over longer term.
Here's the question part.  A frequency counter that measures DUT basically puts 
out a reading every second during the measurement.  When TimeLab is well into 
1000s or so, it is still reading every second; it does not change the gate time 
to say, 1000s.
That being the case, why this consensus of what time source to use for what tau?
I recall reading on TICC, in time interval mode, anything that's reasonably 
good is good enough.  I'm aware TI mode and Freq mode is entirely different, 
but it is the same in fact that measurement is made for very short time span AT 
A TIME.
I'm still trying to wrap my small head around this.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Using a common power supply among few time standards

[Taka Kamiya via time-nuts]

Yes, I did consider use of a second linear supply for 12V.  But decided against 
it.  This particular project was to use ONE 24V supply only.  This is because 
of my previous project.  Also the issue with another 12V linear is that these 
open frame supplies are awfully inefficient.  They generate enormous amount of 
heat for little current.  Since this is a rubidium box, heat management was 
important.

On previous project, I used 24V linear supply, and 12V switcher supply.  AND 5V 
DC/DC off 24V, 5V 3 terminal off 12v, and 3.3V internal to one device.  Each 
was routed all over the place.  The end result was a good working system.  But 
ground situation became very complicated.  I was very concerned because EFC can 
easily be affected.

This is still a work in progress.  There is already a plan for 3rd iteration 
with GPDSO, and 4th iteration with OCXO.  I'd expect similar problems.  I'm 
still debating a good design as OCXO requires +/-5V supply that has to be very 
clean and stable.  

At one point, I plan to remake the first project.  Besides the fact it works, I 
didn't practice good engineering process.  Lack of foresight and slapping on 
STUFF as needed led to this awful configuration.  There got to be a much better 
way, and I got to get there for my own satisfaction.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, February 12, 2020, 9:49:42 PM EST, Charles Steinmetz 
 wrote:  
 
 Taka Kamiya wrote:

> I started with 24V linear power supply (open frame type).  This is the only 
> power supply in the box.  From there, it branches to Rb, a small dist amp, 
> and a simple interface circuit.  Dist amp is 12V rated and interface is 5V.  
> I modified the dist amp by including a 3 terminal regulator.  *  *  *  I 
> crated a 5V source right at Rb's interface board to be used as EFC power.  
> This is the only purpose of this branch.  I also created a separate 5V for 
> the simple interface circuit.
>
>  *  *  *  EFC circuit was fine but digital interface board killed the 
>regulator. Put a heat sink on it and issue is resolved.  A bit surprising but 
>it shouldn't be  The circuit only uses 25mA or so but voltage drop is 
>huge.  *  *  *  I will have to consider use of small smp board for large 
>voltage drops.

Good idea to use two, 5 V supplies in this situation.

The EFC circuit presumably draws no more than 0.5 mA, so regulator power 
dissipation is probably at most 19 V x 0.5 mA, or <10 mW.  As you found, 
no problem.

At ~ 25 mA, the interface board dissipates ~ 19 V x 25 mA, or ~ 500 mW. 
  As you found, nothing a moderate heatsink can't handle.  But you don't 
have to dissipate all 500 mW in the regulator.  For example, you could 
feed the 5 V regulator from the 24 V supply through a 400 ohm, 1 W 
resistor (putting a capacitor of, say, 470 uF to ground at the input of 
the 5 V reg).  This would share the ~500 mW dissipation equally between 
the 5 V regulator and the resistor.  (A 10v, 1 W  zener diode would also 
work.)

Another option would be to use two, mains-powered linear power supplies 
-- one 24v supply, and one 12v supply.  Then sub-regulate the two 5v 
supplies from the 12v supply rather than from 24v.

> My only remaining concern is if regulator fails short, then what happens??  
> It will kill the particular device, which I'm fine with, but what else?  
> Perhaps simple fuse is in order for every branch.

A fuse by itself will not necessarily open in this situation.  If you 
are worried about failing short, use a simple zener diode crowbar with 
the protective fuse.  Use a shunt zener with a breakdown voltage about 
2v greater than the regulated power supply voltage across the load, fed 
through the protective fuse.  The fuse should be rated at about 200% of 
the load current.  The zener must be sufficiently robust to withstand 
the fault current until the fuse opens.

With a zener rated 2v greater than the operating voltage, there is a 
good chance the downstream load will survive without damage.

Best regards,

Charles



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[time-nuts] Tbolt and LOCK indicator - is it there?

[Taka Kamiya via time-nuts]

I have a few red labeled retail version of an older t-bolt.  I'm wondering if 
there is a signal somewhere that will indicate LOCK condition.  I know I can 
read the TSIP output and parse it, but all I need is just a simple LED.  It's 
not anywhere in its manual and I have not seen anyone mention it or even 
discuss it.  Has anyone poked around inside?  Is there a secret test point 
somewhere?
Thank you.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Using a common power supply among few time standards

[Taka Kamiya via time-nuts]

I spent last two days boxing  up LPRO-101 into a 2U rack case.  It has Rb, dist 
amp, interface for LED, and EFC knob on front.  While doing so, I gave power 
supply concern I have been discussing careful thought.  I believe I came to 
something that is workable and fits my needs.  

I started with 24V linear power supply (open frame type).  This is the only 
power supply in the box.  From there, it branches to Rb, a small dist amp, and 
a simple interface circuit.  Dist amp is 12V rated and interface is 5V.  I 
modified the dist amp by including a 3 terminal regulator.  Now, it's a 24V 
device.  I crated a 5V source right at Rb's interface board to be used as EFC 
power.  This is the only purpose of this branch.  I also created a separate 5V 
for the simple interface circuit. The reason for two 5V supply is that I didn't 
want to mix the source for EFC and digital circuit together.

Pretty quickly, I found out going from 24V to 5V incurs huge loss resulting in 
heat and death of 3 terminal regulator for that branch.  EFC circuit was fine 
but digital interface board killed the regulator. Put a heat sink on it and 
issue is resolved.  A bit surprising but it shouldn't be  The circuit only 
uses 25mA or so but voltage drop is huge.
Basically, I'm doing the same thing S100 bus computers did.  I will have to 
consider use of small smp board for large voltage drops.  I didn't this time, 
as its noise profile is not known to me.  Can't really go wrong with linear 
regulators.  My only remaining concern is if regulator fails short, then what 
happens??  It will kill the particular device, which I'm fine with, but what 
else?  Perhaps simple fuse is in order for every branch.  

This method is a lot simpler than hap-haphazardly creating multiple voltage at 
power supply and routing all over the place.  It became impossible to trace 
ground loops.  Above method makes it really easy as, as far as power supply is 
concerned, everything is a 24V device.
Thanks everyone for discussions.  I learned a lot in this process.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, February 8, 2020, 9:52:02 PM EST, Charles Steinmetz 
 wrote:  
 
 Chris wrote:

> How about using the open frame linear supplies like the ones from Power One 
> or Lambda?

I have had very good results with Deltron open-frame linear supplies. 
They have selectable mains voltage and low output noise (1mVrms/5mVp-p). 
  I have used many (i.e., hundreds) of the Model W303E triple-output 
supply.  These have one, 5v/8A section and two sections, each selectable 
between 5v/12v/15v at 0.7A/1.7A/1.5A.  [*NOTE* there is an overall 55W 
output limit, so they will not do all of that at once.]  Each section 
can be adjusted +/- 5%.  These show up regularly on ebay.

As for switchers, I have been satisfied with the performance of 
Integrated Power Designs (IPD) products.  [IPD is a different company 
than Power Designs, who made some of the best lab and bench power 
supplies of the 1960s through 1990s.]  One in particular may be of 
interest to time nuts: the Model SRW-65-4006.  This is a four-output 
supply (5v/5A, 24v/1A, and +/-15v/2A) [*NOTE* again, there is a 65W 
overall limit, so it won't do all of that at once].  It is available 
open-frame or with a chassis and cover.  For installation close to other 
circuitry, and particularly inside a piece of equipment, I strongly 
recommend the model with both chassis and cover (options CH and CO). 
Check ebay and look at distributors.

Assume you will need to post-filter the switcher output, either with L/C 
filters or low noise linear regulators.  Note that I did not say "LDOs". 
  I don't know why, but everyone seems to be stuck on LDOs these days. 
Active regulators (including LDOs) *always* perform better with more 
headroom (up to 4v or so).  The only excuse for designing LDO is if you 
have a gun to your head from a power budget you can't otherwise control. 
  [Here, "LDO" is mostly a matter of how you use the part, not of its 
claimed capabilities -- "LDO" regulators work much better with at least 
4v of headroom.]

Best regards,

Charles



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Re: [time-nuts] Using a common power supply among few time standards

[Taka Kamiya via time-nuts]

I *just* put pieces together for my project.  It's in a 2U rack case.  AND 
REALIZED RACK FLANGE IS ON BACK PANEL!  Geez...  Now, I have to re-drill some 
holes and turn it around.  This particular case has integrated flange.  It's 
part of the side panel - and power supply is mounted there.  I can't believe I 
did that.
Bert, 
I saw some advertisement on Amazon where other companies are starting to use MW 
logo and Mean Well name on their product.  When I looked at it, it was clear 
the unit itself isn't MeanWell.  I'm thinking before too long, there will be 
counterfeit one floating around  I guess the name and reputation is 
starting to develop and unethical companies are piggy backing on their name.


--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, February 8, 2020, 5:59:12 PM EST, ew via time-nuts 
 wrote:  
 
 Thank you for your warning. Have not bought Traco but was considered after 
Poul-Henning recommendation. Will stay with Mean Well have plenty good 
experience,  a couple % more efficiency was tempting no more         
Bert Kehren


In a message dated 2/8/2020 4:43:02 PM Eastern Standard Time, 
megaflu...@gmail.com writes:

Hi Bert,

Make sure to measure the noise on the Traco (on both input and output)
We had some issue with noise from a couple of Traco models at work. We
changed to Mean Well, and much less noise

Br,
Askild

On Sat, Feb 8, 2020 at 8:10 PM ew via time-nuts 
wrote:

