HP 8901B Operation And Calibration Manual

Operation Model 8901B
LOCAL
(keystrokes)
EXAMPLE
To measure AM depth at AM OUTPUT with the AM ALC turned off, measure Vorr first:
Remove any signal at the RF INPUT and connect a dc voltmeter to AM OUTPUT.
- AUTOMATIC
OPERATION
(program codes)
AUMZ
For this example, assume the voltmeter reads an offset voltage of -0.36 Vdc. Connect an AM signal to
the RF INPUT and tune the Modulation Analyzer. Disable the AM ALC by selecting 6.2 SPCL.
Measure the dc voltage at AM OUTPUT. (When low AM rates are used, it is easiest to measure the
dc voltage
at AM OUTPUT before the modulation is applied.) For this example, assume the voltmeter
reads
-0.46 Vdc. Measure the peak ac voltage at AM OUTPUT (for low rates an oscilloscope may be
necessary). For this example, assume
0.02 Vpk was measured on an oscilloscope. The % AM is:
Vpk x 100% - 0.02 x 100% = 20% AM
%AM= -
lVdc - off1
l(4.46) - (-0.36)1
BLOCK DIAGRAM
AM I
I
MODULATION OUTPUT/
I AUDIOINPUT
I
# I
DEMODULATOR^ AUOIO
(ALC LOOP)
F I LTE RS
INPUT
ATTENUATOR
~~~~~ IF AMP
=5
-
-
BOCAL rL OSCILLATOR ALC REF
AUDIO VOLTMETER
DETECTORS AND DISPLAY
AM Output Block Diagram
3-148 AM Output

HP 8901B Specifications

General

Brand	HP
Model	8901B
Category	Measuring Instruments
Language	English