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
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