Here's what I'd do:
Find a local library that has a decent periodical section. University libraries are usually
much better than public libraries for this, at least in my experience. If at all possible, you want a library that still has old periodicals in printed form (typically in large bound volumes), not just microfilm/microfiche, especially when browsing for old ads (which are often in color and won't be reproduced well on B&W copy film used for microfilm)
Either bring a digital camera or some money for the copy machine.
(Or, you can go all out and bring a laptop computer and scanner, but that's only feasible in some situations, and many scanners are really too loud for library use anyway)
Browse the racks for
Life magazine for late 1946. Not only because that TV wasn't introduced until late in the year, but because this would also be during the Christmas shopping season.
Now flip through until you find an RCA ad for the 630TS. In the meantime, marvel at all the rest that 1946 had to offer in
Life magazine. If you fail to find such an ad in the first bound volume you grabbed, pull the next volume and continue through 1947 until you find one. I'm sure RCA had an ad for the 630TS
somewhere in
Life magazine.
Once you've found one, take a nice high-res photo of the ad or copy it on the library photocopier. If you go with the latter, though, keep in mind that
Life magazine has an oversize format, so full-page ads are hard to copy unless the library has a large-format copier.
See, wasn't that fun?
I dunno about the rest of you, but I think it's a lot of fun to browse the periodical stacks at a decent (university) library. I usually go with stuff from the 1940's through 60's.
Life is great for this, along with
Consumer Reports and similar magazines. Also
Popular Science and its ilk, though you aren't as likely to see a lot of more specialized hobbyist magazines (such as electronics-related magazines) at most libraries.