computer interferance

[K8LEN]

The computer HP<older one>, causes interferance in my yaesu ft857 on 40 and 80 meters only.

I unplugged the monitor to see if that was the problem and it had no effect on it.
On turning off the computer the interferance is slightly reduced, but unplugging the computer from the a/c outlet..all interferance is gone.

Any suggestions appreciated.

Tnx
POB/K8LEN

[K4EEZ]

hi
Adding ferrite Rings, to the 115v Ac mains cable and adding smaller ferrite rings to all other wires that leed from the PSU to the main board and 5v/12/0v devices, also plug the pc in to another out let (other than the one your PSU is plugged in for the radios) will help

of couse, if you like you can take the PC supply apart and locate the missing filter components

coils L1, L2 and missing filter caps ceramic (0.03pf to 500pf @ 500v) also need to install chokes to the psu board the bigger the windings on the chokes the better filter you will make for stopping RFI

http://etutorials.org/shared/images/.../fig128_01.jpg

or just buy a good filtered PSU.

[N0SYA]

Hi
Think in this case you may need to filter the psu in the pc a bit better than it is. Sometimes you can find an ac filter that takes the place of the ac socket on the back of the psu and solder it in, sometimes you can add missing filtering parts left out of the psu as a cost saving measure by the maker. Some ferrites on the ac line may help.