I have an R-2000 and 830S by Kenwood.
Both radios do not receive when plugging in coax connectors into the
S0-239 receptacles. I've eliminated the cables as the problem. I
believe it is possible salt air corrosion internally in both radios.
The signals and noise drop out completely when screwing in the PL-259
connectors all the way in and tightening them down. When they are only
half way plugged in I get normal reception when wiggling the cable but
they are not screwed in completely and not making a good electrical
connection. I lived on the beach and sometimes would open the windows
for ocean breezes. The 830S was right next to the open window and the
R-2000 was sitting on a night table a few feet away from the open
windows. I've eliminated the cables themselves and suspect salt air
corrosion internally in both radios.

Is there a spray contact/solder connection cleaner available on the
market that might help solve this problem?

Recently I had the S0-239 replaced onthe 830S and still have the same
reception problem. The noise and signals drop out completely in both
radios when screwing in the coax connectors (PL-259) completely.

Thanks for the help!

73's
K4JDP-John