HYT TC-320 User manual

TC-320

Contents
1. Introduction ........................................................................................................................................1
2. Product Controls................................................................................................................................2
3. Software Specifications.....................................................................................................................6
4. Circuit Description ...........................................................................................................................10
5. CPU Pins...........................................................................................................................................17
6. Parts List 1........................................................................................................................................21
7. Tuning Description...........................................................................................................................31
8. Troubleshooting Flow Chart............................................................................................................42
9. Disassembly and Assembly............................................................................................................45
10. Exploded View................................................................................................................................51
11. Parts List 2......................................................................................................................................52
12. Packing Guide ................................................................................................................................55
13. PCB View.........................................................................................................................................56
14. Level Diagram.................................................................................................................................58
15. Block Diagram ................................................................................................................................59
16. Schematic Diagram........................................................................................................................60
17. Specifications.................................................................................................................................63

Copyright Information
HYT is the trademark or registered trademark of Hytera Communications Co., Ltd. (the Company) in
PRC and/or other countries or areas. Hytera retains the ownership of its trademarks and product names.
All other trademarks and/or product names that may be used in this manual are properties of their
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The product describes in this manual may include the Company’s computer programs stored in memory
or other media. Laws in PRC and/or other countries or areas protect the exclusive rights of the
Company with respect to its computer programs. The purchase of this product shall not be deemed to
grant, either directly or by implication, any rights to the purchaser regarding the Company’s computer
programs. Any of the Company’s computer programs may not be copied, modified, distributed,
decompiled, or reverse-engineered in any manner without the prior written consent of the Company.
Disclaimer
The Company endeavors to achieve the accuracy and completeness of this manual, but no warranty of
accuracy or reliability is given. All the specifications and designs are subject to change without notice
due to continuous technology development. No part of this manual may be copied, modified, translated,
or distributed in any manner without the express written permission of us.
If you have any suggestions or would like to learn more details, please visit our website at:
http://www.hytera.com.

Service Manual Introduction
1
1. Introduction
Intended User
This manual is intended for use by qualified technicians only.

Product Controls Service Manual
2
2. Product Controls
(1) PTT Key (2) SK (programmable) (3) Speaker
(4) Volume Control
Key ([+]/[-])
(5) Microphone (6) Nameplate
(7) Charging
Terminal
(8) Antenna
(9) Power On/Off Key
(10) Channel/Status
Indicator
(11) Channel
Selector Knob
(12) Charge
Indicator
(13) Accessory Jack
Cover
(14) Accessory Jack (15) MINI USB Port (16) Strap Hole
(17) Screw for Belt Clip (18) Belt Clip (19) Battery Cover (20) Battery Latch

Service Manual Product Controls
3
﹡PTT (Push-to-Talk) Key
Hold the PTT key to transmit, and release it to receive.
﹡Programmable Function Key
The side key (SK) can be programmed with long/short press functions by your dealer. (Note: Short Press
means key press shorter than 1 second, while Long Press means key press longer than 1 second. ）
﹡Channel/Status Indicator
See the table below for LED and alert tone indications:
Item Indication
Wired Clone
To enter Wired Clone Mode
Hold down both SK and Power On/Off Key, and the
source radio is turned on with Status Indicator
flashing red once.
Turn on the target radio directly.
Status of the source radio
(After target radio is turned on
and cloning cable is
connected, press PTT of the
source radio to begin cloning.)
The Status Indicator glows red during cloning
process.
Error occurs during cloning:
zUser Clone: Once cloning begins, frequency band
and Model ID will be checked. The Status
Indicator glows orange for 2 seconds and then
goes out to indicate a failed check. If the check is
successfully carried out but error occurs during
cloning, the Status Indicator will keep flashing
orange until you press any key other than the
Power On/Off Key to cancel it.
zFactory Clone: If error data clone occurs, the
Status Indicator will flash orange. In this situation,
press any key other than the Power On/Off Key
to turn it off.
Once cloning is completed, the Status Indicator will
solidly glow green.
The Status Indicator flashes red when it indicates low
voltage, which will not be responded in the clone
mode.

