Kenwood Tk 780h1 Owners Manual

							21
TK-780 / H
INSTALLATION
1-3. Data Equipment Connection
The jumpers must be set to either one for each function.
Otherwise, the radio will not work properly.
AHK/BUSY
R64 (0Ω) R18 (0Ω) Function
Yes No BUSY System busy output indicates if no
repeater channel is available in the
currently selected LTR system
when PTT is pressed, active low
: Default
No Yes AHK MIC hook input.
ME/AM
R12 (0Ω)R167 (0Ω)Function
Yes No AM Speaker mute input, active high
: Default
No Yes ME MIC ground.
MI/TXS
R94 (0Ω) R24 (0Ω) Function
Yes No TXS Transmitter sense output, active
high : Default
No Yes MI Internal MIC input.
LOK/AM
R5 (0Ω) R6 (0Ω) Function
Yes No AM Audio mute signal input.
No Yes LOK
Link complete pulse output : Default
DTC/LOK/TXS/FSW
R168 R84 R51 R13 Function
(0Ω)(0Ω)(0Ω)(0Ω)
No No No Yes LOK Link complete pulse output.
Yes No No No DTC Data control channel signal input,
Data channel : low (Default)
No No Yes No TXS Transmitter sense output,
active high
No Yes No No FSW Foot switch input, active low
R12 R167
R24
R94
R168
R13
R51R18
R64
TX-RX unit (A/2)
Foil side view
R6
R5
R84
2. Accessory Terminal
2-1. Terminal Function
ConnectorPin Pin I/O Function
No. No. name
CN1 1 DEO O Detect signal output. (Output level :
(DO) 250mVrms; standard modulation)
2 AHK I External hook signal input.
(AH) “COM2” port must be select “AUX
HOOK/PTT” / “DATA PTT” function
in the KPG-49D.
On hook : L, Off hook : H
BUSY O System busy signal output for
trunking system.  No vacant repeater
: L, Vacant repeater : H
RXD2 I Serial data input 2.
“COM2” port must be select
“REM” / “DATA” / “DATA+GPS”
function in the KPG-49D.
3IGN (IG)I Ignition input for KCT-18.
4 DI I External modulation signal input.
5 ME – MIC earth.
AM I Audio mute signal input.
6 MI I Internal MIC input.
TXS O Signal indicating whether the
transceiver is transmitting or not.
TX : H, Another : L
7 PTT I External PTT signal input.
(PT) “COM2” port must be select
“AUX HOOK/PTT” / “DATA PTT”
function in the KPG-49D.
TX : L, Another : H
TXD2 O Serial data output 2.
“COM2” port must be select
“REM” / “DATA” / “DATA+GPS”
function in the KPG-49D.
TX-RX unit (A/2)
Component side view
Note :The following parts are not installed at the time of
shipping; R5,R13,R18,R24,R51,R84,R167 
						

