Service_Manual_Cobra_18WX_STII_EMG.pdf

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1、ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08 Page: 1 OF 6 Print date: 06-4-10 ALIGNMENT PROCEDURE MODEL: 18WX ST II REVISION: 00 DATE : AUGUST 09, 2000 PREPARED BY:_ CHECKED BY: _ APPROVED BY: _ TOTAL PAGES: Downloaded from www.cbradio.nl ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2

2、-08 Page: 2 OF 6 Print date: 06-4-10 18WS2 ALIGNMENT INSTRUCTION 1.0 TEST CONDITION: 1.1. STANDARD DC POWER: EXT.DC 13.8VDC 1.2. MEASUREMENT CHANNEL: CB CH19 (27.185MHz) WX CH3 (162.475MHz) 1.3. STANDARD AUDIO LOADING: CB/WX 8 1.4. ANTENNA IMPEDANCE: CB/WX 50 1.5. STANDARD REF. MODULATION: CB 30% (A

3、M) WX 3KHz (FM) 1.6. STANDARD REF. AUDIO OUTPUT: CB/WX 0.5W 1.7. FREQUENCY TABLE CB BAND WX BAND CH NO. FREQ. (MHz) CH NO. FREQ. (MHz) 01 26.965 1 162.550 02 26.975 2 162.400 03 26.985 3 162.475 04 27.005 4 162.425 05 27.015 5 162.450 06 27.025 6 162.500 07 27.035 7 162.525 08 27.055 8 161.650 09 27

4、.065 9 161.775 10 27.075 10 163.275 11 27.085 12 27.105 13 27.115 14 27.125 15 27.135 16 27.155 17 27.165 18 27.175 19 27.185 20 27.205 21 27.215 22 27.225 23 27.255 24 27.235 25 27.245 26 27.265 27 27.275 28 27.285 29 27.295 30 27.305 31 27.315 32 27.325 33 27.335 34 27.345 35 27.355 36 27.365 37 2

5、7.375 38 27.385 39 27.395 40 27.405 ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08 Page: 3 OF 6 Print date: 06-4-10 1.8. TEST EQUIPMENT SETUP AS BELOW: A. TX test equipment setup: Spectrum Power Analyzer Supply Modulation Wattmeter 18WS2 Meter D.U.T. Oscilloscope Frequency Audio Gen. Counter

6、 Distortion AC Meter Voltmeter B. RX test equipment setup: SINAD Meter RF Signal Power Generator Supply Distortion 8 ohm 18WS2 Meter loading D.U.T. Oscilloscope Note: D.U.T. = device under test ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08 Page: 4 OF 6 Print date: 06-4-10 2.0 ALIGNMENT 2.1

7、LOCAL FREQ. ALIGNMENT TEST ITEM TEST CONDITION & PROCEDURE PURPOSE 1. VCO Frequency Connect a 5pf capacitor to TP7. Set CB mode RX CH19. Adjust VC1 FOR 16.485 MHz at the frequency counter. 2. 10.245MHz frequency Connect a 5pf capacitor to TP8. Set CB mode RX CH19. Adjust VC2 FOR 10.245 MHz at the fr

8、equency counter. 2.2 VCO ALIGNMENT TEST ITEM TEST CONDITION & PROCEDURE PURPOSE 1. CB VCO Voltage 1. Connect a digital multi-meter to TP1 2. Set CB RX mode: CH1. Adjust L11 for 1.0 0.1 V. 3. Set CB TX mode Check CH40 4.5V. 2. WX VCO Voltage 1. Connect a digital multi-meter to TP1 2. Set WX mode CH08

9、. Adjust L1 FOR 1.5 0.1V. Check CH1 0 3.0V. 2.3 WX RECEIVER TEST ITEM TEST CONDITION & PROCEDURE PURPOSE 1. Audio output level 1. Set WX mode, CH3. 2. Output of signal generator thru a 0.01F to TP3. 3. RF Gen. set 10.7MHz, Fmod= 1KHz, Dev.= 3KHz, RF level: 1mV. 4.Set volume control to middle positio

10、n. 1. Adjust L9 for maximum audio output & minimum distortion at the distortion meter.(Distortion less than 8% ) 2. Set volume control to maximum position, audio power output shall be more than 3 Watts. 2. WX sensitivity 1.Output of signal generator to antenna input terminal. 2. RF Gen. set 162.475M

