Furuno FELCOM 12 Service Manual page 77

Synthe 1st-1Local, 2Local, RX 2nd Local NG
Synthe 1 st – 1 Local
When the PLL (U15) unlocks, LD(Lock Detect) line becomes to "L" level. The
CPU 2 receives the unlock signal and generates the NG indication.
Synthe 1 st – 2 Local
When the PLL (U10) unlocks, LD(Lock Detect) line becomes to "L" level. The
CPU 2 receives the unlock signal and generates the NG indication.
Synthe RX 2 nd Local
When the PLL (U34) unlocks, LD(Lock Detect) line becomes to "L" level. The
CPU 2 receives the unlock signal and generates the NG indication.
UNLOCK 1 and 2 signals are also used to generate 5V TX ON signal which controls the
TX circuit on the TX board. When the PLL, either of U10 or U15 unlocks, transmission
is automatically stopped.
1626.5-1646.5MHz
TX
1530-1545MHz
U34
PLL 3
LD
U10
730MHz
PLL 2
(MAIN)
LD
U15
900MHz
PLL 1
(SUB)
LD
VCXO
(15.6MHz)
RF CON (16P0147)
VCXO CNT
TX Lo
1626.5-1646.5MHz
S-DATA
BPSK
RX Lo
1620.05-1635.05MHz
Q12
90.05MHz
50kHz IF
Q25
90.1MHz
U5
Q39
FL7 FL2
U6
UNLOCK 2
FL1
U6
UNLOCK 1
UNLOCK 3 J2-12
RX Lo
DIV
TX Lo
J2-11
J2-10
5V TX
J7-2
U7/8
6-9
To terminal unit
UNLOCK 3
UNLOCK 2
CPU 2
(U23)
UNLOCK 1
J10-12/10/11
CPU (16P0148)
5V TX ON
TX (16P0157)