COMTEK COM-ACB-160 Instructions manual

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Four-Square Arrays

ACB-4-A Series: COM-ACB-160-A, COM-ACB-80-A, COM-ACB-40-A,

COM-ACB-30-A, COM-ACB-20-A

COM-ACB-A-INS-Revision 5

 COMTEK SYSTEMS 2022

1200 Southeast Ave. - Tallmadge, OH 44278 USA

Technical Support: [phone]  Technical Support International: [phone]

E-mail: [e-mail]

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Congratulations! You are now the proud owner of a COMTEK ACB-4 Hybrid Four-Square
Phasing System for use in a mono-band phased array. These systems offer reliable, enhanced
operations for many years and have been proven to be a powerful weapon in the arsenal of the
contester and DXer. Connected with quarter-wave phasing feedlines to four ground-mounted
verticals, these hybrid systems allow the user to steer the pattern of the array to one of four
directions. COMTEK ACB-4 Hybrid phasing systems are affordable and are simple to install and
use. They are designed and built with specific, high quality components for a single band, available
for the 160, 80, 40, 30 and 20 meter bands.

These phased arrays consist of four
elements fed with a particular phase
and power ratio to obtain a
directional pattern.

Each element of the array can be fed
with different amounts of power and
phase relationships to obtain this
directional pattern, providing good
gain and front-to-back and front-to­side ratios.

COMTEK phased array relay units
used with 4 vertical elements. Our
4-square vertical array offers very
good directivity.

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4-Square Array

More gain and better front-to-back and front-to-side ratios are possible using a 4-element array.
Four separate verticals are arranged in a square -- a 4-Square Array -- one vertical at each corner of
a square. The square is one quarter wavelength on a side. Its pattern is directional across each
diagonal of that square. In other words, it beams across opposite corners of the square. The
COMTEK ACB-4 provides the correct power and phase division between these 4 vertical elements
and a switch matrix which allows rotation of the relative powers and phases allowing 4 separate
directions at the flick of a switch from your operating position.

The exterior Relay Unit of the ACB-4 contains all the switching and phase and power controls
using hybrid toroids. No coax cables are hanging at the switchbox. You switch 90 degrees at each of
the 4 switch settings-providing a full 360 degrees of coverage.

ACB-4 HYBRID PHASING COUPLER SPECIFICATIONS
The ACB-4 is band specific. You cannot use an 80M ACB-4 for any band other than 80M. In

order to meet your needs, we offer the ACB-4 for all amateur bands from 10M to 160M. If you have
any special needs, or the model you are interested in is not listed, please contact us.

CONTROL CONSOLE

 Operation on 12 to 13.6 Vdc, well filtered, 2 amp minimum
 Heavy duty diodes with RF bypass caps
 Current limiting resistor protection for each LED
 Chassis and cover custom manufactured to our specifications.
 Label made for recording your favored directions
 Compact size: 2-3/8" H x 6-1/4” W x 5-1/2" D

90 DEGREE HYBRID-RELAY UNIT

 High amperage gold plated contact relays with dust covers
 PTFE silver stranded wire over fiberglass tape wound toroids
 Balanced temperature, frequency and voltage stable capacitors
 Laboratory analyzed for improved performance
 Double-sided printed circuit board
 Two kW conservative rating for Amateur Radio Service
 MOV's for lightning surge protection with RF bypass capacitors
 Size: 4" H x 6" W x 8-1/2" D
 Brushed aluminum finish Z-Chassis and Cover with riveted seams

Manual Updates and Information

Every effort is made to supply the latest manual revision with each product. Occasionally a manual
will be updated between the time your COMTEK product is shipped and when you receive it.
Please check the DX Engineering web site (www.dxengineering.com) for the latest revision manual.

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INSTRUCTIONS

The ACB-4 consists of a control console and the hybrid relay unit. They are connected via a three
conductor control cable. Our tests have used 1,500 feet of 24 AWG wire. For those with long runs,
18 AWG control cable should be adequate.

