Motorola R2550 Service Manual

							DISPLAY 
ZONE
SOFTKEYS :ill$S[! 
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Figure  3-1. Screen  Zone Arrangement AUDIO 
CONTROL  ZONE
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Fosition:  (+)
Posi  ti)
t2 
						

							Control 
the 
cursor  location  and input  informa-
tion  by:
.  Using  the CURSOR  ZONE 
keys 
to move
the  cursor  among  the 
three  zones.
.  Using  the 
CURSOR  POSITION  keys 
to
move  the cursor  from field 
to field 
within  a
zone.
.  Once  at 
the 
desired  field, 
use either  the
TUNING  knob 
or the  numeric  keys  to  enter
numeric  information. 
Use the softkeys  for
other  menu 
selections.
3-2.1  Expanded 
Display
Some  functions  have 
the ability  to 
expand  their
contents  and overwrite 
other  display  areas.
These  consist  of 
the  following:
.  Encode  tables
.  Dedicated  keys 3-2.1.1 
Encode  Tables
Encode  Tables 
are selected  from  the  Audio
Mod  Sum:/lvlod  Sum: field). 
Selection  of the
General  Sequence  or DTMF 
encode  modes, 
and
pressing  the  display  table  softkey,  causes 
the
system  to 
overwrite  the 
meter 
and display  zones
with  the display  tables. 
Use the return 
softkey
to exit  to previous 
screen.
3-2.1.2  Dedicated  Keys
Refer  to the  Other  Functions  portion 
of this
manual  (paragraph 
3-8) for 
an explanation 
of
expanded  screens  in 
the  HELP,  MEM, 
SPF, and
CAL  modes.
3.3  HELP
The  Analyzer  provides 
on-screen  operating
instructions  via the 
dedicated  HELP 
key. 
Help
screens  are 
organized  such that  each  display 
area
has  an  associated  help 
screen  pertaining 
to that
area  of 
the screen.  System help (figure 
3-2) is
available  via 
a softkey  within 
each help 
screen.
Use  the return  softkey  to return 
to the  function
in  progress.
13 
						

							l.{heration 
of fhis unit is done  primcilc 
thrsugh the use  of
sqftkegs  located imdiatelg 
beltn the displeg 
srreen.
Thess  kegs along  nith the 
tU[St]B  PIISITIIHi 
kegs lncaled
*u  fhe 
risht  of lhe 
screen  prouide 
fsr ihe entrg  of test
requir*nenls  rnd the selerfion 
of data 
to be 
displaced.
2.  tach 
highl  ighted 
cursor  lsraf ion has 
its orn  unique-mnu 
of
selectisns  displaged 
in boxes 
imediafelc 
rhoue th* softkegs.
$il+lu  push 
the keg  beloH 
ihe 
bax to 
mke the  seleclion.
S.lhree  ffiin Hindolg  ot rursor  zones ilre useJ  for EF and
fiudio  rsntrol 
on lhp 
righl  and data  displag  sn the  left,
The  tlrB${H  Z{S[ kegs  provide 
fsr easg  ilosemnl 
bet$een
fhese  zonee.  ihee in fhs 
zone  of interesi 
th* cursar  cen he
rsued  Let*een  the hiehlighied 
entrt localion 
Lg using
the  fiue 
tU[$0R  P0$IIIttl 
keus,
Prse I 
of  3
Figure  3-2. System  Help
L4 
						

							3-4 
WARI\INGS
The  system  provides 
warnings  for 
the  following
operating  conditions, 
which 
are considered
detrimental  to 
the  proper 
functioning  of the
Analyzer:
.  RF  Overload
(Input  level to monitor  too  great 
for ac-
curate  measurement)
.  Recalibrate
(Indicates  that the 
units  internal 
tempera-
ture  has 
changed  more 
than 10o 
C from
where  it 
was  last 
self-calibrated.  This
may affect  the accuracy  of the  generator
output  level,  monitor 
input 
level below
+20  dBm,  and modulation  level.  Refer 
to
paragraph  3-8.3 for 
further 
information)
.  RF  Over  Temperature
(Excessive  power 
to RF 
load)
.  Optional  Battery 
Pack Voltage  Low If 
any  of these 
conditions  exist:
.  A warning  will be displayed  on  the 
warning
line  of the  CRT  for 
RF  overload,  recali-
brate,  and  low 
battery  voltage.
.  A  continuous  audible  warning  tone 
along
with  an overwrite  of the  screen  with 
a
warning  message  will 
be presented 
for RF
Over  Temperature  (figure 
3-3). This 
con-
dition  may  occur when 
the intermittent
power  rating of the  125 
watt  internal  load 
is
exceeded.  Both 
the  display  and the 
warn-
ing  tone  remain 
on and 
all operator  input is
ignored  until the condition  is 
corrected.
The  Analyzer 
then resumes 
normal operat-
ion.
CAUTION
Remove  RF power 
immediately  to
correct  the RF 
Over  Temperature
condition.  Otherwise  damage  to 
the
unit  may  occur.
WARNING
RF  LOAD  IS OVER  TEMPEMTURE
REMOVE  RF INPUT 
POWER
Figure  3-3. RF 
Over  Temperature  Warning 
Message
15 
						

