Moisture in Coax...

[KG4CGC]

Take down the coax and test it for a short.
Just to be on the safe side, wack off about 4 to 6 inches and put a new connector on it. There is silicone sealer tape that sticks to itself but has no adhesive. This stuff is awesome but can get pricey if you don't shop around. Hardware stores have it and sometime the Evil Empire carries it. Try RS if all else fails.
Cushcraft included silicon goop with some of their antenna kits. 10 years later and that stuff is still fresh like the day I applied it. The goop goes on the threads after you has the coax almost all threaded up on the SO-239. Then you finish screwing it on a couple or three turns and you're sealed from moisture and corrosion on that front.
I've recently become a fan of heavy duty all weather crimp on F connectors for 75 ohm coax. RG-6Q is my choice for scanner and stuff of that nature. It is also more compatible with small antenna amplifiers that you can buy just about anywhere for cheap.