EQUIPMENT REQUIRED BUT NOT
This section contains detailed list-
Table 2-3 lists equipment/compo-
ings of the characteristics and capabilities
nents which are required for maintenance
of the Transponder Set Test Set AN/Al?M-
or calibration of the Transponder Set Test
378. Tables of equipment supplied, and
Set AN/APM-378, but which are not sup-
euipment required but not supplied are part
plied as part of the test set.
of this section. Principles of operation,
functional operation, and operating informa-
PRINCIPLE S OF OPERATION.
tion are also contained in this section.
EQUIPMENT DESCRIPTION AND
2-11. Figure 2-2 shows the basic rela-
tionship of the test set to the transponder
being checked. The test set transmits
The AN/APM-378 test set is a por-
interrogation pulses to the aircraft trans-
table accept/reject tester, housed in a rug-
ged combination case. A detachable cover of
or via direct-connected rf cables). If it
the case, in addition to protecting the controls
is operating correctly, the transponder
and indicators of the test set, contains the
produces reply pulses and transmits them
accessory cables, and the antenna assembly.
back to the test set. Internal circuits of
Power for the test set is obtained from 115
the test set then check the received replies
V ac or 28 V dc power sources at the flight-
for proper pulse spacing/presence/absence,
line locations where the test set is employed.
etc. For each check made by the test set,
Figure 2-1 shows the overall view of AN/
an ACCEPT or REJECT indication is
APM-378 test set.
given to indicate acceptable or unaccept-
able operation of the aircraft transponder.
Table 2-1 lists the characteristics
and capabilities of the AN/APM-378. The
2-12. When making Mode 4 tests, the test
test set (completely solid state) employs
set generates a pretrigger, which is applied
strip-line rf circuits and integrated-
to the Interrogator Computer KIR-1A. The
circuits to provide maximum ruggedness
KIR-1A responds with a Mode 4 Interroga-
and highest reliability. Built-in self-test
tion Video Word, which modulates the test
circuits determine the test set operational
set transmitter, The resulting Mode 4
readiness, prior to testing of transponders.
interrogation is sent to the transponder,
Controls and indicators of the test set have
which applies it to the associated IFF com-
been designed for simplicity of operation,
puter equipment. If the coding is correct
and can be correctly manipulated even by
the transponder replies to the test set. The
oerators wearing arctic gloves.
resulting signals in the test set are then
applied to the KIR-1A as Reply Video, which
generates a TDV signal. This TDV signal,
and a GTC pulse are fed from the KIR-1A
Table 2-2 lists the equipment and
to the test set; both signals must occur co-
incidently in order to generate an ACCEPT
components supplied as part of the Trans -
indication in the test set.
ponder Set Test Set AN/APM-378.