The heart of a four square system is the COMTEK ACB-4. As with any antenna system, the vertical
radiators themselves are vitally important. The following types of vertical antennas have been
successfully used worldwide:

1) Conventional ground mounted 1/4-wave verticals - available from DX Engineering

2) 1/4-wave elevated ground plane verticals

The ACB-4 Relay Unit contains two hybrids and the necessary switching matrix to provide correct
phasing to each of the four elements 0 & -90 and -180 & -90 degrees.

RF power division is also accomplished with the ACB-4 so all ports get an equal power split. Due
to mutual coupling within the array, each element will present different impedance; i.e. different
from the impedance of a single element.

If all elements are not the same (or very similar), your system may not be symmetrical and an
imbalance may result. Be careful to make each vertical radiator as identical as possible.

The physical layout of the array is also important. Elements should be symmetrical in placement,
within one foot of each measured location.

Use of a good radial system is paramount with any high performance earth mounted vertical
antenna system. With a vertical antenna system, the radials are the second half of the antenna. They
also act like a screen, shielding radiation from the lossy earth below the radials. Radials greatly
influence radiation efficiency of a ground-mounted vertical antenna system.

Use of the DX Engineering DXE-RADP-3 Stainless Steel Radial Plate is an ideal solution to having
a symmetric and well designed radial system. Mount a DXE-RADP-3 to the 2" OD (maximum OD
is 2”) mounting pipe at each of the vertical antennas using a DXE-SSVC-2P Stainless Steel V-
Clamp.

For best performance, refer to Table 1 for the radial system required for the band of operation. In
most cases peak performance actually comes with as few as 20 or 30 radials. At that point the array
stops rapidly increasing in field strength as radials are added. 32 radials is generally a very
comfortable number when cost vs. efficiency is considered. Payback is generally only a fraction of a
dB when more than 40 radials are compared to 20-30 radials. In any event, it is never necessary to
use more than 50 or 60 radials. Dozens of studies have proven there is very little change in
efficiency beyond 50 radials, regardless of soil type. DX Engineering DXE-RADW Radial Wire, a
stranded copper 14 gauge relaxed PVC insulated copper wire is suggested for the best results.

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Band of

Operation

Minimum

Number of

Radial Wires

Maximum Length

of each Radial

Wire

Minimum Length

of each Radial

Wire

160 Meters

32

130 Feet

65 Feet

80 Meters

32

65 Feet

32.5 Feet

75 Meters

32

65 Feet

32.5 Feet

40 Meters

32

33 Feet

16.25 Feet

Table 1 - Radial Wire Lengths

Not all of the radial wires will be 1/4-wavelength long. Since the four vertical antennas are spaced
1/4-wavelength apart, the radial fields would cross each other. At the point where the radial fields
do cross, they can be cut and bonded together with intersecting radials from the adjacent radial
fields, as shown in Fig 1.

The wire radials should placed as symmetrically as possible straight from the feedpoint around each
of the vertical antennas and spaced evenly, regardless of how many radials are used. Do not run
radials parallel or in bundles, and avoid bending radials to extend the length. This nullifies or
reduces radial effectiveness.

If you have limited space, put in as many straight radials as you can. Radials must be connected to
the antenna feedline shield. The DX Engineering DXE-RADP-3 Stainless Steel Radial Plate is an
ideal optional item for making radial connections. The corrosion resistant stainless steel plate
provides an excellent reliable system for attaching radial wires to your vertical antenna system
feedpoint.

Radial wires can be laid in shortly mowed grass using DX Engineering DXE-STPL-100K/BD Steel
or Biodegradable Radial Wire Anchor Staples to hold them down. Use enough staples to ensure the

wires will not be snagged by mowers, people, or animals. Grass will
quickly overgrow the radials and it will be virtually impossible to see
them. An article describing this process is available on the DX
Engineering website in the Tech Support section. Radials can also be
buried just under the surface by using a power edger or single blade
plow to make a slit in the soil.

Figure 1 - Typical
Radial Field

When the radial field is set up for the four vertical antennas,
copper strap or heavy solid buss wire should be used to
provide cross bonding of the radials that meet each
other.

