Sunday, 13 February 2011

6W RF Power Amplifier with 2SC1971


This RF Power Amplifier taken from FRB Amplifier Kit. It uses 2SC1971 for FM broadband design from 88 to 108 MHz.

Power Amplifier Schematic Circuit

Power Amplifier Printed Circuit Board and Component Layout

Assemble Instructions
RF power amplifier assemble by soldering the components to the pads indicated. Keep coil, resistor, and capacitor leads as short as possible. The coils should be 3/16" to 1/4" above the board and separate turns by one wire diameter. Bend leads to form a little mounting foot for soldering to the circuit board.

Tuning and power output are affected by the distance between the coil turns, you can make fine adjustments by either spreading or compressing the coil slightly. The area surrounding the pads is ground. C2, C3, C4, C6, C7, C8, C9, C10, L2, and R1 are soldered at one end to ground as well as the shield braid on the coax cables. Bolt Q1 to a small heat sink or the chassis with heat sink thermal compound or gray thermal pad underneath the tab. With an input level of 200-500mw, you should see an output of 5-6 watts. Be sure to have a proper dummy load (50 ohms) or tuned antenna connected to the output, doing otherwise will likely destroy the transistor.


  1. whit 1971, you canno't get no more than 3W!
    Whit 1972 you can get about 7Watts