if you look at the spectrum outside of catv, youll find the
most possible cause of the problem at a certain frequency. for example, cb
radios run at around 26 mhz. if you get a wavetek ms 1300,1400,1450, or above
signal level meter, youll find an ingress testing capability on it that will
show where your problems are at on the spectrum. then all you do is start
troubleshooting using the meter untill you get your drop/plant within specs.