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TR-127GK/DX 

 
 

CHAPTER 5 

MAINTENANCE 

 

 

 

5.0 PRECAUTIONS 

The inherent quality of the solid-state components used in this transceiver will provide many years of 
continuous use. Taking the following precautions will prevent damage to the transceiver. 
 
(i) Never key the transmitter unless an antenna or suitable dummy load is connected to the antenna 

receptacle.  

 
(ii) Ensure that the input voltage does not exceed 16 VDC or fall below 11. 
 
(iii) Transmitting over long periods can cause heat built-up and cause transmitter damage. 
 

5.1 PERIODIC INSPECTION 

This unit is aligned at the factory to deliver maximum performance. However, continued performance 
cannot be expected without periodic inspection and maintenance. Important points to be checked 
regularly are as follows; 
 
 

Check Item 

Action 

Whip antenna (option) If cracked or broken, replace it. 
Coaxial cable 

If sheath is cracked or immersed 
in water, install new coaxial 
cable.  

Coaxial & power plug 
connections 

If loosened, reconnect. If 
corroded, clean contacts. 

Battery connection 

If corroded, clean power 
terminals. 

Ground terminal 

If corroded, clean terminal. 

 
 

5.2 FUSE REPLACEMENT

  

To protect the equipment from serious damage, a fuse is provided on the power supply lines. The fuse 
protects against over voltage / reverse polarity or internal fault of the equipment. If the fuse has blown, 
first find out the cause of the trouble before replacing it. A fuse rated for more than the transceiver 
requirement should not be used, since it may permanently damage the equipment. Damage due to over 
fusing is not covered by the warranty. 

Summary of Contents for Texas Ranger TR-127DX

Page 1: ...REV A Dec 2004 TR 127GK DX 40 CHANNEL AM CB MOBILE RADIO Service Manual Communications Inc ...

Page 2: ...crophones And Installation 8 CHAPTER 3 CIRCUIT DESCRIPTION 3 0 Introduction 9 3 1 PLL Circuit 9 3 2 Receiver Circuit 9 3 3 Transmitter Modulation Circuit 9 3 4 Transmitter Amplifier Circuit 9 CHAPTER 4 ALIGNMENT 4 0 Required Test Equipment 11 4 1 Alignment Procedures 11 CHAPTER 5 MAINTENANCE 5 0 Precautions 15 5 1 Periodic Inspection 15 5 2 Fuse Replacement 15 CHAPTER 6 DIAGRAMS AND PARTS LIST 6 0...

Page 3: ...ators Meter shows incoming signal strength RF output power and SWR level Transmit LED glows red when transmitter is in operation 1 2 RECEIVER Sensitivity For 10dB S N 1 0µV IF Frequency AM 10 695 MHz 1st IF 455 KHz 2nd IF Image Rejection 50dB Adjacent Channel Selectivity 60dB RF Gain Control 45dB adjustable for optimum signal reception Automatic Gain Control AGC Figure Of Merit 100mV for 10dB Chan...

Page 4: ...y from the microphone In the Public Address PA mode the control function as the volume control 3 ON OFF VOLUME CONTROL This knob controls the volume and power to the radio To turn radio on rotate the knob clockwise Turning the knob further will increase the volume of the receiver 4 SQUELCH CONTROL This knob is used to eliminate background noise being heard through the receiver which can be disturb...

Page 5: ... 11 ANL OFF SWITCH In the ANL position the Automatic Noise Limiter ANL in the audio circuits is activated 12 NB OFF SWITCH In the NB position the Noise Blanker NB is activated The NB is very effective in eliminating repetitive impulse noise such as ignition interference 13 PA CB SWITCH Select the mode of operation In the PA position the radio acts as public address amplifier Your voice will come o...

Page 6: ... 2 Rear Panel 1 ANTENNA This jack accepts a 50 ohm coaxial cable with a PL 259 type plug 2 DC POWER This jack accepts the 13 8V DC power cable with built in fuse The power cord provided with the radio has a black and red wire The black goes to negative and red goes to positive 3 EXT SP This jack accepts a 4 to 8 ohm 5 watt external speaker When the external speaker is connected to this jack the bu...

