HP 8559A Operation And Service Manual page 97

MODEL 8559A
4-26. DISPLAY FIDELITY (Cont'd)
Algebraically subtract each converted reading (Theoretical Reading Subtracted from Corrected DVM
Reading) from previous converted reading. Record results in Table 4-16 (see sample computations). Maxi-
mum difference between adjacent readings should not exceed
0.1 dB/dB. Divide maximum value by 100 to calculate Log Incremental Error (in dB/dB).
Replace 10-dB step attenuator with 1-dB step attenuator. Set step attenuator to 0 dB.
Set spectrum analyzer Amplitude Scale to LIN and adjust TUNING control for maximum reading on
DVM.
Adjust signal generator OUTPUT LEVEL for DVM reading of 800 mV
should be approximately at top CRT graticule line.
Record DVM reading for step attenuator settings of 6 dB and 12 dB in Table 4-17.
Calculate each Corrected DVM Reading by algebraically subtracting offset recorded in step 2. Record
results in Table 4- 17.
Algebraically subtract corresponding Theoretical Reading from each Corrected DVM Reading, recording
results in Table 4-17. Maximum value should not exceed +24 mV, corresponding to
Reference Level. Divide maximum value by 8 to calculate Percent Linear Error.
Attenuator
Setting
0
6
12
PERFORMANCE TESTS
TABLE 4-17. AMPLITUDE LINEAR DISPLAY ACCURACY
D V M
D V M
Reading
Reading*
+
10 mV, corresponding to
+
offset (step 2)
of Reference Level Linear Error
Theoretical
Theoretical
Reading Subtracted
Reading From Corrected
D V M Reading
0
PERFORMANCE TESTS
1 dB/10 dB or
0.5 mV. Trace
3% of 800 mV