HYT TC-700 Ex PLUS User manual

Contents
General．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．1
FM-Approved Intrinsically Safe Radio Information．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．3
Radio Overview．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．4
Software Specifications．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．8
Circuit Description．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．15
CPU Pins．．．．．．．．
．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．21
TC-700 EX PLUS VHF Parts List 1 ．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．
．．．．．25
TC-700 EX PLUS UHF Parts List 1 ．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．43
Adjustment Description．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．61
Troubleshooting Flow Chart．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．69
Disassembly and Assembly for Repair．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．73
Exploded View．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．76
TC-700 EX PLUS Parts List 2 ．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．77
Packing．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．79
Exploded View (FM-approved Battery)．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．80
Parts List (FM-approved Battery)．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．81
TC-700 EX PLUS VHF PCB View．．．．．．．．．．．．．．．
．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．
TC-700 EX PLUS UHF PCB View．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．
TC-700 EX PLUS Level Diagram．．．．．．．．．．．．．．．．
．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．
TC-700 EX PLUS Block Diagram．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．
TC-700 EX PLUS VHF Schematic Diagram (CPU Unit)．．．．．．．．．．．．．．．．．．．．
TC-700 EX PLUS UHF Schematic Diagram (CPU Unit)．．．．．．．．．．．．．．．．．．．．
Specifications．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．

TC-700 EX PLUS Service Manual
1
General
Manual Scope
This manual is intended for use by experienced technicians familiar with similar types of communication
equipment. It contains all service information required for the equipment and is current as of the
publication date.
Safety and General Information
Any person using the radio must observe the standard safety regulations and read the certificate to
prevent incorrect operation or abuse of the radio.
The following additional safety regulations must also be observed:
- Unauthorized modification of the radio may result in termination of Ex-protection.
- Unauthorized service or repairs are inhibited.
- Do not disassemble the FM-approved intrinsically safe products.
- The radio must not be opened in a hazardous area.
- The battery must only be changed in a non-hazardous area.
- Additional or spare batteries must not be carried into a hazardous area.
- Use only the Ex-battery BL1703-Ex（FM）specified by HYT. The use of other batteries is strictly
prohibited and will result in termination of Ex-protection.
- The battery must only be charged in a non-hazardous area with the designated charger
CH10L11-Ex.
- Use only HYT approved accessories: SM08M1-EX, ESM01-EX.
- Ensure that the radio is not taken into Zone 0 areas.
- To avoid electromagnetic interference and/or compatibility conflicts, turn off your radio in any
facility where posted notices instruct you to do so. Hospital or health facilities may be using
equipment that is sensitive to external RF energy.
- When instructed to do so, turn off your radio when on board an aircraft. Any use of a radio
must be in accordance with airline regulations or crew instructions.
- To avoid possible interference with blasting operations, turn off your radio when you are near
electrical blasting caps, in a blasting area, or in areas posted: “Turn off two-way radio.” Obey
all signs and instructions.

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- For vehicles with an air bag, do not place a radio in the area over an air bag or in the air bag
deployment area.
- Do not use any portable radio that has a damaged antenna. If a damaged antenna comes into
contact with your skin, a minor burn can result.
- Do not expose the radio to direct sunlight over a long time, nor place it close to heating
source.
WARNING: Failure to use an FM-approved product unit with an FM-approved battery or
FM-approved accessories specifically approved for that product may result in the
dangerously unsafe condition of an unapproved radio combination being used in a
hazardous location.

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FM-Approved Intrinsically Safe Radio Information
FM-Approved Intrinsically Safe Radio
Certification
FM-approved Intrinsically Safe
TC-700EX PLUS a Portable Radios
I.S. Class I, II, III, Division 1, Groups CDEFG, T3C
a=Radio Band Model Frequency Band
V: 136-174MHz
U(1):400-450MHz
U(2):440-490MHz
U(3):420-470MHz
U(4):470-520MHz
U(5):350-400MHz
U(6):300-350MHz
U(7):400-470MHz
U(8):450-520MHz

