Fluke 5500A, Service Manual

Page: 239 / 296

SC300 Option
SC300 Hardware Adjustments
6
6-113
harmonic is greater than or equal to –34dBc The second harmonic will fluctuate, but
there is a point at which both harmonics will be at the correct decibel level.
R8
-34 dBc
-39 dBc
2nd harmonic
3rd harmonic
yg127f.eps
Figure 6-29. Adjusting the Leveled Sine Wave Harmonics
6-141. Adjusting the Aberrations for the Edge Function
Adjustments need to be made after repair to the edge function to adjust the edge
aberrations.
6-142. 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.
•
20 dB Attenuator: Weinschel 9-20 (SMA) or Weinschel 18W-20 or equivalent
•
Output cable provided with the SC300
Before you begin this procedure, verify that the SC300 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 6-22 for the proper setup connections and connect the Calibrator
Mainframe to the oscilloscope. Set the oscilloscope vertical to 1 mV/div and horizontal
to 1 ns/div. 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.
6-143. Adjusting the Edge Aberrations
Refer to Figure 6-30 while making the following adjustments:
1. Set the oscilloscope to display the 90% point of the edge signal. Note this voltage (or set
to center of the display) as it will be used as the reference for the following adjustments.
2. Set the oscilloscope to display the leading edge and the first 10 ns of the edge signal.
Adjust A90R13 to set the edge signal at the 10 ns point to the reference level.
3. Adjust A90R12 to flatten out the edge signal. Readjust A90R13 if necessary to keep the
edge signal at the reference level.
4. Adjust A90R35 so the first overshoot is the same amplitude as the second aberration.