Converting Broadcast radio to ATC receiver

Thread Starter

MarkL

Joined Jan 6, 2010
3
First of all, I am a pre-beginner at all this and don't pretend to know the difference between AM and FM, so be gentle.
I live close enough to BWI airport to monitor the tower, ground control, Patomac Approach and departure as well as some enroute traffic control. Some of my antiques have selectivity that allows me to hear Tower,119.4, and approach on the same radio, but ground control,121.9, is a stretch, and requires a second radio. enroute and departure would require additional radios to monitor them all, although it would get pretty busy. Can an FM radio, 88 - 108, be re-tuned to receive the air band, 108 - 133? I was searching on eBay the other day and saw an ad "CONVERT YOUR RADIO INTO AN AIRCRAFT BROADCAST RECEIVER". For six dollars the author will impart his knowledge and wisdon to me. I'm afraid the wisdom will be to go buy another antique receiver. I wouldn't want to spend six bucks on that. Over the years I've been told that aviation com. is AM even though the freqs. are in the FM range. Maybe you can see where I get confused. If it's a matter of sticking a screwdriver in an "IF can" I may be able to handle it. If I have to take nail clippers to a winding, I'm gonna need a partner. My bet is someone out there knows and is patient enough to tell me.
 

Thread Starter

MarkL

Joined Jan 6, 2010
3
Thanks, I guess. I take that as a no. Re-tuning is not a solution. I seem to hang on the trailing edge of technology.
 

Wendy

Joined Mar 24, 2008
23,806
Actually there is a way, but it is pretty technical. You move the frequencies to the FM band with a down converter. Look up the term heterodyne on Wikipedia.
 

Thread Starter

MarkL

Joined Jan 6, 2010
3
As complicated as the Wikipedia article sounded, it is probably understated and way over my head and abilities. Thanks for adding to the explanation. As an engineer you'll understand, 'when you know what you don't know you half way through.' I'm hardly a quater of the way then. heheh I have a feeling Blueroomelectronics had the solution.

Thanks again,
 

bertus

Joined Apr 5, 2008
22,994
hello,

You could also make a converter using a NE602.
The oscillator can be 20 Mhz, this will subtract 20 Mhz from the recieving signal.
So the scale from 88 to 108 becomes 108 to 128.

Greetings,
Bertus
 

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eblc1388

Joined Nov 28, 2008
1,542
AM is used, I was told for another reason.

With FM, when there is no signal, the noise is unbearable and thus a squelch circuit is needed. This effectively silence the audio output with no radio signal presence.

Apparently a little bit of noise from an AM radio, with a correctly adjusted squelch level, is more comforting than silence which also happens when the power is off, someone turned down the volume, radio is faulty or whatever.
 
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