Some radios have a model number. You could start there.

If not, a chassis number, some of the transistor numbers, etc. might help. A photo might stir some memories. If it's old, it probably boasts the number of transistors somewhere on its case. Often the color of the case is a clue, as well as the country in which it was sold. Can we assume that it is AM-only (535 - 1605 kHz)? Or is it multiband (LW, MW, and SW)? Or even FM???

If you hear a hiss, the radio may be at least partially functional. Certainly the 220 is put through a transformer and rectified to a low voltage. The most likely failure is that the radio is tuned in between stations and the cord which moves the tuning capacitor is broken, leaving it forever on no station. Does the volume potentiometer scratch when it is rotated?