Can you put a ferrite on the cables at the unit end? If not then internal
to the unit you may be able to use a shielded box with a ferrite to kill
the higher frequencies.

At 10:50 AM 11/14/97 -0000, you wrote:
>Perhaps this isn't the right place for this but I have an EMC problem as
>follows :
>
>A unit with a keyboard and mouse output (both PS/2 type connectors)
>passes class B with no problems UNTIL a keyboard and mouse are attached.
>
>Obviously the internal noise of the unit is being radiated out from the
>cables.
>
>I would like some advice on what to do about this - I have the following
>constraints :
>
>        The keyboard is 'off the shelf', CE marked, not screened and
>cannot be altered.
>        I have the option of making a filter PCB that sits inside the
>unit to filter the PS/2 connectors.
>        I cannot reduce the internal noise of the unit any further -
>mostly 27MHz video clocks.
>
>Any advice or help greatly appreciated.
>
>Is there an EMC maillist out there or any good sites to visit for ideas
>????
>
>       \\\|///
>     \\  - -  // "Yes it IS safe
>      (  @ @  )   to switch on"
>+---oOOo-(_)-oOOo------------------+
>| Mark Birks                       |
>| Hardware Section Leader          |
>| OmniBus Systems, Stanford House, |
>| Stanford-on-Soar,                |
>| Loughborough, Leicestershire. UK.|
>|                                  |
>| Tel/Fax: +44 (0)990 004300/333   |
>| E-Mail: markb@omnibus.co.uk      |
>|   ooo0                           |
>|  (    )   0ooo                   |
>+---\  (----(   )------------------+
>     \_)     ) /
>            (_/
>
>
Larry G. Nelson Sr.
mailto:L.Nelson@ieee.org
http://www.ultranet.com/~nr