[time-nuts] Re: Need help to DATUM Power Supply MPS (Type MFS Modular Frequency Systems)

[Wilko Bulte via time-nuts]

Quoting jung.schorndorf--- via time-nuts, who wrote on Thu, Jun 09, 2022 at 
04:26:08PM +0200 ..

hello Helmut,

> power supply unit for the GPS frequency standard
> from DATUM (Type MFS Modular Frequency Systems), I visited your homepage and
> registered on "time-nuts" mailing list.
> .
> May I ask if you have a frequency system like this with better documents
> than I do?
> The problem is the defective mains transformer in the Power Supply MPS
> module. I'm looking for the data (voltage & current)
> to find the right one from my transformer collection.
> I can only measure a few coil resistances on the transformer, the primary
> coil doesn't work at all.

> Also, maybe someone has the circuit of the electronics board.
> Our German subsidiary DATUM-Symmetricom-Microchip no longer since 20 years
> has any documents.

I have been looking for the same information in every corner of the Internet
but never found any schematics unfortunately..

But I happen to have the same PSU, a bit older even, as it is labeled
Efratom. A working one fortunately!

So, worst case I can open it and measure the voltages that the transformer
produces. It is not a lot of fun to open it (I had to, it had a loose screw
rattling inside or something like that) but it is doable.

If I remember correctly it produces 18V (AC? not sure) for the oven heater, 
the rest of the MFS runs on 22.5V DC. There might also be 5V DC involved for
the MGPS (GPSDO module).

MfG,

Wilko
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[time-nuts] Re: GPSDO - GPS1300-10-1000 by RFX Ltd. UK

[Wilko Bulte]

hello Bryan,

Runnimg LH on a *Pi is feasible without any problems. I have built such a setup 
myself, it lives in my shack and is based on a Samsung UCCM GPSDO (telco 
surplus obtained in China). The Pi in question is an OrangePi Zero running 
Armbian Linux. It runs an Xdesktop on top of a VNCserver.  Obviously LH shows 
herself on that desktop ;-) This whole shebang allows running the 
GPSDO/OrangePi combo to run headless (i.e. without a display), one can use any 
VNCclient to check on LH via the network. Laptop, tablet, even a smartphone can 
be used to monitor the GPSDO. The OrangePi has both Wlan as well as wired 
Ethernet options.

Hope this makes sense, I did an article for Electron, the monthly of the Dutch 
VERON ham organisation. In Dutch, for obvious reasons. But can make it 
available if there is interest.

Wilko
PA1WBU

> On 2 Mar 2022, at 19:21, Bryan _  wrote:
> 
> I have seen a project where ladyheather is run off a PI, suppose you could 
> just configure LH to display what you need.
> 
> -=Bryan=-
> 
> 
> From: va2...@ebox.net 
> Sent: March 2, 2022 9:34 AM
> To: Discussion of precise time and frequency measurement 
> 
> Subject: [time-nuts] Re: GPSDO - GPS1300-10-1000 by RFX Ltd. UK
> 
> Hello to all members.
> 
> I want to add to my lab a Pi based display that would show a GNSS SV map
> like the one attached to this message.
> 
> Any suggestions ?
> 
> Thank you !
> 
> Claude VA2 HDD
> 
> 
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[time-nuts] Re: How I spent my 2021

[Wilko Bulte]

hi Skip,

Now, that was a very interesting read! The tenacity with debugging such a 
variety of issues has to be admired!

At the same time I am quite surprised to see the messy (sorry, no insult 
intended, but the original dead bug proto style can and is done a lot cleaner 
than this) build result in such a high quality instrument. All is not what it 
seems is clearly applicable.

Congratulations with the succes sofar!

Wilko

NB: as for your wife's comment: I showed your writeup to my wife and she had an 
OMG too. And, to add to that, she has graduated as an EE ;-)

> On 4 Feb 2022, at 01:03, Skip Withrow  wrote:
> 
> Hello Time-Nuts,
> 
> I wanted to share what I have been working on for the last year, but
> the story is way too long for a single time-nut post.
> 
> Tom Van Baak has graciously agreed to host the saga.  You can read all
> about it at -
> http://leapsecond.com/u/skip/Sigma-Tau-MHM-pics.pdf
> 
> Enjoy!
> Skip Withrow
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[time-nuts] Re: Another reason to monitor line frequency :) - My AC measurement project & question

[Wilko Bulte]

A thought has just crossed my mind, not sure if the idea is valid or not. The 
idea is to re-purpose (parts of a) PLC network adapter. At the very least they 
can be a source of line voltage rated parts I'd think.

But the low frequency characteristics make me wonder in this context, as PLC is 
in the HF range?

