Jack Painter wrote:
wrote
So, if coax is kept inside the tubing, there is no stray rf and
therefore a choke or balun is not needed?

Gary did a good job of answering your questions, but I am reinforcing
what
he said.

By design, the J-Pole may allow feedline radiation: None, a little,
or a
lot, depending on the users unique configurations of feedline length,
design
frequency, and accuracy of matching-stub construction, etc. Therefore
an
isolating 1:1 Balun or coils of feedline (choke) at the feedpoint of
the
antenna are highly recommended. Routing the coax inside the variable
lenth
of the main antenna length to get to the shorting (matching) stub
would have
little or no effect on preventing feedline radiation, if your design
was
subject to it in the first place.


Are you saying the shield must be grounded to a surge supressor to
prevent lightening stikes?

Not everyone is subject to lightning, and for some it is rare enough
that
they choose not to worry about it. But if lightning protection design
is
used, it requires shield-grounding. Coax shield (braid, solid, any
kind)
must be grounded, and at several points depending on the tower
height, mast,
length of feedline, etc. In order for lightning arrestors (more
commonly
called SPD or Surge Protection Device) to work properly, the coax
shield
must be well grounded *before* it is connected to the arrestor/surge
device.
That's another whole subject and we have explained your J-pole
doesn't
"need" grounding several times. A copper J-Pole however, is about as
attractive a point for lightning attachment as you could offer. It is
also
subject to the same levels of static electricity that any airborne
antenna
picks up. Act according to your individual desire for survival there.


My ideas was to run the wire inside and even make the coaxle
connections inside the tubing with wire terminals and screws, so as
to
keep everything neat and weath proof.

That would be a really neat and pretty wx-proof design, but a lot of
work.
There might be an easier way to wx-proof it, mentioned later.


What if you used a non insulated pvc type pipe to connect the stub
and
verticle element?

The cross-connector is a shorting, matching "bar", as Gary warned you
against using the word "stub" if that was going to confuse anyone
because it
is not a waveguide or filter or anything else the word stub is
normally used
to describe. Therefore it could never be made of an insulating
dialectric
such as PVC. You could however hot-dip coat the whole antenna in
plastic or
rubber if you wanted to really wx-proof it, and this would eliminate
the
difficult inside-assembly of coax in the tubing that your proposed.

One final note: the J-Pole is no miracle antenna. It's has zero gain
when
compared to any vertical antenna, and its entire attraction is it
"fairly"
easy construction, and very inexpensive construction materials. To
get as
*reliable* a vertical antenna for marine use that I required, might
have
cost well over $100. At or above that level the vertical antennas of
5/8
wavelength can normally provide gain of 6-10 dbi, and I do not want
to get
into what that is compared to as it has been hashed over a million
times. I
would leave it at "there will be considerable gain possible in
vertical
designs over the J-Pole". You have to be willing to pay for that.
Most users
are happy with J-Pole performance so it's record stands pretty well
on its
own.

73,
Jack Painter
Virginia Beach, Virginia

What type of verticle are you talking about, like a ground plane? Would
a ground plane be a better antenna for 2meters?