Poor cable connection

Question

I have a Sony K?-32? Trinitron 16:9 tv I purchased about 8-9 years ago in Hong Kong. The cable connection is a type of RCA connection that is standard in Hong Kong but requires an adaptor to attach a North American threaded fitting. I find my reception from cable is poorer than another TV in the house and I always have to reposition (jiggle) the connection to clear reception (snow?). Even at best reception picture and colours are not as clear and sharp as other TV's in house. Picture from DVD player is much better with some DVD's producing an excellent (although not as good when new, I think)picture.Can the connection be changed to North American type? Is this something I can do at home? Other suggestions to improve reception? Thank you.