Abell A720T User manual

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A720T (VHF) Service Manual
ABELL INDUSTRIES CO., LTD

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CONTENT
CHAPTER 1 INTRODUCTION..............................................................................................................................................4
1.1 SCOPE OF APPLICATION...............................................................................................................................................4
1.2 SECURITY ISSUES............................................................................................................................................................4
CHAPTER 2 STRUCTURE AND KEY FUNCTIONS......................................................................................................... 5
2.1 STRUCTURE...................................................................................................................................................................... 5
CHAPTER 3 COMPOSITE MODE........................................................................................................................................7
3.1 MODE...................................................................................................................................................................................7
3.2 HOW TO ENTER EACH MODE..................................................................................................................................... 7
3.3 PC MODE............................................................................................................................................................................ 7
3.3.1 PREFACE..........................................................................................................................................................................7
3.3.2 CONNECTION STEPS........................................................................................................................................................7
CHAPTER 4 DISASSEMBLED PARTS IN MAINTENANCE PROCESS........................................................................ 9
4.1 DISASSEMBLE THE RADIO...........................................................................................................................................9
4.2 EXPLOSIVE VIEW.......................................................................................................................................................... 10
CHAPTER 5 UNIT CIRCUIT............................................................................................................................................... 11
5.1 DMR DIGITAL CIRCUIT SIGNAL BLOCK DIAGRAM........................................................................................... 11
5.2 ANALOG CIRCUIT STRUCTURE................................................................................................................................ 11
5.3 RECEIVER........................................................................................................................................................................ 12
5.3.1 FRONT-END RADIO-FREQUENCY AMPLIFIER.................................................................................................................. 12
5.3.2 FIRST FREQUENCY MIXER............................................................................................................................................. 13
5.3.3 INTERMEDIATE FREQUENCY AMPLIFIER (IF AMP).......................................................................................................13
5.3.4 AF AMPLIFIER...............................................................................................................................................................13
5.3.5 NOISE SUPPRESSION CIRCUIT....................................................................................................................................... 13
5.4 PHASE LOCKED FREQUENCY SYNTHESIZE.........................................................................................................14
5.4.1 PLL CIRCUIT.................................................................................................................................................................14
5.4.2 UNLOCKED DETECTOR................................................................................................................................................. 15
5.5 TRANSMITTER............................................................................................................................................................... 15
5.5.1 RF AUDIO..................................................................................................................................................................... 15
5.5.2 QT/DQT/4FSK CODING...............................................................................................................................................15
5.5.3 WIDE/NARROW BAND SWITCH.....................................................................................................................................15
5.5.4 VOLTAGE-CONTROLLED OSCILLATOR(VCO) AND RF AMPLIFIER................................................................................16
5.5.5 ANTENNA TRANSFER SWITCH AND LPF........................................................................................................................16
5.5.6 POWER CONTROL..........................................................................................................................................................16
5.5.7 TEMPERATURE PROTECTION CIRCUIT........................................................................................................................... 16
5.6 POWER SUPPLY..............................................................................................................................................................17

