Delta Electronics, Inc.

Model SLS-7/SLS-7M Antenna Switching Matrix


The Delta Electronics Model SLS-7 Strip Line Switch is a manually or remotely controlled 50 Ohm switch matrix for connecting any of a number of transmitters to any of a number of antennas. The SLS-7 is ideally suited for use with 40 kW average power transmitters and with 2.5:1 maximum VSWR antennas. The switch design provides a compact system with excellent power rating, low insertion VSWR, low insertion loss, and high isolation characteristics.

The design of the switch makes it inherently impossible to connect more than one transmitter to one antenna or to connect one transmitter to more than one antenna. An interlock circuit that exactly duplicates the RF circuit operates to remove power from the RF circuit prior to switching. At the completion of the switching sequence, the interlock circuit is rerouted and reconnected to protect the new RF circuit. An indicator circuit provides a dry contact closure for each transmitter to antenna connection for remote indication of the switch status.

The switch is available in either a manually operated version (SLS-7) or a motorized version (SLS-7M). All manually operated switches incorporate a motorized wiring harness and can be easily converted to motorized operation.


The Model SLS-7 Strip Line Switch comprises a matrix of horizontal transmission lines (rows), vertical transmission lines (columns) and crosspoint switching elements at each row-column intersection. Each crosspoint consists of row and column leaf springs and a rotor contact. In the Thru position, RF power flows through the crosspoint to the adjacent row leaf spring and adjacent column leaf spring, and the grounded rotor contact shields the transmission lines from each other. When the rotor contact is rotated 90 degrees to the Turn position, the conductive shoulders of the rotor contact connect the row transmission line to the column transmission line and perform the desired switching. The rotor contact also disconnects the adjacent row and column leaf springs from the switched circuit. This action removes transmission line stubs from the RF circuit and prevents paralleling of inputs or outputs.

All auxiliary interlock and indicator switching is performed by a wafer switch deck incorporated in the manual switch or motor actuator located on the rear of each switch module. The rotor contact is mechanically linked to the manual switch or motor actuator. Thus, the rotation of the rotor contact automatically performs the auxiliary switching.

The protective interlock circuit exactly duplicates the RF circuit through the switch. The timing of the interlock switching prohibits the occurrence of "hot" RF switching. The first 30 degrees of rotation opens the established interlock path removing RF power from the crosspoint. The second 30 degrees of rotation accomplishes RF path switching. The last 30 degrees of rotation establishes the interlock circuit to the new RF path and permits power to be applied.

The SLS-7 also provides a bussed row and column indicator circuit for remote matrix status. The indicator circuit switch closes when the crosspoint is in the Turn position and opens when the crosspoint is in the Thru position.

The SLS-7 provides the capability for remotely controlled switching of all crosspoints. The switch may be initially equipped for manual operation of all crosspoints, or for motorized operation of some or all crosspoints. All motorized crosspoints are capable of manual override operation. Manual switch controls are accessible from the front of the switch.


The SLS-7 is available in either a free-standing, self-supporting cabinet or a rack mounting panel for installation in a standard 19" or 24" wide EIA equipment rack. The switch is constructed per customer order to contain the number of inputs, outputs, and crosspoints required for the particular application. Self-supporting cabinet switches are available with sizes ranging from one column and one row (1 x 1) to twenty-five columns and twenty-five rows (25 x 25). Consult the factory for applications requiring matrices larger than twenty-five columns or rows. Rack mounted switches may have matrix sizes of up to eight rows by two columns for the 19" rack-mounting version, and matrix sizes of up to eight rows by four columns for the 24" rack-mounting version.

The following basic configurations are available. For each configuration, inputs from transmitters may be assigned to either the rows or columns and outputs to antennas may be assigned to either the columns or rows, respectively, depending on the application and design of the communication facility.

Configuration A: This configuration has the column connectors on the top of the switch and the row connectors staggered on opposite sides of the switch facing to the rear.

Configuration B: The column connectors are on the top of the switch. All row connectors are located along one side of the switch facing to the rear. The standard BL configuration defines the row connectors on the left side of the switch when viewed from the front. The optional BR configuration defines the row connectors on the right side of the switch when viewed from the front.

Configuration D: This configuration defines a standard 19" or 24" wide EIA equipment rack-mounting switch. All row and column connectors face to the rear and are limited to 1-5/8" EIA male flange maximum size.

