Virtually all the last generation of all-American five plastic cased table radios had printed circuit boards along with a piece of glued on aluminum foil above the 50C5 and 35W4 on the underside of the case top. Components around those two tubes always had a baked or burnt look as well as the board around them.
. Metal chassis were long gone; the board mounted on slots in side of cab. They may not even have wasted a good ferrite core on the antenna coil, just a printed circuit wire loop on the inside of a quasi cardboard cab. back.
Popping that out for service ( no screws, just plastic tabs) generally cracked the cabinet if it was heat hardened.
Even Dynaco, a well respected audio outfit made audio amps and preamps with tube printed circuit boards, as well as Heath Co. for audio, metering and RF applications.
Detroit went through this phase too until the Japanese produced better quality cars. Doors and hoods with 1/4 gaps, no alignment an routine breaks in every component. In the case of electronics of course, the American manufacturers never recovered. Early auto imports had easily rusting bodies, but they quickly realized that Americans generally used salt in winter and corrected that problem.
