Motorola R-2400 Operator's Manual page 36

6.
when
using the
service
monitor's *RF
Inlout,'
port
in
the "Pwr Mon/Anlzr on"
mode, there
iJ
no
directly
connected signal path
to
the
spectrum
analyzer receiver. Instead, the signal path iJ
loosely
coupled through internal capacitance.
Thus,
a
signal
of
a given power
level at
a
low
frequency
will
appear
to
be
of
greater power
at a
higher
fre-
quency. Hence,
a
transmitter's harmonic power
will
appear
greater
than
it
really is, relative
to
the
level
of
the carrier display. LEVEL ACCURACY ovER
WIDE
FREQUENCY RANGES IN
THE
..PwT
Mon/Anlzr
on"
MODE
Is NoT
SPECIFIED.
Refer
to
page 5-6
for
a
recommended procedure.
7
.
when
using
the
spectrum analyzer feature,
the
HORIZ
and VERT vernier controls MUST BE
IN
THE
$CaLl"
POSITIONS. Failure to
do this
may
result
in
an uncalibrated display.
FIGURB 5.2-SINAD/z0
dB QUIETING
TEST SETUP AND DISPLAY
5.2.0
RECEIVER SENSITIVITY TEST.Iz dB SIN
AD/
AUDIO
DISTORTION
Use the
R-2200
/R-2400 signal generator and SINAD
meter
to
measure a
receiver's performance by the fol-
lowing
procedure:
l.
As shown on figure 5.2,
connect the
Monitor's *RF
InlOut" to
the
antenna connector
of
the
receiver
under test. Connect
the
service
monitor's ,,yert/
Sinad/Dist" to the
receiver's audio output.
Disable
all PL's
and open the
Squelch.
2.
Set the function switch to
,,Gen".
3.
Select
the RF frequency and
enter
directly from
the
keyboard.
4.
Select the "Dev" function on the left LCD.
Use
"Dev,
a/o
*
/
-"
to verify
+
and-deviations.
5.
Adjust
"l
KHz Lvl" control for
60Vo
of rated
devia-
tion
as
indicated on the LCD. To prevent
spurious
noise modulation,
set
"code
Synth
Lvl"
to min
and
"Ext Lvl" to ,,Off".
a. with
a
l000uv
RF input level, adjust
the volume
;ffi 131,""Jil:
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ii
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the
speaker.
b.
Select
"Dist"
on the
left LCD to
display distor-
tion or "SINAD" to
display SINAD.
6.
Set
RF
Step attenuator
to -50
dB and the
"RF ver-
nier" to
mid-range. The displayed RF level
should
indicate about 2uY. Adjust the attenuator (10
dB
steps)
and the "RF vernier" until a
12
dB SINAD
reading
appears on the display.
7.
From
the
RF
level on
the
display,
read the receiver's
12
dB SINAD sensitivity
in uV or
dBm.
5.3.0
RECEIVER SENSITIVITY
TEST
20 DB QUIETING
l.
Connect the
service
monitor to the
receiver under
test, as shown
in
Figure 5.2. set the
left LCD
to
"DVM",
"Function" switch
to
"Gen" and
select
66FM"
or
"cw"
mode.
Press "Gen
on/off'to
dis-
able the generate
function, indicated by
the flashing
"Gen" indicator on the left display.
2.
Turn on the
receiver (unsquelched)
and turn up
the
receiver
audio gain
to
feed audio
noise
to
the moni-
tor
(at least % rated audio power).
Read the audio
noise voltage fed
to
the monitor. Note the
noise
reading
(REF) in volts.
3.
Press "Gen
on/off"
to
enable
the generator. with
all modulation off,
adjust the RF
level
until
the dis-
play
reads 20
dB
less
than REF
above
(0.
lOx
the
REF voltage).
4.
Read the RF level required to produce
20
dB quiet-
ing in uV or dBm using the "RF
V/dBm"
key.
5.4.0
SQUELCH SENSITMTY
TEST
l.
Connect the
service
monitor to the
receiver
under
test, as shown
in
figure 5.2. Set the "Function"
switch
to "Gen"
and
modulation to "FM". Enter
the
frequency
of
the receiver under
test.
2. To
check
PL/DPL
squelch sensitivity, enter
the
proper PL/DPL
frequency/code
from the
key-
board.
Set
modulation switch to
"cort",
select
pL
or DPL
mode, enter Tone Data, and key
in
fre-
quency.
Ensure
that "Ext Lvl"
and
"l
KHzLvl,
are
off.
3. Adjust
the "Code Synth
Lvl"
control to provide
a
nominal
750
Hz
(500 Hz
-
I
KHz) deviation of
the
PL/DPL
code.
To
check carrier squelch, turn
off
all modulation.
4.
Place "Gen
on/off'
switch to
off
to remove the RF
output from
the receiver.
Set the receiver's squelch
control to
the
point
where the receiver
just
begins
to
quiet.
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