Introduction: Transistor Radio Hack!

Picture of Transistor Radio Hack!
Take an old AM/FM transistor radio and make a quick modification so it picks up Air Traffic Control, Air Shows and other Civil Aviation Band transmissions. Amazing! Thanks to Cy Tymony for the Make Magazine article. See the Test Results in the video.

Step 1: Get Started

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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!


AdieR3 (author)2017-06-08

need one for move one step forward

komal singh (author)2017-02-24

It can catch far radio stations or not

aksuduud (author)2009-09-13

I think i did something wrong cause it didnt work. But the good thing is that suddenly it got increased antenna power so i could hear normal radio stations better! Thanks anyhow.

khyalia (author)aksuduud2016-02-21

I sound like school teacher lol

khyalia (author)aksuduud2016-02-21

Because u shrinked the coil. Frequency Range decresed . quality incresaed.because dampong factor decreased

khyalia (author)khyalia2016-02-21

Beacuse inductance increased also .lol

guillaumetorreilles (author)2016-01-25

I am using both a hacked DVB-t receiver working as a SDR and this radio, the SDR gives much more precision but this build works fine!

A good name (author)2009-04-19

I think intercepting radio signals from a government establishment is jsut saying "harass me please"

Kasm279 (author)A good name2009-12-31

 listening to airplane traffic control =/= intercepting radio signals from a government agency

PranavV7 (author)Kasm2792015-11-30

Not really. I am a pilot and I know we have handheld two-way radios. We are allowed to use them around the airport or for training purposes. Anyway, if you are using them to monitor air traffic at home for hours each day, you might be deemed suspicious. You can check the Code of Federal Regulations if in doubt. As always, if you think it might be against the law, better not do it until you are sure it is legal.

analogue23 (author)A good name2015-04-22

Those are not "secret frequencies" anyone can BUY an air traffic receiver or even listen for free online. Also, the "government" does not know (nor CARE) what you listen to on over the air radio. They have no way of telling what you hear unless they are creeping around your windows.

gaieb (author)analogue232015-05-24

Sorry you are wrong there, we could determine what stations you were listening to back in the 50s if not before, In England they go around or use to in vans to monitor what tv station you were listening to so they could charge you. But I don't think you have to worry about that, unless you are already on one of their lists, then it is anyones guess. Would depend on the number of assets they have in the area.

Kiteman (author)gaieb2015-05-25

"Detector vans" did not detect what station you were watching, they picked up the faint radio emissions of the old CRT tubes themselves. Since nobody used CRTs, and EM emissions of electronics in general have decreased dramatically since the invention of the microchip, detector vans have fallen out of use.

The BBC now just assume that everybody has a TV, and send enforcement notices to any address that doesn't have a TV licence. If you do not own a TV, you have to fill in a bunch of paperwork to register the absence of a TV, rather than the presence of one.

gaieb (author)Kiteman2015-05-26

You are wrong, they detected the hetrodyne signal, which changed depending on which channel you were watching.

Kiteman (author)gaieb2015-05-27

I wonder how you know that, since the BBC has never released the details of how their vans worked (even after an FOI order), and there has never been a single prosecution using detector van evidence.

parthanians (author)2015-09-01

Can i remove coil and put one with either more turns or more spacing or both to tune into higher frequencies? i dont understand much of the internal circuitry of the radio receiver but is the coil the only thing responsible to be able to catch hold of the various frequencies? Also Kipkay, okay we do not live in an ideal world so after my questioned mod if i simply knock my receiver into AM mode will it work better?

daveww (author)2015-08-19

MarkL22 (author)2015-06-11

Thank you Kipkay this was just the information I was looking for, and I fixed my radio.
I actually didn't use the instructions as you meant them to be used here...not exactly.

A friend had this little cheap Chinese AM/FM radio and they had broken the antenna. I do not know if they had opened it up and disturbed the copper coils or not.

The radio reception absolutely sucked at her camp so I gave her a multi-band radio and she can now listen to her favourite station.

Not that this little radio is worth my time, but I was curious to see if I could make something out of it. I replaced the broken antenna, but I then noticed that the radio would not pick up anything above 103.xx

Using your instructions to increase the range I was able to put the station 104.3 right back on the dial where it is supposed to be. Yeah!

The radio reception still sucked though, so I went a bit further and "messed" with the main tuning capacitor. This radio does not have the small square tuning transformers.

One of the adjustments on the main tuning capacitor made a hugh improvement to the reception. Seemed like a gain control. This little radio must have been put together on a Monday. My Thursday adjustments made it into a nice working radio.

christopher.jaeger.334 (author)2015-02-15

can it pick up police scanner frequenceys ?

