[time-nuts] Opera coordinator has resigned

J. Forster jfor at quikus.com
Sat Mar 31 19:27:31 UTC 2012


Sorry. "click" is a bad choice of words. It's more a feel as you mate them
than an audible click.

-John

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


> Dear John and all,
>
> I do work in high energy physics and we use LEMO and other standards.
> For some years now, I have started to advertise against LEMO (in
> particular the LEMO 00 size), as it is VERY sensitive to mechanical
> defects and partial connection (yes, you can ..). We have found very
> often defective LEMO connections, which could only be detected via time
> domain reflectometry. Or LEMO interfaces, which changed impedance
> significantly when rotating them in the fully mated position.. this list
> could be extended a lot more. And this famous click when mating is
> inaudible in typical high energy physics electronics barracks.. too much
> fan noise.
>
> In addition, for the very fast signals of modern DAQ systems, LEMO 00 is
> just not up to speed (literally) anymore. If size is not of ultimate
> importance, we switched to SMA, or SMC if size matters.
>
> About this dreadful OPERA fiber connector:
>
> It very much looks like a FC connector. It has a polarisation nut and I
> have to confess having misconnected them more than once myself.
> It might have been beneficial to shorten in this standard the thread
> length so there is no possibility to engage the thread (not even
> partially) when not properly aligned. As the thread is indeed fairly
> long, you can do what seemed to have happened in OPERA.
>
>
> I acknowledge the importance of QA, but also some design-inherent
> features like low power indications should be in place to prevent these
> things from happening.
>
> Regards,
> Achim
>
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