> Just got this in the mail I am sure they have related items.
> We use with very good results Mean Well SD DC/DC products, for my Rb 8607
> project I plan on using Traco Power
>
> https://www.maximintegrated.com/en/design/reference-design-center/ref-circuits/7055.html?utm_source=Eloqua_medium=email_content=REFDES1234_campaign=FY20_Q3_2020_FEB_ALL-BU_AMER_EE-Mail_EN
> Bert Kehren
>
> In a message dated 2/8/2020 11:45:09 AM Eastern Standard Time,
> kd4...@gmail.com writes:
>
> Hi Taka,
>
> How about using the open frame linear supplies like the ones from Power
> One or Lambda?
> I usually pick these up when I find them, recap if needed and they're a
> cheap and easy way to get a supply.
>
> Chris
> KD4PBJ
>
> > On Feb 6, 2020, at 4:29 PM, Taka Kamiya via time-nuts <
> time-nuts@lists.febo.com> wrote:
> >
> > I have been addicted to home brewing GPSDO, Rubidium, OCXO, and etc,
> etc, etc.  I don't mean making of these from scratch but taking a surplus
> unit and encase them in ready-to-use form.  Most of them are in U2 rack
> case.
> >
> > One part of it that I really do not like is constructing a power supply
> for each and every unit I make.  Good power supplies are essential to clean
> and stable timebase, I know.  It is also heat generating as most of what I
> make use linear regulators.  But it's tedious and mandane to do it every
> single time!  So, I wanted to make a large enough power supply to provide
> +24V, +/- 12V, and 5V.  My plan was to have independent feed line for each
> timebase unit.
> > Is this even a good idea?  I have no experience in this to make a
> reasonable judgement.  This plan would mean these power voltages will be
> fed to each components without any local regulation.  While I do plan to
> put ferrite chokes and bypass capacitors at input, but since the whole
> point is to eliminate local power supply components, there will be nothing
> else in terms of isolation.
> > Similarly, I was also thinking of having a large battery bank for 24
> volt supply.  What type of battery is irrelevant and so as charging method
> for this question.  I have heard of this being done.  But for units that
> require 24 volts, that means there is no room for any type of regulation.
> Most 24V batteries output varying voltage depending on state of charging.
> I know 12V battery can produce as high as 13.x volt.  Is anyone doing this
> type of thing on this list?  If so, would you be willing to share details?
> >
> > Appreciate any input.
> >
> > ---
> > (Mr.) Taka Kamiya
> > KB4EMF / ex JF2DKG
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Re: [time-nuts] Using a common power supply among few time standards

[Taka Kamiya via time-nuts]

Right now, my problem is where to strike a reasonable yet good compromise.
I thought of using DC/DC but these are quite noisy, and noise comes from both 
ends.  I had one powering distribution amplifiers.  For an experiment, I placed 
a ferrite bead on the output and the whole thing oscillated rail to rail.  (and 
killed the dist.amp)  Also, these things switch at very high speed where 
ability of 3 terminal regulators to reduce noise is at minimum.
On the other hand, I was playing with red label T-bolt.  This thing has 
internal DC/DC converters to take 24V and turn it into +/- 12V and 5V.  
Powering it with clean linear supply and a garden variety switcher, output was 
equally clean.  (at least far below my lab's ability to observe issues)  I saw 
no difference in output at all.  Tech support at SRS demanded I use linear 
supply for PRS-10, and declined to discuss further.  Yet, I've seen most DIY 
implementation uses switcher.  I *think* /tvb uses 48V common supply.  I also 
read a comment on this list, when one is dealing with time-nut level accuracy 
and stability, every milli-volt counts.

I guess I'll have to deal with this on case-by-case basis.  (pun intended)

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, February 8, 2020, 9:11:13 AM EST, jimlux 
 wrote:  
 
 On 2/7/20 7:01 PM, Taka Kamiya via time-nuts wrote:
> I recall S-100 scheme had an issue of per-board regulator failing short and 
> dumping 8V into bus killing rest of the system

More like the 5V regulator (most likely a trusty 7805 in a TO-3 package) 
shorting, applying 8V to all those TTL parts on the board, which die, 
and put 8V on the address and data lines.  However, I'm not sure that 
was a particularly common failure.  In many years of working with a lot 
of S100 systems, I never had that problem.

> I am thinking of making use of 28V (aircraft power supply?) regulated power 
> supply, and have local linear regulator to created needed voltages.  One 
> concern is, should I need large amount of 5V then loss will be tremendous.

Probably a better solution is multiple bulk supplies off line AC then 
regulate down. Or a DC/DC from 28V to 8V, then good linear regulator to 5V.

There's really no way around it, although you can do things like 
synchronize all your PWM converters, so if you do get spurs, they're in 
consistent places.


   I just came across an article that discussed magnetic field 
sensitivity of LPRO-101.  The author ended up relocating the transformer 
off-board.  (in a different case)  A very timely information as this is 
what I am actually working on.
> Further comment will be appreciatedTakaTime-nut in training
> ---
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
>  
> 
>      On Thursday, February 6, 2020, 6:51:38 PM EST, jimlux 
> wrote:
>  
>  On 2/6/20 3:14 PM, Will Kimber wrote:
>> Hi,
>>
>> Usual (best?) is supply slight over voltage and use LDO/RC filtering in
>> each unit as Bob suggested. But that would require either supplying
>> 24v/12v/5v/-12v (with some margin 10%?) or converting some single supply
>> of 24v or 48v  in each unit to required voltages at each piece of
>> equipment.  The later requires switching supplies to get all voltages.
> 
> 
> Well that was the strategy used on S-100 boards. Bulk 8V unregulated
> supply regulated down to 5V on the board.
> 
> 
> 
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Re: [time-nuts] Using a common power supply among few time standards

[Taka Kamiya via time-nuts]

I recall S-100 scheme had an issue of per-board regulator failing short and 
dumping 8V into bus killing rest of the system
I am thinking of making use of 28V (aircraft power supply?) regulated power 
supply, and have local linear regulator to created needed voltages.  One 
concern is, should I need large amount of 5V then loss will be tremendous.  I 
just came across an article that discussed magnetic field sensitivity of 
LPRO-101.  The author ended up relocating the transformer off-board.  (in a 
different case)  A very timely information as this is what I am actually 
working on.
Further comment will be appreciatedTakaTime-nut in training
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, February 6, 2020, 6:51:38 PM EST, jimlux 
 wrote:  
 
 On 2/6/20 3:14 PM, Will Kimber wrote:
> Hi,
> 
> Usual (best?) is supply slight over voltage and use LDO/RC filtering in
> each unit as Bob suggested. But that would require either supplying
> 24v/12v/5v/-12v (with some margin 10%?) or converting some single supply
> of 24v or 48v  in each unit to required voltages at each piece of
> equipment.  The later requires switching supplies to get all voltages.


Well that was the strategy used on S-100 boards. Bulk 8V unregulated 
supply regulated down to 5V on the board.



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[time-nuts] Using a common power supply among few time standards

[Taka Kamiya via time-nuts]

I have been addicted to home brewing GPSDO, Rubidium, OCXO, and etc, etc, etc.  
I don't mean making of these from scratch but taking a surplus unit and encase 
them in ready-to-use form.  Most of them are in U2 rack case.

One part of it that I really do not like is constructing a power supply for 
each and every unit I make.  Good power supplies are essential to clean and 
stable timebase, I know.  It is also heat generating as most of what I make use 
linear regulators.  But it's tedious and mandane to do it every single time!  
So, I wanted to make a large enough power supply to provide +24V, +/- 12V, and 
5V.  My plan was to have independent feed line for each timebase unit.
Is this even a good idea?  I have no experience in this to make a reasonable 
judgement.  This plan would mean these power voltages will be fed to each 
components without any local regulation.  While I do plan to put ferrite chokes 
and bypass capacitors at input, but since the whole point is to eliminate local 
power supply components, there will be nothing else in terms of isolation.
Similarly, I was also thinking of having a large battery bank for 24 volt 
supply.  What type of battery is irrelevant and so as charging method for this 
question.  I have heard of this being done.  But for units that require 24 
volts, that means there is no room for any type of regulation.  Most 24V 
batteries output varying voltage depending on state of charging.  I know 12V 
battery can produce as high as 13.x volt.  Is anyone doing this type of thing 
on this list?  If so, would you be willing to share details?

Appreciate any input.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Fake new LPRO 101 Rb's on Ebay?

[Taka Kamiya via time-nuts]

I am suspending purchases directly from China for now.  The whole country is in 
chaos, according to our media.  Their resources are strained.  Too many chances 
for something going wrong - ignored, lost, delayed, damaged, etc, etc, etc.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Tuesday, February 4, 2020, 2:35:56 AM EST, Poul-Henning Kamp 
 wrote:  
 
 
In message <1626784396.61618.1580801360...@mail.yahoo.com>, Perry Sandeen via t
ime-nuts writes:

>In all seriousness, can the coronavirus be transmitted in gear we
>buy from China or does it require a living host for spreading?

Very few vira can survive 14 days, and for all we know at present
that time is sufficient to desinfect 2019-nCov, and to detect any
infections.

A few specialized infectious agents have the ability to produce
"spores" which can survive for *long* periods of time, and then
revive on contact with humidity.  The best known example is Anthrax.

-- 
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
p...@freebsd.org        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] Cesium Mechanical Chronometer

[Taka Kamiya via time-nuts]

I used to collect old watches.  Most mechanical parts are made of brass, and 
rest of it are some type of steel (including stainless)  Getting any part of it 
magnetized is a major issue in mechanical watches.  Undoing the change may 
include demagnetizing the whole watch, which a watch maker can do.

Typically, a marine chronometers are mounted on a rotatable mount, so that the 
face of it will always face up.  When tuning a watch, a watch maker does it 
face up, face down, right side up, right side down, etc, etc, etc.  The 
oscillation rate of the balance wheel will change depending on orientation.  
Some VERY expensive mechanical watches has a part called tourbillon to 
compensate it.  Assuming the clock does not have it, (and M21 does not, as far 
as I know) and if it can be WELL characterized, perhaps this tendency can be 
used to synchronize it with an external source.
About winding, winder for mechanical (and not automatic) watches do exist.  
They attach to the crown (of the watch) and rotates it.  There is a timer and 
slip mechanism to prevent over-winding.  Typically, a crown of an automatic 
(self-winding) watches free spin with a clicking sound, and plain mechanical 
watches just stop, and won't let you wind any further.  I have never seen a 
mechanism to wind key type winding mechanism.

By the way  I have a railroad watch that is well over 100 years old.  It 
keeps +/- 1 second per day.  Amazing feat using purely mechanical parts.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, February 1, 2020, 10:40:14 PM EST, Ben Bradley 
 wrote:  
 
 I understand, though I was thinking a small coil could be placed
inside the case near the balance wheel. Worst case it seems fully
reversible (depending on mounting the coil and a small hole for the
wires to come out) and worth a try.

