Cool! thanks for posting... could a second tuned circuit replace the 1.8 k resistor to make it a "2 dial" set?
Does Australia *actually* have AM stations that broadcast with decent fidelity? Most stations in the US limit the audio response to 8 kHz with many only going to 5 kHz... On top of that, a lot of compression/clipping is usually employed... the resulting sound quality is pretty awful!
jr