Until you have the two units tied together and GPS ok and the Fault light
out, you won't see the 15 MHz signal. You should see a 5 volt pp square wave
of sorts coming out of the 10 MHz port.
I found a clean 10 MHz signal on the collector of Q208 and several other
points. These are on the back side of the board, near the 15 MHz connector.
I am trying to find out how they triple the 5 MHz to get 15 MHz. Maybe it
can be changed to just double to 10 MHz. There are a few inductors on the
board and that may make for a filter.
I don't yet have a computer connected. Does the SatStat program run under
windows?
Regards,
Tom
----- Original Message -----
From: "Anthony Roby" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Tuesday, October 28, 2014 10:52 PM
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,
Z3811A, Z3812A GPSDO system
I played around today with these interfaces and couldn't get anything out
of them. I still don't have my GPS connected, but I would have thought I'd
see something out of one of the ports. I tested the serial port on my PC
and that is working, but I don't see anything of note coming off the RFTGs.
I have not connected both together through J5 - maybe that's the next thing
to try. Any particular reason why the -ve side of the RS422 signal is used
vs. the +ve?
I was able also to get SatStat and the RFTG software running on Windows XP
under VirtualBox. Hopefully once I get a signal out of the units, that
software will be stable.
Anthony
-----Original Message-----
From: time-nuts [mailto:[email protected]] On Behalf Of Stewart
Cobb
Sent: Sunday, October 19, 2014 11:53 PM
To: [email protected]
Subject: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,
Z3811A, Z3812A GPSDO system
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.
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