Active Antenna Phasing
For Amateur, SWL, Broadcast AM DX
DXE-AAPS3-1P-INS-Revision 0a
© DX Engineering 2012
P.O. Box 1491 ∙ Akron, OH 44309-1491
Phone: (800) 777-0703 ∙ Tech Support and International: (330) 572-3200
Fax: (330) 572-3279 ∙ E-mail:
Table of Contents
System Package and Features
DXE-ARAV3-2P - Active Receive Vertical Antennas
DXE-NCC-1 - Receive Antenna Variable Phasing Unit
Additional Items Needed, But Not Supplied
Technical Description Active Vertical Antennas
Antenna Feedlines
Combining two Vertical Antennas to improve S/N Ratio
Nulling Interference and Noise
Understanding Noise
Basic Tools Required
Active Vertical Antenna Installation
Ground Mounting Rod
Providing a Good RF Ground
Coaxial Cable Feedline
ARAV2 Low Frequency Response - Internal Jumpers
Alternate Mounting
NCC-1 Front Panel Controls and Switches
NCC-1 Rear Panel Connections
NCC-1 Internal Jumpers
NCC-1 Installation
Radio Interface Diagrams
Operating the Receive Phasing System
Manual Updates
Optional Items
Technical Support
Phase nulling with two antennas and a phasing unit allows an operator to hear a desired signal by
reducing or completely removing a much stronger interfering signal arriving from a different
direction, without affecting the desired signal. Ideal for Amateur Radio, Shortwave Listening or
Broadcast AM DX reception, the DXE-AAPS3-1P Active Antenna Phasing System (AAPS) offers
excellent directional receiving performance from 500 kHz to 15 MHz using two high quality
DXE-ARAV3 vertical receive antennas working in conjunction with the outstanding DXE-NCC-1
Receive Antenna Variable Phasing Unit.
DX Engineering’s unique design is 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. Coupled with the DXE-NCC-1 Receive
Antenna Variable Phasing Unit, this package makes up a complete electronically rotatable receive
antenna 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
active receive antenna system.
Placing the active receive system on the same mast or tower as the transmit
antenna is not recommended.
This compact receiving antenna system operates over a very wide bandwidth with superior strong
signal performance. The output Third Order Intercept (TOI) is approximately +30 dBm. This is
significantly better than most aftermarket preamplifiers and receivers - making it one of the cleanest
active antennas on the market, reducing or eliminating spurious signals.
Feedline decoupling, absent in some other popular designs, is also exceptionally good. Decoupling
the shield greatly reduces feedline conducted noise and unwanted signal interference
Any receive system can be affected by local noise sources. Local noise can be random or directional
in nature. First, 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 becoming more popular
and are a known generator of unwanted noise interference. When the noise source is directional in
nature, using the two DXE-ARAV3 receive antennas in conjunction with the DXE-NCC-1 allows
the user to phase out the noise being received.
Ideally your receive antennas 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
passively re-radiated by the transmit antenna. The DXE-ARAV3 series active vertical antenna
system also grounds the receive antenna element when power is turned off for protection of the
active devices.
The DXE-ARAV3 active receive antennas, used in the DXE-AAPS3 package, may be used in
installations when spacing from transmit antennas is at least 1/10-wavelength or more.
When using radio systems and RF amplifiers an optional time sequencer such as the DXE-TVSU1A Time Variable Sequencer Unit should be used to ensure the correct timing while switching
from receive to transmit, and back to receive to protect the active receive antennas.
DXE-AAPS3-1P Active Antenna Phasing System
Package and Features
The two active receive antennas system package DXE-ARAV3-2P is combined with DXE-NCC-1
Noise/Phase Controller to make a steerable dual vertical array.
DXE-ARAV3-2P - Active Receive Vertical Antennas
(Two antennas)
(2) Non-conductive mounting plates
(2) Solid brass element mounting blocks
(2) High quality, 102 in. tapered stainless steel whip antenna elements
(2) AVA-2 Active matching systems w/ Internal Antenna Disconnect Relays
(2) Element connection wires
(2) Sets of Stainless steel clamps and hardware for element assembly
DXE-NCC-1 - Receive Antenna Variable Phasing Unit
Reduce overload or interference by nulling a strong signal or noise before it gets to your receiver
Better and more stable nulling than any other noise canceller or phasing unit on the market
Peak weak signals hidden under a strong signal on the same frequency
Null out local AM broadcast stations
Null out noise from power line arcing, lamp dimmers, motors and consumer electronics arriving
from a single direction
Best alternative to DX Engineering's Receive Four-Square antenna
Combine two antennas to create a directional pattern
The NCC-1 enables you to adjust the antenna array pattern as if you were moving the antennas
Special Features
 Exceptional Dynamic Range, nearly 1000 times better than nearest competitor
 Phasing is voltage controlled allowing precise resetting of phase
 Phasing rotates more than 360 degrees with smooth control
 Built-in two channel voltage controlled attenuator system
 Low noise, high dynamic range amplifiers
 Vastly superior dual channel complementary phasing system
 Very low noise floor
 Separate controls for reversing channel and phase
 Works on all modes, 300 kHz to 30 MHz
 Provides power for external active antennas
 Input for mute on transmit
A sequencer such as the DXE-TVSU-1A should be used to ensure the correct transmit to receive switching
when operating with a high power amplifier.
Additional Items Needed, But Not Supplied
Mounting pipe and/or copper or copper clad ground rod, 1/2" to 3/4" OD, 4 ft. long (included clamps
work with ground rods from 1/2 in. to 3/4 in.)
