Aircraft radio receiver

Communications between commercial aircraft and the ground can be interesting, entertaining, and even unsettling at times. However, radio equipment capable of receiving frequencies ranging from approximately 220 MHz to 400 MHz (commonly used in aircraft, both military and commercial) is not readily available. Furthermore, scanners can be complex, bulky, and expensive. With such an easily constructed circuit, anyone can enjoy listening to these conversations.

Listening to aircraft/aviation communications is fascinating, and this electronic circuit offers a viable alternative to the very expensive commercial radio scanners on the market. Fantastic for us enthusiasts!

The electronic circuitry for this aircraft receiver was first published in the Think Tank column of Popular Electronics magazine in September 1995. It appears to be very simple to build, with only about 20 electronic components.

L1 is made by winding 2 turns of 22 AWG magnetic wire on a 5/32 drill bit. This inductor can be modified to change the frequency range of the circuit. If an overload problem occurs when the antenna is connected to the emitter of Q1, the antenna can also be placed at the anode of D1. R5 adjusts the regeneration, thereby adjusting the sensitivity.

Component List:
 R1, R3 - 47 kΩ 1/4 W resistor;
R2 - 10 kΩ 1/4 W resistor;
R4 - 4.7 kΩ 1/4 W resistor;
R5 - 5 kΩ linear taper potentiometer;
R6 - 2.2 kΩ 1/4 W resistor;
C1, C2, C3, C6 - 0.001 μF ceramic disk capacitor;
C4 - 2.2 picofarad ceramic disk capacitor;
C5 - 1 picofarad ceramic disk capacitor;
C7 - 15 μF 15 V electrolytic capacitor;
C8 - 18 picofarad variable capacitor;
D1 - 1N82 diode;
Q1 - 2N918 NPN transistor;
L1 - see notes;
L2 - 1.8 μH inductor
; ANT1 - approximately 18 inch wire antenna;
MISC - printed circuit board, wires, C8 knob.

Technical Specifications            
: Power Supply Voltage: 9-12 volts;
Operating Frequency: 220 MHz - 400 MHz