28
TK-5710
(
B
)
/5710H
(
B
)
CIRCUIT DESCRIPTION
4-3. Drive Amplifier Circuit (From T/R switch to
Power module)
The transmit signal passing through the T/R switch
(D435) is amplified by the two drive amplifiers (Q150,
Q151). The transmit signal from the drive amplifier (Q151)
passes through a 3dB attenuator and is fed to the power
module .
4-4. Final Amplifier Circuit (From Power module to
Antenna output): TK-5710 (B)
The transmit signal from the TX terminal (CN1) of the final
unit (X45-375) is amplified by the power module (IC2).
The signal amplified by the power module passes
through the antenna switch (D1, D12, D3 and D11), CM
coupler and low-pass filter, then it is fed to the antenna.
CM coupler is a line for detecting forward wave and
reflected wave.
Forward wave is detected by D5, and is converted into
Fig. 7
Audio band and Base band circuit
DC voltage. The converted DC voltage is fed to the APC
comparator (IC1), and is compared with the PC voltage, then
is output from the OUT-B terminal (pin 7) of IC1 as an APC
voltage. The APC voltage controls the gate voltage of the
power module (IC2), and keeps transmission output stable.
If an abnormal antenna load is connected, reflected wave
is detected by D6, and output voltage (DC voltage) is fed to
the APC comparator (IC1). The transmission output is
reduced more as this DC voltage rises.
T/R
SW
D435
3dB
Attenuator
POWER
MODULE
Drive AMP
Q150
8T
Drive AMP
Q151
Fig. 8
Drive amplifier circuit
FC
SW
MUTE
MIC
5C
MO
MB
5C
RST
MCO
MCO
VDD
Q723
3.3A
5C
5C
5C
5C
5C
8C
3.3A
SW
Ao
3.3A
IC720
Ai
Ao
TXO(SCR)
Ai
STXI(SCR)
ATXI(ANI)
ATT
AGC
Q715
Q716
SUM
IC733
X400
VCXO
Q413,
Q414,
Q416
VCO
SW
Q720
DET
D727,D728
CODEC
IC724
IC715
DSP
IC738
DAC
IC719
IC729
(2/2)
IC719
(1/2)
IC735(2/2)
IC718
(1/2)
Fig. 9
Final amplifier circuit: TK-5710 (B)
ANT
D6
APC
D5
D1,D3,
D12,D11
TX(CN1)
LPF
ANT
SW
FWD
DET
REFL
DET
POWER
MODULE
FINAL UNIT (X45-375)
+B
8T
PC
8T
VR1
IC2
IC1
CM
COUPLER