[time-nuts] Z3815A

Mark C. Stephens marks at non-stop.com.au
Wed May 29 12:02:07 EDT 2013


Hmm, Something is awry with this particular Z3815A:
e.g.
p4th D > efc_rep
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00
0.000000 0.0 0 0.000000e+00 0.000000e+00 0.000000e+00

If I could figure out how to populate it...
efc_comp looks like a likely candidate but, to quote TVB, "I got a little nervous about playing pforth roulette" ...


-marki

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Azelio Boriani
Sent: Thursday, 30 May 2013 12:00 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Z3815A

Here the figures are the same, except: start ptr is 24 and stop ptr is
23 and last efc average is 680694.8 and not 0.0

On Wed, May 29, 2013 at 3:53 PM, Azelio Boriani <azelio.boriani at screen.it> wrote:
> I haven't tracked the Z3815A startup so can't tell when the 
> uncertainty was available. Looking at the log (diag:log:read:all?) I 
> can tell that after the power on you should have a GPS reference valid
> (~12 minutes later) then a GPS lock started and an ACT from unlock (~1 
> second later). Two hours later you should have a position hold mode 
> started and I think that the uncertainty must be available at that 
> point. It will look high but should be available.
>
> On Wed, May 29, 2013 at 3:33 PM, Mark C. Stephens <marks at non-stop.com.au> wrote:
>> Thanks Azelio, That's what I wanted to hear, it does display predicted holdover uncertainty.
>> It still hasn't come up on mine and it's been of for more than 48 
>> hours (uh-oh, everyone says) Without resetting it, can you, from memory, remember when the PHU was displayed?
>> Like right after GPS lock (as per other smart clocks) or some time later?
>>
>>
>> -marki
>>
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] 
>> On Behalf Of Azelio Boriani
>> Sent: Wednesday, 29 May 2013 11:09 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Z3815A
>>
>> The Z3815A here has (right now) 3.4us/24h of holdover uncertainty and -7.0ns PPS relative to GPS. The health monitor and the self test show OK everywhere. It is ON since 12, 2011.
>>
>> On Wed, May 29, 2013 at 1:03 PM, Bob Camp <lists at rtty.us> wrote:
>>> Hi
>>>
>>> Well, probably as good as the manual ... we have the guy who designed it (Rick Karlquist) lurking around here somewhere. I don't think I've ever seen a manual.
>>>
>>> How long have you had the 3815? If not so long, I'd contact the seller. You have indeed convinced me to quickly fire up the next one I have coming in.
>>>
>>> Bob
>>>
>>>
>>> On May 29, 2013, at 2:14 AM, Mark C. Stephens <marks at non-stop.com.au> wrote:
>>>
>>>> Wow the 2 black heatsinks on the puck are really hot - too hot to touch.
>>>> I don't think that would be normal deign.
>>>> They are probably the excessive current sink culprits.
>>>> Anyone got a manual for the e1398a OCXO?
>>>>
>>>>
>>>> -marki
>>>>
>>>> -----Original Message-----
>>>> From: time-nuts-bounces at febo.com 
>>>> [mailto:time-nuts-bounces at febo.com]
>>>> On Behalf Of Mark C. Stephens
>>>> Sent: Wednesday, 29 May 2013 12:36 PM
>>>> To: Discussion of precise time and frequency measurement
>>>> Subject: Re: [time-nuts] Z3815A
>>>>
>>>> I believe these were all rescued from the Tip (Dump, Trash) judging by the water damage and bent cases.
>>>>
>>>> Mine had been tested in Japan and had approximate co-ordinates in it:
>>>> https://www.google.com/search?q=34+44'+N+135+21'+E&oq=34+44'+N+135+
>>>> 21
>>>> '+E
>>>>
>>>> Initially I had a OCXO communication error which I fixed by a 
>>>> :syst:pres (shrug, I thought it was pretty major at the time, I can 
>>>> tell you!)
>>>>
>>>> At the moment it's in an air scrubbed and temperature controlled room, naked, without its case.
>>>> Both heatsinks are just slightly warm to the touch.
>>>> However the Puck is fairly warm..
>>>>
>>>> I still have "Holdover Uncertainty Predict: --" which is a bit of a worry.
>>>>
>>>> Also the 1PPS TI is always about -100ns relative to GPS, which is way out there..
>>>>
>>>>
>>>> -marki
>>>>
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: time-nuts-bounces at febo.com 
>>>> [mailto:time-nuts-bounces at febo.com]
>>>> On Behalf Of Stewart Cobb
>>>> Sent: Wednesday, 29 May 2013 8:13 AM
>>>> To: time-nuts at febo.com
>>>> Subject: Re: [time-nuts] Z3815A
>>>>
>>>> Your Z3815A may need more cooling than it's getting, especially if 
>>>> you have it resting "horizontally" as it looks like it should.  I 
>>>> bought one of those "kits from China" about a year and a half ago.
>>>> Powered it up, waited for it to lock ... and it was dead within a 
>>>> week, with the unmistakable smell of overheated electronics.  One 
>>>> of the Vicor power bricks inside
>>>> (probably) overheated and shorted out.  Here's what I learned:
>>>>
>>>> The Z3815A board was designed to go into a VXI-like mainframe, with a carefully specified amount of cooling airflow.  I think that particular board was designed to require that airflow, and overheats without it.
>>>> There's a group in Australia which has experience with these boxes, and I got the impression from my contacts with them that they see the Vicor bricks fail pretty regularly.  That would imply that they're not getting the cooling they need, because Vicor bricks in other applications are pretty reliable in my experience.
>>>>
>>>> You can see a photo of the original Z3815A on TVB's website here:
>>>>
>>>> <http://www.leapsecond.com/museum/z3815a/>
>>>>
>>>> The Z3815A I got from China was in a different case, just two bent pieces of sheet aluminum.  The case _looks_ official, with the right label on the front and silkscreen on the back.  But the board inside had a lot more crud and corrosion than the nice clean case did, and parts of the plastic edge connector on the back of the board were broken.  Worst of all, the coaxial cable from the antenna connector ended in a one-inch flying lead soldered to the board.  The "shield" of the coax cable ended in another flying lead, soldered to ground somewhere else.  (Any RF engineers reading this are probably cringing now.)  I'm pretty sure that no one at HP designed or approved that connection.  Once I saw it, I understood why the GPS receiver appeared to be "deaf."  Even connected to a very good antenna, it never saw more than 4 satellites, and even those had weak signals.
>>>>
>>>> Did someone in China find a cache of bare Z3815 boards in a scrapyard somewhere, and fab an official-looking case to match?  I don't know, but it might be the way to bet.  Meanwhile, take the lid off your Z3815A and feel the heatsinks on the power bricks.  If they're too hot to touch, they're too hot; give them some air.
>>>>
>>>> Cheers!
>>>> --Stu
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