Kenwood TK-481, TK-480 Service Manual
800MHz/900MHz FM TRANSCEIVER
TK-480/48 1
SERVICE MANUAL
REVISED II
This service manual applies to products with 30100001 or
subsequent serial numbers.
Whip antenna
(T90-0636-25) : TK-480
(T90-0640-25) : TK-481
Knob (ENC)
(K29-5232-03)
Knob (VOL)
(K29-5231-03)
Panel assy
(A62-0981-04)
Badge
(B43-1139-04)
Knob (PTT)
(K29-5157-03)
Cabinet assy
(A02-3659-03) : K2
Packing
(G53-0841-02) : K2
© 2001-3 PRINTED IN JAPAN
B51-8408-20 (N) 1015
CONTENTS
GENERAL ............................................................ 2
SYSTEM SET-UP ................................................ 2
OPERATING FEATURES .................................... 3
REALIGNMENT................................................. 11
CIRCUIT DESCRIPTION.................................... 14
SEMICONDUCTOR DATA................................ 20
DESCRIPTION OF COMPONENTS .................. 23
PARTS LIST ....................................................... 24
EXPLODED VIEW ............................................. 30
PACKING ........................................................... 31
ADJUSTMENT .................................................. 32
TERMINAL FUNCTION .................................... 40
PC BOARD VIEWS
DISPLAY UNIT (X54-3210-XX) .................... 41
TX-RX UNIT (X57-5630-XX) ......................... 47
SCHEMATIC DIAGRAM ................................... 53
BLOCK DIAGRAM............................................. 57
LEVEL DIAGRAM (TK-480) .............................. 59
LEVEL DIAGRAM (TK-481) .............................. 60
KNB-16A/17A (Ni-Cd BATTERY) ..................... 61
KPG-36 (PROGRAMMING INTERFACE CABLE)
KSC-19 (CHARGER) .......................................... 61
SPECIFICATIONS.............................................. 62
.... 61
Photo is TK-480/481 K2 type.
(Produced in Singapore)
CAUTION
When using an external power connector,
please use with maximum final module protection of 9V.
TK-480/481
GENERAL / SYSTEM SET-UP
INTRODUCTION
SCOPE OF THIS MANUAL
This manual is intended for use by experienced technicians familiar with similar types of commercial grade communications equipment. It contains all required service information for the equipment and is current as of this publication date. Changes which may occur after publication are
covered by either Service Bulletins or Manual Revisions,
which are issued as required.
ORDERING REPLACEMENT PARTS
When ordering replacement parts or equipment information, the full part identification number should be included.
This applies to all parts : components, kits, and chassis. If
the part number is not known, include the chassis or kit
number of which it is a part and a sufficient description of
the required component, for proper identification.
PERSONNEL SAFETY
The following precautions are recommended for personnel safety :
• DO NOT transmit until all RF connectors are secure and
any open connectors are properly terminated.
• SHUT OFF this equipment when near electrical blasting
caps or while in an explosive atmosphere.
• This equipment should be serviced by only qualified technicians.
SERVICE
This radio is designed for easy servicing. Refer to the
schematic diagrams, printed circuit board views, and alignment procedures contained within.
NOTE
WE CANNOT guarantee oscillator stability when using
channel elements manufactured by companies other than
KENWOOD or its authorized agents.
You must use the KPG-49D to program TK-480/481 trans-
ceivers with a serial number of 30100001 or greater. You
cannot use the KPG-35D for those radios.
TK-480/481 transceivers with a serial number of
30100001 or greater have a red triangle in the KENWOOD
logo label (B43-1139-04) on the front panel. You will also
find the model name plate marked as “Ver 2.0” on the rear
of the transceiver.
Unit TX-RX unit Display unit
Model &
destination 0-10 0-11 0-10 0-11
TK-480
TK-481
Note X57-5630-XX/X54-3210-XX : Produced in Singapore
X57-5630-XX X54-3210-XX
K ✓✓
K2 ✓✓ LOC : 44.395MHz ✓
K ✓✓
K2 ✓✓ LOC : 44.395MHz ✓
Frequency range Remarks QT/DQT DTMF Charger Battery 16 key
806~870MHz
896~941MHz
SYSTEM SET-UP
Merchandise received
License and frequency allocated by FCC
Choose the type of transceiver
Transceiver programming
IF1 : 44.85MHz
IF1 : 44.85MHz
Frequency range (MHz) RF power Type
TX 806~825 2.5W TK-480 K,K2
851~870
RX 851~870
TX 896~902 TK-481 K,K2
935~941
RX 935~941
A personal computer (IBM PC or compatible), programming
interface (KPG-36), and programming software (KPG-49D) are
required for programming.
(The frequency, trunked system features, conventional system
features, TX power HI/LOW, and signaling data are programmed
for the transceiver.)
✓✓Option ✓
✓✓Option ✓
–
–
Are you using the speaker microphone?
NO
Delivery
YES
KMC-25
Speaker microphone
(Option)
2
OPERATING FEATURES
TK-480/481
1. Operation Features
The TK-480/481 is an 800/900MHz band EFJ LTR™-compatible trunked radio designed to operate in both trunked
and conventional modes. The programmable features are
summarized.
Model Trunking mode
Conventional mode
This model can handle up to 32 systems with up to 250
groups in each system. The transceiver can be used in both
trunked mode and conventional mode. Systems, groups,
and their functions are programmed.
2. Transceiver Controls and Indicators
2-1. Physical Layout
Microphone Speaker
1 2 3
4
5
6
7
8
9
12
10
11
Volume/Power switch
Transceiver Power and Volume switch. Turn clockwise to
switch On the transceiver. Turn counterclockwise fully to
switch OFF the transceiver. Also adjusts the volume
level. When the power is switched off, all the parameters, such as the system and group, are stored in
memory. When the power is switched on again, the system returns to the previous conditions.
Auxiliary (orange) key (Programmable)
Battery pack release catch
Push down to release the battery pack. See Installing the
Ni-Cd Battery Pack.
MONITOR key* (Programmable)
PTT (Push-To-Talk) key
Press this key, then speak into the microphone to call a
station.
LAMP key* (Programmable)
TX/BATT indicator
This red LED lights during transmission (it does not light
during busy or when transmit is prohibited). If the battery
voltage falls below the programmed voltage during transmission, the brightness of this indicator decreases at intervals of about one second, so it can be used as the battery voltage alert function.
S, A, B, and C key (Programmable)
Note : The transceiver is also available without the DTMF
keypad (
).
2-2. Panel controls
The key on the top and front panel is momentary-type
push buttons. The functions of these keys and knob are explained below.
Antenna connector
Connect the supplied antenna here.
System or Group selector knob (Programmable)
Turning the system (or group) selector knob clockwise
increases the system (or group) number by one. Turning
the knob in the counterclockwise direction decreases the
system (or group) number by one.
After the system number (or group number) reaches the
highest system number (or group number), it goes back
to lowest system number (or group number).
System numbers (or group numbers) not set are skipped.
Caution : The FPU (KPG-49D) allows selecting between
system selector and group selector.
DTMF keypad (keypad model only)
Press the keys on the telephone keypad to send DTMF
tones.
