orangetrader wrote:
How do you tell if a cable is RG-59, RG-59U or RG-6?

If there an harm if these cables are used together?

As someone else mentioned, RG-59 is to be used for very short runs. I
wouldn't even bother with RG-59, just use RG-6 everywhere.

You might want to consider signal loss as described he

http://www.swhowto.com/VideoLoss.htm

--
Himanshu