On Sat, Feb 1, 2020 at 10:31 PM Bob kb8tq  wrote:
>
> Hi
>
> Keep in mind that these particular chronometers were designed (as best as
> was possible) to be impervious to outside influences. Mag fields, rocking back
> and forth, orientation changes all should have whatever the lowest impact you
> could make them have.
>
> Bob
>
> > On Feb 1, 2020, at 9:58 PM, Ben Bradley  wrote:
> >
> > I'm wondering about the balance wheel, if it's ferromagnetic (has iron
> > or steel in it, which would probably make this idea not work), or if
> > it's perhaps all aluminum or similar non-magnetic material. Adding a
> > constant magnetic field from a coil and electric current source would
> > provide a magnetic induction-induced drag on the balance wheel and
> > slow it down (hopefully not so much that it stops). Setting the
> > chronometer to normally run slightly fast would allow it to be slowed
> > down and regulated by the strength of the magnetic field on the
> > balance wheel.
> >
> > On Sat, Feb 1, 2020 at 3:06 PM Bob kb8tq  wrote:
> >>
> >> Hi
> >>
> >> If the idea is to generate a rate card and keep it up to date ….. I think 
> >> that
> >> can be done with just the GPS. The CSAC really does not add a lot that
> >> I can see to that case.
> >>
> >> Of course I may have (yet again) missed something ….
> >>
> >> ==
> >>
> >> The very standard  / “old school” approach for this is a microphone on the 
> >> case
> >> of the M21. These days feed the mic preamp output into a cheap micro along
> >> with the GPS info and away you go.  Spit the results out to a little OLED 
> >> display
> >> maybe …..
> >>
> >> Bob
> >>
> >>> On Feb 1, 2020, at 1:39 PM, Tom Bales  wrote:
> >>>
> 
>  Many thanks for everyone's response on my cesium-synchronized mechanical
>  chronometer project.  I'll keep the group informed of progress.  Some
>  responses to your questions and suggestions:
> >>>
> >>>
> >>>  - My current plan is to use a chronometer that has been adjusted for
> >>>  rate and is close to dead-on.  Of course, they're never dead-on, and 
> >>>that's
> >>>  why keeping track of the rate is important.  I haven't dismissed the idea
> >>>  of actually disciplining the chrono from the CSAC, but since this 
> >>>chrono's
> >>>  rate adjustment involves screws on the balance wheel (it has a 
> >>>free-sprung
> >>>  helical balance spring without any means of adjustment), that would be a
> >>>  great challenge.  Perhaps the best would be for the CSAC system to 
> >>>maintain
> >>>  a "rate card" of the chronometer, so that when all the electronics fail,
> >>>  and the user is left with only the chrono, at least they would have a
> >>>  really good knowledge of its rate and variation.  Doing so would require 
> >>>a
> >>>  feedback signal from the chrono, which could be acoustic or 
> >>>photoelectric.
> >>>  The electronic rate card could be updated now and then by turning off the
> >>>  sync impulse to the chrono and listening for the ticks to move relative 
> >>>to
> >>>  the 1pps.
> >>>  -  The chrono would need a bigger box in order to incorporate the
> >>>  CSAC/GPS system, 

Re: [time-nuts] Cesium Mechanical Chronometer

[Taka Kamiya via time-nuts]

I don't know about older marine chronometers but modern ones tick much faster 
than 1 pps.  Most are designed to tick 28800 pph, which is 8 ticks per second.  
One jump per second is pretty much a quartz watch thing.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, January 30, 2020, 12:44:49 PM EST, Bill Slade 
 wrote:  
 
 Just a thought, as I have no experience with mechanical clocks. Couple your 
atomic clock 1pps signal to a mechanism that weakly mechanically couples to 
your chronometer spring-mass-escapement system in some way (assuming 1 tick per 
second natural frequency for your chronometer).  Rely on the entrainment 
phenomenon to synchronize the mechanical clock to the electrical signal.

Cheers!


From: time-nuts  on behalf of Tom Bales 

Sent: Thursday, January 30, 2020 4:49 PM
To: time-nuts@lists.febo.com 
Subject: [time-nuts] Cesium Mechanical Chronometer

>
> And now for something completely different:  I am working on a quixotic
> project to control a standard, detent-escapement marine chronometer (e.g.,
> Hamilton 21) with a CSAC cesium atomic clock module.  Yes, I know this
> makes no sense--but, then, we're timenuts.  I want the mechanical
> chronometer to function normally if the CSAC signal, presumably a 1pps
> pulse, is lost.  The CSAC will be GPS disciplined, so during normal
> operation, with an operating GPS constellation, the time is referenced to
> UTC via GPS; if GPS is lost, then the CSAC takes over and its 1pps signal
> drives the chronometer; if all electronics are lost, the chronometer hangs
> in as a mechanical chronometer.  Has anyone any experience with
> electrically controlling (or disciplining) a marine chronometer?
>
>
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Re: [time-nuts] Symmetricom 023-63008-07 5MHz Crystal Oscillators

[Taka Kamiya via time-nuts]

I believe the seller is in Hong Kong.  I've dealt with him before on 
Ebay."QUEENS" land

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, January 23, 2020, 12:08:23 PM EST,  wrote:  
 
 Bob,

I just might play at the mixing to see if it will work!

Hmmm, 16 oscillators give a cold current of  12.8 Amps!

The direct sellers you find with Google sell them for <$20.00 each.

One of them:

https://www.teewtfstore.com/index.php?main_page=product_info_id=
244548

This seller (can't quite figure out where they are located) Seems to
indicate Canadian dollars?

If you buy 4 or more at $13.16 CA shipping is free.

Cheers,

Corby


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Re: [time-nuts] Simple GPSDO Multiple Outputs - buffered line driver options?

[Taka Kamiya via time-nuts]

I'm not the OP but I was just throwing some ideas about cheap way to distribute.
But the responses were very timely.  I am, indeed, using HP53132A, RG58, and 
were doing ADEV measurement of a 10MHz signal.  I have my answers already so I 
won't go into details but I was seeing some explainable indications.  It might 
very likely be leak from or into the reference/input.  I will use double 
shielded and phase stable cables and see if I can eliminate the issue.

Thanks a-bunch!
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Tuesday, January 21, 2020, 4:27:26 PM EST, Bob kb8tq  
wrote:  
 
 Hi

If all you are doing is driving a 5335 and running at 1 second gate times, then 
there’s not
a lot to worry about. If indeed you are multiplying this or that up to X band 
for various purposes
then  ….. that’s different. Both are in the “hobbyist” range.

Spurs matter for some things and don’t matter much for others. A spur at -120 
at 10 MHz 
may be up around -60 db at 10 GHz. It might matter there … it might not. A -60 
db spur 
at 10 MHz gets into the “yikes” range if directly multiplied. 

How big is your bench? How long are your feed cables? You are getting into a 
significant 
fraction of a wavelength at 10’ of cable. If unterminated (and / or poorly 
shielded) it will spray
a bit of RF. 

Lots of details and no single answer without digging deeper into what you are 
trying to do.

Bob

> On Jan 21, 2020, at 4:06 PM, Bryan _  wrote:
> 
> On the point of using a MDA-3V at the hobbyist bench level, any issues that 
> one needs to be concerned about. A few modification projects online, but none 
> really comment on any issues or performance.
> 
> -=Bryan=-
> 
> 
> From: time-nuts  on behalf of Bob kb8tq 
> 
> Sent: January 21, 2020 7:57 AM
> To: Taka Kamiya ; Discussion of precise time and 
> frequency measurement 
> Subject: Re: [time-nuts] Simple GPSDO Multiple Outputs - buffered line driver 
> options?
> 
> Hi
> 
> Cross talk between the reference in and the measured signal on the 53131 
> series can be an
> issue . The counter drops resolution in the vicinity of 10 MHz as a result. 
> There is also an  issue
> with  the sampling process rather than direct feedthrough.
> 
> If you are measuring things like phase noise, having a lot of 10 MHz running 
> around the lab will put a
> spur in the phase noise plot. It may be close enough in that you don’t notice 
> it every time. The same
> sort of spur will play nasties with things like ADEV measurements. Getting a 
> 10V RMS signal down
> 120 db is tough …
> 
> Finally if you happen to be playing with radios, WWV is at 10 MHz. It does 
> not take a lot of reference
> signal to get back into the typical receiving antenna.
> 
> ==
> 
> If you are daisy chaining counters, there are several ways to do it:
> 
> 1) Drive the “ext ref in” and daisy chain off of “ext ref out”. This way the 
> signal is buffered at each device.
> It may add a bit of noise, but you can go a long way doing this.
> 
> 2) Put a coax Tee connector at each instrument. If the device is high Z in, 
> this can do ok. If it is a 50 ohm
> termination all the time … not so much. Even with the high Z input it’s 
> better for short runs than long ones.
> 
> 3) Mix the two approaches. If you have a variety of gear, use the ones with 
> ref in / ref out as buffers. String
> the other gear in-between those boxes.
> 
> Bob
> 
>> On Jan 21, 2020, at 10:27 AM, Taka Kamiya via time-nuts 
>>  wrote:
>> 
>> I've tried daisy chaining 4 HP5335A.  By the time signal got to the 4th box, 
>> it was too weak to reliably drive the 1 pps.  I had a terminator at the last 
>> tee with short length of RG58s between boxes.  I guess some box puts 
>> relatively heavy load on the signal?
>> 
>> I'd like to know why 10V is a bad idea.  (besides too close to the upper 
>> limit)  Cross talk between what/where?
>> 
>> To OP:I have video amplifiers Extron MDA-3V successfully used for this.  1 
>> port in, 3 ports out ones by Extron are very inexpensive at 10 dollars+/-.  
>> I never did formal testing but reading on all counters matched exactly.  
>> They are 75 ohms but it didn't matter in my use case.  You can change/adjust 
>> internal resisters if you are concerned.
>> 
>> ---
>> (Mr.) Taka Kamiya
>> KB4EMF / ex JF2DKG
>> 
>> 
>>  On Tuesday, January 21, 2020, 7:45:22 AM EST, Bob kb8tq  
>>wrote:
>> 
>> Hi
>> 
>> What are you driving?
>> 
>> Most “normal” gear is pretty happy with a fairly wide range of input levels. 
>> Obviously things
>> like termi

Re: [time-nuts] Simple GPSDO Multiple Outputs - buffered line driver options?

[Taka Kamiya via time-nuts]

I've tried daisy chaining 4 HP5335A.  By the time signal got to the 4th box, it 
was too weak to reliably drive the 1 pps.  I had a terminator at the last tee 
with short length of RG58s between boxes.  I guess some box puts relatively 
heavy load on the signal?

I'd like to know why 10V is a bad idea.  (besides too close to the upper limit) 
 Cross talk between what/where?  

To OP:I have video amplifiers Extron MDA-3V successfully used for this.  1 port 
in, 3 ports out ones by Extron are very inexpensive at 10 dollars+/-.  I never 
did formal testing but reading on all counters matched exactly.  They are 75 
ohms but it didn't matter in my use case.  You can change/adjust internal 
resisters if you are concerned.  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Tuesday, January 21, 2020, 7:45:22 AM EST, Bob kb8tq  
wrote:  
 
 Hi

What are you driving? 

Most “normal” gear is pretty happy with a fairly wide range of input levels. 
Obviously things
like termination and long lengths of coax can get into the act. For 4 outputs, 
a passive splitter
with 6 db of loss should do just fine. You have only taken the output voltage 
down by 2:1 ….

Just for reference:

https://www.avionteq.com/Document/53131A-specification-sheet.pdf 


Calls out a 200 mv to 10V RMS input level as acceptable For a variety of 
reasons, 10V RMS
is a really bad idea (cross talk ….). Lower is better in this case.

