TK-5810
(
BG
)
/5810H
(
BG
)
26
SW
Q503
SW
IC509
IC517
MIC
MI2
MM
LPF
IC501
ASIC
IC708
SW
DET
D500,D501
Q501,Q502
DSP
IC701
Q505
IC512
IC505
LPF
IC514
IC502
IC514
IC519
VCXO
TX-RX UNIT
VCO
IC524
IC512
MM2
DAC
Fig. 7 Audio band and Base band circuit
CIRCUIT DESCRIPTION
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.
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
Q211
Noise Amp
FM IC
D216
DET
IC708
ASIC
Fig. 6 Squelch circuit
Fig. 5 Audio Amplifi er circuit
IC708
IC701
ASIC
DSP
LPF
SW
AMT /SCSW
DBSW
/SPK_MUTE
PA
SW
DAC
SW
SW
IC503
IC506
IC510
IC515
IC517
IC516
Q506
IC518
IC522
Int/Ext
SP
PA
SP
IC522
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
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.