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Introduction
The DX Engineering RR8 remote antenna switches, when
combined with the CC-8 controller, 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 stacked antennas and
phasing lines to the RR8 series of switches.
Principles of Stacked Yagi Arrays
The DX Engineering RR8 series of
remote antenna switches, when combined with a simple diode matrix and 1/4
wavelength 75-Ohm 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 CC-8
controller offer users flexibility in connecting many combinations of the four
antennas. More information on stacking yagis or broadside arrays can be found in
the ARRL Antenna Book in Chapter 11.
Connecting Multiple Yagis
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-8 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 4.
To connect the antennas in this example, refer to the tables, figures and
guidelines below, 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 selectable in a
stack, but not independently.
2. Create a matrix like Table 2 to assign antennas to the proper ports
and switches.
3. Create a diode matrix (see Figure 2 below) to configure the
switching arrangement on the CC-8. Use 1N4001 through 1N4007-type diodes. The
diode matrix can be built around the control cable plug on the CC-8.
4. Sketch a diagram of the coaxial feedline connections (refer to Figure
2 below).
5. Cut the feedlines to the proper length and attach them so that the
connectors face downward (see page 3 of RR8 user manual).