The four-square array is directional across its diagonals. So when laying out your array, make
certain you know the difference between true north and magnetic north (using a compass) for your
QTH and place the elements accordingly to true north. Remember that you will be beaming across

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the diagonals. Using the formula 246/f (MHz) should determine spacing along the sides of the
square for best pattern results. This means the diagonal distance will be 1.41 X 246/f (MHz).

Other spacing close to this value may work, but the characteristics of the main lobe will change
gain, directivity and front-to-back. Time spent in laying out a symmetrical installation will pay solid
dividends. The system is forgiving, but the best front-to-back is obtained when symmetry is
maintained and with each element resonant on the same frequency and with each antenna base at
the same elevation. Use 234/f (MHz) for the vertical and radial length.

The ACB-4 uses a Quadrature hybrid in toroid form to obtain 90 degree phase shifts. This device is
a four port hybrid and one port must be terminated with a 50-ohm dummy load. This termination
is vital! When the array is working well, with all elements resonant, there is typically less than 5%
power dissipated by this load. However, when an element is open, shorted, or not resonant at the
same frequency as other elements, this load will dissipate power. A test for your system is to
measure the power between the ACB-4 and the dummy load. The lower the power reading, the
better your system is performing. Coax between the load port and the dummy load may be any
convenient length of 50-ohm cable. A length of 50-ohm cable to the operating position connected to
a wattmeter and the dummy load will allow simultaneous operation and monitoring the power level
to the load.

Front-to-back is affected by the balance between elements. If you want good front-to-back, pay
attention to the details of making each element the same and ensure the array is symmetrical. Using
the Four-Square vertical array, you will notice the best front-to-back on low angle signals. Signals
arriving at high angles see all elements in the array at the same time (no phase delay is possible) and
therefore may display small front-to-back ratios. Don’t worry if this happens; just wait for low
angle signals to test your system.

Tuning the vertical elements (use this procedure with any type element)

1) Install one vertical element and install the ground radial system. (234/f (MHz))

2) Connect a short 50-ohm cable and antenna analyzer to the vertical element feedpoint.

3) Tune the quarter-wave element to resonance (defined as the least amount of power in the
load) approximately 4% lower than the desired array center frequency. Due to mutual
coupling, the array will shift up approximately 100 kHz when all verticals are connected and
fed from the ACB-4 Hybrid Relay Unit. Our experience has shown reduced mutual coupling
with less than 1/4-wave sized elements, 1/4-wave wire elements

.
Examples: For an 80 meter system tune each element at 3.550 kHz for a center frequency of

3.650 kHz mid-range coverage. For a 40 meter system tune each element at 7.000 kHz for a
center frequency of 7.100 kHz.

4) Disconnect 50-ohm feed line. Make sure the remaining elements identical to the first
element.

5) Drive a 1-1/4" to 1-1/2" outside diameter pipe into the ground at the array center. Install the
hybrid relay unit with supplied U-Bolt.

6) Connect all the vertical elements with 1/4-wavelength 75-ohm RG-11U foam coax to their
respective ports on the ACB-4 relay unit.

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Use cable tags to identify coaxial cable from each vertical element, and place several inches

below connectors at the ACB-4 relay unit. This will aid in properly installing the cables if
disconnected for any reason.

7) Connect a 50-ohm dummy load to load port via 50-ohm coax.

8) Connect the 50-ohm feed line from ACB-4 relay unit to the transmitter.

9) Connect a 3 conductor cable to terminals inside the control console and the ACB-4 relay
unit.

Use the included Ty-Wrap on the cable as shown to avoid accidentally pulling the

cable out of the control box.

A 2.1 mm power cord is supplied with unit. The wire with the white stripes is the +12 Vdc line.

Outer Connection is GROUND Center Pin is +12 VDC.

Power used must be +12 Vdc, well filtered at 2 amps (fused) minimum.

All Models Ship with the DC powered ACB-4 Control Console

1

Northwest

2

Northeast

3

Southeast

4

Southwest

The output of the Control Console is as follows:

POSITION

TERM. 1

TERM. 2

1

Northwest

l2-14 Vdc

12-14 Vdc

2 (Default)

Northeast

None

None

3

Southeast

12-l4 Vdc

None

4

Southwest

None

12-14 Vdc

Voltage level depends on DC voltage used to power the Control Console.

