(I apologize if this is a dupe, I used wrong e-mail account previously)
Hi I am a lurker, finally signed onto the group. Some of this are
probably dumb questions, but I figured this group was the best source of
the info!
Thanks to a NASA auction, I bought for very cheap, a Datum (Symmetricom)
ExacTime 9390-6000 sn 4185. Very clean and unused looking.
Technical trivia: Upon first powering it up, I find coordinates that per
Google Earth show it was last operated in Irvine Calfornia at an office
park on Parker near Toledo Rd! The unit has a label for the SPACEHAB
(Astrotech) project, likely was part of ground testing by some contractor.
I was able to power up and by using a cobbled up coax connection to a
cheapo Garmin GA27 antenna, I was able to acquire 4 satellites tracking
and get lock. I have weak signal here due to trees so had to do a cold
boot and wait about 4 hours to get lock.
Inside I find a TCXO. And it appears, an Oncore receiver is the heart of
this unit.
1) I read that there is a firmware problem with leap seconds. Mine
appears to display UTC accurately (compared to "atomic" wall clock) and
GPS has about a 14 or 15 second offset (Normal I think?).
2) I would like to retrofit a Rb oscillator, can this be done, whats
involved? Parts needed, cables, programming?
3) Where can I find schematic, service manuals and parts list for the
retrofit?
4) Is this a useful unit? Is it functionally an accurate device? I don't
see much discussion about it.
5) There is an option in the "J3" area consisting of J3c a "D" style
connector and J3f a BNC connector. What is this option?
6) Can I determine the available and fitted options from the menu?
Should I assume that if the menu says it can output 100 KHz or 1 KHz
etc, it can do this?
7) It appears to have an event counter for comparing an external
oscillator with the internal. Is this correct?
8) Can the event counter, discipline an external oscillator through a
voltage?
9) The receive signal level units are confusing, is this a level
relative to noise floor?
10) Although tracking and locked, the screen flashes "DOING GPS
CORRECTIONS" periodically. Is this normal?
Any hints or tips to using this unit?
My needs are to provide reference for the HSO in my HP-8920B and to
provide precise timing and phase for some radio projects.
Thanks in advance
--
Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
www.Leikhim.com
jleik...@leikhim.com
407-982-0446
WWW.LEIKHIM.COM
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