Instructables

Transistor Radio Hack!

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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.


 
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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!
Mikeop995 months ago
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?
DhanushkaYT11 months ago
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?
zenno7471 year ago
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...

http://www.youtube.com/watch?v=o6DejzpzvEs&list=UUWtdMLAceQeQUNjRDadGJ6A&index=13

nibbler1252 years ago
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
nibbler1,

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.
Tobashadow2 years ago
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.
Tobashadow,

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.
PhilKE3FL1 year ago
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.

see: http://en.wikipedia.org/wiki/Airband

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."
skia3755 years ago
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?????
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:
http://www.smeter.net/spectrum/aviation.php

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.
maybe youre it's your radio, heck i don't know
arianism5 years ago
awsome but umm how is this not illegal?
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.
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 arianism5 years ago
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.
Aplonis2 years ago
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

dkulkarni2 years ago
Try receiving Airband With WORLD Band radio its highly sensitive.......
vishalapr2 years ago
Kipkay U r amazing!I never knew U were on instructables!!!!
Richu163 years ago
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 Richu162 years ago
my 70s radio has them , and i think that one is from the 80s
harry883 years ago
could you mod a 120 volt radio and if so could it expand the range and mabey pick up truck scanners and cop scaneers
mine doesent have that transistor thingy...can mine work!!!
mason1685 years ago
 i dont know the link is broken
nvm i went to radio shack and bought one and it already had air traffic on it
cgosh4 years ago
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 cgosh4 years ago
dear cgosh possible you guide me i want buy airband radio thanx. mehtab
Is it possible for a transistor radio to operate without the copper coils on its board? Because I recently picked up an RCA brand transistor radio (there's a picture of it here *http://i11.ebayimg.com/07/i/001/29/c1/f96d_35.JPG* if anyone recognizes the model) and upon opening it up, I couldn't find coils ANYWHERE. Is there a way to get around this that anyone knows of? Might I be able to solder coils on to it, and if so, where would I put them? I'd greatly appreciate it if someone could help me out.
 could you please post pics of the inside? also try pulling the board out and flipping it, the coils could be on the other side
I don't think a radio could work very well without a coil, since it's a vital component to filter the incorrect frequencies. You mind posting an image of the insides?
A good name5 years ago
I think intercepting radio signals from a government establishment is jsut saying "harass me please"
 listening to airplane traffic control =/= intercepting radio signals from a government agency
that last song playing sounded like Stairway to Heaven.
It was.
aksuduud4 years ago
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.
cgosh4 years ago