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5.7 CPU CONTROL SYSTEM.............................................................................................................................................. 18
CHARTER 6 FUNCTIONS AND CONFIGURATIONS.................................................................................................... 19
6.1 FUNCTION DEFINITION AND PARAMETER CONFIGURATION...................................................................... 19
6.1.1 CHANNEL...................................................................................................................................................................... 19
6.1.2 SCAN.............................................................................................................................................................................19
6.1.3 POWER/BATTERY SAVE................................................................................................................................................. 19
6.1.4 VOX............................................................................................................................................................................. 20
6.1.5 TOT.............................................................................................................................................................................. 20
6.1.6 HIGH/LOW POWER SWITCH.......................................................................................................................................... 20
6.1.7 SQUELCH LEVEL........................................................................................................................................................... 20
6.1.8 RECEIVE AND MAKE CALL...........................................................................................................................................20
6.1.9 RADIO CHANNEL, RADIO ID AND GROUP ID............................................................................................................... 20
6.1.10 LOW BATTERY WARNING............................................................................................................................................ 22
6.2 CONFIGURATIONS........................................................................................................................................................ 23
6.2.1 SQUELCH LEVEL........................................................................................................................................................... 23
6.2.2 HIGH/LOW POWER SWITCH.......................................................................................................................................... 23
6.2.3 VOX............................................................................................................................................................................. 23
6.2.4 PROMPT TONE TURN ON/OFF....................................................................................................................................... 23
6.2.5 CHECK BATTERY CHARGING STATUS............................................................................................................................23
6.2.6 CTCSS..........................................................................................................................................................................24
6.2.7 CDCSS......................................................................................................................................................................... 24
CHAPTER 7 RADIO DEBUGGING.................................................................................................................................... 25
7.1 THE REQUIRED TEST EQUIPMENT......................................................................................................................... 25
7.2 DEBUGGING INTRODUCTION................................................................................................................................... 27
CHAPTER 8 PARAMETERS................................................................................................................................................32
BILL OF MATERIALS (ELECTRONICS)..........................................................................................................................34
FIG.1 A720T BIT MAP...........................................................................................................................................................49
TOP SIDE：.............................................................................................................................................................................49
BOT SIDE：............................................................................................................................................................................ 50
FIG. 2 A720T SCHEMATIC DIAGRAM.......................................................................................................................... 51
FIG. 3 A720T BLOCK DIAGRAM.................................................................................................................................... 55
FIG. 4 A720T PACKING..................................................................................................................................................... 56

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Chapter 1 Introduction
1.1 Scope of application
This manual is written for technicians who well know communication profession and have maintenance experience. It
includes all information and existing published data required by the equipment maintenance. The change may happen
after its publication, if required, you can use repair bulletin and manual revised edition as supplement.
Before repair the equipment, please read this manual first.
1.2 Security Issues
Safe power radiation of two way radio
Two way radios can produce and emit electromagnetic energy to outside, and electromagnetic transmission safety
design of ABELL two way radio completely conforms with national and international standard. In order to ensure the
best communication effect of two way radio and the electromagnetic transmission safety for human, when you use
two way radios for communication, please keep the two way radio perpendicular to the ground, and your month away
from microphone 2.5-5 cm.
Electromagnetic interference
In order to avoid electromagnetic interference, please turn off two way radio when you are in the places where there is
clear indication to turn off the two way radio (such as hospital, airport)
Explosive environment
You'd better turn off two way radio when in explosive environment.
Please turn off two way radio when in gas station or parking there.
Please turn it off when near electric fuse.
It is strictly prohibited to replace or recharge battery in the place where there is potentially explosive air.
Damaged antenna
When antenna is damaged, you better not to use two way radios. When the damaged antenna touches human skin, it
may cause mild burn.
Parts replacement
When start to replace any parts, please note the type, don't randomly use the components which differ from the
information provided by the company.
Maintenance service
In order to repair the equipment, we set up a completed service system, and provide the material including schematic
diagram, printed substrate as your reference.

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Chapter 2 Structure and key functions
2.1 Structure
○
1○ 3○ 4 Programmable function key:These keys are programmable function keys; Long press (key-press
time should reach the time we set for long press key) and short press (normal key), which can be set for different
functions. Press it to enable programmable auxiliary functions.
Your dealers can can program key 1, 3 and 4 to add hotkeys and preset channel/group:
Short press: quick press and then release
Long press: Keep pressing for several seconds(preset time between 0.25s to 3.75s )
No function: If you preset this key as no function, it will warn you when pressing it.
○
2PTT key:Press this switch, and then call the opposite by microphone. Release the switch to listen.
○
5 Antenna
○
6 Knob: Channel switch
Rotate it from channel 1 to channel 32. (note: there are totally 32 channels in two areas of A720T)
○
7 Knob: Power on/off and Volume control
Clockwise rotate it to turn on the two way radio power, you will hear a sound of "click", then continuously rotate it to

