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When transistor radios first became available, transistors were very expensive, and even a modest radio cost more than a week's wages at the time. Meanwhile, the pop music explosion created a market for budget priced receivers that young people could afford. This resulted in designs like this Coronet. It uses a two germanium transistor tuned radio frequency (TRF) circuit which is reflexed so that the RF amplifier stage also operates as audio amplifier. The AF signal is transformer coupled to the output stage. The single output transistor is biased in Class A - unusual in transistor radios - and feeds the speaker via a transformer. Power comes from a standard 9v PP3 battery. This design is very unusual in that it is capable of driving a loudspeaker without using regeneration - the usual method used to squeeze the maximum gain from simple circuits like this. Even the famed Sinclair Micromatic could only drive an earphone, and the Sinclair design used high gain silicon transistors together with regeneration. This receiver is sensitive enough to pick up BBC Radio 5 live together with several local stations during the day. After dark, when medium wave propagation really perks up, I have heard many foreign stations from as far away as eastern Europe - without any external aerial.
I've left the pic of the internals large so that key features are clearly visible. Starting down from the tuning capacitor, the round object with the blue spot is the RF transformer that feeds the diode detector. The RF transistor is visible just above. The next transformer - with the blue bobbin - is the interstage coupling transformer. The last transformer, just to the right of the speaker magnet, is the output transformer. The audio amplifier transistor can be seen just below the output transformer.