							22
TK-780/ H
INSTALLATION
ConnectorPin Pin I/O Function
No. No. name
8 SQ O Squelch signal output.  Signal logic
type can select “Carrier operate
relay” or “Tone operate relay”.
Active logic level or type can select
in the KPG-49D.
CN2 1 AM I Audio mute signal input.
LOK O Access logic signal output.  Active
level or type can be selectable in the
KPG-49D.
2 MM I MIC mute input.
3 DTC I Data control channel signal input.
Data channel : L, Normal channel : H
TXS O Signal indicating whether the trans-
ceiver is transmitting or not.
TX : H, Another : L
FSW I Foot switch signal input.
Foot sw on : L, Foot sw off : H
LOK O Access logic signal output.
Active level or type can be
selectable in the KPG-49D.
CN3 1 HOR O Horn alert signal output.  Signal
output for horn relay drive (open
collector).  L level during horn drive :
Max. sink current 100mA.
2 E – Earth.
3 SB O Power output after power switch
(DC 13.6V±15%, 0.75A max.).
CN4 1 LOK O Access logic signal output.
Active level or type can be
selectable in the KPG-49D.
2 RXD1 I Serial data input 1.
“COM1” port must be select “REM”
/ “DATA” / “GPS” / “DATA+GPS”
function in the KPG-49D.
3 TXD1 O Serial data output 1.
“COM1” port must be select “REM”
/ “DATA” / “GPS” / “DATA+GPS”
function in the KPG-49D.
CN5 1 PA O Relay for PA function in KAP-1
control signal.  PA on : H, PA off : L
2 SPO O Audio signal input from KAP-1.
3 SPI I Audio signal output to KAP-1.
CN6 1 SP O Output for internal/external speaker.
2 E – Earth.
3. Optional Board Terminal
Terminal is for mounting the option board are provided at
the TX-RX unit (A/2) and TX-RX unit (B/2).  The table below
shows the correspondence between the board and termi-
nals.  Disconnect R529 and R571 in TX-RX unit (B/2) when
the scrambler board is attached.
The table below shown the differences between the
schematic terminals and the PC board terminals.
Schematic diagram PC board view
Name I/O Function Name Unit
SB – Switched B+, DC 13.6V SB
TX-RX (A/2)
output. Maximum 0.75A
5C – 5C 5CTX-RX (A/2)
GND – Earth ETX-RX (A/2)
DEO O Detect signal output (Output DEOTX-RX (A/2)
level : 250mVrms; standard
modulation)
RXAI I RX audio input RXAITX-RX (B/2)
RXAO O RX audio output RXAOTX-RX (B/2)
TXAI I TX audio input TXAITX-RX (B/2)
TXAO O TX audio output TXAOTX-RX (B/2)
LOK O Access logic signal output. LOKTX-RX (A/2)
Active level or type can be
selectable in the KPG-49D.
OPT O Option board select. Please OP
TX-RX (A/2)
(EMG) select option board type in the
KPG-49D.
OP1 O Option code 1 (for voice C1
TX-RX (A/2)
scrambler code 1)
OP2 O Option code 1 (for voice C2
TX-RX (A/2)
scrambler code 2)
OP3 O Option code 1 (for voice C3
TX-RX (A/2)
scrambler code 3)
OP4 O Option code 1 (for voice C4
TX-RX (A/2)
scrambler code 4)
SQ O Squelch signal output. Signal SQ
TX-RX (A/2)
logic type can select “Carrier
operate relay” or “Tone operate
relay”. Active logic level or type
can select in the KPG-49D.
TXD1 O Serial data output 1 TD1TX-RX (A/2)
RXD1 I Serial data input 1 RD1TX-RX (A/2)
TXD2 O Serial data output 2 TD2TX-RX (A/2)
RXD2 I Serial data input 2 RD2TX-RX (A/2)
RSSI OReceive signal strength indicationRSSITX-RX (A/2)
PTT I PTT PTTTX-RX (B/2)
MPTT I MIC PTT MPTTTX-RX (B/2)
FSW I Foot switch input FWTX-RX (A/2)
ST I Side-tone input STTX-RX (A/2) 
						

							23
TK-780 / H
RSSI
SB
E LOK
C3
C1 C2
FWOP
SQC4 5C RD2
RD1 TD2
TD1
DEO
R571 R529
MPTTPTT
RXAIRXAO
TXAI
TXAO
TX-RX unit (A/2)
Foil side view
INSTALLATION
4. Ignition Sense Cable (KCT-18 : Option)
The KCT-18 is an optional cable for enabling the ignition
function. The ignition function lets you turn the power to the
transceiver on and off with the car ignition key.
If you use the Horn Alert function or the Manual Relay
function, you can turn the function off while driving with the
ignition key.
4-1. Connecting the KCT-18 to the Transceiver
1. Install the KCT-19 in the transceiver.   (See the KCT-19
section.)
2. Insert the KCT-18 lead terminal ( 
2 ) into pin 3 of the
square plug ( 
1 ) supplied with the KCT-19, then insert
the square plug into the KCT-19 connector ( 
3 ).
1
3
6
1315
KCT-18 KCT-19
Contact
3
21
Fig. 3
4-2. Modifying the Transceiver
Modify the transceiver as follows to turn the power or
the Horn Alert or Manual Relay function on and off with the
ignition key.
1. Remove the lower half of the transceiver case.
2. Set jumper resistors (0Ω) R151 and R152 of the TX-RX
unit (A/2) as shown in Table 1.
Operation when KCT-18 isconnected R151 R152
KCT-18 cannot be connected Enable Enable
Power on/off and Horn Alert or Disable Enable
AUX-A on/off
Horn Alert or AUX-A on/off, Timed power offEnable Disable
Power cannot be turned on Disable Disable
Table 1 R151 and R152 setup chart
TX-RX UNIT
    (A/2)
ANT
KCT-19
CN7
R151R152
Fig. 4
ST
TX-RX unit (B/2)
Foil side view TX-RX unit (A/2)
Component side view 
						

