Radio Shack HTX-400 Service Manual

Mini handheld 70cm fm, amateur
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Service
Specifications ----------------------------------------------------------------------------------------------- 1
Theory of Operation --------------------------------------------------------------------------------------- 2
Block Diagram ---------------------------------------------------------------------------------------------- 8
Alignment Instructions ------------------------------------------------------------------------------------ 9
Test Equipment Set-Up --------------------------------------------------------------------------------- 1 2
Semiconductor Lead Identification and IC Internal Diagram ---------------------------------- 15
PCB Views ------------------------------------------------------------------------------------------------- 25
Wiring Diagram ------------------------------------------------------------------------------------------- 29
Troubleshooting Chart ---------------------------------------------------------------------------------- 30
Exploded View of Unit ---------------------------------------------------------------------------------- 31
Whole Parts List ------------------------------------------------------------------------------------------ 32
Schematic Diagrams ------------------------------------------------------------------------------------ 40
HTX-400
MINI HANDHELD 70cm FM
AMATEUR TRANSCEIVER
Catalog Number : 19-1104
CONTENTS
¨ Ï 1999 Tandy Corporation
All Rights Reserved.
RadioShack is a registered trademark used by Tandy Corporation
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Summary of Contents for Radio Shack HTX-400

  • Page 1: Table Of Contents

    Service HTX-400 MINI HANDHELD 70cm FM AMATEUR TRANSCEIVER Catalog Number : 19-1104 CONTENTS page Specifications ----------------------------------------------------------------------------------------------- 1 Theory of Operation --------------------------------------------------------------------------------------- 2 Block Diagram ---------------------------------------------------------------------------------------------- 8 Alignment Instructions ------------------------------------------------------------------------------------ 9 Test Equipment Set-Up --------------------------------------------------------------------------------- 1 2 Semiconductor Lead Identification and IC Internal Diagram ---------------------------------- 15...
  • Page 2: Specifications

    SPECIFICATIONS 1. GENERAL FREQUENCY : RX -------------------------------------------------------- 420-470 MHz TX --------------------------------------------------------- 430-470 MHz FREQUENCY GENERATION ------------------------ PLL SYNTHESIZER FREQUENCY STABILITY ---------------------------- ¡ ¾ 5 PPM OPERATING TEMPERATURE ---------------------- 14¢ ª TO 131¢ ª F (-10¡ É TO 55¡ É ) POWER SOURCE -------------------------------------- DC 3.0V TO 9V MODULATION -------------------------------------------- F3E IMPEDANCE ---------------------------------------------- 50 ohm...
  • Page 3: Theory Of Operation

    THEORY OF OPERATION 1. SEMICONDUCTORS AND FUNCTION 1.1 IC COMPLEMENT REF.NO TYPE MANUFACTURER FUNCTION IC601 TK11230AM TOKO IC-REGULATOR IC801 TMP87PP21DF THOSHIBA CPU IC IC802 24LC16B PRO-CHIPS EEPROM IC806 NJM2902V MIC AMP IC501 LV2105V SANYO PLL IC NJM2073M AUDIO POWER AMP IC805 FX465DF MX-COM...
  • Page 4 1.3 DIODE COMPLEMENT REF.NO TYPE MANUFACTURER FUNCTION D804-805 1N4001(M2) ROHM REVERSE B+ PROTECT D807 1N4001(M2) ROHM REG REVERSE PROTECT D806 RB471E ROHM D/D CON S/W D804A KDS187 CTCSS COMPARATOR D830 MA77 PANASONIC CLOCK SHIFT S/W D802 KDS187 MODEL SELECTOR ZD803 ZD7.5Y PTT S/W LED801-802...
  • Page 5 2. DESCRIPTION OF FREQUENCY DETERMINING AND STABILIZING CIRCUIT 2.1 INTRODUCTION THE FREQUENCIES FOR TRANSMITTER AND RECEIVER LOCAL FREQUENCIES ARE ALL DRIVED FROM A SINGLE 15.2 [MHz] VCTCXO BY MEANS OF A PHASE LOCKED LOOP. THE FIRST LOCAL OSCILLATOR FREQUENCIES ARE 389.15 [MHz] TO 439.15 [MHz]. THE SECOND LOCAL FREQUENCY IS FIXED AT 30.4 [MHz] TO GENERATE SECOND IF 450[KHz].
  • Page 6 (4) PROGRAMMABLE DIVIDER AND ITS CONTROL THE PROGRAMMABLE INPUTS FOR EACH CHANNEL ARE SET INSIDE IC801. EACH INPUT SIGNAL TO CONTROL THE PLL IC501 IS DONE WITH THE PROVIDED (CPU IC 801) KEY MATRIX INPUT PINS - PIN25 TO PIN28 AND FOR EACH KEY MATRIX INPUT, AN INTERNAL CODE CONVERT EPROM PROVIDES THE APPROPRIATE BINARY CONTROL TO IC501 FOR THAT CHANNEL.
  • Page 7 (8) RECEIVER LOCAL OSCILLATOR OUTPUTS 1’ st MIXER : THE OUTPUT SIGNALS OF Q104 IS INJECTED TO THE SOURCES OF 1st MIXER Q203 IN THE 1’ st IF MIXER SECTION. 2’ nd MIXER : THE OUTPUT OF 30.4 [MHz] OSCILLATOR CIRCUIT WITH X401 IS INJECTED INTO IC401.
  • Page 8 (2) CIRCUIT FOR SUPPRESSION OF SPURIOUS RADIATION THE TUNING CIRCUIT BETWEEN THE OUTPUT OF FINAL AMP Q101 AND ANTENNA, 4-STAGE "PHI TYPE" NETWORK L101, L102, L103, L104, L105, L106, L107, C101, C102, C103, C104, C105, C106 SERVES AS A SPURIOUS RADIATION SUPPRESSOR. THIS NETWORK ALSO SERVES TO MATCH THE IMPEDANCE BETWEEN TX FINAL POWER AMP Q101 AND THE ANTENNA.
  • Page 10: Alignment Instructions