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Radio Overview
1. PTT (Push-to-Talk) Key
Press and hold down the PTT key to transmit; release it to receive.
2. SK1 (Side Key 1) (programmable)
3. SK2 (Side Key 2) (programmable)
4. Antenna
5. Microphone
6. Speaker
7. TK (Top Key) (programmable)
8. Channel Selector Knob
Rotate the knob to select from channel 1 to 16.
9. Radio On-Off/Volume Control Knob
Rotate the knob clockwise to turn the radio on; rotate the knob fully counter-clockwise until a “click” is
heard to turn the radio off.
Turn the knob clockwise to increase the volume, or counter-clockwise to decrease the volume.
10. LED Indicator
The table below explains functions of the LEDs and beeps.
11. Accessory Jack
12. Battery Latch

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5
13. Belt Clip
14. Accessory Cover
15. Battery
16. Screw
17. Electrode Piece
Source radio: Turn the source radio on while
holding down the PTT and SK2.
Target radio: Rotate the On-Off/Volume Control
knob clockwise to turn the target radio on.
The orange LED flashes
twice.
Source radio (power on the target radio and
connect the cloning cable, and then press the
PTT of the source radio to initiate cloning.)
1) LED solidly glows red
when cloning is in
progress;
2) LED goes out when
cloning is completed;
3) LED flashes red when
cloning fails.
Wired Cloning
Target radio 1) LED solidly glows
green when cloning is
in progress;
2) LED goes out when
cloning is completed.
Turn on both the source radio and target radio
while holding down the PTT and SK1. Both
radios are required to be on the same channel
for cloning.
The orange LED flashes
once.
Wireless cloning
Source radio (turn on both the source radio and
target radio while holding down the PTT and
SK1, and then press the PTT of the source
radio while both radios are on the same channel
to initiate cloning.)
LED solidly glows red when
cloning is in progress.

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Target radio 1) LED solidly glows green
when cloning is in
progress;
2) LED flashes green and
radio sounds beep tone,
when cloning is
completed;
3) LED flashes red when
cloning fails.
Power On The green LED flashes once.
Low Battery Alert LED flashes red, and radio
sounds three beeps every 30
seconds.
Transmitting LED glows red
Receiving LED glows green when
carrier is present.
Scanning Green LED flashes once
every 1 second.
Programming Reading: LED glows red;
Writing: LED glows green.
Encoding (DTMF/PTT ID/2-Tone (5-Tone)/HDC1200/HDC2400TM) 1) LED glows red while
transmitting;
2) LED glows orange when
transmission ends.
Decoding (2-Tone (5-Tone)/HDC1200//HDC2400TM) Orange LED flashes after the
signalling is successfully
decoded.
Select Power Level 0.5W: One beep is heard;
1.5W: Two beeps are heard;
3W: Three beeps are heard.

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Function Key Press One beep to enable, two
beeps to disable.

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8
Software Specifications
Specifications
Conventional Mode
1. Channel Selector Knob (16 channels)
VHF: 136-174 MHz
UHF: 420-470 MHz, 400-450MHz, 440-490MHz, 470-520MHz, 300-350MHz, 300-350MHz,
400-470MHz, 450-520MHz
2. Channel Spacing: 25/20/12.5KHz (programmable)
3. Step: 2.5/5/6.25KHz
4. LED Indicator: Red/Green/Orange
5. 3 Programmable Function Keys
6. CTCSS/CDCSS Encode & Decode
7. DTMF Encode
8. 2-Tone (5-Tone) Encode & Decode
9. HDC2400TM Encode & Decode
10. HDC1200 Encode & Decode
11. Squelch Mode:
1) Carrier
2) CTCSS/CDCSS
3) Optional Signalling
4) CTCSS/CDCSS AND 2-Tone (5-Tone)/ HDC2400TM/HDC1200
5) CTCSS/CDCSS OR 2-Tone / HDC2400TM/HDC1200
12. Scan
13. Time-Out-Timer (TOT)
14. Rent
15. Battery Save
16. Emergency
17. PTT ID
18. Busy Channel Lockout (Tx Admit Criteria)