No, it cannot. Go to radioreference dot com and get help there on what you will need to receive police scanner chatter. You will probably need whats called a trunk tracker digital scanner, those can run several hundred dollars - unless your police dept is in USA and also happens to use APCO25 "phase 1" you might find a Uniden scanner ON SALE or Clearance for around $ if you are Lucky. Original price on those is about 599., but they are clearing them out for new stock. You can also TRY and wangle with an SDR dongle, the RTL2832 usb stick from China (around $20) but it requires a bit of technical knowledge to get it to work to receive such complex things as scanner chatter- as in installing complicated programs etc. If you want clean, simple police scanner just go to that radioref. site I mention here and look up what you need but you need to post what area you are in, as in nation, state and county and what you are interested in hearing, because each state/county has different requirements in a scanner. Some need a 700. scanner that has specific digital features some don't.

rahul.janarthanan.14 (author)2015-04-05

how far it can pick up the signals

tmpenner (author)2015-03-08

How would the modification to a lower frequency be similar? I need to pick up a 75.7

ivendrans (author)2014-08-27

Hai very Nice Project So that iam latest technolagy.......

Mikeop99 (author)2013-11-03

I wonder if you are able to help me. I have taken a brand new analogue radio and am attempting to fit it into an old radio (want the look of an old radio but have fm and a Bluetooth module). I discovered the easiest way to make the tuning needle work was to take the tuning capacitor off the new one and mount it to the board of the old one and solder wires from the new board to its relocated tuning capacitor. Works perfectly other than I now can get any fm. I did however get air traffic control at one point which to me sounds as if a have change the range I pick up or something as a generally don't get anything. Is the location of the coil a factor with the tuning capacitor?

DhanushkaYT (author)2013-05-05

Nice work.......I was wondering if I could make a rf mixer and beat higher frequencies down to in between 88-108 so we could receive higher frequencies at around 144 or around 200....what do you think?

zenno747 (author)2013-01-04

This hack is not too difficult to do. I converted this old wren ghetto blaster to air traffic control here in dublin Ireland and it works fine but the only thing left that i have to do is make the band narrower to stop other close stations from bleed-over. Youtube video below...

nibbler125 (author)2011-07-07

i live next to a airport and sometimes it will interfere with my radio instead of music it will cut off and you will hear the piolets voice instead

PhilKE3FL (author)nibbler1252012-10-12


Yours is a case in point that shows we do not live in the perfectly compliant theoretical world where FM demodulators ONLY demodulate FM signals and AM demodulators ONLY demodulate AM signals.

Sounds like your radio is a good candidate for this modification.

Tobashadow (author)2011-07-08

You do know this will never work!

For your information the radio band that radio is made for is 87.5 to 108.0 MHz using frequency modulation hence the (FM).

All civilian air communications occur within the 108 - 137 MHz radio band. And use Amplitude Modulation (AM) mode.

So even tho you can tune to the band you can not listen to it unless you convert the entire radio to AM.

PhilKE3FL (author)Tobashadow2012-10-12


You are correct in a perfectly "compliant" theoretical world. But, we do NOT live in a perfectly compliant theoretical world. By this I mean we live in the real world where things never work perfectly as intended, just usually close enough that it is almost perfect. But, almost perfect, is not perfect and so...

I've tested both AM & FM demodulation of the opposite bands and have found that they can decode the other band just not very well. I did this with an wide band receiver for the AM & FM broadcast bands. They were able to be heard, just not well nor perfectly clearly either.

So, it all depends on if the particular radio has some unintended demodulation of an AM signal. Tuning it up to the aviation band means the only thing there are the AM broadcasts so there will be NO FM signal to demodulate or interfere with the incidental demodulation of an AM signal. Then it all depends on if the radio can amplify that incidental demodulation enough to be heard.

PhilKE3FL (author)2012-10-12

The aviation band is an AM (Amplitude Modulation) band between 118 & 137 MHz, the FM band on the radio is a Frequency Modulation band & will NOT be able to hear the AM broadcasts of the aviation band easily if at all. It all depends on how poorly the particular radio is at picking up FM vs. AM broadcasts and how much the FM part can even pick up AM transmissions. Some "incidental" AM demodulation in the FM section of the radio can cause the radio to pick up AM broadcasts but it's probably not very good at doing so.


