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A720T (VHF) Service Manual V1.0

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ANT

F500

58.05MHz

CF300

450KHz

U500 IF

57.6MHz

U307

TDA2822

SP

X600

19.2MHz

Q 601

MIC

U306

NJM2904V

U601 Q 601 Q 602

PLL VCO

RX

TX

Chart 1 Analog Circuit Structure

AK2365A

Q 501

RF AMP

BAP65-03

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

TCXO 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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Summary of Contents for A720T

Page 1: ...A720T VHF Service Manual V1 0 1 56 A720T VHF Service Manual ABELL INDUSTRIES CO LTD ...

Page 2: ...ITAL 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 Q...

Page 3: ...IO 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 ELECTRO...

Page 4: ...p 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...

Page 5: ...s 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 2 PTT 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...

Page 6: ...ou 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 9 Speaker 10 Dust cover for earpieces and ...

Page 7: ...gramming 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 ABE...

Page 8: ...g 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 chan...

Page 9: ...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 P...

Page 10: ...A720T VHF Service Manual V1 0 10 56 4 2 Explosive View ...

Page 11: ... to be 4FSK digital audio signal then TDA2822 power amplifier will magnify and drive SP speaker BAP65 03 Q501 RF AMP ANT F500 58 05MHz CF300 450KHz IF SYSTEM U307 TDA2822 SP SCT3258 IP data port MIC U306 NJM2904 U601 PLL VCO RX TX Q4 TX AMP Q3 PA AMP DMR Circuit Structure U302 data vocie port AMBE 3000 Encoder Decoder AD DA switch Frame Encoding Frame Decoding Modulation Frame Header Vaild Date De...

Page 12: ...ss 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 frequen...

Page 13: ...plifier 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 thr...

Page 14: ...f 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 ...

Page 15: ...phasised 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 pr...

Page 16: ...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...

Page 17: ...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_ CTL DC SW U313 LM27 34XMK 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 TX_ CTL DC SW ...

Page 18: ...mit 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 dis...

Page 19: ... 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...

Page 20: ...a 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 aft...

Page 21: ... activities within preset time this calling is over You will hear a short tone Receive a ALL Call Definition of ALL Call one radio call all radio on the same channels Steps When you are receiving a ALL Call You ll hear a prompt tone indicator LED bright green If there is no voice activity within preset time the ALL Call is over If you turned on Channel Free function when programming after the call...

Page 22: ...on Press PTT key to make call speak indicator LED bright red Wait till the call tone is finished if you turned on call tone during programming then start to speak Radios on the same channel cannot answer your all call Make Group Call and Individual Call by Pre programmed Call Key You can pre program a function key with an ID to make group call or individual call You can pre program long press or s...

Page 23: ...key to switch between high and low power You will hear a prompt Di tone which means that radio is under low power status Radio is under high power status when you hear a prompt Di Di tone 6 2 3 VOX This function allows you to hands free call in pre programmed channels When you are wearing VOX earpieces radio can detect your voice and start to transmit your voice automatically You can quit VOX by p...

Page 24: ... Rx CDCSS pre programmed can only receive the signal which carries the same CDCSS code can receive any signal no CDCSS code programmed with the same TX and Rx frequency After TX CDCSS code pre programmed your radio will transmit pre programmed CDCSS code with your signal Tail Tone Elimination To avoid tail tone for receiver after carrier disappear in the channel Carrie will disappear after speaker...

Page 25: ...ed ampere meter 17 gears and other functions 2 Full scale can be set as 300mA or 3A 3 It must use low loss cable 3 Digital voltmeter 1 Voltage range approximate FS 18V 2 Input impedance 1MΩ or even bigger 4 Oscilloscope 1 Measuring range DC to 30MHZ 2 High accuracy measurement can be provided from 5 to 25MHz 5 Spectrum analyzer Measurement range DC to 1GHz or even bigger 6 Dummy load 16Ω 3W or eve...