							24
TK-780/ H
INSTALLATION
5. Connection Cable (KCT-29 : Option)
The KCT-29 connection cable kit is used to connect the
TK-780/780H transceiver to the KPG-1A Modem GPS Re-
ceiver or the KPG-1B Modem GPS Controller.
5-1. Installing the KCT-29 in the transceiver
1. Remove the upper cover from the transceiver.
2. Lift the DC cord bushing ( 
1 ) from the chassis.
3. Remove the pad as shown in Figure 5 ( 
2 ).
4. Insert the KCT-29 cable ( 
3 ) into the chassis ( 4 ).  The
wire harness band ( 
5 ) must be inside the chassis.
5. Replace the DC cord bushing ( 
6 ).
6. Connect the KCT-29 to the TX-RX unit (A/2) as shown in
Figure 6 ( 
7 ).
KCT-29
BD
C
CN2CN3 CN4
C
D
B
A3 46
7
5
CN1B
1
2
Fig. 5
Fig. 6
6. Interface Cable (KCT-31 : Option)
The KCT-31 is a RS-232C interface cable for LMR mobile
radios, TK-780/780H.
The 9-pin (D-sub) connector is connected to an external
RS-232C terminal.  The other end of the cable is connected
to the internal connector of LMR mobile radio.
Note : You cannot write a firmware with the KCT-31.
6-1. Features
• This KCT-31 has a RS-232C-TTL level interface circuit.
• This KCT-31 does not require an external power supply.
• This KCT-31 can be used up to 9600 bps.
• Compatible with an ER terminal of DTE that has the volt-
age 6V or more.
6-2. Terminal function (D-sub connector)
Pin No. I/O Port name Function
1 I CD Carrier detect
2 I RD Receive data
3 O SD Transmit data
4 O ER Data terminal ready
5 – SG Signal ground
6 I DR Data set ready
7 O RS Request to send
8 I CS Clear to send
9 – CI Ring indicator
1 5
6 9 
						

							25
TK-780 / H
INSTALLATION
Red
Black
Yellow
GreenA
B
C
ABC
COM1 No Yes Yes
COM2 Yes Yes No
2. Make sure the unit’s power is turned off.
3. Remove the upper case of the transceiver and lift the DC
cable bushing ( 
1 ) from the chassis.
4. Remove the pad as shown in Figure 8 ( 
2 ).
5. Insert the KCT-31 cable ( 
3 ) into the chassis ( 4 ).
The write retaining band ( 
5 ) must be inside the chassis.
6. Replace the DC cable bushing ( 
6 ).
7. Connect the KCT-31 to the TX-RX unit (A/2) as shown in
Figure 9 ( 
7 ).
8. Replace the upper case.
1
2
A
B
3 46
5
CN6CN1
CN2
CN4
CN3
A
B
7
CN6CN1
CN2
CN4
CN3
B
C
When the COM2 is used. When the COM1 is used.
6-3. Installing the KCT-31 in the transceiver
Note :
When the COM1 is used, A connector is unused.
When the COM2 is used, C connector is unused.
1. Bind the unused connecor to the cable with a retaining
band as shown.
When the COM1 is used. When the COM2 is used.
Red
Black
Yellow
Green
A BC
Fig. 7
Fig. 8
Fig. 9
Note :
· The modification must be applied to the TK-780/780H
transceivers with a serial number of 30200000 or smaller
when using a COM2 port.  Replace the 47kΩ (R675) chip
resistor on the TX-RX unit (B/2) with a 4.7kΩ resistor.
Original New
47kΩ (RK73GB1J473J)→4.7kΩ (RK73GB1J472J)· Enable the serial port function on the terminal.
· Refer to the service manual of each radio or the help file
that came with the FPU (Field Programming Unit) for de-
tails. 
						