							3-5 
PRIMARY 
OPERATING  MODES
Select  the  operating 
mode 
by placing 
the cursor
in  the  RF 
Control:  field 
in 
the RF  zone. 
Use
the  desired  softkey  to 
make 
selection.  Primary
operating  modes 
are: MOMTOR, 
GENERATE,
and  DUPLEX. 3-5.1 
MONITOR 
Mode
The  Monitor 
mode (figure 
3-4) provides 
the
units  test receiver 
function  which is used  in 
the
testing  of radio 
transmitters. 
It is 
capable  of
monitoring  RF input 
through its 
antenna  or a
direct  connection  to 
the transmitter  to accurately
determine  the frequency,  power 
level, and
modulation  characteristics.  It monitors  signals
from  400 
kHz  to 
999.9999  MHz. Center  fre-
quency  is set  in 100 
Hz increments. 
Specific
controls  which  further  configure the MONITOR
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Figure  3-4. Monitor 
Mode
16 
						

							mode 
are located 
within the RF 
zone  when
MONITOR  is 
first  selected.  The 
specific  entry
fields  are 
as follows.
Preset This  field 
allows  one of the 
twenty  possible
preset  monitor/generate  frequency pairs 
to
be  selected.  Frequency 
memory presets 
are
programmed  in the  memory 
screen as 
dis-
cussed  in paragraph 
3-8.5. When 
a preset
number  is 
entered  in 
this  field, 
the monitor
and  generate 
frequencies  stored under that
number  are used  by  the 
analyzer  for moni-
tor  and  generate 
modes.
B/W Selects  either wide  or  narrow 
IF 
and  audio
bandwidths  of 
the  unit  via softkey 
selection.
Freq Enter the  desired monitor 
frequency 
using
keypad  or tuning  knob.
Attenuation Select  the  amount  of 
attenuation  at the  RF
input  to the  monitor  receiver 
using  softkeys.
Selectable  input 
attenuation  is 
useful  in
adjusting  displays for 
a wide  range 
of input
levels,  as well  as for 
use  in high  RF  field
environments  where  intermodulation 
may
cause  desensitization  of the  receiver. Mon 
RF 
In
Selects  the 
RF input  port 
via softkeys.
CAUTION
Do  not apply  inpttt power 
to the  ANT 
input
port.  In the  event  RF power 
is inadvertently
applied,  the port 
is protected 
by an  in-line
RF  fuse.  This 
fuse  m.ay 
be accessed  by 
un-
screwing  the 
front  of 
the  BNC 
connector  out
of  the 
front  panel. 
Refer to Section  2-1,
Description  for additional 
detail.
The  RF UO  port 
contains  an  RF 
load 
and
should  be used 
for direct  connection  to 
the
radio  under  test. The 
ANT  port 
accesses
the  units  sensitive  receiver 
and should  be
used  with an antenna  for off-the-air  recep-
tion.  Selection  of the  ANT  port 
is indicated
by  a red 
LED  adjacent  to the  ANT 
connec-
tor.
Modulation  Type
Selects  the type 
of modulation  via 
softkeys.
17 
						

							3-5.2 
GENERATE  Mode
The  GENERATE  mode 
(figure 
3-5) configures
the  Analyzer  to 
generate  an 
RF 
signal  at 
a
controllableoutputr.rtoprovide.forawide range  of 
receivsr 
*nt  Muttiple 
internal 
and extemal 
mo 
dulation  signals 
c 
an  be  simlrltaneous-
ly  impressed  on 
the  tuiitt  frequencyto  gensrate
ffit**  signul 
for 
servicing  Signals 
from
400  kHz  to qggqgig 
vltr rnray 
be generated
L.*]*oency  is 
set  in 
100  Hz increments
Figure  3-5. 
Generate  Mode
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18 
						