Configuration DSA: This configuration, a modification of Configuration A, double staggers the row connectors on opposite sides of the unit to provide four vertical columns of row connectors. This configuration is recommended for a switch with the row connectors extended to top of switch using right angle rigid coax transmission lines in order to minimize the cabinet depth.

Standard Features

Interlock Isolation Unit

The SLS-7 includes the Model IIU Interlock Isolation Unit to provide an isolated interlock interface to the transmitters. The interlock circuit of the switch is a single wire circuit with a common return. Since the interlock circuits of many transmitters are above ground and may not be connected together via the switch interlock harness, the IIU relays provide isolated interlock switching for each transmitter. The IIU also provides an additional contact closure to a common for each valid interlock circuit. This contact closure may be monitored by a control system for remote indication of the interlock circuit status.

Interlock Keylock Switches

The SLS-7 is equipped with interlock keylock switches installed in the output interlock circuit. The keylock switches provide positive lockout of the interlock circuit and the corresponding RF output. The key can be removed only when the keylock switch is in the open interlock circuit position. Each keylock switch may be supplied with either different keying or identical keying.

RF Connectors

The standard RF termination is 3-1/8" EIA male flange. Optional terminations are 1-5/8" EIA male flange, 7/8" EIA male flange, Type LC receptacle, Type LT receptacle, and Type N receptacle. The switch may be initially equipped with any combination of these connectors. Modification kits are available for field conversion of these terminations.


Key Operated or Automatic Antenna Grounding

The switch may be equipped with a special row or column of grounding crosspoints that ground each output terminal when the associated crosspoint is in the Turn position. This feature allows an antenna to be grounded at the switch for isolation during maintenance activities or for static discharge when the antenna is not connected to a transmitter. With this option, the row or column adjacent to the output terminals is equipped with grounding crosspoints. These antenna grounding crosspoints may be equipped with either key operated rotor assemblies for manual grounding or with actuators for automatic grounding. The key operated grounding crosspoints can only be manually operated and can only be operated using the unique key for that crosspoint. The key can be removed only when the crosspoint is in the antenna ground position. The motorized antenna grounding crosspoints are controlled by the associated Model MCU-8 or MCU-9 Matrix Control Unit to automatically ground the antenna upon disconnection of the antenna from a transmitter.

Test Point

An additional row or column terminated with a Type N connector may be provided on the matrix to be used as a test point for antenna VSWR measurements.

Row Extension Kits

When all coaxial cables connecting to the switch are located in ceiling trays, the switch may be equipped with right angle rigid coaxial transmission lines on the row connectors to extend these connectors to the top of each switch. These row extension kits are available in 7/8" EIA, 1-5/8" EIA and 3-1/8" EIA standard transmission line sizes.

Dummy Load

The SLS-7 may be supplied with dummy loads as part of the switch system. In certain instances, low power dummy loads may be installed inside the matrix cabinet.


On special order, the SLS-7 may be supplied with extra terminations to permit through trunking of either rows or columns. Optionally, the SLS-7 may be inverted to locate the column connectors on the bottom of the switch for applications utilizing floor cable trenches for the coaxial cables.

Installation Services and Logistic Data

Installation services and logistic data are available for the Model SLS-7 Strip Line Switch. The installation services include site survey, system installation and site acceptance tests. The logistic data includes provisioning data, spare parts lists, factory training, reliability and maintainability analyses, safety studies, and technical manual documentation.


Matrix Control Units

The SLS-7M may be remotely controlled with either the Delta Model MCU-8 Matrix Control Unit or the MCU-9 Matrix Control Unit.. The MCU-8 and MCU-9 provide standard features such as transmitter/antenna circuit display, interlock status display, transmitter/antenna busy protection and unavailable transmitter/antenna circuit protection. The MCU-8 provides remote control and a video status display for a single switch up to forty inputs and forty outputs and for multiple switch systems up to four 16 input by 16 output switches. The MCU-9 provides remote control and a plasma panel status display for a single switch up to sixteen inputs and sixteen outputs and for dual switch systems up to 8 inputs by 8 outputs each. The MCU-8 and MCU-9 are available with an EIA RS-232 or RS-422 serial data interface to a customer's control system or computer.

