I am surprised the schematics for these have not surfaced yet. Are they not
out of support now?
I got a set and am awaiting on a power supply and some connectors. Anyone
have a source for the latches for the D connectors?
Tom
----- Original Message -----
From: "Anthony Roby" <ar...@antamy.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Thursday, October 23, 2014 10:39 PM
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,
Z3811A, Z3812...
My curiosity got the better of me so I ordered these earlier this week and
received them today.
I've powered both up and quickly measured the 10MHz output. I don't yet
have a GPS antenna feed that I can connect, so couldn't check that out.
And I need to look into why both of the units have the Fault and StdBy
lights illuminated. I was surprised how compact they are and they weight
next to nothing. And they are very nicely made. I took the tops off both
and took some photos (see http://goo.gl/87e8GG), but have not ventured
into unscrewing everything to get to the bottom of the boards. From the
top, I didn't immediately spot anything extra on the board for the 10MHz
out. All the extras appear to be for the GPS, but the underside of the
boards may tell a different story.
Anthony
-----Original Message-----
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
Stewart
Sent: Thursday, October 23, 2014 12:20 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,
Z3811A, Z3812...
My units came in today. What I got appears to be new-in-box. It's probably
the only thing I'll ever get with a blue Agilent sticker on the box. =) It
has a yellow Symmetricom notice inside the box.
The circuit board appears to be the same on both units, but that says
nothing about the firmware, of course. The REF-1 has an Oncore receiver
labeled TM-AB - whichever one that is, small parts to support it, and a
TNC connector for the GPS receiver.
The REF-0 is missing everything related to the receiver, and has an SMA
for the 10MHz output in the space where the REF-1 has the TNC along with a
few extra small parts. This is a shared space with both SMA and TNC pads,
though they don't seem to share the same electrical path. Since the SMA
and TNC share the same physical space, even if the 10MHz is available
somewhere, you'd have to do some surgery on the case before you could
bring it out. Probably by adding a hole in the case for the GPS antenna
and using the pad space for the SMA.
It will be a day or two before I have the bits to apply power and connect
an antenna. So, that's what I know. I'd probably just break something if I
tried to find and bring out the 10MHz, so I'll have to leave that to
someone else. But, the appropriate signals need to get between the boards,
so I wonder what's on the Interface pins? Maybe just arbitration, 1PPS,
and sawtooth comms?
In my case, I do need the 10MHz, so I'm just as happy to have bought both
units at this point. Maybe, down the road, someone will come up with the
mods to convert a REF-1 into a REF-0, and vice versa, unless the firmware
prevents that.
Bob
From: GandalfG8--- via time-nuts <time-nuts@febo.com>
To: time-nuts@febo.com
Sent: Tuesday, October 21, 2014 5:59 AM
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,
Z3811A, Z3812...
It seems from the auction revision table that this seller has been
offering these for some time, so perhaps another "hidden" gem:-), but
it's perhaps also worth noting that if this system functions on similar
principles to earlier RFTG kit then the GPS conditioning is only applied
to the unit actually containing the GPS module, with the other unit
intended as a standby should the first one fail.
In other words, unless the system redundancy is really required most users
would probably only need the GPS based unit, or would at least be better
off buying two of those for the same money that the "matched" pair would
cost.
The only advantage, as far as I'm aware anyway, of the non-GPS unit is
that it contains a 10MHz output.
However, Skip Withrow published modification details in January 2013
showing how straightforward it was to add the the 10MHz output, to the
RFTGm-II-XO module, the PCB location for the socket was already available,
so I would suspect it wouldn't be too difficult on these either.
Regards
Nigel
GM8PZR
In a message dated 20/10/2014 05:53:29 GMT Daylight Time,
stewart.c...@gmail.com writes:
Fellow time-nuts,
This (long) post is a review of the HP/Symmetricom Z3810A (or Z3810AS)
GPSDO system built for Lucent circa 2000. I wrote it because I looked for
more information before I bought one, and couldn't find much.
It's relevant because (as of this writing), you can buy a full system on
the usual auction site for about $150 plus shipping. For those of you
lamenting the dearth of cheap Thunderbolts, this looks like one of the
best deals going. The description of these objects does not include
"GPSDO", so time-nuts may have missed it. Search for one of the part
numbers in the subject line and you should find it.
