jeb08

I'm running rg-59 coax from a nuvico dv3 dvr to a monitor 500 ft away. Picture looks great on my 4 inch service monitor, but when I put either a 17" lcd or a 20" crt to it the picture looks bad. Lots of wavy lines, etc. Monitors are ok, have tested both. I have tried both a 10db and 20db gain booster on the line to no avail. Any other options I'm missing here? Thanks.