Wilko

> On 23 Jan 2022, at 03:33, glen english LIST  wrote:
> 
> hear hear.stick to galvanic isolation or better  -
> 
> On MF/SW broadcast sites for this we used optically coupled sensors.
> 
> The mains supply is simply intensity modulating an opto isolator ( a pair 
> actually for both sides of the waveform) .. They can with stand a fair degree 
> of overload and its likely something else will flashover first with slots in 
> the PCB. The opto was used in a linear mode.  lots of effective R in the 
> emitter . didnt bother with saturation prevention diode B-C because the 
> recovery was (still) fast compared to the 50/60Hz.
> 
> -glen.
> 
>> On 23/01/2022 6:15 am, willl will wrote:
>>> On 1/21/22 7:00 PM, Robert LaJeunesse wrote:
>>> Stick with the transformer. The use of a capacitive divider is predicated
>> on the line waveform always being a sine wave. Dream on! All it takes is
>> one good spike down the line, maybe only 20-30V amplitude, and your
>> capacitive divider passes it right on to that ADC that has a much lower
>> (3.3V?) limit. Guess what goes poof?
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[time-nuts] Re: Another reason to monitor line frequency :) - My AC measurement project & question

[Wilko Bulte]

Given that it sounds that these capacitors  are mains connected I would 
recommend using Y rated capacitors for safety reasons. That should prevent them 
from going short circuit, Y caps being designed to "fail open".

Or did I misunderstand the proposed circuit?

Wilko

> On 22 Jan 2022, at 03:06, Lux, Jim  wrote:
> 
> On 1/21/22 4:43 PM, willl will wrote:
>> Hi everyone,
>> 
>> I have an recently finished project that also measuring AC waveform, full
>> description here:
>> https://github.com/will127534/RaspberryPiAtomicNixieClock/wiki
>> 
>> Basically using an AC transformer and Ti's ADC8681 @ 50Khz sampling rate.
>> 
>> This year I'm working on a earthquake sensor + AC mains monitor system (In
>> an earthquake prone area, AC mains frequency will fluctuate by power
>> generator and machine emergency stop like this one:
>> https://twitter.com/kuriuzu/status/1360602496821911553).
>> 
>> I want to improve AC measurement. Apart from the ADC sampling speed upgrade
>> (previously bottlenecked by the SPI connection to FPGA). I'm currently
>> debating about whether or not to bypass the transformer. How does the
>> distortion of an AC transformer impact the accuracy of mains waveform and
>> frequency? I'm not sure if it is worth it to go through the mains voltage
>> safety requirements.
> 
> You can use a capacitorsget your galvanic isolation, and a CR voltage divider 
> with minimal waveform distortion. Pick a burden current (say, 1 mA) and for 
> 120V line, you need 120k impedance at line frequency 60Hz
> 
> X = 1/(377*C) --> C = 1/(377 * 120E3)  = 22 nF
> 
> Say you want ~100:1 ratio? so 22 nF in series with 1.2k  (or 2.2uF) would do 
> nicely. Then feed your high Z ADC with a couple 0.1 uF capacitors from the 
> ends of the 1.2k.
> 
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[time-nuts] Re: help reviving Trimble UCCM-LPS GPSDO

[Wilko Bulte]

The OCXO is powered from the 5V rail of the UCCM, so I wonder how a Vref=5V 
would work? A bit of headroom wouod be required to make a reference circuit 
work.?

Wilko

> On 23 Dec 2021, at 18:15, Bob kb8tq  wrote:
> 
> Hi
> 
> It’s a pretty good bet that the Vref is 5V
> 
> Bob
> 
>> On Dec 23, 2021, at 8:42 AM, Wilko Bulte  wrote:
>> 
>> hi,
>> 
>> I am currently trying to revive a Trimble UCCM-LPS ex-telco GPSDO.
>> The model is a 57963-D according to the PCB silkscreen.
>> 
>> Got the board without its OCXO but luckily my stash of surplus I have
>> discovered a Trimble OCXO labeled 72345-86. Given that that OCXO also has a
>> label UCCM-LPS it "should work".
>> 
>> Joining the two resulted in:
>> 
>> UCCM >syst:status?
>> 
>> ---
>> 57964-86 serial number  S35DB68332   firmware ver  1.0.0.1-01 Ext
>> mode
>> ---
>> Reference Status __   Reference Outputs
>> ___
>> XX Ext Ref   : [LOS]
>> TFOM 2FFOM
>> 3
>> UCCM A Status[OCXO WARMUP]
>> 
>>>> GPS: [phase:-2.8E-09, settling]
>> ACQUISITION ...[GPS 1PPS
>> Valid]
>> Tracking: 8    Not Tracking: 3    Time
>> 
>> PRN  El  Az  C/N   PRN  El  AzGPS  13:28:51 23 Dec
>> 2021
>> 15  71 212   37 5   6 195
>> 24  45 272   4330   7  85ANT DLY  77 ns
>> 17  28  97   3719  19 124Position
>> 
>> 13  55 140   38  MODE Hold
>> 14  39  58   39
>> 23  33 291   44  LAT  N  51:xxx
>> 10  17 324   40  LON  E   5:xxx
>> 12   7 212   34  HGT   +27.54 m
>> (MSL)
>> 
>> 
>> 
>> 
>> ELEV MASK  5 deg
>> ---
>> 
>> Command complete
>> 
>> Unfortunately it never went GPS locked. Longer story short: the pin of the
>> OCXO that (I think) should produce a Vref for the EFC circuitry produced
>> some random ~ 266mV. 
>> 
>> A quick experiment learned that the OCXO freq responds to the EFC voltage. 
>> So, looks like the Vref circuit in the OCXO has died.
>> 
>> Now the question: has anyone a working unit that they can measure the
>> correct Vref voltage from?  
>> 
>> For now I have fitted a 2.5V LM336 vref and I
>> see the EFC voltage go up and down a bit, with the output freq hovering
>> around 10MHz (+/- 4mHz roughly).
>> 
>> tia,
>> Wilko
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[time-nuts] Re: help reviving Trimble UCCM-LPS GPSDO