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adjust volume. When you want to turn off two way radio, counter-clockwise rotate the knob until hear a sound of
"click".
Note: if you turn off the power on sound when programming, you will not hear the power on sound.Check the battery
when power on failure to make sure battery installed properly. If you still cannot power on the radio, please contact
the dealer. Clockwise to higher the volume
○
8 Luminous diode Indicator
It shows red when transmitting; It shows green when power on, receiving or detecting signal; Red flashes when low
battery.
○
9Speaker
○
10 Dust cover for earpieces and programming

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Chapter 3 Composite Mode
3.1 Mode
Mode type
Function
User mode
This mode is used for general operation
PC mode
By this mode, use external programming cable to make various settings
Debugging mode
Adjust parameter of machine
3.2 How to enter each mode
Mode type
Operation steps
user mode
Boot whilst automatically come into user mode
PC mode
Use programming cable to connect with PC
Debugging mode
Through programming software, come into debugging mode.
3.3 PC mode
3.3.1 Preface
Use programming cable to connect A720T and PC, operate programming software (ABELL A720T programming
software) on PC to make programming setting for communication equipment. Figure 1 shows the process of
programming setting on PC.
3.3.2 Connection Steps
1. Use programming cable to connect A720T and PC
2. Operate programming software (ABELL A720T programming software).
3. Set the communication port.
4. Conduct various programming operation on two way radio.
5. When the radio transmit, red light is blinking. When the radio receives, green light is blinking.
User mode
Debugging mode
PC mode

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Notice：
When data is written into EEPROM, the data stored in PC must conform with model of radio. Turn on power of
radio only on condition that the software must run and cable must be connected.
In the course of transmitting or receiving data, do not press [PTT] key.
Programming cable (optional):
Connect A720T with PC using programming cable.
Programming S/W
ABELL A720T programming software (installed) allow users to conduct programming setting on A720T through
programming interface cable.
Program on PC
If use PC with ABELL two way radio programming for transmitting data to radio, the setting destination data (basic
communication parameters) can all be modified. as the value is automatically generated in setting frequency
range(frequency type), generally it is not necessary to change destination data. the value can be changed only in
necessary condition. The data in form of RS-232C can be input into EEPROM, in this mode, the function of PTT line
can be served for sending and receiving data.

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Chapter 4 Disassembled parts in maintenance process
4.1 Disassemble the radio
1. Remove two screws and take away the belt clip
2. Rotate to remove antenna
3. Pull out volume and channel knob
4. Remove waterproof ring
5. Remove antenna base
6. Remove waterproof screw nut
7. Remove 4 screws
8. Pull out the logo sticker
9. Remove 2 screws
10. Pull housing
11. Use the soldering iron to melt the tin on speaker
wire. Then you can separate up case and aluminum
housing part.
12. Remove 6 screws and 2 copper screw nuts.
13. Up warp two BTB
14. Against battery connector from back then lift
PCB part

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4.2 Explosive View

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Chapter 5 unit circuit
5.1 DMR digital circuit Signal block diagram
4FSK digital signal channel process of Block diagram of DMR digital circuit:
Via MIC, voice comes into NJM2904V, being amplified; After that DSP digital signal is processed to 4FSK
digital modulating signal, which are sent to VCO and crystal modulator by two ways as MDO1/MOD2, then sent
out by transition circuit.
The 4FSK digital modulation signal received by receiving circuit is sent to SCT3258TD DSP digital signal
processing; and it was demodulated by AMBE3000 to be 4FSK digital audio signal; then TDA2822 power
amplifier will magnify and drive SP speaker.
B AP6 5-03
Q 501
RF AMP
ANT
F50 0
58.05MHz
C F300
45 0 KHz
IF SYS TEM
U307
TDA28 22
SP
SC T32 58
IP data port
MIC
U306
NJM2904
U601
PLL VC O
RX
TX
Q 4
TX AMP
Q 3
PA AMP
DMR Circuit Structure
U302
data/vocie port
AMBE-3 00 0
En coder/Decod er
AD/DA swi tchFrame En codi ng
Frame De codi ng
Modu la ti on
Frame H eader/Vaild Date
Dem odul ation
TDMA
IF
19.2M
MO D2
MO D1
U500
D1 D3
X6 00
Voi ce
AK236 5A
5.2 Analog Circuit Structure
Receiver is working on double conversion superheterodyne mode,first intermediate frequency is 58.05MHz, second
Intermediate Frequency is 450KHz. The first vibration signal is provided by the phase-locked loop (PLL).
Required frequency by transmitter is come directly from PLL.

