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PC headset with ICOM radio

Discussion in 'Microphones, Speakers & Audio Processing' started by KB1THM, Jul 29, 2010.

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  1. KB1THM

    KB1THM Ham Member QRZ Page

    I have an Icom IC-718. I want to be able to use my PC headset with it. Would buying one of those HEIL SOUND AD-1-I adapter cables work? I just wonder if it would supply the dc bias for the PC mic witch most of them are electret. Are Heli's mics electret mics? If they are then it would work. If anyone knows the answer please do reply to this post I would appreciate it. I want to have a cheap alternative to this hand mic.

    Brandon - KB1THM
     
  2. VK6DT

    VK6DT Ham Member QRZ Page

    Icom radios usually require a microphone "pre-amplifier" with a PC headset.

    I have a IC746Pro and a Plantronics PC headset. I wired a (kit) single transistor pre-amp to get the mic audio signal large enough to feed the radio. The mic gain is set to "maximum" on the radio. I had issues with RF feeding into the mic audio; until I tidied up the audio wiring layout and installed ferrite chokes at the pre-amp input & output. I also fiddled with the capacitor values in the circuit to find a stable operating condition. It may require some experimentation on your part.

    Best wishes
    VK6DT
     
  3. AC0FP

    AC0FP Ham Member QRZ Page

    ICOM radios come with an electret microphone and of course they provide the power source (DC bias) to run it, or any other electret microphone for that matter . The trick is getting the PC headset wired up to the 718 with the right cable connectors.

    The only way VK6DT post is correct is if the the "new" microphone for the 718 is a dynamic element type, not only would you need a "preamplifier" but an isolation capacitor to decouple the ICOM 718's microphone bias supply!

    73,

    fp :)
     
  4. KB1THM

    KB1THM Ham Member QRZ Page

    OK I got the answer from calling heli sound. They said to buy the "AD-1-IC" adapter and then I can use my PC headset.
     
  5. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    Well of course they would say that.

    I have wired many PC headsets to my 756 PRO and with the right combination of voltage dropping resistor and blocking cap you can get some amazing audio. For my setup, all done within the mic plug:

    solder a 4.7K resistor to pin 2 of the mic plug. leave the other end loose. Solder a 0.33uf cap (+ side to the mic socket) to pin 1 on the mic plug. Attach the (-) side to the loose end of the 4.7K resistor and connect this junction to the hot electret mic lead. Connect the ground of the mic element to pin 7 of the mic plug.

    That's all there is to it. Experiment with the cap value between 0.1uf to about 3.3uf until you get the sound you want. Changing the 4.7K resistor up or down will increase or decrease the output going in to the rig.

    If you don't want to cut the end of the headset, buy a 3.5mm stereo extension cord and cut it off and wire into the mic plug.

    Have fun, I use the headset while contesting and it trips the VOX nicely and I get many compliments on the audio.

    73,
    VE3TMT
     
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