Testing Frequency Sensitivity And Trigger Level; Testing The Dc Voltage Function - Test Equipment Depot 88 Service Manual

88
Service Manual

3-18. Testing Frequency Sensitivity and Trigger Level

The following procedure verifies the counter sensitivity and trigger levels for all
frequency modes and ranges. For any function and range, the sensitivity and trigger level
is the same in both frequency and duty cycle modes.
1. Connect the DMM calibrator to the z and COM inputs on the Meter.
2. Select the 4 V ac range, and press the RPM button to choose the frequency mode.
3. Apply the input from step 1 of Table 3-5, and check for the called-for response.
4. Select the 4 V dc range, and press the RPM burron to select frequency mode.
5. Apply the input from step 2 and step 3 of Table 3-5, and check for the called-for
6. On the Meter, press the RANGE button to enter the 40V dc range.
7. Apply the step 4 and step 5 input and check for the called-for responses on the
Step
1
2
3
4
5

3-19. Testing the DC Voltage Function

Perform the following procedure to verify the accuracy of dc voltage measurements. (A
separate verification procedure for dc millivolts (mV) is provided later in this section.)
1. Connect the calibrator to the z and COM inputs on the Meter.
2. Set the Meter rotary switch to F V.
3. Refer to Table 3-6. Apply the inputs in steps 1 through 5 and compare the Meter's
3-12
response.
Meter.
Table 3-5. Frequency Counter Sensitivity and Trigger Level Tests
Range
4 V ac
4 V dc
4 V dc
40 V dc
40 V dc
Step
1
2
3
4
5
response with the values shown.
Amplitude (RMS)
300 mV ac
1.7 V ac
1.0 V ac
6.0 V ac
2.0 V ac
Table 3-6. DC Voltage Test
DC Input Voltage
3.500 V
35.00 V
-35.00 V
350.0 V
1000 V
Frequency Display Reading
1 kHz 999.8 - 1000.2
1 kHz 999.8 - 1000.2
1 kHz 0000
1 kHz 999.8 - 1000.2
1 kHz 0000
Display Reading
3.493 to 3.507
34.93 to 35.07
-34.93 to -35.07
349.3 to 350.7
995 to 1005