							26
TK-780/ H
INSTALLATION
4
3
2
1
W1
W2
CN1
CN2
KCT-19
Cushion
(G13-1710-04)
CN3CN5
1CN3
Fig. 10
7. PA/HA Unit (KAP-1 : Option)
7-1. Installing the KAP-1 in the Transceiver
The Horn Alert (max. 2A drive) and Public Address func-
tions are enabled by inserting the KAP-1 W1 (3P; white/
black/red) into CN3 on the TX-RX unit (A/2), inserting W2
(3P; green) into CN5 on the TX-RX unit (A/2), and connecting
the KCT-19 (option) to CN2 and CN3 of the KAP-1.
•Installation procedure
1. Open the upper case of the transceiver.
2. Insert the two cables ( 
1 ) with connectors from the
KAP-1 switch unit into the connectors on the transceiver.
3. Secure the switch unit board to the chassis with a screw
( 
3 ).  The notch ( 2 ) in the board must be placed at the
front left side.
4. Attach the cushion on the top of the KAP-1 switch unit.
8. Fitting the Control Panel Upside Down
The TK-780/780H control panel can be fitted upside
down, so the transceiver can be mounted with its internal
speaker (in the upper half of the case) facing down in your
car.
1. Remove the control panel and the TX-RX unit (B/2) con-
trol section.  (Fig. 11)
Fig. 11
2. Fold the flat cable ( 1 ) in the opposite direction ( 2 ).
3. Rotate the control section ( 
3 ) 180 degrees ( 4 ).
4. Insert the flat cable into the control section connector,
CN502 ( 
5 ).
5. Mount the control section on the transceiver ( 
6 ).
CN502
1
2
3
4
5
6
Fig. 12 
						

							27
TK-780 / H
INSTALLATION
9. External Speaker
9-1. KES-3 : Option
The KES-3 is an external speaker for the 3.5-mm-diam-
eter speaker jack.
•Connection procedure
1. Connect the KES-3 to the 3.5-mm-diameter speaker jack
on the rear of the transceiver.
KES-3
Fig. 149-2. KES-4 : Option
The KES-4 is an external speaker used with the acces-
sory connection cable.
•Connection procedure
1. Install the KCT-19 in the transceiver.  (See the KCT-19
section.)
2. Insert the crimp terminal into the square plug supplied
with the KCT-19.
3. Connect CN5 of the transceiver to connector C of the
KCT-19 instead of to the internal speaker connector.
KES-4
1
3
6 13
15
12
Crimp terminal
(E23-0613-05)Black lead
Black/White lead
Fig. 15
6. Rotate the control panel 180 degrees and mount it on the
transceiver.  Refit the two halves of the case to complete
installation.  (Fig. 13)
Fig. 13
Note : When installing KES-4, you must use an optional
cable, KCT-19.  Do not connect the KES-4 to 3.5mm
speaker jack.  The performance may be degrade. 
						

							28
TK-780/ H
Frequency Configuration
The TX-RX unit (A/2) incorporates a VCO, based on a frac-
tional N type PLL synthesizer system, that allows a channel
step of 2.5, 5, 6.25, 7.5kHz to be selected.  The incoming
signal from the antenna is mixed with a first local oscillation
frequency to produce a first intermediate frequency of
44.85MHz.
The signal is then mixed with a second local oscillation
frequency of 44.395MHz to produce a second intermediate
frequency of 455kHz.  This is called a double-conversion
system.  The TX-RX unit (A/2) contains a wide/narrow MCF
and CFs.  The transmit signal is produced by the PLL circuit
for direction oscillation and division.  The signal output from
the VCO is amplified by a straight amplifier and transmitted.
ANT
SWRX
AMP1st
MIX
TX
AMPPOWER
AMP
CF 455kHz
(Wide) CF 455kHz
(Narrow)
MCF
44.85MHz
–
+MIX/IF/DET
190.85~218.85MHz 
: K,HK
180.85~206.85MHz 
: K2,HK2
PLL/VCO
VCXO
16.8MHz 146~174MHz : K,HK
136~162MHz : K2,HK2 146~174MHz : K,HK
136~162MHz : K2,HK2
44.395MHzAFO
MD
MB
Fig. 1 Frequency configuration
Receiver System

