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PERFORMANCE TEST
4.3.17
Vertical deflection; common mode rejection ratio at 50 MHz
(continuation of 4.3.16)
The common mode rejection ratio (CMRR) indicates the susceptibility to common
mode signals at higher frequencies. The susceptibility is verified in this test.
Settings/procedure:
1
-
Use a power splitter and two cables of equal length to CH1 and CH2. Apply
a sine-wave signal of 50 MHz with an amplitude of 0.6 V(pp into 50
Ω
) to
inputs CH1 and CH2.
2
-
Press the AUTOSET key.
3
-
Use a 50
Ω
termination. Use the internal termination when available.
4
-
Set CH1 and CH2 to 0.1 V/div and adjust the generator voltage for a
deflection of 6 divisions.
5
-
Set CH1 and CH2 to DC input coupling.
6
-
Press the CH1+CH2 key; to activate the added mode.
7
-
Press the INV key of CH2; the result is the display of the differential signal
of CH1-CH2.
8
-
Press the ON keys of CH1 and CH2; this switches CH1 and CH2 off and
only the differential signal of CH1 CH2 display is now visible.
9
-
Readjust the VAR function of CH1 or CH2 for minimum amplitude.
Requirements:
-
Verify that the amplitude of the CH1-CH2 differential signal is less than 0.24
divisions.
-
Repeat the above settings and procedure for CH3 and CH4 (for PM3384B and
PM3394B only).
4.3.18
Vertical deflection; LF linearity
The linearity of the vertical amplifier is checked by moving a signal with a fixed
amplitude vertically over the entire screen area.
Test equipment
Fluke 5500A mode: wavegen, wagve square (Alternative: function generator
PM5136).