TFT 844 - Page 16

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3.5.3
Pilot
Carrier
Modulation
Press the
19KHz
function switch
and
the
-20db/10%
attenuation
switch.
The
LEFT/TEST
meter will
indicate
the
pilot
modulation
level,
with
the
100%
mark
on
the meter denoting
10%
modulation. Correct
pilot
modulation level
is
between
8%
and
10%.
This measurement
can
be
made
in the presence of
program
modulation.
3.5.4
3.5.5
3.5.5.1
38
KHz
Subcarrier Suppression
a.
Apply
a modulating
between
5
KHz
and
15
KHz
to
the
left
channel
of
the
transmitter
under
test,
and
adjust
its
level
to
indicate
90%
on
the
LEFT/TEST
meter.
b.
Press
the
38
KHz
function switch.
c.
With
the
meter
attenuation
switches,
select
an
attenuation
that
provides a usable reading
on
the
LEFT/TEST
meter.
The
38
KHz
subcarrier
suppression
is
then the algebraic
sum
of
the
meter reading
and
the
attenuatin
inserted.
For example, a meter reading of
-2
dB
with the
-50
dB
meter attenuation switch depressed
denotes a
38
KHz
subcarrier
suppression of
52
dB
below
100%
modulation.
Stereo Separation
Stereo
Channel
Separation (Left
Channel
Modulated)
a.
Apply
a modulating signal
between
50
Hz
and
15
KHz
to
the
left
channel of the
transmitte
under
test
and
adjust
its
level
to
indicate
90%
on
the
LEFT
TEST
meter.
b. Press the
R
function switch.
c.
With
the
meter attenuation switches,
select
an
attenuation
that
provides a usable reading
on
the
LEFT/TEST
meter.
d.
The
channel separation
is
the algebraic
sum
of
the
meter reading
and
the attenuation
inserted,
less
approximately
1
dB
(0.915
dB)
to
account for the
90%
left-channel modulation
level.
For
example,
a
meter reading of -2
dB
with the
1%/-40
dB
meter
attenuation
switch
depressed denotes
a
stereo
channel separation
of
41
dB.
-
15-