Owen Duffy wrote in
:

"Ed_G" wrote in
. 192.196:



No, I wouldn't say "shield" would be a proper term, either.
But I
would suggest that a "cancellation" similar to radiation in a
balanced feedline, would be pertinent.


Then I will leave you to your view that the system is balanced.

Owen



I would have preferred an explanation of your view on why it
wouldn't
be, but I thank you for all your prior discussion.

From my first post on the topic:

"If Ed connects parallel line from the centre of the dipole to the hot
and
common terminals of the ATU, there is likely to be common mode current
on the parallel line adjacent to the ATU. If the only connection on
the tx side of the ATU is the coax, then it will also have a common
mode current adjacent to the ATU and near enough to equal to the
common mode current on the other side of the ATU."

Sure, you can fabricate a parallel line from two coaxial lines, it
just has much more loss than a conventional air spaced line... and
although it is short, you intend operating it at extreme VSWR. The
shielded twin line you synthesise does not have any magic properties
in supressing or shielding feed line radiation.

Note that I am avoiding the term balanced line that some have used.
Balance is not forced by line geometry, but is a result of the
environment, so balanced lines are balanced by external factors, not
the line geometry.

Owen

PS: I wonder if you had considered end feeding the Inverted V with the
ATU. IIRC you had a sheet metal roof. You could just fix the tuner to
the roof, connect the ground terminal to the roof sheet, and take a
wire from the ATU output terminal to the end of the inverted V (which
is a continuous conductor across the apex). This is an unbalanced load
connected to an unbalanced output. Is that too easy?




Owen, after reading Roy's explanation, I came back to this one
and what you have been saying is now more clear to me.

I will have to check what is available for end feed on the roof,
but it is a completely rubber covered roof and I doubt there is any
convinent way to access a ground. Tnx.

Ed