Keep connector interfaces, especially the outer conductors of threaded RF connectors, clean and free of dirt and any other debris. Follow the guidelines to maintain the connectors, and therefore the performance, of your instruments and cables over time.

Contaminants such as metal fibers are sources of uncertainty in measurements. Contaminants can be abrasive and cause damage to the surfaces of matings connectors, which inhibits the repeatability of your measurements. Contaminated connectors pose problems especially for high-frequency, high-precision measurements because they prevent a good impedance match. Therefore, it is important to keep the threaded RF connectors in your test system clean.

Required equipment:

  • Protective eyewear
  • Pure, filtered compressed air or nitrogen
  • Magnifying glass
  • (Non–air dielectric connectors only) Lint-free swabs, such as foam swabs, of appropriate size for the connectors
  • (Non–air dielectric connectors only) Pure (99.5%) isopropyl alcohol
  • (Non–air dielectric connectors only) Toothpick
Notice Do not use swabs or isopropyl alcohol on connectors that have an air dielectric, such as 3.5 mm, 2.92 mm, or 1.85 mm connectors. Refer to front panel and pinout documentation to confirm the connector types for your instrument. If using isopropyl alcohol to clean the appropriate connector types, do so in a well ventilated area.

Complete as many of the following steps as you need to clean threaded RF connectors. Complete only the steps that are appropriate for the type of connector you are cleaning:

  1. After putting on protective eyewear, blow out any loose debris from the connector with compressed air or nitrogen by blowing across the connector face.
    Tip Do not blow directly into the connector as this can lodge any debris more firmly. Blowing across the connector is the safest method for cleaning connectors that use air dielectric.
  2. (Non–air dielectric connectors only) Examine the connector with a magnifying glass to check for debris. If you still notice debris, try removing it with a lint-free, foam-tipped swab by gently moving the foam swab around the center conductor.
    Notice Follow these guidelines when cleaning connectors with a foam swab:
    • Always clean the connector in a circular motion around the center pin, not across the pin. Never put lateral pressure on the center pin of a connector.
    • Apply as little pressure as necessary. Applying too much pressure can embed debris deeper into the connector.
    Notice NI does not recommend using cotton swabs to clean threaded RF connectors. Cotton fibers can become lodged in the connector, causing damage or measurement errors.
  3. (Non–air dielectric connectors only) Examine the connector with a magnifying glass again. If you still notice debris, barely dampen another foam swab with isopropyl alcohol (do not saturate it) and attempt to clean the connector in the same manner as with the first swab.
    Notice Do not apply isopropyl alcohol directly to a connector.
  4. Verify that no foam or other foreign material remains in the connector.
  5. (Non–air dielectric connectors only) If the connector is still contaminated, use a very small toothpick with a small amount of isopropyl alcohol applied. Use the magnifying glass when using the toothpick.
    Notice Use extreme care to avoid damaging the connector with the toothpick.
  6. If desired, use the compressed air or nitrogen to remove any foreign particles and to dry the connector if you used isopropyl alcohol.

After cleaning, verify that the center pin has not been bent or damaged. Also verify that the collets of the mating connector are neither bent nor damaged. When connectors are not in use, keep them covered with the dust cap for included with your instrument for the connector.

If you are not successful in cleaning the connector after completing as many steps of this procedure as are appropriate for the connector type, remove the item from service and label it accordingly.