Bob

> On Jan 21, 2020, at 4:19 AM, skipp isaham via time-nuts 
>  wrote:
> 
> Hello once again to the Group,
> 
> May I ask what the current relatively simple options are for
> expanding a Thunderbolt or equivalent... output for distribution
> to multiple devices?
> 
> Although I expect only two or three isolated / buffered outputs
> will be required in my example. I'm worried about signal level
> if a passive system (Mini Circuits divider or equivalent type)
> is used.
> 
> Would appreciate a few quick opinions on what is practical and
> seems to work well.
> 
> thank you in advance
> 
> regards,
> 
> skipp
> 
> skipp025 at yahoo dot com
> 
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Re: [time-nuts] EFOS B Hydrogren maser arrived

[Taka Kamiya via time-nuts]

What a lucky find!  Old but works and refurbished!  Congratulations.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, December 27, 2019, 9:22:52 PM EST, Magnus Danielson 
 wrote:  
 
 Fellow time-nuts,

This afternoon my EFOS B hydrogen maser has arrived and been set up. We
just need to wait for it to lock up, which may take about a week. I can
report a lot more on it, as I have a huge stack of documents. Hydrogren
diassociator already gives that nice pink glow. Its been refurbished and
measured, so it goes to 3E-15 at least, should reach 2E-15, with out
trouble. It is a huge beast, so it took quite some effort to get the 250
kg heavy beast of the van, and in the house. Now we have enjoyed dinner
and good drinks. I will do a bit of more cleanup before I meet my final
destination for the evening, but it all looks good so far.

I have 5 MHz, 180 MHz and 1440 MHz outputs to play with.

So, I have now transitioned from OCXO, to Rubidium, to Cesium and to
Hydrogren maser.

So, this is why I think in terms of phase microstepper.

Cheers,
Magnus



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Re: [time-nuts] Power supply for time source concerns

[Taka Kamiya via time-nuts]

I just found something funny.  I have been thinking "clean" power supplies that 
connects to AC mains.  Then I thought, what about lead acid batteries??  So I 
went to my lab and took some measurement.  This is a 12V 7A lead acid sealed 
battery, the kind commonly found on UPS devices.
The result?  Surprise?  The battery is oscillating at 5MHz and noise level is 
15mV peak-to-peak
Of course, not...!  Battery is pure DC and while voltage might drift, this is 
not that.  For the record, a charger of any kind is not hooked up.  It's one 
battery all by itself.  Battery is not oscillating but that's what the 
measurement actually shows.  That brings another point in my quest to "clean" 
power source.  It's not just the power supply but the whole lab eco system has 
to be considered.  Having one master 24V source (my original plan) is not the 
answer if mV level noise is going to be a problem.  

This "discovery" puts whole new layer to having a nice power supply.

Just as a point of reference, I hooked up a common cheap float charger.  The 
charger itself has 2V p-p noise.  Connected to battery, it still have 100mV p-p 
noise.  There goes battery = noise sponge theory
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Tuesday, December 24, 2019, 3:00:50 PM EST, Bob kb8tq  
wrote:  
 
 Hi


> On Dec 24, 2019, at 6:40 AM, Poul-Henning Kamp  wrote:
> 
> 
> 
>> That again depends on topology and control type.  The canned converters 
>> are almost always optimized to have the lowest number of switches and 
>> work with cheap magnetics (single coil) without easily entering 
>> problematic operation modes, noise is only a secondary concern. 
> 
> That depends a LOT on which canned converter you decide to buy,
> if you only go after price, or W/mm³ capacity, then certainly yes.
> 
> But for a one-off application like this, any money saved on a
> cheap model is easily lost many times over in the trouble it will
> cause.
> 
> But returning to the original post:  Has anybody ever characterized
> how much difference it makes to use two different PSU's for heater
> vs. electronics sides of telecom Rb's ?

The “old time” answer was that a poorly regulated / poorly filtered supply was 
considered “ok” for a heater. For the active electronics you wanted something
nice and stable / clean. To your point, once you get around to *measuring* 
this, stability wise that answer often does not hold up. Noise wise, you are 
right 
back to “what frequency?” ….

The somewhat more complex “old time” answer was that you don’t want the 
honking big current of the heater coming off the supply you have tried so hard
to super-regulate. ( = it’s the supply that’s the issue not the Rb it’s self). 
Obviously
that’s going to depend on how the supply was designed. 

Of course next layer to the onion is …. where does the ground current go? …. 
hmm….

Bob

> 
> I'm sure there is a reason why they make it two different pins ?
> 
> -- 
> Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
> p...@freebsd.org        | TCP/IP since RFC 956
> FreeBSD committer      | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.
> 
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Re: [time-nuts] Power supply for time source concerns

[Taka Kamiya via time-nuts]

I think the conversation is going into an area way beyond my initial intent.
My goal is to have a "good enough" source for 24V to run multiple time sources. 
 Yesterday, I measured the output of switcher I've been using for testing 
purpose only.  Holy cow it's dirty!  120mV peak-to-peak wide band noise.  Put 
one ferrite bead on plus side and it had an amazing result.  Broadband noise 
disappearance and periodic pulse (still 120mV p-p)
My goal is to have about 5mV p-p or lower capable of delivering 20Amp in 
switching arrangement.  It's easy to do with linear regulators but it makes the 
room awfully warm.  Why 5mV?  Because it is good enough.  If more is necessary, 
it will have to be dealt with locally inside the time source itself.  Cabling 
can pick up that much easily.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, December 23, 2019, 1:09:58 PM EST, jimlux  
wrote:  
 
 On 12/23/19 5:42 AM, Bob kb8tq wrote:
> Hi
> 
> If you dig into the app notes on the LT304x parts after a lot of extolling the
> wonders and virtues, they eventually get into magnetic coupling between the
> “upstream” and “downstream” bypass components. Taking care of that with
> proper layout is possible, but non-trivial.

And not entirely predictable by modeling, even with the fancy 
multiphysics signal integrity modeling.

It is one of those things where you will probably need a few iterations.

> 
> Is milivolts of noise “ok”? Maybe it is. There are a lot of devices out there 
> that
> run with 10’s of milivolts of noise on the supply line. Do you need <100uV p-p
> over 10KHz to 100 MHz? There are devices that do. If that’s what you need,
> it’s going to be a struggle. There is no one single “good enough” number.
> 
> The power supply world still stops at pretty low frequencies. Very common IC’s
> these days are quite happy to produce crud at the “many GHz” level. There are
> a few folks who carry around cell phones that put out signals up there as 
> well.
> Regulator IC’s will only do part of the job, filtering in one form or the 
> other (likely
> several forms) is still needed.

Yes, I think, though, that filtering (even over multiple decades) is 
easier at higher frequencies - Assuming you can tolerate the IR voltage 
drop through the filters.


> 
> Past that system layout begins to get into the act. You can spend a couple of 
> fun
> weeks in intro level classes on this sort of stuff. You can be the prof 
> presenting the
> class and pretty quickly get to “that would require some research” as the 
> answer
> to this or that seemingly basic question. It’s not in any way a trivial topic.
> 
> So what to do?
> 
> Bottom line is still that test equipment is your friend. Spectrum analyzers 
> that cover
> a wide range of frequencies (and have good sensitivity) *are* part of the 
> “kit” that
> allows you to keep things quiet. You can only go just so far ( = not very 
> far) before
> you are into the “verify” stage of things. Indeed sound cards and SDR’s can 
> collect
> some of this data so there *are* a range of tools you can use.
> 
> Checking cabling / grounding / cross talk is very much part of setting up any 
> RF
> bench. It always has been. Tracking down that stupid whatever on the other 
> side
> of the room that is putting out a ton of noise *is* part of the drill. 
> Repeating the
> process from time to time also is part of the fun. Looking at the data you 
> collect to
> spot “strange” stuff *is* part of the deal …… There is work involved and you 
> need
> to understand what you are doing.
> 


I think understanding how the effect of unwanted interference (by 
whatever path) manifests itself in the desired output is part of the 
challenge - In many cases, the most sensitive detector of interference 
is the unit under test (certainly this is the case for a low noise 
receiver).

One thing that can help evaluate a design is it artificially introduce 
interference or noise into the power supply - if you can't see a change 
in the output of the UUT, then the filtering/isolation scheme must be 
working.  If the artificial interference is at a level that is >> the 
level you'd see in expected use, then you're in great shape.





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Re: [time-nuts] Power supply for time source concerns

[Taka Kamiya via time-nuts]

Yes.
I considered float charging a battery bank and switching power supply + linear 
regulator combination as well.  

Concern with the first is safety in charging.  I was intending to use GEL cell 
lead acid battery.  24V chargers are plentiful but there is no telling what 
they actually do.  Adding a series regulator won't work because of the required 
voltage drop with most of the 3 terminal kind.  I still want to try this as it 
will double as UPS as well.

Switcher + linear regulator sounds promising.  One unknown is, how much high 
frequency ripples/noises those regulators actually remove.  I guess I'll just 
have to try this out.  Ferrite sleeves, low pass filters, chokes, etc, etc, etc 
are under consideration.
I have a very nice lab grade switching power supply but unfortunately, this 
stupid thing resets to ZERO every time power cycled and starts up in current 
limiting mode.  Meaning if I forget to switch modes, it can go as high as 60 
volts.  By then, all devices are GONE!
My main usage will be just for time standard for my lab.  Stable 10MHz and 1 
pps is all I need to sync everything up.  I am not going to multiply output to 
GHz range or do anything else exotic.  I wonder how much ripple will actually 
affect?  


--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, December 22, 2019, 6:00:32 PM EST, jimlux  
wrote:  
 
 On 12/22/19 1:18 PM, Poul-Henning Kamp wrote:
> 
> In message <1958104416.2586171.1577043445...@mail.yahoo.com>, Taka Kamiya via 
> t
> ime-nuts writes:
> 
>> First question to the group is, how do YOU manage this problem?
> 
> It used to be that there were only one kind of switching power-supply: The 
> noisy ones.
> 
> That is no longer true by definition, but there is no easy road to this 
> particular Damascus.

My strategy is DC/DC converter to get close, and high PSRR LDO linear 
regulator to the final voltage. Close attention to the DC/DC converter 
input and output so you don't couple to the ultimate output through 
radiated or parasitic conducted paths.

The LT3042 series regulators have high PSRR, are available with negative 
voltages now, and can be paralleled for more current capacity.

