Motorola R-2400 Operator's Manual page 24

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3.6.9 TRIG MODE
The triggering
mode
is
a
three position rotary switch
and
selects the
scope
triggering mode or
can
turn the
scope
off to
save
power.
"AUTO"
(automatic) provides
a
con-
tinuous sweep
with no
vertical input. The "NORM"
(normal) position requires an external vertical input to
trigger a sweep. The "SCOPE OFF" position turns off
the scope. This
will
extend battery operating time.
3.6.10 TRIG LEVEL
The triggering level
potentiometer
adjusts the
scope
trig-
ger voltage.
3.6.11 VERT/SINAD/DIST DVM
Multi-purpose
input. Also
located
in
the
oscilloscope
section
is a
BNC connector to
connect signals
to the unit
for the following
functions:
1. External vertical
inputs
for
oscilloscope operation.
Sensitivity
ranges
from
10
mV/div to
10
V/div.
2. SINAD
meter input range is .5 V to
10
VRMS.
3.
Distortion meter input
range
is
.5
V to
10
VRMS.
4.
Digital Volt Meter input.
Accepts
AC
and
DC volt-
ages and provides
3 digit
autoranging scales of
1,10,100
and
300
volts
full
scale.
NOTE: An extreme overload condition to the
oscilloscope
could result in activating input protection circuitry which
can induce reading errors
on all
measurement
modes
using
the multipurpose input
connector. This
will
only
occur
with the
oscilloscope
vertical input sensitivity
set
much too sensitive for thesignal
being measured,
and
the
viewed oscilloscope signal
is obviously
overloading
and
deflecting far
off-screen.
3.7.0 MONITOR
SECTION
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3.7.1 VOLUME/SQUELCH The volume control
adjusts
the speaker
output level. The
squelch
control
adjusts the
threshhold level.
Full
counter clockwise
disables
the
sq
uelch
.
NOTE: Monitor sensitivity is greatly
decreased
as
the
squelch
control is
increased clockwise
beyond the
no-
squelch squelch
point
3.].2
IMAGE
H.T/LO
In either monitor
mode
this
toggle switch
selects
the
fre-
quency of
the
local oscillator injection above or below
the
programmed monitor
frequency to remove image
in-
terference. The
normal position
is
"LO". When
a signal
unsquelches the
receiver, flipping the switch to
"HIGH"
will verify that
the signal being
monitored
is
at the pro-
grammed frequency and
not a
receiver mixing
image.
This switch is also
used
to
identify
images
when
the
R-2400 spectrum analyzer is being
used.
3.7
.3 BANDWIDTH
WIDE,/NARROW
In either "PWR MON" or
"SENS
MON"
functions this
switch
selects
the
IF
bandwidth. Narrow band
is
-+-
10
kHz modulation
acceptance used
for
most 2-way radio
communication
systems
and wide band
is
!75
kHz mod-
ulation
acceptance used
for
commercial
FM
broadcast
monitoring or locating
a
signal when the exact
frequency
is
not
known.
3.7.4 DEMOD
OUT
The demod out BNC connector provides receiver audio
output. Output
signals can be used
for transmitter distor-
tion
measurements
or for external
frequency
counters.
3.8.0 MODULATION SECTION
3.8.1 GENERAL
The multimode code
synthesizer contains
all
controls
used
to generate
an audio signal.
Starting with
a
sinusoid-
al one
kilohertz tone oscillator, the section
also includes
capability
to
modulate
a carrier with PL,DPL,IDPL,
single
tone or two tone
paging
type signalling.
A
four pin
microphone connector
is
available for voice modulation
and a BNC connector is available
for
input from
an
external signal generator.
An
important feature is
the
capability to do simultaneous modulation.
It
is possible
to
combine voice,
&Dy
single code available
from
the
code synthesizer and
a
1
kHz test tone in order to provide
composite
signals
for
complete testing.
3.8.2
I
KHz LEVEL
An internal
1
kHz tone modulation level control
is
pro-
vided. When in the
full
counterclockwise position the
1
kHz
source
is
disabled.
Modulation
levels can
be
viewed
by selecting
"DevlVoAM"
on the
left LCD
and operates
in
any selected
function switch position.
3.8.3 EXT MOD
TN
A
BNC
connector is
provided
for
external modulation
signal inputs
\_,
FIGURE 3.6-CLOSEUP
OF MONITOR SECTION
3-9