Product Controls Service Manual
4
Item Indication
Status of the target radio in
Wired Clone Mode
zThe Status Indicator glows green during cloning.
zThe green Status Indicator goes out once cloning
is completed.
Power On (to enter User Mode)
When the radio is turned on, a power-on alert tone
sounds and the Status Indicator flashes orange once.
When the radio is currently on a blank channel, it will
sound beep tones continuously.
Powering off
When the radio is turned on, a power-off alert
tone will sound.
Low Battery Alert
The Status Indicator will flash red, and a low-pitched
tone will sound every 10 seconds.
Transmitting
The Status Indicator will glow red during transmitting.
zWhen the TOT timer expires, the radio will sound
beep tone continuously.
zA TOT pre-alert tone will sound before the TOT
timer expires.
Receiving
The Status Indicator will glow green when carrier is
present.
Scanning
zThe Status Indicator will flash green once per
second during scanning.
zScan Start Alert (programmable by the dealer):
One beep will sound.
zScan End Alert (programmable by the dealer):
One beep will sound.
Writing/Reading
zThe Status Indicator glows red when the PC is
reading data from the radio.

Service Manual Product Controls
5
Item Indication
zThe Status Indicator glows green when the PC
is writing data into the radio.
Power Adjustment
zA low-pitched tone will sound when the radio
switches from high power to low power.
zA high-pitched tone will sound when the radio
switches from low power to high power.
VOX
zThe alert tone sounds once when the VOX feature
is activated.
zThe alert tone sounds twice when the VOX feature
is disabled.
* Channel Selector Knob
Rotate the knob to select your desired channel.
﹡Power On/Off Key
Long press the Power On/Off Key until an alert tone is heard to turn the radio on/off.
* Volume Control Keys [+]/[-]
You may adjust the volume level through keys [+] / [-]. Press [+] to increase or [-] to decrease the volume
level. During adjustment, the radio will sound alert tones corresponding to the volume level.
* Battery Latch
Used to secure or remove the battery.
﹡Audio Accessory Jack
Used to connect audio accessories such as earpiece and microphone.
* Mini USB Jack
Used to connect accessories such as programming cable, cloning cable and power cord.

Software Specifications Service Manual
6
3. Software Specifications
Function List
zChannel Capacity: 16
zChannel Spacing:
25KHz/12.5KHz
zChannel Scan
zRx/Tx status indication (red/green LED)
zCTCSS/CDCSS Encode&Decode (38 groups of CTCSS, 83 groups of CDCSS, and CTCSS Tail
Revert of 180 degrees.)
zLow Battery Alert
zBattery Save
zUnlock Detection and Emergency Alarm
z2 Selectable Squelch Levels
zMonitor
zTime-out Timer (TOT)
zSquelch Tail Elimination
zPC Programming (manual / automatic adjustment)
zHigh/Low Power Switch (2.0/0.5.0W)
zWide & Narrow Bandwidth Compatible
zBusy Channel Lockout (transmission prohibited in busy status)
zWired Clone
zBattery Strength Indicator
zManual Adjustment
Description of Modes
3.1.1 User Mode
It is a conventional communication mode. The radio will enter this mode by default after power-on.
3.1.2 PC Programming Mode
The radio in User Mode enters PC Programming Mode through specific protocol based
communication with the programming software. In this mode, radio functions and tuning parameters can
be set through the programming software (including User Version and Factory Version).

Service Manual Software Specifications
7
Operations:
Step 1 Install PC programming software and its driver dedicated for TC-320 before your initial use.
Step 2 Connect the USB port of PC with the Mini USB port of the radio using a programming cable.
Step 3 Turn on the radio.
Step 4 Run the programming software to perform reading or writing operation.
Note:
¾When reading/writing is in progress, the Status Indicator glows red/green; when reading/writing
data is completed, the Status Indicator goes out.
¾During the operation, if any abnormal situation occurs or no reply is given within a certain period,
the reading/writing operation will fail and an error message window will pop up.
3.1.3 Wired Clone Mode
Description
Wired Clone mode is an independent mode. To access other modes, you must restart the radio.
Wired Clone Mode includes Clone Mode and Factory Clone Mode.
zClone Mode
Connect two radios using a clone cable. Hold both SK and Power On/Off Key of the source radio,
it will be turned on and will enter Clone Mode after 2 seconds. The target radio can be directly turned
on to enter user mode. In this mode, parameter data stored in EEPROM of the source radio will be
cloned to EEPROM of the target radio. The range of data transmitted only covers channel data and
common parameters, excluding tuning data, version and serial No. of the model.
zFactory Clone Mode
Connect two radios using a clone cable. Hold both SK and Power On/Off Key of the source radio,
it will be turned on and will enter Clone Mode by default after 2 seconds. Press SK afterwards to
switch to Factory Clone Mode. The target radio can be directly turned on to enter user mode. The
range of transmitted data covers all data (including settings for the Manual Tune Switch) stored in
EEPROM, with exclusion of the serial No.
Process
Process of Wired Clone:
Step 1 The Status Indicator flashes red once after the source radio enters Wired Clone mode. Press
PTT to clone data to the target radio.

