This article describes a 10 watt linear amplifier that is capable of delivering over 15 watts into 50 ohms and uses cheap plastic transistors that are used in CB equipment.
If you have difficulty in finding 2SC2078 then lift the lid of your CB set to find a suitable alternative. The bias generator transistor, TR4, is marked TIP31 in the circuit diagram, but here you can use just about anything that will fit. You could even use another 2SC2078, if you had money to burn, but more practical components would be TIP41, TIP3055, MJE3055. All that matters is that it will pass up to 1 Ampere and have the correct base details in a TO220 case.
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