11、Hz, Fmod= 1KHz, Dev.= 3KHz, RF level: 1V. 3. WX set CH3. 1. Adjust L4 and L3 for more than 12dB at the SINAD meter. 2. Repeat as needed. Check all channels sens. must met D.T.S. ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08 Page: 5 OF 6 Print date: 06-4-10 2.4 CB Receiver Alignment TEST ITE

12、M TEST CONDITION & PROCEDURE PURPOSE 1. Audio output level 1. CB RX mode. 2. ST to OFF 3. Output of signal generator thru 0.01uF to TP3. 4. RF Gen. set 10.7MHz, Fmod= 1KHz, AM= 30%, level: 1mV. 5. Set Volume control to middle position. 6. Set Squelch to minimum. 1. Adjust L8 and L23 for maximum audi

13、o output & minimum distortion at the distortion meter.( Distortion less than 5% ) 2. Set volume control to maximum position, audio power output shall be more than 3 Watts. 2. RX sensitivity 1. Set normal band CH19. 2. Output of signal generator to antenna input terminal. 3. RF Gen. set 27.185MHz, fm

14、: 1kHz, AM= 30%, RF level: 1V. 1. Adjust L5, L6 and L10 for more than 10dB S/N ratio. 2. Repeat as needed. Check CH1 and CH40. 3. SQUELCH control ( Tight Squelch ) 1. Set normal band CH19. 2.Output of signal generator to the antenna input terminal. 3. RF Gen. set 27.185 MHz , Fmod= 1KHz, AM= 30%, RF

15、 level: 2500 V. 4. Rotate the Squelch control to fully clockwise position 1. Slowly turn VR5 to a position that the audio output waveform at the oscilloscope just appears from no output. 2. Must open at 4000uV. 3. Must not open at 800uV. 4. Signal meter display 1. Set normal band CH19. 2. Output of

16、signal generator to antenna input terminal. RF Gen. set 27.185MHz, no modulation, RF level: 100 V. 1. Adjust VR1 for “9” displayed on the signal meter of LED panel. 2. Increase RF level by 30dB. The signal meter should be displayed at “+30” position. 5. Sound Tracker ( ST must be on ) a) S/N b) Audi

17、o Gain 1. Set normal band CH19. 2. RF Gen. set 27.185MHz,30% modulation 3. S/N RF level 1.0uV RF level 1000uV 4. Audio Gain 100uV 50% Mod. 1. S/N: 1.0uV 15dB. 1000uV 50dB. 2. ST audio output change 2-8dB from OFF to ON. ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08 Page: 6 OF 6 Print date:

18、06-4-10 2.5 CB Transmitter Alignment TEST ITEM TEST CONDITION & PROCEDURE PURPOSE 1. TP4 Alignment 1. Channel set normal band CH 19. 2. Set TX mode. Connect the TP4 (IC8 pin9) thru a 10pF capacitor to the oscilloscope. 1. Adjust L7 (double tuned IFT) for maximum RF output waveform at the scope. (Fre

19、q. = 27.185MHz) 2. Repeat as needed. 2. TX Carrier output power 1. Channel set normal band CH 19. 2. Set TX mode. 3. Connect an RF wattmeter to the antenna socket. 1. AdjustL21,L20 and L17 for 4.0 watts RF output power. 2. Check TX CH1 and CH40 should meet D.T.S. 3.TX Carrier frequency detector. 1.

20、Channel set CH 19. 2. Set TX mode. TX Frequency for 27.185MHz 300Hz at the frequency counter. 4. TX Signal meter 1. Connect an RF wattmeter to the antenna socket. 2. No modulation. 3. Set TX output power for 3watts. Adjust VR6 for “4” displayed at the TX signal meter of the LED panel. (red LED) 5. M

21、AXIMUM Modulation (AMC control) 1. Set TX mode. Output of AF generator to MIC jack, 1000Hz, 5 mV . 1. Adjust VR2 for 89-91% modulation. 2. Distortion less than 8.0% at 80% modulation. 3. Check CH1,CH40. 6. TX 2nd harmonics 1. Connect an RF wattmeter to the antenna socket. Adjust L14 for less than -6

22、0dB at spectrum analyzer. 7. Occupied band width, ( OBW ) 1. Set TX High power mode 2. Set modulation frequency 2500 Hz. The frequency spectrum of the harmonics should be at least 2 dB better than the limits of the FCC specification. Alignment Points 18 18ws2mp-E1(change 2003).sch-1 - Wed Jul 02 15:11:40 2008 18 WX ST II with TDA2003 Audio Amp