Introduction:-
The communications between commercial aircraft and the ground can be interesting, amusing and sometimes even disturbing. However radios that receive the approximately 220MHz to 400MHz band commonly used for aircraft (both military and commercial) are not easily found. And scanners can be complicated, large and expensive. With an easy to build circuit such as this one, everyone can enjoy listening in on these conversations.
Circuit diagram:-
click on the picture for better quality................
Parts:-
| R1, R3 | 2 | 47K 1/4W Resistor | |
| R2 | 1 | 10K 1/4W Resistor | |
| R4 | 1 | 4.7K 1/4W Resistor | |
| R5 | 1 | 5K Linear Taper Pot | |
| R6 | 1 | 2.2K 1/4W Resistor | |
| C1, C2, C3, C6 | 4 | 0.001uF Ceramic Disc Capacitor | |
| C4 | 1 | 2.2pF Ceramic Disc Capacitor | |
| C5 | 1 | 1pF Ceramic Disc Capacitor | |
| C7 | 1 | 15uF 15V Electrolytic Capacitor | |
| C8 | 1 | 18pF Variable Capacitor | |
| D1 | 1 | 1N82 Diode | |
| Q1 | 1 | 2N918 NPN Transistor | |
| L1 | 1 | See Notes | |
| L2 | 1 | 1.8uH Inductor | |
| ANT1 | 1 | Approx. 18 Inch Wire Antenna | |
| MISC | 1 | PC Board, Wire, Knob For C8 |
Notes:-
- L1 is made by winding 2 turns of 22 AWG magnet wire on a 5/32 drill bit. This inductor can be modified to shift the frequency range of the circuit.
- The antenna can also be placed at the anode of D1 if overload is a problem with it connected to the emitter ofQ1
- R5 adjusts regen and thus sensitivity.
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