Markus Kern wrote: > Hello everyone, > Hi, > I am new to the list and currently looking for a timing standard for a > VLBI application. After some searching I have decided to use two > thunderbolts for a first attempt and now have some questions regarding > the different available versions. > > There seem to be two types of Thunderbolts available on eBay right now. > One is the "flat" board mount version without PSU and which requires > a (+12V, -12V, +5V) power supply. The other is the "boxed" version > with integrated PSU and which requires 24V. These are all old > Thunderbolts with 8 channel GPS. The new Thunderbolt E with 12 > channels obviously doesn't show up on eBay yet. (See [1] for > comparison) > > My first question concerns the power supply. [2] shows that the output > phase noise is significantly dependent on the PSU. How does the > integrated PSU of the boxed version compare to the PSUs tested in [2]? > Is it worth getting the boxed (somewhat more expensive on eBay) version > just for the PSU? > I believe that the blue trace (#3) on the last figure from John Miles' page [3] is with the integrated 24 to -12, +12, +5 V PSU. So you are better off buying a cheap barebones Thunderbolt and a cheap linear PSU. > My second question is about the Thunderbolt's OCXO. [3] shows how to > replace the built in OCXO with a more stable one and suggest that not > all Thunderbolts have the same OCXOs. The bad OCXO in [3] appears to > be from PIEZO and has S/N 1384. The better Thunderbolts apparently > have "10811-class" OCXOs (like the replacement). Neither, > unfortunately, match the labeling of the OCXOs seen on eBay (e.g. [4]). > Is there an easy way to distinguish these different Thunderbolts? > > Thanks, > Markus > > [1] http://www.febo.com/pipermail/time-nuts/2008-May/031370.html > [2] http://www.leapsecond.com/pages/tbolt/noise.htm > [3] http://www.thegleam.com/ke5fx/tbolt.htm > [4] > http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=170300146215 > > Good luck,
-- Sylvain RICHARD _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
