poadeleted21
Touchdown! Greaser!
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Why do they have different jacks than airplanes? 
Helicopter Headsets
- Thread starter poadeleted21
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Sac Arrow
Touchdown! Greaser!
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I'm not positive, but I think it's because helicopter headsets use a microphone with a different bias which would burn up if plugged in to an airplane jack.
poadeleted21
Touchdown! Greaser!
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Yeah, but why not just use the same mic and jack?
denverpilot
Tied Down
RotorAndWing
Final Approach
[FONT=Verdana,Helvetica,Arial][SIZE=-1][FONT=ARIAL,]Found this on another site. Hope it answers your question.
In the "old days" there were essentially 2 types of microphones use in aviation:
1) [FONT=inherit !important][FONT=inherit !important]Dynamic[/FONT][/FONT] Microphones: These were essentially a coil of wire wrapped loosely around a permanent magnet and connected to a membrane. Much like a speaker. When you talk into the membrane the sound waves vibrate the coil over the magnet and an electrical signal is generated which contains electrical fluctuations approximating the air pressure fluctuations produced by sound.
2) Carbon Microphones: Granules of a special carbon are contained in area behind a metal membrane. The metal membrane transfers the air vibrations caused by sound to the carbon granules. A DC voltage applied to the carbon granules is varied by the changing resistance offered by the vibrating carbon granules. [/FONT][FONT=ARIAL,]
Both microphone types worked well but each had shortcomings. The dynamic microphones weren't quite as rugged but they were less noisy. The carbon microphone needed a DC "bias" current to allow it to operate, where a dynamic microphone did not. The military adopted the dynamic microphones as standard.
Later on, when transistors were invented, a hybrid microphone was developed called an "amplified dynamic".
This revolutionary device utilized a dynamic microphone and a transistor amplifier so that it could be used in "biased" carbon type systems. They still weren't very rugged, but the improved sound quality overshadowed this. The early dynamic amplified microphones would break if you just dropped your headset.
There has been additional development with "electric" elements replacing the permanent magnet "dynamic" element. The ceramic electric element is much more rugged.
Now to the original question. If you were able to plug a military style unamplifed "dynamic" microphone into a civilian microphone jack, it would burn immediately because of the bias voltage. Thats why they use different jacks.
Helicopters were originally very "military" oriented. Since the military were the biggest customers, the audio systems were standardized. Even these days when military and civilian use is better balanced, alot of the tactical communications equipment used in the civilian (police/forestry/firefighting/news) still use the dynamic microphone standard. So I don't expect this to change in the near future. I have however seen a few pure "private" use helicopters converted to accept a "carbon" (or equivalent) microphone.
[/COLOR][/FONT][/COLOR][/SIZE][/FONT]
In the "old days" there were essentially 2 types of microphones use in aviation:
1) [FONT=inherit !important][FONT=inherit !important]Dynamic[/FONT][/FONT] Microphones: These were essentially a coil of wire wrapped loosely around a permanent magnet and connected to a membrane. Much like a speaker. When you talk into the membrane the sound waves vibrate the coil over the magnet and an electrical signal is generated which contains electrical fluctuations approximating the air pressure fluctuations produced by sound.
2) Carbon Microphones: Granules of a special carbon are contained in area behind a metal membrane. The metal membrane transfers the air vibrations caused by sound to the carbon granules. A DC voltage applied to the carbon granules is varied by the changing resistance offered by the vibrating carbon granules. [/FONT][FONT=ARIAL,]
Both microphone types worked well but each had shortcomings. The dynamic microphones weren't quite as rugged but they were less noisy. The carbon microphone needed a DC "bias" current to allow it to operate, where a dynamic microphone did not. The military adopted the dynamic microphones as standard.
Later on, when transistors were invented, a hybrid microphone was developed called an "amplified dynamic".
This revolutionary device utilized a dynamic microphone and a transistor amplifier so that it could be used in "biased" carbon type systems. They still weren't very rugged, but the improved sound quality overshadowed this. The early dynamic amplified microphones would break if you just dropped your headset.
There has been additional development with "electric" elements replacing the permanent magnet "dynamic" element. The ceramic electric element is much more rugged.
Now to the original question. If you were able to plug a military style unamplifed "dynamic" microphone into a civilian microphone jack, it would burn immediately because of the bias voltage. Thats why they use different jacks.
Helicopters were originally very "military" oriented. Since the military were the biggest customers, the audio systems were standardized. Even these days when military and civilian use is better balanced, alot of the tactical communications equipment used in the civilian (police/forestry/firefighting/news) still use the dynamic microphone standard. So I don't expect this to change in the near future. I have however seen a few pure "private" use helicopters converted to accept a "carbon" (or equivalent) microphone.
[/COLOR][/FONT][/COLOR][/SIZE][/FONT]
dillardrg
Pre-takeoff checklist
David Clark sells $50 adapters for RW to FW or FW to RW. They were $50 a couple of years ago when I bought 1.
ClimbnSink
Ejection Handle Pulled
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Airplanes should switch to the helicopter plug. Just one plug and most headsets have a shorter coiled cord. Makes ten feet of headset cable and two plugs seem annoying.