HYT TC-446 Service Manual
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HYT TC-446 Service Manual

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  • Page 1 cn...

  • Page 3: Table Of Contents

    Content General… … … … … … … … … … … … … … … … … … … … … … … … … … … … … 2 Brief Introduction… … … … … … … … … … … … … … … … … … … … … … … … ..3 Software Description…...

  • Page 4: General

    TC- 446 Service Manual 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. ...

  • Page 5: Brief Introduction

    TC- 446 Service Manual Brief Introduction (12) (11) (10) (13) 1. Antenna LED indicator The light will glow red during transmission. The light will glow green during receiving. During transmission, the light flashes red when the battery voltage is low. 3.

  • Page 6: Software Description

    (6) Turn off the power and then disconnect the two SELF points on PCB to complete the model setting. Take TC-446 (446.00625~446.09375MHz) as example. From the initial data table, it is of standard model. To initialize its model and channel data, you can operate as following: (1) Short out the two MS2 points on PCB;...
  • Page 7 TC- 446 Service Manual (4) After data reset, turn off the power, disconnect the two SELF points and restart the power to use the radio. Remarks: The old data (frequency, CTCSS/CDCSS, channel function settings) will be changed once the model is set, and part of functions will also be changed.
  • Page 8 TC- 446 Service Manual 6. User/Factory Wired Clone Mode Turn on the power while holding down MONI, the radio enters wired clone mode. (1) If the two SELF points are disconnected, press MONI again to begin user wired clone and red LED blinks; When cloning is completed, red LED goes out.
  • Page 9 TC- 446 Service Manual  Initial data table Model 4 CH 9-16CH Frequency (MHz) IF (MHz) (MHz) (MHz) (MHz) (MHz) (MHz) (MHz) (MHz) (MHz) (MHz) (MHz) (MHz) (MHz) Standard 446.00625~446.09375 -21.4 446.00625 446.00625 446.05625 446.05625 446.03125 446.03125 446.08125 446.01875 446.06875 446.04375 446.09375 CH QT/DQT...

  • Page 10: Circuit Description

    TC- 446 Service Manual Circuit Description Frequency Configuration The receiver utilizes double conversion superheterodyne. The first IF is 21.4MHz and the second is 455KHz. The first local oscillator signal is supplied from PLL circuit. Frequency needed in the transmitter is supplied from PLL circuit. Figure 1 shows the frequency configuration. Frequency Range: 446.00625 MHz—...
  • Page 11 TC- 446 Service Manual The First Mixer The signal from RF amplifier is mixed with the first local oscillator signal from PLL frequency synthesizer in the first mixer (Q23) to generate a 21.4MHz first IF signal. The first IF signal is then fed through two monolithic crystal filters (XF1) to remove spurious signals from adjacent channels.
  • Page 12 TC- 446 Service Manual Receive signaling CTCSS/CDCSS Audio frequencies over 300Hz of the output signal from IC1 is cut off by a low-pass filter. The resulting signal enters the microprocessor IC11. IC11 determines whether the CTCSS/CDCSS matches the preset value and controls the MUTE and AFCO and the speaker sound output according to the squelch results.
  • Page 13 TC- 446 Service Manual Transmitter Transmit audio The audio signal from microphone is amplified through IC3, and then pre-emphasized , and then filtered by another low-pass filter（separate filter）(Q25 and Q24) to eliminate the frequencies over 3KHz. The resulting signal enters the VCO for direct FM modulation. (See figure 5) CTCSS/CDCSS Encoder The necessary frequency for CTCSS/CDCSS encoder is generated by IC11 and...

  • Page 14: Cpu Pins

    TC- 446 Service Manual CPU Pins PIN No. PIN NAME DESCRIPTION CTCSS/CDCSS input BUSY Input busy signal BATT Detect battery voltage TIBI CTCSS/CDCSS exterior circuit central point input SAVE Power saving control H: OFF L: ON TXLow Transmitter power control H: Low power L: High power data output clock output...
  • Page 15 TC- 446 Service Manual ENC3 Audio muting control MUTE Audio power control TONE5 CTCSS code output TONE4 CTCSS code output TONE3 CTCSS code output TONE2 CTCSS code output TONE1 CTCSS code output TONE0 CTCSS code output WNTC W/N L: Wide H: Narrow 47-70 Power input: 5V...

