Icom ic-775 Service Manual page 8

CR-282 HIGH-STABILITY
CRYSTAL
UNIT
By replacing the original crystal unit with this
unit,
the
total
frequency
stability
of
the transceiver
will
be improved.
CR-282 frequency
stability:
±
0.5
ppm
(-30°C
to -i-60°C:
-22T
to
-M40T)
®
Remove
the top
and bottom covers as described on
p.
2-1.
(D
Remove
10 screws from
the
PLL
unit
and
the ribbon
cabie from J11; then
turn
over the
PLL
unit to
see
the
reverse
side. (Fig.
1)
d) Unsoider the leads
of
the
installed crystal,
then
remove
the
crystal.
-
Use
a desoldering
braid.
@
Unsolder
the 4
positions
on
the
PLL
unit
where
the
CR-282
will
be
installed.
(D
Install
the
CR-282
in
the
PLL
unit,
paying
attention to
orientation.
-
Symbols on
the bottom
of
the
CR-282
must be
identically
matched
with
symbols on
the P.C. board.
(D
Bend
the leads
of
the
CR-282
at the
foil
side of
the P.C.
board
and
soider
them
as
shown
in
figure
2
at
right.
®
Trim the ieads
even
with
the soider
points.
(D
Replace the
PLL
unit,
ribbon cabie
and
covers.
After
changing
the crystal
unit,
frequency adjustment
is
necessary
with
L4 on
the
PLL
unit.
-
Refer
to
p.
5-2
for
adjustment
details.
NOTE: The CR-282
is
an oven-heat-type
crystal
unit,
and
the specified
frequency
stability
described
above
is
guar-
anteed
1
min. after
power ON.
Ribbon
cable
(Fig. 1)
Solder
points
(Fig.
2)
2-4