Page 7: ... 255 4 27 005 24 27 235 5 27 015 25 27 245 6 27 025 26 27 265 7 27 035 27 27 275 8 27 055 28 27 285 9 27 065 29 27 295 10 27 075 30 27 305 11 27 085 31 27 315 12 27 105 32 27 325 13 27 115 33 27 335 14 27 125 34 27 345 15 27 135 35 27 355 16 27 155 36 27 365 17 27 165 37 27 375 18 27 175 38 27 385 19 27 185 39 27 395 20 27 205 40 27 405 ...

Page 8: ...e VOL to a comfortable listening level 4 Set the MODE switch to the desired mode 5 Listen to the background noise from the speaker Turn the SQUELCH knob slowly clockwise until the noise just disappears The SQUELCH is now properly adjusted The receiver will remain quiet until a signal is actually received Do not advance the control too far or some of weaker signals will not be heard 6 Set the CHANN...

Page 9: ... lead cable The audio conductor and its shielded lead comprise two of the leads The third lead is for transmit control and the fourth is for receiving control The microphone should provide the functions shown in the schematic below Figure 2 3 4 WIRE MIC CABLE Pin Number Mic Cable Lead 1 Audio Shield 2 Audio Lead 3 Transmit Control 4 Receive Control Figure 2 3 Your Transceiver Microphone Schematic ...

Page 10: ...3 2 RECEIVER CIRCUIT The incoming RF signal comes into the radio via the antenna and into the front end pre amp Q12 The RF signal is fed into the mixer circuit of Q13 and then into the AM IF section of the receiver The signal is then detected by the AM detector and then fed to the audio amplifier section of the receiver and finally out to the speaker 3 3 TRANSMITTER MODULATION CIRCUIT 1 The transm...

Page 11: ... Q10 Q15 D2 3 AM IF AM DET SQ AF POWER IC1 IC3 L23 TX MIXER MIXER L P F TX POWER LOW PASS PLL TX L21 GPS 668 ROTARY SW PLL CODE L12 13 14 FILTER OSC Q16 Q17 IC2 Q18 DRIVER DRIVER X2 10 695MHz Q24 TX RX SW VCO PLL IC IC4 X1 10 240MHz TX 8V 8V RX 8V Q19 MIC AMP IC1 AF POWER Q25 REG DC 13 8V TR 127GK DX BLOCK DIAGRAM ...

Page 12: ...quired test equipment listed are used for the test setup or alignment shown in Figure 4 1 Transmitter Test Setup and Figure 4 2 Receiver Test Setup These test setups are used in part or total during the following adjustments Refer to page 14 for adjustment locations 4 1 1 PLL ALIGNMENT ITEM U U T SETTING ADJUST POINT MEASUREMENT VCO Set radio to CH 1 AM RX mode Connect Multi meter to TP9 L23 2 5 V...

Page 13: ...ght on 4 1 3 RECEIVER ALIGNMENT ITEM U U T SETTING ADJUST POINT MEASUREMENT AM Sensitivity Set radio to CH 19 AM RX mode Set RF GAIN fully clockwise Set SQ fully counter clockwise Set VOL Control at 2 o clock Connect RF SG to antenna jack Frequency 27 185 MHz 1uV Mod 30 L4 L5 L6 L7 L8 L9 L20 L2 L3 VR1 Audio Output 2V S N 10 dB Set radio to CH 40 AM RX mode RF SG setting 27 405 MHz Set radio to CH ...

Page 14: ... 13 Figure 4 1 Transmitter test setup Figure 4 2 Receiver test setup ...

Page 15: ... 14 TR 127GK DX MAIN PCB ADJUSTMENT LOCATION ...

Page 16: ...inspection and maintenance Important points to be checked regularly are as follows Check Item Action Whip antenna option If cracked or broken replace it Coaxial cable If sheath is cracked or immersed in water install new coaxial cable Coaxial power plug connections If loosened reconnect If corroded clean contacts Battery connection If corroded clean power terminals Ground terminal If corroded clea...

Page 17: ... 16 TR 127GK DX CHAPTER 6 DIAGRAMS PARTS LIST 6 0 GENERAL Information on most electrical and mechanical parts is included in the parts list The reference designators are in alphanumeric order ...

Page 18: ... 17 TR 127GK DX ROTARY SWITCH PCB EPT092920Z SMD COPPER SIDE COMPONENT SIDE ...

