[time-nuts] Opera coordinator has resigned

[J. Forster]

Yes, I am aware of that. Bayonet and threaded connectors can be mated, or
partially mated as I said. This applies to BNC, C, N, HN, TNC, SMA, APC-7,
and MS at least, but not to LEMO and some families of military and
commercial multipin connectors.

Improper mating can easily be seen on a VNA, and can sometimes destroy a
TWTA if it is not protected with an internal isolator.

Normally FO connectors have their faces lapped very flat and exactly
normal to the fiber axis. If they are not lapped properly or mated
properly, the insertion loss increases dramatically.

It was happenstance that the OPERA connector was mated enough to work, but
not enough to work properly.

-John

============




> On Sat, Mar 31, 2012 at 6:23 PM, J. Forster <jfor at quikus.com> wrote:
>> Frankly, I'm a bit surprised at the connector problem. Much of High Energy
>> instrumentation uses LEMO connectors, which have a definite "click"
when
>> mated. They are not like BNCs which can be mated, without locking.
>
> It was an optical bayonet-type connector, not an electrical one. Changes
in optical power induced by the loose connection resulted in big changes
in delay through the mechanism of charging and discharging the
capacitance associated with the photodiode. At least that is my crude
understanding of the matter,
>
>> I rest my case. You simply cannot inspect in quality.
>
> It's hard to disagree with this statement. Who doesn't like quality? I
was trying to go a bit more concrete and suggest that redundant
> systems, especially based on alternative technologies, can help catch
errors which may have gone undetected using other means, like
> inspection and other sanity checks. In fact, if you have experience with
space electronics I think I don't have to convince you of the benefits
of redundancy, as well as of the fact that the probability of making
mistakes is never 0. If you think about it, this whole issue was solved
thanks to redundancy: there was another experiment in the same lab which
detected cosmic muons, and it was through the
> correlation of the muon detections between the two experiments that the
slip between time bases was discovered. I think redundancy is a good
complement, not necessarily a substitute, to other quality
> assurance methods.
>
> Cheers,
>
> Javier
>
>