ICU4AT

From ICOM Service Bulletin 23288-002 for ICOM ICu4-AT.
Serial # affected:  Above 1010

On some radios, the unit will go into unlock condition indicated by a "U"
in the display during transmit at high power using standard short antenna.
Some radios will NOT unlock, but will have severe noise on the transmit audio.

Problem is caused by RF energy being recified and causing bad data in the
PLL system and RF overload in the VCO circuit.

1.  Remove front cover. (4 bottom screws, 1 side screw) *

2.  Gently lift 4 disc capacitors located on the chassis B lid to facilitate
    placement of Copper conductive tape.

3.  Install a piece of Copper tape (1.5" x 3/8") from VCO enclosure to chassis
    "B" lid.  (bridging a 1.5" long narrow gap between these assemblies.)

4.  Solder each corner of Copper tape and gently re-flatten capacitors onto
    tape.  (careful not to short capacitors to tape)

5.  Make certain that the ground spring on DTMF board (already there) makes
    firm contact with chassis B lid, when the front cover is replaced.
    Clean contact area on the chassis B lid where the ground spring contacts.
    There must be no impurities on this surface.

6.  Re-assemble unit and check at HIGH RF output on 440, 445, 449 MHz to make
    sure little or no RF feedback occurs.

7.  It's Done !

*  WA6ZTY's note. Cover does not come off readily, gently work top of radio
   upward out of case for about 1/16 to 1/8", that should release front cover
   tabs so that cover can hinge open.  Be gentle with cover.