[time-nuts] HP Z3817A Reverse Engineering

[Robert Benward]

Hi Ed,
May I ask where did you get your STLN4096A and what you paid for it?  Do 
they have any more?

My E1938 recently crapped out.  If I put a substitute 10MHz near the first 
buffer, the PIC processor comes alive, then I can remove the 10MHz and it 
begins to oscillate on it's own.  I can quickly recycle power and it still 
oscillates.  Let it cool down and I need to repeat the "stimulus" procedure. 
Anybody have any ideas?

Thanks,
Bob

----- Original Message ----- 
From: "Ed Palmer" <ed_palmer at sasktel.net>
To: "Time-Nuts" <time-nuts at febo.com>
Sent: Sunday, January 08, 2012 12:20 PM
Subject: [time-nuts] HP Z3817A Reverse Engineering


>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
>
>
>
>