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LBI3LO72
TRANSMITTEB ALIGNMENT
TEST
EQUIPMENT
1
.
50-ohm
lva
t
tmeter
2,
50-ohm
Load
3.
DC
Probe
(19C330165G1)
4.
Voltmeter
(20,000
ohns-per-volt)
5.
13.8
V Regulated Pover
SUPP1Y
6.
Audio
Signal
Generator
7.
Frequency Counter
PRELIMINARY CIIECK AND
ADJUSTMENTS
NOTE
lnstall
the transmit orystals in
the
appropriate
sockets'
set the tuning cores in
L2o1'
'
L2O2,
L2O4
,
and
L205, so
tha
t the tops
of
these cores
are flush with the
tops of
the plastic coil forms.
Then.
turn
the
core
in
L201
2 turns
clockwise
and
turn
the core in
L2O2 4 turns
c
1
ockvi
se
.
Preset L207, L2Oa, L214, ard L215
so
that
the tops of the tuning
screws
are 1/8 inch
(3MM)
above the tops of
the
bushings on the castings'
Set
RPT/DIR frequency
switch
to
the
lower frequency
used,
Set power adiust control
R260
to
maximum
(fu11Y clockwise).
A11
adjustments
are
made
wlth
trans-
mitter keyed.
Unkey
the
transmitter
between
steps
to
avoid
overheating.
The
DC
probe and
voltmeter set
on
the
1 Volt
DC
scale 1s used to
monitor
TP201-TP203 when alignirg
the
transmitter'
Transnit
Frequency
is set by
L151
and
L752.
Check P903-2
for 8.5 volts
+0.15
volt.
Refer
to
CONTROLS,
STALS.
phot
og
ra
phs
TIIST
POINTS
to
locate
and
cRY-
I
2,
5.
6.
7,
when tuning
L2O7, L2Oa,
L274,
and L215,rsome of the coils
nay
peak
wi
th
the
tuning
screws
comj-ng out
of
thei r
ca
stings
.
This should only occur near the
top end of
the band.
If
i t
does,
the
affecled
screv(s)
should be turned clockwise
iust
to
the
point
where the neter
reading(s)
begin to change,
and
then
turned
I/4
lo
1/2
lutn
counterclockwise.
AUDIO
OSC
I
LLATOR
lO0O
Hr
I.O
VRMS
A.LIGNMENT
PROCEDURE
STEP
TEST
PROBE
TUNING
CONTROLS
I{ETER
READINC
PROCEDURE
I
3
4
5
6
7
8
I
10
11
l2
13
Tp20
1
TP2O
1
TP2O1
TP2O2
TP2O2
Tp20
3
TP20
3
Tp20
3
Tp203
Tp201
Watt-
meter
L151,L152
L207,L202
L204
L205
L2A7,L2O2
L2O4,L2O5
L207
L20
8
LzO5,L207
L208
L274
L275
L214,
L2r5
L752
R26A
Maxinum
(+0.35V
Typ,
)
Rated
Power
Mi
n
imum
(+0,15V
Typ.
)
Ma
xinum
(+0.30v Typ.)
Ma
ximum
(-1,10v
Typ.)
Mi
n
imum
(-1.ov
Typ.)
Ma
x
imum
(-1.25v
Typ.)
Ma
ximum
(+1.00V Typ.)
Min
inum
(+0.10V
Typ.
)
Maximum
(+0.65V
Typ.
)
Maximum
(+0,80V
Typ.
)
Ma
ximum
(20-25
Watts)
Rated
Power
Adjust
L151,
L752
L2Of
and
L2O2
in
that
order for
maximum
meter
reading.
Do
NOT
adJusr
L151/L152.
The
transritter
hN
prevlously
been
set
on
frequency.
Ad.just L204
for
mininum
meter
reading'
Adjust
L205
for
maximum
meter reading.
Readjust
L2O1,
L242,
L2O4
and,
L205
in
that order for
maxinum
meter reading.
Adjust
L2O7
for
mininum
meter reading.
Readjust L2A5, L207, and
L2O8
in
that order for
maximum
meter reading.
Adjust L214 for
minlmum
meter reading.
Adjust L208 for
maximum
meter readlng.
Adjust
L215
for
maximun
meter reading'
Readjust L2!4
and'
L275 for
maximun,
in that sequence'
lYattmeter should in-
dicate at least 20 watts.
Svitch the radio to the hlgher frequency
used, and adjust L151/L152 for this
higher frequency.
Ivattmeter should indicate
at least
20
watts on this channel also.
If not,
slight
readjustments of L2O7,
L2O8,
LEM, and/or L2I5 $ay be necessary.
Switch back and forth between both
channels to ensure each channel delivers
at least 20 watts after
adiustments are
compleied.
If necessa.y, readiust
R260 for rated
power output.
TRANSMITTER ALIGNMTNT
PROCEDURES
16
Issue I
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