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For those customers in high snowfall totals or pesky wildlife, an 8 gallon
plastic trash can, can be obtained and placed over the ACB-4 relay unit to
prevent snow from building up to the connector ports.

We recommend you install the coax cables so position 2 on the inside
control is your most favored direction. Position 2 is the default position
and does not supply any voltage to the relays. This means when the
control box is off, you are beaming in the direction of position 2.

NOTES

1) As an example, most types of RG-11 foam coaxial cable have a velocity factor of 78%.
The formula for a specific frequency is: 246/f (MHz) X .84 = length in feet. This works out

to 50 feet 6 inches at 3.800 after measuring for an electrical 1/4 wave. Foam RG-11 coax
must be used to reach the antennas. DX Engineering DXE-11U Coaxial Cable is ideal.

CATV hardline velocity factors are typically .81% or higher. Polyethylene coax with a

velocity factor of .66 will not reach the antennas.

Your VSWR should be less than 2:1 from 3.5-3.8 MHz with full size aluminum vertical

elements, with 5% or less of transmitted power "dumped" into the 50-ohm load.

2) See the ARRL Antenna Handbook chapter on "Antenna Orientation" for details on how to

determine true north for your QTH. Using only a compass with no correction can cause the
array to be off by as much as 30 degrees.

3) Do not HOT SWITCH, i.e. transmit while switching. THIS CAN DAMAGE THE

RELAY. HOT SWITCHING is NOT covered under warranty.

WARNING ! DO NOT INSTALL ANTENNAS NEAR POWER LINES!

METAL OBJECTS TOUCHING HIGH VOLTAGE LINES CAN CAUSE SERIOUS OR

FATAL INJURIES!

QUARTER-WAVE (1/4w) FEEDLINE SET-UP FOR FAVORED DIRECTION USING
DEFAULT POSITION

RELAY UNIT PORTS: #1 2 3 4
Directions: NW NE SE SW

(This is normally used by North American stations.)

The following setup directions are for other parts of the world. Remember Position 2 is the favorite
direction:
RELAY UNIT PORTS: #1 2 3 4

SW NW NE SE
NE SE SW NW
SE SW NW NE

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Position 2 is the default position, i.e., the array favors this direction when no power is applied to the
relays.
Position 1 applies voltage to all three relays, which are closed.
Position 2 no voltage and all relays open
Position 3 applies voltage and closes K-1 & K-2.
Position 4 applies voltage and closes K-3.
Facing the 3 wire terminal strip, K-1; K-2 and K-3.

IF any two antenna connections are not in the proper ports, the array will not function correctly and
a higher SWR will result.

COMTEK SYSTEMS ACB-4 4·SQUARE SETUP DIMENSIONS

160 = 1.835
Spacing = 134 feet
Diagonal = 189 feet
Foam Coax = 104 feet 6 1/2 inches (RG-11 @ 78% to 81% VF minimum is required.)
ACB-4 to any vertical = 94 feet 6 inches (78% minimum figures shown)

80 = 3.500 (Favors CW Operation) 30 = 10.125
Spacing = 70 feet 3 inches Spacing = 24 feet 3 inches
Diagonal = 99 feet Diagonal = 34 feet 3 inches
Foam Coax = 54 feet 9-1/2 inches Foam Coax = 18 feet 11-1/4 inches
ACB-4 to any vertical = 49 feet 6 inches ACB-4 to any vertical = 17 feet 1-3/4 inch

80 = 3.650 (Favors CW & Phone Operation) 20 = 14.200
Spacing = 67 feet 4 inches Spacing = 17 feet 3 inches
Diagonal = 95 feet Diagonal = 24 feet 4-1/2 inches
Foam Coax = 52 feet 6-1/2 inches Foam Coax = 13 feet 6 inches
ACB-4 to any vertical = 47 feet 6 inches ACB-4 to any vertical = 12 feet 2-1/4 inches

80 = 3.775 (Favors DX Phone Window)
Spacing = 65 feet 1-3/4 inches
Diagonal = 91 feet 10 inches
Foam Coax = 50 feet 9-1/2 inches
ACB-4 to any vertical = 45 feet 11 inches

