Right here is a straightforward mission of Easy FM Radio Receiver which is construct round an NPN transistor Q1 BF 494 and 16-pin IC KA2247. Most FM Radio operates on 10.7 MHz IF frequency and makes use of 10.7MHz ceramic filter and 10.7 MHz IFT coil. As these elements (10.7 MHz ceramic filter and 10.7 MHz IFT coil) used on FM radio are arduous to seek out. So, this Easy FM Radio Receiver Utilizing KA2247 is predicated on 5.5 MHz IF frequency and makes use of a 5.5MHz ceramic filter and 5.5 MHz IFT coil that are simply accessible in market and in addition may be taken off from previous Black & white TV set, Audio/Video Transmitter e.t.c. You may also use a SW2 coil used on a SW2 radio receiver set instate a 5.5 MHz IFT coil or you may made your personal.
A circuit diagram given is a straight ahead. First a part of a circuit is construct round an NPN transistor Q1 BF 494. An RF 88-108 MHz amplifier, Oscillator of frequency between 93.5 MHz-113.5MHz and Mixer stage will mixes an incoming frequency (88-108MHz) with an oscillator frequency (93.5 MHz-113.5 MHz) and offers an output IF frequency of 5.5 MHz
Resistor R1 (470K) is related to base of Q1 and +6Volts. Resistor R2 (470) is related to emitter and floor. Capacitor C1 (1Kpf) is related to antenna and a base of an NPN transistor Q1 BF 494. Capacitor C2 (103) is related between base Q1 (BF494) and floor. Capacitor C3 (10pF) is related between an emitter and collector of Q1 BF 494.
Coil L1 (5 turns of 23 SWG wire on 5mm air core) and a trimmer capacitor VC1 (2-22pF) is related in parallel and related to a collector of an NPN transistor Q1 (BF 494) and +6Volts.
Capacitor C4 (33pF) is related to an emitter of Q1 (BF 494) and to a primary pin of 3-pin 5.5 MHz ceramic filter. A 2nd or center pin of 5.5 MHz ceramic filter is grounded. A 3rd pin is related to pin 1 of IC1 KA2247. Pin 2 of IC1 is related to floor with a capacitor C5 (.04uF). Pin 3 is related to floor via a capacitor C6 (.04uF) .Pin 4 is related to floor. Pin 5 and 6 are related to a resistor R3 (6K8). A 5.5MHz IFT coil can be related between pin 5 and 6. Pin 7 isn’t related. Pin 8 is related to 2-pin related via an electrolytic capacitor C7. A capacitor C9 (.01uF) is related to pin 8 and floor. Pin 6 is related to +6 Volts provide and is related to a constructive terminal of electrolytic capacitor C8 100uF/25) and floor.
You need to use a PCB board (given in an article) or it’s possible you’ll use a 5cm* 7cm veroboard on your FM radio receiver. Chances are you’ll use a 75cm lengthy wire on your antenna. Take an IC (16-pin) socket I and place it on a center of your veroboard. Now take all different elements like NPN transistor Q1 BF 494, ceramic capacitors, tunning capacitor VC1, resistors, ceramic filter (5.5MHz ceramic filter), 5.5MHz IFT coil e.t.c.
Subsequent we’ll construct a coil L1 and this may be made by giving 5 turns of 23 SWG wire on 5mm air core. Now additionally place this coil L1 on a veroboard.
Now place an IC KA 2247 on 16-pin and place it on a center of your veroboard. Additionally place a 2-pin connector on a proper aspect of a veroboard of measurement of 5cm*7cm.
Calibration and Adjustment
Subsequent stage is calibration and adjustment. Now join an output terminal of your FM radio to a working mono audio amplifier. Join a speaker to your amplifier.
Take a 6Volts battery and join it to your FM radio. You’ll hear a hissing sound out of your amplifier. Now your FM radio receiver is working. Activate a quantity to center of audio amplifier. Take a plastic screwdriver and gently tune a VC1 (2-22pF) tuning till you catch a stations. So, your FM Radio Receiver is working and prepared for utilizing.*
Q1: NPN transistor BF 494
IC1: KA 2247
Ceramic Filter: 5.5 MHz 3-pin ceramic filter
Tuning capacitor: 2-22pF trimmer
5.5MHz IFT Coil
Capacitors and electrolytic circuit
16-pin IC socket, 5.5 MHz IFT coil, 2-pin connector, 5*7cm verobord, 75cm lengthy wire, 6Volts and many others.