Sears Silvertone Color

[old_tv_nut]

(Jeffhs' post is too long to quote )- but regarding the question of "marketing agreements" - no, that was not a marketing agreement, but the companies with small design staff were buying the RCA patent license package. This gave them access to the RCA chassis design as well as the basic technology. They had varying success with copying the RCA design, especially in circuits where stray coupling could cause a problem - same schematic but different layout could give different results.
Large companies, Zenith in particular, fought the RCA licensing for years, taking it to higher and higher courts until RCA was forced to unbundle implementation patents from the basic technology patents. Meanwhile, these larger companies spent money on finding ways to build receivers that didn't require the RCA implementation patents.

I knew someone who went from Motorola to Admiral, where they basically licensed the RCA design. He learned a lesson from that and went on to become a patent lawyer.