[time-nuts] Different Thunderbolt versions

[Markus Kern]

Hello everyone,

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?

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