The radio cartridges were great for the era they could record a days worth of promos.
The Dj would throw in a couple hundred cartridges into the machine and walk away.
They still used live Djs by me though and they would walk away and the record would stick for 4 or five minutes sometimes.
Anyway I found this old article in a google search and thought I would add my 2 cents.
Have a good day. []
Mike