You can get amateur (ham) radio signals on the 160-meter band just above the top of the AM dial (1800 - 2000 kHz, just above the 1600 kHz at the top of the AM dial). Use the two remaining silver screw adjusters on the main tuning capacitor shown in Step 2 (they only go 1/2 turn, then start back again; one is gross tuning, the other is fine tuning). Tune to a station at the top of the AM band and "work" it downward. 160 meters will be most active after dark, can travel 100's or even 1,000's of miles. Higher bands are strictly local (50 miles), just like FM and aircraft. To add an antenna, stretch a long wire (any kind/length, indoors or out) and wrap the end around the entire radio about 20 wraps (inductive coupling) perpendicular to the radio's internal antenna (bar with fine wires wrapped on it). If it's outdoors, take it down during thunderstorms.
nk dtk4 years ago
can this be used to pick up amature radio, like in the 2meter band or anything like that?
awang85 years ago
Why would you want to listen to aviation signals anyway?
Derin awang84 years ago
To see what real aviation is like.This might be useful for people who do virtual aviation.
curios
mander434 years ago
Would this mess with an airplane if it was used inside of an airplane?
dude66574555 years ago
does this have to be on a transistor radio?
what is the maximum range if you don't want to go to the airport?
Well, seeing as how this is vhf and it is usually to the farthest point your antenna can see plus one third more of that distance. If you can "see" the area of land that the airport is on, then you should be able to receive their signal. Because the earth seems less curved to radio waves, the horizon of radio waves is a little longer then that of higher frequency light waves. In the case of receiving, it would depend on the height of the antenna, and what amount of power the tower is using. Some ham radio operators(like myself) try to set goals of obtaining low power QSOs and we try to see how far we can get while using the lowest power. QRP or low power has several clubs for people to join if they succed in this goal. To be classified QRP, the transmitted power should be really low, around the area of 5 watts give her take a couple of watts. Take care, KF7AOL
typically line of site or 5 miles
pat12020035 years ago
I tried this and I couldn't get a signal. I live about 1 mile away from my local airport. Am I close enough?
hmm u should be idk drive to the airport and see if it wont work than its the radio lol
Hey your avatar...where did you find it? Shyler at the gmc has the same one...
Maybe your airport isn't a civil one?
ReCreate5 years ago
is there any way to under do it to receive signals around 30-50MHZ?
bwpatton15 years ago
How old is your radio cuz ive got one from like the 1960's or 70's.
knarx5 years ago
Isn't this illegal in many countries?
Kipkay (author)  knarx5 years ago
No. Never illegal to receive transmissions. You can go to the store and buy a police/fire/air scanner for $75 and listen to your heart's content.
only illegal to modify them to receive cell phone transmissions but...i dont think a radio can do that?
Right, since many phones now transmit in the microwave range, or thereabouts, it would be difficult at best to get your radio to demodulate such transmissions.
awang8 Goodhart5 years ago
Aren't microwaves a bit small?
Goodhart awang85 years ago
Yes, and they need special circuitry for demodulation.
mynci Kipkay5 years ago
Actually, it is illegal in some countries. For example, it is illegal in the United Kingdom to listen to airband. It's actually illegal here to listen to almost everything that isn't broadcast or amateur radio, unless you have a license. (If anyone tells you that it's legal to listen provided that you don't act on the information, they are falling for a common - but false - myth from the old days when it was possible to pick up police radio on a VHF FM receiver.) However, I've never heard of anyone being prosecuted for listening to the airband. People quite openly listen, and nothing ever happens to them.
mynci mynci5 years ago
Ah, I found an Ofcom reference for anyone interested in UK law on this matter:

