T311S and R34S are AM/FM radio receiver products made by HH SCOTT in the 70’s which is capable of producing up to 25 Watts of power at 8 Ohm loads.
The supply voltage they use for this power amplifier circuit is 24VDC symmetrically.
The Power Transistor are uses medium power transistors with TO-220 packaging similar to the legend transistor in Indonesia: TIP31.
Here is a schematic redraw of the Power Amplifier section of this SCOTT HH radio receiver:
Q316 and Q317 serve as preamp differential amplifiers.
A zener diode in the emitter of the preamp transistor acts as a voltage stabilizer so that it is maintaining the voltage ensure to 11 Volts.
Q313 is a transistor that acts as a voltage amplifier for the incoming signal from the Q316 output.
Meanwhile, the transistor Q314 serves as a determinant of the idle current in the final power transistor.
This circuit also has an OCP feature to limit the overcurrent of the final output transistors by installing transistors Q309 and Q310.
The power circuit is quite simple, but there have been additional features of servo bias and Over Current Protection in this circuit.
Transistor power including transistors with low power.
According to Datasheets, it is capable of up to 25 Watts ( DATASHEETS ).
The following are the picture of kinds active components that they use in this power amplifier:
