I have bought two different RCA receivers in the past week and both receivers have the same problem. Or at least the same problem is occurring. A channel will be doing fine, then all of a sudden the colors on the tv will slightly dim, then brighten, dim, then brighten. Very lightly, you have to really be watching to notice it. It is bugging me bad! Can anyone help? Could it be something in the coax? Please let me know. Thanks