Over time with use BNC connectors on test equipment will attract contaminants . Since BNC is usually used for relatively high frequencies, I suspect that contaminants will have negatively affect performance of the system.

I also suspect that type of cleaning agent can affect performance of the system.

So my question is: How to properly clean a BNC connector without affecting its performance in a negative way?

  • \$\begingroup\$ I'm thinking of editing this question to be a bit more general and cover other types of RF connectors and then make it community wiki. Would that be a good idea? \$\endgroup\$ – AndrejaKo Sep 2 '13 at 19:01
  • \$\begingroup\$ Good RF connectors are silver or gold plated. The scopes I've used had neither. \$\endgroup\$ – jippie Sep 2 '13 at 19:18
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    \$\begingroup\$ I've used 20-year-old scopes that have never ben cleaned, with no problems. What are you doing with your scope, that it's building up"contaminants"? \$\endgroup\$ – The Photon Sep 2 '13 at 19:18
  • \$\begingroup\$ Which makes me wonder: A silver plated RF connector ... what happens when I use regular silver polish? (Apart from getting the connector shining). \$\endgroup\$ – jippie Sep 2 '13 at 19:19
  • \$\begingroup\$ @The Photon Well I didn't have anything that a bit of compressed air didn't fix (just some dust, lesson learned, caps are now always on connectors when probes aren't), but that made me research the issue and I found very little information about maintenance steps. For example there was an Agilent document that basically said same thing as the deleted answer: Use isopropanol on it. I researched a bit more and dug up few more sources, but nothing too definitive, so I decided to ask here and see the responses. \$\endgroup\$ – AndrejaKo Sep 2 '13 at 19:26

Stick to the manual, which will likely tell you: No solvents, just mild detergent (i.e. a bit of dish soap and water). Use only if really necessary, and apply just a little using q-tips. If dry q-tips work, even better...

This is not really specific to RF connectors, just good guidance for any electronic device.

Inside the BNCs, pure alcohol might also work, but sometimes, alcohol will act aggressive towards rubber (and it will certainly do harm to some plastics on the front panel, let alone the markings). Also, alcohol will likely just spread out any dirt and leave it in the tiny spots once it dries. I tend to use alcohol only when I can wipe it before it evaporates, or as a last resort when detergent or purified water won't do the trick.

Back in the days of analog tapes and cassettes, alcohol was recommended for the tape heads and the capstan, but you were cautioned to not use it on any rubber (pinch roller!).


I've used Caig DeoxIT on all kinds of connectors over the years. It hasn't failed me yet. Classic would be fine for most BNC connectors, unless they're gold plated, in which case, DeoxIT Gold would be a better choice.


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