Universal connector
Connect the external KMC-25 speaker/ microphone (optional) here. Otherwise, keep the supplied cover in place.
* : MONITOR and LAMP are arbitrary names chosen for
these buttons. They can be used for any of the auxiliary
functions.
2-3. Programmable keys
The FPU (KPG-49D) enables programmable keys to se-
lect the following functions.
Auto Tel, AUX(only when Voice Scrambler is not selected), DTMF ID (BOT), DTMF ID (EOT), Display Character,
Emergency (only AUX key), Function, Group Down, Group
Up, Home Group, Key Lock, Lamp, Memory (RCL/STO),
Memory (RCL), Memory (STO), Monitor A, Monitor B, Monitor C, Monitor D, Redial, RF Power Lo, Scan, Scan Del/Add,
Scan Temporary Delete, Scrambler (Only when Voice
Scrambler is selected), SP Attenuation (Only MIC switch),
System Down, System Up, TEL Disconnect and none.
These functions the FPU programs to the function keys
are described in the following sections.
3
TK-480/481
OPERATING FEATURES
■ Auto TEL
Automatically connects available repeaters that are connected to telephone circuits when operating as LTR system.
The time allocated to search for available repeaters is 60
seconds, after which connection failure occurs, a DTMF
tone is output and the function terminates.
If connection to an available circuit is made, only ID 253,
EOT or hang-up time-out can terminate the function.
■ AUX
This function can be programmed when the voice scrambler board is not installed.
If this key is pressed, an underscore (“_”) appears at the
extreme right of the LCD and AUX port which is inside of the
transceiver turns to the active level. If pressed again, the
underscore disappears and the AUX ports turns to the
deactive level.
■ DTMF ID (BOT)
Pressing this key in Conventional mode, automatically
sends the preset Connect ID.
■ DTMF ID (EOT)
Pressing this key in Conventional mode, automatically
sends the preset Disconnect ID.
■ Display character
This key switches the LCD display between the system/
group number and system/group name.
■ Emergency
Pressing this key for longer than the programmed “Emergency Key Delay Time” causes the transceiver to enter the
emergency mode. The transceiver jumps to the programmed “Emergency System/Group” and transmits for
the programmed “Active Time”.
The transceiver disables mic mute while transmitting.
After finishing transmission, the transceiver receivers for
the programmed “Interval Time”. The transceiver mutes
the speaker while receiving. Following the above sequence,
the transceiver continues to transmit and receive.
If “Man Down Switch” has been programmed on the radio and the switch is activated, the radio enters Emergency
mode after the specified “Man Down Delay Time” expires.
■ Key lock
Pressing this key causes the transceiver to accept entry
of only the [Function], [Key Lock], [PTT], [Lamp], [Monitor A],
[Monitor B], [Monitor C], [Monitor D], and [Emergency] keys.
The locked keys also include the tuning control.
■ Lamp
This key illuminates the LCD and keys on the front panel.
When the key is pressed, the LED lamp goes on.
When it is released, the lamp goes off after about five
seconds. If any key is pressed while the LED lamp is on, the
lamp is kept on for five seconds.
■ Memory
This key allows DTMF memory data to be recalled; up to
32 memories each with a memory dial of up to 16 digits and
an A/N of up to 10 digits per memory.
■ Monitor
Used to release signalling or squelch when operating as a
conventional. It is also used to reset option signalling.
■ Redial
Pressing this key when System/Group is shown, displays
the previously transmitted DTMF code. Pressing [PTT] at
this time, transmits the code that is currently displayed.
■ RF power low
Used to temporarily switch transmission output to low
power. Turning the function on enables:
Hi→Low, Low→Low
Key states are backed up, except in the PC mode when
they are reset.
■ Scan
Press this key starts scanning. Pressing this key stops
scanning.
■ Scan Del/Add
Used to select whether system scan routines are used
during system scan. Each pressing of the key (to ON)
toggles between lockout and lock. The scan routine is
started when on lock. The DEL indicator flashes when the
system is on lockout.
■ Function
Pressing this key causes the transceiver to display
“FCN”. Then, pressing a DTMF key causes the corresponding programmed function to start. This key may be convenient when using many functions with the 12-key keypad
(K2 type).
■ Group up/down
When the key is pressed each time, the group number to
be selected is incremented/decremented and repeats if held
for one second or longer.
■ Home group
Each pressing of the key selects a preset system/group.
4
■ Scan temporary delete
This key is temporarily deleted a system being scanned.
If you press this key when scan is stopped (when a call is
being received from another station), the system is temporarily deleted and scanning restarts.
This key operates even when “Scan Type” is set to “List
Type System Scan”.
■ Scrambler
If a scrambler code (1 to 4) has been set in the FPU, an
underscore (“_”) appears at the extreme right of the LCD
display when scrambler is active. Pressing this key changes
ON/OFF of scramble operation.
Holding this key down for 2 seconds sets Scramble Code
Select Mode.
OPERATING FEATURES
TK-480/481
■ System up/down
When the key is pressed each time, the system number
to be selected is incremented/decremented and repeats if
held for one second or longer.
■ Telephone disconnect
Pressing this key ends an RIC connection (disconnects
the telephone line).
■ None
Sounds error operation beep, and no action will occur.
Use this function when the transceiver is required to be
more simple operated.
2-4. Display
P
9
Sub display
Displays the system, channel and group numbers. Also
displays various functions, such as TA.
Alphanumeric display
The twelve-character dot matrix alphanumeric display
shows the system and group numbers. You can program
system and group names with up to ten characters in
place of these numbers. The left display is used as a delete indicator (
call (
) or scrambler ( _ ) function. The delete/add indicator shows the systems locked out of the scanning sequence. Selective call and scrambler are optional functions that can be programmed.
) and the right is used for the selective
3. Scan Operating
3-1. System scan
System scan can be selected with the “Scan” key by pro-
gramming the scan feature. When the “Scan” key is
pressed and the “SCN”’ mark appears, scan mode in entered. Scanning starts from the system following the currently displayed system. When a call is received, scanning
stops, and the system and group are displayed.
When the system knob or programming key is touched
during scanning, the scan stops and the revert system or
group can be changed. Scanning resumes one second after
the key is released.
System scan consists of the following 2 types.
■ Fix system scan
All the set systems except locked-out ones are scanned.
If the DEL/ADD feature is assigned to the programmable
key, it can be controlled from the front panel.
P (Priority) indicator
The P indicator ( ) appears when a selected channel is
programmed as priority, in conventional operation.
MON (Monitor) indicator
The MON indicator appears when the button programmed as MONITOR is pressed.
SVC (Service) indicator
This icon is not used on this transceiver.
SCN (Scan) indicator
The SCN indicator appears when using Scan mode.
LO indicator
Appears when low power is selected.
Handset indicator
The handset indicator ( ) appears when the selected
group is programmed as telephone IDs.
MAIL indicator
Flashes when a status message (FleetSync™) is received. Lights when a status message is stored in the
stack memory.
■ List type system scan
A scan list can be set for each system.
The list to be scanned can be changed by changing the
display system.
If many system have been set, the scan speed can be
increased by narrowing the systems to be scanned with
scan lists.
