Back side of display board:
I D507 D504 ___
I ___ ___ I___I I
I I___I I___I -- + --
I D506 Q506 . . I I
I _o_------ _o_ J I hole for
I I___I I I___I . I on/off-vol
I o o I o o I control
I I I I__________________
I -----K---------- I
I add diode: 1N914 or equiv. I
Connect diode between top lead of D506 and lower right lead of
Q506 as shown.
A surface mount diode may be added right of Q506 at J. note that the
.___. are the same trace, while above the J is the center pole.o
. Note that this diode is 1906-0336, "-" at bottom, both "+" at top.
D506 may be absent. If not, remove it.
Reset CPU if needed.
A friend did this and his IC-2GAT can now transmit 138 to 178 MHz (no
RF power output measurements were made). He did no retuning, and did
not have to reset the CPU. He used a tiny axial-lead glass diode,
replaced its leads with wire-wrap wire, and encased it in shrink-tube.
The operation requires a super-tiny soldering iron. Observe CMOS
soldering precautions: Unplug the iron and ground the tip before
touching the circuit.
The 2GAT mod is really...
Remove D 504 which is orginally a 1SS196 and replace it with a 1SS184
which is a dual diode. The service manual componet symbol shows the dual
diode but lists the 196.