Cobra 18WX STII Service Manual
ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08
ALIGNMENT PROCEDURE
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MODEL: 18WX ST II
REVISION: 00
DATE : AUGUST 09, 2000
PREPARED BY:_____________
CHECKED BY: ____________
APPROVED BY: ____________
TOTAL PAGES:
Page: 1 OF 6 Print date: 06-4-10
ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08
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 Ω
1.4. ANTENNA IMPEDANCE: CB/WX 50 Ω
1.5. STANDARD REF. MODULATION: CB 30% (AM)
WX
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 27.065 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
Page: 2 OF 6 Print date: 06-4-10
3KHz (FM)
±
ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08
Meter loading D.U.T.
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
Distortion AC
Meter Voltmeter
B. RX test equipment setup:
SINAD Meter RF Signal Power
Generator Supply
Distortion 8 ohm 18WS2
Oscilloscope
Note: D.U.T. = device under test
Page: 3 OF 6 Print date: 06-4-10
ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08
meter to TP1
2. Set CB RX mode: CH1.
RF level: 1mV.
ll be more
2.0 ALIGNMENT
2.1 LOCAL FREQ. ALIGNMENT
TEST ITEM TEST CONDITION & PROCEDURE
1. VCO Frequency
Connect a 5pf capacitor to TP7.
Set CB mode RX CH19.
2. 10.245MHz frequency Connect a 5pf capacitor to TP8.
Set CB mode RX CH19.
2.2 VCO ALIGNMENT
TEST ITEM TEST CONDITION & PROCEDURE
1. CB VCO Voltage 1. Connect a digital multi-
3. Set CB TX mode
2. WX VCO Voltage
1. Connect a digital multi-meter to TP1
2. Set WX mode CH08.
2.3 WX RECEIVER
TEST ITEM TEST CONDITION & PROCEDURE
PURPOSE
Adjust
MHz at the frequency counter.
Adjust
MHz at the frequency
counter.
VC1
VC2
FOR 16.485
FOR 10.245
PURPOSE
Adjust
L11
for 1.0 ± 0.1 V.
Check CH40 ≤ 4.5V.
Adjust
L1
FOR 1.5 ± 0.1V.
Check CH1 0 ≤ 3.0V.
PURPOSE
1. Audio output level
2. WX sensitivity
1. Set WX mode, CH3.
2. Output of signal generator thru a 0.01µF
to TP3.
3. RF Gen. set 10.7MHz, Fmod= 1KHz,
Dev.= ± 3KHz,
4.Set volume control to middle position.
1.Output of signal generator to antenna
input terminal.
2. RF Gen. set 162.475MHz, Fmod= 1KHz,
Dev.= ± 3KHz, RF level: 1µV.
3. WX set CH3.
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 sha
than 3 Watts.
1. Adjust
2. Repeat as needed.
L4
more than 12dB at the
SINAD meter.
Check all channels sens.
must met D.T.S.
and
L3
for
Page: 4 OF 6 Print date: 06-4-10
ALIGNMENT PROCEDURE OF 18WS2 REVISION: 00 ENG-18WS2-08
3. RF Gen. set 27.185 MHz , Fmod= 1KHz,
Increase RF level by 30dB.
2. RF Gen. set 27.185MHz,30% modulation
2.4 CB Receiver Alignment
TEST ITEM TEST CONDITION & PROCEDURE
1. Audio output level
2. RX sensitivity
3. SQUELCH control
( Tight Squelch )
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. Set normal band CH19.
2. Output of signal generator to antenna
input terminal.
3. RF Gen. set 27.185MHz, fm: 1kHz,
AM= 30%, RF level: 1µV.
1. Set normal band CH19.
2.Output of signal generator to the antenna
input terminal.
AM= 30%, RF level: 2500 µV.
4. Rotate the Squelch control to fully
clockwise position
PURPOSE
1. Adjust L8 and
maximum audio 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.
1. Adjust
2. Repeat as needed.
1. Slowly turn
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.
L5, L6
for more than 10dB S/N
ratio.
Check CH1 and CH40.
L23
VR5
and
for
L10
to a
4. Signal meter display
5. Sound Tracker
( ST must be on )
a) S/N
b) Audio Gain
1. Set normal band CH19.
2. Output of signal generator to antenna
input terminal.
RF Gen. set 27.185MHz, no modulation,
RF level: 100 µV.
1. Set normal band CH19.
3. S/N @ RF level 1.0uV
@ RF level 1000uV
4. Audio Gain @ 100uV 50% Mod.
1. Adjust
2.
1. S/N: 1.0uV ≥ 15dB.
1000uV ≥ 50dB.
2. ST audio output change
VR1
for “9”
displayed on the signal
meter of
The signal meter should be
displayed at “+30” position.
2-8dB from OFF to ON.
LED
panel.
Page: 5 OF 6 Print date: 06-4-10
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