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DTMF Mic for IC-910 & IC-746 Easy Mod - W2EFT

Discussion in 'General Technical Questions and Answers' started by W2EFT, Aug 30, 2008.


How did you find this micophone modification?

  1. Worked great as described.

  2. $65.00 is a little pricey for a handmic Icom!

    0 vote(s)
  3. Wires are getting smaller every year, or my arms are shorter.

    0 vote(s)
  4. Find it worked with other Icom rigs. (Please let us know!)

    0 vote(s)
  5. Forgot to put the plug case over the wire my first time.

    0 vote(s)
  6. I would have paid the extra $5.00 if Icom just offered it.

Multiple votes are allowed.
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  1. W2EFT

    W2EFT Ham Member QRZ Page

    DTMF MIC MOD FOR IC-910 & IC-746​

    I've owned the 746 and 910 for years and have never understood why I spent $1,800.00 for a nice rig but needed to use my HT to program my repeater controllers or access my own IRLP. I found an answer and it works great. I bought the Icom HM-118TN. It's a commercial grade Motorola feeling Icom hand mic, has a backlit key pad and Up /Down control buttons. The obvious issue of course is that it has the modular termination. Before you start, it will be helpful to download the manuals for the IC-2200H and and print the mic wire diagram on page 2. Print the mic pin diagram for the IC-910 on page 15. Now you can make notes on both as the pin designations use the same terminology.

    After carefully stripping back the rubber casing and removing the many string strain supports, you will find the pin#)colors as follows: 1)Red: +8V DC, 2)Brown: Channel Up/Dwn, 3)Yellow: 8V Control, 4)Green: PTT, 5)Copper: Mic GND, 6)White: Mic Audio, 7)Grey: GND, 8)Blue: Data IN. After the mod, you will not be using yellow or blue wires, but the touch tone pad will operate, it will be back lit, and the UP / Down buttons will work also.

    On your 8 pin mic connector, attach the following: 1)White: Mic, 2)Red: +8V DC, 3)Brown: Up/Down, 4)-unused-, 5)Green: PTT, 6)Grey: PTT GND, 7)Copper: Mic GND, 8)-unused-.

    I have tested the mic on the IC-910 and IC-746 at low and high levels and the touch tones were accepted my my controller at all levels. The gain of the mic sounds better with the level high on the radio.

    Edward F Thomas, W2EFT
  2. AB8ZL

    AB8ZL Ham Member QRZ Page

    Sounds like it should work on an IC 7000 also.
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