Technical data

Calibration 3
U2761A Service Guide 39
Amplitude Flatness (0 dB Range) Adjustment
This procedure calibrates the AC amplitude flatness for high
frequency using 0 dB direct path. This calibration is
performed using Sine wave at nominal amplitude of
300 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 62 shown
in Table 3- 18. Setup 62 establishes the power reference
for all remaining setups in Table 3- 18. You must always
perform setup 62 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
0dB
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.
7 Proceed to AC amplitude flatness (+20 dB range)
adjustment or exit the calibration mode when necessary.