DXE-F6-CTL - 75 Ω F-6 Style, Direct Bury Coaxial Cable: Full Spool or Custom Cable
Assemblies. Flooded coaxial cable is recommended. CATV F-6 is a high quality 75 Ω flooded
coaxial cable. Flooded coaxial cables automatically seal small accidental cuts or lacerations of the
cable jacket. Flooded cables also prevent shield contamination and can be direct-buried. Contact DX
Engineering to have custom lengths of CATV F-6 cable manufactured with DXE-SNS6 - Snap-NSeal 75 Ω Coaxial Connectors installed.
DXE-CPT-659 - Coax Cable Stripper for CATV F-6, RG-6 and RG-59 coaxial cable. DX
Engineering’s economical stripping tool prepares CATV F-6 style coax for connectors in one
operation and includes an extra cutting cartridge.
DXE-SNS6-25 - Watertight Coaxial Connector, Snap-N-Seal for CATV F-6 Cable, 25 pieces
The feedline shield is used as the ground return for the active antenna power, so the feedline
connections must be high quality and weather resistant. For this reason, it is recommended using
Snap-N-Seal type F connectors DXE-SNS6-25.
DXE-SNS-CT1 - Compression Tool for Snap-N-Seal 75 Ω Coaxial Connectors. The DXESNS6-25 connectors cannot be installed with normal crimping tools or pliers. An installation tool
such as the DXE-SNS-CT1 is essential for proper connector installation.
UMI-82180 - DX Engineering Approved RTV Sealant. Permatex Black RTV Sealant, NonAcetic. Avoid using any corrosive sealant which has a vinegar-like smell.
UMI-81343 - Anti-Seize should be used on stainless steel hardware (small amount on threads) to
prevent galling and to ensure proper torque.
Technical Description
Active Vertical Antennas - DXE-ARAV3-2P
This deluxe receiving antenna system is designed to operate over a very wide bandwidth from the
AM broadcast band to 30 MHz with superior strong signal performance. The Third Order Intercept
(TOI) is approximately +30 dBm, reducing or eliminating spurious signals. Exceptional feedline
decoupling, absent in some other popular designs, greatly reduces feedline conducted noise and
unwanted signal interference.
Each of the DXE-ARAV3 active receive antennas require a well filtered +10 to +15 Vdc @ 50 mA
nominal current. The DXE-NCC-1 Receive Antenna Variable Phasing Unit will supply power for
the two active receive antennas through the coaxial cable. The DXE-NCC-1 Receive Antenna
Variable Phasing Unit will interrupt the power to the active receive antennas for proper grounding
of their receiving whip elements during the transmit operation of the transceiver, or when the
system is turned off. Alternatively, well filtered station power may be used with a 1 amp in-line
Antenna Feedlines
It is not necessary to use any special length of feedline with receive antennas used in this system.
The front panel controls will compensate for feedline lengths. You should still use a good feedline
and make good connections. DX Engineering recommends DXE-F6 75 Ω CATV style cable with
weather-tight connectors such as DXE-SNS6 Snap-N-Seal, both available from DX Engineering.
Combining two Vertical Antennas to improve Signal-to-Noise Ratio
If your location is limited by interference coming from many directions, you can use the NCC-1 to
enhance signals. It functions as an electronically rotatable directional receive antenna. The
following guidelines apply when enhancing signals:
 The most reliable and consistent
phasing performance occurs
with receive antenna spacing
less than 1/4-wavelength when
receive antennas are in line with
the desired direction, and less
than 1/2 to 1-wavelength apart
when receive antennas are
spaced at right angles to desired
 Best sensitivity occurs when
receive antennas are more than
1/10-wavelength apart when the
receive antennas are in line with
the desired direction, and more
than 1/2-wave apart when
broadside to the desired
 When enhancing desired signals,
it is preferable to locate both A
and B INPUT receive antennas
as far from local noise sources
as possible.
Adjusting the NCC-1 will vary the
phasing of the two receive antennas
and shift the pattern to your desired
The ARAV3 Active Vertical Antennas are a perfect match for the NCC-1.
Nulling Interference and Noise
The NCC-1 is not a noise blanker. The NCC-1 is designed to reduce noise or interference before it
gets to the receiver by nulling the direction from which the noise is arriving. The NCC-1 can be
effective on all types of noise, including interference (QRM) from unwanted signals. The NCC-1
allows the user to continuously adjust both phase and amplitude when combining two antenna
inputs. The signal output to the receiver is the addition or subtraction of signals from two separate
receive antennas. Unwanted directional noise can be removed or unwanted signals can be cancelled.
Desired signals can be peaked or enhanced.
If noise is coming from several sources in different directions, satisfactory results may not be
achieved. Unlike conventional noise blankers, the phasing method of signal enhancement or
rejection does has several advantages.
 Interference much stronger than a desired signal can be completely removed without affecting
the signal if it is arriving from a different direction than the desired signal.
 The NCC-1 can be effective with all types of interference and all modes.
 Signals can be peaked instead of nulled with a flip of a switch.
Note: Failure to follow guidelines outlined in sections below will often result
in reduced nulls or reduced enhancement of distant signals
Understanding Noise
Noise limits our ability to hear a weak signal on the lower bands. Noise is often an accumulation of
many unwanted signals. Noise from antennas is generally a mixture of local ground wave and
ionosphere propagated noise sources, although many locations suffer with dominant local noise
Noise is generated by randomly polarized sources. Noise polarization is filtered depending on the
method of propagation:
 Noise arriving via the ionosphere is randomly polarized. Noise arrives at whatever
polarization the ionosphere favors at the moment. Noise has the same ratio of electric to
magnetic fields as a "good" signal.
 Sources within a few wavelengths of the antenna arrive randomly polarized. The noise does
not have a dominant polarization and it can either be electric or magnetic field dominant.
Local noise can also 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,
security lights, and many other items can be sources of unwanted noise. Plasma televisions
are becoming more popular and are a known generator of unwanted noise interference.