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[time-nuts] Power supply for time source concerns

[Taka Kamiya via time-nuts]

Most commercially manufactured time and frequency sources use switching power 
supply.  However, when contacted, tech support for SRS says, in regards to 
PRS-10, use linear power supply.  I am guessing, when manufacturers design 
complete units, they take switching noise into consideration and deal with it 
with filtering, etc.
I've seen data on TVB's site and others that demonstrates effects of power 
supply noise.
Now, when I make DIY timing sources, I started including linear power supplies. 
 My PRS-10/GPS unit has 2.4A 24V linear supply for PRS10 and switching supply 
for stuff that really doesn't care.  It seem to work well.  But the problem is 
HEAT!  Almost all timing devices are heat sensitive and drift accordingly.  
Open frame linear supplies has efficiency of somewhere around 65 to 70%.  I 
could, for example, partition inside the case and fan cool the P/S only but 
doing so for every single DIY unit becomes tedious.
First question to the group is, how do YOU manage this problem?
My thought now is, what about making an external linear supply ONLY and supply 
all the voltages connected units could possibly need.  I could fan cool that!  
I happen to have a rack mounted UPS unit that is well beyond service life.  I 
can gut it and stuff open frame supplies to 24V, +/-12V, and 5V.  Does anyone 
see issue with this?  Of course, on timing device side, I will have to put 
large enough cap to decouple.  
PS.  I was bit by a telecom surplus time source bug.  I have various one 
already running and more on the way.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Using HP5071A with dead tube along with GPS

[Taka Kamiya via time-nuts]

My experiment is not going well so far.  I have NOT done any tuning.  Just 
connected 1 pps out from GPS to 1 pps IN on 5071A.  Frequency keeps increasing, 
which I think is weird.  I thought it might just be unstable without proper 
parameters, but no.  Over last 24 hours, it kept going up.  I was about to 
start reading the 5071A manual.  Likely as TVB says, it will likely be needing 
quite a bit of refining loop parameters.  One unknown is, in this current state 
(fault), if OCXO is even steerable.  1 pps WAS detected and menu option did 
tell me so.  

I didn't know you can put 5071A in (Cs tube only) STAND-BY mode...  Mine is 
dead so it's in permanent stand-by.  It's initial boot sequence detects this 
and shuts it down.  

On a slightly different topic, my PRS10 + GPS experiment is working rather 
well.  I haven't done any tuning and using default for everything.  I'm going 
to wait about a month before doing so.  Loop constant is 1 day, so it may take 
quite some time to completely stabilize.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, December 19, 2019, 5:34:55 PM EST, Mark Sims 
 wrote:  
 
 I've actually done this...  Lady Heather has built in "alternate disciplining" 
algorithm for the Thunderbolt.  I tricked up some code to use this along with a 
TAPR-TICC to make a GPSDO.  The first (rather crude) hack worked pretty well.  
I haven't had a chance to do it properly... yet.

The idea was to allow the 5071A to run with the CBT in standby for applications 
that do not require the cesium goodness.

-

> A fun (and actually very useful) project would be to turn it into a 
GPSDO
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[time-nuts] Using HP5071A with dead tube along with GPS

[Taka Kamiya via time-nuts]

I can't quite remember who gave me this idea...  but I'm pretty sure he was a 
member of this mailing list.
I have an HP5071A high performance version with a dead tube.  But rest of the 
unit, as far as I know, works just fine.  I know it has a PPS INPUT on it.  I 
also know it has a very good OCXO in that, too.  Would it be possible to steer 
this OCXO using GPS when Cs tube is completely dead and unlocked?  I do not 
want to take this apart, just in case nice usable tube lands in my hand in 
future.
The reason I ask...  I can just do it and see, but I have no way to verify the 
performance.  I have an old Cs with no characterization, and rest are Rbs and 
T-bolts.  Seems like what I propose would result in OCXO pulled by two 
different servos.  (and even if the results were awful, I wouldn't know it)

Happy holidays!

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] 1 pps Accuracy in two locations

[Taka Kamiya via time-nuts]

I totally messed up what I wanted to say.  Here's the corrected version.

In 1 ps, signal travels 0.3mm.  Everything has to be on one die (as in die in a 
chip) as propagation delay in cabling alone will add enough errors.

(I'm sorry tvb for creating more job for you to do)
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, December 4, 2019, 3:07:34 PM EST, Taka Kamiya via time-nuts 
 wrote:  
 
 Also, at that speed, signal travels 0.3mm per second, assuming zero velocity 
factor.  Everything will have to be on chip scale to realize that.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

    On Wednesday, December 4, 2019, 11:01:12 AM EST, Tom Van Baak 
 wrote:  
 
 Martyn,

 > I'm always being asked to provide equipment that can produce two 1
 > pps outputs aligned to each other to within a few ps.

They should look at their best 1PPS on a 'scope. You can get ns with 
care; I doubt ps is possible. I mean, that's THz BW isn't it?

Can you share with us what their application is?


 > So they are asking for two of my GNSS frequency standards with 1 pps
 > outputs.
 >
 > The 1 pps outputs being derived from the rubidium oscillator (which
 > is aligned to GPS/GNSS)
 >
 > The best I think I can achieve is in the low ns range.

Right. It will be ns, not ps. Forget about using GNSS for ps level timing.


 > Does anyone know how this can be achieved?

Google for papers by high-end national timing laboratories. Words like: 
active temperature stabilized (phase stabilized) bidirectional optical 
fiber links.

Very possible, very expensive, quite common now. I'd guess most of the 
timing centers in Europe are linked this way.

/tvb




On 12/4/2019 1:40 AM, mar...@ptsyst.com wrote:
> Hello,
>
>  
>
> I'm always being asked to provide equipment that can produce two 1 pps
> outputs aligned to each other to within a few ps.
>
>  
>
> These two 1 pps pulses are not in the same location and could be 100 metres
> to a few km away.
>
>  
>
> So they are asking for two of my GNSS frequency standards with 1 pps
> outputs.
>
>  
>
> The 1 pps outputs being derived from the rubidium oscillator (which is
> aligned to GPS/GNSS)
>
>  
>
> The best I think I can achieve is in the low ns range.
>
>  
>
> Does anyone know how this can be achieved?
>
>  
>
> Regards
>
>  
>
> Martyn
>
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Re: [time-nuts] 1 pps Accuracy in two locations

[Taka Kamiya via time-nuts]

Also, at that speed, signal travels 0.3mm per second, assuming zero velocity 
factor.  Everything will have to be on chip scale to realize that.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Wednesday, December 4, 2019, 11:01:12 AM EST, Tom Van Baak 
 wrote:  
 
 Martyn,

 > I'm always being asked to provide equipment that can produce two 1
 > pps outputs aligned to each other to within a few ps.

They should look at their best 1PPS on a 'scope. You can get ns with 
care; I doubt ps is possible. I mean, that's THz BW isn't it?

Can you share with us what their application is?


 > So they are asking for two of my GNSS frequency standards with 1 pps
 > outputs.
 >
 > The 1 pps outputs being derived from the rubidium oscillator (which
 > is aligned to GPS/GNSS)
 >
 > The best I think I can achieve is in the low ns range.

Right. It will be ns, not ps. Forget about using GNSS for ps level timing.


 > Does anyone know how this can be achieved?

Google for papers by high-end national timing laboratories. Words like: 
active temperature stabilized (phase stabilized) bidirectional optical 
fiber links.

Very possible, very expensive, quite common now. I'd guess most of the 
timing centers in Europe are linked this way.

/tvb




On 12/4/2019 1:40 AM, mar...@ptsyst.com wrote:
> Hello,
>
>  
>
> I'm always being asked to provide equipment that can produce two 1 pps
> outputs aligned to each other to within a few ps.
>
>  
>
> These two 1 pps pulses are not in the same location and could be 100 metres
> to a few km away.
>
>  
>
> So they are asking for two of my GNSS frequency standards with 1 pps
> outputs.
>
>  
>
> The 1 pps outputs being derived from the rubidium oscillator (which is
> aligned to GPS/GNSS)
>
>  
>
> The best I think I can achieve is in the low ns range.
>
>  
>
> Does anyone know how this can be achieved?
>
>  
>
> Regards
>
>  
>
> Martyn
>
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Re: [time-nuts] Difference in antennas

[Taka Kamiya via time-nuts]

So concensus is, 50dB gain antenna is too much gain, unless feed line is 
too long, reception is poor, or there are other circumstances extra gain is 
desired?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, November 21, 2019, 3:00:14 PM EST, Bob kb8tq  
wrote:  
 
 Hi

That is indeed the gotcha. Once you get past a certain amount of gain in the
preamp, the C/N levels don’t change enough to notice. Looking today vs looking
tomorrow is unlikely to be of any help if you are after a fraction of a db. 

About the only way to check would be to fast switch an attenuator in and out of
the signal path. Watch things for a minute at one setting and then do the same 
at
another setting. Run for a while and log all the deltas. If you see a 
degradation of
more than a few tenths of a db, you are getting towards the minimum gain point. 

Indeed there are some receivers that have an AGC built in. *IF* your receiver 
has one
and *IF* you can get at it, that would be a great way to work this out. Indeed 
anybody
who makes it past both of those constraints has a pretty unique device.



Simple answer for a 50 db antenna is to put an attenuator in after the DC has
been eliminated from the circuit. It’s not idea, but it’s the best you can do. 
Running
a great big splitter is one great way to come up with attenuation …..

Bob


> On Nov 21, 2019, at 10:29 AM, John Ackermann N8UR  wrote:
> 
> Bob, this is a great summary, thanks!
> 
> One related question, especially with mixed systems -- how do you tell
> if you have optimum signal level at the receiver?
> 
> Most show some sort of SNR or Cn value.  What should we look for?  What
> are the indication of *too much* signal?  One issue in particular is how
> to handle a modern GPS that expects modest antenna gain when it's
> plugged into a system with a 50dB gain antenna at the top.
> 
> Thanks!
> John
> 
> 
> On 11/21/19 8:00 AM, Bob kb8tq wrote:
>> Hi
>> 
>> Way back in time, the first gear out there to use what we now look at as 
>> “normal” antennas 
>> was survey gear. For various reasons they decided on a 12V power supply and 
>> 40 to 50 db
>> of gain in the preamp mounted in the antenna. They also got into L1 / L2 
>> pretty quickly. 
>> 
>> A bit later the cell phone (and later broadcast) guys got into this. In a 
>> location with a lot of 
>> RF (like a cell site) having a lot of gain at the antenna didn’t work all 
>> that well. IMD issues 
>> got into the act pretty quickly. In addition, front end filtering was 
>> required to reduce overload
>> issues. The focus was on L1 only so filtering was relatively easy.
>> 
>> There is a whole separate set of antennas that put a big chunk of the RF 
>> portion of the radio
>> in the antenna. Those still survive here and there. I have one of them and 
>> probably a couple
>> of dozen of the more “normal” antennas. 
>> 
>> As time marched on, supplying 12V to antennas became a bit less popular. 
>> Most of the cell 
>> guys went over to a 5V antenna supply. The net result was 12V 50 db survey 
>> antennas that did 
>> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas 
>> didn’t do L1/L2 so
>> not going to work for survey. The survey antennas had way to much gain and 
>> no filtering so 
>> not going to work for a cell site. 
>> 
>> Indeed things did and do get crossed up in various pro and basement systems. 
>> With care and
>> the right set of circumstances things may work. In other cases the result 
>> can be an ongoing set
>> of systems issues over an entire network of stations. 
>> 
>> Prices for a good new survey antenna are up in the many thousands of dollars 
>> range. They have
>> very stable phase centers and (usually) test results to allow correction of 
>> any residual phase 
>> issues. This is part of what lets you get into the “couple of mm” range on a 
>> survey. 
>> 
>> For timing, you have to dig a bit and answer a few questions. Is your 
>> concern how close you
>> are to BIH? If so you will need to know all the delays in your system. This 
>> includes the delays
>> in the antenna filters and the preamp. Is your concern (or measure) the ADEV 
>> at 1 second?
>> If so the delays are not a concern. Your antenna choice may be a bit 
>> different depending on
>> this focus.
>> 
>> Bob
>> 
>> 
>> 
>>> On Nov 21, 2019, at 1:25 AM, Taka Kamiya via time-nuts 
>>>  wrote:
>>> 
>>> I have been looking antennas.  Prices seem to range less than 30 dollars to 
>>> more than 500 dollars.  S

[time-nuts] Difference in antennas

[Taka Kamiya via time-nuts]

I have been looking antennas.  Prices seem to range less than 30 dollars to 
more than 500 dollars.  Some are 20db gain and some are 40 db gain.  Some are 
specified as marine use only.  Some are specified as timing use.  Some doesn't 
say anything at all.  Power supplies are different.
Other than obvious, antenna is an antenna, isn't it?  It captures L1 signal, 
amplify it and send it down the coax.  What makes one more costly than others?  
What makes one timing antenna and one navigation antenna?  It doesn't make 
sense to me.  