3-2. System lockout
The system lockout feature is used to lock systems out
of the scan sequence, and can be selected by programming
in the following two ways:
■ Fixed lockout
The system to be locked out is selected by programming.
When a locked system is selected, the Delete (
appears on the left of the SYSTEM indicator. The revert system is scanned even if it is locked out. If there is a locked
system, the Delete (
ning.
) indicator flashes during fixed scan-
) indicator
■ User selectable lockout
If the scan lockout feature is programmed to a key, the
user can lock systems out of the scan sequence with the
key. To lock a system out of the scan sequence, press the
key when the system is displayed. The Delete (
is displayed on the left of the SYSTEM indicator.
) indicator
5
TK-480/481
OPERATING FEATURES
To unlock a system, select the system and press the key.
The Delete (
tem has returned to the scan sequence. The revert system
is scanned even if it is locked out. If there a locked system,
the Delete (
systems are locked out, the scan stops and only the revert
system is received.
) indicator disappears to indicate that the sys-
) indicator flashes during fixed scanning. If all
3-3. Drop-out delay time (Scan resume time)
If a call is received during scan, the scan stops. The scan
resume time can be programmed as 0 to 300 seconds in
one-second increments. The default value is 3 seconds.
3-4. Dwell time
The dwell time is the time after transmission ends until
the scan resumes in scan mode. It can be set 0 to 300 seconds by programming. The default value is 3 seconds.
3-5. System/Group revert
System/Group revert can be programmed for one of the
following;
■ Last called revert
The system or group changes to the revert system or
group when a call is received with the system or group being scanned.
■ Last used revert
If a system/group call is received during scanning and the
PTT button is pressed for transmission and response within
the drop out delay time, the system or group is assigned as
the new revert system or group.
■ Selected revert
If the system/group was changed while scanning, the
newly selected system/group.
■ Selected + Talkback
If the system/group was changed while scanning, the
newly selected system/group. The transceiver “talks back”
on the current receive group.
3-6. Scan message wait
The time for staying with the home repeater that receives a signal during system scan and monitoring data
messages can be programmed. If there is no signal from the
home repeater, the system is scanned for about 50ms. If
there is a signal, three data messages are monitored. Normally, three data messages are monitored for each system,
and it can be increased in multiples of three data messages
per line to up to eight lines.
If the repeater data message indicates that there is no
call, data monitoring is terminated and the home repeater of
the next system is scanned.
3-7. Group scan operation
Group scan can be programmed for each group. In addition to the ID codes of the selected group, the ID codes of
the other groups that are permitted for group scan are decoded. (The two fixed ID and block decode codes are always
decoded.)
If, during group scanning, a call is received with one of
the selectable group ID codes for which group scan is enabled, the group display indicates the group number that the
call came in with. That group then becomes the new selected group. Group scan resumes after the specified dropout delay time or dwell time shared by the system scan
elapses.
3-8. In Conventional system.
If QT or DQT is set for the channel, the channels, including signalling, are scanned.
In case of the priority group is set in conventional system, if a group scan (including group scan during a system
scan) temporarily stops (receiving) in a group that does not
have priority, a look back is performed to the priority group.
Look back is performed according to the look back time A
and B settings. If a call is received on the priority group, reception immediately switches to the priority group.
4. Details of Features
4-1. Time-out timer
The time-out timer can be programmed in 15 seconds
increments from 15 seconds to ten minutes. If the transmitter is keyed continuously for longer than the programmed
time, the transmitter is disabled and a warning tone sounds
while the PTT button is held down. The alert tone stops
when the PTT button is released.
4-2. Sub LCD
You can use 3-digit the display to display the system
number, channel number or group number. It is useful when
the main (12-digit) display indicates system, group or channel name or other functions.
4-3. Selective Call Alert LED
You can select whether or not the LED on the transceiver
flashes in an orange color when selective call was occurred.
4-4. PTT ID
PTT ID provides a DTMF ANI or MSK ID to be sent with
every time PTT (connect ID at beginning of transmission,
disconnect ID at end of transmission, or both).
You can program PTT ID “on” or “off” for each group
channel (DTMF). The contents of ID are programmed for
each transceiver.
The transceiver is capable to have ID. The format is
DTMF. The timing that the transceiver sends ID is programmable.
BOT : Connect ID is sent on beginning of transmission.
EOT : Disconnect ID is sent on end of transmission.
Both : Connect ID is sent on beginning of transmission
and disconnect ID is sent on end of transmission.
There is also “PTT ID” setting for each channel.
6
OPERATING FEATURES
TK-480/481
4-5. Radio password
When the password is set in the transceiver, user can not
use the transceiver unless enter the correct password.
This code can be up to 6 digits from 0 to 9 and input with
the keypad or selector, and “S” key.
4-6. Battery Warning
This transceiver has battery warning feature. If the low
voltage is detected during transmission, the transceiver
warns it by flashing red “LED”.
Then more low voltage is detected during transmission,
the transceiver stops transmission and warns it by flashing
red “LED” and beep.
Please notice “standard” for the battery exchange,
charging time by flashing red LED and beep.
4-7. Minimum Volume
The minimum volume is programmable (off (0) to 31).
The transceiver remains the minimum volume level however the mechanical volume position is set to zero.
4-8. Call indicator
The call indicator can be programmed for each group. In
trunked system, it can be set to respond to a selectable decode ID or one of two fixed IDs, except block IDs. When a
call is received with a selectable decode ID, the call indicator
flashes. When a call is received with a fixed ID, the call indicator lights continuously.
On a conventional system, the call indicator can be programmed to light for each QT or DQT code. It keeps flashing
while a call is being received. It is turned off by pressing any
front panel key.
4-9. Free system ringback
This feature is available only when a telephone interconnected ID code is selected. If a busy tone sounds when the
PTT button is pressed, the transceiver enters this mode automatically.
When the PTT button is released, a beep sounds for
400ms to indicate that the mode has been entered. If the
scan is on, it is resumed (the “SCN” mark goes on). When
any repeater becomes available, a ringing tone sounds and
this mode ends.
The mode is terminated when the system, group, scan,
PTT, key is changed.
4-10. System search
This feature can be programmed to automatically access
other programmed systems when the selected system cannot be accessed. If an intercept tone sounds when the PTT
button is pressed after setting the mode, the transceiver
has entered the mode.
If the group ID is a telephone interconnect ID, the transceiver then attempts to access, in succession, other systems that have a telephone interconnect ID in the revert
group location. If the group ID is a dispatch ID, the transceiver attempts to access other systems that have a dispatch ID programmed in the revert group location.
If there is no system to be accessed, an intercept tone
sounds, the mode is terminated, and the transceiver returns
to the first system. If the access is successful, the mode is
terminated, and the searched system becomes the new selected system (If during scanning, the scan stops).
4-11. Transpond
This feature can be programmed to turn on and off for
each group. If the ID of the group for which transpond is
enabled is received, two data messages (transmit ID and
turn-off code) are automatically transmitted if the PTT button is not pressed as a response within the time set (0 to
300 seconds in 1-second increments). If the PTT button is
pressed within the time, the transpond is not preformed.