    ALIGNMENT INSTRUCTIONS 1. ALIGINMENT LAYOUT RV803 RV802 [CPU SECTION ] [ RF SECTION ] 2. TEST EQUIPMENT REQUIRED 1) CPU and Phase Locked Loop Section ¨ ç Frequency Counter ¨ è DC Power Supply ¨ é DC Volt Meter ¨ ê Oscilloscope 2) Transmitter Section ¨...
  • Page 11 3) Receiver Section ¨ ç RF Signal Generator ¨ è AF Level Meter ¨ é Distortion Meter ¨ ê DC Power Supply ¨ ë Sinadder Meter ¨ ì Oscilloscope ¨ í 16 Ohm 1w Dummy Load 3. ALIGNMENT PROCEDURE 1) PHASE LOOKED LOOP AND CPU SECTION STEP SETTING CONNECTION ADJUST...
  • Page 12 2) TRANSMITTER SECTION STEP SETTING CONNECTION ADJUST ADJUST FOR RF Power stage ; Connect dummy RV-101 Adjust for max. Mode : Transmit load and RF power indication on the Volume : Optional meter to the external power meter (300mW¡ ¾ 5 0mW) Squelch : Optional ANT-jack on the Frequency : 445.50MHz...
  • Page 13: Test Equipment Set

    TEST EQUIPMENT SET-UP (FIGURE 1) (FIGURE 2)
  • Page 14 45dBc (FIGURE 3) (FIGURE 4)
  • Page 15 (FIGURE 5) (FIGURE 6)
  • Page 16: Semiconductor Lead Identification And Ic Internal Diagram

