[Elecraft] Stealth! (was: net report...)
Ron D'Eau Claire
[email protected]
Tue Feb 17 12:03:06 2004
A couple of other options that I have used in apartments are:
A doublet in the attic space under the roof. It's possible to get a
full-size 40 meter dipole in there with a couple of bends in most attics
over a 1000 sq. ft. condo or apartment. But if you use open wire feeder
(stealth open wire described below) and an ATU you don't care about =
exact
lengths. Most places have an access hatch to the attic in a closet. =
Route
the antenna away from wiring and metal pipes as much as possible. I =
always
kept it just under the rafters following the roof line as sort of an
"inverted V" with the feed point at the highest point on the ridge. In =
one
place I had with "cathedral" ceilings, I ran a wire with insulation that
matched the paint running along corners or other un-obvious places high =
on
the ceiling line. My favorite feeder was "open wire" line - two small
conductors the same color as the wall, running parallel to each other =
and
held in place with staples or push-pins into the drywall (gypsum) board. =
I
just mounted my wires against the board. Some ops want it spaced even a =
1/4
in from the wall, so they wrap it around push-pins (and no, the wrap =
around
the pin will NOT interfere with operation on HF - it's not enough =
inductance
to bother with). =20
On my QRP rig, I used a small homebrew balanced tuner about half the =
size of
my K2 mounted on couple of small nails like you'd use for pictures on =
the
wall just above the operating desk. Visitors had to find the tuner =
before
they could find and trace the antenna and feed line. Worked a LOT of DX =
on
40, 30, 20 meter CW with such an installation running 15 watts out.
Consider an end fed wire, especially if your operating desk is near a
window. Small enameled wire is invisible from a few feet away. In one
apartment, I used a slingshot to throw the far end over a tall tree a =
few
feet from the window. Actually, I threw a loop of fishing leader =
attached to
a small weight over the tree, and another loop of fishing leader that =
ran
through it stayed with me. Once it was "up", I pulled the second loop =
with
the antenna wire attached to one end of the leader so the fine antenna =
wire
ran out toward the tree until the end was a comfortable distance from =
the
foliage, then I tied my leader end off at the balcony on the second =
floor.
Invisible from the ground or even from the balcony unless one knew =
exactly
what to look for. Stayed up FB too. Loaded it against a counterpoise =
running
along the baseboard in the second floor apartment.=20
At power levels up to 15 watts or so the RF exposure is completely
negligible with such antennas on HF, even inside the apartment, =
according to
the 'experts'.=20
Ron AC7AC