Software Specifications Service Manual
8
Step 2 During communication, the Status Indicator of the source radio glows red, and the Status
Indicator of the target radio glows green. When the communication ends, green LED of the
source radio glows and the green LED of the target radio goes out, which indicates the
preparation for another clone.
Step 3 If any abnormal situation occurs during communication, the source radio will flash orange
Status Indicator and will stop communication for another cloning.
Step 4 When cloning ends, the source radio goes back to the standby status. Press PTT again to begin
another cloning operation.
3.1.4 Manual Tune Mode
Hold PTT, SK and Power On/Off Key to turn the radio on and enter Manual Tune Mode.
Note:
This operation is subject to the option Tune Switch in the programming software. If this switch is set
to Close, the radio can not enter this mode. It helps avoid any unexpected change of values and
degradation of radio performance.
Do keep this option unchecked after values are well adjusted from the factory, to avoid any unexpected
change of values. Such values can only be reset and changed in Manual Tune Mode only.
Description of Tuning:
To enter Manual Tune Mode
Hold PTT, SK and Power On/Off Key until the radio is turned on and the Status Indicator glows orange,
the radio will enter Manual Tune Mode. When the key is released, the radio will enter Item N of Tx group
(N depends on the position where the channel selector knob locates). The Status Indicator glows red for
TX tuning items and green for RX tuning items.
To switch between TX Tuning items and RX Tuning items
This operation is done through the channel selector knob.
zThe Status Indicator solidly glows red when you are adjusting items in Tx group.
zThe Status Indicator solidly glows green when you are adjusting items in Rx group.
About the TX/RX tuning items
This action is carried out by applying channel selector knob as follows:
zTX group: CH1-CH9 respectively stands for TX Low Power, TX High Power, CDCSS Balance,
CDCSS Deviation, CTCSS Deviation (low), CTCSS Deviation (medium), CTCSS Deviation (high),
TX Low Voltage Threshold and Max. TX Audio Deviation.

Service Manual Software Specifications
9
The Status Indicator solidly glows red during TX group tuning (CH1 to CH9).
zRX group: CH10-CH12 respectively stands for SQL On 5, SQL Off 5, and RX Low Voltage Threshold.
The Status Indicator solidly glows green when you are tuning items CH10-CH12.
On CH13-CH16, no tuning item can be found and the Status Indicator goes out.
To switch between wide and narrow bands
When tuning a certain item, short press SK (the Status Indicator flashes orange indicating valid press) to
switch between wide/narrow bandwidth. After this operation, the first frequency of current bandwidth is
the frequency for adjustment by default.
To switch the frequency
Short press PTT (the Status Indicator flashes green indicating valid press) to switch between
frequencies orderly under certain bandwidth and certain tuning item.
To tune the value
Short press [+] under certain bandwidth and certain tuning item, and the value will increase in steps of 1;
hold [+], and the value will keep increasing in steps of 1. The value will remain unchanged once it
reaches the allowed maximum value.
Short press [-] under certain bandwidth and certain tuning item, and the value will decrease in steps of 1;
hold [-], and the value will keep decreasing in steps of 1. The value will remain unchanged once it
reaches the allowed minimum value.
About several special items
zTX group: CH8 (TX Low Voltage Threshold) This item is related to AD sampling. Press [+] or [-] after
entering the above item, to activate AD sampling (including calculation) once. Rotate the Channel
Selector Knob to save the current AD sampling value. If neither [+] nor [-] is pressed, the value will
not be updated, and AD sampling will not be activated.
zRX group: CH10-CH12 respectively stands for SQL On 5, SQL Off 5, and RX Low Voltage Threshold.
These items are related to AD sampling. Press [+] or [-] after entering the above items, to activate AD
sampling (including calculation) once. Rotate the Channel Selector Knob to save the current AD
sampling value. If neither [+] nor [-] is pressed, the value will not be updated, and AD sampling will
not be activated.
About the Key-press
zShort press: key-press time shorter than 1 second;
zLong press: key-press time longer than 1 second.

