Complex sentence: The station was an affiliate of the Don Lee Network, and also carried CBS network broadcasts until 1936, when they collaborated with NBC; they remained a NBC affiliate until NBC ceased hourly newscasts in the 1990's.
Split into simpler sentences: The station was an affiliate of the Don Lee Network, and also carried CBS network broadcasts until 1936, when they collaborated with NBC. They remained a NBC affiliate until NBC ceased hourly newscasts in the 1990's.