AOR LA800 Manuel d'utilisateur
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56 MONITORING TIMES June 2013
F
IRST LOOK
MT Takes a Look at the Latest Tech
AOR LA400 and LA800 Loop Antennas
By Bob Grove W8JHD (All photos courtesy of author)
T
his month Monitoring Times
takes a first look at two new
AOR Active Antennas – the
AOR LA400 and LA800 Loop An-
tennas.
Loop antennas are popular
among serious AM band DXers and
many shortwave broadcast listeners.
Their sharp directivity allows them
to be mounted in an orientation that
minimizes interference, both from
co-channel broadcasters as well as
local electrical interference, and which
favors desired signal bearings. Typical
loops can be rotated to favor specific
signal sources.
All receiving antennas can be
subdivided into two classes, active and
passive. Active antennas are equipped
with amplification devices, while pas-
sive antennas depend entirely upon
their hardware configuration for gain.
Among active antennas are simple whips
with base-mounted preamplifiers like L&F
Engineering’s H800 and H900, and loops with
integrated amplification like the AOR LA-400
and LA-800 reviewed in this article. Some
models have remote tuning (like the two AOR
units) while others are integrated with the loop
mounted vertically on top of the tuner/amplifier
box.
The advantage of the remote loop design
is its ability to be positioned away from the lis-
tening position in a location of less interference
and/or better signal pickup. The entire loop/
control box assembly may be suspended from a
glass window with a user-provided suction cup
hook.
❖ AOR LA400 Active Loop
Antenna
AOR recently released a new small foot-
print active antenna – the AOR LA-400 mag-
netic loop. The “magnetic” reference alludes
to the fact that a radio wave is electromagnetic,
possessing both electric (positive and negative
voltages) as well as magnetic (north and south
polarization) properties.
The wire loop of the LA-400 antenna is
actually enclosed in an aluminum shield which
prevents the intrusion of the electric component
in the arriving wave front, but allows the ingress
of the magnetic portion of the field. The major
advantage of such field discrimination is its
resistance to local noise interference which may
be predominantly electric in nature.
❖ Let’s Take a Look
The compact LA-400 is capable of receiv-
ing signals from 10 kHz through 500 MHz, a
substantial bandwidth, indeed. It comes with
about 3-1/2 feet of BNC/BNC coaxial cable to
interconnect the control box with the receiver,
handy for use with many new wide-frequency-
coverage receivers which utilize BNC connec-
tors. If you’re using a shortwave-
only receiver, you’ll probably need
a BNC/PL-259 adapter. An AC wall
adapter is provided to power the 20
dB amplifier.
The 12 inch loop is plugged
directly into the top of the control
box, but for remote mounting, the
user may substitute up to 65 feet of
coaxial cable to interconnect the loop
with the control box. Such remote
mounting will also require the short
LAN control cable to be replaced by
a longer cable.
The front panel sports a power
switch, a rotary band switch, and a
fine tuning control. Four positions
of the band switch allow selection
of frequency bands from 150 kHz
to 30 MHz. A fifth position selects
a broadband amplifier allowing un-
tuned reception continuously from
10 kHz through at least 500 MHz.
❖ Now, Let’s Try it Out!
With the LA-400 sitting on my radio
bench, I plugged its output into my WiNRADiO
G39DDCe wide coverage receiver. As with any
indoor antenna, I knew this would not be an
interference-free location.
Table One: LA400 Magnetic Loop
Antenna Specifications
Frequency Range 10 kHz - 500 MHz
Unaligned Range 10 kHz - 150 kHz and 30 MHz -
500 MHz
Gain 20dB minimum
Operating Temperature 14 to 140 deg F
Power Requirements 9-15 VDC, 80mA @ 12VDC
Antenna Impedance 50 ohms
Sizes:
Loop 12 inches (305mm diameter
Loop Element 12-inches (W) x 14.4-inches (H)
x 1.5-inches (D)
Control Box 4.6 inches (W) x 2.3-inches (H)
x 4.4-inches (D)
All Assembled 11.8-inches (W) x 16.7-inches (H)
x 4.33-inches (D)
Weight: Loop Element 7.7 ounces and Control Box 10.5
ounces
Supplied Accessories: 12-inch control cable (LAN type);
AC power supply; BNC (F)/BNC (F) RG-58U coaxial
cable (38-inch), and a printed user manual.
Note: LA400 is not intended for transmit purposes and is
not waterproof (for indoor use only).
My first experiment was to test the directiv-
ity of the loop on local AM broadcasters. Select-
ing the broadband mode, the loop exhibited its
expected bidirectional pattern from the lowest
frequencies well into shortwave. Above that, the
pattern becomes distorted with the loop finally
behaving more like an omnidirectional whip
AOR LA400 Active Antenna Package Contents
– The AOR LA400 comes with the remote-
mountable loop, tunable preamplifier, AC wall
adapter, BNC RF cable, LAN control cable, and
operator’s manual.
AOR LA400 Active Antenna Control Box – The control box has a
front panel power switch, band switch, and fine tuning control. A
BNC connector atop the case permits direct loop attachment or ac-
commodation for a remote cable
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Résumé du contenu
Page 1 - IRST LOOK
56 MONITORING TIMES June 2013FIRST LOOKMT Takes a Look at the Latest TechAOR LA400 and LA800 Loop AntennasBy Bob Grove W8JHD (All pho
Page 2 - Let’s Check it Oout
June 2013 MONITORING TIMES 57antenna at VHF and UHF. Within the tunable range, the adjustable selectivity is quite sharp, an
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