Monoprice has RCA cables in 6", 1', 1.5', 2', and 3' lengths. If you needed to go 80 feet and your only option was 100', I'd support your effort to not have 20' of slack wound up somewhere.

These colorful cables are known as RCA cables, which is short for Radio Corporation of America, the company that introduced the design back in the 1940s when they were used to connect phonographs ...

75 ohm. Get RG-58 or RG6 coaxial cable, and then get a set of strippers and an F or S fitting crimper. RCA fittings are about $2 each, and do not require soldering. RG-58 is 50 ohm. RG-6 is 75.