eXact 240 - 3.5 DC Levels and Output Amplitudes

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240-0664
SECT IO N I I I
CA LIBR A TION
3.4.1 PRELIMIN ,R Y SET TING S ND DJUSTMENTS (coNTINUED)
(c) CONNECT THE VERTICAL AMPLIFIER OF THE OSCILLOSCOPE TO THE
S INE WAVEFORM OUTPUT TERMINAL OF THE FUNCTION GENERATOR .
(D) SHAPE THE SINE WAVE AS FOLLOWS
(1) A DJUST C S INE S HA PE R145 FULLY cc w (GROUND).
(2) USING FIGURES 1 THROUGH 5 WITH THEIR RESPECTIVE NOTES,
ADJUST A S INE SHAPE ~ ND B SI NE SH A PE (R139 AND R143)
FOR THE BEST SINE WAVE POS SIB LE.
NOTE: THESE ADJUSTMENTS ARE VERY INTERDEPENDENT. ONE
CAN BE AT A SETTING WHERE IT IS IMPOSSIBLE FOR THE
OTHER TO CORR ECT . 8 S INE S HA PE CONTROLS MORE OF
THE AMPLITUDE A ND A S INE S H APE MORE OF THE SH A PE
ITSELF.
IT IS BEST TO S ET 8 FOR NEARLY MAXIMUM
AMPLITUDE, THEN AS A IS A DJUSTED 8 CAN BE REDUCED
IN AM PLITUDE TO MAINTAIN PROPER SH A PE. THIS IS AN
OPTIMUM WAVE SHAPE AT THIS POINT.
(3) ADJUST c S INE S H APE TO ROUND THE BOTTOM OF THE SINE
WAVE. A S INE S H/ PE A ND 8 SI NE S HA PE MAY BE READJUSTED
FOR FIN AL SMOOTHING.
3.4.2 FIN AL S INE W~ VEFORM ADU TME NTS
( A) CONNECT THE DISTORT I ON ANA LYZER INPUT TO THE S INE WAVEFORM
OUTPUT TERMINAL OF TH E FUNCTION GENERATOR.
(B) CAREFULLY A DJUST S INE SHA P E A , BAND C FOR MINIMUM HARMONIC
DISTORTION.
(c) VERIFY THAT THE TOTAL HARMONIC DISTORTION IS LESS THAN 2%.
NOTE 1: IF THE ABOVE S PECIFIC A TIONS CANNOT BE MET, CHANGING
OF V104 AND REPEATING CA LIBR A TION PARAGRAPHS 3.4.1
THROUGH 3.4.2 (c) SHOULD BE A CCOMPLISHED.
NOTE 2: IF A Wh VEFORM ANALYZER IS USED IN PLACE OF A DISTOR-
TION ANA LY Z ER, TH E FIRST 10 H AR MONICS SHOULD BE CHECKED
WITH ADJUSTMENTS MADE CONSIDERING THE FIRST 5.
3.5 DC LEVEL S AN D OUTPUT AM PLITUDES
3.5.1 P R ELIMIN ARY SE TTING S A ND A DJUSTMENTS
(A) SET THE OSCILLOSCOPE CONTROLS AS FOLLOWS:
VERTIC L SE NS ITIVITY
SWEE P TIMING
INPUT COUPLING
TRIGGER
A PPROX. 5 v/cM
10 MSEc/cM
DC
EXTERNAL