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Introduction
Ideal for Amateur Radio or Shortwave Listening, the
DXE-ARAV4
Active Receive Antenna
systems (
ARAV4
) offer excellent receiving performance from 100 kHz to 30 MHz using a 3-piece
aluminum antenna element only 102 inches long. DX Engineering’s unique design makes it vastly
superior to traditional active antennas in both strong signal handling and feedline decoupling,
providing significantly better weak signal reception due to lower spurious signal interference and
reduced noise.
Location Considerations
The best place to install your active antenna is where you have the recommended space away from
power lines and
away from your house, tower or any structures which are excellent sources of
noise
. Even passive wiring in a building or metal fencing can act as a pickup antenna and re-radiate
noise.
The
ARAV4
systems can be affected by local noise sources. Local noise can be random or
directional in nature. Every effort must be made to locate sources of noise that could be eliminated
at the source. Dimmer switches, electric timers, photocell-operated security lights, and many other
items can be sources of unwanted noise. Plasma-screen television receivers are a known generator
of unwanted noise interference. Most modern LED or LCD flat panel televisions are not broadband
noise generators.
If the noise source is external and single directional in nature, using two
ARAV4
antennas in
conjunction with the
DXE-NCC-2
Receive Antenna Variable Phasing Controller could allow the
user to phase out the noise being received.
Large transmit antennas
are a very good source of re-
radiated noise.
Ideally your receive antenna should be a minimum of 1/2-wavelength away from any transmit
antenna (on the lowest frequency) to avoid mutual coupling and the transfer of any noise being re-
radiated by the transmit antenna. If the unit is located 1/10-wavelength to 1/2-wavelength from a
transmitting antenna, the unit must be powered off at least
5 ms
before transmitting on the transmit
antenna. However, with this close spacing, coupling from the nearby transmit antennas becomes
more pronounced. At much higher frequencies above 25 MHz, where the active element length
becomes a partial wavelength, coupling increases further. Placing a
DXE-ARAV4
on the same mast
or tower as a Yagi or other transmitting antenna is not recommended for this reason.
When installed closer than 1/2-wavelength on the lowest frequency from a transmit antenna, to
assure highest protection for the active antenna, a
DXE-TVSU-1B
Time Variable Sequencer Unit
should be used to ensure the correct transmit-to-receive switching. The
ARAV4
series active
vertical antenna system grounds the antenna element when power is turned off.
THIS IS A RECEIVE-ONLY SYSTEM
You should
never
attempt to transmit through the system.
The use of bypass relays and sequential timing is required to avoid damage to the
receiver and active antennas in the proximity of transmit antennas.
Placing any active receive system on the same mast or tower as the transmit antenna is
not
recommended.
