[Elecraft] Computer noise problem

[Bozidar Benc]

Hello,

PC in my shack generated lot of noise on my K1, especially on 40 m band.
When I replaced PC's power supply with an older one, the noise decreased
almost by half.

My antenna was 20m long wire with 10:1 transformer at the end, which is
connected to my K1 with 20 m of RG58 cable.

Now the interesting part.
After I added a 10 m long counterpoise to the antenna, the noise from my PC
almost completely vanished!

Does anyone have any explanation?

Another question: Is it clever to ground my K1, and if it is, where on K1 is
the best place to connect ground?

73, Bole, 9A3RR
k1 #1499