Giant Cobra CB 29 LX LE Manual

GIANT ELECTRONICS LTD.
29-LX ALIGNMENT REVISION: 00 ENG-29-LX-08
www.radioaficion.com
ALIGNMENT PROCEDURE
For Cobra model CB 29 LX LE (Giant: 29-LX)
MODEL: CB 29 LX LE
REVISION: ___V01______
DATE : _2010-6-22___
PREPARED BY:___
CHECKED BY: ____________
APPROVED BY: ____________
Total page: 5 pages
Page: 1 / 6 print date: 10-6-22

29-LX ALIGNMENT REVISION: 00 ENG-29-LX-08
CB 29-LX ALIGNMENT INSTRUCTION
1.0 TEST CONDITION:
1.1. STANDARD DC POWER: EXT.DC 13.8VDC
1.2. MEASUREMENT CHANNEL: CB CH19 / WX CH5
1.3. STANDARD AUDIO LOADING: CB 8 
1.4. ANTENNA IMPEDANCE: CB 50 
1.5. STANDARD REF. MODULATION: CB 30% (AM) / WX +/- 3KHz (FM)
1.6. STANDARD REF. AUDIO OUTPUT: CB 0.5W
1.7. FREQUENCY TABLE:
CB Section: WX Section:
CH NO. FREQ. (MHz) CH No. FREQ (MHz)
1 26.965 1 162.550
2 26.975 2 162.400
3 26.985 3 162.475
4 27.005 4 162.425
5 27.015 5 162.450
6 27.025 6 162.500
7 27.035 7 162.525
8 27.055 8 161.650
9 27.065 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 27.375
38 27.385
39 27.395
40 27.405
Above red color channels are the definition test model channel for alignment.
Page: 2 / 6 print date: 10-6-22

29-LX ALIGNMENT REVISION: 00 ENG-29-LX-08
1.8. TEST EQUIPMENT SETUP AS BELOW:
A. TX test equipment setup:
Spectrum Power
Analyzer Supply
Modulation Wattmeter CB29LTD
Meter D.U.T.
Oscilloscope Frequency Audio Gen.
Counter
Distortion AC
Meter Voltmeter
B. RX test equipment setup:
SINAD Meter RF Signal Power
Generator Supply
Distortion 8 ohm CB29LTD
Meter loading D.U.T.
Oscilloscope Note: D.U.T. = device under test
Page: 3 / 6 print date: 10-6-22

29-LX ALIGNMENT REVISION: 00 ENG-29-LX-08
2.0 Ali gnment of P.L.L. portion of CB and WX.
2.1 Equipment required:
A: Oscilloscope
B: DC voltage meter .
2.2 Alignment procedure:
TEST ITEM TEST CONDITION & PROCEDURE PURPOSE
1. CB TX VCO voltage
@ CH40
1. CB TP3 OUTPUT
@ TX mode
2. WX VCO voltage
@ CH8 / CH10
Connect the DC volt. Meter to the
junction point of R59 and R60.
Connect the oscilloscope to the junction
point of R6 and JP14.
Connect the DC volt. Meter to the TP601
Adjust L19to obtain approximately
3.0V 0.2V reading.
Adjust L20 for maximum output on
the oscilloscope.
1. Adjust L605 to obtain approx 1.5 0.1V
@CH8 (162.650MHz)
2. Checking the CH10 the volt ≤3.0V
3.0 Alignment of CB receiver portion.
3.1 Equipment required:
A: Signal generator
B: AC voltmeter.
C: Oscilloscope.
D: Dummy load ( 8 ohm, 5 watts, resistive.) E:
DC power supply ( 13.8 v. 2Amp.)
3.2 Alignment procedure:
TEST ITEM
1. AUDIO OUTPUT
2. RX Sensitivity
3. NB
4.Tight Squelch
5. “S-9”and +30 meter
indicator.
6. PA output RF Level
@1mV, 30% Mod.
TEST CONDITION & PROCEDURE
1. Set channel 19.
2. Set the S.G. on 27.185MHz with 1KHz,
30% mod. and 1mV output level.
3. Set NB/OFF SW to OFF, Squelch to min.
( CCW), CB/WX/PA to CB, ANL SW to
CB/ANL, RF GAIN to max. Volume
approximately Center.
1. Same as above step 1 and 3.
2. Set the S.G. on 27.185MHz with 1KHz,
30% mod. RF output level 1.0uV.
1. Set NB/OFF SW to NB.
2. Set the level of S.G. to 1.0uV.
3. Noise generator to on.
4. Adjusted then revert item 1 setup.
1. Set Squelch volume to maximum ( CW ).
2. Set the level of S.G. to 1500uV.
3. Adjusted then revert item 1 setup.
1. Set the level of S.G. to 100uV.
2. Set the level of S.G. to 3.16mV.
1. Set CB/WX/PA to PA function
PURPOSE
1. AdjustL1,2,3,4,5,6& 7for
maximum audio output & minimum
distortion on the distortion meter.
1. Adjust L1,2,3,4,5,6&7for more
than 12dB to the SINAD meter.
2. Repeat as needed.
3. Set RF S.G. output level 0.4uV, the adj.
VR2to 2V on the AC volt meter.
1. Turn the volume to obtain 2V reading
on AC voltmeter.
2. Adjust L1 for minimum reading on AC
volt meter.
1. Slowly turn VR4to a position that the
audio output waveform at the scope
just appears from no output.
1. Adjust VR1 for “S-9”reading on
The LCD meter.
2. Check the bars up to +30.
1. Checking the audio output need more
than 3.5W @10%THD
Page: 4 / 6 print date: 10-6-22

