The internal jumpers mounted on the Model 2703’s PC board
(labeled LK1 - LK7) are used to configure the 75 ohm or 120 ohm net- work link parameters. Figure 4 (above) shows the location of the Model 2703’s jumpers on the internal PC board.
The table below shows the factory default jumper settings. Following the table are descriptions for each jumper.
NOTE: One combination of jumper settings is required for 75 ohm operation, and another combination is required for 120 ohm opera- tion. The Model 2703 is factory configured for 75 ohm operation.)
JUMPER SUMMARY TABLE
Jumper | Function | 75 ohm | 120 ohm | Factory Default |
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LK1 | 75 Ohm TX Shield to GND | On | Off | On (connect) |
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LK2 | 75 Ohm RX Shield to GND | Opt.* | Off | Off (disconnect) |
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LK3 | Reserved | Off | Off | Off |
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LK4 | 120 Ohm Shield to GND | Off | Opt. | Off (disconnect) |
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LK5 | Configuration | On | Opt. | On (enabled) |
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LK6 | 75 Ohm Input Impedance | On | Off | } On (75 Ohm) |
LK7 | 75 Ohm Input Impedance | On | Off | |
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*Opt. = optional setting, all others are required for proper operation
Jumper LK1: 75 Ohm Transmit Shield-to-Ground Connection
This setting determines whether the shield of the 75 Ohm (coax) transmit cable is connected to earth ground. This connection must be made when operating in 75 Ohm (unbalanced) mode. Conversely, this connection must not be made when operating in 120 Ohm (balanced) mode.
LK1 | Setting | |
Strap On | 75 | Ohm TX |
Strap Off | 75 | Ohm TX |
Jumper LK2: 75 Ohm Receive Shield-to-Ground Connection
This setting determines whether the shield of the 75 Ohm (coax) receive cable is connected to earth ground. This connection is optional when operating in 75 Ohm (unbalanced) mode. This connection must not be made when operating in 120 Ohm (balanced) mode.
LK2 | Setting | |
Strap On | 75 | Ohm RX |
Strap Off | 75 | Ohm RX |
Jumper LK3: Reserved for Future Use
This strap is reserved for future use and must remain Off.
LK3 | Setting |
Strap On | Not a Valid Setting |
Strap Off | Normal Operation |
Jumper LK4: 120 Ohm Shield-to-Ground Connection
This setting determines whether the shield of the 120 Ohm (modu- lar) cable is connected to earth ground. This connection is optional when operating in 120 Ohm (balanced) mode. This connection must not be made when operating in 75 Ohm (unbalanced) mode.
LK4 | Setting | |
Strap On | 75 | Ohm RX |
Strap Off | 75 | Ohm RX |
Jumper LK5: Configuration Auto-Sense
This setting determines whether the host can automatically sense the configuration of the Applique. The operation of the Applique is not affected by this jumper setting.
LK5 | Setting |
Strap On | |
Strap Off |
9 | 10 |
