Best RF Connection to old TV

[vol.2]

I have an old late 70s Sony TV which only has and Antenna input on the rear.

It has a switch to go between the pole antenna and an "external antenna."

I have been using an RF modulator to hook up to the back of the TV, but the TV only has screw terminals for the external antenna, not a Coaxial input like later TVs I own.

I have a few questions/issues about this hookup

1) My RF modulator has a coaxial output and the TV does not. I have been using a "75 ohm to 300 ohm adapter" on the end of a coaxial cable to break out the coax to spade terminals and then screw that onto the TV

I have no idea if this is correct, I just know that it needs to be wires or some kind of terminal connectors to even hookup to the back of the TV

Is this correct? In other words, is the Sony TV expecting 300 ohms at the antenna terminal, and therefor it's correct that I'm using this matching transformer for that purpose?

2) I am getting some occasional interference in the RF signal. My instinct is that there are so many devices now that put RF into the airwaves that I'm getting stray waves from wireless connections and smart phones and stuff like that. I live in a city, so this seems like a plausible answer.

Is there some way to mitigate external interference to my TV from the RF modulator?

I am somewhat experienced in repairing old TVs, but I lack RF experience. I've already been in this thing and had to replace all the caps and many other parts just to get it working correctly again, so I'm totally fine going inside and working on it.

My thought was that I could maybe bypass the external antenna connector and go straight to the VHF tuner with an RCA style coax cable (which it seems to use) directly into the tuners. If I did this, what considerations should I have in regards to impedance matching? Would this help at all?

Thanks