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3.5.5. AMP L I TU D E MODU LATO R , COMP E NSAT I O N O F TH E M O D U LAT I O N VO LTAG E
- R elease a l l range buttons
- Press mode button AM/1 k H z; if necessary, release button W O B .
voltage a t resistor 6 3 4 o f u n i t 1 : maximum L F voltage 5 m V p _ p
-
Measure t h e
-
Adjust
the
compensation voltage to < 5 mV with potentiometer 63 1 on u n i t 1 , if necessary.
3.5.6. HF S I G N A L
3.5. 6. 1 . H F ampl itude
- Release a l l buttons
- Termi nate connector H F OUT with 75
- Set H F A M P L I TU D E f u l l y clockwise
-
Press range button 1 -3
- Measure the voltage at output H F OUT: 50 m V ± 1 m V
- Adjust t h e voltage t o nominal with potentiometer 6 1 2 o n u n it 1 , if necessary.
3. 5. 6.
2.
F requency
Check the position of the sca l e pointer
- Set the pointer approx imately to the m iddle of the sca l e
-
H o l d
the largest k n o b o f control F R EQU E N CY with
- Adjust the smaller k nob - aga i nst the resistance of the sl ipping clutch - to the right stop of the sl ipping clutch
- Release the la rge knob and set control F R EQU E NCY to the left stop . The poi nter should n ow be located
on both left pair of marks which a re on the left alongside the sca le; if not, sh :ft the pointer on the scal e cord
accordi ng to 3 . 2 . 5 . 2 . ( mechanical zero point )
- Set the poi nter with control F R EQU E NCY on t h e r i g h t pa i r o f marks, which a r e on t h e left a l o ngside t h e
sca l e
- H o l d the larger knob o f control F R EQU E NC Y aga i n
-
Set
t h e sma l l knob t o t h e left stop o f t h e sl ipping cl utch (electrical zero poi nt) .
Checking the accuracy of the frequency
- Switch on the i nstru ment 30 m i nutes before checking
-
Connect
a counter, e.g. P M 6630
- Turn control HF AMP L I T U D E fu l l y clockwise
-
Check
the frequencies according to tabl e 1 .
Readjust, if the tolerancies are not met; use the corresponding ind icated scale .
n
one
hand
or
P M 6640,
to connector
H F OUT
35
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