Liquids and in particular compressed air damage the circuits inside the waveguide.
Cleaning
If visual inspection shows that the R&S SZU or the test port adapters require cleaning, consider the following instructions.
To clean the R&S SZU
Cleaning agents, solvents, acids and bases can damage the labeling or plastic parts of the product. Do not use any liquids for cleaning.
Clean the outside of the R&S SZU I/Q upconverter using a lint-free cloth. You can dampen the cloth with water but keep in mind that the casing is not waterproof.
To clean the waveguide-to-V test port adapter
Proceed as described in the application note 1MA99. The application note provides information on the means you can use and how to clean the thread and the inside of the connector.