FM Broadcast 55W Push-Pull RF Amplifier

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This prototype rf amplifier uses two 2SC2640 VHF power transistor wired in push-pull configuration. The 50 ohm impedance of the input is transformed to lower impedance by the 4:1 broadband coaxial cable transformer providing a close match to the base of the two transistor. To operate in class C, the base of the transistor must be at ground potential so the secondary winding of the 4:1 coaxial transformer is grounded at the center position( null). The impedance of both collectors are transformed by the combination of inductors L1 , L2 and the 120pF capacitor and further transformed by the 1:1 coaxial balun.

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