[Wilko Bulte]

> On 23 Dec 2021, at 18:58, Attila Kinali  wrote:
> 
> On Thu, 23 Dec 2021 12:14:48 -0500
> Bob kb8tq  wrote:
> 
>> It’s a pretty good bet that the Vref is 5V
> 
> A quick google lead me to this forum post:
> https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/1325/
> 
> Looks like the Vref is supposed to be 2.5V

For the Symmetricom UCCM or for the Trimble?

These UCCM are form-fit-function compatible but that does not mean the circuits 
are the same. Or the OcXO. 

Samsung also produced UCCM, of which I have 2, both working fine. Again 
different circuits, different GPS etc. 

Wilko
> 
>Attila Kinali
> -- 
> The driving force behind research is the question: "Why?"
> There are things we don't understand and things we always 
> wonder about. And that's why we do research.
>-- Kobayashi Makoto
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[time-nuts] Re: Why do have OCXO a Vref output? (was: help reviving Trimble UCCM-LPS GPSDO)

[Wilko Bulte]

> On 23 Dec 2021, at 18:47, Attila Kinali  wrote:
> 
> On Thu, 23 Dec 2021 14:42:27 +0100
> Wilko Bulte  wrote:
> 
>> A quick experiment learned that the OCXO freq responds to the EFC voltage. 
>> So, looks like the Vref circuit in the OCXO has died.
> 
> A stupid side question: Why do have OCXO a Vref output in the
> first place?
> 
> I can see that some form of reference might make stabilizing
> the power in the crystal easier, but that still wouldn't make
> it necessary to have an actual reference output.

Well, an external disciplining circuit might make good use of a oven stabilised 
reference, at least that is what I assume?

Disciplining circuit uses Vref from the OCXO for a DAC that in turn drives the 
EFC of the OCXO. 

No doubt someone will correct me if that is a wrong assumption :-)

> And related to that: Would supplying the voltage reference
> externally, in case of a broken Vref output, work for whatever
> is inside that needs this reference voltage?

Well, currently I have a 2.5V Vref externally connected. No smoke as of yet 

Wilko

> 
>Attila Kinali
> 
> -- 
> The driving force behind research is the question: "Why?"
> There are things we don't understand and things we always 
> wonder about. And that's why we do research.
>-- Kobayashi Makoto
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[time-nuts] help reviving Trimble UCCM-LPS GPSDO

[Wilko Bulte]

hi,

I am currently trying to revive a Trimble UCCM-LPS ex-telco GPSDO.
The model is a 57963-D according to the PCB silkscreen.

Got the board without its OCXO but luckily my stash of surplus I have
discovered a Trimble OCXO labeled 72345-86. Given that that OCXO also has a
label UCCM-LPS it "should work".

Joining the two resulted in:

UCCM >syst:status?

---
57964-86 serial number  S35DB68332   firmware ver  1.0.0.1-01 Ext
mode
---
Reference Status __   Reference Outputs
___
XX Ext Ref   : [LOS]
  TFOM 2FFOM
3
  UCCM A Status[OCXO WARMUP]

>> GPS: [phase:-2.8E-09, settling]
ACQUISITION ...[GPS 1PPS
Valid]
Tracking: 8    Not Tracking: 3    Time

PRN  El  Az  C/N   PRN  El  AzGPS  13:28:51 23 Dec
2021
 15  71 212   37 5   6 195
 24  45 272   4330   7  85ANT DLY  77 ns
 17  28  97   3719  19 124Position

 13  55 140   38  MODE Hold
 14  39  58   39
 23  33 291   44  LAT  N  51:xxx
 10  17 324   40  LON  E   5:xxx
 12   7 212   34  HGT   +27.54 m
(MSL)




ELEV MASK  5 deg
---

Command complete

Unfortunately it never went GPS locked. Longer story short: the pin of the
OCXO that (I think) should produce a Vref for the EFC circuitry produced
some random ~ 266mV. 

A quick experiment learned that the OCXO freq responds to the EFC voltage. 
So, looks like the Vref circuit in the OCXO has died.

Now the question: has anyone a working unit that they can measure the
correct Vref voltage from?  