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ANT
F50 0
58.05MHz
C F300
450 KH z
U500 IF
57.6MHz
U307
TDA28 22
SP
X6 00
19.2MHz
Q 601
MIC
U306
NJM2904V
U601 Q 601 Q 602
PLL VCO
RX
TX
Chart 1 Analog Circuit Structure
AK236 5A
Q 501
RF AMP
B AP6 5-03
Q 4
TX AMP
Q 3
PA AMP
D1 D3
5.3 Receiver
Receiver is working on double conversion superheterodyne mode, its rated operation frequency range is
136-174MHz.
5.3.1 Front-end radio-frequency amplifier
Signal received by antenna comes into low pass filter and receiving/transmission switching diode (D1, D3 and D501,
D502 are disconnected), the unwanted signal is filtered out by secondary LC band-pass filter, go through RF overload
protection diode(D505), go into RF amplifier(Q501) and amplified by it, after which the signal will go through third
level LC band-pass filter and unwanted signal will be filtered out, wanted signal will be allowed to go into first mixed
frequency(Q502).
Due to the limited working bandwidth of LC band-pass filter, the required bandwidth is achieved by AFC automatic
frequency control voltage adjusting varactor diode (D503-D507) capacitor value. AFC voltage is controlled by U300
microprocessor center frequency (see Figure 2).
ANT SW
ANT
D1.D3
SP
L502 L503
BPF
APC/T V
TUNE
U300
CPU
Q501
RF AMP
L509 L510
BPF
Q502
MIXER
1ST LOCAL OSC
(PLL)
F300
MCF Q503
IF AMP
TC XO 19.2M
U500
IF, AK2365A
CF300
MUITLPLY
Q601
LPF,HPF
U500
U306
TDA2822
Chart 2 Receiving Circuit
D503 D504 D506 D507
450KHZ
58.05MHZ

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5.3.2 First frequency mixer
The signal from the RF amplifier is mixed with the first oscillator signal from the PLL frequency synthesizer circuit at
the first mixer (Q502) and generates the 1st IF signal of 58.05MHz.The first if signal is further eliminated by a
two-stage single-crystal filter (F500).
5.3.3 Intermediate Frequency Amplifier (IF AMP)
First intermediate frequency amplified through Q503, then go into chip U500(FM process chip) 。Signal will mix
with second local referenced signal and generates a 450KHz second IF signal, which will go through a 450KHz filter
to filter out unwanted spurious signal before it is amplified and and discriminated.
5.3.4 AF Amplifier
In the U500, the audio signal demodulated by frequency discrimination is de-emphasised by IC501(A,B) high-pass
filter and then IC501(C, D) low-pass filter. The processed AF signal passes through an AF volume control and is
amplified to a sufficient level to drive a loud speaker by an AF power amplifier (U306).
5.3.5 Noise Suppression Circuit
Part of the audio signal from 13 pin of U500 will go through U500 again, use filter and amplifier to amplify noise
and then Rectify to generates a DCV with corresponding noise level. The DCV go through A/D port of micro
processor. U300 will detect the input voltage value to see if whether it exceed or lower than the preset value, then
decide the output voice through speaker.
To output voice through speaker, micro processor(U300) will send a high level signal to AF_MODE control line:
open Q302 through Q303 to supply power, open the Audio Power Amplifier (U306).

