HP 8901B Operation And Calibration Manual page 193

Operation Model
8901B
COMMENTS
Reasons to Recalibrate
Any time the power-sensor type is changed (for example, from an H P 8482A to an HP 8484A), and
RF POWER is selected, the Modulation Analyzer displays the need for recalibration by lighting the
RECAL annunciator.
Any time power sensors of the same type are exchanged (for example, from one H P 11722A to another),
and RF POWER is selected, the Modulation Analyzer DOES NOT recognize the need for recalibration.
When in doubt about whether the calibration factors match the power sensor, use Special Function 37
to display the calibration factors as described in Procedure step
#4
in this operating instruction.
Calibration information is retained in the Modulation Analyzer's non-volatile memory even when the
Modulation Analyzer is disconnected from its power source.
Finer Resolution for dB Measurements
Special Wnction 32.1 enables a resolution better than 0.004
dB.
For audio frequency measurements,
this special function enables a resolution of 0.1 Hz for frequencies from 100 to 250 kHz instead of the
normally displayed resolution of
1
Hz. The selection of Special Function 32.0 or 32.1 is maintained
through instrument power down.
32.0 Power is displayed with the normal measurement resolution of 0.01
dB.
32.1 Power is displayed with a measurement resolution better than 0.004 dF3.
32.2 Displays 0 if the normal measurement resolution is enabled (32.0 SPCL) and displays 1 if a finer
resolution
is
enabled (32.1).
Error 15
Error 15 is displayed until all necessary cal factor entries are made. Two calibration factors must be
available for the Modulation Analyzer to make RF power measurements; a reference calibration factor,
and a calibration factor at the signal frequency (entered manually or derived automatically from the
Automatic Calibration Factor table). Also, if RF power measurements are attempted at frequencies
higher or lower than any frequency in the table, interpolation is not possible and Error 15 is displayed.
Specifications for Cal-Factor Entry
RF Frequency Range:
Resolution: 50 kHz
Calibration Factor Range: 40-12076
Calibration Factor Resolution: 0.1%
Maximum number of entries/table:
0-42 GHz RF Frequency
17 for first table,
23 for second table
This special function
is
not available with firmware date codes 234.1985 and below.
(To
display the firmware date code, select
42.0
SPCL.)
To order a ROM set that contains this special function, contact the nearest HP sales office.
3-78 RF Power