What's that thing called?

[devious_101]

I recently discovered that there is a TV antenna mounted on the roof of my apt building. I checked around to find out where it's coming in and I have found it behind a switch plate for my cable tv input (i have cable internet). The antenna cable is a really old type of wire that you would screw down to the back of your old TV from back in the day. Where can I find an adapter to make it into an F-Type/Coaxial connection? Any help would be appreciated!

[wje]

That sounds like 300 ohm balanced line, although I'm rather surprised that would be run thru a wall.
You need a 300 ohm balanced to 75 ohm unbalanced (that's your F connector) balun. Try Radio Shack.

[bairdjc]

wow my condo had these when I moved in - it was built in 1972 and they ran antenna leads to each unit from a main antenna (which is now gone obv). When I painted the place I just cut off the wires, stuffed them inside the low volt "box" and put a blank plate on top

[Michael P]

Even when those MATV systems were new, the reception was usually crappy, especially on UHF channels. Even though the output was 300 ohm, the distribution system usually was coax. If you can open up the wall box you'll see that the 300 ohm terminal was actually a transformer from a 75 ohm system. UHF does not travel as far on coax as VHF, and most of these systems were built before modern RF distribution techniques were developed.

Since they were "free" nobody bothered to maintain them. The antennas for these systems usually had broken wires and/or broken elements.