I did some simple experiment with 26db, 40db, and magnetic stick on type.  I 
didn't really see significant difference.  Signal level itself even wasn't all 
that different.  I have nearly a clear sky view 360 degrees above 30 degrees 
above horizon.  In some directions, clear view to horizon.  My feed is Timewave 
type.  So It may not be the best but nearly ideal.  

Can someone shed light on this topic?  (of course, I know some antenna has 
integrated receiver.  I am not talking about those)

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Confusion over Thunderbolt - noob is going crazy

[Taka Kamiya via time-nuts]

Thank you.
The BNC port one may be a custom job.  I know they OEM'd for few companies.  
Since I have so many GPSDOs, I want one "master" unit.  So I started looking 
what appear to be the most commonly used type.
By the way  did you ever get to tame the severe jitter of Symmetricon 
version of GPSTM?  I was so pleased with the Trimble version that I bought 6 of 
this Symmetricon version.  As it is, they are useless.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, November 15, 2019, 10:51:11 AM EST, Arthur Dent 
 wrote:  
 
 Basically there is only one Thunderbolt. There are 2 firmware versions (2.2
& 3.0) and some of the earlier firmware version had a Piezo branded
oscillator rather than the Trimble branded one and the Trimble one is
somewhat better. The thick Thunderbolt package has a switching power supply
mounted on top of the Thunderbolt that allows one voltage to supply the
unit rather than the +5/+12/-12 used by the Thunderbolt proper. The sellers
of the one with the power supply mounted on top seem to ask way more for
the package than the cost of the included power supply would warrant.

I have one of the 2.2 firmware version with a Trimble branded OCXO that I
have used for years and it works perfectly for my use. Of the over 200
units I have sold there were only a couple of the 2.2 firmware versions and
no Piezo OCXOs in all those.  I’ve never seen or heard of a BNC antenna
connector. Internal to the wireless locator where these Thunderbolt were
used there was a cable to go from the type F connector on the Thunderbolt
to the TNC connector on the rear panel of the locator.
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Re: [time-nuts] Confusion over Thunderbolt - noob is going crazy

[Taka Kamiya via time-nuts]

You mentioned "this particular model," referring to the RED version, is no 
longer manufactured or supported.  (no firmware support)  But does that mean 
ones OLDER than that is still supported for firmware upgrades?  Where do I go 
on Trimble's website?  There was nothing on firmware under "support". 

Thank you for helping out this noob!


--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, November 15, 2019, 2:48:00 PM EST, Gregory Beat via time-nuts 
 wrote:  
 
 Taka -

The majority of the surplus GPSDO units come from the mobile/cellular 
telecommunication companies since the late 1990s.  Surplus equipment occurs due 
to Service advances (2G—>3G—>4G/LTE—>5G), Technology upgrades/obsolescence, and 
 Consolidation/merger of telecom companies.
==
NO Distinct Advantage in owning the Trimble Thunderbolt models versus other 
options,
some would note a few disadvantages (now 10 years later, like 1024-week 
rollover).
==
A large number of Trimble Thunderbolt GPS Disciplined Oscillators (GPSDO) 
appeared on the surplus market in 2007 and 2008.  Majority of these were the 
“THIN Model” (no internal DC-DC converter).

At that time (2008) TAPR Time-Nuts had a Group Buy, and offered a KIT (~ $225).
Tom Van Baak (tvb) and other members of Time-Nuts tested units and packaged 
these with a tri-voltage (+5, +12, -12) power supply for Group Buy participants.
http://www.leapsecond.com/pages/tapr-tbolt/

W6AER built (DIY) this Rack Case for his surplus Thunderbolt & power supply.
https://w6aer.com/10mhz-gps-disciplined-oscillator-gpsdo-trimble-thunderbolt/
= 
The RED Thunderbolt model has a Larger case because it contains the SMPS (24V 
to Tri-Voltage) as well as the GPSDO (THICK model). 
http://trl.trimble.com/docushare/dsweb/Get/Document-10015/
This specific model is no longer mfg. or supported by Trimble (no firmware 
updates provided).  Surplus “Red” units have appeared from 911 telephone 
centers (past 5 years), since the RED model does not handle the 1024-week 
rollover.  The “cheapest” has been ~$250 (2018 price, I paid) for a surplus 
unit from a Pennsylvania 911 center.
https://en.wikipedia.org/wiki/GPS_Week_Number_Rollover
The Lady Heather software (Mark Sims) “notes & corrects” the 1024-week rollover 
occurrence with these Trimble units, on its computer display.
ANY OTHER Solution would also have to “Correct” for the 1024-week rollover.
—
The BLUE Thunderbolt E model is Current Trimble Production ($$), hence RARELY 
seen as Surplus.  Trimble refreshed their hardware, simplifying design (newer 
components).
http://trl.trimble.com/docushare/dsweb/Get/Document-383329/
Trimble Thunderbolt-E Product Page
https://www.trimble.com/Timing/thunderbolt-e.aspx
=
THUNDERBOLT Frequently Asked Questions (from Group Buy, a decade ago).
http://www.ko4bb.com/getsimple/index.php?id=time-nuts-thunderbolt-gpsdo-group-buy

g. beat, w9gb
chicago
==
Date: Fri, 15 Nov 2019 04:02:56 + (UTC)
From: Taka Kamiya 
To: Time Nuts Group 
Subject: [time-nuts] Confusion over Thunderbolt - noob is going crazy

I have several GPSDO, BUT I don't have a TRUE Trimble Thunderbolt.  I want one.
There seem to be infinite variations of them.  So far (I have been looking for 
a week), there are no good summary (or even a summary) of various types and how 
they are different.
I know there is a thin type that looks to be 1" or so thick, and thick type 
that is about double that.  I know one model has a Blue label (Thunderbolt E) 
and an earlier model had a Red Label (Thunderbolt).
I know there are differences in the Internal Crystal Oscillator/Oven.

Spending $1500 for new one is out of question, but price seems to vary from 
$150 to $500 for used ones.  Since most of these surplus units now come from 
China, I'd think they are reclaimed equipment.  Is this assumption right?
Any reliable source?? 
I am a bit skeptical with the surplus market the way it is.  Are they all 
telecom quality??
Thank you very much.
--
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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[time-nuts] Confusion over Thunderbolt - noob is going crazy

[Taka Kamiya via time-nuts]

I hope I don't get yelled at for asking this question.  I honestly looked 
everywhere and still can't get this.
I have several GPSDO but I don't have a TRUE Thunderbolt.  I want one.  So I 
started looking.  There seem to be infinite variations of them.  So far (I have 
been looking for a week), there are no good summary (or even a summary) of 
various types and how they are different.
I know there is a thin type that looks to be 1" or so thick, and thick type 
that is about double that.I know thick type can have blue label with current 
Tbolt E, or red label (read somewhere this is an earlier one?)
I know there is a type that contains inferior oven and better one.  (Marked 
Trimble)I know there is a type with F connector for antenna, and there is one 
with BNC.I know there is an early type and late type.  (I don't know how to 
tell)I know the latest one is T-boltE, which is not necessary similar to 
earlier ones.I know there is a type that requires single voltage and 3 sources.
What I don't know is:
How many different types are there.Any particular one to avoid?  I know there 
were some experiment done with replacing OCXO of earliest type.Why form factor 
change?  OCXO does not seem to be any tallerSpending $1500 for new one is 
out of question, but price seems to vary from $150 to $500 for used ones.  
Since most of them come from China, I'd think they are reclaimed equipment.  Is 
this assumption right?
Any reliable source?  I am a bit skeptical with the market the way it is.Are 
they all telecom quality?  

Thank you very much.


--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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[time-nuts] Nortel GPSTM Trimble version firmware file request

[Taka Kamiya via time-nuts]

I have two Nortel GPSTM NTBW500AA-11 and -07.  GPS Firmware are 10.4 and 10.5 
respectably. (as reported by Lady Heather)  They behave quite differently, so 
I'd like to either make them both 10.5 or upgrade to later versions.  According 
to Nortel, ROM files were available at some point but I can no longer find them 
on Internet.  If anyone know where one can be found, I'd be grateful for this 
information.  I do have a software to upload the same to the flash roms.

Please note, this is a Trimble version, not Symmetricom version.  They are 
completely different internally.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] HP5071A with bad tube.... can I get one used?

[Taka Kamiya via time-nuts]

I bought this HP5071A knowing it didn't lock and paid very little for it.  I 
think I'll keep it for a while hoping another one shows up.  I know there is a 
ROM in the tube with serial number and a poem.  Do you know if the unit starts 
its life as high performance unit, does it have to stay that way?  If 
non-high-performance unit shows up, can they be mixed and matched somehow?

I do have a "limping along" FTS4040A that still locks.  But its an old unit.  
I'm still trying to verify its performance, but even in best of case scenario, 
it's an order or two behind standard version of HP5071A.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, October 24, 2019, 2:23:39 PM EDT, Bob kb8tq  
wrote:  
 
 Hi

Based on running a high performance tube version of the 5071A for a number of 
years, the
tubes last about 5 to 7 years when run 24/7/365. Once they die, the practical 
($$$)
alternative is to send the beast back to the factory for a new tube. Indeed 
given the price
and the complexity of shipping (it’s a hazmat item), this is only practical if 
you are a company
that needs to use the device. 

At least on the high performance 5071, the “end of life” process is not an 
immediate death sort of
thing. The stability (ADEV) of the device degrades as the tube wears out. If 
you have a stability 
requirement (not just function) the wear out point will be a bit earlier than 
the numbers above.
Just how much earlier depends a bit on how picky you are. ( = if you high 
performance tube is 
worse than a standard tube, how happy are you?) You also would need the gear to 
test the ADEV. 

