Anritsu 37 D Series, Maintenance Manual

Page: 115 / 190

7-8
MEASUREMENT
ACCURACY PROBLEMS
All Data on All
Channels is Greatly
Inaccurate
Refer to the block diagrams in Chapter 3 that are labeled "Signal
Paths.”
For 50 and 65 GHz models, refer to the block diagram of the Test Sig-
nal paths (Figure 7-4). Also, refer to Tables 7-2 through 7-4. Use of a
spectrum analyzer, oscilloscope, and DVM will be useful to find the de-
fective assembly.
The instrument may be in an unusual setup, such as a
non-phase-locked “Receiver” mode, or the internal memory buffers
may have corrupt data due to a process that was started, but incor-
rectly terminated. To correct this problem, press the Default Pro-
gram key, then the
0
key to return the instrument to normal measure-
ment condition and clear the memory buffers. Reload all of the
coefficient disks from the Calibration Kits.
Excessive Ripple in
the Display of
Low-Loss Devices
Ensure that all of the calibration coefficients are loaded into the VNA.
The coefficients may have been erased by a Default Program /
0 re-
set.
The calibration selected should be 12 Term . Also perform the calibra-
tion using sliding terminations rather than broadband fixed termina-
tions.
Insufficient System
Dynamic Range
Select “Include Isolation” and increase the RF Source power during
the calibration setup.
Before measuring the Isolation Devices during the calibration, press
the Video IFBW key and select “10 Hz Minimum”.
During the measurement of the DUT, select “10 Hz IF Bandwidth.”
Perform the automated “System Dynamic Range” test found in the
3700Test Program (described in Chapter 4). If this test fails, the prob-
lem is typically solved by replacement of the Sampler/Down
Conversion Module.
7-9
NON-RESPONSE OR
OTHER UNUSUAL
BEHAVIOR Many problems may be solved simply by performing a Master Reset,
which clears all memory buffers and sets the instrument to factory-de-
fault settings. To do this, press the Default Program key, then the 0
key. Note that this will also clear all setup memories (#1 through #10),
and will delete all Cal Kit coefficients. Cal Kit coefficients must be re-
loaded using the floppy disk from the Cal Kit.
TROUBLESHOOTING MEASUREMENT ACCURACY PROBLEMS
37XXXD MM 7-11