60W Transistored Power Amplifier Circuit Diagram

This is the circuit diagram of 60W transistored power amplifier. This circuit was designed and built during the 80s. From then it works without problem. It does not present a particular construction problem, apart from the known: the attention to the supplied power source, choosing suitable heatsinks and good matching of the driver transistors. The diodes D3..5 should be placed on the heatsinks of power transistors to have thermal coupling with the output transistors.

 60W Transistored Power Amplifier Circuit Diagram

With the trimmer R15, we regulate the voltage at the output of the amplifier [with long work hours and little heat stabilized]. With the trimmer TR1, we can adjust the bias current of the amplifier at 50 to 100 mA. The bias current can be measured if you measure the voltage drop at the ends of the resistors R36 and R37, for the voltage that are given in the circuit, the current is approximately 75 mA. The voltage indicated in above diagram can be different, but may have a tolerance of about +/- 10%.

Parts List

R1 = 1.8K ohm	R25 = 8.2K ohm	D1,D2 = 24V/1W Zener	C1 = 4.7uF/25V
R2 = 220K ohm	R26 = 27K ohm	D3….9 = 1N4002	C2 = 470pF
R3 = 27K ohm	R27 = 820 ohm	T1-2 = BC550C	C3-4 = 100uF/63V
R4,R10,R11,R17 = 3.3K ohm	R28 = 3.3K ohm	T3,T4 = BC560C	C5 = 68pF
R5,R9,R12,R16 = 100 ohm	R29 = 100 ohm	T5,T13 = BD530	C6,C10 = 330pF
R6 = 18K ohm	R31,R39 = 180 ohm	T6,T8 = BC414C	C7 = 22pF
R7,R13 = 3.9K ohm	R32,R38 = 6.8K ohm	?9 = BC416C	C8 = 220uF/16V
R14 = 10K ohm	R33,R34 = 1.2K ohm	T7,T10 = BD529	C9 = 100nF 100V
R15 = 22K ohm Trimmer	R35 = 82 ohm /1W	T11 = BD591	C11,C12 = 10pF
R18,R23 = 330 ohm	R36,R37 = 0.33 ohm / 5W	T14 = BD592	C13,R15 = 47uF/63V
R19,R21,R22 = 15K ohm	R40,R41 = 10 ohm / 2W	T12 = 2N5630	C16,R17 = 100nF/100V
R20 = 12K ohm	R42 = 180 ohm/5W	T15 = 2N6030	C18,R19 = 100nF/100V
R24,R30 = 82 ohm	TR1 = 4.7K ohm Trimmer