[time-nuts] HP Z3817A Reverse Engineering
Robert Benward
rbenward at verizon.net
Mon Jan 9 14:58:00 UTC 2012
Hi Ed,
I just tracked down Fluke and he offered me one, and per your advice I will
try and confirm the condition before purchasing from him (not that there are
alternate sources) . I have the schematics, but taking apart the hocky puck
is another matter, I pry and pry but get nowhere. I don't think it was
designed to take apart. What buggs me is that if I warm up the oven and
stimulate the oscillator with an external signal, it will oscillate. So it
DOES work, and if I go into the puck to trouble shoot it, I probably won't
find anything defective.
Bob
----- Original Message -----
From: "Ed Palmer" <ed_palmer at sasktel.net>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Sunday, January 08, 2012 10:07 PM
Subject: Re: [time-nuts] HP Z3817A Reverse Engineering
> Hi Bob,
>
> I bought mine on eBay from fluke.l for about $114 (including shipping). I
> don't know if he has any more.
>
> He didn't get positive feedback from me. His pictures showed a
> reasonable, used unit. The unit he shipped was dented badly enough that
> it was slightly crushed and appeared to have been out in the rain. It
> does work, but the E1938 seems to be taking a long time to settle down. I
> hope the crystal wasn't damaged when it took the hit that dented the case.
> There is no physical damage to any of the boards. I've dealt with him
> before and was surprised and disappointed that he didn't describe the
> condition better. Buyer beware.
>
> As for your 'lazy' E1938, have you grabbed the schematics and circuit
> description from
>
> http://www.prc68.com/I/HPE1938.shtml ?
>
>
> Ed
>
>
> On 1/8/2012 5:58 PM, Robert Benward wrote:
>> 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
>
>
>
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