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

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!

Comments

[ManimatumM]

Yes it is. Using a T shape coax cable Antenna we can listen from home loud and clear. Have a nice day.

[komal singh]

It can catch far radio stations or not

[simone.mastroianni.04]

I'll explain everything right, as far as I noticed (No offense) you have no basis on the airwaves.
There is a big difference between the frequency and the distance of a transmitter.
For
example: There is a radio transmitter in the tokyo airport that
operates at a high frequency (say 150 MHz), we also have, in Tokyo,
another radio transmitter (a very ordinary radio station) that operates
at a frequency of 102 MHz.
None of the two
frequencies will ever be able to transmit so far, except at some
frequencies (even if I'm not a radio amateur so I will not be very
precise)
The radio modified by this man does nothing but
increase the reception range, both for high frequencies and for normal
frequencies. The reception range is always that. It depends almost all on the transmitters, not on the radios; unless you amplify the power of the antenna, but it's a whole other story.

So, the answer to your question is no.

Bye

[RobertB773]

how do u know which transformer is the right one to tune I trying to get better stations in a building

[aksuduud]

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]

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

[jompon2547]

what do you mean by that
and
i try to make spark gap telegraph
how should i wire up the coil
do you have any idea???

[khyalia]

Beacuse inductance increased also .lol

[khyalia]

I sound like school teacher lol

[AdieR3]

need one for move one step forward

[guillaumetorreilles]

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!

[parthanians]

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]

[MarkL22]

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]

can it pick up police scanner frequenceys ?

[analogue23]

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]

how far it can pick up the signals

[tmpenner]

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

[ivendrans]

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

[Mikeop99]

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?