    SEMICONDUCTOR LEAD IDENTIFICATION AND IC INTERNAL DIAGRAM 1. INTERGRATED CIRCUITS A. IC801 TMP87CH21DF...
  • Page 17 PIN NAME REMARKS DESCRIPTION ACTIVE GROUND XOUT HIGH FREQUENCY CLOCK OUT HIGH FREQUENCY CLOCK IN RESET RESET input P22(XTOUT) OPEN DRAIN P21(XTIN) OPEN DRAIN CTCSS DEFAULT OPTION LOW:CTSS TEST Fixed to Low(GROUND) P20(INT5/STOP) OPEN DRAIN BUSY input (IN) High:Busy P40(INT3/TC3) TRI STATE PLL(LV2105) CLOCK (OUT)
  • Page 18 PIN NAME REMARKS DESCRIPTION ACTIVE VASS AD REFERENCE LOW VOLTAGE VAREF AD REFERENCE HIGH VOLTAGE P70(SEG31) OPEN DRAIN AUDIO PROTECT (IN) P71(SEG30) OPEN DRAIN PTT KEY (IN) PUSH:”H” P72(SEG29) OPEN DRAIN OPTION VIBRATOR (IN) P73(SEG28) OPEN DRAIN SIGNAL MUTE (OUT) P74(SEG27) OPEN DRAIN CLOCK SHIFT...
  • Page 19 PIN NAME REMARKS DESCRIPTION ACTIVE COM1 LCD COMMON OUTPUT COM0 LCD COMMON OUTPUT LCD DRIVE VOLTAGE...
  • Page 20 B. IC805 FX465 FX465 C. IC601 / IC803 TK11230 D. IC3 NJM 2073...
  • Page 21 E. IC501 LV2105 F. IC802 24LC16...
  • Page 22 G. IC806 NJM2902V H. IC401 TA31136FN...
  • Page 23 IC804 XC6371 J. IC807 NJM2904 K. IC808 AS2810 ADJ/GND V...
  • Page 24 2. TRANSISTOR I.D. Number DESCRIPTION SPECIFICATION MARKING TYPE Q101 MRF9242T1 9242 Q102, Q103, Q302, Q303 MMBR951LT1 Q104, Q105, Q304 2SC3356 R24 OR R25 Q201, Q202, Q302, Q303, 2SC4226 R24 OR R25 Q304 Q203 KTC4081 Q301, Q606 KRC404 Q501 KRC410 Q601, Q602, Q603, Q604 KRA310 Q607 KTA2015...
  • Page 25 3. DIODE I.D. Number DESCRIPTION SPECIFICATION MARKING TYPE D201, D202, D101, DIODE MA77 D301, D830 D102 DIODE MA862 D804, D805, D807 DIODE 1N4001 D806 DIODE RB471E D804A, D802 DIODE KDS187 ZD803 ZENER-DIODE ZD7.5Y 7.5Y LED801, LED802 A TYPE B TYPE C TYPE D TYPE E TYPE...
  • Page 26: Pcb Views

    PCB VIEWS 1. CPU, RF, VCO BOARD LOCATION CPU TOP LOCATION CPU BOTTOM LOCATION RF TOP LOCATION RF BOTTOM LOCATION VCO TOP LOCATION VCO BOTTOM LOCATION...
  • Page 27 2. CPU, RF, VCO BOARD PATTERN CPU TOP PATTERN CPU 2LAYER PATTERN RF TOP PATTERN RF 2LAYER PATTERN VCO TOP PATTERN VCO 2LAYER PATTERN...
  • Page 28 3. CPU, RF, VCO BOARD PATTERN CPU 3LAYER PATTERN CPU BOTTOM PATTERN RF 3LAYER PATTERN RF BOTTOM PATTERN VCO 3LAYER PATTERN VCO BOTTOM PATTERN...
  • Page 29 4. AUDIO, PTT BOARD LOCATION AUDIO TOP LOCATION PTT TOP LOCATION 5. AUDIO, PTT BOARD PATTERN AUDIO TOP PATTERN AUDIO BOTTOM PATTERN PTT TOP PATTERN PTT BOTTOM PATTERN...
  • Page 30: Wiring Diagram

    WIRING DIAGRAM BLACK YELLOW GREEN SPEAKER...
  • Page 31: Troubleshooting Chart

    TROUBLESHOOTING CHART SYMPTOM PROBLEM REMEDY Unit does not work at 1. Defective power switch VR101 1.Replace 2. Defective INPUT POWER LINE / REGULATOR 2.Replace No output from speaker 1. Defective external speaker jack 1.Replace or repair at all 2. Defective IC3,Q111,113,114 & Speaker 2.Replace defective component No noise on speaker...
  • Page 32: Exploded View Of Unit