So what is it? It's a dual GPSDO built by HP as a reference (Redundant
Frequency and Time Generator, or RFTG) for a Lucent cell-phone base
station, built to Lucent's spec KS-24361. Internally, it's a close cousin
of a later-model Z3805A. Externally, it looks to be almost a drop-in
replacement for the earlier RFTG system built to Lucent's spec KS-24019.
That was a redundant system containing one rubidium (LPRO, in the one I
have) and one OCXO in two almost-identical boxes. That spec went through
several revisions with slightly different nameplates and presumably
slightly different internals. You can generally find one or two examples
on the auction site (search for RFTG or KS-24019).
This system is similar, but the two boxes each contain a Milliren
(MTI) 260-0624-C 5.000MHz DOCXO, and neither contains a rubidium. The
Milliren DOXCO is the same one used in the later models of the HP Z3805A /
58503A. It's a very high-performance DOCXO, in the same class as the
legendary HP 10811, and better than the one in most surplus Thunderbolts.
The 5 MHz output is multiplied up to 10 MHz in at least one unit, and 15
MHz in both units. I don't have the ability to measure phase noise on
these outputs, but I'd be interested to see the results if someone could.
Nomenclature: The Z3810AS (there always seems to be an "S" at the
end) is a system consisting of the Z3811A (the unit containing a GPS
receiver), the Z3812A (the unit with no GPS receiver), and the Z3809A (a
stupid little interconnect cable). The GPS receiver inside the Z3811A is a
Motorola device, presumably some version of an OnCore.
Where the Z3811A has a TNC GPS antenna input, the Z3812A has an SMA
connector labeled "10MHz TP". That is indeed a 10 MHz output. It comes
active as soon as power is applied to the unit, and its frequency follows
the warmup curve of the OCXO. The two units have identical PCBs (stuffed
slightly differently), and I have no doubt that someone can figure out how
to add a 10 MHz output to the Z3811A as well.
Operation: From the outside, these units are broadly similar to earlier
units in the Lucent RFTG series. The (extremely valuable) website run by
Didier, KO4BB, has a lot of information on those earlier units, much of
which still applies here. The purpose of these units was to provide a
reliable source of frequency and timing information to the cell-site
electronics. The 15 MHz outputs from both units were connected to a power
combiner/splitter and directed to various parts of the transmitter. The
units negotiate with each other so that only one 15 MHz output is active
at a time. The outputs labeled "RS422/1PPS" contained a 4800 baud (?)
serial time code as well as the PPS signal, which were sent to the control
computer.
Power is applied to the connector labeled "+24VDC" and "P1", in exactly
the same way as the earlier RFTG units. Apply +24V to pin 1 and the other
side of the power supply (GND or RTN) to pin 2. In these units, that power
supply goes directly to an isolated Lucent DC/DC converter brick labeled
"IN: DC 18-36, 1.9A". Presumably you can run both units with a 4-amp
supply.
Once you have applied power, connect the Z3809A cable between the jacks
labeled "INTERFACE J5" on each unit. The earlier RFTG units used a special
cable between two DE-9 connectors, and it mattered which end of the cable
connected to which unit. The interconnect for these units is a
high-density DE-15 connector (like a VGA plug). The Z3809A cable is so
short that the two units need to be stacked one above the other, or the
cable won't reach. It doesn't seem to matter which end of the cable goes
to which unit. I don't know whether it's a straight-through cable, or
whether you could use a VGA cable as a substitute.
When you apply power, all the LEDs on the front panel will flash. The "NO
GPS" light will continue flashing until you connect a GPS antenna.
Once it sees a satellite, the light will stop flashing and remain on.
The unit will conduct a self-survey for several hours. Eventually, if all
is well, the Z3812A ("REF 0" on its front panel) will show one green "ON"
light and the Z3811A ("REF 1") will show one yellow "STBY"
light. This means that the Z3812A is actually transmitting its 15MHz
output, and the other one is silently waiting to take over if it fails.
Most time-nuts want to see more than a pretty green light. The old RFTG
series allowed you to hook up a PC to the "RS422/PPS" port and peek under
the hood with a diagnostic program. The program is available on the KO4BB
website. It is written for an old version of Windows, and I had no luck
getting it to run under Windows 7. It does run under WINE (the Windows
emulator for Linux) on Ubuntu 12.04 LTS.
