I get it, and then maybe once it's all set, I could put end-caps on the top
and the bottom of the vertical segment to keep it dry. Maybe it would be
good to put in some kind of fastener, too, holding the flexible braid
immobile against the interior of the downward-pointing vertical segment ---
before the installation of the end-caps, obviously.
I like it --- simple but effective.
But does the horizontal segment have to be an entire meter, though? I think
I can remeber seeing those T-like, FM antennas mounted on large towers but
with horizontal segments that were shorter than a meter --- I think they
were slightly shorter than the vertical segments.

--
73
Tom H
VA7FAB

On 17-Mar-2005, "tom" wrote:

I get it, and then maybe once it's all set, I could put end-caps on the top
and the bottom of the vertical segment to keep it dry. Maybe it would be
good to put in some kind of fastener, too, holding the flexible braid
immobile against the interior of the downward-pointing vertical segment ---
before the installation of the end-caps, obviously.

Yes, I omitted those refinements as sort of obvious.

But does the horizontal segment have to be an entire meter, though? I think
I can remeber seeing those T-like, FM antennas mounted on large towers but
with horizontal segments that were shorter than a meter --- I think they
were slightly shorter than the vertical segments.

I chose the one meter length arbitrarily so that it would be about a half wave. The idea is that
the feedline should be kept at right angles to the radiator for some distance. A coil of coax where
the feedling exits the PVC might be a good idea to reduce coupling.

73,
-ken-

If the idea of the coiled-feedline balun is to prevent the outer braid from
turning into a radiating element, wouldn't it be preferable to position the
coils in the feedline next to the antenna feedpoint instead of at the
opposite end of the horizontal segment? Or would there be harmfull,
inductive coupling to the the coils if they were that close to the
feedpoint?
Also, if one were to use a ferrite-bead type balun (not the type that the
feedline is wrapped around) instead of a coiled-feedline type balun, do you
think it would it be necessary to have electrical contact between the
ferrite-bead and the outer braid (necessitating stripping the outer
insulation)?


--
73
Tom H
VA7FAB

Tom, you are making this waaaay too complicated. Just solder up a
ground plane on an SO-239, hook a coax to it and start transmitting.
You don't even need welding rod. I have used coat hanger wire in the
past. Forget about baluns, beads and inductive coupling. We're not
launching a spacecraft here. Keep it simple.

Dick - W6CCD

On Fri, 18 Mar 2005 20:17:24 GMT, "tom" wrote:

If the idea of the coiled-feedline balun is to prevent the outer braid from
turning into a radiating element, wouldn't it be preferable to position the
coils in the feedline next to the antenna feedpoint instead of at the
opposite end of the horizontal segment? Or would there be harmfull,
inductive coupling to the the coils if they were that close to the
feedpoint?
Also, if one were to use a ferrite-bead type balun (not the type that the
feedline is wrapped around) instead of a coiled-feedline type balun, do you
think it would it be necessary to have electrical contact between the
ferrite-bead and the outer braid (necessitating stripping the outer
insulation)?