Some of what’s in the 5071A is running based on firmware and settings shot in 
here and there
on the device. Updating / adjusting / tweaking those settings has not been 
documented out
here “in the wild” AFIK. The factory (obviously) does understand how to tweak 
this or that. 
The degree to which tweaks might be needed with this or that unusual tube is 
very much 
open to debate.

The whole “can’t get a tube” issue is hardly unique to the 5071A. I have a pair 
of Cs standards
in the basement. Both have tube issues. One may be repairable if I ever get 
around to playing
with the fix. Once “fixed” will it run for another few months or a few more 
years? There is no way
to know without trying it. 

Will this or that tube last a month, a year or two or a decade or thee? I know 
of no external test that will
guarantee a decade of capacity. There are indeed tests that will suggest that 
you are limping along. 
Most (but not all) basement Cs standards are in the “limping along” category. 
As with the 5071, 
just what constitutes limping along, depends a bit on how close to (or how much 
better than) the 
factory spec you need to be.

Bob

> On Oct 23, 2019, at 11:42 PM, Taka Kamiya via time-nuts 
>  wrote:
> 
> I have an HP5071A with a high performance option that does not work.  All of 
> my tests indicate the faulty component is a tube itself.  Buying a new tube 
> is way out of my budget.  I am now torn between parting it out and see what I 
> can use and keeping it intact with hope something might pop up.  
> 
> Question for the group  Obtaining a used tube for this, I don't care if 
> its high performance or not, as long as it works with the chassis, is really 
> not a possibility, correct?  I have never seen one on eBay.
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
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[time-nuts] HP5071A with bad tube.... can I get one used?

[Taka Kamiya via time-nuts]

I have an HP5071A with a high performance option that does not work.  All of my 
tests indicate the faulty component is a tube itself.  Buying a new tube is way 
out of my budget.  I am now torn between parting it out and see what I can use 
and keeping it intact with hope something might pop up.  

Question for the group  Obtaining a used tube for this, I don't care if its 
high performance or not, as long as it works with the chassis, is really not a 
possibility, correct?  I have never seen one on eBay.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Using commercial video amplifier for 10MHz clock distribution.

[Taka Kamiya via time-nuts]

I've done some quick test.
Specimen is one of my Extron MDV3.Instruments used were 

TruePosition based GPSDO producing 10MHz at 11.9dBmHP8644A producing 15MHz at 
10dBmHP8591EM spectrum analyzer
HP437B power meter + 482A sensor

I connected 10MHz to OUTPUT port of Extron MDV3.  Nothing was detected on input 
or other output ports.  Non detectable either by power meter or SpecAn.I 
connected 10MHz to OUTPUT port and looked at other OUTPUT port.  Nothing 
detected as well.
I connected 10MHz to INPUT port and took a power measurement at output port of 
Extron.  11.2dBmI connected 10MHz to INPUT port and looked at output port by 
SpecAn.  Keeping eyes on CRT
Then I connected 15MHz to OUTPUT port, zero change on CRT
As far as Saturation, up to 12.3dBm input, it was clean.  Above this, 2nd 
harmonic started to show up.  At 14dBm, all harmonics were -40dB below the 
primary signal.  This is probably the limit I'd go.
With this, I can conclude this particular device has a "pretty good" isolation 
between output port and output to input port, as well as sufficient protection 
for reverse leakage.  Obviously, my result is specific to my device.  Some 
future/past design revision, other models, other makes, etc has to be 
re-measured.  

I left test setup as-is.  If anyone want me to test something else, I'd be 
happy to.
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Saturday, October 19, 2019, 2:02:32 PM EDT, tim...@timeok.it 
 wrote:  
 
 
  Hi,

  A premise must be made to define the performance of these DAs as EXTRON can 
be compared to those built for the distribution of reference frequencies.
  The Extron is a very nice solution, certainly of modest price, but we must 
consider that its performances are limited. This especially if we talk about 
saturation levels but much more important is the low separation between the 
output channels. These two factors can be negligible if the required 
level/stability is good but not excellent, in fact by disconnecting a load or 
simply changing the length of a coax connection on a channel almost certainly a 
change in level / phase will occur in the adjacent output.

  If anyone is interested, you will find my solution here:

  
http://www.timeok.it/wp-content/uploads/2015/08/Frequency-Distribution-Design-Basic-Module-v-4.1.pdf

  Using it as a buffer for the low phase noise HP 10811-60109 and BVA 8600 
there is no deterioration of the phase / noise floor.

  I ordered some new PCBs related to the buffer only. If anyone is interested 
let me know off list.

  Luciano

  tim...@timeok.it


  Da "time-nuts" time-nuts-boun...@lists.febo.com
  A "Discussion of precise time and frequency measurement" 
time-nuts@lists.febo.com
  Cc
  Data Sat, 19 Oct 2019 08:30:02 +
  Oggetto Re: [time-nuts] Using commercial video amplifier for 10MHz clock 
distribution.
  There is a schematic here on the Extron uploaded by a TN member. The 
schematic for the Extron looks looks dead simple that one could really just 
make a simple 3 channel with the included mods in the writeup, only problem is 
I don't see a source for a CLC409 any longer, and I don't have the experience 
or knowledge to use a substitute ADA800x ??

  


  -=Bryan=-

  
  From: time-nuts  on behalf of ed breya 

  Sent: October 18, 2019 1:39 PM
  To: time-nuts@lists.febo.com 
  Subject: Re: [time-nuts] Using commercial video amplifier for 10MHz clock 
distribution.

  I have a Hitachi VD-1000 video distribution unit that's been sitting
  unused for years, waiting until I finally get around to making it into a
  reference unit. I just dug it out and looked inside. It is full of RCA
  jack cables for jumping the signals around in different ways. I
  apparently had changed things around already, to make one section into a
  15-output distributor. I have forgotten all about it long ago, so now
  it's just a dizzying array of cabling. I must have made notes somewhere,
  that I'll have to find for when I eventually (probably fairly soon) do
  the proper conversion.

  It uses CLC404 amplifiers, which appear to be older and a little noisier
  than the CLC409, but should be OK for this. Unfortunately, it uses a
  small switching supply, which I dislike for things like this, so
  ultimately will make a linear one for it.

  This thing has 40 BNC connectors on the back, which would allow for lots
  of I/O and branching combinations. This is likely way more than I'll
  ever need, so the "new" plan is to incorporate some improvements,
  considering what I recently learned during my work on the frequency
  multiplier project. I'll be reducing the total fanout, and changing some
  of the outputs to have fully-floating transformer coupling, to reduce
  ground loop effects in high sensitivity applications, and also
  

Re: [time-nuts] can of worms: time-of-day in a community radio station

[Taka Kamiya via time-nuts]

I only have one idea.  Something I thought of doing it myself but have not done 
so, yet.
I think syncing locations with GPS or ntp is good enough for time 
synchronization.  But display could be problematic.  As they make transition 
from one program to another, 1 second overlap or 1 second of blank is quite 
long.  Listeners will certainly catch on to that.
I wanted a digital clock that has HH:MM:SS but below that are bar graph for 
sub-second.  Say 10th of a second, one LED representing 1/10th.  That way, they 
can count down and meet at 00 exactly enough for human perception.  For this 
kind of thing, fast flying 10th digit isn't really useful as it's awfully hard 
to read, let alone read and do something else, like think of a word to fill 
that last 1/2 second.
I would think this kind of thing is easy enough to implement either as a 
hardware or an application on Windows/Linux workstation.  Whatever the device 
to use, it must be synced with the master source.  PC's clock can go off by 20 
seconds per day quite easily.  Even server class machines close to million 
dollars use cheap 32KHz fork crystal.



--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, October 18, 2019, 4:00:41 PM EDT, Eric Scace  
wrote:  
 
   I fear that I am developing a reputation for bringing to the list rather 
oddball questions. In my rôle as agent provocateur, therefore, here is another 
such problem.

  Questions for you are at the end. Thanks for your thoughts,.

— Eric

Issue:
  A community broadcast radio station with multiple studio locations wishes to 
improve the display of time-of-day throughout the station’s operating 
environments. Its current legacy approaches (described below) cause problems 
such as:
on-air presenters fail to smoothly segue into scheduled program feeds (e.g., 
BBC news) because the studio clock is “a little off”… and because the studio 
clock is digital. [Quick: how many more seconds can you speak before the top of 
the hour when a digital clock shows 4:59:42? Watching an analog stepping second 
hand is much easier in this situation.]
computers that automatically capture audio programs to files in storage 
sometimes truncate the start or end of the program because the computer’s idea 
of time-of-day disagrees with that of the program source.
desktop computers throughout the station, including in production studios, all 
render slightly different versions of time-of-day to their users.
servers (e.g, for streaming, for archiving shows) are similarly in cheerful 
disagreement as to time of day.
wall clocks studios in one city show a different time to their engineers than 
the studios in another city, rendering handoffs more complicated. Ditto for 
remote broadcast sites, and even between studios in the same site.
requires manual intervention to bring the most egregious systems back to some 
semblance of reality

Background & existing situation:
  Commercial broadcast stations have more money and technology to solve these 
problems. In contrast, “community radio” stations have limited funds and are 
largely staffed by volunteers (like me!).

  In this case, the existing systems are a hodgepodge:
mostly Windows OS PCs, with a couple of Macs
Linux servers
mash-mash of wall clocks, the best of which is a LaCrosse WWVB digital in the 
primary on-air studio. The WWVB signal is more than adequate but the LaCross 
display format is sub-optimal for studio use.

Goals: (first pass)
minimum accuracy requirement: time-of-day displayed within ±0.1 second of UTC 
timescale. (Two clocks both falling outside this range will cause program 
handoffs to be uncomfortably tight or loose.)
no manual intervention required for summer/winter time transitions
no manual intervention required for leap seconds
leap second:
no smearing (minimum requirement)
accurate leap second display (desirable but unlikely to be achievable)
desirable consistency goal: time-of-day displayed within ±0.025 second 
throughout each site. At this level, two adjacent clock displays will not be 
perceived as out of step by a person.
presentation goals: studio/remote broadcast control point time-of-day displayed 
in both analog (with stepped seconds hands) and digital form (preferred H:MM).
If digital form includes seconds, the seconds digits should be visually 
separated; e.g..smaller. A presenter can then, at a glance and without 
confusion, announce the time (“four twenty-three”) from the digital display.
Date in form “Oct 17 Thu” available.
medium-term desirable: displays continue within specs for accuracy/consistency 
across power cutovers (to/from generator) and public Internet outages.
maintenance goals:
"eschew emergencies”: no one should have to rush to the station in the middle 
of the night, nor drop what their doing during the day, because time-of-day 
display has failed or gone out-of-spec.
standardize on the same hardware/software everywhere
identical hardware allows more cost-effective 1:N 

[time-nuts] Using commercial video amplifier for 10MHz clock distribution.

[Taka Kamiya via time-nuts]

I am using Extron MDA 3V for distributing 10MHz at several places in my lab.  
MDA3V is a one port in - 3 port out device made for VIDEO market and rather low 
end at that.  Input and output is 75 ohm and bandwidth extend to 150MHz or so.  
Looking at 10MHz sine wave through it, it looks good.  No visible distortions.  
Gain is unity between input and one of the ports.

