Icom IC-7400 Service Manual page 8

• 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
TUNER
(antenna tuner)
connector
Black belt
Blue
J1
belt
Black
J151
Blue
J121
Red
Soldering
points
Connect a frequency counter, then adjust
the frequency to be 64.00000 MHz.
J262
2LO IN
3 - 2
Shield cover
P2
(CHASSIS)
RF unit
J761
(MAIN unit)
CR-338
Supplied crystal
Red belt
RF unit
RF unit
L1901