Kenwood TM-321A Service Manual page 12

TM-321A
DESCRIPTION
OF
ELEMENTS
FINAL UNIT (X45-1360-11)
Function
Element
Description
Qi
Power amplifier
Boosts power to the required level. M57774.
D1
Protection against
reverse
power connection
D2,D3
Transmit/receive select ON during transmit.
D4
High-frequency output voltage
level detect Detects high-frequency output level and controls output
in
the
APC
circuit.
D5 Reflected power detector Adjustable with
VR1.
CONTROL UNIT
(X53-3040-13)
Element
Function
Description
IC1
6V
AVR
{C2 Reset IC Outputs Reset
signal and
detects low voltage.
IC3
Microprocessor
Controls frequencies and general set functions.
Converts digital
data
from IC3 (P40 to P43, P50 to P53) to
an
analog tone
IC4 Tone
DAC
frequency.
Qi
Squeich switching
Switches
squelch
on/off when remote
controller
is
connected.
Q2
Switching
Controls the microprocessor''s backup detect input.
D1
Reverse current protection Protects against external voltage applied to pin
5
of the microprocessor.
D2(1/2)
Microprocessor protection
Protects against static surge.
D2(2/2)
Voltage drop
D3(1/2) Reverse current protection Prevents current from flowing to the
backup battery.
D3(2/2) Reverse current protection
Prevents
backup battery current from flowing to inappropriate circuits.
D4
Microprocessor protection
Protects against static
surge.
TX-RX
UNIT (X57-3170-10)
Element
Function
Description
IC1
8V
AVR
IC2
PLL
Pulse-swallow type phase-locked loop.
IC3 Shift
register Controls,
band
switching,
and electronic volume functions.
IC4
AF
amplifier Speaker output.
Qi
High-frequency amplifier Operates in
receive mode (144MHz).
Q2
First mixer
Converts the
received frequency into the 30.825MHz.
Q3
High-frequency amplifier
First
intermediate frequency amplifies.
04
AF
muting
Operates when
CTCSS
is ON,
when
SOS
is
high,
and
in
transmit mode.
Q5
8R
switching
ON
in
receive mode.
06 8T
switching
ON
in
transmit mode.
Q7
8T
switching control ON
in
transmit mode.
Q8
8R switching control ON
in
receive mode.
Q9
Constant-voltage control
5V
power supply for
PLL.
Q11
High-frequency amplifier
Amplifies 12.8MHz to the level required for the
PLL
Q13,014
PLL
low-pass
filter
Q15
PLL
unlock control ON when the
PLL
is
ocked.
Q16 Amplifies
the
VCO
output to the level
required
for the
PLL.
High-frequency amplifier
Q17
High-frequency amplifier
Amplifies
the
VCO
output to the
level
required
for input to the 1st
IF
mixer (Q2)
019
Transmit driver (power amplifier) Amplifies to the
level
required for input
to the final unit power module.
Q20
+
B
(DB)
AVR
of Q19
Operates
in transmit mode.
13
TM-321A
DESCRIPTION
OF
ELEMENTS
FINAL UNIT (X45-1360-11)
Function
Element
Description
Qi
Power amplifier
Boosts power to the required level. M57774.
D1
Protection against
reverse
power connection
D2,D3
Transmit/receive select ON during transmit.
D4
High-frequency output voltage
level detect Detects high-frequency output level and controls output
in
the
APC
circuit.
D5 Reflected power detector Adjustable with
VR1.
CONTROL UNIT
(X53-3040-13)
Element
Function
Description
IC1
6V
AVR
{C2 Reset IC Outputs Reset
signal and
detects low voltage.
IC3
Microprocessor
Controls frequencies and general set functions.
Converts digital
data
from IC3 (P40 to P43, P50 to P53) to
an
analog tone
IC4 Tone
DAC
frequency.
Qi
Squeich switching
Switches
squelch
on/off when remote
controller
is
connected.
Q2
Switching
Controls the microprocessor''s backup detect input.
D1
Reverse current protection Protects against external voltage applied to pin
5
of the microprocessor.
D2(1/2)
Microprocessor protection
Protects against static surge.
D2(2/2)
Voltage drop
D3(1/2) Reverse current protection Prevents current from flowing to the
backup battery.
D3(2/2) Reverse current protection
Prevents
backup battery current from flowing to inappropriate circuits.
D4
Microprocessor protection
Protects against static
surge.
TX-RX
UNIT (X57-3170-10)
Element
Function
Description
IC1
8V
AVR
IC2
PLL
Pulse-swallow type phase-locked loop.
IC3 Shift
register Controls,
band
switching,
and electronic volume functions.
IC4
AF
amplifier Speaker output.
Qi
High-frequency amplifier Operates in
receive mode (144MHz).
Q2
First mixer
Converts the
received frequency into the 30.825MHz.
Q3
High-frequency amplifier
First
intermediate frequency amplifies.
04
AF
muting
Operates when
CTCSS
is ON,
when
SOS
is
high,
and
in
transmit mode.
Q5
8R
switching
ON
in
receive mode.
06 8T
switching
ON
in
transmit mode.
Q7
8T
switching control ON
in
transmit mode.
Q8
8R switching control ON
in
receive mode.
Q9
Constant-voltage control
5V
power supply for
PLL.
Q11
High-frequency amplifier
Amplifies 12.8MHz to the level required for the
PLL
Q13,014
PLL
low-pass
filter
Q15
PLL
unlock control ON when the
PLL
is
ocked.
Q16 Amplifies
the
VCO
output to the level
required
for the
PLL.
High-frequency amplifier
Q17
High-frequency amplifier
Amplifies
the
VCO
output to the
level
required
for input to the 1st
IF
mixer (Q2)
019
Transmit driver (power amplifier) Amplifies to the
level
required for input
to the final unit power module.
Q20
+
B
(DB)
AVR
of Q19
Operates
in transmit mode.
13