Wavetek 3000 - Residual AM Test

PERFORMANCE TESTS
4 .8 RESIDUAL
AM
TEST
SPECIFICATION

>65 dB below
carrier in a 50 Hz to 15 kHz post-detection
bandwidth .
METHOD
EQUIPMENT
Modulation Meter

Radiometer AFM2
Distortion AnalyzerHP334A
A modulation meter operating
in AM mode is used to demodu-
late the Signal Generator output at the
minimum leveler
point where AM noise is maximum . A distortion
analyzer (oper-
ating in level mode) is used to increase
the resolution of
the demodulated output of the modulation meter . The system
is calibrated at a 10%
AM level . The 10% AM is removed and
theresidual
AM

is
read indB below the

calibrated 10%

AM
level
.

20
dB
is
added to the reading to relate the residual
AM to the carrier
.
PROCEDURE

1 . Set the Signal Generator controls as follows :
FREQUENCY selector

500 .000 MHz
MODULATION
MODE

AM
MODULATION
FREQ

1 kHz
MODULATION FM/AM

0% AM
OUTPUT VERNIER

-7
dBm reading on OUTPUT meter
OUTPUT step attenuator

0 dBm
Figure 4-2 . Residual
AM
Setup
3 .

Set the
modulation meter to read %AM at 500 MHz .

Set
the RF input attenuation to
10 dB, the IF bandwidth to ±400
kHz, the meter response to fast, the
function switch to +AM,
the meter range switch to 10 and
the filter bandwidth to 50
Hz-15 kHz .
2 . Connect the equipment as
shown
in
Figure 4-2 .
Model 3000
Signal Generator
Modulation Meter
Distortion
Analyzer
Input
RF
AF O
RF Out
Input
OutDut