Page 26: ... 500 CH 4 174 000 174 000 Chart 2 Adjustment QT List Frequency VHF 136 174 MHz Signaling number QT wide band QT narrow band 0 67 Hz 67 Hz 1 127 3Hz 114 8Hz 2 136 5 Hz 136 5 Hz 3 206 5Hz 206 5Hz 4 241 8Hz 241 8Hz Note Connect radio with PC Send channel data to radio and then back up the data Input the adjustment frequency program to radio Note After adjustment reform the loaded backup channel data ...

Page 27: ... adjustment optional enable PPT adjust data change frequency frequency difference wit hin 100Hz 3 high power adjustment debugging channel CH 1 low port CH 2 middle port CH 3 high port BATT port 7 5V power meter ampere meter antenna terminal A720T programming software high power high middle low frequency points adjustment Enter power adjustment enable PTT adjust data change power current after debu...

Page 28: ...e port adjustment narrow band frequency deviation 2 2KHz 0 2 KHz 1 transmit digital 4FSK bit error rate adjustment Test channels CH1 CH2 CH3 CH4 CH5 3920 measuring equipment Antenn a terminal JK101 JK102 Connect comput er A720T progra mming softwar e Digital send path I amplitude path Q adjustment this adjustment needs AEROFLEX3920 click digital adjustment item to adjust path Q digital frequency d...

Page 29: ... measuring equipment Antenn a terminal JK101 JK102 Connect comput er progra mming softwar e 3920 send 4FSK signal to radio then radio send demodulated signal back to 3920 Adjust dBmw of 3920 check receive bit error rate of 3920 Adjust sensitivity till worst bit error rate within radio s decoding ability Bit error rate 5 0 35uV ...

Page 30: ...cies adjustment QT frequency deviation 350Hz 50Hz 10 DQT wide band frequency deviation adjustment 023N debug channel CH 1 low port CH 2 middle port CH 3 high port frequency deviation detector filter LPF 300Hz HPF 20Hz power meter frequency deviation meter oscillosco pe Antenna terminal A720T programming software DQT 023N RF wide band high middle low port frequencies adjustment enter QT adjustment ...

Page 31: ...nd adjustment enter SQ open speaker adjustment adjust squelch to open speaker after debugging click the confirmation to save debugging data Level 5 squelch open speaker SSG 121dBm 1d Bm SQ narrow band open speaker adjustment test channel CH 2 level 5 SSG 121dBm MOD 1KHz DEV 1 5KHz A720T programming software level 5 SQ open RF middle point frequency narrow band adjustment enter SQ open speaker adju...

Page 32: ...INAD 25K 0 22uV 12dB SINAD 12 5K 0 25uV 12dB SINAD Digital sensitivity BER 5 0 22uV BER 5 SNR 25K 45 dB 12 5K 40 dB Adjacent channel selectivity 25K 70 dB 12 5K 65 dB Intermodulation 25K 65 dB 12 5K 65 dB Spurious response rejection 70dB Audio output power 1000 mW Rated audio distortion 5 Battery standby 36 hours 1800mAh 45 hours 2200mAh Battery life 5 5 90 analog digital 14 18 hours 1800mAh 17 21...

Page 33: ...A720T VHF Service Manual V1 0 33 56 Audio distortion 5 Frequency stability 2 5 ppm Max frequency deviation 25K 5 kHz 12 5K 2 5 kHz ...

Page 34: ...R 9 R41 R327 R338 R624 R630 R631 R634 R635 R636 6 151 14702211 010 SMD carbon resistor 47R 5 0402 YAGEO RC0402JR 0747R 3 R21 R22 R519 7 151 16802211 010 SMD carbon resistor 68R 5 0402 YAGEO RC0402JR 0768R 1 R510 8 151 11012211 010 SMD carbon resistor 100R 5 0402 YAGEO RC0402JR 07100R 6 R60 R356 R357 R393 R416 R417 9 151 11812211 010 SMD carbon resistor 180R 5 0402 YAGEO RC0402JR 07180R 1 R517 10 1...

Page 35: ...0 SMD carbon resistor 8K2 5 0402 YAGEO RC0402JR 078K2 1 R506 27 151 11032211 010 SMD carbon resistor 10K 5 0402 YAGEO RC0402JR 0710K 13 C28 R303 R308 R326 R336 R337 R347 R381 R396 R397 R425 R541 R391 28 151 11232211 010 SMD carbon resistor 12K 5 0402 YAGEO RC0402JR 0712K 2 R504 R549 29 151 11532211 010 SMD carbon resistor 15K 5 0402 YAGEO RC0402JR 0715K 1 R638 30 151 11832211 010 SMD carbon resist...

