What kind of port does it have?
I doubt it is HD if it doesn't have a connection capable of outputting it!
But, if what you want to do is go from an HDMI to a composite an RF modulator is the device you need.
Something like this
https://www.amazon.com/Belkin-F8V3063-RF-Modulator/dp/B00076FVP6
Granted that is half the price of a new HDTV...