1+ 2+ 3 Aircraft Band Receiver By Cy Tymony
Modify an AM/FM radio to pick up air traffic control communications.
You will need: AM/FM radio, small Phillips screwdriver, small flathead screwdriver
Extending the Range of Your Radio
The aircraft band, 108 to 138MHz, is directly above the FM band. But aircraft signals are broadcast in an
AM format. Amazingly, it’s possible to modify a typical AM/FM radio to receive aircraft signals in the
proximity of an airport, without removing or adding any parts! Here’s how.
540 kHz 1600 88
108 MHz 138
1. Identify the radio parts.
Use a battery-powered, inexpensive, analog radio.
Remove the back cover and locate the main tuning capacitor (A). It’s easy to find — just turn the tuning dial,
and you’ll see its parts move through its clear case.
Near the main tuning capacitor you should see
one or two small coils of copper wire (B) mounted
on the PC board. These coils are used to limit the
frequency range of the radio.
Next, locate the tuning transformers (C). They
look like square, metallic boxes with tuning slots in
the top. One of the tuning transformers may have
a couple of small diodes near it mounted on the PC
board. This is the tuning transformer that you’ll
adjust. Its function is to filter out AM noise.
2. Modify the radio.
Tune the radio to an FM station at the upper end of
the FM band. Notice where the dial is positioned.
Spread apart the small coils near the main tuning capacitor using a small flathead screwdriver.
When you finish, tune the dial and you’ll notice
that the broadcast stations have moved down the
dial. The radio is now able to receive stations well
Tune the radio between stations so you can hear a
slight hiss. Notice the position of the slot on the top
of the tuning transformer that is near the main tuning capacitor (nearest to the small diodes). Slowly
turn its screw until the hiss sound is at its maximum
level. Note exactly how many turns and in which
direction you turn the screw, for easy repositioning
later. The radio is now able to receive AM signals in
its newly expanded FM band.
Illustration by Timmy Kucynda
3. Test the modified radio.
Replace the radio’s cover. Take it — and the screwdrivers — near an airport during a peak air traffic period.
Turn the radio on the FM band with the volume up and slowly adjust the dial. You should be able to hear
air-to-tower transmissions. If needed, make adjustments to the tuning coils and the tuning transformer.
Cy Tymony is the author of the Sneaky Uses for Everyday Things book series.