DX Engineering DXE-RR8B-HP-P1 Technical Article

Controlling a Stacked Yagi Array

Using the DXE-RR8 Series (-SD or -HP)

Remote Antenna Switch

DXE-RR8-STACKED-YAGI-Technical-Information - Revision 2b

Using the DXE-EC-8 One of Eight Control Console, or DXE-CC-8A Antenna 8 Port Switch Console

© DX Engineering 2018

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Introduction

The DX Engineering RR8 series remote antenna switches (DXE-RR8 (series)-HP and -SD), when
combined with the DXE-EC-8 One of Eight Control Console or DXE-CC-8A Antenna Switch 8
port Control Console, enables users to simultaneously select multiple antennas in stacked arrays of
Yagi or broadside arrays. This brief guide provides instructions on how to properly connect and
control stacked antennas and phasing lines to the RR8 series of switches.

Principles of Stacked Yagi Arrays

The DX Engineering RR8 series/EC-8 or CC-8A remote switching system, when combined with a
simple diode matrix and 1/4 wavelength 75Ω Q-sections, allows users to stack four antennas and
obtain an SWR under 1.35:1 (when any combination up to three antennas is selected).

The eight ports on the RR8 remote antenna switch and the 8 positions on the EC-8 or CC-8A
controller offer users flexibility in connecting many combinations of the four antennas. More
information on stacking yagi antennas can be found in the ARRL Antenna Book in Chapter 11.

Connecting Multiple Yagi Antennas

Since the eight ports on the RR8 enable so many combinations
for stacked antennas, we have created an example to illustrate
one possibility of this versatile antenna switch.

Example An amateur radio operator has a tower with four
stacked Yagi antennas as symbolized in Figure 1. After modeling
the possible antenna combinations, the operator decides on the
arrangement shown in Table 1. From that, he creates Table 2 as
a matrix to track the association of ports on the RR8, switches on
the CC-8A controller, and antennas on the stack. To make
switching easier, he then creates a diode matrix as shown in
Figure 2. Finally, he attaches the feedlines according to the
guidelines highlighted on page 3.

To connect the antennas in this example, refer to the tables and
figures on page 2 and the guidelines table on page 3, and then do
the following:

1. Determine how many antennas you want to stack.

Note: You can connect up to 4 antennas, but only 3 can be selected
individually or simultaneously. In this example, Antenna B is Figure 1
selectable in a stack, but not independently.

2. Create a matrix like Table 2 to assign antennas to the proper ports and switches.

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Table 1

Arrangement of Stacked Yagis Based

on Figure 1

Table 2

Switching Possibilities of Stacked Yagis

Based on Figure 1

EC-8 or CC-8A
Switch Position

Antenna

RR8 series

Port Number

EC-8 or CC-8A
Switch Position

1

A

1 2 3 4 5 6 7

8

2

C

1 (Antenna A)

X

3

D

2 (Antenna A)*

X X

4

C and D

3 (Antenna B)

Not Selectable by Itself

(in this example)

5

B and C

4 (Antenna B)*

X X X X

6

A and B

5 (Antenna C)

X

7

A, B and C

6 (Antenna C)*

X X X X 8 B, C and D

7 (Antenna D)

X

8 (Antenna D)*

X X

* = Must be grounded when not selected

Tables 1 and 2 - Control Matrix for the CC-8A Switch Positions and RR8 Ports

3. Create a diode matrix (see Figure 2) to configure the switching arrangement on the EC-8 or

CC-8A. Use 1N4001 through 1N4007-type diodes. The diode matrix can be built around the
control cable plug on the CC-8A or internally on the EC-8. Figure 2 depicts the diode logic
determined in Table 2. Control position 1,2 &3 all pass through single diodes and select single
antennas. Control position 4, 5 & 6 each connects to 2 diodes and select 2 antennas
simultaneously. Control position 7 & 8 each connects to 3 diodes and select 3 antennas
simultaneously.

Figure 2 - CC-8A Diode Matrix shown Figure 3 - Coaxial Cables & T's

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4. Sketch a diagram of the coaxial feedline connections (refer to Figure 3).

Guidelines for

Switching Stacked Yagi Antennas

1. Stacked arrays must be identical antennas on the same band.

2. Feedlines connecting each antenna to the RR8 must be the same length. These 50Ω

transmission lines can be any length, but the length for each must be the same.

3. The 75Ω transmission lines must be electrically ¼-wavelength. RG-11 is acceptable even

at high power. The end directly connected to the RR8 provides the connection for stacked
configurations and must be grounded when not selected. This is accomplished by soldering
in jumpers inside the RR8 unit, as described in the RR8 manual, on the even numbered
ports as described in this example.

4. The junctions of the 75Ω and 50Ω cables must be made with T-connectors mounted

directly to the RR8 connector.

5. Establish a numbering convention for RR8 ports; i.e., T-connectors go to odd-numbered

ports and 75Ω Q-sections connect to even-numbered ports.

6. T-connector ports cannot be grounded, they must “float” when not selected so they do not
have jumpers. Ports connected by 75Ω line must be grounded when not selected do have
jumpers as mentioned above. This is accomplished by configuring the internal jumpers on
the RR8 as described in the RR8 user manual.

5. Cut the feedlines to the proper length and attach them so that the connectors face downward (see
the RR8 series user manuals).

Antennas that are not stacked can be used on separate bands, and every RR8 port can be used
for any antenna. Each stacked antenna requires two ports on the RR8; antennas that are not
stacked require only one port.

Technical Support

If you have questions about this contact DX Engineering at [phone].
You can also e-mail us at: [e-mail]

©DX Engineering 2018

Specifications subject to change without notice.

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