4-12. Transmit inhibit
The transceiver can be programmed with a transmit inhibit block of ID codes. If an ID code within this block is decoded the preset time before the PTT button is pressed,
transmission is inhibited. The BUSY indicator lights and a
busy tone sounds until the PTT button is released to indicate
that transmission is not possible (except clear-to talk mode).
Transmission with the group for which the encode ID is
not set is inhibited, and the busy tone is output while the
PTT button is held down, regardless of the clear-to -talk setting.
4-13. Auto TEL
A telephone interconnect call can be made by simply
pressing the key by assigning this feature to the key. This
feature accesses the TEL channel of the available system
automatically.
When the key is pressed, a queue tone is output, and the
“AUTO TEL” appears on the alphanumeric display along
with a flashing handset indicator (
mode has been entered. If the TEL ID is set for the revert
system, the TEL channel of that system is accessed. If all
TEL channels are busy, an attempt is made to access the
TEL channels of another system in which the TEL ID code
has been programmed. It is repeated for 60 seconds until
the access succeeds. If the access succeeds, a dial tone
returns from the repeater. If the key is pressed again when
the queue tone is sounding, this mode is canceled.
If the access fails after 60 seconds, a deny tone is output
and this mode is terminated. When the talk ends, the revert
system/group returns. When the scan mode is effective, the
scan resumes. The Auto TEL feature can be programmed to
turn on or off for each system.
) to indicate that this
■ ARQ mode
If affects Trunking mode only. Automatic Repeat Request (ARQ) mode is a manner to minimize the air traffic of
data communication. Also, it enables to occupy the trunking
repeater channel for the data communication period.
■ Data TX with QT/DQT
Whether programmed QT/DQT is modulated or not with
a data transmission except for Selcall. A radio unit can receive a data message regardless of QT/DQT if the receiving
unit is not scanning.
7
TK-480/481
OPERATING FEATURES
5. Option Signalling
5-1. DTMF
Built-in DTMF decoder is available for option signalling.
It is possible to use individual call, group call, D.B.D.
(Dead Beat Disable). D.B.D. is used with DTMF only.
If the option signalling matches, a predetermined action
will occur.
If option signalling matches on a group which is set up
with option signalling, the option signalling indicator (
flash and option signalling will be released. The transpond
or alert tone will sound.
If the selective call alert LED is set up, the orange LED
will flash.
While option signalling matches (or if option signalling is
deactivated when you are transmitting), you can mute or
unmute ID/QT/DQT/Carrier.
■ AND/OR
You can select AND or OR for option signalling match
conditions.
Alert/Transpond
AND QT/DQT/ID+DTMF; Option matches = Action
OR QT/DQT/ID+DTMF; Option matches = Action
AF mute open
AND QT/DQT/ID+DTMF; Option matches = Action
OR QT/DQT/ID; Signalling only matches = Action
) will
■ AND/OR
AND : QT/DQT/ID + MSK to unmute. MSK matches =
alert tone
OR : QT/DQT/ID to unmute. MSK matches = alert tone
6.
Alphanumeric Two-way Paging Function
(FleetSync™)
6-1. General
The Alphanumeric Two-way Paging Function
(FleetSync™) is a Kenwood proprietary protocol. It enables
a variety of paging functions.
6-2. ID Construction
A radio unit ID is defined by a combination of 3-digit Fleet
and 4-digit ID numbers. Each radio unit must be assigned its
own Fleet and ID numbers.
6-3. PTT ID
A pre-programmed unique ID (Own) can be sent at the
beginning of transmission and/or the end of transmission to
identify which radio unit is on air.
When selecting (Sel) for MSK ID, the radio calls the specific Fleet user the same as selective call.
6-4. Selective Call (SELCALL)
This is a voice call to a particular individual or group of
stations.
With OR set up, alert/transpond will not function with
only DTMF.
With OR set up, AF mute will not release when only
DTMF matches.
With a conventional group not set up with QT or DQT,
only the carrier is considered when signalling matches.
■ Auto Reset
If option signalling matches a group set up with option
signalling, option signalling is released. After matching option signalling, option signalling will temporarily reset automatically.
■ Dead Beat Disable
If the D.B.D. code matches, a predetermined action will
occur. Whether option signalling is activated or not, when
D.B.D. matches on any group, the transceiver will become
TX inhibited or TX/RX inhibited. While D.B.D. is active, if the
D.B.D. code + “#” code is received, D.B.D. will disactivate.
When D.B.D. matches, transpond will function. Alert will
not be output, and option signalling match icon will not appear.
5-2. MSK
Built-in MSK (FleetSync™ : Fleet-ID) decoder is available
for option signalling. When the group ID matches, squelch
remains muted while the station waits for reception of
proper MSK signal. When MSK signal matches, squelch
unmutes.
■ Example of call types;
[100][ALL ] : <Group Call>
All the units whose fleet number is “100” are called.
[100][1000] : <Individual Call>
The unit, whose the fleet number is “100” and ID number is “1000”, is called.
[ALL][ALL ] : <Broadcast Call>
All the units are called.
[ALL][1000] : <Supervisor Call>
All ID “1000” are called regardless of their fleet number.
■ Unit ID Encode Block
Encode ID Block can be set to limit manual dial ID. The
radio unit will not accept an ID other than these IDs which
are entered from the keypad. If Inter-fleet Call is enabled,
block ID setting affects each fleet group.
6-5. Status Message
Using a 2-digit number, you can send and receive a Status message which may be decided in your talk group. Each
Status may be displayed with 16 alphanumeric characters if
programmed in the radio. A maximum of 9 received messages can be stored in the stack memory, and it can be reviewed after reception. If the message memory becomes
full, the oldest one will be erased. The stack memory will be
cleared by turning radio power off.
8
OPERATING FEATURES
TK-480/481
■ Status 80~99 (Special)
Status numbers from 80 to 99 are reserved for special
purposes. Entering these statuses from the DTMF keypad
can be inhibited.
Please notice that the following status numbers are used
for special purposes;
80~87 : Reserved for future use.
88 : Terminates to emergency mode.
89 : Request for hornalert (For Mobile).
90 : Remote stun on. Disable the received radio unit’s
TX.
91 : Remote stun on. Disable the received radio unit’s
TX/RX.
92 : Cancel remote stun. Enable the received radio unit’s
TX/RX.
93 : Acknowledgement status sent when the radio unit is
in stun mode (TX disabled).
94 : Acknowledgement status sent when the radio unit is
in stun mode (TX/RX disabled).
95~97 : Reserved for future use.
98 : Man Down Emergency status.
99 : Emergency Status.
Note : Remote stun works with DTMF D.B.D. function also.
■ Automatic Status Response
If you pre-select a status number and leave the radio in
the Status Mode, it can automatically respond with the selected status number upon request from the base station.
(The request function is initiated by serial control on the
base station (Optional).)
6-6. Short Message (Optional)
A maximum of 48 characters can be sent (External equipment is required). Received Short Messages will be displayed in the same manner as a Status Message. A maximum of 4 received messages can be stored in the stack
memory. In the Stack Mode, 3-digit LCD indicates the received Short Message as “M01”~”M04".
6-7. Long Message (Optional)
A maximum of 1024 characters can be sent (External
equipment is required). Received Long Message will not be
displayed or stacked in the radio memory but is output
through the COM (Data) port.
