I have an old Philips magnovox tube tv from the 90s that I bought off eBay to hook up to a Roku player. The only problem is that it doesn't have any av input on the actual tv to hook up the Roku express like my old similar model tv had. It only has a cable input on the back of the tv. I bought a bnc converter and a cable like you would use on a tv to a VCR plus a small bnc to cable screw that allows it to go in to the bnc parts, this model of tv, a smart series (not a smart tv. That is just the model name on the front of the TV: Philips magnovox smart series). So can this work? And can it work with the bnc converter or do I need to purchase another tool to help it work?
It doesnt make much sense to buy a very old TV with only a coaxial cable connector to hook your Roku (model # and firmware version unknown) up to.
I cannot begin to understand the logic of this decision.
That issue aside, without knowing what Roku model you have and assuming it has RCA/composite output, you'd need an RCA to RF converter/modulator:
https://www.amazon.com/s?k=rca+to+RF+modulator&ref=nb_sb_noss