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Monday, March 4, 2024

Easy FM Radio Receiver Utilizing KA 2101

Remark errors or corrections discovered for this circuit, and get the possibility to win massive!

Right here is an easy circuit diagram of 88-108 MHz FM Radio Receiver Circuit diagram. The circuit may be very easy and the parts used on this circuit may be simply out there in a market and likewise the price is reasonable additionally.

This circuit works on a well-liked built-in circuit KA 2101.T1 works for RF Amplifier, Oscillator 93-113.5 MHz and mixer. And KA 2101 works for five.5 MHz IF amplifier FM detector and AF preamplifier. A circuit diagram of AF amplifier is just not given right here however you need to use TBA 810 (7 watt), e.t.c.  The TBA 810 (7 watt) will efficiency good and high quality sound output. You might also use 5.5 MHz ceramic filters within the state of 5.5 MHz IFT coils which can remove of tunning IFT coil and distortion.

Circuit Diagram

Circuit Description

Transistor Q1 BF 494 is a excessive frequency transistor and can works right here as RF amplifier, oscillator (5.5MHz larger than 88.00MHz-108MHz) and a mixer. A Coil L1 is a 23 SWG wire wound on 5mm air core with 5 turns. This coil and a 2-22pF trimmer will make an oscillation of frequency 5.5MHz larger than 88.00MHZ and 108.00MHz. A 5.5MHz output sign from emitter of Q1 is handed to a 5.5MHz IF enter stage of IC1 KA2101 utilizing a capacitor C4 (47pF).

Subsequent is IC1 KA 2101 which is 14-pin IC. Pin 1 and pin2 is related to a resistor R4. Pin 1 can be related to floor via a capacitor C5 (0.04uF). A major winding of T1 is related to C* (68pF) in parallel and to a capacitor C6 (33pF).Pin 3 and 4 are grounded. Pin 5 is related to +9 volts battery via a resistor 39 ohms. A capacitor C9 is .04uF which is related to pin 5 of IC2 and floor. Pin 6 can be grounded. Pin 7 can be related to floor via a capacitor C7 (.001uF). Pin8 and pin 14 are related to one another via a capacitor C7. 

Pin 9 and 10 are related to a major winding T1. A capacitor C* (68pF) can be related to major winding of T1. A capacitor C8 (102) is related to floor and pin 7..

Pin 12 is an AF output pin. And an AF sign is related to AF amplifier via connector 1.

PCB Structure


An appropriate vero board of 5cm* 7-1/2cm may be use to construct this mission. Now we are going to want a 14-pin IC socket for IC1. 

Now take a 14 pin IC socket and placed on a center of veroboard and solder it. Now place an IC1 KA2101 on IC socket.

Now take all the remaining parts and solder all by one after the other as given on circuit diagram with 25 watt soldering iron. You’ll want additionally to solder a 9 volts battery clip to attach a 9Volts battery. 5.5 MHz IFT1 coils may be made by winding 23 turns of 37 SWG wire on 8mm ferrite core. C* (68pF) is to attach on a major of 5.5MHz IFT coil.

Calibration and Adjustment

After putting all of the parts and soldering, subsequent it’s a must to do a calibration and adjustment.

Take 9 volts battery and join it to a 9V battery clip. Take a small B&W TV receiver and switch it ON and choose it on VHF vary. Carry an antenna (75 cm lengthy wire) close to to a B&W TV and tune a tunning till you’ll see a plain on raster. As quickly as you’ll see a plain raster on TV this may verify you that RF amplifier, oscillator and mixer comprising transistor Q1 is working.

Subsequent is to verify if IC2 part is working or not. To do that Take AF Amplifier i.e. TBA 810, TBA 820 e.t.c. Now join it to an output of AF amplifier of IC 2 KA 2101. You’ll hear a hissing sound out of your AF amplifier. This may verify that your FM radio receiver is working.

Subsequent step is to tune 5.5MHz IF stage. Take a 5.5 MHz IF sign generator and join its output to a capacitor C4 (47pF). Now take a plastic screw driver tune gently tune IFT coils T1. It is best to hear a tone sound from an amplifier. This may confirms that 5.5MHz utilizing an IC1 KA 2101 part is working. Now disconnect 5.5MHz IF sign generator and reconnect C4 once more. Subsequent tune a VC1 2-22pF trimmer till you’ll hear a station clear and loud. You might also use an antenna 75cm in the event you receiving weak sign. Get pleasure from listening you radio.*


Resistors (all 1/4watt)

R1: 470K

R2: 470


R4: 2K2



C2: .04uF


C4: 47pF

C5: .04uF 



C8: 15pF



Ceramic Filter

X1: 3-pin 5.5MHz ceramic filter


Q1: BF494

IC1: KA 2101


9Volts battery, 9 volts battery clip, 14-pin IC sockets, vero board 5*7/1cm, 2-pin connector T1 (5.5 MHz IFT coil)

Creator Prototype

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