6-8. Emergency Function
Emergency status 99 will be sent at the beginning of
each emergency transmission.
■ FleetSync™ Baud Rate
MSK data baud rate setting. The same rate must be set
as a communication partner.
1200bps :
Data communication is made in 1200bps. The communication area is much wider than 2400bps. Recommended
for repeater operation.
2400bps :
Data communication is made in 2400bps. The communication area is narrower than 1200bps, but it will decrease
the data traffic. Data rate 2400bps may not work properly depending on the repeater’s characteristic.
■ Message Mode Timer
Message Mode Timer is a delay timer returning from
message/stack mode to Normal mode.
■ Status/Short/Long Message on Data Group
Status/Short/Long Message transmission is made
whether on the Data System/Group.
■ Status/Short/Unit ID Message Serial Output
(Option)
Whether a received Status/Short message or PTT ID is
output or not from serial port.
■ Call Alert (Continuous)
The radio can provide the alert tone repeatedly until next
operation.
■ PTT ID Sidetone
This function allows a single beep sound after the PTT ID
(MSK) for FleetSync singalling is encoded.
■ Caller ID Stack
The radio stores the last 3 received caller IDs to volatile
memory.
■ Caller ID Display
PTT ID is displayed on LCD.
6-10. Parameters
■ GTC Count
Number of Go To data Channel messages to be sent before transmitting a data message if it is being made on Data
System/ Group. If a radio unit receives a GTC message, it
will move to the Data System/Group of the current system.
Increase this item to make sure the called radio unit moves
to the Data System/Group.
■ Emergency Status response
“Alert” can be selected for the called radio unit’s response to reception of status 99 which is used as an emergency status.
6-9. Other Functions
■ Manual Dial
Fleet, ID and Status numbers can be entered from DTMF
keypad. (DTMF microphopne is required.)
■ Random Access (Contention)
When a channel (or all the repeater channels for Trunking
mode) is busy, radio unit will not transmit (depending on its
Busy Channel Lockout setting in conventional mode). As
soon as a channel is cleared, some transmissions may
crash. Random access is used to avoid this by employing a
random transmission sequence.
9
TK-480/481
OPERATING FEATURES
■ Number of Retries
Number of Retries is the maximum number of retry
transmission when no acknowledgement is received in the
Maximum ACK Wait Time. Increase this item to improve
data communication reliability.
■ TX Busy Wait Time
TX Busy Wait Time is the maximum amount of time before giving up the data transmission when the channel (or all
the repeater channels for Trunking mode) is busy. Also, this
timer affects if it expires during Random Access period.
■ Maximum ACK Wait Time
Maximum ACK Wait Time is the maximum amount of
time to wait for an acknowledgement from the called radio
unit. It is used as an interval time of retries. It must be set
greater than the ACK Delay Time of the called radio unit.
■ ACK Delay Time
ACK Delay Time is the amount of time from the end of
receiving a data to the beginning of sending an
acknowledgement. It should be adjusted as the repeater’s
hang-up delay time. Also, it must be set less than the Maximum ACK Wait Time of the calling radio unit.
■ TX Delay Time (RX Capture)
TX Delay Time is the amount of unmodulated transmission to let the called unit stop scanning or exit its battery
save mode. It is used only when starting a data communication sequence.
■ Data TX Modulation Delay Time
Data TX Modulation Delay Time is the amount of time
from the beginning of transmission to the beginning of a
data modulation. It is used every time data is transmitted.
It must be set to more than 300ms if data communication is
made in Trunking Mode.
7. Audible User Feedback Tones
The transceiver outputs various combinations of tones to
notify the user of the transceiver operating state. The main
tones are listed below.
The high tone is 1477Hz, the mid tone is 941Hz, and the
low tone is 770Hz.
7-1. Power On Tone
This tone is output when the transceiver is turned on.
(The high tone is output for 500ms.)
7-2. Alert Tone
This tone is output when the transceiver is TX inhibition
for TOT and PLL unlocked. It is output until the PTT button
is released. (The 697Hz tone is output.)
7-3. DBD On Tone
When a D.B.D. code is received, transpond tone sounds.
7-4. DBD Off Tone
When a D.B.D. release code is received, transpond tone
sounds.
7-5. Password Agreement Tone
When the correct password is entered, the tone sounds.
The optional feature's control tone can be set to yes or no.
7-6. PTT Release Tone
When you release the PTT switch, the PTT release tone
sounds.
7-7. Busy Tone
Sounds in LTR mode, when you cannot use a repeater
(system busy or TX inhibit). Sounds in conventional mode,
when busy channel lockout is functioning. You can select
yes or no for the optional feature's warning tone.
7-8. Group Call Tone
Sounds when a group call with the correct DTMF option
signalling is received, repeats 7 times. You can select yes or
no for the optional feature's warning tone.
7-9. Individual Call Tone
Sounds when an individual call with the correct DTMF
option signalling is received. You can select yes or no for
the optional feature's warning tone.
7-10. Key Press Tone [A]
Sounds when a key is pressed. For toggle keys, sounds
when toggle function is turned on (key press tone [B]
sounds when it is turned off). You can select yes or no for
the optional feature's control tone.
7-11. Key Press Tone [B]
Sounds when a key is pressed. For toggle keys, sounds
when the toggle function is turned off (key press tone [A]
sounds when it is turned on). You can select yes or no for
the optional feature's control tone.
7-12. Key Press Tone [C]
Sounds when a key is pressed. Also sounds when storing data, adding a DTMF code to memory, and when changing test mode settings. You can select yes or no for the
optional feature's control tone.
7-13. Key Input Error Tone
Sounds when a key is pressed but that key cannot be
used. You can select yes or no for the optional feature's
warning tone.
7-14. Roll Over Tone
Sounds at the smallest system/group. You can select
yes or no for the optional feature's control tone.
7-15. Transpond Tone
Sounds when an individual call with the correct LTR/
DTMF option signalling is received. For group calls, only the
group tone will sound, not the transpond tone.
10
TK-480/481
User mode
Panel test mode
PC mode
Firmware programming mode
Panel tuning mode
Data programming mode
PC test mode PC tuning mode
Clone mode
OPERATING FEATURES / REALIGNMENT
7-16. Intercept Tone
This tone indicates that the transceiver is out of range. It
indicates that the PTT button is pressed, and transmission
has started, but the repeater cannot be connected and talking is not possible. It is output until the PTT button is released. (The mid tone and low tone are output alternately in
200ms intervals.)
7-17. Delay Tone
This tone is output when the PTT button is pressed and
the repeater is accessed three times or more to indicate
connection with the repeater is delayed. This tone is the
same as the busy tone. (It is not output of clear to talk has
been set to yes.)
7-18. Proceed Tone
This tone is output when the PTT button is pressed,
transmission starts, and the repeater is connected to indicate that the user can talk if the clear to talk function has
been set. (The high tone is output for 100ms.)
7-19. Queue Tone
This tone is output until the auto TEL function is set and
the TEL channel is accepted successfully. (The mid tone on
for 50ms, off for 50ms, and on for 50ms in 1 second intervals.)
