"McSpreader" wrote in message
...
"dickydoo" wrote in
:

I am using it to play midi files thru a sequencer programme
{cakewalk}via a sound module to an amplifier and speakers.
When using power supply there is loud RF noise. Just using
internal battery no RF noise.
Works okay with a borrowed Toshiba.
I noticed the Toshiba has a bigger transformer and maybe has an
RF filter inside.
Is there an RF filter in the Armada transformer? If not would an
RF choke solve my problem ?
Thanks for any help.

The 'transformer' is in fact a switching mode power regulator. These
operate at high frequencies and produce electrical noise signals that
are both conducted and radiated.

If the noise is entering the laptop via the wire, a clip-on ferrite
suppressor may be effective, e.g.:
http://www.maplin.co.uk/module.aspx?ModuleNo=32799&doy=27m8&QV=Y


Thank you.