Installation manual
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411iedSignal
AEROSPACE
BENDIX/KING
® Service
Aid
AlliedSignal
General
Avi
ation Avionics
400 Norrh Rogers Road
Olarhe, Kansas 66062-1212
Service.
Aid:
KT
76/KT
78-102
Transponder
SUBJECT:
Mode
A
and
C updates to
improve
reliability.
Reliability of the
KT
76/78
can
be
improved
by
removing
and
replacing the
components
listed
below
and
careful
alignment
of the decoder one-shots.
Remove
and
replace the
components
in
the unit
with
the
ones
in the following
list.
COMPONENT
PART
NUMBER
DESCRIPTION
1413
120-00061-0000
IC,
SN74221N
C426
105-00031-0014
CAP,
MY
3.3KKP,
BOV
C429
104-00001-0038
CAP,
S/M
2400pf,
1%
C430
104-00001-0038
CAP,
S/M
2400pf,
1%
R474
131-00153-0023
RES,
F/C
15Kolj4W
5%
R491
135-00123-0012
RES,
M/F
12Ko1/4W
5%
R494
133-00113-0015
RES,
VAR
2Ko
1W
R495
135-00123-0012
RES,
M/F
12Ko1j4W
5%
Using
the procedure in the
KT
76/78
Maintenance
Overhaul
Manual
align the
mode
A one-shots
at
TP403
and
TP404
for 8.6 pS
+/-
0.1
pS.
Align
the
mode
C
one-
shots at
TP405
and
TP406
for
21.6
pS
+/-
0.1
ps~
These
adjustments
should
be
smooth,
if
they are
erratic,
clean or replace the
variable
resistors
as
necessary.
Date:
Oct/93
P/N
601-01340-0020
SA
KT
76/
KT
78-102
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