Outline
The incoming signal from the antenna passes through a
low-pass filter and a transmission/reception selection diode
switch (D211, D212) and goes to the front end of the re-
ceiver.  The front-end filter is a BPF, a variable BPF consist-
ing of three coils and three varicap diodes (D206, D207,
D208) to eliminate unwanted out-of-band signal compo-
nents.  The low-noise amplifier (LNA) (Q202) uses a bipolar
transistor to achieve wide-band and low-distortion amplifica-
tion.
The signal passes through the BPF and is down-con-
verted with the first local signal by IC202 to produce the firstIF signal of 44.85 MHz.  The first local signal passes through
an LPF and an attenuator to eliminate unwanted harmonics
components and implement the optimum input level to the
mixer, then enters IC202.  A DBM is used as a mixer to
achieve a high potential.
The signal output from the mixer passes through two
MCFs (XF1).  The signal is amplified by an intermediate fre-
quency amplifier and input to the FM IF IC (IC11).
The first intermediate frequency signal is mixed with the
second local signal of 44.395MHz to produce the second IF
signal of 455kHz.
The unwanted near-by signal components are then elimi-
nated by a wide ceramic filter (CF1) or a narrow ceramic fil-
ter (CF2) and the resulting signal goes back to the FM IF IC.
The signal is quadrature-detected in the IC to produce an
audio signal, which is amplified by a DET amplifier (IC2) and
output to the TX-RX unit (B/2).

Wide/Narrow Changeover Circuit
The W/N port (pin 11) of the shift register (IC7) is used to
switch between ceramic filters.  When the W/N port is high,
Q24 turns on and the ceramic filter SW diode (D22, D23)
CF1 turns on to receive a Wide signal.  At the same time,
Q16 turns on and one of the filters is selected so that the
wide and narrow audio output levels are equal.
When the W/N port is low, Q23 turns on and the ceramic
filter SW diode (D22, D23) CF2 turns on to receive a Narrow
signal.
LPF ANT
BPFL202~204BPF Q202
AMPQ15
AMPIC2
AMP IC202
MIXXF1
BPF D211,212ANT
SW–
+
CF1/
CF2
IC11
MIX,IF,DET
X2
2nd
local OSC 1st local 
OSC (HT)DEO
Fig. 2 Receiver systemFig. 3 Wide/Narrow changeover circuit
CIRCUIT DESCRIPTION
CF1
(Wide)
CF2
(Narrow)
IFI
MXO IC11
IF system
AFO
DET
OUTC107
C100
C108 R114
R123
R133 R126 R125
R130 R131
+
+
Q16DM Q32
R121
W/N
IC7 11pin
Wide : H
Narrow : LC118
D22 D23Q235C
Q24
Wide : L
Narrow : H 
						

							29
TK-780 / H

AF Signal System
The detection signal (DEO) from the TX-RX unit (A/2)
goes to the audio processor (IC504) of the TX-RX unit (B/2).
The signal passes through a filter in the audio processor to
adjust the gain, and is output to IC502.  IC502 sums the AF
signal and the DTMF signal and returns the resulting signal
to the TX-RX unit (A/2).  The signal (AFO) sent to the TX-RX
unit (A/2) is input to the D/A converter (IC5).  The AFO out-
put level is adjusted by the D/A converter.  The signal output
from the D/A converter is added with the BEEP signal (BPO)
and the resulting signal is input to the audio power amplifier
(IC10).  The AF signal from IC10 switches between the inter-
nal speaker and speaker jack (J1) output.

