What is the recommended procedure for cleaning RF connectors before mating?

The recommended procedure for cleaning RF connectors before mating removes contamination (dust, metal particles, skin oils, flux residue from soldering, and oxidation) that can degrade the RF performance (increasing return loss, insertion loss, and PIM) and potentially damage the connector interface. The procedure is: step 1, visual inspection (examine the connector under magnification (10-20×) for: debris, corrosion, bent or damaged center pin, damaged threads, and deformed dielectric); step 2, dry cleaning (use clean, dry, compressed air or nitrogen to blow out loose particles from the connector interface; direct the air into the connector opening from a shallow angle to avoid pushing debris further inside); step 3, wet cleaning (apply a small amount of isopropyl alcohol (IPA, 99%+ purity) to a precision lint-free swab (Chemtronics Coventry, ITW Texwipe); gently swab the center pin, dielectric surface, and inner wall of the outer conductor; rotate the swab to lift contamination; use a fresh swab for each pass (do not re-use contaminated swabs)); step 4, drying (allow the IPA to evaporate completely (approximately 10-30 seconds at room temperature); alternately, blow dry with clean compressed air); step 5, re-inspection (re-examine under magnification to verify all contamination has been removed; if contamination remains: repeat steps 3-4 with a fresh swab); and step 6, mate immediately or cap (mate the cleaned connector promptly or install a protective cap to prevent re-contamination).