For now I have fitted a 2.5V LM336 vref and I
see the EFC voltage go up and down a bit, with the output freq hovering
around 10MHz (+/- 4mHz roughly).

tia,
Wilko
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[time-nuts] Re: Efratom MBF 5MHz distrib amp schematics & conversion to 10MHz

[Wilko Bulte]

hi,

As a FYI:

Over the weekend I have checked 5 of these 5MHz MBF amplifiers. I think I can
conclude that Efratom/Ball has individually matched C41 and C42 to the 5MHz
center frequency. In other words: check what your amp has installed, even 1
capacitor might be > 180pF. Happened to me on one unit.

Sofar all amps I could get centered on 10MHz with 150 or 180pF total
capacitance.

Maybe even better 'peaking' can be achieved with a differen toroid coil but 
I decided that that was too much hassle (these things are attached to the
PCB globs of silicone sealant "goo").

Wilko

Quoting Wilko Bulte, who wrote on Mon, Nov 08, 2021 at 05:43:33PM +0100 ..
> hi,
> 
> With many thanks to my ham pal Robert PE1MJA for patiently reverse
> engineering it please find attached the schematics for the Efratom MBF 5MHz 
> distribution amplifier.
> 
> Note that the MBF distrib amps come in different versions, the schematics 
> show the 5MHz in / 5MHz out version.
> 
> Given that we want to use them for 10MHz a small change proved to be
> required: 
> 
> - in the 1-st stage removing the 750pF capacitor (center bottom) made the 
> center frequency of the amp move to 10MHz. That cap is in parallel with an
> 180pF cap, leave that one in place. The cap to be removed is marked as C42
> on the PCB silkscreen.
> 
> The amps are quite narrowly 'peaked' on their design frequency, in its 
> original
> form the MBF was not much of an amp for 10MHz.
> 
> We have both MBF with BNC outputs, as well as units for internal
> distribution via their DIN41612 rear connectors. Both versions have 
> slightly different parts values in places.
> 
> In two of my own units I found 2 different values for C42. Regardless,
> ensuring that the total capacity is at ~180 pF peaked the amp at 10MHz. So,
> also do inspect the cap in parallel with C42.
> 
> Yet to be resolved is the red Fault LED remaining lit with 10MHz, for now I
> am ignoring that one.
> 
> Wilko
> PA1WBU
> 
> NB: I also attached an OpenDocument spreadsheet with the connector pinouts 
> for the various modules.




--- End of quoted text ---
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[time-nuts] Re: What to expect from rubidium lock behavior?

[Wilko Bulte]

hi Paul, Bob,

Is there a significant difference between these telco-surplus Rb and the more 
'fancy' ones in this regard? 

I happen to own an Efratom MRK-HLN, which, I presume, is also more geared 
towards "always on". So, I wonder would the MRK be better or worse compared to 
a telco-surplus unit? Arguably a telco-surplus unit is also of the always-on 
variety or?

best,
Wilko
(newbie trying to get a feel for this)

> On 11 Dec 2021, at 16:27, paul swed  wrote:
> 
> Totally agree with Bob. Same experience.
> 
> 
>> On Sat, Dec 11, 2021 at 8:12 AM Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> Yes, that’s pretty normal operation for any of the telecom Rb’s. They
>> also typically drift about 1x10^-9 over the first day of operation. It’s
>> best to leave them running all the time. Second best is to turn them
>> on a couple days before you need to use them.
>> 
>> Bob
>> 
 On Dec 11, 2021, at 2:23 AM, Erik Kaashoek  wrote:
>>> 
>>> My rubidium frequency standard (Accubeat AR60A) finally got its nice box
>> with good cooling and some LED's showing the status.
>>> While watching the unlock LED I noticed the AR60 say's it is locked,
>> about 4 or 5 minutes after cold start, when the frequency error jumps below
>> about 1e-8
>>> It takes 2 or 3 more minutes of slow drift to become stable within
>> 1e-10. Is this to be expected?
>>> With this locking speed it is tempting to switch off the AR60A unless
>> needed for some measurement. Would daily switching on/off have any impact
>> on lifetime?
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[time-nuts] Re: HP 5065A, no 2nd harmonic.

[Wilko Bulte]

Aha! That is very interesting background information! It nicely puts your 
comment in perspective to "bridge the fuse with a wire and be done with it". 

Big grin here when reading the "beer was involved" comment. I have used a 
similar approach on my business visits to HP CXO (well after T&M was spun off) 
;-). A bit like a certain "beer ware license" (hi Poul).

