Philips pm2521 Operating Manual page 42

44
Selection of the trigger level
- Select the + or - trigger level by depressing pushbutton +/-.
Remark:
Signals which are higher or lower than the circuit zero oÍ the PM 2521 lO terminall can be triggered with
respectively the + or - triggeÍ level. In + tÍigger level mode the PM 2521 triggers on positive crossings of the
trigger level. In - tÍigger level mode the PM 2521 triggers on negative cÍossings of the trigger level.
+TRIGGE R
L E V E T O
sT 30r 5
820226
Fig. 16. Trigger level selection in function Hz.
-
A d j u s t t h e t r i g g e r l e v e l w i t h t h e t h u m b w h e e l u n t i l t h e G A T E i n d i c a t i o n o n t h e d i s p l a y i s i g n i t e d .
R e m a r k :
The trigger level can be adjusted between zero and end of range.
The voltage reading on the display indicates the height of the trigger level.
l f t h e i n p u t s i g n a l c a n n o t b e t r i g g e r e d , p r o c e e d a s Í o l l o w s :
-
S e l e c t a n o t h e r t r i g g e r l e v e l p o l a r i t y b y d e p r e s s i n g p u s h b u t t o n + / - a n d t r y t o t r i g g e r a g a i n .
-
C h e c k w h e t h e r t h e i n p u t s i g n a l i s l o w e r t h a n T , S o / o o Í t h e e n d o f r a n g e v a l u e o f t h e s e l e c t e d t r i g g e r l e v e l
range. Signals lower than 7 ,5 o/o cannoÍ be triggered accurately.
-
S e l e c t a h i g h e r t r i g g e r l e v e l r a n g e b y d e p r e s s i n g p u s h b u t t o n U P a n d t r y t o t r i g g e r a g a i n .
Measurement of the frequency
-
S e l e c t f u n c t i o n H z w i t h t h e f u n c t i o n s e l e c t o r .
The PM 2521 will now display the frequency of the input signal .
R e m a r k :
The PM 2521 is switched to automatic ranging mode.
The available ranges in the Hz function are
R A N G E R A N G I N G M O D E S G A T E T I M E
1 0 k H z M A N U A L * o n l y 1 0 s
1 0 0 k H z
1 M H z
1 0 M H z
A U T O o r
M A N U A L
*
1 s
1 0 0 m s
1 0 m s
Manual ranging mode can be selected by depressing pushbutton AUTO/MAN*.
By depressing either pushbutton UP or DOWN the ranges are selected.
lf the measured value exceeds, the range end value (> 99999), overload (OL) will be displayed.
During measuring the GATE indication is ignited. This only means that the gate is open. lt does not mean that
the PM 2521 triggers.
-
l f t h e d i s p l a y s h o w s a n u n s t a b l e o r a z e r o r e a d i n g , c h e c k t h e s e n s i t i v i t y a n d t h e t r i g g e r l e v e l a g a i n .
T R I G G E R P O I N T S ( + + ) T R T G G E R P O T N T S ( - - )