7-20. Deny Tone
This tone is output if the auto TEL function is set, the
queue tone is output, but the TEL channel cannot be accessed within 60 seconds. It is similar to the intercept tone.
(The mid tone and low tone are output alternately in 150ms
intervals.)
7-21. Free System Ringback Mode Tone, System
Search Mode Tone
This tone indicates that the transceiver is free system
ringback mode or system search mode. (The mid tone is
output for 400ms.)
7-22. Ringing Tone
This tone indicates that the transceiver can use the repeater in free system ringback mode. (The mid tone and no
tone are output eight cycles alternately in 50ms intervals.)
7-23. System Search Tone
Sounds when the system changes during system search.
You can select yes or no for the optional feature's warning
tone.
REALIGNMENT
1. Modes
Mode Function
User mode For normal use.
Panel test mode Used by the dealer to check the funda-
mental characteristics.
Panel tuning mode Used by the dealer to tune the radio.
PC mode Used for communication between the
radio and PC (IBM compatible).
Data program- Used to read and write frequency data
ming mode and other features to and from the radio.
PC test mode Used to check the radio using the PC.
This feature is included in the FPU.
See panel tuning.
Firmware program- Used when changing the main program
ming mode of the flash memory.
Clone mode Used to transfer programming data from
one radio to another.
2. How to Enter Each Mode
Mode Operation
User mode Power ON
Panel test mode [A]+Power ON (Two seconds)
PC mode Received commands from PC
Panel tuning mode [Panel test mode]+[S]
Firmware programming mode [S]+Power ON (Two seconds)
Clone mode [C]+Power ON (Two seconds)
3. Panel Test Mode
Setting method refer to ADJUSTMENT.
7-24. System Search End Tone
Sounds when a possible connection to a repeater in system search is not mode. You can select yes or no for the
optional feature’s warning tone.
4. Panel Tuning Mode
Setting method refer to ADJUSTMENT.
11
TK-480/481
REALIGNMENT
5. PC Mode
5-1. Preface
The TK-480/481 transceiver is programmed by using a
personal computer, programming interface (KPG-36) and
programming software (KPG-49D).
The programming software can be used with an IBM PC
or compatible. Figure 1 shows the setup of an IBM PC for
programming.
5-2. Connection procedure
1. Connect the TK-480/481 to the personal computer with
the interface cable.
2. When the POWER switch on, user mode can be entered
immediately. When PC sends command the radio enter
PC mode, and “PROGRAM” is displayed on the LCD.
When data transmitting from transceiver, the red LED is
blinking.
When data receiving to transceiver, the green LED is
blinking.
Notes:
• The data stored in the personal computer must match
model type, when it is written into the flash memory.
• Change the TK-480/481 to PC mode, then attach the interface cable.
5-3. KPG-36 description
(PC programming interface cable: Option)
The KPG-36 is required to interface the TK-480/481 to the
computer. It has a circuit in its D-subconnector (25-pin) case
that converts the RS-232C logic level to the TTL level.
The KPG-36 connects the universal connector of the TK-
480/481 to the computers RS-232C serial port.
5-4. Programming software description
The KPG-49D programming disk is supplied in 3-1/2" disk
format. The software on this disk allows a user to program
TK-480/481 radios via programming interface cable (KPG-
36).
5-5. Programming with IBM PC
If data is transferred to the transceiver from an IBM PC
with the KPG-49D, the destination data (basic radio information) for each set can be modified. Normally, it is not necessary to modify the destination data because their values are
determined automatically when the frequency range (frequency type) is set.
The values should be modified only if necessary. Data
can be programmed into the flash memory in RS-232C format via the universal connector.
KPG-49D instruction manual parts No. : B62-1096-XX
IBM-PC
KPG-36
KPG-49D
Fig. 1
6. Firmware Programming Mode
6-1. Preface
Flash memory is mounted on the TK-480/481. This allows
the TK-480/481 to be upgraded when new features are released in the future. (For details on how to obtain the firmware, contact Customer Service.)
6-2. Connection procedure
Connect the TK-480/481 to the personal computer (IBM
PC or compatible) with the interface cable (KPG-36). (Connection is the same as in the PC Mode.)
6-3. Programming
1. Start up the programming software (KPG-49D), select
“firmware program” in the “Program” item, and press
the Return key on the personal computer. This starts up
the firmware programmer.
2. The top screen is displayed. Press any key to advance to
the next screen.
3. Set the communications speed (normally, 57600 bps)
and communications port in the Setup item.
4. Set the firmware to be updated by File select (=F1).
5. Turn the TK-480/481 power ON with the [S] switch held
down. Hold the switch down for two seconds until the
display changes to “PROG 57600”. When “PROG
57600” appears, release your finger from the switch.
6. Check the connection between the TK-480/481 and the
personal computer, and make sure that the TK-480/481 is
in the Program mode.
7. Press F10 on the personal computer. A window opens on
the display to indicate progress of writing. When the TK-
480/481 starts to receive data. the [P] icon is blinking.
8. If writing ends successfully. the LED on the TK-480/481
lights and the checksum is displayed.
9. If you want to continue programming other TK-480/481 s,
repeat steps 5 to 8.
12
REALIGNMENT
TK-480/481
Notes:
• To start the Firmware Programmer from KPG-49D, the
Fpro path must be set up by KPG-49D Setup.
• This mode cannot be entered if the Firmware Programming mode is set to Disable in the Programming software (KPG-49D).
• When programming the firmware, it is recommend to
copy the data from the floppy disk to your hard disk before update the radio firmware.
Directry copying from the floppy disk to the radio may not
work because the access speed is too slow.
6-4. Function
1. If you press the [MON] switch (top of left side) while
“PROG 57600” is displayed, the checksum is displayed.
If you press the [MON] switch again while the checksum
is displayed, “PROG 57600” is redisplayed.
2. If you press the [LAMP] switch (bottom of left side) while
“PROG 57600” is displayed, the display changes to
“PROG 19200” to indicate that the write speed is low
speed (19200 bps). If you press the [LAMP] switch again
while “PROG 19200” is displayed, the display changes to
“PROG 38400”, and the write speed becomes the
middle-speed mode (38400 bps). If you press the [LAMP]
switch again while “PROG 38400” is displayed, the display returns to “PROG 57600”.
How to enter the password with the encoder;
If the encoder is rotated while “CLONE LOCK” is displayed, numbers (0 to 9) are displayed flashing. When
you press the [S] key, the currently selected number is
determined. If you press the [S] key after entering the
password in this procedure, “CLONE MODE” is displayed if the entered password is correct. If the password is incorrect, “CLONE LOCK” is redisplayed.
4. Power on the slave TK-480/481.
5. Connect the cloning cable (No. E30-3325-05) to the universal connectors on the master and slave.
6. Press the [S] key on the master while the master displays
“CLONE MODE”. The data of the master is sent to the
slave. While the slave is receiving the data, “PROGRAM”
is displayed. When cloning of data is completed, the master displays “END”, and the slave automatically operates
in the User mode. The slave can then be operated by the
same program as the master.
7. The other slave can be continuously cloned. When the [S]
key on the master is pressed while the master displays
“END”, the master displays “CLONE MODE”. Carry out
the operation in step 4 to 6.
Note:
Only the same models can be cloned together.
