Motorola R2550 Service Manual

							which 
snaps into 
the right 
front 
han-
dle  of the  unit.
4.  Take 
the power 
cord  that  is 
stored  in
the  cover.  Attach 
the cords  female
connector  to the  appropriate 
connec-
tor  on the 
Analyzers  rear panel.
Connect  the 
other  end of the  cord  to
the  power 
source.  For 
AC,  use 
a
grounded  3-wire 100-130 
VAC or
200-260  VAC power 
source.
5.  Set  the two-position  LINE 
switch
(bottom  of unit)  to 
either  the 110 
or
220  position, 
as applicable.  The 
fac-
tory  initially 
sets the 
LINE 
switch  for
110  VAC.  A 
3A  fuse 
for 110 
VAC
operation  and a 10A 
fuse 
for DC
operation  are installed 
at the  factory.
Change  as indicated 
for 
220  VAC
operation.
OPERATION  FUSE 
PART 
NUMBER
110  VAC 
3A 65-20404
12  VDC  10A 
65-10266
220  VAC  1.5A 
65-890033
6.  Remove 
accessories  from 
the cover  as
needed.
7.  Insert 
the whip  antenna  into the ANT
port,  located  to the  right 
of the  tuning
knob  on the 
front  panel.
8.  Press  the power 
switch  ON. The 
Ana-
lyzer  is now  ready  for 
use.  Before
operating  the Analyzer, 
review 
the
operating  procedures 
described in 
this
manual. CAUTION
When  installing  the Analyzer 
in a
vehicle,  fuse the 
DC 
supply  line
close  to the 
vehicles  battery. The
DC-L}A  fitse (located 
on the  Anal-
yzers  rear panel)  protects 
the
Analyzer  against overload  but does
not  protect 
the vehicle
1-5.3  Battery  Pack  Operation
The  optional battery  pack 
(RPN-4000A) 
is
designed  to conveniently  mount 
to the  back  of
the  R-2550. 
Containing  an internal  battery
charger,  the battery  pack 
is automatically
recharged  whenever connected 
direct to 
an  AC
receptacle.  Battery 
charging  is independent  of
the  main  R-2550 
equipment.
NOTE
The  battery  pack 
has an internal
switch  allowing 
the user to  switch
operation  of the  battery  pack 
to
II5  VAC  or 220 
VAC.  Before
attempting  to plug 
the battery  pack
into  the ac line 
for  charging,
ensure  this 
switch  is set  to the
correct  position 
for your 
line
voltage.  This switch 
is accessable
by  removing 
six stcrews  attaching
the  cover  to 
battery  pack 
chassis
as  shown  infigure 1-1.
2 
						

							Figure 
1-1. 
1lO VACt220  VAC 
Selection  Switch 
						

							1-5.4 
Battery  Pack fnstallation
l.  Se[  the 
R-2550  in 
an  inverted 
vertical
position  on a table  with 
the back  of
the  unit  facing 
upward.
Lay  battery  pack 
on the 
back  surface
of  the  R-2550 
such that 
the cut 
out  in
the  battery,  will 
match 
the locations
of  the  power 
plug 
on the  R-2550. Do
not  engage  the 
attachment  screw yet.
Plug  four-pin 
connector  from 
battery
pack  to four-pin 
connector  on back  of
R-2550  labeled  DC POWER. 4. 
Plug  AC cord  from 
batrery  pack 
tc
AC  power 
plug 
on back  of R-2550
unit.
Dress  cabling  into 
retaining 
area  and
slide  battery  into position 
to align
with  mounting 
screws
Align  and tighten 
the four 
slotted
mounting  screws.
5.
2.
6.
3.
Figure 1-2. Battery  Pack 
Installation
4 
						

