Wavetek 3000 - AM Bandwidth Test

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 modulationmeter reading in %AM
.
Set the modulation meter function switch to -AM, and note
the
modulationmeter%AMreading 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
MODULATIONMODE switch to AM .
15 . Make a note of the modulation meter reading in
%AM .
Set
the modulation function switch to +AM andnote 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 pointsmay be tested as desired .
The measurement is madewitha modulation
meter operating
in AM mode and afunction generator . The
functiongenerator
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 modulationfrequency is increased from
1 kHz
to
20 kHz
and the AM bandwidth is measured as the change in dB level
from
the
calibration level .
ModulationMeter

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
MODULATIONFREQ

EXT
MODULATION FM/AM

0% AM
OUTPUT VERNIER

+3 dBm reading on OUTPUTmeter
OUTPUT
step
attenuator

0 dBm
4-19