29-LX ALIGNMENT REVISION: 00 ENG-29-LX-08
4. Alignment of WX receiver portion.
4.0 Equipment required:
A: Signal generator
B: AC voltmeter.
C: Oscilloscope.
D: Dummy load ( 8 ohm, 5 watts, resistive.)
E: DC power supply ( 13.8 v. 2Amp.)
4.1 Alignment procedure:
TEST ITEM TEST CONDITION & PROCEDURE
1. AUDIO OUTPUT 1. Set channel 5. RF connect to the TP4.
2. Set the S.G. on 10.7MHz with 1KHz,
±3KHz mod. and 1mV output level.
3. CB/WX/PA to WX. Volume set
approximately Center.
2. RX Sensitivity 1. Set RF output connect to the TP1.
2. Set the S.G. on 162.450MHz with 1KHz,
±3KHz mod. RF output level 1.0uV.
3. Tone Decoder Sens. 1. Set unit off, RF output @1.2uV, AF
(Turn-on): @±4KHz @1050Hz, RF Freq @162.450MHz
PURPOSE
1. Adjust L604for maximum
2. audio output & minimum distortion on
the distortion meter.
1. Adjust L603& L602for more
than 12dB to the SINAD meter.
Repeat as needed.
1. The unit will turn on automatically when
RF signal open.
5. Alignment of Transmitter portion.
5.1 Equipment Required:
A: VTVM ( full scale: 1V DC with RF probe). B:
RF power meter.
C: Spectrum analyzers.
D: Frequency counter.
E: DC power supply. (13.8VDC / 3AMPs)
F: 50 ohm load and attenuator.
G: Oscilloscope.
H: AF generator.
5.2 Alignment procedure:
TEST ITEM TEST CONDITION & PROCEDURE PURPOSE
1. TP4 output 1. Connect the oscilloscope to the TP4. Adjust L20, 21, 17for maximum
2. Set TX mode , Channel 19. output on the oscilloscope.
2. TX power 1. Set TX Channel 19. 1. Adjust L17,14for maximum
output on the RF power meter.
2. Turn L14to obtain 4.0W on the RF
meter reading.
3. TX carrier frequency 1. Set TX Channel 19.
4. Second harmonic 1. Set TX Channel 19.
5. “P4”indicator 1. Set TX Channel 19.
6. Modulation 1. Set TX Channel 19.
2. AF GEN. Output 30mV.
7. Talk-back 1. Set unit in TX mode with 90% Mod.
1. Adjust L24to obtain 27.185MHz on
the frequency counter.
1. Adjust L11for a min. 2nd harmonic
( 54MHz) output on the Spectrum anal.
1. Adjust VR5 for “P4”display at the TX
Signal meter of the LCD meter.
1. Adjust VR4for 90% on the
modulation Meter.
1. The speaker can be heard the tone when
Talkback turn on.
Page: 5 / 6 print date: 10-6-22

29-LX ALIGNMENT REVISION: 00 ENG-29-LX-08
5. LCD & Backlight Checking
5.1 There are four colors in the backlighting operation, they are Red, Green, Blue and Amber.
5.2 The LCD drawing as following display in dot matrix and icons.
5.3 Please refer to the next procedure of item 6 let the UUT into the test mode to checking the LCD and
backlight performance.
6. Test Mode Operating Method
6.1 Press and hold the key of “CB/WX/PA ”and “Enter ”at the same time then turn the DC power on
to enter the test mode for CB and WX channel.
6.2 In CB mode, turn the channel selector by clockwise for CH1 (26.965MHz) - CH19 (27.185MHz) -
CH22 (27.225MHz) - CH40 (27.405MHz).
6.3 In WX mode, turn the channel selector by clockwise for CH8 (161.650MHz) - CH5 (162.450MHz)
- CH10 (163.275MHz).
6.4 Press the “NB/ANL ”key for LCD display scanning
6.5 Press the “SWR/CAL ”key for backlight Amber color turn on; Press the “MEM SCAN ”key for
backlight RED color turn on; Press the “CH9/19”key for backlight Green color turn on; Press the
“DIM/ESC ”key for backlight Blue color turn on.
7. Radio Check
7.1 Battery Check: In radio check menu mode, select “1ST Test”- Battery Level.
BATTERY VOLTAGE
PASS: 11.2VDC - 15.5VDC
FAIL HIGH: 15.5V - 16.5V
FAIL LOW: 10V - 11.2V
7.2 RF Power Check: In radio check menu mode, select “2nd Test”- RF POWER OUTPUT.
RF POWER OUTPUT
PASS: TX Power more than 3.0W @50 ohm loading
FAIL: TX Power less than 3.0W @50 ohm loading
7.3 Antenna Mismatch Warning Check: In radio check menu mode, select “3rd Test”- CHECK
ANTENNA.
PASS: @50 ohm dummy loaded
FAIL: Antenna open or Shorted.
Page: 6 / 6 print date: 10-6-22