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  1. #1

    AFS intercom

    Will the Advanced intercom support an electret noise canceling microphone which requires 9- 17 volts for proper operation?

  2. #2
    What type of headset is it?
    Rob Hickman
    Advanced Flight Systems Inc.

  3. #3
    Pilot USA model1181T

  4. #4
    We have never had this question and I really don't know. We have used the intercom with all the standard headsets (Bose, Lightspeed) without any issues, we literally have hundreds of the intercoms in the field. If there was really something different about the Pilot USA headsets that made it not work with some intercoms I suspect that people would not buy them.

    Have you had the Headsets not work with other Intercoms or had reports that it does not work?
    Rob Hickman
    Advanced Flight Systems Inc.

  5. #5
    I have used the Pilot USA headsets with several intercom brands with no apparent problem. The issue is that my existing intercom, PS engineering 500EX, has one
    audio input intended for a com radio audio. So that requires an addition of an audio mixer board in order to hear AFS and GPS alarms. So I see that the AFS
    intercom has several aux audio inputs. I am considering replacing the existing with the AFS. However, The electret mike element data sheet indicates that 9-17
    volts is required to properly activate noise canceling. So I was wondering what voltage the AFS unit supplies to the mike element.

  6. #6
    Quote Originally Posted by neville View Post
    I have used the Pilot USA headsets with several intercom brands with no apparent problem. The issue is that my existing intercom, PS engineering 500EX, has one
    audio input intended for a com radio audio. So that requires an addition of an audio mixer board in order to hear AFS and GPS alarms. So I see that the AFS
    intercom has several aux audio inputs. I am considering replacing the existing with the AFS. However, The electret mike element data sheet indicates that 9-17
    volts is required to properly activate noise canceling. So I was wondering what voltage the AFS unit supplies to the mike element.
    Neville, it would use the same power source that you use with the PSE 500EX. To my knowledge, no intercom provides power to the headsets. What is traditionally done is that the headset has it's own battery pack or is powered by the aircraft power through a connection in a LEMO plug.

    I have a PSE 8000BT in my RV-10. It doesn't provide any power to my Bose and/or Lightspeed headsets. I have LEMO plugs that are wired to aircraft power. I also have the option of using batteries so I can take the headsets to other aircraft.

    My assumption is that Pilot USA should work the same way.

    bob
    Bob Leffler
    N410BL - RV10 - Flying
    http://mykitlog.com/rleffler

  7. #7
    The Pilot USA 1181T is not a complete noise cancelling headset. The mike element is a electret noise canceling element. The ear piece elements are a dynamic coil and are passive. A electret mike element has, in addition the
    actual electret element, a FET transistor amplifier which requires a supply voltage. The supply can be aircraft power or a battery. The supply must include a capacitor to pass mike audio into the intercom/comm radio and isolate the electret supply voltage. Noise canceling in an electrete element is accomplished by the physical construction and magnetizing effect of the element obtained a part of the construction prossess.

    Every intercom or comm radio I have ever worked on in 40 years of avionic/marine repair has some supply voltage to the mike element starting with the carbon elements of the old days,( but still in common use). Otherwise there would be no audio signal developed due to no changing current as the element changes resistance
    when impacted by the speakers changing sound waves.

    Most newer intercoms and radios supply voltage in the +/- 5 volt range.
    Last edited by neville; 06-27-2014 at 07:01 AM.

  8. #8
    Quote Originally Posted by neville View Post
    The Pilot USA 1181T is not a complete noise cancelling headset. The mike element is a electret noise canceling element. The ear piece elements are a dynamic coil and are passive. A electret mike element has, in addition the
    actual electret element, a FET transistor amplifier which requires a supply voltage. The supply can be aircraft power or a battery. The supply must include a capacitor to pass mike audio into the intercom/comm radio and isolate the electret supply voltage. Noise canceling in an electrete element is accomplished by the physical construction and magnetizing effect of the element obtained a part of the construction prossess.

    Every intercom or comm radio I have ever worked on in 40 years of avionic/marine repair has some supply voltage to the mike element starting with the carbon elements of the old days,( but still in common use). Otherwise there would be no audio signal developed due to no changing current as the element changes resistance


    when impacted by the speakers changing sound waves.

    Most newer intercoms and radios supply voltage in the +/- 5 volt range.
    You are correct. Most microphone bias voltages are +/- 5V. Telex's Airman series headsets are noise cancelling and use this voltage to accomplish it.

    As far as your headset with our intercom- Like Rob said, we have not received any complaints/concerns regarding any type of headset, nor the noise cancelling functions of said headsets with our intercom. If your headset is working just fine with your current intercom, I don't think I would have any concern with ours.

    Does the intercom you currently use have the 9-17 volt on the mic?
    Isaac Becktold

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