  • Page 16: Part List 1

    TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3001051830000 Chip resistor 0402 18KΩ J 1/1 R622 3001060000000 Chip resistor 0603 0Ω J 1/10W R106 R107 R108 R110 R151 R192 R194 R197 R202 R508 R601 R602 3001061000000 Chip resistor 0603 10Ω...
  • Page 17 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3001061040010 Chip resistor 0603 100KΩ J 1/ R175 R176 R623 R624 R625 R626 3001061050010 Chip resistor 0603 1MΩ J 1/10 R109 R116 3001061230000 Chip resistor 0603 12KΩ J 1/1 R170 R617 3001061240010...
  • Page 18 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3001061850000 Chip resistor 0603 1.8MΩ J 1/ R155 R156 3001062030000 Chip resistor 0603 20KΩ J 1/1 3001062220000 Chip resistor 0603 2.2KΩ J 1/ R165 R174 3001062230000 Chip resistor 0603 22KΩ J 1/1 R104 R120 3001062240010...
  • Page 19 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address R154 R158 R159 3001064700000 Chip resistor 0603 47Ω J 1/10 R115 R123 R125 R191 3001064710000 Chip resistor 0603 470Ω J 1/1 R118 R166 3001064720000 Chip resistor 0603 4.7KΩ J 1/ R121 R177 3001064730000...
  • Page 20 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3001068200000 Chip resistor 0603 82Ω J 1/10 R171 3001068210010 Chip resistor 0603 820Ω J 1/1 R619 3001068220000 Chip resistor 0603 8.2KΩ J 1/ R117 R169 R628 3001068230010 Chip resistor 0603 82KΩ...
  • Page 21 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3101050800000 Chip capacitor 0402 8PF B 50V C101 C139 C141 C142 C193 3101051000000 Chip capacitor 0402 10PF D 50V C135 C144 C187 C253 C255 3101051010030 Chip capacitor 0402 100PF J 50 C132 C179 C180...
  • Page 22 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3101051030020 Chip capacitor 0402 0.01UF K 2 C137 C240 C241 C242 C243 3101051040040 Chip capacitor 0402 0.1UF K 10 C178 C233 C246 C250 3101051590000 Chip capacitor 0402 1.5PF B 50 C140 C196 3101051810000...
  • Page 23 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3101052220000 Chip capacitor 0402 2200PF K 5 C254 3101052230000 Chip capacitor 0402 0.022UF K C167 C168 C169 3101052240010 Chip capacitor 0402 0.22UF Z 1 C123 3101052490010 Chip capacitor 0402 2.4PF B 50 C102 C192 3101052710000...
  • Page 24 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3101054720000 Chip capacitor 0402 4700PF K 5 C232 3101054730000 Chip capacitor 0402 0.047UF K C157 C158 C161 C162 C237 3101055610000 Chip capacitor 0402 560PF K 50 C171 【switch to 3101055620010】SMT 3101055620000 3101057590000...
  • Page 25 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3104081550000 Ta-capacitor 1206 1.5UF±20% 1 C112 3104081560030 Ta-capacitor 1206 15UF M 6.3V C115 C177 3104082250030 Ta-capacitor 1206 2.2UF K 16V C165 3104082260040 Ta-capacitor 1206 22UF M 10V C118 C247 C248...
  • Page 26 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3231351640000 Air-core inductor E2-0.35*1.6*4TL 3231351680000 Air-core inductor E2-0.35*1.6*8TR 3303010500290 Switch diode 1SS372(TE85L.F 3303020100020 Switch diode MA2S11100L SS- 3303020100070 Switch diode MA2Z07700L SOD 3303020100080 Switch diode MA2S07700L 1.7 3303030100010 Switch diode DAN222(TL) SOT 3303210200000...
  • Page 27 TC- 446 Service Manual Part List 1 Material Name Qty. Ref. No. Address 3499000000140 Transistor 2SK508-K52-T1B-A 3499000000150 Transistor UMC4(NTR) NPN/PN 3499000000180 Transistor UFMMT717 PNP SOT 3501020000030 FET 3SK318YB-TL-E-Q 3503010000010 FET 2SJ243-T1-A P-c 3503020000010 FET 2SK1588-T1-AZ N 3503020000030 FET 2SK1824-T1-A N- 3503040000000 FET UPA572T-A N-cha 3504990000010...

