[time-nuts] Z3815A's hit the scene

Kit Scally kscally at bytecan.com.au
Fri May 4 01:49:19 EDT 2007


This is my first posting to the group having been in
"lurk mode" for a month or so.  

I have been able to "liberate" a quantity of (working)
frequency references used in CDMA base stations for a
small group of enthusiasts in Australia & New Zealand
(the ANZAC T & F Nuts).  It responds to the SCPI command
of *IDN? as a "HEWLETT-PACKARD,Z3815A .

These modules incorporate either HP's ubiquitous
"Hockey-Puck" E1938A oscillator (designed in part by
Rick Karlquist) or an equivalent C-MAC double-ovened
oscillator. The motherboard performs all the necessary
1pps housekeeping from the internal Furuno or Motorola
GPS engine and produces a disciplined 10 MHz output
together with other phase locked frequencies (19.6608
MHz, E1, T1 references etc).  One variant of the units
respond to (nearly ?) all SPCI commands from SatStat, so
there's a lot of available performance data at hand.  

Performance is stunning to say the least - enhanced no
doubt by the E1938A and some very smart on-board

Murray, from across the Tasman (ZL1BPU in New Zealand),
has graciously agreed (persuaded ?) to attempt some
qualification testing on the units and I hope to report
back the details when they come to hand.  (Murray's VNG
Clock in a Box design at
http://www.qsl.net/zl1bpu/MICRO/index.htm  is a cheaper
and simpler approach, but given a double-ovened
oscillator, makes an interesting comparison with the
Z3815A !) 

I can possibly provide 1pps stability and EFC voltage
plots if anyone in the group is interested.  (Programmes
courtesy of Murray, ZL1BPU and Con, ZL2AFP)


Kit Scally




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