 Ground wave noises arriving from a significant distance are vertically polarized. The path
along the earth "filters out" and removes any horizontally polarized signals. Horizontal
electric field components are "short circuited" by the conductive earth as they propagate and
are eliminated.
With the exception of ground wave-propagated noise, receiving antenna polarization effects are not
predictable. It is possible vertically polarized antennas may be quieter than horizontally polarized
antennas. The opposite is also true.
It may be difficult to remove noise with any device when:
 Noise and desired signals come from the same direction and elevation angle
 Both antennas don’t hear the same noise
 The noise source is moving around, or noise sources are coming from several directions at
the same time
Basic Tools Required
5/16", 7/16", 1/2" wrenches or nut drivers, and a 5/8" wrench
# 2 Phillips Head Screw Driver
Active Vertical Antenna Installation
The best place to install your active antennas is where you have the recommended space. Refer to
pages 20-22 for installation information. The two DXE-ARAV3 receive antennas should be located
a minimum of 1/2-wavelength (at the lowest frequency used) away from any transmit antenna. If
possible, select a location far away from any dwelling where many potential noise sources are
If the receive antennas are located 1/10-wavelength to 1/2-wavelength from a transmitting antenna,
the receive antennas must be powered off at least 5 ms before transmitting on the transmit antenna.
A sequencer such as the DXE-TVSU-1A should be used to ensure the correct transmit-to-receive
With this close spacing, coupling from nearby transmit antennas or metal structures becomes more
pronounced. At higher frequencies, where the active element length becomes a partial wavelength,
coupling increases further. Placing a DXE-ARAV3 on the same mast or tower as a Yagi or other
transmitting antenna is not recommended for this reason.
Pay attention to details. The time you spend making a good installation will pay you back many
times with good results.
The assembly described is for the DXE-ARAV3-1P. Use UMI-81343 - Anti-Seize on stainless
steel hardware threads to prevent galling and to ensure proper torque.
Orient the black Mounting Plate with the two brass element mounting block holes closer to the top
left, as shown in Figure 1. Use the 7/16" x 1-1/2" bolts, flat washers, split washers, and nuts to
mount the brass element block to the mounting plate. Make sure the threaded hole in the element
block for the antenna element is facing upward. Use a flat washer under each bolt head and a flat
and split washer combination under each nut. Do not over-tighten.
Figure 1
Mount the AVA-2 matching unit with the ANT + terminal toward the top up. Use the 5/8" bolts, a
flat washer under each bolt and a flat and split washer under each nut. Refer to Figure 2.
Figure 2
Loosely install the two stainless steel V-Clamps on the black mounting plate as shown in Figure 3.
Figure 3
Upper Clamp
Lower Clamp
NOTE: The following describes the use of the DXE-SSVC-1P and DXE-SSVC-1PG V-Clamps
that are included with the DXE-ARAV3. These are used for mounting the DXE-ARAV3
on a typical ground rod from 1/2" OD to 3/4" OD.
If you plan to mount the DXE-ARAV3 to a larger mounting mast, you will need two
optional DXE-SSVC-150P and one optional DXE-SSVC-150PG V-Clamps which will
accommodate a mounting pipe that is 1" OD to 1-1/2" OD. Refer to Figure 8 for
Refer to Figure 4 and install one of the two wires (both are the same length) from the brass block to
the AVA-2 antenna ANT + connection, use the wing nut and hand tighten only. The wire is held in
place on the brass element block with one 5/16" x 1/2" bolt and one star washer. The closed lug
goes on the brass element and the open lug goes on the AVA-2.
Figure 4
The other wire goes from the ANT - (use the wing nut and hand tighten only) on the AVA-2 to the
ground tab on the stainless steel V-Clamp installed on your ground rod as explained in the next
section. The open closed goes on the ground tab and the open lug goes on the AVA-2 as shown in
Figures 5 and 6.
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Ground Mounting Rod
Drive your four foot copper clad steel ground rod into the ground far enough to provide a sturdy
mount for the antenna system. Ensure the DXE-ARAV3 matching unit will be above any potential
standing water.
Depending on soil conductivity, increasing ground rod depth
beyond a few feet for an active receive antenna rarely improves
RF grounding because skin effect in the soil prevents current
from flowing deep in the soil. Avoid ground rods less than 5/8"
in diameter.
Position the DXE-ARAV3 unit on the ground rod. Adjust the
height so the ground rod top is not higher than the DXEARAV3 black insulated panel. This prevents unwanted
interference with the active element. Tighten the two VClamps to hold the DXE-ARAV3 in place.
Attach the V-Clamp with the tab to the ground rod just below
the bottom of the DXE-ARAV3 as shown in Figure 5. The VClamp can work with ground rods from 1/2" to 3/4" in
Figure 5
Install the ground wire hardware and ground wire on the stainless
steel V-Clamp with the tab. The other end of this wire goes to the
AVA-2 ANT- connection as shown in Figure 6.
Figure 6
Firmly install the 102 inch receiving element whip (one piece or three piece) in the top of the Brass
Element Block.
After final testing and setting of jumpers (if needed, see pages 13 and 14 for jumper information) to
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enhance weather resistance, place a bead of non-corrosive, marine grade silicone along the seams
where the two halves of the case meet. Leave small openings in the two bottom seams to allow any
condensation to drain.
Do not use sealants that have a vinegar-like smell because they contain acetic acid which will
corrode aluminum. Recommended sealant is the UMI-82180 - Approved RTV Sealant.
Providing a Good RF Ground
This active vertical antenna works well with just a single copper ground rod used as the mounting
You can test ground quality by listening to a steady local signal. Attach 15 feet of wire laid in a
straight line away from the coaxial feedline. If you observe a change in signal or noise level, you
need to improve the ground. A second rod spaced a few feet away from, and connected the first one
may correct the problem. If a good ground cannot be established, use a DXE-RFCC-1 Feedline
Current Choke that will further decouple the feedline from the antenna and reduce common mode
current and associated noise from the feedline.
