Model:         IC-28A

 Division:      Amateur

 Note:          This service bulletin is meant for technical per-
                sonnel with experience working on solid state com-
                munications equipment.  Damage caused by im-
                properly installing this modification may cause
                ICOM to charge for subsequent repairs to the
                product.  ICOM does not warrant this modification.

 Bulletin #:    28Oct86-012

 Date:          October 28, 1986

 Subject:       Improve RX sensitivity 1 dB

 Procedure

  1.   Replace the following parts on the receiver board:

      Current        Part                New
      Part           Identifier          Part

      18pf 50V       C21                 12pf 50V
      8pf            C23                 9 pf 50V
      39pf           C108                56pf  50V
      Jumper         W5                  Remove



 Model:         IC-28H

 Bulletin #:    28Oct86-014

 Date:          October 28, 1986

 Subject:       Improve RF output power

 Procedure

  1.  Add R113 between IC-6 pin 1 and ground on the main board.

  2.  Remove and replace the following parts on the main board:

      Current        Component      New
      Part           Identifier     Part

      LA-233         L22            LA-235
      12pf 50V       C46            47pf 50V
      33pf 50V       C52            22pf 50V
      22pf 50V       C109           10pf  50V


 Model:         IC-28A/H

 Bulletin #:    28Oct86-015

 Date:          October 28, 1986

 Subject:       Improve S-meter gain

 Procedure

  1.  Remove and replace the following parts on the RX board:

      Current        Component      New
      Part           Identifier     Part

      33K            R37            27K
      1.5K           R45            2.7K
      47pf           C62            100pf

      This modification will increase the S-meter gain by 5dB



 Model:         IC-28A/H

 Bulletin #:    3Nov86-003

 Date:          November 3, 1986

 Subject:       Prevent birdies at 154.755 and 154.810 MHz

 Procedure

  1.  Cut the land between Pin 1 of IC-1 (MV87001-G) and R102 on
      the main board.

  2.  Install a 1 MicroHenry coil (1R0) between Pin 1 of IC-1 and
      R102 on the main board.

  3.  Install a .01 uf capacitor between Pin 1 of IC-1 and ground.

  4.  Cut the land between Pin 5 of IC-1 and C27.

  5.  Install a 1 Meg resistor between pin 5 of IC-1 and C27.