1938 Emerson model BM-206

Although this radio could have been marketed as a five tube radio it uses a very cheap and simple circuit. The basic radio is a three tube 'straight' or TRF set using a 6D6 RF amplifier, 6C6 detector, and 25L6 audio amplifier. Presumably the radio had to be produced and marketed at minimum cost, and using a TRF circuit saved the cost of IF transformers and a converter tube. The ac/dc power supply uses a 25Z5 rectifier, and the electomagnetic speaker field coil is used as choke in the smoothing circuit.

The series filament voltage drops add up to 62v, so a ballast tube, type L55BG, is used to drop a further 55 volts so that the filaments can be powered directly from the normal 117v ac supply.

5 tubes, ac/dc, broadcast band