Quote: "As of 2012, most countries divide the upper 19 MHz into 760 channels for AMPLITUDE MODULATION voice transmissions, on frequencies from 118-136.975 MHz, in steps of 25 kHz."

skia375 (author)2008-08-04

I couldnt get the transmission but I got my radio to get up to 111.9hmz so why couldnt I hear when imright under a airplane passage route?????

wobbler (author)skia3752012-09-30

If you're only going up to 111.9MHz you're unfortunately still too low. Although the aircraft band goes from 108-136MHz, the chatter is above 118MHz. See here for frequency bands overview:

You should also be able to find the actual frequencies for your area by having a search on the internet for your local airport frequencies.

What I would do is find the highest frequency FM station you can find, then move the frequency dial to point down a few MHz and then bring the station back in by using the instructions as above. Keep repeating this bit by bit until you've got the station off at the 88MHz end and you then know you've got roughly 108-136MHz across the band. By doing it a bit at a time, you've got more chance of keeping everything controlled and working ok.

Good luck in getting your radio to go higher.

logan996 (author)skia3752008-08-07

maybe youre it's your radio, heck i don't know

arianism (author)2008-11-25

awsome but umm how is this not illegal?

Aplonis (author)arianism2011-11-18

I forget just WHERE in the regs it is, but EVERY citizen of the USA is guaranteed the right to LISTEN to ANY transmitted frequency. What IS illegal, however, is to pass any information obtained thereby along to other parties. So you can receive any frequency whatever but you cannot tell anyone what you learned if it is of a private nature. The transmitting party is deemed to have "spoken in pubilic" by transmitting on the radio bands. This is one of the VERY early rules put out by Congress sometime in the 1930's and has never been repealed.

mannys9130 (author)arianism2009-03-20

any transmission emmited with in any band other than cellular phone or wireless telephone is able to be received legally. You may not intercept telephone signals. That is indeed illegal, but this is fine because it is in the aircraft bands. You may receive these frequencies, however, on some, you may need a licence, such as marine, amateur, aircraft, and commercial am and fm broadcasting.

awang8 (author)arianism2009-01-03

It's just listening to people talking aircraft language. I mean, you don't hijack the signal which could be deadly, you're just curious to find out what they say in control towers.

Aplonis (author)2011-11-18

I did this once about 30 years ago. After discovering a strong, anomalous blip on my Kenwood TS830S ham radio's 160 meter band, I dialed up out of the ham freqs to discover my neighbor's cordless phone (an uber cheap Radio Shack model) operating there. It was very low power, but right next door so still came in strong.

As I was living in the basement of my fathers house while going to college at the time, my equally cheap AM/FM clock radio couldn't pick up very much. So I marched the AM band tuning out of range and set it on my neighbor's phone. When he would call me, I'd hear it first on the AM radio before it would ring on the handset. I'd answer, "Hello Tom" and he'd be a little freaked on how I knew it was him. I'd say, "I recognized your ring". This was years before anybody had a cell phone and could program that in.

I'd forgotten all about that until reading this Instructable. Thanks for the memories. LoL

dkulkarni (author)2011-09-27

Try receiving Airband With WORLD Band radio its highly sensitive.......

vishalapr (author)2011-07-08

Kipkay U r amazing!I never knew U were on instructables!!!!

Richu16 (author)2011-03-18

Mine didn't have the tuning transformer will it work? Is it possible listen maybe with additional items? And what radio does have the tuning transformer? 1980s? 1990s? Please reply as soon as possible. I need to listen to airband. I lived approximately 3 miles from Brunei airport.

loy266 (author)Richu162011-06-30

my 70s radio has them , and i think that one is from the 80s

harry88 (author)2010-07-12

could you mod a 120 volt radio and if so could it expand the range and mabey pick up truck scanners and cop scaneers

mastermakoko (author)2010-06-07

mine doesent have that transistor thingy...can mine work!!!

sventeeuwen (author)mason1682010-03-07

 i dont know the link is broken

lil jon168 (author)mason1682009-04-01

nvm i went to radio shack and bought one and it already had air traffic on it

cgosh (author)2009-08-17

No one cares if you listen to aircraft signals. Much of it is garbled and quick.
If you were on an airplane, have an FM radio tuned to 107.3, it could interfere with the pilot's radio if he's tuned to 118.0 mHz, due to the 10.7 mHz I.F. (intermediate frequency) that's generated by your radio to make it work. (107.3 + 10.7 = 118).
Most aircraft frequencies are higher than this, so it's not likely to be an issue.
Your aircraft-modified radio could mess with a pilot's radio, but you'd have to be within a few feet of it. You can do the same with any two FM radios tuned 10.7 mHz apart, or any pair of AM radios tuned 455 kHz apart.

aircom (author)cgosh2010-02-16

dear cgosh possible you guide me i want buy airband radio thanx. mehtab

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Bio: Tinkerer, hackster and prankster. Hit me up on Facebook: Thanks for checking out my Instructables!
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