Most local noise is conductive. That is, it comes from the source and
the sink residing on the same breaker in the panel. The source noise
current injects itself into the sensitive sink side that is sharing
the path. By using an extension cord, you can confirm this by
powering the noise source off another outlet that goes to a different
breaker. That noise that is not conductive is radiative. It arrives
from the source through the air. This can be nipped in the bud by
using a transmission line choke at its entry (generally the feedpoint
of the antenna).

73's
Richard Clark, KB7QHC

Is this true for all antenna designs? Is this choke various depending on other
characteristics of antenna and feedline.

For example, in my anticipated 160m full wave loop which I plan to feed with diy ladder
line to a Johnson Matchbox (250w), is there a specific recommendation for such a choke?
Can I simply make what I need with a few windings of something around another round
something and than wrapp it in rubber tape etc. Is this something I can incorporate
into the hardware system at the antenna feedpoint where I will be attaching the two
ends of my loop to the ladder line?

-bill