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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 Shield-to-GND Connection Made
Strap Off 75 Ohm TX Shield-to-GND Connection Broken
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 Shield-to-GND Connection Made
Strap Off 75 Ohm RX Shield-to-GND Connection Broken
LK3: DIP Switch S1-1 Enable
This strap is reserved for future use and must remain Of
f.
LK3 Setting
Strap On Not a Valid Setting
Strap Off Normal Setting
LK4: 120 Ohm Shield-to-Ground Connection
This setting determines whether the shield of the 120 Ohm
(modular) 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 Shield-to-GND Connection Made
Strap Off 75 Ohm RX Shield-to-GND Connection Broken
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
operation. The Model 2703 is factory configured for 75 ohm
operation.)
7 8
JUMPER SUMMARY TABLE
Jumper Function 75 ohm 120 ohm Factory Default
LK1 75 Ohm TX Shield to GND On Off On (connect)
LK2 75 Ohm RX Shield to GND Opt.* Off Off (disconnect)
LK3
Reserved
Off
LK4 120 Ohm Shield to GND Off Opt. Off (disconnect)
LK5 Configuration Auto-Sense On Opt. On (enabled)
LK6 75 Ohm Input Impedance On Off
LK7 75 Ohm Input Impedance On Off
}
On (75 Ohm)
*Opt. = optional setting, all others are required for proper operation
Figure 5. Jumper locations on Model 2703 PC board.
LK6
LK7
LK5
LK3
LK2
LK4
LK1