[time-nuts] Anyone seeing an issue with PRN2?

[Michael Rothwell]

I'm seeing gpsdo sync loss when PRN 2 becomes visible.

It looks like it had an outage recently:
https://www.navcen.uscg.gov/?Do=constellationStatus
https://www.navcen.uscg.gov/?Do=gpsShowNanu=2017066

Anyone else seeing similar effects?

-- 
Michael Rothwell
mich...@rothwell.us
(828) 649-ROTH
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Poul-Henning Kamp]

In message <8fdafefb-3563-94be-e68d-63fe00164...@earthlink.net>, jimlux writes:
>On 7/9/17 10:27 AM, Bob kb8tq wrote:
>> Hi
>>
>> People *have* been known to sort MiniCircuits parts and use the “extras” in
>> something else. A certain major oscillator manufacturer once bought a bunch
>> of RPD-1’s , sorted them for the “one in a hundred” examples, and then 
>> returned
>> the rest for credit…… Somehow I doubt HP didi it quite that way.
>
>Some manufacturers will cherry pick for you.  Maybe the datasheet says 
>gain is 14 to 18 dB, and you order a batch that you want to be 15.5-16.5 
>dB.. They'll pick those out, but of course, now the remainder have a 
>hole in the distribution.  Particularly when you're buying high-rel or 
>space grade, where they have to 100% test anyway.

I've been told by somebody from HPs manufacturing in Europe that
there were one or two "magic" components where the manufacturer
would send their entire production to HP.

HP would test, measure and sort into four bins: "Failed", "Good",
"Really good" and "HP".

The first three bins got shipped back to the manufacturer.

He suspected that back at the manufacturer, the "Really good"
got a "MIL-GRADE" stamp :-)


-- 
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] J06 HP-59992A time interval calibrator for HP-531xx counters

[Poul-Henning Kamp]

In message 
,
 Mark Sims writes:

>Also coax and RF relays cost a lot.   Pretty soon your BOM cost
>is over what a 59992A will run... assuming you can find one.

The crucial feature of the 59992A was support for DC-bias, and
that seems to have dictated its design.

If you have no need for DC-bias, an 8-pin microcontroller with a
stable crystal and suitable resistor networks on the outputs will
do fine.

TI measurements on top of DC-bias was important in development and
manufacturing of disk drives:  Measurement of jitter of mechanical
origin must happen on the analog side of the differential read
amplifier, which usually balances a couple of volts up for cost
reasons.

-- 
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] Tuning a Symmetricom 1111C

[Ed Palmer]

On 2017-07-10 10:00 AM, Tom Knox  wrote:

Hi Ed;

Thanks for the response. Great logic/detail on potential issues and solutions. 
The power supply issue seems completely intermittent and when running may be 
completely fine. That said I am leaning toward the power supply being the 
issue, it would explain all the issues. I first saw the power supply issue with 
the batteries installed, I removed the fuse and the missing voltages came up 
and the unit locked. before with those voltages absent it was displaying the 
lock light every few seconds after warmup. I had assumed a bad battery had 
created too great a load on the supply. But it failed to come up again when I 
rebooted and then came up again the next time I rebooted. It is either zero or 
correct. I have several problematic 4065's and thought they had 1000B's, I will 
check if any have a C.


Several problematic 4065s??  I can think of a few people that would like 
to have that kind of problem!



It would be easy to swap them and would resolve the question of if these 
problems are related. The unit I have may actually be locking but outside it's 
acceptable EFC range. Phase Noise is exceptional about -120dB @ 1Hz offset 5MHz.


No, I don't think so.  If you look at the manual you'll see that the 
number of tests and measurements the processor makes are such that the 
lock is either good or it's not there.  What you're probably seeing is 
just the performance of the uncontrolled OCXO which is pretty good.  The 
phase noise spec for the 4065C is -106 dBc @ 1 Hz offset.  Your bad 
power supply might actually be improving the phase noise by preventing 
the processor from affecting the OCXO.  It's interesting to note that 
the Allan Deviation at one second for the high performance tube is less 
than half the value of the standard tube.  That means that even at one 
second, the system is affecting and perhaps degrading the raw 
performance of the OCXO.



I will look at solder on the bricks, for the symptoms that could be the issue.


Not just the bricks.  The entire board.  I can't remember where on that 
board I found bad connections.  I think it affected the front panel 
processor.  I think the 5V was low so the front panel randomly 
rebooted.  I didn't make any notes about that.  I know, I'm bad!


I don't know why I didn't think of it before, but you should read 
through this message thread:


https://www.eevblog.com/forum/metrology/no-luck-on-my-first-attempt-at-acquiring-a-cesium-frequency-standard/

I helped a guy repair a Datum 4040A Cesium Standard.  The 4040A and the 
4065A are both built around the Datum 5045A Cesium module.  They then 
have different power supply and user interface 'wrappers' around the 
5045A.  His 4040A had many bad capacitors in the power supply section of 
the 5045A module.  The power supply in question is hidden under the 
metal cover on top of the module where the big circuit board is.  
Unfortunately, he deleted his pictures, but there's still lots of useful 
troubleshooting info on that power supply section.  I made a bunch of 
measurements and posted them so he could compare with his.


If you want to see some pictures of my unit, they're here:

http://s701.photobucket.com/user/edpalmer42/library/Datum%20FTS-4065A?sort=4=1

In the second picture, the power supply is under the sort-of brass 
colored panel with the black and white label.


 Ed

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[time-nuts] 58503B diagnostic information

[Olgierd Dudko]

Hi,
Does anybody know the motherboard diagnostic LED codes for Symmetricom 58503B 
(model of 2007)?
Note, in contrary to the well-documented Z3805A etc., the 58503B has only two 
diodes: red and a green one.
The 58503B seemed failed after a power cycle. Now kind-of reboots itself every 
few seconds. 
Any service hints would be appreciated.

Best regards
Olgierd
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