Wilko

> On 1 Dec 2021, at 20:20, Bob kb8tq  wrote:
> 
> Hi
> 
> The reason for the thermal fuse (which is *not* a feature of other OCXO’s) 
> is the 10811’s deployment in a wide range of devices. There are a few that
> do have restrictions on them. The 5065 is not one of those devices. 
> 
> The protection provided is minimal. The pass transistor will fail in a runaway
> situation. Unless you happen to be on a submarine or something similar
> you are not creating a significant problem when it does. 
> 
> The thermal fuse significantly degrades the reliability of the device. It is 
> by
> far the most likely part in the entire OCXO to fail. Putting up with this 
> failure
> process (and the cost of the fuses) is not reasonable if the benefit is quite
> small. 
> 
> Indeed there was some beer involved in the discussion, but HP OCXO 
> engineering was onboard with the above information last time we chatted 
> about it. That would have been in the early 1990’s …. These failures have
> been going on for a *long* time. 
> 
> Bob
> 
>> On Dec 1, 2021, at 7:41 AM, Wilko Bulte  wrote:
>> 
>> In general it is a very bad idea to defeat safety provisions that a 
>> manufacturer put in their product. They are there for a reason, any 
>> manufacturer would omit them, if only to save on cost. 
>> 
>> I would think no-one on this list would replace a blown fuse in their house 
>> fuse box with a nail. Or?
>> 
>> Wilko
>> 
>>>> On 1 Dec 2021, at 12:13, Askild  wrote:
>>> 
>>> Hi,
>>> 
>>> Just a little warning.
>>> Included are some pictures of a 10811 where thermal fuse protection have
>>> not functioned.
>>> I do not know why, if the fuse did not work, or somebody replaced it with a
>>> wire, as this was in a HP 8663A that I found in a recycling bin, and I do
>>> not know the history.
>>> 
>>> 
>>> Regards,
>>> Askild
>>> 
>>> 
>>> 
>>>> On Tue, Nov 30, 2021 at 8:34 PM Bob kb8tq  wrote:
>>>> 
>>>> Hi
>>>> 
>>>> The thermal fuses die on their own far more often than they die protecting
>>>> anything. The fuse is there to provide safety is certain odd situations.
>>>> The
>>>> simple answer these days is to replace it with a piece of wire.
>>>> 
>>>> Bob
>>>> 
>>>>>> On Nov 30, 2021, at 12:05 PM, Larry McDavid  wrote:
>>>>> 
>>>>> Do these thermal fuses fail spontaneously or is there a common cause?
>>>>> 
>>>>> If the "heater" transistor mounting screws were quite loose, those
>>>> transistors themselves might have overheated and failed. But, a thermal
>>>> fuse should fail by high temperature...
>>>>> 
>>>>> Sounds like progress, though. Cold OCXO means low frequency.
>>>>> 
>>>>> Jared, I sent you a private email with some pictures; did you get that?
>>>>> 
>>>>> Larry
>>>>> 
>>>>> 
>>>>> On 11/30/2021 8:03 AM, Jared Cabot via time-nuts wrote:
>>>>>> Well, I found it, the thermal fuse is open circuit.
>>>>>> If I briefly bypass it with a jumper wire, the oven pulls the expected
>>>> current.
>>>>>> Looks like I need something that will trip at roughly around 115C,
>>>> rated to 1.0A
>>>>>> (HP Part number 10811-80008)
>>>>>> Hopefully I can find something in Akihabara to make it easier to get my
>>>> hands on ASAP...
>>>>>> Jared
>>>>> ...
>>>>> --
>>>>> Best wishes,
>>>>> 
>>>>> Larry McDavid W6FUB
>>>>> Anaheim, California (SE of Los Angeles, near Disneyland)
>>>>> ___
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[time-nuts] Re: Lowest noise (phase noise and ADEV) method to achieve 10 MHz signal from 5 MHz input

[Wilko Bulte]

For those interested, Dave PA5DOF and your's truly are working to get the 
doubler implemented that Luciano has on his website. The first PCB prototype is 
in and has been built and works OK. Some minor tweaks/fixes  will be added to a 
V0.2 PCB. If there is interest I can share the Gerber files. 

The doubler is intended to be hooked up to an Efratom MRK-HLN 5MHz Rb. Our 
shack T&M equipment for the best part requires a 10MHz reference. 

Wilko

> On 29 Nov 2021, at 10:35, tim...@timeok.it wrote:
> 
> 
>   you can use this:
> 
>   
> http://www.timeok.it/wp-content/uploads/2015/08/high-performance-frequency-doublerv1-31.pdf
> 
>   Luciano P. S. Paramithiotti
>   tim...@timeok.it
>   www.timeok.it
> 
>   Da "Matt Huszagh" huszaghm...@gmail.com
>   A time-nuts@lists.febo.com
>   Cc
>   Data Sun, 28 Nov 2021 19:29:58 -0800
>   Oggetto [time-nuts] Lowest noise (phase noise and ADEV) method to achieve 
> 10 MHz signal from 5 MHz input
>   Hi,
> 
>   I've got a 10 MHz distribution amplifier and am considering purchasing a
>   5 MHz reference. Most (not all) of my equipment accepts a 5 MHz
>   reference, but I'd like to be able to use the existing distribution
>   amplifier I have if possible. Therefore, I'm considering ways I might
>   generate a low-noise 10 MHz signal from the 5 MHz reference.
> 
>   An obvious way is to use a doubler. However, as I understand it, even an
>   ideal doubler will add 20log(2)=6 dB of phase noise to the 10 MHz
>   signal. It seems like a possibly more expensive, but lower noise way
>   would be to use a PLL with a divider that locks the divided 10 MHz
>   signal to the 5 MHz input. If the time constant of the loop filter is
>   set long enough, does this avoid the phase noise multiplication issue?
>   From what I've gathered, this is a technique HP used in some of their
>   gear. For example, the 8566 and 8340/1 lock a 100 MHz VCXO to an
>   external reference with a PLL.
> 
>   Any other thoughts on this?
>   Matt
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[time-nuts] Re: Project Great