If you want to locate your ground mounted antenna where ground rods cannot be used effectively,
you must use a radial system or metal ground screen. A suitable radial system consists of four to
twelve equally spaced radials, with each radial being at least 15 feet long.
Only if the antenna is located over rock, on a roof, or otherwise installed where conductive soil
conditions do not exist, you must use a ground screen. Welded-wire galvanized screens are okay for
this receive antenna only and are not recommended for transmit antennas. Screen radius must at least
equal the element height and be placed around the antenna as symmetrically as possible.
Do not use elevated radials or grossly asymmetrical radial configurations. The ground system is an
integral part of this receiving system, and if it is asymmetrical or exhibits pronounced resonances,
the antenna system may not function properly.
Rear View
Front View
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The feed line should be run away from the antenna at the exact center to the antenna element. If
possible, bury the feed line for some distance from the antenna. This helps to decouple the feedline
from unwanted noise. A DXE-RFCC-1 Receive Feedline Choke will also ensure feedline
Connect a suitable 75 Ω feedline to the type F connector OUTPUT. Leave a small loop in the
feedline to relieve stress on the AVA-2 connection and securely attach the feedline to the mast
below the mounting plate.
The feedline connectors must remain dry. Do not place any intentional DC shorts or opens on the
feedline between the NCC-1 and the ARAV3s. This includes lightning arrestors, splitters, or any
other accessory not intended for feedlines that carry power or control voltages.
Coaxial Cable Feedline
Flooded 75 Ω CATV type feedline cable (F-6) is strongly recommended for use with the ARAV3
systems. DXE-F6 Flooded 75 Ω CATV type feedline cable has a bonded foil to improve shielding.
Moisture typically seeps in around the shield and can cause increased noise. Flooded style cables
have the distinct advantage of automatically sealing small accidental cuts or lacerations of the
jacket. Flooded cable also prevents shield contamination and has a gummy liquid inside that seals
cuts or nicks, displaces water, and can be direct buried.
The feedline is used to provide power for the AVA-2 matching unit. We
recommend the use of DXE-SNS6-25 Snap-N-Seal type F connectors to
ensure high quality and weather resistant feedline connections. Use the
proper tool to crimp these connectors.
To help decouple the feedline from radiated noise, bury the feedline for some distance from the
antenna when the feedline reaches the ground. A DXE-RFCC-1 DX Engineering Receive Feedline
Choke will also ensure feedline decoupling, which may be installed in-line, preferably at the station
Low Frequency Response - Internal Jumpers
The sensitivity response of the ARAV3 system does not need to be changed for most installations
above 3.5 MHz. However, if you are interested primarily in frequencies below 3.5 MHz, jumpers
may be required to optimize or increase sensitivity or eliminate interference from strong broadcast
stations. Set the jumpers to the lowest operating frequency desired. Refer to Figure 9 for
various jumper settings.
For access to the jumpers, loosen the two #2 Phillips Screws on each
side of the AVA-2 unit and remove the chassis from the bottom.
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The circuit board and jumper headers will be visible as shown in Figure 7. The AVA-2 has five
internal jumpers that modify frequency versus gain response. The L jumpers change the inductance
values and C jumpers change the capacitance values. As shipped, all jumpers are deactivated.
Figure 7 - Low Frequency
Jumper locations & Settings
Installing jumpers in L1MF, L1HF or both, will configure the antenna for a sensitivity peak near the
frequencies listed in Figure 7. The frequency response above the peak frequency does not change
significantly. Below the peak frequency, sensitivity reduction is reasonably fast. Installing a jumper
in any C1 position when jumpers are being used in L1 will move the peak response lower in
frequency, decreasing sensitivity at higher frequencies.
Alternate Mounting
If you plan to mount the DXE-ARAV3 to a
larger mounting mast, two optional DXESSVC-150P and one optional DXE-SSVC150PG V-Clamps are required which will
accommodate mounting pipes from 1" OD to 11/2" OD. Refer to Figure 8 for examples.
Figure 8
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NCC-1 Front Panel Controls and Switches
POWER: Turns power off and on. When powered-off, INPUT B is disconnected and INPUT
A is connected directly to the receiver, removing antenna power.
 Two Attenuator switches reduce gain in ten dB steps. The steps are 0, -10, -20, and –30 dB.
The left switch  sets INPUT “A” attenuation (primary antenna), the right switch  sets
INPUT “B” (secondary antenna) attenuation.
BALANCE: Provides fine adjustment of gain. It is used to balance or equalize signal levels
from INPUT A and B. The BALANCE control provides anywhere from zero to 12 dB
attenuation on either A or B. This control has the same “feel” and operation as the balance
controls on conventional stereo systems. Maximum gain on both channels occurs when the
BALANCE control is positioned in the center of the range, and gain is reduced as the knob is
rotated away from a particular channel. If you rotate the BALANCE control clockwise, the
gain of INPUT A is reduced. Without precise signal or noise level balancing between
antennas, noise nulling or canceling will not be deep.
PHASE: Changes the phase delay relationship between INPUT A and B. The resulting phase
shift will change the position of nulls or directions of peak signal response.
INPUTS: Reverses A (primary) and B (secondary) antenna inputs. This is done after
attenuation adjustment. Changing this switch is the electrical equivalent of physically
swapping antenna element locations.
BAND: Optimizes phase range and selects the filter boards used. "L" is for frequencies below
10 MHz, and selects optional filters FL1 & FL3. "H" is for frequencies above 5 MHz and
selects optional filters FL2 & FL4.
