Bought an HDTV receiver box today and TV modulator to feed vintage TV sets

[wa2ise]

That's nice you say but what's the vintage TV connection?

Well, it has an Svideo output jack that I used an Svideo cable with the luma signal peeled off feeding the TV modulator to feed my 1950 Admiral bakelite TV set. Rason for that is that I can feed that TV a B&W signal without the chroma subcarrier, which in a B&W TV this old will show as a crawling checkerboard pattern. So I can watch live broadcasts (like a football game) on the B&W set as if it were a B&W broadcast before color TV was established. And the HDTV box, a Samsung, has HD rate video outputs at the same time it makes the Svideo regular TV signal.

A satellite TV box, or a digital cable box with an Svideo output jack will also let you do the above. So this is what you'll have to do once NTSC terrestrial broadcasts stop in a few years.