Page 36: ... 5 0402 YAGEO RC0402JR 07470K 7 R31 R502 R503 R511 R512 R540 R551 49 151 11052211 010 SMD carbon resistor 1M 5 0402 YAGEO RC0402JR 071M 5 R52 R56 R96 R533 R546 50 151 10002321 010 SMD carbon resistor 0R 5 0603 YAGEO RC0603JR 070R 3 C394 L305 L520 51 151 11012321 010 SMD carbon resistor 100R 5 0603 YAGEO RC0603JR 07100R 1 C672 52 151 15612321 010 SMD carbon resistor 560R 5 0603 YAGEO RC0603JR 07560...

Page 37: ...5C1H470J 1 C26 71 081 15606251 040 SMD ceramic capacitor COG 56P 5 0402 50V mu Rata GRM1555C1H560J 1 C83 72 081 16806251 040 SMD ceramic capacitor COG 68P 5 0402 50V mu Rata GRM1555C1H680J 2 C584 C585 73 081 11016251 040 SMD ceramic capacitor COG 100P 5 0402 50V mu Rata GRM1555C1H101J 8 C327 C434 C465 C469 C512 C557 C673 C699 74 081 11516251 040 SMD ceramic capacitor COG 150P 5 0402 50V mu Rata GR...

Page 38: ...0 86 081 42237241 040 SMD ceramic capacitor X7R 22nF 10 0402 25V mu Rata GRM155R71E223K 5 C331 C378 C385 C481 C488 87 081 43337241 040 SMD ceramic capacitor X7R 33nF 10 0402 25V mu Rata GRM155R71E333K 2 C577 C578 88 081 44737241 040 SMD ceramic capacitor X7R 47nF 10 0402 25V mu Rata GRM155R71E473K 2 C25 C446 89 081 46837231 040 SMD ceramic capacitor X7R 68nF 10 0402 16V mu Rata GRM155R71C683K 2 C4...

Page 39: ...citor COG 56P 5 0603 50V mu Rata GRM1885C1H560J 1 C128 101 081 12216351 040 SMD ceramic capacitor COG 220P 5 0603 50V mu Rata GRM1885C1H221J 1 C84 102 081 41027351 040 SMD ceramic capacitor X7R 1nF 10 0603 50V mu Rata GRM188R71H102K 2 C21 C115 081 41027351 070 SMD ceramic capacitor X7R 1nF 10 0603 50V YAGEO CC0603KRX7R9BB102 103 081 41047351 040 SMD ceramic capacitor X7R 100nF 10 0603 50V mu Rata ...

Page 40: ...2032101 010 Wound chip inductor 22nH 5 0603 mu Rata LQW18AN22NJ00 1 L505 211 22022101 010 Wound chip inductor 22nH 2 0603 mu Rata LQW18AN22NG00 119 211 1025C201 050 Wound chip inductor 1 0uH 20 2012 TDK MLZ2012M1R0HT000 1 L20 120 211 22239101 050 Wound chip inductor 2 2uH 5 2520 TDK NLV25T 2R2J PF 1 L22 121 211 4726A101 06 0 Wound chip inductor 4 7uH 30 4012 Sunlord SWPA4012S4R7NT 2 L304 L319 122 ...

Page 41: ... D408 025 5V1D5204 25 0 Zener diode WZ5C5V1D5E SOD 523 CYG 141 031 550AR123 15 0 Audion NPN SMD BFU550AR SOT23 NXP 3 Q8 Q503 Q505 142 031 C4617222 050 Audion NPN SMD 2SC4617TLR SOT 416 SC 75A ROHM 2 Q325 Q406 143 031 C5108122 080 Audion NPN SMD 2SC5108 SOT 523 SC 75 TOSHIBA 1 Q610 144 031 U550X116 15 0 Audion NPN SMD BFU550X SOT143B NXP 1 Q501 145 031 114EE222 05 0 Audion NPN SMD DTC114EEBMGTL SOT...