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Description
1. User Mode
This mode is for normal operation.
2. All Reset Mode
First ground the SELF point, and then turn the radio on while holding down the TK key for 2 seconds.
The radio enters all reset mode with green LED flashing twice. Turn the Channel Selector knob to
the desired channel and press PTT. The radio data is all reset (All clone modes will be automatically
activated when All Reset is completed). Frequency settings are shown as follows:
Selected Channel Frequency Band(MHz) F1 (MHz) F2 (MHz) F3 (MHz) F4 (MHz) F5 (MHz)
1 136 - 174 (V)
TX1:136
RX1:136.1
TX2:145.5
RX2:145.6
TX3:155
RX3:155.1
TX4:164.5
RX4:164.6
TX5:174
RX5:173.9
2 400 - 450 (U1)
TX1:400
RX1:400.1
TX2:412.5
RX2:412.6
TX3:425
RX3:425.1
TX4: 437.5
RX4:437.6
TX5:450
RX5:449.9
3 440 - 490 (U2)
TX1:440
RX1:440.1
TX2:452.5
RX2:452.6
TX3:465
RX3:465.1
TX4:477.5
RX4:477.6
TX5:490
RX5:489.9
4 420 - 470 (U3)
TX1:420
RX1:420.1
TX2:432.5
RX2:432.6
TX3:445
RX3:445.1
TX4:457.5
RX4:457.6
TX5:470
RX5:469.9
5 470 - 520 (U4)
TX1:470
RX1:470.1
TX2:482.5
RX2:482.6
TX3:495
RX3:495.1
TX4:507.5
RX4:507.6
TX5:520
RX5:519.9
6 300 - 350 (U6)
TX1:300
RX1:300.1
TX2:312.5
RX2:312.6
TX3:325
RX3:325.1
TX4:337.5
RX4:337.6
TX5:350
RX5:349.9
7 350 - 390 (U5)
TX1:350
RX1:350.1
TX2:360
RX2:360.1
TX3:370
RX3:370.1
TX4:380
RX4:380.1
TX5:390
RX5:389.9
8 450-520 (U8)
TX1:450
RX1:450.1
TX2:467.5
RX2:467.6
TX3:485
RX3:485.1
TX4:502.5
RX4:502.6
TX5:520
RX5:519.9
9 400-470 (U7)
TX1:400
RX1:400.1
TX2:417.5
RX2:417.6
TX3:435
RX3:435.1
TX4:452.5
RX4:452.6
TX5:470
RX5:469.9
Channel data is shown as follows:

TC-700 EX PLUS Service Manual
10
Channel Rx Frequency
(MHZ)
Tx Frequency
(MHZ) Signalling Power Channel Spacing
1 RX1 TX1 None H 25KHZ
2 RX3 TX3 None H 25KHZ
3 RX5 TX5 None H 25KHZ
4 RX1 RX1 None LO 20KHZ
5 RX3 RX3 None LO 20KHZ
6 RX5 RX5 None LO 20KHZ
7 RX1 RX1 None LO 12.5KHZ
8 RX3 RX3 None LO 12.5KHZ
9 RX5 RX5 None LO 12.5KHZ
10 RX3 RX3 67HZ LO 25KHZ
11 RX3 RX3 254.1HZ LO 25KHZ
12 RX3 RX3 023 LO 25KHZ
13 RX3 RX3 754 LO 25KHZ
14 RX3 RX3 2-TONE LO 25KHZ
15 RX3 RX3 5-TONE LO 25KHZ
16 RX3 RX3 None LO 25KHZ

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3. Wireless Cloning Mode
Select Wireless Cloning from optional functions in programming software, and turn the radio on while
holding down PTT and SK1 keys simultaneously for 2 seconds. Then the source and target radios enter
Wireless Cloning Mode with orange LED flashing once (when both radios are turned on and stay on the
same channel), hold down PTT on the source radio to begin cloning. During cloning, the source radio
emits red LED, while the target radio emits green LED. When cloning is finished, the target radio flashes
green and sounds Beep tone, and the LED of the source radio is off. If cloning fails, the target radio
flashes red.
4. Wired Cloning Mode
Select Wired Cloning from optional functions in programming software, and turn the radio on while
holding down PTT and SK2 keys simultaneously for 2 seconds. Then the source radio enters Wired
Cloning Mode with orange LED flashing twice. Then simply turn the target radio on. Hold down PTT on
the source radio to begin cloning. During cloning, the source radio emits red LED and the target radio
emits green LED. When cloning is finished, the LEDs of both radios are off. If cloning fails, the source
radio flashes red.
5. Manual Adjust Mode
Manual adjustment is performed to adjust frequency deviation, power, sensitivity, squelch, etc.
Note: Prior to entering this mode, select the Manual Adjust Mode from optional functions in
programming software.
The manual adjustment operations are detailed as follows:
(1) Enter Manual Adjust Mode
Turn the radio on while holding down TK and SK2 keys simultaneously for 2 seconds, and then the radio
enters Manual Adjust Mode with red LED flashing twice.
(2) Channel Number on the Channel Selector Knob
Adjust the settings on the selected channel. Channel spacing of 25KHz and low frequency F1 are
selected for each channel change.
(3) SK2 Key
Set frequency. 1 point tuning adjusts center frequency; 3 point tuning adjusts F1, F3, F5; 5 point tuning
adjusts F1-F5.

