Complex sentence: For the first 19 months, there were no live disc jockeys; instead, there were "vignettes" done by actors, informing listeners of the time, where the current hour was a part of the dialog.
Split into simpler sentences: For the first 19 months, there were no live disc jockeys. Instead, there were "vignettes" done by actors, informing listeners of the time, where the current hour was a part of the dialog.