Transmitter System; Audio Circuit; Modulation Circuit - Kenwood TM-V71A Service Manual

D164,165 RF AMP
LPF D187,189 Q363
ANT
SW
AIP
SW
IC576
Q400
RF AMP
Q408
AIP
SW
IC576
Q450

2-5. Audio Circuit

The detected band A audio signal is amplifi ed by Q810
and de-emphasized by Q806. The band B audio signal is
amplified by Q811 and de-emphasized by Q807. One of
these audio signals is selected with a cross point switch
(IC806). The signal passes through the electronic volume
IC801
J801
AF AMP
(SP1)
J802
(SP2)
ATT

3. Transmitter System

3-1. Modulation Circuit

The audio modulation input from the microphone is
amplifi ed by IC802. After the DTMF signal and 1750Hz tone
signal generated by the MPU are switched with IC806, they
are mixed by IC803. After the signal amplified by IC802
is switched by IC806, it is amplifier by IC803. The signal
is then pre-emphasized by Q805 and Q808, and its level
is adjusted by IC804. The resulting signal goes to each of
CIRCUIT DESCRIPTION
BPF BPF BPF
D378,379 D375,376 RF AMP D370,371
L377 L375 L370
Q362
IC667
MPU D/A
IC918
BPF BPF BPF
D423,424 D420,421 RF AMP D415,416
L422 L420 Q407 L415
IC667
MPU D/A
IC918
Fig. 3 Band A and Band B UHF receiver circuit
IC804
E VR
Q816 Q804 Q803
Fig. 4 Audio circuit
BPF BPF
D367,368 D364,365 MIXER
L368 L366
Q361
45.05MHz
1st Local OSC
Band A
BPF BPF
D412,413 D409,410 MIXER
L413 L411 Q406
49.95MHz
1st Local OSC
Band B
(IC804), is amplifi ed by the AF amplifi er (IC801), and is then
fed to the speaker or the external speaker jack.
CTCSS and DCS signals that pass through the filter
circuit (IC805) go to the MPU (IC918) for CTCSS and DCS
decoding.
DE-EMPHASIS A
Q806 Q810
IC806
Cross
Point
Q807 Q811
SW
DE-EMPHASIS B
BEEP
IC805
1/2
DTMF
IC918
MPU
IC805
MUTE1
1/2
MUTE2 CTCSS Filter AMP
the band A and band B VCOs as a modulation signal. The
TONE/ DCS signal generated by the MPU is fed to IC803.
The signal amplifi ed by IC803 is distributed and the level is
adjusted by IC804. The modulating signal goes to each of
the band A and band B VCOs and the reference oscillation
circuit.
TM-V71A/V71E
X486
45.505MHz
MCF IF AMP
2nd Local OSC
XF486 Q495
FM IC
IC486
CF
Wide
CF
Narrow
16.8MHz Q547
TCXO Tripler
X66 x3
MCF IF AMP
2nd Local OSC
XF546 Q551
FM IC
IC546
CF
Wide
CF
Narrow
IC486
FM IC (A)
IC666
Multi
SW
IC546
FM IC (B)
Band A
AF
Band B
AF
5