Aircraft Radio Communications Receiver

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The communications between commercial aircraft and the ground can be interesting, amusing and sometimes even disturbing. However radios that receive the approximately 220MHz to 400MHz band commonly used for aircraft (both military and commercial) are not easily found. And scanners can be complicated, large and expensive. With an easy to build circuit such as this one, everyone can enjoy listening in on these conversations.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1, R3	2	47K 1/4W Resistor
R2	1	10K 1/4W Resistor
R4	1	4.7K 1/4W Resistor
R5	1	5K Linear Taper Pot
R6	1	2.2K 1/4W Resistor
C1, C2, C3, C6	4	0.001uF Ceramic Disc Capacitor
C4	1	2.2pF Ceramic Disc Capacitor
C5	1	1pF Ceramic Disc Capacitor
C7	1	15uF 15V Electrolytic Capacitor
C8	1	18pF Variable Capacitor
D1	1	1N82 Diode
Q1	1	2N918 NPN Transistor
L1	1	See Notes
L2	1	1.8uH Inductor
ANT1	1	Approx. 18 Inch Wire Antenna
MISC	1	PC Board, Wire, Knob For C8

Notes

The circuit originally appeared in the Think Tank column of the Sept. 1995 issue of Popular Electronics.

L1 is made by winding 2 turns of 22 AWG magnet wire on a 5/32 drill bit. This inductor can be modified to shift the frequency range of the circuit.

The antenna can also be placed at the anode of D1 if overload is a problem with it connected to the emitter of Q1

R5 adjusts regen and thus sensitivity.

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Comments

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anonymous Aircraft Radio Communications Receiver Friday, March 21, 2014 11:32:14 PM

Can this be modified to listen to spacecraft communications from the International Space Station and Soyuz spacecraft?

ss542006 Aircraft Radio Communications Receiver Sunday, November 24, 2013 4:36:02 PM

I am getting ready to build this radio,I am using a 0-60pf variable cap with a 22pf in series to bring it down to the 15pf as shown in the schematic. There is alot of military aircraft traffic here so I should be able to use it alot. I do want to build a second for the 108-135megahertz commercial/civilian aircraft band...what would be the coil for this conversion and what would be the capacitor value for the emitter to collector?

ss542006 Aircraft Radio Communications Receiver Saturday, November 02, 2013 8:58:02 PM

In the schematic is the 1N82 diode in correct orientation? Cathode towards C8?

anonymous aircraft communicationAircraft Radio Communications Receiver Wednesday, January 25, 2012 11:45:58 PM

I have a gmrs twoway radio it keys from 110.9 to @36.5 MHz. Will anybody hear me in a airplane. If they are not to far away my call is k6cal I am in San Jose CA

Norman (KA1GUK) Aircraft Radio Communications Receiver Wednesday, August 17, 2011 5:05:40 PM

One thing I forgot to mention in my previous comment was that the 2N3904 transistor will not work at 400MHz, but the SF245 transistor used in the Czech circuit will. The 2N3904 transistor will work fine in the audio stage, however.

Norman (KA1GUK) Aircraft Radio Communications Receiver Wednesday, August 17, 2011 4:37:48 PM

Please see the circuit at: http://krysatec.benghi.org/phprs/view.php?cisloclanku=2006033102 It's in the Czech language, but you can translate it and the schematic does not need any translation. The ideas of using a front end buffer and an audio amp stage can help this type of receiver circuit quite a bit. I like the circuit on the above website, but the values of the coil and tuning cap need to be changed to tune the newer air band. I'm not sure what else may need to be changed at this point to accommodate the higher frequencies.

anonymous Aircraft Radio Communications Receiver Monday, March 07, 2011 12:25:51 AM

it does really work?

