DX Engineering DXE-PS-2B-P User manual

Pro-Stack Broadband
Two Antenna
Phasing System
DXE-PS-2B-P
DXE-PS-2B-P-INS Revision 1f
© DX Engineering 2014
1200 Southeast Ave. - Tallmadge, OH 44278
Phone: [phone] ∙ Tech Support and International: [phone]
Fax: [phone] ∙ E-mail: [email protected]

- 1 -
Introduction
The DXE-PS-2B-P Pro-Stack Broadband Two Antenna Phasing System is primarily designed to
combine two identical Yagi, log periodic or vertical antennas in a phasing arrangement. The DXE-
PS-2B-P is a frequency independent broadband phasing system that operates with two mono-band
antennas on any band, from 160 through 10 meters. It is a 50Ω system that is switched by applying
12 to 15 volts dc to three control wires. The unit can be used for other applications requiring the
following four basic antenna feed selections:
Both antenna ports in-phase
Both antenna ports out-of-phase
Antenna port 1 only
Antenna port 2 only
Default is both antenna ports in-phase. To ensure lowest SWR, impedance matching automatically
changes when any antenna is disabled.
Information on the appropriate distances for the separation between the two stacked Yagis, to create
a versatile, high performance array, is discussed fully in the “ARRL Antenna Book”, 20th Edition.
Generally, stacked Yagi antennas are separated vertically greater than 1/2-wavelength, free space.
The bottom antenna should generally be as high above ground as the stack spacing distance.
Optimum spacing is generally around one wavelength.
Features
Power Handling up to 5 kW
Broad band coverage on 160-10 meters
RF Shielded Weatherproof Housing - unique protection
High-RF tolerant, silver - PTFE UHF connectors
Proven DX Engineering RF Relays - high performance
Safe 12 volt dc relay operation
MOV surge protection on control lines
RoHS compliant assembly
Using Antenna Pattern to your Advantage
Signals arrive at your antenna from different azimuth directions and different elevation angles,
depending on many variables. The ability to steer the major lobe of an antenna (or array of
antennas) in both planes moves the major lobe and nulls, not just the major lobe. Typically two dB
or slightly more is gained by stacking a second antenna. The largest advantage is not necessarily
additional gain, but the ability to move harmful pattern nulls away from primary signal arrival
angles. While gain makes a marginal improvement, moving a null can be a phenomenal change,

- 2 -
sometimes the difference between barely readable and having a strong signal which can provide the
performance edge needed to work rare DX - and win contests.
It is therefore desirable to not only change azimuthal direction by rotating the antenna, but also
elevation angle by switching between antennas at different heights above ground and/or changing
the phase relationship between multiple antennas. The old standard system in stacks was to activate
or disable specific antennas in the stack to change pattern. In general, gain remains higher when all
antennas are driven and phase is changed. This system allows either phase inversion or completely
disabling any antenna.
The DXE-PS-2B-P Pro-Stack Broadband Two Antenna Phasing System provides the greatest
flexibility from two identical antennas. This system contains a broad-bandwidth high-power 2:1
impedance matching transformer. This eliminates common requirements of using mixtures of 75Ω
and 50Ω cables for impedance matching.
A central stack-box location is best. Feedlines to each antenna from any stack-box should match
the antenna system impedance and have the same electrical length. Feedlines need only be long
enough to reach comfortably from each antenna to the stack-box. While it is best to have feedlines
equal electrical lengths, total errors of twenty electrical degrees or less have only a minor impact on
system performance. With such wide tolerances in cable lengths, cutting similar cables to equal
lengths will suffice. There is no need to closely phase-match cables.
Larger Array Building Blocks
The DXE-PS-2B-P Pro-Stack Broadband Two Antenna Phasing System control box works in
conjunction with identical boxes, or in combinations with 3-stack boxes, to build larger stacked
arrays. For example, four antennas are stacked using three DXE-PS-2B-P boxes. In this example,
two PS-2Bs would be centrally located; one between the upper and lower antenna pairs, and each
antenna would be fed through equal length cables. A single PS-2B located in the middle of the stack
feeds the upper and lower boxes through equal lengths cables. This would allow the user to take any
antenna or combination of antennas off-line, or feed any antenna or combination of antennas out-of-
phase. Keep in mind out-of-phase systems generally have more gain than systems that disable
antennas.
The best arrangement for larger stacked systems is feeding antennas in pairs, with the pairs fed from
other stacking boxes. This is a distributed or branched feed system. All cables at any branch level
should be equal length. While it is best to avoid length errors, accumulated errors totaling 20-
degrees or less have a minimal affect on gain and positioning of lobes. With such wide tolerances in
cable lengths, cutting similar cables to equal lengths will suffice. There is no need to closely phase-
match cables.
Multiple antenna arrays require modeling with software such as “EZNEC”by W7EL to examine the
multiple patterns possible by reversing phase and dropping antennas in a large system.

