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Aircraft Band Receiver

Modify an ordinary analog AM/FM radio to eavesdrop on air traffic control communications. All you need is a screwdriver -- can't be easier than that!

Aircraft Band Receiver

The FM radio band (88-108 MHz) lies just below the Civil Aviation Band (108-138 MHz), which is used for air traffic control, air shows, and other ground-to-air communications. This means that it’s easy to modify an ordinary analog AM/FM radio to receive these transmissions.

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Steps

Step #1: Get Yourself an Analog Portable Radio

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Aircraft Band Receiver
  • Pick an older style AM/FM radio with a traditional tuning dial, not one with a synthesized tuner.
  • For our project here we're using the venerable RadioShack AM/FM Pocket Radio. (As of 11/9/12 the RadioShack Pocket Radio no longer uses analog tuning, It has the tradional dial, but now uses digital tuning. The copper loops referenced in the rest of the project no longer apply.)

Step #2: Remove the Back Panel

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Aircraft Band Receiver
  • Remove the screws from the back of your radio and gently pry open the casing.
  • Case screws to consumer electronics can frequently be found inside of the battery compartment, so make sure to look there if your case isn't coming apart when you think you've removed all of the screws.

Step #3: Locate the Coils

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Aircraft Band Receiver
  • Identify the three copper-colored coils (circled here in red) and the two tuning transformers (shown in the blue boxes).
  • FYI: That clear plastic box to the left of the coils is the radio's tuning capacitor. Move the dial around on the front of the radio and you'll see its parts move inside the clear case.

Step #4: Adjust the coils

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Aircraft Band Receiver
  • Switch the radio on and set it to FM reception. Tune to a station high on the dial, as close as you can to 108 MHz.
  • Using a flat screwdriver, slowly expand the coil windings on all three coils.
  • You should notice the tuned radio station is moving slowly down the dial. This is good, as we are expanding the reception range of the radio in the band above 108 MHz.

Step #5: Test it Out

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Aircraft Band Receiver
  • Retune the radio and check that the original station is still available, but lower down on the dial.
  • In the picture you can see that the station around 108 MHz has now moved down to the location marked 101 MHz on the dial.
  • The final step is to turn the radio dial in-between stations, so that all you hear is hiss. Now adjust the tuning transformers so that this hiss is at the loudest possible level.
  • Congratulations! The modifications are complete. Put the case back on and let's pay a visit to the local airport to try it out.
  • Get as close to the tower as you can, and tune the dial in the new extended region you just created. When planes are in the area, you should be able to pick up their communications!

Steve Hobley

This week, I have been mostly working on...

I've been tinkering around with bits of technology since I was five years old. I used to take the telephone apart at home, just to see how it worked.

After a couple of years I could even put it back together again - and sometimes it would continue to work.


Comments

  1. TechnoWeenie says:

    Won’t work the way you think it will.

    FM Broadcast is wide FM modulated, whereas aircraft transmit AM. Different modulation scheme = no worky

    1. That Pilot Guy says:

      NO. Just no. The only aviation tool that is based on AM is the NDB/ADF, which are being phased out. Tower, Ground, Center, VORs, Air to Air, all use VHF, Which is in the portion of the spectrum in which FM is used.

      1. Runway 28 says:

        I agree with That Pilot Guy. I used to listen to aircraft VHF using a FM receiver without any mod. The radio I had caught the aircraft bands, it wasnt very strong reception but it worked well and I soon learned the pilot lingo… good old days :)

      2. Nick says:

        You seem to be confusing Modulation with frequency band. Indeed all these communications you are referring to are in VHF Frequency band, BUT they are modulated using AM (Amplitude modulation and NOT FM (Frequency modulation).
        Have a look at http://en.wikipedia.org/wiki/Airband

        In short, I agree with TechnoWeenie, it will not work…

      3. Tom says:

        Technically, TechnoWeenie is correct. Aircraft VHF radios are AM for historical purposes (AM was available before FM and early aviation needed whatever was available). However if you have a strong enough signal you can demodulate it in various unconventional methods, like crystals, fillings in teeth etc. So this might work for a strong signal with some distortion but it will never pull in weak signals and probably won’t do either well or clearly.

    2. CircuitBurner says:

      Yes, FM receivers will work on aircraft band.
      They are transmitting with an AM carrier wave, but FM receivers demodulate an AM signal just fine, with only a small loss in sensitivity.
      Now, forget about Transmitting with FM and receiving it on an AM, as the demodulation of an AM Rx will make an FM signal sound like noise.
      Also, lol, Tx on aircraft band without the requisite credentials and locations not using aircraft, can and will land you in trouble…lots.

    3. Rob says:

      This WILL work.
      If you don’t think it will, Google “slope detection”.
      KJ6JJK

    4. foobar says:

      A friend once told me he listened to aircraft communication with a totally unmodified FM radio.

    5. Foobar2000 says:

      My uncle once told me that he had heard aircraft communications on a totally unmodified FM radio, so this should work.

      1. Foobar2000 says:

        Oops I didn’t realise it went through the first time :D. Well that friend was actually my uncle, anyone you pick is fine by me.

  2. KJ6MSG says:

    Aviation communications are in fact Amplitude Modulated. The frequency band has nothing to do with modulation method. With a strong enough signal, a FM demodulator will demodulator part of an AM signal, albeit very poorly.

    - A pilot with an EE degree and amateur radio license

  3. SkipF says:

    I’m kinda surprised this thread is still on-line…
    -another ham radio operator.

  4. guinnessbear says:

    I used to do this mod when I was a kid, and it does work..Those who are saying it won’t, try it!

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    1. Jim Miller says:

      what!!!