38
7
INSTALLATION AND CONNECTIONS
■ 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 in the previous
diagram.
w Disconnect W2 from J4401 (MAIN unit) and W3
from J4201 (MAIN unit).
e Remove 9 screws from the PLL unit, disconnect P4
from J201 (MAIN unit) and P2 from J401 (MAIN
unit), then remove the PLL unit.
r Remove the supplied internal crystal and replace
with the CR-338.
t Return the PLL unit, plugs and flat cables to their
original positions.
y Adjust the reference frequency at C16 using a fre-
quency counter if desired.
• Connect the frequency counter to P 2 (PLL unit).
u Return the bottom cover to its original position.
W 3
W 2
J 4201
J 4401
P 4
J 201
J 401
P 2; Frequency check point
(Connect a frequency counter
and adjust the frequency to
64.00000 MHz with C 16.)
C 16
MAIN unit
PLL unit
■ Optional IF filters
Several IF filters are available for the IC-78. You can
install 1 filter for 455 KHz IF. Choose the appropriate
filter for your operating needs. (pgs, 21, 22)
D Installation
q Remove the bottom cover as shown on the p. 48.
w Remove 7 screws, connection cable p1 from J1, p5
from J701, W4 from J4101 and W5 from J4001 and
2 Tr-clampers as shown in the diagram below.
e Install the de-
sired 455 KHz
filter as shown
in the diagram
at right.
r Mount the filter
with the sup-
plied washers
and nuts.
t Solder the 4
leads.
y Return the
MAIN unit and
bottom cover to
their original po-
sitions.
After filter installation, specify the installed filter
using
initial set mode
. (p. 33) Otherwise, the in-
stalled filter will not function properly.
