It is important to keep an eye on the quality of rg59 that you are using. There is cable available which cant carry video signal due to the poor copper coating on the centre core. Testing with a pulse bar generator and scope (the old way is best) If you have a scope look at the video signal you have coming from the camera and if terminated at 75 ohms at the scope end you will exoect to stt your 1 volt p to p. But look at the sync pulse which should have nice square edges and be the lower .3 of a volt peak to peak.
