Kenwood TK-8102 Service Manual page 13

TK-8102
IC1 : PLL IC
PLL
DATA
16.8MHz
Unlock Circuit
During reception, the 8RC signal goes high, the 8TC sig-
nal goes low, and Q29 turns on. Q31 turns on and a voltage
is applied to the collector (8R). During transmission, the
8RC signal goes low, the 8TC signal goes high and Q30
turns on. Q33 turns on and a voltage is applied to 8T.
The CPU in the control unit monitors the PLL (IC1) LD
signal directly. When the PLL is unlocked during transmis-
sion, the PLL LD signal goes low. The CPU detects this
signal and makes the 8TC signal low. When the 8TC signal
goes low, no voltage is applied to 8T, and no signal is trans-
mitted.
Q31
8R
SW
Q29
SW
8RC
Fig. 7 Unlock circuit
MIC IC21(1/2)
MIC/IDC
NJM2100V
MIC KEY
INPUT
IC3
D/A
CONVERTER
M62363FP
X1
TCXO
16.8MHz
12
CIRCUIT DESCRIPTION
5kHz/6.25kHz
1/N
Phase
comparator
REF
OSC
1/M
5kHz/6.25kHz
8C
Q33
8T
SW
Q30
SW
8TC
LD
IC6 IC1
CPU PLL
PLL lock
: LD "H"
IC4
IC22
Splatter
SUM AMP
FILTER
NJM2902V
NJM2904V
IC6 IC3
D/A
CPU
CONVERTER
784214GC
M62363FP
Q20
Q11 Q15
VCO BUFFER RF
2SC4649
2SK508NV 2SC5108
(N,P)
(K52) (Y)
IC1 Q3
RF AMP
PLL
2SC4649
MB15A02
(N,P)
Fig. 8 Transmitter system
LPF
D10,12
Charge
pump
D9,11
Fig. 6 PLL circuit
Transmitter System
Outline
The transmitter circuit produces and amplifies the de-
sired frequency directly. It FM-modulates the carrier signal
by means of a varicap diode.
Power Amplifier Circuit
The transmit output signal from the VCO passes through
the transmission/reception selection diode (D19) and ampli-
fied to a specified level of the power module (IC101) by the
drive block (Q23, Q25 and Q39). The amplified signal goes
to a low-pass filter. The low-pass filter removes unwanted
high-frequency harmonic components, and the resulting sig-
nal is goes the antenna terminal.
IC3 IC4
D/A
BUFFER
CONVERTER
NJM2902V
M62363FP
Q39 Q23
RF AMP
RF AMP
2SC5108
2SC3357
(Y)
Q11 Q3
TX VCO AMP
Q15
BUFF
AMP
Q10
RX VCO
Q7,12
T/R SW
Q25 IC101
POWER AMP
RF AMP
S-AU27AM(K3)
2SC3357
ANT