Using the CD2003GP (TA2003) chip, you can assemble a simple and fairly good-sounding FM radio receiver. In this article I will tell you how to assemble it with electronic tuning using varicaps.
Coil L2 is a local oscillator coil. L1 is located in the input circuit. These coils are wound with a wire with a diameter of 0.6mm on a mandrel with a diameter of 5mm. L1 contains 4 turns and L2 contains three turns of wire. After assembly, you must change the arrangement of the turns of L2 so that the desired FM radio stations are received .
Crystal filter at 10.7 MHz with a red dot. Discriminator also at 10.7 MHz
The main difficulty is getting varicaps. I took varicaps from an old TV on a kinescope. The brand of varicap is unknown to me, the inscription L2 is on the body. You can take other varicaps, you just need to adjust the local oscillator coil by moving and pushing apart the turns of the coil.
Instead of tuning on varicaps, you can use a variable capacitor. Then resistors can be eliminated from the circuit. Connect two variable capacitors to the coils L1-L2. Typically, a single variable capacitor contains two variable capacitors with a capacity of approximately 3-40 pF
