Precision connectors are part of the measurement system. Damage or poor practice causes repeatability problems that no calibration can fix.

Basic rules
1. Inspect before connecting. Look for bent or recessed centre pins, debris and plating damage. A magnifier helps; for precision work, check pin depth with a connector gauge.
2. Clean properly. Use compressed air (oil-free) first, then lint-free swabs with isopropyl alcohol on threads and dielectric where the manufacturer allows. Do not let solvent soak into dielectric beads.
3. Align straight. Mate connectors on-axis, turn only the nut, never rotate the body of the device or cable. Rotating the centre conductors against each other wears them quickly.
4. Torque correctly. Use the specified torque wrench for the connector type. Over-torque damages threads and interfaces; under-torque causes poor repeatability. Hold the wrench at the end of the handle and stop when it breaks.
5. Use connector savers (adapters) on instrument ports. Replace the saver when worn, not the instrument port.
6. Mind mating compatibility. SMA, 3.5 mm and 2.92 mm are mechanically compatible, but mating SMA (looser tolerances, often with dielectric to the face) to precision connectors risks damage if the SMA is out of specification. Gauge cheap SMA parts before connecting them to precision ports. 2.4 mm and 1.85 mm are mutually compatible, but not compatible with the SMA family.
7. Cap unused ports and store cables without tight bends.

Signs of trouble
- S11 varying when you flex or re-mate a connection.
- Verification standards that no longer measure as before.
- Visible scratches or a shiny ring on the outer conductor face.

A connector care routine costs a few minutes per day and saves expensive port repairs.