Very soon, we are going to see ads for digital converters that make your analog TV set compliant with the new standards (here's the site set up by the government with info for consumers). The ad above is from 1935 and pushes then-new UHF converters (via Modern Mechanix).
If you are into history of technology, these two books by Albert Abramson are indispensable:
History of Television, 1880-1941
History of Television, 1942 to 2000
Earlier:
Flashback: Advertising When TV Was New