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SP
IF AMP AK2365A DET
DET
LPF
FM IF IC U500 IC501
LPFHPF Q311
SW
TDA2822
U306
Q302
Power SW
W/N SW
U301
TLV320AIC3204
QT /DQT
U300
CPU
BUSY
FM_MUTE
AF_MODE
TI
Chart 3 AF Amplifier and Squelch
W/N
De_emphasis
U302
SCT3258
5.4 Phase Locked Frequency Synthesize
The PLL circuit generates the first vibration signal for reception and the RF carrier signal for transmission.
5.4.1 PLL Circuit
Step frequency of PLL is 5 or 6.25KHz.The 19.2MHz reference oscillator signal is divided in a phase-locked loop
(U601) by a hybrid counter and generates a reference frequency of 5 or 6.25KHz. The voltage controlled oscillator
(VCO) outputs signal is buffer amplified by Q605 then divided in PLL(U601) by a dual-module programmable
counter .The divided signal is compared in (U601) with a phase comparator with a 5 or 6.25 KHz reference signal.
The ouput signal from the phase comparator is filtered through a low-pass filter and passed to the VCO to control the
oscillation frequency. (See Fig.4)
5.4.1 Voltage-Controlled Oscillator(VCO)
19.2MHz
PLL DATA
REF OSC
I/M
I/N
U601 PLL LMX2571
5KHz/6.25KHz
PHASE
COMPARATOR
CHARGE
PUMP
LPF
Chart 4 PLL Circuit
T X /R X
SW
HS C277
D509, D2
RF-OUT
Q601 generate operation frequency during transmitting mode, Q602 generate operation frequency during receiving
mode. From phase comparator to Varactor Diodes(D603 and D609 in transmitting mode,D606 and D607 in receiving

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mode), adopt voltage-controlled oscillator to control oscillation frequency. In receiving mode, Q607 conduct to
provide Q601 power supply. In transmitting mode, Q607 cut off Q611 to conduct and provide Q602 power supply.
(Q607 cut off or conduct is determined by output high/low level of micro processor. Micro processor(U300 and 56th
pin) output high level in receiving mode, output low level in transmitting mode)output of Q601 and Q602 will be
amplified by Q605 and sent to buffer amplifier.
5.4.2 Unlocked Detector
Lose lock if there is low level on LLP(10th pin of U601). Then get DC voltage from R634, if the low level detected by
micro processor(53rd pin of U300), transmitting will be unable regardless of communication switch.
5.5 Transmitter
5.5.1 RF Audio
FM signal from microphone will be amplified when through U307(A), and will be processed by IDC pre-emphasised
circuit when through another U301 and amplified. Then part(higher than 3KHz) of the signal will be filtered out when
going through inner low-pass filter of U301. Then start FM after going trough amplifier and VCO. Audio deviation
is controlled by the inner output electric level of audio filer U301. Check Chart 6 followed
5.5.2 QT/DQT/4FSK Coding
Required signal for MOD/QT/DQT/4FSK coding is produced by U301 and U300, which is being adjusted according
to reference frequency of PLL all the way. Since reference oscillator cannot adjust any frequencies out of loop
frequency, FM will be at another side of VCO in another path. Check Charter 6 followed.
5.5.3 Wide/Narrow Band Switch
We can use programming software to enable wide/narrow band to set that of various channels. Wide/narrow band data
will be realized by inner output of U300. Check Charter 6 followed.
MIC
Q323
SW
MIC_MUTE
U300
DCTC
AMP
MIC
U307
PREEMPHASIS IDC
U301
(SPLAT TER FILTER)
LPF
U301
BUFFER D601,Q602
VCO
X600
REFERENCE
OS C 19.2M
(TCXO)
Chart 6 Transmit Audio QT /DQT/DTMF
LPF
R350,R349,C378.C385
DT MF
CT C-TCXO
CPU
U301

