Fluke 5820A, Service Manual

Page: 99 / 158

Calibration and Verification
Hardware Adjustments
3
3-61
Resolution Bandwidth 3 MHz
Video Bandwidth 3 kHz
Reference Level 20 dBm
2. Use your Spectrum Analyzer’s Peak Search function to find the desired reference
signal. The Analyzer should show the fundamental, and second and third harmonics.
The harmonics need to be adjusted so that the second harmonic is at 33 dBc and
third harmonic should typically be at 38 dBc as shown in Figure 3-11.
3. To adjust the harmonics, adjust R8, as shown in Figure 3-11 until the peaks of the
second and third harmonic are at the correct dB level. You may find that you can
place the second harmonic at 33 dBc but the third harmonic is not at 38 dBc. If this
is the case, continue adjusting R8. The second harmonic will fluctuate, but there is a
point at which both harmonics will be at the correct decibel level.
R8
33 dBc
38 dBc
2nd harmonic
3rd harmonic
aag051f.eps
Figure 3-11. Adjusting the Leveled Sine Wave Harmonics
3-67. Adjusting the Aberrations for the Edge Function
Adjustments need to be made after repair to the edge function to adjust the edge
aberrations.
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 5820A.
3-68. 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