Note:
Normally, write in the high-speed mode.
7. Clone Mode
Programming data can be transferred from one radio to
another by connecting them via their external universal connectors. The operation is as follows (the transmit radio is the
master and the receive radio is a slave).
1. Turn the master TK-480/481 power ON with the [C] key
held down. If the password is set to the TK-480/481, the
TK-480/481 displays “CLONE LOCK”. If the password is
not set, the TK-480/481 displays “CLONE MODE”.
2. When “CLONE LOCK” is displayed, only the knob (en-
coder) and [S], and [0] to [9] keys can be accepted. When
you enter the correct password, and “CLONE MODE” is
displayed, the TK-480/481 can be used as the cloning
master. The following describes how to enter the pass-
word.
3. How to enter the password with the keypad;
If you press a key while “CLONE LOCK” is displayed.
The number that was pressed is displayed on the TK-480/
481. Each press of the key shifts the display in order to
the left. When you enter the password and press the [S]
key, “CLONE MODE” is displayed if the entered pass-
word is correct. If the password is incorrect, “CLONE
LOCK” is redisplayed.
Cloning cable
(E30-3325-05)
Fig. 2
13
TK-480/481
CIRCUIT DESCRIPTION
1. Overview
This transceiver is an 800/900MHz band EFJ LTR™
trunked system compatible FM portable transceiver that can
be programmed to operate on both LTR and conventional
systems.
2. Circuit Configuration by Frequency
The receiver is a double-conversion superheterodyne
with a first intermediate frequency (IF) of 44.85MHz and a
second IF of 455kHz. Incoming signals from the antenna are
mixed with the local signal from the PLL to produce the first
IF of 44.85MHz.
This is then mixed with the 44.395MHz second local os-
cillator output to produce the 455kHz second IF. This is detected to give the demodulated signal.
The transmit signal frequency is generated by the PLL
VCO, and modulated by the signal from the microphone. It
is then amplified and sent to the antenna.
TK-480
TX 806~825MHz
851~870MHz
RX 851~870MHz
ANT
ANT
SW
PA
AMP
RF
AMP
TX
AMP
TK-481
TX 896~902MHz
935~941MHz
RX 935~941MHz
1st MIX
44.85MHz
TK-480 :
806.15~825.15MHz
TK-481 :
890.15~896.15MHz
TK-480
806~825MHz
851~870MHz
MCF
TK-481
896~902MHz
935~941MHz
CF
455kHz
IF SYSTEM
44.395
MHz
PLL
VCO
AF
AMP
MIC
AMP
SP
MIC
3. Receiver System
3-1. RF unit
An incoming RF signal from the antenna terminal is
passed through the antenna switch (D7, D9, and D10 are
off) and then the bandpass filter (L11). The signal is amplified by RF amplifier Q9, and passed through the bandpass
filter (L20) to remove the spurious signal again. The resulting signal is applied to the first mixer (Q6), where it is mixed
with the first local oscillator signal output from the frequency synthesizer to produce the first IF (44.85MHz).
3-2. IF unit
The first IF signal is passed through a four-pole monolithic crystal filter (XF1) to remove a adjacent channel signal.
The filtered first IF signal is amplified by the first IF amplifier
(Q5) and then applied to the IF system IC (IC9). The IF system IC provides a second mixer, second local oscillator, limiting amplifier, quadrature detector and RSSI (Received Signal Strength Indicator). The second mixer mixes the first IF
signal with the 44.395MHz of second local oscillator output
(crystal unit X1) and produces the second IF signal of
455kHz.
The second IF signal is passed through the ceramic filter
(CF1,2) to more remove the adjacent channel signal. The
filtered second IF signal is amplified by the limiting amplifier
and demodulated by the quadrature detector with ceramic
discriminator (CD1). The demodulated signal is routed to
the audio circuit.
14
Fig. 1 Frequency configuration
ANT
IC12
5
L30 D9,D10
HPF
ANT
SW
2
LPF
L11
BPFQ9RF AMP
1
HPF BEF
L20
BPFQ61st MIX
1st local
OSC (PLL)
DE-
EMP
EXP
XF1
MCFQ51st IF
MUTE
41
Fig. 2 Receiving system
X1
2nd local
OSC
IC3 (2/2)
AF AMP
IC9
MIX,DET,IF
IC4
VOL
IC8 (2/2)
AF AMP
AF AF
CF1
CF2
Q310
SW
SSW
VC1
VC2
IC300
AF PA
EXT.
SP
INT.
SP
CIRCUIT DESCRIPTION
SQ voltage
ANT input level
SQ close
SQ open
RSSI voltage
ANT input level
Preset
value
Preset
value
TK-480/481
3-3. Audio amplifier circuit
The demodulated signal from IC9 is amplified by IC8 (2/
2), high-pass filtered, low-pass filtered, high-pass filtered,
band-eliminate filtered,and de-emphasized by IC12.
The signal then goes through an AF amplifier IC3 (2/2), an
electronic volume control (IC4), and an AF switch (Q310 is
on), and is routed to audio power amplifier (IC300), where it
is amplified and output to the internal speaker.
The audio mute signal (AM) from the microcomputer becomes Low in the standby and Q304, Q305 which are
power supply circuit for IC300 turn off. Also, IC12 is set to
the power down mode according to data from microprocessor, and the AF signal is muted. When the audio is output,
AM becomes High to turn Q304, Q305 ON, and voltage is
supplied to power terminal VP of IC300. Also, IC12 is canceled out of the power down mode.
The speaker is switched by the logic of speaker switching terminal SSW on the universal connector. When SP-MIC
is not attached, the logic of SSW becomes High and SW
(Q310) is turned ON, and the AF signal is input to both amplifiers of IC300.
When SP-MIC is attached, SSW is connected to GND at
inside of SP-MIC. For this reason, Q310 is turned OFF, and
the AF signal is input only to amplifier for EXT SP of IC300.
Change of INT/EXT SP refer to Fig. 3.
AM SSW VC1 VC2 SP
H H H L INT
H L L H EXT
L H L L MUTE
L L L L MUTE
3-4. Squelch circuit
The output from IC9 enters FM IC again, then passed
through a band-pass filter. The noise component output
from IC9 is amplified by Q19 and rectified by D3 to produce
a DC voltage corresponding to the noise level. The DC voltage is sent to the analog port of the CPU (IC15). And IC9
outputs a DC voltage (RSSI) corresponding to the input of
the IF amplifier. The CPU reads the RSSI signal via pin 24.
IC15 determines whether to output sounds from the
speaker by comparing the input voltage of pin 28 and pin 24
with the preset value.
IC9 : FM IF IC
IF AMP
DET
RSSI BPF
12
AMP
7
Q19 D3
NOISE
AMP
DET
28
IC15
CPU
24
Fig. 4 Squelch circuit
SB
AF
AM
SSW
Q301
Q308
Q305
Q304
SW
VC1
2
VC2
8
Fig. 3 Audio amplifier circuit
VP
IC300
Fig. 5
5
INT. SP
4. Transmitter System
Squelch and RSSI voltage vs ANT input level
4-1. Microphone amplifier
EXT. SP
The signal from the internal microphone goes through
the mute switch (Q300).
