Ikegami 9 inch color CRT production monitor, no picture

[Chip Chester]

An RF to SDI converter would be a tuner. And yes, you'll need one if you're trying to view broadcast television.
If it's this one, https://www.bhphotovideo.com/c/produ...ield_Rack.html
it's a standard def monitor with selectable aspect ratios. SDI is SD only. Don't know if they made other input modules for it.
If you look up the full model number (from the back perhaps) you can determine the real specs, and feed it with the proper input signal to see if it works.