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12
The frequency toggles at a low to high cycle. Green LED flashes once when adjusting F1.
(4) TK Key
Used to toggle the channel spacing among 25 KHz, 20 KHz and 12.5 KHz. Red LED flashes once when
the 25 KHz spacing is selected.
(5) PTT/SK1
PTT→Increase
SK1→Decrease
PTT/SK1 is pressed to increase or decrease the value of the adjusting item. Glowing red LED indicates
the maximum value and green LED indicates the minimum value. Hold down the key to increase or
decrease the value continuously.
Press the PTT key to save the BATT LOW, VOX and SQL settings, with green LED flashing once.
(6) Select Adjustment Group
The first group of adjusting items is selected once the radio enters the manual adjust mode.
Select CH16 and press the PTT key to enter the next group. Press it again to return to the first group.
Orange LED flashes once when the first group is selected and flashes twice when the second group is
selected.
(7) Frequency Setting
5 point tuning (MHz) TX: { TX1,TX2,TX3,TX4,TX5}
RX:{
RX1,RX2,RX3,RX4,RX5}
3 point tuning (MHz) TX: { TX1, TX3, TX5}
RX:{
RX1, RX3, RX5}
1 point tuning (MHz) TX: { TX3}
RX:{
RX3}

TC-700 EX PLUS Service Manual
13
First Group of Adjusting Items
Channel No. Adjusting Item Remarks
25KHz 20KHz 12.5KHz
1 Tx power LOW 5 point tuning
2 CDCSS PLL balance 3 point tuning (wide)
3 CDCSS deviation 3 point tuning (wide) 1 point tuning
1 point tuning
(narrow)
4
CTCSS deviation LOW (67Hz)
3 point tuning (wide) 1 point tuning
1 point tuning
(narrow)
5
CTCSS deviation CENTER
(136.5Hz)
3 point tuning (wide) 1 point tuning
1 point tuning
(narrow)
6 CTCSS deviation HIGH (254.1Hz) 3 point tuning (wide) 1 point tuning
1 point tuning
(narrow)
7 AK2346 audio deviation (TX) 3 point tuning (wide) 1 point tuning
3 point tuning
(narrow)
8 2-Tone deviation 1 point tuning (wide) 1 point tuning
1 point tuning
(narrow)
9 DTMF deviation 1 point tuning (wide) 1 point tuning
1 point tuning
(narrow)
10 MSK deviation 3 point tuning (wide) 1 point tuning
1 point tuning
(narrow)
11 TX power HIGH 5 point tuning
12 TX voltage LOW 1 point tuning

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14
6. PC Tuning Mode
Select tuning mode of programming items in the programming software and then tune as the setting.
Second Group of Adjusting Items
Channel No. Adjusting Item Remarks
25KHz 20KHz 12.5KHz
1 RX sensitivity 5 point tuning
2 AK2346 volume (RX) 1 point tuning (wide) 1 point tuning
1 point tuning
(narrow)
3 Squelch level 3 (OPEN) 5 point tuning (wide) 1 point tuning
3 point tuning
(narrow)
4 Squelch level 3 (SQUELCH) 5 point tuning (wide) 1 point tuning
3 point tuning
(narrow)
5 Squelch level 9 (OPEN) 5 point tuning (wide) 1 point tuning
3 point tuning
(narrow)
6 Squelch level 9 (SQUELCH) 5 point tuning (wide) 1 point tuning
3 point tuning
(narrow)
7 RX voltage LOW 1 point tuning

