Hi Gents,
Building a 7mhz ground plane/vertical dipole here....using
a 69ft self-supporting, grounded, "BX" tower.
I'll have the base of the GP up a little over 1/4-wave, with
9 or 12 radials, sloping downward at ~35 degrees.
Right now, I plan on putting a good bifilar-wound current
balun right at the base. The antenna side will have about
1-inch extra wire so I can clamp on a current meter right
at the balun.
The radials will be insulated from the tower in groups
of 3 or 4, on each of the 3 tower legs. The radials will
feed from the center of the tower (inside) and will be
attached to the "ground" side of the balun. The
other lead of the balun will connect to the aluminum "shelf"
that supports the balun and coax. The shelf mechanically and
RF-wise connects to the 3 tower legs. Those connections
will place the whole antenna at DC gound.
My question is what to do with the shack side of the coax
feed that connects to the balun....fasten to a tower leg just
a couple of feet down or what? I.e, thinking that the
tower might be a bit "hot" with RF there...not sure about that.
Or was my placement of the balun not the best choice? If
chosing a lower location, like level with the lower tips of
the radials, then the question is how to run the balanced
feed out of balun up to the base of the antenna. And that
should be 50-ohm line. Twisted pair (Z is too high) or coax?
Please respond direct with a copy to the reflector.
Steve, K7LXC the TT ADMIN has to figure out how
to get me subscribed again...some kinda problem there that
he's working on. n0tt1 at juno.com
Thanks guys!
73,
Charlie, N0TT
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