Squelch Circuit
The detection output from the FM IF IC (IC11) is ampli-
fied by IC2 and the signal (DEO) is sent to the TX-RX unit (B/
2).  The signal passes through a high-pass filter and a noise
amplifier (Q503) in the TX-RX unit (B/2) to detect noise.  A
voltage is applied to the CPU (IC511).  The CPU controls
squelch according to the voltage (ASQ) level.  The signal
from the RSSI pin of IC11 is monitored.  The electric field
strength of the receive signal can be known before the ASQ
voltage is input to the CPU, and the scan stop speed is im-
proved.
Transmitter System

Outline
The transmitter circuit produces and amplifies the de-
sired frequency directly.  It FM-modulates the carrier signal
by means of a varicap diode.

VCO/PLL Circuit
The TK-780/780H has a VCO for the transmitter and a
VCO for the receiver in a sub-unit (A1).  They are housed in a
solid shielded case and connected to the TX-RX unit (A/2)
through CN101.  One of the VCOs is selected with an ST
signal.  A filtered low-noise power supply is used for the
VCOs and varicap diodes.
The VCO for the transmitter is described below.  It is de-
signed so that Q103 turns on with a prescribed frequency
when a reverse bias is applied to D102 and D107 by using
the control voltage (CV) through CN101.  The control voltage
is changed by turning the trimmer capacitor (TC102).  The
output from Q103 is applied to the buffer amplifier (Q106) to
generate a VCO output signal.  This signal is used as a drive
input signal or a local signal of the first mixer.  Since a signal
output from Q106 is input to the PLL IC, it passes through
CN101 and buffer amplifier (Q300) and goes to the PLL IC
(IC300).  The modulation signal from CN101 is applied to
D109 and passes through C125 and C126 to modulate the
carrier.
The PLL IC uses a fractional N type synthesizer to im-
prove the C/N ratio and lock-up speed.  The VCO output sig-
nal input to the pin 5 of the PLL IC is divided to produce a
comparison frequency according to a channel step.  This sig-
nal is compared with the reference frequency which is out-
put from the VCXO (X1).  VCXO provides 16.8MHz, 2.5ppm
(–30 to +60°C) and guarantees stable performance when
the temperature changes.  The TK-780/780H changes the
VCXO reference voltage (MB) by software and fine-adjusts
the reference oscillator frequency to use the set with a
2.5KHz frequency step.  The output signal from the phase
comparator passes through a charge pump in the PLL IC and
an external active LPF (Q301, Q302) to generate a DC VCO
control voltage CV.  Serial data (DT, CK, EP) are output from
the CPU (IC511) and shift register (IC8) in the TX-RX unit (B/
2) to control the PLL IC.  The PLL lock status is always moni-
tored by the CPU.
FIg. 4 AF signal system
IC2
AMPIC503
AMPQ503NOISE AMPD509 IC11 IC511DEO
RSSIHPFDET
CPU IF
SYSTEM
TX-RX UNIT (B/2)
Fig. 5 Squelch circuit
IC504 IC3 Q103 IC711 MIC
AF AMP
TA75S01F
MIC KEY
INPUTAF AMP,
IDC, LPF
TC35453F
IC511
CPU
30622M8A
-
***GPSUM AMP
TA75W558FUX1
VCXO
16.8MHz
VCO
2SK508NV
(K53)
IC300
PLL
SA7025DK
Q106RF AMP
2SC4215
(Y)
Q300
BUFFER
2SC4215
(Y)
Q203
RF AMP
2SC3357
Q204ANT
RF AMP
2SC2954
IC400POWER AMP
M67741H-32 : K
M67741L-35 : K2
M68702H : HK
M68702L : HK2Q7BUFFER
2SC4215
(Y)
Fig. 6 Transmitter system
CIRCUIT DESCRIPTION
AUDIO
PROCE.SUM
AMPD/A
CONV. IC504 IC504 IC5AF PAIC10 SP
DTMF BPOAFO
DEO
TX-RX UNIT (B/2) 
						