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5.5.4 Voltage-Controlled Oscillator(VCO) and RF Amplifier
Signal comes from VCO buffer amplifier(Q605) will be amplified when through Q606, Q8, and Q10. This
amplified signal go through amplifier and Q3(RF MOSFET DOLULE), the RF power will be 5W if you set radio
as high power, will be 1.5w if your set radio as low power. Check chart 7.
ANT
Q8,Q10
AMP
Q4
RD01MUS2
Q3
PA AMP
D1 D3
ANT SW
LPF
ANT SW
D501 D502
RX
T5V
AP C
FC
+7.5V
TH1
Temperature
Q9 Chart 7 Auto Power Control
AMP
RD07MUS2B
U8 NJM2904V
5T
5.5.5 Antenna transfer switch and LPF
Before RF signal reach antenna terminal, RF amplifier output signal , harmonic will be filtered when it going
through low-pass filter then this signal go through transmit/receive switch circuit(made of D1 and D3). D1 and D3
keep open(conductive) in transmitting mode, keep closed(isolation) in receiving mode.
5.5.6 Power Control
Power control circuit can stabilize the transmission output power through detecting drain current of final
amplifier field-effect tube. Voltage comparing circuit, U8 use the reference voltage configured by microprocessor
to compare with the voltage obtained from the last current. The different value of power control voltage and
U8output automatic detection voltage and reference voltage is in direct proportion. The output voltage can
control the power amplifier of field-effect tube, and maintain the constant of output power of transmission part.
The output power of transmission part can be changed by microprocessor, and the reference voltage can be
changed by microprocessor to control output power.
5.5.7 Temperature Protection Circuit
When the thermistor(TH1)reaches about 80℃, the protection circuit turns on to protect transmitting final amplifier(Q3)
from the overheating.

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5.6 Power Supply
J404 input +7.5V to U313 LM2734X to born +3.3V voltage to power U300 micro processor. J404 input+7.5V to
U308 XC6204B502MR +5.0V(5C) voltage to power VCO and PLL circuit 从J404. J404 input +7.5V to U314
XC6204B502MR +5.0V(5R)voltage to power receiving circuit and audio circuit. J404 input +7.5V to U315
XC6204B502MR +5.0V(5T)voltage to power transmitting control circuit.
U314
XC6 204 B5 02M R
5V 5R
RX_ CT L
DC-SW
U313
L M27 3 4X MK
Vcc 7 .5 V
DC-DC
U309
U310
XC6 219 B3 32
XC6 219 B3 32
5V A3V3
REG
REG
RF3V3
U309
U310
XC6 219 B1 22
XC6 219 B3 32
DSP3 V3
REG
REG
D1V2
U315
XC6 204 B5 02M R
5V 5T
T X_ CT L
DC-SW
U308
XC6 204 B5 02M R
5V DC5 V
DC-SW
Chart 8 DC-SW

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5.7 CPU Control System
U300 micro processor clock running on 12.228MHz.
Low voltage warning of battery：
The battery voltage is monitored by U300 microprocessor. When it is below the low voltage of warning, the warning
tone will alarm.
On standby status:
When battery voltage is lower than preset warning value, system enter into low voltage warning status, radio
will give a “Beep” sound at preset intervals
On transmitting status:
When battery voltage is lower than preset warning value, press PTT key, the indicator LED will keep showing
flash red, radio is on transmitting status; When you release PTT key, radio will give a “Beep” sound at preset
intervals.
When battery voltage is lower than preset warning value but still withing the required transmitting voltage, red
long bright, you can press PTT key to transmit, radio will give a “Beep” sound at preset intervals.
If voltage lower than required transmitting voltage, when release PTT key, radio will give a “Beep” sound at
preset intervals. When you press PTT key again, red keeping flashing, radio will give a “Beep” sound and stop
transmitting; The transmitting will recover again till voltage higher than required transmitting voltage, red flash
and “Beep” sound will disappear.
When battery voltage lower than standard, red keep flashing, if you press PTT key, radio will give “Beep”
sound at preset intervals.
Radio will power off when battery voltage lower than power voltage. You need to charge the battery till higher
than power voltage to power on again.
When battery voltage higher than high voltage protection circuit, transmitting will be stopped, radio will give
“Beep” sound. Radio can only be allow to transmit till voltage turn normal.
RESET
E E P R O M
1 2 .2 8 8MH z
X 3 0 0
X OU T
X IN
S D A
S C L
W P
2 4 C 51 2
U 3 1 8
S -8 0 1 2 2A N MC
U 3 1 7
RESET
S T M3 2 F1 0 3 V B T 6
U 3 0 0
P T T
MO N I
P T T
MO N I
1
2

