Chapter 1 Introduction
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National Instruments Corporation 1-3 BNC-2140 User Manual
If your application requires that you use a prepolarized microphone with a
microphone preamplifier, contact Brüel and Kjær.
Custom Cabling
National Instruments offers cables of different lengths for the BNC-2140
accessory to connect your analog I/O signals to the DSA devices. National
Instruments recommends that you not develop your own cabling solution
due to the high-density connector that is required and the necessity to
maintain high signal integrity.
If your application requires you to develop your own cable, use the
following guidelines:
• Use shielded twisted-pair wires for each differential analog input or
output channel pair. Since the signals are differential, using this type of
wire yields the best results.
• When connecting the cable shields, be sure to connect the analog input
grounds to the AIGND pins and the analog output grounds to the
AOGND pins. For a connector pinout description refer to Tab le3-2 in
Chapter3, Signal Connections.
• You can create your own accessories by using a 68-pin very high
density cable interconnect (VHDCI) receptacle header using AMP
68-position right-angle PWB receptacle header 787254-1.
• Recommended manufacturer part numbers for the 68-pin mating
connector (for the cable assembly) are as follows:
– AMP 68-position cable straight plug, part number 787131-3
– AMP 68-position backshell with jackscrews, part number
787191-1
UM.book Page 3 Tuesday, July 14, 1998 10:37 AM