Icom IC-7400, Service Manual, Page: 8 / 92

3 - 2
• CR-338 HIGH STABILITY CRYSTAL UNIT
By installing the CR-338, the total frequency stability of the
transceiver will be improved.
q
Remove the bottom cover as shown on the previous page.
w
Remove the 4 screws from the shield cover of the RF unit,
and disconnect P2 (CHASSIS) from J761 (MAIN unit), then
lift up the shield cover.
• There is an earth spring on the shield cover, so be careful
not to lose it when removing the cover.
e
Remove the 8 screws from the RF unit, disconnect J1, J121
and J151, then remove the RF unit.
r
Remove the supplied internal crystal and replace with the
CR-338.
t
Return the RF unit, J1, J121 and J151 to their original posi-
tions.
y
Connect a frequency counter to the J262, 2LO IN, then ad-
just the reference frequency to be 64.00000 MHz with the
L1901 on the RF unit.
u
Return the J262, shield cover, earth spring and bottom cov-
ers to their original positions.
Earth spring
Shield cover
RF unit
J761
(MAIN unit)
P2
(CHASSIS)
TUNER
(antenna tuner)
connector
Black belt
Blue
belt
J151
Blue
J1
Black
J121
Red
CR-338
Supplied crystal
Red belt
RF unit
Soldering
points
Connect a frequency counter, then adjust
the frequency to be 64.00000 MHz.
RF unit
J262
2LO IN
L1901