Kenwood TK-5810 Service Manual page 26

TK-5810 BG
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3-6. Audio Amplifi er Circuit
Audio processing (high-pass filter, low-pass filter, de-
emphasized and so on) at FM mode and decoding at P25
mode are processed by DSP. Audio signal from IC708,
IC701 goes through Low-pass fi lter (IC503). The signal then
goes through mute switch (IC506), amplifier (IC510), and
switch (IC515), and electronic volume control (IC517), and
pre-amp (IC516), and audio mute switch (Q506), and audio
route switch (IC518), and audio power amp (IC522).
While busy, /SPK_MUTE becomes High, turn Mute
switch (Q506) off, and signal is fed to AF Power Amp (IC522).
While Non-busy, /SPK_MUTE is become Low, turn Mute
switch (Q506) on, then there is not AF output.
IC708 IC503
ASIC LPF
DSP
IC701
4. Transmitter System
4-1. Audio Band Circuit
The signal from the microphone goes through the mute
switch (Q503), the MIC-Mute signal (MM) becomes Low,
and then mute switch (Q503) is turned off. The signal
MIC
MI2
IC502
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/5810H BG
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CIRCUIT DESCRIPTION
IC506 IC510 IC515
SW
AMT /SCSW DBSW
Fig. 5 Audio Amplifi er circuit
Q503
SW
IC512 IC512
MM
Q505
SW
D500,D501
Q501,Q502
MM2
IC514 IC514
LPF
Fig. 7 Audio band and Base band circuit
3-7. Squelch Circuit
It amplifies the demodulated noise signal from FM IC
(IC209) after fi ltering through BPF circuit. Then, the ampli-
fi ed signal is converted to DC signal by the detection circuit.
The converted signal is fed to the ASIC (IC708).
IC209
FM IC
IC517 IC516
SW DAC
from microphone goes through summing-Amp (IC512) and
MIC-AGC (IC512, Q501, Q502, D500 and D501), and goes
through audio route switch (IC509), and amplifi ed by MIC-
Amp IC505. LPF IC501 works as anti-aliasing fi lter.
IC509 IC505
SW
DET
IC519
IC517 IC524
DAC
Q211
Noise Amp D216
DET
Fig. 6 Squelch circuit
Q506 IC518
SW SW
/SPK_MUTE PA
IC501 IC708
LPF ASIC
DSP
IC701
TX-RX UNIT
VCXO
VCO
IC708
ASIC
Int/Ext
IC522 SP
PA
IC522 SP