- 3 -
This unit is RoHS (Reduction of Hazardous Substances) compliant. The components,
including the solder used are all lead free. If you decide to do any modifications or internal
repairs, you should use only lead free solder and lead free soldering tools. Lead free solder
melts approximately 100 degrees (F) higher than the old leaded solder, so you may need to
upgrade your current soldering system.
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 (www.dxengineering.com) for the latest revision manual.
Additional Material Needed but not Supplied:
UMI-81343 - Anti-Seize compound - used on the threads of Stainless Steel Hardware to
prevent galling and aid in proper tightening torque.
Two electrically equal length 50Ω coaxial cables to run from the DXE-PS-2B to each of the
identical Yagi antennas.
4-Wire Control Cable - COM-CW4 Control Cable is ideal.
LCT-37534 Dielectric Grease

- 4 -
1 - Stacking Yagis
In-phase
The greatest gain increase comes from the
first pair of antennas.
Optimum spacing is usually around one-
wavelength stack spacing.
Lower heights produce a cleaner pattern.
Avoiding nulls in the middle of useful
propagation angles is often more important
than a small gain improvement.
Note that increased heights result in maximum
stack gain improvement (maximum gain still
occurs at about 1 wavelength antenna-to-antenna
spacing) and lower wave angles. The lowest
antenna should generally be significantly higher
than the antenna-to-antenna spacing above ground
for maximum stacking gain. Greatly increased
height produces more minor lobes and stronger
minor lobes.
Neglecting feedline losses, over medium soil two
stacked Hy-Gain model 205CA 20 meter antennas
have the following in-phase gain improvement:
Figure 1
70 feet = 1 wavelength
Height
35+70 ft
52+104 ft
70+140
Optimum
87.5+175
110+180ft
Gain/ angle
15.41dBi
@15 deg
16.89 dBi
@11 deg
17.27dBi
@ 8 deg
17.17
@7 deg
17.87 dBi
@ 6 deg
Stack spacing
0.5 wave
.75 wave
1 wave
1.25 wave
1 wave
Reference
Figures
Figure 1
Figure 2
Figure 3

- 5 -
Figure 2 - Maximum gain at 8 degree elevation
Figure 3 - Maximum gain at 6 degree elevation

- 6 -
Switching Out One Antenna
Dropping one antenna is useful to change patterns and fill null areas, even if it results in a loss of
overall gain. It is also useful for reducing or elimination precipitation static during inclement
weather by disconnecting the upper antenna. Pattern would depend on the type of antenna and
antenna height.
Out-of-Phase
Out-of-phase stacking is more effective at raising wave angle than dropping one antenna. Here is
the typical pattern of a maximum gain stack of Hy-Gain 205CA 20 meter antennas fed out-of-phase:
Figure 4 - Maximum gain at 28 degree elevation

- 7 -
Overlaying the two patterns of in-phase and out-of-phase:
Figure 5
If signals arrive in a null of the in-phase pattern, changing to out-of-phase can result in almost 40
dB increase in field strength.
In the pattern above, Blue is out-of-phase. Red is in-phase. This pattern demonstrates why the real
advantage is filling of nulls. Note the blue trace is 2 to 3 dB down from the in-phase gain, so it
primarily fills nulls.

- 8 -
2 - Phased Verticals
The stacking box can be used to feed three vertical antennas in a four pattern array. In this
arrangement the three antennas are each individually 1/4-wave resonant antennas. The center # 2
passive element must be directly grounded to a good ground system at all times. Elements #1 and
#3 are then fed in various phase relationships. The following patterns are for three 1/4-wave
elements over perfect ground. Figure 7 shows the proper radial system for three verticals with the
radial systems bonded together where they would intersect.
Elements 1 and 3 out-of-phase (in this special case middle element has no current):
Figure 6
Figure 7 Figure 8
EZNEC+ ver. 5.0
--------------- SOURCE DATA ---------------
Frequency = 7.1 MHz
Source 1 Voltage = 190.7 V at 18.03 deg.
Current = 4.136 A at 0.0 deg.
Impedance = 43.84 + J 14.27 ohms
Power = 750 watts
SWR (50 ohm system) = 1.392 (75 ohm
system) = 1.802
Source 2 Voltage = 190.7 V at -161.97 deg.
Current = 4.136 A at 180.0 deg.
Impedance = 43.84 + J 14.27 ohms
Power = 750 watts
SWR (50 ohm system) = 1.392 (75 ohm
system) = 1.802
Total applied power = 1500 watts

- 9 -
Element one or three only (pattern can reverse):
Figure 9
EZNEC+ ver. 5.0
--------------- SOURCE DATA ---------------
Frequency = 7.1 MHz
Source 1 Voltage = 252.1 V at 32.82 deg.
Current = 7.08 A at 0.0 deg.
Impedance = 29.93 + J 19.3 ohms
Power = 1500 watts
SWR (50 ohm system) = 2.024 (75 ohm system) = 2.701