Hi Alan, rather than damp in the Radarama itself, I would suspect damp in the co-ax which will act as a wick, I've had water come in and right down co-ax in the past, rather than use sel-amalgamating tape now, I fill the connectors up with electricians' silicone grease (NOT silicone sealer) to the extent that it squeezes out when connectors screwed together. Water and damp cannot penetrate. Once a surface has this grease on it adhesive/self-amalgamating tape will not take. I've always found it virtually impossible to get an absolute seal with SA tape, which will also crack and perish in a few months. Self adhesive heat shrink is more effective.