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Conference smurf::ase

Title:ase
Moderator:SMURF::GROSSO
Created:Thu Jul 29 1993
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2114
Total number of notes:7347

2007.0. "BC12N cables for Memory Channel Hubs" by SANITY::PCUMMINGS (The perfect democracy) Fri Apr 18 1997 16:07

    I'm looking for some information on the BC12N-10 Memory Channel Hub
    cables that are used on 2100, 4100, 8400 configurations between
    the system box and the Memory Channel Hubs.
    
    I was told in a TruCluster Configuration and System Management class
    that the cylinders on each BC12N-10 cables were magnets and that these
    need be pushed up so that they are touching the connectors on each of
    the BC12N cable and if they are not, you can wind up with intermittent
    memory channel errors.
    
    Any truth to this? Can someone elaborate on this?
    
    thanx
    /paul
    
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2007.1Sounds mythical...NNTPD::"cherkus@zk3.dec.com"Dave CherkusFri Apr 18 1997 16:5819
It isn't a magnet, it's just a ferrite bead. 

The first batch of MC cables (prototypes) had no beads.

The second had them right up against the connector.

The third had them an inch or two away from the connector.  This was
requested by me and many others because it became impossible to put
the cables on due to bulkhead spacing.  I remember talking to our
favorite MC engineer about this.

I think your instructor probably saw the second generation cables and 
presumed they all had to look that way.

The ferrite bead doesn't slide at all on the new cables.  I wonder
how the instructor is repositioning it.

Dave
[Posted by WWW Notes gateway]
2007.2what's its purpose?SANITY::PCUMMINGSThe perfect democracyFri Apr 18 1997 19:247
    Interesting - guess the instructor was all wet on that one.
    
    So what's the purpose of the ferrite bead ? 
    
    thanx
    /pc
    
2007.3He was partially right...NNTPD::"cherkus@zk3.dec.com"Dave CherkusMon Apr 21 1997 16:218
Ferrite beads are used to remove high frequency noise from
cabling.  In this case I presume it is to remove the noise
generated inside the system cabinet (due to several hundred
megahertz alphas, among other things) from leaving via the
cables.  

Dave
[Posted by WWW Notes gateway]