Complex sentence: RCA had demonstrated a prototype transistor radio as early as 1952 and it is likely that they and the other radio makers were planning transistor radios of their own, but Texas Instruments and Regency were the first to offer a production model.
Split into simpler sentences: RCA had demonstrated a prototype transistor radio as early as 1952 and it is likely that they and the other radio makers were planning transistor radios of their own. But Texas Instruments and Regency were the first to offer a production model.