Trigger Sensitivity Via Ch1, Ch2, Ch3 And Ch4 (Ext) - Fluke Autoranging CombiScope PM3370B Service Manual

6 - 30
6.3.34 MAIN TB triggering PM3390B/3394B; trigger sensitivity via CH1, CH2, CH3 and
CH4 (EXT)
The trigger sensitivity depends on the amplitude and frequency of the trigger signal. In this test the
main timebase trigger sensitivity via the CH1, CH2, CH3 and CH4 inputs is checked. For the
PM3390B, this is checked for CH1, CH2 and EXTernal TRIGger input.
Test equipment:
Fluke 5500A mode: levsine
(Alternative: constant amplitude sine wave generators SG 503 + SG 504).
Test set-up:
Settings/procedure and requirements:
1 - Apply a 100 MHz sine-wave signal of 1 V(pp into 50Ω) from the SG 503 to input CH1.
2 - Press the AUTOSET key and set CH1 to 0.5V/div.
3 - Use a 50Ω termination. For instruments with switchable 50Ω input impedance it is
recommended to make use of this feature (via VERT MENU key).
4 - Set the input coupling of CH1 to DC and POSition the signal in the vertical center of screen.
5 - Select 'trig' from in the menu under the TB MODE mode key.
6 - Press the TRIGGER menu key and select level-pp 'off' and 'dc' trigger coupling from the
TRIGGER MAIN TB menu
7 - Adjust TRIGGER LEVEL for a correctly triggered display.
8 - Decrease the amplitude of the input signal.
9 - Verify that the signal is well-triggered at amplitudes of 0.6 divisions and more.
10 - Decrease the input frequency to 50 kHz.
11 - Verify that the signal stays well-triggered at amplitudes of 0.6 divisions and more.
12 - Increase the input frequency to 200 MHz.
13 - Increase the input voltage to 1.2 division.
14 - Turn TRIGGER LEVEL.
15 - Verify that the signal is well-triggered at amplitudes of 1 division and more.
16 - Apply a 300 MHz sine-wave signal of 2V (pp into 50Ω) from the SG 504 to input CH1.
17 - Adjust the input voltage to 2 divisions. Signal must be in vertical center of screen.
18 - Verify that the signal is well-triggered at amplitudes of 2 divisions and more; adjust TRIGGER
LEVEL when necessary.
PM3394B: repeat the procedure for CH2, CH3 and CH4 for the frequencies 50 kHz (0.6 division input
signal) and 300 MHz (2 division input signal)
PM3390B: repeat the procedure for CH2 and the EXTTRIG input for the frequencies 50 kHz
(0.6 division input signal) and 300 MHz (2 division input signal)
Press the ANALOG key ('DIGITAL MODE' is displayed briefly), then repeat the tests in this chapter
for the digital mode.
Press the ANALOG key ('ANALOG MODE' is displayed briefly) to return to analog mode.
PERFORMANCE TEST