Federico Colombo Aircraft Radio Communications Receiver Thursday, August 12, 2010 12:53:00 AM

I biuld this circuit but I receive no signal (yet)... I used a 2N5179 instead of 2N918. 1N34A instead of 1N82. And a C7 of 22uF (not 15uF). The other parts are same as needed. Do you have any comments about these replaces?. Thank you very much.

anonymous Aircraft Radio Communications Receiver Tuesday, April 27, 2010 12:34:35 PM

I built it and works! I replaced 2n918 with a 9018 with a frequency transition of 1100 mhz! I made L2 with 28 turns of 0,6 mm wire on 7mm drill bit , 1.6 cm long. Also a diode 1n34 works fine!

Don Hill Aircraft Radio Communications Receiver Saturday, October 17, 2009 12:48:32 PM

My research indicates that the 1N82 is a germanium diode from the fifties. A 1N34 should work as a replacement. A normal silicon diode will not work well as a Germanium diode has a 0.3V forward drop and a silicon diode has a 0.7V forward drop.

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anonymous	Aircraft Radio Communications Receiver	Friday, March 21, 2014 11:32:14 PM
Can this be modified to listen to spacecraft communications from the International Space Station and Soyuz spacecraft?
ss542006	Aircraft Radio Communications Receiver	Sunday, November 24, 2013 4:36:02 PM
I am getting ready to build this radio,I am using a 0-60pf variable cap with a 22pf in series to bring it down to the 15pf as shown in the schematic. There is alot of military aircraft traffic here so I should be able to use it alot. I do want to build a second for the 108-135megahertz commercial/civilian aircraft band...what would be the coil for this conversion and what would be the capacitor value for the emitter to collector?
ss542006	Aircraft Radio Communications Receiver	Saturday, November 02, 2013 8:58:02 PM
In the schematic is the 1N82 diode in correct orientation? Cathode towards C8?
anonymous	aircraft communicationAircraft Radio Communications Receiver	Wednesday, January 25, 2012 11:45:58 PM
I have a gmrs twoway radio it keys from 110.9 to @36.5 MHz. Will anybody hear me in a airplane. If they are not to far away my call is k6cal I am in San Jose CA
Norman (KA1GUK)	Aircraft Radio Communications Receiver	Wednesday, August 17, 2011 5:05:40 PM
One thing I forgot to mention in my previous comment was that the 2N3904 transistor will not work at 400MHz, but the SF245 transistor used in the Czech circuit will. The 2N3904 transistor will work fine in the audio stage, however.
Norman (KA1GUK)	Aircraft Radio Communications Receiver	Wednesday, August 17, 2011 4:37:48 PM
Please see the circuit at: http://krysatec.benghi.org/phprs/view.php?cisloclanku=2006033102 It's in the Czech language, but you can translate it and the schematic does not need any translation. The ideas of using a front end buffer and an audio amp stage can help this type of receiver circuit quite a bit. I like the circuit on the above website, but the values of the coil and tuning cap need to be changed to tune the newer air band. I'm not sure what else may need to be changed at this point to accommodate the higher frequencies.
anonymous	Aircraft Radio Communications Receiver	Monday, March 07, 2011 12:25:51 AM
it does really work?
Federico Colombo	Aircraft Radio Communications Receiver	Thursday, August 12, 2010 12:53:00 AM
I biuld this circuit but I receive no signal (yet)... I used a 2N5179 instead of 2N918. 1N34A instead of 1N82. And a C7 of 22uF (not 15uF). The other parts are same as needed. Do you have any comments about these replaces?. Thank you very much.
anonymous	Aircraft Radio Communications Receiver	Tuesday, April 27, 2010 12:34:35 PM
I built it and works! I replaced 2n918 with a 9018 with a frequency transition of 1100 mhz! I made L2 with 28 turns of 0,6 mm wire on 7mm drill bit , 1.6 cm long. Also a diode 1n34 works fine!
Don Hill	Aircraft Radio Communications Receiver	Saturday, October 17, 2009 12:48:32 PM
My research indicates that the 1N82 is a germanium diode from the fifties. A 1N34 should work as a replacement. A normal silicon diode will not work well as a Germanium diode has a 0.3V forward drop and a silicon diode has a 0.7V forward drop.