Page 19: ...16 D317 D318 D319 D320 D321 D322 EDSS00355Y DIODE S M D 1SS355 6 D302 D303 D304 D305 D306 D308 D309 D310 D311 D312 D313 D314 D315 EDSS00181Y DIODE S M D 1SS181 TE85L 7 Q301 Q303 Q304 TYZRN1403Z TR RN1403 TE85L 8 Q302 TYDTC114TK TR DTC114TK 9 ROTARY SW EWRT32059S ROTARY SW GPS 0668 10 J303 EX07N48223 PCB CONN S 2 PIN 11 J301 EX07N48222 PCB CONN S 5 PIN 12 J302 EX07N48209 PCB CONN S 10 PIN 13 J301 S...

Page 20: ... 19 TR 127GK DX DISPLAY PCB EPT092930Z COMPONENT SIDE COMPONENT SIDE COPPER SIDE ...

Page 21: ...T TR 127GK DX DISPLAY P C B ITEM REFERENCE NUMBER RANGER PART NUMBER DESCRIPTION 1 EPT012930Z DISPLAY PCB 2 D201 EX01Y40004 LED 3mm RED GREEN 3 LED DISPLAY EX03N40016 LED DISPLAY GREEN 4 D202 EX01N40140 LED 3mm RED ...

Page 22: ... 21 TR 127GK DX MAIN PCB EPT012910A COMPONENTS SIDE ...

Page 23: ... 22 TR 127GK DX MAIN PCB EPT012910A COPPER SIDE ...

Page 24: ...15L 150PF 50WV C4 5 CC0502015L 200PF 50WV C27 CC0502215L 220PF 50WV C73 81 170 CC0504715L 470PF 50WV C6 CC0506815L 680PF 50WV C110 CC0503915G 390PF 50WV C109 CC0505615G 560PF 50WV C94 CC0500301A 3PF 50WV C132 CC0500602A 6PF 50WV C107 129 168 CC0501004A 10PF 50WV C22 CC0501504A 15PF 50WV C92 CC0502704A 27PF 50WV C93 CC0503304A 33PF 50WV C56 101 CC0504704A 47PF 50WV C108 167 CC0506804A 68PF 50WV C57...

Page 25: ... ECSPG18000 SPRING COIL L12 13 ECSPG18003 SPRING COIL L16 ECBAD18504 BEAD COIL L19 ECBAD18520 BEAD COIL L31 ECBAD18526 BEAD COIL T1 ECCHK16294 CHOKE COIL T2 ECCHK16004 CHOKE COIL VR1 4 RE50100066 S F R 500Ω 3P VR2 RE20300030 S F R 20KΩ L VR3 RE10400079 S F R 100KΩ KVSF6 637A VR5 RE10300078 S F R 10KΩ VR6 RE10200072 S F R 1K Ω L VC1 CV050200AZ TRIMMER C 20PF 5Q B ECBAD18582 BEAD COIL RELAY EX05N408...

Page 26: ...TR 127GK DX SCHEMATIC DIAGRAM ...

Page 27: ...0016 RV50203574 RV10203584 42 44 45 43 40 41 39 RV20303575 EX01N40004 JS053006MN QT7799010A JN263035ZS 34 36 37 35 33 32 31 JS053008MB EX06T40007 MT1200110M JS013006MV SCREW M3X6 VR 1 KB RF GAIN VR 5 KB SWR CAL VR 20 KB CLARIFY LED DISPLAY GREEN LED RED 3 MM LED RED GREEN 3 MM M2 6X6 SCREW RUBBER COVER M3X6 M3X6 M3X8 SCREW BACK PLATE SCREW DC SOCKET SCREW M3 NUT MT240N060X EPT91V130Z MT1200021K MT...

Page 28: ...RV50203574 RV10203584 42 44 45 43 40 41 39 RV20303575 EX01N40004 JS053006MN QT7799010A JN263035ZS 34 36 37 35 33 32 31 JS053008MB EX06T40007 MT1200110M JS013006MV SCREW M3X6 VR 1 KB RF GAIN VR 5 KB SWR CAL VR 20 KB CLARIFY LED DISPLAY GREEN LED RED 3 MM LED RED GREEN 3 MM M2 6X6 SCREW RUBBER COVER M3X6 M3X6 M3X8 SCREW BACK PLATE SCREW DC SOCKET SCREW M3 NUT MT240N060X EPT91V130Z MT1200021K MT12000...

Page 29: ...AT0127040A COPYRIGHT 2004 Ranger Communications Inc Communications Inc ...

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