HP 83491A User Manual page 54

Reference
Cleaning Connections for Accurate Measurements
Making Connections
• Align connectors carefully
• Make preliminary connection lightly
• To tighten, turn connector nut only
• Do not apply bending force to connection
• Do not overtighten preliminary connection
• Do not twist or screw in connectors
• Do not tighten past the "break" point of the torque wrench
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