Am Bandwidth Test - Wavetek 3000 Instruction Manual

4 .12 AM BANDWIDTH TEST
SPECIFICATION
METHOD
Modulation Freq .
DC to 20 kHz (+3 dB bandwidth)
External
EQUIPMENT
PERFORMANCE TESTS
12 . Make a note of the modulation meter reading in
%AM .
Set the modulation meter function switch to -AM, and note
the modulation meter %AM reading as before . Compute the
average of the two
readings . The average %AM should be
between 27 .5 and 32 .5% . Record the average %AM to the near-
est 0 .5% on line 31 of the PTR .
13 .
Set the Signal Generator MODULATION MODE switch to CW
and the MODULATION FREQ switch to VERNIER .
14 . Adjust
the Signal Generator MODULATION FM/AM control
for a reading of 4 .500 ±0 .003 volts DC on the digital multi-
meter . Set the MODULATION FREQ switch to 1 kHz and the
MODULATION MODE switch to AM .
15 . Make a note of the modulation meter reading
in %AM .
Set the modulation function switch to +AM and note the modu-
lation meter %AM reading as before . Compute the average of
the two readings . The average %AM should be between 84 .5
and 95 .5% AM . Record the average %AM to the nearest 0 .5%
on line 32 of the PTR .
NOTE : This
concludes the modulation system accuracy test .
As many other points may be tested as desired .
The measurement is
made with a modulation meter operating
in AM mode and afunction generator .
The function generator
supplies an external sine wave to amplitude modulate
the
Signal Generator . The system is calibrated at -6 dB on the
modulation meter dB scale (approximately 50% AM) . The exter-
nal modulation frequency
is increased from 1 kHz to 20 kHz
and the AM bandwidth is measured as the change in dB level
from the calibration level .
Modulation Meter
Radiometer AFM2
Function Generator Wavetek 130
Oscilloscope Tektronix D10/5A18N/5B10N
PROCEDURE 1 .
Set the Signal Generator controls as follows :
FREQUENCY selector 050 .000 MHz
MODULATION MODE AM
MODULATION FREQ EXT
MODULATION FM/AM 0% AM
OUTPUT VERNIER +3 dBm reading on OUTPUT meter
OUTPUT step attenuator 0 dBm
4-19