IC2410.9

     To anyone experiencing low audio with the ICOM 2410A/H, I
have just recently purchased one of these myself and ran into the
same exact problem.  After looking the unit over and determining
the same thing regarding an external mic and after a couple of
calls to ICOM, we determined the following things need to be
looked at:  
 
1.   Is the microphone an HM-56 or an HM-56A?  If it's an HM-56,
     then the 4 volt zener should be replaced with a 9.1 volt
     zener.  If it is an HM-56A, no change in the zener is
     required.  
2.   If the problem still persists after changing the diode, or
     if you have an HM-56A, I would recommend replaSing the
     microphone element with a Radio Shack (NO, I AM NOT
     KIDDING!!) Part No. 270-090 as the element that came with
     the ICOM does not have the frequency response
     characteristics required to produce the low end sounds that
     make up most of the volume.  Afteràreplacing that element,
     then touch up on the deviation controls R-5 and R-7 may be
     required.  
 
     NOTE:  The original microphone element in the ICOM mic has
     the outer body connected to the positive side of the
     circuit.  The Radio Shack element has the outer body
     connected to the negative side of the circuit.  Therefore,
     wire the element into the circuit accordingly.  
 
     I hope this helps out - it has done a terrific job for me. 
The ICOM now sounds simply marvellous!  (Say this line like Billy
Crystal!)  
 
     Thanks to Gary (KF7XV) and LynDel (AA7DG) at ICOM Tech
Support for their excellent product knowledgeand technical
expertise.  
 
     Please note that this change is not recommended or supported
by ICOM at this time.  
 
          73!
 
          Brett N9LOU