PRESIDENT JOHNSON II User manual

JOHNSON II
SERVICE MANUAL

- TECNNICAL CHARACTERITICS
1 - GENERAL:
- Multiconfiguration (E, d, EU, EC, U, PL)
-E ⇒40 channels AM/FM 4W (from 26,965Mhz to 27,405Mhz)
-d ⇒80 channels FM 4W (from 26,565Mhz to 27,405Mhz)
40 channels AM 1W (from 26,965Mhz to 27,405Mhz)
-EU ⇒40 channels FM 4W/AM 1W (from 26,965Mhz to 27,405Mhz)
-EC ⇒40 channels FM 4W (from 26,965Mhz to 27,405Mhz)
-U ⇒40 channels FM 4W (from 26,965Mhz to 27,405Mhz)
40 channels FM 4W (from 27,60125Mhz to 27,99125Mhz)
-PL ⇒40 channels AM/FM 4W (from 26,960Mhz to 27,400Mhz)
-Channel step
-10KHz
-Class of emission
-AM(A3E)/FM(F3E)
- Power supply
-13,2V (from10,8V to 15,6V)
- Antenna impedance
- 50Ω
- Dimensions(in mm)
- 170(W)x150(D)x52(H)
- Weight
- 1Kg
2 - TRANSMISSION:
- Frequency allowance
-±300Hz
- Transmission interference
-Inferior to 4nW(-54dBm)
- Audio frequency response
-From 300Hz to 3kHz in AM/FM
- Emitted power in the adjacent channel
-Inferior to 20µW
- Microphone sensitivity
-Inferior to 10mV
-Current drain
-2A(in transmission mode with modulation)
- Modulated signal distortion
-Inferior to 2%

3 - RECEPTION:
-Maximum sensitivity at 20dB sinad
-0,5µV(-113dBm) AM/FM
-Audio frequency response
-From 300Hz to 3kHz in AM/FM
-Adjacent channel selectivity
-Superior to 60dB
-Frequency image rejection
-Superior to 60dB
-Intermodulation response
-Superior to 54dB
-Maximum audio power
-5W
-Squelch sensitivity
-Threshold 0,2µV(-120dBm)/Tight 1mV(-47dBm)
-Current drain
-400mA nominal/1000mA maximum

ALIGNMENT PROCEDURE
(JOHNSON II)
* VCO/PLL PORTION
- Alignment procedure
- Test points
- Frequencies chart
* TRANSMITTER
- Alignment procedure
- Test points
* RECEIVER
- Alignment procedure
- Test points
Test equipement required
Frequency counter 200 Mhz HF Generator
DCVolmeter BFVolmeter
Distortiometer HFVolmeter
Wattmeter - Dummy load Osilloscope
FM linear detector Load 8 Ω
AF generator Sinad meter
Conditions of Measurements on HF Generator
Reception
AM mode: Level - 107 dBm Frequency 1 KHz with 60% of modulation.
FM mode: Level - 107 dBm Frequency 1 KHz with 1,2KHz of deviation.
Transmission
Frequency1 KHz 30mV.

ALIGNMENT VCO/PLL
1 - Alignment procedure(13,2V;configuration”EU,E,d”)
STEP CONDITION ADJUSTMENT REMARKS OF ADJUSTMENT
1 FM(EU,E)
TX mode
Channel 40
L302 Connect a voltmeter to TP 301,
adjust L302 to reach 2V±0,2V.
2 FM(EU,E)
RX mode
Channel 40
L301 Connect a voltmeter to TP 301,
adjust L301 to reach 2,3V±0,2V.
3 FM(EU,E)
TX/RX mode
Channel 1
Connect a voltmeter to TP 301,and check:
Rx Channel 1=2V±0,2V
Tx Channel 1=1,7V±0,2V
4 FM(EU,E)
RX mode
Channel 20
CT301 Connect a frequency counter to TP302,and
adjust CT301 to reach
37,900MHz.
5 FM(EU,E)
TX/RX mode
Channel 1 to 40
or 1 to 80(d)
Connect a frequency counter to TP302,and
check frequencies.

VCO/PLL ALIGNMENT POINTS
TP302

VCO/PLL ALIGNMENT POINTS
L301
L302
TP301

- FREQUENCY LIST (EU,E,EC)
CH Channels
Frequencies
(MHz)
VCO
Frequencies
(MHz)
1 26,965 37,660
2 26,975 37,670
3 26,985 37,680
4 27,005 37,700
5 27,015 37,710
6 27,025 37,720
7 27,035 37,730
8 27,055 37,750
9 27,065 37,760
10 27,075 37,770
11 27,085 37,780
12 27,105 37,800
13 27,115 37,810
14 27,125 37,820
15 27,135 37,830
16 27,155 37,850
17 27,165 37,860
18 27,175 37,870
19 27,185 37,880
20 27,205 37,900
21 27,215 37,910
22 27,225 37,930
23 27,255 37,950
24 27,235 37,930
25 27,245 37,940
26 27,265 37,960
27 27,275 37,970
28 27,285 37,980
29 27,295 37,990
30 27,305 38,000
31 27,315 38,010
32 27,325 38,020
33 27,335 38,030
34 27,345 38,040
35 27,355 38,050
36 27,365 38,060
37 27,375 38,070
38 27,385 38,080
39 27,395 38,090
40 27,405 38,100

- FREQUENCY LIST (PL)
CH Channels
Frequencies
(MHz)
VCO
Frequencies
(MHz)
1 26,960 37,655
2 26,970 37,665
3 26,980 37,675
4 27,000 37,695
5 27,010 37,705
6 27,020 37,715
7 27,030 37,725
8 27,050 37,745
9 27,060 37,755
10 27,070 37,765
11 27,080 37,775
12 27,100 37,795
13 27,110 37,805
14 27,120 37,815
15 27,130 37,825
16 27,150 37,845
17 27,160 37,855
18 27,170 37,865
19 27,180 37,875
20 27,200 37,895
21 27,210 37,905
22 27,220 37,915
23 27,250 37,945
24 27,230 37,925
25 27,240 37,935
26 27,260 37,955
27 27,270 37,965
28 27,280 37,975
29 27,290 37,985
30 27,300 37,995
31 27,310 38,005
32 27,320 38,015
33 27,330 38,025
34 27,340 38,035
35 27,350 38,045
36 27,360 38,055
37 27,370 38,065
38 27,380 38,075
39 27,390 38,085
40 27,400 38,095

- FREQUENCY LIST (U)
CH
CEPT
Channels
Frequencies
(MHz)
VCO
Frequencies
(MHz)
1 26,965 37,660
2 26,975 37,670
3 26,985 37,680
4 27,005 37,700
5 27,015 37,710
6 27,025 37,720
7 27,035 37,730
8 27,055 37,750
9 27,065 37,760
10 27,075 37,770
11 27,085 37,780
12 27,105 37,800
13 27,115 37,810
14 27,125 37,820
15 27,135 37,830
16 27,155 37,850
17 27,165 37,860
18 27,175 37,870
19 27,185 37,880
20 27,205 37,900
21 27,215 37,910
22 27,225 37,930
23 27,255 37,950
24 27,235 37,930
25 27,245 37,940
26 27,265 37,960
27 27,275 37,970
28 27,285 37,980
29 27,295 37,990
30 27,305 38,000
31 27,315 38,010
32 27,325 38,020
33 27,335 38,030
34 27,345 38,040
35 27,355 38,050
36 27,365 38,060
37 27,375 38,070
38 27,385 38,080
39 27,395 38,090
40 27,405 38,100