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Power Flatness
Power
atness is de ned as the maximum variation in power at the RF output connector across
the frequency range of the analyzer. If the speci cation is
2 dB is allowed. In this test a calibrated power sensor is connected directly to the RF output.
he analyzer is stepped through twenty-seven CW frequencies at one power level and each is
measured and corrected based on the power sensor cal factor. he maximum variation is then
compared to the speci cation. Several power levels are tested, ranging from the maximum
speci ed power to the minimum speci ed power without using the built in attenuator (if
applicable). If the analyzer has an attenuator, three more levels are tested, each one using one
section of the attenuator (10 dB, 20 dB, and 30 dB). he power meter is zeroed before making
any series of measurements below
A second test is performed as a precaution to ensure that no power holes exist. A through
cable is connected and, starting at 10 MHz, the analyzer is swept over its frequency range using
1601 points-per-sweep. he B* input is also measured and the resulting trace is checked for
any signi cant power holes that could have been missed during the previous section of this
test. he sweep is repeated again using each section of the attenuator (if one is installed) to
verify its power
atness.
If This Test Fails
Repeat the test, verifying that all connections are secure. If the test still fails, repeat
adjustment #104.
Absolute Power Accuracy
his test veri es the accuracy of the B* input at 30 MHz from its maximum input of +16 dBm
0
0
down to
50 dBm (
source is required to achieve the required power (in this case an HP 8116A function generator).
An external 10 dB step attenuator is used to vary output power over the full 66 dB range.
he output of the HP 8116A is sent to the step attenuator. A 6 dB attenuator is placed after
the attenuator and a power sensor is then connected to the attenuator. he source and step
attenuator are varied in 5 dB increments from +16 down to approximately
resulting power is noted. For measurements below
on the step attenuator values. his avoids having to use a low-power diode sensor (although
this would be acceptable, it is an inconvenience). Once the power levels have been measured
(or calculated) using the power meter as a reference, the power sensor is disconnected and
the output of the attenuator is connected to the RF input of the analyzer. he same power
level conditions are then repeated and the resulting analyzer measurements are averaged and
recorded.
hese measurements are compared to the power meter readings and any deviations are
compared to the speci cation. A narrow bandwidth is used for all analyzer measurements. For
75
analyzers, the 6 dB attenuator is replaced with a minimum loss pad.
If This Test Fails
First verify that the correct 40 dB section of the attenuator is being used (if applicable). See
\ he step attenuator's 40 dB card selection (3)" in \Performance est Software Installation"
earlier in this chapter.
If this is okay, repeat adjustment #110. If the test still fails, the cause is most likely damaged
A5 receiver diodes. See \ roubleshooting the A5 Receiver Assembly" in the \ roubleshooting
and Block Diagrams" chapter for more information.
0
19 dBm.
47 dBm for the HP 8730A and Option 1EC analyzers). A separate power
6
1 dB then a maximum variation of
0
24 dBm, the power out is calculated based
0
24 dBm and the
Performance T ests
1-23
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