When the SP-MIC is not attached, the microphone
switching terminal (MSW) on the universal connector becomes High, and mute switch (Q300) is turned ON. When
the SP-MIC is attached, MSW is connected to GND at inside
of SP-MIC. For this reason, Q300 is turned OFF, the internal
microphone is muted, and only the input of the external microphone is supplied to the microphone amplifier of the TXRX unit.
15
TK-480/481
CIRCUIT DESCRIPTION
The signal from microphone passes through the limitter
circuit in D11, and through the high-pass filter, the ALC circuit, the low-pass filter, the high-pass filter, and pre-emphasis/IDC circuit in IC12. When encoding DTMF, mute switch
(Q7) is turned OFF for muting the microphone input signal.
The signal passes through the D/A converter (IC4) for the
maximum deviation adjustment, and enters the summing
amplifier consisting of IC3 (2/2), and is mixed with the low
speed data from the CPU (IC15).
The output signal from the summing amplifier passes
through the D/A converter (IC4) again for the TA maximum
deviation adjustment,and the AF switch (Q21 is off in TX),
and goes to the VCO modulation input.
The other output signal from the summing amplifier
passes through the D/A converter (IC4) again for the BAL
adjustment,and the buffer amplifier (IC1 (2/2)), and goes to
the VCXO modulation input.
EXT.
MIC
Q300
MIC
SW
MIC
D11
LIMIT
12
HPF ALC
4-2. Drive and Final amplifier
The signal from the T/R switch (D5 is on) is amplified by
the pre-drive (Q11) and drive amplifier (Q12) to 50mW.
The output of the drive amplifier is amplified by the RF
power amplifier (IC30) to 2.5W (1W when the power is low).
The RF power amplifier consists of two stages MOS FET
transistor. The output of the RF power amplifier is then
passed through the harmonic filter (LPF) and antenna switch
(D7 is on) and applied to the antenna terminal.
4-3. APC circuit
The APC circuit always monitors the current flowing
through the RF power amplifier (IC30) and keeps a constant
current. The voltage drop at R127, R128 and R129 is caused
by the current flowing through the RF power amplifier and
this voltage is applied to the differential amplifier (IC21 1/2).
IC21 (2/2) compares the output voltage of IC21 (1/2) with
the reference voltage from IC4, and the output of IC21 (2/2)
controls the VGG of the RF power amplifier to make the
both voltages to same voltage.
The change of power high/low is carried out by the
change of the reference voltage. Q14,15 and 18 are turned
on in transmit and the APC circuit is active.
DTMF
98IC12
19
PRE EMP
IDC
6
Q7
15
16
COMP LPF HPF
MUTE
SW
18
MSW
Q301
IC4
D/A
I5
O5
LSD
IC3 (2/2)
SUM
AMP
IC4
D/A
O2
I2
IC4
D/A
O1
I1
Fig. 6 Microphone amplifier
From
T/R SW
(D5)
+B
REF
VOL
(IC4)
Q11
Pre-DRIVE
AMP
R127
R128
R129
Q12
DRIVE
AMP
IC21
(1/2)
IC30
RF
POWER AMP
VDD VGG
IC21
(2/2)
LPF
Fig. 7 Drive and final amplifier and APC circuit
Q21
AF
MUTE
5R
IC1
BUFF
AMP
D7
ANT
SW
IC14
VCO
X2
VCXO
ANT
16
CIRCUIT DESCRIPTION
TK-480/481
5. Frequency Synthesizer Unit
5-1. Frequency synthesizer
The frequency synthesizer consists of the VCXO (X2),
VCO (IC14), PLL IC (IC11) and buffer amplifiers.
The VCXO generates 16.8MHz. The frequency stability is
1.5ppm within the temperature range of –30 to +60°C. The
frequency tuning and modulation of the VCXO are done to
apply a voltage to pin 1 of the VCXO. The output of the
VCXO is applied to pin 8 of the PLL IC.
The TK-480’s VCO covers a dual range of the 806~
825MHz, and the 851~870MHz. The VCO generates
806.15~825.15MHz for providing to the first local signal in
receive. In TA mode, the pin 1 of the VCO goes low and the
VCO generates 851~870MHz.
The TK-481’s VCO covers a dual range of the 896~
902MHz, and the 935~941MHz. The VCO generates
890.15~896.15MHz for providing to the first local signal in
receive. In TA mode, the pin 1 of the VCO goes low and the
VCO generates 935~941MHz.
The output of the VCO is amplified by the buffer amplifier
(Q8) and routed to the pin 5 of the PLL IC. Also the output of
the VCO is amplified by the two-buffer amplifier (Q10, Q17)
and routed to the next stage according to T/R switch (D4,
D5).
The PLL IC consists of a prescaler, fractional divider, reference divider, phase comparator, charge pump. This PLL
IC is fractional-N type synthesizer and performs in the
100kHz reference signal which is eighth of the channel step
(12.5kHz). The input signal from the pins 1 and 5 of the PLL
IC is divided down to the 100kHz and compared at phase
comparator. The pulsed output signal of the phase comparator is applied to the charge pump and transformed into
DC signal in the loop filter (LPF). The DC signal is applied to
the pin 3 of the VCO and locked to keep the VCO frequency
constant.
PLL data is output from DT (pin 52), CP (pin 64) and EP
(pin 69) of the microprocessor (IC15). The data are input to
the PLL IC when the channel is changed or when transmission is changed to reception and vice versa. A PLL lock condition is always monitored by the pin 21 (UL) of the microprocessor. When the PLL is unlocked, the UL goes low.
6. Control Circuit
The control circuit consists of microprocessor (IC15) and
its peripheral circuits. It controls the TX-RX unit and transfers data to and from the display unit. IC15 mainly performs
the following;
1) Switching between transmission and reception by PTT
signal input.
2) Reading system, group, frequency, and program data
from the memory circuit.
3) Sending frequency program data to the PLL.
4) Controlling squelch on/off by the DC voltage from the
squelch circuit.
5) Controlling the audio mute circuit by decode data input.
6) Transmitting tone and encode data.
6-1. Memory circuit
Memory circuit consists of the CPU (IC15) and a flash
memory (IC17), a flash memory has a capacity of 2M bits
that contains the transceiver control program for the CPU
and data such as transceiver channels and operating features.
This program can be easily written from an external devices. The data, such as operating status, is programmed
into the EEPROM (IC16).
• Flash Memory
Note : The flash memory holds data such as written with
the FPU (KPG-49D), firmware program (User mode, Test
mode, Tuning mode, etc.) This data must be rewritten when
replacing the flash memory.
• EEPROM
Note : The EEPROM stores tuning data (Deviation, Squelch,
etc.).
Realign the transceiver after replacing the EEPROM.
IC15
CPU
IC16
EEPROM
TA
(TA : Low)
UL
CPU
IC15
BUFF
VCXO
Q10
BUFF
Q8
MB
TA
LPF
DT,CP,EP
18
IC14
VCO
IC11
PLL
CV
5
8
Fig. 8 PLL block diagram
Q17
BUFF
IC1
SW
To mixer
FC
BAL
D4
D5
SW
To
drive
amp
FLASH
IC17
Fig. 9 Memory circuit
17
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