Fluke 5500A, Service Manual

Page: 189 / 296

SC600 Option
SC600 Hardware Adjustments
6
6-63
Note
To verify the edge aberrations back to national standards, you should send
your Calibrator Mainframe to Fluke, or other facility that has established
traceability for aberrations. Fluke, for example, has a reference pulse that
is sent to the National Institute of Standards and Technology (NIST) for
characterization. This information is then transferred to high speed
sampling heads, which are used to adjust and verify the SC600.
6-81. Equipment Setup
The following equipment is needed for this procedure:
•
Oscilloscope: Tektronix 11801 with SD22/26 input module or Tektronix TDS 820
with 8 GHz bandwidth.
•
10 dB Attenuator: Weinschel 9-10 (SMA) or Weinschel 18W-10 or equivalent
•
Output cable provided with the SC600
Before you begin this procedure, verify that the SC600 is in the edge mode (the Edge
menu is displayed), and program it to output 1 V p-p @ 1 MHz. Press
O
to activate
the output.
Refer to Figure 6-7 for the proper setup connections and connect the Calibrator
Mainframe to the oscilloscope. Set the oscilloscope vertical to 10 mV/div and horizontal
to 1 ns/div. Set the oscilloscope to look at the 90% point of the edge signal; use this
point as the reference level. Set the oscilloscope to look at the first 10 ns of the edge
signal with the rising edge at the left edge of the oscilloscope display.
6-82. Adjusting the Edge Aberrations
Refer to Figure 6-17 while making the following adjustments:
1. Adjust A90R13 to set the edge signal at the right edge of oscilloscope display, at 10
ns, to the reference level set above.
2. Adjust A90R36 so the first overshoot is the same amplitude as the next highest
aberration.
3. Adjust A90R35 so that the second and third overshoot aberrations are the same
amplitude as the first aberration.
4. Adjust A90R12 to set the edge signal occurring between 2 ns and 10 ns to the
reference level set above.
5. Readjust A90R36 and A90R35 to obtain equal amplitudes for the first, second, and
third aberrations.
6. Adjust A90R13 to set the edge signal occurring between 0 ns and 2 ns to the
reference point set above. Center any aberrations so the peaks are equal above and
below the reference level.
7. Readjust A90R12 if necessary to keep the edge signal occurring between 2 ns and 10
ns at the reference level.
8. Readjust A90R13 if necessary to keep the edge signal occurring between 0 ns and 2
ns at the reference level.
9. Set the UUT output to 250 mV and the oscilloscope vertical to 2 mV/div. Check the
aberrations.
10. Connect the 10 dB attenuator to the oscilloscope input. Connect the UUT to the
attenuator and program the UUT output to 2.5 V.