Larry K7SV k7sv at comcast.net
Fri Oct 21 21:55:00 EDT 2016

I’m still using two six position coaxial switches in the shack. Both are rotary with 7 connectors on the back. One is a B&W Protax model 375 and the other is a Waters model 335. The design of the two appears to be identical.

Both switches have been showing signs of dirty contacts, especially the 335. There’s no way to open these switches up to expose the switch contacts. I finally determined that if one removes the three screws that hold the face plate, contact cleaner could be sprayed in the holes for the screws. Ultimately I sprayed enough contact cleaner in one of the holes so I could hear is slushing around inside. Then as I shook the unit in various directions I kept turning the switch. I did this enough to ensure that contact cleaner was on all sets of contacts as I rotated the switch. 

Once I figured I’d done that enough, I turned the switch so the front with the three holes was facing down and shook it up and down to remove the excess contact cleaner. I used CRC QD Contact Cleaner which is quick drying and leaves no residue. I picked the product up at Lowes home improvement. 

The switches are back in place and each click of both switches results in an immediate solid contact. 

73 de Lar K7SV

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