Icom IC-775 - 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