Tait TB7100, Service Manual

Page: 165 / 370

TB7100 Service Manual Frequency Synthesizer Fault Finding 167
© Tait Electronics Limited October 2005
Figure 11.8 Measurement points for the VCO and related circuitry in UHF radios
+5V
DEC
P
IN6O
F
Q5001
PIN
6
OF
Q5001
P
IN3O
F
Q506
PIN
3
OF
Q506
Q508
AND
R593
Q508
AND
R593
P
IN6O
F
Q506
PIN
6
OF
Q506
BASE
OF
Q5100
BASE
OF
Q5100
TX
POR
T
TX
POR
T
RX
POR
T
RX
POR
T
P
IN4O
F
IC5100
PIN
4
OF
IC5100
SIGNA
L
T
YPES
RF ANALOG CLOCK DIGIT
A
L
PLL
LOOP
FIL
TER
AND
SUMMER
FIL
TERING
OF
SUPPL
Y
FOR
VCO
CIRCUITR
Y
FREQUENCY
SYNTHESIZER
PLL
F
EEDBACK
LOOP
VOL
T
AGE
RECEIVE VCO
TRANSMIT
V
CO
TRANSMIT
BUFFER
AMPLIFIER
AND
COUPLER
5
V
S
WITCH
TR
SWITCH
SYN
T
X
L
O
SYN
RX
LO1
TRANS- MITTER
RECEIVER
DIGIT
A
L
BOARD
DIG
SYN
T
R
S
W
DIG
SYN
E
N
INVER
TER
RECEIVE
BUFFER
AMPLIFIER
AND
COUPLER
VIA
T
O
CHECK
DIG
SYN
TR
SW
VIA
T
O
CHECK
DIG
SYN
T
R
SW
R103
JUNCTION
O
F
C541
AND
R
547
JUNCTION
OF
C541
AND
R547
R577
R544
+3V0
A
N
L506
3V
SUPPL
Y
R593
R585