Anritsu 37 D Series, Maintenance Manual

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Non-Ratio Power:
This test checks the RF power level of the four individual RF paths
in the VNA. The complete paths are checked beginning with the RF
source and continuing out of the VNA Test Ports through the Down
Conversion and A/D circuits. All signal paths, including the front
panel Option 15 cables (if installed) are tested.
If the test fails and depending on the severity of the power loss, the
RF Source in the VNA may fail to phase lock (in worst cases) or the
VNA’s system dynamic range may be degraded. Ensure the the RF
cable between the Test Ports is of good quality and all external ca-
bles are connected properly. If this does not solve the problem, it
must be corrected by a trained Anritsu Service Engineer.
Non-Ratio Stability:
This test checks the general stabilty of the Non-Ratio channels. Raw
data is displayed, stored to memory, then divided by itself resulting
in a very smooth RF display at high resolution. The quality of this
display is checked after 10 sweeps.
If the test fails, a problem seen in both Test Channels (channels 2
and 3 on the VNA) could be caused by a defective RF cable between
the Test Ports. A problem seen on only one channel could be caused
by a damaged or incorrectly connected Option 15 front panel cable. A
problem seen on all four channels could be caused by an insufficient
warm-up period. If the problem still exists after these checks, it
must be corrected by a trained Anritsu Service Engineer.
Transmission Noise and Stability:
This test displays the system noise while measuring the default
source power (+5 dBm to –15 dBm, depending on model). A short
drift test is also performed, testing both Log Magnitude and Phase.
The instrument must not be disturbed during the drift test.
If the test fails, the RF cable between the Test Ports is the most
likely cause of failure when the problem appears in both S21 and
S12. If only S21 or S12 fails, check the Option 15 front panel cables
(if installed), then contact a trained Anritsu Service Engineer.
Transmission Sampler Saturation:
This test ensures that the Samplers of the Down Conversion module
are operating within their linear range by checking at default and
reduced VNA power.
If the test fails, interior attenuators on the VNA RF deck may have
been removed or be the incorrect values. The sampler(s) may have
degraded requiring replacement of the Sampler/Down Conversion
module.
PERFORMANCE TESTS OPERATIONAL TESTS
4-10 37XXXD MM