Serial Interface Assemblies

The SSSI Small Switch Serial Interface and the MSSI Medium Switch Serial Interface provide an RS-232 serial data interface for remote control and status reporting of the Model SLS-7M. The SSSI is used with switch sizes up to four columns and four rows and the MSSI is used with switch sizes up to eight columns and eight rows. The single printed circuit board interface assembly includes microprocessor, random access memory, programmable read-only memory, actuator interface circuits and serial data interface circuits. The control and status command format is based on the Model MCU-8C and Model MCU-9C serial interface format standard for compatibility with computer control programs and drivers developed for transmit matrix control and status via the MCU-8C or MCU-9C.

Matrix Control Software

Remote control software which provides control, status display and diagnostic testing of the SLS-7 and MCU-8/9 is also available. The software operates on an IBM-AT or compatible personal computer with VGA graphics. The software is available for use with a customer supplied personal computer or as part of a Delta supplied computer system. In addition to providing all the basic control and status features of the MCU-8/9 units, the software enhances the control capabilities by using mouse-driven equipment selection routines and expands the display capabilities to include large matrix schematic diagrams and equipment labels. The program also provides diagnostic routines to automatically test remote matrix operation capabilities and to isolate faults to the line replaceable unit level. Preset switch configurations establishing multiple transmitter/antenna connections may be defined, stored and automatically implemented. All switch configuration changes, status reports, and diagnostic test results may be logged on the system printer. Optional program modules provide control and status reporting of other communication station facilities including rotatable log periodic antennas, receive matrices, transmitters, receivers, and site security equipment.

The software operates as a remote controller for the SLS/MCU system. Thus, the personal computer may communicate with the MCU using an RS-232 or RS-422 serial data bus directly or via modems and telephone lines or radio circuits. Alternately, the switch may be equipped with a Matrix Interface Unit and a direct RS-232/422/423 or fiber optic data communication circuit established between the computer and the switch.

Frequency Range:DC to 32 MHz

(Operation to 150 MHz available on special order. Consult factory for extended frequency range performance specifications.)

Impedance:50 Ohms Coaxial
Power Rating:100 kW Average, 320 kW Peak
Unity VSWR, 2500 Ft Maximum Altitude

(To determine the power rating for other values of load VSWR, divide power rating by load VSWR. Consult factory for higher altitude derating.)

Insertion VSWR:1.10 maximum for matrix sizes up to 25 x 25
Insertion Loss:   Size              Loss
10 x 10:         0.10 dB
16 x 16:         0.15 dB
20 x 20:         0.18 dB
25 x 25:         0.22 dB

(Insertion loss for all models at 32 MHz is 0.025 dB + N(0.004) dB. N equals the number of modules in the path. A 10 x 10 matrix has 19 modules in the longest path.)

Cross Channel Isolation:70 dB Minimum
Terminations:Standard:  3-1/8" EIA Male Flange
Optional:  1-5/8" EIA Male Flange
                7/8" EIA Male Flange
                Type LC Receptacle
                Type LT Receptacle
                Type N Receptacle
Size:Self-Supporting: 64.75" high (11 row max) x 17" deep

Height increases by 4.0 inches for each row above 11. Width varies with number of columns. Depth increases to 30 inches for switches with 14 or more rows. Contact factory for specific size information.

Rack Mounting: 19" or 24" wide standard EIA rack panel x 20" deep. Height varies with number of rows.

Weight:   Size         Manual       Motorized
10 x 10:       625 lbs        750 lbs
16 x 16:     1300 lbs      1650 lbs
20 x 20:     2000 lbs      2550 lbs
25 x 25:     3800 lbs      3800 lbs

(Switch weight varies with options. The table above gives approximate weights for some representative sizes of self-supporting switches.)

Accessories:Key Operated or Automatic Antenna Grounding
Built-In Dummy Loads
Interlock Keylock Switches
RF Connector Field Modification Kits
Row Connector Extension Kit
Remote Control Options:Delta Matrix Control Units - MCU-8 and MCU-9
Delta Serial Interface Assemblies - SSSI and MSSI
Delta Remote Control Software for personal computer remote control.

For additional information on any of our products, please contact Sales to discuss your particular requirements:
Delta Electronics, Inc.
5730 General Washington Drive
P. O. Box 11268
Alexandria, VA 22312

Phone: (703) 354-3350
U.S. Toll Free: 1-800-8-DELTA-8 (1-800-833-5828)
Fax: (703) 354-0216

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