							30
TK-780/ H

Unlock Circuit
During reception, the TR signal goes high, the KEY signal
goes low, and Q10 turns on.  Q11 turns on and a voltage is
applied to the collector (8R).  During transmission, the TR
signal goes low, the KEY signal goes high and Q13 turns on.
Q12 turns on and a voltage is applied to 8T.
The CPU in the TX-RX unit (B/2) monitors the PLL (IC300)
LD signal directly.  When the PLL is unlocked during trans-
mission, the PLL LD signal goes low.  The CPU detects this
signal and makes the KEY signal low.  When the KEY signal
goes low, no voltage is applied to 8T, and no signal is trans-
mitted.Q17 turns the PC signal on or off using 8T so that the
circuit works only during transmission.  With stability at low
power in mind, Q29 turns off to optimize the detection volt-
age.
The APC circuit is configured to protect overcurrent of
the power module due to fluctuations of the load at the an-
tenna end and to stabilize transmission output at voltage
and temperature variations.
Control Circuit
The CPU carries out the following tasks:
1) Controls the shift register (IC7, IC8, IC508) AF MUTE,
WIDE/NARROW, T/R KEY outputs.
2) Adjusts the AF signal level of the audio processor (IC504)
and turns the filter select compounder on or off.
3) Controls the DTMF decoder (IC507).
4) Controls the LCD assembly display data.
5) Controls the PLL (IC300).
6) Controls the D/A converter (IC5) and adjusts the volume,
modulation and transmission power.
IC508
SHIFT
REG.IC511
CPU
Q10
SW
Q11
SW
IC300
PLL
Q13
SW
Q12
SW
LD
TX-RX UNIT (B/2)
TR8C
8R 8T
KEY
PLL lock
: LD “H”
Fig. 7 Unlock circuit

Power Amplifier Circuit
The transmit output signal from the VCO is amplified to a
specified level of the power module (IC400) by the drive
block (Q203, Q204).  The amplified signal passes through
the transmission/reception selection diode (D211) and goes
to a low-pass filter.  The low-pass filter removes unwanted
high-frequency harmonic components, and the resulting sig-
nal is goes the antenna terminal.

APC Circuit
The automatic transmission power control (APC) circuit
detects part of a power module output with a diode (D27,
D30) and applies a voltage to Q21.  Q21 compares the APC
control voltage (PC) generated by the D/A converter (IC5)
and DC amplifier (IC6) with the detection output voltage to
control Q19 and Q20, generates DB voltage from B voltage,
and stabilizes transmission output.
RF
AMP Q203RF
AMP Q204POWER
AMP IC400
APC
DRIVERQ19 DB
+B
VR1 Q20
PRI
DRIVER
DC
AMPIC6PC
SW Q17
ANT
SW D211LPFANT
Q29
POWER
DET D27,30
Q21 D36HK,HK2
APC
CONTROLTEMPPROTECTH/L
SWH/L
IC7 5pin
25W (High power) 
: “H” 8T
(TX : 8V)
TX :
PC SW ON D15
PC
IC5
23pin
Q33 HK,HK2
TEMP
PROTECT
Fig. 8 APC circuit
IC5
D/A
converter
IC300
PLL
IC7
Shift
register
IC8
Shift
registerIC508
Shift
register
DT
RFCK
ES
ENOE
CS
CK
DT ACK
SD
CP
EP
AFCLR
AFMSKE
AFDAT
AFRDT
AFTRD
AFRTM
AFSTB
IC504
Audio
processor
IC507
DTMF
DECO.
IC511
CPUTX-RX UNIT (A/2)
LCD ASSY
Fig. 9 Control circuit

Memory Circuit
The transceiver has a 2M-bit (256k x 8) flash ROM
(IC510) and an 8k-bit EEPROM (IC512).  The flash ROM con-
tains firmware programs, data and user data which is pro-
grammed with the FPU.  The EEPROM contains adjustment
data.  The CPU (IC511) controls the flash ROM through an
external address bus and an external data bus.  The CPU
controls the EEPROM through two serial data lines.
SCL
SDA IC511
CPU ADDRESS BUS
DATA BUS
IC510
FLASH
ROMIC512
EEPROM
Fig. 10 Memory circuit
CIRCUIT DESCRIPTION