AM/FM

Use an AM/FM radio to receive aircraft transmissions.

With all the high-tech listening options out there — iPods, MP3 players, satellite radio — who needs AM/FM? But before you toss that radio relic into the trash, try this project to eavesdrop on air traffic radio transmissions.

You’ll need: AM/FM radio, screwdriver.

How to do it: (Note: Aircraft radio signals broadcast on the 108 to 136 MHz range, whereas FM radio signals use the 88 to 108 MHz range. To pick up aircraft signals, all you’re doing is adjusting your dial to pick up the higher frequency.)

Open the back of your radio (by either sliding the case open or using a screwdriver) so you can see the parts of the circuit board.

Examine the circuit board and look for the part under the tuning dial that selects the stations. Look for two or three small square metal pieces on the circuit board; these are the filter transformers. One of these filter transformers will have two or three small glass diodes next to it (diodes look like clear beads with wires on each end). This is the transformer that you need to adjust.

Turn your FM radio on and turn to a spot between stations so that you hear a background hiss.

Using a screwdriver, turn the top of the filter transformer until the hiss gets as loud as possible. This converts the FM portion of the radio so it can receive AM signals.

Now you must extend the range of the FM band. To do this, look at the radio’s tuning dial (still in the open part of the radio) and find a pair of small copper coils next to a large square tuning capacitor on the main board. Using the flat part of the screwdriver, spread the coils apart so there is as much space as possible between each coil. By doing this, you have extended the broadcast range and can receive aircraft signals
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