Wavetek 3001 Instruction Manual page 51

13 . Set the MOD UL ATIO N M OD E switch to C W and the MOD U LATIO N
IF R ΕΟ switch to DC .
14 . Adj ust the
M
ODUL ATIO N FM/AM co n trol fo r α reading of 4 .500
10 .003 V
DC on
t
h e digital mulUmeter . Set t h e MOD ULATIO N FRE O
switc h to 1 kH z and t h e MOD UL ATIO N MODE switc h to AM .
15 . Ma ke α note of t he
m
odu latio n m ete r read i ng i n %ΑΜ . Set t h e mo du .
lation
f
u nctio n switch [ο + ΑΜ a nd n ote th e mo du lation mete r % ΑΜ
read ing κ before . Compute t
h e average of the two readings . T
he average
% ΑΜ
s
h ou l d b e between 84 .5 and 95 .5% AM . Record t
h e ave r age % ΑΜ
to t h e nea rest 0 .5% on line 34 of the PTR .
As ma n y ο tiιει
p
oi n ts may
b
e tested as desired .
DC 1 ο 20 kH z 13
d
8
b
andwidt h ), in pu t level
r
equi re d - 10 Vpp Into 600
ohms to
p
rovi d e cali brate d %ΑΜ co n t rol .
The meas ure m ent is made with α modu latio n meter operating in AM mode
and α f un ctio n ge n er ato r . T he functio n generator supp lies an exte r nal sine
wave to amplitude modulate t h e i n stru me n t . The system ά cali brate d α 1
δ
d
B on the mo dulation meter dB scale Japproximartely 50% AM) . The
exte rn al mo du lation
f
re qu e n cy is increased
f
rom 1 kH z to 20 kH z a nd t h e
AM b a ndwid t h is meas ur ed as
t
h e cheap in dB
f
r om the calibration level .
141 16) 17)
1 . Set th e instrument co n trols κ follows :
FRE D VERN I ER
CA L
F
re
qu
ency selecto
r
050 .000
MHz
M
OD
UL
ATIO
N M
OD
E AM
MOD ULATIO N FRED ΕΧΤ
MOD ULATIO N FM/AM 0% AM
O
UTP U T VERN I ER +3 dB
O
UTPUT Ste p Atten uator 0 dBm
2 .
Connect the equipment κ shown in Figure" .
3 . Set t h e modulation mete r to rea d %ΑΜ at 50 MHz . Set the RIF input
atten uatio n to 20 dB, t he I F b andwidth to Υ 400 kH z, th e motor response
to last.
t
he function switch to +ΑΜ , the meter range switch to 100, and
t h e
f
ilter b and wi d th to 75 kH z.
4 . Set
t
he function generator
f
or α 1 kH z sine wave ou tp u t a nd
t
he
attenuator controls for α 10
V
ρρ τιη e waveon the oscilloscope .
5.
A djust the FM/AM cont rol for α mo d ulation m ate r readi ng of δ dB
(ap proxim ately 50% AM) .
6 .
Mai n tai n the 10
V
φ
o
u tpu t level and increase th e fu nctio n ρeηerατοι
fre que ncy from 1 to 20 kHz . Ob serve t h e mo du latio n meter scale. It
sh o u ld r ead b etwee n -6 a nd -9 dB .
N
ote the change in dB
f
r om the -6 d 3
cali b ration level .