  • Page 28: Adjustment Description

    TC- 446 Service Manual Adjustment Description The radio can be adjusted with PC programming software or by manual adjustment. Manual adjustment procedure of TC-446 is as follow. (Refer to “ model set mode”and “ manual adjust mode”in the section Software Specification.) Instrument:...
  • Page 29 TC- 446 Service Manual  RECEIVER: (Enter the manual adjust mode) Measurement Adjustment Specification Item Condition Test /Remarks Terminal Part Method Instrument Adjust the waveform to the top, and the top is flat, the 1.RX Center. Turn to bandwidth is about 100kHz, 4.
  • Page 30 TC- 446 Service Manual  Transmitter Measurement Adjustment Specification Item Condition Test Terminal Parts Method /Remarks equipment 1. TX Center. Turn to CH13 in 7.Transmit Radio Communication Adjust center Error manual adjust mode and press ≤± 250Hz frequency Test Set frequency PTT.

  • Page 31: Troubleshooting Chart

    TC- 446 Service Manual TC500 Series Troubleshooting Chart I. Receiver: 1. No receive or low RX sensitivity / intermittent RX output: Start Check CF1(455K2nd IF Inject 21.4MHz filter), IC1(IF IC), signal into Q22 pin X1(20.945M 2 C; SSG output ≤ -92dbm;...
  • Page 32 TC- 446 Service Manual Repair Example：(Tested by communication test set after power on) 1) Symptom: TX OK; no RX at all, but RX frequency OK; no-solder at one end of crystal X1; Cure: touch up X1 2) Symptom: TX OK; low RX sensitivity or intermittent RX output; Cure: replace 455KHz filter 3) Symptom: TX OK;...
  • Page 33 TC- 446 Service Manual Start Turn to max. VOL; Hold down Check SPK plug, MONI; around 2.8V (limit) audio SPK, spring; output at SPK plug? Replace faulty components; 1 KHz audio input at IC8(AF AMP) pin1? Check VR1 and its wiring to IC8; Replace faulty components.
  • Page 34 TC- 446 Service Manual Symptom 2: audio OK after power on, no RX audio output or audio distortion in RX (abnormal noise output while holding down MONI) Start Check if Q21 conductive; Check Hold down MONI; operating status of Audio output at Q19, Q20;...
  • Page 35 TC- 446 Service Manual II. Transmitter： 1、No power (low output power) Start Plug into standard power supply (7.5V); Connect instruments; Toggle on TX; Observe current&power changes. Low current High current but and no power no or low power output in TX output in TX In TX, 6.0V In TX, around...
  • Page 36 TC- 446 Service Manual L29, C138, Replace faulty C67 OK? components; In TX, 4.8V Check bias collector voltage, resistor and 1.2V base voltage TX 5V power and 0.3V emitter supply circuit. voltage at Q17? R122, C98, R196, Replace faulty C42 R195 OK? components;...
  • Page 37 TC- 446 Service Manual Repair Example： 1) Symptom: no TX power; > 3A TX current; Cure: replace Q31 2) Symptom: low TX power; Voltage at Q4, Q31, Q32 OK; 10mw power at Q31 （RD07） IN; Around 1W power at D11; Cure: replace Q31 2、No or low TX audio (test port for communication test set：AF OUT/AF IN) Start...
  • Page 38 TC- 446 Service Manual Repair Example： 1) Symptom: no TX audio, cracked VR2; Cure: replace VR2 and adjust 2) Symptom: low TX audio; poor modulation sensitivity of MIC after adjusting VR2 Cure: replace MIC II. PLL： 1、 TX or RX unlock：(Caused by faulty oscillator loop) －...
  • Page 39 TC- 446 Service Manual Start Adjust to freq band/freq Correct software mode settings and freq range? set in the radio; TX unlock: TX unlock on RX unlock: RX unlock on some channels? some channels? Adjust TC2 Voltage at Adjust TC1 Voltage at RX CV? TX CV?
  • Page 40 TC- 446 Service Manual 1、 TX and RX unlock： （Caused by faulty common sector） Start Adjust to correct software Correct software mode settings and freq range? mode and freq; 4.9V at IC2 pin2 ? 12.8MHz at IC2 5V output pin13? Q5(5C)? Check 12.8MHz crystal, C130, TC6;...
  • Page 41 TC- 446 Service Manual Repair Example： 1) Symptom: unable to transmit even if PTT is pressed; wrong freq band found when reading from radio via PC; Cure: correct the freq band 2) Symptom: unable to lock freq, TR accessible sometimes, occasional TX or RX unlock; Cure: replace Q15(5108) 3) Symptom: unable to transmit even if PTT is pressed;...
  • Page 42 TC- 446 Service Manual VI. Power Supply： Fail to power on (no response while rotating power knob after plugging in power supply) Start Plug positive end of power cable into positive connector while negative end into aluminum chassis or ground around PCB;...
  • Page 43 TC- 446 Service Manual Repair Example： 1) Symptom: Plug in 6.0 power cable, rotate power knob but unable to switch on power; voltage at L15 OK; no 7.5V at IC4 IN; power knob OK; Cure: replace D20 2) Symptom: Plug in 6.0 power cable, rotate power knob but unable to switch on power; Voltages at L15, IC4 IN OK;...

