Simple FM Radio Receiver Using KA2247

This FM radio receiver circuit processes broadcast frequency modulation by combining a dedicated IC, discrete transistors, and tuned resonant elements. Signals from the 75cm wire antenna are coupled into the front-end stage, where the BF494 NPN transistor operates in conjunction with inductor L1 (wound from 23 SWG wire) and the VC1 trimmer capacitor (2-22pF) to tune into the desired broadcast frequency band. Various resistors (such as 470K, 470, and 6K8) and capacitors (ranging from small values like 10pF, 33pF, 1Kpf, and 103, to larger ones like .04uF, .01uF, and a 100uF/25V electrolytic) configure biasing, coupling, and decoupling across the board to stabilize the RF and audio paths. Once the incoming signal is captured and mixed, it passes through the 5.5 MHz ceramic filter and the 5.5 MHz Intermediate Frequency Transformer (IFT) coil. These components isolate the specific 5.5 MHz IF stage, ensuring precise selectivity. Finally, the signal is routed to the 16-pin KA2247 IC (mounted on a matching socket for secure connection), which handles the internal demodulation and amplification duties necessary to drive an audio output from the Veroboard or custom PCB layout.