Circuit Description Service Manual
10
4. Circuit Description
4.1 General Principle Diagram
The general circuit is composed of RDA chip circuit, TX circuit, RX circuit, power supply circuit, control
circuit, etc. See the block diagram below:
PWER
VOX_DET
MICIN
TX_EN
AF
RFOUT
Synthesizer
Figure 1
zRDA Chip Circuit
This chip is highly integrated. Its function includes voice signal
processing/modulation/demodulation, DSP, VCO, PLL, LNA and RF IF. The voice signal from MIC
goes to RDA chip for amplification. Next, the amplified voice signal will undergo a series of
processing including A/D conversion, filtering, pre-emphasizing, gain control, amplitude limit and D/A
conversion. Then the analog voice signal is delivered to VCO and amplified to a signal with 8dBm.
When the RX RF signal enters this chip, it would experience demodulation, filtering, de-emphasizing
and gain control. Finally, the signal is output to the audio amplifier.

Service Manual Circuit Description
11
zTX Circuit
The modulated RF signal from RDA chip goes to Q407 and Q402 for amplification, and then further
amplified by Q403. Then the amplified signal is delivered to low-pass filter to filter out the high-order
harmonics. Finally, it is sent via the antenna.
zRX Circuit
After going through LPF and amplitude limiter, the RF signal received from the antenna enters Q501
LNA for amplification. Then the BPF will filter the signal to remove other unwanted signals. The
resulting signal is delivered to RDA chip for demodulation. After that, the voice signal from
demodulation is output U301 for amplification, which is finally output from the speaker.
zPower Circuit
LDO U619 and DO U621 convert the 3.8V power supply into two 3.3V power supplies, powering
VCC and VDD respectively. VCC powers CPU, while VDD powers RDA chip. Then Q409 converts
the 3.3V power supply to VT to power the TX circuit.
4.2 Realization Methods of Basic Functional Modules
4.2.1 RDA Chip Circuit
This chip is highly integrated. Its function includes voice signal
processing/modulation/demodulation, DSP, VCO, PLL, LNA and RF IF.
RDA Chip Circuit
Figure 2

Circuit Description Service Manual
12
The reference clock signal of RDA chip is provided by 26MHZ crystal oscillator. The block diagram is
given below:
LDO
Syntheizer
LNA
Switch
RF_IN
-
-
0/90
+
+
I ADC
Q ADC
DSP Core
Audio filter
Sub CH filter
FM Modem
AFC loop
DAC
ADC
I PGA
Q PGA
PA
MCU
GPIO
GPIO0~7
Interfac
e
BUS
……PDN
SPI
I2C
RSSI
VCO
PA_driver
XTAL
MIC
DVDD
AVDD
3.3~
4.8V
After entering RDA chip via MIC, the voice signal will undergo A/D conversion to get digital
signal, which will be delivered to DSP for further processing such as filtering, amplification,
amplitude-limiting and pre-emphasizing. Then the resulting voice signal is modulated to the internal VCO
and output after being amplified by the driver amplifier. At the RX end, the received RF signal will go to
LNA for amplification first, and then go to IF demodulation circuit to get demodulated voice signal. After
gain control, such signal is converted into digital signal, which will enter DSP for further processing such
as filtering, amplification and de-emphasizing.
The function of RDA is subject to MCU U622 and its reference clock signal is from 26MHZ crystal
oscillator. This chip is applicable to UHF (400~520MHZ) and VHF (134~174MHZ). The NF can be up to
3dB and IIP3 up to -6dBm, meeting GB and FCC requirements. Its RF output may reach up to 8dBm.
4.2.2 RF Power Amplifier Circuit (TX Section)
The block diagram of the RF power amplifier circuit is shown in the figure below:

