The two best practical possible fixes have already been mentioned.

First, move the transmitter as far away as possible from the computer, 
as well as from any other electronics that are connected to the 
computer. You can buy the appropriate audio cable for doing that at 
Radio Shack, Best Buy, etc. I know both stores have 12 foot cables, 
but I have seen them as long as 30 feet from other sources.

Also, try to keep this connecting cable away from the other cables as 
much as possible.

If the RF is getting into the speakers through either the cable that 
runs between the speakers, or the one going from the speakers to the 
computer, or even through the cable from the power supply for the 
speakers, the snap on ferrite beads from Radio Shack may also help, 
but distance is by far the best bet.

Of course, the RF could also be going in through any other cable or 
equipment that is connected to the computer. The quick test for this 
possibility is to disconnect each piece of equipment from the computer 
while the transmitter is running in order to see if you hit paydirt.

One other idea that may reduce the amount of the noise is to simply 
try re-arranging the rat's nest of cables behind your computer. Do 
this while the transmitter is running, and you will know immediately 
if moving the cables around makes a difference.



If none of this works, you may simply have to turn down the speakers 
while the transmitter is running, and monitor the computer through a 
radio.

Also remember to turn off the transmitter when you do not need to use 
it.

Mike Duke, K5XU