Page 42: ...abilizer IC 5 0V LM2734XMK SOT 23 6 2 U313 U322 161 012 B502M291 19 0 stabilizer IC 5V XC6204B502MR SOT 25 1 U315 012 P170N191 14 0 stabilizer IC 5V RP170N501D TR FE SOT 23 5 162 012 2822G101 23 0 Audio Amplifier IC TDA2822G SOP 8 UTC 1 U306 163 012 S8012291 330 voltage detection IC S 80128ANMC JCNT2U SOT 23 5 SII 1 U317 164 012 X2571199 54 0 PLL IC LMX2571NJKR WQFN36 1 U601 165 014 15050115 250 S...

Page 43: ...TLAE010 ALPS 1 6N 1 K4 177 50C A720T001 01 1 battery connector A720T PA phosphor copper BeCu black 1 J404 178 67Y A780T001 01 1 antenna contact clip A780T 0 2t BeCu Gold Plated 1 CN201 179 466 720T1211 V0 2 PCB Main Board Six layer blind hole A720T VHF V2 MP60LI107919A0 112 9 45 2 1 2T 1 Production tools Software CPU Prog ram Part Number Version check code Machine Burn file name 955 A720T102011 3 ...

Page 44: ...0200802 151 FPC male socket 20PIN 8 1 5mm AXK6F20347YG 1 J402 M 371 90200802 152 FPC male socket 20PIN 8 1 5mm AXK6F20347YG 2 815 0A720T00 00 1 PTT connector A720T 1 2 1 462 780TYY22 V 01 PTT FPC Soft PVC double layer A780T VHF V1 2S00450A0 77 8 51 0 15mm 1 2 2 371 90120501 151 PC female socket 12PIN 6 1 5mm AXK5F12347YG 1 J902 Plastic Parts 1 501 A720T001 01 4 Housing A720T PC1414 black 4PCS Copp...

Page 45: ...20T 24 9 5 0 3t black back gum 1 for Mic PCB 10 708 0A720T01 01 2 sponge pad A720T 13 0 3 3mm hard sponge black 2 bilateral holes of the aluminum case 11 708 000A8103 01 1 Encoder sponge pad A 81 9 5 9 5 1 0mm sponge black single side gum 1 FUN FPC cover 12 708 000A8102 01 1 Potentiometer sponge pad A 81 9 5 8 5 2 0mm sponge black single side gum 1 PTT FPC cover 13 70F 0A720T01 01 1 Water dust pro...

Page 46: ...ring D3 1 0 3 3 8N piano wire nickel plating 1 FOR SOS button 7 63Y A720T001 11 1 E snap spring D3 0 ID1 2 0 3mm SUS304 1 FOR SOS button 8 662 P0020060 102 machine screw PM2 6 cross recess stainless steel 2 small back cover and aluminum case 9 662 P0020040 301 machine screw PM2 4 Trox stainless steel 2 housing and aluminum case 10 611 A720T001 01 3 antenna base A720T brass teflon Gold Plating nick...

Page 47: ... 4V 1800mAH English 821 L1878N00 00 2 Li ion battery AB L1878 7 4V 1800mAH Chinese not waterproof 4 812 X2136174 00 1 Antenna assembly long thin 168mm rubber SMA Krubber SMA K 136 174MHz X 2 136 174M 3108 B gum cover 1 5 761 25500001 111 hand strap TH 308GB 255mm black English 1 6 751 08516007 011 PE bag 85 160 0 07mm 1 for battery 7 751 11026007 011 CPE bag 110 260 0 07mm 1 for transceiver 8 751 ...

Page 48: ...sion Spring A720T nickel plating 1 16 4 614 00A82001 01 1 belt clip Hinge A 82 1 9 23 6 SUS301 nickel plating 1 optional parts 1 821 BL227800 00 1 Li ion battery AB L2278 7 4V 2200mAH Chinese 1 821 BL227800 00 2 Li ion battery AB L2278 7 4V 2200mAH English 2 814 AEHH8T02 0 01 D type ear hook AE HH8 TD HRE 1016H8 AB2 Digital H8 1 814 AEHH8T03 0 01 G type ear hook AE HH8 TG02 HRE 1013H8 AB2 Digital ...