Service Manual Circuit Description
13
BIAS DOWN
APC
U401
APC
BAT
Figure 3
The modulated RF signal from RDA chip goes to Q407 and Q402 for amplification, and then further
amplified by Q403. Then the amplified signal is delivered to low-pass filter to filter out the high-order
harmonics. Finally, it is sent via the antenna. The control signal “VT” is used to control the operation of
driver amplifier (Q407 and Q402). U401 works for auto power control (APC).
4.2.3 Receiver Circuit (RX Section)
The Block Diagram of RX Circuit is shown as below:

Circuit Description Service Manual
14
LNA
Q501
AT41511
ANT LPF
RX_EN
BPF1
VT
D401 D402
Figure 4
The RF signal is received via the antenna. After going through LPF and amplitude limiter, the signal is
amplified by Q501 LNA.
Next, the BPF will remove the interference signal in amplified RF signal. Then the resulting signal goes
to RDA chip for further processing. The processed signal is delivered to U302 for amplification and finally
output by the speaker.
4.2.4 MCU Control, Signal Processing and Audio Amplification
Circuit diagram of this section is shown as below:

Service Manual Circuit Description
15
U622
MCU
MC9S08AC60
SDA/SCL
RESET
EN0/EN1/EN2/EN3
AF
VOX_DET
1
2
PTT/SK1/SK2
RXD
TXD
1
2
CSS/CODE/INT/SDO
/RXON/TXON/SQ/PDN
SDIO/SCLK/SEBN/PDN
EXT_PTT
/EXT_MIC
BAT
Figure5
MCU Control Circuit
MCU control circuit is composed of MCU, EEPROM, keys, etc. This section has the following functions:
to initialize data of the radio and save data to EEPROM; to detect battery voltage and signals from
external keys, LD and VOX, and to make response; to transmit required data to PLL based on the
channel encoding status; to switch and control RX/TX based on the input PTT signal; to switch the
squelch circuit on/off based on the input signaling decode signal and squelch level signal; to control
circuits of high/low power switch, audio power amplifier, RDA chip power supply, RX power supply and

Circuit Description Service Manual
16
TX power supply; (for programming) to communicate with PC via RXD/TXD based on the RS232
protocol, and transmit/receive data to/from PC.
RDA Chip Control
By controlling the RDA chip, the MCU can realize these services: frequency setting, frequency
bandwidth, reference clock, sleep mode, SQ, VOX, squelch, frequency deviation, voice filtering,
signaling encoding/decoding, pre-emphasizing, gain control, amplitude limiting, de-emphasizing, etc.
Audio Amplifier
The audio signal output from U622 is amplified by the audio power amplifier (U301) to drive the speaker
directly.
Power Supply Section
Block diagram of power supply circuit is shown as below:
VCC
VDD
VT
Figure 6
LDO U619 and LDO U621 convert the 3.8V power supply into two 3.3V power supplies, powering VCC
and VDD respectively. VCC powers CPU, while VDD powers RDA chip. Then Q409 converts the 3.3V
power supply to VT to power the TX circuit.

Service Manual CPU Pins
17
5. CPU Pins
PIN No. Pin Name Definition I/O Description
1 PTC4
POWER
ON/OFF
I Power Switch
2 IRQ/TPMCLK IRQ I
Connected to power switch for
reviving MCU in power-off mode
3 RESET RESET I Reset
4 PTF0/TPM1CH2 BEEP O Tone
5 PTF1/TPM1CH3 VRCR O PWM output for freq. adjustment
6 PTF2/TPM1CH4 APC O PWM output for PA APC
7 PTF3/TPM1CH5 CSS I Detection pin, CDCSS status output
8 PTF4/TPM2CH0 TXON I TX status detection pin
9 PTC6 PWER O Radio power control pin
10 PTF7 UP I Volume increase key
11 PTF5/TPM2CH1 RXON I RX status detection pin
12 PTF6 DOWN I Volume decrease key
13 PTE0/TxD1 UART_TXD O Port
14 PTE1/RxD1 UART_RXD I Port
15 PTE2/TPM1CH0 INT I Detection pin, programmable
16 PTE3/TPM1CH1 CODE I/O
Detection pin, modulated digital
signal input/output
17 PTE4/SS1 SEBN O SPI port of communication
18 PTE5/MISO1 SDO I SPI port of communication