B PHASE: Moves B INPUT phase by exactly 180 degrees.
NORM is 180 Degrees or no phase reverse, REV is 0 Degrees.
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NCC-1 Rear Panel Connections
 INPUT A: Primary Receive Antenna – Phono and F style connector. Phono and F style
connectors are used to prevent accidental connections to transmitting equipment.
 INPUT B: Secondary Receive Antenna – Phono and F style connector. Phono and F style
connectors are used to prevent accidental connections to transmitting equipment.
The NCC-1 can supply T/R Controlled DC power to active antennas through the INPUT A
and B coaxial lines. DC power can come from either the NCC-1 supply or through a separate
rear panel power connector. The NCC-1 has an internal high-speed solid-state switch that will
switch up to 30 Volts DC Positive voltage at 150 mA per input channel for powering receive
 RX OUT: Receive Signal output to receiver – Phono and Type F connector. These types of
connections work well with most transceiver and receiver RX ANT Inputs.
 Main Power: The NCC-1 requires well-filtered +12 to 15 Vdc @ 1A minimum
The NCC-1 should be connected to a well filtered and regulated 12 to 15 Vdc @ 2 A power
source. While station power is highly recommended, a well-regulated, low-noise external wall
transformer can be used. A 2.1 mm plug, center positive power plug is proved with the NCC-1.
External high current sources, such as station power supplies, should be appropriately fused at
the power source. The use of switching power supplies is discouraged due to the presence of
noise in their output.
 ANT PWR: Supplies external voltage to INPUT A and INPUT B feedlines to power the active
antennas. Allowable voltage range is 12-30 Vdc with 300 mA maximum load current for both
INPUTs combined. A 2.1 mm plug, center positive power plug is proved with the NCC-1.
 T/R CTRL: Activated by pulling to ground or by external application of voltage (internal
jumper selectable). When activated INPUT A is bypassed directly to receiver and INPUT B
disconnects. Activation also removes antenna power from both INPUTs – Phono connector
The T/R CTRL line can be configured to disable the NCC-1 and remove power from antennas
attached to the NCC-1 when pulled either low or high. The normal switching threshold voltage is
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+3 Vdc. A valid T/R CTRL input disconnects INPUT B and bypasses INPUT A directly to the RX
OUT. Antenna voltage is also removed from input ports when T/R CTRL is activated. This reduces
chances of damaging the NCC-1 when the receiving antennas are located close to transmitting
antennas and allows the DX Engineering ARAV3 series active antennas to mute, protecting them
from transmitted energy.
NCC-1 Internal Jumpers
The NCC-1 motherboard has jumpers that configure the antenna jack power and transmitter muting
options. With the unit unplugged and no power connected, remove 6 screws on each side of the
metal cover and lift it off.
To configure the jumpers, turn the NCC-1 so the components match the orientation of Figure 9.
The Default jumper positions as shown:
HD1 – Antenna A Power: OFF
HD2 – Antenna B Power: OFF
HD4 – Antenna Power Source: EXTernal (Change this jumper for NCC-1 control)
HD5 – TX Mute Polarity: NOR or Low (Most transceivers) Both Jumpers Installed.
Figure 9 - NCC-1 Jumper Locations
The jumpers are small plugs that fit over and connect two of the pins on the associated header. The
jumper is removed by pulling straight out and installed by aligning with two pins and pushing
straight in to fully seat the jumper.
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HD1 & HD2 - Antenna A and B Power - Activate/Disable
Jumpers HD1 and HD2 (both three pin headers) activate or disable power on the feedline to
INPUTs A and B.
HD1 is in the front corner of the circuit board directly behind the PHASE control and BAND
toggle switch. This header controls power to the INPUT A port. When this
jumper is on the middle and forward pins, power is OFF to INPUT port A as
shown. When this jumper is moved and connects the middle and rearmost pins,
power is applied to INPUT port A.
HD2 is along the edge of the board directly towards the rear from HD1. This header controls
power to INPUT port B. When this jumper is on the middle and forward pins,
power is OFF to INPUT port B as shown. When this jumper is moved and
connects the middle and rearmost pins, power is ON to INPUT port B.
Note: During TX Mute activation, power to the active antennas is disabled
regardless of the Antenna Power jumper settings.
HD4 - Antenna Power Source
The HD4 jumper determines the source of active antenna power, either through the NCC-1
power supply or the ANT PWR jack on the rear panel. HD4 is a three pin header located at the
rear of the main circuit board near the power jacks and the two large power transistors that are
bolted to the main circuit board. When the jumper on HD4 is positioned on the middle and EXT
pins, antenna power comes from the ANT PWR jack. When the jumper on HD4
is positioned towards 12V, as shown, the antenna port power comes from the
NCC-1 main power supply.
HD5 - TX Mute Polarity
HD5 controls the logic state that activates the TX Mute polarity function and is located just
below the rear panel Ext Control connector. HD5 is a four pin header. When
HD5 has two pin jumpers in both positions completely filling the header,
operation is normal. A logic low activates the TX Mute. This means any
voltage above 3 volts positive or an open circuit allows the NCC-1 to function normally. Power
is available for use at antenna ports.
Anything below 1 volt positive (including a "Ground on Transmit") causes the NCC-1 to mute.
Power is removed from the antenna ports and the INPUT A port is connected directly to the
receiver port. Switching time is about 2 ms.
If one shunt on HD5 is installed on the center two header pins, logic is reversed. Positive
voltage over 3 volts applied to the TX Mute will force the NCC-1 into standby and
disable the antenna power feature. Any voltage below one volt, including a
grounded condition, will allow the unit to function normally.
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NCC-1 Installation
Please read the following section carefully.
The best location for this unit is at the operating position with easy access to the controls since you
will be using the S-Meter on your receiver while adjusting the NCC-1.
