TM 1-1520-240-MTF
4-54
c. Check light operation high and low
sensitivity over appropriate markers.
8. Transponder AN/APX-100 and Radar Signal
Detecting Set AN/APR-39.
a. Transponder master switch — STBY. Allow
2 minutes for warmup. Check CODE OFF
flag on pilot’s barometric altimeter out of
sight.
b. At a minimum altitude of 2,000 feet and
distance of 30 miles, request a transponder
check from an appropriate radar facility.
c. Check all modes, including emergency.
Check AIMS altimeter.
d. Obtain operation information from radar
facility.
e. While
checking
transponder,
check
operation of radar signal detecting set.
Check that detecting set displays bearing to
all known radar facilities.
9. Doppler Navigation Set (AN/ASN-128).
a. Verify proper system operation with MODE
switch at TEST and display indicates GO.
(1) Fly helicopter over surveyed test
course (figure 4-1) at cruise airspeeds.
The altitude should be low enough to
minimize error in establishing position
over checkpoints.
(2) Enter magnetic variations, lateral and
longitudinal
coordinates
of
the
checkpoints.
