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