To use it, you need to make an adapter cable to connect the oddball
RS-422 pinout to a conventional PC RS-232 pinout. The adapter cable looks
like this:
RFTG PC
DE-9P DE-9S
7 <----------> 5
8 <----------> 3
9 <----------> 2
(According to the official specs, this is cheating, because you're
connecting the negative side of the differential RS-422 signals to the
RS-232, and ignoring the positive side of the differential signals.
However, it's a standard hack, and it's worked every time I've tried
it.)
With that adapter, you can see the periodic timetag reports from the unit.
The RFTG program will interpret these timetags when it starts up in
"normal mode". However, when I try to use any of the diagnostic features
built into the program, it crashes WINE. The timetag output was required
for compatibility, but I suspect that HP didn't bother to implement the
Lucent diagnostics.
Instead, they added a connector which is not on the previous RFTG series.
That connector is labeled, logically enough, "J8-DIAGNOSTIC".
It too is wired with RS-422, so you need to use the same adapter cable as
before. Once you do, you'll find that this connector speaks the usual HP
SCPI command set (Hooray!). I used the official SATSTAT program (again
under WINE on 12.04 LTS), but I'm sure that other programs written for
this command set will work as well. The default SATSTAT serial port
settings of 9600-8-N-1 worked for me.
After about 24 hours, with a poorly-sited indoor GPS antenna, my system
has converged to TFOM=3, FFOM=0 (the best possible numbers), and a
"predicted 24-hour holdover uncertainty" of 5.2 microseconds, which is not
too shabby. It found the correct day and year without any assistance, so
if it has a "GPS week number rollover" problem, it's still in the future.
I don't currently have the ability to compare the 10 MHz output to
anything else. Again, if someone else can, I'd be interested to see the
results.
Additional Notes: The parts on the boards all have date codes of 1998 or
1999. The Motorola GPS receiver has a firmware label that reads
"02/04/00". The SCPI error logs inside the HP units were virgin when I
first got them. They had 84 and 94 power cycles, respectively.
Before the GPS receiver acquired time, the error log timestamps read
"2000-05-09 00:00:00", which I interpret as a firmware release date.
The PCB has an interesting feature. Next to each soldered-in pin of the
Milliren OCXO is a single-pin socket soldered into the board. I'm guessing
this was used in manufacturing, to temporarily install a Milliren and
confirm that the system worked before permanently soldering it in. (At
production prices, the Milliren would have cost far more than the rest of
the PCB.) You might be able to use this in reverse, if you have a set of
Millirens to test from another source.
The Z3809A interconnect cable has three of the 15 pins on each end clipped
a bit shorter than the rest. Not so short that they won't eventually make
contact, but short enough to make contact later than the rest. Don't know
why, but it's clearly deliberate. A lot of hot-plug connectors are built
that way, including USB connectors. I have no idea what the pinout of the
interconnect is.
The redundant system slaves both DOCXOs to the same GPS reference.
Inside the GPS loop bandwidth, the two oscillators will have almost the
same frequency and will differ only by phase noise and short-term
stability. This is almost a perfect setup for experimenting with certain
kinds of time-nut measurements, assuming someone can figure out how to get
10MHz out of the Z3811A unit. If you then command both units into
holdover, you could measure longer-term stability as well.
The units are described as "new in factory sealed box". After an
archeological investigation of the various strata of labels and tape on
the boxes, I would say that's probably accurate. My set seems to have been
shipped from the Agilent factory in Korea to Symmetricom in Sunnyvale, CA
sometime in August, 2000, shortly after it was built, and remained
untouched until I opened it. I'm guessing it was built and saved as part
of a spares program for Lucent, and kept until Lucent decided they didn't
need spares any more.
I have no connection with the current seller of these units (or any other
sellers, for that matter) except as a satisfied customer. I think I'll
order another set as a spare, before the feeding frenzy hits.
Request for help: Both the SatStat and RFTG programs run under WINE on
stock Ubuntu 12.04 LTS (32-bit) without any tricks or special
configuration. Neither seems to run under WINE on Ubuntu 14.04 LTS
(64-bit). I am a WINE novice. Any hints from WINE experts would be
appreciated. Also, I've been able to run TimeLab under WINE, but I can't
connect it to my USB-to-488 interface, so I can't take data. If anyone can
tell me how to set that up, I'd be extremely grateful.
Cheers!
--Stu
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