Hello, I am working with an instrument which outputs 0-5mV, and that signal has to reach a sensing device 35' away. I am concerned with noise, and I don't think shielded cable will work well enough. So I am considering using coax cable. But I don't understand coax. There are numerous "RG" ratings and ohm ratings. Suppose I used RG62 with 50 ohm terminations. What do I need to know about the termination and the cables in order to properly use this? What's the difference between RG62 and say RG59? What are the ohm ratings referring to, and what terminations would I need for an ohm rating of 50? Is there a 50 ohm load which gets put somewhere in the system? Clearly I have many questions. Any help would be appreciated.

thanks