Power Supply - Kenwood TK-3360 Service Manual

6-5. Key Input
Keys and channel selector circuit.
The signal from the keys and channel selector are direct-
ly input to the MCU, as shown in Figure 10.
Selector
IC809
MCU
57
EN4 PTT
58
EN3 ENG KEY
59
EN2 SIDE1
61
EN1 SIDE2
Fig. 10 Key input
7. Signaling Circuit
7-1. Encode
■ Low-speed data (QT, DQT)
Low-speed data is output from pin24 of the MCU. The
signal passes through the low pass CR fi lter, and goes to
the audio processor (IC812). The signal is mixed with the
audio signal and goes to the VCO and TCXO (X1) modulation
input after passing through the D/A converter inside the au-
dio processor (IC812) for BAL adjustment.
IC809
MCU
24
LSDO
1
TXTONE
2
D/A
SIDETONE
converter
IC817
Fig. 11 Encode
■ High-speed data (2-tone, DTMF)
High-speed data (HDS) is output from pin 1 of the MCU.
HDS deviation made by an adjustment in the MCU is passed
through the low pass CR fi lter and then applied to the audio
processor (IC812).
The signal is mixed with the audio signal and goes to the
VCO and TCXO. The side tone is output from Pin 2 of the
MCU. The signal passes through low pass CR fi lter and D/A
converter, and goes to the audio power amplifi er. The level
is controlled by the MCU.
CIRCUIT DESCRIPTION
Q815
PTT
SW
Level
converter
ENG
SW
37
68 SIDE1
69
70
SIDE2
IC812
Audio Processor
18 24
VCO
ALT MOD2
21 23
TCXO
MIC MOD1
AF
AMP
■ MSK
The MSK signal is generated in the audio processor
(IC812). The signal passes through the D/A converter (inside
the audio processor: IC812) and is routed to the VCO. When
encoding the MSK, the microphone input signal is muted.
7-2. Dceode
■ QT/DQT
The output signal from the IF IC (IC401) enters the MCU
(IC809) through IC812. IC809 determines whether or not
the QT or DQT matches the preset value, and controls the
AFSW and speaker output sounds according to the squelch
results.
■ 2-tone
Part of the received AF signal output from the IF IC (IC401)
passes through an audio processor (IC812) goes to the oth-
er AF amplifi er IC808 and 816, is compared, and then goes
to IC809. IC809 checks whether or not the 2-tone data is
necessary. If it matches, IC809 carries out a specifi ed opera-
tion, such as turning the speaker on.
■ MSK (Fleet Sync)
The MSK input signal from the IF IC (IC401) goes to
IC812. The decoded information is then processed by the
MCU.
■ DTMF
The DTMF input signal from the IF IC (IC401) goes to
IC812. The decoded information is then processed by the
MCU.

8. Power Supply

There are fi ve 5V power supplies and three 3.3V power
supplies: 50M, 50V, 50C, 50R, 50T, 33M, 33MSC and 33BC.
50M and 33M are always output while the power is on.
33MS is always output, but turns off when the power is
turned off, to prevent malfunction of the MCU.
50C is a common 5V and is output when SAVE is not set
to ON.
50R is 5V for reception and output during reception.
50T is 5V for transmission and output during transmis-
sion.
50V is 5V for the SP/MIC connector.
33B is 3.3V for the audio processor (IC812).
TK-3360
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