[Elecraft] Computer noise problem

[Vic Rosenthal]

Bozidar Benc wrote:

> 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!

Before you added the counterpoise, the shield on the RG58 was acting as 
part of the antenna.  Since the coax ran close to the PC, it picked up 
noise.  After you added the counterpoise, the coax shield was decoupled 
from the antenna (the counterpoise was an odd multiple of 1/4 wavelength 
on 40 meters, so it effectively 'grounds' the coax shield).

Good demonstration of a useful principle!

Vic K2VCO