You are receiving the 'image' frequency. If the I.F. of your radio is 450 kHz.,
then when you are tuned to 330 kHz the local oscillator is tuned to 780 kHz. ( 780 - 450 = 330 )
However, if your add 450 to 780, you get 1230. Whether you hear 330 kHz or 1230 kHz depends
on the front end selectivity of the tuned circuits ahead of the mixer, which on your radio,
apparently is rather poor. If there are other strong stations in your area you probably will hear
them too on 'Long Wave'.