Step 1: Get Started
The only thing you need for this project is an AM/FM transistor radio, an older model that has a physical adjustment for tuning rather than digital. This will be a wheel or slider that changes stations. The only tool you should need is a small screwdriver.
Open the radio by removing all the screws. Watch for the hidden screws located in the battery compartment.
TIP: Stick them to a magnet so you don't lose them.
Step 2: Locate the Components
Now we need to locate the components we will be modifying. First, look for the main tuning capacitor. It will be a square, usually clear, compartment that houses the tuning controls. It will be right next to the tuning wheel. Near the main tuning capacitor you will see two coils of copper wire. These are what control and limit the frequency range of the radio.
Step 3: Tuning Transformers
The tuning transformers are square transformers with tuning slots in the top. Mine had five.
TIP: The best way to locate the one we will be adjusting, is to look for a couple of diodes closest to one.
Step 4: Get to Work
Now, turn on the radio and tune it to the clearest station on the high end of the FM band, near 108.
TIP: Confirm you have found the correct copper coil (one controls AM, the other FM) by touching it with a screwdriver. You should hear a change in the station.
Using your screwdriver, slightly spread out the copper coils. The station will fade away and you have just increased the range on the upper end of the FM band beyond 108MHz!
Step 5: Final Step
Tune the radio in between two stations where you can hear hiss. Adjust the tuning transformer until the hiss is the loudest. Turn it slowly to hear the change and make note of where you started so you can return it to the original location if you want to reverse the modification.
Step 6: Test It Out
Put the radio back together and bring it outside.
Tip:the closer you can get to an airport the easier it will be to find a transmission
Tune above the 108MHz range and should hear transmissions from the Civil Aviation Band (108-138MHz). It may take some patience and you may even have to adjust the tuning transformer a bit. Have fun!