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4 .10 I
N
T
ERN
A
L
M
OD
UL
ATIO
N FRE
Q
UEN
CY T
E
ST
S
PE
CI
F
ICATIO
N
ME
T
H
OD
E
Q
U
I
PMEN
T
PR
OC
E
D
URE
4.11
PER
C
EN
T AM ACC
UR
ACY T
E
ST
ME
T
H
OD
4-14
meter ra
n
ge switc
h
to 3 . t
h
e RF input attenuation to 20 c1
B
, t
h
e I
F
band-
width to 1400 4! Ιι , ιΙω ι neter response [ π first, an
d
t
h
e filter Ιιαικ /ωί d(
h
to 50 Hi - 15
k
H
z .
4-
M
easure t
h
e average level π 1 t
h
e
FM
d
eviation on
t
h
e mo
d
ulation
meter l
d
is
r
egar
d
occasional
p
ea
k
sl . T
h
e residual
F
M s
h
o
u
l
d b
e <200 Hz .
Read t
h
e resi
d
ual
FM
wit
h
t
h
e f
u
nction switc
h
set to +
FM and -FM .
R
ecor
d
t
h
e g
r
eater π 1 the two rea
d
ings i
n
Ητ on li
n
e 28 of t
h
e
P
T
R
.
As many ot
h
er fre
qu
encies may be tested as
d
esi
r
e
d
400 Hz an
d
1 kHz + 5`λ
Α frcrς uency counter ~s ιι seλ to meas
u
re modulation frequency a , the
inst
r
ument rear- ηατι e Ι MOD ΤΡ . Since t
h
e i
n
ter
n
al 400 Hz an
d
1 k Ηι
oscillato
r
s are used for
b
ot
h
the AM a
n
d
FM
mo
d
es, t
h
is test will suffice
fo
r
both mo
d
es .
1 - Set the instrument co
n
trols as follows :
FRE
D
VERN
I
ER
N/A
F
re
qu
ency selecto
r
N/A
MODULATION MODE
I
M
OD
UL
ATIO
N FRE
D
400 Ητ
M
OD
UL
ATIO
N F
ΜίΑΜ
M
i
d
-range
O
U
T
PU
T
VERN
I
ER
Ν Α
OU
T
PU
T Step Attenuotos
WA
2 .
Connect ι
h
ε low fre
qu
ency input of the frequency counter to the
M
OD ΤΡ (
p
in 36 ο ! rear panel
PR
OG
R
A
MM
I
N
G jack .1101) and the cable
s
h
iel
d
to ground (pin 25 π 1
J
1011 . (See Figure 2-3 and Sc
h
e
m
atic 1) .
3 .
T
h
e πουηι e ί τΙιοιιΙλ rea
d b
etween 380 and 420 Hz .
R
ecord
t
h
e coun-
ter
r
ea
d
ing on line 29 of t
h
e
P
T
R
.
4 .
Set t
h
e
M
OD
UL
ATIO
N FRE
Qcontrol to 1 kfIz .
5.
T
h
e co
u
nte
r sh
o
u
l
d
rea
d between
950 a
n
d 1050
Hz, Record the
counter readi
n
g on line 30 of the PTR .
S
PE
CI
F
ICATIO
N
± Ι 5% + 5% of reading) it α fre
qu
ency of 1
kH
z NOTE :
T
h
is specification
applies fo
r
output li
m
its *+3
d
8
m
. AM is possi
b
le a
b
ove +3
dB
m if t
h
e
p
ea
k
of t
h
e
m
o
du
late
d
output
d
oes not excee
d
+13 d8
m
.
T
h
e % ΑΜ aceuiacy !s measu
r
e
d
wit
h
α
m
o
du
lation
m
ete
r
after t
h
e fro
n
t-
ραπe Ι
M
OD
UL
ATIO
N F
Μ !ΑΜ control
e
rror,
w
h
ic
h
is τ 4%, is s
ub
tracted
οιι 1 .
T
h
e
M
OD
UL
ATIO
N FM/AM
sli
d
er acc
ur
acy, w
h
ic
h
consists of ιιιρ
cιητ rοΙ linearity a
nd
t
he modulation scale e
r
rors, is
m
eas
ur
e
d in
ter
m
s of
the DC voltage α (
t
h
e rear-panel
M
OD ΤΡ .
T
h
e cali
b
ration of t
h
e voltage
αε , ο ss t
h
e control at maxi
mum p
osition is c
h
ec
k
e
d
initially .
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