You have seen 3 Sony KDI 40V3000 TVs with this same problem? What did Sony say? Do you have an amplifier in the system that might be overdriving the tuner? What is the signal strength of the digital channels on the coax at the back of the TV?
Experience is what you get when you don't get what you want. Any wire cut to length will be too short. I must be a near GENIUS. All my teachers told me I was at the very PEAK of the bell curve!