icom 2m-8 mic Flex-5000

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  • Updated 1 year ago

I am configuring an adapter cable for a Icom SM-8 Desk Mic to Flex front Microphone plug.

icom pinout

1   Mic V+

2 +Vc

3 Mic freq +/-

4 Up/Dn

5 Ptt

6 Ground Ptt

7 Ground (mic)

8  Mic AF

Since Pins 1,3,4 are not used I gather I will need to bridge a resistor from Pin 2 to Pin 8 for the Mic bias voltage..   The thing that I want to make sure of is the grounds.  I think all I will need to do is make an adapter with a 2k ohm resistor across Pin 2 to 8.  pins 1,3,4 are not used,  and I will be in business.

The flex manual pinout is

1. not connected

2 +5vdc

3 not used

4 not used

5 Chassis ground

6 Ptt+

7 Mic (-)

8 mic (+)

I found a link on how to make the heil ic headset which runs on the Icom radios as connecting pin 5 & 7 to shield of the microphone wire.  Don't quite understand what they mean.. http://kc.flexradio.com/KnowledgebaseArticle50372.aspx


Brent  K5EDI

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Posted 1 year ago

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I figured out the pinout,  the sm-8 element gets its voltage from pin 2 +vdc rather than a different wire.  I just made an adapter so I would not have to change the icom plug.  Note, this is different than a heil headset which has a phantom voltage..  There are many forums which tended to get me very confused.   This will likely work on other icom mic's if the schematic is similar.  And it works very well on the Flex, had to turn down the gain quite a bit.. 

sm-8 manual :   https://www.manualslib.com/manual/953851/Icom-Sm-8.html



Flex 5000 front plug  pins                    Icom sm-8 pins


  1. not connected 

  2.                                                 2

  3. Not connected

  4. Not connected

  5.         Ptt -                                 6

  6.         Ptt                                    5

  7.    Mic  (-)                                  7

  8.    Mic (+)                                  1