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Circuit Description
1. Power Supply
The radio is supplied by the battery. The power supply is from B+, and supplies power SWB+ for the
three AVRs, after passing through fuse FE250mA and switch. IC504 supplies 5V (M5V) voltage for the
control circuit. And IC503 supplies 5V (C5V) voltage for the shared circuit. IC502 supplies voltage for the
transmit/receive circuit. While transmitting, T5C becomes low level and Q502 is turned on to supply 5V
(T5V) voltage for the transmit circuit. While receiving, R5C becomes low level and Q504 is turned on to
supply 5V (R5V) voltage for the receive circuit. Power supply for RF is from B+ and works after passing
through fuse FE4 2A. Power supply for audio PA is from B+ and works after passing through fuse FE5
0.5A.
Fig. 1 Power Supply Block Diagram
2. PLL Frequency Synthesizer
PLL circuit generates the first local oscillator signal for receive and RF signal for transmit.
AVR
AVR
AVR
SW
FUSE
BATT
SW
T5C
T5V
SW
R5C
R5V
5CNS
C5V
M5V
SAVE

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16
Fig.2 PLL Block Diagram
1) PLL Circuit
Step frequency of PLL can be 2.5 KHz, 5.0 KHz or 6.25 KHz. A 16.8MHz reference oscillator signal is
divided at IC301 by a counter to generate a 2.5 KHz, 5.0 KHz or 6.25 KHz reference frequency. Output
signal from VCO is buffer amplified by Q301 and divided at IC301 by a frequency divider. The divided
signal is compared with 2.5 KHz, 5.0 KHz or 6.25 KHz reference signal in the phase comparator of IC301.
The output signal from phase comparator is filtered through a low pass filter to generate a level D.C., and
the level D.C. controls oscillator frequency by controlling VCO.
2) VCO
The operating frequency is generated by Q302 in transmit mode and by Q307 in receive mode.
Operating frequency generate a control voltage by phase comparator to control varactor so that the
oscillator frequency is consistent with the MCU preset frequency (D301、D302、D303 and D304 in
transmit mode, and D307、D308、D309 and D310 in receive mode). T/R pin is set high level in receive
mode, and low level in transmit mode. The output from Q302 and Q307 is amplified by Q304 and sent to
buffer amplifier.
3) Unlock Detector
An unlock condition appears if low level occurs at MUXOUT pin of IC301. Transmission is inhibited if this
condition is detected by microprocessor.
3. Receiver
The receiver utilizes double conversion superheterodyne (UHF)/(VHF).
VCO
MCU
PLL
SW
D201
BUFF
Q301
SW
D101
BUFF
Q111
CLK,DAT,STB
T/R
CV
To Drive Amp
To Mixer
VCXO
X301
CTC
UL
1st Local OSC

TC-700 EX PLUS Service Manual
17
Fig. 3 Receiver Section Configuration
1) Front-end RF Amplifier
The signal from antenna is amplified at RF amplifier (Q207) after passing through a
transmit/receive circuit and a band pass filter. Before passing the first mixer, the amplified
signal is filtered through another band pass filter to remove unwanted signals.
2) First Mixer
The signal from RF amplifier is mixed with the first local from PLL frequency synthesizer circuit at the fix
mixer (IC202) to create a 49.95MHz first IF signal. The first IF signal is then fed through a crystal filter
(XF203) to further remove unwanted signals.
3) IF Amplifier
The first IF signal is amplified by Q206 before passing through crystal filter and by Q204 after crystal
filter and then enters IF processing chip IC204. The signal from IC204 is mixed with the second oscillator
signal again in IC204 to create a 450 KHz second IF signal. The second IF signal then passes through a
450KHz ceramic filter (wide: CF201，narrow: CF202) to eliminate unwanted signals before it is amplified
and detected in IC204.
4) Narrow/Wide Switch Circuit
Pin WCON and pin NCON of IC500 outputs wide (high level) and narrow (low level) channel spacing
signal respectively to turn on corresponding diode-connector, and to choose ceramic filter CF201 (wide)
or CF202 (narrow) to filter useless spurious signal.
5) Audio Amplifier
The resulting audio signal from IC204 enters baseband processing chip IC408. The processed audio
signal is then amplified by an audio power amplifier (IC401) to drive the speaker.
ANTSW
BPF RF AMP
Q207 BPF
1st Local OSC
(PLL)
IF AMP
Q206
MCF
XF203
IF AMP
Q204
IF,MIX,DET
IC204
CF201,202
AF AMP
IC401 SP
Audio
Processor
IC408
VCXO
X3
multiply 16.8MHz
APC
ANT
2nd Local OSC

