[time-nuts] HP Z3817A Reverse Engineering
Ed Palmer
ed_palmer at sasktel.net
Sun Jan 8 17:20:00 UTC 2012
I recently purchased a Motorola STLN4096A with the HP E1938A
oscillator. I bought it for the oscillator only.
Then I got intrigued by the HP Z3817A GPSDO that's included. I've
reverse engineered most of it and I've got it running. The 1 PPS is
really good ( 1000 measurements, Std. Dev. of <200 ps, min to max range
of <1.5 ns) and the HUP is very slowly dropping (currently at 13 us
after ~1.5 days) as the oscillator works out the kinks after it's long
sleep. It's dropping much slower than my Z3801A did when I first turned
it on.
There's one input that I haven't been able to figure out. I've got data
in and 1 PPS in from the GPS receiver. Everything seems to be working
so I'm at a loss what that the other input could be for. There are no
clues to it's function because it appears to go into one of the Xilinx
chips.
Does anyone have any more info on the unit? Has anyone figured out the
other input?
I have searched the net and the archives. There's very little info or
discussion on this unit.
Ed
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