Technical data

Calibration 3
U2761A Service Guide 41
Amplitude Flatness (+20 dB Range) Adjustment
This procedure calibrates the AC amplitude flatness for high
frequency using +20 dB amplifier. This calibration is
performed using Sine wave at nominal amplitude of
400 mVrms across 50
Ω load.
1 Connect the power meter to measure the output
amplitude of the U2761A as shown in Figure 3- 4.
2 Set the power meter Filter Mode to Auto if you have
previously set it to Manual.
3 Use the power meter to perform a 100 kHz AC power
measurement at the output terminal for setup 89 in
Table 3- 19. Setup 89 establishes the power reference for
all the remaining setups in Table 3- 19. You must always
perform setup 89 before any of the following setups.
4 On the power meter, use the Relative Power function to set
the current reading as the reference value. This will allow
you to make future measurement result in dB.
5 Set the power meter Offset to Offset
+20dB
value previously
calculated in Table 3- 14. The power meter will directly
read the flatness error specification relative to 1 kHz.
6 Enter the measured value to the U2761A as described in
“Calibration Procedure” on page 30.
NOTE
This is the final adjustment procedure for the U2761A.