Page 49: ...A720T VHF Service Manual V1 0 49 56 Fig 1 A720T BIT Map TOP Side ...

Page 50: ...A720T VHF Service Manual V1 0 50 56 BOT Side ...

Page 51: ... 3 18 V SSA 19 V REF 20 V REF 21 V DD A 22 PA O W KU P 23 PA 1 24 PA 2 25 P A 3 2 6 V S S _ 4 2 7 V D D _ 4 2 8 P C 4 3 3 P E 7 3 8 P E 8 3 9 P E 9 4 0 P E 1 0 4 1 P E 1 1 4 2 P E 1 2 4 3 P E 1 3 4 4 P E 1 4 4 5 P E 1 5 4 6 P B 1 0 4 7 P B 1 1 4 8 V S S _ 1 4 9 V D D _ 1 5 0 PB 12 51 PB 13 52 PB 14 53 PB 15 54 PD 8 55 PD 9 56 PD 10 57 PD 11 58 PD 15 62 PC 7 64 PE4 3 PE5 4 PE6 5 V BA T 6 PC 13 A N ...

Page 52: ... C 301 1u F PL L3 V 3 C 355 47 0P D SP3 V3 C 356 10 uF C 359 47 0P C 360 10 uF DC AUDIO R300 R500 C300 C500 TX D TX D G ND G ND V OL o u t V OL o u t MIC_ OU T MIC_ OU T R XD R XD R X_ CT L R X_ CT L TX _ C TL TX _ C TL TX _ D O W N TX _ D O W N A F_ MO D E V OX EX T_ PTT S W EX T_ PTT S W PL C PL C MIC MU TE C 352 47 0P A 3 V 3 R 421 0R C 4 6 5 1 0 0 P D 4 0 4 E D Z 5 1 B Q404 A O3 400 A Q405 A O...

Page 53: ...4 N C 5 V RE FA 6 A VS S 7 A VD D 8 B I A S 9 N R E C T O 1 0 N A M P O 1 1 N A M P I 1 2 A U D I O O U T 1 3 D I S C O U T 1 4 P D O U T 1 5 R S S I O U T 1 6 IFOUT 17 A VS S 2 18 P DN 19 R STN 20 C SN 21 S CL K 22 S DA TA 23 D ETO 24 L O I N 3 2 D V D D 2 5 D V S S 2 6 V R E F D 2 7 V S S 3 2 8 A G N D O U T 2 9 A G N D I N 3 0 L O C A P 3 1 GND 0 U 500 A K2 365 A R 533 1M R 532 22 0K C 555 1n F...

Page 54: ...nF C N2 0 0 A NT R 97 4K 7 A PC _S W A PC _S W FC C 600 6P C 673 10 0P R 641 0R R 639 N C R 600 1K L6 22 B L60 1 TP 201 V OU T C 6 4 3 1 0 0 n F C 6 4 2 1 0 0 n F C 640 10 0nF C 671 33 00P R 633 4R 7 C 6 4 4 1 0 u F C 651 10 nF C 660 10 00P C 667 10 00P R 645 10 0K R 643 N C C 666 10 nF L6 19 47 0N H C 661 22 0P C 662 22 0P P LL_ DA T P LL_ CL K P LL_ CS P LL_ LD P LL3 V3 LO L C 6 5 2 1 0 0 n F C ...

Page 55: ... NF M UT E MUTE M PS8550 Q 302 DC S W 5V 5T SW 5R SW R X _ C T L T X _CT L 5R 5T 5C SW 5C LM 2734X U313 DT A123JE Q 322 XC 6204B502M R U308 XC 6204B502M R U315 12 288MH z X300 XO UT XI N SD A SC L W P U318 S 80122AN MC U317 PLL LD PLL DA T PLL CS PLL CLK PLL CI RC UI T DM R AU DI O CI RC UI T AF CO DT MF B EEP M UT E DT MF C IR CUI T SY S_I NER V_S DI V_S DO V_S CLK V_C S AP C T V T X RX C IR CUI ...

Page 56: ...A720T VHF Service Manual V1 0 56 56 Fig 4 A720T Packing ...

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