Philips pm2521 - Page 47

TIME MEASUREMENTS
Selection of the sensitivity ranges
— Select function V^^- with the function selector.
— Select the automatic ranging mode by depressing the AUTO/MAN* pushbutton.
Remark:
9
Manual ranging is indicated with * on the display.
— Connect the voltage source to the 0 and V terminal and measure the input signal.
— Make a note of the selected range and polarity. Slow signals may pass more than one range.
— Select function trigger level with the function selector and select one of the noted ranges and polarity.
Remark:
Ranges
V -T-r-r Trigger level
200 mV
2 V
‘ 2 V
20 V
200 V
2000 V
20 V
200 V
2000 V
Input signals that are lower than 7.5 % of the end of range value of the trigger level range cannot be triggered
accurately.
In the trigger level function only manual ranging ft possible, with the pushbuttons UP or DOWN.
Selection of the trigger level
NORMAL TRIGGER MODE
*
— Select the + or — trigger level by depressing pushbutton +/—.
Remark:
Signals which are higher or lower than circuit zero of the PM 2521 (O-terminal) can be triggered with the
+ or — trigger level respectively. In + trigger level mode, the PM 2521 triggers on positive crossings of the
trigger level. In — trigger level mode the PM 2521 triggers on negative crossings of the trigger level.
■ j Adjust the trigger level with the thumbwheel until the GATE indication on the display is ignited.
Remark:
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.
If the input signal cannot be triggered, proceed as follows:
— Select another trigger level polarity by depressing pushbutton +/— and try to trigger again.
— Check whether the input signal is lower than 7.5 % of the end of range value of the selected trigger level
range. Signals lower than 7.5 % cannot be triggered accurately.
— Select a higher trigger level range by depressing pushbutton UP and try to trigger again.