							Section 
2
DESCRIPTION
2-I  DESCRIPTION
The  R-2550  Communication  System 
Analyzer  is
a  portable  test 
instrument  designed 
to 
monitor
and  service  radio 
communications  equipment
over  the frequency  range 
of 400  Hz 
to 9999999
MHz.  Figures  2-l 
and 2-2 
show  the 
Analyzers
controls,  indicators, 
and 
connectors,  and 
lists
their  functions.  The 
Analyzer  generates 
signals
measures  modulation 
and 
frequency,  and per-
forms  a variety  of 
tests  normally  associated  with
the  following  devices:
RF  Signal 
Generator
.Sensitive  Measurement  Receiver
spectrum  AnalYzer
Duplex  Offset 
Generator
.Oscilloscope
.Period  Counter
.AC/DC  Voltmeter
.RF  Wattrneter
signaling  EncoderlDecoder
signal  Strength 
Meter
.SINAD  Meter
.Distortion  Analyzer
2.2  OPERATOR  CONTROLS
2-2.1  Keys 
& Indicators
Power  Switch
Press  ON 
to 
energize  all 
circuitry  The
unit  automatically  selects 
AC power 
if
line  power 
is 
available.  Otherwise,  the unit 
looks  for 
a DC 
source.  Switching  is
automatic  upon 
cycling  of 
the  POWER
switch.
ON  LED
Illuminates  when 
power 
switch  is 
pressed
oN.
DC  LED
Illuminates  when 
equipment  uses 
DC
power.
Cursor  Zone 
KeYs (RF, 
AUD,  & DISP)
Determines  the 
zone  (third 
of CRT
screen)  that 
the 
cursor  will 
be active  in
When  changing  zones, 
the 
cursor  mQves
to  the  same  cursor  location  occupied  the
previous  time it 
was  in 
that  zone
Cursor  Position  Keys (Up, 
Down,  Left, 
Right,
TAB) The five  cursor  movement  keys 
are used
to  move  the 
cursor  to 
the  left, 
right,  up
down,  or 
tab.
HELP  KeY
Displays  help 
instructions  for 
the  present
screen.
MEM  Key
Accesses  the 
Memory  screen for 
non-
volatile  memory 
Presets.
5 
						

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Figure  2-1. Front  Panel 
Controls,  Indicators, 
and  Connectors 
						

							UNUSED 
CONNECTOR
RS.232  PORT
rO  M}IZ  REFERENCE
OSCILLATOR  IN/OUT
DC  INPUT  POWER
CONNTECTOR
REFERENCE  OSCILLATOR
CALIBRATION  ADJUST
LINE  VOLTAGE
SELECTOR  SWITCH
FUSES
AC  PLUG
INTERNAL/EXTERNAL
REFERENCE  OSCILLATOR
SWITCH
Flgre  2-2. 
Side,  Rear, 
and Bottom  Panels 
						

							Numeric 
Keys (0-9)
For  entering  numeric information  into 
the
Analyzer.  When a key 
is pressed, 
the
existing  CRT numeral  (where 
the  cursor
is  sitting)  is 
replaced 
with the numeral
represented  by the 
keypress.  The Analy-
zer  then  reacts 
to 
the  new 
information
just  entered.  When an invalid 
numeric
entry  is 
attempted,  the Analyzer 
ignores
the  keypress 
and the 
numeral 
on the
screen  remains 
unchanged.
+/-  Key
Toggles  the 
displayed  sign from  its  pre-
sent  value 
to the  negative 
of its  present
value.
ALT  Key
Enables  the alternate  functions 
on the
keypad.  Upon pressing 
the ALT  key, the
message  ALT appears  on  the message 
line.
Pressing  any other  key following 
the ALT
key  will  cause  the ALT  message 
to disap-
pear.
SPF  Key
Displays  the special  functions  menu 
of
the  display.
F2  Key  (optional 
function)
Permits  access to 
additional  functions.
Currently,  this 
key  provide 
no functional-
ity.
CAL  Key
Instructs  the processor 
to perform 
a self
calibration  on the 
system. Fl 
Key  (Optional 
Function)
Permits  access to additional 
functions.
Currently  used to return 
to local  mode
from  remote 
mode.
Softkeys Located  below the 
display,  the  softkeys
provide  a menu function 
to indicate 
all
possible  values or entries  for 
the  current
cursor  position. 
If the  cursor  moves, 
the
softkey  functions  change.
2-2.2  Knobs
SQUELCH Squelch  control. 
Clockwise  rotation
increases  the receiver 
threshold  signal
level  above  which  the 
squelch  opens.
VOLUME Controls  volume 
of the  speaker  audio.
BRIGHT Intensity  adjustment  of the  CRT.  Clock-
wise  rotation 
results 
in higher  intensity.
TUMNG Incrementally  changes the digit  over
which  the cursor  is 
currently  sitting.
Clockwise  rotation 
of the  tuning  knob
increases  the number; 
counter-clockwise
rotation  decreases  the number.  This
provides  the equivalent 
of an 
analog
control  for 
numeric  cursor 
entry locations.
2-2.3  CRT
9  cm  x 
11  cm  birmapped 
CRT. Provides 
data,
operating  controls,  and instructional 
information.
Displays  in 
digital,  analog,  and bar graph 
forms. 
						