40 = 7.100
Spacing = 34 feet 7 inches
Diagonal = 48 feet 10 inches
Foam Coax = 27 feet
ACB-4 to any vertical = 24 feet 5 inches

Band of

Operation

Minimum

Number of

Radial Wires

Maximum Length

of each Radial

Wire

Minimum Length

of each Radial

Wire

160 Meters

32

130 Feet

65 Feet

80 Meters

32

65 Feet

32.5 Feet

75 Meters

32

65 Feet

32.5 Feet

40 Meters

32

33 Feet

16.25 Feet

Radial Wire Lengths

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Not all of the radial wires will be 1/4-wavelength long. Since the four vertical antennas are spaced
1/4-wavelength apart, the radial fields would cross each other. At the point where the radial fields
do cross, they can be cut and bonded together with intersecting radials from the adjacent radial
fields, as shown in Fig 1.

The wire radials should be placed as symmetrically as possible straight from the feedpoint around
each of the vertical antennas and spaced evenly, regardless of how many radials are used. Do not
run radials parallel or in bundles, and avoid bending radials to extend the length. This nullifies or
reduces radial effectiveness.

Comtek 4-Square typical performance:

Directivity is diagonal-through each of the two sets of verticals.

Gain: 4 dB over single vertical
Beam width: +/- 46 degrees
Front-to-Back > 20 dB over 120 degrees
Front-to-Side > 15 dB
Rotation time: < 1 second
Directions: 4 - Across diagonals
Required Footprint: Including radials
160M (1.835) 400 X 400 feet
75/80M (3.650) 200 X 200 feet
40M (7.100) 105 X 105 feet
20M (14.200) 51 X 51 feet

Array Layout Examples:

X-1 X-2

X-4 X-3

Band

Freq.
MHz

X-1 to X-2. X-2 to X-3.

X-3 to X-4. X-4 to X-1

Diagonal
X2 to X4

Diagonal
X1 to X3

160

1.835

134'

189'

189'

80

3.500

70' 3"

99'

99'

80

3.650

67' 4"

95'

95'

80

3.775

65' 2"

92'

92'

40

7.100

34' 7"

48' 10"

48' 10"

30

10.125

24' 3"

34' 3"

34' 3"

20

14.200

17' 3"

24' 5"

24' 5"

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TROUBLESHOOTING AND MISCELLANEOUS

The Cable ID Tags should be numbered 1, 2, 3, and 4, and placed on the 1/4-wave coax lines from
each antenna at the hybrid coupler relay unit port end. This will prevent an out of sequence
connection, which will result in poor performance. A waterproof marker used to number the tags is
recommended.

TYPICAL NORTH AMERICAN
EXAMPLE

Position 1 = Northwest
Position 2 = Northeast
Position 3 = Southeast
Position 4 = Southwest

These are the favorite directions for
North America users. Remember,
Position 2 is the default position
when power is off, the array will
beam towards Europe (Northeast).

Insure DC power is OFF prior to
connecting the 3 conductor control
cable to the hybrid terminal strip.

Initial test should be with transmitter
in low power position.

Never switch relays while transmitting. “HOT SWITCHING” at HIGH power levels will
damage the relays and possibly the transmitting equipment.

Hot switching at 50 to 75 watt power levels is acceptable and will aid in the cleaning of the
relay contacts by rotating the control switch from Position 1 to Position 2 then back to 1.
Repeat this sequence several times.

Comtek stocks two sizes of RF beads which slip over RG-11 foam or RG-59 foam coax. These
beads choke RF from flowing on the shield, resulting in cleaner patterns.

SIMPLIFIED POWER MONITORING PROCEDURE

After the array is tuned, you may run a length of RG-58 or RG-8X from the Dummy Load Port to a
wattmeter in the shack. Connect a short jumper from the wattmeter antenna out to the dummy load.
This allows complete monitoring of the dissipated power at all times while on the air.

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TOWER LEG INSTALLATIONS

Remove the sheet metal screw above the U-Bolt prior to installing the hybrid on a tower leg, as in a
dipole array. This permits the cover to be removed later without removing the U-Bolt.

