Got a Sharp QT-270 boombox for $7.50.

It has:
-tone control
-one cassette deck
-am/fm radio
-volume control
-built in microphone

The Sharp QT-270 appears to be from the late 80's or early 90's.

Does anyone know which year the Sharp QT-270 was released in?

i would guess around 82.

no no,its at least 86-88,these came out a few years after the GFs faded out..GFs ran from 79 With the GF8080,9090,9191,and stated to faze out at latest 85 with the GF-A1 ect,i think the QTs started in around 85/86...then it was all downhill from there..