							NOTE
The  CRT  has 
a screen  saver 
fea-
ture  that 
reduces  intensitY  after
approximately  30 
minutes 
of inac-
ilviry.  Press 
any  key  to restore 
the
display.
2-2.4  Connectors
2-2.4.1  trront 
Panel  Connectors
RF  IN/OUT
Provides  RF 
input 
signal  to the  Analy-
zers  internal  monitor 
or output  signal
from  the Analyzers  internal generator.
Also  provides 
combined  input/output  in
DUPLEX  mode. Contains  the 
RF  watt-
meter  load. 
This is 
the  only  front  panel
connector  to 
which  RF power 
may be
applied.
GEN  OUT
Provides  a high  level  generator 
RF out-
put  port 
isolated  from 
the Monitor  input.
DO NOT  APPLY RF 
POWER.
ANT Input port 
for sensitive  monitor 
receiver.
Useful  for 
off-the-air  measurements.
DO  NOT  APPLY  RF 
POWER.
NOTE
The  GEN  OUT 
and ANT 
con-
nectors  are protectedfrom 
over-
load  by 
a 1/16  amp  RF 
fuse  in-
stalled  in the 
front  panel 
con-
nector.  This 
fuse  may  be 
acces-
sed  by unscrewing  the 
front
portion  of the 
BNC  connector
from  the 
panel 
using a 7/16  inch
deep  socket  wrench.  Replnce-
ment  fuse part 
number  is GG-
6530277C002. CAUTION
The  RF 
fitse  leads 
must 
be
trimmed  to a 
length  of .48  +.02
inches  and the 
tips  cttt  to  a point
to  facilitate  installation.
VERT/SINAD  DIST/DVM 
COUNTER IN
Combined  input port 
for oscillosci 
?e
vertical,  SINAD meter, 
Distortion  fiIetr:i,
DVM,  and period 
counter  inputs.
DEMOD  OUT Recovered  (demodulated) 
audio output
(MONITOR  or DUPLEX 
mode).
MOD  OUT
Composite  output  of internally  generated
modulation  signals.
EXT  MOD  IN
External  modulation  input 
connector.
Requires  a fixed  input  level 
of l\u  for
accurate  level 
displays.
MIC Connector  for 
external  accessory  micro-
phone.
2-2.4.2  Side  Panel 
Connector
RS-232  PORT (25 
pin)
Provides  input/output  for printer 
or con-
trol  interface.
9 
						

