What can one do with a watchman

[Electronic M]

I've got a couple of different watchman's....I keep them mostly for cool factor. If you want to use them as a portable within 1 block of your home you can get a blonder tongue AM60 agile modulator, and cut a tuned dipole according to Shango66's YouTube video (you don't need the antenna analyzer just trim the same percentage of the total length off).

I mostly collect and watch vacuum tube and hybrid (tube and SS) signal chain TVs 1945-75 (I've got a lot of dresser sized consoles including some of the first color sets). I use my watchman to evaluate antenna performance (how far can I transmit with the AM60 cranked) and limit broadcast range (turn it down to try to make sure I'm not recievable by anyone else than the nextdoor neighbors). The blonder tongue boxes require analog composite video and audio from any older source that supplies that or from an HDMI to AV adapter if all you have is HDMI sources.
There are cheaper devices that have to be hard wired to the TV that do the same thing (but those only support CH3-4).

I think the most practical thing if you want to go full portable would be an external DTV converter box(Velcroed to the back). There are thin ones about as big as the big as the back of the set that take 12V from a wall wart (chop the wart end of the cord off the wall wart and tap it the wires from the box into the sets battery. You could probably disconnect the antenna in the set from it's tuner and stick the DTV tuner in series and have that work. IIRC I bought such a tuner a while ago with that idea in mind for my Sony or Philco Safari (those Philco's are big enough that I might be able to hide the board inside) I can't remember where I put it through.

I don't think Sony left any useful empty space inside those (especially the smaller ones) and the only DTV tuners small enough to have a prayer of fitting inside the case are USB tuners... I'm not aware of anything that can host/operate a USB tuner dongle, output analog video or RF that's not bigger than the smaller DTV converter boxes.

I've seen some people use Sony portables as clocks...they set up some computer device to output the time to a second monitor then convert that signal to analog NTSC and feed that to the set.

It's your TV and it's not unobtainably rare so you can do anything to it that makes you happy without bothering anyone.