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Introduction
The
DXE-RR8B-SD
is the largest switch in the DX Engineering RR8 series. It is designed to
switch coaxial lines in high-power RF systems. RF rated enclosed relays with wide contact gaps
provide exceptional RF voltage and current capability. The
RR8B-SD
can be used to
simultaneously select multiple output ports as well as conventional one-of-eight antenna switching.
This allows the
RR8B-SD
to be used in complex antenna phasing and stacking systems as well as
traditional switching arrangements. The
RR8B-SD
also uses a removable screw terminal control
cable plug. The removable plug greatly simplifies installation by eliminating the need for soldering.
Disassembly is not required for control wiring access
The
RR8B-SD
also offers the following features:
• RF Shielded Weatherproof Housing - unique protection
• Excellent Port Isolation; greater than 60 dB at 30 MHz, worst case.
• High-RF tolerant, Amphenol UHF connectors
• Shorted or open selection of unused antenna ports
• Enclosed 25-ampere high-voltage RF relays
• Safe 12-volt relay operation
• MOV Lightning protection on control lines
Specifications
Power Rating:
>10 kW normal amateur operation on all modes when using antennas with less than
2:1 SWR on 30 MHz and below. >5 kW above 30 MHz.
Control Voltage
: 10-14 Vdc at 160 mA
Port-to-Port Isolation
: >60 dB below 30 MHz
Impedance
: 50 ohms
Control Line
: Control lines (usually BCD ) can normally use good quality CAT5e cable (4 twisted
pairs of 24 AWG wire) for runs up to 1000 feet. Typical DX Engineering BCD control lines
requirements are +12 VDC at 25 milliamps. Depending on the number of control lines needed
(usually 3 or 4) you can double up the twisted pairs of CAT5e cable, or use control wire that is at
least 22 AWG, allowing runs up to 1500 feet. If you use a cable with more conductors, it is a good
idea to tie the unused conductors to ground. For longer runs of control cable, use a line loss
calculator to ensure you supply the proper control levels needed.
Approximate BCD Control Line Lengths.
Minimum Copper
Wire Gage (AWG)
Length
24
1,000 feet
22
1,500 feet
20
2,000 feet
Theory of Operation
The
RR8B-SD
uses a star arrangement of eight relays to select one or more of eight output ports
when voltage is applied from an 8-wire control line. The eight RF-rated relays provide greatly
improved power handling and SWR over conventional switches and allows port-to-port connections
between any of the eight output ports.
