background image

 

               

CB Radio

 
 
 
 
 
 
 

Model DX

 

979

 

                                                                                                                                               

Service Manual

 

 
 
 
 

 

 
 
 

Copyright Reserved 

 

Summary of Contents for DX 979

Page 1: ...CB Radio Model DX 979 Service Manual Copyright Reserved...

Page 2: ...phones 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 A...

Page 3: ...2500 Hz Antenna Impedance 50 Ohms Output Indicators Meter shows incoming signal strength RF output power SWR and AM Modulation level Transmit LED glows red when transmitter is in operation 1 2 RECEIVE...

Page 4: ...OL This knob is used to eliminate background noise being heard through the receiver which can be disturbing when no transmissions are being heard through the receiver To use this feature turn the knob...

Page 5: ...ows tuning of the receive frequency above or below the channel frequency by up to 1 0KHz Although this control is intended primarily to tune in SSB signals it may be used to optimize AM signals 14 SWR...

Page 6: ...er 8 ohms 4W to this jack 4 EXT SP This jack accepts a 4 to 8 ohm 5 watt external speaker When the external speaker is connected to this jack the built in speaker will be disabled 5 F C This jack is u...

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...

Page 8: ...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 SQUE...

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 function...

Page 10: ...and into the front end pre amp Q17 The RF signal is fed into the mixer circuit of Q18 Q19 and then into the AM IF section of the receiver The signal is then detected by the AM detector and then fed to...

Page 11: ...10...

Page 12: ...ort PCB from TP7 TP8 and TP9 Set radio to CH 1 AM RX mode Connect Multi meter to TP2 L14 2 5 VDC 0 1 Set CLARIFIER Control to 12 o clock Connect Oscilloscope to TP3 L15 Adjust for max Connect Frequenc...

Page 13: ...to microphone VR13 11 5 W SSB Carrier Balance Set radio to CH 19 USB TX mode Set MIC GAIN fully counter clockwise Connect Oscilloscope to antenna connector VR6 Spurious Emission to Minimum AM TX High...

Page 14: ...dB LSB Sensitivity Set radio to CH19 LSB RX mode Set VOL Control Fully Clockwise RF SG setting 27 184 MHz 0 5uV Mod off L11 L12 Audio Output 2V S N 10dB NB Adjust Set radio to CH 18 AM RX mode RF SG s...

Page 15: ...14 Figure 4 1 Transmitter test setup Figure 4 2 Receiver test setup...

Page 16: ...DJUSTMENT LOCATION DRIVER BIAS FINAL BIAS RF METER ALC AM MOD AM LOW POWER APC AM HI POWER AM MOD METER SSB S METER AM S METER SSB SQUELCH AM SQUELCH TX OFFSET CARRIER BALANCE 10 240 MHz ADJUST AM LOW...

Page 17: ...pection 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...

Page 18: ...17 DX 979 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 19: ...18 DX 979 ROTARY SWITCH PCB EPT092920Z SMD COPPER SIDE COMPONENT SIDE...

Page 20: ...C201 C202 CK1104AB5X CHIP C 0 1uF 50WV 10 D201 D202 D203 D204 D205 D206 D207 D208 D209 D210 D211 D212 D13 D214 D215 D216 D 217 D218 D219 D220 D 226 D227 D228 EDSS00355Y DIODE S M D 1SS355 11 D221 D222...

Page 21: ...20 DX 979 DISPLAY PCB EPT092930Z COMPONENT SIDE COMPONENT SIDE COPPER SIDE...

Page 22: ...930Z DISPLAY PCB 2 R301 R302 R303 R304 R305 R306 R307 RCY016814Z CHIP F R 680 0 1W 3 R308 RCY011024Z CHIP F R 1K 0 1W 4 D301 D302 EDSS00355Y DIODE 1SS355 5 LED201 LED202 EX01Y40114 LED LAMPS KM 23ESGC...

Page 23: ...22 DX 979 DIM PWR MIC RF VOL SQ CONTROL VR PCB EPT092940Z COMPONENT SIDE COPPER SIDE...

Page 24: ...2Y0128 CHIP F R 1K TMC3KJ 7 L402 YCTLI5653C CHOKE COIL 5 6uH 8 L401 YCBAD18581 BEAD FERRITE COIL WB 403025 9 Q902 TYDTA124EA T R DTA124EUAT106 10 VR401 VOL SQ OFF RV50303522 V R 50KB 50KA W SW 11 MIC...

Page 25: ...SIDE PART LIST DX 979 TALKBACK CLARIFIER CONTROL VR P C B ITEM REFERENCE NUMBER RANGER PART NUMBER DESCRIPTION 1 EPT092950Z TB PCB 2 VR501 CLARIFIER RV10203528 VR 1KB 3 VR502 TALKBACK RV20203558 VR 2...

Page 26: ...25 DX 979 METER PCB EPT092961Z COMPONENT SIDE COPPER SIDE COPPER SIDE SMD...

Page 27: ...0WV 12 C619 613 614 615 616 CK5105AB7R CHIP C 1uF 16WV 13 C621 CK1473AB5X CHIP C 0 047uF 50WV 14 C617 CK2474AB7R CHIP C 0 47uF 25WV 15 C605 611 CK5475AA7R CHIP C 4 7uF 16WV 16 C622 CTY161066A T C 10uF...

Page 28: ...W 5 R2 RCY013314Z 330 OHM 0 1W 6 R5 R11 RCY011024Z 1K OHM 0 1W 7 R10 R12 RCY012224Z 2 2K OHM 0 1W 8 R7 C5 RCY011034Z 10K OHM 0 1W 9 C7 CK1059AB1A 0 5PF 50WV 10 C6 CK1030AB1A 3PF 50WV 11 C3 C4 CK2104AB...

Page 29: ...28 DX 979 MAIN PCB EPT092913Z COMPONENTS SIDE...

Page 30: ...29 DX 979 MAIN PCB EPT092913Z COPPER SIDE...

Page 31: ...1 5M 1 16W R124 RCP161064Z 10M 1 16W R244 RCP141514Z 150 1 4W R239 RCP121034Z 10K 1 2W C8 CC0508204L 82PF 50WV C4 CC0501015L 100PF 50WV C137 CC0501515L 150PF 50WV C31 136 CC0502715L 270PF 50WV C11 14...

Page 32: ...T12258 I F T L40 ECIFT12262 I F T L14 ECIFT12263 I F T L43 ECIFT12265 I F T C306 L43 PIN4 6 CK1820AA4A 82PF 50WV L5 ECIFT12253 I F T L7 42 ECIFT12440 I F T L8 ECIFT12492 I F T L48 ECCHK16096 470UH L50...

Page 33: ...DX 979 SCHEMATIC DIAGRAM CONTROL PCB...

Page 34: ...DX 979 SCHEMATIC DIAGRAM MAIN PCB...

Page 35: ...DX 979 MECHANICAL PART DX 979 EXPLODE DRAWING...

Page 36: ...Any updates or corrections to this Service Manual will be included in the Tech Support section of our website at www GalaxyRadios com UPDATES CORRECTIONS...

Page 37: ...ber RAN This RAN may be obtained from our website or by calling our Service Department at 760 480 8800 between 10 00 AM and 4 00 PM Pacific Time The RAN must be written below your return address on th...

Page 38: ...ATS979010A July 2003...

Reviews: