Realistic PRO-2021 - Appendix; Circuit Revision; VHF-MID Band VCO Alignment; VHF-MID Band RF AMP Alignment

APPENDIX
VHF-MID Band Alignment for European/Australian models
CIRCUIT REVISION
1. The following parts should be changed.
Low band ` Mid band Low band Mid band
Not used 18pF
Not used 56 pF
BB329 Not used
Not used BB329
Not used 4LN-092
GR-N5341 GR-N791
GR-N5341 GR-N791
Not used 47k9
0.0014 F 56pF 21739 21882
0.0014 F | b6pF
0.0014 F | 100pF
56pF 22pF
22pF 10pF
2. 045 changed to [C11 Pin 66 from IC11 Pin 65.
3. R112 changed to ІС8 Pin 5 from ІС8 Pin 4.
vco ALIGNMENT
Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
Connect а DC SSVM to TP5 and ground.
Program CH1, 2 and 3 as follows:
CH1 (68 MHz), CH2 (78 MHz), CH3 (88 MHz)
Select channel 3 (88 MHz) and adjust TC3 for 11.0V on the DC SSVM.
Select channel 1 (68 MHz) and adjust T7 for 1.5V on the DC SSVM.
Repeat steps 3 and 4 until no improvement is observed.
The DC SSVM should show as below.
68 MHz Voltage of TP5 1.5V
78 MHz Voltage of TP5 4.7V
88 MHz Voltage of TP5 11.0V
RF AMP ALIGNMENT
Step 1:
Step 2:
Step 3:
Step 4:
Connect instruments as shown below.
ANT.
JACK
SCOPE
TP1
UNIT |Р!󰾰 لم
UNDER TEST [- o]󰾰 1—
m
т
|󰾰
мон !
SWEEP MM | |
СЕМЕВАТОВ
۰
“ა
>
'
i 68MHz ~ 88MHz >. |
7” т
سا
Program
68
MHz
(CH1),
78
MHz
(CH2),
88
MHz
(CH3).
Select
Channel
1
(68
MHz)
and
adjust
T3
and
T6
for
maximum
RF
waveform.
Check
the
Channels
1
~
3
one
by
one
for
maximum
RF
waveform.
Slight
deviation
as
shown
below
is
acceptable.
RESPONSE (dB)
FREQ (MHz)
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