TC-700 EX PLUS Service Manual
18
4. Transmitter
1) Audio and Signalling
Audio signal from the microphone is amplified and low-pass-filtered in IC402 before it enters baseband
processing chip IC408, which also enters CTCSS/CDCSS/DTMF/2-Tone (5-Tone) signalling generated
by CPU. The IC408 processed mixing signal enters VCO for direct FM modulation (see fig.5).
2) RF Power Amplifier
The transmit signal from VCO buffer amplifier (Q111) is amplified by Q101 and Q102. The amplified
signal is then amplified by the power amplifier Q103 and Q104 (including a two-stage FET amplifier) to
create 4.0W (UHF)/5.0W (VHF) RF power (see Fig. 6).
Fig. 4 APC System
3) Antenna Switch and LPF
Output signal from RF amplifier passes through a low-pass filter network and a transmit/receive switch
circuit comprised of D102, D103 and D104 before it reaches the antenna terminal. D103 and D104 is
turned on (conductive) in transmit mode and off (isolated) in receive mode.
4) APC
The automatic power control (APC) circuit stabilizes the transmit power by detecting the drain current of
final stage amplifier FET. IC101 (2/2) compares the preset reference voltage with the voltage obtained
AMP
Q101、102
DRIVE AMP
Q103
FINAL AMP
Q104
Q110
SW
IC101
APC
Q110
SW
ANT SW
D102
ANT SW
D103、D104
ANT
RX
DET
SWB+
APC
SW
Q109
SW
DC
SW
Q107
SW
APC
T5C
Q105
SW
SWB+

TC-700 EX PLUS Service Manual
19
from final current. APC voltage is in proportion to the difference between auto detect voltage and
reference voltage output from IC101 (1/2). The output voltage controls FET power.
5. Baseband and Signalling System
The block diagram of signalling section is shown as figure 5.
Fig. 5 Audio and Signalling Circuit
1) CTCSS/CDCSS
Transmit: CTCSS/CDCSS signalling produced by CTCSS_PLL pass a low pass filter and then
enters VCXO. CTCSS/CDCSS signalling produced by CTCSS_OUT pass a low pass
filter and then mixed with audio before enters VCO.
Receive: Demodulated signal enters MCU after pass IC404、IC405. MCU then judges whether
CTCSS/CDCSS matches the preset values or not. According the result, the out tone
will be controlled by AFMUTE.
2) 2-Tone (5-Tone) and DTMF
Transmit: The signal produced by MCU provides a Tx and SP output tone, and is then applied to
the baseband processor. The signal in mixed with the audio signal and goes to the
VCO.
Receive: Demodulated signal is filtered after passing baseband processor, and then enters
MCU for decoding.
3) MSK
Transmit: MSK signal produced by baseband processor enters VCO together with audio signal
AF DET
IC404
AMP LPF
IC405
LPF
CTCSS/CDCSS
TI
RXIN/RXINO
IC401
AMP
SP
AFCO
AFMUTE
MIC
Q401
SW
IC402
AMP LPF
D402
RB706F-40
VOX
MIC MUTE
5CNS
PTT
TONEO
Q406
Q407
SW
Q403
SW
Q404
SW
ALM/BP
AUDIO PROCESSOR
IC408
AK2346
VR1
Scrambler
DeScrambler
VR3
RXLPF
Pre-
Emphasis
COM-
pressor
SMF VR4
Expand
Splatter
VR2
Limiter De-
Emphasis
MSK
Modulator
MSK
Demodulator
MOD
IC407
BPF
TONEI
AFCK
CODIO
AFRDF
AFDT
AFSK
AFDIR
1/2OSD
TONEO