Ofcom Guidance on Receive-Only Radio Scanners
knarx Kipkay5 years ago
Really!? Didn't know that. In Germany it is the "Unwarranted Tapping of nonpublic data" - it is legal stuff, so I can not translate it that it sounds properly in a lawy way in English. But it is illegal in Germany - on the other side the radio communication of the police is rebuilt to digital radio communication.
Radio transmissions fall under public data. Anyone within range can receive them and, with the proper equipment, see/record them.
yeah, it is illegal to transmit, not receive on the bands, and i mean emergency in such a sense, as if you were in or saw a car accident say, or if main power was out you could talk over it.
cv66america5 years ago
I'm at my Laptop right now and whenever I press and hold the up and down arrows (or any key for that matter) I hear a "wooing" sound in my radio. What is that??
that my friend would be the feedback from your keyboard. think of it this way, you keyboard has alot of metal lines going through it and it's not shielded, anytime you make contact with a key the rest of the unused lines become an antenna sending out your keystroke wirelessly. check out the link.

http://hackaday.com/2008/10/20/eavesdrop-on-keyboards-wirelessly/
a long time agoe my computer guru told me that could read computer proccessing cyles the same way...they use some program called cobra or somthing...i never could find any data on it
interesting, i might have to do some research on that, i suppose with the new advances in cpu types now that it'd be pretty hard to read them, but it sounds totally plausible. sounds like a myth for the busters.
thanks! that makes a lot of sense now!
idk but it sounds pretty funny
corksean145 years ago
Civil Aviation means small private aircraft and such? as in no 747's or other big jets? also, can someone tell me what the range is like? thanks:)
It doesn't matter how big the jet is. If it's owned by a person or a company (like a corporate jet) it is Civil Aviation. I managed a Boeing 727 but it was owned by a millionaire and done up like a penthouse apartment. Even though we couldn't get into some of the Civil Aviation airports because it was so big, we were still classified as Civil even if we landed at a commercial airport, or a military base.
a friend of myne (he is about 60 now) he designed burst transmitting for the milatary...they use not only burst transmitting..they also flow up and down on the channles....and then they probaly have the data enqrypted to..this was 10 years agoe or more..they then started employing it into cell phone tech because it save battery life....point being you would have a tought time listening in on milarary signals they dont want you to hear...
Air traffic control uses the same band of frequencies for everybody. Military operations use a different band and may use encryption, but all aircraft operating in the US air-traffic control system have to be able to talk to the same controllers.
Most military aircraft communications are in the military (UHF) aircraft band, located between 225 to 400 MHz. Aircraft communications will be in AM mode while satellite communications in this band will be in NFM mode. Military aircraft sometimes also use the Civilian Aircraft Band (108 to 137 MHz), especially when flying into a civilian airport. They may also be heard in the 137 to 144 MHz and 148 to 150.8 MHz government bands. The 225-400 MHz Military Aircraft Radio Band, also known as the "UHF aero" or "UHF Air" band.
might you be able to solder on a lager coil improving the mhz range further yet?
joinaqd5 years ago
NOLIFER!!!! it doesnt WORK!!!!
What's a nolifer?
Is there a way to further mod this design to pick up on, say, police radio frequencies?
zeawolf5 years ago
Actually it is legal in many states in the US to listen to Police Scanners. I own two. I lived in PA and now in WV. If your state is a legal state just check out Radio Shack. In some states it is illegal to have a scanner in your automobile (Virginia I think). In PA I had a Frequency that was an airplane com channel. Sadly many police are going to "Trunked" channel which you need a special radio to listen. I read an article once that you can simply add an antenna to a certain lead on the Variable tuner and can actually hear shortwave. ~Z~
ram1015 years ago
i've been able to receive wireless telephone converstaions from neighbours on my radio past 108FM by connecting a FM Transmitter antenna to the radio and tuning it.I can only hear 1/2 outgoing converstation spoken by neighbours
Sandisk1duo5 years ago
That's not s tuning transformer, variable inductor!
whatever it is, it has a lot of names(e.g,variable capacitor.).
buttersnake5 years ago
My great aunt had a really old and pretty nice police scanner that i would sit and listen to when i was about 8 years old. Most of the time it was just serious talk, but every now and then they would be cutting up on there and it just seemed funny to me. Normally they sounded like a scripted robot, the robot got bored and started blurting out humor...lol.
DIY Dave5 years ago
Cool Once I heard airband on a regular FM radio
Hahaha, I heard Stairway To Heaven!
metalmancfh5 years ago
in US it is illegal to listen in to police bands, but if you are listening and able to help with some emergency it then becomes legal. if that made sense
Kipkay (author)  metalmancfh5 years ago
That is incorrect. "Help with an emergency'? You mean like hop in your car and follow the police to a bank robbery and help them cuff the criminals? I can walk into my local Radio Shack right now and buy a number of scanners that receive police transmissions. It is illegal to transmit on those frequencies but not to receive them. Here is just an example: Radio Shack Scanner
Do you know if you are able to modify a AM radio to be able to receive the Police Radios? Nice Video
Thornburg5 years ago
That really is pretty sweet. I am going to have to try it see that I will be getting my pilots license soon.
the radio was playing stairway to heaven, lol
Bubbler5 years ago
About thirty years back, same radio type, we used to place a 22pf capacitor across two points in there somewhere. (Long time ago now). This enabled us to hear the police transmissions from HQ, and transmissions from the local patrols. Sadly, the cops went hi-tech, leaving us to find new evening entertainment. We also ran them off of those big squarish lantern batteries, for extra long life. They fixed on with elastic bands.
Scammah5 years ago
Very cool now I can break out my radio shack $10 build your own radio kit and get it to work better.
chalky5 years ago
FORGET OBAMA= VOTE KIPKAY FOR PRESIDENT!
kipkay you never fail mate:)
TheInventor5 years ago
KipKay......................YOU ROCK!!!
puflines5 years ago
this guy is cool heh
I just started with my old sony transistor :D
greeenpro5 years ago
You are kidding me!! Amazing. Thanks for making this so specific.
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