¡Gracias, todos! Yes, the MK-484 is a single chip TRF radio. It has several RF stages, AVC, and detector all enclosed in a case no bigger than a transistor. Just a handful of other passive components and you've got a radio that works with earphones. It likes to work at a little less than 1.5 volts. Add a couple of transistors or an amp chip like an LM-386 and you can work a small speaker. I made a pocket radio with an MK-484 last year:
http://theradioboard.com/rb/viewtopi...577&highlight=