[Wilko Bulte]

Being curious here: has anyone ever taken a Cs in a submarine? E.g. the 
Marianatrench or so?

As a native from a mountain-deprived country I could not help wondering.

Wilko

> On 28 Nov 2021, at 08:14, Tom Van Baak  wrote:
> 
> Hi Thomas,
> 
> Good to hear the experiment was contagious for you. If you have additional 
> questions let me know.
> 
> Your suggestion about Mount Evans and Pikes Peak are excellent. You will 
> enjoy this 2017 paper:
> 
> "An Undergraduate Test of Gravitational Time Dilation"
> https://arxiv.org/abs/1710.07381
> https://arxiv.org/pdf/1710.07381.pdf
> 
> ---
> 
> As for CSAC, the news is not so good. I've worked with several groups to 
> explore CSAC for gravitational time dilation experiments. Those clocks are so 
> cute and small, it's irresistible; but the numbers just don't add up. Over a 
> day their stability is in the low e-12's vs. a "real" cesium clock like a 
> 5071A in the low e-14's. So when you are doing a relativity experiment trying 
> to detect a frequency shift that's on the order of e-13's you reach for a 
> 5071A instead of a CSAC. The performance is nearly 100 to 1.
> 
> One solution is a taller mountain. The best on the planet is Mauna Kea (Big 
> Island, Hawaii) where you can literally drive from sea level to the summit 
> (13,800 ft, 4200 m) in a few hours. The frequency shift up there is 4.5e-13, 
> which is 40 ns per day. But still, to have even the slightest chance of 
> success you'd want your clocks to be good to 1e-13 or better. CSAC aren't 
> even close, and probably neither are telecom Rb.
> 
> I'm currently involved with another solution -- a HAB (High Altitude Balloon) 
> CSAC flight. Getting to 100,000 ft altitude is quite common. Up there, clocks 
> run a whopping 3.3e-12 faster, which is 280 ns/day, or 12 ns/hour. This is a 
> clear case where the amazing low mass and low power of a CSAC is a  critical 
> advantage. However, the numbers still aren't working out and the logistic and 
> environmental conditions are brutal. I won't say it's impossible, but it may 
> take years and a huge bag of tricks before it works or it's proved too 
> impractical.
> 
> ---
> 
> Jim, I'd be interested in any Cubesat / CSAC results. They don't exactly land 
> in one piece so the typical round-trip clock comparison method wouldn't work. 
> A direct frequency comparison might. In that case the drift and re-trace 
> specs of a CSAC are probably more important than the stability.
> 
> /tvb
> 
> 
>> On 11/27/2021 12:37 PM, Thomas Valerio wrote:
>> I think that Tom's GREAT adventure is kind of what sealed the deal making
>> me a time-nut or at least a time-nuts lurker, a lot of this stuff is still
>> little over my head, but I keep reading.
>> 
>> If anyone is inclined and has the clocks and the kids ( I don't have
>> either ), there is always Mount Evans and Pikes Peak, although you may
>> have to leave the clocks behind overnight.  Mount Evans is still on my
>> bucket list but without clocks and two or three days of time to monitor
>> them, I don't think I will be doing the Mount Evans edition of GREAT.  For
>> anyone that is flush enough to afford or can beg, borrow or steal access
>> to a Microsemi chip scale atomic clock, I think a Mount Evans edition
>> would be an awesome addition to Tom's original work.
>> 
>>Thomas Valerio
>> 
>> 
>>> For newcomers to time-nuts, Andy is asking about my DIY gravitational
>>> time dilation experiment(s).
>>> 
>>>  > What am I missing?
>>> 
>>> It looks like you used the wrong value (or wrong units) for "h".
>>> 
>>> The summit of Mt Rainier is 14411 ft (4400 m), but the highest point on
>>> Mt Rainier that is accessible by road is the Paradise visitors center at
>>> 5400 ft. Our house is at 1000 ft elevation so the net difference in
>>> elevation of the clocks was 4400 ft (1340 m).
>>> 
>>> The clock(s) on the mountain ran fast by gh/c² = 9.8 × 1340 / (3e8)² =
>>> 1.5e-13. Fast clocks gain time. We stayed for about 42 hours so the net
>>> time dilation was 42×3600 × gh/c² = 22 ns.
>>> 
>>> 
>>> 
>>> For more information see the Project G.R.E.A.T. 2005 page:
>>> 
>>> http://leapsecond.com/great2005/
>>> 
>>> Better yet, these two recent talks from 2018 and 2020 cover all 3 GREAT
>>> experiments:
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Lots of time nutty photos in both of those!
>>> 
>>> /tvb
>>> 
>>> 
>>> On 11/27/2021 7:33 AM, Andy Talbot wrote:
 Just been reading your adventures with 3 Cs clocks, a mountain and 3
 kids,
 but I can't make the estimate of time dilation work out.
 You measured ~ 23ns and say it agrees with calculation
 
