[RFI] Several USB cables - single toroid

[Jim Brown]

On 2/20/2024 6:12 PM, K9MA wrote:
> One problem I can see with several cables through one core is that the 
> currents in the wires may be out of phase, rather that true common mode. 
> Imagine the two halves of a zip cord dipole meeting at the core, then 
> passing through it as a transmission line. The currents would just 
> cancel each other out, resulting in no flux

What you're describing is out of POLARITY, not Phase.  Polarity has two 
values, is the positive or negative sense of a waveform, which gets 
reversed by turning around the wires or running the signal through an 
inverting stage.

Phase is a continuous function, measured in degrees or radians, it's 
different for every frequency. So yes, it's quite likely that common 
mode current (which is determined by the rest of the antenna that each 
is a part of) are varying degrees out of phase with each other. And yes, 
it's a very good reason not to wind multiple cables through the same core.

73, Jim K9YC