[time-nuts] HP Z3817A Reverse Engineering

Azelio Boriani azelio.boriani at screen.it
Sun Jan 8 13:19:24 EST 2012


OK, I wasn't able to find anything else. Moreover the STLN4096A seems to
have a Rb oscillator now from the usual 'bay vendor... so seems confusing
as the Z3817A may be the E1938A mounted on the PCB that can discipline it
or it is another type of unit or whatever else. No picture found until now
using google.
Is the Z3817A like the fig.1 picture you can find here:
http://www.prc68.com/I/HPE1938.shtml ?

On Sun, Jan 8, 2012 at 6:57 PM, Ed Palmer <ed_palmer at sasktel.net> wrote:

> Hi Azelio,
>
> Thanks, but I already found that.  I've moved quite a bit beyond that.
>  That message was  one of the few in the archives that had any significant
> info on this unit.  For some reason, I find that surprising.
>
> Ed
>
>
> On 1/8/2012 11:33 AM, Azelio Boriani wrote:
>
>> Have you already this?
>>
>>
>>
>> On the TIB (P1) DB-25 connector, I'm fairly confident about these:
>>
>> V+ pins 1 and 21
>> V- pins 8 and 25
>> 10MHz #1 pins 2/15 xfmr coupled, ~4.6V into 1M
>> 10MHz #2 pins 23/16 xfmr coupled, ~4.6V into 1M
>> 1PPS pin 14
>>
>> Supply voltage is dictated by Lucent DC-DC converter. Input is 18-36V,
>> 1.9A.
>>
>> Still chasing down the other pins. Currently I am working on a possible
>> disciplining input:
>>
>> input of some kind to U6/3 via 100 ohms pin 18, prob. diff with 4
>> input of some kind to U6/2 via 100 ohms pin 4, prob. diff with 18
>>
>> The MMI (J1) DB-9 connector is RS-232, 9600baud, 8n1 and runs a a
>> familiar SCPI interface.
>>
>>
>>
>>
>>
>> On Sun, Jan 8, 2012 at 6:20 PM, Ed Palmer<ed_palmer at sasktel.net>  wrote:
>>
>>  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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