Make connections to the NCC-1 as follows:
 Connect a fused power source of 12-15 Vdc @ 1A or more to the 2.1 mm
center-positive MAIN PWR jack using the provided 2.1 mm plug. Station
power is recommended.
 Connect the first receiving antenna to the INPUT A F style or Phono connector.
 Connect the second receiving antenna to the INPUT B F style or Phono connector.
 Connect a standard shielded audio style cable between the T/R Control Phono connector and
an external transmit control source.
o By default, the NCC-1 is set to mute when the T/R Control line is pulled LOW.
This is normal station wiring. Many modern transceivers have a rear panel amplifier
control jack typically labeled as "TX", "AMP", "Send”, “Control" or "TX GND" that
pulls low when the transceiver is keyed. (Check the user manual for your radio)
Note: Internal jumpers (HD5) can be changed to allow the NCC-1 to use an
inverted + 5 to 50 Vdc amplifier control line. This is an unusual configuration.
o T/R Control line on the NCC-1 can be paralleled on the same control line used for
the amplifier provided the amplifier does not load the line when not transmitting. If
the amplifier does load the line, you will have to add a blocking diode.
o The DX Engineering TVSU-1A programmable sequencer can also be used to
provide the proper transmit/receive switching for an amplifier, transceiver, and the
NCC-1. Refer to Appendix A for the high power installation connection diagram.
 Connect the RX OUT jack to a receiver or the transceiver receive-only antenna port.
Do not connect the RX OUT connector of the NCC-1 to a transceiver RF output!
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 If desired, connect a fused external power source to the ANT PWR 2.1 mm center-positive
jack if you are not using the NCC-1 supply to power antennas (HD4 Jumper
Selectable). The allowable voltage range is 10-30 Vdc with 300 mA maximum
load current for both INPUTs combined. The DX Engineering DXE-ARAV3
Active Receive antennas typically require a nominal 12 Vdc @ 50 mA each.
Radio Interface Diagrams
The following typical interface diagrams are shown for the DXE-AAPS-1P Active Receive
Vertical Antenna Phasing System.
The DXE-ARAV3 receive antennas must be at least 1/10-wavelength away from any transmit
antenna and preferably more than 1/2-wavelength away. The DXE-NCC-1 switches the power off
during transmit. This configuration allows the operator to selectively null out interference, and
thereby enhance the desired received signal direction ability.
Every radio manufacturer and every amateur radio operator's location is different. The following are
only suggestions, and you should consult your radio manufacturer's manual for details and further
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Typical HF Set Up
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Typical HF System Set Up with an
HF Amplifier and using
- 22 -
Typical SWL or Broadcast AM DX System Set Up
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Operating the Receive Phasing System
Now that everything is correctly installed and all the cables are properly connected, let's run through
a typical operation:
1. Connect the NCC-1 to your station and a suitable power source.
2. Set the front panel controls as follows:
Both A and B attenuator switches to the 0 dB position, unless one antenna requires more
preset attenuation
BALANCE control to the center position, the knob indicator line should be centered
PHASE control rotated to zero position
INPUTS switch to NORM
B PHASE NORM-REV switch set to NORM
BAND switch to L for operation below 5-10 MHz or H for operation above 5-10 MHz. In
the range of 5-10 MHz, either setting may work
To get the best rejection of unwanted signals or noise, rotate the PHASE control until the noise or
interference is at the lowest level. If a null cannot be found, change the PHASE NORM/REV switch
to the REV position. The null might be shallow until levels are balanced.
Adjust the BALANCE control to further reduce noise or interference. It may be necessary to go
back and forth between PHASE and BALANCE controls a few times. If the BALANCE control is
not within 90 degrees of the center position, apply attenuation to the opposite side the BALANCE
pointer is on. This should center the BALANCE control indicator line.
Often a little experimentation is required to get the best performance using and understanding of
antennas and phase relationships. You can also reverse directions by changing INPUT A and
INPUT B using the INPUT switch. This switch is most useful when elements are in line with
desired or undesired directions, but there are cases where it can extend phase range and aid in
achieving a better null.
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The PHASE NORM-REV switch will turn a NULL point into a PEAK point. Adjust for a null as
above, and then reverse the PHASE switch.
Unwanted signals or noise can only be nulled if present on both A and B
Desired signals can only be peaked if the have about the same S/N ratio on both
antennas and when spacing is correct.
Different fading rates and times between dissimilar or wide spaced antenna can
make control adjustment tedious.
The most stable and reliable nulls occur when antennas are moderately close
together (between 1/10 and 1/4-wavelength apart), oriented in the same
direction, and sharing the same polarization.
The PHASE control changes the phase relationship between A INPUT and B INPUT, effectively
changing the direction of a peak or null. When the phase control is fully counterclockwise, INPUT
A has minimum phase shift and INPUT B has maximum phase shift. As the PHASE control is
rotated clockwise phase shift in INPUT A increases while phase shift in INPUT B decreases.
The PHASE NORM-REV switch inserts zero (REV) or 180-degree (NORM) phase inversion in
INPUT B. This switch has the effect of changing a peak to a null, or a null to a peak. If a signal is
nulled with the NORM-REV switch in one position, changing the position will result in a peak.
If you have a general coverage receiver, select a strong steady signal between 1.5 and 30 MHz. The
ideal signal would be ground wave, although the time and frequency standards on 5, 7.335, and 10
MHz are good alternatives. Try to use a signal that does not have excessive or rapid fading.
Note: Any signal being nulled or peaked must be adjusted to the same level as seen at the
receiver from both channels or the NCC-1 Phase Control will not work as expected.
Manual Updates
Every effort is made to supply the latest manual revision with each product. Occasionally a manual
will be updated between the time your DX Engineering product is shipped and when you receive it.