 The equation quoted in a related reference, for "low elevations" is
 g.h/c²
 which if you plug in g = 9.81 m/s²  and h = 4300m for Mt Rainer gives
 an
 expected 

[time-nuts] Re: List Opinion/Suggestion(s)

[Wilko Bulte]

Another option would be a Meinberg NTP appliance. 
https://www.meinbergglobal.com/

I have implemented a couple (for geographically dispersed data centres) of the 
Meinberg LANtime M300 about 10'years back. They still run without a hitch, and 
have done so without ever failing. "Ours" are dual radio units, GPS and DCF77. 
They also provide 10MHz, the "quality" of which is determined by which XO you 
select. See their website. 

Really well recommended product, German quality ("Gründlichkeit" & 
"Kwalitätsarbeit")

Wilko
(Who also has an M300 in his ham shack, albeit a DCF77-only unit 😀)

> On 22 Nov 2021, at 19:13, Shawn  wrote:
> 
> Hey Guys,
> 
> I'd like to ask for opinions from the list if I could.
> 
> I have a need to put a couple GPSDOs on some remote locations, 10MHz
> output plus NTP.  Found some Spectracom 9183s as well as some
> Symmetricom XLi units on EBay that look like they'd fill the bill.
> 
> The 10MHz will be mostly used by some Service Aggregation Routers to
> re-clock some DS1s that are being transported over packet microwave and
> the NTP is for the computers and cameras, the network is closed off
> from external access.
> 
> I'd really appreciate any insights/gotchas/other suggestions that you
> guys may have in this arena.
> 
> Thanks in advance!
> 
> Shawn
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[time-nuts] Re: GPS Elevation Mask Values.

[Wilko Bulte]

Santa is testing his new SteSle[tm]? *)

Kidding aside, maybe it is an idea to see if the position reported by the 
various GPS starts to "wander"? I assume any spoofing/scrambling should be 
noticable too, apart from the SV plot that LH reports.
Maybe good GPS reject "implausible" SV locations from the location solution?

Wilko

*) Stealthy Sled

> On 16 Nov 2021, at 13:15, Dana Whitlow  wrote:
> 
> Dan, in recent years I've read that DOD (or some such agency) has been
> running
> spoofing tests here and there, but always in remote thinly-populated areas
> (for
> what should be obvious reasons).
> 
> As to why not all your receivers exhibit the "finger", I point out that the
> appearance
> of a GPS satellite "in the hole" must be treated as an exception, and
> different
> combinations of receiver HW & FW with different analysis & display  SW could
> plausibly react differently to such exceptions.  I suppose such behavior
> should
> be called "bugs", but I would not be too harsh on the designers unless this
> "bug"
> also led to erroneous PVT output.
> 
> In any event, about all I can say is "What a grand mystery!".
> 
> Dana
> 
> 
>> On Mon, Nov 15, 2021 at 8:24 PM Dan Kemppainen 
>> wrote:
>> 
>> Hi,
>> 
>> The adafruit board had a run with the LTE-LITE and Ublox. Adafruit board
>> shows no birds above the north pole. Same as does the LTE-LITE on this
>> run. Again, the Ublox shows them up there according to LH. (At least
>> everything is consistent!) (The curious of you can view the attached plots)
>> 
>> Currently running some logs of raw data from all three GPS modules.
>> We'll give the logs 24 hours and run them through U-Center tomorrow.
>> 
>> As for right now, eliminating the antenna and mounting location are the
>> most important part. It's getting to be winter here, and snow makes
>> getting to the antenna difficult/dangerous.
>> 
>> 
>> Dana,
>> 
>> I would be highly surprised if anyone were spoofing GPS here. We're
>> pretty much in the middle of nowhere. Besides, why only Ublox modules
>> giving the fits on LH?
>> 
>> 
>> Keelan,
>> 
>> Thus the confusion as to why there's birds above the north pole. This
>> has happened on two PC's with Two different models of Ublox Modules. Two
>> other brand modules seem OK on LH.
>> 
>> Certainly odd.
>> 
>> Thanks,
>> Dan
>> 
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[time-nuts] Efratom MFS modules for sale to a good time-nut home

[Wilko Bulte]

hi,
I checked with Tom and he OK-ed me posting this:
As you probably have seen my ham buddy Dave & I possess some surplus modules 
from the Efratom MFS that we would like sell to a "time-nutty" enthousiast for 
a "time-nutty" price. Or "amateur price", as we ham's tend to call it here in 
NL. We prefer to not put it 'on the Bay' as you probably can imagine.