							Specific 
controls 
which further 
configure  the
GENERATE  mode are 
located 
within the RF
Control  zone 
when 
GENERATE  is 
first 
selected.
The  specific  entry 
fields  are  as  follows:
Preset The  preset 
function  is the  same  as in 
the
MOMTOR  mode.
B/W Selects  either 
wide or naffow 
bandwidth  of
the  unit  via 
softkey  selection.
Freq Enter  the 
desired  generate 
RF frequency
using  keypad 
or tuning  knob.
Output  Lvl
Selects  generator 
output level 
in 
0.1  dBm
steps  over the 
range  of -130 
dBm  to 0
dBm.  An 
altemate  display of generate 
level
in  microvolts  is available  in 
the  Meter:
area  of 
the  display  zone. 
Output  level is
available  in 
two  ranges 
depending  upon
which  output  port 
is selected:
.  The  range 
of -80 
dBm  to 0 dBm  is
available  when 
the  high level  GEN
output  port 
is selected.
.  The  range  of -130 
dBm  to  -50 
dBm  is
available  when  the 
RF  VO output port
is  selected.
NOTE
If  AM 
modulation  is  selected, the maxi-
mum  output  at the 
GEN  port 
is re-
duced  to -6 
dBm;  the  mnximum  ouput
at  the  RF 
I/O  port 
is reduced 
to -56
dBm. Gen 
RF Out
Selects  the 
RF output  port 
via softkeys.  The
RF  UO  port 
is recommended  for most 
applica-
tions  where  GEN and MON  ports 
are com-
bined  for 
a single  connection  to the  radio
under  test. The 
GEN  port 
is recommended
where  higher  levels 
are needed. 
Selection  of
the  GEN  port 
is indicated 
by a red 
LED
adjacent  to the  GEN  OUT  connector.
CAUTION
Do  not  apply  input  power 
to the 
GEN
output  port. 
In the  event  RF power 
is
inadvertently  applied, the port 
is pro-
tected by  an  in-line RF 
fuse.  This 
fuse
may  be accessed  by unscrewing  the
front  of 
the  BNC 
connector  out of the
front  panel. 
Refe, to 
Section  2-1,
Description  for additional 
inform.ation.
Modulation  Type
Selects  the type 
of modulation 
via softkeys.
19 
						

							3-5.3 
DUPLEX 
Mode
The  DUPLEX  Mode  (figure 
3-6) provides 
a
simultaneous  RF generator 
output that is 
offset
in  frequency  from 
the monitor 
center  frequency
and  fully 
adjustable  in 
output  level. 
This capa-
bility  provides 
for servicing  full 
duplex  radio
equipment  as well 
as repeaters 
and radios 
opera-
ting  with 
offset  transmit 
and receive  frequencies.
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Lul:-  ?4.3 
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0ffset:  +45.888 
fflz
fkn: I  dB  illfl
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Fixed  lkHrl  2.80 kHz -
$cnth:  S.S$ 
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fxternel:  9.00 
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Figure  3-6. Duplex  Mode
20 
						

							Specific 
controls 
which 
further 
configure  the
DUPLEX  mode are 
located 
within the RF
Control  zone 
when 
DUPLEX  is 
first 
selected.
The  specific  entry 
fields 
aro as follows:
Preset The  preset 
function  is 
the  same  as in 
the
monitor  mode. 
However,  when 
the Duplex
mode  is 
activated  and 
a preset 
number  is
entered  into  this 
field, the duplex 
offset fre-
quency  will be automatically  calculated to 
be
the  difference  between 
the 
stored  monitor 
and
generate  frequencies.  If 
the difference  between
the  stored  monitor 
and generate 
frequencies  is
greater  than or equal 
to 55  MHz, 
the duplex
frequency  offset 
will be 
set  to its 
maximum
value  of 55  MHz.
B/W Selects  either 
wide or 
narrow  bandwidth  of the
unit  via softkey  selection.
Mon  trreq
Entet  the 
desired  monitor 
frequency 
using
keypad  or tuning  knob.
Offset Enter  the generator 
frequency  offset  relative  to
the  monitor  frequency 
entered. Offset fre-
quencies  of + 
0 to  55 MHz 
are allowed.  The
offset  frequency 
is 
set  in 
5 kHz 
steps. Mon
This  field  actually  contains two 
separate  fields,
one  for monitor  input 
attenuation  and 
one for
monitor  port 
selection.  Refer 
to the
MOMTOR  description for 
further  details.
Gen This  field  actually  contains  two 
separate  fields,
one  for generate 
output level 
and  one  for
generate  output port 
selection.  Refer 
to 
the
GENERATE  description for 
further  details.
NOTE
OnIy  FM 
modulation  is provided 
for
the  duplex  generator. 
Either FM 
or
AM  demodulation  may 
be selected.
Selection  must be done  in MONITOR
Mode  within  the RF 
control  zone. The
RF  I/O  port 
combines  monitor and
generate  signals 
for the 
d.uplex 
func-
tion.  However, 
either the ANT 
or GEN
ports  m.ay be 
independently  selected.
2t