Motorola R2550 Service Manual

(00 
- 
19)  and  the 
monitor  and generate 
frequen-
cies  associated  with 
each.
To  change  the preset 
memory  frequencies,
perform  the following 
steps:
a.  Preds 
the MEM  key 
to 
access  the special
Memory  scrsen.
b.  Move 
the cursor  to 
the  appropriate  digit of
the  monitor 
or generate 
frequency  value
displayed,  and  enter 
the desired  frequency
information.
c.  Press 
the 
return  key  to 
return to the  previ-
ous  screen.
40 

Section 
4
APPLICATIONS
4-I  BASIC  FM 
TRANSMITTER  TESTING
This  section  of the 
manual  contains  information
on  typical  tsst 
setups  to perform 
some of 
the
more  common  radio 
tests 
using  the 
R-2550. Motorola 
takes no 
responsibility  for 
application
accuracy,  applicability,  or 
safety.  Always 
refer
to  your 
own transceivers  service manual 
for
recommended  test 
methods 
and specifications.
Mtc
AUDIO
IN
TRANSMITTER  UNDEB  TEST
Figure  4-1. 
Basic  FM 
Transmitter  Testing 
Setup
4l 

4-l.l 
Basic FM  Transmitter  Testing 
Setup
Refer  to Figure  4-1. 
Connect  the R-2550  Ana-
lyzer  RF 
VO  port 
to the  RF 
output  of 
the  trans-
mitter  under test. Connect  the R-2550  Analyzer
MOD  OUT jack 
to the  mic 
audio  input 
of the
transmitter  under test.
CAUTION
For  transtnit  power 
output mea-
surements,  connect 
the 
transmit-
ter  under  test 
only  to  the  R-2550
Analyzer  RF I/O  port. 
Do not
connect  it to the  R-2550 
Analyzer
ANT  port. 
The ANT  port 
is used
with  an...

4.
factor 
in 
RF  power 
measurements  espe-
cially  at 
UHF  and above
With  the 
cursor  located 
within the 
RF
Control  zone, press 
the RF 
DISPLAY  soft-
key:
Key  the 
transmitter  and 
read 
the power
(Input  Level)  and 
frequency  error (Freq
Err).  Refer 
to your 
radios  service manual
to  determine  if 
power 
and frequency  are
within  specified  limits 
and determine  if
any  adjustments  are 
required 4-t.3 
Modulation  Measurements
1.  Key  up 
the  transmitter  with 
appropriate
PL...

The 
voltage  levels 
displayed  in 
the
iud.u  Cintrol 
zone are 
Peak  oPen,
*ii,  ,oltog  Source 
imPedance  of
ie  MOD  OUT 
Port is 
100  ohms
lum  the lkHz  signal  on 
and  set 
for
il**  level 
as 
detennined  in 
step  3
Verify  proper 
MIC sensitivity  by 
reading
;;;i;,i.n.  Refer 
to 
Your  radios 
ser-
irc,  **our  to 
determine  maximum  rated
;ffi  deviation  to 
dercrmine  if 
anY
odio**tno  are 
required 7. 
To 
measuro  the 
percen*gt:1  distortion
locate  the 
cursor  within 
the...

4-1.4 
Off-TheAir  Measurements
1.  Connect  the 
TEKA-24A  Pick-Up 
Antenna
to  the  R-2550  ANT 
Port OPerate 
the
transmitter  under 
test 
either  into 
its 
own
anrcnna  or 
into  a 
dummY  RF 
load
2.  With  ths 
cursor  located 
wittrin the 
FtF
Control  zone, 
press 
the MON 
softkey  to
place  the R-2550  Analyzer  into 
its 
Moni-
tor  mode  of 
oPeration 4. 
Check  transmitter  frequency and 
modula-
tion  as 
detailed  in 
paragraphs  4-12 
and
4-r.3.
NOTE:  This 
method  may 
be used  to...

IVER 
TESTING
ual  connins  information
,i  p.rrot* 
some of 
the
rts  using  the 
R-2550 The 
R-2550  Analyzer  DVM 
input 
is 
unbalanced
Gfi;;;;TY:l;ffi  fi?i::3ff :::#;
to  measure  balanc
receiver  audio 
outputs  or 
telephone  lines
Figure  4-2 
Basic  FM 
Receiver  Testing 
Setup
46 p.^gffio-t
RECEIVEB  UNDER 
TEST 

-^-2.1 
Basic 
FM 
Receiver  Testing 
Setup
^tefer  to 
Figure  4-2 
Connect  the 
R-2550  Ana-
lyzer  RF 
VO  port  to 
the radio  antenna  connector
Connect  the 
radio  audio  output  to 
VERT/SINAD
port  of the  R-2550  AnalYzer
CAUTION
With  some  radios,  grounding  the 
speaker
leads  wiII 
damnge  the 
audio  circuitry
lJse  isolation  techniques  on 
these  radios Within 
the 
Audio  Control  zone 
set as
follows: Setto6oP/o ol
System  Deviallon
3.
l.  With  the 
cursor  located  within 
the...

6. 
With  the cursor  located 
within 
the Dis-
play  Control  zone (at 
Display:),  press 
the
EXT  SCOPE 
softkey.
Set  scope  vertical 
and horizontal 
detlec-
tion  to 
observe  sine  wave  from 
receiver
audio.
Dlsplay:  EXTERML  SCOPE
l..it]:ii..  i:i.ii:t  ii$:.dii. 
ll{r$i.ri..jf} 
i.:i.i
l{rt:  i.ltf:i:
i:1.,
4-2.2  Receiver  Distortion 
Measurement
1.  With  the cursor  located 
within the Dis-
play  Control  zone, press 
the EXT  DlsT
softkey  to 
measure  percentage 
of distor-
tion.  enemat...

4. 
Note  RF 
output  level 
required 
for  SINAD
reading  of 12 
dB  (-115 
dBm tYPical
dependent  on 
manufacturers  specifica-
tions).
NOTE:  RF 
output  level 
can be referenced  to
mV,  uV, dBu,  or 
dBm.  Selection  of
units  is available  within 
the Display
Control  zone (OutPut 
Level:).
4-2.4  Modulation  Acceptance Bandwidth
1.  Set  the 
volume  control of 
the  radio 
to
lTTo  of its 
rated  audio  output  level.
2.  Set  the RF output  level 
6 dB  (doubles 
the
voltage,  i.e. 
0.35  uV...