  • Page 44: Disassembly And Assembly

    TC- 446 Service Manual Disassembly and Assembly  Remove the Battery Turn the radio off. Slide the battery latches upwards. Pull the top part of the battery away from the radio’ s body and lift the battery from the radio. (See figure 1) Figure 1 ...
  • Page 45 TC- 446 Service Manual Pull the chassis upwards and then pull the chassis away from the front cover. (See figure 3) Figure 3 The disassembly is shown as the figure 4. Figure 4  Disassemble PTT button Push the PTT button in indicated direction until out of the cover. (See figure 5) Figure 5 －...

  • Page 46: Attach The Battery

    TC- 446 Service Manual  Assemble PTT button Paste double-coated tape to the cover. And then press the PTT button into the corresponding opening in the cover. (See figure 6) Figure 6  Attach the battery 1. Fit the extensions at the bottom of the battery into the slots on the radio chassis. Press the top part of the battery towards the radio until a click is heard.

  • Page 47: Exploded View

    TC- 446 Service Manual Exploded View － 45 －...

  • Page 48: Part List 2

    TC- 446 Service Manual Part List 2 Description Qty. 7102506000020 Machine screw M2.5*6.0mm 7102004020050 Self-tapping screw ST2.0*4.0mm Cross recess pan head (color zinc plating) 7102009001000 Machine screw M2.0*9.0mm (color zinc plating) 7102505000100 Machine screw M2.5*5.0mm T9 hexagonal head 6000051000010 TC500 Rear cover Black ABS700 6000374000000 TC308 Antenna cap Black TPUS95A 6100237000000...
  • Page 49 TC- 446 Service Manual 6100075000000 TC-368 Mic gasket Black 30 degree silica rubber Mic CZII-64AP-RoHS -60dB± 2dB φ9.7*4.5mm 5002110000030 4210080000000 Lead with tin on both ends 80mm Black 4210080000300 Lead with tin on both ends 80mm Red 5205000000280 Speaker jack HSJ1456-010320 5205000000190 Earpiece jack HSJ1650-010020 TC500 PVC water-proof gasket PVC 0.3mm-thick Φ4.7...

  • Page 50: Packing

    TC- 446 Service Manual Packing － 48 －...

  • Page 51: Pc Board View

    TC-446 PC Board View Top Layer PCB No.:4100500101600...

  • Page 52: Block Diagram

    TC-446 PC Board View Bottom Layer PCB No.:4100500101600...

  • Page 53: Schematic Diagram

    0.1U C125 1U/16V C198 470p 10u/10V UPA572T 1u/ 6.3V 1000P 1000P 1000P R177 HYT Science & Technology Co. Ltd. 4.7K DTA114YE Error : HYT.jpg file not found. R175 100K MODEL PAGE TC-446 Part Name Schematic Diagram DATE August , 2005 FILE NO.

  • Page 54: Specifications

    TC- 446 Service Manual Specifications 400 MHz ~420 MHz 450 MHz ~470 MHz Frequency range 136 MHz ~150 MHz 150 MHz ~174 MHz Channel capacity (simplex) Channel spacing 25KHz(wide)/12.5KHz(narrow) Antenna impedance 50Ω Microphone impedance 2KΩ Operation voltage 6V DC Frequency stability ±2.5×10 Transmitter Carrier frequency error...

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