    EXPLODED VIEW OF UNIT...
  • Page 33: Whole Parts List

    WHOLE PARTS LIST The numbers used on "Exploded View of Unit" correspond to Ref No. shown at the right side of the table below. CODE NO. DESCRIPTION SPECIFICATION Q'TY REF.NO. LOCATION 80169001 ASS'Y SET 61000328 COVER 1-BATTERY ABS, BLK 61000419 WINDOW-LCD ACRYL, SILK 64000065 CAP"C"-DC JACK SILICONE,BLK...
  • Page 34 CODE NO. DESCRIPTION SPECIFICATION Q'TY REF.NO. LOCATION 15210104 THICK FILM CHIP-R 100K-J-1/16W (0603) R831,R845,R848,R849, R853,R854,R855,R862, R869,R852,R861B,R848A 15210105 THICK FILM CHIP-R 1M-J-1/16W (0603) R871 15210121 THICK FILM CHIP-R 120-J-1/16W (0603) R808 15210153 THICK FILM CHIP-R 15K-J-1/16W (0603) R839 15210182 THICK FILM CHIP-R 1.8K-J-1/16W (0603) R823,R827 15210222 THICK FILM CHIP-R...
  • Page 35 CODE NO. DESCRIPTION SPECIFICATION Q'TY REF.NO. LOCATION 1821A010 C-CHIP-TANTALUM 10UF-M-6V SIZE A C815,C824,C827,C855, C857,C862 1821B010 C-CHIP-TANTALUM 10UF-M-16V SIZE B3 C809 1821C147 C-CHIP-TANTALUM 47UF-M-10V SIZE C C812,C801 19610004 DIODE-SWITCH KDS187 D804A 19610013 DIODE KDS190 D802 19810001 DIODE D804,D805,D807 19820006 DIODE-SCHOTTKY RB471E D806 20010003 DIODE-ZENER ZO2W7.5V(Z)
  • Page 36 CODE NO. DESCRIPTION SPECIFICATION Q'TY REF.NO. LOCATION M40E052C PCB-MH-430-AUDIO 18*10.4*0.8T,MLB 80169008 ASS'Y RF B.D 80169013 ASS'Y RF SMD 11610011 IC-IF TA31136FN IC401 11610015 IC LV2105V IC501 11610034 IC UPC2748T IC201 11710003 IC-REGULATOR TK11230AMTL IC601 13010003 TR-PNP KTA1001S Q106 13210013 TR-PNP KRA225S Q607 13210015 TR...
  • Page 37 CODE NO. DESCRIPTION SPECIFICATION Q'TY REF.NO. LOCATION 15210683 THICK FILM CHIP-R 68K-J-1/16W (0603) R405A 15210821 THICK FILM CHIP-R 820-J-1/16W (0603) R214 15210823 THICK FILM CHIP-R 82K-J-1/16W (0603) R404 16510222 RESISTOR-SEMI POZ3AN-1-222-N TOO RV101 17010010 C-CERAMIC GRM39 COG 010C 50 C104 17010030 C-CERAMIC GRM39 COG 030C 50 C202,C219...
  • Page 38 CODE NO. DESCRIPTION SPECIFICATION Q'TY REF.NO. LOCATION 1821B010 C-CHIP-TANTALUM 10UF-M-16V SIZE B3 C602 19610001 DIODE-SWITCH KDS181 D601 19610007 DIODE-SWITCH KDS114 D204 19610010 DIODE MMBD101LT1 D401 19610012 DIODE-SWITCH MA-862 D102 19610014 DIODE MAS-728 D205 22010100 COIL-CHIP FSLU2520 R22K-P2 L106 22010105 COIL-CHIP FSLU2520 27NK-P2 L113,L114 22010108 COIL-CHIP...
  • Page 39 CODE NO. DESCRIPTION SPECIFICATION Q'TY REF.NO. LOCATION 15210623 THICK FILM CHIP-R 62K-J-1/16W (0603) R302 17010010 C-CERAMIC GRM39 COG 010C 50 C307 17010090 C-CERAMIC GRM39 COG 090C 50 C315 170100R5 C-CERAMIC GRM39 COG 0R5C 50 C321 17010102 C-CERAMIC GRM39 X7R 102K 50 C303,C333 17010103 C-CERAMIC GRM39 X7R 103K 50...
  • Page 40 CODE NO. DESCRIPTION SPECIFICATION Q'TY REF.NO. LOCATION 69000202 P.E FOAM-BOTTOM P.E FOAM, WHT 69000263 BOX-GIFT(R/SHACK) MANILAR 450G 70000088 BAG-POLY(100*250) LDPE 0.05T,CLR 80200017 ASS'Y BATT.CASE 61000242 BUTTON-LOCK ACETAL,BLK 61000256 CASE 1-BATTERY PC+ABS,BLK 62000033 TERMINAL A SUS 0.2T,NI-PL 62000034 TERMINAL B SUS 0.2T,NI-PL 62000035 TERMINAL C SUS 0.2T,NI-PL 68000031 SCREW-B.H,T/P2...

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