On 13 sep, 17:17, John Smith wrote:
On 9/13/2010 1:01 PM, Owen Duffy wrote:

...
I might note here that a Trask 4:1 current balun is not a Guanella current
4:1 balun, they have quite different connections. The argument that Trask
makes in support of his design on a single core does not apply to the
Guanella design.

Owen

You might want to note that to Trask, he thinks it IS a current balun
... since it has the appearance of two 1:1 current baluns used on a
single core, I tend to agree with his take on it.

Regards,
JS

Owen

It is obvious, We are talking about different things. Fields always
will induce common mode currents in conductors, then it is virtually
impossible totally remove it. We also will have commond mode currents
in our line if our ham neigbourhood turn on his TX or our wife talk
near with her celluar phone...
When I (or "we") talk about interrupt common mode current with choke
(or isolator) I am not thinking in prevent all possibles induction
fields over the conductors. The goal is interrupt a current that would
have in a point if the device (choke) it was not there (neither you
hope for ideal behavior, we must be consecuent).
In this sense no puntual devices can avoid induction laws. Also, a
good isolator it is a capacitor and always will allow displacement
currents.

From electromagnetic point of view the inductor field beyond the
isolator it is functionally similar to any other external field. Even
if you install a five meter optical fiber with a pair of tranducers
isolator betewen a line section you can not prevent electromagnetic
coupling. Similar situation if we buy our ideal balun and then we run
our line parallel to antenna :)

Do you search for a TL incapable to induce external fields?, then we
are not talking about baluns, perhaps we could talk about EM shieding
of the TL.

73

Miguel LU6ETJ