External Reference (J3); Send Data (J4); Receive Data (J5) - Comtech EF Data SDM-650B Installation And Operation Manual

Configuration
The G.703 2048 kbit/s optional connector board provides the balanced signals on a
15-pin female D connector. These signals are the same as the G.703 interface connector.
Refer to Section 3.2.4.4 for the connector pinouts.
The unbalanced signals are accessible from J3, J4, and J5. A description of available
unbalanced signals and directions is described in the following paragraphs.

3.2.4.6 External Reference (J3)

The external reference input signal has two inputs. The BNC connector, J3, has the
unbalanced input signal, and the DB15 connector has the balanced input signal.
To use the unbalanced input on the BNC connector, SW1 positions 1 and 2 must be
closed (close to PCB).
To use the balanced input on the DB15 connector, SW1 positions 1 and 2 must be open
(away from PCB).
The switch pack is located on the optional G.703 2048 kbit/s connector board.

3.2.4.7 Send Data (J4)

The send data output signal has two outputs. The BNC connector, J4, has the unbalanced
output signal, and the DB15 connector has the balanced output signal.
To use the unbalanced output on the BNC connector, SW1 positions 3 and 4 must be
closed (close to PCB).
To use the balanced output on the DB15 connector, SW1 positions 3 and 4 must be open
(away from PCB).
The switch pack is located on the optional G.703 2048 kbit/s connector board.

3.2.4.8 Receive Data (J5)

The receive data input signal has two inputs. The BNC connector, J5, has the unbalanced
input signal, and the DB15 connector has the balanced input signal.
To use the unbalanced input on the BNC connector, SW1 positions 5 and 6 must be
closed (close to PCB).
To use the balanced input on the DB15 connector, SW1 positions 5 and 6 must be open
(away from PCB).
The switch pack is located on the optional G.703 2048 kbit/s connector board.
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SDM-650B Satellite Modem
Rev. 5