I also have distribution Amps from Spectracom.  These, of course, are made for 
clock distribution purpose and I don't question usage for the purpose.  The 
level of "accuracy" of distribution is that I need frequency stability, but 
time delay in coax, slight phase shift in coax, and other small nuances are not 
my concern.  (should they be?)  I'm not running a competitive service to NIST 
and this is not for commercial purpose.  I'm just a junior time nuts.
Couple of questions though.  This device is 75ohm.  It's easy to add 150ohm in 
parallel to a matching resister and make it 50ohm.  However, I'm guessing 50 
ohm / 75 ohm mismatch is not really a big deal that I'm not doing anything 
about it.  Input and output cables are RG58 (50 ohm)  VSWR is 1.5, For external 
sync port, many equipment is not exactly spec'd for 50 ohm, but often only 
spec'd for voltage or at db level without any specific impedance mentioned.  
Recommended cable is 50 ohm though.  I typically shy away from consumer grade 
gear but looking inside, it's just an op-amp and registers.  If I use square 
wave which contains higher frequency components, would this be inadequate?
There are many web pages by people doing exactly what I'm doing with usually 
bigger Extron devices.  I'd like to consult the Time-Nut community of sanity in 
what I am doing.  Is this really not an issue, or "it's not simple as THAT" 
type situation?
Thank you very much
--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] GPS Antennas

[Taka Kamiya via time-nuts]

If your other gear survived, likely, the lightening hit was an indirect one.  
If you do install more rods near antennas, it is extremely important that those 
rods are connected/bonded to the house main feed grounds at service entrance 
via low impedance/resistance connection.  How exactly this needs to be done is 
a very deep science people make living out of.  Without this 
antenna-ground-to-main-ground-connection, there will be enough potential 
difference that your stuff will blow again.
In State of Florida where I live, and the lightening capital of the United 
States, the code says, stick two rods in the ground and call it done.  This is 
not even close to enough for lightening protection.  It's barely enough for 
personal protection.  I have five rods at the moment.  I plan to add many more 
as time and resource permits.  I'd like to have ten rods at least.
Good luck and let's all be safe!

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Tuesday, October 15, 2019, 9:20:15 PM EDT, Joseph Gwinn 
 wrote:  
 
 On Tue, 15 Oct 2019 19:01:37 -0400, time-nuts-requ...@lists.febo.com 
wrote:
> --
> 
> Message: 2
> Date: Tue, 15 Oct 2019 16:58:42 +0200
> From: Attila Kinali 
> To: Discussion of precise time and frequency measurement
>     
> Subject: Re: [time-nuts] GPS Antennas
> Message-ID: <20191015165842.841855f9d85e4fbdbe633...@kinali.ch>
> Content-Type: text/plain; charset=US-ASCII
> 
> On Thu, 29 Aug 2019 12:59:06 -0400
> Dan Kemppainen  wrote:
> 
>> For the second summer in a row we were smacked with lightning. So I'm in 
>> need of a new GPS antenna. Might as well look for one with multi band 
>> units. I recall some talk about the cheap multi-band units on ebay that 
>> that are compatible with the f9P modules. Can anyone report back how 
>> they worked out?

After two hits, I'd consider a lightning rod or two near the antenna, 
with the air terminal well above the antenna, but not connected to that 
antenna.

Joe Gwinn

> 
> End of time-nuts Digest, Vol 183, Issue 28
> **

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Re: [time-nuts] HP105B HP 105B 1 amp fuse blowing

[Taka Kamiya via time-nuts]

The fact that 25V supply is dropping to 23.4V shows it is drawing far more 
current than it is rated.  I am assuming this is a regulated power supply.  
Does the power brick actually shuts down at 500mA or does it let the the 
voltage drop and try to supply what it can?  Maybe one or more Nicad has an 
internal short?  That will cause and over-voltage situation per battery and 
thus over-current.  I've recently seen a brick power supply go into oscillation 
and produce 3x rated voltage when too much current was drawn.  (and blew the 
circuit)

Also, different batteries has different charging rates.  As far as 105B 
document goes, it says 24V 0.5Amp supply but that is for default configuration. 
Designed charge rate is 390mA (page 3-4) and is current controlled by A5Q3.

I would actually measure how much current is drawn there.  Since the fuse is 
already blown, just put an am-meter across the fuse and see  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, October 10, 2019, 4:00:41 PM EDT, Roy Thistle 
 wrote:  
 
 Hi All:
A 105B (quartz oscillator) is blowing the 1A fuse, after it is on about 1 hour.
The fuse appears to have just melted (not a black mark as the result of a 
flash, in the case of a high current short.)… just looks like the fuse wire 
(inside the glass capsule) melted into some little blobs, for about 1/4  the 
fuse length, near the middle. It wasn't a fast-blo or slow-blo fuse... just the 
normal kind.
I think the unit is drawing just a little too much current, as the result of 
the batteries needing charging (I had the fast charge option on when the fuse 
blew.) And so, the fuse heated up, and finally melted. Not sure why the 
batteries were not charging normally... but 20.1 volts is what I measured 
across the pack, initially, and 23.4 V after about 45 min of charging.
I am charging the batters, from a power cube, at 510 ma, and dropping (cube 
gives 25V, 500mA max)… the batteries are 20 C size NiCads, wired in series... 
that of course is a retrofit.
I don't want to put another fuse in, and blow that too, without some reasonable 
explanation of why the first one failed!
Please, any comments, or hints/suggestions... much appreciated.
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Re: [time-nuts] DC distribution

[Taka Kamiya via time-nuts]

I used to use power pole, too but they don't lock firmly enough for my liking.  
So I don't use them anymore.  It would be perfect if there is an option to add 
positive locking mechanism of some kind.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, October 4, 2019, 4:06:50 PM EDT, Didier Juges 
 wrote:  
 
 That's what I do too. I do use Power Pole for my ham stuff that draws high
current but for all the <2A 12V stuff the 5.1mm barrel connector with
positive center is hard to beat because I have so many power sources and
equipment already wired for it. I am not ready to rewire all the off the
shelf equipment that came with one of those.

Power Pole are convenient for batteries though because you can use the
connector to charge the battery or use it as a source.

Didier KO4BB

On Fri, Oct 4, 2019, 2:01 PM Taka Kamiya via time-nuts <
time-nuts@lists.febo.com> wrote:

> Mine is very simple
> USB connector for 5VBarrel connector 5.5/2.1mm for 12VTerminal strip for
> 24V
> None of them are high power devices.
>
> ---
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
>
>
>    On Friday, October 4, 2019, 2:03:55 AM EDT, Bill Dailey <
> docdai...@gmail.com> wrote:
>
>  Setting up a new workbench and am wondering what wisdom people can
> offer.  I am powering numerous synthesizers (5v), small receivers (5v),
> Upconverters (5v), larger receivers (12v), fury Gpsdo’s.. etc.  anyone use
> something neat and not real expensive for distributing 5v and 12v.  I am
> hoping for a long COTS pcb with fusing and maybe holes for plugs.
>
> Any insights?
>
> Bill
>
> Bill Dailey
>
> Negativity always wins the short game. But positivity wins the long game.
> - Gary Vaynerchuk
>
> Don’t be easy to understand,
> Be impossible to misunderstand
> - Steve Sims
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Re: [time-nuts] DC distribution

[Taka Kamiya via time-nuts]

Mine is very simple
USB connector for 5VBarrel connector 5.5/2.1mm for 12VTerminal strip for 24V
None of them are high power devices.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Friday, October 4, 2019, 2:03:55 AM EDT, Bill Dailey 
 wrote:  
 
 Setting up a new workbench and am wondering what wisdom people can offer.  I 
am powering numerous synthesizers (5v), small receivers (5v), Upconverters 
(5v), larger receivers (12v), fury Gpsdo’s.. etc.  anyone use something neat 
and not real expensive for distributing 5v and 12v.  I am hoping for a long 
COTS pcb with fusing and maybe holes for plugs.  

Any insights?

Bill

Bill Dailey

Negativity always wins the short game. But positivity wins the long game. - 
Gary Vaynerchuk

Don’t be easy to understand, 
Be impossible to misunderstand 
- Steve Sims
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Re: [time-nuts] Looking for documentation for GPSTM BY SYMMETRICOM (not Trimble)

[Taka Kamiya via time-nuts]

Bob,
Yes, I am aware of all that. I got what I needed, thanks to a kind gentleman.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Monday, September 30, 2019, 12:36:01 PM EDT, Bob kb8tq  
wrote:  
 
 Hi

Both GPSDO’s were *sold* to Nortel. Neither one was made by them. The two 
vendors that you 
most commonly see popping up on eBay are Symmetricom ( now Microchip) and 
Trimble. There
may have been other vendors as well. 

If you are looking for schematics and block diagrams on any surplus GPSDO or 
OCXO or Telecom
Rb, good luck. Unless a Time Nut has traced out the internals it is very 
unlikely they exist. Manufacturers
stopped putting that sort of stuff out decades ago for a variety of reasons.

Bob

> On Sep 29, 2019, at 6:54 PM, Taka Kamiya via time-nuts 
>  wrote:
> 
> I am looking for any documentation for Nortel branded GPSDO called GPSTM.  
> What's confusing is there are at least 2 kind with exactly the same name!  I 
> need one made by Symmetricom.  Model number is NTBW50AA-22.  
> 
> Ones made by Trimble are all over the Internet, alone with documentation.  
> That is NOT what I am looking for.  It has to be Symmetricom.
> If anyone can help me out, I'd be very grateful.
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
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Re: [time-nuts] Even Seconds Pulse option (1PP2S), HP 58503B

[Taka Kamiya via time-nuts]

I believe it's a CDMA thing.  I have a Nortel GPSTM that came out of CDMA site. 
 It has the same thing.

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Sunday, September 29, 2019, 9:36:55 AM EDT, Gregory Beat via time-nuts 
 wrote:  
 
 A new resident arrived at the “Time Cave” this weekend, the HP/Symmetricom 
58503B.  Just the plain front panel (4 LEDs) model, without Option 1 (VFD clock 
display).
Acquired in USA, cheaper than current Asian exporter.
https://accusrc.com/uploads/datasheets/4975_58503b.pdf

Supposedly stored in a closet since 2010 (verified by its diagnostic logs), the 
unit only had 2,000 hours of operation.
Today, it happily has a GPS Lock and is currently “re-learning” where the 1 PPS 
and 10 MHz outputs wandered (taming Lazarus).
—
One surprise, it has Option 2 (1PP2S) installed on its Rear Panel.

Option 002 : 1 PP2S (One-Pulse-Per-Two-Seconds) connector for outputting a 
pulse every other second, synchronized to the even seconds in GPS time. 
Pulses occur on even-numbered seconds (i.e., 2 seconds, 4 seconds, etc.).
===
QUESTION: 
What Specific Applications would use this 1PP2S output regularly??

greg

Sent from iPhone 6s
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