							2-2.4.3 
Back Panel 
Connectors  2-3 
BOTTOM 
CONTROLS
10  MHZ  STD  InternaUExternal 
Oscillator Micro-Switch
BNC  connector  provides 
input/output  for 
Used to  switch  between input 
and  output
10  MHz 
reference  frequency. 
Input 
configurations for 
ttre  rear  panel 
10 MHz
impedance  is 
50  ohms.  Input  level 
re-  reference 
oscillator BNC 
connector.
quirement  is 
70  mV 
to 1 
Vrms.  OutPut
level  is 
approximately  250 
uVrms.  CAUTION
The  R-2550  will not 
function  prop-
AC  POWER  Connector  erly 
if 
this switch  is  set to external
Primary  AC power 
input port. 
without a I0 
MHz  reference 
signal
applied  to the  rear 
I0 MHz  refer-
DC  POWER  Connector  ence 
BNC 
connector.
Primary  DC power 
input 
Port.
FUSE  Internal 
Reference 
Oscillator Adjustment  Access
Line  fuseholders  for AC 
and DC line  Provides  convenient  external access to
fuses:  recatbrate 
reference oscillator frequency
setting.
OPERATION  FUSE 
PART 
NTJMBER
CAUTION
110  VAC  3A  55-20404 
(Jse 
a reliable 
and accurate 
fre-
220  VAC  1.5A 
65-890033 
quency snndard  when 
making  this
12  VDC  10A 
65-10266 
adjustment.
II0l220  VAC 
Selector  Switch
Used  to 
switch  the units  internal  power
supply  for 
either  I 
10V  or 220V  operation.
Check  the fuse 
for proper 
Size When
switching  to 
a different  line voltage.
10 
						

							Section 
3
OPERATING  INSTRUCTIONS
3.1  GENERAL
The  Analyzer  is 
designed  specifically  for 
the
service  and 
monitoring  of  radio  communications
equipment.  This 
product 
represents  a break-
through  in 
simplicity  of operation.  In place 
of
numerous  meters, keys 
and controls,  the R-2550
employs  a large 
CRT display  which simulta-
neously  presents 
control and  data  displays.  A
simplified  front panel, 
utilizing  soft keys, 
cursor
movement  keys, 
a numeric  key pad, 
an analog
tuning  control  and 
other  dedicated  function keys
all  combine  to 
make  the unit  extremely 
easy to
leam  and very  efficient 
to use.
Primary  operating  modes 
of the  unit  are
MONITOR,  GENERATE,  and DUPLEX.  They
are  accessed  through the 
RF  Control  display area
at the  upper right 
of the 
screen.  Within these
modes  of 
operation,  various measurement  func-
tions  may  be 
selected  in 
order  to measure 
and
diagnose  many 
types of radio 
equipment  under
test.
RF  data  display,  voltmeters,  distortion meter,
SINAD  meter, frequency  counter  and  modula-
tion  decoder  functions 
are available  through 
the
Meter  display  ,uea 
at the 
upper  left 
of the
screen.
Spectrum  analyzer, 
oscilloscope  and 
bar graph
displays  are 
available  through  the Display 
area
at  the  lower 
left 
of the  screen. Control 
of the  internal  modulation 
synthesizcr
and  level 
selection  for 
externally  applied modu-
lation  are provided 
through the Audio 
area at the
lower right  of the  screen.
Further  explanation  of 
the  function 
of each 
of
these  screen  areas 
can be 
accessed  through 
use
of  the  HELP 
key to the lower  right 
of the
scrgen.
3-2  BASIC  OPERATION
Control  of the 
unit  and  selection 
of data  to 
be
displayed  are  done 
through the  use 
of three  main
windows  which 
simultaneously  appear on 
this
screen  (figure 
3-1).
These three  main windows,  or 
cursor zongs, 
are
accessed  simply 
through  a 
cluster  of 
three
CURSOR  ZONE keys 
at the top 
center of the
unit.  The 
location  where  the cursor  rests wittrin
each zone  is known 
as a 
cursor  field. To 
con-
trol  the 
unit  and enter  data, 
all operator  inputs
are  made 
at highlighted  cursor field 
locations
(brighter-face  type).
For  further 
simplicity,  softkeys, with 
customized
on-screen  labels  interact 
with the screen  to
provide  a unique  menu 
of  entry  options for 
each
cursor  field. 
This greatly 
reduces  the number  of
keys  and having 
to search  through 
unrelated
controls  to find 
the 
one  thats  needed.
11