Chapter 2 157
Making Adjustments
26. Correcting for Absolute Amplitude Accuracy for Option 050
26. Correcting for Absolute Amplitude
Accuracy for Option 050
This adjustment applies to:
All 8590 E-Series spectrum analyzers, Option 050
The frequency response of the analyzer is adjusted to optimize the
amplitude accuracy for the frequency range between 818 MHz and
948 MHz. The amplitude error from “Checking the Absolute Amplitude
Accuracy for Option 050" is used to determine how much flatness
correction is necessary. Normally, only a small amount of adjustment is
needed to bring the absolute amplitude accuracy of 8590 E-Series
spectrum analyzer equipped with an Option 050 into specification.
1. Looking at Table 2-11, Frequency Response Attenuator 10 dB,
calculate the error from the nominal value of −9 dB. For example, if
the measuring receiver reading at 818 MHz is −9.2 dB, then the
error is −0.2 dB. Find the average error by adding the four errors for
each frequency and then dividing the sum by four.
Average Error___________________dB
Note that if the average error is greater than 0.5 dB, there may be a
hardware problem. Typically, front-end component problems are
responsible for large amplitude errors. A defective First Mixer or a
poor cable connection may cause a power hole near the analyzer
Option 050 frequency band. In this case, performing a frequency
response check will uncover this type of problem. Perform a
functional check of the input attenuator if the errors for some
attenuation settings are larger than others.
CAUTION The next step disables the protection for the factory correction
constants.
2. Press the following analyzer keys.
FREQUENCY, −2001, Hz
CAL, More 1 of 4, More 2 of 4
Service Cal
Flatness Data
EDIT FLATNESS
3. Press ⇑ (step up key) until the ERROR readout for 804 MHz is
displayed (781 MHz for an 8591E spectrum analyzer or an 8591C
cable TV analyzer).
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