DEEP SNOW PROTECTION

For customers residing in areas with high snowfall amounts, one
suggestion is to purchase an 8 gallon trash container and turn it
upside down over the Hybrid installed on a 2 or 3 foot pipe. This
will prevent snow from accumulating around the UHF connector
ports. An 8 gallon size may be purchased in home supply stores. A
brick or heavy block of wood can be placed on top to prevent
being blown over by strong winds.

TYPES OF VERTICAL MATERIAL

The following have been successfully used in Four-Square arrays in conjunction with the COMTEK
SYSTEMS ACB-4 SERIES:

1. Aluminum irrigation tubing 3" to 5" OD. Typical height for 3" OD coupled is 64 feet for

resonance at 3.650. Heights will vary slightly, being determined by the diameter used.

2. Rohn 20/25G tower on insulated bases for 80 meters. Rohn 25G and 45G are used on 160

meters.

3. Wires supported from nylon/Dacron ropes, which are in turn tower supported. Trees offer

supports for wire arrays as well, however, tree supported arrays require heavy maintenance.
Wire arrays typically do not exhibit bandwidth as aluminum elements.

4. Hy-Gain Hy-Towers extended to 75 feet with all other stubs removed, for 3.650.

5. Short Top-Loaded verticals for 80 meters from 38 feet to 50 feet in height. These work well,

but do not cover the entire band as full quarter wave sized aluminum elements.

6. Commercial verticals may also be used in a four-square array. DX Engineering

(www.dxengineering.com) has a full line of vertical antennas that are perfect for phased array
systems.

DX Engineering sells quality aluminum tubing in 3' and 6' lengths. The 6' pieces are UPS
shippable. Phone: [phone] or visit the DX Engineering web page at www.dxengineering.com

ADDITIONAL REFERENCES

Antennas and Techniques for LOW-BAND DX'ing by ON4UN, was published by ARRL,
The Amateur Radio VERTICAL ANTENNA HANDBOOK by Capt. Paul H. Lee,

N6PL. This excellent book covers Conical Monopoles, an excellent vertical superior to shunt­feeding towers. All About VERTICAL ANTENNAS by William I. Orr, W6SAI & Stuart D. Cowan,
W2LX.

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INSTALLATION NOTES and FREQUENTLY ASKED QUESTIONS. (FAQ)

How close can I install my 4-Square to other verticals or my tower?

Unless the 4-Square will be installed on a multi-acre location, insure the array will not be
beaming into towers or other objects such as buildings closer than one-half wavelength. Some
installations perform well at lesser distances, but one-half wave distance is the recommended
minimum.

Will a 4-Square cover the entire band?

Yes and No. Using full sized aluminum verticals, the 20, 40, and 80-meter bands can be fully
covered with appropriate spacing. 160 meters can easily cover 1.800 to 1.900 using Rohn
20G/25G tower sections as the radiators. Using wire elements will not permit full coverage.

Can I install a 40 meter 4-Square inside my 80 meter 4-Square?

This is not recommended. The 40 m performance will be greatly reduced due to mutual

coupling. (No 20 m inside a 40 m; No 80 m inside a 160 m etc. also applies.)

If one phasing line is too short to reach a vertical, can I add a few feet? Can I make
one 3/4 wave long while the other 3 are at 1/4 wavelength?

Simply stated, No. If un-equa1 lines are used, the phase relationship is incorrect and
performance will be poor. Make ALL either 1/4 or 3/4 electrical wavelengths in length.

How deep do I bury the radials?

If foot traffic is minimum, simply cut grass shorter than normal and pin radials down with wire
lawn staples every 3’ to 5’ as terrain requires. Grass thatch will cover them in a few months.
(Don’t forget to raise cutting level of mower!) If burial is required, slight trenching 1"-2" is
sufficient.

Should I use three or four conductor control cable?

Four conductor control cable is recommended for future upgrades. This is when you would
replace the COMTEK system components (relay unit and control console) with a complete DX
Engineering Transmit Four-Square system which will improve performance and give you the
added benefit of Omni.

