Complex sentence: The ABC started a second Brisbane station on 7 January 1938 using the callsign 4QR-the new station carried national programming--the forerunner of Radio National--while 4QG aired mainly local content.
Split into simpler sentences: The ABC started a second Brisbane station on 7 January 1938, using the callsign 4QR. The new station carried national programming--the forerunner of Radio National--while 4QG aired mainly local content.