Please check the DX Engineering web site ( for the latest revision manual.
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Optional Items
DXE-F6 - 75 Ω F-6 Style, Direct Bury Coaxial Cable: Full Spool or Cu stom Cable Assemblies
DX Engineering recommends using a high quality 75 Ω “flooded” F6 type coaxial cable. Flooded style cables
have the distinct advantage of automatically sealing small accidental cuts or lacerations of the jacket. Flooding
also prevents shield contamination and can be direct-buried. This low-loss cable features dual shields and an
85% Velocity Factor.
Custom cable assemblies are available, Call DX Engineering for details.
DXE-SNS6 Snap-N-Seal connectors are recommended for use with this coaxial cable to ensure a high quality
and weather resistant feedline connection. The proper tool DXE-SNS-CT1 must be used to install these connectors.
DXE-CPT-659 - Coax Cable Stripper for CATV F-6, RG-6 and RG-59 coaxial cable
Coax Cable Stripper for CATV F-6, RG-6 and RG-59 coaxial cable.
Includes 1 Replacement Blade - DXE-CPT-659
Prepares CATV F-6, RG-6 and RG-59 coaxial cable for the installation of "F" type connectors - One-step cutting
 Precision cut
 No nicks or scratches to conductor
DXE-SNS6-25 - Watertight Coaxial Connector, Snap-N-Seal for CATV F-6 Cable, 25 pieces
Snap-N-Seal is an environmentally sealed CATV F coaxial connector system for harsh environments. The connectors
have a unique, 360 degree radial compression system that offers the signal leakage protection required for high
performance receive systems.
 Quad sealed system prevents moisture from migrating into the connection
 360 degree radial compression provides superior RF integrity (-95dB typical, 60% bonded foil cable)
 Easy cable preparation
 Connector to cable retention of 40 lbs minimum
 Superb impedance match to 1 GHz
 Manufactured of high quality 360 brass, cadmium plated with yellow chromate coating for maximum corrosion resistance
 UV-resistant plastic and O-rings provide a reliable environmentally sealed connector
An installation tool, such as the DXE-SNS-CT1 is required to install the connectors. Normal crimping tools or pliers will not work.
DXE-SNS-CT1 - Compression Tool for Snap-N-Seal 75 Ω Coaxial Connectors
Ratchet compression tool for installing DXE-SNS6 Snap-N-Seal coaxial connectors. Ordinary pliers will not install
these connectors properly.
DXE-TVSU-1A - Time Variable Sequencer Unit
The DX Engineering TVSU-1A Time Variable Sequencer Unit is a microprocessor-based transmit / receive control-signal delay
unit. It provides 0-30 ms of delay, programmable in 2 ms increments, to as many as five outputs tied to the CW keying or push-totalk (PTT) lines.
By controlling the receive-to-transmit (and back) timing of linear amplifiers, preamplifiers, and other sensitive equipment, damage
caused by improper switching can be eliminated.
This sequencer improves CW performance by eliminating annoying leading edge chopping or truncating of Morse characters. This is
especially important in contests or pileups where sending accuracy is critical.
The TVSU can also control external devices such as preamps, active antennas, or external relays that need
to have power removed during transmit. Separate power-in and power-out jacks on the front
panel are used to control external power in this type of application. Two 2.1mm power plugs and two
3.5mm stereo plugs are provided.
 Control timing of PTT turn-on, hang delay of PTT, amplifier hang delay, external antenna relay hang delay and turn-on delay of
auxiliary output
 Dip switch settable delays of 0-30 milliseconds in 2 millisecond steps
 Side tone generator that follows input of keyer or hand key not transmitter
 Side tone pitch can be programmed from 300 to 1000 Hz in 50 Hz steps, front panel headphone jack with adjustable volume
 Supports CW full break in
 Can control external power to our Active Receive Antennas and permit operation in closer proximity to transmit antennas
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DXE-RPA-1 - Receiver Preamplifier, 0.3-35 MHz
This is the best HF low noise amplifier available. The RPA-1 is optimized for 0.3-35 MHz operating range. The push-pull amplifier
design and robust components enable it to withstand high signal levels and operate when you need it most. The dynamic range of the
RPA-1 is better than most receivers.
The RPA-1 is suitable for indoor or outdoor installation, with the option of being powered through the
coaxial feed. The metal housing provides shielding and improved lifespan. The unit uses RCA type
phono jack and CATV F connector for the input and output connections, and has a relay that
automatically bypasses the amplifier when dc power is removed.
 Push-pull operation eliminates harmonic distortion
 High quiescent current increases ability to handle strong signals without distortion or overload
 Meticulous craftsmanship and durable components provide superior dynamic range
 RCA type phono jack and type F connector ease installation
 Simplified switching - automatic bypass eliminates gain when dc power is off
 10-18 Vdc power using power connector or through the coax
 10-18 Vdc through coax enables remote operation at antenna
UMI-81343/81464 Never-Seez and DXE-NSBT8/NMBT8 Anti-Seize
An Anti-seize compound MUST be used on any Stainless Steel nuts, bolts, clamps or other hardware to prevent galling
and thread seizure. Any of these products can be used for this purpose.
Anti-Seize, 1 oz. Squeeze Tube
Anti-Seize, 8.5 oz. Aerosol Can
Never-Seez, 8 oz. Brush Top
Never-Seez, 8 oz. Brush Top, Marine Grade
* These products are classified hazardous and are limited to domestic UPS Ground shipping only
DXE-SSVC-150P Stainless Steel V-Clamp
This stainless steel V-Saddle Clamp is made in four sizes to fit steel tubing or pipe ranging from 1/2" to 3''
OD for use in antenna construction. The DXE-SSVC-150P uses a V-Bolt and will attach to a mast ranging in
size from 1" OD to 1-1/2" OD. The V-Saddles is made from high-strength 304 (18-8) stainless steel. The
special stainless steel saddles have serrated teeth and will clamp to the pipe securely by biting into the
surface. For this reason, it is not recommended for softer aluminum tubing or pipe. Included are Stainless
Steel Hex Nuts, Split Washers and Flat Washers.
