Adjustment 19 - Power Reference (Using Dc Substitution); Adjustment 18 - HP 8901B Operation And Calibration Manual

Adjustments Model
8901B
Adjustment 18
POWER REFERENCE (USING REFERENCE COMPARISON)
Service Sheet 3
Description
The frequency of the internal power reference is checked and adjusted, if necessary,
to
50 MHz. The
power from an external 1 mW power reference is measured with a power sensor and the power meter
of the Modulation Analyzer. The same power sensor and power meter are then used
to
measure the
power from the Modulation Analyzer's power reference. The Modulation Analyzer's power reference is
adjusted to give the same reading as for the external power reference.
NOTE
After adjustment, the accuracy of the Modulatwn Analyzer's power ref-
erence will be &I..%!%. Greater accuracy can be obtained
by
using a re-
cently calibrated external power reference or by following the procedure in
Adjustment 19
-
Power Reference (Using DC Substitution).
Equipment
Power Reference
..........................................................
HP 435A Opt KO5
Sensor Module
..................................................................
HP 11722A
Procedure
1.
Connect the sensor module's cables to the SENSOR and INPUT of the Modulation Analyzer.
Connect the sensor module's input to the CALIBRATION
RF'
POWER OUTPUT. (If a
sensor module is not available, connect the Modulation Analyzer's INPUT directly to the
CALIBRATION RF POWER OUTPUT.)
2. On the Modulation Analyzer, press the blue key then press INSTR PRESET (the AUTOMATIC
OPERATION key) to preset the instrument. Key in 45.16 SPCL
to turn
on the
RF
power
calibrator. Press TRACK MODE. The Modulation Analyzer's display should read between 49.5
and 50.5 MHz.
3. If the frequency of the RF power calibrator is not within the proper limits, remove the thumb
screw retaining the A32 Power Reference Oscillator and slide the assembly out. Adjust A32L1 for
a frequency reading between 49.5 and 50.5 MHz. (The adjustment is accessed through a hole on
the back side of the assembly.)
After removing the
RF
power calibrator assembly, take care that the power
supply terminals do not short against the metal chassis parts.
5-28 Adjustment 18