"scott" jsodellatgmail.com wrote in message
...
Thanks, that's helpful.

I forgot to mention that the ferrites are to be placed on the power brick
side of each cable. Another one on the laptop side would surpress any
interference out of the laptop's internal switchers.

I got another suggestion off-list that shielding the
brick in a grounded steel box might help but given the brick's small size
I
guess I will start with your ferrite sugesstion.

Shielding the box only prevents interference from leaving the box by
radiation, and this will, given the small size of the box, only be in the
VHF-UHF range. HF interference is *always* transferred out of the box by
conduction through a cable. If you check the FCC/CE standards about
radiation limits, you will see that below 30MHz, only limits are given for
conducted emission.

Any suggestions on the best
source for apppropriate ferrite ring cores? In browsing online cataologues
this HF radio novice has found a bewildering variety of ferrite devices
and
materials. I agree that my next task is to find a local radio ham and get
some hands-on help.

Best bet indeed. Ferrites are specified for certain frequency ranges, so you
have to pick the right type here. I'm afraid I can't give you the exact type
from the top of my head, but 4C6 material comes to mind.

Regards,
Meindert