We have as surplus:
- MGPS GPSD module to discipline the Rb (the two Rb are 'keepers' ;-) incl 
bulkhead & antenna
- MBU battery backup units (Qty 2)
- MFC 2.048MHz synthesizer module
- MRM monitoring module
- MDC-RR module
The special DIN41612 connectors that go onto the rear of these modules are 
included.
All of it comes from a military mobile sat groundstation, housed in an 
air-conditioned truck mounted sheltercontainer. I tested it before dismantling 
the hulking 6U double rack depth unit. 
Please contact me off-list at w...@xs4all.nl in case you are interested. 
Equipment is located in Arnhem, the Netherlands. Pick-up is OK, as is shipping 
at buyer's cost.
best,
Wilko
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[time-nuts] Re: introduction

[Wilko Bulte]

Thank you Paul!

This was indeed truly remarkable: a complete TSGT transportable satellite 
groundstation truck mountable airco-ed shelter unit, with *all* equipment still 
inside. Up/downconverters, TWT power amplifiers, data modems, antenna steering 
etc. 1990s/early 2000 era.  Unfortunately I was too late in responding to also 
grab the HP 12GHz spectrum analyser and the HP 20GHz sweepgenerator that were 
rackmounted just above the Efratom. But lucky enough to have a guy who bought 
the SA and de sweepgen not recognising what that "light brown Ball Efratom 
thing" was. 8-)

The shelter will become a camper, believe it or not..

Wilko

> On 3 Nov 2021, at 15:19, paul swed  wrote:
> 
> Wilco
> Welcome to time-nuts that does include frequency. That is some military
> surplus find you have. There is little surplus like that in much of the US
> these days. Believe its gathered up and resold to other countries. I never
> see the old surplus dealers that were a lot of fun to visit. Not that even
> back then I could afford shipping for the steel monsters.
> You will find all sorts of very very good technologists here. Ham and
> otherwise. Some do really fantastic projects like restore H Masers. But
> many of us are simply lowly Cesium and Rubidium references and then the
> lazy persons answer a GPDSO. (I like lazy)
> You will fit in well and we always appreciate projects, insights, and
> sharing.
> Enjoy
> Paul
> WB8TSL
> 
>> On Wed, Nov 3, 2021 at 9:32 AM Wilko Bulte  wrote:
>> 
>> hi,
>> 
>> Thought it be good to introduce myself, being new to the list etc.
>> My name is Wilko, I am a ham operator located in Arnhem, the eastern part
>> of the Netherlands, callsign PA1WBU. There is at least one list member that
>> knows me (hi Poul ;)
>> 
>> I recently found myself with 2x UCCM GPSDO, a FEI Rb &  a Meinberg LanTime
>> M300 DCF77 unit. Since, say, 3 weeks I also have an Efratom MFS. A fellow
>> ham and I bought this as military surplus, it had 2x 5MHz Rb MRK, a MGPS, a
>> bunch of MBU battery units, MBF distrib amps, monitoring unit etc. All
>> housed in a rather hefty 6U double depth 19" rackmount box.
>> 
>> Since it has been split in two separate units, each holding a Rb, PSU, and
>> some distrib amps. So the two of us now each have a small 3U Rb reference
>> in our ham shack. And one that does not take up too much space on the bench.
>> 
>> Sounds like the time-nuts (well, frequency-nut) virus has spread :-|
>> 
>> Wilko
>> 
>> NB: we have some MFS modules surplus to requirements, like the MGPS. In
>> case there is interest, please contact me off list. It is better to offer m
>> here tthan sticking them on eBay I suppose?
>> 
>> 
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[time-nuts] introduction

[Wilko Bulte]

hi,

Thought it be good to introduce myself, being new to the list etc.
My name is Wilko, I am a ham operator located in Arnhem, the eastern part of 
the Netherlands, callsign PA1WBU. There is at least one list member that knows 
me (hi Poul ;)

I recently found myself with 2x UCCM GPSDO, a FEI Rb &  a Meinberg LanTime M300 
DCF77 unit. Since, say, 3 weeks I also have an Efratom MFS. A fellow ham and I 
bought this as military surplus, it had 2x 5MHz Rb MRK, a MGPS, a bunch of MBU 
battery units, MBF distrib amps, monitoring unit etc. All housed in a rather 
hefty 6U double depth 19" rackmount box. 

Since it has been split in two separate units, each holding a Rb, PSU, and some 
distrib amps. So the two of us now each have a small 3U Rb reference in our ham 
shack. And one that does not take up too much space on the bench.

Sounds like the time-nuts (well, frequency-nut) virus has spread :-|

Wilko

NB: we have some MFS modules surplus to requirements, like the MGPS. In case 
there is interest, please contact me off list. It is better to offer m here 
tthan sticking them on eBay I suppose?


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