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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
~ff
to
save
power ..
''
AUTO"
(automatic)
provides
a con-
tmuous
sweep
With no
vertical
input. The
"NORM"
(~ormal)
position requires
an external
vertical input to
tngger
a
sweep
.
The
"SCOPE
OFF" position turns
off
the
scope.
This will extend
battery o
perating
time.
3.6.10
TRIG
LEVEL
The
triggering
level potentiometer
adjusts the scope
trig-
ger voltage.
3.6.11 VERT/SINAD/DIST DVM
Muhi-purpose input.
Also
located in
the
oscilloscope
section
is
a
BNC
connector
to
connect signa ls to
the
unit
for the following
functions:
1.
External
vertical inputs
for osci lloscope 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
YRMS
.
4.
Digital Volt Meter input
.
Accepts AC
and
DC
volt-
ages
and provides
3
digit
a utoranging 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
the signal
being measured, and the
viewed oscilloscope signa
l
is
obviously overloading and
de
tlecting far
off-screen.
3.7.0 MONITOR
SECTION
MONITOR
evolume 0 Squelr.h
Sigl vi
•
Image
BW
H1
Wide
Lo
Nar
Demod Out
FIGURE
3.6-CLOSEUP
OF
MONITOR SECTION
3-9
3.7.1 VOLUME/SQUELCH
The
volume control adjusts
the
speake
r
output
level.
The squelch
control
adjusts the
threshhold
leve
l. Full
counter
clockwise
disables the
squelch.
NOTE: Monitor sensitivity is greatly decreased as the
squelch
control
is
increased clockwise beyond
the no-
SlJUCich squelch
point.
3.7.2
IMAGE HJ/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
"H
IGH"
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 BANI)WJDTH WLI>E/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
±75kH
z
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
frequen
cy
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 a lso includes
c~pability
to
modulate
a carrier with
PL,DPL,JDPL,
smgle tone or two tone
paging type
signalling.
A
four
pin
microphone connector
is
avai lable for voice
modulation
and
a
BNC
con nector
is available
for
input from an
ext
ernal signal generator. An
important
feature
is the
capability to
do
simultaneous
modulation.
It
is
possible
to
combine voice, any single code available from
the
code synthesizer and a
1kHz test tone in
order
to provide
composite signals
for
complete testing.
3.8.2 l
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 ·'Dev/%AM" o
n
the left
LCD
and
operates
in
any selected
function
swi
tch
position.
3.8.3
EXT
MOD IN
A
BNC
connector
is provided for external
modulation
signal inputs.
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