[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

Bob Camp kb8tq at n1k.org
Wed Oct 29 20:11:12 EDT 2014


There are a few possible variations:

1) Different power supply voltages

2) Cheating RS-232 versus a proper RS-422 converter

3) The “right” interface cable (what ever it’s pinout is) versus a VGA cable ( or no cable at all…)

4)  The HP interface versus the Lucent one

5) Windows 3.11 versus Windows 10 beta (or maybe something in-between). 

I’m only observing that some have had more luck with these than others. Since they are all NOS, they should all work. That suggests one or another hookup issue. I don’t think there is any need for ultra long detail lists. Stu took care a lot of that. I don’t have one, so at this point I’m just an observer on the sidelines. 


> On Oct 29, 2014, at 7:33 PM, Tom Miller <tmiller11147 at verizon.net> wrote:
> Hi Bob,
> Most of the answers were covered with Stu Cobb's original message from 10/20/14 copied below.
> ----- Original Message ----- From: "Bob Camp" <kb8tq at n1k.org>
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Sent: Wednesday, October 29, 2014 6:55 PM
> Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,Z3811A, Z3812A GPSDO system
>> Hi
>> One thing that might help others who are having issues with these units:
>> Which pins did power go to?
>> Which pins do you see RX (and maybe TX) data on?
>> Which cables went where (and their pinout) to interconnect this or that?
>> What software are you using?
>> Yes, One could make some pretty quick guesses at most of this. It’s often a quick guess gone wrong that messes people up …
>> Bob
> ____________________________________
> 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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