DXE-SSVC-150PG Stainless Steel V-Clamp with Tab
This stainless steel V-Saddle Clamp is made in two sizes to fit steel tubing or pipe ranging from 1/2" to 1-1/2'' OD
for use in antenna construction. The DXE-SSVC-150P uses a V-Bolt and will attach to a mast ranging in size
from 1" OD to 1-1/2" OD. The V-Saddle is made from high-strength 304 (18-8) stainless steel. The special
stainless steel saddles have serrated teeth and will clamp to the pipe securely by biting into the surface. For this
reason, it is not recommended for softer aluminum tubing or pipe. Continuing on the popular DXE-SSVC series
of clamps, the "G" models have a special tab for connecting an optional ground braid or wire. Included are
Stainless Steel Hex Nuts, Split Washers, Star Washers, Hex bolt for the tab and Flat Washers.
UMI-82180 - DX Engineering Approved RTV Sealant
Permatex Black RTV Sealant, Non-Acetic. We have all used RTV to seal water out of things, right? Have you
ever sealed a piece of electronic gear with it -- then opened it some time later to find that it had still managed
to become corroded inside? Guess what? It's not the rain that corroded it - It's the RTV! Normal RTV gives
off acetic acid when it cures. That's the vinegar smell. The acetic acid causes the corrosion. Applies just like
"normal" RTV, dries in one hour and cures in 24 hours at 70 degrees F. And it doesn't smell like vinegar!
 3.3 oz. Tube
 Black
*This part is classified hazardous and is limited to domestic UPS Ground shipping only
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DXE-RFCC-1 - Receive Feedline Current Choke, 50 Ω to 75 Ω 300 kHz to 30 MHz
If you wish to reduce feedline radiation and improve reception, a Feedline Current Choke is recommended if your SWR is already
low. Adding a DX Engineering Feedline Current Choke at the point where the feedline exits the
area of the antenna will substantially reduce unwanted feedline radiation or reception without the
need for improved station grounding.
The advantages of using an FCC:
 Prevents unwanted RFI by eliminating feedline current and radiation
 All power goes to the antenna, improving efficiency
 Reduces noise or unwanted signals picked-up by the feedline
 Overcome a less than optimal ground system
The DX Engineering RFCC-1 receive feedline common-mode choke is the most effective solution to common-mode noise or
unwanted signal ingress available to date. The DX Engineering RFCC provides thousands of ohms isolation between the input and
output coaxial shield connections while passing desired signals, including dc or low frequency ac control signals. The RFCC has
extremely high isolation impedance which effectively blocks common-mode noise or unwanted signals, even in the presence of very
poor grounding. Low noise receive antennas are traditionally located away from electrical wiring and other noise sources.
Unfortunately, noise and other unwanted signals have a direct path to your low-noise antenna through the feedline shield connections
between the station equipment and antenna. Unwanted signals can also energize the outside of the feedline shield, and this undesired
signal energy can be conducted directly to the receiving antenna. This can reduce antenna directivity. Unless you have a perfect zeroresistance RF ground at the antenna, some of the common-mode noise or unwanted signals from the feedline shield will make it into
the antenna. The RFCC is effective from 300 kHz to 30 MHz. It comes with standard CATV type “F” female connectors, although it
can be used in any 50 to 75 Ω receiving system. The RFCC is a passive device, therefore requires no power to operate.
Technical Support
If you have questions about this product, or if you experience difficulties during the installation,
contact DX Engineering at (330) 572-3200. You can also e-mail us at:
For best service, please take a few minutes to review this manual before you call.
All products manufactured by DX Engineering are warranted to be free from defects in material and workmanship for a period of one
(1) year from date of shipment. DX Engineering’s sole obligation under these warranties shall be to issue credit, repair or replace any
item or part thereof which is proved to be other than as warranted; no allowance shall be made for any labor charges of Buyer for
replacement of parts, adjustment or repairs, or any other work, unless such charges are authorized in advance by DX Engineering. If
DX Engineering’s products are claimed to be defective in material or workmanship, DX Engineering shall, upon prompt notice
thereof, issue shipping instructions for return to DX Engineering (transportation-charges prepaid by Buyer). Every such claim for
breach of these warranties shall be deemed to be waived by Buyer unless made in writing. The above warranties shall not extend to
any products or parts thereof which have been subjected to any misuse or neglect, damaged by accident, rendered defective by reason
of improper installation, damaged from severe weather including floods, or abnormal environmental conditions such as prolonged
exposure to corrosives or power surges, or by the performance of repairs or alterations outside of our plant, and shall not apply to any
goods or parts thereof furnished by Buyer or acquired from others at Buyer’s specifications. In addition, DX Engineering’s warranties
do not extend to other equipment and parts manufactured by others except to the extent of the original manufacturer’s warranty to
DX Engineering. The obligations under the foregoing warranties are limited to the precise terms thereof. These warranties provide
exclusive remedies, expressly in lieu of all other remedies including claims for special or consequential damages. SELLER
©DX Engineering 2012
DX Engineering®, DXE®, DX Engineering, Inc.®, Hot Rodz™, Maxi-Core™, THUNDERBOLT™, Antenna Designer™, Yagi
Mechanical™, and Gorilla Grip® Stainless Steel Boom Clamps, are trademarks of PDS Electronics, Inc. No license to use or
reproduce any of these trademarks or other trademarks is given or implied. All other brands and product names are the trademarks of
their respective owners.
Specifications subject to revision without notice.
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