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ACB-4 TROUBLESHOOTING

One of the most common reported problems after a new installation is lack of front-to-back or
working a station opposite the normal direction. This is caused by incorrect sequence of wiring
from the inside control console or the quarter-wave coax lines, to the relay unit. The control console
wiring sequence from left to right is G-1-2 (3 is not used):

On the relay unit, the connection pattern is GND, CTL1, CTL2.

The following truth table indicates relay closure in selected positions, and voltages applicable to the
terminals in the ACB-4 control console. See page 8 for directional connections for the quarter-wave
coax.

POSITION

TERM. 1

TERM. 2

K1

K2

K3

1

l2-14 Vdc

12-14 Vdc

Close

Close

Close

2 (Default)

None

None

Open

Open

Open

3

12-l4 Vdc

None

Close

Close

Open 4 None

12-14 Vdc

Open

Open

Close

Voltage level depends on DC voltage used to power the Control Console.

- 16 -

MOUNTING CLAMP

INSTALLATION

Control
Console
Position

Beam

Direction

Relative Phasing

#1

#2

#3

#4

1

NW

-180

-90 0 -90

2

NE

-90

-180

-90

0

3

SE

0

-90

-180

-90

4

SW

-90 0 -90

-180

- 17 -

Thank you again for purchasing a Comtek Hybrid Phasing System for your 4-square. Comtek has
manufactured hybrids since 1989, and have models in use world wide by major Contest and DX
stations.

Enjoy your 4-Square array’s performance while contesting and DXing.

Comtek Systems: www.comteksystems.com

- 18 -

ACCESSORIES

COM-CW3 3 conductor control cable
COM-CW4 4 Conductor wire
COM-VFA-4 Vertical Feedpoint Assembly
DXE-RADP-3 Stainless Steel Radial Plate

ACB Series Part Numbers:

COM-ACB-160-A 160 Meter Relay Unit and Control Console
COM-ACB-80-A 80 Meter Relay Unit and Control Console
COM-ACB-40-A 40 Meter Relay Unit and Control Console
COM-ACB-30-A 30 Meter Relay Unit and Control Console
COM-ACB-20-A 20 Meter Relay Unit and Control Console

COM-ACB4A Control Console

COM-ACB-160 160 Meter Relay Unit
COM-ACB-80 80 Meter Relay Unit
COM-ACB-40 40 Meter Relay Unit
COM-ACB-30 30 Meter Relay Unit
COM-ACB-20 20 Meter Relay Unit

- 19 -

COMTEK SYSTEMS 4-SQUARE DUMPED POWER CHART

Dumped Power
In Watts

200

150

100

50

0

1.8 1.9 2.0

3.5 3.6 3.7 3.8

7.0 7.1 7.2 7.3

14.0 14.1 14.2 14.3

Record dumped power levels at these frequencies, depending on which ACB-4 model hybrid phasing
system installed. Maintain with your instructions as a reference in the event SWR or dumped power
levels change.

- 20 -

Technical Support

If you have questions about this product, or if you experience difficulties during the installation,
contact Comtek Systems at [phone]. You can also e-mail us at:

[e-mail]

For best service, please take a few minutes to review this manual before you call.

Warranty

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 NEITHER MAKES NOR ASSUMES ANY OTHER WARRANTY WHATSOEVER,
WHETHER EXPRESS, STATUTORY, OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY AND
FITNESS, AND NO PERSON IS AUTHORIZED TO ASSUME FOR DX ENGINEERING ANY OBLIGATION OR
LIABILITY NOT STRICTLY IN ACCORDANCE WITH THE FOREGOING.

©DX Engineering 2022

DX Engineering®, DXE®, DX Engineering, Inc. ®, Hot Rodz®, Maxi-Core®, DX Engineering THUNDERBOLT®, DX
Engineering Yagi Mechanical®, EZ-BUILD®, TELREX®, Gorilla Grip® Stainless Steel Boom Clamps, Butternut®,
SkyHawk™, SkyLark™, SecureMount™, OMNI-TILT™, RF-PRO-1B®, AFHD-4® 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 change without notice.