Lf Square-Wave Response Ch4 And Ext Trig - Fluke Autoranging CombiScope PM3370B Service Manual

7 - 6
7.14

LF SQUARE-WAVE RESPONSE CH4 and EXT TRIG

For PM3370A, PM3380A, PM3382A, PM3390A and PM3392A only the step 'lfx10' has to be adjusted.
- Select 'lf ch4' with the TRACK rotary.
Select 'lfx100' with the softkeys: the ∆ sign is displayed behind 'lfx100'.
-
- Switch CH4 to ON and CH3 off.
- Press the TRIG 4 key.
- Put CH4 in 1 V/div with DC coupled input.
- Apply a square-wave signal of 100 kHz and 2.75V (pp into 50Ω) from a calibrator (mode 'edge')
to CH2. As an alternative you may use a 100 kHz / 5 Vpp square-wave from a function generator.
- Select 50Ω input impedance; if not available use a 50Ω termination resistor between cable and
oscilloscope input.
Adjust MTB/VAR to 2.00 µs/div.
-
Adjust the ∆ rotary for a flat pulse top (the initial overshoot should not be adjusted).
-
Select 'lfx10' with the softkeys: the ∆ sign is displayed behind 'lfx10'.
-
- Put CH4 in 0.1 V/div.
- Change the square-wave signal into 10 kHz/500 mV peak-peak.
Adjust MTB/VAR to 20.0 µs/div.
-
Adjust the ∆ rotary for a flat pulse top (the initial overshoot should not be adjusted).
-
- Remove the input signal.
CALIBRATION ADJUSTMENT PROCEDURE