[TowerTalk] Ladderline - what are the facts??/

[Jim Brown]

On Wed, 6 May 2009 10:04:52 -0400, Dan Zimmerman N3OX wrote:

>No, cancellation is cancellation.

Think about where the magnetic flux is in a parallel wire line. It 
is MOSTLY between the two conductors, but it also leaks out around 
them. Now, wind that line around a core. Most points within the 
ferrite core is closer to one conductor than the other, so it sees 
more flux from that conductor than the other. In other words, the 
flux in the core is not uniform, so locally, within the core, there 
is not cancellation. If the core has significant loss, that 
difference results in heating. 

Coax is different. 100% of the flux associated with differential 
current is contained within the coax dielectric. Only the flux from 
common mode current is outside the coax and seen by the ferrite 
core. 

73,

Jim K9YC