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Charter 6 Functions and Configurations
6.1 Function Definition and Parameter Configuration
6.1.1 Channel
This machine can store up 32 channels in 2 areas. 16 channels in each area.
6.1.2 Scan
Press preset scan key to active scan function, radio indicator LED will flash yellow. Once signal detected in any of
the channels, indicator LED will long bright green, speaker will open. There will be a delay after channel disappear,
then go to scan next channel.
Press preset scan key to quit scan status.
Two Scan Ways
Main channel scan(manually): radio will scan all channels/groups in your preset scan list. When enter scan mode,
according to different settings, your radio can start scan from the last scanned active channel/group or start scan
from current channel.
Auto scan(automatically): After you choose an active preset scan channel/group, radio will start scan automatically.
Start and Stop Scan
Steps:
Press pre-programmed scan key. Or switch the channel knob to select a scan channel(pre-programmed).
After scan function activated, indicator LED will flash yellow, you will hear a prompt “Di” tone. After scan stopped,
indicator LED no stop bright, you will hear a prompt “Di Di” tone.
During scan, response to scan
When your radio scan detect stop at an active channel/group, radio will keep staying at this channel, which is called
pre-programmed time limit of free time.
Steps:
1Hold radio and place it 1 to 2 inch away from your month at vertical position. If you turn on “Channel Free”
function, you will hear a short sound after the caller released PTT key, which means this channel is unoccupied and
wait for your speaking.
Within the free time, press PTT key, indicator LCD will bright red.
Wait till the “call tone” is finished(if you turned on “call tone” during programming), then start to speak.
Release PTT key to listen.
If you don’t have any response during free time, radio will leave and scan other channels.
6.1.3 Power/Battery Save
You can turn this function via customer programming software.
If there is no any operation or call 8 seconds after power on, your radio will active power/battery save mode.
Select Open: Turn on power/battery save mode
Select Close: Turn of power/battery save mode

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Default: Turn on
6.1.4 VOX
With voice instead of pressing the PTT key, use voice to control transmission by microphone.
6.1.5 TOT
To forbid long time channel occupation and to protect radio from being operated for long time transmitting.
6.1.6 High/Low Power Switch
Select High or Low power by programming.
6.1.7 Squelch Level
Squelch level from 0-9 can be chosen, level 1 is the shallowest which is easy to receive weak signal, level 9 is the
deepest which can receive stronger signal, and whose background noise is relatively less, interval of each grade is
about 1dbm, level 0 is out of control with squelch hysteresis.
6.1.8 Receive and Make Call
Select Area
Area is a channel group. This radio support 2 areas, there are max. 16 channels in each area
Steps:
Press pre-programmed area key.
You will hear a prompt “Di” tone, which means your radio has switched from area 1 to area 2; you will hear a
prompt “Di Di”tone, which means your radio has switched from area 2 to area 1.
6.1.9 Radio Channel, Radio ID and Group ID
Steps:
After the desired zone is set (if there are more than one zone),switch channel knob to choose channel, radio ID and
group ID.
Receive and Reply Call
Steps:
In channel,after you set the radio ID and group ID , you can receive call or call back.
Indicator LED bright red when radio is transmitting, bright green when radio is receiving signal.
Receive and Reply Group Call
Your radio must be set to belong to the group if you want to receive the group call.
Indicator LED bright green.
Hold radio and place it 1 to 2 inch away from your month at vertical position. If you turned on “Channel Free”
function when programming, after the caller released PTT key, you will hear a short prompt tone, which means
this channel is free for you to call back.
Press PTT key to speak. Indicator LED bright red.