[time-nuts] HP 58501A reference clocks

Steve D kls at ve7fm.com
Sat Mar 26 19:13:50 EDT 2016


Hi group,

I recently purchased an HP 58XXXA or 58501A precision reference clock unit.
The unit is clearly a prototype made by HP for Ericsson GE. The front label
actually says 58XXXA. The serial number of the unit is EGE001P. It has a
GPS antenna in and 10 MHz, 19.2 MHz, 9600 kHz and a 600/300/100 Hz outputs.
Inside is has a main board with part # 58501-60001, a 10 MHz OCXO part #
05071-60219, a Motorola GPS part # 84D43215M02, a hand built board which
generates (likely phase locked) 19.2 MHz from the 10 MHz, a hand built
board to hold the three front mounted LED's and a third party power supply.

At power up the front panel power LED comes on and a second later the GPS
and ALARM LED's toggle on/off in sequence. The main board LED's also all
toggle and then one of them flashes once per second. I can communicate with
the unit via SCPI using 9600/8/N/1 RS232 data.  I was able to verify the
GPS does receive a signal as the time is correct and the date updates but
is 1024 weeks behind(GPS rollover bug). However the "GPS LOCK" and "ALARM"
LED's never do anything. The 10 MHz out the back does travel between
9,999,997 and 10,000,003 Hz which follows the EFC test point voltage that
goes between -5 and +5 volts. I have found very few SCPI commands that
work. At this point they are:

*IDN? which gives: HEWLETT-PACKARD,58501A,0,Fiji_EGE
*CLS
*TST? which gives 1 (possibly indicating a rom error)
PTIME:DATE?
PTIME:TIME?
SYSTEM:ERROR?

I have pulled the four firmware roms and reseated them as well as the
Xilinx chip, it made no difference. So the question is, did it ever work or
has something failed?

I find it to be a fascinating piece of equipment and think the hand built
boards are super cool to see, but lets face it, it would be more fun if it
worked.

I have posted pictures and a firmware dump on the eevblog forum here:
http://www.eevblog.com/forum/testgear/prototype-hpagilent-gps-based-refererence-clocks-generator/

I'm coming to this group to see if anyone has any ideas or knowledge of the
unit.

thank you!

Steve VE7FM


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