Model:         IC-Micro 4AT

 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 worn-out this modifica-
                tion.

 Bulletin #:    23288-002

 Date:          August 19, 1988

 Subject:       Some Micro 4ATs go into PLL unlock (indicated by
                "U" on the display) during transmit at high power
                using the supplied antenna.  Other radios will NOT
                unlock but will have severe noise on the transmit
                audio.

 Information:   The problem is caused by RF energy causing bad
                data in the PLL system and RF overload in the VCO
                circuit.

 Procedure

      Contact ICOM's Service Department to have this problem cor-
      rected.